[en] This research program has as its primary objective the description of the fate and behavior of radionuclides released to the environment from nuclear fuel chemical separations facilities. It can be grouped into two general modes of scientific approach: 1) controlled environment greenhouse uptake experiments and 2) field studies. Both modes utilize the uniquely contaminated soils and/or the ongoing operations of the separations facilities at the SRP. The greenhouse experiments seek to determine the long-term availabiltiy of radionuclides to agricultural plants from soils contaminated by a chemical separations facility. In these experiments we are also investigating factors which might modify availability of nuclear contaminants such as different crop species, soil amendments, and soil types. The field research focuses primarily on the environmental behavior in agricultural corps of chronic low-level releases of uranium. From the greenhouse uptake studies, any temporal effect on Pu and Cm uptake is inconclusive, with variable effects from different crop species, radionuclides, and soil treatments. in plant tissues of wheat and soybean crops grown near F-Area separations facility, root uptake is more important in contributing to U concentrations than Pu. This is in distinct contrast to the behavior of Pu in agro-ecosystems, where surficial pathways are the dominant modes of contamination, and is probably related to (1) the ubiquitous presence of naturally occurring U isotopes and (2) a greater phytoavailability of U than did wheat. Completion of corn radionuclide analysis will allow comparisons between Pu and U behavior and among wheat, soybean, and corn crops