SOLUBILITY TESTS ON VARIOUS URANIUM(IV) PHOSPHATES

The corrosion resistance of uranium phosphates, in powdered or pellet form, was investigated in distilled and mineral waters. The uranium co ncentration in the solutions was determined by means of Time-Resolved Laser-induced Fluorescence (TRLIF) of uranyl ion and gamma spectroscop y of U-230. The influence of some parameters like V/m ratio (solution volume to sample weight), oxidation state of the uranium tracer and ac idity of the water, was also studied. The average uranium concentratio n in the obtained solutions is in the range of 2.5 x 10(-4) M to 7.3 x 10(-5) M. These rather high concentration values could be due to the sensitivity of U (IV) to dissolved oxygen in the water, which oxidizes uranium (IV) on the surface of the grains. The solubility of the mixe d-valence uranium uranyl phosphate U(UO2)(PO4)(2) was found to also de pend on the acidity of the medium.