Conor Galvin

Picture of Conor Galvin

I joined the ASG at Imperial College as a PhD student in January 2015. My work consists of atomic scale simulation of mixed oxide and conventional nuclear fuels. Before joining the ASG, I completed an MSc in Nuclear Engineering at Imperial College London. During my Masters, I carried out a research project at ANSTO, on the oxygen diffusion and permeability of nuclear related materials, using finite element methods. As an undergraduate I studied experimental physics at University College Dublin.

Mixed actinide oxides make up 5% of nuclear fuels in operation today. Furthermore, conventional UO2 fuel effectively becomes a mixed oxide during reactor operation due to transmutation. There is also growing interest in ThO2 mixed oxide fuel due to the beneficial features of ThO2. For instance, Th bearing ores are relatively abundant in the Earth’s crust (four times more so than uranium). It has also been suggested that Th provides a more proliferation resistant path to nuclear power (although how resistant is still a matter of some debate). As a result, understanding the behaviour of mixed oxides is of considerable importance. Using molecular dynamics (MD), the work undertaken during my PhD investigates the thermal dependence of lattice parameter, linear thermal expansion coefficient, enthalpy and specific heat at constant pressure for (Th,Pu)O2 systems. Furthermore, the influence of (Th,Pu)O2 composition on oxygen diffusivity, oxygen defect energy and the superionic transition are also investigated. It is difficult to obtain experimental data at higher temperatures for mixed oxides; therefore, my simulations provide important insight for systems that are still not sufficiently well understood. Another consequence of the irradiation of nuclear fuel is the presence fission products (among them rare gases such as Xe, Kr or He). Microstructural change arise from the diffusion of fission gasses through a lattice or the formation of bubbles of trapped fission gases in voids created by radiation damage. Since practically all crystals contain dislocations any diffusion may contain a dislocation-mediated contribution. My PhD also investigates the influence of dislocations in UO2 ({100}, {110}, {111} edge dislocations and screw) on He diffusion.