A power company shut down a nuclear plant in south-central Washington state after operators received an indication that a system used to cool equipment wasn't working.

Energy Northwest spokesman John Dobken said early Tuesday that there was no release of radiation from Columbia Generating Station near Richland, and no danger to the public.

He tells The Associated Press that officials hope to restart the plant sometime this week.

The Tri-City Herald reported that the plant was shut down Monday after operators were alerted to problems with the system that uses water to provide cooling to heat exchangers and pumps, including those that control the power level of the reactor.

Energy Northwest says it seems that a water system valve may not have been in the right position, but that an investigation is ongoing.

The last time the plant had an unplanned shutdown was in November 2009, when there was a hydraulic fluid leak.