The Preliminary study for safety design of JAEA's Radioactive Material Analysis and Research Facility "Laboratory-2" dedicated to fuel debris analysis at TEPCO's Fukushima Daiichi Nuclear Power Station site

Sato, Akinori; Kosaka, Ichiro; Kaji, Naoya

The Japan Atomic Energy Agency (JAEA) is now constructing Radioactive Material Analysis and Research Facility (The administration building, Laboratory-1 and Laboratory-2). Laboratory-2 is planned as a hot laboratory handling the fuel debris and conducting radioactive analysis and mechanical/chemical characterization of fuel debris. Therefore, some specific issues, such as shielding and criticality safety should be investigated as preliminary studies. For evaluations of radiation shielding, the conservative conditions were adopted such as conservative source intensity, the effect of activated structural material and excluding self-shielding system. As a preliminary evaluation of criticality safety, the critical mass limit was evaluated under conservative conditions such as fresh fuel and 30 cm water reflection. Through evaluations, it is found that shielding design of Laboratory-2 is achievable even if calculations are performed under conservative conditions. Through preliminary calculation of critical mass limit, handling of the assumed amount of fuel debris (5 kg) is concluded to be feasible.