“Initial reports indicate the cause of the shutdown was a problem with the safety system. The reactor has been taken off-line,” a ministry statement said. The incident occurred at 11:15 p.m. Monday, radiation levels in and around the plant reported to be normal. The reactor has been disconnected from the net and work is under way to fix the malfunction, he said.

The plant is located near the Volga River city of Saratov, about 700 kilometers (450 miles) southeast of Moscow. The radiation background at the plant and in the nearby area is within norm, says a statement released by the Press Center of Nuclear Energy.