Nuclear fission by its very nature induces change, i.e. transmutation of elements, how a structure accommodates this change is vital to the long-term stability of nuclear fuel. Current nuclear fuel is based on UO2, adopting the cubic fluorite structure, many fission products are soluble within this structure, and can give rise to new phases being formed. These new phases will impact fuel performance, through modification of thermophysical properties, thus potentially reducing the ability of the fuel to be used within the core longer term. The project examines the impact arising from the formation of phases which form as precipitates in the fuel, with a structure formed from ‘non-equilibrium’ synthesis.
The formation of fission products within fuel, dramatically impacts both the thermophysical and structural response coupling in many cases with the induced radiation damage. For example, not only will fuel
experience change in microstructure through formation of gas bubbles, but such change induces a reduction in thermal conductivity, which leads to heat being retained within the fuel. Fission product formation within the fuel can either be soluble, or insoluble, with each having differing impact on behaviour. For many fission products there is a miscibility gap in solubility. For example, in the systems U-Ln-O, the miscibility gap gives rise to the formation of new phases, forming coherent domains within the broader matrix. Domain behaviour, and formation is not fully understood and is ripe for further examination.
Contact: Prof Karl Whittle