ML20289A570
| ML20289A570 | |
| Person / Time | |
|---|---|
| Issue date: | 10/15/2020 |
| From: | Antonios Zoulis NRC/NRR/DRA |
| To: | Mike Franovich Office of Nuclear Reactor Regulation |
| Kichline M | |
| Shared Package | |
| ML20289A715 | List: |
| References | |
| Download: ML20289A570 (5) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 October 15, 2020 MEMORANDUM TO: Michael X. Franovich, Director Division of Risk Assessment Office of Nuclear Reactor Regulation FROM:
Antonios Zoulis, Chief /RA/
PRA Oversight Branch Division of Risk Assessment Office of Nuclear Reactor Regulation
SUBJECT:
SUMMARY
OF U.S. NUCLEAR REGULATORY COMMISSION STAFF PARTICIPATION IN THE SEPTEMBER 2020 VIRTUAL FLEX SUMMIT HOSTED BY THE NUCLEAR ENERGY INSTITUTE This memorandum summarizes the U.S. Nuclear Regulatory Commission (NRC) staffs participation in a five-day summit on various topics related to implementation of diverse and flexible coping strategies (FLEX). The summit was held virtually as five webinar sessions conducted September 1-3 and 9-10, 2020. The FLEX Summit was hosted by the Nuclear Energy Institute (NEI) and was attended by representatives from numerous utilities and industry stakeholder groups as well as a diverse set of NRC staff from the Offices of Nuclear Reactor Regulation, Nuclear Regulatory Research, and the regions. Approximately 200 NRC staff and industry members participated in the summit. A copy of the FLEX Summit agenda is included as Enclosure 1. The NRC staff provided presentations in Session 1 for FLEX background and expanded use, Session 2 for FLEX operating experience (OpE), Session 4 for FLEX in licensing and oversight, and Session 5 for modeling FLEX in station probabilistic risk assessments (PRA).
The FLEX Summit provided a platform to reach a common understanding on various FLEX-related topics, such as proper implementation of FLEX strategies, OpE, knowledge management, and expanded use of FLEX to improve safety and operational flexibility. In addition, the FLEX Summit included a discussion of the treatment of FLEX in PRA models to support NRC licensing and oversight. Specific presentations by NRC staff included: the history of Title 10 of the Code of Federal Regulations (10 CFR) Section 50.155, Mitigation of Beyond-Design-Basis Events; NRCs crediting FLEX effort; NRCs perspectives on FLEX OpE; crediting FLEX in risk-informed licensing applications, the Significance Determination Process (SDP) for FLEX findings; and NRCs audit results for the Pressurized Water Reactor Owners Group (PWROG) FLEX data collection and analysis report. The FLEX Summit also featured a joint presentation on common ground in human reliability analysis (HRA) for FLEX which included an open dialogue on NRC and Electric Power Research Institute (EPRI) HRA methods currently available and the lessons learned from EPRI and NRC FLEX HRA efforts.
CONTACTS: Michelle Kichline, NRR/DRA Kristy Bucholtz, NRR/DRA 301-415-3153 301-415-0961
M. Franovich Session 1, FLEX Background and Expanded Use, discussed the evolution of FLEX. In this session, the NRC staff discussed the history behind the development of 10 CFR 50.155, starting from the occurrence of the earthquake in Japan in 2011. This presentation is included as. A utility representative provided information about the development of NEI 12-06, Diverse and Flexible Coping Strategies (FLEX) Implementation Guide. The NRC staff discussed the efforts made to provide credit for FLEX in regulatory decisions and the associated challenges. This presentation is included as Enclosure 3. Utility representatives discussed the industrys efforts to optimize the use of FLEX and where its use could be expanded to gain additional safety benefits. Significant work has been accomplished by the NRC and the industry to credit the use of FLEX, as evidenced by the many regulatory applications that have been approved with FLEX credit. However, there are two remaining technical challenges - FLEX reliability data and HRA for FLEX - on which the NRC and industry are nearing resolution.
Session 2, FLEX OpE, discussed the efforts to improve the sharing of FLEX OpE to ensure nuclear stations appropriately learn from FLEX failures throughout the industry and continually improve FLEX preventative maintenance (PM) strategies. In this session, utility representatives discussed the lessons learned from recent FLEX failures and their associated causes. A representative from Energy Harbor discussed the establishment and purpose of the FLEX PM Subgroup as the primary industry interface with EPRI. A representative of EPRI discussed the products that are available from EPRI for collaborating and benchmarking FLEX PM strategies and OpE. A representative from NEI discussed enhancements to the process for sharing FLEX OpE. Lastly, the NRC staff provided the NRCs perspectives on FLEX OpE and conveyed that an information notice is under development on this topic. The NRCs presentation on this topic is included as Enclosure 4. Subsequent to the FLEX Summit, Information Notice 2020-02, FLEX Diesel Generator Operational Challenges, was issued (Agencywide Document Access and Management System [ADAMS] Accession No. ML20196L822).
Session 3, Enhancing Safety in FLEX Operations and Maintenance Activities, discussed industrys exploration of strategies to enhance safety by using FLEX equipment to supplement operator responses to emergency situations and lower the stations risk profile during online and shutdown maintenance activities. In this session, a PWROG representative discussed the existing use of FLEX in PWR emergency operating procedures and identified improvements that can be gained from FLEX. Boiling Water Reactor (BWR) Owners Group representatives discussed the existing use of FLEX in BWR station procedures such as, emergency operating and severe accident guidelines. A utility representative discussed Exelons BlackStarTechTM rapidly deployable portable battery powered coping system. A Duke Energy representative discussed the available FLEX equipment, its incorporation into PRA models, its use, and the lessons learned at their plant sites.
Session 4, FLEX in Licensing and Oversight, discussed the NRCs and licensees experience with crediting FLEX equipment in risk-informed license amendment requests and oversight activities. In this session, the NRC staff discussed the NRCs regulatory history with crediting FLEX in licensing, the review process, and informational needs for crediting FLEX in risk-informed license amendment requests. The NRCs presentation on this topic is included as. The NRC discussed that incorporation of FLEX into PRA models used for risk-informed applications continue to be a topic of interest during licensing reviews, as it may constitute a key assumption or source of uncertainty that could impact the regulatory decision.
The NRC staff discussed that it looks forward to continuing engagement with the industry in
M. Franovich order to streamline licensing reviews. A utility representative discussed FLEX information provided in risk-informed applications and in PRA. Also, in this session, the NRC staff discussed the SDP screening questions in Inspection Manual Chapter 0609 Appendix A, The Significance Determination Process for Finding At-Power, and illustrated their use in tabletop exercises. The NRCs presentation on the SDP for FLEX findings is included as Enclosure 6.
Utility representatives provided an industry perspective on the treatment of FLEX findings in the SDP.
Session 5, Modeling FLEX in Station PRAs, discussed the various approaches available to model the human actions needed to successfully implement FLEX strategies in different contexts. In addition, this session discussed the results from the collection and analysis of FLEX portable equipment failure data and how it should be used to support modeling FLEX in PRAs. In this session, a PWROG representative discussed the Owners Groups efforts to collect and analyze FLEX portable equipment failure data and provided an overview of the equipment reliability results from their draft report, PWROG-18043-P, Revision 0, FLEX Equipment Data Collection and Analysis. The NRC staff discussed the results of the Staffs audit of the PWROG draft report PWROG-18043-P, Revision 0. This presentation is included as Enclosure 7. The NRC audit identified some concerns which were documented in an audit report issued June 10, 2020 (ADAMS Accession No. ML20155K827). The PWROG committed to provide a revised version of the report for NRC review in early 2021. Additionally, a utility representative discussed the insights from crediting FLEX strategies in the loss of all alternating current emergency operating procedures in Southern Nuclear PWR PRAs. A PWROG representative presented a comparison of human error probability results for a few typical FLEX actions obtained using the EPRI HRA Calculator and the NRCs Integrated Human Event Analysis System for Event and Condition Assessment (IDHEAS-ECA) HRA methods. The NRC staff and a representative of EPRI discussed the common ground on FLEX HRA and the lessons learned from EPRI and NRC FLEX HRA efforts. This presentation is included as. The presentation identified that there is substantial common ground between NRC and EPRI regarding FLEX HRA. The FLEX HRA using IDHEAS-ECA effort resulted in a greater understanding of FLEX strategies and equipment and found that IDHEAS-ECA produced reasonable results for the scenarios addressed. Going forward, the NRC plans additional coordination with EPRI to resolve the differences between the NRC and industry HRA methods for FLEX.
The NRC staff considered the FLEX summit to be a tremendous success that will help improve the efficiency and effectiveness of crediting FLEX in licensing reviews and its consideration in oversight activities. This workshop helped advance NRR and agency efforts to increase the use of risk-informed decision-making through enhancing the common understanding on the various FLEX related topics. This workshop supported a foundation for continued communication and advancement of FLEX in licensing and oversight. The NRC looks forward to continued engagement with external stakeholders to streamline the licensing reviews of risk-informed license amendment requests that include credit for FLEX, and to enhance the realism involved in modeling FLEX in PRAs, especially in the areas of equipment reliability data and HRA.
The enclosures to this memorandum include the FLEX Summit agenda and the NRC staffs FLEX Summit presentations.
Enclosures:
M. Franovich
- 1.
FLEX Summit Agenda (ADAMS Accession No. ML20289A645)
- 2.
NRC Presentation on History of 10 CFR 50.155 (ADAMS Accession No. ML20289A650)
- 3.
NRC Presentation on NRCs Crediting FLEX effort (ADAMS Accession No. ML20289A658)
- 4.
NRC Presentation on FLEX Operating Experience NRC perspectives (ADAMS Accession No. ML20289A671)
- 5.
NRC Presentation on Credit for FLEX in Risk-Informed Licensing Applications (ADAMS Accession No. ML20289A678)
- 6.
NRC Presentation on Significance Determination Process for FLEX Findings (ADAMS Accession No. ML20238B980)
- 7.
NRC Presentation on NRCs Audit Results for the PWROGs FLEX Data Collection and Analysis Report (ADAMS Accession No. ML20289A694)
- 8.
Combined NRC/EPRI Presentation on Common Ground on FLEX HRA (ADAMS Accession No. ML20289A710)
M. Franovich
SUBJECT:
SUMMARY
OF U.S. NUCLEAR REGULATORY COMMISSION STAFF PARTICIPATION IN THE SEPTEMBER 2020 VIRTUAL FLEX SUMMIT HOSTED BY NUCLEAR ENERGY INSTITUTE DISTRIBUTION:
PUBLIC RidsNrrDra Resource ADAMS Package Accession: ML20289A715 Office NRR/DRA/APOB NRR/DRA/APOB BC:DRA/APOB Name KBucholtz MKichline AZoulis Date 10/8/20 10/8/20 10/15/20 OFFICIAL RECORD COPY