Thermal state of ventilated storage container with spent nuclear fuel under normal operation

Abstract

Thermal state is an important part of the safety assessment of any nuclear facility. Numerical studies of the thermal state of a container with Spent Nuclear Fuel (SNF) are carried out. The problem was considered in conjugate quasi-static formulation as a part of the multistage approach to the simulation of the thermal processes at the dry SNF storage. Mathematical model and calculation approach to the problem solving were verified by comparison with calculated and measured temperatures of ventilated air in the outlet vents. The storage container, which is operated on Zaporizhska NPP (Ukraine), was modelled under normal operation. The structure of cooling airflow inside the container and distribution of temperature and heat flux density on surface of the storage cask were detected. The maximum temperatures inside the storage container at the average monthly temperatures during the year were calculated, temperature fluctuation is about 23°C. The operation of the ventilated storage containers with spent nuclear fuel on Zaporizhska NPP is safe. Obtained results must be used at the development of the ageing management program for the dry SNF storage facility on Zaporizhska NPP.