Zirconate pyrochlore as a transmutation target: thermal behaviour and radiation resistance against fission fragment impact

Abstract Zirconates with the pyrochlore structure (A2Zr2O7) are investigated at ITU for use as an actinide host in inert matrix fuels for transmutation. Zirconate pyrochlores with A=Nd as an inactive stand in for the trivalent actinides Am and Cm were fabricated and characterised, and their thermal transport properties measured. The low thermal conductivity indicates that zirconate pyrochlore can only be used for transmutation if it is dispersed in a cercer or cermet composite fuel. The temperature profiles of a MgO–An2Zr2O7 composite were calculated using the measured Nd-zirconate thermal conductivity for different concentrations of the included phase. The radiation stability of Nd2Zr2O7 against fission products (FP) was investigated using iodine irradiation (120 MeV). Significant alterations of the implanted regions were observed even at relatively low fluence.