Development of a fast reactor and related thermal hydraulics studies in Japan

日本における高速炉開発と関連する熱流動研究

大島 宏之; 上出 英樹 

Ohshima, Hiroyuki; Kamide, Hideki

日本ではシビアアクシデント(CDA)対策を重要な視点としてナトリウム冷却高速炉の開発を行ってきた。安全性強化とCDA対策に関連した研究の近年の進捗として、外部事象の一つである火山噴火のPRA, CDA時の崩壊熱除去に関する模擬試験、CDA時の溶融炉心燃料の挙動を評価する上で重要な、ナトリウムプール中の溶融燃料の分散特性にかかる基礎試験などを実施してきた。本論文では、これらの成果について述べる。

Development of a sodium-cooled fast reactor has been implemented in Japan from the viewpoint of severe accident countermeasures. This paper describes the progress of research and development related to safety enhancement and the severe accident countermeasures. A volcanic PRA methodology was developed for the proper consideration of external hazards. Water and sodium experiments were carried out for the decay heat removal in a core disruptive accident (CDA), and also thermal hydraulic interactions between the core and upper plenum where dipped heat exchanger was operated. In order to elucidate the behavior of molten fuel during CDA, basic experiments of core melt fragmentation in deep and shallow sodium pools were carried out. X-ray visualization showed the liquid column of molten steel was intensively fragmented nearly simultaneously with a rapid expansion of sodium vapor.