PLUTONIUM TRANSPORT THROUGH POROUS-MEDIA (SILICATE SAND)

The fraction of mobile Pu species for filtration of Pu solutions through silicate rock depends on the preparation method, the pH, the thickness of the filtering layer, and the solution composition. The fraction of mobile Pu species is 2-20% for filtration of solutions containing 2.3 . 10(-8)-8.6 . 10(-7) M Pu and 0.05 M NH4NO3 through a layer of quartz sand 4.5 cm in height with an average grain size of 310-290 mu m. The minimal values are observed for solutions in which hydrolysis and polymerization of Pu hydroxy complexes are most extensive. Plutonium is weakly retained by a layer of quartz sand from solutions containing humic substances. This is due to the binding of Pu to finely dispersed colloidal soil particles that pass through the quartz sand with an average grain size of 310-290 pm. Washing the layer of quartz sand containing Pu with various solutions at pH 6-7.7 does not substantially mobilize the Pu.