Japan’s Shikoku Electric Power Co on 27 October restarted unit 3 at its Ikata nuclear plant in Ehime Prefecture after the Hiroshima high court lifted a suspension order which had kept the unit offline for almost a year. Commercial operation of the unit is scheduled for 28 November.

The high court accepted an appeal by Shikoku Electric, ruling that there are no safety risks associated with potential volcanic activity in the nearby region, reversing its provisional injunction of December 2017. The injunction had ordered the utility to  stop the 890MWe pressurised water reactor (PWR) until 30 September, following a request from a local opposition group. However, the high court said on 25 September that the group's concerns about a possible destructive volcanic eruption during the plant's operating period were unfounded. The Hiroshima District Court rejected the group’s call to extend the injunction.

Ikata 3 received Nuclear Regulatory Authority approval to resume operation in April 2016, having been idle since being taken offline for routine inspection in April 2011. It entered  commercial operation in September 2016 before being closed again for routine maintenance in October 2017 and was scheduled to restart in January before the court injunction suspended its operation.   

Meanwhile, Shikoku Electric had already decided to decommission the ageing units 1 and 2 at the Ikata plant. A decommissioning plan for Ikata 2 was submitted to NRA earlier in October. The 538MWe PWR began operating in 988 and was taken offline in January 2012 for periodic inspections. Shikoku announced its decision to close the unit in March this year as the cost and scale of modifications required  to meet revised safety standards made its restart uneconomical.

According to the plan, the four-stage decommissioning of Ikata 2 will take about 40 years, with the first stage lasting about ten. This will involve preparing the reactor for dismantling, including fuel removal and a survey of radioactive contamination. The 316 used fuel assemblies will be sent for reprocessing and 102 fresh fuel assemblies that be returned to the fuel fabricator. The second stage, lasting 15 years, will involve the dismantling of peripheral equipment from the reactor and other major equipment. The third stage (about eight years) will involve demolition of the reactor, and the fourth stage (about seven years) the demolition of all remaining buildings and the release of land for other uses.

Shikoku decided in March 2016 to decommission Ikata 1, also a 538MWe PWR, which began commercial operation in 1977. Upgrades costing more than JPY170 billion ($1.5 billion) would have been needed for it to operate beyond 40 years. The NRA approved  a similar decommissioning plan for Ikata 1 in June 2017.  

Photo: Ikata nuclear power plant  (Photo Newsliner/CC BY-SA 2.5)