Multiunit nuclear power plant accident scenarios and improvements including those based upon interviews with TEPCO engineers concerning the 2011 Fukushima accidents

In this work, we identify important multiunit risk factors based upon interviews with Tokyo Electric Power Company (TEPCO) engineers. These results provide first-hand information on multiunit risk factors that were important during the 2011 Fukushima accidents. Majority of the interviewees were involved in Fukushima Daiichi and Daini accident mitigation during March 2011. Interviewees worked at Daiichi and Daini sites and headquarters provided views of the accidents from different perspectives. They explained difficulties during the accident mitigation response phase due to lack of multiunit accident experience, and lack of necessary resources. In addition to the risk factors, corresponding site improvement suggestions are discussed based upon our reviews of the interview results. The identified risk factors and site improvement suggestions can be utilized as analysis subjects in future multiunit risk studies as well as references for nuclear sites to identify important multiunit risk vulnerabilities.