ML18067A479

Forwards Response to 961213 RAI Re 10CFR50.46 Large Break Loss of Coolant Accident Evaluation Model

ML18067A479
Person / Time
Site:	Palisades
Issue date:	04/09/1997
From:	BORDINE T C CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9704160004
Download: ML18067A479 (10)

Text

A CMS Energy Company April 9, 1997 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 DOCKET 50-255 -LICENSE DPR-20 -PALISADES PLANT 11JOIDBS t:. Bord/DB Manager Licensing RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REGARDING 10CFR50.46 LARGE BREAK LOSS OF COOLANT ACCIDENT EVALUATION MODEL In a letter dated October 11, 1996, the NRC notified Consumers Energy Company of concerns that had arisen regarding the Siemens Power Corporation (SPC) Large Break Loss-of-coolant Accident (LOCA) evaluation model for pressurized water reactors.

Consumers Energy responded with an assessment of the impact of these problems on the Palisades Plant in a letter dated October 24, 1996. This assessment was further clarified in a Consumers Energy Company letter dated November 22, 1996. Subsequently, in a letter dated December 13, 1996, the NRC requested additional information to be provided within 120 days. The Attachment to this letter provides the requested information.

SUMMARY

OF COMMITMENTS This letter contains no new commitments and no revisions to existing commitments.

Thomas C. Berdine Manager, Licensing 15 Q 14 8 CC Administrator, Region Ill, USNRC Project Manager, NRR, USNRC NRC Resident Inspector

-Palisades Attachment 9704160004 970409 PDR ADOCK 05000255 p PDR 11n11111m nm nm mu 11111 HD

• I 1

• t t 1 I I I

• Palisades Nuclear Plant

• 27780 Blue Star Memorial Highway

• Cove;/, Ml 49043

• Tel: 616 764 2913

• Fax: 616 764 2490 ATTACHMENT CONSUMERS ENERGY COMPANY PALISADES PLANT DOCKET 50-255 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION REGARDING 10CFR50.46 LARGE BREAK LOSS OF COOLANT ACCIDENT EVALUATION MODEL 8 Pages

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• RESPONSE TO NRC REQUEST FOR ADDITIONAL 10CFR50.46 LARGE BREAK LOSS OF COOLANT ACCIDENT EVALUATION MODEL . ' NRC letter of December 13, 1996, requested Consumers Energy Company to provide additional information regarding the Palisades LBLOCA analysis.

Each information request and associated Palisades response are itemized below. 1. Request: Maximum linear heat generation rate Response:

The maximum linear heat generation rate (LHGR) is 15.28 KW/ft. 2. Request: Reflood rate as a function of time Response:

See Figure 1. The reflood rate in this figure is the effective flooding rate which is used by the FCTF correlation.

3. Request: Core collapsed level as a function of time Response:

See Figure 2. 4. Request: Quench time as a function of core height Response:

See Figure 3. 5. Request: Core pressure as a function of time Response:

Figures 4 and 5 show core exit pressure during blowdown and reflood, respectively.

6. Request: Core subcooling as a function of time Response:

SPC uses the initial inlet subcooling as input to the FCTF heat transfer correlation.

The correlation uses only the initial inlet subcooling.

The dependence of the heat transfer coefficient on the inlet subcooling is quite weak; and, consistent with the FLECHT correlation, the instantaneous subcooling was not used to correlate the test data and is not used in the analysis.

The initial core inlet subcooling predicted for Palisades is 161.72"F.

However, SPC conservatively uses 135"F as input to the FCTF correlation.

135"F is the maximum subcooling represented in the data on which the correlation is based. 7. Request: Heat transfer coefficient for PCT location as a function of time Response:

See Figure 6. 8. Request: Clad temperature for PCT location as a function of time Response:

See Figure 7.

. .

13, 1997 ,,,..... 0 Q) rn " 2.2 .s 1.9 . 'wl 1.3 40.0 50.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 Time (seconds)

Figure 1 Reflood Rate as a Function of Time

13, 1997 '*. '.-:.___ .. , "' 5.0 .... 4.0 v > v J 'O *a 3.o .... 'O v al 2.0 .... .... 0 (.) 1.0 20.0

• 70.0 120.0 170.0 220.0 270.0 320.0 Time (seconds)

Figure 2 Collapsed Liquid Level in Core as a Function of Time February 13, 1997. ,..... 300.0 rn 'C 0 CJ QJ rn 'W QJ 8 200.0 .d CJ QJ a 100.0 0.0

• 2.0 4J lO lO 10.0 12.0 Core Height (feet) Figure 3 Quench Time as a Function of Core Height

' .

• Febryary 13, 1997 ,,,.... *a; 2000.0 Q) Jo. 0 u 1500.0 Jo. 0 () Q) = 1000.0 *1"4 Q) M rn rn Q) 500.0 M 0.0 5.0 10.0 15.0 Time (seconds)

Figure 4 20.0 Upper Plenum (Core Exit) Pressure During Slowdown Period 25.0

• February 13, 1997 .. ' """' *poj rn . 45.0 Q) M 0 u M 0 +J 40.0 Q) d *"4 Q) M l1J .35.0 l1J Q) M °'4 20.0 40.0 60.0 80.0 Time (seconds)

Figure 5 100.0 Pressure in Reactor Vessel Upper Plenum (Core Exit) during Reflood 120.0

• bl) Q.) Q I +J

I: 0.0 24.0 48.0 72.0 96.0 120.0

• Time (seconds)

Figure 6 Heat Transfer Coefficient for PCT Location A * .*: '

13, 1997 ., 2000.0 ""'

• rn Q) 1750.0 Q) 1-4 bD Q) '-I Q) 1500.0 M .jiJ M Q) 1250.0 s Q) E-t bD 1000.0 (!j .-1 u 750.0 m Q) 500.0 0.0

• 24.0 48.0 72.0 Time (seconds).

Figure 7 I Peak Cladding Temperature as a Function of Time 96.0 120.0