CASTOR HAW28M – Fabrication and Cold Trials of a Cask for Transport and Storage of Vitrified High Active Waste Containers

From 1997 to 2006 GNS had returned vitrified high active waste (HAW) from reprocessing in France to Germany by using the GNS cask CASTOR® HAW 20/28 CG. The cask has a capacity of 28 canisters with a maximum total thermal power of 45 kW. 74 casks of this type were loaded at the reprocessing plant in La Hague, France and have been shipped to the storage facility in Gorleben (TBL-G). The remaining HAW canisters at La Hague site exceed the technical limits of the CASTOR® HAW 20/28 CG cask concerning heat capacity and radioactive inventory. Therefore GNS developed a new cask generation, named CASTOR® HAW28M, which ensures the further return of the HAW to Germany. Hence it is possible to load 28 HAW canisters with a maximum total thermal power of 56 kW. Already in the spring of 2003, the application for approval of the Type B package design containing fissile material was submitted to the competent authority. In September 2009 the design approval certificate was issued by the Federal Office for Radiation Protection (BfS). Accompanying the licensing procedure the manufacturing/assembly of prototypic components was investigated and the fabrication of 21 packages had been initiated. In 2007 one brand-new, empty CASTOR® HAW28M cask was shipped from the GNS cask assembly facility in Mülheim to the TBL-G for cold trials. With this cask, GNS had demonstrated the transhipment of casks at the Dannenberg transfer station from rail to road, transport to and reception at the TBL-G as well as incoming dose rate and contamination measurements and preparation for storage. Another cask was shipped to La Hague in 2008 to demonstrate all handling operations during transhipment and loading at that site also. During the cold trials all important handling steps which have to be carried out at the cask loading plant and at the reception area of an interim storage facility in Gorleben were performed, witnessed by the licensing authorities and their independent experts. The paper gives an overview on the manufacturing process, the status of fabrication and the cold trials performed.