Hanford nuclear reservation workers who were at the site’s Plutonium Finishing Plant Thursday morning are being offered tests for radiation exposure.
An air monitor for radioactive contamination alarmed Thursday morning as open air demolition was being done to tear down the plant’s Plutonium Reclamation Facility. A low level of airborne contamination was detected.
Data collected so far does not suggest that workers were in enough danger of inhaling radioactive particles to require testing for exposure, according to a memo sent to Plutonium Finishing Plant workers Friday by Todd Southerland, the plant’s safety, health and radcon director.
But rather than rely solely on the results of air and other samples collected, “we believe each employee should have their potential exposure evaluated so they have that peace of mind,” the memo said.
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Because the detection of airborne contamination was brief and workers were told to take cover, the potential exposure to radioactive particles was minimized, the memo said.
A bioassay test for internal contamination can check for radioactive exposure as low as one millirem, which is equivalent to about a tenth of the radiation received in a chest x-ray.
Work continued Friday to collect and analyze air sample data and to do additional surveying around the Plutonium Finishing Plant to fully understand the alarm.
About 350 workers at the plant were ordered to take cover indoors just before 7 a.m. Thursday. The take-cover order was lifted about 10:45 a.m. and employees, who had started work in the early morning to avoid the afternoon heat, worked the remainder of their scheduled shifts.
Some spots of radioactive contamination were found outside the demolition zone, including on sidewalks, near a respirator station and near a vehicle access gate. Fixative was applied to glue the spots of contamination in place and plans made to remove the contamination.
When the alarm sounded, work was underway to peel back the face of one of the four glove boxes that span the length of the Plutonium Reclamation Facility’s central area, called a canyon. The glove boxes are part of the building’s structure and could not be removed intact.
Prior to open-air demolition with shears on the end of an excavator arm, equipment had been removed from the glove boxes, as much contamination as possible removed and fixative applied.
During demolition, water was sprayed to control dust and bright blue fixative was sprayed to glue any contamination in place.
The Plutonium Finishing Plant was used during the Cold War for a final processing step for Hanford-produced plutonium before it was shipped to nuclear weapons production facilities.
The Plutonium Reclamation Facility was built onto one end of the plant to recover plutonium from scrap materials to increase Hanford’s output of weapons plutonium.