Abstract: An electron discharge machining (E.D.M.) tool combination is useful for removal of an installed nuclear steam generator tube plug of conductive material. A conductive wand shaft connected to an E.D.M. voltage source is movably mounted in a housing and insulated from the housing. An inlet adapter is mounted on the wand end and connected to a source of deionized and demineralized water to provide a dielectric fluid and removed material carrier. A hollow electrode is mounted on a hollow extension beyond the end of the wand and inlet adapter in fluid communication with the adapter for movement with the wand relative to the housing. A drive plate is moved by means of a ball nut along a roller ball shaft which is rotationally driven by a motor in the housing. The drive plate reciprocates the wand and electrode for E.D.M. operation. The wand position can be monitored remotely by a signal from a potentiometer with a tap movable with the wand.

Abstract: A mechanical plug (20) having internal threads (24) and displaceable cone (30) for expanding the plug into secure engagement with a steam generator tube (14) is removed by a method which includes the step of moving the cone (30) upwardly within an internal cavity (22) along tapered surface (26), stretching the plug and thereby reducing its diameter by means of a tube stretcher 40 having an internally and externally threaded adapter (42), a bolt-like expander (50) and a force pad (52), and, pulling the plug from the tube.

Abstract: A probe (8) for inspecting the walls of a tubular conduit (40, 42) or the like is provided with a pair of movable arms (20a, 20b) urged outward from a central rod 4 into contact with the tube interior. Eddy current coils (16, 18) carried in the tube engaging ends (32a, 32b) of the arms (20a, 20b) are maintained in a constant, spaced apart relationship with the tube wall interior for increasing inspection accuracy and sensitivity. The movable arms (20a, 20b) can accommodate varying internal tube diameters, expanding and contracting relative to the central rod (4). A sloping nose (2) and tapered arm portions (32a, 32b) assist the probe in traversing the conduit interior.

Abstract: An upper end fitting 14 of a nuclear fuel assembly is provided at two of its opposite corners with spring retention caps 12 having a hook-like structrue defined by an inwardly directed flange 50 engaging a slot 56 in the top nozzle or end fitting 14. The spring packs 20 are retained within the spring retention caps 12 even if one or both spring retention screws 34 break and both the broken screw portions and the springs are maintained in operative position by the cap 12 until reconstitution.

Abstract: A debris catching strainer grid for capturing and retaining deleterious debris carried by reactor coolant before it enters the active region of a fuel assembly and creates fuel rod cladding damage has a plurality of fuel end cap compartments defined by pairs of first and second intersecting and slottedly interlocked grid-forming strips attached to a perimeter member and to each other. The end cap compartments defined by strips including vertical rows of integral leaves on opposite sides of the strip or by pairs of adjacent integral leaves intermediate their intersections. In the latter case, each leaf of the pair of leaves is the mirror image of the other leaf of the pair with an asymmetric shape with the greatest distance of projection out of the plane of the strip remote from the midpoint of the strips between their intersections.

Abstract: A hollow flow deflector (10) for use in a nuclear reactor fuel assembly having spaced grids of orthogonal strips (16, 18) mounted for defining square matrices of aligned and supported cylindrical fuel elements (12, 14). The deflector has a central cylindrical opening (20), an upstream end portion (22), a downstream end portion (24) and an intermediate transition portion (26) joining the end portions. The hollow flow deflector (10) has a plurality of concave flow channels (30) regularly spaced about the periphery of the body in its downstream end portion. The flow channels (30) have their inlet portion defined in the transition portion (26) of the body (10).

Abstract: A probe (10) for longitudinally traversing and circumferentially inspecting the interior of a tube. A rotating sensor containing head (44) is driven by a rotor (40) extending from the end (38) of a cylindrical housing (12) in which it is mounted. The axially fixed rotor (40) surrounds and is driven by a helix drive connection (70) to a piston extension (32). The piston (20) reciprocates in a cylindrical chamber (14) within the housing (12) in response to selectively applied fluid pressure acting against a spring bias (60). A strain gage (62) on the spring (60) controls the fluid pressure by means of valve (2) whereby reciprocation of the piston (20) and its extension (32) rotates the rotor (40) by means of the helical groove (70) and balls (72). The various parts are hollow to accommodate the necessary wire conductors (51 and 64) and H.sub.2 O.

Abstract: A nuclear steam generator isolation dam (28) locking pin (36) is slidably mounted and spring (52) biased in an axial bore (42,44) of a body (40) press fit in a dam boss (32). The pin (36) is actuated by a lever (54) in a slot (54,58,62) for selective lock-in, lock-out and spring biased travel for seeking its keeper (27) in the wall (26) of the nozzle.

Abstract: An automatic indexer assembly provides a constant axial and rotational movement of a signal-producing-sensor probe through a zone of a tube to be inspected with minimum signal distortion by means of threadedly connected fixed and movable hollow shafts. A probe tail is clamped to move with the movable shaft as it is driven by a constant speed drive motor and gear reducer mounted on a platform and guide plates which move with the movable shaft along a track parallel to the shaft axis. A water swivel and electrical slip ring also move on a platform with the movable shaft. Twisting of a fluid supply line and an electrical supply line is minimized. Constant sensor movement can be accomplished to permit accurate recording of the signal produced on a recording means with a minimum of backlash, acceleration, deceleration, or intermittent variables distorting the signal.

Abstract: A moisture separator reheater (10) tube support where the tubes are resiliently supported on curve-shaped metal spring members (46 or 58-64) in a manner permitting differential thermal radial and axial growth between the tube runs (26) and the support and spacer plate (30). The moisture separator reheater (10) units are used in nuclear pressurized water reactor systems.

Abstract: A bolt and keeper secure nuclear steam generation isolation dam segments in assembled relation. The bolt is rotated into locked position with its handle in a slot as a transverse projection on the bolt end is moved along a ramp into a securing notch against the bias of a compressible rubber spring.

Abstract: A couplant material for establishing a sound path of good acoustical impedance between a transducer and a supporting wave-transmitting substrate which is capable of being easily shaped at room temperature, withstanding thermal cycling from room temperature to over 450.degree. F., and substantially maintaining its acoustical properties in a radiation atmosphere while providing a minimum of irritating fumes and outgassing. The couplant material is a non-flammable, grease-like silicone fluid heavily filled with zinc oxide. It has been used previously as a heat sink compound for electronic components.

Abstract: A modular radiation shielding system for use on the lower side of a nuclear steam generator tubesheet 14 to protect inspection and repair workers in the primary head 20 of the generator 10 from radiation of the tubesheet 14 and plurality of tubes 12 it secures. The modular assemblies each comprise a geometrically shaped lead panel 22 sheathed in a stainless steel box 30 with a transverse opening extending therethrough for alignment with a tube 12. A rapid installation tube gripper 40, which may have a lead nose for shielding, extends through the opening and into a tube 12 to hold the geometrically shaped modular assembly against the lower surface of the tubesheet 14.

Abstract: A fuel element support grid for supporting a plurality of nuclear fuel elements intermediate their ends has at least some of the pairs of intersecting and slottedly interlocked strips including pairs of intersecting integral fluid flow directing vanes along at least one adjacent edge of each of the strips of the pair. Welds attach the pair of vanes to each other thereby providing welded attachment of the strips. The welds may be at the intersection of the vanes remote from their areas of integral attachment to their respective strips or they may be adjacent to their areas of integral attachment to their respective strips.

Abstract: A fuel rod support grid having a quadrangular perimeter and fuel rod compartments defined by slottedly interlocking grid-forming members with openings in register intermediate the lines of intersection of the grid-forming members to provide accessible exposed edges for small nugget welds. The edge of one of two adjacent openings in register may define a weld enhancing tab. Typically, the pairs of openings in register and their small nugget weld are at two locations intermediate the line of intersection of two grid-forming members.

Abstract: Fuel elements (16) support grids have openings (22,24) in the intersecting matrix strip (12,14) edges adjacent their points of intersection in which box-shaped conduit means (20) with integral mixing vanes (30 and 32) on the flow exit end (28) are secured. The vanes (30,32) create flow in two offset and oppositely transverse directions (34 and 36) relative to the direction of flow through the conduit means in order to generate thermal-hydraulic performance improving vortices (18) in the flow subchannels defined by the diagonal gaps between fuel elements (16). The box-shaped conduit means (20) also improve grid strength and rigidity.

Abstract: A method and apparatus for installing a mechanical tube plug 74 to assure the integrity of the seal between the tube plug 74 and tube 66. The actual torque applied in accomplishing each step in the tube plug installation process is monitored and recorded to assure that the integrity of each step of the tube plug installation process is maintained and, therefore, the integrity of the seal is assured.

Abstract: This application relates to a piston having two sets of three roller bearings mounted by means of milled grooves in a lightweight skirt of less diameter than the piston head. Each triangularly arranged set of roller bearings is symmetrically arranged to give a rolling three point stability and rolling anti-friction support to the piston as it reciprocates in the cylinder. Lubrication of the roller bearings is enhanced by openings through the piston skirt in the area of the oil rings above the roller bearings. The roller bearing axles are mounted in milled grooves.

Abstract: A probe (10) for scanning the interior of a curved conduit (28) has a carrier (12) with a rotatable portion (12b). Sensor means (18) are secured to the rotatable portion (12b) and are aligned with respect to the curvature of the conduit by means of an elongated flat strip (20), secured to the rotatable portion (12b) and extending longitudinally therefrom. Driving means (14) is provided to urge the probe (10) longitudinally through the conduit (28).

Abstract: A contamination monitoring system is disclosed wherein a low frequency alternating current signal is applied to a remotely mounted probe in the liquid being monitored for contamination. A fixed resistor located at the probe is electrically in parallel with the resistance of the liquid being monitored. The resistor is isolated from the liquid and allows a signal to be transmitted through an interconnecting cable even though the liquid resistance is very high. A signal is returned to signal processing electronics via the interconnecting cable to a high input impedance amplifier which drives an isolation transformer.