Cask Size and Weight Reduction Through the Use of Depleted Uranium Dioxide (DUO2)–Steel Cermet Material

摘要

Newly developed depleted uranium (DU) composite materials enable fabrication of spent nuclear fuel (SNF) transport and storage casks that are smaller and lighter in weight than casks made with conventional materials. One such material is DU dioxide (DUO2)–steel cermet. This work examines the radiation shielding efficiency of this new cermet material as compared with conventional steel used in Holtec International’s HI-STAR 100 cask system. In this analysis, the steel layers of the HI-STAR 100 cask are replaced with a layer of cermet material. The thickness of the cermet shielding is adjusted to give the same radiation doses as the HI-STAR 100 cask. When gamma radiation dose alone is considered, the best-case outside radius (70% DUO2 in steel) is reduced from 121 to 113 cm and the weight is reduced from 77 to 61 tons. When 1% B4C neutron absorber is added to the nominal case (49% DUO2 in steel), the cask outside radius is reduced from 121 to 108 cm and the cask weight is reduced from 77 to 72 tons. The radial cross-section shielding area is reduced 41%. These calculations assume a constant 85-cm radius for the multipurpose canister that contains 24 pressurized-water-reactor fuel assemblies. These reduced sizes and weights will significantly influence the design of next-generation SNF casks.