Spent fuel containing method and spent fuel container

A metal container is made, for example, of a stainless steel, and formed larger than a spent fuel assembly. Appropriate number of vibration stoppers are disposed integrally on the inner surface of the container main body. Appropriate number of spent fuel assemblies are loaded to the container. A thermal conductive granular material is filled in a space between the inner surface of the container main body and the spent fuel assemblies and a space between adjacent spent fuel assemblies. The thermal conductive granular material comprises an alumina granule. After heat of radioactive elements contained in the spent fuel assemblies is transferred to the side wall of the container main body by thermal conduction by way of the thermal conductive granular material. In addition, radiation rays emitted from the spent fuel assemblies are decayed by passing through the thermal conductive granular material. With such a constitution, heat dissipating property of the spent fuel assemblies is improved to suppress temperature elevation. (I.N.)