It is hard to dispel the impression that the judges reached a conclusion on the safety of a nuclear power plant based on their own interpretations and judgments.

The Hiroshima High Court has issued a provisional injunction on the operation of the No. 3 reactor at Shikoku Electric Power Co.’s Ikata nuclear power plant in Ehime Prefecture. The decision overturned a ruling by the Yamaguchi District Court’s Iwakuni branch to allow the reactor to operate, which rejected an appeal filed by residents of Yamaguchi Prefecture. Shikoku Electric plans to file a complaint against the Hiroshima court’s decision.

The No. 3 reactor is now idle due to regular inspections. The power company had scheduled the resumption of its commercial operations for April. Since the provisional injunction takes effect immediately, the reactor cannot be restarted unless the decision is changed through court proceedings. The impact is serious from the viewpoint of ensuring a stable supply of electricity.

One of the key issues was whether active faults exist near the Ikata plant.

The high court concluded that Shikoku Electric judged an active fault does not exist without conducting sufficient surveys, and criticized the Nuclear Regulation Authority’s safety inspections by saying, “There were errors or omissions.”

However, some experts said the survey was appropriate. In the first place, the NRA’s screening process is strict and conducted over a long period, and it demands nuclear power plants secure the highest international level of safety. The Ikata reactor has passed this strict screening.

For the safety screening of nuclear power plants, court decisions have been made in the past by respecting the administrative side’s screenings based on the latest advanced scientific and technological knowledge. The latest high court decision has to be said to have gone beyond this framework.

The high court also ruled that Shikoku Electric underestimated the impact of a volcanic eruption, another point at issue. The court pointed out that the company underestimated the amount of volcanic ash that could be emitted in the event of a large-scale eruption of Mt. Aso in Kumamoto Prefecture, about 130 kilometers from the Ikata nuclear power plant.

However, since the frequency of large-scale eruptions is extremely low, it is very difficult to accurately predict the amount of ash that would be emitted. The NRA has endorsed the assumption made by Shikoku Electric as rational.

The high court ruling indicates its stance is one of “zero risk.”

In recent years, a number of applications have been filed to seek provisional injunctions against nuclear power plants across the country. In separate proceedings over a provisional injunction of the Ikata No. 3 reactor, the Hiroshima High Court first ordered the suspension of the reactor’s operations, but later canceled the decision after deliberating over an objection seeking to restrain the order.

Since provisional injunction proceedings require a speedy trial, evidence used in the proceedings is limited compared to ordinary trials. If the plaintiffs filed an appeal of the provisional injunction to stop the restart of a nuclear reactor, knowing about these particular aspects, it must be said to be an abuse of court process.

— This article appeared in the print version of The Yomiuri Shimbun on Jan. 18, 2020.