Concept of stress limitation for CASTOR® casks made of ductile cast iron

Since 1979 experience is gained with the design, licensing, fabrication and application of transport- and storage casks made of ductile cast iron. Up to now a total of about 750 so called CASTOR® casks were produced and loaded with high level radioactive waste world-wide. During this time period a broad basis of theoretical and experimental knowledge for different design areas were generated. Especially the mechanical properties of all fabricated casks were extensively tested according the manufacturing specification. With the large number of fabricated casks a worthful statistical data base were formed and reflects the high quality and level of the ductile cast iron, which is used for the thick walled monolithic cask body of the CASTOR® casks. It has been shown, that the ductility of the material were continuously improved and reaches a mean value of approximately 15 % elongation at this time. This guarantees a high degree of safety for the mechanical design of the cask under accidental design conditions.