Three Japanese reactors to be retired

17 March 2015

Kansai Electric Power Company and the Japan Atomic Power Company (JAPC) have decided to decommission three nuclear power plants shut down after the Fukushima accident of 2011 rather than applying to restart them.

Mihama NPP 400 (NRA)
Kansai's three-unit Mihama plant (Image: NRA)

Kansai Electric officially announced its decision to decommission units 1 and 2 at its Mihama plant, while JAPC will decommission Tsuruga unit 1. Both companies have said they had assessed the work needed to ensure the units meet requirements introduced by the Japanese Nuclear Regulation Authority (NRA) announced in July 2013.

Tsuruga 1, a 341 MWe boiling water reactor, started up in 1970 and is one of Japan's oldest nuclear reactors. Independent studies completed in 2014 confirmed that geologic faults running under the siteare inactive. However, JAPC said that while it would have been technically feasible to bring Tsuruga 1 up to the standards required, the size of the project and the degree of capital investment required underpinned the decommissioning decision.

JAPC's announcement does not include Tsuruga 2, a pressurized water reactor (PWR) which started up in 1987, although the company has yet to apply for permission to restart that reactor.

Mihama 1 and 2 are both PWRs and have also been in operation since the early 1970s, unit 1 since 1970 and unit 2 since 1972. A third unit at the site started up in 1976, and was not included in Kansai's statement today.

Japan's entire fleet of 48 operable nuclear reactors have been taken out of service since the Fukushima accident of 2011. To date, the NRA has received restart applications for 19 units under the revised regulatory regime, triggering a review process to ensure that plants meet the revised criteria before being permitted to restart. Those criteria include measures such as the provision of alternative power supplies, multiple sources of cooling water, back-up control rooms and venting to prevent hydrogen escape.

With the exception of JAPC's Tokai 2, which started up in 1978, restart applications have not yet been submitted for any Japanese reactor that has been in operation for over 30 years. As today's announcements would suggest, utilities will consider carefully the economic prudence of undertaking major work on older units. More decommissioning announcements could well be on the way.

So far, four reactors - Kansai's Takahama 3 and 4 and Kyushu's Sendai 1 and 2 - have restart approval from the NRA, with preliminary permission to make the changes to the basic design of the reactor installations needed to meet the regulatory requirements. Local and prefectural government approval is also required before they can restart.

Researched and written
by World Nuclear News