DEVELOPMENT OF FORGED STEEL APPLIED TO MAIN BODY OF TYPE B(U) PACKAGE

Mitsubishi Heavy Industries, Ltd. (MHI) has developed MSF-57BG spent fuel transport and storage cask. Newly developed forged steel is applied to body shell and base plate for the cask. The cask material (called LF3-m) was developed based on ASTM A350 LF3 to improve fracture toughness and to provide high strength at elevated temperature. At 150°C LF3-m keeps mechanical strength equivalent to that of A350 Grade LF5 material at room temperature. The material test results using forging of LF3-m as a trial proved that the material is well suited to build the main body for the transport and storage cask.