ML20126D792

Fulfills 30 Day Reporting Requirement of 10CFR50.46(a)(3)(ii) for Small Break LOCA Analysis for Facilities

ML20126D792
Person / Time
Site:	Byron, Braidwood
Issue date:	12/22/1992
From:	Jackson M COMMONWEALTH EDISON CO.
To:	Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
NUDOCS 9212280163
Download: ML20126D792 (6)

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, i 1ENpi"sMaY D:c:mber 22,1992 y Downers Grove, minois 6051b Dr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 ATTN: Dccument Control Desk

Subject:

Byron Nuclear Power Station Units 1 and 2 Braldwood Nuclear Power Station Units 1 and 2 ECCS Evaluation Model Changes NBolocke1NosR-45_4mS&455mSE45 Land _50 45Z

Reference:

1. Byron Station Units 1 and 2, Braldwood Station Units 1 and 2 Updated Final Safety Analysis Report updated to December,1991.

2. Letter, M. A. Jackson to T. E. Murley (NRC) dated July 25,1992.

3. Letter, B. S. Humphries (Westinghouse) to Dr. T. A. Rieck,

" Commonwealth Edison Companies, Byron /Braidwood Stations Small Break LOCA SI Spilling Line Assum ation Error," November 23,1992, Westinghouse Letter Number E NSL OPL-l 92 588 Dr. Murley:

This letter fulfills the 30 day reporting requirement of 10CFR50.46(a)(3)(ll) for the analysis for Byron and Braidwood Small Break Nuclear Power LossinofReference stations, Coolant Accident (SBLOCA) house notified Comm

3. Westing that an error in the Byron /Braidwood NOTRUMP SBLOCA analysis for VANTAGE 5 fuel (Reference 1) had been identified. Incorrect safety injection data for the CCP was inadvertently used. The Westinghouse Centrifugal standard SBLOCA Charging methodoPump (logy a)ssumes that the Si line attached to the brok

, cold leg spills (no credit for injection flow . For break sizes which are smaller than the Si line diameter, the Siis assumed to sp)ll to RCS pmssure; however, if the break is greater than or equal to the Si line size, the Si is postulated to spill to containment 3ressure. The Byron /Braldwood SBLOCA analysis includes break sizes ranging from 2 nches to 6 inches In diameter. Since these breaks are larger than the CCP Si line (1.5 inch diameter), the analysis should hava used CCP data with one lina spillin9 to containment pressure; however, the analysis used CCP data with one line spilling to

RCS pressure.

An evaluation has been completed to estimate the effect of this error. The change in Peak Cladding Temperature (PCT) due to the error is estimated to be 166.5 F for the 3 inch limiting break. This penalty is in addition to the 20*F penalty assigned for the CCP Technical Specification change evaluation reported in Reference

2. Furthermore, an evaluation was performed which demonstrated that the 3-inch break would remain the limiting break.

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2-Additionally, a 5*F penalty has been assigned to SBLOCA as a result of the increased uncertainty of the pressurizer pressure initial condition during Economic Generation Control (EGC) operation. Westinghouse has performed plant specific evaluations for Byron and Braidwood and have quantified the varlability of automatic reactor control systems parameters. Pressurizer pressure and level and reactor average temperature experience wider variations than were assumed in the original SBLOCA analysis. The 5'F penalty conservatively bounds the effects of EGC operation.

A 0.1"F penalty has been assigned to the SBLOCA results for Braldwood Unit 2 due to the reconstitution of fuel assembly T48X (Braidwood Unit 2 Cycle 3). One fuel rodlet has been removed, and has been replaced by a stalnless steel rod.

The not SBLOCA PCT for the Byron /Braidwood Stations remains below 1700'F, including the effects of all previous evaluations and the evaluation of the effect of Economic Generation Control. Since continued compilance with the 10CFR50.4G(b) criteria has been shown, this is not considered to be a potontial safety issue, nor is it reportabic under 10CFR21. The APCT penalties for the charging pump flow reduction are based on results from the NOTRUM P model for Byron /Braidwood. Since the flow reductions have been erillcitly modeled using an NRC reviewed model, Commonwealth Edison c oes not plan to re perform SBLOCA analysis. Commonwealth Edison does not plan to issue another report pursuant to 10CFR50.46 until the next annual report or until another 50*F APCT penalty is accumulated.

Please direct any questions to this office.

Respectively, QY%U.

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hGeneric MarciaissuesA. Jackson Administrator Attachment cc: A. B. Davis - Regional Administrator, Region lll J. E. Dyer - PDill 2 Director, NRR R. Elliott - Braidwood Project Manager, NRR J. Hickman Byron Project Manager, NRR' Senior Resident Inspector - Byron Senior Resident inspector - Braldwood i

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' ATTACHMENT 1 3

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4 10CFR50.46  !

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. SMALL BREAK LOCA i

MARGIN UTILIZATION i s  :

1.  !

! BYRON AND ORAIDWOOD STATION.

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UNITS 1 and 2.

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ATTACHMENT 1 BYRON 1,2 SMALL BREAK LOCA 10CFR50.40 MARGIN UTILIZATION Page 1 of 3 PLANT NAME: BYRON.SIATION.UNIISl&2 UTILITY NAME: COMMONWEALIliEDISON__

A. ANALYSIS OF RECORD PCT._1A5311*F (Comments: Cale Note No._SEO SAlh3tZ3 00_

Evaluation Model: NOIRUME. FOT 2.50_, FdH.LOS, SGTP .1L%, Other:

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B. PRIOR LOCA MODEL ASSESSMENTS - 1989 oPCT.a_0'F (Permanent Assessment of PCT Margin - Letter #: CAE:902314LOCE90 309)

C. PRIOR LOCA MODEL ASSESSMENTS 1990 APCT.+ 0'F (Permanent Assessment of PCT Margin - Letter #: CAE91135/.QCE 91-136)

D. CURRENT LOCA MODEL ASSESSMSNTS - 06/1991 (Permanent Assessment of PCT Margin)

1. FUEL ROD INITIAL CONDITION INCONSISTEN0Y AP CT._+_3_7.'F E.10CFR50.59 SAFETY EVALUATIONS - (Permanent Assessment of PCT Margin)

None.

F. OTHER MARGIN ALLOCATIONS (Temporary Use of PCT Margin):

1. PLANT MARGINS USED: HHSLSUBLJNOTIL1) APCT. +_20'F

2. PLANT MARGINS USED: HHSLSPJLLfLOWlNOTE 2)_aPCT.3_160.5*F

3. PLANT MARGINS USED: EGO _REEBAT10NjNOIE.3)_aPCT. +_5*F LICENSING BASIS PCT + MARGIN ALLOCATION Net PCT.16816*F Notes:

1. A temporary PCT penalty of no more than 20'F was assessed by Westinghouse (SECL 90 015) in support of a potential change to the charging pump surveillance acceptance limit. This propc3ed change is still under review and has not yet been submitted for NRC approval. The SBLOCA penalty would result from a slight reduction in delivered SI under spilling line conditions between 1400 psia and 1000 psia RCS pressure.

2. A 166.5'F penalty has been assigned to the limiting break as a result of a modeling error related to the bac < pressure on the high pressure safety injection branch line associated with the ruptured cold leg.

3. A 5'F penalty has been assigned to small break LOCA as a result of the increased uncertainty of the pressurizer pressure initial condition during Economic i Generation Control (EGC) operation.

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. ATTACHMENT 1 BRAIDWOOD 1 SMALL BREAK LOCA 10CFR50.46 MARGIN UTILIZATION Page 2 of 3 PLANT NAME: DBAlQWQQD_SIATION.UMlI 1 UTILITY NAME: GOMMONWEALIH_ERJSON A. ANALYSIS OF RECORD APCT. 1453d*F '

(Comments: Calc Noto No._SEC:SAll 3173:00 Evaluation Model: NOIBUldE, FOT.210_, FdH.j 05,

' SGTP ._15__%, Other: _ )

B. PRIOR LOCA MODEL ASSESSMENTS 1989 6 PCT. + 0*F (Permanent Assessment of PCT Margin Letter #: GCE90:309 i C. PRIOR LOCA MODEL ASSESSMENTS 1990 oP CT._+_ S*F (Permanent Assessment of PCT Margin Letter #: GCEd1130 )

D. CURRENT LOCA MODEL ASSESSMENTS 06/1991 (Permanent Assessment of PCT Margin)

1. FUEL ROD INillAL CONDITION :NCONSISTENCY 6 PCT.+ 3Z*F E.10CFR50.59 SAFETY EVALUATIONS - (Permanent Assessment

1. Letter: SECL-91-L68Q lssue: MISSINGtGBlD PIECE APCT.3of PCT17-Margin)F F. 1.OTHER PLANT MARGIN MARGINSALLOCATIONS (Temporary Use of PCT6 Margin) PCT. +_._20 F USED: HHSLSURVJNQIE_1)

2. PLANT MARGINS USED: HHSLSElLL_ELQW 6 PCT.3_1GS,5'F

3. FUEL MARGINS USED: N/A APCT. *F

4. PLANT MARGINS USED: EGC_OEEBATJON_(NQTES) 6 PCT. + 5'F

'f LICENSING BASIS PCT + MARGIN ALLOCATION Net PCT =l698,6*F Notes:

1. A temporary PCT per ly of no more than 20*F was assessed by Westinghouse (SECL 90 015) in sur. 1 of a potential change to the charging pump surveillance acceptance limit. This proposed change is still under review and has not yet been submitted for NRC approval. The SBLOCA penalty would result from a slight reduction in delivered SI under spilling line conditions between 1400 psia and 1000 psia RCS pressure.

2. A 166.5'F penalty has been assigned to the limiting break as a result of a modeling error related to the back pressure on the high pressure safety injection branch line associated with the ruptured cold leg.

3. A 5*F penalty has been assigned to small break LOCA as a result of the increased uncertainty of the pressurizer pressure Initial condition during Economic Load Control (EGC) operation.

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BRAIDWOOD 2 SMALL BREAK LOCA 10CFR50.46 MARGIN UTILIZATION Page 3 of 3 PLANT NAME: BBAID_ WOOD _SIAllORUNlI.2 UTILITY NAME: COMM_QNWEALILLEDlSON i A. ANALYSIS OF RECORD PCT._L453d*F (Comments: Cale Note No._ SEQ SAll-31Z3 D0

. Evaluation Model: NOIBU.ME, FOT.L51. FdH.L65, l SGTP .15_ %, Other: )

D. PRIOR LOCA MODEL ASSESSMENTS 1989 APCT.3 0'F l

(Permanent Assessment of PCT Margin Letter #: CAE 90 314/CCEa0 3091 C. PRIOR LOCA MODEL ASSESSMENTS - 1990 APCT.+ 0*F (Permanent Assessment of PCT Margin Letter #: CAE 91-135/CCE 91130)

D. CURRENT LOCA MODEL ASSESSMENTS - 06/1991 (Permanent Assessment of PCT Margin)

1. FUEL ROD INITIAL CONDITION INCONSISTENCY APCT.3__32*F E.10CFR50.59 SAFETY EVALUATIONS -(Permanent Assessment of PCT Margin)

None.

F. OTHER

1. PLANTMARGINMARGINS ALLOCATIONS USED: HH. SLSUBL (Tem >orary(NOTEl)Use of PCT Margin):

APCT.3__20*F

2. PLANT MARGINS USED: HHSLSEILLELOWJNOIE 2) APCT.al6.615'F

3. FUEL MARGINS USED: BERONSIlIUIlOR(NOIE 41 APCT. + Od*F

4. PLANT MARGINS USED: EGG _DEEBAILON_(NOTE 3) APCT. + 5'F j LICENSING BASIS PCT + MARGIN ALLOCATION Net PCT =1681Z'F i

Noles:

l 1. A temporary PCT penalty of no more than 20*F was assessed by Westinghouse (SECL 90 015) in support of a potential change to the charging pump surveillance acceptance limit. This proposed change is still under review and has not yet been i

i submitted for NRC approval. The SBLOCA penalty would result from a slight reduction in delivered SI under spilling line conditions between 1400 psia and 1000 psia RCS pressure.

2. A 166.5'F penalty has been assigned to the limiting break as a result of a

modeling error related to the back pressure on the high pressure safety injection branch line associated with the ruptured cold leg.

3. A 5*F penalty has been assigned to small break LOCA as a result of the increased uncertainty of the pressurizer pressure initial condition during Economic i Generation Control (EGC) operation.

4. A 0.1*F penalty has been assigned to the SBLOCA results for Braidwood

Unit 2 due to the reconstitution of fuel assembly T48X. -One fuel rodlet has been-removed, and has been replaced by a stainless steel rod.

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