Abstract: The method comprises applying a braze material to a sleeve in a manner so that the sleeve may be attached to a tube so as to bridge the defective region of the tube. The sleeve is constructed to have a groove on the outside surface thereof that extends around the entire circumference. The groove is filled with braze material and a flux is applied to the braze material in a manner to prevent the braze material and flux from becoming removed. Once such a sleeve has been inserted into the defective tube, the sleeve is internally expanded in the area of the sleeve wherein the groove is located. The expansion of the sleeve in the area wherein the groove is located causes the braze material to closely contact the inside surface of the tube. The other end of the sleeve can then be either similarly placed in contact with the tube or welded to the tube. Next, the area of the tube wherein the braze material is located is internally heated so as to create a brazed joint between the sleeve and the tube.

Abstract: The spent fuel consolidation system provides a system for vertically and remotely dismantling an irradiated nuclear fuel assembly while the fuel assembly remains submerged in a coolant and for consolidating the spent fuel rods of the dismantled fuel assembly. The system comprises a platform rotatably mounted on a vertical support with a fuel assembly station, a consolidation station, and a canister station attached to the platform. A gripper mechanism is slidably disposed on the vertical support for transferring spent fuel rods from one station to another as the various stations are rotated into alignment with the gripper mechanism. The fuel assembly station provides a station for holding the fuel assembly while the spent fuel rods are removed therefrom, the consolidation station provides a station for consolidating the spent fuel rods, and the canister station provides a station for holding the consolidated spent fuel rods.

Abstract: The spent fuel consolidation system provides method and apparatus for remotely vertically and horizontally compacting an array of spent fuel rods while the fuel rods remain submerged in a coolant. The invention comprises a row ordering section for rearranging the configuration of the fuel rods, horizontal consolidation section for horizontally compacting several rows of fuel rods, and a vertical consolidation section for vertically compacting several rows of horizontally compacted fuel rods. The system is capable of compacting the fuel rods from a given fuel assembly to about one half of the volume originally occupied by such fuel rods in the fuel assembly thereby providing greater storage capacity for a given volume of spent fuel storage.

Abstract: The latching mechanism comprises a pivotable member that cooperates with a contact member for coupling the contact member to the pivotable member. A drive mechanism moves the contact member into contact with the pivotable member thereby pivoting the pivotable member and allowing the contact member to seat in the pivotable member. A biasing mechanism urges the pivotable member into its initial position. The drive mechanism can be also utilized to release the contact member from the pivotable member.

Abstract: A method of operating a pressurized water nuclear reactor comprising determining the present core power and reactivity levels and predicting the change in such levels due to displacer rod movements. Groups or single clusters of displacer rods can be inserted or withdrawn based on the predicted core power and reactivity levels to change the core power level and power distribution thereby providing load follow capability, without changing control rod positions or coolant boron concentrations.

Abstract: A liquid metal pump bearing support comprises a series of tangentially oriented spokes that connect the bearing cylinder to the pump internals structure. The spokes may be arranged in a plurality of planes extending from the bearing cylinder to the pump internals with the spokes in one plane being arranged alternately with those in the next plane. The bearing support structure provides the pump with sufficient lateral support for the bearing structure together with the capability of accommodating differential thermal expansion without adversely affecting pump performance.

Abstract: The baffle inspection apparatus comprises a gauging mechanism mounted on a movable support for determining the width of a gap between two adjacent baffle plates in a nuclear reactor. The gauging mechanism comprises a rotatable member with a plurality of feeler gauges disposed thereon that is capable of remotely rotating and laterally aligning each feeler gauge with the selected gap to determine the size of the gap. The apparatus may be equipped with underwater camera and lights for remotely viewing the inspection operation.

Abstract: The baffle maintenance apparatus comprises a peening apparatus mounted on a movable carriage for reducing the width of a gap between two adjacent baffle plates in a nuclear reactor. The peening apparatus comprises an hydraulic hammer mounted on a pivotable plate that is capable of being positioned in proper relationship to the baffle plate for reducing the gap therebetween. The baffle maintenance apparatus may also comprise a gauging mechanism mounted on the carriage for determining the width of the gap between the baffle plates.

Abstract: A fuel assembly for a nuclear reactor comprises a 5.times.5 array of guide tubes in a generally 20.times.20 array of fuel elements. The guide tubes are arranged to accommodate either control rods or water displacer rods. The fuel assembly also comprises a plurality of Inconel and Zircaloy grids arranged to provide stability of the fuel elements and guide tubes while allowing the flow of reactor coolant therebetween.

Abstract: A pump and heat exchanger for pumping a conductive fluid through interaction with a magnetic field and a flowing second conductive fluid. A plurality of tube sets are arranged along radii of a circular annulus formed between two shells. One of the fluids is pumped by conventional means through the radial spaces between the tubes, generating currents and voltages which cause the other fluid to flow within the tubes and in the opposite direction. In magnetic air gap regions of the pump, the tubes are rectangular in shape. As a result of the circular geometry, currents flow circumferentially within the annulus, and voltages are maintained at a low value.

Abstract: After the tube portion to be removed is severed from the remainder of the U-tube and its weld to the header is machined off, the internal surface of the portion is engaged internally by an ID gripper and pulled out of the header. Then the external surface is engaged by an OD gripper and pulled further out of the header. The first tube length is pulled out as far as the space under the header permits and is then cut off. Successive lengths are likewise pulled out and cut off.The apparatus for accomplishing this object includes a base secured to the header by expanded mandrel mechanisms. A carriage is suspended from the base on screws which are driven by a motor to move the carriage away from and towards the base. An OD gripper assembly is suspended from the carriage and is movable by fluoroactuated piston rods away from and towards the carriage. An ID gripper assembly extends through the OD gripper assembly. The gripper of the ID assembly is actuable to engage the internal surface of the tube portion.

Abstract: The nuclear reactor shutdown system comprises a temperature sensitive device connected to a magnetic latch of a neutron absorbing mechanism. The temperature sensitive device is disposed in the neutron absorbing mechanism in such a manner that it is exposed to the reactor coolant so that when the reactor coolant temperature rises above a specific level, the temperature sensitive device will cause the magnetic latch to open and allow neutron absorbing material to enter the reactor core. The temperature sensitive device comprises temperature sensitive material which may be a temperature sensitive resistor sometimes referred to as a thermistor. The thermistor is a device wherein its resistivity significantly increases with increase in its temperature such that when its temperature has significantly increased, the current passing through this system substantially decreases.

Abstract: The electric actuator comprises a deep cup harmonic drive gear train member with an electric motor, brake, tachometer, and resolver disposed therein. The arrangement and coupling of the components provides a high torque-to-weight ratio actuator that is capable of more than 360.degree. rotation.

Abstract: The pump isolation valve provides a means by which the pump may be selectively isolated from the remainder of the coolant system while being compatible with the internal hydraulic arrangement of the pump during normal operation of the pump. The valve comprises a valve cylinder disposed around the pump and adjacent to the last pump diffuser with a turning vane attached to the lower end of the valve cylinder in a manner so as to hydraulically match with the discharge diffuser. The valve cylinder is connected to a drive means for sliding the valve cylinder relative to the diffuser support cylinder so as to block flow in either direction through the discharge diffuser when the valve is in the closed position and to aid in the flow of the coolant from the discharge diffuser by means of the turning vane when the valve is in the open position.

Abstract: The tube plug comprises a shell having a tapered inner surface against which an externally tapered expander member moves by application of a pulling force. The motion of the expander member relative to the shell causes the shell to expand into contact with a heat exchange tube thereby plugging the tube. The expander member is formed from a hardened metal with tangentially blended leading radius and a self-locking trailing edge which provides for ease in expanding the shell while preventing inadvertent unlocking of the plug. The shell has a substantially uniform wall thickness throughout the portion of the shell which experiences expansion so that the force necessary to perform the expanding process does not increase beyond the strength limitations of the installation equipment as the expander member is moved through the shell.

Abstract: A fuel assembly in a nuclear reactor comprises a locking mechanism that is capable of locking the fuel assembly to the core plate of a nuclear reactor to prevent inadvertent movement of the fuel assembly. The locking mechanism comprises a ratchet mechanism that allows the fuel assembly to be easily locked to the core plate but prevents unlocking except when the ratchet is disengaged.

Abstract: The electromagnetic pump comprises specially shaped magnetic pole extensions disposed around the duct along the line of flow of the fluid. The pole extensions increase the magnetic field along the axial center line of the duct, thereby increasing the mid-duct fluid body forces which in turn increase mid-duct velocity. The pole extensions decrease both viscous drag along the electrode walls and turbulent mixing in the exit regions of the duct. Both of these reductions increase pump efficiency. Moreover, the nearly uniformed velocity profile obtained with these pole extensions reduces current leakage in the end regions of the electrodes.

Abstract: Apparatus for decontaminating radioactive components comprising an attachment mechanism for completely suspending the apparatus from the tube sheet of a nuclear steam generator, a first drive mechanism for moving the apparatus in a first direction, a second drive mechanism for pivoting the apparatus in a second direction, and a third drive mechanism for moving the apparatus in a third independent direction. The apparatus also comprises a dual nozzle arrangement attached to the third drive mechanism for directing a water-grit mixture toward the component to be decontaminated. The apparatus provides a mechanism for remotely decontaminating the channel head of a nuclear steam generator so as to allow working personnel to enter therein.

Abstract: The plug installation apparatus comprises a mechanism for moving an internally captured expander member relative to the shell wherein it is captured thereby expanding the plug into contact with the internal surface of a tube within which the plug is disposed. The apparatus further comprises a sensor mechanism for determining that the plug has been properly inserted in the tube prior to expanding the plug for preventing improper expansion of the plug. The apparatus also comprises force measuring devices for determining and verifying that the proper amount of force has been applied to the expander member.

Abstract: The sleeving method comprises inserting a metal sleeve within a tube so as to bridge the defective region of the tube. The sleeve is constructed to have teeth on the outside thereof that are capable of tightly contacting the inside surface of the defective tube and creating a labyrinth-type seal therebetween. Once such a sleeve has been inserted into the defective tube, the sleeve is internally expanded in the area of the sleeve wherein the teeth are located. The expansion of the sleeve in the area wherein the teeth are located causes the teeth to closely contact the inside surface of the tube. The other end of the sleeve can then be either similarly attached to the tube or welded to the tube. Next, the remainder of the sleeve is internally expanded which causes the sleeve to shrink in length which results in the teeth slightly penetrating the inside surface of the tube thereby creating a leak tight seal therebetween.