Optimization of Radionuclide Removal from Low-level Process Wastes by the Use of Response Surface Methods

Abstract

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.