An evacuation drill to prepare for a nuclear disaster has been held in Niigata Prefecture, but central and prefectural government officials remained at odds over when to hand out potassium iodine pills to residents to mitigate the risk of thyroid cancer in such a scenario.

The drill was based on a situation in which an earthquake registering 6 on the Japanese seismic intensity scale of 0 to 7 would hit the Kashiwazaki-Kariwa nuclear power plant, operated in the prefecture by Tokyo Electric Power Co., knocking out the power supply and leaving the utility unable to cool its reactor 7.

About 1,500 people within a 30-km radius of the plant participated in the drill.