The role of risk aversion in nuclear plant safety decisions

• USNRC is risk-averse toward risk from core damage of nuclear plant caused by fire.
• USNRC is more risk-averse for issuing a specific rule than for a general guideline.
• Risk attitudes toward radiation exposure vary from country to country.
• Benefit to cost ratio does not fully reflect a risk attitude of a decision maker.

Risk to civil infrastructure facilities from extreme natural and manmade hazards is characterized by involuntary exposure and potentially severe consequences to the public. Individuals and the public tend to overstate involuntary risks that are poorly understood or involve the possibility of fatalities. Such exaggerations of risk perception influence policy-making and the development of appropriate strategies for mitigating and managing the risk. Regulatory decision-making for nuclear power plant safety represents a case that is affected by exaggerated risk perception caused by fear. The recent meltdowns at the Fukushima Daiichi Plant in Northeast Japan in March 2011 reinforced such fears and fueled opposition to the further development of nuclear power as a solution to the nation's growing energy demands. In this paper, we analyze the US Nuclear Regulatory Commission (NRC)'s regulations regarding to the operation of nuclear power plants utilizing a decision model known as cumulative prospect theory (CPT), which permits risk-averse behavior to be modeled in assessing both likelihoods and consequences of a hazardous event. The investigation is extended to different requirements that are influenced by the International Commission on Radiological Protection for an international perspective. Finally, we consider how risk attitudes can be incorporated in future decisions with an example of retrofitting Browns Ferry Nuclear Plant in accordance with the Severe Accident Mitigation Alternatives stipulated by the USNRC.