Kinetic Measurements for the Carbothermic Synthesis of UN, PuN, and (U,Pu)N

Abstract

A kinetic study of the synthesis of nitrides using carbothermic reduction of UO, and PuO, in flowing N2 was conducted. Reaction rate constants as functions of the reaction temperature and Nz flow rate were determined. The measured rate constants varied with temperature according to the Arrhenius equation a t constant N2 flow rates. In logarithmic form, the measured rate constants also varied linearly with N2 flow rate at constant temperature, up to a f l~w rate o f 120 cm"/min-g of reactant. The rate constant for a particular reaction temperature and N, flow rate can be calculated from the logarithmic form of the Arrhenius equation by adding a flow-rate term. The expressionIn k(7.,F)=( -86,000/RT)+18.1+0.021Ffits the kinetic data from 1430" to 1625'C. Close agreement was obtained between calculated and experimental rate constants determined for 50-g batch production runs. The reaction rates measured are considered rapid enough for an economical nitride process.

Fabrication and electrochemical behavior of nitride fuel for future applications

“…Results of thermogravimetry indicated carbothermic reduction obeys with the first order rate equation and the reaction rate is controlled by a solid-state diffusion process across the product layer [16][17][18]. So it is reasonable to use fine powders of dioxide and carbon.…”

Synthesis and Optimization of the Sintering Kinetics of Actinide Nitrides

“…A few authors used thermogravimetric techniques to study the reaction kinetics of Reaction 7 and report that the reaction follows a first order rate law according to Equation 3 [69,74,95], where α 0 is the reaction ratio and k 0 is the reaction rate. Following these results, the data was plotted on an Arrhenius plot to determine an activation energy, which was found to be between 300 -360 kJ / mol , depending on the author and the study [69,74,95].…”

Synthesis of uranium nitride by a mechanically induced gas–solid reaction

“…Many authors have studied various synthesis routes for economically producing large quantities of high purity nitride powders [1][2][3][4][5][6][7][8][9][10][11][12][13]. Much of this previous work has focused on optimizing the carbothermic reduction of uranium dioxide (UO 2 ) prior to nitriding to form UN.…”