ML17257A099
| ML17257A099 | |
| Person / Time | |
|---|---|
| Site: | Harris, Grand Gulf, Vogtle  |
| Issue date: | 09/26/2017 |
| From: | Ellen Brown Special Projects and Process Branch |
| To: | Duke Energy Progress, Entergy Operations, Southern Nuclear Operating Co |
| Brown E, DORL/LSPB, 415-2315 | |
| References | |
| CAC MG0109, CAC MG0110, CAC MG0111, CAC MG0112 | |
| Download: ML17257A099 (5) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 September 26, 2017 LICENSEES: Duke Energy Progress, LLC; Southern Nuclear Operating Company, Inc.; and Entergy Operations, Inc.
FACILITIES: Vogtle Electric Generating Plant, Units 1 and 2; Shearon Harris Nuclear Power Plant, Unit 1; and Grand Gulf Nuclear Station, Unit 1
SUBJECT:
SUMMARY
OF AUGUST 30, 2017 MEETING WITH NUCLEAR ENERGY INSTITUTE; DUKE ENERGY PROGRESS, LLC; SOUTHERN NUCLEAR OPERATING COMPANY, INC.; AND ENTERGY OPERATIONS, INC.; TO DISCUSS PILOT SUBMITTALS USING TORNADO MISSILE EVALUATOR METHODOLOGY (CAC NOS. MG0109, MG0110, MG0111, AND MG0112)
On August 30, 2017, the U.S. Nuclear Regulatory Commission (NRC) staff conducted a Category 1 public meeting with Duke Energy Progress, LLC (Duke Energy); Southern Nuclear Operating Company, Inc. (SNC); and Entergy Operations, Inc. (Entergy), at NRC'Headquarters, 11545 Rockville Pike, Two White Flint North, Rockville, Maryland. The purpose of the meeting was to discuss the NRC's efforts in support of the development of the Nuclear Energy lnstitute's (NEl's) Tornado Missile Risk Evaluation Tool. Revision 0 of NEI 17-02, "Tornado Missile Risk Evaluator (TMRE) Industry Guidance Document," was provided in support of a previous meeting and is available in the Agencywide Documents Access and Management System (ADAMS) under Accession No. ML17181A307. The licensees' presentations are available in ADAMS under Accession No. ML17255A108. An NRC staff methodology feedback document (ADAMS Accession No. ML17235B148) was also provided in support of this meeting.
BACKGROUND During a public meeting with the NRC staff on August 17, 2017 (ADAMS Accession No. ML17257A009), the NRC had a number of comments regarding Revision 0 of NEI 17-02. In most cases, the NRC staff requested additional detail for several topics, including spalling and shielding, be provided in the revised guidance. The NRC staff reiterated several concerns provided during the July 6, 2017 meeting (ADAMS Accession No. ML17207A064). In the area of de minimus penetration (de minimus), the guidance was still lacking sufficient justification to support the approach. Both SNC and Entergy indicated that their pilot submittals would not be crediting de minimus. Duke Energy indicated that one penetration was selected to exercise the methodology guidance. The NRC communicated again the concerns with the potential nonconservative effect of some conservative assumptions for estimating the base risk on estimating the change in risk. A focus of that conversation was the assumption that a loss of offsite power was nonrecoverable. The NRC staff also indicated its concern that the values in several tables in Section 7.0 and Appendix C of NEI 17-02 could not be validated. The industry indicated that for some of the tables, an effort was already underway to validate the values.
DISCUSSION The meeting opened with a few questions regarding the constraints pertaining to applicability of the TMRE methodology to system, structures, and components (SSCs). The licensees and the NEI representative confirmed that the approval being sought is intended to address current nonconformances/noncompliances. The methodology, if approved, would not be applicable to future changes to the facilities, including new structures. It was discussed that the nonconformances should be captured in the existing Appendix B of Part 50 to Title 1O of the Code of Federal Regulations corrective action program (CAP). As it was indicated previously that most of the pilot licensees had completed walkdowns to identify nonconformances/
noncompliances, the NRC staff questioned whether a process was in place to address missed existing nonconformances/noncompliances. It was indicated that like other nonconformances/noncompliances, the CAP would play a role to address any missing SSCs.
During the meeting, two of the pilot licensees presented information related to their pending submittals. The SNC indicated its intent to submit in late September 2017, then described the proposed submittal; provided background on the Vogtle Electric Generating Station (Vogtle}
tornado missile licensing and design bases and an example of exposed equipment failure probabilities for a component and quantification results, and highlighted those SSCs where nonconformances/noncompliances had been identified. The licensee indicated that for the Vogtle facilities, temporary missiles due to construction activities exceeded the number of missiles that were assumed generically for missile inventory in the methodology. Therefore, consistent with the methodology, a bounding site missile inventory was developed and applied to a site-specific tornado missile hazard curve. The licensee provided the results for the various tornado types by Fujita Prime (F'} intensity scale. The NRC staff questioned the large early release frequency results for the F'6 as the value was 0. The licensee indicated that the change in risk was below the truncation value. The NRC staff indicated a concern that this result was one example of the previously indicated concerns with conservatism in estimating the base risk that may lead to a nonconservative impact on the change in risk. It was also indicated that Vogtle would not be invoking the de minimus threshold to exclude any penetrations.
Duke Energy described the tornado missile licensing and design bases aspects of the proposed submittal for the Shearon Harris Nuclear Power Plant (Harris) facility, including example exposed equipment failure probabilities and quantification results. The NRC staff questioned a proposed revision to the Harris Final Safety Analysis Report, as updated, suggested that scope of the submittal that indicated an exception to compliance for SSCs was a "low importance to safety." It was recommended that the description be revised to better reflect the limitations of the application of the methodology as previously discussed. Additionally, the NRC staff indicated concerns with the suggestion that methodology would apply to future modifications.
Duke Energy indicated that it would take a look at the proposed language to ensure it was consistent with the TMRE methodology limitations. The licensee indicated that within the probabilistic risk model some issues were dispositioned as negligible impact consistent with standard probabilistic risk analysis practices and that those issues would be explicitly listed. It was indicated that Duke Energy saw no issues that would preclude submittal around late September - early October.
The NRC staff questioned the basis for treatment of short-term operator actions (i.e., those that need to be executed within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of the initiating event) and indicated a concern with nonconservative assumptions and the feasibility of those actions. There was also a question regarding whether the percentage of different missile types should be validated as those percentages could change the assumptions regarding the target robustness.
The NRC staff also emphasized some areas that would likely need additional detail and justification, including the nonrecoverable loss of offsite power assumption in Section A.2.1.1 of NEI 17-02. Another area was shielding. Both licensees indicated that work was still ongoing related to the approach to addressing the recovery actions related to a loss of offsite power.
Lastly, the NRC staff noted that there did not appear to be a definition of shielding nor was there comprehensive guidance within the methodology to ensure a consistent approach to crediting shielding.
Members of the public were in attendance. No public Meeting Feedback forms, nor comments were received.
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, 50-416, 50-424, and 50-425
Enclosure:
List of Attendees cc: Listserv
Attendees Nuclear Regulatory Commission Public Meeting Concerning Pilot Submittals of the Tornado Risk Evaluator Methodology August 30, 2017 U.S. NUCLEAR REGULATORY COMMISSION Greg Casto Robert Dennig Doug Broaddus Michael Markley G. Ed Miller Mike Orenak Nageswara Karipineni Gordon Curran Alex Schwab Mehdi Reisi Fard Siva Lingam Zeechang Wang Robert Kuntz Eva Brown EXTERNAL STAKEHOLDERS Alex Gilbreath, Southern Nuclear Operating Company, Inc.
Pat Chriscoe, Duke Energy Progress, LLC Melvin Arey, Duke Energy Progress, LLC Alex Holder, Duke Energy Progress, LLC Scott Brinkman, Duke Energy Progress, LLC James Hallenbeck, Entergy Operations, Inc.
Richard Harris, Enercon Ken McElroy, Southern Nuclear Operating Company, Inc.
Ken Lowery, Southern Nuclear Operating Company, Inc.
Stephen Vaughn, Nuclear Energy Institute Jana Bergman, Curtiss-Wright/Scientech John Caves, Duke Energy Progress, LLC Abul Hasanat, Entergy Operations, Inc.
Tim Dodson, Engineering Planning and Management Atwood Browning, Entergy Operations, Inc.
Ryan Sprengel, Exelon Nuclear Justin Huber, Southern Nuclear Operating Company, Inc.
Leo Shanley, Jensen Hughes Chris Riedl, Tennessee Valley Authority Brenda Simril, Tennessee Valley Authority Dana Millar, Entergy Operations, Inc.
..* ML17257A099 NRC-001 OFFICE NRR/DORL/LSPB/PM NRR/DORL/LSPB/LAiT NRR/DORL/LSPB/LA NAME EBrown IBetts JBurkhardt DATE 09/25/17 09/15/17 09/19/17 OFFICE NRR/DORL/LSPB/BC NAME DBroaddus (SWall for)
DATE 09/26/17