Status of overpacks for uranium hexafluoride transport

The original overpacks for uranium hexafluoride (UF6) transport, which utilized phenolic foam insulation, were developed in the 1960's and ultimately became international standards. A second generation of overpacks for 10-ton-capacity UF6 cylinders used polyurethane foam and was developed in the early 1970's. In the mid 1970's, a third generation was designed, but no attempt to develop it occurred until the early 1980's, when full-scale testing of an overpack for 14-ton capacity UF6 cylinders was initiated and resulted in designs for a new family of UF6 overpacks. In the meantime, two additional developments affected overpack use for UF6 cylinder transport: (1) the discovery that phenolic-foam-insulated overpacks have water absorption and outleakage problems inaugurated a program for their improvement and (2) new polyurethane-insulated overpacks were manufactured. The current status of all these overpacks, including their designs, testing, and approval for transport is presented