ML13141A403

Closure Options for Generic Safety Issue (GSI)-191, Assessment of Debris Accumulation on Pressurized-Water Reactor Sump Performance in Resolution of Final Issues Related to Generic Letter

ML13141A403
Person / Time
Site:	McGuire, Mcguire
Issue date:	05/08/2013
From:	Capps S D Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC MC4692, TAC MC4693, GL-04-002, GSI-191
Download: ML13141A403 (5)

Text

Steven D. Capps DUKE Vice President ENERGY. McGuire Nuclear Station Duke Energy MG01VP I 12700 Hagers Ferry Road Huntersville, NC 28078 o: 980.875.4805 f: 980.875.4809 Steven.Capps@duke-energy.com May 8, 2013 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

SUBJECT:

Duke Energy Carolinas, LLC (Duke Energy)McGuire Nuclear Station (McGuire), Units 1 and 2 Docket Nos. 50-369 and 50-370 Closure Options for Generic Safety Issue (GSI)-1 91, "Assessment of Debris Accumulation on Pressurized-Water Reactor Sump Performance" in resolution of final issues related to Generic Letter (GL) 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" (TAC NOS. MC4692 and MC4693)On November 18, 2008, the Nuclear Regulatory Commission (NRC) issued a Request for Additional Information (RAI) regarding supplemental responses to GL 2004-02.On July 2, 2012, McGuire submitted final responses to all but one NRC question in the November 18, 2008 RAI. For the one remaining RAI question related to in-vessel downstream effects, McGuire committed to resolving the issue pending completion of NRC review and approval of the methodology described in WCAP-16793-NP, Revision 2, "Evaluation of Long-Term Cooling Considering Particulate, Fibrous and Chemical Debris in the Recirculating Fluid." As described in detail in the July 2, 2012 submittal, McGuire has designed and implemented modifications to the plant configuration in both Units 1 and 2 to enhance post-accident performance related to GSI-191, including:

Removal of a large quantity of fibrous insulation from containment (complete in both Units)* Design and implementation of a wholly modified, larger and more efficient strainer that incorporates bypass eliminators, resulting in a low downstream "pass-through" fibrous debris quantity in the reactor core of less than 15 grams/fuel assembly (complete in both Units)* Implementation of Emergency Core Cooling System (ECCS) Water Management Initiative modifications (complete in both Units)www.duke-energy.com U. S. Nuclear Regulatory Commission May 8, 2013 Page 2 The July 2, 2012 submittal also outlined the three remaining commitments related to closure of GSI-191 for McGuire. Commitments 1 and 2 in that letter were associated with completion of the remaining physical plant modifications noted above required to align the station configuration (Units 1 and 2) with that of the qualifying GSI-1 91 analyses; Commitment 3 was associated with the required McGuire response to in-vessel downstream effects. The status of those commitments is updated in Attachment 1.On July 9, 2012, the NRC technical staff issued Commission Paper SECY-12-0093 "Closure Options for Generic Safety Issue -191, Assessment of Debris Accumulation on Pressurized-Water Reactor Sump Performance".

In this letter, the staff recommended that licensees be allowed the flexibility to choose any of three options to resolve remaining issues on GSI-1 91: Option 1 -Compliance with 10 CFR 50.46 Based on Approved Models; Option 2 -Mitigative Measures and Alternative Methods Approach; and Option 3 -Different Regulatory Treatment for Suction Strainer and In-Vessel Effects. The associated Staff Requirements Memo approving the SECY-12-0093 recommendation was subsequently issued on December 14, 2012.In accordance with the SECY letter recommendation, McGuire will pursue GSI-191 Closure Option 1 since both Units 1 and 2 meet the requirements of 10 CFR 50.46, "Acceptance Criteria for Emergency Core Cooling Systems for Light-Water Nuclear Power Reactors," based on approved models for analyses, strainer head loss testing, and in-vessel downstream effects.WCAP-16793-NP, Revision 2 was approved by the NRC Safety Evaluation (SE) dated April 8, 2013; therefore, successful completion of the analysis in accordance with this SE will show compliance with 10 CFR 50.46 as it relates to in-vessel downstream effects, and resolve the final outstanding RAI question for McGuire.There are no new commitments made herein; however, the completion date for Commitment 3 in Attachment 1 is revised from 90 days upon issuance of the aforementioned SE to July 31, 2013 to allow time for the appropriate documentation of the in-vessel downstream effects analysis in accordance with the April 8, 2013 NRC SE.If any questions arise or additional information is needed, please contact P. T. Vu at (980) 875-4302.I declare under penalty of perjury that the foregoing is true and correct. Executed on the 8th day of May, 2013.Sincerely, Steven D. Capps Attachment U. S. Nuclear Regulatory Commission May 8, 2013 Page 3 xc (with Attachment):

V. M. McCree, NRC Region II Administrator Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, GA 30303-1257 J. S. Kim, NRC Project Manager 11555 Rockville Pike Mail Stop 0-8 C2 Rockville, MD 20852-2738 J. Zeiler, NRC Senior Resident Inspector McGuire Nuclear Station W. L. Cox, Ill, Section Chief Division of Environmental Health, Radiation Protection Section North Carolina Department of Environment and Natural Resources 1645 Mail Service Center Raleigh, NC 27699-1645 Attachment 1 McGuire Nuclear Station Generic Letter 2004-02 Supplemental Response Commitments it U. S. Nuclear Regulatory Commission May 9, 2013 Attachment 1 Page 1 of 1 (:ýOm idt ýITTFt, mi men Uae DuDate Fiber Insulation Replacement Project modifications are scheduled to be completed.

Spring 2013 (Completed on April 10, 2013)ECCS Water Management Initiative modifications Fall 2012 for Unit 2 are scheduled to be implemented.(Completed on October 25, 2012)3'i~ I McGuire will address the in-vessel downstream effects issue.July 31, 2013 (Problem Investigation Process M-08-7391, Corrective Action#2)