Development of Spheroidized Graphite Cast Iron Material for Spent Fuel Transport and Storage Cask and Investigation of its Mechanical Properties

The DCI to be used in manufacturing spent fuel transport and storage casks will be extremely thick (500mm). As a part of the study program for evaluating economic feasibility as well as for establishing standards for DCI casks, the manufacturing of large-model casks and collection of data were started by each material manufacturer (a round robin test). It is well known that, as thickness increases, the graphite structure in spheroidized graphite cast iron is deformed, and graphite chunks are more likely to be produced. There exists, therefore, the necessity to elucidate what factors control these characteristics. For this study, we manufactured a 40ton (large and thick) casting to simulate an actual-size cask. After performing nondestructive examination, we cut the casting into sections. We conducted various mechanical tests at the center of the wall thickness of these sections to investigate DCI's material properties.