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

Tonoike, Kotaro ; Watanabe, Tomoaki  ; Gunji, Satoshi  ; Yamane, Yuichi  ; Nagaya, Yasunobu  ; Umeda, Miki ; Izawa, Kazuhiko ; Ogawa, Kazuhiko 

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 administrated a research and development program to tackle this challenge since 2014. The Nuclear Safety Research Center of Japan Atomic Energy Agency, commissioned by the authority, is conducting activities such as computations of criticality characteristics of the fuel debris, development of a criticality analysis code, preparation of criticality experiments, and development of a criticality risk analysis method.