ML23138A394
| ML23138A394 | |
| Person / Time | |
|---|---|
| Issue date: | 06/14/2023 |
| From: | Michele Sampson NRC/RES/DE |
| To: | Eggett D, Vogan T ASME Board on Nuclear Codes and Standards, American Nuclear Society (ANS) |
| References | |
| Download: ML23138A394 (4) | |
Text
June 14, 2023 Thomas Vogan, Chair ASME Board on Nuclear Codes and Standards (BNCS)
Two Park Avenue New York, NY 10016-5990 Don Eggett, Chair American Nuclear Society American Nuclear Society 555 N. Kensington Avenue La Grange Park, IL 60526
SUBJECT:
THIS LETTER IS TO COMMUNICATE TO THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS AND THE AMERICAN NUCLEAR SOCIETY THE U.S. NUCLEAR REGULATORY COMMISSION VIEWS WITH REGARD TO THE PROBABLISTIC RISK ASSESSMENT STANDARDS THAT ARE BEING DEVELOPED AND MAINTAINED BY THE ASME/ANS JOINT COMMITTEE ON NUCLEAR RISK MANAGEMENT.
Dear Mr. Vogan and Mr. Eggett:
The U.S. Nuclear Regulatory Commission (NRC) values the productive relationship we have established with the American Society of Mechanical Engineers (ASME) and American Nuclear Society (ANS) in support of the development of probabilistic risk assessment (PRA) consensus standards. The PRA consensus standards developed under the auspices of the ASME/ANS Joint Committee on Nuclear Risk Management (JCNRM) have been a key enabler to the success of the NRCs licensing and risk-informed regulatory programs and have resulted in improvements to safety and increased the efficiency of our regulatory programs. Currently, several PRA standards are being developed and maintained by the ASME/ANS JCNRM that are of great interest to the NRC.
These standards include:
ASME/ANS RA-S-1.1-2022: The new edition for the Level 1/Large Early Release Frequency (LERF) PRA standard addresses at-power conditions and all hazards for light water reactors (LWRs). This new edition was finalized in 2022 and issued as an American National Standard Institute (ANSI) standard. The NRC appreciates the ASME/ANS JCNRMs effort in developing and publishing this standard. Staff is considering the endorsement of this standard, with appropriate clarifications or qualifications, as one of the main elements of next revision to Regulatory Guide (RG) 1.200, Acceptability of Probabilistic Risk Assessment Results for Risk-Informed Activities.
T. Vogan, D. Eggett 2 ASME ANS RA-S-1.2: The Level 2 PRA standard addresses all operating modes and hazards for LWRs. This standard has been issued for trial use, has undergone pilot applications (one pilot being the NRC Level 3 PRA project) and is being finalized to be issued as an ANSI standard. The NRC considers the completion of this standard to be a medium priority because of the plans to endorse, with appropriate clarifications or qualifications, in the next revision of RG 1.200 to support future regulatory activities and the expectation that the standard can be finalized without a substantial amount of additional work. To better support ongoing regulatory guidance development, issuance of the final standard in 2023 would be most useful to the agency.
ASME/ANS RA-S-1.3: The Level 3 PRA standard addresses all operating modes and hazards for LWRs. This standard has been issued for trial use and is currently being piloted (one pilot being the NRC Level 3 PRA project). Based on the current scope of the NRCs endorsement efforts, the NRC considers the completion of this standard to be a low priority.
ASME/ANS RA-S-1.4-2021: The non-LWR PRA standard addresses all operating modes, hazards, mechanistic source terms, radiological consequences, and risk integration for design, preconstruction, pre-operation, and operating stages. This standard has been issued as an ANSI standard. The NRC appreciates the ASME/ANS JCNRMs effort in developing and publishing this standard. This standard has been endorsed with clarifications or qualifications for trial use in RG 1.247, Acceptability of Probabilistic Risk Assessment Results for Advanced Non-Light Water Reactor Risk-Informed Activities.
ASME/ANS RA-S-1.5: The Level 1/Level 2 PRA standard addresses advanced LWRs during preconstruction and preoperational stages. The NRC considers the completion of this standard to be a high priority because this standard supports future NRC staff reviews and is planned to be endorsed, with appropriate clarifications or qualifications, in the next revision to RG 1.200. The high priority is based on the projected 2024 publication date and the potential for impacts on the NRCs RG 1.200 revision effort. To better support ongoing regulatory guidance development, issuance of the final standard by 2024 would be most useful to the agency.
ASME/ANS RA-S-1.6: The Level 1/LERF PRA standard addresses low-power and shutdown conditions for both internal and external hazards for LWRs. This standard was issued for trial use in 2014, has undergone pilot applications and is in the process of being finalized as an ANSI standard. The NRC considers the completion of this standard to be a high priority because of the plans to endorse this standard, with appropriate clarifications or qualifications, in the next revision of RG 1.200 to support future NRC staff reviews of new light water reactor applications, including small modular reactors.
The high priority is based on the projected 2024 publication date and the potential for impacts on the NRCs RG 1.200 revision effort. To better support ongoing regulatory guidance development, issuance of the final standard by 2024 would be most useful to the agency.
ASME/ANS RA-S-1.7: The Level 1/Level 2/Level 3 PRA standard addresses all operating modes and hazards for multi-unit PRA models. Based on the current scope of the NRCs endorsement efforts, the NRC considers the completion of this standard to be a low priority.
T. Vogan, D. Eggett 3 These standards are important to the NRC, industry, and other stakeholders since they facilitate risk-informed activities and give the needed confidence that the results from a PRA can be used in the associated activity. Therefore, the publication of robust standards in a timely manner will help stakeholders better plan and incorporate these standards in risk-informed activities.
With regard to risk-informed activities, for operating reactors, numerous activities are ongoing.
Similarly, for advanced LWRs and non-LWRs, numerous risk-informed activities are anticipated.
These standards are instrumental to sustaining the NRC as a modern risk-informed regulator.
As such, the NRC will continue to support JCNRM to help ensure an effective path forward in issuing the above standards.
If you have any questions, please contact Matthew Humberstone who is the NRC representative on the JCNRM, or his alternate, Jeffery Wood. You can reach them at, 301-415-1464 (matthew.humberstone@nrc.gov) and 301-415-0953 (jeffery.wood@nrc.gov), respectively.
Sincerely, Signed by Sampson, Michele on 06/14/23 Michele Sampson, Director NRC Standards Executive Division of Engineering Office of Nuclear Regulatory Research cc: Kathryn Hyam, ASME Oliver Martinez, ASME JCNRM Patricia Schoeder, ANS JCNRM Rick Grantom, ASME JCNRM Dennis Henneke, ANS JCNRM
ML23138A394; Ltr ML23138A394 OFFICE RES/DRA/PRB RES/DRA NRR/DRA NSIR/DPCP/RSB CAraguas NAME MHumberstone MH MFranovich MF MSampson MS VHall for VH DATE May 19, 2023 May 26, 2023 Jun 1, 2023 Jun 14, 2023