Story highlights A plant worker's clothing was contaminated with nuclear waste

State officials want the Department of Energy to investigate

(CNN) Authorities at Washington state's Hanford nuclear waste site are investigating a possible leak after discovering radioactive material on a worker's clothing. The discovery follows an incident early last week in which a site tunnel collapsed, sparking fears of radiation exposure.

Washington River Protection Solutions, a contractor working at the site, on Thursday detected high readings of radiation on a robotic device known as a crawler that workers were pulling out of a nuclear waste tank. Contamination was also discovered on the clothing of one of the workers.

"Established decontamination procedures were followed, which involves removing the contaminated clothing. Further surveying the worker showed no contamination remained. No other workers were affected, and all members of the crew were cleared for normal duty," said WRPS spokesman Peter Bengtson.

The Double-Shell Tank AZ-101 contains 800,000 gallons of nuclear waste, according to the Washington Department of Ecology, which oversees the Hanford site. The nuclear plant is located in the south-central part of Washington state, about 45 miles from Yakima.

Using leak-detection instruments, WRPS said it did not find liquid escaping the tank. However, workers are preparing a plan to conduct a visual inspection by video.

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