Spent nuclear fuel storage vessel

A storage vessel is constituted with concretes incorporated with aggregates. Containing tubes for containing spent nuclear fuels are arranged in a zigzag manner in the inside of a chamber. A heat radiation shielding plate having heat releasing fins is disposed so as to form air channels for circulating cooling air between the plate and an adjacent chamber inner wall. Cooling air flows from air introducing port to the inside of the chamber and takes heat from the containing tubes incorporated with heat generating spent nuclear fuels and rising its temperature and cools the containing tubes by elevating air stream due to the temperature elevation and the flows directing from the air introduction port to an air exhaustion port. Radiation heat generated from containing tubes disposed to the back of the air exhaustion side is not irradiated directly to the inside of the chamber but shielded by the shielding plate. The radiation heat is transferred efficiently especially to cooling air at relatively low temperature at the lower portion. (I.N.)