GNS CASTOR® V Dual Purpose Casks: The Backbone for Spent Fuel Dry Interim Storage in Germany

The present concept for spent fuel management in Germany is dry interim storage and subsequent final disposal. For the case of spent fuel assemblies from commercial nuclear power plants in Germany CASTOR® V dual purpose casks essentially constitute the backbone for dry interim storage. GNS has developed two types of CASTOR® V casks – CASTOR® V/19 and CASTOR® V/52 – licensed for both transport and interim storage of 19 PWR and 52 BWR spent fuel assemblies, respectively. Since March 1997, when the first CASTOR® V/19 cask containing 19 PWR fuel assemblies was stored at the interim storage facility in Gorleben, more than 300 CASTOR® V have been loaded and put in storage. To meet the customer as well as licensing requirements across these years, the initial cask design from the 1990s was continuously enhanced and optimized. Accordingly, the cask inventory parameters evolved from a heat load of 25 kW and initial enrichment of up to 4.05 wt-% U235 to a heat load of 40 kW and initial enrichment of up to 4.45 wt-% U235. MOX fuel assemblies may also be transported and stored in CASTOR® V casks. Currently, the initial enrichment of the spent fuel assemblies to be transported and stored in the CASTOR® V casks is going to be increased. Moreover, periodical renewals of existing licenses as well as new applications kept cask design as well as proof of the design state-of-the-art. As a result, GNS is currently holding four type B(U)F-licenses for CASTOR® V casks. Following the significant changes in political and legal boundary conditions in Germany 2011 an accelerated phase-out of nuclear power is demanded. This leads to new boundary conditions for the German electric power utilities and subsequently for the further CASTOR® V casks development. One challenge amongst others is to quickly remove spent fuel from shut-down plants. In order to achieve this, the cask inventory parameters are going to be extended and quivers to accommodate nonstandard fuel rods will also be developed and stored in CASTOR® V casks. Finally, cask manufacturing capacities are to be increased. The presentation will give an overview of the specific capabilities of the CASTOR® V as dual purpose casks and an outlook to future developments.