Development of a societal-risk goal for nuclear power safety

The safety-goal policy of the U.S. Nuclear Regulatory Commission (NRC) has never included a true societal-risk goal. In particular, safety goals have focused primarily on radiation-related fatalities, and instead only constrain on risks to individuals. Experience with actual nuclear accidents at Chernobyl and Fukishima has shown that even in accidents that yield only small numbers of fatalities, the extent of the societal disruption incurred to avoid possible radiological consequences can been significant, more so than the actual radiological consequences to the general public. We have evaluated the social disruption from severe reactor accidents as a basis to develop a societal-risk goal for nuclear plants, focusing on population relocation. Our analysis considers several different accident scenarios at five nuclear-plant sites in the U.S based on accident scenarios considered in the State of the Art Reactor Consequence Analysis (SOARCA) study. The corresponding source terms were used as input into the Radiological Assessment System for Consequence Analysis (RASCAL) software to calculate offsite consequences using actual weather data for each of the five plant sites over a two-year period. The resulting radiological plumes were then compared to population data to determine the population that would need to be relocated over a period of one year to meet current protective-action guidelines. Our results suggest that the number of people relocated is a good proxy for societal disruption, is an objective measure, and is relatively straightforward to calculate given current dispersion models and geographic information systems. Safety goals taking into account societal disruption could in principle be applied to the current generation of nuclear plants, but could also be useful in evaluating and siting new technologies.