Japan retires more reactors as restarts approach

18 March 2015

More clarity on Japan's nuclear future came today as the first unit slated for restart gained technical approval, while two further older reactors were announced for retirement rather than being put through the restart process.

The older units officially declared for decommissioning are Shimane 1, owned by Chugoku Electric Power Company, and Genkai 1, owned by Kyushu Electric Power Company. These smaller units, of 439 MWe and 529 MWe respectively, started operation in the mid-1970s and enter retirement just one day after the same status was announced for three others of similar age - Tsuruga 1, along with Mihama 1 and 2.

The changes mean Japan now has a count of 43 operable nuclear power reactors and a total capacity of 40470 MWe, down from 54 units and 47,122 MWe before the 2011 accident at Fukushima Daiichi. All of the remaining reactors, however, will remain offline until they have been upgraded to meet extended safety requirements, such such as the provision of alternative power supplies, multiple sources of cooling water, back-up control rooms and venting to prevent hydrogen escape.

The leading unit in this process is Kyushu's Sendai 1, which today gained the Nuclear Regulation Authority's (NRA's) approval for its 'construction plan'. This means the 846 MWe reactor unit is technically ready for restart, having been upgraded, and that these engineering changes have been verified by the regulator. It also means that Kyushu's management, personnel training and operational methods are in line with the NRA's demands.

Sendai 2 as well as Kansai Electric Power Company's Takahama 3 and 4 are at the earlier stage, having made their upgrades, but awaiting the NRA's confirmation of the work.

Another 15 reactors are moving through the restart process, which has been prioritised to bring on the most-needed reactors first, in the localities and prefectures more supportive of restart. Publicly demonstrating the competency of both the power companies, the NRA and the process is an important factor in establishing public confidence in Japan's nuclear power safety culture.

Researched and written
by World Nuclear News