Leaching behavior of uranium from growing in aqueous solutions

Taking account of the most water soluble property of uranium element in the actinide series, the behavior of uranium under granite-water environmental situations was studied and the following results were achieved. (1) The concentration of uranium at the upper stream of river Yoshii, the granite zone, was found to be proportional to third power of the concentration of nitric acid. It seemed to us that uranium in the river water has the chemical form of [UO2(CO3)3]4-. (2) Dissolution testing of pulverized granite showed that uranium did not dissolve in water under acidic condiktion, whereas it dissolved greatly in water under alkaline condition. (3) In the dissolution testing, the rate determining step of the dissolution of uranium was prove to be the diffusion process and the apparent activation energy was amounted to 4.26 KCal/K.Cal. The dissolution was inversely proportional to one third power of the granule dia. of the granite. (author)