Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B37/00—Component parts or details of steam boilers
  • F22B37/002—Component parts or details of steam boilers specially adapted for nuclear steam generators, e.g. maintenance, repairing or inspecting equipment not otherwise provided for
  • F22B37/003—Maintenance, repairing or inspecting equipment positioned in or via the headers
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/88—Investigating the presence of flaws or contamination
  • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
  • G01N21/954—Inspecting the inner surface of hollow bodies, e.g. bores
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C17/00—Monitoring; Testing ; Maintaining
  • G21C17/017—Inspection or maintenance of pipe-lines or tubes in nuclear installations
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E30/00—Energy generation of nuclear origin
  • Y02E30/30—Nuclear fission reactors

Definitions

• the present invention relates to an end effector for a remote manipulator, and more particularly, to an end effector which enhances visual inspection of the end of a tube in a tube sheet of a nuclear steam generator.
• a nuclear steam generator has thousands of closely-spaced tubes affixed at an end of a tube sheet. As these tubes become worn, they may fail; consequently, they require routine servicing. This servicing usually involves repairing the tubes or simply plugging them.
• a robotic cantilever device which is commonly referred to as a manipulator.
• the manipulator Before any servicing takes place, the manipulator must be accurately placed under the tube. If a positioning error is made, there may be serious consequences. For example, a faulty tube could go unrepaired, while a neighboring satisfactory tube was plugged. This faulty tube could then leak radioactive material, which could force an unplanned shutdown of the nuclear steam generator.
• the end effectors attached to the manipulator were limited.
• a technician at a remote location, could see only one view of the tube end at a given time.
• the technician could only view the outer portion of the tube end; he could not simultaneously view both the outer and inner portions of the tube end. Because these views were not on his monitor simultaneously, it was difficult for him to verify the accuracy of servicing and the condition of the weld. Furthermore, it was difficult for the technician to check the work because he was forced to reposition the manipulator to obtain other views.
• an end effector illuminates the work surface of the tube end, and through a series of mirrors, provides a panoramic view of the tube end without repositioning the manipulator.
• the invention comprises a housing having an inside, an outside, a top, an opposed bottom, and an axis extending through the top and bottom.
• An illuminating means such as a fuse light, is mounted inside the housing.
• a light guide is secured inside the housing and adjacent to the illuminating means.
• An outer mirror is located at the top of the light guide and is adapted in size and shape to surround the tube end.
• An inner mirror is located at the top of the light guide and is supported on the housing axis.
• a camera is positioned within the housing and beneath the light guide.
• a transmitting means is electrically connected to the camera for sending tube image data to a monitor at a remote location.
• light travels from the light source into the light guide.
• the light guide redirects the light upward to the top of the housing.
• the outer and inner mirrors are adapted in size and shape such that light directed by the light guide to the top of the housing simultaneously reflects from the outer and inner mirrors onto the outer and inner portions of the tube end, respectively.
• the outer mirror has a frustroconical portion having a mirror surface turned inwardly toward the axis, for reflecting light from the outer portion of the tube end toward the camera.
• the inner mirror includes a frustroconical portion having a mirror surface turned outwardly from the axis, for reflecting light from the inner portion of the tube end toward the camera.
• the camera receives the light reflected by the tube end and generates tube image data.
• the transmitting means forwards the tube image data from the camera to the monitor at the remote location. At this remote location, a technician can verify that the tube was properly serviced by examining its weld and its heat affected zone. The technician sees three "lines-of-sight" on his remote monitor.
• One line- of-sight extends from the camera to the outer mirror and radially inward onto the outer portion of the tube.
• the second line-of-sight stretches directly from the camera to the bottom of the tube.
• the third line-of-sight extends from the camera to the inner mirror and radially outward onto the inner portion of the tube. Because of the positioning of the mirrors, the technician can see all views of the tube end without repositioning the manipulator.
• the technician at the remote location guides the manipulator to the next tube and repeats the above- mentioned process.
• FIG. 1 is a schematic view of a tube sheet region of a nuclear steam generator and a remote manipulator (which is known in the art) with an attached end effector, constructed in accordance with the present invention
• FIG. 2 is a side view of the end effector, also known as a visual inspection tool, affixed to the manipulator;
• FIG. 3 is a partial cross-sectional view of the inspection tool shown in Fig. 2, taken along line 3-3, showing the tool positioned inside a tube end;
• FIG. 4 is a top plan view of the inspection tool affixed to the manipulator;
• FIG. 5 is a partial cross-sectional view of a portion of the inspection tool - namely, a tube probe, an outer mirror, and a camera - showing the tube probe inserted into a tube end and three "lines-of-sight" extending between the tube end and the camera;
• FIG. 6 is a view of the three "lines-of-sight"
• FIG. 7 is a cross-sectional view of a plugged tube, taken along line 7-7 of FIG. 5, with the tool removed for clarity;
• FIG. 8 is a cross-sectional view of an outer mirror
• FIG. 9 a top view of the outer mirror
• FIG. 10 is a side view of a light guide; and FIG. 11 is a top view of the light guide supported within ths outer mirror.
• FIG. 1 shows a lower plenum region of a nuclear steam generator 12, having a transverse tube sheet 14 in which are affixed a multiplicity of tubes 16, some of which have been serviced.
• a support structure such as a stay column 18, provides a stable mounting structure for a temporary manipulator arm 20, which may be supported by a strut 22.
• the arm 20 carries an end effector 24, constructed in accordance with the present invention, for insertion into the open ends 26 of the tubes.
• FIG. 3 shows the invention in partial cross- section.
• the invention has a housing 28, which includes an inside portion 30, an outside portion 32, an open* top 34, an opposed bottom 36, and an axis 38 extending through the top and bottom.
• the housing 28 is preferably made of aluminum and is ideally black and anodized to reduce light reflections.
• a means for illuminating 40 the housing 28 and the vicinity of the tube end 26 is affixed to the inside 30 of the housing and at substantially the top 34 of the housing. Any illuminating means will suffice, such as a conventional twelve-volt fuse light.
• the fuse light is affixed to the housing by a fuse holder, or any suitable connecting means, 42. Additionally, a light bracket 44 secures the fuse holder to the housing 28.
• a light guide 46 such as one manufactured of transparent optics quality plastic stock, preferably that marketed under the trademark Lexan, is secured within the housing 28 at substantially the top 34 of the housing, adjacent to the illuminating means. In the preferred embodiment, the light guide is made of a solid piece of Lexan.
• the light guide 46 has a top 48, a bottom 50, a side or surface 52, and a idplane 56.
• the top 48 of the light guide 46 is adjacent the top 34 of the housing 28.
• the light guide is angled inwardly toward the axis 38 at substantially its midplane, as shown in FIGS. 2, 3.
• the light guide directs light from the illuminating means 40 to the top of the housing.
• An outer mirror 58 is secured to the top 48 of the light guide 46 and is adapted in size and shape to surround the tube end 26.
• the outer mirror has a cutaway portion 60 adjacent to the illuminating means 40, which allows light from the fuse light to pass to the light guide 46.
• the outer mirror further includes a frustroconical portion 62 having a mirror surface turned inwardly toward the axis 38 and extending slightly above the top 48 of the light guide.
• An inner mirror 64 located at the top of the light guide 46 and supported on the housing axis 38, is adapted in size and shape to enter and exit the tube end 26.
• a tube probe 66 is centered above the light guide 46.
• the tube probe 66 is adapted in size and shape to enter and exit the tube ends 26 of the steam generator 12.
• the tube probe consists of essentially three components: a pilot portion 68, the inner mirror 64, and a shaft 70.
• the substantially tubular pilot portion 68 at the top of the tube probe 66, guides the probe into the center of the tube end 26.
• the probe 66 has a rounded tip 72 to facilitate, entry into the tube end.
• the inner mirror 64 is secured at the probe bottom 74.
• the tube probe 66 is connected to the housing 28 by the shaft 70.
• the shaft attaches to the inner mirror bottom 76 and extends downwardly into the light guide 46 and is secured under the illuminating means 40.
• a camera means 78 Directly beneath the light guide 46 is a camera means 78, secured within the housing 28, for receiving light reflected by the tube end and generating tube image data.
• Any suitable camera means will suffice, such as the one manufactured and marketed by Toshiba, model number CCD Mod. #IK M30 A.
• the camera includes a lens 80 having a top 82 and bottom 84, wherein the top of the lens is spaced from the bottom 50 of the light guide 46.
• the camera also includes a focus ring 86 and a means 88 for focusing the camera.
• the camera is focused by a drive gear 90 in mesh with a driven gear 92, both of which are adjacent to the lens 80 of the camera, and both of which cooperate to move the lens in an axia,l direction toward and away from the stationary light guide.
• the drive gear and driven gear are remotely operated by a conventional twelve-volt D.C. motor 94.
• the drive gear 90 and driven gear 92 can be any suitable gears, such as those manufactured by W.M. Berg Inc. , Spur Gear model number PW48B40A, made of brass.
• the driving gear is connected to the motor by a shaft 96, as shown in FIG. 3.
• One thrust washer 98 such as the one manufactured by W.M.
• FIG. 3 A connector 106 for attaching the housing 28 to the manipulator is also shown in FIG. 3. Any suitable connecting means will suffice, such as the connector manufactured by Bendix, model number PT02A-8P.
• FIGS. 2, 4 show the effector 24 connected to the manipulator arm 20 in more detail.
• an elongated bracket 108 extending from the effector, is positioned above the arm of the manipulator.
• the bracket 108 and the arm 20 are interconnected by two cylindrical, rubber mountings 110, 112, such as those manufactured by Stock Drive Products, model number 10Z2-301A and secured in place by hex nuts 114, 116.
• each tube end such as 26, has three portions that are inspected: an inner portion 118, an outer portion 120, and a bottom portion 122.
• the tube probe 66 is inserted into a tube end 26 which may contain a plug 124.
• the outer mirror 58 surrounds the tube end, while the camera means 78 is positioned directly below the tube.
• the illuminating means 40 is turned on, light travels into the light guide 46.
• the light guide directs the light to the top 34 of the housing 28.
• the inner mirror 64 and the outer mirror 58 simultaneously reflect the light from the top of the housing onto the inner portion 118 and outer portion 120 of the tube end, respectively.
• the camera means 78 receives the light reflected by the tube end 26 and generates tube image data. This data is electronically transmitted, via cable 126, to a remote location, such as a monitor 128. (See FIGS. 3, 6. )
• This monitor 128 displays three lines-of-sight, as shown in FIGS. 5, 6.
• One line-of-sight 130 extends from the camera 78 to the outer mirror 58 and radially inward onto the outer portion 120 of the tube end.
• the second line-of-sight 132 stretches directly from the camera to the bottom 122 of the tube end.
• the third line-of-sight 134 extends from the camera to the inner mirror 64 and radially outward onto the inner portion 118 of the tube end.
• FIG. 7 shows, in detail, a weld 136 of tube end 26.
• This weld includes two metal sections 138, 140 separated by a plug 142.
• a heat affected zone 144 is also shown.
• the technician at his remote location, must inspect this heat affected zone 144 to ensure that it meets industry standards. With this end effector, the technician sees a panoramic view of this weld without repositioning the manipulator.
• FIGS. 8, 9, 10, 11 show one available set of outer mirror 58' and light guide 46' respectively.
• the frustroconical reflecting surface 62' of the mirror is supported above a pedestal portion 146 by three legs 148 spaced one hundred twenty degrees apart.
• the light guide 46' fits within the legs, so as to be supported by the pedestal portion 146 and span the space 60' between the reflecting surface 62' and the pedestal portions 146.
• the pedestal portion 146 is supported by, or forms part of, the housing 34 shown in FIG. 3.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Chemical & Material Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Thermal Sciences (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• Mechanical Engineering (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Plasma & Fusion (AREA)
• Instruments For Viewing The Inside Of Hollow Bodies (AREA)
• Monitoring And Testing Of Nuclear Reactors (AREA)

Priority Applications (1)

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Cited By (4)

Citations (4)

• 1993
  • 1993-10-07 WO PCT/US1993/009566 patent/WO1994024675A1/en not_active Ceased
  • 1993-10-07 AU AU51709/93A patent/AU5170993A/en not_active Abandoned
  • 1993-10-13 TW TW082108491A patent/TW240315B/zh active

Patent Citations (4)

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