Nuclear energy and nuclear safety

Currently comprising about 8% of Japan’s electricity mix, the nation’s 6th Strategic Energy Plan targets a nuclear share of 20-22% by 2030. Achieving this will require the restart of 25-28 reactors. Of Japan’s 33 operable reactors, 14 have been restarted so far. In 2024, Tohoku EPCO’s Onagawa 2 reactor (825 MW) and Chugoku EPCO’s Shimane 2 reactor (820 MW) marked the first boiling water reactors (BWRs) to restart since 2011, a notable milestone. Looking ahead, more BWRs, including Kashiwazaki-Kariwa 7 in 2025, are anticipated to resume operations. The recent decisions to allow extension of existing reactors’ lifetime are favourable, nonetheless, uncertainties remain about Japan’s ability to meet the 2030 target. Beyond restarting existing reactors, Japan is also investing in next-generation reactor technology to help meet future energy needs. Mitsubishi Heavy Industries, in partnership with Kansai EPCO, Hokkaido EPCO, Shikoku EPCO, and Kyushu EPCO, is developing the "SRZ-1200," a 1.2-gigawatt advanced light water reactor, expected to be completed by the mid-2030s. This aligns with Japan’s broader strategic direction, and the upcoming 7th Strategic Energy Plan is expected to maintain similar nuclear targets, reflecting Japan's commitment to nuclear power as a core element of its energy mix and climate goals. In relation with the development of new nuclear capacities, the utilities are compelled, regulation wise, to dismantle the existing reactors which have been fully stopped. Closing the overall nuclear cycle and especially the fuel cycle is also identified by the actors as a huge stake for the coming years and decades, as many utilities are facing limited capacities to store the spent fuel and as the geopolitical situation leads to more energy sovereignty. Japan’s restart of nuclear plants also has global implications, potentially easing Europe’s winter energy concerns by freeing up liquefied natural gas (LNG) for the global market. Rising electricity costs, up 20% for households and 30% for businesses over the past year, are pushing the government to consider further subsidies and cash relief measures for utilities, households, and businesses. Notably, Japanese utilities like Kansai, Kyushu, and Shikoku EPCOs, which restarted nuclear plants, reported profits in 2023, highlighting the potential for nuclear restarts to stabilize costs. However, the sharp depreciation of the yen continues to drive up import costs, with coal prices tripling and natural gas doubling within the last year.