Simulating Thermal Behaviour of AECL's Spent Fuel Dry Storage System with CATHENA

Abstract

This paper documents the comparisons between CATHENA predictions and temperature measurements taken at the Gentilly-2 NPP spent fuel dry storage facility and in a mockup of a storage basket placed inside a storage cylinder. It also presents CATHENA temperature predictions related to the storage of spent fuel in MACSTOR modules as planned for Ignalina NPP. Lithuania. CATHENA has been chosen because it can simulate many noncondensable gases including air and helium, and because of its great flexibility in the representation of the MACSTOR module geometry. The results of the simulations show good agreement with the experimental measurements. The two comparisons indicate that CATHENA can be used to simulate heat transfer from the fuel to the external air circuit of the spent fuel dry storage system. For the Ignalina MACSTOR module, containing RBMKfuel having higher heat release than typical CANDUfuel, CATHENA predicts that the maximum fuel temperature is expected to be around 240 degrees C, giving an acceptable margin below the maximum allowed temperature of 300 degrees C. In conclusion, this paper shows that the thermalhydraulic code CATHENA can accurately predict the thermal behavior of AECL's air cooled spent fuel dry storage system.