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News Navigator: Why will only 9 of Japan's nuclear reactors be online this winter?

The No. 3 (front) and No. 4 reactors at Kansai Electric Power Co's Oi Nuclear Power Plant are seen in this photo taken from a Mainichi Shimbun helicopter in Oi, Fukui Prefecture, on March 12, 2022. (Mainichi/Takao Kimura)

The Mainichi Shimbun answers some common questions readers may have about the limited number of nuclear reactors set to be online in Japan over the coming winter, following Prime Minister Fumio Kishida's pledge that up to nine nuclear reactors will be in operation amid power shortage concerns.

    Question: There are many more nuclear reactors in Japan. Why nine?

    Answer: After the meltdowns at Tokyo Electric Power Company (TEPCO) Holdings Inc.'s Fukushima Daiichi Nuclear Power Station, Japan's nuclear power plants are not allowed to operate unless they meet the government's earthquake, tsunami, and anti-terrorism safety standards. There are 57 total reactors in the country, but only a handful meet these standards. Subtracting 24 reactors set to be decommissioned and those with incomplete safety updates leaves just nine available to run over the winter.

    Kishida mentioned that these nine reactors will be put into operation, and all of them have been in operation at least once since the new standards were put in place after the Fukushima Daiichi disaster. In other words, none are new reactors.

    Q: Which are those nine reactors?

    A: They are the No. 3 and 4 units at the Oi nuclear power station, the No. 3 and 4 units at the Takahama nuclear plant, and the No. 3 reactor at the Mihama nuclear plant, all run by Kansai Electric Power Co. in Fukui Prefecture; the Sendai nuclear station's units 1 and 2 in Kagoshima Prefecture, and the Genkai power station's No. 3 reactor in Saga Prefecture; and the No. 3 unit at Shikoku Electric Power Co.'s Ikata power plant in Ehime Prefecture.

    In addition, anti-terrorism facilities at the Genkai plant's No. 4 reactor are scheduled for completion in mid-February 2023, after which it will be ready for operation. However, all these reactors are in west Japan, and there are limits to how much they can supplement eastern Japan's electricity supply.

    Q: What about the situation at other reactors?

    A: Other than those mentioned above, seven reactors have passed the safety review. However, in addition to safety measure work, a review of the construction plan and the consent of the local government where the plant is located are also required before it can restart.

    Q: We need a lot of electricity in the summer as well. Could any of these seven units be up and running next summer?

    A: There are three reactors that have a projected restart date, but only the No. 1 and 2 units at Kansai Electric's Takahama plant will be ready by next summer. Those two will be operational in June and July 2023, respectively, after the completion of anti-terrorism facilities.

    The No. 2 reactor at Chugoku Electric Power Co.'s Shimane nuclear station in Shimane Prefecture has not posted a restart date, but it plans to finish safety measure work this fiscal year, so it may be able to go online next summer.

    (Japanese original by Takuya Yoshida, Science & Environment News Department)

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