Thermodynamic analysis of chemical and phase composition of metallic uranium irradiated with thermal neutrons and distribution of fission products and plutonium

Abstract

A thermodynamic analysis of the chemical and phase composition of metallic uranium irradiated with thermal neutrons until burnup to 1% was carried out using ASTRA-4 software over a temperature range of 400–800 K. The radial distribution of metallic fission products in the irradiated uranium core was shown to be nonuniform; the concentration thereof in surface layers was several times higher than in the core center. Plutonium was distributed analogously. Due to the limited solubility of a number of fission products, the precipitation of intermetallides, such as U(Ru,Rh,Pd)3 occurs in α-U. Carbon impurities in uranium stipulate the emergence of carbides of such metals as U, Zr, Ce, whose distribution is similar to the distribution of uranium and metallic fission products.