A spacer grid includes interlocked straps comprising metal sheets or plates welded together to define a spacer grid having a top and bottom. The interlocked straps define a plurality of cells comprising vertical passages connecting the top and bottom of the spacer grid. The cells include: upper dimples proximate to the top of the spacer grid and distal from the mid-plane of the spacer grid; lower dimples proximate to the bottom of the spacer grid and distal from the mid-plane of the spacer grid; cantilevered upper springs having fuel rod engagement surfaces proximate to the top of the spacer grid and distal from the mid-plane of the spacer grid; and cantilevered lower springs having fuel rod engagement surfaces proximate to the bottom of the spacer grid and distal from the mid-plane of the spacer grid.

A nuclear fuel assembly grid that includes two zones, a protected zone and a crumbled zone. The crumbled zone occupies the periphery of the grid and is designed to experience plastic deformation under high impact loads and the protected zone occupies the interior of the grid where the control rod guide thimbles are located and protects all of the control rod guide thimble locations by experiencing only plastic deformation under such loads.

A nuclear fuel assembly grid having a torpedo-shaped mixing vane assembly supported at each intersection of the grid straps that surrounds a fuel rod support location. The torpedo-shaped stem supports mixing vanes that extend over each of the fuel rod support locations.

A nuclear fuel assembly grid having a torpedo-shaped mixing vane assembly supported at each intersection of the grid straps that surrounds a fuel rod support location. The torpedo-shaped stem supports mixing vanes that extend over each of the fuel rod support locations.

A nuclear fuel assembly comprises nuclear fuel rods (4) extending along a longitudinal axis (L) and a support skeleton (6) configured to support the nuclear fuel rods (4). The support skeleton (6) includes two end pieces (8, 10), a plurality of guide tubes (12) connecting the end pieces (8, 10) to each other, and spacer grids (14) attached to the guide tubes (12), with each spacer grid (14) supporting the nuclear fuel rods (4). The nuclear fuel assembly further includes at least one reinforcement device (20) comprising at least one reinforcement plate (22) which is in contact with at least two of the guide tubes (12) and attached to one or more of the guide tubes (12) at attachment points (21). Each reinforcement plate (22) has at least two attachment points (21) that are offset relative to each other along the longitudinal axis (L).

A nuclear fuel assembly comprises nuclear fuel rods (4) extending along a longitudinal axis (L) and a support skeleton (6) configured to support the nuclear fuel rods (4). The support skeleton (6) includes two end pieces (8, 10), a plurality of guide tubes (12) connecting the end pieces (8, 10) to each other, and spacer grids (14) attached to the guide tubes (12), with each spacer grid (14) supporting the nuclear fuel rods (4). The nuclear fuel assembly further includes at least one reinforcement device (20) comprising at least one reinforcement plate (22) which is in contact with at least two of the guide tubes (12) and attached to one or more of the guide tubes (12) at attachment points (21). Each reinforcement plate (22) has at least two attachment points (21) that are offset relative to each other along the longitudinal axis (L).