Study on criticality control of fuel debris by Japan Atomic Energy Agency to support Nuclear Regulation Authority of Japan

Tonoike, Kotaro ; Yamane, Yuichi  ; Umeda, Miki ; Izawa, Kazuhiko ; Sono, Hiroki 

From the viewpoint of safety regulation, criticality control of the fuel debris in the Fukushima Daiichi Nuclear Power Station would be a risk-informed control to mitigate consequences of criticality events, instead of a deterministic control to prevent such events. The Nuclear Regulation Authority of Japan has set up a research and development program to tackle this challenge. The Nuclear Safety Research Center of Japan Atomic Energy Agency, commissioned by the authority, has launched activities such as computations of criticality characteristics of the fuel debris, development of criticality risk assessment method, and preparation of criticality experiments to support them.