Japan’s Chubu Electric Power Company has removed the upper lid of the reactor pressure vessel at unit 1 of the Hamaoka NPP Omaezaki, Shizuoka Prefecture. Unit 2 underwent a similar procedure in March. Hamaoka 1&2 are the first nuclear power reactors in Japan to undergo reactor dismantling.
Hamaoka 1&2 are boiling water reactors. Unit 1 (540 MWe) began operating in 1976 and unit 2 (840 MWe) in 1978. Due to updated seismic regulations introduced after the 2007 Niigata Chūetsu offshore earthquake, Chubu Electric decided in 2008 to decommission both units. Initial work began in 2009. Used fuel from the reactors has been transferred to the used fuel pools of units 4&5 on the same site and all fresh fuel has been removed. The facility has undergone extensive decontamination work, as well as decommissioning turbines, generators, and some reactor building components since 2015.
In 2009, the Ministry of Economy, Trade & Industry approved the decommissioning plan for the two units. The plan divided the decommissioning into four stages: the first stage for preparatory work; the second for dismantling and removal of equipment surrounding the reactors; the third for dismantling the reactors; and the fourth for demolition of buildings.
Chubu Electric initially planned to begin dismantling the reactors in fiscal 2023 but postponed the start of work for a year to study measures against radiation exposure. In 2024 the planned duration of dismantling work was extended from six to 12 years. In December 2024, the Nuclear Regulation Authority approved Chubu’s application to move to the third stage of decommissioning after the second stage was completed. Chubu Electric plans to begin the fourth phase – dismantling the reactor building – in fiscal 2036, and to complete decommissioning work in fiscal 2042.
