Advanced Thermal Reactor Fugen Nuclear Power Station (hereinafter referred to as "Fugen") terminated permanently its operation as the prototype Advanced Thermal Reactor (ATR) on March 29th, 2003. After permanent shutdown of Fugen, in order to secure safety, the facility is maintained and managed properly based on " the Nuclear Reactor Regulation Law ". And several projects are carried out as the preparation period of decommissioning of ten years (e.g. development and study of necessary technologies to flesh out the details of the decommissioning of Fugen, transfer of spent fuels to the site outside of the nuclear power station, removal and transfer of the heavy water from heavy water system). The decommissioning will be started in consideration of the progress of these preparations after several procedures are executed based on the law. These projects are being carried out by making efforts for public information to obtain the understanding and support from local society. In addition, the technology development, preparations and achievement of decommissioning are published actively by collaboration and technical cooperation with relevant authorities. The purpose is to utilize these developments or achievements in the nuclear facilities decommissioning in Japan effectively. ■For the safe and effective decommissioning of Fugen 　 As for the preparation of decommissioning, the relevant project is carried out effectively based on these basic policies as follows.