Simulation of coolant mixing in a BWR spent fuel storage pool and flood chamber

The waiting times in case of failure of the cooling system of the spent fuel storage pool were determined with the three-dimensional numerical calculation tool ANSYS CFX. With the calculated variant, it is assumed that the swivel gate is opened when required. For the decay heat of 1.5 MW, waiting times until the spent fuel storage pool has been heated to 60 °C or 80 °C were calculated and the temperature offset between the spent fuel storage pool and the storage chamber pool was determined.

The calculations showed that the coolant from the flood chamber and the storage chamber, which is located above the lower edge of the open swivel gate, mixes ideally with the water from the spent fuel pool. The results of the CFD analysis can be used for the cross-code verification of models in integral codes.