Simulation of the inhibition of water α-radiolysis via H2 addition

Abstract

The continuous formation of H2, O2, and H2O2 observed in water during α-radiolysis may be suppressed by the addition of H2 above the threshold hydrogen concentration (THC). Using the FACSIMILE simulation code, water radiolysis was reproduced in order to determine the THC and clarify the mechanism at room temperature. Using the reaction set and rate constants reported by Ershov and Gordeev together with the primary yields for water decomposition products generated using 12 MeV α-particles, the THC was found to be 165 μM. Further simulation results clearly showed that the value of THC is strongly dependent on the reaction set and rate constants. In addition, a possible mechanism involving a chain reaction governed by the two reactions OH + H2 → H + H2O and H + H2O2 → OH + H2O was proposed. Furthermore, the same inhibition effect was found when a high-temperature simulation (300 °C) was performed, but the concentration range and THC were much smaller than the values obtained at room temperature. The importance of the reverse reaction OH + H2 → H + H2O was also investigated.