Evaluation of temperature distribution in a nuclear fuel with cladding detachment

The interaction of a radiation field with a nuclear material of a fuel cartridge is expressed by local changes of physical nature. The cladding material, submerged in a corrosive atmosphere and designed to be in intimate contact with the mechanically dynamic fuel, is often detached both in axial and circumferential directions. This separation is characterized by poor heat transfer conductance through the cladding, affecting the nominal temperature distribution by increasing the values beyond the maximum safety limit of design. Furthermore, in extreme conditions, the local overheating of the nuclear fuel will cause the evaporation of the coolant flow along the cladding and ultimately the melting of the fuel. Previous analytical analysis, limited by the complex nature of the topic, enable only 2-dimension approximations where the separation is considered to be completely circumferential along a prescribed axial length. Alternately, one can consider a separation of the full length over a prescribed angle. Considering the above mentioned and the present advanced numerical calculation tools, a 3-D precise calculation of the temperature distribution in a nuclear fuel motivated the present work.(authors). 1 ref., 4 figs