ML20151V433

Informs of Input Error in Limiting Small Break LOCA Analyses Submitted to & Approved by NRC for Jm Farley Plant,Units 1 & 2 Power Uprates.Error Is Reported IAW 10CFR50.56,since Absolute Value of Error Is in Excess of 50 F

ML20151V433
Person / Time
Site:	Farley
Issue date:	09/10/1998
From:	Dennis Morey SOUTHERN NUCLEAR OPERATING CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9809140309
Download: ML20151V433 (6)

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Dave Morey Southern Nucl:ar I

, Vice President Optrating Comp ny '

farley ProDet RO. Box 1295 Birmingham. Alabama 35201 Tel 205.992.5131

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! september 10, 1998 l SOUTHERN h COMPANY Docket Nos.: 50-348 50-364 10 CFR 50.46 i U. S. Nnclear Regulatory Commission A'ITN: Document Control Desk Washington, DC 20555 4

Joseph M. Farley Nuclear Plant Unrate Peak Clad Temperature (PCT) Calculation Error Ladies and Gentlemen:

1 Southern Nuclear was recently informed of an input error in the limiting small break loss of I cooling accident (SBLOCA) analyses submitted to and approved by the NRC for the Farley i Nuclear Plant Units 1 and 2 power uprates. This error is reported in accordance with 10 CFR 50.46 since the absolute value of the error is in excess of 50 *F.

RCS mass flow rate calculated for the high Tavg case was used in the limiting low Tavg case afTecting calculated PCTs. Although the error resulted in a PCT reduction, the absolute values i of the changes resulting from the errors are 75 *F for Unit I and 87 'F for Unit 2. Accordingly, l Southern Nuclear has determined that the above changes constitute significant errors in the  !

limiting SBLOCA analyses done for uprate for both Farley units and are reportable under 10 1 CFR 50.46. In addition, On February 27,1998, Westinghouse reported a 30 F assessment l

, resulting from a clad burst strain error discovered in the limiting SBLOCA analysis. The error was applica' ole to the Burst and Blockage / Time in Life and was being tracked for reporting as part of the 199810 CFR 50.46 annual report. To account for this error a new Burst and Blockage assessment was performed resulting in an increased penalty. The effects of the above errors resulted in an overall calculated PCT increase. Additional detail is provided in ,

a:tachments I and 2. I As a result of the RCS mass flow error, the low Tavg cases are no longer limiting. The high Tavg SBLOCA analyses for uprate now provide the highest PCTs and therefore provide the limiting SBLOCA PCTs. The reported limiting high Tavg PCT includes resolution of the clad i burst strain error. These values are given in Attachment 1; therefore the reanalysis is complete.

4 Compliance with the requirements of 10 CFR 50.46 continues to be maintained for Farley Units ,

I and 2. This submittal contains no NRC commitments. 1 a ,, ,s ,

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I U. S. Nuclear Regulatory Commission Page 2 Should you have any questions or concerns regarding this matter, please contact this office.

Respectfully submitted, SOUTHERN NUCLEAR OPERATING COMPANY Dave Morey j

EWC/maf sigrrevl. doc Attachments l l

cc: Mr. L. A. Reyes, Region II Administrator l Mr. J. I. Zimmerman, NRR Project Manager Mr. T. P. Johnson, FNP Sr. Resident Inspector l

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ATTACHMENT 1 JOSEPH M. FARLEY NUCLEAR PLANT- UNITS 1 AND 2 !

TOTAL RESULTANT SMALL-BREAK LOCA PCTS ( F) i 1

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2 ATTACHMENT 1 JOSEPH M. FARLEY NUCLEAR PLANT- UNITS 1 AND 2 TOTAL RESULTANT SMALL-BREAK LOCA PCTS ( F)

UNIT 1. *F UNIT 2. *F A. ANALYSIS OF RECORD (VANTAGE 5)

1. ECCS Analysis,HighTavg 1923* 1891*

2. Burst and Blockage / Time in Life 79** 61**

Total Analysis of Record PCT = 2002 1952 B. 10 CFR 50.46 MODEL ASSESSMENTS

1. Prior Reported Assessments 0 0 '

2. Change in Burst and Blockage / Time in Life 0 0 C. 10 CFR 50.59 PLANT MODIFICATIONS Annular pellets on the top 6" ofIFBAs in 0 10 Unit 2 Cycle 13.- -

r D. TOTAL RESULTANT SMALL-BREAK LOCA PCT 2002 1962

• - Existing high Tavg SBLOCA analysis results which were reviewed and approved by the NRC '

as part of the Farley Nuclear Plant Power Uprate package. These uprate SBLOCA analysis results replace entirely the previous non-uprated results last reported in the 199710 CFR 50.46 annual report.

• • Burst and Blockage /fime in Life was determined with SPIKE. This assessment was not evaluated for the high Tavg cases as given in Reference I because they were not the limiting cases. For Unit 2, the Burst and Blockage /Fime in Life reflects the effects of a 10 F penalty in the base PCT due to annular pellets being implemented in the uprated Cycle 13.

Reference 1: Memorandum from J. I. Zimmerman (N'IC) to D. N. Morey (SNC), " Issuance of Amendments - Joseph M. Farley Nuclear Plant Units I and 2 (TAC Nos. M98120 and M98121)," April 29,1998.

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ATTACliMENT 2 DISCUSSION OF SMALL-BREAK LOCA MODEL ERRORS AND CHANGES i

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1 DISCUSSION OF SMALL-BREAK LOCA MODEL ERRORS AND CHANGES I

i NOTRUMP Input Error - R_CS# ass Flow Rate Error for Low Tave Cases I

{ During the ongoing steam generator replacement (SGR) SBLOCA analysis, an inadvertent input 4

error concerning the RCS mass flow was discovered in the NRC approved limiting uprate

! SBLOCA analysis. The error occurred in the SPADES run used to set up the NOTRUMP input i decks for the limiting low Tavg cases. An RCS flow of 27,078 lbm/sec was assumed for the j Farley Units 1 and 2 low Tavg and high Tavg steady-state runs. However, the above RCS mass

flow was correct for the high Tavg cases and incorrect for the low Tavg cases since the

! corresponding low Tavg density correction was not included. Thus, the high Tavg cases are not

afTected by the above error and they remain valid.

i l The corrected low Tavg RCS mass flow would have been 27,878 lbm/sec. A reanalysis of the low Tavg SBLOCA cases with the corrected RCS mass Gow resulted in a change in base PCT of l- -75 F for Unit I and -87 *F for Unit 2, prompting SNC to issue this significant error report. The .

l above reductions in PCTs for the low Tavg cases result in the existing high Tavg cases becoming l the limiting uprate SBLOCA analysis for both units. Attachment I shows the limiting uprate ,

SBLOCA analysis PCTs coaresponding to the high Tavg cases for both Units 1 and 2. )

It is noted that the above error occurred in the power uprate SBLOCA analysis only. The current l

j. Unit 2 Cycle 13 is operating at the uprated power and Unit I will be uprated during Cycle 16 j j scheduled for December,1998. Thus, the currently operating Unit 1 Cycle 15 at the non-uprated ,

power is not affected. However, the error is reported for both units at this time for completeness.

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It is noted that on February 27,1998, Westinghouse reported a 30 'F assessment resulting from a SBLOCTA clad burst strain error discovered in the limiting uprate SBLOCA analysis that was

part of the NRC approved power uprate license amendment (see Reference 1 in Attachment 1) for j Farley Nuclear Plant. The SBLOCTA error was applicable to the Burst and Blockage / Time in  :

i Life assessment that was applied only to the most limiting uprate SBLOCA analysis (i.e., low -

Tavg of Unit 1). This error was being tracked for reporting as part of the 199810 CFR 50.46 l annual report. The Burst and Blockagerfime in Life penalties shown in Attachment I were

determined using SPIKE instead of SBLOCTA and, as such, are not subject to the SBLOCTA t

clad burst strain error discussed above.

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