Exclusion Area Radiation Release during the MIT Reactor Design Basis Accident

摘要

Pending changes in NRC emergency planning requirements have prompted this reevaluation of the maximum radiation dose to an individual located at the exclusion area boundary of the MIT Reactor during the first two hours of its Design Basis Accident. The DBA is postulated to be the melting of four fuel plates in one element, releasing a maximum of 1.5% of the core fission product inventory to the coolant. The approach used was to evaluate the major release pathways to the exclusion area boundary. The resulting total maximum dose is estimated to be 0.595 rads to the whole-body and 0.118 rads to the thyroid. These are well within the regulatory limits for exclusion area releases during an accident. The steel scattering dose was the largest component of the total whole-body dose(63%) and the truck lock penetration dose was found to be negligible. In addition, the behavior of each component of the dose beyond the exclusion area boundary was estimated based on a few prominent gamma energies with the resulting conclusion that the total dose decreases beyond the boundary.