Improved Technologies for Decontamination and Reuse of Plutonium Contaminated Gloveboxes

Abstract

The Los Alamos Large Scale Demonstration and Deployment Project (LSDDP), in support of the US Department of Energy (DOE) Deactivation and Decommissioning Focus Area (DDFA), has been identifying and demonstrating technologies to reduce the cost and risk of management of transuranic element contaminated large metal objects, i.e. gloveboxes. DOE must dispose of hundreds of gloveboxes from Rocky Flats Environmental Technology Site (RFETS), Los Alamos National Laboratory (LANL), and other DOE sites. This paper reports on the results of four technology demonstrations on decontamination of plutonium-contaminated gloveboxes with each technology compared to a common baseline technology, wipedown with nitric acid. The general objective of the demonstrations was decontamination to an alpha-emitting nuclide disintegration rate of less than 50,000 disintegrations per minute per 100 square centimeters (dpm/100 cm2), the surface activity level desired for re-application of these particular gloveboxes to a new mission. The technologies demonstrated include: • A LANL-developed electrochemical decontamination system (EDS) technique utilizing a recycled electrolyte solution to contact the glovebox surface via a small electrode fixture, which is moved from location to location until the entire metal surface is decontaminated. • A commercial three-step decontamination technology marketed by Environmental Alternatives Inc. (EAI) was demonstrated to quantify its performance relative to the baseline technology. • Cerium (IV) nitrate decontamination, previously utilized at other DOE sites and developed for application to gloveboxes at RFETS, was demonstrated to quantify its performance in this application. • A Russian-developed electrochemical decontamination (ECD) technology was monitored by the Los Alamos LSDDP for potential application in DOE. Although this decontamination activity was not an LSDDP “demonstration,” it was planned, monitored, and reported using LSDDP methodologies. Generally, the experience from these demonstrations shows that all innovative technologies perform better than the baseline, nitric acid wipedown. The goal of meeting 50,000 dpm/100 cm2 was not achieved by the baseline technology or cerium nitrate decontamination at all measured locations with the number of decontamination technologies used in the demonstration. Additional decontamination cycles were estimated for achievement of the targeted activity for cost estimating purposes. However, the actual decontamination achieved may be acceptable for LLW status at some facilities. Both electrochemical techniques are capable of decontaminating surfaces to the targeted contamination level and, if desired, can decontaminate to very low levels. The EAI technology is the best performing of the wipedown techniques, but is more costly. Table I summarizes the number of cycles the various technologies required to achieve the desired decontamination level and the associated decontamination factor.