Thermal Study on Neutron Shields used for Spent Fuel Transport/Storage Packagings

Abstract

The study of highly effective neutron shields for packaging, which maintain integrity under severe thermal conditions, such as extended use under high temperatures or hypothetical fire conditions, is described. Such neutron shields are of the following four types. (i) Silicone rubber type—a good heat resistant type; because of its good fluidity, it can be poured into complex cases. (ii) Polypropylene type—the lightest type with a higher atomic number density of hydrogen. (iii) Ethylenepropylene rubber type—an intermediate type between the above two types in shielding ability and heat resistance. (iv) Titanium hydride type—the most hydrogenous type. The shielding ability of the above four neutron shields is evaluated. In addition, an extended heat resistance test was carried out, and the maximum allowable temperatures of these shields is evaluated. In conclusion, the neutron shields presented here are appropriate for transport/storage packaging for high burnup fuels.