A study on dose control for Tokaimura criticality accident termination.

Verification of the dose control method for Tokaimura criticality accident was performed. Personal dose estimation for accident termination was performed based on measurements of dose rate taken before the work commenced, but the personal dose to workers as a result of the termination work was found to be approximately 50 times higher than the previous estimation. For this report, the doses are reevaluated based on the results of close range measurements from 40 to 100 m, and the results were found to agree with the actual personal doses within the uncertainty of its determination 60-80 %. Therefore, the work can likely be done safely by taking into account factors such as annual dose limits and the guideline dose constraints for works in high-level neutron radiation fields.