Japan holds nuclear disaster drill simulating Tomari plant accident

The government on Saturday conducted a comprehensive nuclear emergency drill simulating a severe accident at Hokkaido Electric Power’s Tomari nuclear plant in Japan’s northernmost prefecture.

The three-day drill, which runs through Sunday, involves the Hokkaido prefectural government, relevant municipalities and the Cabinet Office. The drill includes exercises conducted at the Tomari plant for the first time in 10 years. About 8,500 local residents are expected to take part.

The drill is based on a scenario in which an earthquake off the western coast of Hokkaido causes equipment failure at the plant’s No. 3 reactor, rendering its cooling system inoperable.

On the second day of the exercise, Prime Minister Sanae Takaichi declared a nuclear emergency. While some participants transported people assumed to have been exposed to radiation, others held a countermeasures meeting through a video conferencing system.

In 2025, the Nuclear Regulation Authority concluded that the No. 3 reactor at the Tomari plant met the country’s new safety standards, a prerequisite for its restart.

The authority is still reviewing a construction plan covering the detailed design of the reactor’s facilities, and the timing of the reactor’s restart remains uncertain.

In a lawsuit filed by local residents seeking a halt to the Tomari plant’s operation, Sapporo District Court partially granted the plaintiffs’ request and issued an injunction in 2022. Sapporo High Court is scheduled to hand down its appellate ruling in January next year.