Decommissioning program and future plan for Research Hot Laboratory, 3

Shiina, Hidenori ; Ono, Katsuto; Nishi, Masahiro; Uno, Kiryu; Kanazawa, Hiroyuki; Oi, Ryuichi; Nihei, Yasuo

The Research Hot Laboratory (RHL) in Japan Atomic Energy Agency (JAEA) was constructed in 1961, as the first one in Japan, to perform the examinations of irradiated fuels and materials. RHL consists of 10 heavy concrete cells and 38 lead cells. RHL contributed to research and development program in or out of JAEA for the investigation of irradiation behavior for fuels and nuclear materials. However, RHL is the one of target as the rationalization program for decrepit facilities in former Tokai institute. Therefore the decommissioning works of RHL started on April 2003. The dismantling of 12 lead cells has been progressing since 2010. The dismantling procedure of lead cells was performed in the following order. The peripheral equipment in lead cells were removed and contamination survey of the inner surface of the cells. Then, the backside shield doors were extracted. The lifting frame for the isolation tent was set on the cells. After that, the ceiling plates, isolation walls and lead blocks were removed. The strippable paint was used to remove permeable contamination on the inner surface of structural steel of the cells. The dismantling work will be continued to mention the efficiency of decommissioning works and reduction of radioactive waste with ensuring safety.