ML19011A139
| ML19011A139 | |
| Person / Time | |
|---|---|
| Issue date: | 01/11/2019 |
| From: | Ching Ng NRC/NRR/DRA/APOB |
| To: | Cj Fong NRC/NRR/DRA/APOB |
| Ng C | |
| References | |
| Download: ML19011A139 (4) | |
Text
January 11, 2019 MEMORANDUM TO:
Christopher J. Fong, Chief PRA Oversight Branch Division of Risk Assessment Office of Nuclear Reactor Regulation FROM:
Ching H. Ng, Reliability & Risk Analyst
/RA/
PRA Oversight Branch Division of Risk Assessment Office of Nuclear Reactor Regulation
SUBJECT:
SUMMARY
OF THE DECEMBER 12, 2018, PUBLIC MEETING BETWEEN THE UNITED STATES NUCLEAR REGULATORY COMMISSION AND INDUSTRY REPRESENTATIVES REGARDING ITS COMMON CAUSE FAILURE PROPOSAL On December 12, 2018, a Category 2 public meeting was held between the U.S. Nuclear Regulatory Commission (NRC) staff and external stakeholders, at One White Flint North, in Room O11-B04. The purpose of the meeting was to discuss the staffs comments regarding the industrys proposal on common cause failure (CCF) analysis and its use in the significance determination process (SDP).
The NRC began the meeting with an overall summary of their current comments and concerns about the white paper Nuclear Energy Institute (NEI) had submitted, which detailed NEIs proposal for how to address CCF impact. As indicated in the presentation, Common Cause Failure (ADAMS Accession No. ML18346A547) the staffs comments included (1) current CCF quantitative assessment and its bases are well-documented and supported by empirical data; (2) defenses against CCF are already a standard licensee practice and their effectiveness is empirically reflected in the current data collection; (3) additional credit for CCF defense strategies should only be considered for cases that go beyond traditional practices (and these would be difficult to define); and (4) the NRCs current CCF approach makes some simplifications (e.g., omission of inter-system dependencies) that should also be addressed.
The NRC staff indicated that NURE-2225, Basis for the Treatment of Potential Common-Cause Failure in the Significance Determination Process (ADAMS Accession No. ML18274A198) contains the technical bases of the staffs treatment of CCF in the SDP.
The NEI gave their presentation, Common Cause Failure Impact within the SDP (ADAMS Accession No. ML18348A631) by stating that their goal with the whitepaper was to focus on qualitative factors when the impact of CCF in the SDP evaluation is significant. The industry representative indicated that the data used by the NRC and the Idaho National Laboratory (INL) to calculate the alpha factors maybe dated. The NRC Staff from the Office of Nuclear Regulatory Research (RES) responded and explained that the data is ranged from 1990s to present.
CONTACT: Ching H. Ng, NRR/DRA 301-415-8054
C Representatives from industry reiterated past comments that the current CCF alpha-factor model methodology is technically sound and acceptable for use per the American Society of Mechanical Engineers (ASME) PRA standard. Industry comments were that the use of the method may be conservative during detailed risk assessments conducted under the SDP.
Industry representatives also indicated that licensees have taken measures to reduce CCF (maintenance crew changes, staggered testing, etc.) but its unclear if the benefit has been reflected in the current alpha-factor data gathered by INL. An NEI representative stated that they will develop a list of CCF defense strategies that are employed by utilities and provide the information to the staff.
Informed by the insights gained from stakeholders interactions, the staff in NRR, pending management approval, may request RES to examine the quantitative aspect of causal alpha factors. The causal alpha factors method would categorize the effects of CCF based on the cause of the failure. In addition, RES staff would evaluate whether the current alpha factors used in the SPAR models accurately reflect existing industry practices designed to prevent CCF. The staff also indicated that to the extent practicable, the staff intends to share the results of the casual alpha factors study with industry and other stakeholders.
During the meeting, the attendees were reminded that although their comments were discussed with the staff, no decisions would be made at the meeting.
A list of meeting attendees is enclosed.
Enclosure:
Attendance List
ML19011A139 NRR-106 OFFICE NRR/DRA/APOB NRR/DRA/APOB: BC NAME CNg CFong DATE 01/11/2019 01/11/2019
Enclosure ATTENDANCE LIST PUBLIC MEETING BETWEEN THE UNITED STATES NUCLEAR REGULATORY COMMISSION AND INDUSTRY REPRESENTATIVES TO DISCUSS INDUSTRYS PROPOSAL RELATING TO COMMON CAUSE FAILURE IMPACT (CATEGORY 2)
December 12, 2018 1:00 p.m. - 3:00 p.m.
ONE WHITE FLINT NORTH, O11-B04
- participated via teleconference NAME ORGANIZATION Christopher J Fong NRC Jason Paige NRC Felix Gonzalez NRC Antonios Zoulis NRC Chris Hunter NRC Jeff Mitman NRC Ching Ng NRC Dale Yeilding NRC Fernando Ferrante EPRI Steve Vaughn NEI Jeff Stone Exelon Gene Kelly Exelon Jana Bergman Curtiss-Wright Laura Kozak*
NRC Anne Ward*
Xcel Energy Donald Helton*
NRC Leonard Sueper*
Xcel Energy Harry Balian*
PSEG Andrew Bittlemann*
Jensen Hughes Erik Shaw*
Jensen Hughes Jeff Seiter*
Entergy