RADIOLYSIS OF WATER AT ELEVATED TEMPERATURES-Ⅲ. SIMULATION OF RADIOLYTIC PRODUCTS AT 25 AND 250℃ UNDER THE IRRADIATION WITH γ-RAYS AND FAST NEUTRONS

摘要

The G-values of water decomposition products under the irradiations with γ-rays and fast neutrons up to 250℃ have been determined in previous studies. In order to clarify the characteristics of the determined G-values, computer simulations under the simplified conditions in nuclear reactors have been carried out. The recent G-values for γ-radiolysis reported by Elliot, Chenier and Quellete [(1990) Can. J. Chem. 68, 712; (1993) J. Chem. Soc. Faraday Trans. 89, 1193], Kent and Sims [(1992) Water Chemistry of Nuclear Reactor Systems 6, p. 153. BNES, London], and Sunaryo, Katsumura, Shirai, Hiroishi and Ishigure [(1994) Radial. Phys. Chem. 44, 273] and Sunaryo, Katsumura, Hiroishi and Ishigure [(1995) Radial. Phys. Chem. 45, 131] are almost equivalent from the point of simulations. On the contrary, C-values for fast neutron radiolysis give a significant influence to the result, which arises from the higher molecular yields and smaller radical yields of water decomposition in fast neutron radiolysis, and it has been revealed that the dose evaluation in the reactor is inevitably important. In addition, it was pointed out by the simulations that reverse reactions for H_2 + ~·OH→H~· + H_2O and e_(aq)~- + H~+ → ~·H, which can be neglected at room temperature, become important at higher temperatures.