Thermal Simulation of the CANDU (Pickering) Fuelling Machine During Refuelling

Abstract

During on-line refuelling in CANDU (Pickering) Nuclear Power Plants, the fuelling machine is used to remove the irradiated fuel bundles from the reactor and replace them with new fuel. This refuelling operation creates thermal transients in the fuelling machine which cause stresses. To evaluate these thermal stresses in the snout of the fuelling machine, which is already considerably stressed due to mechanical loading, the fuelling machine along with the fuel channel/transfer port is analyzed using finite element technique. A thermal analysis is performed for a coarse meshed model of the fuelling machine - fuel channel/transfer port structure to calculate the temperature distribution in the structure at different time points. The calculated temperature is then interpolated on a fine meshed model of the front portion of the fuelling machine and a stress analysis is performed to determine the maximum thermal stresses in the fuelling machine.