Simulations of H2O2 concentration profiles in the water surrounding spent nuclear fuel taking mixed radiation fields and bulk reactions into account

To simulate the dynamics of the concentration gradient of hydrogen peroxide in groundwater surrounding spent nuclear fuel under various conditions, a model has been developed. The model treats the water volume as a sequence of volume elements, and applies the processes that affect hydrogen peroxide concentration to each volume element. The surface steady-state concentrations of H2O2, and the time to reach steady-state, have been determined under different conditions. The processes accounted for in the model are radiolytic production of H2O2 from α- and β-radiation, surface reactions consuming H2O2, homogeneous reactions consuming H2O2, and diffusion. The system has been modeled mainly for different surface reaction rate constants and homogeneous (bulk) reaction rate constants. The simulations show that the surface concentration of H2O2 approaches the steady-state concentration very rapidly and that the impact of homogeneous (bulk) reactions consuming H2O2 on the steady-state concentration is significant.