Monte Carlo Simulation of the Gamma Dose Rate in a Loss-of-Water Accident at the North Carolina State University Research Reactor

In pool-type research reactors, a sudden loss of all pool water can result in significant external radiation dose. Of concern are fission product decay gamma rays emitted within the core, streaming out of the biological shield producing unacceptable radiation exposure in and around the reactor building. A Monte Carlo model was developed and used to generate dose maps for key access and traffic areas throughout the reactor facility at North Carolina State University. It was found that several of these areas could be exposed to significant gamma radiation fields, ranging from 230 rem/h 20 ft directly over and in line of sight of the core to 4 mrem/h outside and adjacent to the reactor building. Expected dose rates were also computed for the reactor bay floor, control room, and offices. The model was benchmarked against dose rates measured at the Lawrence Livermore National Laboratory pool-type reactor.