On January 17, 2020, the Hiroshima High Court (presiding judge Kazutake Mori) handed down a ruling ordering the halt of Shikoku Electric Power Co.’s Reactor No. 3 at the Ikata Nuclear Power Plant (Ehime Prefecture, the only nuclear plant on the island of Shikoku) due to real risks to life and limb of residents in the event of an earthquake or volcanic eruption. This was in response to a request for an injunction filed by residents from an island in Yamaguchi Prefecture within 50 km of the plant. The ruling overturned a March 2019 decision by the Iwakuni branch of the Yamaguchi District Court that had dismissed the residents’ concerns and ruled that the plant could continue operating, stating among other things that there was a low likelihood of a large eruption during the reactor’s operating life.
The judge found that the possible presence of an active seismic fault near the Ikata nuclear plant could not be denied, saying, “The fault’s proximity to the nuclear plant is recognized to be less than 2 km, but Shikoku Electric Power did not investigate sufficiently, and I have to say that there were errors and omissions in the Nuclear Regulation Authority’s process that found no problems exist.” As for the safety of volcanic eruptions, the judge found that the NRA review had underestimated the impacts of volcanic ash in the event of an eruption at Mount Aso.
Reactor 3 is currently halted for regular inspections and cannot restart even after they are completed unless the latest ruling is overturned in court.
The Ikata nuclear plant has had serious troubles, including an incident when all power was lost temporarily during operation when a control rod was mistakenly removed from the reactor and cooling for a pool of spent nuclear fuel failed for 43 minutes. Shikoku Electric Power Co. originally stated that it would not immediately appeal the ruling, but on February 19, 2020, it filed a petition in the same high court challenging the injunction and requesting that it be overturned.