Nuclear Regulatory Commission: Natural Hazard Assessments Could be More Risk-Informed, Report to Congressional Requesters [open pdf - 0B]
"On March 11, 2011, an earthquake triggered a tsunami wave that exceeded the seawall at Japan's Fukushima Daiichi nuclear power plant, leading to the release of radioactive material into the environment. The disaster raised questions about the threats that natural hazards, such as earthquakes and floods, may pose to U.S. commercial nuclear power reactors. NRC [Nuclear Regulatory Commission] licenses and regulates U.S. nuclear power reactors. NRC criteria for licensees to assess natural hazards were developed using an approach that required reactors to be designed according to a set of potential accidents using deterministic analysis. Since the 1990s, NRC has been encouraging the use of PRA [Probabilistic Risk Assessment] as part of a risk-informed, performance-based approach. GAO [Government Accountability Office] was asked to (1) determine the extent to which PRA is applied to natural hazards at operating U.S. reactors and (2) describe expert views on and suggested changes, if any, to NRC processes for assessing natural hazards at such reactors. GAO reviewed documents; analyzed responses from 15 experts in assessing nuclear reactor risks and/or natural hazards; visited five selected nuclear power plants; and interviewed NRC officials and industry and public interest group representatives. […] GAO recommends that NRC analyze whether licensees of operating reactors should be required to develop PRAs that address natural hazards. NRC agreed with the recommendation and stated it will conduct the analysis in the context of ongoing initiatives."
Government Accountability Office: http://www.gao.gov/