Japan’s Hiroshima High Court high court has rejected a petition by local residents to halt the operation of unit 3 at Shikoku Electric Power Co’s Ikata NPP in Ehime Prefecture, upholding a lower court decision. This will allow Shikoku Electric to continue operation of Ikata 3, which is currently closed for a regular inspection until 19 June.

The appeal was filed by seven residents of Hiroshima and Ehime prefectures who live between 60 and 130 kilometres from the reactor. The trial focused on whether the estimate of seismic ground motion made by the utility was appropriate. The residents said the estimate was inadequate, arguing that a major accident could occur in the event of a powerful earthquake similar to one that devastated north-eastern Japan in March 2011.

Shikoku Electric defended its estimate citing the region's local characteristics including ground conditions, which showed there was "no particular danger”. In November 2021, the Hiroshima District Court had also dismissed a request by the residents to suspend the reactor

Shikoku Electric Power Co restarted Ikata 3 in December 2021. The reactor had then been offline since December 2019 for regular checks and because of a subsequent court injunction. The restart came after reversal in March of an injunction handed down by the Hiroshima High Court in January 2020 banning the reactor from operating because of safety concerns.

The 2020 decision in was based on the court’s view that the rules and risk assessment of Shikoku Electric and the Nuclear Regulation Authority regarding a possible disastrous eruption of Mt Aso, some 130km away, were inadequate. However, the Hiroshima High Court reversed this decision March 2021 in response to an objection from Shikoku Electric, allowing it to restart the reactor.

Image: The Ikata nuclear power plant (courtesy of Shikoku)