Environment News Service

URANIUM, THORIUM IN DECOMMISSIONED PLANTS MUST BE BELOW BACKGROUND

The Nuclear Regulatory Commission (NRC) is amending its regulations to provide criteria for the cleanup of uranium and thorium in soil and radioactivity on building surfaces during the decommissioning of uranium mills and other uranium extraction facilities. The criteria represent upper limits on the radiation dose levels that would be permitted. The NRC previously used agency guidance documents to decide whether to approve cleanup and decommissioning plans and license terminations. The criteria are based on the existing Environmental Protection Agency (EPA) soil standard for radium. The new standard for uranium and thorium uses the radiation dose from radium in soil as a benchmark. Licensees who are decommissioning their uranium facilities will have to calculate the radiation dose from radium over 1,000 years for their particular site. They will then have to remediate so that the dose from NRC-regulated uranium and thorium remaining on site after decommissioning will not exceed the dose allowed for radium. The staff recently calculated that the potential dose to an individual from applying the benchmark approach may range between 22 and 34 millirems per year. The average annual dose to an individual in the United States from natural background radiation is about 300 millirems. In addition, licensees will be required to demonstrate that radiation doses from NRC-regulated materials are as low as is reasonably achievable.

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