RC-97-0120, Forwards Annual 1996 ECCS Evaluation Model Revs Rept Which Requires Licensees to Notify NRC on Annual Basis of Corrections to or Changes in ECCS Evaluation Models,Per 10CFR50.46

Forwards Annual 1996 ECCS Evaluation Model Revs Rept Which Requires Licensees to Notify NRC on Annual Basis of Corrections to or Changes in ECCS Evaluation Models,Per 10CFR50.46

ML20148J423
Person / Time
Site:	Summer
Issue date:	06/06/1997
From:	Gabe Taylor SOUTH CAROLINA ELECTRIC & GAS CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
RC-97-0120, RC-97-120, NUDOCS 9706170140
Download: ML20148J423 (10)

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. 10CFR50.46

• Sout ar tina Electric & G:s Company J.T Jenkinsvihe, SC 29065 Nuclear Operations I (803) 3454 344 l SCE8Ci saanamamwr June 6,1997 1 RC-97-0120 l I

Document Control Desk l U. S. Nuclear Regulatory Commission Washington, DC 20555 i l Gentlemen:

Subject:

VIRGIL C. SUMMER NUCLEAR STATION DOCKET NO. 50/395 OPERATING LICENSE NO. NPF-12 ECCS EVALUATION MODEL REVISIONS REPORT (ANN 2300)

Attached is the annual (1996) Emergency Core Cooling System (ECCS) Evaluation l Model Revisions Report for the Virgil C. Summer Nuclear Station (VCSNS). This report is being submitted pursuant to 10CFR50.46, which requires licensees to notify the NRC.

on at least an annual basis of corrections to or changes in the ECCS Evaluation l Models. I I declare that the statements and matters set forth herein are true and correct to the best of my knowledge, information, and belief.

If you have any questions, please call Mr. Michael J. Zaccone at (803) 345-4328.

L Very ruly yours, '

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l MJZ/GJT l Attachment J'7 c: J. L. Skolds NRC Resident inspector R. R. Mahan (w/o att.) W. F. Conway J. B. Knotts, Jr. NSRC l R. J. Winite DMS (RC-97-0120)

L. A. Reyes RTS (ANN 2300) j A. R. Johnson File (813.12-4, 818.02-17) l!llllllllll(llllllllllllllllll!llll!lll

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m NUCLEAR EXCELLENCE - A SUMMER TRADITION!

l 9706170140 970606 PDR ADOCK 05000395

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, Docum:nt Control Desk ANN 2300 RC197-0120 Page 2 of 2 STATE OF SOUTH CAROLINA  :

TO WIT :

COUNTY OF FAIRFIELD  :

I hereby certify that on the & d of L 19h before me, the subscriber, ,

a Notary Public of the State of South arolina personally appeared Gary J. Taylor, being duly sworn, and states that he is Vice President, Nuclear Operations of the South Carolina Electric & Gas Company, a corporation of the State of South Carolina, that he provides the foregoing response for the puraoses therein set forth, that the statements made are true and correct to the best of his mowledge, information, and belief, and that he was authorized to provide the response on behalf of said Corporation, i i

WITNESS my Hand and Notarial Seal d// j NotarfPublic '

My Commission Expires eC =in EdesJu!v13,20:i Date l

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e CHANGES TO THE WESTINGHOUSE ECCS EVALUATION MODELS INTRODUCTION Provisions in 10 CFR 50.46 require the annual reporting of corrections to or changes in the ECCS Evaluation Model (EM) approved for use in performing safety analyses for the Loss of Coolant Accident (LOCA). This report describes corrections and revisions to the Westinghouse ECCS EM which are applicable to the V. C. Summer Nuclear Station (VCSNS). The current approved Westinghouse ECCS ems are listed in Table 1 and consist of several computer codes with specific functions.

Westinghouse has completed the evaluation of several items related to the Westinghouse ECCS EM listed in Table 1. Each of these items is discussed in Table 2, which includes a description of the item, the assessment which was performed, the resulting change to the EM, and the effect of the change on the Peak Clad Temperature (PCT).

Tables 3 and 4 summarize the changes or corrections in the ECCS Evaluation Model since the last notification and the associated change in the peak clad temperature (PCT). None of the model changes were considered significant under 10 CFR 50.46.

Table 5 summarizes the changes made to the ECCS Evaluation Model since the last notification under 10 CFR 50.59. There was no effect on PCT due to these i evaluations.

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l TABLE 1

SUMMARY

OF WESTINGHOUSE ECCS EVALUATION MODELS FOR VCSNS 1

NAME: 1981 MODEL WITH BASH APPLICATION: Analysis of Large Break LOCA CODES USED: PURPOSE. i SATAN-VI Blowdown hydraulic transient BASH Reflood hydraulic transient l LOCBART Hot assembly thermohydraulics and fuel rod thermal transient

WREFLOOD/ COCO /LOTIC Containment pressure transient 1

NAME: 1985 SBLOCA MODEL l APPLICATION: Analysis of Small Break LOCA CODES USED: PURPOSE:

! NOTRUMP System Hydraulic transient SBLOCTA Fuel rod thermal transient l

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TABLE 2 l

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l CHANGES OR CORRECTIONS TO THE VIRGIL C. SUMMER l NUCLEAR STATION ECCS EVALUATION MODELS NOT PREVIOUSLY REPORTED i

l SBLOCTA Fuel Rod initialization l Translation of Fluid Conditions from SATAN to LOCTA l

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SE.LOCTA Fuel Rod initialization -

Mected Evaluation Model 1985 Westinghouse Small Break LOCA Evaluation Model Using NOTRUMP Backaround An error was discovered in the SBl.OCTA code related to adjustments which are made as part of the fuel rod initialization process which is used to obtain agreement between the SBLOCTA model and the fuel data supplied from the fuel thermal-hydraulic design calculations at full power, steady-state conditions. Specifically, an adjustment to the  :

power, which is made to compensate for adjustments to the assumed pellet diameter l was incorrect. Additionally, updates were made to the fuel rod creep and strain model  ;

to correct logic errors that could occur in certain transient conditions. These model i revisions also had a small effect on the fuel rod initialization process, and can produce  ;

small effects during the transient. Due to the small magnitude of effects, and the .

interaction between the two items, they are being evaluated as a single, closely related )

effect.  !

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This change is considered to be a Non-Discretionary Change as described in WCAP-13451, Estimated Effect Representative plant calculations with the corrected model demonstrated that these revisions result in a predicted peak clad temperature increase of +10* F.

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Translation of Fluid Conditions from SATAN to LOCTA Affected Evaluation Model 1981 Westinghouse Large Break LOCA Evaluation Model Using BASH Backoround An error was discovered in the coding related to the translation of fluid conditions between the SATAN blowdown hydraulics code and the LOCTA code used for subchannel analysis of the fuel rods. In performing axialinterpolations to translate the SATAN fluid conditions into the mesh nodalization used by the LOCTA code, the length of the lower core channel fluid connection to the lower plenum node was incorrectly calculated.

Estimated Effect Representative plant calculations with the corrected model resulted in approximately a 115'F effect on the BASH large break LOCA evaluation model. Therefore, a +15*F penalty has been assigned to the BASH large break LOCA evaluation model.

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Table 3 Small Break Peak Clad Temperature Margin Utilization Revision Date: 02/10/97 Plant Name: Virgil C. Summer Eval. Model: NOTRUMP Fuel: Vantage +

Utility Name: South Carolina Electric & Gas FO-2.45 FAH-1.62 SGTP-10%

Reference

• Clad Temperature Notes J A. CURRENT ANALYSIS OF RECORD (2/94) 2 PCT- 1823'F 1 B. ~ PRIOR PERMANENT ECCS MODEL 1 APCT= 97'F ASSESSMENTS

! C. 10 CFR 50.59 SAFETY EVALUATIONS Table 5-A APCT- O'F D. 199610 CFR 50.46 MODEL ASSESSMENTS (Permanent Assessment of PCT Margin)

1. SBLOCTA Fuel Rod initialization Error 4 APCT- 10*F

, E. TEMPORARY ECCS MODEL ISSUES i

! 1. None APCT= 0'F F. OTHER MARGIN ALLOCATIONS ,

1. Burst and Blocka0e/ Time in Life APCT= 8G'F 2 l l

i LICENSING BASIS PCT + MARGIN ALLOCATIONS PCT = 2016'F l

• References for the Peak Clad Temperature Margin Utilization summary can be found in Table 5-B.

Notes:

1. AOR performed for core power . 2900 MWt and A75 steam generators.

l 2. This assessment is a function of base PCT plus permanent margin allocation and as such will increase / decrease with margin allocation changes.

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TABLE 4 Large Break Peak Clad Temperature Margin Utilization Revision Date: 02/10/97 Plant Name: Virgil C. Summer Eval. Model: BASH Fuel: Vantage +

Utility Name: South Carolina Electric & Gas FO-2.50 FAH-1.70 SGTP-10%

Reference

• Clad Temperature Notes A. CURRENT ANALYSIS OF RECORD (10/95) 3 PCT = 2099*F 1 B. PRIOR PERMANENT ECCS MODEL 1 APCT- O'F i

ASSESSMENTS C. 10 CFR 50.59 SAFETY EVALUATIONS Table 5-A APCT- 0*F D. 199610 CFR 50.46 MODEL ASSESSMENTS (Permanent Assessment of PCT Margin)

1. Translation of Fluid Conditions from SATAN to LOCTA APCT= 15'F E. TEMPORARY ECCS MODEL ISSUES

1. None APCT- 0*F F. OTHER MARGIN ALLOCATIONS

1. None APCT- 0*F l LICENSING BASIS PCT + MARGIN ALLOCATIONS PCT = 2114*F l

i References for the Peak Clad Temperature Margin Utilization summaries can be found in Table 5-B.

Notes:

1. AOR is for A75 steam generators and core power = 2900 MWt.100 psig IFBA fuel is non'-limiting

] compared to non-lFBA fuel for V. C. Summer.

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TABLE 5 TABLE A - 10 CFR 50.59 Safety Evaluations Plant Name: Virgil C. Summer Utility Name: South Carolina Electric & Gas Reference Clad Temperature Notes

1. SMALL BREAK ECCS SAFETY EVALUATIONS A. None APCT= 0*F TOTAL 10 CFR 50.59 SMALL BREAK ASSESSMENTS PCT = 0'F

11. LARGE BREAK ECCS SAFETY EVALUATIONS A. Fuel Reconstitution APCT- O'F TOTAL 10 CFR 50.59 LARGE BREAK ASSESSMENTS PCT = 0Y TABLE B - References

1. CGE-96-202, "10 CFR 50.46 Annual Notification and Reporting," February 9,1996.

2. CGE-93-0054-SGUL, "SECL-93-036, Rev.1," March 9,1994.

3. CGE-95-0009-SGUL, " Revised Large Break LOCA Results for Uprating Submittal," October 24, 1995.

4. CGE-96-213. " South Carolina Electric and Gas Company, Virgil C. Summer Station,10 CFR 50.46 Small Break LOCA Notification and Reporting," July 8,1996.

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