Mathematical modeling of the process of decomposition of ammonium polyuranates

In the manufacture of fuel for nuclear power plants, uranium oxides play an important role, which, first of all, can be attributed to uranium dioxide (UO₂), uranium nitrous oxide (U₃O₈) and uranium trioxide (UO₃). The technology of nuclear fuel preparation provides for purification of uranium concentrate from impurities. To do this, the uranium concentrate dissolved in nitric acid is subjected to extraction purification with tributyl phosphate. Thus, solutions of uranyl nitrate are obtained, purified from impurities of other elements. The concentrated precipitate is filtered, and heat treated to produce U₃O₈. The study of the process of thermal dissociation of hexavalent hydrate is of great practical importance. Uranyl nitrates dissociate in a drum furnace. A drum furnace is a horizontal cylindrical apparatus within which the endothermic reaction of the thermal decomposition of ammonium polyurates to the formation of nitrous oxide-uranium oxide takes place. On the basis of the full diffusion model of the decomposition process of ammonium polyuranates, the original boundary conditions on the reaction surface are recorded, which allow to obtain a closed system of second-order partial differential equations representing a mathematical model of the studied process.