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To assist the development of scientific research prototype and engineering prototype of melten salt electrorefining equipment, electric field analysis was carried out. By using Comsol Multiphysics software, a mathematical model of electric field and electrochemical field in 10 kg/batch uranium metal spent fuel pyroprocessing molten salt electrorefining cell was built based on Maxwell principle and electrochemical theory, under the condition of constant input current density. The effects of the electrorefining cell structure, electrode distance and cathode shape on the cell electric field and electrochemical performance were studied. The simulation results show that for the PEER square cell, the energy consumption is low, current efficiency is high and economic performance is excellent. For the highthroughput frustum cone cell, the current density is high, the electrochemical current density distribution of cathode is concentrated on the anode side, the uranium deposition morphology is uniform, and the electrochemical performance is excellent. For the flat-plate cathode square cell, the current density and current efficiency are high, electrochemical dissolution and deposition rate of uranium is fast, the economic performance and electrochemical performance are excellent. For the rod cathode square cell, the energy consumption is low, the electrochemical current density distribution of cathode is concentrated on the anode side, and the uranium deposition morphology is uniform. Within the range of this study, with the increase of electrode distance, the electric field intensity of the electrolytic cell increases, the mass transfer rate of uranium ions in molten salt increases, the electrochemical anode current density increases, the electrochemical current density of high-throughput frustum cone cell increases, and the electrochemical performance of the cell is almost unchanged. But with the increase of electrode distance, the cell voltage increases, the absolute value of electrode overpotential increases, the total cathode current density decreases, the total anode current density increases, the uniformity of thermal field temperature distribution decreases, the electrochemical cathode current density of PEER square cell decreases, the current efficiency decreases, and the economic performance and thermal stability of the electrolytic cell weaken. The simulation calculated values are in good agreement with the experimental data abroad, which indicates that the model can wholly embody the uranium metal molten salt electrorefining test practice. Taking the above factors into consideration, the high-throughput frustum cone cell with parallel-plate cathode and short spaced electrodes may be the cell with the best technical and economic indicators of electric field and electrochemical field. And it should be selected according to the requirements and process conditions in actual test and application.

Aiming at the independent research and development of a simulated high-level waste liquid spray calcination transformation treatment test device, a three-dimensional multi-physical field model of spray calcination was established by means of finite element analysis method. In this paper, the simulated high-level waste liquid is a mixed solution of nitrate solution and sucrose. The main chemical components of nitrate dissolution are HNO3 and NaNO3. The process of evaporation and calcination of high-level waste liquid to form oxides is also called the pretreatment of high-level waste liquid or the conversion of high-level waste liquid. In this experiment, the atomized droplets sprayed at high speed are evaporated, dried and calcined in turn in the calciner to obtain the calcined product. The distribution law of temperature flow field and chemical reaction state and results inside the test device were revealed by simulation calculation. The results show that under the condition of multi-physical field coupling, the chemical reaction temperature has an effect on the yield of the product. The temperature is positively correlated with the product concentration, and the effect of temperature on the yield of NO2 is greater than that of Na2O. At the same time, in this chemical reaction, the concentration of reactants (NaNO3 and HNO3) had a positive correlation with the concentration of main products (NO2 and Na2O). However, the rate of increase in the concentration of the main products (NO2 and Na2O) decreased with the increase of the concentration of the reactants (NaNO3 and HNO3). [ABSTRACT FROM AUTHOR]

Dihydroxyurea (DHU) was synthesized using tri-associated solid phosgene [ bis(trichloromethyl) carbonate] dissolved in dioxane and hydroxylamine hydrochloride dissolved in potassium acetate solution. The reduction of Pu(IV) by DHU was investigated using UV-Vis spectrophotometry. The reduction back-extraction behavior of Pu(IV) in 30% tri-butyl phosphate/kerosene was firstly investigated under conditions of various temperature, various DHU and HNO3 concentrations and various phase contact times. The results showed that Pu(IV) in the organic phase can be stripped rapidly to the aqueous phase by DHU. Simulating the 1B contactor of the PUREX process using a 0.1 M DHU in 0.36M nitric acid solution as the stripping agent, the separation factors of uranium/plutonium can reach 2.1·104. This indicates that DHU is a promising salt free agent for uranium/plutonium separation. [ABSTRACT FROM AUTHOR]