A new spring design for a strap employed in a grid of a nuclear reactor fuel assembly includes a pair of ligaments that each connect with the free portion of the retention plate. The ligaments each are equally spaced a certain distant from the termination of the slots within the strap body. The spring additionally includes a spring contact plate that is wider than the connections of the spring ligaments with the free portion to increase the surface area with which the spring contact plate is in ...

A support grid for laterally maintaining the relative position of elongated fuel elements within a fuel assembly for use within a core of a nuclear reactor. The grid is formed in the shape of a lattice with the intersecting lattice members defining a plurality of cells, most of which respectively support the nuclear fuel elements. The remaining cells support nuclear control rod guide tubes and instrumentation thimbles. The cells supporting the nuclear fuel elements are provided with diagonally p...

A side-slotted nozzle type double sheet spacer grid for nuclear fuel assemblies is disclosed. The spacer grid includes intersecting inner strips and four perimeter strips. Each inner strip has unit strip parts, each fabricated by integrating two unit sheet parts together into a single structure, such that the two unit sheet parts face each other and a nozzle type coolant channel is defined between the two unit sheet parts. Each perimeter strip is fabricated by integrating an inner thin sheet hav...

An improved grid for use in a fuel assembly of a nuclear reactor includes a plurality of straps connected in a lattice, with a plurality of mixing vanes being disposed on the straps and being arranged such that the hydraulic forces on the mixing vanes generally cancel one another out. The mixing vanes of diagonal quadrants of the grid are generally aligned with diagonally disposed imaginary alignment planes. Each strap includes a plurality of strap members, with each strap member including a spr...

The spacer for a nuclear fuel bundle includes unit cells having upper and lower, generally octagonally shaped walls connected one to the other by spring leg portions along sides thereof 90.degree. apart. The walls also carry stops in opposition to the sides of the walls to which the spring leg portions are connected. By orienting the cells in the spacer such that the majority of the cells have their stops lying toward one side of the spacer, the fuel bundle can be disposed in a horizontal positi...

A spacer for a nuclear reactor fuel assembly includes sheet metal webs which intersect one another on edge and form grid meshes. A leaf spring projects from a sheet metal web in a grid mesh and is assigned to a bearing boss for the force-locking holding of a rod in the grid mesh. The leaf spring is attached to the sheet metal web at a leaf edge extending in the longitudinal direction of the rod. In order to avoid fretting in a nuclear reactor, a perforation is formed in the leaf spring and has a...

A nuclear fuel support grid 10' of egg-crate structure has wave defining strips 12a, 12b, 12c, 12d defined by bends 16' inclined from the vertical and opposing cantilevered springs 18' with inclined spring bases 20' opposing them for support of fuel rods 22 intermediate their ends. The "inclined waves" defined by inclined surfaces formed by bends 16' and spring bases 20' of cantilevered springs 18' provide lateral components to the coolant flow in patterns which enhance DNB and corrosion behavio...

In a grid in a nuclear fuel assembly for supporting fuel rods, elongated straps intersect with each other to define grid cells. At least one pair of punched sections are formed, in spaced relation to each other, in each of peripheral walls of the respective grid cells. At least one of elongated spring elements is formed in the peripheral wall of each grid cell. Each spring element is formed such that a portion of the peripheral wall of the grid cell between the pair of punched sections bulges an...

A spacer for retaining and positioning elongated elements at one or a plurality of levels in a nuclear reactor fuel assembly comprises a grid structure of joined-together sleeve cells. A coolant is adapted to flow upwards through the fuel assembly. The majority of the sleeve cells are provided with an upstream edge with a waveform. The edge is waveformed in such a way that the upwardly flowing coolant first encounters a peak of the wave which is disposed between the joints of the sleeves and the...

A protection flap provided on mixing vanes of structural or mid-span mixer grids in order to eliminate or substantially reduce fretting of fuel rods retained by such grids. The flap is an extension or addition of vane material bent upwardly so as to be substantially parallel to the longitudinal axis of the fuel rod being retained. The flap provides a smooth, vertical surface against which the fuel rod contacts in case of vibration, bowing or shifting.