Abstract: A CEDM data acquisition system (40) receives analog coil-current signals from control element drive mechanism coils (18, 20); conditions the analog signals to remove noise induced therein by the electronic circuitry (44) associated with the control element drive mechanisms; digitizes the conditioned analog signals; displays the acquired test data; and records the data for future use. The inventive data acquisition system preferably has the ability to simultaneously measure, display and record coil-current data for all of the five coils associated with each CEDM rod-group with respect to time. Further, the inventive data acquisition system preferably allows the user to monitor, display and record data for up to eight CEDMs simultaneously. It also allows the measurement of rod-drop times during rod-drop testing of the CEDMs.

Abstract: A measurement chamber (18) having an upper and a lower region is at substantially the same elevation as a horizontal pipe (12) having a top region and a bottom region. An equalization line (14) fluidly connects the top region of the pipe (12) to the upper region of measurement chamber (18). A sample line (16) fluidly connects the bottom region of pipe (12) to the lower region of the measurement chamber (18). Heat junction thermocouples (22) generate a signal indicative of the level of fluid in the measurement chamber (12) which is equal to the level of fluid in the pipe (12). The signal is transmitted to a remote location by line (24).

Abstract: A pair of openings are formed using an EDM technique. A pair of clamps are inserted into the openings and moved toward each other until such time as the inboard edges of the two openings are engaged. A pair of EDM cutters are used to cut a pair of slots which extend from one opening to the other. Upon completion of these slots, the sample, which remains clamped between the two clamps, is withdrawn and lowered back down the conduit to a remote collection point.

Abstract: A system and method of detecting air vortexing and coriolis effect vortex-created cavitation in a shutdown cooling system drain pump of a nuclear power plant during midloop operation where the plant includes a horizontal hot leg having a drain pipe connected from the lower region thereof to a drain pump which includes attaching transducers of a portable clamp-on ultrasonic flowmeter to the drain pipe to measure and detect flow-void-created disruptions in the flowmeter ultrasonic signal and providing a remote alarm triggered by the disrupted signal.

Abstract: An ultrasonic testing system can receive data from at least two ultrasonic transducers and process the data in parallel to each other. The testing system can compress the data by a fixed ratio by storing the value of the sample having the highest-amplitude out of a group of samples. The testing system can also provide threshold-based run-length encoding by compressing data by only storing samples which exceed a user-defined threshold value as well as a user-defined range of samples surrounding said samples. The ultrasonic testing system also provides a hardware gate for storing a peak amplitude and associated time-of-flight for a user-defined interval and a gate for storing the time-of-flight for the first excursion of the data through a user-defined threshold and interval. The operation of these gates or the storage of waveform data may be delayed by a constant delay or until the data exceeds a user-selectable threshold during a user-selectable time interval.

Abstract: A robot and associated control system, as well as a method of control, for servicing a heat exchanger having a substantially planar tube sheet which defines a multiplicity of laterally spaced tube openings of known shape, each of which is centered at a coordinate on a tube sheet coordinate system. A sensory system associated with the robot end effector and the associated digital processing system, includes a vision subsystem for generating an image of a portion of the tube sheet and generating a first signal commensurate with the spatial relationship of the tool to a selected tube opening. An optical subsystem is also provided, for projecting a structured light beam toward the tube sheet and receiving a reflected structured light pattern, indicative of how closely the tool is aligned with the target opening.

Abstract: A BWR emergency core cooling system suction strainer. The strainer comprises corrugated metal screen material formed of alternating ridges and furrows with flat chordal lands and flat side walls interconnecting the lands; and an elongated frame with arcuate end support portions shaped to accommodate the ridges and furrows. The flat side walls merge slightly toward one another in a substantially radially inwardly direction and diverge slightly away from one another in a substantially radially outwardly direction to permit release of debris from the screen surface while providing increased screening area for a given volume of strainer.

Abstract: In order to use up a stockpile of weapons-grade plutonium, the plutonium is converted into a mixed oxide (MOX) fuel form wherein it can be disposed in a plurality of different fuel assembly types. Depending on the equilibrium cycle that is required, a predetermined number of one or more of the fuel assembly types are selected and arranged in the core of the reactor in accordance with a selected loading schedule. Each of the fuel assemblies is designed to produce different combustion characteristics whereby the appropriate selection and disposition in the core enables the resulting equilibrium cycle to closely resemble that which is produced using urania fuel. The arrangement of the MOX rods and burnable absorber rods within each of the fuel assemblies, in combination with a selective control of the amount of plutonium which is contained in each of the MOX rods, is used to tailor the combustion characteristics of the assembly.

Abstract: A hand held insitu reactor vessel stud cleaner includes a right angle drill having a frame with an annular ring portion mounted thereon. An annular rotating plate assembly with a cylindrical brush holder or thread chase is concentrically mounted thereon and driven by a spur gear and ring gear combination or a belt and pulley combination. Vacuum structure is provided to remove corroded material loosened by the brushes or chase.

Abstract: In order to support a shroud against bending, shear, stress and torsion, straps are placed in strategic positions with respect to cracks or like types of weaknesses which have been detected, and fastened in place using a suitable fastening technique. Holes are formed using an EDM technique in cooperation with supports for an EDM placed on the straps, and bolt units which have an expanding portion are inserted into the holes, torqued and expanded in a manner which fastens the strap to the shroud. A temperature responsive bimetallic strain system which produces a clamping force, is created by forming the straps of a material which has a lower expansion coefficient than the shroud material. As the reactor heats, the expansion differential tensions the straps and produces a clamping force.

Abstract: A drain system for a shutdown cooling system of a pressurized water reactor type of a nuclear power plant (10) has an increased flow rate in the drain pipe (28) and drain pump (33). The hot leg (18) connected drain pipe has a vaned vortex breaker (30) mounted therein between its connection with the hot leg (18) lower region and the drain pump (33). This minimizes vortex-created cavitation in the drain pump thereby permitting the increased flow rate.

Abstract: In order to seal an electrical connector in a manner wherein mating of the connector components does not deteriorate environment sealing elements or require periodic maintenance, a GRAFOIL.RTM. type end seal is arranged to be abutted by a leading edge portion of one of a male plug member and a female receptacle members in a manner which establishes the sole hermetic seal for the connector.

Abstract: In order to support a shroud against bending, shear, stress and torsion, straps which are preferably formed of the same material as the shroud, are placed in strategic positions with respect to cracks or the like type of weaknesses which have been detected, and fastened in place using a suitable fastening technique. In the preferred embodiments of the invention holes are formed using an EDM technique and bolt units which have an expanding portion are inserted into the holes, torqued and expanded in a manner which fastens the strap to the shroud. Welding and the like type of fastening techniques are not excluded and may used alternatively or in combination with the bolting technique as required.

Abstract: In order to facilitate refueling operations, cables, which provide control and power linkages between control element drive mechanisms (CEDMS), and a terminal panel supported on a side wall of the reactor cavity, are disposed in a cylindrical extension of a cylindrical enclosure which encloses the CEDMS, with sufficient slack that they can be drawn out of the cylindrical extension through windows and supported on a drawbridge type of arrangement comprised of pivotal window tray type structures which are respectively hingedly connected to the cylindrical extension and either the wall or the terminal panel, and which span the gap between the cylindrical extension and the terminal panel when pivoted to their respective supporting positions.

Abstract: A probe inspects steam generator tubing for defects. The probe includes a transducer which generates a localized ultrasonic Lamb wave. The ultrasonic wave is transferred to the tubing by a coupling medium, such as water, that physically couples the transducer and the tubing. Defects in the tubing reflect the ultrasonic wave to the probe which detects the reflections. The results are then used to determine the length and depth of such defects as cracks, pitting, and thinning. The localized ultrasonic wave performs an inspection sensitive enough to detect ligaments between crack segments. This allows highly accurate predictions of tubing integrity and rupture strength.

Abstract: The work cell is divided into a plurality of calibration zones, and calibration is made with only one measured point in each zone. The calibration zones are set up such that the calibration error in each zone remains within an acceptable tolerance. Within each zone, calibration is preferably made according to a linear calibration algorithm. The method according to the invention includes the steps of storing a first database, of the coordinates of all the tube openings in the tube sheet coordinate system. Each coordinate of the first database is assigned to one of a plurality of calibration zones.

Abstract: A blind nut tool has spaced arms, one to extend on either side of a drywell head flange. The arms are mounted on a U-shaped channel member and the lower arm holds and retains a nut and washer pair on the underside of the flange as it is torqued on a threaded stud extending through the flange. The channel receives the stud and has a pin which engages a flat on the stud for storage of the tool.

Abstract: A method for generating a validated measurement of a process parameter at a point in time by using a plurality of individual sensor inputs from a scan of said sensors at said point in time. The sensor inputs from said scan are stored and a first validation pass is initiated by computing an initial average of all stored sensor inputs. Each sensor input is deviation checked by comparing each input including a preset tolerance against the initial average input. If the first deviation check is unsatisfactory, the sensor which produced the unsatisfactory input is flagged as suspect. It is then determined whether at least two of the inputs have not been flagged as suspect and are therefore considered good inputs. If two or more inputs are good, a second validation pass is initiated by computing a second average of all the good sensor inputs, and deviation checking the good inputs by comparing each good input including a present tolerance against the second average.

Abstract: In order to reduce the number of lifts which are required to remove the various equipment normally disposed above the reactor pressure vessel and to make way for refuelling or regular maintenance, the control rod element drive mechanisms are completely enclosed within a cylindrical enclosure which is attached to the head of the pressure vessel. The top of the cylindrical enclosure is closed with a cap-like member which acts as both a missile shield and a head area cable tray. The missile shield, the cylindrical enclosure, the control rod drive mechanisms and the pressure vessel head, are connected to form an integral unit which can be removed in a single lift. Cable trays are pivotally supported on a wall of a building to establish a bridge between the building and the head area cable array and to establish a connection with the control element drive mechanism cables. During lifting, the control element drive mechanism cables are disconnected and the pivotal bridge trays are swung out of the way.

Abstract: An omega seal (32) between a housing (24) having a circumferential omega lip (38) including a free end, and a reactor vessel nozzle (22) having a complimentary omega lip (40) including a free end. A semi-rigid, annular seat member (60) is placed within one of the lips, and the housing is positioned in vertical alignment with the nozzle so that the free end of the housing lip and the free end of the nozzle lip are juxtaposed, thereby forming an omega structure having a cavity (44) occupied by the seat member, a gap (42) between the free ends of the lips, and an outer surface (47,49) on either side of the gap. A semi-rigid ring (46) is positioned in conforming relation to the outside surface of the omega structure. A compressive force is applied and maintained on the exterior of the seal ring, thereby extruding a portion of the ring into the gap.