Calculation of dose rates due to loss-of-coolant accident in open-pool spent-fuel storage

The objective of the spent-fuel storage pool is shielding the worker and public from radiation emitted by radioactive decay in the spent fuel and providing a barrier for any radioactive release. In open-pool multipurpose reactor, the spent-fuel storage pool is connected to the main pool through the transfer channel. It was prepared to store 528 spent-fuel elements distributed in two racks that constructed one above the other. The loss-of-coolant accident (LOCA) in spent-fuel storage pool could result in rising of the radiation dose in the reactor building as the water level in the pool falls. The value of the radiation dose rate depends on the height of the water level above the spent fuels, and the number of spent-fuel elements stored in the storage pool during LOCA. The dose rate calculations were carried out starting from the minimum height which the water level could drop above the spent-fuel storage racks. The calculations were carried for two cases as follows: the full capacity of both racks and the full capacity of the lower rack only. Monte Carlo N-Particle Transport MCNP5 code was used to calculate the radiation dose rate above the storage pool and in the control room. The results show that the dose rate in the control room would be lower than the permissible limit when the water level height was 270 and 140 cm for the two cases, respectively. The dose rate above the storage pool would be lower than the permissible limit when the water height above the racks is higher than 385 cm in the first case, and 290 cm for the second case.