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US 4,391,771 AGranted
Arrangement for retaining a fuel rod in a reconstitutable fuel assembly
AssigneeCombustion Engineering, Inc.
InventorAndrew J. Anthony
Life of this patent
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AssigneeCombustion Engineering, Inc.
InventorAndrew J. Anthony
Estimating the term…
An improved nuclear fuel assembly in which the lowermost grid is located close to the lower end fitting of the assembly, and a conventional Zircaloy-clad fuel rod is fitted with a stainless steel tip having a bevelled notch thereon for engaging resilient means on the grid within about one inch (2.5 cm) from the lower tip of the fuel rod. The notch mechanically restrains the fuel rod from lifting upwards during reactor operation, yet is shallow enough to permit removal of the fuel rod in the event reconstitution is required. The stainless steel tip is mechanically secured to the Zircaloy end cap of the fuel rod, and is located in a low importance flux region of the core so that the higher neutron poison absorption cross section of stainless steel is of little consequence. Since the lowermost grid secures each fuel rod within one inch of the lower end of the rod, there is little likelihood that the coolant flowing over the lower ends of the fuel rods will induce significant vibrations.
A nuclear fuel assembly having a horizontal lower end fitting, an elongated frame rigidly connected to the lower end fitting and extending vertically therefrom, the frame including a plurality of longitudinally spaced apart horizontal grids, each grid formed from a plurality of interconnected metal strips defining a multiplicity of openings and having resilient means projecting laterally into each opening, and a multiplicity of longitudinally disposed, parallel fuel rods each passing through an opening in every grid and maintained in vertical and horizontal position by the resilient means, the fuel rods formed of Zircaloy tubes sealed at each end with Zircaloy caps wherein the improvement comprises:
Dependencies are inferred from the claim text.