A FRACTURE-MECHANICS SAFETY CONCEPT TO ASSESS THE IMPACT BEHAVIOR OF DUCTILE CAST-IRON CONTAINERS FOR SHIPPING AND STORAGE OR RADIOACTIVE MATERIALS

Within the scope of the German licensing procedures for shipping and s torage containers for radioactive materials made of ductile cast iron, BAM performs approval design tests including material tests to ensure the main safety goals of shielding, leaktightness and subcriticality under ''Type B accident conditions''. So far the safety assessment con cept of BAM is based essentially on the experimental proof of containe r strength by prototype testing under most damaging test conditions in connection with complete approval design tests, and has been develope d especially for cylindrical casks like CASTOR- and TN-design. In conn ection with the development of new container constructions such as ''c ubic cast containers'', and the fast developments in the area of numer ical calculation methods, there is a need for a more flexible safety c oncept especially considering fracture mechanics aspects. This paper p resents the state of work at BAM for such an extended safety concept f or ductile cast iron containers, based on a detailed brittle fracture safe design proof. The requirements on stress analysis (experimental o r numerical), material properties, material qualification, quality ass urance provisions and fracture mechanics safety assessment, including well defined and justified factors of safety, are described.