ML13074A795

Millstone, Unit 2, Supplement to Response to Request for Additional Information Regarding 30-Day Report for Emergency Core Cooling System Model Changes (TAC ME7881)

ML13074A795
Person / Time
Site:	Millstone
Issue date:	03/07/2013
From:	Grecheck E S Dominion Nuclear Connecticut
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
12-578A
Download: ML13074A795 (2)

Text

Dominion Nuclear Connecticut, Inc.5000 Dominion Boulevard, Glen Allen, VA 23060 7J Dominion Web Address: www.dom.com Proprietary Information

-Withhold Under 10 CFR 2.390 March 7, 2013 U. S. Nuclear Regulatory Commission Serial No. 12-578A Attention:

Document Control Desk NSSL/WDC RO Washington, DC 20555 Docket No. 50-336 License No. DPR-65 DOMINION NUCLEAR CONNECTICUT.

INC.MILLSTONE POWER STATION UNIT 2 SUPPLEMENT TO RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING THE 30-DAY REPORT FOR EMERGENCY CORE COOLING SYSTEM MODEL CHANGES (TAC NO. ME7881)By letter dated January 25, 2012, Dominion Nuclear Connecticut, Inc. (DNC) submitted the Millstone Power Station Unit 2 (MPS2) 30-Day Report for Emergency Core Cooling System Model Changes. The report documented changes to, or errors discovered in, an acceptable Small Break Loss of Coolant Accident (SBLOCA) evaluation model (EM)application for the emergency core cooling system for MPS2, in accordance with 10 CFR 50.46(a)(3)(ii).

By letter dated August 28, 2012, the NRC transmitted a request for additional information (RAI) to DNC related to the report. DNC responded to the RAI in a letter dated November 1, 2012.In a telephone call between NRC and DNC on November 20, 2012, DNC agreed to perform additional sensitivity studies which would combine the effects of certain modeling assumptions for the MPS2 SBLOCA. Attachment 1 provides the summary report of the sensitivity studies. The report contains proprietary AREVA information.

The non-proprietary version of the report is provided in Attachment

2. It is respectfully requested that Attachment 1 be withheld from public disclosure in accordance with 10 CFR 2.390. The AREVA application for withholding and affidavit is provided in Attachment 3.As shown in the attached report, the SBLOCA current licensing basis peak clad temperature of 1801°F remains conservative.

Since the MPS2 SBLOCA current licensing basis peak clad temperature is conservative and consistent with the Reference 1 NRC approved methodology, no additional reporting under 10 CFR 50.46(a)(3)(ii) is warranted.

DNC understands that Supplement 1 of the Reference 1 AREVA S-RELAP5 based PWR SBLOCA evaluation model is currently with the NRC for review and approval.

As stated in the DNC letter dated November 1, 2012, within one year of NRC approval of Supplement 1 of Reference 1, DNC plans to submit a reanalysis of the SBLOCA event using Supplement 1 of Reference 1.Attachment I contains information that is being withheld from public disclosure under 10 CFR 2.390. Upon separation from Attachment 1, this letter is decontrolled.--

Serial No. 12-578A Docket No. 50-336 Page 2 of 2 If you have any questions regarding this submittal, please contact William D. Bartron at (860) 444-4301.Sincerely, Eugene S. Grecheck Vice President

-Nuclear Engineering and Development

References:

1. AREVA Report EMF-2328(P)(A), Revision 0, "PWR Small Break LOCA Evaluation Model, S-RELAP5 Based," March 2001.Attachments:

1. Millstone Unit 2 Small Break LOCA Sensitivity Study Summary Report (Proprietary)

2. Millstone Unit 2 Small Break LOCA Sensitivity Study Summary Report (Non-Proprietary)

3. AREVA application for withholding and affidavit Commitments made in this letter: None cc: U.S. Nuclear Regulatory Commission Region I 2100 Renaissance Blvd.Suite 100 King of Prussia, PA 19406-2713 J. S. Kim Project Manager -Millstone Power Station U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08 C2A Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station