ML19120A134

3/15/19 Summary of Public Meeting with Nuclear Entergy Institute, Duke Energy, and Southern Nuclear Operating Company Post-Pilot Implementation of Tornado Missile Risk Evaluator Methodology at Vogtle, Units 1 and 2 and Shearon Harris, Unit

ML19120A134
Person / Time
Site:	Harris, Vogtle
Issue date:	05/06/2019
From:	Ellen Brown Special Projects and Process Branch
To:	Duke Energy Progress, Nuclear Energy Institute, Southern Nuclear Operating Co
Brown E
References
EPID L-2017-LLA-0350, EPID L-2017-LLA-0355
Download: ML19120A134 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 M:1.y 6, 2019 INDUSTRY GROUP/

LICENSEE: Nuclear Energy Institute, Duke Energy Progress, and Southern Nuclear Operating Company FACILITIES: Vogtle Electric Generating Plant, Units 1 and 2, and Shearon Harris Nuclear Power Plant, Unit 1

SUMMARY

OF MARCH 15, 2019, PUBLIC MEETING WITH NUCLEAR ENERGY INSTITUTE, DUKE ENERGY PROGRESS, AND SOUTHERN NUCLEAR OPERATING COMPANY, TO DISCUSS POST-PILOT IMPLEMENTATION OF TORNADO MISSILE EVALUATOR METHODOLOGY (EPID L-2017-LLA-0350 AND L-2017-LLA-0355)

On March 15, 2019, the U.S. Nuclear Regulatory Commission (NRC) staff conducted a Category 2 public meeting with the Nuclear Energy Institute (NEI), Duke Energy Progress (Duke), and Southern Nuclear Operating Company (SNC) at NRC Headquarters, 11555 Rockville Pike, One White Flint North, Rockville, Maryland. The purpose of the meeting was to discuss any questions related with the post-implementation of the approved plant-specific applications of NEl's Tornado Missile Risk Evaluator methodology described in Revision 1A of NEI 17-02, "Tornado Missile Risk Evaluator (TMRE) Industry Guidance Document." Additionally, the meeting was intended to discuss questions associated with guidance provided by the NRC staff in a letter to NEI regarding tornado missile protection issued on February 28, 2019. The TMRE methodology document was provided in support of a previous meeting and is available in the Agencywide Documents Access and Management System (ADAMS) under Accession No. ML18207A876. The NRC staff's letter to NEI is available in ADAMS under Accession No. ML18338A085.

BACKGROUND On January 11, 2019 (ADAMS Accession No. ML18304A394), the NRC staff approved the addition to the Final Safety Analysis Report, as updated (UFSAR) a plant-specific methodology for SNC's Vogtle Electric Generating Plant (Vogtle), Units 1 and 2. This methodology supports the licensee's determination regarding whether protection of a selected group of safety-related systems, structures, or components (SSCs) against externally-generated tornado missiles is necessary. This approval was the first of three pilot submittals submitted to support the development of a generic risk-informed methodology to support a determination of whether certain safety-related SSCs require protection from externally-generated tornado missiles.

As indicated previously, on February 28, 2019, the Office of Nuclear Reactor Regulation issued a letter to the industry regarding actions that NRC licensees may consider in the resolution of issues with tornado missile protection. This correspondence discussed that licensees should evaluate the current plant configuration against the current UFSAR, the initial safety evaluation

report issued at the operating license stage, all subsequent tornado protection-related NRC approvals for the facility, and the "known and established" NRC guidance at the time of the approval(s), to assess whether additional tornado protection is necessary.

DISCUSSION The discussion started with acknowledgement by NEI and the NRC staff of success of the first TMRE pilot review and approval. It was further recognized that 15-month turnaround for a pilot review is relatively expeditious. The NRC staff noted that the cooperation and coordination between the NRC staff, SNC licensing staff, with support from NEI, was essential to the success and relative timeliness of the review.

Several questions regarding implementation of the Vogtle approval were discussed. In Section 3.8 of the Vogtle TMRE approval safety evaluation (SE), the NRC staff indicated that the licensee's methodology appropriately "[i]ncludes provisions for future sensitivity studies and the periodic reviews of the tornado missile risk of nonconforming SSCs to ensure the risk

• remains acceptably low." The Vogtle staff questioned whether the periodic review was based on the permanent missile count conducted as part of the initial walkdown. The NRC staff indicated that as discussed in Section 3.7 of the Vogtle approval SE, the licensee's proposed process to determine the impact of significant changes which increase the site missile (temporary or permanent) burden within the 2,500-foot missile radius were appropriately considered. Further, it was questioned whether the walkdowns performed initially to determine site missile count for TMRE were a one-time occurrence. The NRC staff indicated that the licensee is expected to both verify and justify why the missile count assumed during any future use of the Vogtle TMRE remains valid.

Unlike the Vogtle pilot submittal, the Shearon Harris Nuclear Power Plant, Unit 1 (Harris) and Grand Gulf Nuclear Station, Unit 1, pilot submittals excluded Target 1 (identified as the containment building) when calculating the near-ground missile impact parameter (MIP). A question was posed regarding using near-ground MIPs that were derived by including Target 1.

The NRC staff indicated that including Target 1 was determined to be acceptable only for Vogtle because the licensee demonstrated that the excluding Target 1 when calculating near-ground MIPs did not affect the application. Similarly, for post-pilot implementation any inclusion of the Target 1 in deriving near-ground MIPs must be justified.

The use of qualitative factors (e.g., sources of nearby missiles, administrative controls, target elevation) in Section 7.2 of NEI 17-02, Revision 1A (ADAMS Accession No. ML18207A876) for not applying a higher target-specific MIP as part of sensitivity analyses was discussed. The NRC staff indicated that the sensitivity study discussion identified in the methodology related to use of those qualitative factors were not used in any of the pilot submittals and therefore was not reviewed by the NRC staff for use.

The participants also discussed the scope of information for use in determining the applicability of any plant-specific methodology approval. The NRC staff indicated when considering the application of a methodology, the NRC staff expects that a licensee adopts the methodology en toto and apply it consistently with applicable terms, conditions, and limitations. The NRC staff noted that a review of the documents containing the applicable terms, conditions, and limitations include the submittal, submittal supplements, any correspondence, including meeting summaries providing NRC staff understanding, as well as the issued SE. The limitations, conditions, and deviations for the pilots were explicitly identified by both the licensee and outlined in the NRC's SE for the Vogtle pilot approval. The NRC staff discussed the ability to

exclude a detailed analysis regarding operator actions outside the control room performed after 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of the occurrence of the tornado that are outside Category I structures or require transit outside of Category I structure. The NRC staff indicated that for plants looking to avail themselves of plant-specific methodology approval must do an appropriate plant-specific evaluation of actions consistent with the probabilistic risk assessment standard or use conservative assumptions (similar to Vogtle) to show the impact on the application.

Additionally, the NRC staff discussed the use of cumulative risk. The staff indicated that the Vogtle pilot approval should not be seen to construe to exclude the potential impact of risk associated with unprotected SSCs in risk-informed decisionmaking carte blanche. This concept was reinforced and added to the plant-specific Harris methodology submittal (Section 8.3 of NEI 17-02, Revision 18, available in ADAMS under Accession No. ML18262A328). Members of the public did listen to the teleconference. No public Meeting Feedback forms nor comments that required additional NRC staff action were received. The NRC did not communicate or make any decisions or conclusions during the meeting.

Sincerely, IRA/

Eva A. Brown, Senior Project Manager Special Projects and Process Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-400, 50-424, and 50-425

Enclosure:

List of Attendees cc: Listserv

Attendees Nuclear Regulatory Commission Public Meeting Concerning Tornado Risk Evaluator Methodology March 15, 2019 U.S. NUCLEAR REGULATORY COMMISSION Greg Casto Robert Dennig Doug Broaddus G. Ed Miller Nageswara Karipineni Gordon Curran Alex Schwab Mehdi Reisi-Fard Shilp Vasavada Eva Brown EXTERNAL STAKEHOLDERS Ken Lowery, Southern Nuclear Jordan Vaughn, Duke Energy Leo Shanley, Jensen-Hughes Stephen Vaughn, Nuclear Energy Institute Christopher Riedl, Tennessee Valley Authority John Schrage, Entergy Randall Wilson, Ameren Justin Wear, Pacific Gas and Electric Jana Bergman, Curtiss-Wright Corporation Christopher J. Riedl, Tennessee Valley Authority David Bice, Entergy Raymond Dremel, Enercon Steve Catron, Florida Power and Light Jim Lechner, Jensen-Hughes Gary Demoss, Pacific Gas and Electric Mike O'Keefe, Certrec William Greeson, Entergy Enclosure

ML19120A134 *via-email NRC-001 OFFICE NRR/DORL/LSPB/PM NRR/DORL/LSPB/LA* NRR/DORL/LSPB/BC (A)

NAME EBrown JBurkhardt MOrenak (GMiller for)

DATE 5/6/19 5/2/19 5/6/19