The use of SCC for the containment of high level radioactive waste

Abstract

Worldwide 10000 m(3) of highly active radioactive waste is being produced each year originating from the most diverse sources. The storage issues arising from this considerable amount is being discussed from country to country. The Belgian concept is founded on the use of cylindrical concrete supercontainers deeply stored inside the geological Boom Clay. This concept is based on a multiple barrier system where every component has its own specific safety function requirements. A self-compacting concrete (SCC) is being considered for the choice of the cementitious buffer, enclosing the radwaste. The use of SCC will ease considerably the precast process and complies with all other requirements regarding strength, durability, chemical interactions,... . A laboratory characterization program, in order to obtain the mechanical and thermal properties of the SCC has been finalised and the data are used to simulate the behaviour of the concrete buffer by using a 2.5D thermal and crack modelling program during the different manufacturing steps of the supercontainer: 1. Fabrication of the concrete, 2. Emplacement of the heat-emitting waste canisters, 3. Filling the remaining annular gap, 4. Closing the lid. Through-going cracks in the concrete buffer, which will considerably ease the transport mechanisms inside the supercontainer, are not expected