Patent ID: 8462910

Claim:
A neutron shield comprising: a plurality of containers each of which contains a powdered neutron absorbing material and which are stacked with one another in a vertical direction; a cladding tube which houses the containers and which is arranged outside a nuclear reactor core; an upper chamber which is provided at an upper portion of an interior of the cladding tube and into which gas leaked outward from the containers and caused by a neutron absorbing reaction of the powdered neutron absorbing material configured to absorb neutrons leaking from the nuclear reactor core is guided; and a support mechanism disposed in the upper chamber and configured to support the respective containers by pressing an uppermost container in the stacked containers in the stacking direction so as to permit deformation caused by thermal expansion or swelling, wherein a clearance is formed between the containers and the cladding tube in a state in which the containers are housed in the cladding tube.