L-09-125, Submittal of Annual Report of Changes to the Emergency Core Cooling System Evaluation Model and in the Application of the Model in Accordance with 10 CFR 50.46(a)(3)

Submittal of Annual Report of Changes to the Emergency Core Cooling System Evaluation Model and in the Application of the Model in Accordance with 10 CFR 50.46(a)(3)

ML091530180
Person / Time
Site:	Davis Besse
Issue date:	05/28/2009
From:	Allen B FirstEnergy Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-09-125
Download: ML091530180 (4)

Text

FENOC 5501 North State Route 2 FirstEnergyNuclear Operating Company Oak Harbor,Ohio 43449 Barry S. Allen 419-321-7676 Vice President - Nuclear Fax: 419-321-7582 May 28, 2009 L-09-125 10 CFR 50.46 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

SUBJECT:

Davis-Besse Nuclear Power Station, Unit No. 1 Docket No. 50-346, License No. NPF-3 Report of Changes to the Emergency Core Cooling System Evaluation Model and in the Application of the Model in Accordance with 10 CFR 50.46(a)(3)

In accordance with 10 CFR 50.46(a)(3), FirstEnergy Nuclear Operating Company (FENOC) hereby submits the annual report for changes and errors in the Emergency Core Cooling System (ECCS) evaluation model (EM) and in the application of the model used at the Davis-Besse Nuclear Power Station, Unit No. 1. The attached report covers the period of January 1, 2008 to December 31, 2008.

There are no regulatory commitments contained in this letter. If there are any questions or if additional information is required, please contact Mr. Thomas A. Lentz, Manager -

Fleet Licensing, at (330) 761-6071.

Sincerely, Barry Allen

Attachment:

Annual Report of Changes to the 10 CFR 50.46 Emergency Core Cooling System Evaluation Model and in the Application of the Model for the Davis-Besse Nuclear Power Station, Unit No. 1 cc: NRC Region III Administrator NRR Project Manager - Davis-Besse Nuclear Power Station NRC Resident Inspector - Davis-Besse Nuclear Power Station Utility Radiological Safety Board

Attachment L-09-125 Annual Report of Changes to the 10 CFR 50.46 Emergency Core Cooling System Evaluation Model and in the Application of the Model for the Davis-Besse Nuclear Power Station, Unit No. 1 Page 1 of 3 10 CFR 50.46 (a)(3) states that each holder of an operating license shall report to the Nuclear Regulatory Commission (NRC), at least annually, each change or error in an acceptable Emergency Core Cooling System (ECCS) evaluation model (EM) or in the application of such a model that affects the calculation of peak cladding temperature (PCT).

EVALUATION MODEL CHANGES AND ERRORS Babcock & Wilcox Nuclear Technologies (BWNT) Loss of Coolant Accident (LOCA)

Evaluation Model No errors were identified and no changes were implemented during the reporting period.

CRAFT2 LOCA Evaluation Model No errors were identified and no changes were implemented during the reporting period.

EVALUATION MODEL APPLICATION CHANGES AND ERRORS Fuel Temperature Uncertainty During development of the cycle 16 LOCA linear heat rate limits, it was discovered that the fuel temperature uncertainty applied to account for the decrease in fuel thermal conductivity at end-of-life (i.e., 62,000 megawatt thermal per metric ton of uranium) for the 2, 4, 6, and 8 weight percent gadolinia fuel was specified incorrectly in the large-break LOCA analyses. It was confirmed that the U0 2 fuel pins at end-of-life utilized the correct fuel temperature uncertainty factor. The fuel temperature uncertainty error resulted in a peak clad temperature (PCT) error of 0°F. The small-break LOCA PCTs were determined to be unaffected.

REFLOD3 Model During review of the REFLOD3 model it was discovered that the Low Pressure Injection (LPI) system's flowrate data were specified incorrectly. The result of this input error was that a slightly lower LPI head flow curve was used because the pressure was specified in terms of pounds-force per square inch gauge rather than pounds-force per square inch absolute that is required by the REFLOD3 code. The result of the 14.7 pounds per square inch difference in LPI pressure was evaluated and the Mark-B-HTP large-break PCTs were not affected. Because REFLOD3 is not utilized for the small-break LOCA analyses, these analyses were not affected by this error.

Attachment L-09-125 Page 2 of 3 Summary A summary of the errors identified during the reporting period and the corresponding PCT changes is provided in Table 1.

Attachment L-09-125 Page 3 of 3 Table 1 10 CFR 50.46 Summary for 2008 PlantName: Davis-Besse Unit 1 LOCA Spectrum Mk-B-HTP Utility Name: FirstEnergy Mk-BIOM Mk-BIOK Mk-B12 LBLOCA SBLOCA LBLOCA LBLOCA LBLOCA Mixed-Core Item Reporting Description PCTor (DeltaPCT)

1. Category

<2,102 OF 2,102 °F 2,099 °F 2,098 OF 1,555 °F LicensingBasis at Beginning of 2008 Estimate Analyzed Analyzed Analyzed Analyzed 1

EM RO.6 EM R0.6 EM RO.6 EM RO.9 EM R0.9 2008 LicensingActivity 1 Application Error Fuel Temperature Uncertainty for Gadolinia Fuel N/A N/A N/A 0 OF N/A

- 2 Application Error Low Pressure Injection System Flow Data Error in REFLOD3 N/A N/A N/A 0 OF N/A

<2,102 OF 2,102 OF 2,099 OF 2,098 OF 1,555 OF LicensingBasis at End of 2008 Estimate Analyzed Analyzed Analyzed Analyzed EM RO.6 EM RO.6 EM RO.6 EM RO.9 EM RO.9 Footnotes: (1) Evaluation Model revision number.