Technology Development for Decommissioning in FUGEN and Current Status

The decommissioning program of proto-type Advanced Thermal Reactor (ATR) FUGEN has started in 2008 as first decommissioning of the commercial-scale water reactor. It consists of four periods, considering the transportation of spent fuels and the radioactive decrease of highly activated materials. It is expected that the whole program of decommissioning will be completed until 2028. Now, the decommissioning is under the first period, spent fuels and heavy water has been carrying out from FUGEN, and a part of the turbine system with relatively low radioactive contamination has been dismantled. FUGEN has a complicated core structure consisting 224 fuel channels with pressure tubes and calandria tank, etc. and used heavy water as moderator, unlike other light water reactor (LWR). The materials of the core structure were highly activated due to a long term operation, tritium and C-14 were generated, and the facilities were contaminated by them. Thus, it is important to study the dismantling technology of the reactor core and the decontamination technology, considering characteristics of FUGEN such as core structure and radioactive inventory in advance. In this presentation, the contents of the decommissioning program and its current status such as dismantling work of a part of the turbine system, the studying situation of dismantling technology of reactor core using Abrasive Water Jet (AWJ) which is a candidate of cutting technologies, the examination of tritium decontamination in heavy water system, the study of decontamination technology for C-14 will be presented mainly.