IN-VITRO MEASUREMENT OF UO2 PHOSPHATE ION INTERACTIONS AT THE PARTICLE SURFACE - PRELIMINARY-RESULTS USING ELECTRON DISPERSIVE ENERGY (EDS)AND P-32 ADSORPTION ASSAYS/

We have developed qualitative and quantitative methods to characterize in vitro UO2/phosphate interaction using either energy dispersive X-r ay spectrometry or adsorption measurement of P-32. U2O(PO4)(2) was use d as reference particles with homogeneous phosphorus distribution. EDS analysis at different accelerating voltages in the range of 10-30 kV has confirmed by a similar P/U weight ratio, the homogeneous chemical composition of U2O(PO4)(2), whereas after in vitro incubation of UO2 i n a medium containing 10 mM phosphate the PIU weight ratio was about t wice as high at 10 than at 30 kV. The formation of uranium phosphate a t the surface of particles was suspected. Preliminary results suggest that these individual particle analyses could be combined to a global radioactive measurement of P-32-labelled phosphate adsorption in a sui table range of phosphate concentrations and particle weights. (C) 1998 Elsevier Science S.A.