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 DominionWeb Address: www.dom.comProprietary Information -Withhold Under 10 CFR 2.390March 7, 2013U. S. Nuclear Regulatory Commission Serial No. 12-578AAttention: Document Control Desk NSSL/WDC ROWashington, DC 20555 Docket No. 50-336License No. DPR-65DOMINION NUCLEAR CONNECTICUT. INC.MILLSTONE POWER STATION UNIT 2SUPPLEMENT TO RESPONSE TO REQUEST FOR ADDITIONAL INFORMATIONREGARDING THE 30-DAY REPORT FOR EMERGENCY CORE COOLING SYSTEMMODEL CHANGES (TAC NO. ME7881)By letter dated January 25, 2012, Dominion Nuclear Connecticut, Inc. (DNC) submittedthe Millstone Power Station Unit 2 (MPS2) 30-Day Report for Emergency Core CoolingSystem 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 10CFR 50.46(a)(3)(ii). By letter dated August 28, 2012, the NRC transmitted a request foradditional information (RAI) to DNC related to the report. DNC responded to the RAI ina letter dated November 1, 2012.In a telephone call between NRC and DNC on November 20, 2012, DNC agreed toperform additional sensitivity studies which would combine the effects of certainmodeling assumptions for the MPS2 SBLOCA. Attachment 1 provides the summaryreport of the sensitivity studies. The report contains proprietary AREVA information.The non-proprietary version of the report is provided in Attachment 2. It is respectfullyrequested that Attachment 1 be withheld from public disclosure in accordance with 10CFR 2.390. The AREVA application for withholding and affidavit is provided inAttachment 3.As shown in the attached report, the SBLOCA current licensing basis peak cladtemperature of 1801°F remains conservative. Since the MPS2 SBLOCA currentlicensing basis peak clad temperature is conservative and consistent with the Reference1 NRC approved methodology, no additional reporting under 10 CFR 50.46(a)(3)(ii) iswarranted.DNC understands that Supplement 1 of the Reference 1 AREVA S-RELAP5 basedPWR SBLOCA evaluation model is currently with the NRC for review and approval. Asstated in the DNC letter dated November 1, 2012, within one year of NRC approval ofSupplement 1 of Reference 1, DNC plans to submit a reanalysis of the SBLOCA eventusing Supplement 1 of Reference 1.Attachment I contains information that is being withheld from publicdisclosure under 10 CFR 2.390. Upon separation from Attachment 1, thisletter is decontrolled.--

Serial No. 12-578ADocket No. 50-336Page 2 of 2If you have any questions regarding this submittal, please contact William D. Bartron at(860) 444-4301.Sincerely,Eugene S. GrecheckVice President -Nuclear Engineering and DevelopmentReferences:1. AREVA Report EMF-2328(P)(A), Revision 0, "PWR Small Break LOCAEvaluation 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 affidavitCommitments made in this letter: Nonecc: U.S. Nuclear Regulatory CommissionRegion I2100 Renaissance Blvd.Suite 100King of Prussia, PA 19406-2713J. S. KimProject Manager -Millstone Power StationU.S. Nuclear Regulatory CommissionOne White Flint North11555 Rockville PikeMail Stop 08 C2ARockville, MD 20852-2738NRC Senior Resident InspectorMillstone Power Station