Development of high performance transportable storage cask For interim storage

Mitsubishi Heavy Industries, Ltd. (MHI) ha s established transportable storage cask design \"MSF series\". Overall external view of the MSF transport and storage cask is illustrated in Fig. 1. MSF series cask employs new-developed design and materials, and realizes the increase of accommodation of fuel assemblies and the improvement of reliability. The following key technologies are applied to the MSF series. - Main body A main body of the MSF cask consists of seamless vessel. It is effective for improving ability to eliminate a weld seam between cylindrical parts and base plate part of the main body. Therefore unique forging method has been developed and employed for manufacturing main body. A shape of main body is polygonal configuration because this shape provides close contact between external surface of the basket cell and internal surface of the body, and heat dissipation performance is greatly improved by enabling to enlarge heat transfer area. - Basket MSF series cask uses a simplified basket cell that consists of individually not jointed square pipes made of boronated aluminum applied by powder metallurgy. This basket cell has good heat dispersion property and powder metallurgy provides higher boron content in boronated aluminum. - Neutron shielding material MSF series cask uses the new-developed neutron shielding material. As our investigation, purity of refractory material, which shielding material consists of, influences durability of shielding material. Therefore the purity has been improved.