Uranium isotope exchange between gaseous UF6 and solid UF5

A new rate equation is derived for uranium isotope exchange reaction between gaseous UF6 and solid UF5 by assuming the total number of UF5 molecules on the particle surfaces to depend on time. The reaction parameters included in the equation are determined from the experimental results, and are compared with the previous ones. The rate equation given in this work satisfies the related isotopic mass balance, and includes explicitly the terms related to the UF6 density and the mean size of UF5 particles, both of which cause an important effect on the reaction. Since the rate equation derived in this work facilitates the simulation of the reaction under various conditions, the long term behavior of a simulated exchange reaction is studied under the condition considered to be close to that in a recovery zone of the MLIS (molecular laser isotope separation) process. (author)