A NEW CONCRETE SHIELDING MATERIAL FOR WASTE MANAGEMENT

摘要

For the transportation and storage of low active waste concrete containers are used worldwide. In almost all cases thewaste in the container is enclosed by mortar or concrete. The walls of the concrete container must have a certain density forshielding reasons. The density of the container material has to be adapted to the degree of activity of the waste.In earlier applications the density of the concrete was increased by adding hematite. The new concept is based on anexact mixture of concrete and iron granules to guarantee a certain density. Densities of up to 4 kg/dm3 are possible. This highfigure cannot be achieved with hematite. This achievement is a further result of the Siempelkamp recycling philosophy.Siempelkamp has developed and now operates a melting facility, the CARLA plant, for the recycling of low activescrap from nuclear installations. During the melting process the majority of the radioactive nuclides are transferred to the slagand to the filter dust. The recycled material is then used for applications in the nuclear field. One of these applications is theproduction of iron granules by a technology developed and applied by Siempelkamp.These iron granules are added to normal concrete, resulting in a high density shielding material. With this high densityconcrete several types of waste containers (cylindrical and rectangular shapes) are fabricated.To obtain a license for the production, transportation and final storage of these containers a lot of tests had to beperformed. These included for example: stacking tests, spreader tests and drop tests. All tests were performed successfully.Siempelkamp has the license to produce these containers made of a new concrete mixture with iron granules. In addition,other shielding structures like plates can be manufactured from granulate concrete as well.The distribution of the iron granules over the whole volume is homogeneous even after filling the concrete mixture intothe mould. This homogeneity is achieved and guaranteed by the production procedure and has been verified on severalcontainers by means of radiography inspections.The advantage of this technology lies in the recycling of metal waste into iron granules for the production of concretewaste containers, thus also reducing the amount of waste in the final repository. With the final repository being the mostexpensive method of storing this is a clear economic advantage. Also, by being independent of the still undecided finalrepository in Germany this is also of political advantage.