A short review of the mechanisms of hydrogen generation from radiolysis of water is presented for conditions ranging from ambient to high temperatures. Factors affecting the hydrogen generation include the type of radiation, the linear energy transfer (LET) of the radiation and the physical conditions of pressure and temperature. An understanding of radiation chemistry of high temperature water is important to maintain integrity and safety of water-cooled nuclear power reactors. Exposition of the coolant to fast neutrons and gamma rays, at ca. 320°C, generates transient radiolytic species, which finally form stable molecular products: H2 and corrosive O2.
Computational methods closely integrated with measurements provide qualitative and quantitative insights into the radiation-induced chemistry at different time scales replacing difficult or dangerous experiments in severe environment. An overview of computing capability of the hybrid method proposed for numerical modelling of radiation-induced chemistry of the cooling water is also presented. Significant sensitivity to the rate constant of the reaction H• + H2O → •OH + H2 on the calculated steady-state concentrations of O2, H2O2, and H2 is discussed.
Financial support under Research task No. 7 “Study of hydrogen generation processes in nuclear reactors under regular operation conditions and in emergency cases, with suggested actions aimed at upgrade of nuclear safety” financed by the National Research and Development Centre in the framework of the strategic research project entitled “Technologies Supporting Development of Safe Nuclear Power Engineering” is greatly acknowledged.