ML103510320
| ML103510320 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 12/20/2010 |
| From: | Sanders C Plant Licensing Branch 1 |
| To: | Chernoff H Plant Licensing Branch 1 |
| Sandeers, Carleen, NRR/DORL, 415-1603 | |
| References | |
| TAC ME4273, FOIA/PA-2011-0115 | |
| Download: ML103510320 (3) | |
Text
December 20, 2010 MEMORANDUM TO:
Harold K. Chernoff, Chief Plant Licensing Branch, I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation MEMORANDUM FROM:
Carleen J. Sanders, Project Manager /ra/
Plant Licensing Branch, I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
SUBJECT:
MILLSTONE POWER STATION, UNIT NO. 2 DAY REPORT OF EMERGENCY CORE COOLING SYSTEM MODEL CHANGE (TAC NO. ME4273)
By letter dated June 18, 2009 (Agencywide Document Access and Management System Accession No. ML091690652), Dominion Nuclear Connecticut, Inc. (DNC or the licensee) submitted to the U.S. Nuclear Regulatory Commission (NRC) a 30-day report of emergency core cooling system (ECCS) model changes for Millstone Power Station, Unit No. 2 (MPS2) pursuant to the requirements of Title 10 of the Code of Federal Regulations (10 CFR) 50.46, Acceptance Criteria for Emergency Core Cooling Systems for Light-Water Nuclear Power Plants. The report was submitted due to an error that was discovered in the computer code used to model small-break loss-of-coolant accidents (SBLOCAs) at MPS2. The error resulted in a -64 °F change in the SBLOCA peak cladding temperature (PCT) and a corrected PCT of 1714 °F.
In accordance with 10 CFR 50.46(a)(3)(ii), if any significant change or error in the PCT value is discovered, a report containing the nature of the change or error and an estimated effect on the limiting ECCS analyses shall be submitted to the NRC within 30 days. The report shall include a proposed schedule for providing a reanalysis or taking other action as may be needed to show compliance with the 10 CFR 50.46 requirements. 10 CFR 50.46(b)(1) requires that the calculated maximum PCT shall not exceed 2200 °F. A significant change or error is defined in 10 CFR 50.46(a)(3)(i) as a change or error in which results in a calculated peak fuel cladding temperature different by more than 50 °F from the temperature calculated for the limiting transient using the last acceptable model, or is a cumulation of changes and errors such that the sum of the absolute magnitudes of the respective temperature changes is greater than 50 °F.
of the June 18, 2009, letter provides the nature of the error and the adjusted SBLOCA PCT value and the manner in which it was derived. The adjusted SBLOCA resulted in a -64 °F change in the SBLOCA PCT and a corrected PCT of 1714 °F. A proposed schedule for providing reanalysis or taking other actions was not provided with the June 18 letter because the adjusted SBLOCA PCT value and the manner in which it was derived were provided. The corrected PCT meets the requirements of 10 CFR 50.46(b)(1).
The NRC staff has reviewed DNCs submittal and finds that it meets the requirements of 10 CFR 50.46. This memorandum is to inform you that no further action will be taken with regards to this matter and TAC No. ME4273 will be closed.
Docket No. 50-336
December 20, 2010 MEMORANDUM TO:
Harold K. Chernoff, Chief Plant Licensing Branch, 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation MEMORANDUM FROM:
Carleen J. Sanders, Project Manager /ra/
Plant Licensing Branch, 1-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
SUBJECT:
MILLSTONE POWER STATION, UNIT NO. 2 DAY REPORT OF EMERGENCY CORE COOLING SYSTEM MODEL CHANGE (TAC NO. ME4273)
By letter dated June 18, 2009 (Agencywide Document Access and Management System Accession No. ML091690652), Dominion Nuclear Connecticut, Inc. (DNC or the licensee) submitted to the U.S. Nuclear Regulatory Commission (NRC) a 30-day report of emergency core cooling system (ECCS) model changes for Millstone Power Station, Unit No. 2 (MPS2) pursuant to the requirements of Title 10 of the Code of Federal Regulations (10 CFR) 50.46, Acceptance Criteria for Emergency Core Cooling Systems for Light-Water Nuclear Power Plants. The report was submitted due to an error that was discovered in the computer code used to model small-break loss-of-coolant accidents (SBLOCAs) at MPS2. The error resulted in a -64 °F change in the SBLOCA peak cladding temperature (PCT) and a corrected PCT of 1714 °F.
In accordance with 10 CFR 50.46(a)(3)(ii), if any significant change or error in the PCT value is discovered, a report containing the nature of the change or error and an estimated effect on the limiting ECCS analyses shall be submitted to the NRC within 30 days. The report shall include a proposed schedule for providing a reanalysis or taking other action as may be needed to show compliance with the 10 CFR 50.46 requirements. 10 CFR 50.46(b)(1) requires that the calculated maximum PCT shall not exceed 2200 °F. A significant change or error is defined in 10 CFR 50.46(a)(3)(i) as a change or error in which results in a calculated peak fuel cladding temperature different by more than 50 °F from the temperature calculated for the limiting transient using the last acceptable model, or is a cumulation of changes and errors such that the sum of the absolute magnitudes of the respective temperature changes is greater than 50 °F.
of the June 18, 2009, letter provides the nature of the error and the adjusted SBLOCA PCT value and the manner in which it was derived. The adjusted SBLOCA resulted in a -64 °F change in the SBLOCA PCT and a corrected PCT of 1714 °F. A proposed schedule for providing reanalysis or taking other actions was not provided with the June 18 letter because the adjusted SBLOCA PCT value and the manner in which it was derived were provided. The corrected PCT meets the requirements of 10 CFR 50.46(b)(1).
The NRC staff has reviewed DNCs submittal and finds that it meets the requirements of 10 CFR 50.46. This memorandum is to inform you that no further action will be taken with regards to this matter and TAC No. ME4273 will be closed.
Docket No. 50-336 Distribution:
PUBLIC RidsNrrMillstone Resource RidsNrrDorlLpl1-2 Resource LPLI-2 Reading RidsNrrLAABaxter Resource RidsRgn1MailCenter Resource RidsNrrDssSrxb Resource BPArks, NRR AGuzzetta, NRR ADAMS Accession No. ML103510320
- via email OFFICE DORL/LPL1-2/PM DORL/LPL1-2/LA DSS/SRXB/BC DORL/LPL1-2/BC NAME CSanders ABaxter
- TUlses (BParks for)
HChernoff (REnnis for)
DATE 12/10/10 12/20/10 12/17/10 12/20/10 Official Record Copy