ML17229A654

Forwards Summary of Results of Any Change to or Error Discovered in Evaluation Models for Eccs,Or Application of Such Models,That Affect Fuel Cladding Temp Calculation.Info Submitted Per 10CFR50.46(a)(3)(ii)

ML17229A654
Person / Time
Site:	Saint Lucie
Issue date:	03/04/1998
From:	Stall J FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-98-057, L-98-57, NUDOCS 9803100326
Download: ML17229A654 (6)

Text

CATEGORY 1 REGULAT Y INFORMATION DISTRIBUTIO SYSTEM (RIDS)

P

ACCESSION NB/:9803100326 DOC.DATE: 98/03/04 NOTARIZED: NO DOCKET ¹

'FACIL:50-335 St. Lucie Plant, Unit 1, Florida Power 6 Light Co. 05000335 "50-389 St. Lucie Plant, Unit 2, Florida'ower S Light Co. 05000389 AUTH. NAME AUTHOR AFFILIATION STALL,J.A. Florida Power S Light Co.

RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Forwards summary of results of any change to or error discovered in evaluation models for ECCS,or application of such models, that affect fuel cladding temp calculation. Info A submitted per 10CFR50.46(a)(3)(ii).

DISTRIBUTION CODE: A001D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: OR Submittal: General Distribution E NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-3 LA 1 1 PD2-3 PD 1 1 R GLEAVES,W 1 1 INTERNAL: ACRS 1 1 FI E CE 1 1 NRR/DE/ECGB/A 1 1 NRR DE EMCB 1 1 NRR/DRCH/HICB 1 1 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 NUDOCS-ABSTRACT 1 1 OGC/HDS3 1 0 EXTERNAL:.'NOAC 1 1 NRC PDR 1 1 D

E NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE. TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION LISTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTROL DESK (DCD) ON EXTENSION 415-2083 TOTAL NUMBER OF COPIES REQUIRED: LTTR 14 ENCL 13

Florida Power 5 Light Company, 6351 S. Ocean Drive, Jensen Beach, FL34957 March 4, 1998 FPL L-98-057'0 CFR 50.46 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Re: St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 Acceptance Criteria for Emergency Core Cooling Systems for Light Water Nuclear Power Reactors:

10 CFR 50.46 Annual Re ort Pursuant to 10 CFR 50.46(a)(3)(ii), the nature of any change to or error discovered in the evaluation models for Emergency Core Cooling Systems (ECCS), or in the application of such models, that affect the fuel cladding temperature calculations for St. Lucie Units 1 and 2 is reported in the attachment to this letter. The estimated eFect from any such change or error on the limiting ECCS analysis for each unit is also addressed. The data interval for the report is from January 1 through December 31, 1997.

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 9803'i0032 05000335 PDR ADQCK PDR P

lllllllllilllllllllllllllllllllllllllll an FPL Group company

St. Lucie Units 1 and 2 L-98-057 Docket Nos. 50-335 and 50-389 ATTACHMENT 10 CFR 50.46 Annual Re ort Page 1 of 3 Emergency core cooling system (ECCS) analyses for St. Lucie Unit 1 and St. Lucie Unit 2 are performed by Siemens Power Corporation (SPC) and Asea Brown Boveri-Combustion Engineering (ABB-CE), respectively. The following information pertaining to the evaluation models for small break loss of coolant accidents (SBLOCA) and large break loss of coolant accidents (LBLOCA), and the application of such models to each St. Lucie unit, is provided pursuant to 10 CFR 50.46(a)(3)(ii).

A summary of calculated peak cladding temperature (PCT) changes is provided in Table 1. The data interval for this report is from January 1 through December 31, 1997.

1. ST. LUCIE UNIT 1 SBLOCA: A change was made to the evaluation model assumptions involving high pressure safety injection (HPSI) flow asymmetry. Re-evaluation of SBLOCA using the revised HPSI flow asymmetry identified a new limiting break size of 0.05 ft~, and resulted in a PCT increase of 149 'F (previously reported in Reference 3.1). The calculated PCT for the limiting SBLOCA is 1953 'F.

LBLOCA: A Z-equivalent model discrepancy, which was reported in the 1996 Annual Report (Reference 3.2), was corrected and explicitly evaluated for the Unit 1 LBLOCAanalysis of record.

The impact &om this error had been conservatively estimated as a maximum PCT increase of 15 'F.

Following correction of the discrepancy, the actual change in calculated PCT is -1.0 'F. The evaluation model was also updated to conservatively use the minimum containment spray and fan cooler initiation time. This change resulted in a 14 'F PCT increase. The combination of revisions to the Z-equivalent model and the minimum containment spray and fan cooler initiation time yields a calculated PCT of 2040 'F for the limiting LBLOCA.

SPC also identified a variability in RELAP-4 code results that may affect the pe'ak cladding temperature calculated in LBLOCAanalyses. The variability is characterized as a large change in the code output result that is produced by small changes in the code input, and for which significantly large changes should not be expected when considering physical behavior. SPC is assessing the cause(s) and impact of this deviation (Reference 3.3). A preliminary assessment indicates that the effect on calculated PCT is not significant and that the St. Lucie Unit 1 LBLOCA analysis of record remains in compliance with acceptance criteria of 10 CFR 50.46. Corrective actions have not been finalized and quantified results are not expected to be available until later in 1998.

St. Lucie Units 1 and 2 L-98-057 Docket Nos. 50-335 and 50-389 ATTACHMENT 10 CFR 50.46 Annual Re ort Page 2 of 3

2. ST. LUCIE UNIT 2 General: The ECCS performance analysis computer codes for SBLOCA and LBLOCA were converted for use on Hewlett Packard (HP) workstations oper'ating under the HP/UX operating system. The codes were previously used with HP Apollo workstations under the Domain operating system, and the overall impact of the conversion is estimated to have no effect on the calculated PCT (to the precision of printed results, i.e., less than .01 'F). In addition to the computer platform change, an option was added to the SBLOCA methods which automates the transfer of data (core boundary conditions) between the CEFLASH-4AS blowdown hydraulics computer code and the PARCH hot rod heatup code. Previously, this data transfer was performed manually. The automated process provides a more accurate and eAicient method of transferring the data, and the effect on the ECCS performance analysis for SBLOCA is estimated to be a reduction in calculated PCT of approximately 4 'F. The limiting ECCS analyses of record have not been performed with the changes described above.

SBLOCA: No errors were found in the SBLOCA analysis for this reporting period. The peak cladding temperature for the analysis of record remains at 1915 'F.

LBLOCA: An error was discovered and corrected in the decay heat energy redistribution factor (ERF) used in the ECCS performance evaluation model for LBLOCA. The impact on calculated peak cladding temperature was conservatively estimated and previously reported in Reference 3.4.

Correcting the ERF error resulted in a 28 'F increase, and the limiting ECCS analysis PCT is 2171 'F.

3. REFERENCES

1. FPL Letter L-97-313, J.A. Stall to USNRC (DCD), "Error in the Application of SBLOCA Evaluation Model; 30 Day, 10 CFR 50.46 Report:" December 17, 1997.

2. FPL Letter L-97-034, J.A. Stall to USNRC (DCD), "Acceptance Criteria for Emergency Core Cooling Systems for Light Water Nuclear Power Reactors: 10 CFR 50.46 Annual Report:"

March 6, 1997.

3. SPC Letter NRC:98:001, J.S. Holm to USNRC, "Interim Report of Evaluation of a Deviation Pursuant to 10 CFR 21.21(a)(2):" January 15, 1998.

4. FPL Letter L-97-205, J.A. Stall to USNRC (DCD), "Error in the Use of LBLOCAEvaluation Model; 30 Day 10 CFR 50.46 Report:" August 8, 1997.

St. Lucie Units 1 and 2 L-98-057 Docket Nos. 50-335 and 50-389 ATTACHMENT 10 FR 50 46 Annual Re ort Page3 of 3 Table I St. Lucie Units 1 and 2 1997 SBLOCA and LBLOCAPCT Summary Unit 1 SBLOCA Summa PCT 1996 10 CFR 50.46 Annual Re ort note 1 1765 'F Chan edueto30% SGtube lu in anal sis note2 +39 'F Chan e due to revised HPSI flow as mmet +149 'F 1997 10 CFR 50.46 Annual Re ort 1953 'F Unit 1 LBLOCA Summa 1996 10 CFR 50.46 Annual Re ort 2027 'F Z-e uivalent error enalt estimated maximum im act on PCT +15 'F Chan e followin correction of Z-e uivalent error -1 'F Chan e due to revised containment s ra and fan cooler minimum dela time +14 'F 1997 10 CFR 50.46 Annual Re ort 2040 'F Unit 2 SBLOCA Summa PCT 1996 10 CFR 50.46 Annual Re ort 1915 'F Chan e durin 1997 0'F 1997 10 CFR 50.46 Annual Re ort 1915 'F Unit 2 LBLOCA Summa PCT 1996 10 CFR 50.46 Annual Re ort 2143 'F ERF error enalt estimated maximum im act on PCT +30 'F Chan e followin correction of ERF error +28 'F 1997 10 CFR 50.46 Annual Re ort 2171 'F Notes: (1) Calculated peak cladding tcmpcraturc is for stcam generator (SG) tube plugging level of 25%.

(2) Analysis was performed in 1996, but did not bccomc analysis of record until issuance of Amendmcnt No. 151 (5/16/97) to thc facility operating license. Thc value is included in this table to identify components contributing to thc cumulative impact on 1997 PCT of record.