Thermophysical Properties of Mixtures of Thorium and Uranium Nitride

Abstract

The miscibility, lattice parameter, and thermophysical properties of (Th0.2U0.8)N and (Th0.5U0.5)N have been investigated. It is shown that additions of thorium nitride (ThN) to uranium nitride (UN) increases the thermophysical performance of the mixed nitride fuel form in comparison to reference UN. In the more dilute limit, additions of ThN serve as a burnable neutronic poison and reduces the change in keff over the lifecycle of the fuel. At higher concentrations, additions of ThN serve as a significant fertile source of 233U. Where appropriate, comparisons to previous work on UN + PuN mixtures are made, as this is a comparable fuel form for potential fast reactor concepts, and a suitable point of contrast in the possible design space afforded by mixed (ThxU1 − x)N fuel forms. The data from this work are the input parameters for finite element modeling of the temperature distribution in a compact reactor. The results of modeling and simulation of this core design are shown for the case of steady-state operation and during double, adjacent heat pipe failure.

Thermal Conductivity of Carbides and Nitrides of Zr, Th and U: Numerical Approach

“…Uranium carbide is considered as a promising material for fuel of fast nuclear reactors due to its unique properties [2]. Actinide nitrides are of interest as the fuel of nuclear power plants, since nitrides have a higher thermal conductivity compared to actinide oxides, which reduces the thermal degradation of reactors [3]. For these nuclear materials, the problem of describing their thermal conductivity has not yet been solved.…”

Advances in actinide thin films: synthesis, properties, and future directions

“…It is here where photothermal approaches offer a viable option for studying samples with small physical dimensions without damage to the sample or the need for destructive sample preparation approaches [95]. Several comprehensive reviews have been recently published on the thermophysical properties of actinide oxides [4], nitrides [96], and carbides [97,98] due to the importance of these compounds to nuclear science and industry.…”

“…Thermal conductivities have been measured for ThO 2 [141], UO 2 [142], NpO 2 [143], and PuO 2 [144]. The heat capacities of select actinide nitride systems have been measured, including ThN [145], and more recently for the UN-ThN mixtures used in nuclear fuels [96]. Among these properties, thermal diffusivity and conductivity have been recently studied as important factors in determining the properties of a nuclear fuel candidate material [4].…”

Thorium and Rare Earth Monoxides and Related Phases

“…The commercialization of molten salt reactor (MSR) technology based on a thorium cycle is on the fast track in China, with a 2 MW experimental reactor currently being tested [ 10 ]. Thorium nitride is under development as a fuel component for compact nuclear reactors, including space reactors [ 11 , 12 ].…”