The potential for a fission product release under accident conditions was analyzed for a maximum hypothetical accident consisting of cladding failure in the high-power fuel assembly (25 kW) after continuous full-power operation. The accident analysis was carried out with and without an intact water pool and operating ventilation system.[64] Reactivity insertion was also analyzed. Additionally, a loss-of-cooling accident was analyzed to determine the fuel temperature and radiation dose from the exposed core.

The accident analysis used Oak Ridge National Laboratory’s ORIGEN code to calculate the fission product inventory in case of accident. An analy­sis of release fractions used a Gaussian plume model, and radiation doses were calculated using MCNP5.

The accident analysis had an overall positive outcome. LEU conversion required no changes in response to any accident. The reactor remained within regulatory limits under all variations to the maximum hypothetical accident.

This analysis had another positive benefit: The university’s capabilities to analyze core accidents increased significantly; previously, only simple methods and models had been used to analyze such accidents. As a result, a more detailed understanding of the potential radiation dose was gained, including the time-dependent behavior and the spatial distribution of dose.