EXAMPLE FOR THE APPLICATION OF IAES TECDOC CRITERIA FOR THE BRITTLE-FRACTURE SAFE DESIGN OF A DUCTILE IRON SHIPPING PACKAGE

A proposed new IAEA regulation describes a procedure for proving a con tainer to be safe against brittle fracture. A very important aspect is the definition of a reference flaw. In non-destructive testing (in th is case 100% volumetric US testing) the probability of non-detection o f any flaw must be on the order of 1 in 100. In combination with stati stics the reference flaw depth will be about 5 times the minimum detec table flaw size. Additional requirements concern the sizes of rejectio n flaws and critical flaws. Once the reference flaw has been establish ed, it must be shown that even for its most critical location and orie ntation, the applied stress intensity is smaller than the fracture tou ghness divided by a safety factor. The most critical location was foun d to be a subsurface flaw close to the surface. The relevant loading f or the MOSAIK 80T (an 80 ton heavy-section ductile iron shipping vesse l) investigated in this paper is the deceleration of 120g resulting fr om a 9 m side drop into an unyielding target. It was found that this c ontainer is indeed safe against brittle fracture.