hitachi nuclear energy shitachi · mfn 09-023 supplement 3 enclosure 1 nrc rai 6.2-140 s05 provide...

SHITACHIGE Hitachi Nuclear Energy

Richard E. KingstonVice President, ESBWR Licensing

PO Box 780 M/C A-65Wilmington, NC 28402-0780USA

T 910 819 6192F 910 362 6192rick [email protected]

MFN 09-023 Supplement 3 Docket No. 52-010

November 16, 2009

U.S. Nuclear Regulatory CommissionDocument Control DeskWashington, D.C. 20555-0001

Subject: Response to PortionInformation Letter No.Certification ApplicationNumber 6.2-140 S05

of NRC Request for Additional375 Related to ESBWR Design

- Engineered Safety Systems - RAI

The purpose of this letter is to submit the GE Hitachi Nuclear Energy (GEH)response to the U.S. Nuclear Regulatory Commission (NRC) Request forAdditional Information (RAI) sent by the Reference 1 NRC letter. GEH responseto RAI Number 6.2-140 S05 is addressed in Enclosure 1.

Enclosure 2 contains markups to DCD Tier 1 and Tier 2 Section 6.2 as noted in

the Enclosure 1 response.

If you have any questions or require additional information, please contact me.

Sincerely,

Richard E. KingstonVice President, ESBWR Licensing

MFN 09-023 Supplement 3 of 2

Reference:

1. MFN 09-624, Letter from U.S. Nuclear Regulatory Commission to JeraldG. Head, Request for Additional Information Letter No. 375 Related toESBWR Design Certification Application, October 1, 2009

Enclosures:

1. MFN 09-023 Supplement 3 - Response to Portion of NRC Request forAdditional Information Letter No. 375 Related to ESBWR DesignCertification Application - Engineered Safety Features - RAI Number 6.2-140 S05

2. MFN 09-023 Supplement 3 - Response to Portion of NRC Request forAdditional Information Letter No. 375 Related to ESBWR DesignCertification Application - Engineered Safety Features - RAI Number 6.2-140 S05 - Markups to ESBWR DCD Tier 1 and Tier 2 Section 6.2

cc: AE Cubbage USNRC (with enclosures)JG Head GEH (with enclosures)DH Hinds GEH (with enclosures)SC Moen GEH (w/o enclosures)eDRFsection 0000-0108-5168

Enclosure I

MFN 09-023 Supplement 3

Response to Portion of NRC Request for

Additional Information Letter No. 375

Related to ESBWR Design Certification Application

Engineered Safety Systems

RAI Number 6.2-140 S05

MFN 09-023 Supplement 3Enclosure 1

NRC RAI 6.2-140 S05

Provide updated RAI response, clarify implementation of PCC pool refill, and confirmvent fan discharge submergence and fan performance

In response to RAI 6.2-140, Supplement 4, GEH provided detailed results for 30-daycontainment analysis, which credited PCCS, PCCS pool refill, PARS, and six drywellgas recirculation (DGR) fans beyond three days. However, GEH later changed thedesign basis requiring operating only four of six DGR fans and provided selected resultsin ESBWR DCD Revision 6.

A. The selected plots provided in ESBWR DCD Revision 6 are not sufficient for the staffto perform confirmatory analysis and complete the review. GEH should update RAI 6.2-140 response to include the four fan case, which represents the new design basis.

B. GEH's response to RAI 6.2-140, Supplement 4, shows varying of the PCC pool refillrates to maximize the PCCS heat transfer. GEH should clarify how it will implement thecontrolled PCC pool refill rates during the operation of ESBWR.

C. ESBWR DCD Revision 6 states that "The vent fan discharge line is > 0.22 m (9 in)and < 0.25 m (10 in) below the top of the drain pan lip." Confirm that the DGR fandischarge line would stay submerged during the 30 day analysis.

D. ESBWR DCD Revision 6 Table 6.2-49 lists the minimum DGR fan performancerequirements. Confirm that the DGR fan performance used in the containment analysisis bounded by the values listed in Table 6.2-49.

E. ESBWR DCD Revision 6 Figure 6.2-14el shows curve of analytical pressure limit.

a. Explain the regulatory significance of this curve.

b. Explain how this curve would be used in ESBWR design.

c. Explain the relevance of this curve to ITAAC, if any.

F. Update ESBWR DCD appropriately to include responses to parts B through D.

GEH Response

A. The plots provided in GEH's response to RAI 6.2-140S04 have been updated basedon the analysis presented in ESBWR DCD Revision 6. These plots, 6.2-140 S05-C1-6and 6.2-140 S05-D1-26, are presented below using the same naming convention forfigure titles used in Supplement 4 of this RAI.

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B: In the TRACG analysis, the PCC pool level was not kept at the highest possiblelevel. Therefore, the containment pressure could be higher at times because of higherpool saturation temperature and lower PCC heat transfer. This trend is shown in theresponse to RAI 6.2-140S04.

In the response to Supplement 4 of this RAI, GEH presented a plot showing the PCCpool level with respect to time (Figure 6.2-140 S04-B1). The analysis currentlypresented in ESBWR DCD Revision 6 contains a PCC pool refill control scheme thatmaintains the level in the pool closer to the top of the PCC tubes (DCD Rev. 6 Figure6.2-14e10). Using the information from the TRACG calculation presented inSupplement 4 of RAI 6.2-140, a DW pressure adder of 25 kPa (3.6 psi) is applied to theDW Pressure curves reported in ESBWR DCD Rev. 6 to adjust the results consideringthe highest possible PCC pool level. The effect of this adder is shown in Figure 6.2-140S05-2 below.

C: An error was discovered in the ITAAC Table 2.15.4-2, Item 14, which describes thelocation of the PCCS vent fan discharge as an elevation below the drain pan lip. Theintent of this ITAAC is to define this elevation within a tolerance such that the ITAACcan be met in a way that ensures the submergence does not exceed what it is in theanalysis. Therefore, the acceptance criteria in this item, as well as the text in Tier 2,Section 6.2.2.2.2 will be changed to consistently read:

"The elevation of the discharge on the PCCS vent fan line is 24 cm (9.4 in)below the top of the drain pan lip with a tolerance of 1.4 cm (0. 6 in)."

The TRACG analysis presented in ESBWR DCD Rev. 6 for the post-72 hour scenariodoes not maintain a 10 inch submergence of the vent fan discharge lines. However, asensitivity study on the effect of the submergence was performed. The difference inPCC vent fan discharge elevation and GDCS pool level is seen to decrease over timeas shown in Figure 6.2-140 S05-C5 below. However, the GDCS pool level illustrated inFigure 6.2-140 S05-C5 also confirms that the vent fan discharge does not becomeuncovered. The fan outlet is set in TRACG to a constant elevation of 20.91 m(referenced to Vessel Zero.) From the figure, the GDCS pool level in Ring 7,corresponding to the 4 vent fan pool, appears to reach a final level of 20.92 m.However, due to the fact that the discharge line is very close to being uncovered, ananalytical DW pressure adder was developed as a safety margin.

Similar to the technique described in paragraph B above, an adder of 15 kPa (2.2 psi) isapplied to the TRACG DW pressure response values as reported in ESBWR DCD Rev.6. The basis for the additional pressure comes from a study conducted to gauge theeffect of submergence of the discharge outlet on DW pressure. Shown in Figure 6.2-140S05-1 below, the DW pressure is seen to increase with increased submergence.The vertical section around 14 inches of submergence occurs early in vent fanoperation and can be ignored. An adjustment factor is determined, consideringsubmergence and decay heat as primary contributors to DW pressure. The DWpressure at the end of the increased submergence test case was 281 kPa; that resultsin a difference from the base case at the same time of -12kPa. The submergenceeffect is then calculated as being 12 kPa divided by the difference in submergence of10.5 inches, or 1.14 kPa/inch submergence. The stated submergence should be heldat 10 inches, so multiplying the submergence effect value by 10 inches yields an adderto 11.4 kPa that is rounded up to 15 kPa. The effect of this adder plus the adder

2 of 37


described in paragraph B is shown in Figure 6.2-140S05-2 below. This figure will alsobe added to the DCD as indicated in the attached markups as Figure 6.2-14e13. Toreduce redundancy, Figures 6.2-14el and 6.2-14e2 will be modified by removing theAnalytical Pressure Limit Curve.

D.: To provide additional assurance that the fan performance is bounding, a sixth datapoint (at 1,570 CFM) will be added to DCD Tier 2, Table 6.2-49. The sixth data pointprovides enough data to cover the range of fan performance and bounds the TRACGdata points shown in Figure 6.2-140S05-D6 below. Please see attached markups.

E(a): The Analytical Pressure Limit curve shown in ESBWR DCD Rev. 6 Figure 6.2-14e13 represents a system performance acceptance criterion. This curve is included toaccommodate variations in IC/PCC pool levels, PCC vent fan discharge submergencevariation, PCC vent fan performance characteristics and variations, PCC heatexchanger efficiency, and TRACG modeling, for example those discussed in B and Cabove. This curve indicates system performance consistent with the GDC 38 criteria torapidly reduce pressure and maintain a reduced pressure.

E(b): The curve defines an acceptance criteria for the analysis; it indicates that thepressure is rapidly reduced and does not approach the design pressure after PCC ventfan have been activated. Furthermore, any subsequent analysis performed during thedetailed design phase must fall below this criterion.

E():" There is no ITAAC that applies to this curve as a test, analysis, or acceptancecriteria.

3 of 37


450

Design DW and WWV Pressure

400 +

350 -4

300 -

250 -

Wwl Pres-r (L-ve 31.Ring 7) P993107RPV Pr--ur (Leve 21, R, ng 1 ) P992101Desgn Presure200

150 -

100

0 24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 384 408 432 456 480 504 528 552 576 600 624 648 672 696 720Time (hr)

Figure 6.2-140 S05-Cl Main Steam Line Break, I DPV Failure (Bounding Case) - Containment Pressures (30days).

450

400-

350

300

250

200

150

100

50

74,0Time (hr)

6.0

Figure 6.2-140 S05-Cla Main Steam Line Break, I DPV Failure (Bounding Case)- Containment Pressures(72-76 hr).

4 of 37


m0 Tn. -

200

180

160 1

140

4i n

100

806

BDWGe~Te~~ Gf~ Terfp TV9~31O~S~pp PoeT Tenp fl§92~O7

60

40 1

20

00 24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 384 408 432 456 480 604 528 552 576 600 624 648 672 696 720

Time (hr)

Figure 6.2-140 S05-C2 Main Steam Line Break, I DPV Failure (Bounding Case) - ContainmentTemperatures (30 days).

200- I

180 - Bul, DW Gee TeeBWeT."A Gae Te-p TV9-3"-1

160Sep PoB Te UTL992907

160

140 -T--

12 TZ

4 100

&- =F

OU

604-:

40 t

20 -

I0 S i 1 I I Ii I IIi i i i i i ! ! ! I I I I 1 1 1 ! I

72.0 72.5 73.0 73.5 74.0Time (hr)

745 75.0 75.5 76.0

Figure 6.2-140 S05-C2a Main Steam Line Break, IDPV Failure (Bounding Case) - ContainmentTemperatures (72-76 hr).

5 of 37


80i

ý 1 1. 1 1 1 1 1 1. 1 1 1 1 1 1 1 1 1 1. 1 ý ý. I I I I ý I I I 1 1. 1. 1 ý ý I 1 1. ý I 1 1. ý 1. 1 1. 1 1 1. 1 1

70 -

60

504

-40 -

30

20

T o tat P o e TO TP O 00 001T".PCCS Power

10) +

C) I I . . . .

0 24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 384 408 432 456 480 604 528 552 576 600 624 648 672 696 720Time (hr)

Figure 6.2-140 S05-C3 Main Steam Line Break, I DPV Failure (Bounding Case) - PCCS Heat Removalversus Decay Heat (30 days).

T.a

80

70+ Th -o'TOýTPOOOOO

6"

50 t

Z40

30

I

W)

10

U -+ ] • I I I I I I I I

72 73 74Time (hr)

75 76

Figure 6.2-140 S05-C3a Main Steam Line Break, 1 DPV Failure (Bounding Case) - PCCS Heat Removalversus Decay Heat (72-76 hr).

6 of 37


300i I I .I I .I . .i . .i . , , i , . I, I l , , , I r , , i , , , , , i , , , , ! . . . . . . . . . . . . . . . . . . . .

250

2OO

150

100

50 ! I..> --......

GOICS 1rpa -Le 34.Rig 7) PA993407G4.20 A-r~pece (Leel 340R1n 8) PAg93408

- W Head (LevI 35, Rang 1) PA993501DW Annu52s (Level 30, Rng 6) PAg93006

4----

g

0 24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 384 408 432 456 480 504 528 552 576 600 624 648 672 696 720Time (hr)

Figure 6.2-140 S05-C4 Main Steam Line Break, I DPV Failure (Bounding Case) - Drywell and GDCSNoncondensable Gas Pressures (30 days).

300 ,,

250 -

200 4:

0.

0.

150

GOCS Airspce (Level 341Ring 7) R P0A3407GDCS AirSpace (Level 34'Rin 0) P0093408DW Head (Level 35. Ring 1) PA993501DW Anvviv (Level 30. Ring 6) Pl003006

[7---i

100 +

50 -

0

72.0i . . . i . . I . . . . I .

72.5 73.0 73.5 74 0Time (hr)

74,5 75.0 75.5 76.0

Figure 6.2-140 S05-C4a Main Steam Line Break, 1 DPV Failure (Bounding Case) - Drywell and GDCSNoncondensable Gas Pressures (72-76 hr).

7 of 37


25

24

23 -1

.22

w421

--GDCS wte levl (L7 33,34. n99 8) )ZLV993408JVent F (r Outet i GDCS POol Ring 8

L

204

19-1

1848 96 144 192 240 288 336 384

Time (hr)432 480 528 576 624 672 720

Figure 6.2-140 S05-C5 Main Steam Line Break, 1 DPV Failure (Bounding Case) - GDCS Pool Water Level(30 days).

26

241- GDCS water I.eI (Le-e4 33.34. R4n 8) DZLuV99M4080

VerM FWen Ouet GDCS Pool RIr 8

23+

•22

w(21 H-

20+

19-4-

18 I - I I I i I I I I I I I ! i I I I I I I I I I I I I I I I72.0 725 73,0 73.5 74.0

Time (hr)74.5 75.0 75.5 76.0

Figure 6.2-140 S05-C5a Main Steam Line Break, 1 DPV Failure (Bounding Case) - GDCS Pool Water Level(72-76 hr).

8 of 37


34,0

335- PCC Po water Lel DZLV993604

Too of 9CC Tubes DOZV993704

3/4 PCC Tubes DZLV99380433.0 Middle DZLV993904

114 PCC Tubes DZLV994004- - -Bodof PCC Tubes DZLV994104

32.5

320

31.5

-6 31.0

30 5

300

29.5

290

285

0 24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 384 408 432 456 480 504 528 552 576 600 624 648 672 696 720Time (hr)

Figure 6.2-140 S05-C6 Main Steam Line Break, 1 DPV Failure (Bounding Case) - PCCS Water Level (30days).

340-

33 5PCC 909 Water LOevl DZLV993604Top of PCC Tubes DZLV9g3704

334 V4 PCC Tubes DZLV99380433.0dl D 5090ZV93904

114 PCC Tubos DZLV994004

Xilo 41 PCC Tubes DZLV9N4104

32.5

32.0

31.5

" 310

305

30,0

29.5

29 0

285

280 I , I72.0 725 73.0 735 740 745 750 75.5 760

Time (hr)

Figure 6.2-140 S05-C6a Main Steam line Break, IDPV Failure (Bounding Case) - PCCS Water Level (72-76hr).

9 of 37


30

27

24

21

118

S15

, 12

Mess Floe Rete to PCCS Pool MFL0390001

9

6

3

0

48 96 144 192 240 288 336 384Time (hr)

432 480 528 576 624 672 720

Figure 6.2-140 S05-DI Main Steam

30

27

Line Break, 1DPV Failure (Bounding Case), Mass Flow Rate to PCCSPool (30 Days).

L Mess FlW Rate to PCCS Pool MFLO39O01 I

24-1-

21

i18

S15-

12

3-

0 I I I I , . I 1 ! [ ! 1 ! 1 1 ! 1 i I i I I I iiI I I I I I i I I I 1 1 I

72.0 72.5 73.0 73,5 74 0Time (hr)

74.5 75.0 75.5 76 0

Figure 6.2-140 S05-DIa Main Steam Line Break, 1DPV Failure (Bounding Case), Mass Flow Rate to PCCSPool (72 hr-76 hr).

10 of 37


c•mo

1700

1600

1500

1400

1300

1200

1100

1000

900

u 800

700

> 600

500

400

300

200

100

0 48 96 144 192 240 288 336 384 432 480 528 576 624 672 720Time (hr)

Figure 6.2-140 S05-D2 Main Steam Line Break, 1DPV Failure (Bounding Case), PCCS RecirculationVolumetric flow Rate (30 Days).

990 -

890 -

790 -

690 -

590

Ir490

U..~390-

S290

- (4) VOL FIO RaW per FAN VFLOO8500001

100 -

90 -

-10 -

72.0 725 73.0 73.5 74.0Time (hr)

745 75.0 75.5 76 0

Figure 6.2-140 S05-D2a Main Steam Line Break, IDPV Failure (Bounding Case), PCCS RecirculationVolumetric flow Rate (72 hr-76 hr).

11 of 37


15

14

13

1.2

1.1

1.0

09

0.8

0.7

0,6

~0.5-0.4

80,3

0.2

0.1

0.0

-0.1

-0.2

-0.3

-0.4

-0.5

T- 2 M .. e ... A .... I

4) ýMes FOe Pete I- FAN MF

0 48 96 144 192 240 288 336 384 432Time (hr)

480 528 576 624 672 720

Figure 6.2-140 S05-D3 Main Steam Line Break, IDPV Failure (Bounding Case), PCCS Recirculation Massflow Rate (30 Days).

0.9

0.8

07

0.6

0.5

0.4

0.3

0.2

00

: -01

-02

-0.3

-04

-0.5

-0.6

-07

-0.8

-0.9

-10

1 2)Mes le , 'e e AN ML5)~2ý4)MeFeePeeeFN FLR00

72.0 72.5 73.0 735 74.0Time (hr)

74.5 75.0 75.5 76 0

Figure 6.2-140 S05-D33a Main Steam Line Break, 1DPV Failure (Bounding Case), PCCS Recirculation Massflow Rate (72-76 hr).

12 of 37


30 .

27

24

21

18

S15

LU

9

6

3

0 48 96 144 192 240 288 336 384 432 480 528Time (hr)

576 624 672 720

Figure 6.2-140 S05-D4 Main Steam Line Break, 1DPV Failure (Bounding Case), PCCS Condensate MassFlow Rate to GDCS (30 Days).

33

30

27

24

ý21-

18

U-15-

(2ý PCCS Moss FeW Pe"te LDratr) to OS Pool MFL046 0007t4t PCCS M-o Foe Rote roain) to GDCS Pool tFLOM84007TOTAL PCCS Mass Floe Rate ([a,,) to GDCS Pool

12

9

6

3

0

72.0 72.5 73.0 73.5 74.0Time (hr)

745 750 75.5 760

Figure 6.2-140 S05-D4a Main Steam Line Break, 1DPV Failure (Bounding Case), PCCS Condensate MassFlow Rate to GDCS (72 hr-76 hr).

13 of 37


3000

2900

2800

2700

2600

2500

2400

€"2200

2100

2000

S1900z

1800

1700

1600

1500

1400

1300

1200

1100

1000

0 48 96 144 192 240 288 336 384 432 480 528 576 624 672 720Time (hr)

Figure 6.2-140 S05-D5 Main Steam Line Break, IDPV Failure (Bounding Case), PCCS Vent Fan Head (30Days).

3000

2900I- (4) HEAD pe Fan, HEAD08500001

2800

2700

2600

S2500

2400

2300

2200

2100

2000 -720

. . .. I . . .I . I . . . I I72.5 73,0 735 74 0

Time (hr)74.5 750 75.5 76 0

Figure 6.2-140 S05-D5a Main Steam Line Break, IDPV Failure (Bounding Case), PCCS Vent Fan Head (72hr-76 hr).

14 of 37


2.0

18

1.5

1.3

1.0

zI.

08

05

0.3

0.0

* VOL now.~v£ FAN4 IP(4) VHOP08500001

Ce

I i i ( b I II I iI i I :I ) ! I I Ii I I I I [ I i ! ii I ! i ! ! !

-0.3

-0,5

-100 150 400 650 900 1150 1400Volumetric Flow CFM

1660 1900 2150 2400

Figure 6.2-140 S05-D6 Main Steam Line Break, 1DPV Failure (Bounding Case), PCCS VentFlow vs. Head (30 Days).

Fan, Volumetric

ax.

z:F

2.0

1.8

1.5

1.3

1.0

0.8

05

0.3

0.0

-0.3

-0.5

L VOL ow s FAN HE)D (4) RHOP08500001

C",

.100 150 400 650 900 1150 1400Volumetric Flow CFM

1650 1900 2150 2400

Figure 6.2-140 S05-D6a Main Steam Line Break, IDPV Failure (Bounding Case), PCCS Vent Fan,Volumetric Flow vs. Head (72 hr-76 hr).

15 of 37


20

18

16

14

S12

10

8

6

V[ u ror F-ow 1 MIF0100V03vacuum Brea1er Fow 2 0FLO420002

4

2

00 48 96 144 192 240 288 336 384 432 480 528 576 624 672

Time (hr)720

Figure 6.2-140 S05-D7 Main Steam Line Break, IDPV Failure (Bounding Case) PCCS Vent Fan, DW-WWVacuum Breaker (30 Days).

18

16 t [ Vcuum Breaecr Flow 1 MFLO100003

Vacuum Bra.er Flow 2 MFLO420003

14-4-

•-12

0. 10

8

•6

4-

2-

0 4-720 72.5

1730

Time (s)

1715 74,0

Figure 6.2-140 S05-D7a Main Steam Line Break, 1DPV Failure (Bounding Case) PCCS Vent Fan, DW-WWVacuum Breaker (72 hr-74 hr).

16 of 37


010

0.09

008

007

0.06

0.05

0.04

0,03

0.02

1 001

0,00

j. -0.01

4 -0.02

-0.03

-0.04

-0.05

-0.06

-0.07

-0.08

-0.09

-0.10

OW-WW Le.We FR., MFL01800V

-- I F

0 48 96 144 192 240 288 336 384Time (hr)

432 480 528 576 624 672 720

Figure 6.2-140 S05-D8 Main Steam Line Break, IDPV Failure (Bounding Case) PCCS Vent Fan, DW-WWLeakage (30 Days).

0.1

0.c

0.0

00

00

0.0

0.0

0.0

0.0

n,0.0

0.

0-0i-0.

-0ý

-0.1

-0.'

-0.'

-0.

-0.

0 - . . . . . . . . . .

9

8 DW-WYA'LeBeW Fkw NLO01W3

07

6

05

04

13

02

)010-

01

02

03

04

05

06

07

08

29

10 .1 1 1 11 1 .. . . 1 1 11

72.0 72 5 73.0 735 74.0Time (hr)

74,5 75.0 75.5 76 0

Figure 6.2-140 S05-D8a Main Steam Line Break, 1 DPV Failure (Bounding Case) PCCS Vent Fan, DW-WWLeakage (72 hr-76 hr).

17 of 37


• '-'NC Gas in Drywall

3900

3600

3300

3000

2700

2400/

S-2100 / / -- NC Gas Mass ALP9922O ]

.1800 //

1500

1200

900J

600

300

0-+0 48 96 144 192 240 288 336 384 432 480 528 576 624 672 720

Time (hr)

Figure 6.2-140 S05-D9 Main Steam Line Break, IDPV Failure (Bounding Case), DW Total NoncondensableGas Mass (30 Days).

NC Gas in Drywall3000-

2700

2400

2100

1800

-NC G. M-s ALP992T201

1500

1200

900

600

300

0 ,

72.0 72.5 73,0 73,5 74 0 74.5 7560 75.5 76 0Time (hr)

Figure 6.2-140 S05-D9a Main Steam Line Break, IDPV Failure (Bounding Case), DW Total NoncondensableGas Mass (72 hr-76 hr).

18 of 37


16

14

12

NC Gas in WW Airspace

I . . . . I . . . . I . . . . I . . . . I . . . . !

10

8I I-NC Gas Mass (loINn WNW A~rspace)I

6

4-

2

0 I I • [ I I I . . . .

0 48 96 144 192 240 288 336 384Time (hr)

432 480 528 576 624 672 720

Figure 6.2-140 S05-DlO Main Steam

16. ..

Line Break, IDPV Failure (Bounding Case), Total WW NoncondensableGas Mass in Air Space (30 Days).

NC Gas in WW Airspace

14 -

12 +

10 -

a

6

4

2

I- NC Gas Mass (ThI, Pn 5Arspase)

0

72.0I I . . . . I . . .I . I I. . . . I I

72.5 73.0 73.5 74.0Time (hr)

74.5 7560 75.5 76,0

Figure 6.2-140 S05-DI0a Main Steam Line Break, IDPV Failure (Bounding Case), Total WWNoncondensable Gas Mass in Air Space (72 hr-76 hr)

19 of 37


340 . .I I. .

33,5PCC Pc/l Water Level oZLVOg3604Top of PCC Tubes DZLV993704

33.0 3/4 PCC Tubes DZLV993804

Moddle DZLV993904Vt4 PCC Tubes DZLV994004

Bo f PCC Tubes DZL 994104

32.5

320

31.5

- 31.0

295

290

28.5

0 48 96 144 192 240 288 336 384 432 480 528 576 624 672 720Time (hr)

Figure 6.2-140 S05-DI I Main Steam Line Break, 1DPV Failure (Bounding Case), PCC Pool 2 Phase Level(30 Days).

34.0 . . . . . .

335PCC Poo' Water Le-el DZLV9g3604

Top of PýCC TubeS DZLV9g370433.0 3/4 PCC Tubes DZLV993804

Middle DZLV9939O41/4 PCC Tubes DZLV994004

Bo1om of PCC Tubes D03V994104

32.5

320

315

5@ 31.0

30.5

30.0

29.5

29 0

28.5

28,0 11111111111. 1111, , I ,72.0 725 73.0 735 740 74.5 75.0 75.5 76.0

Time (hr)

Figure 6.2-140 S05-DI la Main Steam Line Break, IDPV Failure (Bounding Case), PCC Pool 2 Phase Level(72 hr-76 hr).

20 of 37


34,,, 0 ..? ,.?. .. .. . . .. .

335

33 0

32.5

32,0

31 5

30Z5

30.0

295

29 0

28 5

28.0 I0 48 96 144 192 240 288 336 384

Time (hr)

Figure 6.2-140 S05-D12 Main Steam Line Break, IDPV Fail

• ' ' [ . . . . I . . . . I . . . . I •rlllllJ•411iF

PCC Poo Water Leve CollapsedTop of PCC Tbes

314 PCC TubesMiddle

1/4 PCC TubesPotto of PCC Tubes

4 I 48 528 576 624 672432 480 528 576 624 672 720

(30 Days).lure (Bounding Case), PCC Pool Level Collapsed

340

33,5

33.0

32.5

32.0

31 5

*j 310

30 5

30.0

29.5

290

28 5

28&0 - I

72.0

PCC Pool water Laval Coftapsed

Top of PTCC Tues

304 PCT TabesMO ddla

1/4 PCC TabesBolom of PCC TPe5

i ! i I I I I I [ F i I i f f i i i i i I I I I I I ! ! i I ! i I I i

72.5 73.0 735 740Time (hr)

I I I I I I I I I • ] I ] • ( I I

74,5 75.0 75.5 760

Figure 6.2-140 S05-D12a Main Steam Line Break, iDPV Failure (Bounding Case), PCC Pool Level Collapsed(72 hr-76 hr).

21 of 37


140

130

120

110

100

90

2-PCCS Pool R04

- 136 TLgg3604_ .37 TL993704L38 TL993804

- L39 TL993904140 TL904004L41 TL994104

80

70

60

50

40i

0 48 96 144 192 240 288 336 384Time (hr)

432 480 528 576 624 672 720

Figure 6.2-140 S05-D13 Main Steam Line Break, IDPV Failure (Bounding Case), PCC Pool WaterTemperature (2-PCCS Pool) (30 Days).

140

130 -1-

I I . I I ý

2-PCCS Pool R04

1. 36 Th993884

1. 37 T1.8937041.384 Th994104

1.38 Th9938041.40~ Th893904

1. 41 Th994004

120 -

110 +

100

83"-_. 90 -

80 -

70+

60

50 1

4072.0 725 73.0 735 740

Time (hr)

7 75 7 I I I I I745 75.0 75.5 76,0

Figure 6.2-140 S05-DI3a Main Steam Line Break, 1DPV Failure (Bounding Case), PCC Pool WaterTemperature (2-PCCS Pool) (72 hr - 76 hr).

22 of 37


140

130

120

110

100

90

80

70

60

50

40

4-PCCS Pool R6

L36 Thg93606L37 TL 93706L38 TL993806L39 TL93906W4 Th9~4006L41 TL994106

0 48 96 144 192 240 288 336 384Time (hr)

432 480 528 576 624 672 720

Figure 6.2-140 S05-D14 Main Steam Line Break, 1DPV Failure (Bounding Case), PCC Pool WaterTemperature (4-PCCS Pool) (30 Days).

140

130

120 -

110-

~90-

4-PCCS Pool R6

L36 TL993606L37 TL993706

L38 TL993806- L39 TL993906

L40 TL994006L41 TL994106

i..-

80 +

70

60±

50

40 I ~ ~~~~ i I I I I I I I i I [ f I I I I t I I I I I I I I I I I I i I

72.0 I . . . . . . . . . . I .72.5 73.0 73.5 74,0Time (hr)

74,6 75.0 75.5I • f I

76.0

Figure 6.2-140 S05-Dl4a Main Steam Line Break, IDPV Failure (Bounding Case), PCC Pool WaterTemperature (4-PCCS Pool) (72 hr-76 hr).

23 of 37


Sup Pool Temperature

2U0 ,

180 -

160 +

140 4

120

1 1oo0

I- an

TL992507TL9 2607TL 99 2707TL921117TL992907

du

60

40 -

20

00 48 96 144 192 240 288 336 384

Time (hr)432 480 528 576 624 672 720

Figure 6.2-140 S05-D15 Main Steam Line Break, IDPV Failure (Bounding Case), Suppression PoolTemperature (R7) (30 Days).

200 ,Sup Pool Temperature

180

-T11121111T19 2607T L992 707TL992807TL992907

160

140

120

-9 100

•80

60

40±

204-

072.0

I . . . .I I ý . . . I I I ý I I ,72.5 73.0 73,5 740

Time (hr)74.5 75.0 75.5 76.0

Figure 6.2-140 S05-DI15a Main Steam Line Break, IDPV Failure (Bounding Case), Suppression PoolTemperature (R7) (72 hr - 76 hr).

24 of 37


200

180

160

140

120

2100

'80

-- TL992608

TL992708Th99ý2ýOý -

60

40

20

00 48 96 144 192 240 288 336 384 432 480 528 576 624 672 720

Time (hr)

Figure 6.2-140 S05-D16 Main Steam Line Break, IDPV Failure (Bounding Case), Suppression Pool LiquidTemperature (R8) (30 Days).

200 . , ,

180 4 TLq92508TL992608

TL992708

L992808160 t

140

120U

1i 100

80

60+

40

20 +

0 I I l i l l l l l l lI Il t I II

72.0 72.5 73.0 73.5 74.0

Time (hr)745 75.0 75.5 76.0

Figure 6.2-140 S05-DI6a Main Steam Line Break, IDPV Failure (Bounding Case), Suppression Pool LiquidTemperature (R8) (72 hr-76 hr).

25 of 37

I--- MFN 09-023 Supplement 3Enclosure 1

140 •. .

130

120

110

100

G- 90

80

70

60

50

40

240 288 336 384 432 480 528 576 624 672Time (hr)

Figure 6.2-140 S05-D17 Main Steam Line Break, IDPV Failure (Bounding Case), Wetwell Airspace VaporTemperature (L29-L31) (30 Days).

140 . . .

130

120

110

100

U90-

80

VWW Region

70

604-

50 T L29 8ý07 TV992907 -- 129 ROB TV992908 U30 807 7V993007L30 R08 TV993008 L31 P07 TV993107 - L3t R08 00993108

40 II[lllll[[l[l[•l[•l[lilllllllll•lill[ll

72.0I I . . . I . . . . I . . .I I,

725 7310 735 74 0Time (hr)

F I I I 7i574.5 75 0 755 760

Figure 6.2-140 S05-DI7a Main Steam Line Break, 1DPV Failure (Bounding Case), Wetwell Airspace VaporTemperature (L29-L31) (72 hr-76 hr).

26 of 37


200

180

160

140

120

100

s-

80

60

GDCS Pool Liquid Temperatures

. .. .I ' I i I I I I " I " " " , ,- I I -I I I I - - -- I --- I----------

40

20

0

0 48 96 144 192 240 288 336 384Time (hr)

432 480 528 576 624 672 720

Figure 6.2-140 S05-D18 Main Steam Line Break, IDPV Failure (Bounding Case), GDCS Liquid Temperature(R7) (30 Days).

200 .. . . . . .

180 GDCS Pool Liquid Temperatures - T0

I I

160 f

140

120

a -

0.100-E-

80

60±

404-

20 -

0 i i i I i I I I I I I I I I I I I I I I I -! !

72.0 72.5 73.0 735 740Time (hr)

74.5 75.0 75.5 76.0

Figure 6.2-140 S05-D18a Main Steam Line Break, IDPV Failure (Bounding Case), GDCS LiquidTemperature (R7) (72 hr - 76 hr).

27 of 37


210

180 GDCS Pool Liquid Temperatures Ii.... r3i40a

160

140 / -

120 -

-.100

80

60

40

20

0

0 48 96 144 192 240 288 336 384 432 480 528 576 624 672 720Time (hr)

Figure 6.2-140 S05-D19 Main Steam Line Break, IDPV Failure (Bounding Case), GDCS Liquid Temperature(R8) (30 Days).

20 0 . . . . . . . . . . . . . . . . . I

180 GDCS Pool Liquid Temperatures

160

140 -- - ---

120

0100

80

60

40

20

720 725 73.0 735 740 745 75.0 755 760Time (hr)

Figure 6.2-140 S05-D19a Main Steam Line Break, IDPV Failure (Bounding Case), GDCS LiquidTemperature (R8) (72 hr-76 hr).

28 of 37

MFN 09-0Enclosure

160 -

150

140

130

120

110

23 Supplement 31

IGDCS Pool Adr Space

GDCS PoP N' Tomperatre L34 R7 (2) TV40

IDCS Pool Tepe Orature L34 R8 (4) TV=93408

-100

90

80

70

60

50

0 48 96 144 192 240 288 336 384 432 480 528 576 624 672 720Time (hr)

Figure 6.2-140 S05-D20 Main Steam Line Break, 1DPV Failure (Bounding Case), GDCS Air Space VaporTemperature (30 Days).

150

140

130 +

120

110

100-

90

80

70

60

50

IGDCS Pool Air Space

GDCS Pool Per Tnperte.ee L34 P7)2) TV99340 0--GCS POe) pr T-mfntree L 34 P8 )4) T933408

4 0 + + I ! I I I I , , I I i d I I , i ! Ii 1 ! ! I I ! I ! I

720 72.5 73.0 735 74.0 74,5 75.0 75.5 760Time (hr)

Figure 6.2-140 S05-D20a Main Steam Line Break, IDPV Failure (Bounding Case), GDCS Air Space VaporTemperature (72 hr - 76 hr).

29 of 37


30 .PCCS Inlet Flows

1- TO FCC Inlet Floss MFLO220001ToIN NC Gas Flos MFLO830001

25 -4-

20 -

e15

10-

5 +

n SI I l 1 ' l 1 l l l j l ! l ! i i I l l i l l i i 1 1i P l l I Lý I E l l l l I E l l l! l! ! l ! l 1 l1 l

0 48 96 144 192 240 288 336 384 432 480 528 576 624 672 720Time (hr)

Figure 6.2-140 S05-D21 Main Steam Line Break, IDPV Failure (Bounding Case), Total PCCS Inlet FlowRates (30 Days).

- -' PCCS Inlet Flows

T~ Colr CC 5 Fl-s MFL.02200017Total PNC Gas Flo- WI-OO30001

35 -

30 -

i25

20

* 15

10-

5 -

0 1 !I :I f i I I I 4=72.0 72.5 73.0 73.6 74.0 74.5 75.0 75.5 76.0

Time (hr)

Figure 6.2-140 S05-D21a Main Steam Line Break, 1DPV Failure (Bounding Case), Total PCCS Inlet FlowRates (72-76 hr).

30 of 37


180DW Gas Temperature

1o -4

S140 -

120

TV993006TV993106TV993206TV993306TV993406

100

0 48 96 144 192 240 288 336 384 432 480 528 576 624 672 720Time (hr)

Figure 6.2-140 S05-D22 Main Steam Line Break, 1DPV Failure (Bounding Case), Upper DrywellTemperatures (R6) (30 Days).

DW Gas Temperature18 0' I 'I ' ' , , , , , ,

TV9923O6TVZ9ý29T 993006

T.106

TV9.3206TV993406160 +

1

• 140-

&

120 +

1 o 1 ! 1 1 1 1 1 i , I , , I I , , , I i I I i , , , I , , !72.0 725 73.0 735 740 745 750 75.5 760

Time (hr)

Figure 6.2-140 S05-D22a Main Steam Line Break, IDPV Failure (Bounding Case), Upper DrywellTemperatures (R6) (72 hr -76 hr).

31 of 37


180

DW Gas Temperature

160

140

I,-

-- TV992206

TV992406TV992570TV992606TV"92706

120

100

0 48 96 144 192 240 288 336 384Time (hr)

432 480 528 576 624 672 720

Figure 6.2-140 S05-D23 Main Steam Line Break, IDPV Failure (Bounding Case), Lower DrywellTemperatures (R6) (30 Days).

180 r rDW Gee Temperature

160

TV992206Tvggý2306TV992406TV992506

- V2606TV992706

a

140

C.

120 +

100

72.0I . . .I I I I . . . . I . . .I I '

72,5 73.0 73,5 74.0Time (hr)

I 7 4 I I I , I I7. 5745 75.0 75.5 76.0

Figure 6.2-140 S05-D23a Main Steam Line Break, 1DPV Failure (Bounding Case), Lower DrywellTemperatures (R6) (72 hr-76 hr).

32 of 37


c•eo

Steam Mesa in Drywall18

16

14

13

I- Steam Mass Total. 'P)g2201

17

5

4

2

0

0 48 96 144 192 240 288 336 384 432 480 528 576 624 672 720Time (hr)

Figure 6.2-140 S05-D24 Main Steam Line Break, IDPV Failure (Bounding Case), DW Steam Mass (30 Days).

Steam Mass in Drywall

18

16 -

144

13

Z7

5 - I- Steam Mass (TOta) ALP992201 I

4

2

00 . . .I I. .II I .I . i I. . . . ý . . . I '

72.0 72 5 73.0 735 74,0Time (hr)

74,5 750 75.5 760

Figure 6.2-140 S05-D24a Main Steam Line Break, IDPV Failure (Bounding Case), DW Steam Mass (72 hr -76 hr).

33 of 37

MFN 09-0Enclosure

2400

2160

1920

1680

1440

1200

960

720

480

240

00

23 Supplement 31

Steam Mess in WW Airspace

Steeas Mass (Total)

I I ~I I I I .I • ; I [ i i i t

I I . . . i . . I . . . I . . .I . . . .I I , r . . . , I I I I I r ... . I .. . .. . I . . . . i . . .I I . . . .I I I . . . .48 96 144 192 240 288 336 384 432 480 528 576 624 672 720

Time (hr)

Figure 6.2-140 S05-D25 Main Steam

2400

2160 I

1920 -

1680... "-

1440

1200

960

720

480

240

0

Line Break, IDPV Failure (Bounding Case), WW Steam Mass (30 Days).

Steam Mass in WW Airspace

[- Steals Mass (Total)]

! i i I I ! I I ! I I I I I I I I

72.0 72.5 73.0 73.5 74.0Time (hr)

74.5 75.0 75.5 760

Figure 6.2-140 S05-D25a Main Steam Line Break, 1DPV Failure (Bounding Case), WW Steam Mass (72 hr -76 hr).

34 of 37


18

16

14

12

1-

6-

4-

WW NC Mess ALP992907WW*DW NC M-ss ROA992907WW.DWVGDCS NC Mass ALP992908WWODW-GDCS*DWH NC Mass ROA992908

0 48 96 144 192 240 288 336 384 432 480 528 576 624 672 720Time (hr)

Figure 6.2-140 S05-D26 Main Steam Line Break, 1DPV Failure (Bounding Case), Noncondensable Gas Mass(30 Days).

18

16 +

14+

12

l1o

8

6 ± - WW NC Mess .LP92907"W"W.W NC M'ss ROA992907WW÷DW.GDCS NC MOss ALP992908WW-DW"GDCS*fWH NC Mass ROA992908

4 -

2

72.0 725 73.0 735 740Time (hr)

745 750 75.5 76&0

Figure 6.2-140 S05-D26a Main Steam Line Break, 1DPV Failure (Bounding Case), Noncondensable Gas Mass(72 hr - 76 hr)

35 of 37


450

0.

5 10 15 20 25

Discharge Submergence (in)

Figure 6.2-140S05-1 DW Pressure as a Function of PCC Vent Fan Submergence450

400

350

300

0.

250

0. 200

150

100

50

072 108 144 180 216 252 288 324 360 396 432 468 504 540 576 612 648 684 720

Time (hr)

Figure 6.2-140S05-2 ESBWR DW Pressure with Appropriate Safety Adders

36 of 37


DCD Impact

The following DCD Sections will be revised as noted in the attached markup:

" DCD Tier 1, Table 2.15.4-2

" DCD Tier 2, Section 6.2.1.1.3.5.1

" DCD Tier 2, Section 6.2.2.2.2

" DCD Tier 2, Figure 6.2-14el

* DCD Tier 2, Figure 6.2-14e2

* DCD Tier 2, Figure 6.2-14e13

* DCD Tier 2, Table 6.2-49

37 of 37

Enclosure 2

MFN 09-023 Supplement 3

Response to Portion of NRC Request for

Additional Information Letter No. 375

Related to ESBWR Design Certification Application

Engineered Safety Features

RAI Number 6.2-140 S05

Markups to ESBWR DCD

Tier I and Tier 2 Section 6.2

26A6641AB Rev. 07ESBWR Design Control Document/Tier I

Table 2.15.4-2

ITAAC For The Passive Containment Cooling System

Design Commitment Inspections, Tests, Analyses Acceptance Criteria

11. The PCCS vent fans flow rate is For each PCCS vent fan line, a flow rate * The tested and analyzed flow ratessufficient to meet the beyond 72 test will be performed with the are greater than or equal to thehours containment cooling containment at pre-operational ambient flow rates of the design basisrequirements following a design conditions. Flow measurements will be LOCA containment analysisbases LOCA. taken on flow to the GDCS pools. An model for the PCCS vent fan lines

analysis of the test configuration will be at containment pre-operationalperformed. ambient conditions.

12. The PCCS vent fans can be remotely PCCS vent fans will be started using The PCCS vent fans start when manuallyoperated from the MCR. manually initiated signals from the MCR. initiated signals are sent from the MCR.

13. The PCCS drain piping is installed to Inspection(s) will be conducted of as-built Based on inspection(s) of as-built PCCSallow venting of non-condensable PCCS drain piping to ensure there are no drain piping, the as-built piping conformsgases from the PCCS drain lines to elevated piping loops or high-point traps to a design that allows venting of non-the PCCS condenser vent lines to in piping runs to the GDCS pools. condensable gases from the PCCS drainprevent collection in the PCCS drain lines to the PCCS condenser vent lines.lines.

14. The elevation of the PCCS vent fan A visual inspection will be performed of The elevation of the discharge on thedischarge point is submerged within the PCCS vent fan discharge point relative PCCS vent fan line 24 cm (9.4 in) belowthe drain pan located in the GDCS to the lip of the drain pan. the top of the drain pan lip with apool at an elevation below the lip of tolerance of 1.4 cm (0. 1the drain pan. 0.5 in) and <241 em (E-1 em) below the top

of the drain pa li.

2.15-53

26A6642AT Rev. 07ESBWR Design Control Document/Tier 2

A loss of all power generation buses is not the limiting assumption and the effects of continuedfeedwater injection is more limiting, as it can potentially add water to the wetwell and compressthe wetwell air space. The ESBWR design incorporates features that mitigate this challenge byisolating reactor inventory sources outside of containment and provides a method of GDCSinitiation based on LOCA condition detection. These features ensure that containment remainswithin design pressure for the entire 72-hour event duration. These features also ensureacceptable performance for the full spectrum of LOCA events within containment, with orwithout the assumption of loss of external injection capability. Additionally, although powergeneration buses are considered available to add feedwater or High Pressure Control Rod Drive(HP CRD) injection, no credit is given for heat removal systems powered by these buses. Table6.2-7h shows the sequence of events for the Main Steam Line Break with failure of one SRV andwith offsite power available. Figures 6.2-14j 1 through 6.2-14m3 show the pressure, temperature,DW and GDCS airspace pressure responses and PCCS heat removal for this analysis. Thenoncondensable mass and the void fraction in the DW and GDCS are presented in Figures 6.2-14nl through 6.2-14o3. The detailed discussion on the chronology of progression is given inAppendix 6E.5. The cases analyzed without offsite power and water addition assume higherinitial pressure, and result in higher pressure as shown in Table 6.2-5. The highest value ofMaximum DW Pressure in Table 6.2-5 is the calculated peak containment internal pressure forthe design basis loss of coolant accident.

6.2.1.1.3.5.1 Post-LOCA Containment Cooling and Recovery Analysis

For post-LOCA containment cooling and recovery, the Main Steam Line Break with failure ofone DPV is selected. The analysis results are not sensitive to the event selection (failure of oneDPV versus one SRV) due to the fact that these two cases are nearly the same in transientresponses up to 72 hours and the containment pressure and temperature are rapidly reduced uponthe activation of the nonsafety-related Structure, System, or Components (SSC).

After the first 72 hours of the accident, the following nonsafety-related SSCs are utilized to keepthe reactor at safe stable shutdown conditions, to rapidly reduce containment pressure andtemperature to a level where there is acceptable margin, and then to maintain these conditionsindefinitely:

(1) SSCs to refill the IC/PCCS pools;

(2) PCCS Vent Fans;

(3) Passive Autocatalytic Recombiner System (PARS); and

(4) Power supplies to the PCCS Vent Fans and the IC/PCCS pool refill pumps.

Once a state of safe, stable reactor shutdown is reached, containment pressure and temperatureare maintained with sufficient margin to containment design limits for a long period of time.Figure 6.2-14el through Figure 6.2-14el0a show key parameters for the long term pressurereduction and maintenance phase. PARS function at 72 hrs and 4 of 6 PCC vent fans arecredited in the calculation. A containment system performance acceptance criteria ("AnalyticalPressure Limit" curve) is shown on Figure 6.2 14el which considers variations in IC/PCC poolfrom minimum to maximum and fan discharge submergence variations during the simulation.

To bound uncertainties and variations in the IC/PCC pool level from minimum to maximum andfan discharge submergence variations during the simulations, an adiustment is determined and

6.2-11


added to the base results. Figure 6.2-14el 3 compares the adjusted pressure to the containmentsystem performance acceptance criteria. The containment pressure is reduced and remainsbelow the acceptance criteria.

Other non-safety related, non-Regulatory Treatment of Non-safety Systems (RTNSS) SSCs canbe placed in service to bring the reactor to cold shutdown conditions and to further reduce thecontainment pressure and temperature. These SSCs include the FAPCS as the preferred method,and the RWCU/Shutdown Cooling (SDC) system in the unlikely event there is fuel damage(Subsections 9.1.3 and 5.4.8, respectively). The RWCU/SDC and the FAPCS system are notpart of the primary success path for post-LOCA containment cooling. Calculations ofRWCU/SDC performance are provided here to show its ability to cooldown the reactor andcontainment. In the unlikely event of fuel damage, where the RWCU/SDC system is used, theReactor Building HVAC Accident Exhaust Filter Units are a required support system for limitingonsite and offsite dose.

Containment pressure and temperature responses which represent a postulated accident recoveryevolution, with RWCU/SDC (fuel damage assumed) providing the cold shutdown function areshown in Figures 6.2-14ell and 6.2-14e12. These response curves are based on theRWCU/SDC operating in suppression pool cooling mode for 24 hours, beginning seven daysafter a LOCA, followed by vessel injection via the normal RWCU/SDC midvessel suction line,with suction from the suppression pool. The heat removal for this mode of RWCU/SDCoperation is provided by the non-regenerative heat exchanger (NRHX). A conservative heatexchanger capacity was assumed which is well within the capability of the RWCU/SDC NRHX.Table 6.2-48 lists the RWCU/SDC NRHX data used in the analysis. There is no requirement tostart the recovery actions at seven days, since the reactor is already in a safe stable shutdowncondition, and containment pressure and temperature are in a non-upward trending state, withsufficient margin to containment design limits.

The accident recovery analysis shows that after being in suppression pool cooling for 24 hoursand then injecting into the reactor vessel for approximately 10 hours, the suppression pool hasequilibrated with the reactor bulk water temperature at cold shutdown conditions.

6.2.1.1.4 Negative Pressure Design Evaluation

During normal plant operation, the inerted WW and the DW volumes remain at a pressureslightly above atmospheric conditions. However, certain events could lead to a depressurization

-transient that can produce a negative pressure differential in the containment. A DWdepressurization results in a negative pressure differential across the DW walls, vent wall, anddiaphragm floor. A negative pressure differential across the DW and WW walls means that theRB pressure is greater than the DW and WW pressures, and a negative pressure differentialacross the diaphragm floor and vent wall means that the WW pressure is greater than the DWpressure. If not mitigated, the negative pressure differential can damage the containment steelliner. The ESBWR design provides the vacuum relief function necessary to limit these negativepressure differentials within design values. The events that may cause containmentdepressurization are:

Post-LOCA DW depressurization caused by the ECCS (for example, GDCS) flooding ofthe RPV and cold water spilling out of the broken pipe or cold water spilling out ofbroken GDCS line directly into DW.

6.2-12


The PCCS condensers are located in a large pool (IC/PCCS pool) positioned above the ESBWRDW.

Each PCCS condenser is configured as follows (Figures 3G. 1-7 1a and 3G. 1-71 b).

A central steam supply pipe is provided which is open to the DW airspace at its lower end. Theopen end of this pipe is provided with a debris filter with holes no greater than 25 mm (1 inch).The maximum inlet velocity during a LOCA is estimated to be no greater than 106 m/s (348 ft/s).The steam supply feeds two horizontal headers through two branch pipes at its upper end. Steamis condensed inside vertical tubes and the condensate is collected in two lower headers.

The vent and drain lines from each lower header are routed through the DW through a singlepassage per condenser module as shown on the figures.

The condensate drains into an annular duct around the vent pipe and then flows in a line thatconnects to a large common drain line, which also receives flow from the other header. The ventline goes to the suppression pool and is submerged below the water level.

A Passive Containment Cooling vent fan is teed off of each PCCS vent line and exhausts to theGDCS pool. The fan aids in the long-term removal of noncondensable gas from the PCCS forcontinued condenser efficiency. The minimum fan performance requirements are shown inTable 6.2-49. The fans are operated by operator action and are powered by a reliable powetsource which has a diesel generator backed up by an ancillary diesel, if necessary, without theneed to enter the primary containment. The discharge of each PCCS vent fan is submergedbelow the GDCS pool water level to prevent backflow that could otherwise interfere with thenormal venting of the PCCS. The vent fan discharge line terminates in a drain pan within theGDCS pool so that the gas seal is maintained after the GDCS pool drains. The vent fandischarge line is 24 cm (9.4 in) below the top of the drain pan lip with a tolerance of 1.4 cm (0.6in > 0.22 m (9 in) and < 0.25 f (10 in) below the top of the drain pan lip. To further preventreverse flow through an idle fan, a check valve is installed downstream of the fan.

The PCCS condensers receive a steam-gas mixture supply directly from the DW. The PCCScondensers are initially driven by the pressure difference created between the DW and thesuppression pool during a LOCA and then by gravity drainage of steam condensed in the tubes;so they require no sensing, control, logic or power-actuated devices to function. In order toensure the PCCS can maintain the DW to WW differential pressure to a limit less than the valuethat causes pressure relief through the horizontal vents, the vent line discharge point is set at anelevation submerged below low water level and at least 0.85 m (33.5 in) and no greater than0.900 m (35.4 in) above the top of the uppermost horizontal vent. The PCCS condensers are anintegral part of the safety-related containment and do not have isolation valves.

The drain line is submerged in the GDCS pool to prevent back-flow of steam and gas mixturefrom the DW to the vent line, which would otherwise short circuit the flow through the PCCScondenser to the vent line. It also provides long-term operational assurance that the PCCScondenser is fed via the steam supply line. The drain line terminates in the same drain pan as thevent fan discharge to replace any evaporation loss in the drain pan after the GDCS pool drains.

Each PCCS condenser is located in a subcompartment of the IC/PCCS pool, and all poolsubcompartments communicate at their lower ends to enable full use of the collective waterinventory independent of the operational status of any given IC/PCCS sub-loop.

6.2-28


Design DW and WW Pressure

400

350W&-- 1 Wet ..ll (~ L-v1 31 .Ring 7) P993107RPV P-esume (L-I 21, Ring 1) P292101

300 .

250

100

50

0 24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 384 408 432 456 480 504 528 552 576 600 624 648 672 696 720Time (hr)

450.. . .I.. . . .. . . I

Design DW and WV Pressure

400

350 "" D Pressure (eVe 34 Reg 5) P99340//~~~R Ieg rerwetweeg Presue (Leve1l 31,Pg 7) Pg93107

-RPV Pressre (Lee 21. RPng 1) P992101

300

a:

150

100

50

0

0 24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 384 408 432 456 480 504 528 552 576 600 624 648 672 696 720Time (hr)

Figure 6.2-14e1. Drywell, Wetwell and RPV Pressures (720 hr)

6.2-297

26A6642AT Rev. 07ESBWtR

450

Design Control Document/Tier 2

. . . .

Design DW and WWV Pressure

400

350 -

300

250

200-

ISO W~re P-essure (Le-e 31.Ring T) P993107

- RPVPissum (Level 21,RiN 1) P992101Dealgn PressureAnau5t5al Pressue Lit

100

50

0

450

I . . I i M a i I 9 6 A i I i d & i I $ & K i i i A a i72 84 96 108 120 132 144

Time (hr)

Design OW and WW Pressure

400

350

300

1 250

I20090

150

100

50

0-

Sryeel Pressure (Level 34.11-g 5) P993405wet.5 Pressure (Leve- 31.es 71 P993,07RPV Pressure Lees 21, Ping 1) P992101Desgn Pressure

721

84 961

108 120Time (hr)

32 1111 156 1 16132 144 156 168

Figure 6.2-14e2. Drywell, Wetwell and RPV Pressures (72 - 144 hr)

6.2-298

26A6642AT Rev. 07ESBWR

450

400

350

300

0t.

250

o. 200

150

100

50

0

Design Control Document/Tier 2

72 108 144 180 216 252 288 324 360 396 432 468 504 540 576 612 648 684 720

Time (hr)

Figure 6.2-14e13. Drywell Pressure with Sensitivity to Vent FanSubmergence and PCC Pool Level (72 hr to 720 hr)

6.2-305


Table 6.2-49

PCCS Vent Fan Minimum Performance Requirements'

Normalized Fan Head AP/p m3 /Sm /s2 (ft2/s2) Flow (CFM)

2,410 (25,900) 0.071 (150)

2,380 (25,600) 0.141 (300)

2,290 (24,600) 0.283 (600)

2,050 (22,100) 0.472 (1,000)

1.880 (20.200) 0.566 (1.200)

1,390 (15,000) 0.741 (1,570)

1. The inlet losses for the PCCS are described in Table 6.2-8, Item 4. The outlet losses shallnot exceed a k/A 2 value of 1500 m-4 (174,000 fi-4).

6.2-191

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