Hydrazine Radiolysis by Gamma-Ray in the N(2)H(4)–Cu(+)–HNO(3) System

Radiolysis of chemical agents occurs during the decontamination of nuclear power plants. The γ-ray irradiation tests of the N(2)H(4)–Cu(+)–HNO(3) solution, a decontamination agent, were performed to investigate the effect of Cu(+) ion and HNO(3) on N(2)H(4) decomposition using a Co-60 high-dose irradiator. After the irradiation, the residues of N(2)H(4) decomposition were analyzed by Ultraviolet-visible (UV) spectroscopy. NH(4)(+) ions generated from N(2)H(4) radiolysis were analyzed by ion chromatography. Based on the results, the decomposition mechanism of N(2)H(4) in the N(2)H(4)–Cu(+)–HNO(3) solution under γ-ray irradiation condition was derived. Cu(+) ions form Cu(+)N(2)H(4) complexes with N(2)H(4), and then N(2)H(4) is decomposed into intermediates. H(+) ions and H(●) radicals generated from the reaction between H(+) ion and e(aq)(−) increased the N(2)H(4) decomposition reaction. NO(3)(−) ions promoted the N(2)H(4) decomposition by providing additional reaction paths: (1) the reaction between NO(3)(−) ions and N(2)H(4)(●+), and (2) the reaction between NO(●) radical, which is the radiolysis product of NO(3)(−) ion, and N(2)H(5)(+). Finally, the radiolytic decomposition mechanism of N(2)H(4) obtained in the N(2)H(4)–Cu(+)–HNO(3) was schematically suggested.