Patent GB-1374099-A (GB)
Title: Packaging for shipment of radioactive materials
IPC: G21F5/012
Filed: 1971-11-17
Abstract: 1374099 Shielded containers TRANSNUCLEAIRE SOC POUR LES TRANSPORTS DE L'INDUSTRIE NUCLEAIRE 17 Nov 1971 [17 Nov 1970 2 Feb 1971] 53258/71 Heading B4Q  A container for the shipment of radioactive materials, e.g. spent nuclear fuel elements, comprises at least one inner container or capsule 1 adapted to contain the materials and also a gaseous or liquid coolant, e.g. air, argon, helium or water, a γ-ray shield 5, 6, 7, and an outer container 2 with cooling fins 3 on its lateral outer surface and containing a liquid, e.g. water, capable of ensuring both neutron shielding and heat transfer, in which the one or more capsules 1 and the γ-ray shield 5, 6, 7 are immersed, spacers 8 being provided between the outer container 2 and the γ-ray shield 5, 6, 7. Thermal insulation 4 comprising an expanded material 4a covered with a heat-proof coating 4b is provided at the extremities of the container. The lateral shield 5 and the end shields 6, 7 are each formed of a core 9 of a heavy metal such as Pb or U in a sheath 10 of stainless steel. In the embodiment shown in Fig. 1 where there is a single capsule 1, the shield 6 forms the bottom of the capsule whilst the shield 7 forms a cover and is formed with a flange 11 which may be bolted to a flange 13 on the capsule, a gasket 14 ensuring a fluid-tight joint. During shipping, the capsules 1 and the shield 5 are rigidly fixed to one another by means of bolts 13a at one end, spacers 16 being provided at the other end to enable the water in the outer container 2 to circulate by convection from one side of the shield 5 to the other. The spacers 8 are perforated to facilitate the circulation of the water. These spacers 8, which act as shock absorbers in the case of a crash, can be borne by the outer container 2 (as shown) or by the shields 5, 6, 7, or they may be in the form of a removable structure (Figs. 6 to 8, not shown). The fins 3, preferably of copper, have their ends embedded in a fire protection layer 18 of plaster or cement. The outer container 2 is equipped with valves 23 for filling and venting, also for sampling, a pressurelimiting expansion valve 24 to limit pressure in the case of a prolonged fire, and a permeable plug 25 for the elimination of H 2  formed by radiolysis. The outer container 2 can be completely filled with water, the thermal expansion of which is balanced by the compression of expanded material such as rubber or plastics foam contained in open compartments (C) (Figs. 7 and 8, not shown) between the outer container 2 and the shield 5. The container is brought from the horizontal shipping position to the vertical loading/unloading position and vice versa by means comprising tilting jacks and bearings attached to the transporting chassis and with which trunnions 19b on the container wall co-operate. Like the outer container 2, the capsule 1 comprises a filling valve 29 but with a dip tube 30 for level control, an expansion valve 31, a vent valve 32, and a permeable plug 33. Partitions inside the capsule 1 for spacing fuel elements are of a neutron prison composition to prevent the occurrence of critical conditions. Where a number of separate capsules 1 are used (Figs. 9 to 12, not shown), the neutron prison may be in the form of plates located between the capsules.