Chemical Degradation of Kerosene Diluent with Nitric Acid

Abstract

Chemical degradation of kerosene diluent with nitric, acid was studied to clarify its effect on uranium distribution ratio and fission product retention in the presence of degradation products. The decontamination of fission products retained in degraded kerosene was also investigated. From the results of infrared spectrometry, it was recognized that nitro compounds, carboxylic acids, nitrate esters and nitroso compounds were formed as the main degradation products. The uranium distribution ratio in the extraction with TBP/degraded kerosene decreased with increasing concentration of nitric acid above 5 N, with rising temperature, and with increasing concentration of olefinic and aromatic hydrocarbons in the kerosene. It is suggested that the decrease of uranium distribution ratio may be due to the formation of carboxylic acids caused by the kerosene degradation. Some fission products, in particular 95Zr-95Nb and 131I, were retained in the organic phase, but 106Ru-106Rh did not remain after scrubbing with 3 N HNO3. Fission product retention caused a decrease of uranium distribution ratio. Usual acid-alkali washing could not remove 95Zr-95Nb and 131I into the aqueous phase, hut 95Zr-95Nb was eliminated by oxalic acid washing.