External evaluation on the logical adequacy of the safety measures and coolability of the reactor core and others in Monju considering Earthquake and Tsunami; The Technical Committee on Severe Accident Countermeasures and others considering Tohoku district - off the Pacific Ocean Earthquake

FBR Plant Engineering Center; Fast Breeder Reactor Research and Development Center, Tsuruga Head Office; Policy Planning and Co-ordination Department, Tsuruga Head Office

JAEA-Evaluation 2011-004, 132 Pages, 2012/01

JAEA-Evaluation-2011-004.pdf:10.12MB

The logical adequacy of the safety measures in Monju, coolability of the reactor core and the ex-vessel storage tank by natural circulation, and coolability of the spent fuel storage pool, considering Tohoku district - off the Pacific Ocean Earthquake were explained by Japan Atomic Energy Agency and reviewed in the above-titled committee. Main conclusions by the chairman of the committee are summarized as follows: (1) Natural circulation cooling is secured in the reactor after station blackout (SBO) as far as flow path exist. Therefore, the reactor core will never melt because of the decay heat removal as far as the natural circulation is reserved after the reactor shutdown; (2) Spent fuels will never melt due to temperature rise in the ex-vessel fuel storage system, since natural circulation cooling can be expected even after SBO; (3) It is possible to take sufficient countermeasures such as water supply against the spent fuel pool because it takes approximately two month before the top of the spent fuel cans which contain spent fuels are exposed by evaporation of the water.