ASME Standard for Probabilistic Risk Assessment:
A Key Part of the Infrastructure for Risk-Informed
Regulation of Nuclear Power Plants
Dr. Shirley Ann Jackson, Chairman
U.S. Nuclear Regulatory Commission
March 16, 1999
Good morning. It is a pleasure to welcome the American Society for Mechanical Engineers (ASME), and all of you, as participants in this workshop on probabilistic risk assessment (PRA) standards. This effort is a major advancement for both the U.S. Nuclear Regulatory Commission (NRC) and the nuclear power industry. Your attendance confirms your belief in the significance of this activity, and I thank you for taking the time to participate in this important effort.
This effort is important for two reasons. First, a year and a half ago, as a direct output of the NRC Strategic Assessment and Rebaselining Initiative, the Commission requested the staff to interact more closely with industry and professional societies in developing standards rather than adopting new rules or regulations. This request was part of our Direction Setting Issue, DSI 13. This initiative also is consistent with recent Federal legislation that mandates greater reliance on consensus standards. The ASME volunteered to take on the responsibility of producing a standard for PRA as part of this initiative. The NRC Office of Nuclear Regulatory Research has worked closely with the ASME in this effort.
I would note that some concern existed at that time over whether a draft standard could be completed in the time frame desired. To meet the aggressive schedule proposed by the NRC, the ASME utilized a redesigned consensus process-and the result has been a success. A year later, here we are-the draft standard has been issued for public review and comment. The ASME Project Team has done an outstanding job in meeting this schedule. This collaborative effort between the ASME and the NRC is an excellent example of what can be accomplished cooperatively when the staff and a standards organization strive to achieve common goals. My congratulations to the team!
Second, I would like to point out that, over the last several years, we have been moving more and more towards risk-informed regulation. We have achieved numerous milestones in this area. The issuance of the regulatory guides and standard review plans last year was a major advancement in risk-informed regulation. We currently are redesigning our assessment, inspection, and enforcement process, and considering a broad-scope modification to risk inform our reactor regulations in 10 CFR Part 50. These are significant activities that will have long-lasting and far-reaching impacts on how the NRC regulates. In each of these activities, the single most important concern continually raised by the Commission is the question of PRA quality. As you well know, a PRA for a reactor is a major engineering analysis involving numerous disciplines: thermal-hydraulic analyses, systems analyses, and data analyses, to name just a few. A PRA is costly to perform and costly to review. Therefore, a standard that ensures the quality and consistency of a PRA will be of key importance in helping to ensure an effective and efficient risk-informed regulatory system.
This is our goal - to have a standard that defines PRA quality. With such a standard, it is expected that the consistency of submittals will improve and that the need for extensive NRC review will reflect this. The draft standard produced by the ASME provides the requirements for a reference PRA, documentation, configuration control, and peer review of the PRA. This standard also recognizes that the requirements of a PRA are application dependent. Consequently, the standard also includes criteria for determining the extent to which the reference PRA requirements are necessary and sufficient to support a particular risk-informed application.
I invite each of you to participate fully in the workshop today. Your views are essential to the success of this endeavor. With a standard that defines a quality PRA, we will accomplish more quickly the goals of the Commission PRA Policy Statement, improving the regulatory process through (1) safety decision-making enhanced by the use of PRA insights, (2) more efficient use of agency resources, and (3) a reduction in unnecessary burden on our licensees.
We must not stop, however, with the completion of this standard. Although congratulations definitely are in order, we can not "call it a day and go home." This standard only addresses internal events at full power operation for a Level 1 and a limited Level 2 PRA. It does not cover a full Level 2, internal fires, external events, or low power and shutdown operations. The same vigor needs to be applied in the next phase, in producing a standard for these missing pieces. I understand that the American Nuclear Society has developed a proposal in this regard. As such, we are only halfway there. The glass definitely is "half full," but we need to top it off! The Commission looks forward with great anticipation, this same time next year, for a draft of Phase 2.
I wish you a productive workshop. I reiterate my congratulations to the ASME and to the NRC Office of Nuclear Regulatory Research for achieving this significant milestone in advancing risk-informed regulation. I look forward to the final publication of this standard.