Westinghouse Electric Corporation

Medical University of South Carolina

Elwyn Roberts

Harry M Ferrari

Thomas B Huggins

Edmund E DeMario

David V Lambert

John T DiGrande

Melvin O Edmunds

Sobhan Patnaik

Warren L Mauterer

Theodore Besmann

Travis Knight

Robert N Stanutz

Described herein are systems and methods for imaging the top surface of a fuel pellet to observe the formation of radial cracks employing resistive heating to volumetrically heat the fuel pellet, but instead of passing the current axially through the pellet, electrodes were placed on the sides of a single pellet to pass the current transversely across the pellet allowing for an unobstructed view of the top surface of the pellet.

Experimental set up for studying temperature gradient driven cracking

An inspection system has a pellet diameter inspecting station and an apparatus for transferring pellets past the station. The apparatus includes a stationary support track for aligning and guiding pellets in a row along a linear path, and a transfer mechanism operable through forward and reverse strokes. The transfer mechanism has first and second grippers actuatable between pellet gripping and releasing positions and operable to grip respective rearmost pellets in a first row of pellets to be advanced past the inspecting station and in a second row of pellets previously advanced past the inspecting station. The transfer mechanism is operable to move from an initial position through the forward stroke to advance the pellets at a constant velocity along the linear path. The transfer mechanism actuates the second gripper from its releasing to gripping position before actuating the first gripper from its releasing to gripping position and starts movement from the initial position along the forward stroke before the first gripper is so actuated such that a gap is formed between the previously advanced row of pellets and the row of pellets to be advanced so as to prevent buckling of pellets in the latter row. The transfer mechanism is also operable to actuate the grippers to release the pellets and move through the return stroke relative to the released pellets back to the initial position.

Pellet transfer apparatus and method

A pellet escalator in a pellet loading apparatus for loading nuclear fuel pellets from a pellet press into a sintering boat includes a conveyor in the form of an elongated arm for moving pellets and being pivotable to vertically move its discharge end toward and away from a sintering boat. The arm has an elongated recessed channel through which travels the upper run of an endless flexible conveying belt for transporting pellets from a receiving end to the discharge end of the conveyor. A chute is mounted to the arm at its discharge end and extends therebelow such that the chute is carried by the arm at its discharge end for vertical movement therewith toward and away from the sintering boat. Resiliently-flexible, deflectable bristled brushes are attached to the chute in opposing vertical rows. The brushes in one row are oppositely inclined and vertically offset from brushes in the other row for defining a gravity feed flow path of non-linear configuration between adjacent inner brush ends for transferring pellets downwardly through the chute along the flow path at a drop rate controlled by brush deflections. A stop finger mounted to the arm at its discharge end is actuatable between blocking and unblocking positions in which it respectively stops and permits pellet discharge from the upper run of the belt in the arm channel.

Nuclear fuel pellet transfer escalator

A nuclear fuel assembly having an array of longitudinally extending fuel rods and axially spaced transverse grids with cells receiving the fuel rods therethrough employs anti-fretting protective devices for protecting lower end portions of tubular claddings of the fuel rods from damage-inducing contact with debris entrained in upward flow of coolant through the fuel assembly. Each device is in the form of a hollow sleeve disposed about and extending coextensive with the lower end portion of one fuel rod cladding. The sleeve has an upper portion which extends through one grid cell between lower and upper ends thereof, and a lower portion which extends below the grid cell from the lower end thereof to a bottom end of the fuel rod cladding spaced below the grid cell lower end.

Protective device for lower end portion of a nuclear fuel rod cladding

Spacer grids for a nuclear fuel assembly are arranged in superadjacent groups having grid springs and opposing dimples which contact a fuel rod passing through a cell of the spacer grid with a selected spring force. As fabricated, the lowermost grid exerts the greatest initial spring force on the rod; intermediate grids exert a smaller spring force; and the uppermost grid exerts yet a lower spring force. The fuel rod is supported laterally while it is permitted to age expand axially with little axial compression resulting from the spring forces of the springs and dimples, whereby bowing of the rod is diminished.

Growing community of inventors

Lugoff, SC, United States of America

Elwyn Roberts