eurotrans wp1.5 safety meeting lyon, october 10 - 11 th 2006 design of the efit-mgo/pb core

EUROTRANSWP1.5 Safety Meeting

Lyon, October 10 - 11th 2006

Design of the EFIT-MgO/Pb Coreand Fuel Assemblies

Carlo Artioli, Massimo Sarotto

Italian Agency for new Technologies, Energy and Environment,Advanced Physics Technology Division

Via Martiri di Monte Sole 4, 40129 Bologna, Italy

http://www.enea.it/prima.html

Lyon, 10 – 11th October 2006 , EUROTRANS – WP1.5 Specialist Meeting C. Artioli, M. Sarotto

Objectives

Transmutation of MAs

ADS 300-400 MWth

High PD to fast MAs incineration

Main Hypothesis

Lead coolant: T Inlet 400 °C – T Outlet 480°C

U-free CERCER Fuel: 50-65% MgO VF + 50-35% (Pu,MAO2)

Reactor Geometry, MgO VF & Fuel Enrichment E:

to satisfy: keff (t) ≤ 0,97 during the cycle

2

E = FIS / ( FERT + FIS )

FIS: PuO2 - FERT : MAO2 (Am, Cm, Np)



3

Pu & MA Isotopic Compositions

MOX spent Fuel after 30 years’ cooling( CEA )

Pu [ w % ]

Pu238 3,737

Pu239 46,446

Pu240 34,121

Pu241 3,845

Pu242 11,850

Pu244 0,001

MA [ w % ]

Np237 3,884

Am241 75,510

Am242 3,27E-06

Am242m 0,254

Am243 16,054

Cm242 2,3E-20

Cm243 0,066

Cm244 3,001

Cm245 1,139

Cm246 0,089

Cm247 0,002

Cm248 1,01E-04

Pu Vector

Pu238

Pu239

Pu240

Pu241

Pu242

Pu244

MA Vector91,8% Am4,3% CmNp237

Am241

Am242

Am242m

Am243

Cm242

Cm243

Cm244

Cm245

Cm246

Cm247

Cm248

Pu Vector



4

FA Design Requirements

Hex FAs with wrapper

Pellet diameter as low as possible (high PD)

Linear power f(MgO VF & conductivity) 200 [W cm-1]

Max fuel operating Tmaxfuel = 1380 °C

Max cladding (SS, SA213T91 coated) Tmaxclad = 550 °C

Pb coolant velocity v 1 [m s-1]

Residence time = 3 years: Pb corrosion is the most

restricting condition (in comparison to BUmax, DPAmax)


A

B

C


4a

After the first 3 years:

Before refuelling the mean residence time is 2 years

After refuelling the mean residence time is 1 years

Years A B C

0 0 0 0

1 1/0 1 1

2 1 2/0 2

3 2 1 3/0

4 3/0 2 1

5 1 3/0 2

6 2 1 3/0

7 3/0 2 1

8 1 3/0 2

9 2 1 3/0

Refuelling

We consider the keff beh., the core performances …

between [1,2] yearsand the BU results (w/o refuell.) at the 3rd year

Fuel cycle hyphotesis

For Pb corrosion (strongest requirement):

3 years as max residence time

Refuelling of 1/3 core each year



5

Core Design Requirements (1/3)

Pth 300-400 MWth but the size optimization criteria should be:

Min cost per kg of fissioned MAs Min cost per MW deployed

cost / MWdeployed = f(core size, accelerator size)

Without sufficient information and data about the unitary costs, we assume the following semplified criterion:

The largest size core acceptable within the currentspallation module design able to evacuate 11-12 MW.The corresponding proton accelerator is: 800 MeV,15-20 mA (to be verified)

decreases by increasing Pth increases by increasing the power(also for the loose of φ*)

Spallation module (19 hex FAs) fixes FA dimension (double apothem = 191 mm)



6

Flattening Technique (2 radial fuel zones)


Fu

el_I

nn

er

Fu

el_O

uter

R1 R2

Tar

get

Rt

Different MgO matrix contents(fabrication more expensivefor supplementary line cleaning)

Different Pin diameters(less efficient because in the outer zone the max coolant outlet T is reached before reaching the max allowed linear power & PD)

StructuralC o o l a n tF u e l

Pu

+M

A

Mat

rix

StructuralC o o l a n tF u e l

Pu

+M

A

Mat

rix

MgO VF OUT = 50%

MgO VF IN = [60-65]%

BREST Style



7

7,2

7,52

8,72

13,63 mm

4,91

168+1 Fuel Pins(7+1 pin rows)

(750 °C)

(480 °C)

(440 °C)

178

186

191 mm

Fuel

Void

SS

Pb

0,60,16

VF(Fuel Pellet) = 21,65%

Filling = 0,9167

Fuel Inner60-65% MgO

Fuel Outer50% MgO

Inner & Outer FA Design



8


High Burn up of MAs: f (fuel E); Low cost: f (PD)

Limited keff (and I) variation during the cycle: f (fuel E)

To obtain keff (t) const fuel E = 50%In 3 years (AveBU = 84,75 MWd / kg (HM) )

-35,1 kg (MA) / TWh

-5,9 kg (Pu) / TWh

Pu & MAs mass variationPu / Pu (BOC) -2,4%

MA / MA (BOC) -14,3%1500

1550

1600

1650

1700

1750

1800

0 1 2 3

[ years ]

[ kg

]

Tot MA

Tot Pu



9

Transmutation Performances

Avoid Pu burning (expensive in sub-critical reactors)

Avoid Pu Build Up (for public acceptability)

Since we always burn 42 kg (HM) per TWh the approach could be:

-42 kg (MA) / TWh

0 kg (Pu) / TWh

f (fuel E = 45,7%)

Does not depend on Pth, DP …

The core design for this goal has to be compatible with:

• the keff (t) variations (f (fuel E) ) during the cycle

• the accelerator performances (800 MeV; 15–20 mA)



10

Calculation Tools & RZ Geometrical model

R [cm]

BoxDummy

Box_Ax_In

Z [cm]In

tern

al L

ead

Target

Foot_Assembly

Top_Assembly

Plenum

Pb_Ext

Bea

m li

ne

Fu

el_I

nn

er

Fu

el_O

uter

Pb_Ext

15AH45

R

R1 R2

Rt

- ERANOS 2.0 – JEFF2.2 library 1) Cell calculations by the ECCO code with 1968 energy groups (heterogeneous geometry description for the Fuel Cells) 2) Spatial calculations by the BISTRO RZ transport code (51 e. gr., RZ geometry with “equivalent” radii to hex geometry)

- Fixed:

1) fuel E (= 45,7%)

2) Spallat. Target Rt = 43,7 cm ( 19 FAs)

3) AH = 90 cm

4) MgO VF in fuel Outer (50%)

- Varying MgO VF in fuel IN (60, 62.5, 65 %):

R = f(E) to obtain keff (t) ≤ 0.97

R1 / R2 to exploit PDcore,max1,2

(equivalent with hexagonal rings)



11

Keff (t) during the cycle

0,958

0,96

0,962

0,964

0,966

0,968

0,97

0 0,5 1 1,5 2

Years

Kef

f

Pth = 365 MW (60% MgO IN)

Pth = 395 MW (62,5% MgO IN)

Pth = 430 MW (65% MgO IN)

Keff(t) in 2 years with fuel E = 45,7%

keff 550-600 pcm / year

( no matter the core size)


13

Max allowable PDs (via Linear Power)

Different MgO VF Different fuel pellet conductivity Different LP

3 4 5

0,97keff 550-600 pcm / year

t [years]

keff

1 1

2 2 average residence t [years]

Refuelling of 1/3 core

0,964

Fuel Cycle (keff [2nd year] ≤ 0,97)



14

Core performances (1/3) Worstcondition(lowest keff, highest I)

(keff 0,964) (keff 0,97)



15

395 MW Hex Layout (drawing by ANSALDO)


16

Core performances (2/3)

ffrad = 1,45

ffax = 1,15

ffrad = 1,29

ffax = 1,14

keff = 0,964 0,97


17

Core performances(3/3)

The low keff excursion

does not require

significative proton current

variations:- 16 mA (1 year)- 13 mA (2 years)

Start Up1 year (BOC)2 years (EOC)

SpallationModule Fuel


18

BU performances (395 MW, EPu = 45,7%)

Pu / Pu (BOC) -0,25%

MA / MA (BOC) -

12,95%

2600

2700

2800

2900

3000

3100

3200

3300

0 1 2 3

Years

[ k

g ]

TOT PuTOT MA


19

Behaviour of MA isotopes

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3

years

[ %

] Tot MA

Am241

Am243

Cm242

Cm244


20

Behaviour of Pu isotopes

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3Years

[ %

]

Tot PuPu238Pu239Pu242


21

Core and Burn Up performances

Reactor Perform. 1 year 2 years

Power [MWth] 395

N. Fas 48 + 174

R [ cm] 43,9+38,6+74=156,5

Core Vol [cm3] 6,38E+06

E (Pu / (Pu+MA)) 45,7% (BOC)

Keff 0,964 0,969

Source Imp 0,59 0,61

APDHom [W cm-3] 61 61

Tot ff In 1,47 1,41

Tot ff Out 1,67 1,63

I [mA] (600 MeV) 25,1 20,3

I [mA] (800 MeV) 16,3 13,2

PDMaxInnHM [W cm-3] 1306

PDMaxOutHM [W cm-3] 884

BU perform.

Pu / Pu (BOC) -0,25%

kg (MA) / TWh

3 years

ABUHM [MWd kg-1] 72,16

MA / MA (BOC) -13,0%

kg (MA)

kg (Pu)

-40,6

-7

MA (BOC) [kg] 3256

kg (Pu) / TWh -0,7

Pu (BOC) [kg] 2738

-422


22

Concluding Remarks

42-0 approach for MAs transmutation (without Pu burning and production)

is a viable strategy

The T/H analysis with RELAP code (P. Meloni) shows that we exceed

the safety limits on cladding temperature: (ffrad too high in the Outer part)

The problem can be solved by: 1) Optimising the 2 zones subdivision

2) Adopting 3 radial zones

INNER ZONE (Fax = 1.143) OUTER ZONE (Fax =1.133)

Max Temperature (°C)

Hot FA 1/48 Fr = 1.29

Average FA 47/48

Hot FA 1/174

Fr = 1.45

Average FA 173/174

Central Fuel (*) 1319 1094 1318 1006

Surface Fuel (*) 905 790 863 719

Internal clad (**) 547 514 559 510

External clad (**) 535 504 549 503

Lead (**) 503 480 515 480* At max linear power ** At max core elevation

The calculations will

be refined (JEFF3.1

MgO, Pb library (1968 g),

Hex reactor model,

Uncertainties on MAs

nuclear data…)

eurotrans wp1.5 safety meeting lyon, october 10 - 11 th 2006 design of the efit-mgo/pb core

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