STUDIES OF THE SPECIATION OF PLUTONIUM AND ETHER ACTINIDES IN NATURALGROUNDWATER USING ANION-EXCHANGE RESIN

The chemical speciation of radionuclides can have a dramatic effect on mobility in groundwater, because sorption by soil depends on speciati on. An anion exchange technique has been developed and used to study t he chemical speciation of radionuclides in a contaminant plume origina ting from an infiltration pit used for managing low-level liquid waste s. The principle radionuclides present include H-3, Sr-90, Co-60 and R u-106, but plutonium and other actinides are also present at very low levels. The major dissolved species of Co-60, Ru-106 and actinides in this plume are anionic and are strongly adsorbed by anion exchange res ins. The anion exchange technique has been used to concentrate the ani onic species from up to 6 L of groundwater and then chromatographicall y separate them by elution with salt and acid solutions. The developme nt work focussed on Co-60 and Ru-106, which are easier to measure than the actinides. The same technique was subsequently used to concentrat e and separate the anionic species of Np, Pu, Am and Cm isotopes in th e plume. The technique can be used analytically to measure changes in radionuclide speciation. It can also be combined with other techniques , such as size exclusion chromatography, to further characterize speci es in fractions collected during separation.