Radiolytic hydrogen evolution in a closed vessel

ABSTRACTRadiolytic hydrogen gas evolution under the liquid-gas two-phase condition has been studied using a closed vessel and γ -rays from a Co-60 source to develop an evaluation method for the H2 evolution amount during transfer and storage of radioactive materials. An experiment was conducted using a closed vessel in which air and aerated pure water were present at room temperature. Several vessels were irradiated once with ɣ-rays at 5.2 × 103 Gyh–1. It was found that apparent G-values of H2 production, calculated with a pressure increase of the closed vessel, became smaller for the cases of higher ratio of gas phase volume to liquid phase volume due to the recombination reaction of radiolytic H2 with O2 and H2O2. Also, equilibrium H2 partial pressure became 10 times higher than the expected value using Henry’s law. These behaviours were explained by the developed model, which includes the liquid-gas distribution ratio of radiolytic H2, the equation of state for H2 in the gas phase, and the effective vo...