Heat dissipating structure of vitrified material

A vitrified material is formed by mixing glass with highly radioactive wastes such as fission products separated by reprocessing of spent nuclear fuels, and filled/sealed in a vessel called a canister. The canister is made of a stainless steel alloy, at the center of which a heat dissipating structure is erected while being connected heat conductively to the bottom plate. The heat dissipating structure has a heat dissipating fin as a heat dissipating portion at the top end of a rod-like heat conductive axial member having a predetermined cross section and is made of a heat conductive material. The heat dissipating structure is secured, at the lower end, to the bottom plate of the canister, and the heat dissipating fin formed at the upper end is protruded upwardly from the surface of the solidified glass. The heat dissipating fin comprises a plurality of radially arranged plate-like unit fins having a predetermined width radially arranged with the direction of the width being in the vertical direction. (I.N.)