DISSOLUTION KINETICS OF U3SI2 PARTICLES IN ALKALINE HYDROGEN-PEROXIDE

Nonproliferation concerns leading to the conversion from high- to low- enriched uranium sparked interest in U3Si2 dispersion targets as an op tion for Mo-99 production. Dissolution of irradiated targets is an imp ortant step in recovering fission-product Mo-99. Alkaline hydrogen per oxide solutions dissolved U3Si2 particles in an open batch reactor; sa mples were analyzed for total peroxide and uranium concentrations as f unctions of time and temperature. Dissolution rates are highest at 1 t o 1.5 M NaON and change little for initial base concentrations from 0. 5 to 2.5 M NaON, indicating relatively robust process conditions. Uran ium dissolution rates depend most strongly on the equilibrium concentr ation of the peroxyl ion (O2H-), an equilibrium product of hydrogen pe roxide (H2O2) and hydroxyl ion (OH-). Temperature and equilibrium conc entrations of O2H- and OH- are included in a uranium dissolution rate model.