ML15201A003

7/2/15 Summary of Meeting with STP Nuclear Operating Company to Discuss Revised Pilot Submittal and Request for Exemptions for a Risk-Informed Approach to Resolve Generic Safety Issue (GSI)-191 at South Texas, Units 1 and 2

ML15201A003
Person / Time
Site:	South Texas
Issue date:	07/30/2015
From:	Lisa Regner Plant Licensing Branch IV
To:	Koehl D South Texas
Regner L
References
TAC MF2400, TAC MF2401, TAC MF2402, TAC MF2403, TAC MF2404, TAC MF2405, TAC MF2406, TAC MF2407, TAC MF2408, TAC MF2409
Download: ML15201A003 (7)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 July 30, 2015 LICENSEE: STP Nuclear Operating Company FACILITY: South Texas Project, Units 1 and 2

SUMMARY

OF JULY 2, 2015, PUBLIC MEETING WITH STP NUCLEAR OPERATING COMPANY TO DISCUSS THE LICENSE AMENDMENT AND EXEMPTION REQUESTS TO USE A RISK-INFORMED APPROACH TO THE RESOLUTION OF GENERIC SAFETY ISSUE 191, "ASSESSMENT OF DEBRIS ACCUMULATION ON PWR SUMP PERFORMANCE" (TAC NOS. MF2400, MF2401, MF2402, MF2403, MF2404, MF2405, MF2406, MF2407, MF2408, AND MF2409)

On July 2, 2015, a public meeting was held between the U.S. Nuclear Regulatory Commission (NRC) and representatives of STP Nuclear Operating Company (STPNOC, the licensee), at NRC Headquarters, Rockville, Maryland. The meeting notice and agenda, dated June 22, 2015, are located in the Agencywide Documents Access and Management System (ADAMS) at Accession No. ML15173A343. A list of meeting attendees is provided in the Enclosure to this meeting summary.

By letter dated June 19, 2013 (ADAMS Accession No. ML131750250), as supplemented by letters dated October 3, October 31, November 13, November 21 and December 23, 2013 (two letters); and January 9, February 13, February 27, March 17, March 18, May 15 (two letters),

May 22, June 25, and July 15, 2014; and March 10 and 25, 2015 (ADAMS Accession Nos. ML13295A222, ML13323A673, ML13323A128, ML13338A165, ML14015A312, ML14015A311, ML14029A533, ML14052A053, ML14072A076, ML14086A383, ML14087A126, ML14149A353, ML14149A354, ML14149A434, ML14178A481, ML14202A045, ML15072A092, and ML15091A440, respectively), STPNOC submitted exemption requests accompanied by a license amendment request (LAR) for a risk-informed approach to resolve Generic Safety Issue (GSl)-191, "Assessment of Debris Accumulation on PWR [Pressurized-Water Reactor] Sump Performance," at South Texas Project, Units 1 and 2 (STP).

The purpose of this public teleconference call was to discuss the licensee's upcoming submittal, which the licensee stated it plans to submit in July 2015. The supplement is expected to provide information on the new Risk over Deterministic (RoverD) methodology, and modify the LAR and exemption requests.

Meeting Summary The licensee provided two handouts. The first, Talking Points for July 2, 2015 Public Call, can be found in ADAMS at Accession No. ML15182A180. The second, Deterministic Basis, provides some modifications and additions to portions of the first submittal, and can be found at ADAMS Accession No. ML15182A228.

The licensee stated that the next submittal will have 14 elements and will be an update to the 2008 submittal. It will discuss changes and updates associated with debris generation and transport for fibers, Rovero, deterministic testing, zone of influence (ZOI) changes for fiber and coatings, and chemical effects.

The licensee continued with a discussion of how it will address the NRC staff's concerns associated with the inorganic zinc ZOI assessment (refer to the June 3, 2015, public meeting summary, which can be found in ADAMS at Accession No. ML15180A273). The licensee recognized its testing non-conservatisms associated with epoxy coatings and pointed out its over-conservatisms associated with Marinite, which has since been removed from both containment buildings. The licensee plans to provide an assessment of the impacts of these and other factors on the coatings analyses.

The licensee plans to provide a detailed description of the thermal-hydraulic analyses, changes to CASA Grande from Rovero, additional sensitivity studies for strainer and spray configurations, a focus on mitigation for the defense-in-depth discussion, and a discussion on boric acid precipitation and its reference to Westinghouse Electrical Company LLC's topical report WCAP-16793, Evaluation of Long-Term Cooling Considering Particulate, Fibrous and Chemical Debris in the Recirculating Fluid.

During a discussion on the exemptions, the NRC staff cautioned the licensee's apparent re-definition of the term "single failure" since it has a very specific definition in regulatory and licensing applications. The NRC staff suggested that attempts to re-define single failure for this specific purpose will lead to additional questions and requests for information. The NRC staff emphasized the need for the licensee to provide a strong justification for exemptions since some of the weld failures may produce debris amounts several times the threshold.

The NRC staff questioned an apparent significant reduction in the reported net positive suction head (NPSH) required for the emergency core cooling system and containment spray system pumps. The licensee stated it had changed only the reference point (i.e., assumed zero elevation) for NPSH measurements and that the values were actually the same as previous submittals. The staff suggested that the licensee address several Westinghouse Nuclear Safety Advisory Letters in its containment analysis, explain its methodology, and how it will be described in the Updated Final Safety Analysis Report.

The NRC staff expressed concern with the Leak-Before-Break (LBB) credit discussed in the draft sections of the submittal (first handout, page 9 of 29). Specifically, the staff pointed out that previous industry efforts to use LBS as a basis for removing certain break locations from GSl-191-related analyses were unsuccessful. 1 The licensee stated that the proposed approach does not involve removal of break locations due to LBS and that all break locations are within the scope of the analysis. The licensee further stated that LBB was only mentioned qualitatively as a means of providing additional assurance that overall LOCA frequencies are low. The licensee stated that this distinction would be clarified in the revised submittal.

1 A discussion is included in an NRC letter dated March 4, 2004, to Mr. Antony Pietrangelo, Nuclear Energy Institute at ADAMS Accession No. ML040410433).

The licensee informed the NRC staff that it will complete its responses to a 2008 request for additional information related to GSl-191. Additionally, after a question from the NRC staff, the licensee stated that no break locations will exceed tested inorganic zinc amounts and that the supplement includes a discussion of credit for top-coated inorganic zinc.

The licensee discussed issues regarding safety margins by identifying conservatisms included in the debris analyses for STP. The NRC staff noted that this section also seemed to imply that low risk numbers could be compared with safety margins, a position that appears to depart from agency guidance on risk-informed decision-making (RG 1.174). The licensee stated that it would consider reorganizing this information to clarify that its approach was not inconsistent with existing NRC guidance on risk-informed decisions.

The NRC staff questioned the licensee's schedule for upcoming submittals and if there is a need for another public meeting. The licensee stated that it plans to submit on July 17 of this year, but stated that date would likely slip a week.

Two members of the public attended the call. Mr. Marvin Lewis provided comments relating to leak-before-break credit and disagreement with the NRC staff having off-line discussions while on mute. Ms. Karen Hadden requested copies of the meeting handouts and associated relevant documents to be sent to her by e-mail. No Public Meeting Feedback Forms were received for this meeting.

If you have any questions, please contact me at 301-415-1906 or via e-mail at Lisa. Regner@nrc.gov.

Sincerely,

~~~<

Lisa M. Regner, Senior Project Manager Plant Licensing Branch IV-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-498 and 50-499

Enclosure:

List of Attendees cc w/encl: Distribution via Listserv

LIST OF A TIENDEES JULY 2. 2015, CONFERENCE CALL WITH STP NUCLEAR OPERATING COMPANY REGARDING RISK-INFORMED APPROACH TO RESOLUTION OF GSl-191 SOUTH TEXAS PROJECT. UNITS 1 AND 2 DOCKET NOS. 50-498 AND 50-499 NAME ORGANIZATION Lisa Regner U.S. Nuclear Regulatory Commission (NRC)

John Stang NRC Victor Cusumano NRC Matt Yoder NRC Margaret Watford NRC Jeremy Dean NRC CJ Fong NRC Ahsan Sallman NRC Steve Smith NRC John Tsao NRC Marioly Diaz Colon NRC Steve Laur NRC Lindsay Robinson NRC Caroline Tilton NRC Jim Hickey NRC Tim Lupold NRC Andrea Russell NRC Matt Rossi NRC Ashley Guzzetta NRC Osvaldo Pensado Southwest Research Institute (contractor for NRC)

Stuart Stothoff Southwest Research Institute (contractor for NRC)

Mike Murray STP Nuclear Operating Company (STPNOC)

Steve Blossom STPNOC Rob Engen STPNOC Ernie Kee STPNOC Wayne Harrison STPNOC Linda Dyer STPNOC Wes Schulz STPNOC Enclosure

NAME ORGANIZATION Drew Richards STPNOC Levi Holden STPNOC Mark Coughlin STPNOC Bruce Letellier Alien Science & Technology Janet Leavitt Alien Science & Technology Dominic Munoz Alien Science & Technology Tim Sande ENERCON Karen Hadden SEED Coalition Marvin Lewis Public

Mtg Notice ML15173A343; Mtg Summary ML15201A003; Licensee Handouts ML15182A180 and ML15182A228 *via email OFFICE NRR/DORL/LPL4-1 /PM NRR/DORL/LPL4-1 /LA NRR/DSS/SSIB/BC NRR/DE/EMCB/BC NRR/DSS/STSB/BC NAME LRegner JBurkhardt VCusumano* Tlupold* RElliott*

DATE 7/17/15 7/21/15 7/21/15 7/22/15 7/21/15 OFFICE NRR/DRA/APLA/BC NRR/DE/ESGB/BC NRR/DSS/SNPB/BC NRR/DORL/LPL4-1 /BC NRR/DORL/LPL4-1 /PM NAME SRosenberg* GKulesa* JDean* MMarkley LRegner (AGeorge for)

DATE 7/27/15 7/24/15 7/28/15 7/30/15 7/30/15