Long-term Aging and Surveillance of 9975 Package Components

The mission of the 9975 package, originally designed only fortransportation of radioactive materials, has been broadened to includestorage at the Savannah River Site. Two components of thispackage, namely the containment vessel O-rings and fiberboardoverpack, require continued integrity assessment under the storageconditions. The performance of the components over timeis being evaluated using accelerated-aging studies. Compressionstress relaxation (CSR) and leak testing are being used to measurethe performance of O-rings. The performance of the fiberboard isbeing evaluated using compression strength, thermal conductivity,specific heat capacity, and other physical properties. Modelsdeveloped from the data collected provide an initial prediction ofservice life for the two components, and support the conclusionthat normal service conditions will not degrade the performanceof the package beyond specified functional requirements for thefirst assessment interval. Increased confidence in this conclusionis derived from field surveillance data and destructive evaluationof packages removed from storage.