Ohi-3 Becomes Japan’s First 1000MW-Class NPP to Be Restarted

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In the evening of March 16, the Ohi-3 Nuclear Power Plant (PWR, 1180MWe), owned and operated by the Kansai Electric Power Co. (Kansai EP), resumed power generation after four and a half years.

Following the nationwide shutdown of all Japan’s NPPs in the wake of the accident at the Fukushima Daiichi NPPs in March 2011, a political decision was made to restart Ohi-3 and Ohi-4 in the summer of 2012, based on a judgment of safety and necessity. In other words, the original resumption of the two units was aimed at meeting electricity demand and avoiding increasing rates in the Kansai area (Osaka, Kobe, Kyoto) because of the additional operation of thermal power plants. However, after just one cycle of operation, both were shut down again in September 2013.

Ohi-3 and Ohi-4 have since both cleared safety examinations conducted by the Nuclear Regulation Authority (NRA), confirming their compatibility with the country’s new post-Fukushima regulatory standards. With the recent restart of Ohi-3, the number of reactors restarted by Kansai EP now comes to three, including the Takahama-3 and -4 NPPs.

Kansai EP will now carry out a series of tests, increasing Ohi-3’s output. The company expects to complete the NRA’s pre-service inspection in early April, when the unit will be returned to full operation.

Kansai EP had filed its application with the NRA for compatibility examinations for Ohi-3 and Ohi-4 in July 2013, when the new standards first came into effect. The NRA, however, gave priority to examining the same company’s Takahama-3 and -4 NPPs, as well as its Mihama-3 and Takahama-1 and -2, the latter three of which were nearing their forty-year lifetime operating limits.

Thus, it took nearly four years from Kansai EP’s original filing of the application for the company to get permission in May 2017 to make changes to Ohi-3’s reactor installation (i.e., its basic design approval). Since then, in November of the same year, the governor of Fukui Prefecture endorsed the restart of Ohi-3 and Ohi-4.

Ohi-3 is Japan’s sixth commercial reactor to be restarted after clearing the examination to confirm compatibility with the new regulatory standards. The other five are: the Sendai-1 and -2 NPPs, owned and operated by the Kyushu Electric Power Co., Kansai EP’s Takahama-3 and -4 NPPs, mentioned above, and the Ikata-3 NPP, owned and operated by the Shikoku Electric Power Co. Among the six, Ohi-3 is the first in the 1000MWe class.

Additionally, Kansai EP’s Ohi-4 is expected to begin power generation in mid-May, and to return to full operation in early June.