Authors:Zhu Zhaowu, He Jianyu, Zhang Zefu, and Zhao Zhiqiang
This work is aimed at studying HNO2 generation by bubbling NO in HNO3 solution. The formation and decomposition of HNO2 depend on the 2NO+HNO3+H2O3HNO2 reaction. During the HNO2 generation, the HNO3 concentration was kept constant. The influence of HNO3 concentration, temperature, NaNO3 concentration and NO bubbling rate was studied. Its possible application in the PUREX process was evaluated.
Authors:Zhu Zhaowu, He Jianyu, Zhang Zefu, Zhang Yu, and Zheng Weifang
The kinetics of the reduction of plutonium(IV) by hydroxyurea (HU), a novel salt free reductant, in nitric acid solutions
has been studied. The observed reaction rate can be expressed as: -d[Pu(IV)]/dt=k0[Pu(IV)]2[HU]/[H+]0.9, where k0 = 5853±363 (l1.1.mol-1.1.s-1) at t = 13 °C. The activation energy is about 81.2 kJ/mol. The study also shows that uranium(VI) has no appreciable influence on
the reaction rate. Compared with other organic reductants our experiments indicate that HU is a very fast reductant for plutonium(IV).
Authors:Zhu Zhaowu, He Jianyu, Zhang Zefu, Zhang Yu, Zhu Jianmin, and Zhen Weifang
Hydroxyurea dissolved in nitric acid can strip plutonium and neptunium from tri-butyl phosphate efficiently and has little influence on the uranium distribution between the two phases. Simulating the 1B contactor of the Purex process by hydroxyurea with nitric acid solution as a stripping agent, the separation factors of uranium/plutonium and uranium/neptunium can reach values as high as 4.7·104 and 260, respectively. This indicates that hydroxyurea is a promising salt free agent for uranium/plutonium and uranium/neptunium separations.