The Nuclear Regulatory Commission has published a proposed rule that has been almost five years in the making: Risk-Informed, Technology-Inclusive Regulatory Framework for Advanced Reactors. The rule, which by law must take its final form before the end of 2027, would establish risk-informed, performance-based techniques the NRC can use to review and license any nuclear power reactor. This is a departure from the two licensing options with light water reactor–specific regulatory requirements that applicants can already choose.

Each month on the last Friday from 3:00 p.m. to 4:00 p.m. (ET), the American Nuclear Society’s Risk-informed, Performance-based Principles and Policy Committee (RP3C) holds a Community of Practice (CoP), which is open to all. On February 23, N. Prasad Kadambi, director of his eponymous engineering consultancy firm, presented “Technology-Inclusive Implications of ANSI/ANS-30.3-2022, Light Water Reactor Risk-Informed, Performance-Based Design.”

The American Nuclear Society has published the first voluntary consensus standard for nuclear reactor design that formally incorporates risk-informed, performance-based (RIPB) decision-making in July 2022. ANSI/ANS-30.3-2022, Light Water Reactor Risk-Informed, Performance-Based Design, tells reactor designers how they can incorporate RIPB principles and methods to ensure safety in new commercial light water reactor designs, and it includes a spectrum of options using both deterministic and risk-based approaches. As the first such standard, ANSI/ANS-30.3-2022 represents progress toward the adoption of RIPB principles for nuclear regulation and licensing—a shift the Nuclear Regulatory Commission was directed to make in the Nuclear Energy Innovation and Modernization Act, which became law five years ago.

Nuclear Safety Design Criteria and Functional Performance Requirements for Liquid-Fuel Molten Salt Reactor Nuclear Power Plants (ANSI/ANS-20.2-2023) has just been issued and is now available for purchase. It was developed by the American Nuclear Society and received approval from the American National Standards Institute (ANSI) on January 4.

By all accounts, 2022 brought many successes for the American Nuclear Society’s Standards Committee, including the initiation of five projects, reaffirmation of 11 current standards, and publication of seven new or revised standards. The entire collection of ANS current standards has been approved or reaffirmed (reapproved without change) by the American National Standards Institute (ANSI) within the past five years, keeping ANS in 100 percent compliance with ANSI’s requirement on maintaining current American National Standards. Also, the ANS standards program was reaccredited by ANSI on August 19, 2022, with the approval of a revised set of rules and procedures. ANS’s new rules and procedures take advantage of the opportunity to develop standards-related technical reports that may be registered with ANSI.

As the largest ultra-low-carbon electricity source in the United States, nuclear energy is a vital pillar of the effort to mitigate climate change. Deployment of advanced nuclear reactor and fuel technologies has been identified as a unique challenge in the production of new nuclear power plants to help maintain and grow our nuclear generating capacity. The licensing of novel nuclear reactor technologies also continues to be a facet of the broader challenge of advanced reactor deployment. When it comes to non–light water reactors and Generation III+ light water reactors, such as the AP-1000 or EPR, deployment is “2X over budget and behind schedule.”¹ However, in the case of recent large Generation III+ light water reactors, licensing has not been the rate-limiting step in the reactor deployment timeline, nor has it had a first-order impact on cost. With that said, several significant advances have been made in the expedition of licensing. This article focuses on three areas where progress has been made since this grand challenge was formulated in 2017, with highlights of some examples where the American Nuclear Society has guided or supported this progress.

The American Nuclear Society has recently published a new standard:

ANSI/ANS-30.3-2022, Light Water Reactor Risk-Informed, Performance-Based Design.

The standard is available for purchase from the ANS Store.

The ASME/ANS Joint Committee on Nuclear Risk Management (JCNRM) has achieved a significant milestone in the advancement of probabilistic risk assessment (PRA) technology. ANSI/ASME/ANS RA-­S-­1.4–2021 [1], Probabilistic Risk Assessment Standard for Advanced Non-­Light Water Reactor Nuclear Power Plants, has been approved by the JCNRM, the ANS Standards Board, the ASME Board of Nuclear Codes and Standards, and the American Nuclear Standards Institute.

Caroline Cochran, chief operating officer of Oklo Inc., and Sarah Bristol, PRA supervisor at NuScale Power, have given presentations recently for the American Nuclear Society’s Risk-informed, Performance-based Principles and Policy Committee (RP3C) Community of Practice (CoP).

Since the 1980s, the nuclear power industry in the United States has worked to enhance the regulatory framework for nuclear facilities by making it more risk-informed and performance-based (RIPB). This has had some success in improving safety and reducing regulatory burden by focusing resources on the most risk--significant areas and allowing greater flexibility in choosing ways to achieve desired safety outcomes. However, there are further opportunities for the use of RIPB approaches in addressing current regulations and applying implementation tools, and in developing new RIPB regulations and advanced tools to further sharpen the focus on risk and performance outcomes.