Spent nuclear fuel cask with dose attenuation devices

A storage apparatus with gamma radiation shielding for spent nuclear fuel comprising:

• a canister comprising a baseplate and an elongated shell defining an internal cavity;
• a fuel basket disposed in the internal cavity, the fuel basket comprising a plurality of metal fuel storage tubes extending upwards from the baseplate along a longitudinal axis and each defining a fuel storage cell;
• a gamma radiation attenuation insert nested inside a first cell of a first tube of the fuel basket;
• the radiation attenuation insert comprising a longitudinally elongated cuboid body including open top and bottom ends, and a plurality of sidewalls extending between the ends;
• an upper securement feature of the radiation attenuation insert engaging a top end of the first tube;
• and
• an elastically deformable lower securement feature on the radiation attenuation insert engaging a bottom end portion of the first tube and configured to detachably affix the radiation attenuation insert to the first tube;
• wherein the radiation attenuation insert is composed of a dense material operable to block gamma radiation.

A method for adding gamma radiation shielding to a fuel basket for storing spent nuclear fuel:

• providing a fuel basket comprising a plurality of longitudinally elongated fuel storage tubes including peripheral outboard tubes arranged perimetrically around the fuel basket and inboard tubes, each of the tubes defining a cell configured to hold a nuclear fuel assembly;
• positioning a radiation attenuation insert over a selected outboard tube, the radiation attenuation insert including a plurality of elastically deformable locking members each movable laterally between an outward undeflected position and an inward deflected position;
• the locking members being in the undeflected position;
• lowering the radiation attenuation insert into the selected outboard tube;
• engaging the locking members with walls of the selected outboard tube, wherein the locking members are each moved to the deflected position;
• sliding the radiation attenuation downwards insert along the walls of the selected outboard tube;
• disengaging the locking members from the walls of the selected outboard tube near a bottom portion of the selected outboard tube, wherein the locking members each return to the undeflected position;
• and
• lockingly engaging each locking member with a corresponding locking edge formed on the bottom portion of the selected tube which resists axial withdrawal of the radiation attenuation insert from the selected outboard tube.