Formation of nitrogen compounds in N,-H 2 0 systems under radiation was studied. A reaction scheme with 24 species and 73 reactions was proposed. Two trigger reactions for nitrogen atom generation: N, ~ 2N (o-value of 1.6 pmol per 1 kJ absorbed energy in N 2 molecules), and N2+H20*-NH 2 +NO (k=3.0 x 10 9 s-at 298 K with activation energy of 34.4 kJ/mol) were included. Calculated results with the reaction scheme agreed within an error factor of two with ammonium formation rates from an aqueous solution with dissolved nitrogen and hydrogen gasses under r-irradiation at temperatures of 288-473 K. The reaction scheme was also verified with BWR plant observations on nitric acid formation from in-leaked air under hydrogen water chemistry and ammonium injection tests.

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The γ-ray-induced oxidation of toluene in liquid carbon dioxide has been reinvestigated. In order to discuss the precursors of the main products: three kinds of cresols and benzyl alcohol, 1-butene was used as the scavenger of oxygen atoms. The formation of cresols and benzyl alcohol was well explained by the participation of two precursors: one is oxygen atoms and the other is ionic species, O− or/and CO3− ions. The ratio of the G-value of oxygen atoms to that of the sum of O− and CO3− ions initially formed was estimated to be 4 : 1 for pure liquid carbon dioxide. The spur model previously proposed was applied to explain the formation of O− and CO3− ions.