Static Stress Analysis on the Large Capacity Thin-Wall UF6 Storage Cylinder Intended To Be Used in Transport*

Large diameter ( 48-inch) cylinders are used for the storage and transport of depleted uranium hexafluoride (DUF6). This DUF6 is the residual material from uranium enrichment operations from the three gaseous diffusion plants in the United States. Gaseous diffusion operations since the mid 1940s have produced an inventory of approximately 50,000 of these cylinders with nominal content of 14 tons DUF 6. The large diameter cylinders were originally designed and fabricated for temporary storage ofDUF6. The cylinders were fabricated from pressure vessel grade steels according to the provisions of the ASME Boiler and Pressure Vessel Codes (Section VIII, Div. 1, 1992). These cylinders were constructed in thick wall (5/8-inch wall thickness) and thin-wall (5/16-inch wall thickness) versions. These cylinders are currently stored in outdoor arrays in a two tier assembly with the contacts being shell to stiffener rings. The lower tier cylinders are supported by chocks. The cylinders are subjected to general and accelerated atmospheric corrosion and to possible damage from stacking and other handling operations. Finite element stress analysis and fracture mechanics methodology have been utilized to assess cylinder structural integrity during handling operations and degradation of the cylinder shell resulting from corrosion or other damage mechanisms.