“…Among the different physical properties, the electrical and thermal properties have received special attention since they exhibit singular behaviour in the vicinity of 1300 K which is the typical temperature of UO 2 pellets in normal PWR operation. Around this range of temperature, it is observed, indeed, that electrical conductivity and heat capacity both present a drastic change in their temperature dependence [1][2][3][4][5][6][7]. This abnormal behaviour has been attributed either to the emergence of intrinsic electronic charge carriers [8,9], or to simultaneous electronic and oxygen anti-Frenkel pair disorder [10].…”