Response to the Seawater Contamination Event at Hamaoka Unit 5 and the Effects of Corrosion by Seawater

Hamaoka Nuclear Power Station Unit 5 is an advanced boiling water reactor with a generating capacity of 1.38 GW. It was shut down on May 14, 2011 at the request of the Minister of Economy, Trade and Industry. Seawater contaminated the equipment in a wide range of locations. We promptly cleaned up the reactor water and conducted an impact assessment and integrity evaluation of the equipment. The contamination areas were mainly categorized into the reactor pressure vessel and reactor internals, which are difficult to inspect and replace, and other peripheral facilities, which are relatively easy to inspect and replace.