Dismantling and disposal of concrete and graphite structures in nuclear facilities

The complete disassembly and demolition of nuclear facilities in Germany will give rise to an aggregate approx. 4.2 million tons of concrete and building rubbish over the next few decades. Roughly 1% of this volume will have to be disposed of as radioactive waste because of its activity and contamination, respectively, per unit mass. This means approx. 40,000 m3 of waste package volume for final storage. The disassembly and dismantling of concrete structures have been studied extensively and, to some extent, have also been tried on a technical scale. Suitable decontamination techniques can greatly reduce the arisings of radioactive waste. The following disassembly of the concrete is possible, in principle, by thermal, mechanical, and mechanical-hydraulic means. As is described in the article, water torch cutting, hydraulic crushers, drills, rock chisels, and saws as well as milling tools are used for this purpose. In the course of the demolition of research and prototype reactors it is also necessary to dispose of ceramic materials, such as graphite and carbon blocks, among other things. In Germany, the aggregate volume of these materials is approx. 900 Mg in the AVR, THTR-300 and research reactor plants. The components concerned mostly exist as blocks and single masses of up to one ton and with different activity levels. Disassembly techniques adapted to the mechanical conditions and activities encountered are available. In some cases, internals must be disassembled remotely. The waste management concepts to be applied are discussed. (orig.)