Effects of edge dislocations on thermal transport in UO2

Molecular-dynamics simulations are used to characterize the effects of dislocations on the thermal transport properties of UO2. Microstructures with various dislocation densities of the order of 1016 m−2 are simulated at temperatures between 800 and 1600 K. The effects of dislocations on the thermal-transport properties are found to be independent on temperature, consistent with the classic Klemens–Callaway analysis. The effect of dislocation density is also quantified. The simulation results are also fit to the pertinent part of the empirical formula for the thermal conductivity used in the FRAPCON fuel-performance code, which gives the overall effects of temperature and dislocation effects on thermal conductivity. The fitted results can be well-described within this formalism, indicating that the results of molecular-dynamics simulations can be used as a reliable source of parameters for models at longer length scales.