Decommissioning is the clean-up work of nuclear facility after shutdown. A special measure is executed for safe control and disposal because of the radioactivation in the core even if all the fuels are finished removing.

Decommissioning is promoted (will proceed) based on the law after shut down. Various preparations of decommissioning, such as development and study of necessary technology to undertake the safe and effective decommissioning, are set up in advance. The preparation of decommissioning until the start of dismantlement officially, will take for approximately 10 years according to conventional studies. We will study effective work contents considering safety and give shape to plan in this preparation period. The decommissioning project should be finished within 30 years, although these careful preparations are carried out.

The fuels were stored in the spent fuel storage pool after discharge from the core. And then these fuels were transferred to the Tokai Reprocessing Center. In addition, the heavy water, which is utilized as the moderator, is removed and transferred. And then the equipment, piping, reactor and building are dismantled step by step. Generated waste is treated and disposed according to the plan.

Total amount of radioactivity will be measured (by the concrete boring, etc.) to study the amount of radioactive materials in the facility. We will evaluate the radioactivity (e.g. where it is and how much it is) and decide the rational dismantling method according to its evaluation results. In addition, we will consider the method to reduce the radioactivity depending on its amount. Recycling method of generated materials is thought out based on the reduction of waste to be environment-friendly. Total amount of dismantled material is approximately 370,000 ton (it is almost concrete). Radioactive waste will be approximately 4,000 ton (it will be 1% of this total). Approximately 99% of residual generated materials will not be necessary to treat as radioactive waste.

There are some decommissioning experiences in Japan, such as JPDR of JAEA(former JAERI) and Tokai-1 of JAPCO (during dismantlement). And there are a lot of the decommissioning experiences in the world.

Technologies of decommissioning will be developed from the two aspects at Fugen. Fugen is characterized by utilization of heavy water as moderator and dense piping structure in the core. As for these unique problems of Fugen, dismantlement technologies are developed independently based on knowledge and experiences obtained from abroad. Meanwhile, cooling system and turbine generator of Fugen are similar to LWR basically. Existing technologies of these characteristics are improving and upgrading. In addition, study of dismantlement work utilizes computer simulation and advanced information-processing technology. In addition, an information exchanged and cooperation and the technology developments are positively advanced internationally. Technical cooperation with domestic relevant authorities are advanced.

There are more than 50 nuclear power plants in operation in Japan.The decommissioning will be carried out for these plants after shutdown in the future. Data information will be collected systematically, evaluated and arranged to apply our research and development results to an effective way. These results will be widely released to the public not only in Japan but also in the world.

We are trying to publish its information via the Internet to get understanding and support of the local society, and we will continue it from now on.