Hybrid method for numerical modelling of LWR coolant chemistry

• A hybrid method for modelling radiation chemistry of the coolant is proposed.
• Non-homogeneous intra-track chemistry and secondary bulk reactions are combined.
• Principal reactions responsible for production of H2, O2 and H2O2 are indicated.
• Sensitivity to the rate of reaction H+H2O=OH+H2 is discussed.

A comprehensive approach is proposed to model radiation chemistry of the cooling water under exposure to neutron and gamma radiation at 300 °C. It covers diffusion-kinetic processes in radiation tracks and secondary reactions in the bulk coolant. Steady-state concentrations of the radiolytic products have been assessed based on the simulated time dependent concentration profiles. The principal reactions contributing to the formation of H2, O2 and H2O2 were indicated. Simulation was carried out depending on the amount of extra hydrogen dissolved in the coolant to reduce concentration of corrosive agents. High sensitivity to the rate of reaction H+H2O=OH+H2 is shown and discussed.