The incident occurred at the 200 West area of the south-central Washington site, where workers have been unearthing containers of waste that had been buried for years. The site is also near a landfill where some waste is being permanently buried.
Workers were evacuated from a trench as a precaution after the suspected breach at 10:35 a.m. PDT, said Calvin Dudney, a member of the joint information center at Hanford. Workers in the area were advised to take cover in secure buildings nearby.
A brown absorbent material escaped from a 55-gallon drum, and workers immediately halted work and evacuated the area. Two workers closest to the drum were given nasal smears and showed no contamination, Dudney said. Nine other workers in the area also were evacuated to a safe building nearby and showed no contamination.
No other information was immediately available.
The State Emergency Operations Center was activated at 11:05 a.m. to monitor the situation and assist Benton, Franklin and Grant counties if emergency operations become necessary.
For 40 years, the 586-square-mile Hanford nuclear reservation made plutonium for the nation's nuclear weapons arsenal, beginning with the top-secret Manhattan Project (search) to build the atomic bomb.
Today, it is the nation's most contaminated nuclear site, with cleanup costs expected to total $50 billion to $60 billion. The work is scheduled to be completed by 2035.