RICHLAND, Wash. (AP) - A new report says mistakes and mismanagement are to blame for the exposure of workers at the Hanford Nuclear Reservation in Washington state to radioactive particles in December.

Contractor CH2M Hill Plateau Remediation Co. on Thursday released its evaluation of what went wrong in December during demolition of the nuclear reservation's highly contaminated Plutonium Finishing Plant.

The Tri-City Herald reports the study said primary radioactive air monitors used at a highly hazardous Hanford project were not up to the job. Then when the spread of contamination was detected, the report said steps taken to contain it didn't fully work.

At least 11 Hanford workers checked since mid-December inhaled or ingested small amounts of radioactive particles. Private and government vehicles were contaminated with radioactive particles

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