Computational analysis of PT/CT contact behavior for a heavy water reactor at high temperature and pressure

A computational model has been developed for a heavy water reactor (HWR) reactor to analyze the temperature distribution of the moderator and pressure tube and to determine the thermal stress analysis of pressure tube (PT) using the non linear elastic model for thermal expansion. For an IAEA ICSP problem, the experimental set up and model were developed by the Fuel Channel High Temperature Heat Transfer (FCHTHT) laboratory in Canada. In case of LOCA or primary heat transfer failure, PT experiences a significant heat flux that results in ballooning of PT. Following the PT deformation, PT/CT contact may occur and thus there is spike in heat flux at calandria tube (CT) resulting in the local dryout of CT. The study was divided into two parts, pre-contact phase and contact phase. The analysis is made by using the COMSOL multiphysics software. The results reveal the effect of buoyancy and support the validation of experimental set up where the graphite heater is offset below the centre to account for the buoyancy effects. The PT was deformed at higher temperature and came in contact at 74.4 seconds.