EVOLUTION OF PACKAGES FOR STORAGE, TRANSPORT AND DISPOSAL OF INTERMEDIATE LEVEL WASTE IN THE UK

The paper describes the evolution of designs of containers for the long term storage, transport and disposal of ILW in the UK destined for the UK Geological Disposal Facility (GDF). The system for higher activity wastes (Type B and certain LSA wastes) uses thin walled stainless steel drum or box shaped containers to carry the ILW that require a Type B overpack for transport. The system for lower activity levels (LSA/SCO) is based on the use of large self-shielded containers that are approved as IP-2 transport packages. To meet containment and shielding requirements under accident conditions at the GDF, the ILW within both types of containers has to be immobilised (eg by grouting); the containers alone are not sufficiently robust to meet these requirements. For the lower activity ILW (LSA) the evolution of the designs is described from 1st generation concrete boxes (WAGR boxes), through the 2nd generation stainless steel concrete lined boxes (GDF specified waste packages) to the 3rd generation DCIC containers. A key issue in the design of shielded ILW containers is that they must be suitable for storage for up to 150 years before transport and emplacement in the GDF. This presents challenges in meeting transport and disposal requirements after such periods which are discussed. The paper credits the introduction of DCIC containers to GNS, Siempelkamp and BAM in Germany where DCIC containers have been developed to meet disposal requirements in Germany: these containers have recently been introduced in the UK for Magnox ILW. DCIC containers are inherently robust and can be designed to meet GDF accident conditions without undue reliance on the form of contents. This has the potential benefit for limiting or even avoiding conditioning of waste (potentially avoiding grouting) and providing a package that can be stored in a simple store, rather than a complex shielded store. The paper indicates how the use of robust self-shielded DCIC containers for ILW has potential for use for Type B ILW and how these Type B packages can be shipped either directly as Type B packages, or within an overpack to meet transport requirements.