Shikoku outlines plans for decommissioning Ikata 2

Wednesday, 17 October 2018

Ikata 2 is a 538 MWe pressurised water reactor that began operating in March 1988. It was taken offline in January 2012 for periodic inspections. Shikoku announced in March this year that it did not plan to restart the reactor. It said the cost and scale of modifications required to upgrade the 40-year-old unit to meet the country's revised safety standards made it uneconomical to restart it.

The utility submitted an outline of its plans for decommissioning the unit to the Nuclear Regulation Authority (NRA) on 10 October. Shikoku also submitted requests to Ehime prefecture and the municipality of Ikata, as specified under nuclear safety agreements concluded with those authorities.

According to the plan, decommissioning of Ikata 2 will take about 40 years and will be carried out in four stages. The first stage, lasting about ten years, will involve preparing the reactor for dismantling (including the removal of all fuel and surveying radioactive contamination), while the second, lasting 15 years, will be to dismantle peripheral equipment from the reactor and other major equipment. The third stage, taking about eight years, will involve the demolition of the reactor itself, while the fourth stage, taking about seven years, will see the demolition of all remaining buildings and the release of land for other uses.

During the first stage, all fuel is to be removed from the unit. This includes 316 used fuel assemblies that will be sent for reprocessing and 102 fresh fuel assemblies that will be returned to the fuel fabricator.

Ikata 2 became the ninth operable Japanese reactor to be declared for decommissioning since the Fukushima Daiichi accident.

In mid-March 2015, the Ministry of Economy, Trade and Industry's Agency for Natural Resources and Energy revised the accounting provisions in the Electricity Business Act, whereby electric power companies can now calculate decommissioning costs in instalments of up to ten years, instead of one-time as previously. This enhanced cost recovery provision was to encourage the decommissioning of older and smaller units.

Shikoku decided in March 2016 to decommission unit 1 of the Ikata plant, also a 538 MWe PWR, which began commercial operation in September 1977. That unit had been taken offline in September 2011 for periodic inspections. Upgrades costing more than JPY170 billion (USD1.5 billion) would have been needed at the unit in order for it to operate beyond 40 years.

The NRA approved Shikoku's decommissioning plan for Ikata 1 in June 2017. That plan also sees the unit being decommissioned in four stages over a 40-year period.

Unit 3 at the Ikata plant was given approval by the NRA to resume operation in April 2016, having been idle since being taken offline for a periodic inspection in April 2011. Shikoku declared the 846 MWe pressurised water reactor back in commercial operation on 7 September 2016. However, in December 2017, a Japanese high court ordered the suspension of the unit's operation. The injunction was effective until the end of last month. The Hiroshima High Court in late September accepted Shikoku's appeal and cancelled the injunction, allowing the utility to begin the process of restarting the reactor.