Properties of nodular ductile graphite cast iron used in GNS-manufactured spent fuel casks

GNS manufactured nodular cast iron has sufficient fracture toughness to ensure the structural integrity of spent fuel shipping casks even under accident conditions. The fracture toughness appears to be only slightly loading rate sensitive. There is no significant anisotropy in this material. The material can be produced in thick sections when only a slight through-thickness property gradient. Critical flaw sizes associated with stress levels which may be encountered in a nine-meter drop-test of a shipping container are well above the detectibility of conventional NDE. GNS has had considerable experience in the production of approximately twenth large casks since the material described in this test program was produced. This has lead to the improvement of production control procedures. A substantial safety margin exists in the properties of currently produced nodular cast iron in comparison to the values of material from the full-scale prototype cask drop-tested. 5 references, 5 figures