Tsunami PRA for Japan Sodium-Cooled Fast Reactor - 14107

After the TEPCO's Fukushima Daiichi nuclear power station accident, Probabilistic Risk Assessment (PRA) is recognized as an important method for safety assessment for tsunami. The many electric power companies in Japan are considering introduction of water tight door as one of measures against the tsunami for the LWRs. Japan Atomic Energy Agency (JAEA) has been conducting conceptual design study of Japan Sodium-cooled Fast Reactor (JSFR) and is also considering introduction of water tight door for JSFR. For this consideration for the JSFR, it is necessary to implement the PRA and to assess the effectiveness of the water tight door from the view point of Core Damage Frequency (CDF). This study implemented the tsunami PRA for JSFR and assessed effectiveness of the watertight structures with/without which cases were compared from the view point of the CDF. For this assessment, this study identified initiating events and analyzed accident scenarios after researching important structures and components related to the decay heat removal system. And this study calculated the CDF and identified dominant sequence contributing to the CDF. The CDF in the case having the watertight structures was approximately 1/10 times lower than that in the case without those. From the result, this study showed the effectiveness of watertight structures on the reactor building, quantitatively. (authors)