Two Decades of Experience with more than 750 CASTORÒ and CONSTORÒ Transport and Storage Casks

In 1983 the world-wide first dual purpose transport and storage cask - a CASTOR® Ic-DIORIT - was loaded in Würenlingen/ Switzerland. Meanwhile CASTOR® casks are used at 24 sites on four continents. Spent fuel assemblies of PWR, BWR, VVER, RBMK, FBR, MTR and THTR as well as vitrified high active waste canisters are transported and/or stored in these kinds of monolithic metal casks. MOX spent fuel of PWR and BWR has been loaded, too. Starting in the mid of the 90s, GNB developed the new CONSTORÒ cask concept, which is based on a double liner technology with a layer of heavy concrete as shielding material inbetween. This CONSTORÒ cask concept fulfils all design criteria for transport and for storage given by the IAEA recommendations and by national authorities. Up to now, more than 750 CASTORÒ and CONSTORÒ casks have been used for transports or/and loaded for longterm interim storage. More than two decades of storage experience attest to the excellent behavior of the casks including the metallic gaskets and the tightness monitoring system. Detailed measurements of temperatures and of gamma and neutron dose rates have shown in each case that the safety requirements have been fulfilled. These measurements allowed to reduce unnecessary safety margins to optimize the benefit for the user.