Waste isolation safety assessment program. Controlled sample program publication number 2: interlaboratory comparison of batch Kd values

Abstract

Objectives were to: (1) ascertain whether different experimenters obtain the same results for the adsorption of Cs, Sr and Pu using common rocks, standard solutions and a prescribed method; and (2) compare the results obtained by individual laboratories using different experimental methodologies and resolve any differences found or determine what conversions can be made to compare results from one method with another. Results from Objective 1 indicate that several parameters that were uncontrolled may have affected results. The uncontrolled parameters were: (1) method of tracer addition to solution, (2) solution to rock ratio, (3) initial tracer concentration in influent solution, (4) particle size distribution, (5) solid--solution separation method, (6) sample containers, and (7) temperature. Observed Kds for Cs and Sr in brine showed agreement among laboratories for both limestone and basalt rock samples. Comparable results were also found for Sr and Cs in the basalt groundwater. Results for Kd(Cs) in the limestone groundwater varied over three orders of magnitude, and Kd(Sr) varied by one order of magnitude in the limestone system. Observed Kd values for Pu typically varied by two to three orders of magnitude in all systems studied. Adsorption of Pu by container walls and by colloidal particles causedmore » much of the variation in Kd(Pu). Direct measurement of Pu adsorbed by the rock (rather than measured by the difference between influent and effluent activities) also failed to reduce the Kd(Pu) variability.« less

Keywords

This publication has 0 references indexed in Scilit: