[en] General design or test performance requirements for radioactive materials (RAM) packages are specified in Title 10 of the United States (US) Code of Federal Regulations Part 71. The requirements for Type B packages provide a broad range of environments under which the system must contain the RAM without posing a threat to health or property. Seals that provide the containment system interface between the packaging body and the closure must function in both high and low temperature environments under dynamic and static conditions. A seal technology programme, jointly funded by the US Department of Energy Office of Environmental Restoration and Waste Management and the Office of Civilian Radioactive Waste Management (OCRWM), was initiated at Sandia National Laboratories. Experiments were performed in this programme to characterise the behaviour of several static seal materials at low temperatures. Helium leak tests on face seals were used to compare the materials. Materials tested include butyl, neoprene, ethylene propylene, fluorosilicone, silicone, Eypel, Kalrez, Teflon, fluorocarbon, and Teflon/silicone composites. Because most elastomer O-ring applications are for hydraulic systems, manufacturer's low temperature ratings are based on methods that simulate this use. The seal materials tested in this programme with a fixture similar to a RAM cask closure, with the exception of silicone S613-60, are not leak tight (1.0 x 10^-7 std cm³.s^-1) at manufacturer's low temperature ratings. (authors)