Uranium oxide, UO2 and

The conventional approach starts with uranium oxide (UO2) and includes two technological stages. The first one is exothermic conversion of the oxide into fluoride with HF ... 

The limitations on possible linear rating and burn-up levels imposed by the characteristics of metallic uranium have led to the development of ceramic forms of fuel such as uranium oxide (UO2) and uranium carbide (UC) pellets. While fuel performance is considerably enhanced by the use of the ceramic form, problems arise due to densification of the fuel and fuelcladding interaction in a radiation environment, leading to the formation of interpellet gaps and clad flattening. 

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