The leachability of some natural and man-made radionuclides from soil and sediments on acid attack

A radiotracer study was made of the teachability of some natural and man-ma de radionuclides from soils and sediments subjected to attack by various ac id mixtures. Particular attention was paid to the nuclides U-238. Th-232, P a (as Pa-233) and Np (as Np-239), since for these neutron activation can be used to study recoveries and/or to induce in situ radionuclides in samples . Thus conventional NAA allowed determination of total U-238 and Th-232 ins trumentally, and also enabled analysis of leachates and residues by radioch emical or instrumental NAA. Activation of these nuclides produced samples e ndogenously labelled with Pa-233 and Np-239 whose behaviour on acid dissolu tion/leaching could be examined. Furthermore, comparison of neutron irradia ted and non-irradiated samples allowed us to investigate the possibility of increased leachability induced by nuclear recoil reactions; however. this effect was negligible. We also investigated the acid leaching of americium adsorbed on the surface of sediment. in general, unsatisfactory leaching re coveries were found for Pa-233, Np-239 and Th-232 for most materials, indic ating the need for total dissolution procedures.