Study on Fabrication and Microstructural Analysis of U₃Si₂ Fuel Pellets

Uranium silicide is formed from ingot of uranium and silicon in near stoichiometric quantities by arc melting. And then uranium silicide pellets were produced by conventional powder metallurgy. The effect of pellet compression molding and sintering on density and the microstructure of U₃Si₂ pellets were studied. It turned out that,0.5% of PEG was added to be binder and the green pellets was got with a pressure ranging from approximately 260 to 300 MPa, then the pellets were sintered with a temperature of 1550°C for 2-4h. To this end, high phase purity U₃Si₂  with density 11.4 g/cm³,which is above 93% of theory density, is produced. The pellet size is uniform and the average grain size is about 60μm, but there is a little U or UO₂ impurity in sample U₃Si₂ pellet. The thermal conductivity of U₃Si₂ pellet is superior to UO₂, and rise approximate linearity with the increasing of temperature.