Hydrothermal synthesis of uranium dioxide and graphene composite and its application as an additive for uranium-dioxide-based accident tolerant fuel

A novel kind of composite constructed by uranium dioxide and reduced graphene oxide (RGO) was developed via a one-step hydrothermal reduction method, named as UO2@G. The introduction of graphene oxide (GO) to the reaction system brought significant changes: in the control experiment without GO, the reductant of ethylenediamine itself could only reduce uranyl ions to mainly U3O8, and the final solid products appear in the form of flakes; by introducing GO to the system, the final products are pure UO2 in homogenous nanospheres. By employing UO2@G as an additive in the UO2 fuel pellet (the final volume ratio of graphene materials was controlled to be around 10%), the thermal conductivity is increased by 35.4%, which is significantly higher than that of the pellet prepared by simply mixing UO2 powders and commercial graphene nanosheets. The simulation results show that the core temperature of the pellet containing the UO2@G composite additives is much lower than that of the one without UO2@G composite additives, showing the potential as novel kind of accident tolerant fuel.