Modelling of Defective Fuel Phenomena

Abstract

A mechanistic model is reviewed for the modelling of defective CANDU fuel behaviour. This physically based treatment includes a multi-physics coupling of fission product release and fuel oxidation phenomena with the occurrence of fuel failure. The stoichiometry deviation profile is used to evaluate effects on the fission-product diffusivity and heat conduction in the fuel. Transport of steam and hydrogen gases along the fuel-to-sheath gap is considered including the partial pressure ratio of hydrogen-to-steam for evaluation of the critical ratio for promotion of secondary hydriding of the fuel element.