Officials at Kansas’ only nuclear power plant say a potential problem with an air conditioning unit has prompted an unplanned shutdown.

Wolf Creek plant spokeswoman Cassie Bailey said Thursday a maintenance check identified issues with the air conditioning unit that cools safety-related electrical systems. The plant shut down late Wednesday.

Bailey says it’s not known when Wolf Creek will resume generating electricity. The plant is located near the town of Burlington, about 55 miles south of Topeka.

Bailey says the problem initially appeared to be with the compressor in the air conditioning unit, but Wolf Creek is still investigating. She said the compressor had been installed recently.

Wolf Creek reduced its power output for seven days in June because of issues with another air conditioning unit.