Optimization of Lanthanide Borosilicate Frit Compositions for the Immobilization of Actinides Using a Plackett-Burman/Simplex Algorithm Design

Abstract

ABSTRACTImmobilization by vitrification is one potential disposition option for a portion of the United States' excess plutonium inventory. Research has been performed at the Savannah River Site (SRS) to determine the optimum composition of a lanthanide borosilicate frit for the vitrification of plutonium using a Plackett-Burman design and simplex algorithm as a statistical tool. This technique uses various response variables to rank and optimize a composition. The variables used in this study correspond to homogeneity, durability, actinide solubility and devitrification after heat-treatment.The optimized frit composition was determined using a constant ThO2 loading of 20 wt%. No noticeable trends were followed with respect to the individual components which may indicate a relatively robust system able to accommodate variations in the feed.Batches containing various loadings of ThO2 were melted to determine if actinide solubility was improved in the optimized composition compared to that of a similar lanthanide borosilicate glass. No noticeable improvement in ThO2 solubility was realized as a result of using this optimization technique.