ML12310A202

Three Mile Island Nuclear Station, Unit 1 - Electronic Transmission, Draft Request for Additional Information Regarding 30-Day Report for Emergency Core Cooling System Model Changes Pursuant to the Requirements of 10 CFR 50.46 (TAC No. ME82

ML12310A202
Person / Time
Site:	Three Mile Island
Issue date:	11/06/2012
From:	Bamford P J Plant Licensing Branch 1
To:	Khanna M K Plant Licensing Branch 1
Bamford P J
References
TAC ME8237
Download: ML12310A202 (3)

Text

November 6, 2012

MEMORANDUM TO: Meena Khanna, Chief Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation FROM: Peter Bamford, Project Manager /RA/ Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

SUBJECT:

THREE MILE ISLAND, UNIT NO. 1 - ELECTRONIC TRANSMISSION, DRAFT REQUEST FOR ADDITIONAL INFORMATION REGARDING 30-DAY REPORT FOR EMERGENCY CORE COOLING SYSTEM MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 (TAC NO. ME8237)

The attached draft request for additional information (RAI) was transmitted by electronic transmission on November 5, 2012 to Mr. Thomas Loomis, at Exelon Generation Company, LLC (Exelon, the licensee). This draft RAI was transmitted to facilitate the technical review being conducted by the Nuclear Regulatory Commission (NRC) staff and to support a conference call (if needed) with Exelon in order to clarify the licensee's submittal reporting a change or error discovered in an Emergency Core Cooling System evaluation model or in the application of such a model that affects the peak cladding temperature (PCT) calculation at Three Mile Island Nuclear Station, Unit 1 (TMI-1). The draft RAI is related to the licensee's submittal dated March 21, 2012. The draft question was sent to ensure that it was understandable, the regulatory basis was clear, and to determine if the information was previously docketed. Additionally, review of the draft RAI would allow Exelon to evaluate and agree upon a schedule to respond to the RAI. This memorandum and the attachment do not represent an NRC staff position. Docket Nos. 50-289 Enclosure: As stated November 6, 2012 MEMORANDUM TO: Meena Khanna, Chief Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

FROM: Peter Bamford, Project Manager /RA/ Plant Licensing Branch I-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

SUBJECT:

THREE MILE ISLAND, UNIT NO. 1 - ELECTRONIC TRANSMISSION, DRAFT REQUEST FOR ADDITIONAL INFORMATION REGARDING 30-DAY REPORT FOR EMERGENCY CORE COOLING SYSTEM MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 (TAC NO. ME8237)

The attached draft request for additional information (RAI) was transmitted by electronic transmission on November 5, 2012 to Mr. Thomas Loomis, at Exelon Generation Company, LLC (Exelon, the licensee). This draft RAI was transmitted to facilitate the technical review being conducted by the Nuclear Regulatory Commission (NRC) staff and to support a conference call (if needed) with Exelon in order to clarify the licensee's submittal reporting a change or error discovered in an Emergency Core Cooling System evaluation model or in the application of such a model that affects the peak cladding temperature (PCT) calculation at Three Mile Island Nuclear Station, Unit 1 (TMI-1). The draft RAI is related to the licensee's submittal dated March 21, 2012. The draft question was sent to ensure that it was understandable, the regulatory basis was clear, and to determine if the information was previously docketed. Additionally, review of the draft RAI would allow Exelon to evaluate and agree upon a schedule to respond to the RAI. This memorandum and the attachment do not represent an NRC staff position. Docket Nos. 50-289

Enclosure:

As stated DISTRIBUTION: Public RidsNrrPMPBamford LPL1-2 R/F Accession No.: ML12310A202

• via email OFFICE LPL1-2/PM SRXB/BC NAME PBamford CJackson*DATE 11/06/12 10/16/2012 OFFICIAL RECORD COPY DRAFT Enclosure REQUEST FOR ADDITIONAL INFORMATION REGARDING THREE MILE ISLAND NUCLEAR STATION, UNIT 1 30-DAY REPORT FOR EMERGENCY CORE COOLING SYSTEM MODEL CHANGES PURSUANT TO THE REQUIREMENTS OF 10 CFR 50.46 DOCKET NO. 50-289

By letter dated March 21, 2012 (Agencywide Documents Access and Management System Accession No. ML12081A083), Exelon Generation Company, LLC (the licensee), sent a notice reporting a change or error discovered in an evaluation model or in the application of such a model that affects the peak cladding temperature (PCT) calculation for Three Mile Island Nuclear Station, Unit 1 (TMI-1). This report was submitted pursuant to the requirements of Title 10 of the Code of Federal Regulations (10 CFR) Section 50.46, which requires, in part, that licensees report a change in the evaluation model used resulting in a significant change in PCT (greater than 50°F). As described in the statements of consideration published in the Federal Register (FR), the intent of this requirement is to enable the staff to establish the safety significance of this change (53 FR 35996-36005).

1. There are two changes to PCT for Large Break Loss of Coolant Accident (LBLOCA) analysis discussed in the report submitted by the licensee. The first change is an Evaluation Model (EM) application error in the determination of the end of Emergency Core Cooling System (ECCS) bypass which resulted in an 80°F decrease in PCT. The second change is an EM modeling change to include the effects of the upper plenum column weldments which resulted in an 80°F increase in PCT. Provide the analysis that lead to each change having an 80 degree change in PCT. 2. Paragraph 50.46(a)(3)(ii) of 10 CFR states: " ... If the change or error is significant, the applicant or licensee shall provide this report within 30 days and include with the report a proposed schedule for providing a reanalysis or taking other action as may be needed to show compliance with 50.46 requirements ... "

The PCT for LBLOCA for TMI-1 has changed by an absolute value of 160°F since the analysis was performed. Simply reporting the changes and errors in the methodology does not satisfy the intent of the regulation. Justify not providing a schedule for reanalysis or taking other action to show compliance with Section 50.46.