In-situ synthesized nanocrystalline UO2/SiC composite with superior thermal conductivity

In this study, a novel UO₂/SiC nanocomposite pellet was constructed via in-situ hydrothermal synthesis and SPS. Such method could avoid the problem of traditional mechanical mixing that could obtained the molecular level mixing during a chemical process. Using such method, SiC was dispersed uniformly in the UO₂ matrix. Its thermal conductivity is significantly higher than those of UO₂ pellet fabricated using hydro-thermally prepared powder and traditional UO₂ pellets at both working temperature (400 °C) and near-accident temperature (1000 °C). The thermal conductivity of UO₂/SiC nanocomposite pellet increased 23.7 % over traditional UO₂ and 48.9 % over UO₂ pellet fabricated using hydro-thermally prepared powder at 400 °C. It also increased 33.6 % over traditional UO₂ and 74.8 % over UO₂ pellet fabricated using hydro-thermally prepared powder at 1000 °C. These advantages are expected to maintain high thermal conductivity of fuels, enhance heat transferring efficiency of reactors, and minimize risks of pellet failure in the entire fuel life cycle.