Influence of boron isotope ratio on the thermal conductivity of uranium diboride (UB2) and zirconium diboride (ZrB2)

Uranium diboride is being proposed as an accident tolerant fuel (either as a part of a composite or a 11B enriched monolithic fuel pellet), while zirconium diboride is often selected as a burnable absorber in conjunction with uranium dioxide fuel pellets. It is therefore important to understand the thermal properties of these materials and examine methods in which they may be improved. The thermal conductivity of UB2 and ZrB2 is calculated through atomic scale modelling methods. It was found that the boron-isotope ratio has a significant impact on the thermal conductivity of ZrB2, but is negligible for UB2 due to the large electron-phonon scattering.