ML062480087

30-Day Report of Emergency Core Cooling System (ECCS) Model Changes Pursuant to the Requirements of 10 CFR 50.46

ML062480087
Person / Time
Site:	Kewaunee
Issue date:	09/01/2006
From:	Gerald Bichof Dominion Energy Kewaunee
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
06-681
Download: ML062480087 (7)

Text

1)ominion Energy Kewaunee, Inc.

7000 I h t n ~ n m n Roulcvard. G k n Allcn, VA 2iO60 September 1, 2006 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 p Dominion" Serial No.06-681 N L&OS/CS RO Docket Nos.

50-305 License Nos.

DPR-43 DOMINION ENERGY KEWAUNEE. INC.

KEWAUNEE POWER STATION 30-DAY REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 In accordance with 10 CFR 50.46(a)(3)(ii), Dominion Energy Kewaunee, Inc. (DEK),

hereby submits information regarding changes to the Westing house Emergency Core Cooling System (ECCS) Evaluation Model for the Best Estimate Large Break Loss of Coolant Accident (BE LBLOCA) analysis for Kewaunee Power Station (KPS) and its application in existing analyses. Attachment 1 provides a report describing evaluation model changes associated with the Westing house BE LBLOCA ECCS Evaluation Model for KPS.

Information regarding the effect of the ECCS evaluation model changes upon the reported BE LBLOCA analyses of record (AOR) results is provided for KPS in. To summarize the information in Attachment 2, the calculated peak cladding temperature (PCT) for the BE LBLOCA analyses for KPS is 2035°F. This result represents a significant change in PCT, as defined in 10 CFR 50.46(a)(3)(i).

The BE LBLOCA results for KPS are confirmed to have sufficient margin to the 2200°F limit of 10 CFR 50.46.

Based upon our evaluation of this information and the associated changes in the applicable licensing basis PCT results, no further action is required to demonstrate compliance with the 10 CFR 50.46 requirements.

This information satisfies the 30-day reporting requirements of 10 CFR 50.46(a)(3)(ii).

In addition, no reanalysis or other actions are necessary to demonstrate compliance with 10 CFR 50.46 requirements.

If you have any further questions regarding this submittal, please contact Mr. Craig Sly at (804) 273-2784.

Very truly yours,

&rald T. Bischof V Vice President - Nuclear Engineering

Serial Number 06-681 Docket Nos. 50-305 Page 2 of 2 Commitments made in this letter:

1. None.

Attachments:

1.

2.

cc:

Report of Changes in Westinghouse Best Estimate Large Break LOCA ECCS Evaluation Model - Kewaunee Power Station.

Reporting of 10 CFR 50.46 Margin Utilization - Westinghouse Best Estimate Large Break LOCA ECCS Evaluation Model - Kewaunee Power Station.

Administrator, Region U. S. Nuclear Regulatory Commission Region Ill 2443 Warrenville Road Suite 21 0 Lisle, Illinois 60532-4352 Mr. D. H. Jaffe Project Manager U.S. Nuclear Regulatory Commission Mail Stop 0-7-D-1 Washington, D. C. 20555 Mr. S. C. Burton NRC Senior Resident Inspector Kewaunee Power Station

ATTACHMENT 1 REPORT OF CHANGES IN WESTINGHOUSE BEST ESTIMATE LARGE BREAK LOCA ECCS EVALUATION MODEL KEWAUNEE POWER STATION DOMINION ENERGY KEWAUNEE, INC.

Serial Number 06-681 Page 1 of 2 REPORT OF CHANGES IN WESTINGHOUSE BEST ESTIMATE LARGE BREAK LOCA ECCS EVALUATION MODEL KEWAUNEE POWER STATION Identification of ECCS Evaluation Model Chanaes The current large break LOCA analysis for Kewaunee Power Station (Kewaunee) was performed using the Westinghouse Best Estimate LBLOCA Evaluation Model (BE LBLOCA) with application to PWRs with Upper Plenum Injection (UPI). Westinghouse identified two errorslchanges in this model and provided the results of assessments to determine the impact on PCT.

The two errorslchanges are summarized below.

1.

Inconsistent Vessel Vertical Level Modelinq Westinghouse identified a discrepancy during the course of a BE LBLOCA analysis whereby the number of vertical levels in the vessel are modeled inconsistent with the analysis input guidelines. An assessment was performed to estimate the impact of these differences on the BE LBLOCA results for the affected plants. This assessment concluded that there is no significant impact on the BE LBLOCA analysis results due to the lnconsistent Vessel Vertical Level Modeling, leading to an estimated impact on PCT of APCT=O°F for Kewaunee.

2.

Revised Downcomer G ~ D ln~uts Westinghouse identified an error during the course of a Westinghouse BE LBLOCA Evaluation Model analysis. A factor of l/z had been missed from the downcomer nominal gap width (GAPN) calculations from the Kewaunee analysis, resulting in downcomer GAPN values twice as big as they should be.

The error has been corrected and a representative steady state and transient rerun was performed using WCOBRA/TRAC to quantify the effect on PCT. The estimated effect on PCT due to the Revised Downcomer Gap Inputs was determined to be APCT= -59°F for Kewaunee.

Serial Number 06-681 Page 2 of 2 Conclusion Dominion has performed an evaluation of PCT for comparison to 10 CFR 50.46 requirements. The Analysis of Record PCT is 2084°F.

Considering the current PCT changes as well as all previously reported changes, the corrected BE LBLOCA PCT is 2035°F. The Kewaunee Power Station BE LBLOCA results have sufficient margin to the 2200°F limit specified in 10 CFR 50.46(b)(I).

The PCT assessments for 10 CFR 50.46(a)(3)(i) accumulation are greater than the 50°F limit for reporting; hence, the changes are significant and submittal of this 30-day report to the NRC is required.

ATTACHMENT 2 REPORTING OF 10 CFR 50.46 MARGIN UTILIZATION WESTINGHOUSE BEST ESTIMATE LARGE BREAK LOCA ECCS EVALUATION MODEL KEWAUNEE POWER STATION DOMINION ENERGY KEWAUNEE, INC.

Serial Number 06-681 Page 1 of 1 10 CFR 50.46 Margin Utilization - Best Estimate LBLOCA Plant Name:

Kewaunee Power Station Utility Name:

Dominion Energy Kewaunee, Inc.

Analvsis Information EM:

U PI (1 999)

Limiting Break Size:

Split Analysis Date:

03/25/02 Vendor:

Westing house FQ:

2.5 FdH:

1.8 Fuel:

422 Vantage +

SGTP(%):

10 Notes:

Uprate to 1772 MWt. Effective beginning Cycle 26 Clad Temp (OF)

LICENSING BASIS Analysis of Record PCT 2084 PCT ASSESSMENTS (Delta PCT)

A.

Prior ECCS Model Assessments

1.

Revised Blowdown Heatup Uncertainty Distribution 5

2.

Spacer Grid Heat Transfer Model Inputs 5

B.

Planned Plant Modification Evaluations

1.

None C.

2006 ECCS Model Assessments

1.

Inconsistent Vessel Vertical Level Modeling

2.

Revised Downcomer Gap Inputs D.

Other

1.

None LICENSING BASIS PCT + PCT ASSESSMENTS PCT =

2035