Development of plasma based decontamination of large metallic objects

The US Department of Energy complex has a significant legacy of equipment which has been used in the production of the nations nuclear weapons stockpile, and is consequently contaminated with Transuranic (TRU) material. Present methods for decontamination and disposal of these items typically involve surface scrubbing followed by size reduction, and packaging for ultimate disposal in a facility such as the Waste Isolation Pilot Plant (WIPP). The present decontamination methods are often crude--involving significant possibility for exposure of personnel to radiation, and frequently generating large quantities of contaminated liquid waste, which must be processed before re-use or disposal. A dry decontamination process using Reactive Ion Etching (RIE) with a fluorine and oxygen based plasma is being developed at Los Alamos National Laboratory as an improved method for removal of TRU material from the surface or near-surface of large metallic objects. Technical issues which remain to be addressed in the development of this process include evaluation of potential cross- and residual contamination, the ability to access hold-up areas such as varying sizes of cracks and crevices in the object being decontaminated, the impact of non-conducting portions of the target, and the efficiency of contaminant control and capture in simple down-stream filters. Details and results of RIE tests using surrogate materials in various geometries will be presented