The Hanford Site’s Plutonium Finishing Plant was immediately evacuated Thursday morning when a criticality alarm sounded. Hanford officials confirmed 90 minutes later that it was a false alarm related to maintenance being conducted on the alarm system that morning. The cause of the false alarm is being investigated. The alarm is designed to warn workers when monitors detect large amounts of radioactivity that could be the result of a criticality, or uncontrolled nuclear reaction.
About 50 workers left the plant in central Hanford as a precaution, some wearing protective gear required in contaminated areas of the site, said Department of Energy spokesman Geoff Tyree. The alarm sounded at about 10:30 a.m. and by about 1 p.m. all the workers had been surveyed for radioactive contamination, with none found. Because workers in personal protective equipment could have tracked contamination through the plant as they exited, the facility was being surveyed Thursday for radiation. Other work inside the plant was not expected to resume Thursday.
Removing protective gear is a careful and deliberate process, usually done as workers exit a contaminated area of the plant to make sure that any possible contamination on the gear does not spread as it is being removed. The process of removing the gear outside the plant slowed work to survey all employees for contamination.
The Plutonium Finishing Plant was used from 1949 through the Cold War to turn plutonium that arrived from Hanford processing plants in a liquid form into hockey puck-size “buttons” for use at U.S. nuclear weapons production sites. CH2M Plateau Remediation Co. workers are in the final stages of decontaminating and removing as much debris and equipment as possible from the plant’s main production facilities to prepare them for demolition. Demolition was expected to start this spring, but Hanford officials now are aiming for summer.
