Radiolysis of water at elevated temperatures. Pt. 2: Irradiation with γ-rays and fast neutrons up to 2500C

Determination of G-values of water decomposition products in neutral water formed by irradiation with γ-rays and fast neutrons at elevated temperatures up to 250oC was carried out by a combination of the NaNO2, acetone + methanol, and HClO4 + methanol solutions, which had been established at room temperature. By using a mass balance relation, the value for water decomposition, G-H20, was calculated. The yields of H2O2, formaldehyde and ethyleneglycol produced as a function of dose in the NaNO2 and HClO4 + methanol solutions were chosen to derive the GOH and GH202 by fitting the simulated calculation to the experimental results. In the γ-radiolysis, the G-values obtained in the present experiment are in good agreement with recently reported ones except for the GOH and GH202. The Gequ- for γ-radiolysis is in a good agreement with the reported values up to 200oC, but slightly lower at 250oC. The water decomposition gives a similar pattern with Geaq- yields. The GOH does not change significantly with temperature, which is contrary to the evaluation by other groups and the GH202 tends to increase with temperature. (author)