The nuclear energy industry and the U.S. Nuclear Regulatory Commission meet May 11th to provide the commissioners with the status of initiatives being implemented by both the agency and industry in risk-informed regulation.
Up until the mid-1990s, the NRC's nuclear safety regulations were traditionally deterministic which means they only asked what could go wrong with nuclear systems and what the consequences are. However, the agency began moving toward risk-informed regulation, which additionally asks how likely a given accident or accident sequence is to occur combining the probability of an event with its likely consequence gives a measure of its risk.
The agency published a policy statement on the use of probabilistic risk assessment (PRA) in 1995. In the first 10 years since then, the increasing use of risk-informed regulation and operations has substantially improved both the industry's and the regulator's efficiency and demonstrably increased safety.
The use of risk-informed regulation has shown success in the area of technical specifications, where risk insights have been used to better decide the way equipment is tested and maintained at reactor sites. The industry also is making use of risk information in integrating its post-Fukushima FLEX emergency equipment in day-to-day operations. The average industry investment in risk-informing its operations is $15 million to $20 million per reactor site.
However, since the initial progress made under the PRA policy statement, further advancements have slowed.
The May 11 commission briefing is an effort by both the industry and the regulator to ensure those early results continue to be seen. Among the opportunities for improvement that the industry has identified include:
- increasing realism in probabilistic risk assessments (PRAs)
- moving toward use of insights in decision-making rather than undue reliance on numerical results
- more consistent use of risk-informed thinking in regulation, including among some NRC technical branches whose regulatory work is more deterministic in nature, and
- focusing and aligning resources to support industry applications.
Speaking at the NRC's 2017 Regulatory Information Conference in March, NRC Chairman Kristine Svinicki conceded that there may be some cultural resistance among some NRC staff to fully embrace risk-informed approaches to regulation. She said the move to risk-informed regulation will be "a continual evolution" for the NRC.
"I know it requires a paradigm shift but I think it's not a question of if we can become comfortable as a regulator it's when. We need to be able to develop workable paradigms for that," Svinicki said.