Investigation of Modified UO2 Fuel with Anomalously High Thermal Conductivity

Abstract

Pre- and post-reactor studies of the properties of modified uranium dioxide fuel fabricated by a modernized water technology, including cooling of ammonium polyuranate with large and nanosize particles obtained simultaneously followed by calcination, reduction, pressing, and sintering of pellets, were performed. The properties of such fuel are compared with those of fuel obtained by the standard water technology. It is found that the heat capacity and thermal conductivity of such fuel are 1.8–2 times higher than the reference values and that the fuel possesses high microstructural stability and capacity for retaining gaseous fission products during irradiation. This is due to special properties: the presence of nanodispersity in grains and metal clusters in which the uranium ions form U–U chemical bonds with one another.