Abstract: Methods and apparatus for moving fuel bundles in a reactor pressure vessel (RPV) of a nuclear reactor are described. In one embodiment of the apparatus, a support tube facilitates the positioning of a multiple channeled magazine within the RPV, especially at locations adjacent fuel bundles. In the one embodiment, the support tube extends in the reactor pressure vessel into the area above the top guide. A magazine assembly is coupled to the support tube, and includes a magazine having a plurality of fuel bundle receiving channels. The magazine extends from the support tube so that it is adjacent the fuel bundles and the top guide. Grapples extend through the magazine channels, engage the fuel bundles, and retract the bundles into the magazine channels. The magazine and support tube, and thus the bundles, are then moved.

Abstract: A process and a system for detecting defective nuclear fuel assemblies in situ. The system includes two basic subsystems. The first subsystem is a sample collection system consisting of a hood placed over the fuel. A technique whereby a vacuum is drawn across a submerged nozzle of a degas tank is used to draw up the sample of fluid out of a fuel assembly. The second subsystem determines the amount of Kr-85 radioisotope contained in the fluid sample. This information is used to determine whether the fuel assembly contains a defective, i.e., leaking, fuel rod. The measurement values for Kr-85 in the fluid sample extracted from the fuel assembly are compared to the measurement values for Kr-85 in fluid samples taken from the reactor pool prior to fuel assembly testing and fluid samples taken from non-leaking control cells, the latter values representing the background to which the subject fuel assembly is compared.

Abstract: A method for ultrasonically inspecting a closely packed regular array of mutually parallel, uniformly sized and spaced rigid rods surrounded by a thin-walled metallic channel and immersed in a compressible medium. The method utilizes the properties of coherently scattered ultrasonic waves to identify rods which are defective, out of position or missing. A plane, monochromatic ultrasonic wave is transmitted toward the array of rods on one side thereof. Then an interference pattern produced on an opposing side of the array is detected. This interference pattern is the result of multiple scattering and diffraction of the plane ultrasonic wave during propagation through the array of rods. When the wavelength is comparable with the rod diameter and the rods are not too close together, scattering results in spatial relationships that produce an unusually large amount of wave penetration through the array in certain directions relative to the incident propagation vector.

Abstract: A reactor refueling mechanism includes a bridge, a trolley on the bridge, and an elevator on the trolley, with the elevator including a mast with a grapple at the lower end thereof. The bridge spans a reactor core and is rotatable therearound, with the trolley being translatable over the bridge. The elevator is also rotatable on the trolley, and the mast is vertically movable for positioning of the grapple. The combined movement capability of the mechanism allows the shuffling of fuel bundles between cells in the reactor core, and the accurate placement of square fuel bundles in complementary square cells in the core.

Abstract: A drive system for propelling first and second drive trucks of a bridge includes a first motor and transmission for driving the first truck, an independent second motor and transmission for driving the second truck and a controller for coordinating the first and second motors for maintaining differential transverse travel between the first and second drive trucks to less than a predetermined maximum. A first closed-loop controls velocity of the first drive truck, a second closed-loop controls velocity of the second drive truck, and an auxiliary closed-loop senses a difference in travel of the first and second drive trucks and adjusts performance of at least one of the first and second closed-loops.

Abstract: A refueling mast for a reactor complex includes four generally cylindrical tubes. Each inner tube has vertical grooved tracks formed therein. Each outer tube has a guide roller mounted thereon with grooves which mate with track grooves of a respective track on the adjacent inner tube. Track grooves are cold formed moving a roller die tool up and down each inner tube, while increasing pressure on the incorporated die rollers. This process flattens the inner tube where the tracks are being formed. The grooved tracks and the associated flattening provide the torsional rigidity required on the mast tubes for precise positioning and orientation of fuel elements.

Abstract: A fuel handling system for nuclear reactor plants comprising a camera containing underwater grapple means for transferring fuel units while submerged within a water containing reactor vessel.