No airborne radioactive particles were detected after steam was spotted Friday morning coming from a small building linked to the second PUREX Plant waste storage tunnel at the Hanford Site in Washington state.
The steam was not expected in that location, and more than 500 workers in the 200 East Area at the center of Hanford were ordered to take cover indoors with ventilation systems turned off from 6:03 a.m. to 12:15 p.m. as a precaution. The Department of Energy did not declare an emergency and the Emergency Operations Center in the nearby city of Richland was not activated.
Work began early this month to fill the second and longer PUREX tunnel with grout for stabilization. By Friday morning, 9,000 cubic yards of grout, or close to 25 percent of the concrete-like needed to fill the tunnel, had been added in thin layers through ports at the top of the tunnel.
The Energy Department said it is likely to need a few days to evaluate the opening in the tunnel building where steam escaped. Grouting work will resume afterward.
Grouting had not yet begun Friday when the steam was spotted. A crew wearing protective clothing and filter-air respirators were sent to the area near the tunnel at about 9:45 a.m. to check for any spread of contamination and to turn on generators to power the lights and cameras inside the tunnel.
The cameras showed steam in the tunnel as the latest layer of grout cured, generating heat and moisture. Some of the steam escaped the tunnel at the building at the end closest to the PUREX Plant and was visible in the cold air of the early morning, according to DOE.
The building had been sealed after being used from to lift the doors to allow railcars loaded with obsolete and failed equipment highly contaminated with radioactive waste to be pushed into the tunnel for storage from 1966 to 1996.
