Abstract: Nuclear reactor upper internal guide tube having a flow diffuser integral with its bottom end. The guide tube provides guidance for control rods during their ascent or descent from the reactor core. The flow diffuser serves to divert the upward flow of reactor coolant around the outside of the guide tube thereby limiting the amount of coolant flow and turbulence within the guide tube, thus enhancing the ease of movement of the control rods.

Abstract: An improved nuclear reactor primary loop flowmeter having two spaced N-16 detectors (12 and 14) positioned along the primary loop piping for monitoring the N-16 activity within the coolant at the respective detector locations. The outputs of the two detectors are cross-correlated to determine the transit time of corresponding N-16 perturbations viewed at the two detector locations. The improvement comprises means for switching (34 and 36) the respective detector output electronic processing channels (18 and 20) between detectors (12 and 14) and measuring the maximum cross-correlation function (30 and 32) with the detector output channels in their original and switched positions to determine the true coolant transit time between detector locations and any phase shift induced by the detector output channels.

Abstract: A tube lock drill for remotely performing operations on equipment including a positioning mechanism disposed in the equipment for selectively positioning the tool with respect to the equipment with the tool comprising a locking mechanism associated with the positioning mechanism for securing the tool in proper relationship to the equipment, a cutting mechanism disposed on a locking mechanism for performing cutting operations on the equipment, and a lifting mechanism attached to the positioning mechanism and attached to the cutting mechanism for lifting the cutting mechanism into contact with the equipment. The tube lock drill tool is capable of being arranged in a plenum of a nuclear steam generator so that remote operations may be performed on the tube sheet and heat exchange tubes in the nuclear steam generator.

Abstract: A method of automatically realigning a steam generator secondary piping system, such as the feedwater system, in the event of a pipe break to a given steam generator in a system having plural steam generators sharing, in part, a common secondary piping system. A feedwater line break is identified by monitoring the respective generators' steam exit line pressures and comparing the several pressures to a first predetermined setpoint. If any one of the several monitored pressures falls below the first setpoint the main steam line isolation valves are automatically closed and the respective generator pressures are again monitored and compared to a second predetermined setpoint. The feedwater line to the generator then exhibiting a drop in pressure below the second setpoint is isolated and the remaining generator main steam line isolation valves may be opened to return the functional intact generators to the system.

Abstract: The internal diameter measuring apparatus comprises a flexible supporting member capable of being inserted into a heat transfer tube in a nuclear steam generator with flexible centering devices disposed on the flexible supporting member at various locations along the flexible supporting member for centering the measuring apparatus within the heat transfer tube. The measuring apparatus also comprises contacting apparatus disposed on the flexible supporting member for contacting the inside surface of the heat transfer tube that is capable of deflecting in response to variations on the inside surface of the heat transfer tube. The contacting apparatus is connected to a transforming mechanism disposed in the flexible supporting member for monitoring the deflection of the contacting apparatus and for transforming the so monitored deflections into readings indicating the internal diameter of the heat transfer tube.

Abstract: An apparatus for efficiently and safely recombining hydrogen and oxygen gas to form water vapor, the apparatus being particularly adapted for use with a nuclear reactor system in which potentially dangerous hydrogen gas, evolved within the containment vessel during certain postulated accident conditions, can be eliminated. Further, this apparatus also aids in the removal of certain radioactive contaminents from the gases in a containment vessel.

Abstract: A method and apparatus for lowering the contrast range between a welding arc and its surroundings for remote viewing of an arc welding process. A monochromatic light source (10) is used to illuminate the area surrounding the welding arc (18) and a narrow band interference filter (22) tuned to the wavelength of the monochromatic light (10), is placed in front of a viewing camera (24). The monochromatic light enhances the arc background while the filter (22) attenuates the arc illumination that reaches the camera for a more desirable contrast ratio so that the arc, weld puddle and surrounding area can be visible with a high degree of definition on the monitor.

Abstract: Ion exchangers which reversibly store borate ions in a temperature dependent process are combined with evaporative boric acid recovery apparatus to provide a boron control system for controlling the reactivity of nuclear power plants. A plurality of ion exchangers are operated sequentially to provide varying amounts of boric acid to a nuclear reactor for load follow operations. Evaporative boric acid recovery apparatus is utilized for major changes in the boron concentration within the nuclear reactor.

Abstract: Apparatus for vertically separating a motor drive shaft from a load shaft while maintaining alignment between the motor drive shaft and the load shaft so that the load shaft and associated apparatus may be accessed for repair or replacement.

Abstract: Apparatus for removing or inserting studs of a nuclear reactor vessel closure head so that the closure head may be removed for refueling the nuclear reactor. The apparatus comprises a carriage having an engagement mechanism for firmly contacting the studs and a rotation mechanism for rotating the engagement mechanism. A drive mechanism is also attached to the carriage for rotating the rotation mechanism. In addition, a support device is associated with the carriage that is capable of supporting the weight of the carriage during transit and of supporting the weight of the stud while the stud is being manipulated.

Abstract: This invention provides a method of operating a nuclear reactor having a negative reactivity moderator temperature coefficient with the object of maintaining a uniform and symmetric Xenon distribution above and below substantially the center of the core over a substantial axial length of the core during normal reactor operation including load follow. In one embodiment variations in the Xenon distribution are controlled by maintaining a substantially symmetric axial power distribution. The axial offset, which is employed as an indication of the axial power distribution, is maintained substantially equal to a target value, which is modified periodically to account for core burnup.

Abstract: A powder compact of mixed zirconium, carbon and uranium monocarbide powders is heated to melt first the zirconium constituent. The liquid zirconium reacts with the solid phases by a diffusion controlled process to form zirconium carbide and a (U,Zr)C solution. The compact is then heated to a higher temperature to melt the uranium monocarbide to form additional (U,Zr)C solid solution whereby the final product is composed of a single phase homogeneous solid solution.

Abstract: Systems for, within a sealed environment, determining the bulk density of radioactive nuclear fuel particles flowing in a process stream. A carrier having a known weight and a channel of known volume is selectively shuttled between the flowing particles and a weigh cell. Thus, from the weight of a known volumetric sample, the bulk density is determined. The carrier and selected portions of the cell and carrier transporter are enclosed within a sealed structure to contain the radioactive material within a controlled environment. Subsequent to density determination, the particle sample is dumped, preferably back into the flowing stream, by structure which rotates the carrier or opens a door at the bottom of the channel. The systems also provide for sealing of the housing at various positions of the carrier.

Abstract: Heliostat assemblies, including fabrication methods, providing capability for azimuthal and elevational sun-tracking. A plurality of mirrors are affixed in a rectangular array which is diametrically mounted within a pair of circular rims which extend perpendicular to the mirror array. A belt-type drive rotates the rims on loadbearing rollers to adjust the elevational orientation of the mirror assembly, and a second drive rotates a carriage upon which the rollers are mounted to adjust the azimuthal orientation of the mirror assembly. Lightweight compression members and sectional shapes transfer loads among the assembly components, including tension cables which assist in transmitting loads between the elevation rims and the mirror assembly.

Abstract: An improved neutron monitoring and startup source for a thermal nuclear reactor including a fast neutron emitting material encapsulated within a cladding substantially black to thermal neutrons. In another embodiment the inventive source, or any source, is advantageously affixed to movable control elements so as to reside out of the reactor core for periods of high neutron flux.

Abstract: A condenser arrangement having a load bearing member hermetically coupled to the condenser's condensation chamber. Load transfer means are adapted to transfer the condenser vacuum load acting on the load bearing member to the turbine or turbine support in a manner to balance the condenser vacuum load acting on the turbine through the turbine exhaust. In the preferred arrangement means are provided to minimize contributions from the condensate to forces acting upon the load bearing member.

Abstract: A method and apparatus for removing iodine-131 and iodine-125 from a liquid sodium reactor coolant. Non-radioactive iodine is dissolved in hot liquid sodium to increase the total iodine concentration. Subsequent precipitation of the iodine in a cold trap removes both the radioactive iodine isotopes as well as the non-radioactive iodine.

Abstract: A method and apparatus for detecting a specific leaking tube or tubes and for detecting the position of a defect within a tube in a liquid metal-to-water tube type heat exchanger, generally used in a sodium cooled nuclear reactor. Subsequent to draining of the heat exchanger a solid reaction product of the liquid metal and water forms at a leak location. Introducing an inert gas to the exterior of the tubes, creating a pressure differential across the tube wherein the interior pressure is less than the exterior pressure, and heating the tube, provide dissociation and isolation of the reaction product, which, when analyzed for chemical content, indicates which tube or tubes is defective. A heat probe apparatus which traverses the interior of the tubes may be used in the heating step, which, as a result of the speed of the dissociation process at high temperatures provides a means for detecting the specific leak location within the tube.

Abstract: A remote gaging apparatus for remotely measuring the pellet stack length and plenum length within a nuclear reactor fuel element comprises a housing capable of having a nuclear fuel element inserted therein with a drive mechanism disposed in the housing and attached to a rod having a stop mounted on the rod for selectively inserting the rod into an open end of the nuclear fuel element. The remote gaging apparatus further comprises a measuring device disposed in the housing and associated with the stop for contacting the stop when the rod is inserted into the fuel element thereby measuring the length of insertion of the rod in the fuel element. By determining the length of insertion of the rod in the fuel element, the stack length of nuclear fuel pellets in the fuel element can be determined along with the length of the unfilled plenum of the nuclear fuel element.

Abstract: A pellet dimension checker for determining the weight, length, and density of a pellet such as a nuclear fuel pellet. The checker comprises a rotatable arm for transferring a pellet from a pellet conveyor, to several dimensional measuring stations, and back to the conveyor if the dimensions of the pellet are determined to be within predetermined limits. Should the pellet be nonconforming, the rotatable arm removes the pellet from the process stream.