Residual Stresses in 3013 Containers

The U.S. Department of Energy (DOE) Complex is packagingplutonium-bearing materials for storage and eventual dispositionor disposal. The materials are handled according to the DOESTD-3013, which outlines general requirements for stabilization,packaging, and long-term storage. The storage vessels for theplutonium-bearing materials are termed 3013 containers. Stresscorrosioncracking has been identified as a potential containerdegradation mode and this work determined that the residualstresses in the containers are sufficient to support such cracking.Sections of the 3013 outer, inner, and convenience containers, inboth the as-fabricated condition and the closure welded condition,were evaluated per ASTM standard G-36. The standard requiresexposure to a boiling magnesium chloride solution, whichis an aggressive testing solution. Tests in a less aggressive 40 percentcalcium chloride solution were also conducted. These testswere used to reveal the relative stress-corrosion cracking susceptibilityof the as fabricated 3013 containers. Significant crackingwas observed in all containers in areas near welds and transitionsin the container diameter. Stress corrosion cracks developed inboth the lid and the body of gas tungsten arc welded and laserclosure welded containers. The development of stress corrosioncracks in the as-fabricated and in the closure welded containersamples demonstrates that the residual stresses in the 3013 containersare sufficient to support stress-corrosion cracking if theenvironmental conditions inside the containers do not precludethe cracking process.