Immobilization 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.