Abstract: A grid for a nuclear reactor fuel assembly which includes intersecting straps arranged to form a structure of egg crate configuration. The cells defined by the intersecting straps are adapted to contain axially extending fuel rods, each of which occupy one cell, while each control rod guide tube or thimble occupies the space of four cells. To effect attachment of each guide thimble to the grid, a short intermediate sleeve is brazed to the strap walls and the guide thimble is then inserted therein and mechanically secured to the sleeve walls. Each sleeve preferably, although not necessarily, is equipped with circumferentially spaced openings useful in adjusting dimples and springs in adjacent cells. To accurately orient each sleeve in position in the grid, the ends of straps extending in one direction project through transversely extending straps and terminate in the wall of the guide sleeve.

Abstract: An improved oil-pumping piston-assembly is provided for an oil-type circuit-interrupter to improve the interrupting performance during low-current conditions, having an improved hydraulic-dashpot action occurring during charging and discharging oil, incorporating, additionally, a "floating" piston design, and reducing the mechanical impulse forces exerted on the cylinder when high-current interruptions are made with an improved check-valve construction.The improved oil-pumping piston-assembly of the present invention is particularly adapted for the inclusion therewith of an auxiliary shunting separable-contact structure, which will, when desired, increase the current-carrying capability of the circuit-interrupter. Its inclusion, or exclusion, is optional, depending upon the current rating desired by the utility customer.

Abstract: A tank-type oil circuit-breaker has a pair of arc-extinguishing grid-structures disposed interiorly within the oil tank, each of said arc-extinguishing grid-structures having a pair of outwardly-directed horizontally-laterally-spaced venting ports, with the angular direction, or divergence between the two horizontally-spaced venting ports of somewhat critical angular magnitude.The construction is such that the two spaced venting ports on each arc-extinguishing grid structure collectively produce a resultant inwardly-directed jet force, which substantially counterbalances the outwardly-directed magnetic and mechanical forces resulting from the U-shaped line-current flow passing through the circuit-interrupter.The angular separation, or angular divergence provided between the two horizontally-laterally-spaced venting ports of each arc-extinguishing grid-structure falls within the range of angular magnitude of 80.degree. to 160.degree.. A desirable divergence range is between 100.degree. and 140.degree.