Assessment Of Potential Damage To Ductile Cast Iron Cask As A Result Of Exceptional Impact Loading

Safety of shipping cask for nuclear spent fuel is always a reason of concern for the designers, regulators and public opinion. Even though safety requirements are already outstanding for this kind of structure, additional worries about its vulnerability have been expressed, especially after the terrorist attack of September 11th, 2001. During the 1970s and 1980s, U.S. National Regulatory Commission (NRC) evaluated the consequences of an hypothetical terrorist attacks and in 1984, came to the conclusion that the use of explosives would not result in a serous threat and, subsequently, proposed lessened security requirements for shipments. The recent public release of a footage of a 1998 test at the Army's Aberdeen Proving Ground in Maryland, showing an anti-tank missile breaching the cast iron wall of a CASTOR cask, re-opened the discussion about the effective safety and resistance of these container to exceptional impact events. In this paper the preliminary results of a research program in progress at the University of Cassino on ductile cast iron structural integrity and impact protection evaluation are presented. The exceptional impact event of an airplane crash onto a cask has been re-analyzed by means of an extensive numerical simulation using hydrocode and developing a specific damage modeling for failure in ductile cast iron