Definition of mutual thermal influence of containers with spent nuclear fuel at the open storage site

The problem of spent nuclear fuel handling in Ukraine is a key issue. A half of spent nuclear fuel is currently stored in Ukraine at the open-site dry storage facility at Zaporizhzhya NPP. Thermal safety analysis should be performed as a part of the storage facility safety assessment. Thermal analysis of a container group is a poorly investigated area. As literature review shows, current results do not clearly identify mutual influence of the containers and influence of weather conditions on the thermal condition of stored spent nuclear fuel. This type of analysis could be performed using the multi-stage methodology proposed by the authors. Thus, mutual thermal influence of the containers and boundary conditions at the inlets to the ventilation duct of each storage container should be identified. Thermal processes in the container group where spent nuclear fuel is stored that are described in this paper are analyzed by solving the conjugate heat transfer problems. A row of containers under wind influence is simulated and the structure of ventilation airflow inside the containers is identified. The mutual thermal influence of the containers is absent under calm conditions, and heated air does not come from one container to another. Resulting from the simulation, boundary conditions at the inlet of the ventilation duct are specified and can be used in the iterative modelling methodology for spent fuel thermal condition. The dependence of the velocity of the inlet ventilation air in the ventilation duct of each  container in the row was defined. The container placement methodology with the purpose of decreasing the wind influence on the thermal condition of spent fuel storage was proposed. Thermal studies are carried out for the containers and storage conditions of the dry spent nuclear storage facility at Zaporizhzhya NPP.