Application of Laboratory Fracture Toughness Measurements to Ensure Fracture Resistance of Transport Packages

Applying laboratory fracture toughness measurements to ensure the fracture resistance of radioactive material transport packages is critical to a fracture mechanics based design. Unfortunately, the dependence of the fracture toughness of many materials on temperature, loading rate, and specimen size complicates the application of laboratory results to the evaluation of full-scale transport package behaviour. A review of previous research related to small specimen test results and a summary of the methods which have been proposed to ensure that transport packages will not fail by brittle fracture is presented. A single specimen elevated rate fracture toughness testing technique is presented as a practical means of quantifying the fracture toughness of samples which can be taken from larger structures. This technique has been successfully applied to the testing of ductile iron (DI). A method of quantifying constraint effects will allow the results from small specimens (such as those machined from corings removed from each package during serial production) to be used directly to ensure the fracture safety of each individual full-scale unit.