Radionuclides in groundwater at the Savannah River Plant Waste Disposal Facilities

At the Savannah River Plant, disposal of radioactivity to the ground has been limited to the burial of solid waste and the discharge of very-low-level waste to open seepage basins. Although solid wastes have been subjected to leaching by an annual rainfall of 45 to 50 inches since 1953, no radionuclides have been detected in groundwater from this source. Seepage basin retention of radionuclides has been less satisfactory. All of the radionuclides released to the seepage basins, except plutonium, have been detected in the surrounding groundwater. Fission-product tritium, present in water, is not adsorbed and thus serves as a useful groundwater tracer. Strontium 90 is poorly adsorbed on local soil (under the acidic conditions usually present in seepage basins), and is detectable in sand layers, at concentrations less than the Radioactivity Concentration Guide, as far as 500 feet from the basins. The radionuclides of cerium, cesium, ruthenium, zirconium, and niobium do not migrate as far as those of strontium. The path of radionuclide migration from the seepage basins [excavated in the Hawthorn formation (Miocene)] is determined by the geology and hydrology of each area. Most of the migration of radionuclides has been through sandy strata or sand-filled clastic dikes. Wherever the soils do not contain these imperfections, migration has been slow.