The US Nuclear Regulatory Commission (USNRC), together with the Electric Power Research Institute(EPRI) and the US Department of Energy (USDOE) today released details of a new model for calculating the seismic risk for Nuclear Power Plants (NPPs) in the Central & Eastern United States (C & E US). This replaces the EPRI Report NP-4276 Seismic Hazard Methodology for the Central and Eastern United States of July 1986; and the Lawrence Livermore National Laboratory Model, Seismic Hazard Characterization of 69 Nuclear Plant Sites East of the Rocky Mountains, (Bernreuter, D.L., et al., 1989, NUREG/CR-5250, Volumes 1–8), and is the result of a 4-year long joint EPRI-USNRC project to revise the ground motion estimates that can be expected at a given NPP location in the C&E US.
Speaking broadly, the new model results in a greater ground motion for a given NPP location, and the greatest increases in ground motion estimates have been obtained for nuclear power plants in the vicinity of the New Madrid (TN) and Charleston (SC) fault systems, based on a 7-plant sample selected for detailed study by the USNRC. The new, higher ground motion estimates do not by themselves translate to a higher nuclear safety risk for NPPs at those locations - each NPP must re- calculate its safety risk based on details of its own design and plant layout, relative to the enhanced ground motion risk it faces.
The USNRC is asking the NPPs it regulates to re-evaluate their seismic risk based on this new model, and the model will also be used in assessing the seismic risk for new nuclear plants in the region during the new licensing process. While the new seismic and ground motion risk estimates have been in development for the last several years, the Commission direction in this regard is also part of regulatory initiatives in response to the events at the Fukushima nuclear power plant following the Tohoku earthquake and tsunami-following, on 11 March 2011.
The USNRC is asking the NPPs it regulates to re-evaluate their seismic risk based on this new model, and the model will also be used in assessing the seismic risk for new nuclear plants in the region during the new licensing process. While the new seismic and ground motion risk estimates have been in development for the last several years, the Commission direction in this regard is also part of regulatory initiatives in response to the events at the Fukushima nuclear power plant following the Tohoku earthquake and tsunami-following, on 11 March 2011.
