Abstract: A means for damping a low-friction azimuth resolver by use of an array of small magnets acting on a metallic pendulum attached to the resolver shaft. The magnetic field acts on the pendulum motion to induce a motional electromotive force and associated currents, which produce forces opposed to the motion, thereby acting as a non-contact damper on the resolver shaft. When the resolver shaft is at rest, no "eddy currents" are produced in the static magnetic field and no damping force exists. If the shaft moves, the attached pendulum cuts the magnetic flux lines and produces a drag force proportional to the shaft angular speed. The pendulum is typically made of diamagnetic material, such as lead or copper, thereby assuring that the induced forces arise solely from the motion. The magnetic field is produced by an array of small, but intense, samarium-cobalt magnets contained in a compact package providing for uniform damping throughout 360.degree. of resolver motion.

Abstract: An uncoupling tool has a two-module design: one module being a driver assembly for developing the uncoupling movement and the other module being a probe assembly for verifying the uncoupled condition. The probe assembly attaches to the threaded end of the piston tube with its probe extending inside the piston tube. The driver assembly attaches to the CRD ring flange. The probe assembly detects the ring magnet in the drive piston using analog position sensors which operate on the principle of the Hall effect and solid state circuitry. A top sensor provides a signal indicating that the control rod is in its "full out" position; a bottom sensor provides a signal indicating that the control rod is uncoupled; and an intermediate sensor provides a signal indicating that the control rod is in a transition position between the "full out" and uncoupled positions. The probe incorporates spacers which focus the magnetic flux onto the sensors.

Abstract: A tool set and a method of using those tools in combination is disclosed that are especially well adapted to the function of rearranging and/or replacing the control rods and fuel supports in a boiling water reactor. The tool set includes a grapple that is capable of simultaneously picking up both a control rod and its associated fuel support. A separate unlatching tool is provided for pulling the control rod's release handle in order to decouple the control rod from a control rod drive. A storage rack that may be mounted in the reactor pressure vessel is provided for storing a fuel support and a pair of control rods when the positions of selected control rods are being shifted about the reactor core area. In the method aspect of the invention, the unlatching tool is used to pull the control rod's release handle. Thereafter, the grapple lifts the control rod and its associated fuel support as a unit.

Abstract: A method and a gage for testing uncoupling tools to ensure proper operation prior to use. The uncoupling tool gage simulates the actual conditions under which the uncoupling tool is expected to perform. The gage has a cylindrical guide for slidably receiving a magnet housing. The guide is supported such that it is concentric with respect to the probe of an uncoupling tool to be checked. The magnet housing is placed inside the cylindrical guide and then moved toward the bottom thereof. When the magnet moves into proximity with a switch in the uncoupling tool probe, an indicator lamp in the uncoupling tool illuminates. If the face of the magnet housing is within a range band on the outside of the guide when the indicator is illuminated, then the uncoupling tool is operating properly.

Abstract: An improved method for repair of incore-instrumentation-housing and related defects in a nuclear reactor system involves three stages, each with ultrasonically assisted inspections. In the first stage, a defective incore housing is removed and the exposed area and aperture at the former location of the incore housing is ultrasonically inspected using an ultrasonic probe with a tiltable disk-shaped head that self-conforms to the local contour of the reactor vessel bottom. In the second stage, a weld buildup is formed. The reactor is then sealed and the weld buildup is machined to define an aperture therethrough. The weld buildup is then ultrasonically inspected with a second probe with a centering member that is stationary as the probe body is moved vertically relative to it. In the third stage, a J-prep is formed. A new incore housing is inserted through the weld buildup aperture. The new incore housing is welded at the J-prep. The J-weld is ultrasonically inspected using a third ultrasonic probe.

Abstract: A tool set and a method of using those tools in combination is disclosed that are especially well adapted to the function of rearranging and/or replacing the control rods and fuel supports in a boiling water reactor. The tool set includes a grapple that is capable of simultaneously picking up both a control rod and its associated fuel support. A separate unlatching tool is provided for pulling the control rod's release handle in order to decouple the control rod from a control rod drive. A storage rack that may be mounted in the reactor pressure vessel is provided for storing a fuel support and a pair of control rods when the positions of selected control rods are being shifted about the reactor core area. In the method aspect of the invention, the unlatching tool is used to pull the control rod's release handle. Thereafter, the grapple lifts the control rod and its associated fuel support as a unit.

Abstract: An improved method for repair of incore-instrumentation-housing and related defects in a nuclear reactor system involves three stages, each with ultrasonically assisted inspections. In the first stage, a defective incore housing is removed and the exposed area and aperture at the former location of the incore housing is ultrasonically inspected using an ultrasonic probe with a tiltable disk-shaped head that self-conforms to the local contour of the reactor vessel bottom. In the second stage, a weld buildup is formed. The reactor is then sealed and the weld buildup is machined to define an aperture therethrough. The weld buildup is then ultrasonically inspected with a second probe with a centering member that is stationary as the probe body is moved vertically relative to it. In the third stage, a J-prep is formed. A new incore housing is inserted through the weld buildup aperture. The new incore housing is welded at the J-prep. The J-weld is ultrasonically inspected using a third ultrasonic probe.

Abstract: An automated system for examining incore housing welds in a nuclear reactor from above is disclosed. The probe uses both ultrasonic and eddy current non-destructive inspection coils to examine the weld for indications, or flaws. It is inserted into the incore housing tube from above because of the high radiation exposure workers experienced using the prior method of inserting a probe into the incore housing from below. This is conveniently done when the incore flux monitors are removed during standard maintenance, and is performed from the refueling bridge.

Abstract: An apparatus and process for the remote inspection for stress corrosion cracking of welded shut boiling water reactor shroud access cover plates is disclosed. The apparatus consists of a streamline housing having a top side with lugs for the attachment of lowering lines on either end of the housing. Medially of the streamline housing and projecting downwardly from the bottom of the streamline housing, there is provided a central rotating pedestal with a rubber base. The rotating pedestal and rubber base enable the entire housing to rest on and rotate relative to the pedestal and rubber base. A first motor interior of the housing rotates the housing at a bevel gear rigidly mounted to the central pedestal. A second motor rotates a threaded shaft driving a ball screw with an attached mount for an ultrasound transducer. The mount and transducer responsive to rotation of the ball screw traverse along the elongate dimension of the housing over an opening through the bottom of the housing.

Abstract: In operation, the device is lowered with paired lines attached to both housing lugs but suspended under tension only from one line to one lug so that the streamline housing is vertically disposed. With the housing vertically disposed during lowering, obstacles can be avoided such as the guide rod for the steam separator and dryer as well as the feedwater and core spray spargers. When lowered to the vicinity of the ledge and cover plate to be inspected, the slack line is fished around any obstacle and thereafter placed under tension. The streamline housing is then lowered using both lines in a horizontal position so as to expose downwardly the pedestal and rubber foot. Lowering is completed with remote camera assistance. Sample sweeps with the ultrasound transducer of spaced apart sections of the cover plate weld are used for precise centering of the pedestal and rubber base with respect to the center of the cover plate.