Overcoming design and licensing challenges -The B(U)F flask TGC27

For the return shipment of intermediate-level compacted metallic waste (CSD-C - Colis Standard de Déchets Compactés) resulting from the reprocessing of German spent fuel assemblies at the La Hague reprocessing plant, France, to Germany, the TGC27 transport and storage flask has been developed. It is a Type B(U) package design for fissile material suitable for transport and long-term interim storage of CSD-Cs. The flask is developed by the AGC consortium, a private partnership of TN International (France) and GNS Gesellschaft für Nuklear-Service mbH (Germany). The consortium has applied for approval of a Type B(U) package design for fissile material in Germany. The strategy of structural safety demonstration is based on a penalizing full-scale mock-up with a thick forged body. Specific expertise has been developed to select materials and tolerances representative of the serial flask in service conditions. For the forging of the body, a low alloy carbon steel grade with an optimized chemical composition has been used. The tensile properties at room temperature are representative of the serial flask at maximum service temperature. The bottom-to-shell welding was performed in order to have mechanical properties corresponding to the minimum properties of the serial production weld, causing maximized deformation in the punch bar tests. The shock absorbers have been produced with hard and soft properties: hard properties to maximize the stress and to be representative of the behavior at -40 °C and soft properties to control the ability of the parts for absorption of the impact energy at the maximum service temperature. For the closing system, i. e. the lids and bolts, the requirements were set with minimum mechanical properties at maximum service temperature. Dummy canisters have also been produced to represent the CSD-Cs. A total of 8 drops will be performed to demonstrate the safety robustness of the TGC27 design: one axial drop, one lateral drop, two angle drops, and four punch bar drops.