EP0171717B1 - Process and apparatus for electropolishing the internal surfaces of u-shaped heat exchanger pipes - Google Patents

Process and apparatus for electropolishing the internal surfaces of u-shaped heat exchanger pipes Download PDF

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Publication number
EP0171717B1
EP0171717B1 EP85109706A EP85109706A EP0171717B1 EP 0171717 B1 EP0171717 B1 EP 0171717B1 EP 85109706 A EP85109706 A EP 85109706A EP 85109706 A EP85109706 A EP 85109706A EP 0171717 B1 EP0171717 B1 EP 0171717B1
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EP
European Patent Office
Prior art keywords
heat exchanger
electrolyte
tube
electrode
manipulator
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP85109706A
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German (de)
French (fr)
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EP0171717A1 (en
Inventor
Ludwig Dipl.-Ing. Voggenthaler (Fh)
Hermann Dipl.-Ing. Operschall
Jakob Dipl.-Ing. Weber (Fh)
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Siemens AG
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Siemens AG
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Publication date
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Publication of EP0171717A1 publication Critical patent/EP0171717A1/en
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F7/00—Constructional parts, or assemblies thereof, of cells for electrolytic removal of material from objects; Servicing or operating
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00—Electrolytic etching or polishing
    • C25F3/16—Polishing
    • 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
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/001—Decontamination of contaminated objects, apparatus, clothes, food; Preventing contamination thereof
    • G21F9/002—Decontamination of the surface of objects with chemical or electrochemical processes
    • G21F9/004—Decontamination of the surface of objects with chemical or electrochemical processes of metallic surfaces

Definitions

  • the invention relates to a method and a device for electropolishing the inner surface of U-shaped heat exchanger tubes with an electrode connected to the negative pole of a DC voltage source, which can be inserted into the heat exchanger tube and pulled out again via a pulling element, and with a pump connected to an electrolyte container for the Feeding the electrolyte.
  • a method and a device for cleaning the inner walls of metallic line systems by electropolishing with the aid of moving electrodes is already known from DE-A-3 136 187.
  • the diameter of the electrode which is matched to the inside diameter of the line system to be cleaned, is fastened to the end of a hose through which electrolyte liquid is pumped into the pipeline under high pressure.
  • the head of this electrode is mushroom-shaped.
  • the electrolyte is deflected by approx. 145 ° and sprayed against the inner wall of the tube at an angle backwards through spray nozzles. This electrode is drawn deeper into the tube by the recoil of the electrolyte at the spray nozzles.
  • the known electrode carries several axially spaced disks of insulating material, through which it is held at a uniform distance from the inner wall of the pipeline. It is a peculiarity of this device for cleaning the inner walls of metallic power systems that the recoil of the electrolyte is not always sufficient to move the electrode around pipe bends. The area of application for vertical pipe sections is very limited. In addition, the cleaning of radioactive contaminated pipelines with this method is associated with a noticeable radiation exposure of the examination personnel, since the electrode has to be threaded into each individual pipeline by hand.
  • the invention has for its object to develop a method and a device for cleaning the inner surface of pipelines and to design so that the vertically arranged U-shaped heat exchanger tubes of the steam generator can be decontaminated by nuclear power plants.
  • the handling of the device should be associated with a minimum of radiation exposure for the operating personnel.
  • the electrolyte liquid is pumped into the heat exchanger tube in the same direction in which the electrode is pulled out of the heat exchanger tube, it is ensured that an electrode once inserted can also be pulled out again.
  • a pusher device with motor-driven transport rollers, the pusher element being clamped between itself, enables a controlled displacement of the electrode, which does not overload the pusher cable and its fastening in the electrode. It also enables the operating personnel to be protected from radiation during decontamination.
  • FIG. 1 shows a steam generator 1, as is usual in nuclear power plants, in order to separate the primary circuit from the secondary circuit, in a simplified representation.
  • the tube sheet 2 of the steam generator 1 three heat exchanger tubes 3, 4, 5 are indicated. The remaining heat exchanger tubes have been omitted for the sake of clarity.
  • the device 6 according to the invention for electropolishing the inner surface of the heat exchanger tubes in the connected state is shown on this steam generator 1.
  • This device 6 essentially contains an electrolyte container 7, a pump 8 for the electrolyte, and an electrolyte feed hose 9, which is guided through a manhole 10 into the chamber 11 of the bottom cap 12 of the steam generator, which chamber is on the right in FIG is attached to two heat exchanger tubes 4, 5 attached manipulator 14 in front of a heat exchanger tube 3 adapter 15.
  • this device 6 includes a guide hose 16 which leads through another manhole 17 into the chamber 18 of the bottom calotte 12 of the steam generator 1, which chamber is on the left in FIG the other end of the same heat exchanger tube 3 is brought into contact with the adapter 21.
  • This guide hose 16 is fastened to a sealing device 22 with its end located outside the steam generator.
  • a push cable 23 is guided through this sealing device and carries a flexible electrode 24 at its end located in the guide hose 16 or heat exchanger tube 3.
  • the device 6 for electropolishing the inner surface of the heat exchanger tubes also comprises an electrolyte supply system 27 connected to the electrolyte container 7 with a circulation pump 28, a heat exchanger 29 and a filter 30 and a direct voltage source 31 for the power supply of the electrode 24.
  • FIG. 2 shows the structure of the electrode 24 shown in section. It consists of a steel cable 32 on which springs 33 to 37 and spacers 38 to 41 are alternately threaded from insulating material and in which the first and last springs 33, 37 are each attached to one Support the clamping sleeve 42, 43 attached to the steel cable.
  • the front clamping sleeve 43 in the insertion direction carries an insertion cone 44, while the rear clamping sleeve 42 is connected to the push cable 23 via a union nut 45.
  • This push cable consists of a smooth copper cable 47 covered on the outside with plastic 46, in particular polytetrafluoroethylene.
  • the structure of the sealing device 22 can be seen from the enlarged illustration in FIG. 3.
  • This sealing device consists of a tube piece 48 in which rings 49 to 53 with a larger clear width and rings 54 to 58 with a smaller clear width are alternately threaded, the inner diameter of the rings with the smaller clear width roughly corresponding to the outer diameter of the push cable 23.
  • Elastic sealing disks 59 to 65 are clamped between these rings, the inner diameter of which is somewhat smaller than the diameter of the push cable 23 passed through them.
  • the two end faces of the sealing device 22 are formed by two disks 66, 67, in which the first 66 has a bore has a clear width that corresponds to the guide tube 16. It is provided with a clamping device 68 for fastening the guide hose 21.
  • the disk 67 is provided with a bore which is adapted to the outer diameter of the push cable 23.
  • the chambers of the sealing device formed by the disks with the larger inner diameter are provided with outlet connections 69 to 72 and a compressed air connection 73, which open into the electrolyte container 7.
  • a feed device 25 is fastened, which carries a plurality of motor-driven drive rollers 74 to 78 pressed onto the push cable 23.
  • FIG. 4 shows a schematically drawn section of the tube sheet 80 of a steam generator with the various heat exchanger tubes 81 to 87 and an adapter 89 pressed onto the tube sheet by the extension arm 88 of a manipulator (not shown further here).
  • the adapter 89 consists of a collecting trough 90 the four hose connections 91 to 94 in the exemplary embodiment are carried out at a distance which corresponds to the distance between the heat exchanger tubes 81 to 87 in the tube sheet 80.
  • These hose connections 91 to 94 are flanged at their end facing the tube sheet and each have a soft sealing ring 95 to 98 on the flange periphery, with which they bear against the weld seams with which the heat exchanger tubes are welded in the tube sheet 80.
  • hose connections 91 to 94 have the same inner diameter as the heat exchanger tubes 81 to 87. They carry the guide or electrolyte supply hoses 99 to 102 at their ends facing away from the heat exchanger tubes.
  • the collecting trough 90 itself has an edge that extends almost below the tube plate 80 103 and has an outlet connection 104 which is connected to the electrolyte container 7 via an auxiliary hose 105.
  • the collecting trough 90 is connected in the middle to a clutch disk 106 of the extension arm 88 of the manipulator.
  • the adapter carries four hose connections 91 to 94 arranged in series one behind the other, two hose connections each being arranged next to one another at the heat exchanger tube spacing.
  • the bottom cap 12 of the Steam generator 1 each a known manipulator 14, 20 for remote-controlled inspection of the heat exchanger tubes 3, 4, 5 are used.
  • An adapter 15, 21 with a connected guide tube 16 or electrolyte feed tube 9 is then plugged onto the extension arms 13, 19 of each of the two manipulators.
  • the work associated with significant radiation exposure in the bottom cap 12 of the steam generator 1 is complete, apart from the subsequent dismantling of the adapters and manipulators.
  • the electrode 24 with the push cable 23 assigned to it is then inserted into the guide hose 16 and the guide hose 16 is coupled to the front end of the sealing device 22.
  • the electrolyte supply hose 9 can then be connected to the electrolyte pump 8. Now the operating personnel can completely move away from the radiation area because all further work can be carried out remotely.
  • the adapters 15, 21 coupled to their extension arms can be positioned in relation to the individual heat exchanger tubes guided through the tube plate 2 such that the hose connections are exactly aligned with the mouths of the heat exchanger tubes in the two chambers 11, 18 of the base cap 12 of the steam generator 1 are pressed.
  • the soft sealing rings (see FIG. 4) at the flange-like ends of the hose connections are pressed against the weld seam which connects the respective heat exchanger tube to the tube sheet 2.
  • pressurized gas or air can be applied, as is not shown here. If this is the case, the feed device 25 is switched on.
  • the push cable 23 is now moved through the motor-driven rollers 74 to 78 together with the electrode 24 fastened to its end through the guide tube 16, the adapter 21 into the respective heat exchanger tube 3.
  • the electrode 24 is retracted as far as the heat exchanger tube is to be decontaminated.
  • the flexibility of the electrode enables the passage through narrow heat exchanger tube bends.
  • the dry insertion of the electrode against the later flow direction of the electrolyte ensures that the electrode can be pulled out again in the event of jamming in the heat exchanger tube with the push cable and supported by the flow of the electrolyte.
  • the pump 8 for the electrolyte is switched on and the electrolyte is pumped into the heat exchanger tube 3 via the electrolyte supply hose 9. This flows through the heat exchanger tube past the electrode 24 and between the push cable 23 and the guide hose 16 into the first chamber of the sealing device 22. From this chamber it flows back through the first hose nozzle 69 into the electrolyte container 7.
  • the DC voltage source 31 is switched on and the electrode 24 is pulled out of the heat exchanger tube again at a predetermined speed via the feed device 25. Due to the current flow between the electrode 24 and the heat exchanger tube 3 connected to the other pole of the direct voltage source 31, the impurities on the inner surface of the heat exchanger tube and protruding bumps in the tube are preferably removed. The removed particles reach the electrolyte tank with the electrolyte flowing back. The flow pressure of the electrolyte supports the pull on the push cable 23. The electrolyte residues entrained by the push cable from the first chamber into the second chamber of the sealing device drip in it or are stripped off when it passes through the sealing disk 60. Electrolyte residues entrained in the third chamber are blown back into the third chamber by the counter-flowing compressed air when they pass through the sealing disk 62 separating the third chamber from the fourth chamber and drip off there.
  • a portion of the electrolyte is continuously pumped out of the electrolyte tank 7 by the circulating pump 28 of the electrolyte supply system 27, passed over a heat exchanger for cooling and over a filter for cleaning.
  • the cleaned and cooled electrolyte liquid then returns to the electrolyte container 7.
  • the temperature in the electrolyte container 7 is kept constant and the electrolyte supply system 27 can continue to run, even if the pump 8, which otherwise pumps the electrolyte into the electrolyte supply hose 9, when adjusting the Adapter is switched off.
  • the voltage source 31 and the pusher device 25 can be switched off.
  • compressed air is blown into the electrolyte feed hose 9 and the remaining electrolyte in the electrolyte feed hose, in the heat exchanger tube 3 and in the guide hose 16 is blown back into the electrolyte container 7.
  • the adapters 15, 21 can be positioned in front of a further heat exchanger tube.
  • the exact position of the two adapters and the tightness are then checked by introducing compressed gas, and the exact position of the two adapters and the tightness can be checked by introducing pressurized gas, and the next can be switched on by simply switching on the feed device 25, the pump 8, and the DC voltage source 31
  • Heat exchanger tube are electropolished without anyone having to enter one of the two chambers 11, 18 of the bottom cap 12 of the steam generator 1.
  • the radioactive contaminants that have passed into the electrolyte during electropolishing are rinsed with the electrolyte into the electrolyte container and ultimately reach the filter 30 via the filter circuit.
  • the activity of the electrolyte and its temperature can be reduced to one low Level can be maintained. Finally, only the filter cake needs to be disposed of.
  • This device has the great advantage that the length of time that the operating personnel can stay in the radiating area, in particular in the two chambers in the bottom cap of the steam generator, can be limited to the times required to use the manipulators and the adapters on the cantilever arms 13 , 19, 88 to fix the manipulators 14, 20 and later to dismantle them once the decompression work has ended. All other work can be carried out remotely.
  • adapters 89 with a plurality of hose connections 91 to 94, a plurality of steam generator tubes 81, 82, 85, 86 can be electropolished at the same time and the total time in which decontamination is carried out can be greatly reduced.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Materials Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Food Science & Technology (AREA)
  • Life Sciences & Earth Sciences (AREA)
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Description

Die Erfindung bezieht sich auf ein Verfahren und eine Vorrichtung zum Elektropolieren der Innenoberfläche von U-förmigen Wärmetauscherrohren mit einer an den negativen Pol einer Gleichspannungsquelle angeschlossenen, in das Wärmetauscherrohr einschiebbaren und über ein Zugorgan wieder herausziehbaren Elektrode und mit einer an einem Elektrolytbehälter angeschlossenen Pumpe für die Zuführung des Elektrolyten.The invention relates to a method and a device for electropolishing the inner surface of U-shaped heat exchanger tubes with an electrode connected to the negative pole of a DC voltage source, which can be inserted into the heat exchanger tube and pulled out again via a pulling element, and with a pump connected to an electrolyte container for the Feeding the electrolyte.

Ein Verfahren und eine Vorrichtung zur Reinigung der Innenwände von metallischen Leitungssystemen durch Elektropolieren mit Hilfe bewegter Elektroden ist schon durch die DE-A-3 136 187 bekannt. Bei diesem Verfahren ist die in ihrem Durchmesser an den Innendurchmesser des zu reinigenden Leitungssystems angepaßte Elektrode am Ende eines Schlauches befestigt, durch den Elektrolytflüssigkeit unter hohem Druck in die Rohrleitung gepumpt wird. Der Kopf dieser Elektrode ist pilzförmig ausgebildet. In ihr wird der Elektrolyt um ca. 145° umgelenkt und über Sprühdüsen schräg nach rückwärts gerichtet gegen die Rohrinnenwand gespritzt. Diese Elektrode wird durch den Rückstoß des Elektrolyten an den Sprühdüsen tiefer in das Rohr hineingezogen. Die bekannte Elektrode trägt mehrere im axialen Abstand voneinander angeordnete Scheiben aus Isoliermaterial, durch die sie in gleichmäßigen Abstand von der Innenwand der Rohrleitung gehalten wird. Es ist eine Eigenart dieser Vorrichtung zur Reinigung der Innenwände von metallischen Leistungssystemen, daß der Rückstoß des Elektrolyten nicht immer ausreicht, die Elektrode um Rohrbögen zu befördern. Bei vertikalen Rohrleitungsabschnitten ist der Einsatzbereich sehr begrenzt. Darüber hinaus ist die Reinigung von radioaktiv kontaminierten Rohrleitungen mit diesem Verfahren mit einer merklichen Strahlenbelastung des Untersuchungspersonals verbunden, da die Elektrode von Hand in jede einzelne Rohrleitung eingefädelt werden muß.A method and a device for cleaning the inner walls of metallic line systems by electropolishing with the aid of moving electrodes is already known from DE-A-3 136 187. In this method, the diameter of the electrode, which is matched to the inside diameter of the line system to be cleaned, is fastened to the end of a hose through which electrolyte liquid is pumped into the pipeline under high pressure. The head of this electrode is mushroom-shaped. In it, the electrolyte is deflected by approx. 145 ° and sprayed against the inner wall of the tube at an angle backwards through spray nozzles. This electrode is drawn deeper into the tube by the recoil of the electrolyte at the spray nozzles. The known electrode carries several axially spaced disks of insulating material, through which it is held at a uniform distance from the inner wall of the pipeline. It is a peculiarity of this device for cleaning the inner walls of metallic power systems that the recoil of the electrolyte is not always sufficient to move the electrode around pipe bends. The area of application for vertical pipe sections is very limited. In addition, the cleaning of radioactive contaminated pipelines with this method is associated with a noticeable radiation exposure of the examination personnel, since the electrode has to be threaded into each individual pipeline by hand.

Der Erfindung liegt die Aufgabe zugrunde ein Verfahren und eine Vorrichtung zur Reinigung der Innenoberfläche von Rohrleitungen zu entwickeln und so auszubilden, daß damit auch die senkrecht angeordneten U-förmigen Wärmetauscherrohre der Dampferzeuger von Kernkraftwerken dekontaminiert werden können. Darüber hinaus sollte die Handhabung der Vorrichtung mit einem Minimum an Strahlen belastung für das Bedienungspersonal verbunden sein.The invention has for its object to develop a method and a device for cleaning the inner surface of pipelines and to design so that the vertically arranged U-shaped heat exchanger tubes of the steam generator can be decontaminated by nuclear power plants. In addition, the handling of the device should be associated with a minimum of radiation exposure for the operating personnel.

Die gestellte Aufgabe wird erfindungsgemäß durch die im Kennzeichen der Ansprüche 1 und 4 angegebenen Merkmale gelöst. Vorteilhafte Weiterbildungen sind in den Ansprüchen 2, 3 und 5 bis 14 beschrieben.The object is achieved according to the invention by the features specified in the characterizing part of claims 1 and 4. Advantageous further developments are described in claims 2, 3 and 5 to 14.

Durch die Verwendung von zwei gleichartigen, für sich bekannten, in der DE-A-3 029 811 offenbarten, Manipulatoren zur fernbedienbaren Inspektion von Wärmetauscherrohren wird es möglich, die Elektode der Elektropoliereinrichtung ferngesteuert und mit stark verminderter Strahlenbelastung für das Bedienungspersonal an die einzelnen Wärmetauscherrohre eines Dampferzeugers anzuschließen. Dabei kann infolge der Führung der Elektrode im Schlauch für die Zuführung bzw. für die Ableitung des Elektrolyten die unmittelbare Einfädlung der Elektrode in ein Wärmetauscherrohr vermieden werden und braucht es stattdessen über den Manipulator lediglich eine Positionierung eines mit einem Schlauchanschluß versehenen Adapters zum Wärmetauscherrohr vorgenommen zu werden.The use of two similar manipulators, known per se and disclosed in DE-A-3 029 811, for the remote-controlled inspection of heat exchanger tubes makes it possible to remotely control the electrode of the electropolishing device and to reduce the radiation exposure for the operating personnel to the individual heat exchanger tubes Steam generator to connect. As a result of the guidance of the electrode in the hose for supplying or discharging the electrolyte, the direct threading of the electrode into a heat exchanger tube can be avoided and, instead, the manipulator only has to be used to position an adapter provided with a hose connection to the heat exchanger tube .

Die Verwendung eines massiven Schubkabels ermöglicht es, relativ große Schub- und Zugkräfte auf die Elektrode zu übertragen, ohne hierzu den zusätzlichen Schub der Strömung des Elektrolyten in Anspruch zu nehmen. Durch das Elektropolieren während des Herausziehens der Elektrode läßt sich durch Regulierung der Ziehgeschwindigkeit und des Stromes die Abtragmenge genau einstellen.The use of a solid push cable makes it possible to transmit relatively large push and pull forces to the electrode without taking the additional push of the flow of the electrolyte. By electropolishing while the electrode is being pulled out, the removal rate can be precisely adjusted by regulating the pulling speed and the current.

Wird darüber hinaus die Elektrolytflüssigkeit in der gleichen Richtung ins Wärmetauscherrohr gepumpt in der die Elektrode aus dem Wärmetauscherrohr herausgezogen wird, so wird sichergestellt, daß eine einmal eingeschobene Elektrode auch wieder herausgezogen werden kann. Eine Schubvorrichtung mit motorisch angetriebenen, das Schuborgan zwischen sich einklemmenden Transportrollen ermöglicht eine kontrollierte, das Schubkabel und seine Befestigung in der Elektrode nicht überlastende Verschiebung der Elektrode. Außerdem ermöglicht es dem Bedienungspersonal, sich während des Dekontaminierbetriebs strahlengeschützt aufzuhalten.If, in addition, the electrolyte liquid is pumped into the heat exchanger tube in the same direction in which the electrode is pulled out of the heat exchanger tube, it is ensured that an electrode once inserted can also be pulled out again. A pusher device with motor-driven transport rollers, the pusher element being clamped between itself, enables a controlled displacement of the electrode, which does not overload the pusher cable and its fastening in the electrode. It also enables the operating personnel to be protected from radiation during decontamination.

Die Verwendung eines gemeinsamen Elektrolytbehälters für die Umspülung der Elektrode und für die Speisung des Filterkreislaufs für den Elektrolyten macht den Betrieb des letzteren von der Speisung des Wärmetauscherrohres unabhängig und erlaubt es, mit relativ geringen Elektrolytmengen auszukommen.The use of a common electrolyte container for rinsing the electrode and for feeding the filter circuit for the electrolyte makes the operation of the latter independent of the feeding of the heat exchanger tube and allows the use of relatively small amounts of electrolyte.

Schließlich können durch die Verwendung von Adaptern mit mehreren Schlauchanschlüssen mehrere Dampferzeugerrohre gleichzeitig elektropoliert werden. Dies verkürzt sowohl die Arbeitszeit am Dampferzeuger und indirekt auch die Strahlenbelastung des Bedienungspersonals.Finally, by using adapters with several hose connections, several steam generator tubes can be electropolished at the same time. This shortens both the working time on the steam generator and indirectly the radiation exposure of the operating personnel.

Weitere Einzelheiten der Erfindung werden anhand eines in den Figuren dargestellten Ausführungsbeispiels erläutert. Es zeigen:

  • FIG 1 eine vereinfachte schematische Übersicht des Aufbaus einer erfindungsgemäßen Vorrichtung zum Elektropolieren der Innenoberfläche U-förmiger Wärmetauscherrohre im Einsatz am Dampferzeuger eines Kernkraftwerks,
  • FIG 2 eine vergrößerte Darstellung eines in ein Wärmetauscherrohr eingeführten Elektrode mit dem angeschlossenen Schubkabel und
  • FIG 3 eine vereinfachte, schematische Ansicht einer Dichteinheit mit dem angeschlossenen Elektrolytbehälter,
  • FIG 4 eine vereinfachte, schematische Darstellung eines anderen am Rohrboden eines Dampferzeugers mit Hilfe eines Auslegers eines Manipulators zur Anlage gebrachten Adapters.
Further details of the invention are explained with reference to an embodiment shown in the figures. Show it:
  • 1 shows a simplified schematic overview of the structure of a device according to the invention for electropolishing the inner surface of U-shaped heat exchanger tubes in use on the steam generator of a nuclear power plant,
  • 2 shows an enlarged view of an electrode inserted into a heat exchanger tube with the connected push cable and
  • 3 shows a simplified, schematic view of a sealing unit with the connected electrolyte container,
  • 4 shows a simplified, schematic representation of another on the tube sheet of a steam generator with the help of an adapter of a manipulator.

Die FIG 1 zeigt einen Dampferzeuger 1 wie er in Kernkraftwerken üblich ist, um den Primärkreislauf vom Sekundärkreislauf zu trennen, in vereinfachter Darstellung. Im Rohrboden 2 des Dampferzeugers 1 sind drei Wärmetauscherrohre 3, 4, 5 angedeutet. Die übrigen Wärmetauscherrohre sind der Übersicht halber fortgelassen worden. An diesem Dampferzeuger 1 ist die erfindungsgemäße Vorrichtung 6 zum Elektropolieren der Innenoberfläche der Wärmetauscherrohre im angeschlossenen Zustand gezeigt. Diese Vorrichtung 6 beinhaltet im wesentlichen einen Elektrolytbehälter 7, eine Pumpe 8 für den Elektrolyten, einen Elektrolytzuführschlauch 9, der durch ein Mannloch 10 hindurch in die in der Figur 1 rechten Kammer 11 der Bodenkalotte 12 des Dampferzeugers geführt und dort an einem vom Auslegerarm 13 eines an zwei Wärmetauscherrohren 4, 5 befestigten Manipulators 14 vor einem Wärmetauscherrohr 3 zur Anlage gebrachten Adapter 15 angeschlossen ist. Außerdem beinhaltet diese Vorrichtung 6 einen Führungsschlauch 16, der durch ein anderes Mannloch 17 in die in der Figur 1 linken Kammer 18 der Bodenkalotte 12 des Dampferzeugers 1 führt und dort an einem vom Auslegerarm 19 eines an zwei Wärmetauscherrohren 4, 5 befestigten weiteren Manipulators 29 vor dem anderen Ende desselben Wärmetauscherrohrs 3 zur Anlage gebrachten Adapter 21 angeschlossen ist. Dieser Führungsschlauch 16 ist mit seinem außerhalb des Dampferzeugers befindlichen Ende an einer Dichtvorrichtung 22 befestigt. Durch diese Dichtvorrichtung ist ein Schubkabel 23 hindurchgeführt, das an seinem im Führungsschlauch 16 oder Wärmetauscherrohr 3 befindlichen Ende eine flexible Elektrode 24 trägt.1 shows a steam generator 1, as is usual in nuclear power plants, in order to separate the primary circuit from the secondary circuit, in a simplified representation. In the tube sheet 2 of the steam generator 1, three heat exchanger tubes 3, 4, 5 are indicated. The remaining heat exchanger tubes have been omitted for the sake of clarity. The device 6 according to the invention for electropolishing the inner surface of the heat exchanger tubes in the connected state is shown on this steam generator 1. This device 6 essentially contains an electrolyte container 7, a pump 8 for the electrolyte, and an electrolyte feed hose 9, which is guided through a manhole 10 into the chamber 11 of the bottom cap 12 of the steam generator, which chamber is on the right in FIG is attached to two heat exchanger tubes 4, 5 attached manipulator 14 in front of a heat exchanger tube 3 adapter 15. In addition, this device 6 includes a guide hose 16 which leads through another manhole 17 into the chamber 18 of the bottom calotte 12 of the steam generator 1, which chamber is on the left in FIG the other end of the same heat exchanger tube 3 is brought into contact with the adapter 21. This guide hose 16 is fastened to a sealing device 22 with its end located outside the steam generator. A push cable 23 is guided through this sealing device and carries a flexible electrode 24 at its end located in the guide hose 16 or heat exchanger tube 3.

An der Dichtvorrichtung 22, die am Elektrolytbehälter 7 angeschlossen ist, ist eine Vorschubeinrichtung 25 mit einer Aufwickeltrommel 26 für das Schubkabel befestigt. Die Vorrichtung 6 zum Elektropolieren der Innenoberfläche der Wärmetauscherrohre umfaßt außerdem ein am Elektrolytbehälter 7 angeschlossenes Elektrolytversorgungssystem 27 mit einer Umwälzpumpe 28, einem Wärmetauscher 29 und einem Filter 30 sowie eine Gleichspannungsquelle 31 fur die Stromversorgung der Elektrode 24.On the sealing device 22, which is connected to the electrolyte container 7, a feed device 25 is fastened with a winding drum 26 for the push cable. The device 6 for electropolishing the inner surface of the heat exchanger tubes also comprises an electrolyte supply system 27 connected to the electrolyte container 7 with a circulation pump 28, a heat exchanger 29 and a filter 30 and a direct voltage source 31 for the power supply of the electrode 24.

Die FIG 2 zeigt den Aufbau der geschnitten dargestellten Elektrode 24. Sie besteht aus einem Stahlseil 32, auf dem abwechselnd Federn 33 bis 37 und Abstandshalter 38 bis 41 aus Isoliermaterial aufgefädelt sind und bei dem sich die erste und letzte Feder 33, 37 an je einer auf dem Stahlseil aufgebrachten Klemmhülse 42, 43 abstützen. Die in Einführrichtung vordere Klemmhülse 43 trägt einen Einführkonus 44, während die hintere Klemmhülse 42 über eine Überwurfmutter 45 mit dem Schubkabel 23 verbunden ist. Dieses Schubkabel besteht aus einem glatten, außen mit Kunstoff 46, insbesondere Polytetrafluorethylen, überzogenen Kupferkabel 47.2 shows the structure of the electrode 24 shown in section. It consists of a steel cable 32 on which springs 33 to 37 and spacers 38 to 41 are alternately threaded from insulating material and in which the first and last springs 33, 37 are each attached to one Support the clamping sleeve 42, 43 attached to the steel cable. The front clamping sleeve 43 in the insertion direction carries an insertion cone 44, while the rear clamping sleeve 42 is connected to the push cable 23 via a union nut 45. This push cable consists of a smooth copper cable 47 covered on the outside with plastic 46, in particular polytetrafluoroethylene.

Der Aufbau der Dichtvorrichtung 22 ist der vergrößerten Darstellung der FIG 3 zu entnehmen. Diese Dichtvorrichtung besteht aus einem Rohrstück 48, in dem abwechselnd Ringe 49 bis 53 mit grösserer lichter Weite und Ringe 54 bis 58 mit geringerer lichter Weite aufgefädelt sind, wobei der Innendurchmesser der Ringe mit der geringeren lichten Weite in etwa dem Außendurchmesser des Schubkabels 23 entspricht. Zwischen diesen Ringen sind elastische Dichtscheiben 59 bis 65 eingespannt, deren innerer Durchmesser etwas kleiner ist als der Durchmesser des durch sie hindurchgeführten Schubkabels 23. Die beiden Stirnseiten der Dichtvorrichtung 22 werden durch zwei Scheiben 66, 67 gebildet, bei denen die erste 66 eine Bohrung mit einer lichten Weite besitzt, die dem Führungsschlauch 16 entspricht. Sie ist mit einer Klemmvorrichtung 68 zur Befestigung des Führungsschlauches 21 versehen. An dem gegenüberliegenden Ende ist die Scheibe 67 mit einer Bohrung versehen, die dem Außendurchmesser des Schubkabels 23 angepaßt ist. Die durch die Scheiben mit dem größeren Innendurchmesser gebildeten Kammern der Dichtvorrichtung sind mit Auslaufstutzen 69 bis 72 und einem Druckluftstutzen 73 versehen, die in den Elektrolytbehälter 7 münden. An der dem Führungsschlauch 16 abgewandten Seite der Dichtvorrichtung 22 ist eine Vorschubeinrichtung 25 befestigt, die mehrere motorisch angetriebene, am Schubkabel 23 angepreßte Antriebsrollen 74 bis 78 trägt. Hinter diesen ist eine ebenfalls motorisch angetriebene Aufwickeltrommel 26 für das Schubkabel 23 vorgesehen.The structure of the sealing device 22 can be seen from the enlarged illustration in FIG. 3. This sealing device consists of a tube piece 48 in which rings 49 to 53 with a larger clear width and rings 54 to 58 with a smaller clear width are alternately threaded, the inner diameter of the rings with the smaller clear width roughly corresponding to the outer diameter of the push cable 23. Elastic sealing disks 59 to 65 are clamped between these rings, the inner diameter of which is somewhat smaller than the diameter of the push cable 23 passed through them. The two end faces of the sealing device 22 are formed by two disks 66, 67, in which the first 66 has a bore has a clear width that corresponds to the guide tube 16. It is provided with a clamping device 68 for fastening the guide hose 21. At the opposite end, the disk 67 is provided with a bore which is adapted to the outer diameter of the push cable 23. The chambers of the sealing device formed by the disks with the larger inner diameter are provided with outlet connections 69 to 72 and a compressed air connection 73, which open into the electrolyte container 7. On the side of the sealing device 22 facing away from the guide hose 16, a feed device 25 is fastened, which carries a plurality of motor-driven drive rollers 74 to 78 pressed onto the push cable 23. A winding drum 26 for the push cable 23, which is also motor-driven, is provided behind these.

Die FIG 4 zeigt einen schematisch gezeichneten Ausschnitt des Rohrbodens 80 eines Dampferzeugers mit den verschiedenen Wärmetauscherrohren 81 bis 87 und einen am Rohrboden, von dem Auslegearm 88 eines hier nicht weiter dargestellten Manipulators, angepreßten Adapter 89. Der Adapter 89 besteht aus einer Auffangwanne 90, durch die im Ausführungsbeispiel vier Schlauchanschlüsse 91 bis 94 in einem Abstand durchgeführt sind, der dem Abstand der Wärmetauscherrohre 81 bis 87 im Rohrboden 80 entspricht. Diese Schlauchanschlüsse 91 bis 94 sind an ihren, dem Rohrboden zugewandten Ende flanschartig erweitert und tragen am Flanschumfang je einen weichen Dichtungsring 95 bis 98, mit dem sie an den Schweißnähten, mit denen die Wärmetauscherrohre im Rohrboden 80 verschweißt sind, anliegen. Diese Schlauchanschlüsse 91 bis 94 haben den gleichen Innendurchmesser wie die Wärmetauscherrohre 81 bis 87. Sie tragen an ihren, den Wärmetauscherrohren abgewandten Ende die Führungs- bzw. Elektrolytzuführschläuche 99 bis 102. Die Auffangwanne 90 selbst ist mit einem nahezu bis unter den Rohrboden 80 reichenden Rand 103 versehen und besitzt einen Auslaufstutzen 104, der über einen Hilfsschlauch 105 mit dem Elektrolytbehälter 7 verbunden ist. Die Auffangwanne 90 ist in der Mitte mit einer Kupplungsscheibe 106 des Auslegearms 88 des Manipulators verbunden. Beim Ausführungsbeispiel der FIG 4 trägt der Adapter vier in Reihe hintereinander angeordnete Schlauchanschlüsse 91 bis 94, wobei jeweils zwei Schlauchanschlüsse im Wärmetauscherrohrabstand nebeneinander angeordnet sind.FIG. 4 shows a schematically drawn section of the tube sheet 80 of a steam generator with the various heat exchanger tubes 81 to 87 and an adapter 89 pressed onto the tube sheet by the extension arm 88 of a manipulator (not shown further here). The adapter 89 consists of a collecting trough 90 the four hose connections 91 to 94 in the exemplary embodiment are carried out at a distance which corresponds to the distance between the heat exchanger tubes 81 to 87 in the tube sheet 80. These hose connections 91 to 94 are flanged at their end facing the tube sheet and each have a soft sealing ring 95 to 98 on the flange periphery, with which they bear against the weld seams with which the heat exchanger tubes are welded in the tube sheet 80. These hose connections 91 to 94 have the same inner diameter as the heat exchanger tubes 81 to 87. They carry the guide or electrolyte supply hoses 99 to 102 at their ends facing away from the heat exchanger tubes. The collecting trough 90 itself has an edge that extends almost below the tube plate 80 103 and has an outlet connection 104 which is connected to the electrolyte container 7 via an auxiliary hose 105. The collecting trough 90 is connected in the middle to a clutch disk 106 of the extension arm 88 of the manipulator. In the exemplary embodiment in FIG. 4, the adapter carries four hose connections 91 to 94 arranged in series one behind the other, two hose connections each being arranged next to one another at the heat exchanger tube spacing.

Sollen die Wärmetauscherrohre eines Dampferzeugers dekontaminiert oder aus anderen Gründen durch Elektropolieren gereinigt werden, so kann in die beiden Kammern 11, 18 der Bodenkalotte 12 des Dampferzeugers 1 je ein vorbekannter Manipulator 14, 20 zur fernbedienbaren Inspektion der Wärmetauscherrohre 3, 4, 5 eingesetzt werden. Auf den Auslegearmen 13,19 jedes der beiden Manipulatoren wird dann ein Adapter 15, 21 mit angeschlossenem Führungsschlauch 16 bzw. Elektrolytzuführschlauch 9 aufgesteckt. Nachdem diese Arbeiten ausgeführt sind, sind die mit deutlicher Strahlenbelastung verbundenen Arbeiten in der Bodenkalotte 12 des Dampferzeugers 1, sieht man vom späteren Abbau der Adapter und Manipulatoren ab, abgeschlossen. Außerhalb des Dampferzeugers wird anschließend die Elektrode 24 mit dem ihr zugeordneten Schubkabel 23 in den Führungsschlauch 16 eingeführt und der Führungsschlauch 16 an das vordere Ende der Dichtvorrichtung 22 angekuppelt. Danach kann der Elektrolytzuführschlauch 9 an die Elektrolytpumpe 8 angeschlossen werden. Jetzt kann sich das Bedienungspersonal völlig aus dem Strahlungsbereich entfernen, weil alle weiteren Arbeiten ferngesteuert ausführbar sind.If the heat exchanger tubes of a steam generator are to be decontaminated or cleaned for other reasons by electropolishing, then the bottom cap 12 of the Steam generator 1 each a known manipulator 14, 20 for remote-controlled inspection of the heat exchanger tubes 3, 4, 5 are used. An adapter 15, 21 with a connected guide tube 16 or electrolyte feed tube 9 is then plugged onto the extension arms 13, 19 of each of the two manipulators. After this work has been carried out, the work associated with significant radiation exposure in the bottom cap 12 of the steam generator 1 is complete, apart from the subsequent dismantling of the adapters and manipulators. Outside the steam generator, the electrode 24 with the push cable 23 assigned to it is then inserted into the guide hose 16 and the guide hose 16 is coupled to the front end of the sealing device 22. The electrolyte supply hose 9 can then be connected to the electrolyte pump 8. Now the operating personnel can completely move away from the radiation area because all further work can be carried out remotely.

Ober die Fernsteuerung der beiden Manipulatoren können die an deren Auslegearme angekuppelten Adapter 15, 21 so zu den einzelnen durch den Rohrboden 2 geführten Wärmeaustauscherrohren positioniert werden, daß die Schlauchanschlüsse genau fluchtend zu den Mündungen der Wärmetauscherrohre, in den beiden Kammern 11, 18 der Bodenkalotte 12 des Dampferzeugers 1 angepreßt werden. Dabei werden die weichen Dichtringe (vgl. FIG 4) an den flanschartigen Enden der Schlauchanschlüsse gegen die Schweißnaht, die das jeweilige Wärmetauscherrohr mit dem Rohrboden 2 verbindet, gedrückt. Um einen korrekten Sitz der Adapter 15, 21 und die Dichtheit des Systems zu überprüfen kann, wie hier nicht weiter dargestellt, eine Beaufschlagung mit Druckgas oder Luft durchgeführt werden. Ist dies der Fall, so wird die Vorschubeinrichtung 25 eingeschaltet. Das Schubkabel 23 wird jetzt durch die motorisch angetriebenen Rollen 74 bis 78 mitsamt der an seinen Ende befestigten Elektrode 24 durch den Führungsschlauch 16, den Adapter 21 in das jeweilige Wärmetauscherrohr 3 eingefahren.Via the remote control of the two manipulators, the adapters 15, 21 coupled to their extension arms can be positioned in relation to the individual heat exchanger tubes guided through the tube plate 2 such that the hose connections are exactly aligned with the mouths of the heat exchanger tubes in the two chambers 11, 18 of the base cap 12 of the steam generator 1 are pressed. The soft sealing rings (see FIG. 4) at the flange-like ends of the hose connections are pressed against the weld seam which connects the respective heat exchanger tube to the tube sheet 2. In order to check the correct seating of the adapters 15, 21 and the tightness of the system, pressurized gas or air can be applied, as is not shown here. If this is the case, the feed device 25 is switched on. The push cable 23 is now moved through the motor-driven rollers 74 to 78 together with the electrode 24 fastened to its end through the guide tube 16, the adapter 21 into the respective heat exchanger tube 3.

Die Elektrode 24 wird dabei soweit eingefahren, wie das Wärmetauscherrohr dekontaminiert werden soll. Die Biegsamkeit der Elektrode ermöglicht dabei das Durchfahren auch von engen Wärmetauscherrohrbögen. Durch das trockene Einschieben der Elektrode entgegen der späteren Strömungsrichtung des Elektrolyten wird sichergestellt, daß die Elektrode im Falle des Klemmens im Wärmetauscherrohr mit dem Schubkabel und unterstützt durch die der Strömung des Elektrolyten wieder herausgezogen werden könnte. Nach dem die Elektrode die gewünschte extremste Position erreicht hat, was über einen Wegmeßfühler (nicht dargestellt) in der Vorschubeinrichtung 25 kontrolliert werden kann, wird die Pumpe 8 für den Elektrolyten eingeschaltet und wird der Elektrolyt über den Elektrolytzuführschlauch 9 in das Wärmetauscherrohr 3 eingepumpt. Dieser strömt durch das Wärmetauscherrohr an der Elektrode 24 vorbei und zwischen Schubkabel 23 und Führungsschlauch 16 in die erste Kammer der Dichtvorrichtung 22. Aus dieser Kammer strömt es durch die erste Schlauchtülle 69 in den Elektrolytbehälter 7 zurück.The electrode 24 is retracted as far as the heat exchanger tube is to be decontaminated. The flexibility of the electrode enables the passage through narrow heat exchanger tube bends. The dry insertion of the electrode against the later flow direction of the electrolyte ensures that the electrode can be pulled out again in the event of jamming in the heat exchanger tube with the push cable and supported by the flow of the electrolyte. After the electrode has reached the desired extreme position, which can be controlled via a displacement sensor (not shown) in the feed device 25, the pump 8 for the electrolyte is switched on and the electrolyte is pumped into the heat exchanger tube 3 via the electrolyte supply hose 9. This flows through the heat exchanger tube past the electrode 24 and between the push cable 23 and the guide hose 16 into the first chamber of the sealing device 22. From this chamber it flows back through the first hose nozzle 69 into the electrolyte container 7.

Nachdem das Wärmetauscherrohr 7 mit Elektrolyt gefüllt ist, wird die Gleichspannungsquelle 31 eingeschaltet und die Elektrode 24 mit einer vorgegebenen Geschwindigkeit über die Vorschubeinrichtung 25 aus dem Wärmetauscherrohr wieder herausgezogen. Durch den Stromfluß zwischen der Elektrode 24 und dem mit dem anderen Pol der Gleichspannungsquelle 31 verbundenen Wärmetauscherrohr 3 werden die Verunreinigungen an der Innenoberfläche des Wärmetauscherrohres sowie vorstehende Unebenheiten des Rohres bevorzugt abgetragen. Die abgetragenen Partikel gelangen mit dem zurückfließenden Elektrolyten in den Elektrolytbehälter. Der Strömungsdruck des Elektrolyten unterstützt den Zug am Schubkabel 23. Die aus der ersten Kammer in die zweite Kammer der Dichtvorrichtung vom Schubkabel mitgenommenen Elektrolytreste tropfen in dieser ab oder werden beim Passieren der Dichtscheibe 60 abgestreift. In die dritte Kammer mitgenommene Elektrolytreste werden beim Passiere der die dritte Kammer von der vierten Kammer trennenden Dichtscheibe 62 von der entgegenströmenden Druckluft in die dritte Kammer zurückgeblasen und tropfen dort ab.After the heat exchanger tube 7 is filled with electrolyte, the DC voltage source 31 is switched on and the electrode 24 is pulled out of the heat exchanger tube again at a predetermined speed via the feed device 25. Due to the current flow between the electrode 24 and the heat exchanger tube 3 connected to the other pole of the direct voltage source 31, the impurities on the inner surface of the heat exchanger tube and protruding bumps in the tube are preferably removed. The removed particles reach the electrolyte tank with the electrolyte flowing back. The flow pressure of the electrolyte supports the pull on the push cable 23. The electrolyte residues entrained by the push cable from the first chamber into the second chamber of the sealing device drip in it or are stripped off when it passes through the sealing disk 60. Electrolyte residues entrained in the third chamber are blown back into the third chamber by the counter-flowing compressed air when they pass through the sealing disk 62 separating the third chamber from the fourth chamber and drip off there.

Von der Umwälzpumpe 28 des Elektrolytversorgungssystems 27 wird ständig ein Teil des Elektrolyts aus dem Elektrolytbehälter 7 abgepumpt, zur Kühlung über einem Wärmetauscher und zur Reinigung über einen Filter geleitet. Die gereinigte und gekühlte Elektrolytflüssigkeit gelangt dann erneut in den Elektrolytbehälter 7. Auf diese Weise wird die Temperatur im Elektrolytbehälter 7 konstant gehalten und kann das Elektrolytversorgungssystem 27 weiterlaufen, auch wenn die Pumpe 8, die den Elektrolyten sonst in den Elektrolytzuführschlauch 9 pumpt, beim Verstellen der Adapter abgeschaltet ist. Sobald die Elektrode 24 aus einem Wärmetauscherrohr 3 herausgezogen ist und den Adapter 21 erreicht hat und das Wärmetauscherrohr 3 somit elektropoliert bzw. dekontaminiert ist, kann die Spannungsquelle 31 und die Schubeinrichtung 25 abgeschaltet werden. Nachdem auch die Pumpe 8 für den Elektrolyten abgeschaltet ist, wird Druckluft in den Elektrolytzuführschlauch 9 eingeblasen und das im Elektrolytzuführschlauch, im Wärmetauscherrohr 3 und im Führungsschlauch 16 befindliche restliche Elektrolyt in den Elektrolytbehälter 7 zurückgeblasen. Nunmehr können durch Ansteuerung der beiden Manipulatoren 14, 20 die Adapter 15, 21 vor ein weiteres Wärmetauscherrohr positioniert werden. Auch hier wird dann wiederum zunächst durch Druckgaseinleitung die exakte Position der beiden Adapter und die Dichtheit kontrolliert und kann durch Druckgaseinleitung die exakte Position der beiden Adapter und die Dichtheit kontrolliert und kann durch bloßes Einschalten der Vorschubeinrichtung 25, der Pumpe 8, der Gleichspannungsquelle 31 das nächste Wärmetauscherrohr elektropoliert werden, ohne daß irgend Jemand in eine der beiden Kammern 11, 18 der Bodenkalotte 12 des Dampferzeugers 1 einzusteigen braucht. Die beim Elektropolieren in den Elektrolyten übergetretenen radioaktiven Verunreinigungen werden mit dem Elektrolyten in den Elektrolytbehälter gespült und gelangen letztendlich über den Filterkreislauf in den Filter 30. Durch den kontinuierlichen Betrieb des Filterkreislaufs über die Umwälzpumpe 28 kann die Aktivität des Elektrolyten, wie auch dessen Temperatur auf einem niedrigen Niveau gehalten werden. Zuletzt braucht nur noch der Filterkuchen entsorgt zu werden.A portion of the electrolyte is continuously pumped out of the electrolyte tank 7 by the circulating pump 28 of the electrolyte supply system 27, passed over a heat exchanger for cooling and over a filter for cleaning. The cleaned and cooled electrolyte liquid then returns to the electrolyte container 7. In this way, the temperature in the electrolyte container 7 is kept constant and the electrolyte supply system 27 can continue to run, even if the pump 8, which otherwise pumps the electrolyte into the electrolyte supply hose 9, when adjusting the Adapter is switched off. As soon as the electrode 24 has been pulled out of a heat exchanger tube 3 and has reached the adapter 21 and the heat exchanger tube 3 is thus electropolished or decontaminated, the voltage source 31 and the pusher device 25 can be switched off. After the pump 8 for the electrolyte is also switched off, compressed air is blown into the electrolyte feed hose 9 and the remaining electrolyte in the electrolyte feed hose, in the heat exchanger tube 3 and in the guide hose 16 is blown back into the electrolyte container 7. Now, by controlling the two manipulators 14, 20, the adapters 15, 21 can be positioned in front of a further heat exchanger tube. Here, too, the exact position of the two adapters and the tightness are then checked by introducing compressed gas, and the exact position of the two adapters and the tightness can be checked by introducing pressurized gas, and the next can be switched on by simply switching on the feed device 25, the pump 8, and the DC voltage source 31 Heat exchanger tube are electropolished without anyone having to enter one of the two chambers 11, 18 of the bottom cap 12 of the steam generator 1. The radioactive contaminants that have passed into the electrolyte during electropolishing are rinsed with the electrolyte into the electrolyte container and ultimately reach the filter 30 via the filter circuit. Through the continuous operation of the filter circuit via the circulation pump 28, the activity of the electrolyte and its temperature can be reduced to one low Level can be maintained. Finally, only the filter cake needs to be disposed of.

Bei der Verwendung eines Adapters 89 mit vier Schlauchanschlüssen 91 bis 94, wie das in der Fig. 4 dargestellt ist, können mit vier verschiedenen Vorschub- und Dichteinheiten und vier verschiedenen Führungs-und Elektrolytzuführschläuchen vier Wärmetauscherrohre gleichzeitig elektropoliert werden. Nach deren Reinigung braucht dann der Adapter 89 vom Auslegerarm 88 des Manipulators nur um zwei Wärmetauscherrohre und später um sechs Wärmetauscherrohre weiter verschoben und an den Rohrboden 80 angedrückt zu werden um die nächsten vier Wärmetauscherrohre elektropolieren zu können. Die Auffangwanne 90 verhindert eine Verunreinigung der Bodenkalotte des Dampferzeugers, wenn an den Dichtungsringen 95 bis 98 Elektrolytflüssigkeit heraustropfen sollte. Auch wird so der Verbrauch an Elektrolytflüssigkeit verringert.When using an adapter 89 with four hose connections 91 to 94, as shown in FIG. 4, four heat exchanger tubes can be electropolished simultaneously with four different feed and sealing units and four different guide and electrolyte supply hoses. After cleaning, the adapter 89 then only needs to be shifted from the extension arm 88 of the manipulator by two heat exchanger tubes and later by six heat exchanger tubes and pressed onto the tube sheet 80 in order to be able to electropolish the next four heat exchanger tubes. The collecting trough 90 prevents contamination of the bottom cap of the steam generator if electrolyte liquid should drip out of the sealing rings 95 to 98. This also reduces the consumption of electrolyte liquid.

Mit dieser Vorrichtung ist der große Vorteil verbunden, daß die Aufenthaltsdauer des Bedienungspersonals im strahlenden Bereich, insbesondere in den beiden Kammern in der Bodenkalotte des Dampferzeugers auf die Zeiten beschränkt werden kann, die erforderlich ist, um die Manipulatoren einzusetzen und die Adapter auf den Auslegerarmen 13, 19, 88 der Manipulatoren 14, 20 zu befestigen und später nach Beendigung der Dekominationsarbeiten wieder zu demontieren. Alle übrigen Arbeiten lassen sich ferngesteuert durchführen. Infolge der Verwendung von Adaptern 89 mit mehreren Schlauchanschlüssen 91 bis 94 lassen sich gleichzeitig mehrere Dampferzeugerrohre 81, 82, 85, 86 elektropolieren und läßt sich die Gesamtzeit, in der dekontaminiert wird, stark verkürzen.This device has the great advantage that the length of time that the operating personnel can stay in the radiating area, in particular in the two chambers in the bottom cap of the steam generator, can be limited to the times required to use the manipulators and the adapters on the cantilever arms 13 , 19, 88 to fix the manipulators 14, 20 and later to dismantle them once the decompression work has ended. All other work can be carried out remotely. As a result of the use of adapters 89 with a plurality of hose connections 91 to 94, a plurality of steam generator tubes 81, 82, 85, 86 can be electropolished at the same time and the total time in which decontamination is carried out can be greatly reduced.

BezugszeichenlisteReference symbol list

  • Dampferzeuger 1Steam generator 1
  • Rohrboden 2Tube sheet 2
  • Wärmetauscherrohre 3, 4, 5Heat exchanger tubes 3, 4, 5
  • Vorrichtung zum Elektropolieren 6Electropolishing device 6
  • Elektrolytbehälter 7Electrolyte tank 7
  • Pumpe 8Pump 8
  • Elektrolytzuführschlauch 9Electrolyte supply hose 9
  • Mannloch 10Manhole 10
  • rechte Kammer 11right chamber 11
  • Bodenkalotte 12Bottom cap 12
  • Auslegerarm 13Extension arm 13
  • Manipulator 14Manipulator 14
  • Adapter 15Adapter 15
  • Führungsschlauch 16Guide hose 16
  • Mannloch 17Manhole 17
  • linke Kammer 18left chamber 18
  • Auslegerarm 19Extension arm 19
  • Manipulator 20Manipulator 20
  • Adapter 21Adapter 21
  • Dichtvorrichtung 22Sealing device 22
  • Schubkabel 23Push cable 23
  • flexible Elektrode 24flexible electrode 24
  • Vorschubeinrichtung 25Feed device 25
  • Aufwickeltrommel 26Take-up drum 26
  • Elektrolytversorgungssystem 27Electrolyte supply system 27
  • Umwälzpumpe 28Circulation pump 28
  • Wärmetauscher 29Heat exchanger 29
  • Filter 30Filter 30
  • Gleichspannungsquelle 31DC voltage source 31
  • Stahlseil 32Steel rope 32
  • Feder 33, 34, 35, 36, 37Spring 33, 34, 35, 36, 37
  • Abstandshalter 38, 39, 40, 41Spacers 38, 39, 40, 41
  • Klemmhülse 42,43Clamping sleeve 42.43
  • Einführkonus 44Insertion cone 44
  • Überwurfmutter 45Union nut 45
  • Kunststoff 46Plastic 46
  • Kupferkabet 47Copper cable 47
  • Rohrstück 48Pipe section 48
  • Ring (mit großer lichter Weite) 49, 50, 51, 52, 53Ring (with a large internal width) 49, 50, 51, 52, 53
  • Ring (mit geringer lichter Weite) 54, 55, 56, 57, 58Ring (with a small internal width) 54, 55, 56, 57, 58
  • Dichtscheibe 59, 60, 61, 62, 63, 64, 65Sealing washer 59, 60, 61, 62, 63, 64, 65
  • Scheibe 66,67Disc 66.67
  • Klemmvorrichtung 68Clamping device 68
  • Auslaufstutzen 69,70, 71, 72Outlet spout 69, 70, 71, 72
  • Druckluftstutzen 73Compressed air nozzle 73
  • Antriebsrolle 74, 75, 76, 77, 78Drive roller 74, 75, 76, 77, 78
  • Rohrboden 80Tube sheet 80
  • Wärmetauscherrohr 81, 82, 83, 84, 85, 86, 87Heat exchanger tube 81, 82, 83, 84, 85, 86, 87
  • Auslegerarm 88Extension arm 88
  • Adapter 89Adapter 89
  • Auffangwanne 90Collecting pan 90
  • Schlauchanschluß 91,92,93,94Hose connection 91.92.93.94
  • Dichtungsring 95,96,97,98Sealing ring 95.96.97.98
  • Schlauch 99,100,101,102Hose 99,100,101,102
  • Rand 103Margin 103
  • Auslaufstutzen 104Outlet connection 104
  • Hilfsschlauch 105Auxiliary hose 105
  • Kupplungsscheibe 106Clutch disc 106

Claims (15)

1. Method for electro-polishing the internal surface of U-shaped heat exchanger pipes with an electrode, which is connected to the negative pole of a dc voltage source, which can be pushed into the heat exchanger pipe and which can be pulled out again by way of a pulling member, and with a pump, which is connected to an electrolyte tank, for the supply of the electrolyte, characterised in that in the two chambers (11, 18) of the base spherical part (12) of the heat exchanger (1) there is set, in the first instance, in each case, a manipulator (14, 20) which is known per se for positioning, in a manner suitable for remote control, pipe probes in the mouths of heat exchanger pipes (4, 5) and at the free end of the bracket arm (13, 19, 88) of each manipulator there is secured, in each case, an adaptor (15, 21, 89) with at least one tube connection; the two adaptors are pressed by the respective manipulator with a seal (95 to 98) onto the mouths of the same heat exchanger pipe (3, 81, 82, 85, 86); subsequently an electrode (24) is pushed by way of a thrust cable (23) as far as the end of the section of the heat exchanger pipe to be examined, through a guide tube (16) connected to the heat exchanger pipe; the electrolytic fluid is then pumped by way of an electrolyte supply tube (9) into the heat exchanger pipe and conducted by way of the guide tube (16) into a collecting basin (7) and the electrode, with current switched on, is slowly pulled out of the heat exchanger pipe and the electrolyte is finally removed from the heat exchanger pipe.
2. Method according to claim 1, characterised in that the electrolytic fluid is pumped into the heat exchanger pipe (3, 81, 82, 85, 86) in the same direction in which the electrode (24) is pulled out of the heat exchanger pipe.
3. Method according to claim 1, characterised in that for the purpose of checking the tight fit of the adaptors (15, 21, 89) compressed gas is pressed into the tube before the electrolyte is pumped in.
4. Apparatus for carrying out the method according to claim 1 to 3, characterised in that an electrode (24) is secured to a thrust cable (23) consisting of a plain sheathed copper cable (47); said electrode can be pushed .into a heat exchanger pipe (3) and back out again with the thrust cable through a guide tube (16) and a pertinent adaptor (21) positioned by a manipulator (20); the thrust cable is guided through a sealing arrangement (22), closing the free end of the tube (16), and an electrolyte supply tube (9), which is connected with an adaptor located on a second manipulator, is connected at its free end to an electrolyte supply system (27).
5. Apparatus according to claim 4, characterised in that the tube end connected with the sealing arrangement (22) is connected to a collecting basin (7) for the spent electrolyte and the end of the electrolyte supply tube (9) is connected to a pump (8) for the supply of fresh electrolyte.
6. Apparatus according to claim 5, characterised in that the collecting basin (7) for the spent electrolyte is connected to an installation (28, 29, 30) for recovering the electrolyte.
7. Apparatus according to claim 4, characterised in that a feed device (25) for the longitudinal displacement of the thrust cable (23) is connected to the sealing arrangement (22).
8. Apparatus according to claim 7, characterised in that the feed device (25) comprises motor-driven drive rollers (74 to 78) which clamp the thrust cable (23) between them.
9. Apparatus according to claim 8, characterised in that the feed device (25) comprises a take-up drum (26) for the thrust cable (23).
10. Apparatus according to claim 4, characterised in that the adaptor (15, 21, 89) has at least one tube connection (91 to 94), which is adapted to the diameter of the heat exchanger pipes (3,4, 5, 81 to 87) and of the electrode (24) and is provided with an annular seal (95 to 98) which can be pressed against the pipe base (2, 80) of the heat exchanger (1), and is secured to the bracket arm (13, 19, 88) of a manipulator.
11. Apparatus according to claim 10, characterised in that a collecting trough (90), which surrounds the tube connection (91 to 94), for outgoing electrolytic fluid is secured to the adaptor (89).
12. Apparatus according to claim 11, characterised in that the collecting trough (90) is connected with an auxiliary tube (105) to the collecting basin (7) for the spent electrolyte.
13. Apparatus according to claim 4, characterised in that the bracket arms (13, 19) of the two manipulators (14, 20) can be positioned, in each case, in synchronism in respect of the two ends of one and the same heat exchanger pipe (3).
14. Apparatus according to claim 10, characterised in that the adaptor (89) supports several tube connections (91 to 94) which are arranged with the same mutual spacing as the heat exchanger pipes (81 to 87).
15. Apparatus according to claim 4, characterised in that the copper cable (47) is sheathed with plastics material, more particularly polytetrafluoroethylene.
EP85109706A 1984-08-17 1985-08-02 Process and apparatus for electropolishing the internal surfaces of u-shaped heat exchanger pipes Expired EP0171717B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19843430384 DE3430384A1 (en) 1984-08-17 1984-08-17 METHOD AND DEVICE FOR ELECTROPOLISHING THE INTERIOR SURFACE OF U-SHAPED HEAT EXCHANGER TUBES
DE3430384 1984-08-17

Publications (2)

Publication Number Publication Date
EP0171717A1 EP0171717A1 (en) 1986-02-19
EP0171717B1 true EP0171717B1 (en) 1988-11-02

Family

ID=6243327

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85109706A Expired EP0171717B1 (en) 1984-08-17 1985-08-02 Process and apparatus for electropolishing the internal surfaces of u-shaped heat exchanger pipes

Country Status (4)

Country Link
US (1) US4645581A (en)
EP (1) EP0171717B1 (en)
DE (2) DE3430384A1 (en)
ES (1) ES8700339A1 (en)

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FR2623279B1 (en) * 1987-11-13 1990-04-06 Electricite De France METHOD AND APPARATUS FOR MARKING A TUBULAR PLATE EXCHANGER TUBE
BE1002822A4 (en) * 1989-02-08 1991-06-18 Lemmens Godfried Working method for repairing the pipes of a steam generator in a nuclearpower station as well as the device used for this
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Also Published As

Publication number Publication date
ES8700339A1 (en) 1986-10-16
DE3566002D1 (en) 1988-12-08
ES546194A0 (en) 1986-10-16
EP0171717A1 (en) 1986-02-19
US4645581A (en) 1987-02-24
DE3430384A1 (en) 1986-02-20

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