L-98-158, Forwards Rept Per 10CFR50.46(a)(3)(ii),which Provides Notification of Error Discovered in Icecon Computer Code Which Is Part of Large Break LOCA Evaluation Model for St Lucie,Unit 1
| ML17229A774 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 06/15/1998 |
| From: | Stall J FLORIDA POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| L-98-158, NUDOCS 9806230367 | |
| Download: ML17229A774 (6) | |
Text
CATEGORY 1~
REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9806230367 DOC.DATE: 98/06/15 NOTARIZED: NO FACIL:50-335 St. Lucie Plant, Unit 1, Florida Power
& Light Co.
AUTH.NAME AUTHOR AFFILIATION STALL,J.A.
Florida Power
&. Light Co..
RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
DOCKET 05000335
SUBJECT:
Forwards rept per 10CFR50.46(a)
(3) (ii),which provides notification of error discovered in ICECON computer code which is part of large break LOCA evaluation model for St Lucie,Unit l.
DISTRIBUTION CODE:
AOOID COPIES RECEIVED:LTR 1
ENCLj SIZE:
TITLE: OR Submittal: General Distribution NOTES:
E RECIPIENT ID CODE/NAME PD2-3 LA GLEAVES,W COPIES RECIPIENT LTTR ENCL.
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ILE CENTER 01 NRR/DE/EMCB NRR/DSSA/SPLB NUDOCS-ABSTRACT NRC PDR 1
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NOTE TO ALL "RIDS" RECIPIENTS:
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Florida Power &Light Company, 6351 S. Ocean Drive, Jensen Beach, FL 34957 June 15, 1998 L-98-158 10 CFR 50.46 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Re: St. Lucie Unit 1 Docket 50-335 LBLOCAEvaluation Model 30 Da 10CFR50.46 Re ort The attached report is submitted pursuant to 10 CFR 50.46(a)(3)(ii) to provide notification of an error discovered in the ICECON computer code which is part of the large break loss of coolant accident (LBLOCA) evaluation model for St. Lucie Unit 1, and concurrently provide the status of the LBLOCAevaluation model relative to the previously reported excessive variability in the RELAP4 computer code.
The estimated impact on calculated peak cladding temperature (PCT) from each anomaly is not significant; however, cumulative (absolute) PCT changes are estimated to exceed 50'F and meet the criteria for reporting within 30 days.
A summary of the cumulative changes to the limiting calculated PCT is provided.
Should there be any questions, please contact us.
Very truly yours, J. A. Stall Vice President St. Lucie Plant JAS/RLD Attachment cc:
Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, St. Lucie Plant
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PDR ADOCK 05000335 P
PD+R an FPL Group company
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St. Lucie Unit 1 Docket No. 50-335 LBLOCAEvaluation Model 30Da 10CFR50.46 Re ort L-98-1 58 Attachment Page1 of 2 Siemens Power Corporation (SPC) performs the emergency core cooling system (ECCS) analyses for St. Lucie Unit 1. The estimated impact on the limiting peak cladding temperature (PCT) from each anomaly discussed below is not significant; however, cumulative (absolute) PCT changes are estimated to exceed 50'F and therefore meet the 30 day reporting criteria. The current St. Lucie Unit 1 large break loss of coolant accident (LBLOCA)analysis PCT is 2040'F as reported in the 10 CFR 50.46 annual report for the year 1997 (Reference 1). A summary of cumulative changes to PCT is provided in Section III of this report.
I.
RELAP4 Excessive Variabilit Issue SPC previously identified a deviation in its EXEM/PWR LBLOCAevaluation model which was reported to the NRC by SPC in January 1998, and again by Florida Power and Light Company (FPL) and SPC in March 1998 (References 1, 2). The deviation occurs as a result of excessive variability experienced by the RELAP4 computer code.
Subsequent to these notifications, SPC completed a 10 CFR Part 21 evaluation of this issue which was reported to the NRC by SPC on May 1, 1998 (Reference 3).
The impact on the St. Lucie Unit 1 LBLOCAPCT has been calculated to be a reduction in PCT of 28'F.
This impact is based on a developmental version of the code which has corrections to reduce the RELAP4 variability. FPL willcontinue to followthe SPC LBLOCA evaluation model corrective action plan as described to the NRC in Reference 2. Based on this action plan, the St. Lucie Unit 1 analysis of record PCT remains unchanged at its current value of 2040'F.
II.
ICECON Code Error On May 21, 1998, FPL received notification from SPC that an error had been discovered involving the units of time used within the ICECON computer code.
ICECON calculates the energy removed by containment fan coolers and is part of the evaluation model used to assess ECCS performance during a LBLOCA. The error results in an unreasonably small value of energy removal by the cooling fans during the analyzed event.
SPC's generic estimate of the impact of the error on calculated PCT is less than 20'F.
Sufficient margin exists in the analysis of record PCT (2040'F) for St. Lucie Unit 1 to accommodate this error and provide assurance that 10 CFR 50.46 acceptance criteria for ECCS performance continue to be met. Plant-specific confirmatory results after correction of the code error are expected to be available later in 1998.
St. t ucie Unit 1 Docket No. 50-335 LBLOCAEvaluation Model 30 Da 10 CFR 50 46 Re ort L-98-158 Attachment Page 2 of 2 III.
Summa of Cumulative Chan es in PCT St. Lucie Unit 1 LBLOCASummary
'Change following correction of z-equivalent error
'Change due to revised containment spray and fan cooler minimum delay time Change due to corrected RELAP4 excessive variability Estimated impact from ICECON error PCT ('F)
-28
<20
- Changes annotated with an asterisk are included in the limiting PCT value of 2040 F
reported in Reference 1.
IV.
References 1.
Florida Power and Light Company letter L-98-057, J. A. Stall to NRC (DCD):
Acceptance Criteria for Emergency Core Cooling Systems for Light Water Nuclear Power Reactors, 10 CFR 50.46 Annual Re ort; March 4, 1998.
2.
Siemens Power Corporation letter NRC:98:016, James F. Mallay to NRC (DCD),
ATTN: Chief, Planning, Program and Management Support Branch: RELAP4 Excessive Variability; March 17, 1998.
3.
Siemens Power Corporation letter NRC:98:026, James F. Mallay to NRC (DCD),
ATTN: Chief, Planning, Program and Management Support Branch: 10 CFR Part 21 Evaluation and Notification for RELAP4 Excessive Variability; May 1, 1998.
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