Year
2010
File Attachment
Abstract
A large-scale transportation cask such as transporting spent fuels of a light water reactor has two kinds of body design alternatives; one being a mono-wall type using a large steel forging, and the other a multi-wall type using a combination of steel plates and lead as gamma shielding. Historically, the multi-wall type was used at first for the body of transportation casks, and the mono wall type followed it. Currently, it can be said that there is a tendency that the mono-wall type is mainly used in European cask designs, and the multi-wall type is used in the United States cask designs. Both types of cask designs are used in Japan. Assuming that the material of the mono-wall type body is a forged low alloy carbon steel, and that the multi-wall type body is a combination of carbon steel plate, lead and carbon steel plate, two types are compared for the instruction to the cask body type and materials for a new cask design. The merits and demerits of each body type are discussed by not only their technical requirements, such as their: (1) Structural design strength, (2) Heat removal design and (3) Shielding design, but also their fabrication and economical standpoints. In addition, the study considers the influence of transportable storage cask demand, which is much larger than that of transportation casks, to the design selection, and is expected to rise more in the near future. It also considers the influences of both nuclear renaissance and the increase of a highpressure vessels demand in chemical industries, which have cropped up a few years ago. The study concludes that the specifications of the content (spent fuels) are one of the key factors determining the cask body type required.