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As a result of the discharges of large volumes of low-level radioactive liquid wastes to surface stream at the Oak Ridge National Laboratory, large quantities of radionuclides have accumulated in the bottom sediments of White Oak Lake. Ruthenium-106 (1038 c) and cesium-I37 (704 c) account for more than 90 per cent of the total activity now present at the site, while G°Co (152 c), the rare earths (17 c, exclusive of and %k (15 c) make up the remainder. More than half of the activity is associated with the upper 6-in. sediment layer, while progressively smalIer quantities of activity are found with depth. The ruthenium, which is restricted to a small area in the now dry upper lake bed, is partially water soluble; however, its rate of movement through the soil is slow enough so that radioactive decay reduces the concentration of that reaching surface streams to insignificant levels. Most of the 13'Cs occupies highly selective exchange sites on the illitic fraction of the clay in the sediment and can be desorbed only by disruption of the lattice structure. Only a small fraction of the 6oCo in the soil was found to be exchangeable. I t is, therefore, unlikely that any large fraction of the 137Cs or GOCo would move from the area except through erosion of the sediment. About one-half of the "Sr and the rare earths in the sediment appears to be exchangeable, while the other half is in the form of slightly soluble salts. Through leaching by ground water, a slow depletion of strontium from the dry part of the lake bed occurs.The accumulation of radionuclides in the sediments of White Oak Lake illustrates the effectiveness of relatively quiescent bodies of water in concentrating activity in stream beds and in retarding the downstream movement of these materials.

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The principles of response surface methodology, and in particular the method of the path of steepest ascent, have been employed in an attempt to discover those combinations of: (a) dose of Grundite clay, (b) particle size of clay, (c) excess soda ash and (d) proportion ofstoichiometric requirement for lime, which will remove the greatest amounts of Cs13' and Sr90 from ORNL process wastes.The method of steepest ascent is a relatively new statistical technique which is applicable to experimentation in which the variables are measureable on a continuous scale. As such it is particularly useful for optimizing chemical processes and in fact found its first application in the chemical industry.(l) This paper describes a successful application of the technique to the optimization of radionuclide removals by a chemical process.Laboratory experiments performed to date in accordance with these principles have led to combinations of the treatment variables which remove up to 95 per cent of the C P 7 and 96 per cent of the SrS0. The largest removal of C P 7 occurred at 600 p.p.m. clay of 200-mesh, 470 p.p.m. of excess soda ash and 1.4 times the stoichiometric amount of lime. The removal of SrgO was largest at 360 p.p.m. clay of 200-mesh, 520 p.p.m. excess soda ash and 2.5 times the stoichiometric amount of lime.