Sorption studies of plutonium on geological materials

G M N BASTON*; J A BERRY*; M BROWNSWORD*; D J LLETT*; C M LINKLATER*; S W SWANTON*; Tweed, C. J.*

JNC TJ8400 99-078, 72 Pages, 1999/03

JNC-TJ8400-99-078.pdf:3.37MB

A desk study has been carried out to establish the feasibility of measuring the oxidation state of plutonium under near-neutral strongly-reducing conditions. X-ray absorbance spectroscopy appears to be capable of establishing the oxidation state of plutonium sorbed on a suitable substrate. An experimental and modelling investigation has been performed to study the sorption of plutonium onto basalt, mudstone and sandstone under strongly-reducing conditions at three concentrations of carbonate. Appropriate synthetic rock-equilibrated de-ionised water and seawater were used. A model has been developed to describe the sorption of plutonium onto basalt, mudstone and sandstone in de-ionised water and seawater. Predicted R values are generally in good agreement with the observed experimental measurements. The model is based on sorption of plutonium(III) species and assumes iron oxide is the dominant sorbing phase.