The balance between safety and productivity: RIPB design

Some background: RP3C is a special committee created by the ANS Standards Board to provide guidance to ANS standards committees on the use of risk-informed, performance-based (RIPB) methods. The CoP is part of RP3C’s charter, which includes training and knowledge-sharing of RIPB principles to exchange ideas outside of the normal management and project process. CoPs are used frequently by organizations to help break down barriers that impede the flow of information.

The speaker: RP3C chair N. Prasad Kadambi opened the CoP with brief introductory remarks about the committee and the need for new approaches to nuclear design that go beyond conventional and deterministic methods before he welcomed this month’s speaker, Paul Amico, who presented "RIPB Design Approaches for Enhanced Safety and Reliability in New Nuclear." A nuclear engineer with 50 years of experience in the industry, Amico is an independent consultant at Jensen Hughes, a professional engineering and consulting company that has worked with the entire U.S. nuclear fleet as well as plants around the world.

Virtues of RIPB: Jensen Hughes puts RIPB-based design at the center of their nuclear work in order “to achieve the intent of the codes and standards rather than just going in and blindly meeting them,” Amico said. This focus, for Amico, is the best way to efficiently ensure regulatory compliance and achieve risk reduction with respect to safety, security, and operational resilience.

In addition to being championed by consulting firms like Jensen Hughes, there has been a surge in interest in RIPB design from offtakers—companies like Amazon, Microsoft, and Dow—that require a consistently available and reliable source of energy for potentially behind-the-meter projects like data centers.

Amico explained that these companies are not worried about safety, as they are convinced that nuclear is safe, low-carbon, and good for the environment. But they are not yet convinced that nuclear can provide the kind of reliability they need to make it worth in the investment. The prospect of having to buy replacement power or manage unexpected repair costs is often financially infeasible, “so there needs to be a balance achieved that optimizes both safety goals and production goals, and the best way to do that is with a risk-informed, performance-based approach.”

To make this connection between safety and performance more concrete, Amico provided data showing nuclear’s increase in average capacity factors over the past 30 years, which correlates with an increase in safety performance in the same time frame.

The tools: Amico walked through the RIPB process flow from a baseline plant design to a final design plan, highlighting a number of key tools and processes used to strike the desired balance between safety and production goals.

Two complementary tools that speak to both sides of that balance are the probabilistic risk assessment (PRA) and generation risk assessment (GRA). While PRA is used to model safety impacts and provide importance rankings for safety concerns, GRA explores the production side, in part by estimating the risk of generation loss during plant operation. These generation losses can fall outside of the scope of a PRA because they do not necessarily coincide with a safety issue but will inevitably impact production efficiency. So, using both assessments in concert with each other leads to a plant that is both productive and safe, which is the fundamental goal of RIPB design.

Go deeper: Amico’s full presentation, where he explains a variety of tools used in the RIPB-based design process, can be watched on the ANS Standards YouTube channel.

Slides and recordings from previous presentations are available on the RP3C page on ANS’s website. Individuals interested in RP3C membership or joining one of the monthly CoP presentations are encouraged to contact standards@ans.org.