Type 8 Plutonium Transport Package Development That Uses Metallic Filaments and Composite Materials*

A new design concept for a Type B transport packaging for transporting plutonium and uranium has been developed by the Transportation Systems Department at Sandia National Laboratories (SNL). The new design came about following a review of current packagings, projected future transportation needs, and current and future regulatory requirements. United States packaging regulations specified in Title 49, Ccxle of Federal Regulations Parts 173.416 and 173.417 (for fissile materials) offer parallel paths under the heading of authorized Type B packages for the transport of greater than A 1 or A2 quantities of radioactive material. These pathways are for certified Type B packagings and specification packagings. Consequently, a review was made of both type Band specification packages. A request for comment has been issued by the U.S. Nuclear Regulatory Commission (NRC) for proposed changes to Title 10, Ccxle of Federal Regulations Part 71. These regulations may therefore change in the near future. The principle proposed regulation change that would affect this type of package is the addition of a dynamic crush requirement for certain packagings. The U.S. Department of Transportation (DOT) may also re-evaluate the specifications in 49 CFR that authorize the fabrication and use of specification packagings. Therefore, packaging options were considered that will meet expected new regulations and provide shipment capability for the U.S. Department of Energy well into the future. The possible lack of available packagings caused SNL to undertake a preliminary development program for a new Type B packaging that could meet present and future regulatory requirements. As a result of this program SNL developed a new design for a package that could transport similar quantities of plutonium and uranium that are currently carried in the DOT-6M packagings. The new package design uses nested cylindrical containment vessels (double containment) with threaded closures and elastomeric seals. A composite overpack of metallic wire mesh and ceramic or quartz cloth insulation materials is provided for structural and thermal protection of the containment vessels in an accident environment.   Two prototype packages were fabricated and subjected to dynamic crush (500 kg steel plate dropped 9 meters onto the package) environments. Subsequent evaluation indicated no deformation in the seal areas of the containment vessels that would jeopardize containment of the material. Wall sections were fabricated to obtain empirical thermal physical data for the composite wall for pre- and post-accident conditions. Finally, a thermal computer model was developed and benchmarked by test results to predict package behavior during a fire environment. Numerous tests were performed on material samples to obtain structural data for the wire mesh and composite materials and a structural model developed to capture the performance of an air transport package subjected to a high speed impact (Neilsen and Pierce 1992). Data from that work demonstrated that the material performed isotropically in a global fashion.