Abstract: A reactor vessel in-service inspection assembly (17) having an improved positioning device (80) for properly and repeatedly locating the inspection transducers (75) of the assembly within a hollow portion of the reactor vessel cavity. An acoustic transducer of the positioning device of this invention is affixed to the positioning arm (40) of the inspection transducers (75). The positioning transducer is operable to generate and simultaneously, radially direct acoustic signals around the circumference of the hollow portion of the vessel cavity and receive the signals reflected off of the cavity walls at a location within the hollow cavity. Means are provided for monitoring the received signals as a function of time. The in-service inspection assembly transducer positioning arm is arranged to automatically move in response to the monitored difference in the time of reception of the received signals to locate the positioning transducer at a preestablished location within the hollow portion of the reactor cavity.

Abstract: A gas tungsten arc welding torch having an elongated gas nozzle (18) with an oblong cross section designed for deep groove, narrow gap welding. The nozzle is rotatably coupled to and communicates with a gas port within the main torch body (16) and defines a gas passage along the length of the welding electrode (10), which extends through the longitudinal axis of the nozzle. The nozzle (18) includes a detachable end section (42) which captures and supports a replaceable gas lens (30) disposed within the gas passage of the nozzle within 7/8 to 1 inch from the nozzle orifice (40), and traverse to the direction of gas flow. The electrode (10) is formed from a solid tungsten rod center (12) and a concentric outer sleeve (14) substantially lower in electrical resistivity than the tungsten rod, which is adhesively and cohesively bonded to the tungsten. The outer sleeve extends from the point of electrical connection (32) within the main torch body (16) to a point on the tungsten electrode downstream of the gas lens.

Abstract: A method of applying a gas shielded tungsten arc welding process in a deep, narrow groove joint wherein the shield gas is directed to the weld puddle through an elongated gas nozzle 14 which surrounds a substantial length of the welding electrode and is sized to extend into the groove. The improvement including incrementally increasing the width (20) of the nozzle to correspond to increases in the width of the groove at preselected increases in the width of the groove as the nozzle is withdrawn from the groove during successive weld passes. The preselected elevations and nozzle widths are chosen so that the desired gas shield area does not substantially exceed 1.25 times the nozzle width.

Abstract: A method and apparatus for effecting within a nuclear power plant horizontal separation of the vertically-extending cylindrical wall of the shell of a steam generator by an accurate cutting technique that generates a weld accommodating profile in preparation for subsequent rejoining. This is attained by progressive installation of horizontal hinged-section tension band assemblies around the shell, adding vertical anchor members clamped to the bands at circumferential intervals therearound, hanging and locking track support brackets onto the anchor members, assembly of a multiple-section rigidized circular track onto the support brackets and around the shell, vertically and radially adjusting and locking the track in place, roller mounting a carriage-supported milling machine assembly on the track, and taking a series of tapered milling cuts in the shell wall while the milling machine assembly is moved along the track by use of gear teeth thereon.

Abstract: A photoelectric docking device for remotely positioning a first member relative to a second member, having a point light source coupled to the first member, which is directed to focus a narrow beam of light on a photosensor fixedly connected to the second member. The photosensor is responsive to the reception of light from the point light source on the first member to provide electrical outputs representative of the relative position of the point source with respect to the photosensor in three-dimensional space. The electrical outputs of the photosensor are then displaced as a three-dimensional pictorial representation of the relative position of the first and second members. Means are further provided for identifying when the first and second members are in intimate contact.

Abstract: Apparatus for monitoring the processes of a nuclear reactor to detect off-normal operation of any process and for testing the monitoring apparatus. The processes are evaluated by response to their paramters, such as temperature, pressure, etc. The apparatus includes a pair of monitoring paths or signal-processing units. Each unit includes facilities for receiving on a time-sharing basis, a status binary word made up of digits each indicating the status of a process, whether normal or off-normal, and test-signal binary words simulating the status binary words. The status words and test words are processed in succession during successive cycles. During each cycle, the two units receive the same status word and the same test word. The test words simulate the status words both when they indicate normal operation and when they indicate off-normal operation. Each signal-processing unit includes a pair of memories.

Abstract: The identity of a cantilevered end effector support member and its angular position on the platform member of a carriage movable along an arm which is rotatable in a plane parallel to a steam generator tubesheet, are supplied to a tubesheet servicing machine control system in the form of a discrete pattern of electrical signals which is used to determine the offset required in aligning the end effector with a particular point on the tubesheet. The discrete pattern of electrical signals is generated by at least two sensor elements mounted on one of the members, preferably at different radial distances from the pivot axis of the support member. At least two trigger elements are mounted on the other member in such a pattern as to trigger selected sensor elements to produce the discrete pattern of signals.

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 spacer and block cutting torch is lowered through the wrapper-to-shell annulus of a removed-top steam generator by addition of vertical sections of hollow-back column by vertical movement of a motorized carriage along a rack-and-guide track extending upwardly from atop the wrapper and manipulation of column clamps, one movable with the carriage and the other affixed to the wrapper, to transfer column weight from carriage to wrapper-top during adding and subtracting column sections. The rearward concave side of the column, held flush with the wrapper wall, readily accepts and serves to enclose operating gas hoses for the cutting torch. Yieldable bias means cooperates with the interior of the generator shell to urge the concave side of the column toward the wrapper.

Abstract: A nuclear reactor flux mapping system having a plurality of neutron detectors operable to be driven into and out of a reactor core along any one of a number of pre-established paths. The detectors, corresponding drives (22) and drive controllers (28) are arranged into at least two physically separate and functionally independent channels. Each channel is respectively arranged to scan complementary paths through the core during normal system operation. At least two, redundant, functionally independent and physically separate "command end of processing" channels (31 and 33) are provided. Each of the command and processing channels (30) are independently operable to automatically, programmably sequence the detector scans and process the detector output data on all of the detector channels while being electrically buffered from each detector channel through two-ported memories (36) in a manner to prevent faults on any of the channels from disabling any of the other system channels.

Abstract: A servicing machine for a steam generator is accurately set up in the generator channel head with a pivoted arm mounted for rotation in a plane parallel to the tubesheet. The angular position of the arm, the longitudinal position of a carriage mounted on the arm and the vertical position of a platform on the carriage are remotely controlled to maneuver a probe used in mapping the precise location of the thousands of holes in the tubesheet. Various operations are then performed at each precise hole location by tools carried by the arm mounted carriage to prepare for installation of new tubing. The operation of a pair of remotely controlled pivoted arms, one on each side of the channel head divider plate, is coordinated to automatically position the ends of U-shaped tubes in corresponding holes in the tubesheet on opposite sides of the divider plate and to secure the same in place.

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 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: 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: A solid solution strengthened Ni-Cr-Fe alloy capable of retaining its strength at high temperatures and consisting essentially of 42 to 48% nickel, 11 to 13% chromium, 2.6 to 3.4% niobium, 0.2 to 1.2% silicon, 0.5 to 1.5% vanadium, 2.6 to 3.4% molybdenum, 0.1 to 0.3% aluminum, 0.1 to 0.3% titanium, 0.02 to 0.05% carbon, 0.002 to 0.015% boron, up to 0.06 zirconium, and the balance iron. After solution annealing at 1038.degree. C. for one hour, the alloy, when heated to a temperature of 650.degree. C., has a 2% yield strength of 307 MPa, an ultimate tensile strength of 513 MPa and a rupture strength of as high as 400 MPa after 100 hours.