Belgoprocess started the industrial decommissioning of the main process building of the former EUROCHEMIC reprocessing plant in 1990, after completion of a pilot project in which two buildings were emptied and decontaminated to background levels. The remaining structures were demolished and the concrete debris was disposed of as industrial waste and green field conditions restored. The Eurochemic reprocessing plant operated from 1966 to 1974 to process fuel from power reactors and research reactors. The main building is a large concrete structure, comprising a surface area of 55,000 m2, concrete volume 12,500 m3, and 1,500 Mg of metal components. The building is divided into multiple cells. About 106 individual cell structures have to be dismantled, involving the removal and decontamination of equipment from each cell, the decontamination of the cell walls, ceilings and floors, the dismantling of the ventilation system. Most of the work involves hands-on operations under protective clothing tailored to each specific task. Tool automation and automatic positioning systems are successfully applied. In view of the final demolition of the main process building, the main process building has been divided into three parts — each part is isolated from the others. In September 2008 the eastern part of the building has been demolished. The paper presents a status overview of the decommissioning and decontamination activities at the main process building of the former Eurochemic reprocessing plant on the nuclear site of Dessel in Belgium. The specific BELGOPROCESS strategy will be highlighted, in which the decommissioning activities are carried out on an industrial scale with special emphasis on cost minimisation, the use of technology on an industrial representative scale and the specific alpha contamination of equipment and building surfaces, requiring that the decommissioning work is done with adequate protective clothing. Also specific breathing and cooling air systems have been provided to allow the operators to carry out the decommissioning tasks in acceptable working conditions.
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.
Belgoprocess started the industrial decommissioning of the main process building of the former Eurochemic reprocessing plant in 1990, after completion of a pilot project. Two small storage buildings for end products from reprocessing were dismantled to verify the assumptions made in a previous paper study on decommissioning, to demonstrate and develop dismantling techniques and to train personnel. Both buildings were emptied and decontaminated to background levels. They were demolished and the remaining concrete debris was disposed of as industrial waste, and green field conditions restored. The main process building is a large rectangular construction of about 80 m long, 27 m wide and 30 m high. About 106 individual cell structures have to be dismantled, involving the removal and decontamination of equipment from each cell, the decontamination of the cell walls, ceilings and floors, the dismantling of the ventilation system. These activities are followed by a complete monitoring of all surfaces in view of the unconditional release of the remaining structures. About 1,500 Mg of metal structures, and 12,500 m3 of concrete with 55,000 m2 of concrete surfaces have to be removed and/or to be decontaminated. The paper presents a status overview of the decommissioning and decontamination activities at the former Eurochemic reprocessing plant on the nuclear site of Dessel in Belgium. The specific Belgoprocess approach will be highlighted, in which the decommissioning activities are carried out on an industrial scale with special emphasis on cost minimisation, the use of technology on an industrial representative scale. The specific alpha contamination of equipment and building surfaces require that the decommissioning work is done with adequate protective clothing. Adapted breathing and cooling air systems have been provided to enable the operators to carry out the decommissioning tasks in acceptable working conditions.
Belgoprocess started the industrial decommissioning of the main process building of the former Eurochemic reprocessing plant in 1990, after completion of a pilot project. Two small storage buildings for final products from reprocessing were dismantled to verify the assumptions made in a previous paper study on decommissioning, to demonstrate and develop dismantling techniques and to train personnel. Both buildings were emptied and decontaminated to background levels. They were demolished and the remaining concrete debris was disposed of as industrial waste and green field conditions restored. Currently, the decommissioning operations carried out at the main building have made substantial progress. They are executed on an industrial scale and will continue till the end of 2005. In view of the final demolition of the building, a clearance methodology has to be proposed. Application of the methodology applied for the storage buildings of the pilot project is complicated for several reasons. Although this methodology is not rejected as such, an alternative has been studied thoroughly. It considers at least one complete measurement of all concrete structures and the removal of all detected residual radioactivity. This monitoring sequence is followed by a controlled demolition of the concrete structures and crushing of the resulting concrete parts to smaller particles. During the crashing operations, metal parts are separated from the concrete and representative concrete samples are taken. The frequency of sampling meets the prevailing standards. In a further step, the concrete samples are milled, homogenised, and a smaller fraction is sent to the laboratory for analyses. The paper describes the developed concrete crushing and sampling methodology.
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