The Japanese government’s drive to put nuclear plants back online has suffered a setback. A district court has blocked the restart of two reactors, saying it would be dangerous to operate them.

Residents of Fukui prefecture and other groups filed a lawsuit against the operator of the Ohi nuclear power plant, Kansai Electric Power Company.

Reactors 3 and 4 are undergoing inspections by Japan’s nuclear regulators, with the aim of restarting the two units if they clear the latest safety standards.

The plaintiffs argued that measures in place at the facility would not be sufficient to keep the reactors cooled in the event of a major accident.

The judge ruled in favor of the plaintiffs. He said the projections used by Kansai Electric to improve safety measures are too optimistic.

The judge concluded it would be dangerous to continue operating the plant on this basis.

The head of Japan’s Nuclear Regulation Authority said the ruling would not have an impact on the safety checks currently underway at 17 of Japan’s 48 commercial reactors.

The Japanese government’s main spokesman said the ruling would not affect the administration’s drive to restart nuclear plants once they clear safety checks.

All of Japan’s reactors remain offline as a consequence of the Fukushima Daiichi nuclear accident. Electricity companies have been spending billions of dollars to upgrade their facilities in the hope of restarting them as early as this summer.