ML16011A061

Summary of 10/1/15 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 Project, Units 1 and 2 (CAC Mf

ML16011A061
Person / Time
Site:	South Texas
Issue date:	02/02/2016
From:	Lisa Regner Plant Licensing Branch IV
To:	South Texas
Regner L, NRR/DORL/LPLIV-1
References
CAC MF2400, CAC MF2401, CAC MF2402, CAC MF2403, CAC MF2404, CAC MF2405, CAC MF2406, CAC MF2407, CAC MF2408, CAC MF2409
Download: ML16011A061 (6)

Text

LICENSEE:

STP Nuclear Operating Company FACILITY:

South Texas Project, Units 1 and 2

SUMMARY

OF OCTOBER 1, 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" (CAC NOS. MF2400, MF2401, MF2402, MF2403, MF2404, MF2405. MF2406, MF2407, MF2408, AND MF2409)

On October 1, 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 September 15, 2015, are located in the Agencywrde Documents Access and Management System (ADAMS) at Accession No. ML15274A247. 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, July 15, 2014; and March 10, March 25, and August 20, 2015 (ADAMS Accession Nos. ML13295A222, ML13323A673, ML13323A128, ML13338A165, ML14015A312, ML14015A311, ML14029A533, ML14052A053, ML14072A076, ML14086A383, ML14087A126, ML14149A353, ML14149A354, ML14149A434, ML14178A481, ML14202A045. ML15072A092, ML15091A440, and ML15246A125, respectively), STPNOC submitted exemption requests accompanied by license amendment requests (LARs) 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 August 20, 2015, submittal, which provided information on STPNOC's new Risk over Deterministic (RoverD) methodology.

The licensee provided a draft of the handout, "Description of Supplement 2 to STPNOC Risk-Informed Licensing Application to Address GSl-191 and Respond to GL-2004-02," which can be found in ADAMS at Accession No. ML15271A304. The final version used during the meeting is in ADAMS at Accession No. ML15274A599. The modifications included a change to the slide 7 flowpath and additional bullets on slide 9.

The NRC staff stated that it would not meet the November 2015 issuance date requested by STP in its August 20, 2015, submittal. The NRC staff stated that there were several outstanding questions that were not adequately addressed by STPNOC in the submittal. Many of the remaining open items are discussed below. The NRC staff stated it would likely have a draft safety evaluation completed in November, but that additional questions were being developed and a request for additional information was likely, as well as the possibility of additional audits.

STPNOC staff discussed the slideshow, which provided an overview of the changes since the November 2013 submittal to incorporate the deterministic elements of the "Risk over Deterministic" approach - referred to as Rovero. The licensee stated that much of the previous scope of the CASA Grande platform are no longer applicable, such as conditional failure probabilities, correlations for lead loss, uncertainty quantification of pipe break probability distributions, time dependent debris transport, and the use of STP's PRA model of record for calculation of delta Core Damage Frequency (CDF) [STP's PRA model of record is only used for delta Large Early Release Frequency (LERF)]. CASA Grande is still used for debris generation and transport to the containment pool (not time dependent).

STPNOC staff also provided an overview of the in-vessel cooling analysis. NRC staff expressed concern that RELAP 5 was being used a basis for long-term core cooling since no verification and validation information was provided. The NRC staff also questioned the quality assurance provided for the use of RE LAP 5. A regulatory audit was discussed as a possible efficiency gain for the NRC staff's review of the in-vessel cooling analysis. This was tentatively discussed for the second week in November.

The NRC staff requested that the STP August submittal to be a 'stand-alone' document to the extent practical to enable an efficient review; however, changes to information were made in the August supplement without a statement as to the applicability of previous submittals. For example, a list of pipe break frequencies was provided which was different from previous submittals. Since there was not a statement that the latest submittal supersedes all previous submittals, the NRC staff is unclear which previous information on the docket is still applicable.

The STPNOC staff stated that clarifications would be provided in a future submittal.

STPNOC stated that it had changed the requested exemption for Title 10 to the Code of Federal Regulations Section 50.46 from subsection 50.46(b)(5) 'Long-term cooling' to subsection 50.46(d). STPNOC stated it changed the specified subsection to a broader exemption specific for breaks not bounded by analysis.

Other NRC concerns discussed with the licensee included discrepancies between the submittal and NUREG-1829, "Estimating Loss-of-Coolant Accident (LOCA) Frequencies Through the Elicitation Process," the PRA for a single train of emergency core cooling system available, in-vessel long-term cooling analysis, and inorganic zinc coatings. This is not an inclusive list, however, since there was not enough time to discuss all of the NRC technical staff concerns.

No members of the public attended the meeting and no Public Meeting Feedback Forms were received.

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

Docket Nos. 50-498 and 50-499

Enclosure:

List of Attendees cc w/encl: Distribution via Listserv Lisa M. Regner, Senior Project Manager Plant Licensing Branch IV-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

LIST OF ATTENDEES OCTOBER 1. 2015, CONFERENCE CALL WITH STP NUCLEAR OPERATING COMPANY REGARDING RISK-INFORMED APPROACH TO RESOLUTION OF GSl-191 NAME Lisa Regner John Stang Victor Cusumano Matt Yoder Josh Kaizer Jeremy Dean Paul Klein Ahsan Sallman Steve Smith John Tsao Marioly Diaz Colon Steve Laur Lindsay Robinson Caroline Tilton Josh Whitman Tim Lupold Andrea Russell Matt Rossi Ashley Smith Michael Markley Reed Anzalone Osvaldo Pensado Mike Murray Steve Blossom Rob Engen Ernie Kee Wayne Harrison SOUTH TEXAS PROJECT, UNITS 1 AND 2 DOCKET NOS. 50-498 AND 50-499 ORGANIZATION U.S. Nuclear Regulatory Commission (NRC)

NRC NRC NRC NRC NRC NRC NRC NRC NRC NRC NRC NRC NRC NRC NRC NRC NRC NRC NRC NRC Southwest Research Institute (contractor for NRC)

STP Nuclear Operating Company (STPNOC)

STPNOC STPNOC STPNOC STPNOC Enclosure NAME ORGANIZATION Linda Dyer STPNOC Wes Schulz STPNOC Drew Richards STPNOC Bruce Letellier Alien Science & Technology Janet Leavitt Alien Science & Technology Dominic Munoz Alien Science & Technology Kip Walker ENERCON Blake Stair ENERCON Phillip Grissom Southern Nuclear Craig Sellers Calvert Cliffs Nuclear Tim Sande ENERCON Paul Leonard NextEra Energy

ML16011A061 OFFICE NRR/DORL/LPL4-1 /PM NRR/DORL/LPL4-1 /LA NRR/DSS/SSIB/BC*

NAME LRegner JBurkhardt VCusumano DATE 1/11/16 1/11/16 1/19/16 OFFICE NRR/DRA/APLA/BC*

NRR/DE/ESGB/BC*

NRR/DORL/LPL4-1 /BC NAME SRosenberg GKulesa RPascarelli DATE 1 /25/16 1/12/16 01/29/16