Year
2014
Abstract
On March 11, 2011, the Fukushima Daiichi Nuclear Power Station lost all external power supply sources due to the earthquake and station blackout caused by the subsequent tsunami. This resulted in severe core damage at Units 1 to 3, and involved hydrogen explosions at Unit 1, 3, and 4. Despite many difficulties during recovery work, on December 16, 2011, the reactors achieved condition of cold shutdown and were in a stable state (completion of Step 2). According to “Mid-and-Long-Term Roadmap towards the Decommissioning of TEPCO’s Fukushima Daiichi Nuclear Power Station Units 1-4”, the term of decommissioning has been divided into the following three phases: from the completion of Step 2 to the start of fuel removal from the spent fuel storage pool (Phase 1), then to the start of fuel debris removal (Phase 2), and until the end of decommissioning (Phase 3). Decommissioning is carried out through these phases. In order to prevent diffusion of airborne radioactive materials, the cover of the reactor building was installed at Unit 1. Unit 4 was scheduled to be the first to start fuel removal from the spent fuel storage pool. Prior to fuel removal at Unit 4, the rubble on the top of the reactor building had to be removed and the fuel handing machine in the operating floor had to be installed. Fuel removal at Unit 4 started from November 18, 2013 (Completion of Phase 1). The preparation for fuel removal including rubble removal from the operating floor and the spent fuel storage pool at Unit 3 is proceeding as well. It was decided to decommission Unit 5 and 6 starting on January 31, 2014. This paper introduces the current status of Fukushima Daiichi Nuclear Power Station including the process towards fuel removal.