PERFORMANCE OF NDA TECHNIQUES ON A VITRIFIED WASTE FORM

Year
1997
Author(s)
J.R Hurd - Los Alamos National Laboratory
J.R Hurd - Los Alamos National Laboratory
David J. Mercer - Los Alamos National Laboratory
David J. Mercer - Los Alamos National Laboratory
G.W. Veazey - Los Alamos National Laboratory
G.W. Veazey - Los Alamos National Laboratory
T.E. Ricketts - Los Alamos National Laboratory
T.E. Ricketts - Los Alamos National Laboratory
R.K. Nakaoka - Los Alamos National Laboratory
R.K. Nakaoka - Los Alamos National Laboratory
Abstract
Rocky Flats Environmental Technology Site (RFETS) is currently considering the use of vitrified transuranic (TRU)-waste forms for the final disposition of several waste materials. To date, however, little non-destructive assay (NDA) data have been acquired in the general NDA community to assist in this endeavor. This paper describes the efforts to determine constraints and operating parameters for using NDA instrumentation on vitrified waste. The present study was conducted on a sample composed of a plutonium-contaminated ash, similar to that found in the RFETS inventory, and a borosilicate-based glass. The vitrified waste item was fabricated at Los Alamos National Laboratory (LANL) using methods and equipment similar to those being proposed by RFETS to treat their ash material. The focus of this study centered on the segmented gamma scanner (SGS) with 1/2-inch collimation, a technique that is presently available at RFETS. The accuracy and precision of SGS technology was evaluated, with particular attention to bias issues involving matrix geometry, homogeneity, and attenuation. Tomographic gamma scanning was utilized in the determination of the waste form homogeneity. A thermal neutron technique was also investigated and comparisons made with the gamma results.