reference zirconium hydride reactor thermoelectric …

AI-AEC-MEMO-12717

REFERENCE ZIRCONIUM HYDRIDE REACTOR

THERMOELECTRIC SYSTEM

- L E G A L N O T I C E -Tliis report was prepared as an account of worlc sponsored by the United States Government. Neither the United States nor the United States Atomic Energy Commission, nor any of their employees, nor any of "their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights.

ATOMICS INTERJIATIONAL A DIVISION OF NORTH AMERICAN ROCKWELL CORPORATION

JUNE 15, 1969 •»TSTRmUTTON OP THIS noCTTMKNT KS UNf IMTTEB

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.

CONTENTS

P a g e

I. I n t roduc t i on 11

II. S u m m a r y 13

A. R e f e r e n c e S y s t e m 13

B. P o w e r p l a n t for O r b i t a l W o r k s h o p 15

C. L u n a r B a s e and Manned Orb i t i ng R e s e a r c h L a b o r a t o r y

(MORL) P o w e r p l a n t s 16

III. R e f e r e n c e S y s t e m , 17

A. S y s t e m D e s c r i p t i o n 17

B. S y s t e m P e r f o r m a n c e 22

1. R e f e r e n c e O p e r a t i n g Cond i t i ons 22

2. Of f -Des ign P e r f o r m a n c e 25

3. P a r t i a l - P o w e r P e r f o r m a n c e 29

C. S y s t e m O p e r a t i o n 29

1. S t a r t u p 30

2. Shutdown 35

D. R e l i a b i l i t y 35

1, S y s t e m R e l i a b i l i t y 37

2. B a s e s for E s t i m a t e s 37

E . S y s t e m T r a d e - o f f s 48

IV. S u b s y s t e m s 57

A. R e a c t o r / S h i e l d A s s e m b l y 57

1. T e c h n o l o g y Sta tus 57

2. R e a c t o r S u b s y s t e m D e s c r i p t i o n and P e r f o r m a n c e 57

B. T h e r m o e l e c t r i c C o n v e r t e r 63

1. TE Module Techno logy S ta tus 63

2. T u b u l a r Module 66

3. C o n v e r t e r Module 71

4. E l e c t r i c a l N e t w o r k and V o l t a g e - R e g u l a t i o n E q u i p m e n t 79

C. N a K - L o o p C o m p o n e n t s 91

1. P u m p S y s t e m 91

2. E x p a n s i o n C o m p e n s a t o r 101

A I - A E C - M E M O - 1 2 7 1 7 3

CONTENTS

P a g e

D. R a d i a t o r 107

1. C o n c e p t Se lec t ion 107

2. R a d i a t o r Des ign 109

M i s s i o n A d a p t a t i o n s 112

A. S a t u r n - V OWS P o w e r p l a n t 112

1. M i s s i o n R e q u i r e m e n t s and I n t e g r a t i o n C o n s i d e r a t i o n s 112

2 . S y s t e m D e s c r i p t i o n 115

3. O p e r a t i o n a l Mode 141

4 . F i n a l R e a c t o r Shutdown and D i s p o s a l 150

B. L u n a r B a s e P o w e r p l a n t 152

1. M i s s i o n R e q u i r e i n e n t s 152

2 . S y s t e m D e s c r i p t i o n and P e r f o r m a n c e 155

3. S u b s y s t e m D e s c r i p t i o n and P e r f o r m a n c e l o l

4 . O p e r a t i o n a l Mode 1^5

5. C o m p a r i s o n wi th P r e v i o u s Des ign 1°^

C. Manned Orb i t i ng R e s e a r c h L a b o r a t o r y P o w e r p l a n t 168

1. M i s s i o n R e q u i r e m e n t s 1"°

2. S y s t e m D e s c r i p t i o n and C o m p a r i s o n wi th P r e v i o u s D e s i g n 168

e r e n c e s 173

175 s s a r y

A I - A E C - M E M O - 1 2 7 1 7 4

TABLES

P a g e

I I - 1 , R e f e r e n c e R e a c t o r — T E S y s t e m Des ign and P e r f o r m a n c e

C h a r a c t e r i s t i c s 14

I I I - l . U n s h i e l d e d S y s t e m Weight B r e a k d o w n 22

I I I -2 . R e f e r e n c e P e r f o r m a n c e C h a r a c t e r i s t i c s 23

I I I - 3 . P a r t i a l - P o w e r P e r f o r m a n c e C h a r a c t e r i s t i c s

( T h r e e Loops O p e r a t i n g ) 28

I I I -4 . R e l i a b i l i t y E s t i m a t e s 39

I I I - 5 . T u b e - W e l d H i s t o r i e s 40

I I I -6 , P o w e r Diode " T h e r b l i g " F a i l u r e - R a t e s 47

I V - 1 . SNAP R e a c t o r O p e r a t i n g E x p e r i e n c e 56

I V - 2 . R e f e r e n c e Z r H R e a c t o r Des ign P a r a m e t e r s 64

I V - 3 . T u b u l a r Module T e s t E x p e r i e n c e 65

I V - 4 . C h a r a c t e r i s t i c s of R e f e r e n c e T u b u l a r Module 69

I V - 5 . C o n v e r t e r Module C h a r a c t e r i s t i c s 73

I V - 6 . P o w e r L o s s e s 90

I V - 7 . P u m p Module S u m m a r y 95

I V - 8 . NaK V o l u m e s 104

I V - 9 . E x p a n s i o n C o m p e n s a t o r C h a r a c t e r i s t i c s 104

I V - 1 0 . T u b e - a n d - F i n R a d i a t o r Des ign C r i t e r i a 108

I V - 1 1 . R e f e r e n c e R a d i a t o r C h a r a c t e r i s t i c s I l l

V - 1 . S a t u r n - V O r b i t a l W o r k s h o p M i s s i o n R e q u i r e m e n t s for N u c l e a r P o w e r S y s t e m 116

V - 2 . S a t u r n - V O r b i t a l W o r k s h o p P o w e r S y s t e m Weight

B r e a k d o w n 125

V - 3 . R a d i a t i o n Dose C r i t e r i a 126

V - 4 . D e n s i t y of Shie ld M a t e r i a l s 131

V - 5 . E s t i m a t e d R a d i a t i o n D o s e r a t e s a t S a t u r n - V O r b i t a l W o r k s h o p

C o m m a n d and C o n t r o l S ta t ion 132

V - 6 . L a u n c h Veh ic l e P a y l o a d E s t i m a t e s 144

V - 7 . Key P o w e r S y s t e m R e q u i r e m e n t s for L u n a r B a s e 153

V - 8 . B a s e l i n e L u n a r P o w e r p l a n t C h a r a c t e r i s t i c s 158

V - 9 . H i g h - P o w e r L u n a r P o w e r p l a n t C h a r a c t e r i s t i c s 162

A I - A E C - M E M O - 1 2 7 1 7 5

TABLES

Page

V-10. Doserate at 0.5 mi from Lunar Base Reactor 164

V-11. Design Compar i son 167

V-12. Key Manned Orbiting Resea rch Labora tory Mission and Reactor Power System Requirements 169

V-13. Mobile Orbiting Resea rch Labora tory System Charac te r i s t i c s . . 171

FIGURES

Front i sp iece . Manned Orbital Workshop with 25-kw Reactor — Thermoe lec t r i c Power System 10

I I I - l . Reference 25-kwe System Schematic 17

III-2. ZrH Reactor — Thermoelec t r i c System, Reac to r /Ga l l e ry Ar rangement 20

III-3, System Per fo rmance vs Load Voltage, Reactor-Out le t Tempera tu re = 1246°F 24

III-4. System Elec t r i ca l Cha rac t e r i s t i c s vs Reactor-Out le t Tempera tu re 26

III-5, Effect of Reactor-Out le t Tempera tu re on System Power ,

Voltage = 56 volts 27

III-6. SNAP lOA Startup in Orbit 32

III-7. System Shutdown Trans ien t s , NaK Tempera tu re s -24«^/min. . . . 34

III-8. System Shutdown Trans ien ts , Power and Rate of Tempera ture

Change -24^/min 34

III-9. System Reliabil i ty, 10,000-hr Duration 36

III-10. System Reliabil i ty, 20,000-hr Duration 38

III-11. Thermoelec t r i c Conver ter Full-and Par t i a l -Power

Reliabil i ty (Elect r ica l ) 46

III-12. Radiator Fin Effectiveness 50

III-13. 15-kwe System Weight and Area 50



III-16. 25-kwe System, 1250°F Reactor-Outlet Tempera tu re 52

III-17. 15-kwe System Weight and Area (Unshielded) 52

AI-AEC-MEMO-12717 6

FIGURES

9 Page

I I I - 1 8 . 2 5 - k w e S y s t e m Weight and A r e a (Unsh ie lded) 53

I I I - 1 9 . 35-kwe S y s t e m Weight and A r e a (Unsh ie lded) 53

I I I -20 . S y s t e m M i n i m u m Weight 54

I I I - 2 1 . S y s t e m R a d i a t o r A r e a , M i n i m u m - W e i g h t S y s t e m s 54

I I I -22 . R e a c t o r T h e r m a l P o w e r , M i n i m u m - W e i g h t S y s t e m s 55

I V - 1 . SNAP 8 D e v e l o p m e n t R e a c t o r G r o u n d T e s t A s s e m b l y 58

I V - 2 . Z i r c o n i u m H y d r i d e R e a c t o r , R e f e r e n c e Des ign 59

I V - 3 . P e r f o r m a n c e E n v e l o p e , R e f e r e n c e Z r H R e a c t o r 60

I V - 4 . Z r H R e a c t o r R e f e r e n c e Des ign 60

I V - 5 . T u b u l a r T h e r m o e l e c t r i c Module 65

I V - 6 . C o n v e r t e r Layout 67

I V - 7 . C o n v e r t e r Module C u t a w a y 72

I V - 8 . C o n v e r t e r Module Layout 75

I V - 9 . Double C o n t a i n m e n t of C o n v e r t e r Module H e a d e r 78

I V - 1 0 . C o n v e r t e r Module Of f -Des ign P o w e r 80

' I V - 1 1 . C o n v e r t e r Module Off -Des ign Ef f ic iency 81

I V - 1 2 . C o n v e r t e r Module Off -Des ign Vol tage 82

I V - 1 3 . C o n v e r t e r Module Off -Des ign F l o w r a t e s , Axia l A T ' S A s s u m e d C o n s t a n t a t 2 0 0 ° F 83

I V - 1 4 . C o n v e r t e r Module Of f -Des ign F l o w r a t e s , Axia l A T ' S

A s s u m e d C o n s t a n t a t 150°F 84

I V - 1 5 . C o n v e r t e r Module Ho t - and C o l d - S i d e P r e s s u r e D r o p s 85

I V - 1 6 . C o n v e r t e r - A s s e m b l y and P o w e r - C o n d i t i o n i n g C i r c u i t

D i a g r a m 86

I V - 1 7 . V o l t a g e - C u r r e n t P r o f i l e 87

I V - 1 8 . M e r c u r y - R a n k i n e P r o g r a m I n t e g r a l S o u r c e P u m p 92

I V - 1 9 . SNAP lOA I n t e g r a l S o u r c e P u m p 92

I V - 2 0 . P u m p C o n v e r t e r 94

I V - 2 1 . P r i m a r y and H e a t - R e j e c t i o n Loop E l e c t r o m a g n e t i c - P u m p

A s s e m b l y 96

I V - 2 2 . P u m p A s s e m b l y , S e p a r a t e S o u r c e , T h r e e - T h r o a t 99

I V - 2 3 . R e f e r e n c e P u m p P e r f o r m a n c e 102

I V - 2 4 . SNAP lOA E x p a n s i o n C o m p e n s a t o r 103

A I - A E C - M E M O - 1 2 7 1 7 7

FIGURES

P a g e

I V - 2 5 . E x p a n s i o n C o m p e n s a t o r , 2 5 - k w e N u c l e a r T h e r m o e l e c t r i c

P o w e r Supply 105

I V - 2 6 , E x p a n s i o n - C o m p e n s a t o r P r e s s u r e C h a r a c t e r i s t i c s 106

I V - 2 7 . C y l i n d r i c a l - R a d i a t o r Weight C h a r a c t e r i s t i c s 110

V - 1 . 2 5 - k w e N u c l e a r T h e r m o e l e c t r i c P o w e r Supply 117

V - 2 . S a t u r n - V O r b i t a l W o r k s h o p wi th 25 -kwe N u c l e a r T h e r m o e l e c t r i c P o w e r Supply 119

V - 3 . A c t u a t o r , N u c l e a r T h e r m o e l e c t r i c P o w e r Supply,

S a t u r n - I V B O r b i t a l W o r k s h o p 123

V-4 . R a d i a t i o n Shie ld Des ign C r i t e r i a 127

V - 5 . 477 Shie ld Out l ine , R e f e r e n c e Des ign 128

V - 6 . Shadow Shie ld Out l ine , R e f e r e n c e Des i gn 130

V - 7 . 25 -kwe N u c l e a r T h e r m o e l e c t r i c P o w e r Supply, T w o - L o o p S y s t e m 134

V - 8 . T h e r m o e l e c t r i c P o w e r P a c k a g e wi th Modif ied P o r t

L o c a t i o n s 135

V - 9 . P r e a s s e m b l e d R a d i a t o r A s s e m b l y I n t e g r a t i o n De ta i l s 138

V - 1 0 . P o w e r S y s t e m Loadpa th S c h e m a t i c 139 V - 1 1 . I n t e g r a l S a t u r n - V Launch C o n f i g u r a t i o n , N u c l e a r T h e r m o

e l e c t r i c P o w e r S y s t e m 140

V - 1 2 . S e p a r a t e Launch Conf igu ra t i on , S a t u r n - I B S e r v i c e Module 142

V - 1 3 . S e p a r a t e L a u n c h Conf igu ra t i on , T i t an III T r a n s t a g e 144

V - 1 4 . S a t u r n - I V B P o w e r S y s t e m C o n t r o l Logic 146

V - 1 5 . S a t u r n - I V B O r b i t a l W o r k s h o p P o w e r - S y s t e m S t a r t u p 148

V - 1 6 . 2 5 - k w e N u c l e a r T h e r m o e l e c t r i c P o w e r Supply L u n a r B a s e

A p p l i c a t i o n 156

V - 1 7 . L u n a r B a s e P o w e r Supply Des ign A l t e r n a t e s 157

V - 1 8 . R e a c t o r Shie ld ing and S t r u c t u r e , L u n a r B a s e Concep tua l 160 V - 1 9 . 25 -kwe N u c l e a r T h e r m o e l e c t r i c P o w e r Supply, Manned

O r b i t i n g R e s e a r c h L a b o r a t o r y 170

A I - A E C - M E M O - 1 2 7 1 7 8

• ''* , *,s* . •••• -1

- J 3 - 0 9 9 - 3 5

F r o n t i s p i e c e . Manned O r b i t a l W o r k s h o p wi th 25 -kw R e a c t o r — T h e r m o e l e c t r i c P o w e r S y s t e m

A I - A E C - M E M O - 1 2 7 1 7 10

I. INTRODUCTION

This r e p o r t p r e s e n t s the r e s u l t s of a n i n e - m o n t h e n g i n e e r i n g s tudy of n u

c l e a r r e a c t o r — t h e r m o e l e c t r i c (TE) power s y s t e m s . This g e n e r a l type of

s p a c e p o w e r s y s t e m i s not new; a 5 0 0 - w a t t (SNAP lOA) r e a c t o r — T E s y s t e m

w a s f l i g h t - t e s t e d in s p a c e in 1965. Since tha t t i m e s ign i f ican t t e c h n o l o g i c a l

a d v a n c e s have b e e n m a d e w i th SNAP ( z i r c o n i u m h y d r i d e type) r e a c t o r s and

wi th TE c o n v e r t e r s . A s of th i s w r i t i n g the l a t e s t of a s e r i e s of SNAP r e a c

t o r s (SNAP 8) h a s j u s t gone c r i t i c a l and i s e n t e r i n g a t e s t p r o g r a m a i m e d at

d e m o n s t r a t i n g o v e r 10,000 h r of o p e r a t i o n at 600 kwt, 1300°F . S i m i l a r l y the

t u b u l a r l e a d - t e l l u r i d e T E c o n v e r t e r s be ing deve loped for the AEC by W e s t i n g -

h o u s e A s t r o n u c l e a r L a b o r a t o r i e s (WANL) have d e m o n s t r a t e d e f f ic ienc ies 3 to

4 t i m e s h i g h e r than t h o s e u s e d in the SNAP lOA s y s t e m . The f ab r i ca t i on

p r o c e s s e s for t h i s c o n v e r t e r m o d u l e have a l s o been deve loped to y ie ld good

r e p r o d u c i b l e r e s u l t s , and e n d u r a n c e t e s t i n g h a s e x c e e d e d 20,000 h r .

T h e s e a d v a n c e s , t o g e t h e r wi th the r e s u l t s of s e v e r a l jo in t NASA/AEC a p

p l i ca t i on s t u d i e s , have m a d e it a p p a r e n t tha t r e a c t o r — TE power s y s t e m s u t i

l i z ing the c o m p o n e n t s deve loped to da te would be a t t r a c t i v e c a n d i d a t e s for

s p a c e m i s s i o n s in the 7 0 ' s r e q u i r i n g power l e v e l s up to a p p r o x i m a t e l y 40 kwe .

In l a t e 1967, t h e r e f o r e , the A t o m i c E n e r g y C o m m i s s i o n s t a r t e d t h i s r e a c t o r —

TE s y s t e m s tudy at A t o m i c s I n t e r n a t i o n a l (AI) to b e t t e r define the des ign and

p e r f o r m a n c e c h a r a c t e r i s t i c s of such a s y s t e m .

The g e n e r a l g u i d e l i n e s p r o v i d e d by the AEC for t h i s des ign effort w e r e tha t

the p o w e r s y s t e m shou ld u t i l i z e the r e f e r e n c e z i r c o n i u m h y d r i d e r e a c t o r coupled

to a p o w e r - c o n v e r s i o n s y s t e m (PCS) i n c o r p o r a t i n g l e a d - t e l l u r i d e t ubu l a r TE

m o d u l e s . WANL p e r f o r m e d the d e s i g n and a n a l y s i s w o r k on the TE c o n v e r t e r s

and p o w e r - c o n d i t i o n i n g e q u i p m e n t u n d e r s u b c o n t r a c t to AI.

Add i t i ona l o b j e c t i v e s se t for th i s s tudy a r e a s fo l lows:

1) E s t a b l i s h a c o n c e p t u a l d e s i g n of a r e f e r e n c e s y s t e m su i t ab le for

adap t ion to e i t h e r m a n n e d o r u n m a n n e d s p a c e m i s s i o n s wi th a n o m i n a l

power l e v e l of 25 kwe and a m i n i m u m l i f e t ime of 20,000 h r .

2) P r e p a r e p a r a m e t r i c p e r f o r m a n c e da ta o v e r a su i t ab le power r a n g e

above and be low 25 kwe to i l l u s t r a t e the t r a d e - o f f s ava i l ab l e b e t w e e n

p o w e r , we igh t , a r e a , t e m p e r a t u r e , e t c .

A I - A E C - M E M O - 1 2 7 1 7 11

3) E s t a b l i s h p r e l i m i n a r y d e s i g n and p e r f o r m a n c e r e q u i r e m e n t s for key

s y s t e m c o m p o n e n t s to s e r v e a s a guide for ongoing a n d / o r fu ture

d e v e l o p m e n t w o r k .

4) P r e p a r e o r u p d a t e c o n c e p t u a l d e s i g n s of r e a c t o r — TE p o w e r p l a n t s

a d a p t e d for spec i f i c s p a c e m i s s i o n s , inc lud ing m a n n e d o rb i t i ng w o r k

shops and m a n n e d l u n a r b a s e s .

The c o n c e p t u a l d e s i g n for a r e f e r e n c e z i r c o n i u m h y d r i d e r e a c t o r s u b s y s t e m

s u i t a b l e for u s e wi th T E or o t h e r P C S ' s w a s a l s o to be e s t a b l i s h e d p a r a l l e l wi th

the above s y s t e m e n g i n e e r i n g w o r k .

The r e s u l t s of the r e a c t o r — T E s y s t e m e n g i n e e r i n g effor t a r e p r e s e n t e d in

t h i s r e p o r t , in the s a m e o r d e r a s the o b j e c t i v e s l i s t e d a b o v e . De t a i l s of the

r e f e r e n c e z i r c o n i u m h y d r i d e r e a c t o r d e s i g n a r e g iven in a c o m p a n i o n docu-^ (1 )* m e n t .

The w o r k r e p o r t e d h e r e i n w a s p e r f o r m e d for the USAEC u n d e r C o n t r a c t No.

A T ( 0 4 - 3 ) - 7 0 1 , and w a s c o m p l e t e d in June 1968.

' ^Superscr ip t n u m b e r s in p a r e n t h e s e s a r e for R e f e r e n c e s a t the b a c k of th i s r e p o r t .

A I - A E C - M E M O - 1 2 7 1 7 12

II. SUMMARY

A. R E F E R E N C E SYSTEM

The r e f e r e n c e 2 5 - k w e r e a c t o r — TE s y s t e m d e s i g n evolved in th i s s tudy con

s i s t s of the z i r c o n i u m h y d r i d e r e a c t o r coupled by the p r i m a r y - c o o l a n t loop to

four p a r a l l e l p o w e r - c o n v e r s i o n s e c t i o n s . The r e a c t o r des ign i s s i m i l a r to the

SNAP 8 r e a c t o r but h a s a s l i gh t l y l a r g e r c o r e and an i n t e r n a l l y cooled BeO r e

f l e c t o r s u i t a b l e for o p e r a t i o n wi th in an e n c l o s e d sh ie ld . T h e s e mod i f i ca t i ons

a r e d e s i r a b l e for m a n n e d s p a c e a p p l i c a t i o n s .

E a c h of the four p o w e r - c o n v e r s i o n s e c t i o n s i nc ludes a TE c o n v e r t e r a s s e m

bly , a NaK p u m p , and a h e a t - r e j e c t i o n loop (HRL). E a c h c o n v e r t e r a s s e m b l y

c o n t a i n s 24 TE t u b u l a r m o d u l e s s t r u c t u r a l l y s u p p o r t e d wi th in a r e c t a n g u l a r box

and i n t e r c o n n e c t e d wi th coo lan t m a n i f o l d s for p r o p e r flow d i s t r i b u t i o n of the hot

p r i m a r y loop and the co ld H R L ' s . The t u b u l a r m o d u l e s a r e a r r a n g e d in p a r a l l e l

" 4 - p a c k s , " e a c h of w h i c h p r o v i d e s s l igh t ly m o r e than 1 kwe at 56 vo l t s , dc .

B lock ing d iodes a r e u s e d for e a c h 4 - p a c k to i s o l a t e p o s s i b l e s h o r t c i r c u i t s to

g r o u n d .

The NaK p u m p s a r e of the d c - c o n d u c t i o n e l e c t r o m a g n e t i c (EM) type . E a c h

p u m p h a s t h r e e t h r o a t s , two of which p u m p l / 4 t h of the to ta l p r i m a r y - l o o p flow

and the t h i r d t h r o a t p u m p s one of the H R L ' s . A s e p a r a t e TE power pack c o n

s i s t i n g of t h r e e h i g h - c u r r e n t m o d u l e s connec t ed in p a r a l l e l p r o v i d e s the dc

c u r r e n t to e a c h p u m p .

E a c h H R L c o n s i s t s of a r a d i a t o r s ec t i on , an expans ion c o m p e n s a t o r , and

i n t e r c o n n e c t i n g piping and m a n i f o l d s . The r a d i a t o r des ign s e l e c t e d as a r e f e r

ence i s of the c o n v e n t i o n a l f i n - a n d - t u b e t y p e , wi th s t a i n l e s s - s t e e l NaK tubes

d i f fus ion-bonded to a l u m i n u m fins and m e t e o r o i d a r m o r . A l t e r n a t e r a d i a t o r

m a t e r i a l s and c o n c e p t s of fer ing po t en t i a l p e r f o r m a n c e i m p r o v e m e n t s w e r e a l s o

iden t i f i ed . The p o s s i b l e u s e of h e a t - p i p e s for the h e a t - r e j e c t i o n s ide of the

P C S w a s a l s o s tud i ed , but i t i s not now r e c o m m e n d e d due to i n e x p e r i e n c e with

a s u i t a b l e work ing fluid for the t e m p e r a t u r e r a n g e of i n t e r e s t .

A r e f e r e n c e s t a r t u p and c o n t r o l s c h e m e w a s defined which u s e s r e a c t o r -

ou t l e t t e m p e r a t u r e a s the c o n t r o l p a r a m e t e r du r ing s t a r t u p and e l e c t r i c a l

A I - A E C - M E M O - 12717 13

cur ren t output during normal operation. No valves or moving par t s other than

the reac tor control drums a r e requi red . A shunt-type voltage regulator which

diss ipates excess power to space through h igh- t empera tu re r e s i s t ance e lements

was selected for voltage and load control .

The major design and per formance cha rac t e r i s t i c s for the reference r e a c

tor — TE sys tem a r e summar ized in Table I I - 1 . The reac tor the rmal power

and coolant-outlet t empera tu re a r e well within the capabil i t ies of the reference

ZrH reac to r , and provide adequate marg ins for rel iabi l i ty, power growth, and/o

compensation for possible sys tem degradation. The unshielded sys tem weight

and radia tor a r ea cor respond to a n e a r - m i n i m u m weight design; the a rea can

be reduced at the expense of inc reased weight. The specific weight of approxi-2

mate ly 280 Ib/kwe and specific a rea of 56 ft /kwe rep resen t a significant i m provement over previous des igns .

TABLE II-1

REFERENCE REACTOR - THERMOELECTRIC SYSTEM DESIGN AND PERFORMANCE CHARACTERISTICS

Elec t r i ca l power: (gross) (regulated)

Voltage

Reactor t he rma l power

Reac tor -ou t le t t empera tu re

Average rad ia tor t empera tu re

Net efficiency (system)

Unshielded weight

Specific weight

Radiator a r ea

Specific a r ea

Design lifetime

System degradation allowance

25.2 kwe 24.7 kwe

56 volts dc

5 83 kwt

1246°F

563°F

4.24%

7000 lb

280 Ib/kwe

1400 ft2

56 ft^/kwe

20,000 hr

10%

A number of sys t em and component optimization and trade-off studies were

made in the p roces s of a r r iv ing at the re fe rence design descr ibed briefly above.

AI-AEC-MEMO-12717 14

A m o n g t h e s e w e r e (1) the o p t i m i z a t i o n of the c o n v e r t e r m o d u l e d i m e n s i o n s ,

(2) s y s t e m w e i g h t - a r e a - a n d - t e m p e r a t u r e t r a d e - o f f s , (3) eva lua t ion of s e v e r a l

c o n v e r t e r - p a c k a g i n g a l t e r n a t e s , (4) s e v e r a l i t e r a t i o n s on the pump type and

c a p a c i t y , (5) c o m p a r i s o n of two vs t h r e e loops in s e r i e s , (6) r e l i a b i l i t y and

we igh t t r a d e - o f f s for two to e ight p a r a l l e l p o w e r - c o n v e r s i o n loops and H R L ' s ,

(7) d e t e r m i n a t i o n of n e a r - o p t i m u m p r e s s u r e d r o p and AT for both loops ,

(8) r a d i a t o r m a t e r i a l s , tube s i z e , and spac ing o p t i m i z a t i o n , and (9) o v e r a l l

s y s t e m r e l i a b i l i t y e s t i m a t e s for v a r i o u s s y s t e m con f igu ra t i ons and des ign

a l t e r n a t i v e s .

P a r a m e t r i c s t u d i e s w e r e a l s o p e r f o r m e d to d e t e r m i n e the s y s t e m c h a r

a c t e r i s t i c s at h i g h e r and l o w e r p o w e r l e v e l s , u s ing a c o m p u t e r code deve loped

for th i s p u r p o s e du r ing the s tudy . F r o m 15 to 35 kwe , the u n s h i e l d e d s y s t e m

spec i f i c weight r a n g e s f r o m a p p r o x i m a t e l y 320 to 250 I b / k w e , r e s p e c t i v e l y .

The spec i f i c a r e a for n e a r - m i n i m u m weigh t r e m a i n s in the r a n g e of 56 to 2

60 ft / k w e , and the r e a c t o r t h e r m a l power r a n g e s f r o m 350 to 800 kwt.

B . P O W E R P L A N T F O R O R B I T A L WORKSHOP

Majo r e m p h a s i s in a d a p t i n g the r e f e r e n c e s y s t e m for spec i f ic space m i s

s i o n s w a s p l a c e d on e s t a b l i s h i n g a c o n c e p t u a l p o w e r p l a n t des ign su i t ab le for

i n t e g r a t i o n wi th the S a t u r n - V O r b i t a l W o r k s h o p (OWS) concep t , which i s c u r

r e n t l y be ing s tud i ed by NASA u n d e r the Advanced Apol lo P r o g r a m . The power

s y s t e m des ign i s e s s e n t i a l l y i d e n t i c a l to the r e f e r e n c e s y s t e m excep t that the

r a d i a t o r a r e a h a s b e e n r e d u c e d s l igh t ly a t the e x p e n s e of a s m a l l weight p e n

a l t y , and r a d i a t i o n - s h i e l d d e s i g n s t a i l o r e d for the m i s s i o n have been inc luded .

The f r o n t i s p i e c e to t h i s r e p o r t i l l u s t r a t e s the p o w e r p l a n t - O W S i n t e g r a t i o n

c o n c e p t evo lved a f te r e x a m i n a t i o n of s e v e r a l a l t e r n a t e a p p r o a c h e s . The r e a c t o r

p o w e r s y s t e m i s shown e x t e n d e d in i t s o p e r a t i o n a l pos i t ion ; dur ing launch o r

shutdo'wn p e r i o d s i t v/ould be r e t r a c t e d wi th in the c y l i n d r i c a l s t r u c t u r e wh ich

s e r v e s a s an a e r o d y n a m i c s h r o u d , h e a t sh i e ld , s u p p o r t s t r u c t u r e , and docking

a d a p t o r . The p o w e r p l a n t p a c k a g e i s a t t a c h e d to (and can be d i s c o n n e c t e d f rom)

the f o r w a r d docking p o r t of the m u l t i p l e docking a d a p t o r . The power s y s t e m is

d e s i g n e d so t h a t wi th m i n i m a l m o d i f i c a t i o n s i t can be l aunched i n t e g r a l wi th the

OWS on a t w o - s t a g e S a t u r n - V , o r s e p a r a t e l y u s i n g e i t h e r a T i t a n - I I I F o r

A I - A E C - M E M O - 1 2 7 1 7 15

Saturn- IB/Serv ice Module combination. With the separa te launch an unmanned

rendezvous with the manned OWS would be requi red , using the Transtage or

Service Module for this maneuver .

Both shadow and 477 radia t ion-shie ld designs were examined for an assumed

dose l imit of 20 to 30 r e m / y r , which is small compared to the dose that is ex

pected from na tura l , space radiat ion. The power-convers ion equipment is

located in a compact gal lery within the shield. The shadow- and 477-shield

weight es t imates a r e approximate ly 14,300 and 16,500 lb respect ively, which

br ings the total powerplant weight (including power cables , deployment mech

an i sms , etc . ) to approximate ly 22,300 to 24,500 lb, depending on the shield

type. Thus the total , shielded power sys tem specific weight is approximately

885 to 975 Ib/kwe.

The es t imated payload marg ins available for the separa te launch and r en

dezvous mode (including al lowances for the shroud, rendezvous propellant , etc.)

a re 6700 to 8900 lb with the Ti tan-IIIF, and 1500 to 3800 lb with the Sa turn- IB/

service module. The marg in available for the in tegra l launch mode on a two-

stage Saturn-V depends strongly on the final weight es t imate for the OWS.

End-of-life (EOL) disposal of the r eac to r power sys tem, if requi red for

safety r ea sons , could be accomplished by undocking the powerplant and then

using the manned Command and Service Module's (CSM) propulsion and guid

ance capability to e i ther de-orb i t the reac tor into the ocean or park it in a

higher long-lived orbi t .

C, LUNAR BASE AND MANNED ORBITING RESEARCH LABORATORY (MORL) POWERPLANTS

Two reac tor — TE powerplant designs evolved in previous joint NASA/AEC (2 3) studies ' were updated to incorpora te the design and performance changes

available with the re fe rence sys tem. In both cases significant improvements

were obtained with respec t to sys tem simplification, specific weight, and

specific a r ea . Fo r the lunar base powerplant, for example, it now appears

possible to inc rease the net power from 20.4 to 35.5 kwe, using the same con

s t ra ints and c r i t e r i a es tabl ished in the previous joint study. For the MORL

powerplant the weight and a r ea reductions were 5 and 26% respect ively , the

total number of coolant loops was reduced from 22 to 5, and the r eac to r outlet-

t empera tu re was reduced approximately 50°F.


III. REFERENCE SYSTEM

A. SYSTEM D E S C R I P T I O N

The r e f e r e n c e Z r H r e a c t o r - T E S y s t e m u t i l i z e s the n u c l e a r r e a c t o r d e

s c r i b e d in R e f e r e n c e 1 c o m b i n e d wi th a c o m p a c t P b T e TE c o n v e r t e r c u r r e n t l y

u n d e r d e v e l o p m e n t by W e s t i n g h o u s e to p r o d u c e 25 kw of e l e c t r i c a l p o w e r . The

d e s i g n u s e s two s e t s of h e a t - t r a n s f e r loops in s e r i e s , the p r i m a r y loops and

H R L ' s . A s o d i u m - p o t a s s i u m l i q u i d - m e t a l a l loy (NaK) i s u s e d in both l o o p s .

The a r r a n g e m e n t of loops and c o m p o n e n t s i s shown s c h e m a t i c a l l y in F i g u r e I I I - l ,

De ta i l ed d e s c r i p t i o n s of c o m p o n e n t s a r e p r o v i d e d in subsequen t s e c t i o n s of th i s

r e p o r t .

TO PARALLEL

LOOPS

RADIATOR Q = 138 kwt (551 kwt)

*NUMBERS IN PARENTHESES INDICATE FULL SYSTEM VALUES

' ELECTRICAL LINES 8-A30-075-1A

F i g u r e I I I - l . R e f e r e n c e 25 -kwe S y s t e m S c h e m a t i c

A I - A E C - M E M O - 1 2 7 1 7 17

T h r e e - l o o p s y s t e m s w e r e a l s o c o n s i d e r e d e a r l y i n t h e s tudy . In t h i s a r r a n g e

m e n t an i n t e r m e d i a t e s e t of l oops wi th h e a t e x c h a n g e r s is p l a c e d b e t w e e n the

p r i m a r y and H R L ' s . The i n t e r m e d i a t e h e a t e x c h a n g e r s ( IHX's) a r e s o m e w h a t

m o r e c o m p a c t than the c o m p a c t c o n v e r t e r s , and in o r b i t a l a p p l i c a t i o n s r e q u i r i n g

a sh i e lded g a l l e r y a s m a l l sh i e ld we igh t s av ings m a y thus be ob ta ined . F o r the

c u r r e n t 2 5 - k w e d e s i g n , h o w e v e r , the i n c r e a s e in we igh t c a u s e d by the i n t e r m e

d ia t e loops m o r e than of f se t s the s h i e l d - w e i g h t s a v i n g s . F o r t h e s e r e a s o n s and

b e c a u s e the t w o - l o o p a r r a n g e m e n t i s a l s o l e s s c o m p l e x and m o r e r e l i a b l e i t w a s

s e l e c t e d . Any f u r t h e r g r o w t h of the s y s t e m to u s e m o r e of the r e a c t o r ' s power

c a p a b i l i t y (>1200 kwt) , h o w e v e r , could r e s u l t in a t h r e e - l o o p a r r a n g e m e n t be ing

o p t i m u m .

The p r i m a r y loops t r a n s p o r t NaK, h e a t e d to 1246 °F in the r e a c t o r , to the

hot s ide of the TE t u b u l a r m o d u l e s . NaK c i r c u l a t i n g in the H R L ' s p r o v i d e s the

5 7 3 ° F a v e r a g e cold junc t ion of the m o d u l e s and t r a n s p o r t s the r e j e c t e d hea t to

r a d i a t o r s . The s a m e s c h e m a t i c a r r a n g e m e n t and s y s t e m c o m p o n e n t s a r e u s e d

in c o m m o n for s e v e r a l d i f f e ren t m i s s i o n a d a p t a t i o n s . As d e s c r i b e d l a t e r in th i s

r e p o r t , the m i s s i o n a d a p t a t i o n s , excep t for the r a d i a t o r and sh ie ld , a r e p r i

m a r i l y c o n f i g u r a t i o n a l c h a n g e s .

The P C S u t i l i z e s four c o m p a c t c o n v e r t e r s e a c h hav ing an independen t H R L .

F o u r p a r a l l e l loops a r e a l s o u s e d in the p r i m a r y s y s t e m to s impl i fy i n t e g r a t i o n .

The p r i m a r y loops a r e not h y d r a u l i c a l l y i ndependen t , a s they s h a r e the r e a c t o r

v e s s e l in c o m m o n .

The s e l e c t i o n of four p a r a l l e l loops w a s b a s e d on a t r a d e - o f f b e t w e e n weigh t ,

p a r t i a l - p o w e r (one loop out) p e r f o r m a n c e , c o m p l e x i t y , and r e l i a b i l i t y . The

p e n a l t y in going f r o m two to four loops w a s 150 lb; f r o m four to s ix w a s 200.

The p a r t i a l - p o w e r c a p a b i l i t y in a f o u r - l o o p s y s t e m is 80% of n o r m a l power a s

suming tha t the r e a c t o r - o u t l e t t e m p e r a t u r e is i n c r e a s e d to i t s full 1300°F c a p a

b i l i ty to p r o v i d e p a r t i a l c o m p e n s a t i o n for l o s s of the loop . Th i s i n c l u d e s the

p e n a l t y of flow r e v e r s a l t h r o u g h the i n a c t i v e NaK p u m p r e s u l t i n g f r o m the p o s t u

l a t ed loop f a i l u r e . (F low c h e c k v a l v e s for th i s a p p l i c a t i o n w e r e exc luded by r e

l i a b i l i t y c o n s i d e r a t i o n s . ) F o r l e s s than four i n s t a l l e d loops the p a r t i a l - p o w e r

c a p a b i l i t y fel l to a l e v e l c o n s i d e r e d to be u n a c c e p t a b l e for the p r o b a b l e r e q u i r e

m e n t s for m o s t m i s s i o n s . An i n c r e a s e to m a n y m o r e than four l o o p s , wi th the

A I - A E C - M E M O - 1 2 7 1 7 18

added c o m p l e x i t y and r e d u c e d r e l i a b i l i t y for fu l l -power o p e r a t i o n , could not be

j u s t i f i ed on the b a s i s of the s m a l l i n c r e a s e in p a r t i a l - p o w e r capab i l i t y . F o u r

loops w a s c o n s i d e r e d the b e s t c o m p r o m i s e for a t y p i c a l app l i ca t ion at the d e s i g

n a t e d p o w e r l e v e l . With the c o m p o n e n t s s i zed for th i s s y s t e m , c o n s i d e r a b l e

g r o w t h can be a c c o m p l i s h e d by adding p a r a l l e l loops wi thou t s e v e r e l y c o m p l i

ca t ing the s y s t e m .

E a c h of the four c o m p a c t c o n v e r t e r s c o n s i s t s of 24 t ubu l a r TE m o d u l e s .

They a r e p l aced in a f o u r - b y - s i x a r r a y ; each se t of four i s connec ted in s e r i e s

e l e c t r i c a l l y for a 56 -vdc e l e c t r i c a l ou tput . All m o d u l e s a r e h y d r a u l i c a l l y in

p a r a l l e l . In the r e f e r e n c e d e s i g n the o v e r a l l s y s t e m ef f ic iency i s 4.24%.

The NaK p u m p s u s e d in the r e f e r e n c e s y s t e m a r e the EM type u t i l i z ing a

s e p a r a t e T E p o w e r supp ly . One p u m p i s u s e d in e a c h of the four s y s t e m quad

r a n t s . E a c h p u m p h a s t h r e e t h r o a t s wi th in the s a m e m a g n e t f r a m e . Two t h r o a t s

a r e c o n n e c t e d h y d r a u l i c a l l y in s e r i e s to m e e t the p r i m a r y - l o o p flow r e q u i r e

m e n t . The t h i r d t h r o a t p r o v i d e s pumping of a H R L , The t h r e e pump t h r o a t s

a r e c o n n e c t e d in s e r i e s e l e c t r i c a l l y to a s p e c i a l t h r e e - m o d u l e TE power supply

hav ing a 2 2 0 - m v 1 5 0 0 - a m p output . The power supp l i e s a r e m o u n t e d d i r e c t l y

on the p u m p f r a m e s .

A to t a l of e ight NaK e x p a n s i o n c o m p e n s a t o r s is u s e d in the s y s t e m . F o u r

a r e u s e d in the p r i m a r y s y s t e m and one in e a c h of the four H R L ' s , All un i t s

a r e i d e n t i c a l , of the d o u b l e - s e a l e d g a s - b a c k e d be l lows type , wi th a vo lume 3

change c a p a c i t y of 0,15 ft , T h e y m a i n t a i n the s y s t e m p r e s s u r e s a t 20 p s i a

u n d e r n o m i n a l o p e r a t i n g c o n d i t i o n s .

The r a d i a t o r s t r u c t u r e and sh i e ld ing r e q u i r e m e n t s for the s y s t e m a r e d e

p e n d e n t to a c o n s i d e r a b l e ex t en t on the m i s s i o n a d a p t a t i o n . T r a d e s tud i e s con

s i d e r i n g h e a t - r e j e c t i o n t e m p e r a t u r e , TE p e r f o r m a n c e , r a d i a t o r a r e a , and s y s

t e m w e i g h t r e s u l t e d in the s e l e c t i o n of 5 7 0 ° F a v e r a g e h e a t - r e j e c t i o n t e m p e r a t u r e 2

and 1400 ft of r a d i a t o r a s n e a r - o p t i m u m v a l u e s .

The r a d i a t o r m a y be d e s i g n e d in a n u m b e r of ways inc luding finned tubes or

h e a t p i p e s . The r a d i a t o r s m a y a l s o be f ixed o r folding depending on v e h i c l e -

i n t e g r a t i o n c o n s t r a i n t s and o the r c o n s i d e r a t i o n s , A t y p i c a l des ign adopted for

the S a t u r n - V OWS a p p l i c a t i o n c o n s i s t s of a fixed 1 2 - f t - d i a m s t r u c t u r e to which

A I - A E C - M E M O - 1 2 7 1 7

19

REACTOR

PUMP TE CONVERTER

ELECTROMAGNETIC PUMP

CONTROL DRUM ACTUATORS

Lj.^MAIN TE CONVERTER

EXPANSION COMPENSATOR

j j PRIMARY LOOP ~~~.,

%^'^\ HEAT-REJECTION LOOP

Figure III-2. ZrH Reactor — Thermoe lec t r i c System, Reac to r /Ga l l e ry Ar rangement

8-MA21-07S-6

AI-AEC-MEMO- 12717 20

a r e a t t a c h e d 96 3 / 8 - i n . - d i a m NaK t u b e s . A l u m i n u m fins wi th i n t e g r a l m e t e o r o i d

a r m o r a r e d i f fus ion-bonded to the s t a i n l e s s - s t e e l t u b e s . E a c h H R L p r o v i d e s

NaK to one q u a d r a n t of the r a d i a t o r c y l i n d e r . E a c h q u a d r a n t in t u r n i s d iv ided

into t h r e e p a r a l l e l f lowpaths by m e a n s of h e a d e r s and i n t e r c o n n e c t i n g piping to

m a i n t a i n the r a d i a t o r p r e s s u r e d r o p to a low v a l u e . The s u p p o r t s t r u c t u r e for

the f inned t u b e s is a 0 . 0 1 0 - i n . - t h i c k Ti s h e l l - a n d - s t r i n g e r s t r u c t u r e wi th i n t e r

na l f r a m e s s p a c e d a t an a v e r a g e of 3-ft i n t e r v a l s . Th i s r a d i a t o r des ign concep t

i s u s e d for the we igh t s u m m a r y p r o v i d e d l a t e r .

The sh i e ld s t r u c t u r e , l i ke the r a d i a t o r , v a r i e s wi th m i s s i o n adap t a t i on .

F u n d a m e n t a l l y , the r e f e r e n c e d e s i g n c o n s i s t s of a m o I t e n - P b g a m m a sh ie ld

( e n c a p s u l a t e d in a s t e e l c o n t a i n e r ) i m m e d i a t e l y s u r r o u n d i n g the r e a c t o r , fol

lowed by a LiH n e u t r o n sh i e ld . I n t e r n a l h e a t g e n e r a t i o n in the Pb g a m m a sh ie ld

i s r a d i a t e d to the r e a c t o r v e s s e l . The p r i m a r y - l o o p c o m p o n e n t s conta in r a d i o

a c t i v e NaK and a r e s a n d w i c h e d b e t w e e n the p r i m a r y r e a c t o r sh ie ld and s e c o n d a r y

s h i e l d i n g . In a t y p i c a l m a n n e d a p p l i c a t i o n the s e c o n d a r y sh ie ld c o n s i s t s of a

d e p l e t e d u r a n i u m g a m m a sh i e ld followed by add i t iona l LiH n e u t r o n sh ie ld ing .

D e s c r i p t i o n s of d e s i g n s for spec i f i c m i s s i o n s a r e p r o v i d e d in Sec t ion V of th is

r e p o r t . G e n e r a l sh ie ld ing r e q u i r e m e n t s , r e a c t o r / s h i e l d i n t e g r a t i o n , and s h i e l d

ing t e c h n o l o g y s t a t u s a r e d i s c u s s e d in R e f e r e n c e 1.

The b a s i c r e a c t o r and g a l l e r y a r r a n g e m e n t i s shown in F i g u r e I I I -2 , The

p r i m a r y - l o o p e x p a n s i o n c o m p e n s a t o r s , the four s y s t e m p u m p s with power s u p

p l i e s , and the TE c o n v e r t e r s a r e l o c a t e d in the g a l l e r y r e g i o n be tween the p r i

m a r y and s e c o n d a r y s h i e l d s . The c o m p o n e n t s a r e a r r a n g e d s y m m e t r i c a l l y about

the s y s t e m c e n t e r l i n e . In the con f igu ra t i on shown, the r e a c t o r is sh ie lded on

a l l s i d e s to p r o v i d e sh i e ld ing for veh i c l e r e n d e z v o u s m a n e u v e r s . The r e a c t o r

c o n t r o l - d r u m a c t u a t o r s a r e l o c a t e d ou t s ide the r e a c t o r sh i e ld . In the lunar b a s e

a d a p t a t i o n the e q u i p m e n t a r r a n g e m e n t i s v e r y s i m i l a r . In th i s c a s e , h o w e v e r ,

it i s a d v a n t a g e o u s to i n v e r t the whole a s s e m b l y to p l a c e the c o n t r o l - d r u m d r i v e s

be low and the g a l l e r y c o m p o n e n t s above the r e a c t o r .

2 An u n s h i e l d e d s y s t e m we igh t b r e a k d o w n i s shown in Table I I I - l . The 1400 ft

f i x e d - f i n n e d - t u b e r a d i a t o r i s inc luded for i l l u s t r a t i o n . Shie lded s y s t e m we igh t s

a r e g iven in Sec t ion V for spec i f i c m i s s i o n a d a p t a t i o n s .

A I - A E C - M E M O - 1 2 7 1 7 21

TABLE III - l

UNSHIELDED SYSTEM WEIGHT BREAKDOWN

System Component

Reactor

P r i m a r y - l o o p piping

Pumps

Expansion compensa tors

Thermoe lec t r i c conver te r s

Gal lery s t ruc tu re

Instrumentat ion, control , and regulation

Subtotal

Radiator

Piping

Radiator and s t ruc ture

Subtotal

System Total

Weight (lb)

1422

100

440

208

1135

120

340

3765

661

2580

3241

7006

B. SYSTEM PERFORMANCE

The s teady-s ta te per formance of a r eac to r — TE sys tem is ext remely stable.

Because of the re la t ive ly high radia tor t e rape ra tu re , var ia t ions in the sink t em

pera tu re due to night and day variat ions a r e insignificant.

1. Reference Operating Conditions

Table II1-2 gives the performance cha rac t e r i s t i c s of this sys tem when

operating at the re fe rence conditions. The regulated power of 24.7 kwe is 2%

less than the gross power output due to losses in the voltage regulation equip

ment . The lifetime objective for the plant is 20,000 hr; however, the sys tem

has no cha rac t e r i s t i c s that definitely limit i ts l ifet ime. Operation well beyond

20,000 hr could be accomplished at only a slightly lower rel iabi l i ty level.


TABLE III-2

REFERENCE PERFORMANCE CHARACTERISTICS

E l e c t r i c p o w e r , kwe:

G r o s s

R e g u l a t e d

V o l t a g e , v o l t s :

S y s t e m

T h e r m o e l e c t r i c t u b u l a r m o d u l e

L i f e t i m e , h r

T h e r m a l - p o w e r b a l a n c e , kwt:

R e a c t o r

P r i m a r y - l o o p l o s s e s

C o n v e r t e r s

P u m p c o n v e r t e r s

R a d i a t o r

G r o s s e l e c t r i c a l p o w e r

H y d r a u l i c power (adds to loop l o s s e s )

T e m p e r a t u r e s , ° F

R e a c t o r NaK

C o n v e r t e r , h o t - c l a d

C o n v e r t e r , c o l d - c l a d

R a d i a t o r NaK

E f f i c i e n c i e s , %

S y s t e m

C o n v e r t e r

C o n v e r t e r C a r n o t

H y d r a u l i c s

582.4

- 5 . 0

577.4

539.0

38,4

577,4

In le t A v e r a g e Out le t

P r i m a r y loops

H e a t - r e j e c t i o n loops

25,2

24.7

56.0

14.0

20,000

551.0

25.2

1.2

577.4

1044

1225

470

663

Total F lowra te , l b / s e c

13.0

12.4

1145 1246

1125 1025

570 670

563 463

P r e s s u r e Drop, psi

3,35

1,50

4.24

4.67

35.0

A I - A E C - M E M O - 1 2 7 1 7 23

32

1-13-69 UNC

48 64 80 LOAD VOLTAGE, volts

96 112

I I -

7759-5265

Figure III-3. System Per fo rmance vs Load Voltage, Reactor-Out le t Tempera tu re - 1246°F

AI-AEC -MEMO- 1 271 7 24

Figure III-3 shows how system performance var ies with changes in load

voltage, for a constant r eac to r -ou t l e t t empera tu re of 1246 °F, As the load

voltage inc reases the cu r r en t d e c r e a s e s , and because the effective thermal

conductance of the conver te r var ies with the cur ren t , the hot-to-cold-junction

A T i n c r e a s e s . The hot-junction t empera tu re i nc r ea se s and the cold junction's

d e c r e a s e s , with the la t ter resul t ing in reduced reac tor power.

These specific per formance curves resul ted because the sys tem was de

signed to produce power at nominally 56 vdc. For par t icu lar applications the

TE modules could be wired for any nominal load voltage that is a multiple of

14 vdc,

2, Off-Design Pe r fo rmance

It may be des i rab le to operate the powerplant at off-design conditions for

two r ea sons . F i r s t , degradation in the TE conver ter could be offset by rais ing

the operating t e m p e r a t u r e , or second, the plant could be operated at less than

i ts full power capabili ty if e lec t r ica l power requ i rements a r e projected at a

lower level for an extended period. Lowering the power level would tend to

inc rease the plant l ifetime and rel iabi l i ty because of the reduced t empera tu res

of all components , and would reduce the load requi red to be dumped by the volt

age regula tor . It is expected that changes in e lec t r ica l output of the plant would

be made only when the r equ i rement s were projected differently for a ma t t e r of

weeks.

F igure III-4 shows the e lec t r ica l power output of the system as a function

of load voltage for different reac tor -ou t le t t e m p e r a t u r e s . At the reference de

sign voltage of 56 volts this information can be c ross -p lo t ted to establ ish the

relat ionship between e lec t r i ca l power and outlet t empera tu re , as done in F ig

u re III-5. It should be noted that the the rmal power, also plotted on this figure,

does not vary proport ional ly to e lec t r ica l power. A 40% reduction in e lec t r ica l

power only reduces the the rma l power by 24%, from 5 82 to 440 kwt. An ext rapo

lation of this curve would show that the the rma l power required to obtain any

e lec t r ica l power at 56 volts is on the order of 300 kwt.

An important observat ion from Figure III-5 is that 27.2 kwe can be obtained

at a r eac to r -ou t le t t empe ra tu r e of 1300°F compared to the 24.7 kwt at 1246°F.


32

28 -

24 -

20 -

LLl

O

16 -

12 -

1

-

Il -ll •

1

DESIGN

1-

1 1

^ ^

VOLTAGE \

_ J . . , . 1 .

1 1

\ \ REACTOR-OUTLET \ \ TEMPERATURE, "F

\ \ \ ^ 1 3 0 8

\ \ \ ^^ ^ ''

\\v\ ; \\v\-

1-13-69 UNCL

20 40 60 80

LOAD VOLTAGE, volts

100 120 140

7759-5266

Figure III-4. System Elec t r i ca l Cha rac t e r i s t i c s vs Reactor-Out le t Tempera tu re


ELE

CT

RIC

AL

PO

WE

R,

kwe

c:

z o

> I—I > O

-J

W

O

ts)

-J

OQ

W

Ul

^ •

CO

S" M

R

^ (D

o

"*

'-i

p3

"*

(D

<?

0 r+

^2

-1

m

30

> c=

m

CD

NJ

OQ

'

(I

O

II &

I—

'

<:;?

o

2

^3

CO

Xt 0)

i-t

r+

i-i

CD

O

3

RE

AC

TOR

TH

ER

MA

L P

OW

ER

, kw

t

T A B L E I I I -3

470 .0

- 5 . 0

465 .0

435.0

30.0

465.0

P A R T I A L - P O W E R P E R F O R M A N C E C H A R A C T E R I S T I C S ( T h r e e Loops O p e r a t i n g )

R e g u l a t e d p o w e r , kwe

Vo l t age , vo l t s :

S y s t e m

T h e r m o e l e c t r i c t u b u l a r m o d u l e

T h e r m a l - p o w e r b a l a n c e , kwt:

R e a c t o r


C o n v e r t e r s

P u m p c o n v e r t e r s

R a d i a t o r

G r o s s e l e c t r i c a l p o w e r

H y d r a u l i c power (adds to loop l o s s e s ^

T e m p e r a t u r e s , ° F

R e a c t o r NaK



R a d i a t o r NaK


S y s t e m

C o n v e r t e r

C o n v e r t e r C a r n o t

H y d r a u l i c s

O p e r a t i n g p r i m a r y loops (3)

N o n o p e r a t i n g p r i m a r y loop (1

H e a t - r e j e c t i o n loops (3)

To ta l F l o w r a t e , l b / s e c

12.9

- 2 . 3

9.5

19.8

56.0

14.0

Inle t

1104

1084

508

500

A v e r a g e

1184

1164

588

580

Out le t

1264

1244

668

660

444.0

20.2

0.8

465.0

4 .21

4 .57

35.5

A I - A E C - M E M O - 1 2 7 1 7

28

This means that the sys tem can accommodate as much as 10% degradation with

out the r eac to r -ou t l e t t empera tu re exceeding 1300°F. Operation at this t em

pe ra tu re level is believed to be acceptable for all components, but the reference

operating conditions a r e lower p r imar i l y to achieve t empera tu re margin to com

pensate for possible sys tem degradation.

3. P a r t i a l - P o w e r Pe r fo rmance

The e lec t r i ca l power capability of the sys tem is 19.8 kwe after loss of one

of the four H R L ' s . This a s sumes that all TE conver te rs in the three operating

loops a r e generat ing power and that the r eac to r core-out le t t empera ture is

r a i sed to 1300°F.

Since the pump on the nonoperating leg of the p r imary loop has no power,

this leg of the loop acts as a r eac to r bypass . Approximately 18% of the original

total flowrate goes through this loop while the flowrate in the other loops in

c r e a s e s to 33% of the original total f lowrate. This inc rease is due both to the

added bypass line and to the reduction in p r e s s u r e drop through the reac tor

co re . The bypass flow enters the r eac to r -ou t l e t plenum at the inlet t empe ra

ture so the t empera tu re exiting the plenum is only 1264°F when the core outlet

is 1300°F. Table III-3 s u m m a r i z e s the performance cha rac te r i s t i c s when

operating with only three quadrants .

C. SYSTEM OPERATION

Operation of the reac tor — TE powerplant is inherently simple because of

the pass ive na ture of TE power convers ion. Both the e lect r ica l power output

and the hydraulic power available from the pumps automatically increase as the

reac tor t empe ra tu r e and power a r e inc reased . The only par t s required to move,

for control of the powerplant, a r e the reac tor control d rums . The control drums

a r e rota ted slowly in d i sc re te steps of approximately 1 ° to change the radial

leakage of neutrons from the core and thus the neutron balance. Rotation of the

d rums in the direct ion to i nc rease the neutron level within the core causes the

reac tor power and t empera tu re to i nc rease until the inherent negative t empera

ture coefficient of the r eac to r s tabil izes the operation at a new power and t em

pera tu re level . A single drum step will change the operating tempera ture ap

proximate ly 5 to 15°F. The corresponding e lec t r ica l power change when operating

near the design point would be from 1/4 to 3/4 kwe.


1. Startup

Severa l options a r e available for s tar tup that t rade off total t ime and stand

by power for s ta r tup against complexity of the electronic control c i r cu i t s . The

s imples t c i rcui t would involve rotating the reac tor control d rums at a constant

ra te until the des i red e lec t r ica l power is reached. The t ime for s tar tup in this

case would be on the o rder of 12 h r . By introducing s tepping-ra te changes into

the s tar tup sequence, the s tar tup t ime could be reduced to 2 to 3 h r . Fea tu re s

must be added to the control sys tem for this ; however, even in this case the

control sys tem logic is re la t ively s imple .

The sys tem s tar tup has four dist inct phases . The detai ls of a typical s tar tup

a r e descr ibed for the Saturn-IVB OWS power sys tem in Section V-A-4b. Since

these detai ls a r e miss ion-dependent , the following paragraphs will descr ibe only

the genera l na ture of each phase and the possible options.

a. Phase 1: Shutdown Margin Removal

For safe handling on the ground the reac to r is designed to be approximately

$4,75 subcr i t ica l at room t e m p e r a t u r e . The f i rs t step in the s tar tup, then, is

to remove this shutdown marg in . Normally a fast s tepping-ra te would be used

during this phase and it would be completed in about 30 min. If the single

s tepping- ra te , dictated by Phase 2 l imi ta t ions , were used throughout the s t a r t

up, this phase would requ i re approximate ly 10 hr .

The slowdown in s tepping-ra te at the end of Phase 1 would be signaled by

a con t ro l -d rum position indicator or step counter . The selected dr\am position

would cor respond to a 25 to 50« subcr i t ica l condition in the r eac to r . Since the

drum position at which the r eac to r is c r i t i ca l va r ies slowly throughout the life

of the r e a c t o r , it is anticipated that the selected drum position could be changed.

This could be coordinated routinely from the ground control center , since any

single adjustment would be usable for s tar tups during a period of at least one

month.

At leas t 5% flow will be requi red during this phase to a s s u r e that no local

NaK freezing occurs in the sys tem and that an acceptable t r ans ien t r esu l t s when

the rmal power is init iated. Though seve ra l ways of providing NaK flow a re


p o s s i b l e , e a c h would r e q u i r e s o m e s t a n d b y e l e c t r i c a l p o w e r . One way i s

to p a s s 50 a m p t h r o u g h s m a l l s t a r t u p p u m p s a t t a c h e d to e a c h loop. This c u r

r e n t would p a s s t h r o u g h e a c h p u m p in s e r i e s , for a to ta l vo l t age d rop of about

2 v o l t s . T h u s the t o t a l p o w e r r e q u i r e m e n t would be about 100 w a t t s . It i s

a n t i c i p a t e d tha t th i s i s a r e l a t i v e l y low r e q u i r e m e n t c o m p a r e d to o the r power

r e q u i r e m e n t s d u r i n g s p a c e c r a f t d o r m a n t p e r i o d s or du r ing n o n o p e r a t i n g m a n n e d

p e r i o d s .

b . P h a s e 2: C r i t i c a l to S e n s i b l e Hea t

Dur ing t h i s p h a s e of the s t a r t u p the s t epp ing r a t e m u s t be r e d u c e d to the

m i n i m u m r a t e . Once the r e a c t o r goes c r i t i c a l the n e u t r o n flux o r power leve l

b e g i n s to i n c r e a s e f r o m s o m e low s o u r c e l e v e l , but no r e a c t i v i t y feedback due

to the n e g a t i v e t e m p e r a t u r e coef f ic ien t of the r e a c t o r i s i n t r o d u c e d unt i l the

power l e v e l r e a c h e s a l eve l of about 1 kwt . Th i s n o r m a l l y o c c u r s on the o r d e r

of 20 m i n a f t e r c r i t i c a l i t y , so the r e a c t o r is s u p e r c r i t i c a l by the a m o u n t of r e

a c t i v i t y i n s e r t e d du r ing t h i s 2 0 - m i n u t e p e r i o d . The d e g r e e of s u p e r c r i t i c a l i t y

d e t e r m i n e s the r a t e of i n c r e a s e of p o w e r , the m a g n i t u d e of the power s p i k e , and

the r e s u l t i n g t e m p e r a t u r e t r a n s i e n t tha t o c c u r s b e f o r e the i n h e r e n t r e a c t o r t e m

p e r a t u r e c h a r a c t e r i s t i c s s t a b i l i z e the o p e r a t i n g c o n d i t i o n s .

The d r u m s t e p p i n g - r a t e i s l i m i t e d so tha t the t e m p e r a t u r e t r a n s i e n t i s a c

c e p t a b l e . When the t i m e to r e m o v e the l a s t 25 to 50^ of the shutdown m a r g i n i s

i n c l u d e d , t h i s p h a s e of s t a r t u p t a k e s about 40 to 60 m i n . The end of P h a s e 2 i s

s i g n a l e d b y a t e m p e r a t u r e s e n s o r on the r e a c t o r ou t le t l ine s e t at a p p r o x i m a t e l y

3 0 0 ° F ,

An e s t i m a t e of the s t a r t u p t r a n s i e n t i s shown in Sect ion V - A - 4 b . The power

sp ike and t e m p e r a t u r e t r a n s i e n t wi th th i s r e a c t o r a r e g r e a t e r than wi th p r e v i o u s

SNAP r e a c t o r s b e c a u s e of the r e d u c t i o n in f u e l - t e m p e r a t u r e coeff ic ient c a u s e d

by the add i t i on of Gd p r e p o i s o n . The m a g n i t u d e of the t r a n s i e n t wi l l be r e d u c e d

a s the r e a c t o r i s o p e r a t e d , for two r e a s o n s . F i r s t , the Gd b u r n s out r e s u l t i n g

in an i n c r e a s e in fuel coef f ic ien t ; and s e c o n d , the s o u r c e power l eve l which af

f ec t s the t i m e b e t w e e n c r i t i c a l and s e n s i b l e hea t i s g r e a t l y i n c r e a s e d a f t e r o p e r a

t ion . In fac t if the r e a c t o r i s to be r e s t a r t e d within an h o u r a f t e r shutdown, the

s t e p p i n g - r a t e for t h i s p h a s e could be e a s i l y doubled.

A I - A E C - M E M O - 1 2 7 1 7

31

REA

CTO

R F

LUX

(n

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c . P h a s e 3: Hea t Shield R e m o v a l

Once the t e m p e r a t u r e s e n s o r i n d i c a t e s tha t the r e a c t o r i s g e n e r a t i n g p o w e r ,

the h e a t s h i e l d s wh ich enve lope the r a d i a t o r dur ing n o n o p e r a t i n g p e r i o d s to p r o

t e c t a g a i n s t NaK f r e e z i n g can be r e m o v e d . This p h a s e of the s t a r t u p i s m o s t

a f fec ted by the d e s i g n of the p o w e r p l a n t and the m i s s i o n i n t e g r a t i o n c o n s t r a i n t s .

The t i m e for t h i s p h a s e can v a r y f r o m z e r o , w h e r e the hea t sh i e ld s a r e e j ec ted

o r r e m o v e d quick ly and no h e s i t a t i o n in the s t a r t u p i s r e q u i r e d , to about 30 m i n ,

w h e r e the r e m o v a l m u s t be a c c o m p l i s h e d m o r e s lowly . In the l a t t e r c a s e , which

m a y invo lve the d e p l o y m e n t of folded r a d i a t o r s , the r e a c t o r - o u t l e t t e m p e r a t u r e

would p r o b a b l y be l i m i t e d un t i l h e a t sh ie ld r e m o v a l is c o m p l e t e d ,

d. P h a s e 4: R a m p to P o w e r

Th i s p h a s e of the s t a r t u p i s r e s t r i c t e d only by the t r a n s i e n t t e m p e r a t u r e

l i m i t a t i o n on the s y s t e m . The r a m p could be a t a r a t e of t e m p e r a t u r e i n c r e a s e

of about 2 0 ° F / m i n and c o m p l e t e d in about 40 m i n . I t i s i m p o r t a n t to r e - e m p h a s i z e

tha t no c o n t r o l s a r e r e q u i r e d for the p o w e r p l a n t o the r than for the con t ro l d r u m s .

As the r e a c t o r t e m p e r a t u r e i n c r e a s e s , the t e m p e r a t u r e d i f fe rence a c r o s s the

T E m o d u l e s i n c r e a s e s and the NaK flow and e l e c t r i c a l power a u t o m a t i c a l l y in

c r e a s e . Once the o p e n - c i r c u i t vo l t age of the TE c o n v e r t e r e x c e e d s 56 v o l t s ,

u se fu l e l e c t r i c a l power a t the r e g u l a t e d 56-vdc l eve l b e c o m e s a v a i l a b l e .

P h a s e 4 of the s t a r t u p i s t e r m i n a t e d when e l e c t r i c a l c u r r e n t r e a c h e s a p r e

d e t e r m i n e d s e t t i n g . A r e a c t o r - o u t l e t t e m p e r a t u r e s igna l would be u sed to s top

d r u m i n s e r t i o n , should an a n o m a l y p r e v e n t r e a c h i n g full e l e c t r i c a l power wi thout

e x c e s s i v e t e m p e r a t u r e . Th i s cutoff would n o r m a l l y be se t a t about 1325°F . After

the end of th i s p h a s e of the s t a r t u p , wh ich c o m p l e t e s the s t a r t u p , the s y s t e m

would be c o n t r o l l e d wi th in a d e a d b a n d on e l e c t r i c a l c u r r e n t output .

A l though the vo l t age r e g u l a t i o n s y s t e m is de s igned to hand le e l e c t r i c a l load

f l u c t u a t i o n s , the e l e c t r i c a l c u r r e n t c o n t r o l point could be ad ju s t ab l e to t ake ad

van t age of long p e r i o d s (weeks ) when r e d u c e d power r e q u i r e m e n t s a r e p lanned .

Th i s could i n c r e a s e l ife o r r e l i a b i l i t y by a l lowing ex tended o p e r a t i o n at r e d u c e d

t e m p e r a t u r e s and r e d u c e d load on the vol tage r e g u l a t o r .

A b r i e f r e v i e w of the s t a r t u p of the SNAP lOA power s y s t e m in o rb i t , shown

in F i g u r e I I I -6 , i s helpful in u n d e r s t a n d i n g the s e q u e n c e . Th i s s t a r t u p s u c c e s s

fully a c c o m p l i s h e d a l l four p h a s e s a s d e s c r i b e d above . P h a s e 1, shutdown m a r g i n

A I - A E C - M E M O - 12717 33

1200

1000

800 -

600 -

400

200 -

0

1 ISG^UNC

1

-

-

1

1 1 1 1 I I 1 1 1 1 1 M M

AVERAGE PRIMARY LOOP ^ v NaK TEMPERATURE \

AVERAGE HEAT REJECTION TEMPERATURE

1 1 1 1 1 1 1 1 1 1 1 1 1 1 !

1 1 1 1 1 1 M

\ ;

\ \ -

1 1 1 1 1 1 I I 10 10 0

TIME mm

Figure III-7. System Shutdown Trans ien t s , NaK Tempera tu res -24«^/min

100 0

7759 5268

0 1

I 15 S9 UNC

Figure III-

600

„400

m o Q-

200

0

o

O a: < ^ 4 0 cn 13 1— <c ce

1 20 Ll_ O

< Q

1 1 1 1 1 1 r 1 * - F U L L POWER

- ^ ^ \

^

~

-

1 1 1 1 1 1 r 1

\

\ .

MISSION ^ ^ • ^ ^ ^ ^ POWER ^ ^ > ~ - - ^ ^ _

^ ^ ^ ^

HEAT REJECTIONv LOOP \ _

1 1 1

PRIMARY NaK LOOP

1 1 1 1

1 1 1 1

-

"

-

r ~ r 1 1 1

10 0 100 0

7759 5269

System Shutdown Trans i en t s , Power and Rate of Tempera tu re Change -24«^/min


removal , was acce le ra ted by the immedia te inser t ion of two of the four control

drums immediate ly upon receipt of the s tar tup command. These were spr ing-

loaded. Phase 1 continued, however, for approximately 6 hr as the remaining

two drums were inse r ted at the single s tepping- ra te . Phase 2, the time from

cr i t i ca l to sensible heat , took approximately 25 min and culminated in the power

spike and t empera tu re t rans ien t shown. This important part of the s tar tup es tab

lished that the effective source power level in the SNAP lOA orbit was about as _ Q

predicted, 10 kw. Phase 3 was accomplished instantaneously by ejection of

the heat shields when the reac to r ou t le t - t empera tu re reached 325 °F, The r amp

to power, Phase 4, took about 2 h r . The control in this case was on r e a c t o r -

outlet t e m p e r a t u r e , 2. Shutdown

The sys tem is shut down simply by rotating the control drums to their least

react ive position. Again, e lec t r ica l generat ion and NaK flow follow automatically

as the r eac to r t empe ra tu r e drops . Normal ly the shutdown would be accom

plished using the same con t ro l -d rum s tepping-ra te as used during Phase 1 of

the s ta r tup . F igures III-7 and - 8 show the sys tem performance using a react iv i ty-

removal ra te of -24«^/min, typical of the ra te result ing from a Phase 1 stepping-

rate with the drum in the normal operation zone. The ra te of cooldown of the

sys tem is controlled by its heat capacity, and the t ime for cooldown therefore

is essent ia l ly independent of the reac t iv i ty - removal ra te in the range of in te res t .

For the ra te shown, the fission power is reduced to 1% in about 3.5 min. This

would probably be fast enough to mee t operat ional requ i rements ; however, the

reac t iv i ty - removal ra te could be inc reased to reduce the power to this level in

less than 1 min. The t empera tu re t rans ien t would not be appreciably different

for this la t ter ca se .

After approximately 1 hr , rep lacement of the heat shields around the r ad i

ator would have to be made to protect against NaK freezing.

D. RELIABILITY

The re l iabi l i ty of the sys tem has been calculated based on reasonable es t i

ma tes of that for the components . These es t imates r ep resen t s t a t e -o f - the -a r t

rel iabi l i ty for s imi la r c l a s ses of equipment where possible , and in other a r eas


o

> t-H I

> O

M

O

u asaa

0 9998

0 9994

0 999

0 998

0 994

0 990

0 98

0 94

0 90

08

04

n

1 1

-

„

-

-

-

-

-

-

1 L_

1 1 1 1 1 1 1 1

1 1 1

HEAT-REJECTION SYSTEM 1

1 1 1

I I I 1 1

1

'CONVERTER 'ELECTRICAL 1 ,

1

REACTOR AND PRIMARY

LOOP'

1 _ _ . _ _ „

TOTAL SYSTEM

1 ,

T"

1

1

1 1 1

-

~

-

-

-

-

-

-:

-

12 14 16

ELECTRICAL POWER kwe

20 22 24 26

Figure III-9. System Reliability, 10,000-hr Duration

they a r e based on demonstrable object ives. The calculated resu l t s a re not to

be taken as p rec i se values of the sys tem rel iabi l i ty, but as good indicators of

the o rder of magnitude of that expected, the t rend of rel iabi l i ty with par t ia l

power leve ls , and a reasonable apport ionment of it to the system components.

1. System Reliabil i ty

F igures III-9 and -10 show a s u m m a r y of system rel iabil i ty es t imates for

various power l eve l s . The calculated figures show that the system has very

high re l iabi l i ty for delivering a la rge percentage of the design power. The gross

sys tem power capabili ty is 25.2 kwe and the rel iabil i ty for producing this power

for 20,000 hr is 64%. The rel iabi l i ty figures inc rease significantly fronn. this

level to 95% at 23 kwe and over 99% at about 18 kwe for the same period. At

10,000 hr , the t rend is the same; however, the full-power rel iabi l i ty is in

c reased to 80%, the 23-kwe value is over 97,5%, and the 18-kwe value is over

99.7%, It should be noted that these par t ia l -power rel iabi l i t ies do not imply

that the sys tem mus t be operated at reduced power in order to achieve them.

The sys tem can be operated continuously at its maximum capability with little

or no effect on the par t ia l -power re l iab i l i t i es .

The major subsys tem values a r e also shown in Figures III-9 and -10. It

can be seen that the f i rs t s t ep - inc reases in rel iabil i ty occur when the e lec t r ica l

output of individual conver ter 4-packs can be lost due to open or short c i rcu i t s .

Below 75% po^wer a large incrementa l change in rel iabil i ty is gained by allowing

an ent i re HRL to fail. The rel iabi l i ty of the reac tor and p r imary hea t - t ransfe r

loop is the final l imiting value. With the exception of insignificant gain which

might be rea l ized by lower s t r e s s on the fuel and more allowable combinations

of con t ro l -d rum fa i lures , the probabil i ty of successful operation for this portion

of the sys tem rema ins essent ia l ly constant r egard less of the power level for the

sys tem,

2, Bases for Es t ima tes

The var ious component re l iabi l i ty values used to calculate subsystem and

sys tem re l iabi l i ty a r e best es t imates of expected rel iabil i ty for developed equip

ment . The re l iabi l i ty analysis of the sys tem is thus based on values judged to

be reasonably at tainable. The following paragraphs contain the bases for the

rel iabi l i ty e s t ima tes of major component classif icat ions, A summary of these

es t imates is shown in Table III-4 for the entire system.


>

O

w E 00 ^

O

DO - J

0 9999

0 9998 -

0 9994

0 999

0 998

0 994 -

: 0 99

0 94

0 90

08

04

0

1 1 1 1 1 I I I 1 1

; HEAT REJECTION SYSTEM 1 _,

REACTOR AND PRIMARY LOOP

1

-

-

1 1 1 1 L . _ ,

[CONVERTER |_ELECTRICAL

1 1 1 1 1

1 1 J

1

1 1

__ __ - -

-

1 1 1 _ ] 1 . 1 1 1 . J 1 1

-

1 1 •

L

1

0 2

I 15-69 UNC

10 12 14 16

ELECTRICAL POWER kwe

18 20 22 24

Figure 111-10. System Reliabil i ty, 20,000-hr Duration

TABLE III-4

RELIABILITY ESTIMATES

Component

P r i m a r y sys tem

Reactor

Vessel

Fuel

Control drums and actuator

Piping

Pumps and conver ter piping

Pump and conver ter e lec t r ica l

Expansion compensator

Main conver ter piping

Heat - re jec t ion loop (4 per

Piping

unit (4)

system)

Pump and conver ter piping

Pump and conver ter e lec t r ica l

Expansion compensator

Main conver ter piping

Radiator

Function

Meteoroid

Conver ter e lec t r ica l

24 of 24 (4-packs)

23 of 24 (4-packs)

22 of 24 (4-packs)

unit

Ful l -power sys tem re l iabi l i ty

Est imated R

10,000 hr

0,9979

0,99900

0.999

0,999999

0,999999

0.9997

0,99968

0,99986

0,99992

0,99968

0.9949

0,99984

0,99985

0,99994

0,99998

0,9986

0.998

0.9987

0.820

0.983

0.9989

0.802

eliability, R

20,000 hr

0,9953

0.9978

0.998

0.9999

0,99987

0,9994

0.99936

0,99962

0.9996

0.99935

0,990

0,99968

0,99969

0,99988

0,9999

0.9971

0.996

0.9975

0.673

0.941

0.9927

0.643


a. Welds

B a s e d on s u r v e y s of f lu id - loop e x p e r i e n c e , a weld f a i l u r e - r a t e of l e s s than

one f a i l u r e in 10 h r / t u b e - w e l d h a s b e e n e s t i m a t e d . This i s s u p p o r t e d by da ta

ob ta ined 3 y e a r s ago f r o m ORNL c o n c e r n i n g r e a c t o r f u e l - e l e m e n t we ld i n t e g r i t y

and m o r e r e c e n t s u r v e y s of l a r g e r e a c t o r h e a t - t r a n s f e r loops and h e a t e x c h a n g e r

conduc t ed by AI,

As of O c t o b e r 1965, W e s t i n g h o u s e w a t e r r e a c t o r fuel e l e m e n t s had a c c u m u -9

l a t ed in e x c e s s of 10 w e l d - o p e r a t i n g h o u r s wi thout a f a i l u r e . M o r e r e c e n t e x p e r i e n c e wi th h e a t e x c h a n g e r s in p r e s s u r i z e d - w a t e r - r e a c t o r (PWR) p l a n t s h a s

9 d e m o n s t r a t e d 1.5 x 10 t u b e - h o u r s w i th 11 f a i l u r e s , none of w h i c h w e r e i d e n t i fied as we ld f a i l u r e s ,

A s u r v e y of t u b e - w e l d p e r f o r m a n c e in s o d i u m s e r v i c e a l s o s u p p o r t s the

weld f a i l u r e - r a t e e s t i m a t e . E x a m i n a t i o n of s o m e of the s o d i u m s y s t e m s which

have a c c u m u l a t e d an i m p r e s s i v e a m o u n t of o p e r a t i n g e x p e r i e n c e g ives the v a l u e s

in Tab le I I I - 5 , C o n s i d e r i n g the s t e a m - g e n e r a t o r e x p e r i e n c e a lone g ives a b e s t - 8

e s t i m a t e f a i l u r e r a t e of 1.3 x 10 f a i l u r e s p e r w e l d - h o u r . If the h e a t e x c h a n g e r

and D o u n r e a y p r i m a r y - l o o p e x p e r i e n c e i s added to the s t e a m - g e n e r a t o r e x p e r i -_9

e n c e , the f a i l u r e - r a t e d r o p s a f ac to r of five to 2,6 x 10 f a i l u r e s p e r w e l d - h o u r .

T A B L E III-5

T U B E - W E L D HISTORIES

F a c i l i t y

H a l l a m N u c l e a r P o w e r F a c i l i t y ( H N P F )

Sodium R e a c t o r E x p e r i m e n t (SRE)

D o u n r e a y

E x p e r i m e n t a l B r e e d e r R e a c t o r II (EBR II)

R a p s o d i e

MSAR (Model S t e a m G e n e r a t o r )

A s s e m b l y

S t e a m g e n e r a t o r Hea t e x c h a n g e r


P r i m a r y loop


Hea t e x c h a n g e r

S t e a m g e n e r a t o r No, 1 S t e a m g e n e r a t o r No, 2 H e a t e x c h a n g e r

Tubes

3,720 8,400

2 0 0 316

-

730 3,026

8 8 8

59 38

2 7 3

Tube Welds

7,440 16,800

4 0 0 632

8,000

1,460 6,052

1,776

118 76

546

H o u r s

7,194 7,194

37,000 37,000

60 ,000

4 ,360 4 ,360

17,400

3,615 4,926 8,541

F a i l u r e s

0 0

0 0

0

1 0

0

0 0 1

A I - A E C - M E M O - 12717 40

Considering the above data and all of the additional tes t - loop experience and -9

faci l i t ies , the weld f a i lu re - ra t e of 1 x 10 failures per weld-hour appears to be

a reasonable es t ima te . This f a i lu re - ra te has been applied to all NaK-loop tube

joints in the sys tem. Where large weldments a r e involved, an es t imate of the

equivalent number of welds has been used,

b . Reactor Vessel

-7 The reac tor vesse l f a i lu re - r a t e of 10 failures per hour r ep resen t s an es t i

mate that the vesse l is equivalent to 100 tube welds in complexity,

c. Reactor Fuel

The reac to r fuel re l iabi l i ty is determined analytically by margin co r r e l a

t ions . These cor re la t ions for fuel growth and phase change were a major resu l t

of the SNAP 8 Exper imenta l Reactor (S8ER) test analysis and SNAP 8 Develop

mental Reactor (S8DR) design p rogram. The fuel e lements a re designed to p ro

vide a mean life of 36,000 hr to phase change with a deviation of 4115 hr. They

also have a calculated mean life of 156,000 hr to cladding rupture with a devia

tion of 31,250 h r . These dis tr ibut ions resu l t in a probability of failure for an -6 -5

element of 1.3 x 10 in 10,000 hr or 5,5 x 10 in 20,000. Combining these

probabi l i t ies in a Poisson expansion for the 295 elements in the core resu l t s in

a 0.99984 probabili ty of no m o r e than one failure in 10,000 hr and 0.99997 proba

bility of no more than two fai lures in 20,000, A rel iabi l i ty of 0.9999 is used as

the es t imated value under the assumption that loss of one or two elements late

in the sys tem life would be of no consequence. This is ext remely conservative

since S8ER operated successfully with 80% of i ts fuel elements cracked. By the

same reasoning the core re l iabi l i ty for 10,000 hr is est imated to be > 0.99999 or

essent ia l ly 1.0, d. Control Drums and Actuators

Each control drum and actuator is es t imated to have a failure ra te of 1 x

10 fai lures per hour. This is broken down to 0.6 x 10 for the actuator and

0.4 X 10 for the bea r ings . These es t imates a re from the tabulation of "Fa i lu re

Ra te s" published by AVCO for equipment judged to be s imi la r in design and appli

cation. In these tab les , s tepper moto r s a re es t imated to have a generic fai lure-- 6 -6 6

ra te between 0,22 x 10 and 0,71 x lO" and bearings range from 0,02 x 10 to 5,5 X 10 . Because of the redundant nature of the bearing it appears reasonable


to a s s i g n a va lue of 0,4 x 10 to the two s e t s of b e a r i n g s for e a c h d r u m . The

d r u m s t h e m s e l v e s a r e not c o n s i d e r e d to have a f a i l u r e - r a t e which would be a

s ign i f i can t add i t ion to a 1 x 10 f a i l u r e - r a t e for the d r i v e c o m p o n e n t .

A f a i l u r e - m o d e and effects s tudy of the ten c o n t r o l d r u m s can b e s u m m a r i z e d

a s fo l lows:

1) Two d r u m s c a n r e m a i n in the shu tdown p o s i t i o n at the beg inn ing-o f -

life (BOL) wi th the r e s u l t be ing a life l i m i t of a p p r o x i m a t e l y 42 m o

for r e a c t o r o p e r a t i o n .

2) T h r e e d r u m s can r e m a i n s e i z e d in any o p e r a t i n g pos i t i on a f t e r hot

B O L and not affect the 2 0 , 0 0 0 - h r o p e r a t i o n .

3) T h r e e d r u m s s e i z e d in the cold c r i t i c a l pos i t i on be fo re hot B O L wi l l

l i m i t r e a c t o r o p e r a t i o n to about 54 m o .

4) T h r e e d r u m s s e i z e d in the h o t - B O L pos i t i on wi l l m a k e the r e a c t o r

shutdown l i m i t e d in a p p r o x i m a t e l y 20 m o .

5) C o n t r o l i s a s s u m e d to b e e i t h e r s i m u l t a n e o u s on a l l ten d r u m s or

s e q u e n t i a l in s u c h a m a n n e r tha t u n d e r n o r m a l o p e r a t i n g cond i t i ons

a l l d r u m s wi l l be in r e l a t i v e l y the s a m e pos i t i on at any g iven t i m e .

The r e l i a b i l i t y of the r e a c t i v i t y c o n t r o l - d r u m s y s t e m i s c a l c u l a t e d by a

b i n o m i a l e x p a n s i o n a l lowing t h r e e out of t en d r u m s to fail a t any t i m e . T h i s

a p p e a r s to be a r e a s o n a b l e a p p r o x i m a t i o n to the c o n d i t i o n s ; the only c r i t i c a l

c o m b i n a t i o n of e v e n t s -which i s i g n o r e d i s t he s i m u l t a n e o u s f a i l u r e of t h r e e

d r u m s a t hot B O L . The p r o b a b i l i t y of t h i s o c c u r r e n c e i s i n s ign i f i can t . The

r e s u l t i n g e s t i m a t e d r e l i a b i l i t y for the c o n t r o l d r u m s i s 0.999999 for 10,000 h r

and 0.99987 for 20 ,000 h r .

e . P r i m a r y P i p i n g

This p o r t i o n of the s y s t e m inc l udes a l l i n t e r c o n n e c t i n g piping of the p r i m a r y

N a K - l o o p wi th the e x c e p t i o n of the c o n v e r t e r m a n i f o l d s and p u m p m a n i f o l d s , A - 8

f a i l u r e - r a t e of 3 x 10 f a i l u r e s p e r hou r i s a s s i g n e d on the b a s i s of an e s t i m a t e d

30 t u b e - w e l d s .

A I - A E C - M E M O - 12717 42

f. P u m p s

E a c h of the four p u m p a s s e m b l i e s c o n t a i n s t h r e e t h r o a t s ; two a r e in s e r i e s

for the p r i m a r y s y s t e m and one i s for the r e s p e c t i v e H R L . Coupled to t h e p u m p

a r e t h r e e T E m o d u l e s . The m o d u l e s a r e e l e c t r i c a l l y p a r a l l e l e d to the pump bus

b a r s . The p u m p t h r o a t s a r e e l e c t r i c a l l y in s e r i e s . The p r i m a r y piping to the

pump c o n v e r t e r i s c o n s i d e r e d to be d o u b l e - c o n t a i n e d .

P o r t i o n s of the p u m p and c o n v e r t e r p ip ing c o n s i d e r e d for the p r i m a r y loop

inc lude eight p u m p w e l d s p e r p u m p and 23 c o n v e r t e r - p i p i n g we lds d o u b l e -_9

con ta ined p e r p u m p . Us ing the t u b e - w e l d f a i l u r e - r a t e of 10 f a i l u r e s p e r hour

r e s u l t s in a r e l i a b i l i t y of 0 .99968 for 10,000 h r , or 0.99936 for 20,000 hr con

s i d e r i n g a l l four p u m p a s s e m b l i e s .

The r e l i a b i l i t y for the p u m p c o n v e r t e r e l e c t r i c a l p e r f o r m a n c e c o n s i d e r s a l l

twe lve c o n v e r t e r m o d u l e s . A s h o r t - c i r c u i t condi t ion in the m o d u l e s is of no

c o n s e q u e n c e s i n c e the bus b a r s to the p u m p p r o v i d e a m u c h b e t t e r s h o r t to

g round than any o t h e r c r e d i b l e p o s t u l a t e d s h o r t f r o m a f a i lu re condi t ion . An

o p e n - c i r c u i t in one m o d u l e out of the twe lve m o d u l e s would r e d u c e the to ta l s y s -_7

tern e l e c t r i c a l p o w e r c a p a b i l i t y about 1% o r 250 w a t t s . A f a i l u r e - r a t e of 1 x 10

f a i l u r e s p e r h o u r p e r m o d u l e i s a s s i g n e d for th i s m o d e . This i s one -ha l f of the

f a i l u r e - r a t e a s s i g n e d to the m a i n c o n v e r t e r m o d u l e s for both sho r t i ng and o p e n -

c i r c u i t m o d e s . The b a s i s for th i s f a i l u r e - r a t e i s d e s c r i b e d in the p a r a g r a p h s

c o v e r i n g the m a i n c o n v e r t e r r e l i a b i l i t y e s t i m a t e s . It i s a s s u m e d that one pump

c o n v e r t e r out of the twe lve can fail wi th no s ign i f ican t effect on the s y s t e m . Using

a b i n o m i a l expans ion for t h i s c r i t e r i o n r e s u l t s in a p u m p c o n v e r t e r e l e c t r i c a l r e

l i ab i l i t y of 0.99986 for 10,000 h r o r 0.99962 for 20,000 h r . This r e l i a b i l i t y is

c h a r g e d to the p r i m a r y s y s t e m . V a r i o u s c o m b i n a t i o n s of p u m p - m o d u l e f a i l u r e s

could r e s u l t in f u r t h e r l o s s of s y s t e m p o w e r wi thout c o m p l e t e power l o s s , but

th i s p o s s i b i l i t y h a s b e e n i g n o r e d for the p r e s e n t a n a l y s i s .

P o r t i o n s of the p u m p and c o n v e r t e r p iping c o n s i d e r e d for e a c h H R L inc lude

four e a c h of p u m p and t u b e - w e l d s , and 7,5 equ iva l en t tube-welds for the c o n t a i n

m e n t j a c k e t s u r r o u n d i n g the m o d u l e s , for a to ta l of 15.5 . Using the t u b e - w e l d _9

f a i l u r e - r a t e of 10 f a i l u r e s p e r hour r e s u l t s in a r e l i a b i l i t y of 0.99985 for

10,000 h r or 0,99969 for 20 ,000 , A f a i l u r e in th i s c a t e g o r y wil l fail only the

H R L invo lved .

A I - A E C - M E M O - 12717 43

The p u m p and c o n v e r t e r e l e c t r i c a l r e l i a b i l i t y w h i c h in f luences e a c h H R L

IS d e t e r m i n e d by the e l e c t r i c a l - b u s bond a r e a s . E a c h p u m p h a s the equ iva len t

of 6 bond a r e a s m s e r i e s . A f a i l u r e of any bond wi l l r e s u l t m the l o s s e q u i v a

len t of the r e s p e c t i v e H R L . The f a i l u r e - r a t e for an e l e c t r i c a l bond i s a s s u m e d _9

to be 10 f a i l u r e s p e r h o u r , on the a s s u m p t i o n tha t an e l e c t r i c a l bond i s about

the s a m e a s a t u b e - w e l d for f a i l u r e - r a t e c o n s i d e r a t i o n s . The r e s u l t i n g r e l i a

b i l i ty IS 0,99994 for 10,000 h r o r 0 .99988 for 20,000 h r for e a c h p u m p .

g. E x p a n s i o n C o m p e n s a t o r Unit (ECU)

B e c a u s e the p r i m a r y f a i l u r e m o d e c o n s i d e r e d for the ECU is l e a k a g e t h r o u g h

the b e l l o w s a s s e m b l y , e a c h un i t h a s r e d u n d a n t b e l l o w s . A p r i m a r y c o n t a i n m e n t

be l l ows funct ions n o r m a l l y con ta in ing the NaK t h r o u g h o u t the expans ion c y c l e ,

and a s e c o n d a r y i s p r o v i d e d to con ta in the NaK and a l low u n i n t e r r u p t e d function

of the un i t m even t of a l eak t h r o u g h the p r i m a r y . P r e v i o u s a n a l y s i s of the b e l

lows for the SNAP lOA c o m p e n s a t o r i n d i c a t e d a s t r e s s - m a r g i n r e l i a b i l i t y of e s

s e n t i a l l y un i ty , A w e l d - f l a w f r e q u e n c y a n a l y s i s of the SNAP lOA b e l l o w s e x

p e r i e n c e i n d i c a t e d r e l i a b i l i t y for f r e e d o m f r o m f laws of a p p r o x i m a t e l y 0.997 p e r

a s s e m b l y . In add i t ion it i s c o n s e r v a t i v e l y e s t i m a t e d tha t e a c h a s s e m b l y wi l l

have a t i m e - d e p e n d e n t f a i l u r e - r a t e equ iva l en t to 180 t u b e - w e l d s . T h e s e v a l u e s

r e s u l t in r e d u n d a n t b e l l o w s p r o v i d i n g a r e l i a b i l i t y of 0 ,99998 for 10,000 h r o r

0.9999 for 20,000 h r for one c o m p e n s a t o r un i t . F o u r c o m p e n s a t o r s a r e r e q u i r e d

for the p r i m a r y s y s t e m and one c o m p e n s a t o r i s r e q u i r e d for e a c h H R L .

h. M a m C o n v e r t e r P i p i n g

The c o n v e r t e r c o n s i s t s of 24 4 - p a c k a s s e m b l i e s . The man i fo ld ing of the

p r i m a r y H R L into and out of the 4 - p a c k s wi l l be d o u b l e - c o n t a i n e d , a l though

th i s f e a t u r e w a s not i n c o r p o r a t e d in to the d e s i g n m t h i s s tudy , f ea s ib l e m e t h o d s

of d o u b l e - c o n t a i n m e n t w e r e r e v i e w e d and one wi l l be i n c o r p o r a t e d a s the c o n

v e r t e r d e s i g n evo lves m the nex t p h a s e of the p r o g r a m . The H R L mani fo ld ing

on the co ld s ide of the c o n v e r t e r s i s m a n i f o l d e d into the four i s o l a t e d l o o p s .

E a c h loop p r o v i d e s the h e a t r e j e c t i o n for s ix 4 - p a c k a s s e m b l i e s . The r e l i a b i l i t y

e s t i m a t e s a r e b a s e d on weld jo in t s a s fol lows

P r i m a r y Manifolding

32 h e a d e r s , e a c h wi th 17 d o u b l e - c o n t a i n e d w e l d s a s fol lows

7 m o d u l e p ipe w e l d s ,

A I - A E C - M E M O - 1 2 7 1 7 44

1 c a p weld ;

9 s e a m weld on h e a d e r (4 i n . / w e l d equ iva len t ) ; and

1 p i p e - t o - h e a d e r weld (not d o u b l e - c o n t a i n e d ) .

H R L Manifo ld ing;

6 4 - p a c k s p e r loop wi th 24 w e l d s p e r 4 - p a c k as fol lows:

8 m o d u l e ;

6 p a c k - t o - h e a d e r ; and

10 s e a m - w e l d equ iva l en t , m a k i n g a to t a l of 144 we lds p e r loop .

_9 A s s i g n e d a we ld f a i l u r e - r a t e of 10 p e r we ld and accoun t ing for the r e d u n d a n c y

of the d o u b l e - c o n t a i n e d p ip ing g ives a r e l i a b i l i t y for the p r i m a r y mani fo ld ing of

0,99968 for 10,000 h r o r 0,99935 for 20,000 h r .

F o r the H R L ' s the r e l i a b i l i t y of the mani fo ld ing for e a c h loop i s c a l c u l a t e d

to be 0.9986 for 10,000 h r o r 0,9971 for 20,000 h r ,

i . H R L P i p i n g

This p o r t i o n of the s y s t e m i nc ludes a l l of the i n t e r c o n n e c t i n g piping of the

H R L ' s wh ich c o n n e c t the c o n v e r t e r 4 - p a c k s , p u m p s , r a d i a t o r s , and E C U ' s

into four i s o l a t e d l o o p s . An e s t i m a t e d t u b e - w e l d c o m p l e x i t y equ iva len t to 16 - 8

w e l d s p e r loop g i v e s an a s s i g n e d f a i l u r e - r a t e of 1,6 x 10 f a i l u r e s p e r hour p e r

H R L . Any l e a k in the p iping fa i ls only the H R L involved ,

j . R a d i a t o r

The r a d i a t o r i s s e g m e n t e d into four p a r t s wi th e a c h s e g m e n t be ing an i s o

l a t ed p o r t i o n of the r e s p e c t i v e H R L . The funct ional f a i l u r e - r a t e for each s e g -_7

m e n t is e s t i m a t e d on the b a s i s of a p p r o x i m a t e l y 200 t u b e - w e l d s to be 2 x 10

f a i l u r e s p e r h o u r . In add i t ion to t h i s f a i l u r e - r a t e is the m e t e o r o i d - p u n c t u r e _7

h a z a r d wh ich i s s e t at 1.25 x 10 p u n c t u r e s p e r hour for the p r e s e n t de s ign .

Th i s r a t e i s e s t a b l i s h e d by the m e t e o r o i d - i n f l u x c r i t e r i a and the a r m o r t h i c k n e s s

s e l e c t e d .

k. C o n v e r t e r E l e c t r i c a l

Two f a i l u r e m o d e s a r e c o n s i d e r e d in the eva lua t ion of the c o n v e r t e r . An

open c i r c u i t in any c o n v e r t e r m o d u l e could c a u s e r educ t i on in to t a l power

A I - A E C - M E M O - 1 2 7 1 7 45

T 1 1 I I

22 OUT OF 24 4-PACKS

AT LEAST / ^ 23 OUT OF 24 4-PACKS

DIODE SHORT PROTECTION MODULE FAILRATE ASSUME 50/50 FOR

SHORT TO GROUND OR OPEN DIODE FAILURE RATES:

OPEN 2.6 X 10-8 LOSS OF SHORT PROTECTION, 1.14 x lO ' '

, ALL 24 4-PACKS

J I I I I I I 10-°

1-13-69 UNC

10' CONVERTER MODULE FAILURE RATE (4 modules '4-pack)

Figure I I I - l l . The rmoe lec t r i c Conver ter Full-and Pa r t i a l -Power Reliabil i ty (Elect r ica l )

AI-AEC -MEMO-1 2717 46

c a p a b i l i t y . A s h o r t - c i r c u i t to g round wi th in any c o n v e r t e r m o d u l e could c a u s e

a l m o s t t o t a l l o s s of power c a p a b i l i t y wi thout s o m e m e a n s of i s o l a t i n g the faul t .

To p r o t e c t a g a i n s t the s h o r t - c i r c u i t cond i t ion , each 4 - p a c k a s s e m b l y i s d i o d e -

p r o t e c t e d so tha t a s h o r t to g r o u n d wi l l only c a u s e the l o s s of the r e s p e c t i v e 4 -

pack . The add i t ion of d iodes c a u s e s a s l igh t i n c r e a s e in o p e n - c i r c u i t h a z a r d

due to the p o s s i b i l i t y of a d iode f a i l u r e . In m a n n e d s y s t e m s the d iodes would

be r e a d i l y a c c e s s i b l e for r e p l a c e m e n t , but the p o s s i b i l i t y h a s not been con

s i d e r e d in t h i s a n a l y s i s .

In a p a p e r p r e s e n t e d at WESCON in Augus t 1962 by D, R. E a r l e s and M. F .

E d d i n s t i t l e d " F a i l u r e T h e r b l i g F a i l u r e R a t e s " it i s e s t i m a t e d tha t power d iodes

have the m o d e f a i l u r e - r a t e s shown in Tab le I1I-6,

T A B L E III-6

P O W E R DIODE " T H E R B L I G " F A I L U R E - R A T E S

Mode F a i l u r e - R a t e x 10 / h r

Open

Dri f t

Leak

Sho r t

U n s t a b l e

0,026

0,02

0,005

0,021

0,068

a s s u m e d l o s s of s h o r t - c i r c u i t p r o t e c t i o n

0,140

The f a i l u r e - r a t e of a diode which r e s u l t s in an open c i r c u i t i s a s s u m e d to - 8

be 2,6 X 10 f a i l u r e s p e r h o u r , and the f a i l u r e - r a t e which r e s u l t s in l o s s of _7

s h o r t - c i r c u i t p r o t e c t i o n i s a s s u m e d to be 1,14 x 10 f a i l u r e s p e r h o u r .

A s s u m p t i o n of f a i l u r e - r a t e s for the c o n v e r t e r e l e m e n t s i s c r i t i c a l to the

p o w e r r a t i n g v e r s u s r e l i a b i l i t y for the s y s t e m ; for t h i s r e a s o n the c o n v e r t e r

r e l i a b i l i t y h a s b e e n s tud ied p a r a m e t r i c a l l y . F o r s tudy p u r p o s e s i t w a s a s s u m e d

tha t the c o n v e r t e r m o d u l e f a i l u r e - r a t e s for both s h o r t i n g to g round and o p e n --7

c i r c u i t a r e equa l ; a to ta l f a i l u r e - r a t e for a m o d u l e of 2 x 10 f a i l u r e s p e r hour -7 -7

i n d i c a t e s f a i l u r e - r a t e s of 1 x 10 for s h o r t i n g and 1 x 10 for o p e n - c i r c u i t .

T h e s e f a i l u r e - r a t e s w e r e v a r i e d o v e r a r a n g e of s e v e r a l o r d e r s of m a g n i t u d e

for c a l c u l a t i n g c o n v e r t e r s y s t e m r e l i a b i l i t y . The r e s u l t s a r e shown in F i g u r e I I I - 1 1 .

A I - A E C - M E M O - 1 2 7 1 7 47

The p r e s e n t d e m o n s t r a t i o n l eve l of m o d u l e f a i l u r e - r a t e s i s in the r a n g e of _ 5

5 x 1 0 f a i l u r e s p e r h o u r . Th i s r e s u l t s f r o m l i m i t e d t e s t e x p e r i e n c e and by

no m e a n s r e p r e s e n t s an e x p e c t e d l o w e r l i m i t . It a p p e a r s r e a s o n a b l e to a s s u m e

tha t c o m p o n e n t t e s t i n g of m o d u l e s could d e m o n s t r a t e a m o d u l e f a i l u r e - r a t e to

b e , a t m o s t , 10 f a i l u r e s p e r h o u r t h r o u g h a c c e l e r a t e d o r m a r g i n t e s t s a s we l l

a s p e r f o r m a n c e e n d u r a n c e t e s t s . It i s a s s u m e d tha t s y s t e m d e v e l o p m e n t and _7

qua l i f i ca t ion t e s t s cou ld f u r t h e r r e d u c e t h i s l i m i t e s t i m a t e to abou t 2 x 1 0 f a i l u r e s p e r h o u r . The r e s u l t i n g c o n v e r t e r r e l i a b i l i t i e s shown in F i g u r e I I I - l l for

_7 a m o d u l e f a i l u r e - r a t e of 2 x 10 a r e the full-and p a r t i a l - p o w e r v a l u e s u s e d for

c a l c u l a t i n g s y s t e m r e l i a b i l i t y ,

E , SYSTEM T R A D E - O F F S

The r e f e r e n c e s y s t e m d e s c r i b e d above h a s b e e n s tud ied in d e t a i l for a

spec i f ic o p e r a t i n g poin t , but the s a m e d e s i g n c o n c e p t could be u s e d o v e r a wide

r a n g e of p o w e r r e q u i r e m e n t s . The r e s u l t s of a p a r a m e t r i c a n a l y s i s a r e p r e

sen t ed in th i s s e c t i o n for the a n t i c i p a t e d p o w e r r a n g e of i n t e r e s t for the 1 9 7 0 ' s .

In th i s s tudy the key c o m p o n e n t s (the r e a c t o r and the TE t u b u l a r m o d u l e s ) a r e

unchanged o v e r the e n t i r e r a n g e , and the o t h e r c o m p o n e n t s , e, g, p u m p s , e x

pans ion c o m p e n s a t o r s , and r a d i a t o r , a r e s i m i l a r in des ign bu t r e s i z e d for the

a p p r o p r i a t e p e r f o r m a n c e .

To f ac i l i t a t e the s y s t e m p a r a m e t r i c a n a l y s e s , a r e a c t o r — T E s y s t e m c o m

p u t e r code w a s d e v e l o p e d . The code input r e q u i r e m e n t s a r e c o n v e r t e r c l ad t e m

p e r a t u r e s , e l e c t r i c a l p o w e r l e v e l , c o n v e r t e r t u b u l a r m o d u l e c h a r a c t e r i s t i c s ,

and g e n e r a l s y s t e m g e o m e t r i c c o n s t r a i n t s . The c a l c u l a t e d r e s u l t s a r e the

t h e r m a l - p o w e r d i s t r i b u t i o n , s y s t e m o p e r a t i n g t e m p e r a t u r e s , r a d i a t o r a r e a ,

e f f i c i e n c i e s , f l o w r a t e s , p r e s s u r e d r o p s , and w e i g h t s . This code w a s u s e d to

d e t e r m i n e s y s t e m weigh t and a r e a c h a r a c t e r i s t i c s for power l e v e l s of 15, 25 ,

and 35 kwe a t r e a c t o r o u t l e t - t e m p e r a t u r e s of 1200, 1250, and 1300°F ; r e a c t o r

coo lan t A T ' S of 200, 250, and 3 0 0 ° F ; C a r n o t e f f i c i enc ies of 25 , 30, 35 , 40 , and

45%; and two r a d i a t o r d e s i g n s .

The two r a d i a t o r d e s i g n s w e r e s e l e c t e d a s a r e s u l t of d e t a i l e d r a d i a t o r

a n a l y s e s . T h e s e a n a l y s e s , d e s c r i b e d f u r t h e r in Sec t ion I V - D - 1 , d e t e r m i n e d

the r a d i a t o r we igh t vs a r e a t r a d e - o f f for the t h e r m a l cond i t ions of the r e f e r e n c e

A I - A E C - M E M O - 1 2 7 1 7 48

25-kwe s y s t e m . The r e f e r e n c e d e s i g n r a d i a t o r w a s p icked a t the m i n i m u m 2

we igh t point , which w a s found to o c c u r at about 1400 ft . This r a d i a t o r h a s a

fin e f f e c t i v e n e s s of 0,80 a t the r e f e r e n c e t e m p e r a t u r e s and a weight , inc luding 2

s t r u c t u r e , of 1.84 l b / f t , The o t h e r point on the c u r v e s e l e c t e d c o r r e s p o n d e d 2

to the a r e a , 1287 ft , a v a i l a b l e for the S a t u r n - I V B W o r k s h o p r a d i a t o r and r e p r e s e n t e d a h e a v i e r d e s i g n tha t could be bene f i c i a l w h e r e an a r e a l im i t a t i on w a s

invo lved . This r a d i a t o r had a fin e f f ec t i venes s of 0.87 at the r e f e r e n c e t e m p e r a -2

t u r e s and a we igh t of 2.19 lb / f t , By ana lyz ing s y s t e m s wi th both r a d i a t o r d e

s i g n s , a t r u e a r e a - w e i g h t t r a d e - o f f a t a given power l eve l can be ob ta ined . F i g

u r e I I I -12 shows how the fin e f f e c t i v e n e s s of the two d e s i g n s v a r i e s with co ld -

c lad t e m p e r a t u r e s a t the TE m o d u l e s .

F i g u r e s I I I - 1 3 , - 1 4 , and -15 show the r e s u l t s of the c o m p u t e r c a l c u l a t i o n s

for 15, 25 , and 35 kwe wi th the h e a v i e r r a d i a t o r . At e a c h C a r n o t eff ic iency

poin t , s y s t e m c h a r a c t e r i s t i c s w e r e d e t e r m i n e d for r e a c t o r coo lan t A T ' S of 200,

250, and 3 0 0 ° F . The AT t h a t r e s u l t e d in m i n i m u m weight was s e l e c t e d and is

shown on the f i g u r e s . In a l l c a s e s the r e f e r e n c e c o n v e r t e r t ubu l a r modu le d e s i g n

w a s he ld fixed wi th the n u m b e r of t u b u l a r m o d u l e s and o p e r a t i n g t e m p e r a t u r e s

v a r y i n g . As C a r n o t e f f ic iency d e c r e a s e s , the r a d i a t o r t e m p e r a t u r e i n c r e a s e s

and r a d i a t o r fin e f f e c t i v e n e s s d e c r e a s e s . Th i s effect , coupled with an a s s o c i a t e d

d e c r e a s e in c o n v e r t e r dev i ce e f f ic iency , r e s u l t s in m i n i m u m r a d i a t o r a r e a o c

c u r r i n g a t C a r n o t e f f i c i enc i e s above the u s u a l 20%.

As C a r n o t e f f ic iency i n c r e a s e s , the coo lan t AT a s s o c i a t e d wi th m i n i m u m

we igh t d e c r e a s e s b e c a u s e the r e a c t o r t h e r m a l - p o w e r d e c r e a s e s ; th i s r e s u l t s

in l ower f l o w r a t e s and p r e s s u r e d r o p , and r e d u c e d p u m p i n g - s y s t e m weigh t .

S i m i l a r c u r v e s w e r e g e n e r a t e d for the l i g h t e r - w e i g h t r a d i a t o r de s ign . The

two s e t s of c u r v e s w e r e c o m b i n e d , a s i l l u s t r a t e d in F i g u r e I I I -16 , and the

enve lope of m i n i m u m we igh t e s t a b l i s h e d . F i g u r e s I I I -17 , - 1 8 , and -19 show

t h e s e m i n i m u m - w e i g h t e n v e l o p e s a t power l e v e l s of 15, 25 , and 35 kwe.

F i g u r e s I I I -20 , - 2 1 , and -22 show how s y s t e m weight , a r e a , and t h e r m a l

po-wer v a r y wi th e l e c t r i c a l power for m i n i m u m - w e i g h t s y s t e m s . T h e s e c u r v e s

w e r e e s t a b l i s h e d by s e l e c t i n g the m i n i m u m - w e i g h t point for e a c h r e a c t o r o u t l e t -

t e m p e r a t u r e on F i g u r e s I I I -17 , - 1 8 , and -19 and t abu la t ing the a s s o c i a t e d r a d i a t o r

A I - A E C - M E M O - 12717 49

100 200 300 400 500 600 700 COLD-JUNCTION TEMPERATURE "F

1 15 69 UNC 7759-5273

Figure III-12, Radiator F m Effectiveness

1

CARNOT EFFICIENCY %s

T -r

Mr

REACTOR OUTLET TEMPERATURE °F

'25

REACTOR COOLANT AT 2 5 0 ° F - H 200° F = A

X J . X 600 800 1000

RADIATOR AREA, ft2

1200 1400

7759-5274

Figure III-13. 15-kwe System Weight and Area


I J -

45 CARNOT EFFICIENCY, %

REACTOR COOLANT A T • = 300"F • = 250''F A = 200''F

1000 1200 1400 1600 1800 2000

RADIATOR AREA, ft^

2200 2400

1-13-69 UNC 7759-5275

Figure III-14. 25-kwe System Weight and Area

1 1 1 r

_-CARN0T EFFICIENCY, %

Lu-L n » 101

REACTOR COOLANT AT

• 300OF

• 250°F

A 200°F

J - J . 0 ' 1800 2000 2200

1-15-69 UNC

2400 2600 2800

RADIATOR AREA, ft2

3000 3200 3400

7759-5276

Figure III- 15. 35-kwe System Weight and Area

AI-AEC-MEMO-12 717 51

1 1 r

, CARNOT EFFICIENCY,".

4^r

• = 300°F • = 250° F A = 200°F

J - J -1200 1400 1600 1800

RADIATOR AREA, ft^

2000 2200

Figure III-16. 25-kwe System, 1250°F Reactor Out le t -Temperature

6 -

5 -

REACTOR OUTLET TEMPERATURE, OF

o ^ r J . _L J -400 600 800 1000

RADIATOR AREA, ft^

1200 1400

Figure III-17. 15-kwe System Weight and Area (Unshielded)


10

REACTOR OUTLET TEMPERATURE (op)

360

320 |_ X

o LU

280 I

240

2400

RADIATOR AREA (fr)

Figure III-18.

8-JY25-119-42

25-kwe System Weight and Area (Unshielded)

10

oV/J _L J_ 0 1600

1 14 69 UNC

1800 2000 2200 2400 2600 2800 F.2

3000 3200 3400 3600

7759 5280 RADIATOR AREA ft

Figure III-19. 35-kwe System Weight and Area (Unshielded)


9 -

REACTOR OUTLET TEMPERATURE, °F

20 25 30 35 ELECTRICAL POWER kwe

1 14 69 UNC 7759-5281

Figure III-20. System Minimum Weight

1-14-69 UNC

20 25 ELECTRICAL POWER, kwe

30 35

7759 5282

Figure I I I -21 . System Radiator Area , Minimum-Weight Systems


° 5

3 -

20 25 ELECTRICAL POWER, kwe

1-14-69 UNC

30 35

7759-5283

Figure III-22. Reactor Thermal Power, Minimum-Weight Systems

a rea and r eac to r the rmal power. Thermal power in Figure III-22 is shown as

a band because of the scat ter in the calculated points and the small variation

with t e m p e r a t u r e . It should be noted that slight differences in the minimum-

weight values shown on the p a r a m e t r i c curves and the weight es t imates for the

re ference sys tem a re due to c loser definition and refinement of the la t ter .

The inherent modular i ty of the r eac to r — TE sys tem and its adaptability

to any po'wer level over a wide range of in te res t is c lear ly shown by the resu l t s

of this ana lys is .


TABLE IV-1

SNAP REACTOR OPERATING EXPERIENCE

R e a c t o r Date C r i t i c a l /

Shutdown

T h e r m a l P o u ' e r (kwt)

T e m p e r a t u r e (°F)

T h e r m a l E n e r g y

(kwt -h r )

T i m e at P o w e r and T e m p e r a t u r e

> I

>

O

o

-J

S N A P E x p e r i m e n t a l R e a c t o r (SER)

SNAP D e v e l o p m e n t a l R e a c t o r (SDR)

SNAP 8 E x p e r i m e n t a l R e a c t o r (S8ER)

SNAP lOA F l i gh t S y s t e m No. 3 (S lOA-FS-3 )

SNAP lOA F l i g h t Systemi No. 4 (S lOA-FS-4 )

S e p t e m b e r 1959/ D e c e m b e r I960

A p r i l 1 9 6 1 / D e c e m b e r 1962

May 1963 / A p r i l 1965

J a n u a r y 1965 / M a r c h 1966

A p r i l 1965 / May 1965

50

65

600

43

1200

1200

1300

1000

1000

225,000

273,000

5,100,000

382,944

41 ,000

1800 h r a t 1 2 0 0 ° F 3500 h r above 9 0 0 ° F

2800 h r at 1 2 0 0 ° F 7700 h r above 9 0 0 " F

1 y r a t 1 3 0 0 ° F and 400 to 600 kwt

10,005 h r

43 days

IV. SUBSYSTEMS

A. R E A C T O R / S H I E L D ASSEMBLY

1. T e c h n o l o g y S ta tu s

The r e a c t o r d e s i g n u s e d for t h i s s y s t e m s tudy i s b a s e d l a r g e l y on the t e c h

nology deve loped o v e r the p a s t 10 y e a r s in the SNAP R e a c t o r P r o g r a m . Dur ing

th i s t i m e 15 r e a c t o r s h a v e b e e n bu i l t for d e v e l o p m e n t , qua l i f i ca t ion , and flight

t e s t s ; f ive h a v e b e e n o p e r a t e d in s u s t a i n e d n u c l e a r power t e s t s , and the o the r

t en w e r e u s e d for n o n - n u c l e a r d e v e l o p m e n t and qua l i f i ca t ion t e s t s . In addi t ion ,

m a n y h u n d r e d s of t h o u s a n d s of t e s t h o u r s h a v e been a c c u m u l a t e d on r e a c t o r

c o m p o n e n t s . T a b l e IV-1 s u m m a r i z e s the n u c l e a r t e s t o p e r a t i o n e x p e r i e n c e ,

which t o t a l s about 3 5,000 h r to d a t e . The one y e a r of o p e r a t i o n of the SNAP 8

E x p e r i m e n t a l R e a c t o r (S8ER) a t power l e v e l s b e t w e e n 400 and 600 kwt at 1300°F

NaK ou t l e t t e m p e r a t u r e and the con t inuous 10 ,000-hour o p e r a t i o n of the SNAP

1 OA r e a c t o r a s a p a r t of a c o m p l e t e r e a c t o r — T E s y s t e m t e s t a r e c o n s i d e r e d to

be of p a r t i c u l a r s i g n i f i c a n c e .

The s ix th r e a c t o r t e s t i s c u r r e n t l y be ing s t a r t e d on the SNAP 8 D e v e l o p

m e n t a l R e a c t o r (S8DR) shown wi th o n e - h a l f the r e f l e c t o r r e m o v e d in F i g u r e I V - 1 .

The t e s t ob j ec t ives inc lude 10,000 h r of h i g h - p o w e r o p e r a t i o n , 500 h r of which i s

a t 1000 kwt, 1 1 0 0 ° F , and the r e m a i n i n g 9500 h r at 600 kwt, 1 3 0 0 ° F . In add i t ion ,

s e v e r a l shutdown and r e s t a r t t e s t s a r e s c h e d u l e d .

A s a r e s u l t of the d e v e l o p m e n t and t e s t e x p e r i e n c e ga ined fronn the SNAP

p r o g r a m s , the t echno logy s t a t u s of the z i r c o n i u m h y d r i d e type r e a c t o r i s c o n s i d

e r e d to be s\ifficiently a d v a n c e d to a s s u r e i t s a v a i l a b i l i t y for space m i s s i o n s in

the e a r l y to m i d - 1 9 7 0 ' s ,

2. R e a c t o r S u b s y s t e m D e s c r i p t i o n and P e r f o r m a n c e

P r e l i m i n a r y d e s i g n and d e v e l o p m e n t w o r k con t inues on the r e f e r e n c e z i r

c o n i u m h y d r i d e r e a c t o r . I ts d e s i g n h a s b e e n u s e d for a l l of the r e a c t o r — T E

s y s t e m s s tud ied and p r e s e n t e d in th i s r e p o r t .

The r e f e r e n c e z i r c o n i u m h y d r i d e r e a c t o r des ign , i l l u s t r a t e d in F i g u r e I V - 2 ,

i s s i m i l a r to the S8DR, e x c e p t for m o d i f i c a t i o n s i n c o r p o r a t e d to m a n r a t e the

s y s t e m and p e r m i t o p e r a t i o n wi th in an e n c l o s e d sh i e ld . F o r e x a m p l e , the n u m

b e r of f u e l - m o d e r a t o r e l e m e n t s h a s been i n c r e a s e d f r o m 211 to 295 and the

A I - A E C - M E M O - 1 2 7 1 7 57

F i g u r e I V - 1 , SNAP 8 D e v e l o p m e n t R e a c t o r Ground T e s t A s s e m b l y

n u m b e r of c o n t r o l drumis h a s been i n c r e a s e d f r o m 6 to 10 to p r o v i d e h i g h e r d e -

d e s i g n m a r g i n s and a w i d e r r a n g e of power and l i f e t i m e c a p a b i l i t i e s . In a d d i

t ion, the r e f l e c t o r / c o n t r o l - d r u m d e s i g n h a s been changed to p c r i n i t cool ing by

the l i q u i d - m e t a l coo lan t e n t e r i n g the r e a c t o r , s i nce the r e f l e c t o r cannot be

cooled by d i r e c t r a d i a t i o n to s p a c e a s h a s b e e n the c a s e with p r e v i o u s SNAP

r e a c t o r s .

The rninimiumL p e r f o r m a n c e ob jec t ive for the r e a c t o r i s to p r o v i d e 600 kw of

t h e r m a l power a t a coolant o u t l e t - t e m p e r a t u r e of 1300° F for 20,000 h r . The

c a l c u l a t e d p e r f o r m a n c e enve lope i s shown in F i g u r e I V - 3 .

The r e a c t o r con f igu ra t ion is shown in F i g u r e I V - 4 . Th i s r e a c t o r , l ike a l l

p r e c e d i n g z i r c o n i u m h y d r i d e r e a c t o r s , u s e s the s o d i u m - p o t a s s i u m i e u t e c t i c

N a K - 7 8 a s the coo lan t . The NaK e n t e r s the b a s e of the r e a c t o r v e s s e l at 1100°F

and flows a r o u n d d r y w e l l s which con ta in the l e f l e c t o r c o n t r o l d r u m s . The

A I - A E C - M E M O - 1 2 7 1 7

58

REFLECTOR COOLING PASSAGE

FUEL ELEMENT

FIXED REFLEQOR

CONTROL DRUM ACTUATOR

BEARING

BeO-POISON CONTROL DRUM

DIMENSIONS

HEIGHT-36 1/4 m DIAM - 21 5/8 m

OUTLET PIPE (TYPICAL)

Figure IV-2. Zirconium Hydride Reactor , Reference Design


IbUU

1200

900

600

300

0

-

. _ /

-

-

—

-

1 ' 1 ' ,1800 F MAXIMUM BeO

/ / J...^

1

S. FUEL GROWTH ANON. X REACTIVITY LIMITS \ .

REFERENCE ^ v THERMOELECTRIC Q X>, SYSTEM DESIGN ^

REACTOR PERFORMANCE EVALUATION AREA

t

1 ' 1 '

x

1100 1300

1000°F INLET 1200°F OUTLET

°F INLET "F OUTLET

FUEL PERFORMANCE

• S8DR GROWTH MODEL • S8DR PREPRODUCTION H2 LOSS

1

-

—

-

-

10 000 20 000 30,000

OPERATING TIME hr

40 000 50 0 0 0

8 M21 048 12A

Figure IV-3 . Per formance Envelope, Reference ZrH Reactor

SECTION

295 FUEL ELEMENTS

COOLANT PASSAGE

FIXED REFLECTORS (BeO or Be)

tLEVATION

22 00 DIA-

Figure IV-4. ZrH Reactor Reference Design

8 A30 075 2


y

coo l an t flow i s t u r n e d 180° , p a s s e s o v e r the fuel e l e m e n t s , and l e a v e s the r e a c

to r v e s s e l at 1 3 0 0 ° F . The fuel e l e m e n t s in the c o r e a r e spaced in a nonun i fo rm

h e x a g o n a l a r r a y to p r o v i d e each e l e m e n t with a coolan t flow a p p r o x i m a t e l y p r o

p o r t i o n a l to the pov/er g e n e r a t e d in the e l e m e n t . The n o z z l e - t o - n o z z l e p r e s s u r e -

d r o p of the r e a c t o r i s 0.65 p s i a t the n o r m a l f l owra t e of 13.0 l b / s e c . Type 316

s t a i n l e s s s t e e l is u s e d a s a s t r u c t u r a l m a t e r i a l for the r e a c t o r v e s s e l and

i n t e r n a l s .

The r e a c t o r fuel m a t e r i a l i s a z i r c o n i u m - u r a n i u m a l loy which h a s b e e n h y -22 3

d r i d e d to a h y d r o g e n con ten t of 6,3 x 10 a t o m s / c m (the H^ content in cold 22

w a t e r i s about 6.6 x 10 ). T h i s fuel m a t e r i a l i s qui te s t ab le in the expec t ed

t e m p e r a t u r e and r a d i a t i o n e n v i r o n m e n t and i t s p e r f o r m a n c e h a s been wel l c h a r

a c t e r i z e d a s a r e s u l t of the o p e r a t i o n of five SNAP r e a c t o r s p lus m a n y i n - p i l e

i r r a d i a t i o n e x p e r i m e n t s . The fuel i s con ta ined in a H a s t e l l o y - N c ladding tube

which i s coa ted on the i n s i d e with a c e r a m i c m a t e r i a l to inhibi t the l o s s of H^

m o d e r a t o r f r o m the fuel r o d .

The m a j o r change f r o m p r e v i o u s Z r H r e a c t o r s l i e s in the d e s i g n of the r e

f l e c t o r c o n t r o l s y s t e m . The SNAP 1 OA and SNAP 8 r e a c t o r s w e r e des igned to

o p e r a t e in a s h a d o w - s h i e l d e d con f igu ra t i on . The c o n t r o l d r u m s w e r e s e m i c y l i n -

d e r s of b e r y l l i u m s u r r o u n d i n g the c o r e which could be r o t a t e d to i n c r e a s e or d e

c r e a s e the n e u t r o n l e a k a g e f r o m the s y s t e m . The r e f e r e n c e con t ro l s y s t e m for

th i s r e a c t o r i s d e s i g n e d to o p e r a t e i n s i d e a sh ie ld which c o m p l e t e l y s u r r o u n d s

the r e a c t o r . T e n c y l i n d r i c a l r e f l e c t o r po i son c o n t r o l d r u m s a r e moun ted in

d r y w e l l s cooled by the i n l e t NaK. N e u t r o n - l e a k a g e c o n t r o l i s a c c o m p l i s h e d in

th i s c a s e by r o t a t i n g the d r u m f r o m p o s i t i o n s w h e r e n e u t r o n - r e f l e c t o r m a t e r i a l

i s ad j acen t to the c o r e to p o s i t i o n s w h e r e n e u t r o n - a b s o r p t i o n m a t e r i a l (poison)

i s a d j a c e n t .

The c o n t r o l d r u m s wi l l o p e r a t e a t r e l a t i v e l y h igh t e m p e r a t u r e s (1500 to

1800°F) b e c a u s e the i n t e r n a l n u c l e a r h e a t g e n e r a t e d m u s t be t r a n s f e r r e d by r a d

i a t i on to the w a l l s of the d r y w e l l , which a r e cooled by 1100°F NaK. B e r y l l i u m

oxide i s u s e d a s the r e f l e c t o r m a t e r i a l in th i s h i g h - t e m p e r a t u r e e n v i r o n m e n t .

The s e l e c t e d po i son m a t e r i a l i s e u r o p i u m - o x i d e d i s p e r s e d in n i cke l and h igh-

s t r e n g t h n i o b i u m a l l o y s a r e p lanned for s t r u c t u r a l u s e .

A I - A E C - M E M O - 1 2 7 1 7

61

The c o n t r o l d r u m r o t a t e s on a s e t of b a l l - a n d - s o c k e t b e a r i n g s . L ike the

S8DR, an a l u m i n u m - o x i d e - c o a t e d shaft r o t a t e s in a c a r b o n - g r a p h i t e ba l l

moun ted in a s o c k e t coa t ed with a l u m i n u m ox ide . The m a x i m u m b e a r i n g t e m

p e r a t u r e i s e x p e c t e d to be b e l o w 1 3 5 0 ° F , T e s t i n g of th i s type of b e a r i n g h a s

b e e n conduc ted a t t e m p e r a t u r e s up to 1 5 0 0 ° F . The c o n t r o l d r u m wil l be r o

ta ted by a n S8DR a c t u a t o r which h a s been modi f ied s l i gh t ly for th i s a p p l i c a t i o n .

The a c t u a t o r o p e r a t i n g t e m p e r a t u r e wil l be l e s s than tha t e x p e c t e d on the S8DR,

due to i t s l o c a t i o n ou t s ide the s h i e l d .

F o r c o n t r o l and m o n i t o r i n g p u r p o s e s a d r u m p o s i t i o n i n d i c a t o r wil l be in

c o r p o r a t e d in to the s y s t e m . Th i s v/ill be l o c a t e d in a cool p a r t of the s p a c e

c ra f t and v/ill ob ta in i t s r e a d i n g by count ing p u l s e s to the a c t u a t o r s . A s ing le

l i m i t s'witch on e a c h d r u m , a c t u a t e d v/hen the d r u m i s in the l e a s t r e a c t i v e

pos i t i on , -will p r o v i d e a s e c o n d a r y check on the pos i t i on i n d i c a t o r and wil l s a t

is fy the p r o b a b l e l aunch pad r e q u i r e m e n t of hav ing a p o s i t i v e i nd i ca t i on that the

r e a c t o r i s in a safe cond i t ion .

The sh ie ld con f igu ra t i on wi l l be dependen t upon the p a r t i c u l a r m i s s i o n for

which the r e a c t o r i s to be u s e d . In g e n e r a l , the r e a c t o r v e s s e l wi l l be s u r

rounded by a g a m m a sh i e ld of e i t h e r t u n g s t e n or m o l t e n l ead e n c a p s u l a t e d in

s t e e l . A th ick l a y e r of i n s u l a t i o n -will s e p a r a t e the h i g h - t e m p e r a t u r e Pb f r o m

a r e g i o n of LiH n e u t r o n s h i e l d i n g . Th i s type of t w o - r e g i o n sh ie ld i s a d e q u a t e

for a p p l i c a t i o n s w h e r e the a l l o w a b l e d o s e r a t e s a r e h igh o r the s e p a r a t i o n d i s

t ance f r o m the p e r s o n n e l i s l a r g e (e. g, m a n n e d l u n a r b a s e ) . In the c a s e of a

shaped 47r sh ie ld for a m a n n e d s p a c e s t a t i on , the sh i e ld ing wil l be m u c h t h i c k e r

in the d i r e c t i o n of the s t a t i o n . N o r m a l l y the f i r s t two r e g i o n s wil l be followed

by a g a l l e r y conta in ing the p o w e r - c o n v e r s i o n s y s t e m (PCS) . Aft of the g a l l e r y

wi l l be a s econd g a m m a sh ie ld of d e p l e t e d U and a s e c o n d LiH n e u t r o n sh i e ld .

The LiH s h i e l d s a r e c a s t in s t a i n l e s s - s t e e l c o n t a i n e r s s t r e n g t h e n e d by in

t e r n a l s h e l l s and s t r i n g e r s . The sh ie ld a s s e m b l y i s n o r m a l l y the h e a v i e s t uni t

in the r e a c t o r s y s t e m and p r o v i d e s p r i m a r y s t r u c t u r e for the e n t i r e s y s t e m .

The weigh t of the r e a c t o r , P C S , and sh ie ld i s c a r r i e d t h r o u g h the sh ie ld to a

load r ing which i s m a t e d to the v e h i c l e . T y p i c a l s h i e l d s a r e d e s c r i b e d in S e c

t ion V for spec i f i c m i s s i o n a d a p t a t i o n s of the s y s t e m .

A I - A E C - M E M O - 1 2 7 1 7

62

Some of the more significant design p a r a m e t e r s for the reac tor subsystems

a r e given in Table IV-2, In general the design involves very few deviations from

the s t a t e -o f - the -a r t as exemplified by the S8DR. In a r ea s where conditions a r e

more severe than S8DR, development p rograms a r e underway to establ ish the

required capabi l i t ies ,

B, THERMOELECTRIC CONVERTER

1. TE Module Technology Status

The objective of the Compact TE Converter P r o g r a m begun by the AEC in

mid-1965 is to develop a h igh-per formance re l iable long-life conver ter module

for application to space s y s t e m s . The basic element in the p rogram being con

ducted for the AEC by Westinghouse is the tubular TE module shown schemat

ically in Figure IV-5 . It has a TE circui t encapsulated between its inner and

outer clads in a completely compact void-free design that is s t ructura l ly rugged.

Because of the unique design of the tubular module, radial heat flows from the

inner to the outer surface without the requi rement of bonded joints . The TE

circui t is completed through a se r i e s of washers and r ings . The a l te rna te P -

and N-type washers a r e separa ted by thin washers of natural mica for e lec t r ica l

insulation. Hot- and cold-conductor r ings span adjacent PbTe washers to form

a serpentine cur ren t flowpath. The c i rcui t is e lect r ical ly isolated from the

s t ruc tura l claddings by thin s leeves of boron nitr ide that provide good thermal

contact between the r ings and the c lads .

Table IV-3 s u m m a r i z e s the test experience accumulated through mid-1968

with the tubular modules . Since the p rog ram began in mid-1965 approximately

eighty tubular modules have been fabricated, and fifty have been life-tested.

The remainder were subjected to special dest ruct ive examination, s h o r t - t e r m

performance t e s t s , and special ones such as cyclic t empera tu re and vibration

t e s t s . To maximize the benefits from each module life-tested an average hot-

clad t empera tu re of 1000°F was chosen at the beginning of the p rogram as the

basic test condition. There a r e axial t empera tu re gradients in the inner clad,

however, because of end effects. In a typical test setup an e lec t r ica l heater is

inser ted into the bore of the module and heat is t r ans fe r red to the inner clad

through NaK fluid which fills the cavity between the hea te r and module. Because


TABLE IV-2

REFERENCE ZrH REACTOR DESIGN PARAMETERS

1. Gene ra l P e r f o r m a n c e

Design t h e r m a l power

Design o u t l e t - t e m p e r a t u r e

T e m p e r a t u r e r i s e

Design l i fe t ime

Coolant f lowrate

P r e s s u r e d rop

Operat ing p r e s s u r e capabi l i ty

2. Fuel and Core In te rna ls

Number of fuel e lements

ZrH hydrogen content

Uran ium content

H y d r o g e n - b a r r i e r m a t e r i a l

Cladding m a t e r i a l

Cladding th ickness

Burnable poison m a t e r i a l

Active fuel length

Overa l l (f lat- to-flat) e l ement length

Outside d i ame te r of fuel e lement

F u e l - e l e m e n t spacing (variable for flow control)

In ternal re f lec tor m a t e r i a l

In ternal r e f l ec to r cladding

Gr idp la te m a t e r i a l

Core shel l , ins ide d i ame te r

Core shell th ickness

Core shell m a t e r i a l

Reac tor coolant m a t e r i a l

600 kwt

1300°F

200°F

26,000 h r

49,000 I b / h r

0.65 psi

35 ps ia

295 22

6.3 X 10^" a t o m s / c m

10.5 wt%

SCB-1

Has te l loy -N

0.015 in.

Gd-155

16.8 in.

17.5 in.

0.570 in.

0.025 to 0.045 in.

BeO

316 SS

316 SS

11.4 in.

0.030 in.

316 SS

NaK-78

3. Reac to r V e s s e l

Outside d i a m e t e r

Ves se l wall th ickness

Inside d i a m e t e r of d r y wells

Drywell wall th ickness

Number of inlet and outlet nozzles

4. Reflector Control S y s t e m

Con t ro l -d rum type

Number of control d r u m s

Reflector m a t e r i a l

Poison m a t e r i a l

S t ruc tu re m a t e r i a l

Cladding m a t e r i a l

Drum d i a m e t e r

Drum length

S t ruc tu ra l s t rongback th ickness

c ladding th ickness

Drum bear ing shaft m a t e r i a l

C o n t r o l - d r u m ac tua to r

C o n t r o l - d r u m bea r ings

5. Shield

H i g h - t e m p e r a t u r e g a m m a shield

Lead conta iner m a t e r i a l

L o w - t e m p e r a t u r e g a m m a shield

Neu t ron-sh ie ld m a t e r i a l

LiH conta iner m a t e r i a l

22.0 in.

3 /16 in.

4.62 in.

0.065 in.

4 ea

Ref lec to r -po i son

10

BeO

60% Eu^Oj in Ni

Nb-10 W

Nb-1 Zr

4.5 in.

19.0 in.

0.25 in.

0.030 in.

Ta -10 W

Modified S8DR

Modified S8DR

Molten Lead

Croloy 2 - 1 / 4

Uran ium

LiH

316 SS


DESIGN FEATURES

FULLY ENCAPSULATED

FULLY COMPACTED-VOID FREE

STRUCTURALLY RUGGED

NO BONDED JOINTS

USES PbTe AT HIGH TEMPERATURE

MECHANICALLY AND ELECTRICALLY ADAPTABLE

LONGEVITY- SHELF AND OPERATING

OUTER CLADDING

ELECTRICAL CONDUCTOR

THERMOELECTRIC MATERIAL

ELECTRICAL INSULATION

INNER CLADDING 612249-4C

Figure IV-5 . Tubular Thermoelec t r ic Module

TABLE IV-3

TUBULAR MODULE TEST EXPERIENCE

T e m p e r a t u r e , H o t ( ° F )

1000

1100

1125

1150

1200

1250

1300

T e m p e r a t u r e , M a x i m u m

( ° F )

1050

1150

1175

1200

1270

1340

1350

N u m b e r of M o d u l e s

58

9

4

2

12

1

2

T o t a l T i m e ( h r )

2 1 7 , 1 0 0

2 5 , 8 0 0

5 ,500

6 , 0 0 0

1 0 , 3 0 0

1,200

5 ,900

2 7 1 , 2 0 0

M a x i m u m T i m e ( h r )

2 4 , 6 0 0

9 , 5 0 0

2 , 0 0 0

4 , 0 0 0

1,700

1,200

4 , 2 0 0


of end l o s s e s , peak t e m p e r a t u r e s a r e about 5 0 ° F h i g h e r than a v e r a g e t e m p e r a

t u r e s .

2. T u b u l a r Module

The r e f e r e n c e t u b u l a r T E m o d u l e s e l e c t e d for the r e a c t o r — T E s y s t e m is

shown in F i g u r e I V - 6 . A s u m m a r y of i t s p e r f o r m a n c e and d e s i g n c h a r a c t e r i s

t i c s i s g iven in T a b l e I V - 4 . The m o d u l e h a s an ID of 0,75 in, , an OD of 1.50 in . ,

and an a c t i v e T E c i r c u i t l eng th of 15,07 in . I ts o v e r a l l l eng th inc luding i n n e r -

c lad e x t e n s i o n s i s 19.0 in .

The r e f e r e n c e m o d u l e -was c h o s e n a f t e r a de t a i l ed p a r a m e t r i c s y s t e m s tudy .

Befo re a n a l y z i n g the s y s t e m t r a d e - o f f s , s e v e r a l m o d u l e d e s i g n c r i t e r i a w e r e

fixed b a s e d on the p r e s e n t s t a t e - o f - t h e - a r t and r e a l i s t i c p r o j e c t i o n s of the t e c h

nology which could be m a d e •with a h igh d e g r e e of con f idence . Th i s was n e c e s

s a r y b e c a u s e the ex i s t ing d e v e l o p m e n t p r o g r a m for t u b u l a r m o d u l e s h a s b e e n a

b r o a d l y b a s e d t echno logy effor t not spec i f i ca l l y o r i e n t e d t o w a r d m o d u l e s t a i l o r e d

for r e a c t o r s y s t e m a p p l i c a t i o n s , A s u m m a r y of the c r i t e r i a a s s t a t ed for the

s tudy fo l lows :

1) TE M a t e r i a l s , S i n g l e - p i e c e 2P and t w o - p i e c e 2N-3N w a s h e r s wil l be

the b a s i s for m o d u l e p e r f o r m a n c e c a l c u l a t i o n s .

2) Cladding M a t e r i a l s . H i g h - s t r e n g t h Incone l or i t s m e c h a n i c a l e q u i v a

len t ( c o n s i s t e n t wi th m i n i m u m - w e i g h t m o d u l e s ) wi l l be c o n s i d e r e d for

modu le i n n e r and o u t e r c l add ing . F o r p a r a m e t r i c c a l c u l a t i o n s the

c ladding wi l l be s i zed p r o p e r l y to e n s u r e suff ic ient con tac t p r e s s u r e s

u n d e r o p e r a t i n g c o n d i t i o n s .

3) End C l o s u r e s , The r e f e r e n c e m o d u l e v/ill be b a s e d on an e n d - c l o s u r e

d e s i g n that y i e l d s n o m i n a l h e a t l o s s e s of 100 w a t t s p e r end.

4) Module Ac t ive Leng th and V o l t a g e . F o r p a r a m e t r i c c a l c u l a t i o n s of

m o d u l e p e r f o r m a n c e and w e i g h t s , a fixed a c t i v e length of 15.0 in ,

and c o r r e s p o n d i n g 14.0 vo l t s at m a t c h e d - l o a d wil l be u s e d . The r a t i o

of t h e s e two v a l u e s is r e p r e s e n t a t i v e of n e a r - m a x i m u m vol t s p e r uni t

a x i a l l eng th tha t can be a t t a i n e d •within the c u r r e n t s t a t e - o f - t h e - a r t .

A I - A E C - M E M O - 1 2 7 1 7

66

O U T E R CLA>D

I NSULATINQ 5UEEVE

CONDUCTOR RING,

THeRMOEUECTRlC W A S H E R

— E L E : C T R I C A . L I N 5 U L ^ T O R

CONDUCTOR RINC,

- — I N S U L A T I N G , S L E E V E

N E R C L A D

- 8 T U R N S @ 1 SO P ITCH —

Figure IV-6. Converter Layout (Drawing No. 914E163)

AI-AEC-MEMO-1Z71 7

67

TABLE IV-4

CHARACTERISTICS OF REFERENCE TUBULAR MODULE

Power output, watts e lec t r ic

Efficiency, %

Voltage to matched-load, vdc

Internal r e s i s t ance , XI

Current , amp

Heat input, kwt

Mean hot-c lad t empera tu re , °F

Mean cold-clad t empera tu re , °F

Dry weight, lb

Envelope Dimensions (in. )

Inner d iameter

Outer d iameter

Total length

Active length

Radial Thickness (in. )

Cladding

Insulator

Conductor

Thermoe lec t r i c ma te r i a l

Inner

0.090

0.040

0.025

262

4.67

14.0

0.74J

18.7

5.61

1125

570

5.75

0.75

1.50

19.0

15.07

Outer

0.020

0.037

0.020

0.143


5) Module D i a m e t e r s . I D ' s f r o m 3 / 8 to 3 /4 in . wi l l be c o n s i d e r e d d u r

ing p a r a m e t r i c s t u d i e s . The c o r r e s p o n d i n g r a n g e for O D ' s -will be

f r o m 1.2 to 2.5 in .

6) Module D e g r a d a t i o n . It w a s a s s u m e d that by the e a r l y 1970 ' s h i g h -

t e m p e r a t u r e (1200 to 1250°F) m o d u l e s with l i t t l e or no d e g r a d a t i o n

wi l l be d e m o n s t r a t e d for l i f e t i m e s in e x c e s s of 10,000 h r . T h e r e f o r e

no spec i f i c v a l u e s of m o d u l e d e g r a d a t i o n w e r e u s e d in the s tudy . In

s t e a d , n o r m a l s y s t e m o p e r a t i n g t e m p e r a t u r e s w e r e e s t a b l i s h e d so

tha t s o m e d e g r a d a t i o n can be r e c o v e r e d by r a i s i n g the t e m p e r a t u r e s

•without e x c e e d i n g c o m p o n e n t l i m i t s .

Al though the c o n v e r t e r h o t - c l a d a v e r a g e t e m p e r a t u r e ob jec t ive i s 1 2 0 0 ° F ,

an a v e r a g e t e m p e r a t u r e of 1125°F w a s s e l e c t e d to a l low s o m e d e s i g n m a r g i n

and to a l low for d e g r a d a t i o n r e c o v e r y .

One c o n c l u s i o n of the s tudy w a s tha t a m i n i m u m OD for a g iven ID, or m i n -

imuna p r a c t i c a l T E e l e m e n t t h i c k n e s s , w a s d e s i r a b l e . T h i s r e s u l t e d in m i n i

m u m s y s t e m we igh t and r a d i a t o r a r e a , p r i m a r i l y b e c a u s e of the h i g h e r h e a t -

r e j e c t i o n t e m p e r a t u r e , and f ewer m o d u l e s b e c a u s e of g r e a t e r e l e c t r i c a l output

p e r m o d u l e . Ef f ic iency v/as m i n i m u m for th i s condi t ion , bu t s i n c e the r e a c t o r

i s not t h e r m a l - p o w e r - l i m i t e d th i s w a s not c r i t i c a l .

S y s t e m we igh t , r a d i a t o r a r e a , and e f f ic iency did not v a r y s ign i f i can t ly -with

c h a n g e s in ID when the e l e m e n t t h i c k n e s s w a s m a i n t a i n e d , bu t the p o w e r output

p e r m o d u l e i n c r e a s e d wi th i n c r e a s i n g ID. To m i n i m i z e the n u m b e r of m o d u l e s ,

then , the l a r g e s t ID a l l owab le wi th in the s tudy c r i t e r i a , 0.75 in . , was c h o s e n .

M i n i m i z i n g the n u m b e r of m o d u l e s i n c r e a s e s r e l i a b i l i t y by r e d u c i n g the n u m b e r

of we lds and the s y s t e m c o m p l e x i t y , bu t i t c an h a v e an a d v e r s e effect on p a r t i a l -

power r e l i a b i l i t y by i n c r e a s i n g the power l o s s with one m o d u l e f a i l u r e . F o r the

r a n g e of m o d u l e s i z e s s tud ied th i s w a s not ye t judged to be a p r o b l e m ; h o w e v e r ,

r e v i e w of the p a r t i a l - p o w e r r e l i a b i l i t y c u r v e s in Sec t ion I I I -D shows tha t f u r t h e r

s ign i f i can t r e d u c t i o n in the n u m b e r of m o d u l e s m a y not be d e s i r a b l e .

With the ID e s t a b l i s h e d , the m i n i m u m p r a c t i c a l OD of 1.5 in . and the a v e r

age c o l d - c l a d t e m p e r a t u r e of 5 7 0 ° F w e r e f ixed.

A I - A E C - M E M O - 1 2 7 1 7

70

3. Converter Module

a. Descript ion and Per formance

The re ference TE conver ter module consis ts of an assembly of 24 tubular

modules a r ranged into six subassembl ies of four tubular modules each. Each

4-pack is enclosed in a single metal jacket that provides containment for all

cold NaK flowing around the four modules . This a r rangement simplifies mani

folding and header r equ i rements for del ivery and removal of cold NaK to the in

dividual tubular modules . Cross-coupl ing of the hot- and cold-NaK manifolding

provides for the differential t he rmal expansion that occurs during startup and

other the rmal t r ans ien t s , and minimizes the rmal s t r e s s e s on the piping

assembly .

A cutaway of the converter module is shown in Figure lV-7 ( isometric) ;

for this orientat ion the tubular modules a r e standing on end with ver t ical cen ter -

l ines . The tubular modules provide the conver ter module s t ruc ture in the ve r

tical direct ion, the hot manifolds provide the longitudinal s t ruc tu re , and the

cold manifolds provide the t r a n s v e r s e s t ruc tu re . For specific applications the

orientation of the conver ter module and the layout of the inlet and outlet mani

folds can be modified to satisfy any unique requ i rement s . Discussion of the

present design, ho'wever, is predicated on the nominal orientation defined above.

The hot- loop NaK enters one end of each longitudinal manifold at the top

and flows to the other end. A portion of the flow exits downward from the man

ifold through each tubular module to the lo^wer longitudinal manifold where it is

collected and re turned to the r eac to r . The cold-loop NaK en te r s the bottom of

the divided outer can which c lus te r s each t r ansve r se group of modules into a

4-pack. Cold NaK then flows into annuli that surround each tubular module,

removes the waste heat from the modules , and is then collected in an exit man

ifold and pumped to the rad ia to r .

Each of the 24 tubular modules in the converter module contains a 0.5-in.-

diam rod that channels the hot NaK into an annular flowpath. A spiral-wound

wire centers the rod in the tubular module and provides a flowpath that ensures

c i rcumferent ia l distr ibution of the flow. Use of the 0.5-in. rod and spira l wire

se rves two purposes . F i r s t , it provides sufficient hydraul ic impedance within

the tubular module to ensure good flow distribution among the tubular modules.


COLD

CONVERTER MODULE 6.3 KWE

Figure IV-7. Converter Module Cutaway


TABLE IV-5

CONVERTER MODULE CHARACTERISTICS

Power output, kwe

Efficiency, %

Matched-load voltage, volts

Number of tubular modules

Number of modules e lec t r ica l ly in s e r i e s

Current per 4-pack, amp

Wet weight, lb 3

Volume, ft

Envelope d imensions , in.

Tempera tu re s (°F)

Inlet clad

Outlet clad

Mean clad

NaK flowrate, l b / s e c

P r e s s u r e drop, ps i

Energy Balance

Heat into conver ter module, kwt

P r i m a r y - h e a t l o s s e s , kwt

Heat del ivered to tubular modules , kwt

E lec t r i ca l power, kwe

Heat removed from conver ter module, kwt

6.3

4.6

56.0

24

4

18.7

284

3.4

12.5 X 19.5 X 24.0

Hot Loop

1225

1025

1125

3.03

0.28

Cold Loop

470

670

570

2.88

0.26

136,1

1.3

134.8

6.3

128.5

Second, it improves the convective heat t ransfer between the NaK and the mod

ule cladding. The calculated AT between bulk NaK and clad is 20°F with the

rod inse r t . Without the rod inser t the AT would be ~ 5 0 ° F and would impose a

significant t empera tu re penalty on the sys tem.

A summary of the conver ter module design and performance cha rac te r i s t i c s

is given in Table IV-5. For the selected sys tem operating t empera tu res each

converter module produces 6.3 kwe at a matched-load voltage of 56 volts. Four

AI-AEC-MEMO- 1 2717 73

tubular modules a r e a r ranged e lec t r ica l ly in se r i e s to yield 56 vol ts , and the

six 4-packs a r e connected e lec t r ica l ly in para l le l . The e lec t r i ca l network that

connects the four conver ter modules and the associa ted voltage regulation eqxiip-

ment is descr ibed in Section IV-B-4 .

The overal l efficiency of the conver ter module operating at 1125 and 570°F

mean hot - and cold-clad t e m p e r a t u r e s , respect ively , is 4.6%. This includes

heat los ses of 1,3 kwt in the p r imary - loop manifolding based on thermal i n t e r

change between the manifolds and the box that surrounds the conver ter module.

The heat balance of the module is given in Table IV-5 .

b . Mechanical Design

An engineering dra^wing of the reference converter module is sho-wn in F ig

u r e IV-8. A fundamental mechanical design requi rement is to provide for dif

ferential thermal expansion because the NaK loops operate at t empera tu re lev

els that differ by more than 500°F. The components must be carefully a r ranged

to allow for the result ing differential expansions.

The hot clads of the tubular modules a r e welded direct ly to the hot mani

folds which a r e free to expand in the longitudinal direct ion and space the 4-packs

as requi red . The hot clads separa te the upper and lower hot manifolds and a re

free to move these inanifolds as requi red by their thermal expansions. The 4-

pack cans operate at cold-loop t empera tu re and a r e attached direct ly to the cold

clads of the tubular modules . The t r a n s v e r s e spacing is thus freely adjusted by

the the rmal expansion of these cans . Suitable flexible connections a r e provided

to join the four hot- in le t manifolds to the common inlet header and the four hot-

exit manifolds to the exit heade r . Likewise, flexibility is provided in the con

nections to the cold-loop inlet and exit h e a d e r s .

Perhaps the most c r i t ica l design requi rement of the sys tem is absolute

containment of NaK in the loops. All loop connections a r e welded and emphasis

is placed on minimizing the number of welds and maximizing the quality of the

required welds. Some weight sacr i f ices were made to reduce the number of

welds such as using the coraplete can around each 4-pack r a the r than individual

tubes with t r a n s v e r s e h e a d e r s at top and bottom. The •weld quality was maxi

mized by providing for p r e - a s s e m b l e d components as much as possible before

genera tor inser t ion. Thus s t r e s s relief, aging, inspect ion, and p r e s s u r e t e s t

ing a r e possible and prac t ica l in most of the welds.


HTT

Figure IV-8. Converter Module Layout

(Drawing No. 939J385)

AI-AEC-MEMO-12717

75

The oval-shaped can w^hich surrounds the 4-pack is the basic building unit.

It is rolled and welded Inconel 718 with a nominal thickness of 0.100 in. This

h igh-s t rength m a t e r i a l is required to prevent bulging of the la rge flat s ides .

The top and bottom dividers and the baffle tubes a r e inser ted in these cans f i rs t .

Then the perforated cover -p la tes a r e seal-welded in place. These units can

then be s t r e s s - r e l i e v e d , aged, inspected, e tc . without fear of damaging gener

a to rs which have not yet been assembled into the pack.

At this point in the assembly sequence the tubular modules can be inser ted

and the tips of the cold clads welded to the can cover-p la tes to form a complete

4-pack. A possible a l te rna t ive would be to assemble the entire cold loop with

out g e n e r a t o r s . This would include the manifolds and the longitudinally flexible

shear m e m b e r s between cans . The assembled cold loop (without tubular mod

ules) could again be s t r e s s - r e l i e v e d , e tc . without fear of generator damage,

thereby maximizing weld quality in the cold loop.

For ei ther a s sembly method the ent i re cold-loop and generator assembly

will be built before the hot manifolds a r e welded on. The hot clads of the tubu

la r modules will be long enough to reach the hot manifolds without any in te r

mediate welds being requi red . The hot manifolds will be channel-shaped •with

one open side so that the clads can be welded to the inside of the manifold. This

is the only way that sa t is factory clad-weld accessibi l i ty can be obtained. Fin

ally the hot manifold cover -p la tes will be seal-welded to the open manifold sides

The assembly , as shown in F igure IV-8, has 202 cr i t ica l welds. Many of these

welds, however, can essent ia l ly be eliminated as potential problem a r ea s by the

use of manufacturing and inspection procedures which will guarantee their qual

ity to be near ly the same as the parent ma te r i a l .

Three mounting lugs a r e shown in the reference design. These lugs a r e

rigidly attached to the 4-pack cans . They will penetrate the cover at each end

and must move thermal ly re la t ive to the cover . One lug can be seal-welded to

the cover , but a sliding seal (or bellows) will be used at the other penetra t ions .

A suitable support linkage •will be requi red to proper ly mount the unit to the

spacecraft and allow for the rmal movement of the support lugs . This method of

support is p re l iminary and •will likely be changed as the constraints of specific

sys tem adaptations and the r e su l t s of further studies become available.


The stiffened shell which covers the ent i re conver te r module provides con

tainment of NaK in the event of a leak, thus avoiding subsequent e lec t r ica l shor t

ing of other conver ter modules . The cover cannot withstand significant in ternal

or external p r e s s u r e ; therefore , a vent has been provided for p r e s s u r e equali

zation during launch and to allow NaK vapor, in the event of a leak, to vent over

board or to a safe a r e a .

Because a tv/o-loop reac to r sys tem was selected for the reference configu

rat ion, an additional provis ion for containing the hot NaK in the converter mod

ule was briefly invest igated. Redundancy in containing the hot NaK is needed

because all four conver ter modules in the sys tem v/ill sha re a common hydraul ic

loop with the r eac to r . Therefore a single hydraul ic leak anywhere in the p r i

m a r y loop will cause fai lure of the complete sys tem. Over 80% of the p r i m a r y -

loop containment v/elds a r e associa ted •with these hot h e a d e r s . A conceptual

sketch shown in F igure IV-9 shows provisions for providing double containment

of the hot- loop h e a d e r s . The bello'ws sho^wn is to allow differential expansion

bet^ween the p r i m a r y and secondary containment. A conclusion of the brief in

vestigation is that double containment of these h e a d e r s is feasible, and can be

incorporated into the conver ter design.

F igure IV-9. Double Containment of Converter Module Header

1-13-69 UNC 7759-5284


c. Off-Design Pe r fo rmance

If the reference conver te r module is operated at t empera tu res other than

those selected for the sys tem design points, the power output, efficiency, and

voltage will vary .

F igure IV-10 shows the calculated variat ions in power output for mean hot-

clad t empera tu re s ranging from 1000 to 1225°F and for mean cold-clad t empera

tures from 400 to 700°F. Similar ly , for the same ranges of t empe ra tu r e s , off-

design values for efficiency and voltage a r e shown in F igures IV-11 and IV-12,

respect ive ly .

Although the final selection of axial-NaK AT in the converter module was

200°F, the design analys is was made , based on a tentative selection of 150°F.

By increas ing the AT in each loop from 150 to 200°F, the e lec t r ica l pe r fo rm

ance cha rac te r i s t i c s change by a negligible amount. Hydraulic p a r a m e t e r s ,

however, a r e significantly affected. F igure IV-13 shows the off-design var ia

tions in hot- and cold-NaK flowrates for the final selection of 200°F, while

Figure IV-14 indicates the values for the ea r l i e r 150°F AT. The p r e s s u r e -

drop variat ions a r e shown in Figure IV-15 as functions of flowrate with the

200°F A T design point indicated,

4. E lec t r ica l Network and Voltage-Regulation Equipment

The e lec t r ica l network for the re ference power sys tem provides shunt-

voltage regulation of the nominal 56.0 vdc output of the TE conver ter . A sche

mat ic d iagram of the network is shown in F igure IV-16. The 24 TE 4-packs

a r e connected to a common negative bus . The positive lead of each 4-pack is

routed individually to the power-conditioning equipment, all of which is located

in a low- tempera tu re environment . Each of the 24 4-packs has an open-circui t

voltage of 11 2 vdc at the re ference operating conditions. Based on the test ex

per ience of the compact conver ter development p rogram, this no-load voltage

will be near ly constant throughout the miss ion l i fet ime.

Shunt-voltage regulat ion was selected since the TE converter attains its

maximum rel iabi l i ty and inninimum degradation when it is operated at constant

t empera tu re conditions, i . e. without thermal t r ans ien t s . This operation is

attained when the e l ec t r i ca l load is held constant. Constant thermal- load oper

ation also simplifies the r eac to r controls , thereby improving overall sys tem

rel iabi l i ty and reducing weight.

AI-AEC-MEMO-12717

79

13 -

l400"F

24 TUBULAR MODULES WEIGHT: 284 lb AXIAL A T : 150°F

MEAN COLD-CLAD TEMPERATURE

l l - ^ I I 1000 1100 1200

HEAN HOT-CLAD TEMPERATURE, °F 1-13-69 UNC

1300

7759-5285

Figure IV-10. Conver ter Module Off-Design Power

AI-AEC -MEMO- 1 271 7 80

2l->V-1000

400OF

24 TUBULAR MODULES WEIGHT: 284 lb AXIAL AT: ISO^F

MEAN COLD-CLAD TEMPERATURE

1-13-69 UNC

1100 1200 MEAN HOT-CLAD TEMPERATURE, °F

7759-5286

Figure IV-11. Conver ter Module Off-Design Efficiency


400°F

500'JF

570°F

600°F

^EAN COLD-CLAD FEMPERATURE

24 TUBULAR MODULES WEIGHT: 284 lb AXIAL AT- 150"F

30 U ^ _L 1000 1300 1100 1200

MEAN HOT-CLAD TEMPERATURE,°F

1-13-69 UNC 7759-5287

Figure IV-12. Conver ter Module Off-Design Voltage

AI-AEC -MEMO-1 2717 82

5 0

4 0

< 30

o

2 0

1 0

I I MEAN COLO-SIDE WEIGHT OF 24 TUBULAR MODULES-284 lb TEMPERATURE °F

HOT-SIDE FLOWRATE COLD-SIDE FLOWRATE

J L 1000

1-13-69 UNC

1100 1200 MEAN HOT-CLAD TEMPERATURE, °F

1300

7759-5288

Figure IV-13. Conver ter Module Off-Design F lowra tes , Axial AT's Assumed Constant at 200° F


6 0

5 0

40

3 0

2 0

/ 700"F

MEAN COLD-SIDE TEMPERATURE

HOT-SIDE FLOWRATE COLD-SIDE FLOWRATE

^ 1000 1100 1200

MEAN HOT-CLAD TEMPERATURE "P

1-13-69 UNC

1300

7759-5289

Figure IV-14. Conver te r Module Off-Design Flowrates , Axial AT's Assumed Constant at 150° F

AI-AEC -MEMO- 12717 84

10

09

08 -

07

05 -

fc 05 -

04 -

03

02 -

01 -

•HOT SIDE COLD SIDE

A T - 200° F

2 3 4 NaK FLOWRATE, lb/sec

- L 6 7

7759-5290

Figure IV-15. Conver ter Module Hot- and Cold-Side P r e s s u r e Drops


POWER-GENERATION

24 FOUR-PACK

SUBASSEMBLIES

INTERNAL FAULT

PROTECTION 24 BLOCKING DIODES

ROUGH CURRENT CONTROL

22 SHUNT RESISTORS

WITH TRANSISTOR SWITCHES

POSITIVE BUS

CURRENT-SENSING TRANSISTOR CONTROL

4: J

^ ^

NEGATIVE BUS

FINE CURRENT CONTROL

ONE SHUNT RESISTOR

WITH LINEAR TRANSISTOR

VOLTAGE-SENSING TRANSISTOR CONTROL

METER SHUNT

tr

FILTER CAPACITOR

*9 1

- < 5 — 6

1-13-69 UNC 7759-5291

Figure IV-16. Conver t e r -Assembly and Power-Condit ioning Circui t Diagram

Figure IV-17. Vol tage-Current Profile

LOAD CURRENT, amp 1-13-69 UNC 7759-5292

It is an inherent cha rac t e r i s t i c of each independent 4-pack that a direct

sho r t - c i r cu i t may be placed a c r o s s i ts t e rmina ls indefinitely without damage.

This means that any value of load r e s i s t ance from zero to infinity may be ap

plied. When the load r e s i s t ance is infinity, i. e. the 4-pack is operating as an

open-c i rcui t , the te rminal voltage is a maximum. When the load res i s tance is

ze ro , i, e. a shor t -c i rcu i t ex i s t s , the output voltage is zero . When the load

r e s i s t ance equals the in ternal r e s i s t a n c e , the terminal voltage is one-half the

open-c i rcu i t voltage, as i l lus t ra ted in Figure IV-17. Thus, the terminal volt

age can be adjusted by controlling the res i s t ance of the load.

Power is del ivered to the po^wer conditioner on 24 independent positive

leads and one common negative lead. Because the load may consist of a la rge

number of power-consuming devices that will be switched on and off in a r an

dom fashion, the total power consumption may vary over a wide range. To

design the sys tem with wide flexibility it was assumed that the load could go all

the way to ze ro .

The total load is further assumed to be made up of two subloads; a single

dc load of approximately 56 volts requir ing a regulation of ±2%, and an inver te r

load which requ i res approximately 56 volts input. It was also assumed that

these loads will be applied as step functions and that they will draw high-

frequency cur ren t s -which must be supplied without the introduction of high-


f r e q u e n c y o u t p u t - v o l t a g e v a r i a t i o n s . The p o w e r - c o n d i t i o n i n g c o m p o n e n t s shown

in F i g u r e I V - 1 6 p r o v i d e a r e g u l a t i o n vo l t age of 56.0 vdc ±1%. T h e s e c o m p o n e n t s

a r e d e s c r i b e d in the fol lowing p a r a g r a p h s .

a. P r o t e c t i o n D iodes

A b lock ing d iode i s p l aced in s e r i e s wi th e a c h of the 4 - p a c k l e a d s to d e

couple the s u b a s s e m b l y f r o m the output bus if the 4 - p a c k or i t s l ead should b e

c o m e faul ted to g r o u n d . A s long a s the output t e r m i n a l vo l tage of a 4 - p a c k i s

g r e a t e r than 56 v o l t s , the diode wil l conduc t and supply c u r r e n t to the output

b u s . If the t e r m i n a l vo l t age d r o p s be low 56 v o l t s , a s i t would if s h o r t e d to

g round , a r e v e r s e vo l t age would a p p e a r a c r o s s the diode and no c u r r e n t would

flow. Without the d iode a fault on any 4 - p a c k o r l e ad would take c u r r e n t f r o m

the output bus and t h e r e b y r e d u c e the c u r r e n t a v a i l a b l e for the l o a d . If the fault

c u r r e n t e x c e e d e d the r a t e d load c u r r e n t , the output vo l t age of 56 vol t s could not

be m a i n t a i n e d . The b lock ing d iodes thus p r o t e c t the c o n v e r t e r a s s e m b l y a g a i n s t

i n t e r n a l f a u l t s .

b . Shunt V o l t a g e R e g u l a t o r

Under a n o - l o a d cond i t ion , i. e. no po^wer be ing u s e d by the s p a c e c r a f t , the

p o w e r - d i s s i p a t i o n r e s i s t o r s of a s h o r t e d r e g u l a t o r m u s t be ab le to c a r r y the e n

t i r e r a t e d c u r r e n t of the p o w e r s y s t e m , or 446 a m p . Since no t r a n s i s t o r s with

th i s c u r r e n t r a t i n g a r e a v a i l a b l e , a l a r g e n u m b e r of l o w - c u r r e n t t r a n s i s t o r s

m u s t be u s e d . Th i s i s not a d i s a d v a n t a g e , h o w e v e r , s i nce it p e r m i t s the c i r c u i t

to be des igned with h i g h e r r e l i a b i l i t y and with a r e d u c t i o n in the power tha t m u s t

be d i s s i p a t e d a t low t e m p e r a t u r e .

In the c i r c u i t of F i g u r e I V - 1 6 , 22 of the t r a n s i s t o r s a r e o p e r a t e d a s s w i t c h e s ,

in which c a s e the m a x i m u m t r a n s i s t o r d i s s i p a t i o n i s 660 w a t t s . T h i s o c c u r s

only in the r a r e c a s e when the e n t i r e load c u r r e n t i s be ing d u m p e d . With t h i s

c i r c u i t p r a c t i c a l l y a l l of the e x c e s s power i s d i s s i p a t e d in the r a d i a t i n g shunt

r e s i s t o r s , which can o p e r a t e at v e r y h igh t e m p e r a t u r e s and d u m p l a r g e a m o u n t s

of power wi th v e r y l i t t l e s p a c e and we igh t .

Each of the 22 swi tch ing t r a n s i s t o r s of F i g u r e IV-16 c a r r i e s a m a x i m u m of

20 a m p . Since the i n t e r n a l r e s i s t a n c e of the 24 4 - p a c k s u b a s s e m b l i e s in p a r a l

l e l i s a p p r o x i m a t e l y 0.125 o h m s , the vo l t age on the output bus wi l l d r o p 2.5 vo l t s

each t i m e a t r a n s i s t o r i s s w i t c h e d - o n . The t r a n s i s t o r s could be s w i t c h e d - o n

A I - A E C - M E M O - 1 2 7 1 7

88

when the b u s vo l t age r e a c h e s 56 plus 1.25 vol t s so that the vol tage would d r o p

to 56 m i n u s 1.25 v o l t s . The output vo l t age would thus be he ld within ±2.2% by

the rough c u r r e n t c o n t r o l . In the c i r c u i t of F i g u r e I V - 1 6 t h e s e s t e p - v o l t a g e

c h a n g e s a r e e l i m i n a t e d and the r e g u l a t i o n i m p r o v e d by us ing one t r a n s i s t o r

o p e r a t i n g l i n e a r l y so tha t it c a r r i e s the c u r r e n t which i s i n t e r m e d i a t e to the 20-

a m p s t e p s . The m a x i m u m d i s s i p a t i o n of th i s s ing le l i n e a r l y o p e r a t e d t r a n s i s t o r

wi l l be only 250 w a t t s , a va lue which can be a c c e p t e d by the l o w - t e m p e r a t u r e

e n v i r o n m e n t .

The o p e r a t i o n of the swi tch ing t r a n s i s t o r s is con t ro l l ed by a logic c i r c u i t

•which s e n s e s the load c u r r e n t . The n u m b e r of t r a n s i s t o r swi t ches open i s

p r o p o r t i o n a l to the load c u r r e n t . The c u r r e n t d r a w n by the l i n e a r t r a n s i s t o r i s

c o n t r o l l e d by s e n s i n g the output bus v o l t a g e . A f i l t e r c a p a c i t o r p r o v i d e s low

i n t e r n a l i m p e d a n c e of the p o w e r s o u r c e s to h i g h - f r e q u e n c y load c u r r e n t s . Since

the v o l t a g e - r e g u l a t i n g c i r c u i t s a r e v e r y f a s t th i s c a p a c i t o r i s not v e r y l a r g e .

c . C h a r a c t e r i s t i c s of the Po^wer-Condi t ioning C i r c u i t

(1) Ef f ic iency

The e f f ic iency of the po^wer-condi t ioning e q u i p m e n t at r a t e d load i s i m p o r t

ant s i n c e the p o w e r - c o n d i t i o n i n g l o s s e s wi l l s u b t r a c t f r o m the m a x i m u m power

which i s a v a i l a b l e f r o m a f i x e d - c o n v e r t e r a s s e m b l y . The eff ic iency of the

p o w e r - c o n d i t i o n i n g e q u i p m e n t a t p a r t i a l load i s not i m p o r t a n t s ince it does not

affect the m a x i m u m a v a i l a b l e p o w e r .

The ef f ic iency of the p r o p o s e d c i r c u i t a t full load i s 98%, inc luding the l o s s

due to the 1-volt d r o p a c r o s s the b locking d i o d e s . The l o s s e s in the v o l t a g e -

r e g u l a t i o n c o m p o n e n t s a r e neg l ig ib l e at r a t e d load b e c a u s e a l l of the t r a n s i s t o r

s w i t c h e s would be open and no c u r r e n t would be flowing in the l i n e a r t r a n s i s t o r .

The power r e q u i r e d to o p e r a t e the c o n t r o l c i r c u i t r y i s a l s o neg l ig ib l e .

(2) Cooling R e q u i r e m e n t s

The e s t i m a t e d p o w e r - c o n d i t i o n i n g e q u i p m e n t power l o s s e s which m u s t be

p icked up by the e n v i r o n m e n t a l c o n t r o l s y s t e m a t a t e m p e r a t u r e not ove r IOO°C

a r e a s in T a b l e I V - 6 .

A I - A E C - M E M O - 1 2 7 1 7

89

T A B L E I V - 6

P O W E R LOSSES

Source of Loss

Blocking diodes

Switching t r a n s i s t o r s

Linear t r ans i s to r

Control c i rcui ts

Wiring l o s se s

Total;

Loss at Ze ro -Load Conditions

(watts)

447

660

250

10

20

1387

Loss at Rated-Load Conditions

(watts)

447

0

0

10

20

477

(3) P e r f o r m a n c e

The r e g u l a t i n g c a p a b i l i t y of the c i r c u i t i s l i m i t e d only by the e l e c t r i c a l

t i m e c o n s t a n t of the c o n v e r t e r a s s e m b l y and the po-wer-condi t ion ing c o m p o n e n t s .

It is v e r y p r o b a b l e tha t the vo l t age can be r e g u l a t e d to ±1% or b e t t e r so tha t

add i t i ona l dc r e g u l a t o r s for c r i t i c a l dc l o a d s wi l l not be r e q u i r e d .

The r e f e r e n c e power s y s t e m h a s no o v e r l o a d c a p a c i t y , s i n c e the load i s

m a t c h e d to the i n t e r n a l r e s i s t a n c e of the c o n v e r t e r a s s e m b l y . Any a t t e m p t to

d r a w m o r e than r a t e d c u r r e n t wi l l c a u s e the output vo l t age to d r o p i n s t a n t l y and

the to ta l power wil l go down. T h i s i s an a d v a n t a g e when des ign ing p r o t e c t i o n

for the p o w e r - d i s t r i b u t i o n s y s t e m s i n c e the s h o r t - c i r c u i t c u r r e n t cannot be

m o r e than twice the r a t e d c u r r e n t .

(4) Size

The c o n s t r u c t i o n of the p o w e r - c o n d i t i o n i n g p a c k a g e wil l fol low p r a c t i c e s

s i m i l a r to t hose u s e d in the Apol lo i n v e r t e r . The cool ing of the d iodes and

t r a n s i s t o r s wi l l be by conduc t ion to the power c o n d i t i o n e r b a s e - p l a t e o r by i n

t e r n a l c i r c u l a t i o n of cool ing l iquid or g a s .

The m i n i m u m v o l u m e r e q u i r e m e n t s for the p o w e r - c o n d i t i o n i n g c h a s s i s (not

inc lud ing the r a d i a t i n g r e s i s t o r s ) wi l l be a p p r o x i m a t e l y a s fo l lows :

A I - A E C - M E M O - 1 2 7 1 7

90

24 diodes at 6 in. /diode 3

23 t r a n s i s t o r s at 16 in. / t r a n s i s t o r 3 2 printed circui t boards at 50 in.

3 1 capaci tor at 27 in.

Termina l s

Enclosure s t ruc ture

Total Volume

Detail design will be requi red to establ ish prec ise dimensions for this

component.

(5) Weight

The weight of the power-conditioning equipment (not including the radiating

r e s i s t o r s ) will be a lmost exclusively the weight of the s t ruc ture since the r ec t i

f iers weigh only 0.65 oz each and the t r a n s i s t o r s only 1 oz each.

Assuming that the packaging density would be the same as attained for the 3

Apollo inver te r at 0.0288 lb / in . , the weight will be approximately 28 pounds.

C. NaK-LOOP COMPONENTS

1. Pump System

The pumps selected for this sys tem a r e of the dc conduction EM type pow

ered by special low-voltage TE modules . As with the e lec t r ica l generation in

this sys tem, the pump packages have no moving par ts and their hydraul ic

power output i nc r ea se s automatical ly as the reac tor operating t empera tu re in

c r e a s e s . The advantages of this type pump a re simplicity of operation and high

rel iabi l i ty . The one disadvantage is that the p r e s s u r e - d r o p within the loops

must be kept low. However, in the design of a TE sys tem this is not par t icu

lar ly r e s t r i c t i ve .

a. Technology Status

Due to the compatibili ty of TE power sources with dc pumps, most of the

pump developnnent has been devoted to in tegral source dc pumps. In this type

the TE genera tor is int imately attached to the throat of the pump and the need

for h igh-cur ren t buses is vir tually el iminated.

144 in.

3 68

100

27

68

250

957 in.3


- ' ' * - te>' . - , : ' , i ' - ' ".?-.•

1-22-64 7636-5402CN

F i g u r e I V - 1 8 . M e r c u r y - R a n k i n e P r o g r a m I n t e g r a l S o u r c e P u m p

P

•V;-"';T-?:'

^•1^'tSli.T

•?.''-tl>i"-i' . •?'.-l'^ 'i^

1 0 - 2 6 - 6 2 7561-5471

F i g u r e I V - 1 9 . SNAP 1 OA I n t e g r a l S o u r c e P u m p

A I - A E C - M E M O - 12717

92

The SNAP 2 Mercury-Rankine P r o g r a m (MRP) developed a dc conduction

pump which used chromel -cons tan tan for the TE power genera tor . The pump

throat consisted of a Type 316 s t a in l e s s - s t ee l tube having a wall thickness of

0.020 in. The active throat length •was 10 in. The MRP pump is shown in F ig

ure IV-18. This pump was designed to operate in a vacuum environment at

1200°F. Over 20,000 h r of test exper ience were accumulated on this pump.

The SNAP lOA pump, shown in Figure IV-19, was a dc conduction pump

powered by a l ead- te l lu r ide TE genera to r . The pump operated at 1000°F in a

space environment and met all shock and vibration requ i rements for launch into

an Ear th orbit . More than 150,000 hr of test operation were logged by this

pump including over 20,000 hr by a single pump. Moreover , the pump was suc

cessfully operated in space during the SNAP lOA space flight.

In addition to these in tegral source pump designs which in general impose

the mos t severe r e s t r i c t i ons on pump design, over 50 dc conduction pumps have

been fabricated at AI for use in ground test faci l i t ies . These pumps have been

po^wered by remote power supplies and have been used for various component

t e s t s . They have operated without a single failure for over 200,000 h r . The

design concepts and fabrication methods used in them a re those specified for the

pump to be used in the ZrH reac to r — TE sys tem.

A t r i p l e -pa s s pump s imi la r to the reference design pump has been fabr i

cated and was pe r fo rmance- t e s t ed . The measured performance was within 5%

of that predic ted.

All fabricat ion steps of the selected pump a re s t a t e -o f - the -a r t and no new

p r o c e s s e s a r e involved.

b. Pump Power Source

To maximize the use of existing tubular TE module experience and to mini

mize the different types of ha rdware development required for the program, a

separa te pump power source , consisting of modules s imi lar to the power-

generat ion modules , was chosen for the reference design.

The bas ic design problem that had to be overcome was to obtain a high cur

rent at a low enough voltage to match the impedance in the pump throa ts . P r e

l iminary studies showed that a p rac t ica l mul t ipass pump, one in which the e lec

t r i ca l cu r ren t flo-ws through more than one throat in s e r i e s , could be designed


I

>

n

o

INNER CLAD,

OUTER CLAD

COLLECTOR RING

ELECTRICAL PIN

RETAINING RING

Figure IV-20. FHimp Converter (Drawing No. 939J386)

if a tubular module could be developed to provide 500 amp at a nominal voltage

of 0.22 volts. The design of such a special purpose module was evaluated and

fo\md to be feasible.

The TE-pump module has an active length of 7 in. , consisting of four t h e r

mocouples in se r i e s that produce an open-c i rcui t voltage of 0.54 volt at the nom

inal mean hot- and cold-clad t e m p e r a t u r e s , 1125 and 570°F, respect ive ly . A

layout of the reference module is shown in Figure IV-20 and a summary of i ts

cha rac te r i s t i c s is given in Table IV-7.

TABLE IV-7

PUMP MODULE SUMMARY

Nominal Load Requirements

Power, watts e lec t r ica l

Current , amp

Voltage, volts

Res is tance , mil l iohms

Module Charac te r i s t i c s

Mean hot-c lad t e m p e r a t u r e , °F

Mean cold-clad t e m p e r a t u r e , °F

Efficiency, %

Internal r e s i s t ance , mil l iohms

Elec t r ica l pin r e s i s t a n c e , mil l iohms

Inner d iameter , in.

Outer d iameter , in.

Open-circui t voltage, volts

Active length, in.

Number of couples

Weight, lb

Heat required, kwt

110

500

0.22

0.44

1125

570

3.46

0.54

0.10

0.75

2.24

0.54

7

4

7.4

3.2


TE POWER SOURCE

>

O

O I 1—'

-J I — '

MAGNET YOKE

PRIMARY LOOP'

HEAT REJECTION LOOP"

OS*

POWER SUPPLY (TUBULAR TE MODULES)

VOLTAGE (mv)

CURRENT (amps)

MAGNETIC FLUXdmes/in.^)

PRIMARY

NO. COOLANT PASSES 2

AP(psi) 3.35

FLOWRATE (lb/sec) 3.25

WEIGHT (lb)

• POWER SUPPLY

• PUMP

• BUS

TOTAL

HYDRAULIC POWER ( watts)

THERMAL POWER (kwO

NET EFFICIENCY (%)

3

220

1500 (500 each)

11,500

HRL

1

1.5

3.10

30

30

50

110

65

9.6

0.68

Figure IV-21 . P r i m a r y and Heat-Reject ion Loop E lec t romagne t i c -Pump Assembly 8-J1-099-12

Because the high cu r ren t and low-voltage output requi res the pump module

to have a low internal r e s i s t a n c e , its e lec t r ica l conductors a r e relat ively thick.

The radial and axial th icknesses of the conductors and the TE washers were

sized so that the module in ternal r e s i s t ance would equal the effective load r e

s i s tance , 0.54 mil l iohm. Design trade-offs were a lso made to satisfy the load

requ i rements without imposing significant thermal-power or •weight penalties on

the sys tem.

Although the pump module design differs from that of the tubular modules

in the main conver te r , s t r e s s calculations and consideration of the manufactur

ing process indicate that fabrication of this design concept is feasible.

c. Pump System Descript ion

Several a l te rna te pump designs were considered before an a t t ract ive pack

age was designed based on the cha rac te r i s t i c s of the tubular TE modules de

scr ibed above. The best design using these modules was found to resul t when

the pumping requ i rements for both the p r i m a r y loop and HRL's were combined

at one location so that th ree modules could be operated in paral le l to provide

high cur ren t at the location v/ithout a penalty due to inefficient use of thermal

power. In this vi ay 1500 amp was available to the pumps at 0.22 volts.

The cha rac t e r i s t i c s of the sys tem dictated that the optimum configuration

would be as shown in F igure IV-21, where the e lec t r ica l current is passed

through two throats on the p r i m a r y loop and one on the HRL. With this config

urat ion the hydraul ic po^wer available to the p r imary would be approximately

twice that available to the HRL. Also it was determined that the pr imary- loop

throats should be in the cooler portion of the loop (1044°F) and the heat - re jec t ion

throat should be in the hot ter portion of its loop (663 °F) . This would minimize

the the rmal shunting between loops.

A sys tem optimization •was performed, trading off NaK-system weight

against pump weight •with p r e s s u r e drop as the var iable . On the basis of the

optimization, p r e s s u r e drops of 3.35 psi in the p r imary loop and 1.5 psi in the

HRL's were selected.

F igure IV-22 sho^ws the reference design pump package. The three-module

power source is designed s imi la r to the 4-packs in the main TE conver ter . One


THERMOLLLCTRIC COMVtRTER KAODULE

MAGMET

YOK.E

S E - C T I O M fK- f\ 7759-5293

Figure IV-22. F^amp Assembly, Separate Source,

Three -Throa t


of these pump packages is used in each quadrant of the sys tem. The power sup

ply weighs 30 lb, the pump also 3 0, and the e lec t r ica l bus 50 for a total of

110 lb.

Figure IV-23 shows the predicted performance of the pump as designed.

Note that at the reference flowrates the p r imary - loop p r e s s u r e - d r o p is 3.45 psi

and that at the HRL is 1.65. These values a r e g r ea t e r than those in the sys tem

design, to provide a design marg in for meeting the pumping requ i rement . F u r

ther margin also exists since the calculated p r e s s u r e - d r o p s for both loops a r e

well below the l imit . The total t he rmal power required to run the four-pump

system is 38.4 kwt or 6.6% of the reac tor power.

Thermal and s t r e s s analyses were conducted to evaluate the pump, and no

ser ious problems were determined for ei ther s teady-s ta te or t rans ien t opera

tion. The differential expansion between the hot and cold throats is bas ica l ly

alleviated by sli ts in the connecting bus bar which allows it to bend more freely.

The maximum magnet t empera tu re , even when operating at 1150°F in the p r i

m a r y loop and 650 in the HRL is 790°F. This is well within the allowable t em

pera ture range for the magnet ma te r i a l .

2. Expansion Compensator

The p r imary loop and HRL a r e designed to be void-free at all t imes . Ex

pansion compensators a r e used in the loops to accommodate the expansion of

the NaK from the cold shutdown condition to the hot operating condition, and to

maintain the sys tem at the operating p r e s s u r e .

a. Technology Status

More than 50 expansion compensators of the type shown in F igure rV-24

were built under the SNAP lOA development p rog ram for development, qualifi

cation, and sys tem t e s t s . This unit is a spring-loaded bellows with a latch

mechanism to prevent deformation due to hydraul ic loads experienced during

launch. A position indicator was also included to provide a measu remen t of

the NaK-loop status during operation. More than 100,000 h r of testing were

accomplished on the SNAP lOA expansion compensator ; the longest single tes t

was 10,000 hr as a par t of a complete nuclear sys tem tes t .


CURRENT = 1500 amp MAGNETIC FLUX = 11,500 lines/in

PRIMARY-LOOP PASSES •(TOTAL)

2

•HEAT-REJECTION PASS —

0 1

1-14-69 UNC

2 3 4 5 NaK FLOWRATE, lb/sec

6 7

7759-5294

Figure IV-23. Reference Pump Pe r fo rmance


F i g u r e I V - 2 4 . SNAP 1 0A E x p a n s i o n C o m p e n s a t o r

b . Des ign D e s c r i p t i o n

The s i ze and weight of the c o m p e n s a t o r s a r e a funct ion of loop NaK vo l

u m e s , the o p e r a t i n g t e m p e r a t u r e s , and o p e r a t i n g p r e s s u r e s . T a b l e IV-8 p r e

s e n t s the NaK v o l u m e s for the r e f e r e n c e s y s t e m . At the r e f e r e n c e o p e r a t i n g 3 3

t e m p e r a t u r e the e x p a n s i o n vo lume of the p r i m a r y loop i s 0.161 ft p e r ft of 3 3

NaK v o l u m e , and 0.061 ft p e r ft of NaK vo lume for the H R L ' s . Using the vo l -3

u m e s in Tab le I V - 8 the to ta l p r i m a r y - l o o p e x p a n s i o n r e q u i r e m e n t i s 0.59 ft and that for the H R L i s 0.44 ft'^.

F o u r e x p a n s i o n c o m p e n s a t o r s a r e r e q u i r e d for the H R L , one for each quad

r a n t . It is a l s o conven ien t to h a v e four c o m p e n s a t o r s in the p r i m a r y l oop . 3

T h u s , the p r i m a r y loop would r e q u i r e four 0.15-ft c o m p e n s a t o r s and the H R L 3

four 0.11-ft c o m p e n s a t o r s . To p r o v i d e c o m m o n a l i t y of d e s i g n , a s ing le c o m -3 .

p e n s a t o r s i z e was s e l e c t e d (0.15 ft ), which r e s u l t s in a s l igh t o v e r d e s i g n in the

H R L . A d o u b l e - s e a l e d g a s - b a c k e d c o m p e n s a t o r af fording s e c o n d a r y NaK con

t a i n m e n t w a s s e l e c t e d to m e e t t h e s e e x p a n s i o n r e q u i r e m e n t s . The c h a r a c t e r i s t i

A I - A E C - M E M O - 1 2 7 1 7

103

TABLE IV-8

NaK VOLUMES

P r i m a r y Loop

Reactor

Converter

Piping

Total :

Heat-Reject ion Loop

Converter

Gal lery piping

Radiator

Total :

1.75 ft^

1.07

0.82

3.64 ft^

1.59 ft^

0.63

4.95

7.17 ft"

TABLE IV-9 EXPANSION COMPENSATOR

CHARACTERISTICS

Type

Expansion volume

P r e s s u r i z a t i o n

Size:

Diameter

Height

Weight

Number requi red

Double-bellows s e r i e s

0.15 ft^

Inert gas

11 in.

9.65 in.

26 lb

8

of such a compensator a r e summar ized in Table IV-9 and a conceptual drawing

of it is shown in F igure IV-25.

The principle of operation of the compensator involves two bellows assem

bled in s e r i e s as shown in F igure IV-25. Two sets of s e r i e s - s t a c k e d bellows

a r e mutually opposed. The inner surface of the p r imary bellows and the

bel lows-top cups of the compensator provide containment for the NaK. The


SECONDARY VOLUME EVACUATION TUBE 2 PLACES

H 00 DIAM

ALTERNATE GAS TUBE CONFIGURATION

FULL VOLUME POSITION

NaK SUPPLY TUBE 0 375 ODx 0 049 WALL

PRIMARY BELLOWS 10 50 OD X 9 00 ID

SECONDARY BELLOWS 10 50 ODx 9 00 ID

8-JY25 119-38

Figure rV-25. Expansion Compensator , 25-kwe Nuclear The rmoe lec t r i c Power Supply

space between the bellows outer surface and the cyl indrical sect ions inner su r

face is evacuated and const i tutes the secondary containment in event of a NaK

leak through the p r i m a r y bel lows. The volume of the inner surface of the s e c

ondary bellows is closed with a dome to facilitate gas fill for sys tem p r e s s u r i

zation. The opposed bellow design provides par t ia l sys tem pressur iza t ion in

the event of the loss of p r e s s u r e from one gas chamber . The null point of the

bellows (heat- t reat position) is at about 2/3 of the maximum s t roke , to allow the

bellows to operate at a low s t r e s s at the operational and launch volumes.

With inc rease of sys tem t e m p e r a t u r e , the NaK volume change is displaced

by the p r i m a r y bellows and the initial p r e s s u r e within the secondary bellows is

increased proport ional to the PVT ( p r e s s u r e / v o l u m e / t e m p e r a t u r e ) re la t ion

ship. This gas p r e s s u r e , in addition to the stiffness of the bel lows, es tabl ishes

the sys tem operating p r e s s u r e . F igure IV-26 shows this p r e s s u r e as a function

of average NaK t empera tu re for the two loops. The normal operating p r e s s u r e

for both loops is 20 psia while p r e s s u r e within the loops at launch, when non-

operat ing, is approximately 6 ps ia . The curves in Figure IV-26 also show that

T 1 1 1 r

0 i 1 I I i I I 0 200 400 600 800 1000 1200

AVERAGE NaK TEMPERATURE (°F)

8-JY19-119-5

Figure IV-26. Expansion-Compensator P r e s s u r e Charac te r i s t i c s


even with one chamber vented to space, both loops would maintain adequate

p r e s s u r e during a shutdo^vn.

At operating t empera tu re both bellows a r e at minimum ex tens ion-s t ress

and maximum p r e s s u r e - s t r e s s leve ls . The tempera ture limitation on the bel

lows is approximately 725 °F . At this t empera tu re the bellows maintain their

s p r i n g - r a t e , a s s i s t in maintaining sys tem p r e s s u r e , and a r e safely below the

normal h e a t - t r e a t t empera tu re of 800°F. The t empera tu re of the bellows will

be maintained at this level by design of the gal lery. However, no NaK-contain-

ment failure of the bellows would be expected until a t empera ture of at least

900 to 1000°F is exceeded.

The expansion compensa tors will be located near the high point of their

loop during launch. The actual attach point for the compensator supply line

will be at the high point so that as the launch acce lera t ion i nc r ea se s , the line

will drain down into the compensator eliminating large static head forces .

D. RADIATOR

1. Concept Selection

The rad ia tor for the HRL is one of the most mission-dependent subsystems

in the powerplant. Integration const ra in ts associated with launch package size,

operat ional cycle, and rel iabi l i ty , all affect the choice of a radiator type.

Several radia tor design variat ions were considered during this study, in

cluding heat -p ipe designs and relat ively standard fin-and-tube rad ia to r s with

ei ther fixed or folding NaK joints . Although final selection of a radiator design

concept would depend strongly on miss ion and integrat ion const ra in ts , a fixed,

cylindrical tube-and-fin type radia tor was tentatively selected for the reference

power sys tem design in o rder to more completely define its design and pe r

formance c h a r a c t e r i s t i c s . Several rad ia tor ma te r i a l combinations were ana

lyzed, including a luminum-bery l l ium alloy (Lockalloy) and pyrolytic graphite

for the radia tor fin and meteoroid a r m o r ; however , aluminum fins diffusion-

bonded to s t a in l e s s - s t ee l tubes were selected, due to the relat ive simplicity

and technology available for this comibination. A semimonocoque ti tanium sup

port s t ruc ture s imi la r to that used in the SNAP lOA system was also selected

for the same r e a s o n s .


TABLE IV-10

TUBE-AND-FIN RADIATOR DESIGN CRITERIA

The rma l power

Inlet t empera tu re

Outlet t empera tu re

NaK flow (total)

The rma l -con t ro l coating:

Emiss iv i ty

Solar absorpt ivi ty

Meteoroid nonpuncture pr

Tube d iameter

obabiT Lty"~

551 kwt

663°F

463°F

12.4 l b / s e c

0.90

0.30

0.990

3/8 in.

CONFIGURATION

CYLINDRICAL RADIATOR

H * 1.5 X D-

ti w^\s •ALUMINUM FIN

^ALUMINUM ARMOR

SS TUBE (Wall thickness = 0.020 in.)

11.5 ft-diam CYLINDER

RADIATING FROM ONE SIDE

STRUCTURE WEIGHT= 0.75 Ib/ft^

'^Reference for meteoroid a r m o r calculat ions: H. D. Hal ler and S. Lieblein, NASA LERC, Analytical Comparison of Rankine Cycle Space Radiators Constructed of Central Double and Block-Vapor-Chamber Fin-Tube Geomet r i e s , " NASA T N D - 4 4 1 1 , F e b r u a r y 1968


Several feasible designs for folding NaK joints which would make possible

the use of deployable rad ia tor panels were evolved. Although such a design is

not specifically incorpora ted in the reference sys tem, the concept may be of

sufficient in te res t for applications requir ing compact powerplant packaging to

justify further investigation and development. The heat -p ipe radiator concept

was not selected due to the lack of a des i rab le working fluid for the 500 to 600°F

t empera tu re range of in t e re s t for this sys tem.

2. Radiator Design

The assumpt ions , configurations, and c r i t e r i a used for the radia tor design

a r e shown in Table IV-10. The the rmal power and t empera tu res l isted a re

those w^hich •were determined to be nea r -op t imum for the reference system on

the bas is of overal l sys tem weight.

F igure IV-27 shov/s the total r a d i a t o r - p l u s - s t r u c t u r e weight as a function of

rad ia tor a rea for different numbers of tubes. The minimum-weight envelope is

a lso plotted. The weight includes the tube, fin, a r m o r , s t ruc ture , and NaK 2

holdup. A s t ruc ture weight of 0.75 lb/ft , determined by a separa te design

study, was used. This plot shows that as the a rea is increased from 1250 to 2

1400 ft , the optimum number of tubes for minimum weight d e c r e a s e s . The 2

min imum radia tor -weight point exists at about 1450 ft with approximately 100

tubes; however, it is c lear that an a rea /weigh t trade-off can be made for the 2

re fe rence sys tem over a rad ia tor a rea range from 1200 to 1450 ft .

Another considerat ion in the radia tor design is the NaK p r e s s u r e - d r o p in

the tubes. P r e l i m i n a r y analys is showed that the tube size should be small to

minimize radia tor weight and a r e a , but the minimum size was res t r i c t ed to

3 /8- in . diam based on potential NaK-plugging considerat ions . Calculations in

dicated that even for this tube size the p r e s s u r e - d r o p was excessive for r ad i

ator a r ea s of in te res t when the NaK was allowed to flow the complete length of

the tube. This excess ive p r e s s u r e - d r o p was alleviated by breaking the flow

into two to three para l le l paths . This also provides some advantage in system

assembly; however, such an a r rangement r equ i res additional headers feeding

the individual NaK tubes.

Thermal per formance for the radia tor was calculated for the worst case

where the projected a r ea is normal to the sunlight. Per formance of the radia tor


4000 -

C3

LJ

o ZD

h-

+

3000 -

P 2000

< a:

1000 1000

NO. OF NaK TUBES

220

SATURN-V OWS DESIGN

J t

LOCUS OF MINIMUM WEIGHT

REFERENCE DESIGN

± 1200 1400 1600

RADIATOR AREA ( f r ) 8-J26-119-73A

Figure IV-27. Cyl indr ica l -Radia tor Weight Charac te r i s t i c s


in the full shade or with sun reflection and d i rec t radiat ion from the earth will

be increased by a maximum of about 2.5%. 2

Table IV-11 p resen t s the cha rac t e r i s t i c s of the 1400 ft cylindrical radia tor 2

selected for the re ference sys tem. An a r ea of 1450 ft would resul t in a slight •weight reduction but not enough to war ran t the l a rge r a r ea . Areas below 1400 ft

resu l t in rapidly increas ing weight c h a r a c t e r i s t i c s . A drawing sho^wing the

c ross - sec t iona l design of a typical radiator is shown in Figure V-9 .

TABLE IV-11

REFERENCE RADIATOR CHARACTERISTICS

Radiator a r e a , ft

Geometry

Number of tubes

A r m o r th ickness , in.

Fin th ickness , in.

Fin and a r m o r m a t e r i a l

Tube outside d iamete r , in.

Tube th ickness , in.

Tube ma te r i a l

S t ructure

Total weight, lb""

1400

Cylindrical

94

0.19

0.035

6061 Aluminum

3 / 8

0.020

347 Stainless steel

Titanium alloy

2580

-''Includes tube, NaK fin, a r m o r , and s t ruc ture


V. MISSION ADAPTATIONS

The re fe rence 25-kwe reac to r — TE sys tem descr ibed in the preceding sec

tions of this repor t provides a general design bas is from which powerplants can

be configured for specific space applicat ions. Mission and integration cons ide r

ations a r e par t icu la r ly important when concerned with the radiation shield and

heat - re jec t ion rad ia tor design, which in turn affects the design and performance

cha rac t e r i s t i c s of the power sys tem. To i l lus t ra te severa l typical integration

concepts and corresponding powerplant c h a r a c t e r i s t i c s , designs for three m i s

sions for which r eac to r — TE sys tems have been and a r e being considered a r e

presented in this section. The f i rs t design is ta i lored to the Saturn-V OWS m i s

sion cur ren t ly under study by NASA as a par t of the Apollo Applications P r o g r a m

(AAP). The second is an update of a powerplant concept evolved in a recent

NASA/AEC study of r eac to r power sys tems for manned lunar ba se s . The third

updates an ea r l i e r design developed in a joint NASA/AEC study of reac tor power

sys tems for the MORL. In the la t ter two cases the bas ic integration concepts

and constra ints es tabl ished in previous studies were maintained, whereas the

OWS powerplant design and integrat ion concept were evolved in this study.

A. SATURN-V OWS POWERPLANT

1. Mission Requi rements and Integration Considerat ions

The Saturn-V OWS concept being studied by NASA is a d i rect , generic evolu

tion from the Saturn-I Workshop which is cur ren t ly under development as par t of

the AAP, As cur ren t ly conceived, the Saturn-V OWS would consist of a dry

Saturn-IVB stage s t ruc tu re fitted with docking por t s , a i r locks , power and life-

support equipment, exper iments , and other subsys tems requi red to function as

a manned OWS. The Saturn-V OWS would be launched (fully equipped) using the

f irs t two stages of the Saturn-V launch vehicle. The planned launch date is cu r

rently est imated to be in the 1973 to 1975 t ime period. The nominal orbit altitude

and inclination a r e 270 n, mi (nautical mi les ) , 50°,

One of several possible Saturn-V OWS configurations is shown on the front

ispiece of this r epor t with a nuclear power sys tem attached to the forward docking

port . This concept would provide accommodations for a s ix-man crew with


g r o w t h c a p a b i l i t y to n i n e . The d e s i g n goal for the o p e r a t i o n a l l i f e t ime of the

OWS i s 2 y r , a l though the c r e w would be r o t a t e d s e v e r a l t i m e s p e r y e a r , u s ing

a modi f i ed v e r s i o n of the Apol lo C o m m a n d and S e r v i c e Module (CSM).

The o r b i t a l a v e r a g e cond i t i oned power r e q u i r e m e n t s for the S a t u r n - V OWS (2) a r e c u r r e n t l y e s t i m a t e d to be f r o m 12 to 16 kwe. C o n s i d e r i n g power cond i

t ion ing l o s s e s , t he g r o s s dc power r e q u i r e m e n t s would thus be in the r a n g e of

14 to 18 kwe . A p o w e r g r o w t h m a r g i n i s a l s o d e s i r e d and the m i n i m u m r a n g e

of i n t e r e s t for the n u c l e a r p o w e r s y s t e m h a s t h e r e f o r e been a s s u m e d to be f rom

15 to 20 k^we. Uncond i t i oned vo l t age r e q u i r e m e n t s a r e 28 vdc o r h i g h e r .

No spec i f i c r e l i a b i l i t y r e q u i r e m e n t s for the power s y s t e m have been e s t a b

l i s h e d , but it i s known tha t a m i s s i o n - s u c c e s s p r o b a b i l i t y for the e n t i r e OWS of

0,95 o r b e t t e r would be d e s i r e d . Thus the r e l i a b i l i t y of the power s y s t e m p r o

duc ing 15 to 20 kwe for the 2 - y r d u r a t i o n would p r o b a b l y have to be ^^0.99, a s

s u m i n g tha t th i s l eve l of po^wer is r e q u i r e d for m i s s i o n s u c c e s s . Surv iva l r e l i

a b i l i t y r e q u i r e m e n t s in e x c e s s of 0,99 for the e n t i r e OWS a r e a l s o d e s i r e d but

diff icult to p r o j e c t , m u c h l e s s d e m o n s t r a t e . P r e v i o u s s t u d i e s of r e a c t o r power

s y s t e m s for the M O R L have conc luded tha t a backup power s y s t e m c a p a b l e of

p r o d u c i n g suff ic ient p o w e r for m i n i m u m s ta t ion and o r b i t - k e e p i n g for a p e r i o d

of about 42 days would be n e c e s s a r y to p r o v i d e such a s s u r a n c e .

In add i t ion to the g e n e r a l p o w e r s y s t e m r e q u i r e m e n t s d i s c u s s e d above , a

n u m b e r of i m p o r t a n t i n t e g r a t i o n f a c t o r s m u s t be c o n s i d e r e d . Among t h e s e a r e :

1) P o w e r s y s t e m c o n f i g u r a t i o n and loca t ion .

2) R a d i a t i o n - s h i e l d we igh t and d o s e p ro f i l e .

3) Launch and deplo^yment m o d e s ,

4) E O L d i s p o s a l p r o v i s i o n s .

All of the above c o n s i d e r a t i o n s a r e i n t e r r e l a t e d , p a r t i c u l a r l y the f i r s t two.

F o r e x a m p l e , it i s d e s i r a b l e t ha t the po^wer s y s t e m i n t e g r a t i o n i m p o s e m i n i m a l

m o d i f i c a t i o n s to the OWS c o n f i g u r a t i o n o r c o m p r o m i s e s in i t s o p e r a t i o n . The

l oca t i on of the t e l e s c o p e w i th i t s r a d i a t i o n - s e n s i t i v e f i lm and o the r e x p e r i m e n t a l

s e n s o r s in the aft end of the OWS m a k e the i n t e g r a t i o n of the n u c l e a r s y s t e m in

tha t r e g i o n difficult and u n d e s i r a b l e . S i m i l a r l y , a t t a c h m e n t of the powerp l an t to

A I - A E C - M E M O - 1 2 7 1 7

113

the sides of the workshop would requi re the use of long deployment boomis to

obtain acceptable radia t ion-shie ld weights, due to the length of the OWS, which

is about 120 ft (including a docked CSM in the forward docking port) . Thus by

a p rocess of el imination it appears that the most favorable location for the

nuclear power sys tem for the OWS as now conceived would be attached to the

forward docking port , as shown on the front ispiece. The side docking por ts

would then be used for docking the CSM's.

The basic radiat ion shielding requ i rements a r e that the total radiation dose

received by the crew during normal operat ion, rendezvous, and ext ravehicular

act ivi t ies (EVA) should not exceed prede termined allowable levels . An allowable (3) whole-body dose of 100 r e m / y r has been proposed for this miss ion . The ex

pected annual whole-body dose due to natura l radiation (electrons and protons)

for the specified orbit is approximately 56 r e m . Thus an allowable annual

whole-body dose of 44 r e m or less from the nuclear power sys tem would ap

pear to be an acceptable and reasonable requ i rement . For the present study

a shield dosera te r equ i rement in the range of 20 to 30 r e m / y r within the Work

shop and a rendezvous dose of l ess than 5 r e m were assumed.

Launch and deplo-yment considerat ions r equ i re that the power sys tem con

figuration, s ize, and weight be compatible with available launch vehicles appro

priate for the miss ion . An objective for this study has been to evolve a power-

plant design which, with minor modifications, could be compatible with any of

the following launch options:

1) Integral launch with the OWS on the two-stage Saturn-V,

2) Separate launch on a Saturn-IB,

3) Separate launch on a Ti tan-3 ,

The la t ter two cases would requ i re an unmanned rendezvous with the OWS,

using the Apollo serv ice module, or Titan Trans tage , Additional details on pay-

load capabili t ies and proposed launch configurations a r e discussed in Sec

tion V-A-3 .

The EOL-disposal r equ i rement is based on nuclear safety considera t ions .

Previous studies made under the AEC Aerospace Nuclear Safety (ANS) P r o g r a m


have shown that it will be des i rab le to provide rel iable means for disposing of

the r eac to r after sustained operation in the orbit altitude range of in te res t for

the OWS, Two general approaches toward satisfying this requi rement con

s idered to be acceptable a r e to:

1) Boost the r eac to r up to a higher orbit (^-450 mi les ) , or

2) Deboost the r eac to r into deep ocean a r e a s .

In the f i rs t approach the f iss ion-produce activity will decay to safe levels

before eventual random r e - e n t r y . Recovery is not required in the second

approach.

Table V-1 summar i ze s the miss ion and power -sys tem requi rements which

have been specified, derived, or a s sumed for this study,

2, System Description

In adapting the re ference r eac to r — TE system to the Saturn-V OWS there

a re no changes in per formance , and all of the foregoing miss ion requirements

a r e met . At full power the sys tem produces 24,7 kwe at 56 volts dc ± 1%, The

rel iabi l i ty requ i rement of 0,99 is exceeded at a par t ia l -power level of about

18 kwe. All performance p a r a m e t e r s and rel iabil i ty es t imates a re as descr ibed

in Section HI. The only difference frona the reference system descr ibed in that 2

section is that the radia tor a r e a is reduced fromi 1400 to 1287 ft at a weight

penalty of 320 lb.

The radiat ion environment imposed by the operating reactor will be p r e

sented la ter in Subsection a, with the discussion of the two shield options,

A layout of the complete plant as adapted for the Saturn-V OWS is shown

in Figure V - 1 , It is designed to mount in line with the Workshop on the Multiple

Docking Adapter (MDA) as depicted in F igure V-2,

During launch the power sys tem is housed •within the heat shield shroud (or

power-supply adapter) , which acts as an aerodynamic fairing and s t ruc ture .

This shroud is coated to provide a re la t ively high solar absorptivity and low

emiss iv i ty so that the equi l ibr ium t empera tu re within it, when the powerplant

is not operat ing in space, is about 100°F, This technique, proven during the

SNAP lOA flight tes t , a s s u r e s that NaK freezing does not occur . When inside the

shroud the overal l plant length is 47.3 ft and the shroud diameter is 12.8 ft.


T A B L E V - 1

S A T U R N - V O R B I T A L WORKSHOP MISSION R E Q U I R E M E N T S F O R NUCLEAR P O W E R SYSTEM

Uncond i t ioned power l eve l :

U n r e g u l a t e d v o l t a g e :

Des ign l i f e t i m e :

R e l i a b i l i t y :

R a d i a t i o n d o s e (wholebody) :

T o t a l , inc lud ing n a t u r a l r a d i a t i o n

R e a c t o r ( n o r m a l o p e r a t i o n )

R e a c t o r ( r e n d e z v o u s )

Spec i a l n u c l e a r s a fe ty p r o v i s i o n s :

Launch o p t i o n s :

P r o b a b l e l a u n c h d a t e :

G e n e r a l i n t e g r a t i o n c o n s t r a i n t :

P r e f e r r e d p o w e r s y s t e m loca t ion :

15 to 20 kwe

> 28 vdc

2: 2 y r

^ 0 , 9 9

100 r e m / y r

20 to 30 r e m / y r

-^5 r e m

E n d - o f - l i f e d i s p o s a l

(Orb i t boos t to ^-450 m i o r d e b o o s t in to ocean)

I n t e g r a l wi th t w o - s t a g e S a t u r n - V

S e p a r a t e wi th S a t u r n - I B / C o m m a n d and S e r v i c e Module or T i t a n - I I I / T r a n s t a g e

1973 to 1975

M i n i m a l mod i f i ca t i on to O r b i t a l W o r k s h o p or l a u n c h v e h i c l e s

Docked to f o r w a r d p o r t of Mul t ip le Docking A d a p t e r

A I - A E C - M E M O - 12717 116

-APOLLO COMMA/^£> ^££rPV/C£ MODOL£ (P^p)

D*TE ykrCBOVtD

SATURN V WORKSHOP

£5/<r\^e NOCLEAP THCRMOeLECTP/C P'OWER 5C/PPL y

PReSSCR/ZED EXPER/ME/Vr CA/^/STER

POWER £a/='PL YADAPrER

- A^^L T/PLE DOCMAJG /IZ^APTE/?

O 5 10 I I I i I M I I I

IS

I 20 2S

_L_ 30 35 40 45

_ L _ 50

rcET Figure V-2, Saturn-V Orbital Workshop with 25-kwe

Nuclear Thermoelec t r ic Power Supply


Dur ing o p e r a t i o n the s y s t e m i s ex t ended out f r o m wi th in the sh roud to e x

p o s e the r a d i a t o r . Th i s p r o v i d e s the added a d v a n t a g e of i n c r e a s i n g the s e p a r a

t ion d i s t a n c e to o v e r 100 ft b e t w e e n the r e a c t o r and the p r i m a r y a r e a s of the

W o r k s h o p w h e r e p e r s o n s a r e l o c a t e d . The m e t h o d of ex tending and r e t r a c t i n g

the p o w e r p l a n t w a s s tud ied only enough to e s t a b l i s h f ea s ib i l i t y . With the m e t h o d

evo lved , the p l an t i s guided by r a i l s i n c o r p o r a t e d into the r a d i a t o r moving on

r o l l e r s a t t a c h e d to the s h r o u d , and i s m o v e d by a s c r e w j a c k a r r a n g e m e n t , A

c o n c e p t u a l d e s i g n of the d e p l o y m e n t m e c h a n i s m is shown in F i g u r e V - 3 . The

m o t i v e f o r c e i s p r o v i d e d by a d r i v e m o t o r o p e r a t i n g t h r o u g h a g e a r t r a i n on a

ba l l s c r e w - a n d - n u t c o m b i n a t i o n . A m a g n e t i c b r a k e i s emp loyed for pos i t i ve

l ock ing . The d e s i g n i s s i z e d to ex tend the s y s t e m in about 15 m i n .

The r e a c t o r c o n t r o l e q u i p m e n t , TE c o n v e r t e r p r o t e c t i v e d i o d e s , and the

v o l t a g e - r e g u l a t i o n e q u i p m e n t would be l o c a t e d in the space s t a t ion , a c c e s s i b l e

for e q u i p m e n t r e p l a c e m e n t o r r e p a i r d u r i n g o p e r a t i o n .

Tab le V-2 g i v e s a we igh t b r e a k d o w n for the power s y s t e m excluding the h e a t -

sh i e ld s h r o u d . Inc luded a r e the we igh t s for the t w o - s h i e l d opt ions d i s c u s s e d in

the fol lowing s u b s e c t i o n .

The c o m p o n e n t s for the s y s t e m a r e d e s c r i b e d in Sect ion IV. In the fol lowing

p a r a g r a p h s the spec i f i c c o m p o n e n t a r r a n g e m e n t s a r e d e s c r i b e d for th i s a d a p t a

t ion of the p lan t ,

a . R a d i a t i o n Shie ld Des ign

The r a d i a t i o n sh i e ld r e q u i r e m e n t s and concep t s h a v e an i m p o r t a n t effect on

the o v e r a l l c h a r a c t e r i s t i c s of r e a c t o r p o w e r p l a n t s for the S a t u r n - V OWS m i s s i o n .

The m o s t i m p o r t a n t sh i e ld c o n s i d e r a t i o n s a r e the dose c r i t e r i a , the g e o m e t r y

of bo th the r e a c t o r and the s p a c e c r a f t , and the sh ie ld m a t e r i a l s . The a s s u m p t i o n s

and g e n e r a l a p p r o a c h t a k e n t o w a r d s evolv ing a c o n c e p t u a l sh ie ld des ign for th i s

i n i s s i o n a r e d i s c u s s e d in t h i s s e c t i o n a long wi th the r e s u l t s ob ta ined .

The sh i e ld ing a n a l y s i s r e q u i r e d to evolve an o p t i m u m m i n i m u m - w e i g h t

sh i e ld des ign for th i s type of m a n n e d s p a c e m i s s i o n i s qui te c o m p l e x and the

r e s u l t s in the p r e s e n t s tudy , t h e r e f o r e , m u s t be c o n s i d e r e d a s p r e l i m i n a r y

e s t i m a t e s . R e f i n e m e n t s in e s t i m a t e s of the r a d i a t i o n - s o u r c e t e r m s and the

p o s s i b l e sh i e ld g a l l e r y d i m e n s i o n s which have been m a d e s ince the sh ie ld ing

a n a l y s i s t a s k w a s c o m p l e t e d , h o w e v e r , i n d i c a t e tha t the r e s u l t s p r e s e n t e d should

be c o n s e r v a t i v e .

A I - A E C - M E M O - 1 2 7 1 7 121

12 11 10 H DATt I A^PRO^'E•D

S-a D£. T t ^ ^ C K .

v i t vy c SCALE l / z

12 11 10

^ , > ATOMjTS ,1^^TLR\ U l O V a

C - (JflNO 0 9 9 7 ^ ^ IfFlAVE

"" iHttT

f ^ $ $ $ $ ^

vV

4 PITCH Dl(\ SALL SCeE.W - 3 0 F r u& )• LEflO

- *£ / iKHEf lD MOroe

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C^ ATOMICS ^1>1LU>^VTI0N a CA 'OC4 Mite ctu o»e>

ccocicc Tfig Q99 74~ltaAve

5E.CTIOM ^ • A

Figure V-3 , Actuator , Nuclear Thermoelec t r ic Power

Supply, Saturn-IVB Orbital Workshop


A

'i 7 1

TABLE V-2 SATURN-V ORBITAL WORKSHOP POWER SYSTEM

WEIGHT BREAKDOWN

Component Weight

(lb)

Reactor

Thermoe lec t r i c conver ters

Pumps

Expansion compensators

Piping

Gallery s t ruc tu re

Instrumentat ion and controls

Radiator and s t ruc ture

Power cable

Deployment mechan i sm

Total Unshielded Weight

Shadow

Radiation Shield Weight 14,330

Total Shielded Weight 22,280 24,450

(1) Dose Cr i t e r i a

The radiat ion dose c r i t e r i a assumed for this miss ion were derived from

data presented in a recen t study of Ear ly Orbital Space Stations (EOSS) by (4) McDonnell-Douglas Corporat ion, Table V-3 shows the maximum-al lowable

dose proposed for this type miss ion , the expected dose due to natural space

radiation, and (by subtraction) the maximum dose allowed from the reac to r .

Different values a r e shown for the allowable and expected dose to the whole

body and blood-forming organs , the lens of the eye and skin. The expected

space radiat ion dose is based on the same orbi t altitude and inclination as the

OWS and allows for s t ruc tu re and body self-shielding.

1,422

1,135

440

208

761

120

340

2,900

214

410

7,950

477

16,500


TABLE V-3

RADIATION DOSE CRITERIA

D u r a t i o n (days )

W h o l e b o d y and b l o o d - f o r m i n g o r g a n s

L e n s of e y e

Sk in of -whole b o d y

Sk in of e x t r e m i t i e s

M a x i m u n n A l l o w a b l e D o s e ( r e m )

60

50

200

275

600

90

60

225

300

650

180

80

240

350

750

360

100

270

4 0 0

900

S p a c e R a d i a t i o n ( r e m )

60

9

40

40

40

90

14

59

59

59

180

28

118

118

118

360

56

238

238

238

M a x i m u m Allo-wable D o s e f r o m R e a c t o r

( r e m )

60

41

160

23 5

560

90

4 6

166

241

591

180

52

122

232

632

360

44

32

162

662

The las t column in Table V-3 shows that the allowable reac tor dose to the

lens of the eye is the smal les t and therefore controls the shield design. For

miss ions up to one year the r eac to r dosera te should therefore not exceed approxi

mately 32 r e m / y r . In the shielding calculations per formed for this study a

maximum-al lowable operating dose from the reac to r was establ ished in the

range of 20 to 30 r e m / y r ,

(2) Geometry and Operational Mode

Figure V-4 shows the proposed integration a r r angemen t for the nuclear

power sys tem and the OWS. The shaded zones super imposed on this a r r a n g e

ment identify general regions with different radiation dose c r i t e r i a . The p r imary

shielded zone cor responds to a cone with a 10° half-angle which includes the

basic Workshop s t ruc tu re where approximately 99% of the c r ew ' s t ime will be

spent, the p r e s su r i zed exper iment canis te r which would contain radiat ion-

sensit ive film, and approximately a 10-ft radia l c lea rance around the Workshop

for possible EVA or other external ly mounted exper iments . The design dose

point shown is located at the control station for the Workshop, which is the

c loses t point to the reac tor which would be occupied routinely. Dosera tes

c loser to the reac tor and further back into the Workshop would vary approxi

mately as the inverse square of the distance from the r e a c t o r .


r - APOLLO COMMAND AND SERVICE MODULE

> I

>

O

- k

-~0

PRESSURIZED r-EXPERIMENT \ CANISTER

FEET

8-JY22-099-37A

Figure V-4. Radiation Shield Design Cr i t e r i a

> HH i

> O

00 Ip'

- J

Figure V-5, 477 Shield Outline, Reference Design 8-J1-099-1

The s h a d e d con i ca l r e g i o n ex tend ing f r o m the p r i m a r y sh i e lded zone out to

a half ang le of 24° i s the s c a t t e r sh ie ld z o n e . The m a j o r c o n s i d e r a t i o n s in th i s

r e g i o n a r e s c a t t e r i n g of n e u t r o n s and g a m m a s f rom p a r k e d C S M ' s and f rom the

s m a l l p o r t i o n of the r a d i a t o r wh ich e x t e n d s ou t s ide the p r i m a r y sh ie lded zone .

In g e n e r a l the d o s e r a t e s in the s c a t t e r s h i e ld zone can be one or two d e c a d e s

h i g h e r than in the p r i m a r y zone b e f o r e s c a t t e r e d r a d i a t i o n into the w o r k s h o p

b e c o m e s i m p o r t a n t .

The t h i r d zone of i n t e r e s t c o v e r s the path tha t m i g h t be t aken by a m a n n e d

CSM a p p r o a c h i n g the w o r k s h o p for r e n d e z v o u s and docking . Al lowable d o s e

r a t e s in t h i s r e g i o n d e t e r m i n e the a m o u n t of sh ie ld ing which m u s t be p l aced on

the s ide of the r e a c t o r if i t i s o p e r a t i n g du r ing the r e n d e z v o u s m a n e u v e r . If

such sh i e ld ing i s p r o v i d e d , the sh i e ld i s c l a s s i f i e d a s a 477 sh ie ld even though

the s h i e l d i n g i s not s p h e r i c a l l y s y m m e t r i c a l . Without s ide sh ie ld ing the sh ie ld

i s r e f e r r e d to a s a shadow sh i e ld . With a shadow sh ie ld the r e a c t o r would have

to be shut down s h o r t l y b e f o r e the r e n d e z v o u s m a n e u v e r i s p e r f o r m e d . Both 477

and s h a d o w - s h i e l d d e s i g n s w e r e evo lved in th i s s tudy.

If the p r i m a r y s h i e l d e d - z o n e ang le w e r e ex tended to inc lude the p a r k e d

C S M ' s wi th the s a m e dose c r i t e r i a a s a r e u s e d wi th in the o r b i t a l w o r k s h o p ,

e x c e s s i v e sh i e ld w e i g h t s would r e s u l t . Thus the p r o p o s e d m u l t i z o n e dose m o d e l

r e p r e s e n t s a r e f i n e m e n t w h i c h m o r e a c c u r a t e l y r e p r e s e n t s the e x p e c t e d o p e r a t i n g

cond i t i ons and r e s u l t s in r e d u c e d sh i e ld we igh t s whi le p r e s e r v i n g a feas ib le i n t e

g r a t i o n c o n f i g u r a t i o n and o p e r a t i o n a l e n v i r o n m e n t ,

(3) R e a c t o r P C S G e o m e t r y

The r e a c t o r d e s i g n shown in Sec t ion IV-A can be u s e d wi th e i t he r a 477 o r

s h a d o w - s h i e l d con f igu ra t i on . In e i t h e r c a s e the g e o m e t r y of the sh ie ld i s a l s o

af fec ted by the l ayout of the p o w e r - c o n v e r s i o n e q u i p m e n t in the sh ie ld g a l l e r y .

F i g u r e V-5 shows the 477-shield g e o m e t r y for the p r o p o s e d i n t e g r a t i o n a r r a n g e

m e n t , r e a c t o r d e s i g n , and m i n i m u m g a l l e r y d i m e n s i o n s . The 10° cone half-

ang le c o m b i n e d wi th the g a l l e r y d i m e n s i o n s d e t e r m i n e the d i a m e t e r of the l o w e r

g a m m a and n e u t r o n s h i e l d s . The g e o m e t r y of the u p p e r n e u t r o n sh ie ld s u r r o u n d

ing the r e a c t o r i s d e s i g n e d to l i m i t the s c a t t e r e d r a d i a t i o n f r o m the p a r k e d C S M ' s

to t o l e r a b l e v a l u e s . N e u t r o n s s c a t t e r e d f r o m the C S M ' s a r e p r i m a r i l y t h o s e tha t

e m e r g e f r o m the s u r f a c e of the 477 sh i e ld a t g r a z i n g a n g l e s be tween 10 and 2 4 ° .

A I - A E C - M E M O - 12717

129

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8-JV22-099-38A

F i g u r e V - 6 , Shadow Shie ld Out l ine , R e f e r e n c e Des ign

F i g u r e V-6 shows the con f igu ra t i on of the shadow sh ie ld . The lower sh ie ld

d i a m e t e r i s the s a m e a s tha t of the 477 s h i e l d , s ince bo th d e s i g n s have the s a m e

g a l l e r y a r r a n g e m e n t . The u p p e r s h i e ld in t h i s c a s e is de s igned to p r o t e c t the

s e r v i c e m o d u l e s f r o m r e a c t o r d i r e c t r a d i a t i o n ,

(4) M a t e r i a l s

Shie ld ing m a t e r i a l s s e l e c t e d for bo th the shadow and 477 sh ie ld d e s i g n s a r e

P b , U, and LiH, P b i s u s e d for the f i r s t g a m m a sh ie ld i m m e d i a t e l y ad j acen t to

the r e a c t o r b e c a u s e of i t s low s e c o n d a r y g a m m a p roduc t ion r a t e s and i ts r e l a

t i v e l y h igh d e n s i t y . Dep le t ed U i s u s e d for the s econd g a m m a sh i e ld l oca t ed at

the b o t t o m of the g a l l e r y w h e r e the n e u t r o n flux h a s been d e c r e a s e d s e v e r a l

o r d e r s of m a g n i t u d e , LiH i s u s e d for bo th n e u t r o n sh i e ld s due to i t s h igh

n e u t r o n - s h i e l d i n g e f f e c t i v e n e s s , good p h y s i c a l and m e c h a n i c a l p r o p e r t i e s , and

a d v a n c e d t e c h n o l o g i c a l s t a t u s . Tab le V - 4 shows the effect ive d e n s i t i e s of the

sh i e ld m a t e r i a l s u s e d . In the c a s e of LiH the d e n s i t y h a s been i n c r e a s e d 30%

to a c c o u n t for cann ing and i n t e r n a l s t r u c t u r e ,

T A B L E V - 4

DENSITY O F SHIELD MATERIALS

M a t e r i a l Dens i t ( Ib / in .^) %

Lead

Uranium

Lithium hydride

0.410

0.676

0.03 5*

'=An a d d i t i o n a l 3 0% is inc luded to a c c o u n t for cann ing .

(5) R e s u l t s

Us ing the b a s i c dose c r i t e r i a , g e o m e t r y , and m a t e r i a l s d i s c u s s e d above , a

n u m b e r of i t e r a t i o n s w e r e m a d e b e t w e e n sh ie ld t h i c k n e s s e s and d o s e r a t e e s t i

m a t e s . The b a s i c tool u s e d for t h i s a n a l y s i s was the Dup lex -2 sh ie ld o p t i m i z a

t ion code wh ich d e t e r m i n e s a n e a r - o p t i m u m d i s t r i b u t i o n of t h i c k n e s s e s for the

v a r i o u s sh i e ld l a m i n a t i o n s . In add i t i on , the DOT and ANISN codes w e r e u s e d

A I - A E C - M E M O - 1 2 7 1 7 131

to d e t e r m i n e n e u t r o n l e a k a g e flux f r o m the u n s h i e l d e d r e a c t o r . The s o u r c e s of

r a d i a t i o n inc luded m the a x i a l ( shadow) d i r e c t i o n w e r e c o r e n e u t r o n s , c o r e g a m m a

r a y s , g a m m a r a y s f r o m r a d i o a c t i v e s o d i u m - 2 4 m the p r i m a r y loop , and s e c o n d

a r y gammia r a y s f r o m bo th g a m m a s h i e l d s . In the r a d i a l d i r e c t i o n only, t h r e e

s o u r c e s w e r e c o n s i d e r e d , n a m e l y , c o r e n e u t r o n s , g a m m a r a y s , and s e c o n d a r y

g a m m a r a y s f r o m the l ead sh ie ld , S o d i u m - 2 4 g a m m a r a y s w e r e not i nc luded m

the r a d i a l d i r e c t i o n s ince t h e i r d o s e c o n t r i b u t i o n i s s m a l l c o m p a r e d to the r a d i a l -

d o s e c r i t e r i a .

The sh i e ld d e s i g n i t e r a t i o n s n a r r o w e d down to the 477 and s h a d o w - s h i e l d d e

s igns shown on F i g u r e s V-5 and - 6 , r e s p e c t i v e l y . The t o t a l we igh t of the shadow

sh ie ld ( inc luding s t r u c t u r e ) i s e s t i m a t e d to be 14,330 lb . The we igh t of the 477

sh i e ld IS e s t i m a t e d to be 16,500 lb . Thus for the spec i f ic c r i t e r i a and c o n s t r a i n t s

u s e d the 477 sh i e ld i s only 15% h e a v i e r than the shadow sh i e ld .

F o r the 477 sh i e ld the i n t e g r a t e d d o s e to the a s t r o n a u t s d u r i n g r e n d e z v o u s

has b e e n c a l c u l a t e d to be l e s s than 5 r e m wi th the r e a c t o r a t full p o w e r , a s s u m

ing they a p p r o a c h the W o r k s h o p f r o m one m i l e out a t 1 m i / h r m a d i r e c t i o n

n o r m a l to the OWS c e n t e r l i n e .

The e s t i m a t e d r a d i a t i o n d o s e r a t e s a t the c o m m a n d and c o n t r o l s t a t ion w i t h m

the OWS a r e shown on Tab le V - 5 , for both sh ie ld t y p e s . The d i r e c t d o s e is the

T A B L E V - 5

E S T I M A T E D RADIATION D O S E R A T E S AT SATURN-V O R B I T A L WORKSHOP COMMAND AND CONTROL STATION

Number of Parked CSM's

Direct Dose, m r e m / h r

Command and Service Module Scattered Dose, m r e m / h r

Radiator Scattered Dose, m r e m / h r

Total, m r e m / h r

Annual Dose, r em

47r Shield

1

1.56

0.53

0.08

2.17

19.0

2

1.56

1.06

0.08

2.70

23.7

Shadow Shield

1

1.56

0.88

0.08

2.52

22.1

2

1.56

1.76

0.08

3.40

29.8

A I - A E C - M E M O - 12717 132

same in both cases but the sca t te red dose from the parked CSM's is slightly

higher for the shadow-shield design and depends on how many CSM's a re parked.

Thus the total annual dosera te es t imate from all sources ranges from 19 to

slightly l e s s than 30 r e m per year , which is within the dose c r i t e r i a assumed

for the study. It should be mentioned that the amount of t ime spent by any

single crew m e m b e r in the command and control station has been est imated to (4) be approximately 17%. The dosera tes in the aft portions of the OWS where

the crew will be spending a l a rge r fraction of their total t ime will be lower than

the values shown. Thus the dosera tes and shield-weight es t imates a re believed

to be conservat ive . Additional more -de ta i l ed shield design and analysis beyond

the scope of the p resen t study a re requi red , however, to obtain more accurate

dose or weight e s t ima t e s .

b, PCS Instal lat ion

The TE PCS along with the pumps, p r imary- loop expansion compensa tors ,

and interconnecting piping a r e located in a gal lery between the two shield sections

as shown in F igure V-7, The components were ar ranged to minimize the d iam

eter and height of the gal lery since both of these have a relat ively strong effect

on the shield weight. The gal lery height is 20 in. and all components fit within

the 10° shield cone having a d iameter of 68 in. at the bottom of the gal lery. An

i somet r i c view of the r eac to r and ga l le ry a r rangement that provides a c l ea re r

understanding of the pipe routing is shown in Figure III-2.

For this design the main TE conver ter assembly is r ea r ranged as shown in

Figure V-8 . The basic s t ruc tu re of the assembly is the same as descr ibed in

Section IV-B-3 ; however, the a t tachments to the main manifolds a r e changed.

Also the unit is placed in the ga l le ry with the 4-packs in the horizontal plane.

This orientat ion presen ts no par t icu la r problem, however, since the la te ra l

design load factors a r e approximately two- th i rds of the longitudinal load factors

and the unit mus t be designed with about the same strength in all d i rect ions .

In the assembly sequence the ga l lery components a re mounted on top of the

secondary shield before mating to the top shield. Such an a r rangement allows

for c lear access to all piping runs and components during assembly . After ins ta l

lation and checkout of the PCS components , the bottom shield and the gal lery


r - ^ A

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NaK EXAPNSION COMPENSATOR (PRIMARY LOOP)

THERMOELECTRIC CONVERTER (MAIN)

-SECONDARY SHIELD

SECTION A " A Ul-A

HEAT REJECTION LOOP NaK

THERMOELECTRIC CONVERTER (PUMP)

ELECTROMAGNETIC PUMPS

IMCHES

0 10 20 30 40 50 60 70 80 ^O 100 110 120

I I ' I ' - r^-T^ \ V ' I ' I ' i' 1 0 I 2 3 4 5 6 7 8 9 10

FEET

8-JY25-119-40

F i g u r e V - 7 , 25 -kwe N u c l e a r T h e r m o e l e c t r i c P o w e r Supply, T w o - L o o p S y s t e m

-19.50

< } UP

e Si

(\ r\ r\

-/2.50-

H-

7

23.sa c —-

Lim

// J.5

• • Figure V-8 . Thermoelec t r i c Power

Package with Modified Po r t Locations


a s s e m b l y a r e m a t e d to the top sh ie ld and r e a c t o r . The r e a c t o r coolan t p ipes

a r e t hen c o n n e c t e d p r o v i d i n g a c o m p l e t e l y s e a l e d p r i m a r y loop. The r a d i a t o r

i s nex t m a t e d to the l ower p o r t i o n of the s e c o n d a r y sh ie ld and the h e a t - r e j e c t i o n

p ip ing c o n n e c t e d .

The c o n v e r t e r a s s e m b l y and p u m p yoke a s s e m b l y a r e m o u n t e d to the lower

s h i e l d . P i p e a n c h o r s wi l l be i n c o r p o r a t e d a t each point w h e r e l i ne s p e n e t r a t e

the m a i n c o n v e r t e r box and n e a r the p u m p m o u n t s . C a l c u l a t i o n s of the piping

l o a d s for the w o r s t c a s e , in which the NaK s y s t e m has h e a t e d to o p e r a t i n g t e m

p e r a t u r e bu t the s h i e l d s a r e s t i l l a t about 100°F , showed tha t the m a x i m u m

s t r e s s o c c u r r e d a t the point w h e r e the l i n e s bend downward a f te r coming out

r a d i a l l y f r o m the r e a c t o r . E v e n t h e s e s t r e s s e s w e r e below the a l lowable of

24,000 p s i ; h o w e v e r , t h e y could be r e d u c e d with a m o r e g e n e r o u s elbow so tha t

a l l s t r e s s e s would be be low about 16,000 p s i .

The e x p a n s i o n c o m p e n s a t o r s for the p r i m a r y loop a r e a t t a c h e d to the n e a r e s t

p r i m a r y - l o o p l ine by a 3 / 8 - i n . - d i a m fill l i n e . Th i s l ine would run to the high

poin t of the loop d u r i n g l aunch , a d i f fe ren t loca t ion depending on the s y s t e m

o r i e n t a t i o n du r ing l aunch , and would be i n s i d e the m a i n l ine o r w r a p p e d wi th it

to p r e v e n t NaK f r e e z i n g .

c . R a d i a t o r

2 The fixed f i nned - tube r a d i a t o r h a s 1287 ft of u s a b l e r a d i a t i n g a r e a . A

c r o s s - s e c t i o n of a t y p i c a l r a d i a t o r pane l i s shown in F i g u r e V - 9 . In it a r e

96 ind iv idua l NaK t u b e s of 3 / 8 - i n . - d i a m 347 s t a i n l e s s s t e e l wi th a 0.020-in. wa l l

t h i c k n e s s . E x t r u s i o n s of 6016 a l u m i n u m , wh ich p r o v i d e bo th the fin and m e t e -

o r o i d a r m o r , a r e d i f fus ion -bonded to t h e s e t u b e s . The ind iv idua l tube- f in p i e c e s

a r e a s s e m b l e d into p a n e l s by we ld ing the NaK tubes to h e a d e r s a t e i t h e r end.

E a c h q u a d r a n t c o n t a i n s s ix i nd iv idua l p a n e l s . The t h r e e longi tud ina l p a n e l s a r e

r e q u i r e d to m i n i m i z e the NaK p r e s s u r e - d r o p a s we l l a s for e a s e of f ab r i ca t i on .

The two c i r c u m f e r e n t i a l p a n e l s on e a c h q u a d r a n t a r e for e a s e of a s s e m b l y . The

NaK supp ly and r e t u r n l i n e s a r e r o u t e d to a l low for d i f f e ren t i a l expans ion .

The p a n e l s a r e a t t a c h e d to a t i t a n i u m s e m i m o n o c o q u e s t r u c t u r e by c l i p s tha t

a l low d i f f e r en t i a l e x p a n s i o n b e t w e e n the tubes and the s t r u c t u r e . The s t r u c t u r e

i s d e s i g n e d to s u p p o r t the r a d i a t o r du r ing l aunch and a c c o m m o d a t e docking and

m a n e u v e r i n g loads when the p lan t i s ex tended in o r b i t . The r a d i a t o r s t r u c t u r e

A I - A E C - M E M O - 12717 137

I

>

o

CO H

o I

MANIFOLD (CRES TUBE)

RADIATOR TUBE (CRES)

SUPPORT (Ti ALLOY)

RADIATOR FIN AND ARMOR (ALUMINUM)

STRUCTURE SKIN (TITANIUM)

CORRUGATED STIFFENER (TITANIUM)

NaK SUPPLY LINE (CRES TUBE)

STRUCTURE FRAME (TITANIUM)

1-14-69 UNC 7759-52100

Figure V-9. P r e a s s e m b l e d Radiator Assembly Integration Details

is not required to support the r eac to r shield weight during launch. The 0.010-in.-

thick corrugated stiffeners and s t ruc tura l skin and the frames a r e all made of

t i tanium since the maximum operating t empera tu re of the s t ruc ture will be be

tween 650 and 700°F.

d. St ructure

The p r i m a r y loadpaths for the sys tem a r e shown in Figure V-10. The LiH

upper shield is re la t ively light and will be supported by i ts own shell . It will

1. UPPER LiH SHIELD

INTERMEDIATE LiH SHIELD

REACTOR

477 GAMMA SHIELD

STRUCTURE

STRUCTURAL PANEL

ATTACHMENT RING

LOWER LiH SHIELD

RADIATOR

1-13-69 UNCI 7759-52101

Figure V-10. Power System Loadpath Schematic


> I—I I

> H O 1

o

- v j

134 4 ft

3.0 ft

MSEC NOSE FAIRING

REACTOR

LAUNCH SUPPORT STRUCTURE

SHROUD/ADAPTOR

RADIATOR

DOCKING SUPPORT STRUCTURE

MDA

SLA

INSTRUMENTATION UNIT

SATURN V WORKSHOP

PRESSURIZED ATM CANNISTER

INTERSTAGE STRUCTURE

S-ll STAGE

143 5 ft

LAUNCH ESCAPE SYSTEM

COMMAND MODULE

SERVICE MODULE

SIVB

S-ll STAGE (REFl

DRY S-V WORKSHOP WITH NUCLEAR POWER SYSTEM STANDARD APOLLO SATURN V

8-JI4-099-64

Figure V - I l . Integral Saturn-V Launch Configuration, Nuclear Thermoelec t r ic Power System

be r e m o v a b l e wi th a bo l t r i n g on i t s l o w e r ou t e r p e r i p h e r y . Its loadpa th wi l l

follow down the o u t e r she l l of the i n t e r m e d i a t e LiH sh i e ld . The r e a c t o r and the

477 g a m m a sh i e ld wi l l be s u p p o r t e d on a c o m m o n c o n i c a l she l l wi th in the i n t e r

m e d i a t e LiH sh ie ld and wh ich i n t e r s e c t s the ou t e r she l l at the lower o u t e r

p e r i p h e r y .

To p r o v i d e m a x i m u m v o l u m e and a c c e s s to the g a l l e r y du r ing s y s t e m fab

r i c a t i o n , the s t r u c t u r e ad j acen t to the g a l l e r y i s a t the ou te r l im i t of the sh ie ld

a r e a . A s e r i e s of p e r m a n e n t p o s t s wi l l f o r m the b a s i s of th i s s t r u c t u r e . T h e s e

wi l l be g iven t o r s i o n a l r i g i d i t y by s t r u c t u r a l p a n e l s t ha t can be r e m o v e d for

a c c e s s to the g a l l e r y on the g round .

The s t r u c t u r e of the l o w e r sh i e ld wi l l be the ou te r she l l wi th a t t a c h m e n t

r i n g s at both the l o w e r and u p p e r o u t e r e d g e . The s e l e c t i o n of the a t t a c h m e n t

r i n g wi l l depend on the l aunch m o d e , a s the power s y s t e m is des igned to be

l a u n c h e d in e i t h e r d i r e c t i o n . The r a d i a t o r s t r u c t u r e i s t ied into the l ower a t

t a c h m e n t r i n g and i s r e q u i r e d to s u p p o r t only the r a d i a t o r .

The p r i m a r y r e a c t o r and s h i e ld s t r u c t u r e is 316 s t a i n l e s s s t e e l . Se lec t ion

of th i s m a t e r i a l is d i c t a t e d by c o m p a t i b i l i t y with LiH and s h i e l d - c a s t i n g -

t e m p e r a t u r e c o n s i d e r a t i o n s .

3. O p e r a t i o n a l Mode

a. Launch Opt ions

S e v e r a l op t ions a r e a v a i l a b l e for l aunch ing the n u c l e a r powerp l an t into o r b i t

and m a t i n g it to the S a t u r n - V OWS. If the OWS i s l aunched u n m a n n e d (which i s

be ing c o n s i d e r e d ) the p o w e r p l a n t could be m o u n t e d on top of the s t ack a t t a c h e d

to the f o r w a r d end of the MDA, a s shown in F i g u r e V - I I . In th i s c a s e the p o w e r -

p lan t would be a l r e a d y l o c a t e d in i t s o p e r a t i o n a l pos i t i on , r e a d y for subsequen t

s t a r t u p , e x t e n s i o n , and o p e r a t i o n a f te r the OWS is m a n n e d .

The o v e r a l l he igh t of the S a t u r n - V OWS s t ack wi th the n u c l e a r power s y s t e m

m o u n t e d a s shown on F i g u r e V-11 i s about 9 ft l e s s than tha t of the s t a n d a r d

A p o l l o / S a t u r n - V inc lud ing the l aunch e s c a p e s y s t e m . The n u c l e a r power s y s

t e m s h r o u d , i nc lud ing the s t a n d a r d M a r s h a l l Space F l i gh t C e n t e r (MSEC) nose

f a i r i n g , i s about 20 ft l o n g e r t han the Apol lo CSM, h o w e v e r , and the c e n t e r of

A I - A E C - M E M O - 1 2 7 1 7 141

NOSE FAIRING

46.3 ft

28 ft

22 ft

DOCKING PROBE

SHROUD/ADAPTOR

RADIATOR 82.1 ft

REACTOR

SERVICE MODULE

SLA

^NSTRUMENTATION UNIT

SIVB

52.6 ft

STANDARD APOLLO

SATURN IB

A 1

1 J

8-J14-099-63

u re V-12. Separate Launch Configuration, Saturn-IB Service Module


gravity of the power sys tem is near the top. Therefore, this configuration

would requ i re further analysis to de termine whether the aerodynamic and

s t ruc tura l cha rac t e r i s t i c s a r e acceptable .

F igure V-12 shows the launch configuration for a separa te unmanned launch

of the nuclear power sys tem using the Saturn-IB/Service Module (SIB/SM). The

SIB/SM combination has been studied and proposed as an unmanned launch vehicle

combination by North American Rockwell, Space Systems Division, For the

p resen t application, the service module would serve both as a mu l t i p l e - r e s t a r t

third stage to reach the parking orbit and final orbit, and as a maneuverable

rendezvous vehicle. The power sys tem would be supported from the service

module with the r eac to r / sh i e ld assembly at the lower end and a docking adaptor

at the upper end. After rendezvous with the manned OWS and docking have been

achieved, the se rv ice module would be disconnected from the power sys tem and

discarded. F igure V-13 shows a s imi lar launch configuration for a separate

unmanned launch using the Titan-III Trans tage . In this case the Transtage

se rves the same function as the serv ice module in the SIB/SM vehicle. In

ei ther case some modifications would be required for the unmanned rendezvous

maneuver . These modifications have been studied by the vehicle cont rac tors

and found to be reasonable and feasible .

The available payloads and marg ins for the designated orbit , launch vehicles,

and modes d iscussed above a r e summar ized in Table V-6. The payload infor

mation was obtained from personnel at the Martin Mariet ta Corporation, Denver,

Colorado, North Amer ican Rockwell 's Space Systems Division, Downey, Cali

fornia, and NASA-MSFC, Huntsvil le , Alabama.

The g ross payload for an unmanned launch of the OWS on a two-stage

Saturn-V is 186,000 lb. A d i rec t ascent to the 270 n. mi , 50° orbit is neces

sa ry in this c a s e , since multiple burn of the S-2 stage is not feasible with the

p resen t engines due to the short burn t ime that would be required for a Hohmann

t ransfe r from a parking orbi t . This payload capability is about 65,000 lb l ess

than that achievable with the manned launch, where the CSM propulsion system

can be used to t r ans fe r the OWS to the des i red orbit .

The cu r r en t Saturn-V OWS weight es t imate is in the range of 156,000 lb for

a t h r e e - m a n vers ion to 188,000 lb for a s ix-man design, including supplies.


NOSE FAIRING

DOCKING PROBE

SHROUD/ADAPTOR

RADIATOR

REACTOR

TITAN III TRANSTAGE

Figure V-13. Separate Launch Configuration, Titan-III

Transtage

8-J14-099-62

TABLE V-6

LAUNCH VEHICLE PAYLOAD ESTIMATES''

Launch Mode

I^aunch veh ic le

G r o s s pay load , lb

Orb i ta l Workshop weight , t h r e e - m a n / s i x - m a n , lb

Net payload ava i l ab l e for n u c l e a r power s y s t e m , lb

Nuc lea r power s y s t e m we igh t , ! lb:

wi th 477 sh ie ld

with shadow sh ie ld

Pay load m a r g i n , lb; with 477 shie ld

with shadow sh ie ld

In t eg ra l Unmanned D i r e c t A s c e n t

T w o - s t a g e S a t u r n - V

186,000

156,000/188,000

30 ,000 / ( -2 ,000)

27,000

24,800

+3 ,000 / ( -29 ,000)

- f5 ,200/( -26,800)

S e p a r a t e Unmanned, wi th Hohmann T r a n s f e r and Rendezvous

T i t a n - m C ( T r a n s t a g e )

23,000

22,700

27,000

24,800

(-4,300)

(-2,100)

T i t an - I I IF ( T r a n s t a g e )

34,000

33,700

27,000

24,800

+6,700

+ 8,900

S a t u r n - I B / S M

28,800

28,500

27,000

24,800

+ 1,500

+3,700

*Orbi t a l t i tude = 270 n. m i Orbi t inc l ina t ion = 50°

t i n c l u d e s 2 ,500- lb s h r o u d / a d a p t o r


e x p e r i m e n t a l e q u i p m e n t , and a 12 .5 -kwe s o l a r - p a n e l b a t t e r y power s y s t e m .

Thus the pay load a v a i l a b l e for the n u c l e a r power s y s t e m r a n g e s f r o m about

+ 30,000 to -2 ,000 lb for the t h r e e - and s i x - m a n OWS c o n c e p t s , r e s p e c t i v e l y .

The we igh t s shown for the n u c l e a r power s y s t e m inc lude e i t h e r 47T o r

shadow sh i e ld ing , a s no ted , and a 2 ,500 - lb a l l owance for the s h r o u d and dock

ing a d a p t o r . ( T h e s e n u m b e r s have b e e n rounded u p w a r d s to the n e a r e s t 100 lb . )

C o m p a r i s o n of the pay load w e i g h t s wi th da ta a v a i l a b l e shows tha t the i n t e g r a l

l a u n c h would be f e a s i b l e only wi th the t h r e e - m a n OWS, in which c a s e the m a r g i n

would be f r o m 3,000 to 5,200 lb depend ing on w h e t h e r a 477 o r shadow sh ie ld i s

u s e d . If t h e po'wer l e v e l of the s o l a r - c e l l b a t t e r y s y s t e m w e r e cut in half the

pay load m a r g i n could be i n c r e a s e d by a p p r o x i m a t e l y 11,000 lb . N o n e t h e l e s s ,

wi th the i n t e g r a l l aunch m o d e i t i s a p p a r e n t tha t the pay loads a v a i l a b l e for the

n u c l e a r p o w e r s y s t e m would be i n a d e q u a t e for the s i x - m a n OWS, which is the

one t h a t could m o s t p r o f i t a b l y u s e the add i t iona l p o w e r .

The p a y l o a d s a v a i l a b l e for the s e p a r a t e l aunch c a s e s a r e a l l b a s e d on an

i n i t i a l l aunch ang le of a p p r o x i m a t e l y 44.5 o r 135.5° to a c h i e v e a 100-mi p a r k i n g

o r b i t in the c o r r e c t i n c l i n a t i o n for the f inal o r b i t . Two b u r n s of the Ti tan

T r a n s t a g e o r the s e r v i c e m o d u l e a r e u s e d for the Hohmann t r a n s f e r . F u e l

w e i g h t r e q u i r e d for the r e n d e z v o u s wi th the OWS i s e s t i m a t e d to be a p p r o x i

m a t e l y 300 lb , which r e d u c e s the ne t pay load a v a i l a b l e for the n u c l e a r power

s y s t e m to the v a l u e s shown. It c a n be s e e n tha t a s e p a r a t e l aunch with the

T i t an - I I IC does not a p p e a r to be f e a s i b l e , but e i t h e r the T i t a n - I I I F or the

S a t u r n - I B / S M v e h i c l e s could be u s e d for t h i s m i s s i o n . (The T i t a n - I I I F i s the

d e s i g n a t i o n g iven to the l a u n c h v e h i c l e be ing deve loped for the Manned O r b i t a l

L a b o r a t o r y (MOL) p r o g r a m , bu t wi th the T r a n s t a g e r e p l a c i n g the MOL and

G e m i n i c a p s u l e . ) The e s t i m a t e d pay load m a r g i n s a v a i l a b l e wi th t h e s e v e h i c l e s

in the s e p a r a t e l aunch m o d e r a n g e s f r o m about 5 to 36%, depending on which

v e h i c l e and sh ie ld ing opt ion i s u l t i m a t e l y s e l e c t e d .

F r o m th i s p r e l i m i n a r y e v a l u a t i o n of l aunch o p t i o n s , it i s conc luded tha t the

s e p a r a t e u n m a n n e d l aunch and r e n d e z v o u s wi th a m a n n e d OWS u s i n g e i t h e r the

S a t u r n - I B / S M or the T i t a n - I I I F v e h i c l e a p p e a r s to be the m o s t p r o m i s i n g a p

p r o a c h . Add i t iona l m o r e - d e t a i l e d s t u d i e s beyond the s cope of the p r e s e n t s tudy

wi l l be r e q u i r e d , h o w e v e r , b e f o r e a f inal s e l e c t i o n can be m a d e .

A I - A E C - M E M O - 1 2 7 1 7 145

> l-H I

O

O I

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"PLANT-EXTENDED" SWITCH

DRUM-POSITION INDICATOR

EXTENDED < 3 1 0 0 F

REACTOR-OUTLET TEMPERATURE SWITCH

(NO SIGNAL WHEN TEMPERATURE >1325°F)

STARTUP' SHUTDOWN SWITCH

ELECTRICAL POWER CONTROL SWITCH

1-13-69 UNC TO DRUM-CONTROL CIRCUITS

(NO SIGNAL WITHIN DEADBAND AT25kwe)

7759-52105

F i g u r e V - 1 4 . S a t u r n - I V B P o w e r S y s t e m C o n t r o l Log ic

b . S y s t e m O p e r a t i o n

In Sec t ion I I I -C the g e n e r a l r e q u i r e m e n t s for s y s t e m c o n t r o l w e r e d i s c u s s e d

a long wi th the c h a r a c t e r i s t i c s of the four p h a s e s of a s t a r t u p . The d e t a i l s of a

c o n t r o l s y s t e m have b e e n f u r t h e r def ined for the spec i f ic c a s e of the S a t u r n - I V B

OWS power s y s t e m . F i g u r e V-14 shows the logic d i a g r a m for th i s c o n t r o l s y s

t e m and V- 15 s u m m a r i z e s the f e a t u r e s of the s t a r t u p inc lud ing the r e s u l t s of

p r e l i m i n a r y c a l c u l a t i o n s of the s t a r t u p t r a n s i e n t . In the logic d i a g r a m the

s t a n d a r d def in i t ion i s u s e d w h e r e both s i g n a l s to an "AND" box a r e r e q u i r e d

to p a s s a s i g n a l , whi le only one of the s i g n a l s to an "OR" box is r e q u i r e d .

In the following p a r a g r a p h s each p h a s e of the s t a r t u p wi l l be d e s c r i b e d .

(1) P h a s e 1, Shutdown M a r g i n R e m o v a l

All d r u m s a r e m o v e d s i m u l t a n e o u s l y a t a r a t e of one s t e p / 1 5 sec un t i l the

d r u m pos i t i on i n d i c a t o r shows they a r e a t 105° . At th i s t i m e , the d r u m s have

e a c h m o v e d 75° and the e l a p s e d t i m e i s 31 m i n . The d e g r e e of s u b c r i t i c a l i t y

at th i s point is d e p e n d e n t upon NaK t e m p e r a t u r e but would v a r y f rom 25^ at

7 5 ° F to 35« a t 1 5 0 ° F .

As the g a d o l i n i u m in the r e a c t o r c o r e i s b u r n e d out, the d r u m pos i t i on w h e r e

t h i s p h a s e i s t e r m i n a t e d would m o v e o u t w a r d , and l a t e r in l i fe , when hyd rogen

l e a k a g e o v e r c o m e s the b u r n o u t effect , i t would m o v e i n w a r d . The pos i t ion s e t

t ing in the c o n t r o l s y s t e m would be a d j u s t a b l e and could a lways be se t for a

p e r i o d of a t l e a s t one m o n t h wi th a c h a n g e .

(2) P h a s e 2, C r i t i c a l to S e n s i b l e H e a t

As s e e n in F i g u r e V - 1 4 , when the c o n t r o l d r u m s a r e r o t a t e d p a s t the 105°

pos i t i on the s t epp ing p e r i o d i n c r e a s e s to 30 s ec and only one d r u m i s m o v e d at

a t i m e . A s s u m i n g the r e a c t o r i s a t 100°F , it would go c r i t i c a l 24 m i n in to th i s

p h a s e , and the s e n s i b l e - h e a t t r a n s i e n t would o c c u r in a n o t h e r 17 m i n . A power

sp ike of a p p r o x i m a t e l y 180 kwt wi l l o c c u r a t th i s t i m e r e s u l t i n g in a m a x i m u m

r a t e of change of t e m p e r a t u r e of 1 2 0 ° F / m i n . The r e a c t o r would a u t o m a t i c a l l y

s t a b i l i z e a t a p p r o x i m a t e l y 2 7 0 ° F wi thou t f u r t h e r r e a c t i v i t y i n s e r t i o n ; h o w e v e r ,

the c o n t r o l s y s t e m wi l l c a u s e the d r u m s to r o t a t e f u r t h e r un t i l the r e a c t o r i s

at 3 I 0 ° F .

A I - A E C - M E M O - 12717 147

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(3) P h a s e 3, P o w e r p l a n t E x t e n s i o n

The e x t e n s i o n of the p o w e r p l a n t f r o m wi th in the sh roud would be a c c o m

p l i s h e d a t a r a t e of about 1 to 2 f t / m i n . In th i s d i s c u s s i o n it i s a s s u m e d tha t

full e x t e n s i o n r e q u i r e s 30 m i n .

A s the p o w e r p l a n t is ex tended the a v e r a g e r e a c t o r t e m p e r a t u r e t ends to

r e m a i n c o n s t a n t and the t h e r m a l power s t a r t s to i n c r e a s e as the r a d i a t o r is

g r a d u a l l y e x p o s e d . As th i s o c c u r s , p u m p power i n c r e a s e s and the s u p p l e m e n t a l

pumping u s e d d u r i n g the shutdown p e r i o d can be t e r m i n a t e d . As the AT in the

p r i m a r y loop i n c r e a s e s and the a v e r a g e r e a c t o r t e m p e r a t u r e r e m a i n s c o n s t a n t ,

the r e a c t o r o u t l e t - t e m p e r a t u r e d r i f t s u p w a r d , so no fu r the r r e a c t i v i t y is added

du r ing th i s p h a s e .

The m i n i m u m r a d i a t o r t e m p e r a t u r e o c c u r s when the u p p e r con i ca l s ec t ion

i s f i r s t e x p o s e d s i n c e the flow is s t i l l qui te low. The 310°F t e m p e r a t u r e l imi t

w a s s e l e c t e d so tha t t h i s m i n i m u m t e m p e r a t u r e would be about 150°F .

(4) P h a s e 4, R a m p to P o w e r

When the " p l a n t - e x t e n d e d " s w i t c h shows the s y s t e m is fully ex tended , the

r e a c t o r o u t l e t - t e m p e r a t u r e l i m i t is r a i s e d to 1325 °F and the s tepping p e r i o d is

r e t u r n e d to 15 s e c . R e a c t i v i t y i s then i n s e r t e d at a r a t e tha t r e s u l t s in a

p r i m a r y - l o o p h e a t i n g r a t e of about 2 0 ° F / m i n . As th i s hea t ing o c c u r s , a l l

p lan t funct ions a u t o m a t i c a l l y i n c r e a s e t o w a r d t h e i r o p e r a t i n g point , and in

a p p r o x i m a t e l y 43 m i n the n o r m a l o p e r a t i n g cond i t ions a r e r e a c h e d . Af te r

about 14 m i n of the r a m p the o p e n - c i r c u i t vo l t age of the c o n v e r t e r e x c e e d s

56 vo l t s and use fu l power b e c o m e s a v a i l a b l e .

The p a r a m e t e r u s e d to c o n t r o l t he p lan t and to t e r m i n a t e the r a m p to power

is e l e c t r i c a l c u r r e n t f r o m the T E c o n v e r t e r . This c u r r e n t i s u s e d to o p e r a t e

the e l e c t r i c p o w e r c o n t r o l swi t ch which a d d s o r s u b t r a c t s r e a c t i v i t y a s n e c e s

s a r y to m a i n t a i n the e l e c t r i c power wi th in a deadband about the s e l e c t e d power

l e v e l . As p r e v i o u s l y s t a t ed , t h i s se t t ing could be ad jus ted if o p e r a t i o n for a

p e r i o d of w e e k s w e r e p r o j e c t e d wi th p o w e r r e q u i r e m e n t s s ign i f i can t ly d i f ferent

than 25 k w e .

If for s o m e r e a s o n the power output i s not adequa t e when the r e a c t o r ou t l e t -

t e m p e r a t u r e r e a c h e s 1325 ° F , the i n s e r t i o n of r e a c t i v i t y is s topped , a s no ted in

A I - A E C - M E M O - 1 2 7 1 7 149

the c o n t r o l s y s t e m logic d i a g r a m . Th i s t e m p e r a t u r e l e v e l i s s t i l l we l l wi th in the

r a n g e w h e r e s e r i o u s d a m a g e or r a p i d d e g r a d a t i o n of the s y s t e m would not r e s u l t .

The above s t a r t u p s e q u e n c e would t a k e a p p r o x i m a t e l y 2 h r and 25 m i n f r o m

beg inn ing to f u l l - p o w e r .

To shut down, the s t a r t u p - s h u t d o w n s w i t c h i s m o v e d f r o m the " o p e r a t e " to

the " s h u t d o w n " p o s i t i o n . As s e e n in F i g u r e V-14 , th i s c a u s e s a l l d r u m s to s t ep

out t o g e t h e r and , s i n c e the p lan t would be ex tended , it would be at a 1 5 - s e c s t e p

ping r a t e . With the d r u r a s in the n o r m a l o p e r a t i n g pos i t i on , t h i s r e s u l t s in a

r e a c t i v i t y r e m o v a l r a t e of about 24{^/min. The r e s u l t i n g shutdown t r a n s i e n t w a s

shown in F i g u r e s I I I -7 and I I I -8 of Sec t ion I I I - C . The r a d i a t i o n flux f r o m f i s s i o n

ing would be r e d u c e d to about 1% in 3.5 m i n .

In abou t 1 h r the h e a t - r e j e c t i o n NaK t e m p e r a t u r e s would be n e a r 150°F and

r e t r a c t i o n of the s y s t e m into the s h r o u d would have to be s t a r t e d to p r e v e n t NaK

f r e e z i n g . The r e t r a c t i o n r a t e would be s low enough tha t suff ic ient r a d i a t o r would

be e x p o s e d to r e j e c t the r e a c t o r d e c a y h e a t wi thout e x c e s s i v e t e m p e r a t u r e s , but

fas t enough to m a i n t a i n the m i n i m u m r a d i a t o r t e m p e r a t u r e above about 1 0 0 ° F .

A r e s t a r t of the s y s t e m would be a c c o m p l i s h e d e x a c t l y a s the in i t i a l s t a r t .

H o w e v e r , b e c a u s e of an i n c r e a s e d r a d i a t i o n s o u r c e l eve l wi th in the r e a c t o r and

an i n c r e a s e d f u e l - t e m p e r a t u r e coef f ic ien t a f t e r a long p e r i o d of o p e r a t i o n , the

s e n s i b l e hea t t r a n s i e n t would be s ign i f i can t ly r e d u c e d . In fac t , if the r e s t a r t i s

u n d e r t a k e n b e f o r e r e t r a c t i o n of the s y s t e m into the s h r o u d , the c r i t i c a l - t o -

s e n s i b l e - h e a t p h a s e of the s t a r t u p would be a c c o m p l i s h e d wi th a 1 5 - s e c s t epp ing

r a t e , s i n c e the s o u r c e l eve l would s t i l l be n e a r the s e n s i b l e h e a t p o w e r l e v e l .

4. F i n a l R e a c t o r Shutdown and D i s p o s a l

At the end of the n u c l e a r p o w e r s y s t e m o p e r a t i o n a l l i f e t ime the r e a c t o r

would be shu t down, u s i n g the n o r m a l c o n t r o l s y s t e m , and d i s p o s e d of in a m a n

n e r wh ich wi l l m i n i m i z e the p o s s i b i l i t y of r a d i o l o g i c a l h a z a r d s .

N u m e r o u s s t u d i e s and e x p e r i m e n t s p e r f o r m e d in the A E C ' s ANS p r o g r a m

and the e x p e r i e n c e in the SNAP lOA fl ight t e s t p r o g r a m have p r o v i d e d a p r a c t i c a l

b a s i s for e s t a b l i s h i n g p r e l i m i n a r y n u c l e a r sa fe ty gu ide l ine s for SNAP r e a c t o r s .

The sa fe ty d e v i c e s and p r o c e d u r e s for the f a c t o r y - t h r o u g h - l a u n c h and o r b i t a l

A I - A E C - M E M O - 1 2 7 1 7

150

s tar tup phases of the miss ion would be s imi la r to and perform the same func

tions as those used for SNAP lOA flight. The lOA flight was completely reviewed

and approved by all government agencies affected. The fact that the reac tor is

not radioact ive until after it has been operated at power great ly simplifies the

nuclear safety r equ i remen t s for this par t of the miss ion .

The orbit altitude range of in te res t for the OWS mission is from 200 to

300 n . m i , for which e s t ima tes of the orbi tal lifetime of an abandoned space

station range from approximately 1 to 10 yr . If the reac tor power system

randomly r e - e n t e r e d 1 to 10 yr after shutdown, survived r e - e n t ry without burn-

up (which is quite probable with a 477' shield), and impacted on land, a small but

finite possibi l i ty of ser ious radiation exposure to anyone coming in close contact

with the debr is ex i s t s . To further reduce the r i sk of this situation occurr ing,

a l ternate means for safe disposal of the r eac to r have been proposed and analyzed (7) in detail . The two most promising disposal techniques a re : (a) boost the r e

actor to a higher orbit or , (b) deboost the reac tor into deep ocean a r e a s .

If the f i rs t option is used, an altitude of about 450 n . m i would provide orbital

s torage for seve ra l hundred y e a r s , after which t ime the f ission-product activity

would have decayed to safe leve ls . If the r eac to r is deboosted into deep ocean

a r e a s , radiat ion from the fission products would not pose a significant hazard .

References 7 and 8 presen t the re la t ive haza rds , rel iabil i ty es t imates , a t t i

tude control and propulsion r equ i r emen t s , etc , for the above disposal options.

If a separa te communicat ion, control , and propulsion package is used to auto

mat ica l ly boost or deboost the reac tor sys tem, the weight penalty would be ap

proximate ly 12 to 22%, depending on the alti tude and other var iables . The r e l i

abili ty of this equipment after extended s torage in space was est imated to be

from 0.85 to 0.95, and the r i sk of radiation injuries could thus be reduced by

about one o rde r of magnitude relat ive to that which would exist from random (9) r e - e n t r y . In the SNAP lOA Safeguards Report it was shown that the individual

r i sk probabil i ty due to random r e - e n t r y of a reac tor after sustained operation - 7 - 8

would be l ess than 10 for radiation injury and less than 10" for lethal rad ia

tion exposure . These hazards a re at least 6 o rde r s of magnitude lower than the

a l ready existing injury or death potential from all other accidental causes .


F o r the S a t u r n - V OWS m i s s i o n i t i s p r o p o s e d tha t the CSM u s e d for r o u t i n e

c r e w r o t a t i o n be u s e d to p r o v i d e the c o n t r o l and p r o p u l s i o n c a p a b i l i t y n e e d e d for

r e a c t o r d i s p o s a l . The r e l i a b i l i t y of the m a n n e d CSM for t h i s p u r p o s e should be

g r e a t e r than 0.99, the s e r v i c e m o d u l e ' s c o n t r o l and p r o p u l s i o n s y s t e m s should

be m o r e than a d e q u a t e for t h i s t a s k , and an e x t r a l aunch would not be r e q u i r e d .

B a s i c a l l y the p r o p o s e d d i s p o s a l t e c h n i q u e would be to decoup le the CSM and the

r e a c t o r p o w e r s y s t e m f r o m t h e i r r e s p e c t i v e docking p o r t s , couple t h e m t o g e t h e r ,

and then u s e the CSM to push the p o w e r s y s t e m up to a h i g h e r o r b i t or to deboos t

i t into the o c e a n . If r e q u i r e d , a s e p a r a t e , a u t o m a t e d d i s p o s a l s y s t e m ( c o n t r o l l e d

f r o m the g round or the OWS) could be i n c o r p o r a t e d in the p o w e r p l a n t p a c k a g e a s

a b a c k u p , in which c a s e the to t a l r e l i a b i l i t y for safe d i s p o s a l should exceed 0 .999.

The ind iv idua l r a d i a t i o n i n j u r y o r d e a t h p r o b a b i l i t y cou ld thus be r e d u c e d to l e s s

than 10 and 10 r e s p e c t i v e l y , w h i c h i s b e l i e v e d to be t e c h n i c a l l y and p o l i t i

c a l l y a c c e p t a b l e .

Al though the fo rego ing d i s c u s s i o n i s of n e c e s s i t y an o v e r s i m p l i f i e d s u m m a r y

of a c o m p l e x p r o b l e m , the s u g g e s t e d a p p r o a c h t o w a r d s a s s u r i n g a d e q u a t e n u c l e a r

sa fe ty m a r g i n s for t h i s m i s s i o n i s thought to be r e a s o n a b l e . Add i t iona l m o r e -

de t a i l ed s t u d i e s of the p r o p o s e d d i s p o s a l t e c h n i q u e s and h a z a r d a n a l y s e s s i m i l a r

to t h o s e m a d e b e f o r e ob ta in ing a p p r o v a l for the SNAP lOA flight t e s t wi l l be

r e q u i r e d ,

B . LUNAR BASE P O W E R P L A N T

1. M i s s i o n R e q u i r e m e n t s

R e a c t o r power s y s t e m s for m a n n e d l u n a r b a s e s w e r e s tud ied r e c e n t l y in a

(3 5)

jo in t NASA-AEC s tudy ' to d e t e r m i n e the d e s i g n and d e v e l o p m e n t r e q u i r e

m e n t s and the p e r f o r m a n c e c h a r a c t e r i s t i c s of th i s type p o w e r p l a n t for such a

m i s s i o n . The b a s i c r e q u i r e m e n t s and r e s u l t s r e g a r d i n g i n t e g r a t i o n , d e p l o y

m e n t , and o p e r a t i n g m o d e ob t a ined f r o m tha t s tudy a r e thought to be s t i l l val id

and have been r e t a i n e d , t h e r e f o r e , in the p r e s e n t s tudy for the p u r p o s e of u p

dat ing the r e a c t o r — T E s y s t e m d e s i g n and p e r f o r m a n c e c h a r a c t e r i s t i c s .

The key power s y s t e m r e q u i r e m e n t s for a l u n a r b a s e p o w e r p l a n t de s igned

to s u p p o r t ex t ended m a n n e d l u n a r e x p l o r a t i o n a r e s u m m a r i z e d on Tab le V - 7 .

A I - A E C - M E M O - 1 2 7 1 7 152

This m i s s i o n i s e n v i s i o n e d a s a l og i ca l ou tg rowth of the Apol lo and Advanced

Apol lo p r o g r a m s , w h e r e i n the l e v e l of e x p l o r a t i o n , c r e w s i z e , and s t ay t i m e s

would g r a d u a l l y i n c r e a s e in a step-wise fash ion . One o r two p e r s o n n e l s h e l t e r s

c a p a b l e of s u p p o r t i n g up to s ix m e n e a c h for s ix m o n t h s wi thout r e supply would

c o n s t i t u t e the l u n a r b a s e .

T A B L E V-7

KEY P O W E R SYSTEM R E Q U I R E M E N T S F O R LUNAR BASE

P o w e r l e v e l r a n g e of i n t e r e s t , kwe 10 to 30

N u m b e r of m e n 6 to 12

M i n i m u m l i f e t i m e , y r 1

P r e - o p e r a t i o n a l s t o r a g e on m o o n , m o ^6

A v a i l a b i l i t y 1975-1980

Al lowab le d o s e to a s t r o n a u t f r o m r e a c t o r , r e m 70

A l lowab le s e p a r a t i o n d i s t a n c e , m i ^ 1 2

A v a i l a b l e r a d i a t o r a r e a , ft 1500 to 2500

A l lowab le p o w e r p l a n t we igh t , lb 29,475

Shie ld c o n c e p t s a) I n t e g r a l 47T b) Lunar soi l

The b a s i c h o u s e k e e p i n g power r e q u i r e m e n t s have b e e n e s t i m a t e d to be

'~1 kwe p e r m a n , so the m i n i m u m luna r b a s e p o w e r p l a n t c a p a c i t y , t h e r e f o r e ,

would be in the r a n g e of 6 to 12 kwe , depend ing on the a c t u a l b a s e s i z e . Add i

t iona l p o w e r would be r e q u i r e d for e x p e r i m e n t s , r e c h a r g i n g m o b i l e v e h i c l e s ,

and s i m i l a r func t ions . The m a x i m u m p o w e r l eve l of i n t e r e s t would thus depend

on the s c o p e and n a t u r e of the e x p l o r a t i o n p r o g r a m , and would p r o b a b l y c o r r e

spond to the m a x i m u m c a p a b i l i t y t ha t could be p rov ided wi th in the payload l i m i t s

of the d e s i g n a t e d l aunch and landing v e h i c l e s . Up to two w e e k s e m e r g e n c y power

would a l s o be supp l i ed by fuel c e l l s .

The S a t u r n - V b o o s t e r c o m b i n e d wi th a Luna r Landing Vehic le (LLV) having

a ne t pay load c a p a c i t y of s l igh t ly l e s s than 30,000 lb ( landed on the luna r su r f ace )

w a s s e l e c t e d by NASA as the s t a n d a r d l o g i s t i c s s y s t e m for t h i s m i s s i o n . The

A I - A E C - M E M O - 1 2 7 1 7 153

a r e a a v a i l a b l e for fixed r a d i a t o r s wi th in the s t a n d a r d s h r o u d w a s abou t 1500 ft . 2

This can be i n c r e a s e d to a p p r o x i m a t e l y 2500 ft u s ing a l a r g e r s h r o u d of the

s i z e d e s i g n e d for the Voyage r m i s s i o n , o r by u s ing folding r a d i a t o r p a n e l s .

The n u c l e a r p o w e r p l a n t would be l anded a s a s e p a r a t e u n m a n n e d pay load in

the v i c in i t y of the l u n a r b a s e , m o u n t e d on the LLV. As long a s 6 m o of p r e

o p e r a t i o n a l s t o r a g e in the moon m i g h t be r e q u i r e d b e f o r e b a s e m a n n i n g and ful l -

power o p e r a t i o n .

T h r e e p o s s i b l e d e p l o y m e n t m o d e s and a s s o c i a t e d p lant c o n c e p t s w e r e c o n

s i d e r e d in the r e f e r e n c e d s tudy:

1) An o f f - loaded a r r a n g e m e n t w h e r e i n the r e a c t o r a s s e m b l y would be

b u r i e d in a hold in the l u n a r so i l and the p lan t would then be a s s e m

b led , c h e c k e d out , and s t a r t e d up on the l u n a r s u r f a c e ,

2) An i n t e g r a l p o w e r p l a n t u s i n g 47T sh ie ld ing and fixed r a d i a t o r s , a l l of

wh ich would be a s s e m b l e d and c h e c k e d out on E a r t h b e f o r e l aunch , and

3) An i n t e g r a l , 477 s h i e l d e d concep t s i m i l a r to 2) wi th dep loyab l e r a d i a t o r s

wh ich would be a s s e m b l e d on the m o o n .

The i n t e g r a l ( p r e - a s s e m b l e d ) p o w e r p l a n t concep t wi th a 477 sh i e ld w a s

s e l e c t e d , to r e d u c e a s t r o n a u t l a b o r and avo id t e c h n i c a l p r o b l e m s a s s o c i a t e d

with the o t h e r c o n c e p t s . C o n s e q u e n t l y in the p r e s e n t s tudy, c o n s i d e r a t i o n w a s

l i m i t e d to the i n t e g r a l de s ign a p p r o a c h u s i n g a 477 sh ie ld to r e d u c e the annua l

dose to the a s t r o n a u t s to the p r e v i o u s l y spec i f i ed v a l u e , 70 r e m . The a l l owab le

s e p a r a t i o n d i s t a n c e b e t w e e n the p o w e r p l a n t and the l u n a r s h e l t e r s w a s a l s o d e

t e r m i n e d to be u p to 1 m i l e , b a s e d on p o w e r t r a n s m i s s i o n and o p e r a t i o n a l c o n

s i d e r a t i o n s .

A n o t h e r i m p o r t a n t g e n e r a l c r i t e r i o n w a s tha t a s s e m b l y , s t a r t u p , and o p e r a

t ion of the p lan t should r e q u i r e a m i n i m u m of a s t r o n a u t l abo r o r a t t e n t i o n , s i nce

the p r i m a r y m i s s i o n o b j e c t i v e s a r e no t to w o r k on p o w e r p l a n t s but to e x p l o r e

the m o o n . Thus a p r e m i u m would be p l a c e d on p o w e r p l a n t s i m p l i c i t y and r e l i

ab i l i t y .

A I - A E C - M E M O - 12717 154

2. System Descript ion and Pe r fo rmance

The updated basel ine lunar powerplant design consis ts of the reference

25-kwe sys tem presented in Section III of this repor t , packaged in a configura

tion suitable for this miss ion . F igure V-16 shows the powerplant a r rangement ,

which is designed to be mounted on the top of the LLV. The reac to r , shield,

and PCS assembly is mounted along the center l ine , inside the radiator at the

base of the powerplant to maintain a low center of gravity. The r eac to r / sh i e ld

a s sembly is supported by s t ru t s attached to a mounting ring. The conver te r s ,

pumps, and p r imary- loop expansion compensators a re located atop the shield.

Each of the four radia tor sections consis ts of cylindrical and conical quadrants

connected in para l le l hydraul ical ly. The expansion compensators for the HRL's

a r e mounted within and near the top of the radia tor .

The electronic package used for remote s tar tup, control , and monitoring

of the sys tem from Ear th during low-power operation on the moon is located at

the top of the sys tem. The electronic package is thermal ly insulated from the

r e s t of the sys tem and is exposed to space for proper the rmal control .

A the rma l shroud covers the radia tor to reduce heat losses during storage

and periods -when the reac tor is shut down. When the sys tem is at full power,

the shroud is deployed, as shown in F igure V-17.

The reac to r con t ro l -d rum d r ive -moto r s and e lec t r ica l connectors a re lo

cated at the base of the sys tem where they a r e access ible to the as t ronauts

during r eac to r shutdown for possible maintenance.

Table V-8 summar i zes basel ine lunar power sys tem cha rac t e r i s t i c s . The

g ross e lec t r i ca l power is 27.0 kwe; los ses in t r ansmiss ion and power condition

ing reduce the power available at the lunar shelter to 22.9 kwe. The converter

power output is inverted to ac , t ransformed to 4160 volts, and t ransmit ted via

cable to the lunar she l te r .

The conver te r modules a r e identical with those of the reference sys tem de

sign and the Saturn-IVB Workshop design. The higher power output is due to

the l a rge r available radia tor a rea and consequent lower conver ter cold-clad

t e m p e r a t u r e .


26 9 ft

15 4 ft

PREOPERATIONAL REACTOR CONTROL AND COMM EQUIPMENT


NaK MANIFOLD

SHROUD ENVELOPE

RADIATOR (1500f|2)

INTERFACE LOAD RING

SUPPORT STRUT

NaK SUPPLY AND RETURN PIPES

REACTOR CONTROL MOTOR

POWER CONVERSION EQUIPMENT

REACTOR CONTROL MOTOR

REACTOR AND SHIELDING

8 JH 099 60

F i g u r e V - 1 6 . 25 -kwe N u c l e a r T h e r m o e l e c t r i c P o w e r Supply L u n a r B a s e A p p l i c a t i o n

SHROUD ENVELOPE

> l-H

>

n

O

-

48.8 ft (REF)

FIXED RADIATOR WITH STANDARD SHROUD

RADIATOR AREA = 1,500 ft^

NET POWER = 22.9 kwe

FIXED RADIATOR WITH LARGE SHROUD

RADIATOR AREA = 2,500 ft^ NET POWER = 35.5 kwe

FIXED AND FOLDING RADIATOR

RADIATOR AREA = 2,500 ft^

NET POWER = 35.5 kwe

FLEXIBLE NaK JOINT

FOLDING RADIATOR

HEAT SHIELD

LUNAR SURFACE

F i g u r e V - 1 7 . L u n a r B a s e P o w e r Supply Des ign A l t e r n a t e s

8-J14-099-58

T A B L E V - 8

BASELINE LUNAR P O W E R P L A N T CHARACTERISTICS (Sheet 1 of 2)

G r o s s p o w e r output , kwe

L o s s in c o n v e r s i o n and t r a n s m i s s i o n , kwe

Net power to s h e l t e r , kwe

T h e r m a l p o w e r , kwt:

R e a c t o r

C o n v e r t e r

P u m p c o n v e r t e r

( P r i m a r y loop

( H e a t - r e j e c t i o n loop)

R a d i a t o r


T e m p e r a t u r e , ° F :

R e a c t o r



R a d i a t o r

E f f i c i e n c i e s , %:

S y s t e m 3.74

C o n v e r t e r 4 .74

C o n v e r t e r C a r n o t 35.9

V o l t a g e s , vo l t s

S h e l t e r h i g h - v o l t a g e bus 4160.0

C o n v e r t e r :

T u b u l a r m o d u l e 14.4

C o n v e r t e r m o d u l e 57.6

Inle t

1045

1225

456

648

Out le t

1247

1025

656

448

27.0

4.1

22.9

613.4

570,0

38.4

25.6)

12.8)

581.4

5.0

A v e r a g e

1146

1125

556

548

A I - A E C - M E M O - 1 2 7 1 7 158

TABLE V-8

BASELINE LUNAR POWERPLANT CHARACTERISTICS (Sheet 2 of 2)

F lowra tes , l b / s e c ;

P r i m a r y loop 13,7

Heat - re jec t ion loop 13,1

P r e s s u r e - d r o p , psi :

P r i m a r y loop 3.0

Heat- re jec t ion loop 1,4

,2 Radiator a rea , ft

Weights, lb:

Reactor

Conver ter

R a d i a t o r / s t r u c t u r e

Pumps

Expansion compensa tors

Piping

Instrumentat ion and control equipment

Power conditioning

Subtotal

Nuclear shield

Reactor and power-conversion sys tem support s t ruc ture

Thermal shield

Direct cu r ren t t r ansmis s ion cable

Alternating cu r r en t t r ansmis s ion cable

Subtotal

Total sys tem weight

Allowable payload

Design miargin

7,525

14,000

1,575

23,100

29,475

6,375

1500

1,422

1,135

2,'760

440

210

518

240

800

525

500

300

250


TE CONVERTER


> n

O

- J

PUMP ASSEMBLY

REACTOR INLET NaK FLOW

INTERFACE LOAD RING

CONTROL DRUM DRIVE MOTOR 8-J14-099-59

F i g u r e V - 1 8 . R e a c t o r Shie ld ing and S t r u c t u r e , L u n a r B a s e C o n c e p t u a l

The total es t imated sys tem weight is 23,100 lb (including the 14,000-lb shield,

power-condit ioning equipment, and t r ansmi s s ion cables) which is 6,375 lb less

than the 29,475-lb payload l imit for the designated launch vehicle sys tem. This

marg in provides the possibi l i ty for increas ing the design power output by adding

TE conver te r s and rad ia tor a r ea .

The n e c e s s a r y inc rease in radia tor a r e a can be obtained by using radia tors

which can be deployed with the the rmal shroud, as shown in Figure V- 17, using

flexible NaK joints at the hinge points. An a l te rna te approach is to use fixed

rad ia to r s and a l a rge r shroud. The Voyager shroud design, for example, is the

same diameter and same general configuration as the standard shroud, except 2

that its cyl indrical section is long enough to accommodate an additional 1000 ft

of rad ia to r . These two a l te rna te configurations a r e shown on Figure V-17, along

with the basel ine sys tem. 2

As shown in Table V-9, with 2500 ft of radia tor available the e lec t r ic power output inc reased to 42,9 kwe gross and 35.5 kwe net. The reac tor power and

ou t l e t - t empera tu res a r e 962.4 kwt and 125 1°F still within the reference ZrH

reac to r per formance capabili ty. The shield weight was held constant at 14,000 1b

and the min imum separat ion distance would thus be increased to approximately

3250 ft for the same dosera te at the higher reac tor power level, A coolant A T

of 300°F is used to minimize pumping-power r equ i rement s . The total sys tem

weight is 27,675 lb; the allowable weight l imit is 28,775 lb (700 less than the

29,475 because of the use of the heavier Voyager shroud), which still leaves a

design marg in of 1100 lb. This marg in , while probably adequate, could be in

c reased by approximately 3200 lb by t ranspor t ing the power-conditioning equip

ment and t r ansmi s s ion cables to the moon in the lunar shel ter or other logist ics

vehic les .

Thus reac to r — TE lunar powerplants with net capacit ies up to 35 kwe appear

feasible within the cons t ra in ts and guidelines established for this miss ion ,

3, Subsystem Descr ipt ion and Per fo rmance

a. Reactor /Shie ld Assembly

The heat source cons is t s of the re ference ZrH reac tor surrounded by a 477

shield, A drawing of the r eac to r and shield is shown in Figure V-18. The reac tor


T A B L E V-9

H I G H - P O W E R LUNAR P O W E R P L A N T C H A R A C T E R I S T I C S (Sheet 1 of 2)

G r o s s p o w e r output , kwe 42.9

L o s s to c o n v e r s i o n and t r a n s m i s s i o n , kwe 7.4

Net power to s h e l t e r , kwe 35.5

T h e r m a l p o w e r , kwt:

R e a c t o r

C o n v e r t e r

P u m p c o n v e r t e r

( P r i m a r y loop

( H e a t - r e j e c t i o n loop

R a d i a t o r

P r i m a r y - l o o p l o s s

T e m p e r a t u r e , ° F :

R e a c t o r



R a d i a t o r


S y s t e m 3.78

C o n v e r t e r 4.67

C o n v e r t e r C a r n o t 35.0

V o l t a g e s , v o l t s :

S h e l t e r h i g h - v o l t a g e bus 4160

C o n v e r t e r :

T u b u l a r m o d u l e 14.0

C o n v e r t e r m o d u l e 56.0

In le t

949

1230

390

384

Out le t

1251

930

690

684

962.4

919

38.4

25.6)

12.8)

914.4

5.0

A v e r a g e

1100

1080

540

5 34

A I - A E C - M E M O - 1 2 7 1 7

162

TABLE V-9

HIGH-POWER LUNAR POWERPLANT CHARACTERISTICS (Sheet 2 of 2)

F lowra te , l b / s e c :


Heat - re jec t ion loop 13.7

P r e s s u r e - d r o p , psi


Heat - re jec t ion loop 1,5

Weights, lb

Reactor 1,422

Conver ter 1,928

R a d i a t o r / s t r u c t u r e 4,600

Pump s 530

Expansion compensa tors 310

Piping 900

Inst rumentat ion and control equipment 300

Power conditioning 1,600

Radiation shield 14,000

Reactor and power-conversion sys tem support s t ruc ture 630

Thermal shield 835

Direct cu r r en t t r ansmis s ion cable 300

Alternat ing cu r ren t t r ansmis s ion cable 320

Total sys tem weight 27,675

Allowable payload 28,775

Design marg in 1,100


i s the s a m e a s tha t d e s c r i b e d in Sec t ion IV-A wi th the excep t ion tha t i t i s o p e r

a t ed in an i n v e r t e d pos i t i on . The c o n t r o l - d r u m d r i v e - s h a f t s p a s s downward

t h r o u g h the l o w e r end of the sh i e ld in to a r i g h t - a n g l e g e a r and then to the d r i v e -

m o t o r s . The l a t t e r a r e l o c a t e d n e a r the l ower p e r i p h e r y of the r a d i a t o r to p r o

vide a c c e s s for p o s s i b l e m a i n t e n a n c e when the r e a c t o r i s shut down.

The r e a c t o r sh i e ld i s c o m p o s e d of an i n n e r P b g a m m a s h i e l d s u r r o u n d e d by

a canned LiH n e u t r o n sh i e ld . A l a y e r of i n s u l a t i o n s e p a r a t e s the two s h i e l d s to

avoid o v e r h e a t i n g the LiH, The n e u t r o n s h i e ld i s cooled b y r a d i a t i o n to the inne r

s u r f a c e of the power s y s t e m r a d i a t o r . The sh i e ld enve lope i s 68 in . in d i a m by

68.5 in . h igh , and the to ta l sh i e ld we igh t i s a p p r o x i m a t e l y 14,000 lb . The sh ie ld

t h i c k n e s s e s shown on F i g u r e V - 1 8 a r e s i z e d to l i m i t the annua l r a d i a t i o n dose to

70 r e m / y e a r (8 m r e m / h r ) at the l u n a r s h e l t e r , wh ich i s l o c a t e d a t a d i s t a n c e of

a p p r o x i m a t e l y 1/2 m i . In add i t i on , the i n t e g r a t e d d o s e to the p r e - o p e r a t i o n a l 12

c o n t r o l e q u i p m e n t l o c a t e d above the r e a c t o r w a s l i m i t e d to 5 x 10 nvt in 6 m o

of o p e r a t i o n a t 10% p o w e r . No sh i e ld i s p l a c e d a r o u n d the p o w e r - c o n v e r s i o n

e q u i p m e n t , and the d o s e r a t e f r o m the a c t i v a t e d NaK in the e x p o s e d p a r t of the

p r i m a r y loop i s i n c l u d e d a s a s o u r c e in the c a l c u l a t i o n of e x p e c t e d d o s e r a t e s .

Tab le V-10 p r e s e n t s the d o s e r a t e c o n t r i b u t i o n s f r o m n e u t r o n s and g a m m a s at a

s e p a r a t i o n d i s t a n c e of 0.5 m i .

T A B L E V-10

D O S E R A T E A T 0.5 m i F R O M LUNAR BASE R E A C T O R

Neutrons

Gamma rays (p r imary and secondary)

24 Na in power-convers ion sys tem

Total

Dosera te ( m r e m / h r )

1.57

3.66

2.32

7.55

A I - A E C - M E M O - 1 2 7 1 7

164

b , PCS Ar rangement

The TE PCS including the conve r t e r s , pumps, and pr imary- loop expansion

compensa to r s a r e located above the r eac to r / sh i e ld as shown in F igures V-16

and -18 , The a r r angemen t is essent ia l ly the same as that in the gallery of the

Saturn-V OWS (see F igure V-7), Pump power r equ i remen t s , conver ter s ize ,

and expansion compensator size a r e the same for both plants . Detailed de sc r ip

t ions of each of the PCS components a r e given in other sections of this repor t .

For the 35.5-kwe plant the r eac to r AT has been increased, result ing in

nea r ly the same pump power r equ i r emen t s . The conver ter packages will be

l a r g e r , however, requir ing a somewhat expanded a r rangement of the power-

convers ion equipment shown previously .

c . Rad ia to r /S t ruc tu re

The r a d i a t o r / s t r u c t u r e is s imi la r to that on the Saturn-V OWS plant (see

F igure V-9). The radia tor consis ts of a 6061 aluminum fin and a r m o r which

is diffusion-bonded to a s t a i n l e s s - s t e e l NaK tube. The individual tube-fin pieces

a r e a s sembled into panels by welding the NaK tubes to headers at either end.

The panels a r e then assembled to the s t ruc ture through supports to provide dif

ferent ia l t h e r m a l expansion between the s t ruc ture and the tube-fin panels. The

NaK heade r s a r e connected to the supply and re turn l ines .

The radia tor s t ruc tu re is of the semimonocoque type, consisting of c o r r u

gated s t i f feners , skin, and f r ames . Titanium is used as the s t ruc tura l m a t e r i a l

because during power - sy s t em operat ion, the maximum tenaperature is between

650 and 700°F,

The rad ia tor s t ruc tu re is at tached to a load ring located at the base of the

rad ia to r . The r e a c t o r / s h i e l d is supported off this same load ring through spar

beams attached to the outside of the shield s t ruc tu re .

4. Operat ional Mode

The methods and p rocedures proposed for deployment of the powerplant on

the lunar surface , p re -opera t iona l s torage, s tar tup, and operation, a re the

same as those identified in the previous study of reac tor power sys tems for (3 5) this mis s ion . ' Briefly, the planned operational mode is as follows:


1) The power sys tem will be launched using the Sa tu rn-V/LLV booster

and landing vehicle, and landed on the lunar surface at a p r e d e t e r

mined position located approximately 1/2 to 1 mi from the position

of the lunar she l t e r s .

2) The reac tor will be s tar ted up by a command signal from Ear th , and

the reac tor power level r a i sed to approximately 5 to 10% of its design

full-power operating point. The the rmal shields will then be opened

to expose approximately 10% of the rad ia to r a r ea (again by control

from Ear th) . Under these conditions severa l hundred watts of e lec

t r i ca l power will be generated, sufficient to power the communicat ions

and control equipment at the top of the powerplant. Its operabil i ty can

thus be confirmed on Ear th before the as t ronauts a r e committed to the

lunar base . In addition the powerplant can be kept w a r m through the

lunar the rmal cycles thus avoiding freezing of the l iquid-metal loops.

3) The as t ronauts will land somet ime during the two-week lunar day at

which t ime the reac tor powerplant will be shut down by remote com

mand. The as t ronauts then will deploy the power - t r ansmis s ion cables

between the lunar shelter and the powerplant, and set up the operat ional

control and power-conditioning equipment, on the lunar surface within

about 100 ft of the powerplant.

4) After the as t ronauts have re turned to the lunar she l t e r s , the heat

shields will be lowered and the sys tem s tar ted up and brought to the

des i red operating power level . (The operat ional control sys t em will

be of the type discussed under the re ference power sys tem in this

repor t . )

5) In the event of sys tem shutdown (planned or unplanned), the heat

shields will be ra i sed back into position to avoid eventual freezing

of the l iquid-metal loops. Maintenance and repa i r will be possible

on the con t ro l -d rum actuator m o t o r s , located at the outer surface

of the powerplant, and on the e lec t r i ca l control and power-conditioning

equipment located on the lunar sur face .


6) At the end of the miss ion the powerplant will be shut down using the

normal control sys tem and abandoned in position. If des i red , the

power level can be reduced to 5 to 10% of i ts des ign-power level and

left on the moon in this condition, ready for subsequent r e s t a r t and

operation.

Nuclear safety requ i rements for this miss ion can be me t quite easi ly since

the power sys tem would not be s ta r ted up until it has been safely landed on the

moon.

5. Comparison With Previous Design

The cu r ren t lunar base powerplant design r e p r e s e n t s a considerable im

provement over that repor ted in Reference 3. Table V-11 is a compar ison of

the more significant features of the cu r r en t and previous des igns . The new

TABLE V-11 DESIGN COMPARISON

Elec t r ica l power del ivered to Degradation allowance, % Reactor power, kwt Reactor ou t l e t - t empera tu re , Converter clad average tempe

System efficiency, % Radiator a rea , ft^ Number of tubular modules Total number of loops Weight, lb:

Power-conversion sys tem . Nuclear shield Support s t ruc ture Thermal shield Transmiss ion cable

Total

Allowable payload

Design margin

she l te r .

° F

sra ture .

kwe

"F: hot cold

ind r eac to r

Cur ren t

22.9 10

613.4 1247 1125 556 3.74 1500 96

5

7,525 14,000

525 500 550

23,100

29,475

6,375

Previous

20.4 14.0 541

1229 1100 500 3.77 1500 256

17

11,195 13,900

525 500 500

26,620

29,475

2,855


s y s t e m h a s a h i g h e r n e t power p r i m a r i l y b e c a u s e of i m p r o v e m e n t s in the T E

c o n v e r t e r and s y s t e m d e s i g n . The r e a c t o r t h e r m a l power i s h i g h e r for the

new s y s t e m b e c a u s e of the h i g h e r e l e c t r i c a l p o w e r output . The s y s t e m effi

c i e n c i e s a r e n e a r l y the s a m e .

The p r e v i o u s d e s i g n u s e d 256 c o n v e r t e r t u b u l a r m o d u l e s wh ich -were s m a l l e r

than the c u r r e n t r e f e r e n c e t u b u l a r m o d u l e d e s i g n . Th i s c h a n g e in c o n v e r t e r

de s ign not only d r a s t i c a l l y r e d u c e d the n u m b e r of t u b u l a r m o d u l e s r e q u i r e d , but

a l s o r e d u c e d c o n v e r t e r we igh t by o v e r 2400 lb . Th i s a c c o u n t s for m o s t of the

weigh t d i f f e r e n c e s b e t w e e n the c u r r e n t and p r e v i o u s d e s i g n s . A n o t h e r 1000- lb

r e d u c t i o n w a s a c h i e v e d by u s i n g i m p r o v e d r a d i a t o r des ign , u s i n g f ewer p a r a l l e l

l o o p s , and e l i m i n a t i n g the i n t e r m e d i a t e loops e n t i r e l y . Th i s g r e a t l y s i m p l i f i e s

the s y s t e m d e s i g n and should i n c r e a s e the r e l i a b i l i t y . The c u r r e n t d e s i g n h a s

twice the we igh t d e s i g n m a r g i n a s the p r e v i o u s d e s i g n .

C. M O R L P O W E R P L A N T

1. M i s s i o n R e q u i r e m e n t s

The M O R L i s a p r e l i m i n a r y d e s i g n for an advanced s p a c e s t a t i on tha t h a s

been s tud i ed e x t e n s i v e l y o v e r the p a s t s e v e r a l y e a r s by the M c D o n n e l l - D o u g l a s

C o r p . for NASA. A jo in t NASA/AEC s tudy to d e t e r m i n e the d e s i g n r e q u i r e m e n t s

and c h a r a c t e r i s t i c s of s e v e r a l t y p e s of r e a c t o r power s y s t e m s for the M O R L

w a s conduc t ed in 1966. ' One of the power s y s t e m s s tud i ed w a s a 2 2 . 5 - k w e

r e a c t o r — T E s y s t e m b a s e d on the P b T e t u b u l a r co rapac t c o n v e r t e r . Al though

the M O R L d e s i g n h a s now been s u p e r s e d e d by the OWS s e r i e s , upda t ing of the

r e a c t o r — T E po-wer s y s t e m d e s i g n for the s a m e i n t e g r a t i o n c o n s t r a i n t s u s e d

p r e v i o u s l y i s of i n t e r e s t .

The m a j o r p o w e r s y s t e m r e q u i r e m e n t s and i n t e g r a t i o n c o n s t r a i n t s e s t a b

l i s h e d for the M O R L m i s s i o n a r e shown in Tab le V - 1 2 .

2. S y s t e m D e s c r i p t i o n and C o m p a r i s o n wi th P r e v i o u s D e s i g n

The g e n e r a l con f igu ra t i on and p e r f o r m a n c e c h a r a c t e r i s t i c s of the u p d a t e d

M O R L r e a c t o r — TE s y s t e m a r e the s a m e a s t h o s e of the r e f e r e n c e 25 -kwe s y s

t e m d e s c r i b e d in Sec t ion III of t h i s r e p o r t . The p o w e r p l a n t l ayout and d i m e n s i o n s

A I - A E C - M E M O - 1 2 7 1 7

168

TABLE V-12

KEY MANNED ORBITING RESEARCH LABORATORY MISSION AND REACTOR POWER SYSTEM REQUIREMENTS

Elec t r i ca l power range , kwe 10 to 30

Lifetime objective, yr 5

Allowable radiat ion dosera te from r e a c t o r , r e m / y r 20

Reactor — Manned Orbiting Resea rch

Labora to ry separat ion dis tance, ft 125

Doseplane d iame te r , ft 80

Shield type Shadow

Available payload for power sys tem, lb

Initial launch 41,000

Replacement 18,110

shown on F igure V-19 a r e set p r imar i l y by the 17° shield half-angle which r e

sults from the doseplane d iameter and separat ion distance requ i rement s . A

shadoAV shield is used, consis tent with the previous requ i rements for this appli

cation. This po-wer-conversion equipment is located in the shield gal lery.

Table V-13 i s a brief summary of the cu r ren t MORL system cha rac te r i s t i c s (2) and a compar i son with the previously published sys tem design. That had an

e lec t r ica l power output of 22.5 kwe and the cu r ren t design power level is 21.9 kwe.

These a re net conditioned powers based on a conditioning efficiency of 0.87.

The r e a c t o r t he rma l powers and efficiencies a r e approximately the same

for the two s y s t e m s . As was the case with the lunar base sys tem, the cur ren t

design u se s the improved conver te r module design which reduces the number of

modules r equ i r ed by 70%. The cu r ren t design does not use an intermediate loop,

thereby el iminating heat exchangers , in te rmedia te loop pumps, compensa tors ,

and piping.

The previous design used 12 active and 2 standby redundant loops with NaK

valves . The cu r r en t design has four active HRL's and no standby redundant loops

Any sy s t em degradat ion which might occur is compensated for by adjusting r e

actor ou t l e t - t empe ra tu r e , which has been reduced 54°F in the cu r ren t design.


TABLE V-13 MOBILE ORBITING RESEARCH LABORATORY

SYSTEM CHARACTERISTICS

Regulated e lec t r ica l power, kwe

Reactor thermal power, kwt

Reactor ou t le t - tempera ture , °F

Converter clad average t e m p e r a t u r e .

" F : hot

cold

System efficiency, % 9

Radiator a rea , ft Number of tubular modules

Number of loops in s e r i e s

Number of hea t - re jec t ion loops in para l le l

Total number of hydraul ic loops

Weights, lb:

Reactor

P r i m a r y loop

Heat exchangers

Converters

Expansion compensators

Pumps

Piping

Support s t ruc ture

Radiator / s t ruc ture / piping

Subtotal

Radiation shield

Total

Current

21.9

582

1,246

1,125

570

3.77

1,400

96

2

4

5

1,422

515

-

1,135

285

440

100

113

2,990

7,000

12,300

19 300

Previous

22.5

622

1,300

1,150

550

3.62

1,891

336

3

14

22

755

503

147

5,082

693

280

200

-

3,573

11,233

9,315

20,548


The cur ren t sys tem has a total of five hydraul ic loops, i, e. one p r i raa ry and

four HRL's , whereas the previous design had 22 hydraulic loops, i, e. one p r i

m a r y , seven in te rmedia te , and 14 HRL's 2

The radia tor a r ea has been reduced by 49 1 ft , which reduces the overal l

package height approximately 7 ft.

The weights shown in Table V-13 a r e a r r anged to provide a consis tent com

par ison and do not include integrat ion penalt ies in e i ther ca se .

The cu r ren t design uses the 477'-shieldable 295-element r eac to r , and the

previous design used a 349-element r eac to r concept with a Be ref lector de

signed for use with a shadow-shield. The conver te r weight is reduced near ly

4000 lb by use of the cu r r en t module design. Other weight differences except

for the nuclear shield a r e a r esu l t of the different hydraul ic a r r angemen t s .

The cur ren t shield design is significantly heavier at 12,300 lb than the p r e

vious weight of 9,315 lb . This difference is caused by the use of a l a rge r gal lery

to accommodate the pumps, conver t e r s , and expansion compensa to r s . The p r e

vious design used compact heat exchangers to reduce gal lery size and shield

weight. However, the cu r r en t study has shown that it is n e c e s s a r y to use l a r g e r

heat exchangers with fewer tubes to improve re l iabi l i ty . Heat exchangers of

this type resu l t in ga l l e r ies a s la rge as those requ i red for the two-loop design

and resu l t in shield weights near ly as heavy as the c u r r e n t design. Without a

significant weight advantage there is no reason to use an in te rmedia te loop,

especial ly since the additional components in the loop reduce overal l sys tem

rel iabi l i ty .

Thus the major improvements in the updated powerplant for the MORL are

considered to be the simplification in the sys tem design which should enhance

the rel iabi l i ty , a 26% reduction in radia tor a r e a , a 50°F reduction in r eac to r

out le t4:emperature , and a 5% reduction in shielded sys tem weight.


• REFERENCES

1. AI-AEC-MEMO-12715, "Reference ZrH Reactor , " December 1, 1968

2. DAC-57950, "Final Report on the Design Requi rements for Reactor Power Systems for Manned Ear th Orbital Applications, " January 1967, Douglas Miss i les and Space Division

3. LMSC-677879, Vol. II, "Design Requi rements for Reactor Power Systems for Lunar Exploration, " September 1967, Lockheed Miss i les and Space Company

4. DAC-56550, "Ear ly Orbital Space Station, " Douglas Miss i le and Space Systems Division, November 1967

5. NAA-SR-12374, "Reactor Power Plants for Lunar Base Applications, " (CRD), June 30, 1967, Atomics Internat ional

6. J . D. Gylfe, NAA-SR-MEMO-12373, Vol. I, "Reactor /Shie ld Subsystems for Manned Orbiting Resea rch Labora tor ies (MORL), " June 15, 1967

7. D. K. Nelson and R. L. Det terman, "Evaluation of SNAP Reactor Disposal Techniques, " Pape r presented at the Amer ican Nuclear Society Annual Winter Meeting, Chicago, 111., November 6-9, 1967

8. SID 65-1552, "Propuls ion Systems for Enhancing SNAP Reactor Safety {Contract A T ( l l - l ) - G E N - 8 ) (U), December 21 , 1965

9. R. S, Hart and W. T. Harper , E d s . , "Final SNAPSHOT Safeguards Report , NAA-SR-10022, Rev. (CRD), March 20, 1965

10. H. C. Haller and S. Lieblein, NASA LERC, "Analytical Comparison of Rankine Cycle Space Radia tors Constructed of Central Double and Block-Vapor-Chamber Fin-Tube G e o m e t r i e s , " NASA TN D-4411, Feb rua ry 1968

11. J . Mil ler , Pe r sona l Communication, NASA, MSFC


GLOSSARY

A A P

a c

AI

ANS

B O L

GSM

dc

E B R

E C U

E M

E O L

EOSS

EVA

H N P F

H R L

ID

IHX

kwe

kwt

L L V

MDA

M O L

M O R L

M R P

Apol lo A p p l i c a t i o n s P r o g r a m

a l t e r n a t i n g c u r r e n t

A t o m i c s I n t e r n a t i o n a l

A e r o s p a c e N u c l e a r Safety

B e ginning -of- Life

C o m m a n d and S e r v i c e Module

d i r e c t c u r r e n t

E x p e r i m e n t a l B r e e d e r R e a c t o r

E x p a n s i o n C o m p e n s a t o r Unit

e l e c t r o m a g n e t i c

E n d - o f - L i f e

E a r l y O r b i t a l Space Sta t ion

E x t r a v e h i c u l a r a c t i v i t i e s

H a l l a m N u c l e a r P o w e r F a c i l i t y

H e a t - r e j e c t i o n loop

i n s i d e d i a m e t e r

I n t e r m e d i a t e h e a t e x c h a n g e r

k i l o w a t t s e l e c t r i c

k i l o w a t t s t h e r m a l

L u n a r Landing Veh ic l e

Mul t ip l e Docking A d a p t o r

M a n n e d O r b i t a l L a b o r a t o r y

M a n n e d O r b i t i n g R e s e a r c h L a b o r a t o :

M e r c u r y - R a n k i n e P r o g r a m

ry

A I - A E C - M E M O - 1 2 7 1 7 175

MSEC

n. m i

NPS

OD

OWS

P C S

P V T

P W R

SRE

S I B / S M

S8DR

S8ER

TE

T E M

WANE

M a r s h a l l Space F l i gh t C e n t e r

n a u t i c a l m i l e s

n u c l e a r power s y s t e m

o u t s i d e d i a m e t e r

O r b i t a l W o r k s h o p

p o w e r - c o n v e r s i o n s y s t e m

p r e s s u r e / v o l u m e / t e m p e r a t u r e

P r e s s u r i z e d W a t e r R e a c t o r

Sod ium R e a c t o r E x p e r i m e n t

S a t u r n - I B S e r v i c e Module

SNAP 8 D e v e l o p m e n t a l R e a c t o r

SNAP 8 E x p e r i m e n t a l R e a c t o r

t h e r m o e l e c t r i c

t h e r m o e l e c t r i c m o d u l e

W e s t i n g h o u s e A s t r o n u c l e a r L a b o r a t o r i e s

A I - A E C - M E M O - 1 2 7 1 7 176

reference zirconium hydride reactor thermoelectric …

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