UNDERSTANDING AGING IN THE 9975 SHIPPING PACKAGE

Unlike other facilities across the Department of Energy (DOE) Complex, the Savannah River Site (SRS) K-Area Complex (KAC) stores nuclear materials inside a 9975 shipping package because of the robust nature of the package to survive facility accidents and fire events. The 9975 is credited for containment, criticality prevention, impact resistance and thermal resistance. A thorough surveillance program has been in place for more than a decade to monitor the material performance and degradation in order establish a basis for the service life and the need for repackaging 9975 shipping packages in KAC. The surveillance approach is a combination of NDE/DE field surveillance as well as laboratory testing and aging studies. The field surveillance NDE techniques include (e.g. visual inspections, leak checks, dimensional measurements as well as weight and thermal measurements). A limited number of 9975s also undergo a more in-depth examination and destructive testing of some components to provide additional assurance that adequate material properties are maintained. The laboratory testing examines the 9975 material components (e.g. O-rings and fiberboard) at the bounding storage conditions and monitor material properties and functional performance over time. The lab tests are designed to accelerate material aging to monitor and trend properties in order to lead the actual field conditions. After almost fifteen years of storage, a number of items have started to show evidence of degradation. The most significant item to experience a performance change is the fiberboard which is changing not only due to aging but also because of the thermal load inside the package. This report serves to document and understand the as found conditions of the fiberboard and other elements of the 9975 shipping package used for long term storage of nuclear materials. Since many of the components of the 9975 are used in other types of shipping packages as well, the understanding of the aging properties can be applied to other types of packages.