Predictions of Radionuclide Migration Rates for a Subseabed Repository
- PDF / 544,845 Bytes
- 8 Pages / 420.48 x 639 pts Page_size
- 40 Downloads / 247 Views
Inc.
287
PREDICTIONS OF RADIONUCLIDE MIGRATION RATES FOR A SUBSEABED REPOSITORY* L. H. B1USH Seabed Programs Division 4516, Sandia National Laboratories, Albuquerque, NM 87185 ABSTRACr Geochemical research carried out by the U.S. Subseabed Disposal Program is described. Data from studies of high temperature interactions between sediments and porewater (seawater), and of sorption and diffusion of radionuclides in oxidized, deep-sea sediments are used, along with results from heat transfer studies, to predict migration rates of radionuclides in a subseabed repository. Preliminary results for most radionuclides in oxidized sediments are very encouraging: fission products with moderate values of KD (generally 10 to 10 ml~g), an. actinides with high values of KD (generally 10 to 10 ml/g) would not migrate significant q•stanms before2 icaying to innocous concentrations. Cs, Sr, and Pu are among this group. The results for anionic species are less encouraging, but preliminary work with reduced sediments indicates that Tc can be effectively isolated. Planning for a field verification of these laboratory and modeling studies is also described. INTRODUCTICN The U.S. Subseabed Disposal Program (SDP), begun in 1974, has been assessing the technical, envirornental, and institutional feasibility of disposing of high level nuclear waste or repackaged spent fuel in deep-sea sediments. One major objective of the SDP has been to evaluate subseabed disposal as the primary alternative to mined geologic disposal of high level waste, the option currently favored by the U. S. Department of Energy. The choice of subseabed geologic formations as the primary alternative is justified by the fact that oceans cover roughly 70 percent of the Earth's surface; these vast areas cannot be overlooked in a thorough search for solutions to the problem of radioactive waste management. Moreover, many deep-sea sedimentary formations reside in what is probably the most stable tectonic environment on Earth, the mid-plate regions of the oceanic crust. Recently, the subseabed option has come to be viewed as complementary to mined geologic disposal. The removal of radioactive iodine fran high level waste, and its disposal in subseabed sediments is one exanple of how the subseabed cption might ccmplement mined disposal [I]. The other major objective of the SDP has been to monitor the ocean-disposal activities of other nations. Even if the U.S. does not utilize the subseabed cption, other nations (especially those of limited size, or with unfavorable geologic environments) might resort to ocean disposal of high level waste. *
This work performed at Sandia National Laboratories supported by the U. S. Department of Energy under contract number DE-ACO4-76DPO0789.
288 (Several nations are currently disposing of low level waste at sea.) This monitoring function is facilitated by U.S. participation in the Seabed Working Group, under the auspices of the Nuclear Energy Agency of the Organization for Econcmic Cocperation and Development. This paper is devoted to a
Data Loading...
