Hydrazine Radiolysis by Gamma-Ray in the N2H4-Cu+-HNO3 System.

Naon Chang,Seonbyeong Kim,Yongsoo Kim,Sangyoon Park,Huijun Won,Bumkyung Seo,Heechul Eun

doi:10.3390/ijms22147376

Abstract

Radiolysis of chemical agents occurs during the decontamination of nuclear power plants. The γ-ray irradiation tests of the N2H4–Cu+–HNO3 solution, a decontamination agent, were performed to investigate the effect of Cu+ ion and HNO3 on N2H4 decomposition using a Co-60 high-dose irradiator. After the irradiation, the residues of N2H4 decomposition were analyzed by Ultraviolet-visible (UV) spectroscopy. NH4+ ions generated from N2H4 radiolysis were analyzed by ion chromatography. Based on the results, the decomposition mechanism of N2H4 in the N2H4–Cu+–HNO3 solution under γ-ray irradiation condition was derived. Cu+ ions form Cu+N2H4 complexes with N2H4, and then N2H4 is decomposed into intermediates. H+ ions and H● radicals generated from the reaction between H+ ion and eaq− increased the N2H4 decomposition reaction. NO3− ions promoted the N2H4 decomposition by providing additional reaction paths: (1) the reaction between NO3− ions and N2H4●+, and (2) the reaction between NO● radical, which is the radiolysis product of NO3− ion, and N2H5+. Finally, the radiolytic decomposition mechanism of N2H4 obtained in the N2H4–Cu+–HNO3 was schematically suggested.

Highlights

It is necessary to analyze the radiolysis of N2 H4, which is the major component of the N2 H4 –Cu+ –HNO3 decontamination solution, during irradiation
In order to investigate the effect of copper ions on the N2 H4 decomposition, γ-ray was irradiated to the N2 H4 –Cu+ –HNO3 solution and N2 H4 –HNO3 solution at pH 3
The decomposed portion of N2 H4 increased with the increase in the absorbed dose regardless of the presence of the Cu+ ions. This result indicates that the amount of radiolysis products of water participating in the N2 H4 decomposition was enhanced when the absorbed dose was increased

Summary

Introduction

The decontamination solution containing N2 H4 is developed to reduce the damage of the base metal and the secondary radioactive wastes compared with the decontamination using organic acid [5,6]. They are composed of N2 H4 and inorganic acids such as HNO3 and H2 SO4 [5,6,7]. The metal ions can be added into the decontamination solution containing N2 H4 for improving the decontamination performance [8]. It is necessary to analyze the radiolysis of N2 H4 , which is the major component of the N2 H4 –Cu+ –HNO3 decontamination solution, during irradiation

Methods

Results

Conclusion