A take-cover order for about 1,000 workers Tuesday afternoon in a portion of central Hanford turned out to be a false alarm.
Workers in the 200 West Area of the nuclear reservation were ordered indoors for about 30 minutes because of a possible chlorine leak.
In a take cover order, workers go inside buildings with all doors and windows closed and ventilation systems turned off.
An alarm sounded at the Hanford Patrol Station indicating there was a leak at a central Hanford water treatment plant built in 1944. The plant uses chemicals, including chlorine, but has no radioactive contamination.
The alarm did not sound at the site’s treatment plant, but workers were told to take cover as a precaution at 1:55 p.m.
An investigation by utility and other Hanford officials found no evidence of a leak. They determined that a faulty electrical connection set off the alarm.
Workers were released to return to work at 2:27 p.m.
The Hanford nuclear reservation near Richland is undergoing environmental cleanup after producing about two-thirds of the plutonium for the nation’s nuclear weapons program.