Abrasive Blasting, a Technique for the Industrial Decontamination of Metal Components From Decommissioning to Unconditional Release Levels

Abstract

When decommissioning nuclear installations, large quantities of metal components are produced as well as significant amounts of other radioactive materials, which mostly show low surface contamination. Having been used or having been brought for a while in a controlled area marks them as ‘suspected material’. In view of the very high costs for radioactive waste processing and disposal, alternatives have been considered, and much effort has gone to recycling through decontamination, melting and unconditional release of metals. In a broader context, recycling of materials can considered to be a first order ecological priority in order to limit the quantities of radioactive wastes for final disposal and to reduce the technical and economic problems involved with the management of radioactive wastes. It will help as well to make economic use of primary material and to conserve natural resources of basic material for future generations. In a demonstration programme, Belgoprocess has shown that it is economically interesting to decontaminate metal components to unconditional release levels using dry abrasive blasting techniques, the unit cost for decontamination being only 30% of the global cost for radioactive waste treatment, conditioning, storage and disposal. As a result, an industrial dry abrasive blasting unit was installed in the Belgoprocess central decontamination infrastructure. At the end of May 2001, after 6 years of operation, 523 Mg of contaminated metal has been treated. 182 Mg of this material was unconditionally released, having been monitored twice by the in-house health physics department. About 303 Mg of the metal, presenting surfaces that could not be measured due to their shape, were melted for unconditional release in a controlled melting facility. The suitability of the abrasive blasting system was verified, and it was proved that there was no intrusion of contamination into the material surface. The paper gives an overview of the experience relating to the decontamination of metal material by abrasive blasting at the decommissioning of the Eurochemic reprocessing plant in Dessel, Belgium.

Radioactive Wastes

“…A processing method of solid radioactive wastes was reported (Hirose et al, 2002), suited for use in processing the radioactively contaminated apparatus such as a channel box, having highly contaminated parts and less contaminated parts, and separating/classifying the contaminated parts according to the estimated radiation level for the appropriate disposal processes. The invention by Mitsukura et al (2002) (Walthery et al, 2002). In this demonstration program, Belgo process showed that it was economically interesting to decontaminate metal components to unconditional release levels using dry abrasive blasting techniques, the unit cost for decontamination being only 30% of the global cost for radioactive waste treatment, conditioning, storage and disposal.…”