EP0144036A2 - Process for decontaminating metallic components of a nuclear plant - Google Patents

Process for decontaminating metallic components of a nuclear plant Download PDF

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Publication number
EP0144036A2
EP0144036A2 EP84113995A EP84113995A EP0144036A2 EP 0144036 A2 EP0144036 A2 EP 0144036A2 EP 84113995 A EP84113995 A EP 84113995A EP 84113995 A EP84113995 A EP 84113995A EP 0144036 A2 EP0144036 A2 EP 0144036A2
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EP
European Patent Office
Prior art keywords
electrolyte liquid
electrolyte
filter
component
liquid
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Granted
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EP84113995A
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German (de)
French (fr)
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EP0144036B1 (en
EP0144036A3 (en
Inventor
Hermann Dipl.-Ing. Operschall
Hubert Dipl.-Ing. Stamm
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Siemens AG
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Kraftwerk Union AG
Siemens AG
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    • 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
    • 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
    • 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
    • C25F7/02—Regeneration of process liquids

Definitions

  • the invention relates to a method for decontaminating metallic components of a nuclear plant by electropolishing with the aid of electrodes and an electrolyte liquid.
  • the electrolyte liquid is thrown by means of a high-pressure pump through nozzles against the inner wall of a pipe, which are acted upon by a hose running in the axis of the pipe, the hose being provided with nozzles and electrodes are to be moved by the recoil of the electrolyte liquid.
  • a spiral wire surrounds the tube as an electrode.
  • a protective cap on the free end of the hose is intended to prevent the electrolyte fluid from draining too quickly. Nevertheless, it can be assumed that considerable amounts of electrolytic fluid are required in view of the recoil movement. This also applies to the device for decontamination described in European patent application 0 074 464, in which the phosphoric and sulfuric acid used as the electrolyte is used as a bath enveloping the component.
  • the object of the invention is a decontamination, in which only small amounts of waste to be ultimately disposed of. Removal should also be as simple as possible.
  • the new method should be designed so that the effort for chemical decontamination, especially in relation to the radioactive corrosion products, essentially the gamma emitters Co-58, Co-60, Cr-51, Mn-54, Zn -65, Sb-124 and Ce-144, is significantly reduced.
  • the electrolyte liquid is passed through a filter in a circuit during the decontamination treatment.
  • the invention there is a reduction in the amount of electrolyte liquid because the liquid volume is cleaned by the constant filtration. An extensive concentration of the activity carriers in the filter is obtained. This means that the electrolyte fluid can be used longer and more often. In this way the radioactive waste (secondary waste) is reduced. It is essentially sufficient to remove used filters with radiation protection.
  • the invention has proven itself with good decontamination results.
  • Candle filters made of an acid-resistant material, in particular plastic are suitable as filters in the implementation of the invention. It is important to have the smallest possible pore size in order to be able to separate the oxide particles dissolved in the electrolyte liquid. The pore size should not exceed 1.5 pm. Even more favorable results are obtained with a filter whose pore size is 1.2 ⁇ m or less. Because of the constant cleaning, the invention makes do with less aggressive electrolyte liquids. Therefore various organic or inorganic acids of low concentration are possible. You can also work with alkalis. The electrolyte content in an aqueous solution need only be a few percent by weight. Phosphoric acid with a concentration of 8 to 15 percent by weight, in particular 10 percent by weight, is particularly suitable for the treatment of austenitic materials.
  • the decontamination can advantageously by a mechanical action amplified.
  • a relative movement between the electrolyte liquid and the component can be generated with ultrasound, preferably in the kilohertz range.
  • high flow rates (> 1m / s) with an erosive effect on the surface to be decontaminated can be generated by high electrolyte throughput, in particular by forming the flow cross sections for the electrolyte throughput as narrow gaps.
  • the electrolyte liquid can also be moved along the component with the aid of an electrode. A trough-shaped electrode filled with a wiping agent is particularly suitable for this.
  • a plastic sponge made of polyester or polypropylene is advantageously used. But you can also work with a plastic brush to improve the mechanical effect, which contributes to breaking up the contaminated oxide layer.
  • the component to be decontaminated can be treated in a plastic tub from which the electrolyte liquid is fed into the filter. This is especially true in the event that external surfaces are to be decontaminated which, because of their surface shape, cannot be enclosed with an electrode so tightly that practically no electrolyte liquid can escape. In the case of components with a cavity to be decontaminated, this can be closed except for an outlet for the electrolyte liquid, so that the component itself is used in a known manner as a container. However, it is also possible to combine the two in order to avoid contamination by escaping electrolyte liquid.
  • the size of the trough-shaped electrodes depends on the curvature of the surfaces to be treated. Large electrodes can be used for weak curvatures. On the other hand, it is also possible to operate a plurality of electrodes with a common voltage source and a common filter in parallel in order to enlarge the overall effective electrode areas.
  • the pipe section 1 to be decontaminated is an anode connected to a DC voltage source 2.
  • the cathode is designed as a trough 3, which encloses a sponge body 4 made of polyester.
  • the electrode 3 is composed of a base plate 6 with a circular cross section and a flanged edge strip 7 which surrounds this and the sponge body 4 and over which the sponge body 4 projects.
  • a handle 8 is attached to the base plate 6, with which the electrode 3 can be guided by hand along the inner surface of the tube 1, so that the sponge body 4 wipes along the inner surface 9 of the tube piece 1.
  • a line 10 leads through the base plate 6, through which, in the direction of the arrows 11, phosphoric acid with a concentration of 10 percent by weight circulates as an electrolyte liquid in a circle.
  • the circle includes a candle filter 12 and an electrolyte pump 13 and a plastic trough 14 from which the electrolyte liquid emerging from the sponge body 4 is sucked off.
  • the pipe section 1 With the help of a pad 15, the pipe section 1 is mounted obliquely over the plastic trough 14, so that the electrolyte liquid flows off on one side.
  • the electrolyte liquid has a temperature of 25 to 40 ° C because it heats up during decontamination.
  • the current surface load is approximately 20 amperes / dm 2 . If, for example, austenitic steel DIN 1.4550 is treated with these values, 10 to 15 minutes being used for an area of 6 dm 2 , the radiation exposure before decontamination is reduced by more than 600 mR / h to values of less than 20 mR /H. The inner surface of the pipe then appears to be shiny metallic.
  • the detached oxide layer is deposited in the filter candle 12 with a pore size of ⁇ 1.2 pm with 90% of the activity.
  • the tube Before re-use, the tube must be rinsed so that it is chemically neutral. This flushing can be much less complex if a chemical which is already present during normal operation of the tube 1, for example the boric acid used in a pressurized water reactor for reactivity control, is used as the electrolyte.
  • the detached activity carriers resulting from the decontamination are removed by a final storage of the filter candle 12 using known means.
  • the electrolyte liquid itself can be retained for further applications.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Food Science & Technology (AREA)
  • General Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Filtering Materials (AREA)
  • Water Treatment By Electricity Or Magnetism (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
  • Cleaning By Liquid Or Steam (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Removal Of Specific Substances (AREA)

Abstract

Das zum Dekontaminieren metallischer Komponenten (1) einer kerntechnischen Anlage bekannte Elektropolieren mit einer Elektrolytflüssigkeit wird so ausgeführt, daß die Elektrolytflüssigkeit im Umlauf durch einen Filter (12) geführt wird. Dabei kann Elektrolytflüssigkeit in einer mit einem Wischmittel gefällten trogförmigen Elektrode (3) längs der Komponente (1) bewegt werden. Die Erfindung kommt insbesondere für die Behandlung von Primärkreisrohren eines Druckwasserreaktors in Frage.

Figure imgaf001
The electropolishing with an electrolyte liquid known for decontaminating metallic components (1) of a nuclear plant is carried out in such a way that the electrolyte liquid is circulated through a filter (12). Electrolyte liquid can be moved along the component (1) in a trough-shaped electrode (3) which has been precipitated with a wiping agent. The invention is particularly suitable for the treatment of primary circuit tubes of a pressurized water reactor.
Figure imgaf001

Description

Die Erfindung betrifft ein Verfahren zum Dekontaminieren metallischer Komponenten einer kerntechnischen Anlage durch Elektropolieren mit Hilfe von Elektroden und einer Elektrolytflüssigkeit.The invention relates to a method for decontaminating metallic components of a nuclear plant by electropolishing with the aid of electrodes and an electrolyte liquid.

Bei dem aus der DE-OS 31 36 187 bekannten Verfahren der oben genannten Art wird die Elektrolytflüssigkeit mit Hilfe einer Hochdruckpumpe durch Düsen gegen die Innenwand eines Rohres geschleudert, die über einen in der Achse des Rohres verlaufenden Schlauch beaufschlagt werden, wobei der Schlauch mit Düsen und Elektroden durch den Rückstoß der Elektrolytflüssigkeit bewegt werden soll. Als Elektrode umgibt ein wendelförmiger Draht den Schlauch. Eine Schutzkappe am freien Ende des Schlauches soll das zu rasche Abfließen der Elektrolytflüssigkeit verhindern. Dennoch ist zu vermuten, daß schon im Hinblick auf die Rückstoßbewegung beträchtliche Mengen an Elektrolytflüssigkeit benötigt werden. Dies gilt auch für die in der europäischen Patentanmeldung 0 074 464 beschriebene Vorrichtung zum Dekontaminieren, bei der die als Elektrolyt verwendete Phosphor- und Schwefelsäure als ein die Komponente einhüllendes Bad verwendet wird.In the process of the above-mentioned type known from DE-OS 31 36 187, the electrolyte liquid is thrown by means of a high-pressure pump through nozzles against the inner wall of a pipe, which are acted upon by a hose running in the axis of the pipe, the hose being provided with nozzles and electrodes are to be moved by the recoil of the electrolyte liquid. A spiral wire surrounds the tube as an electrode. A protective cap on the free end of the hose is intended to prevent the electrolyte fluid from draining too quickly. Nevertheless, it can be assumed that considerable amounts of electrolytic fluid are required in view of the recoil movement. This also applies to the device for decontamination described in European patent application 0 074 464, in which the phosphoric and sulfuric acid used as the electrolyte is used as a bath enveloping the component.

Beim Bekannten ist nicht dargelegt, wie die Elektrolytflüssigkeit nach dem Dekontaminieren behandelt wird, ohne daß der damit entstehende radioaktive Abfall, der seinerseits strahlungssicher beseitigt werden muß, nicht ebenfalls umfangreich wird. Deshalb liegt die Aufgabe der Erfindung in einer Dekontamination, bei der nur geringe Mengen an letztlich zu beseitigenden Abfällen anfallen. Die Beseitigung soll außerdem möglichst einfach sein. Darüber hinaus soll das neue Verfahren so auszugestalten sein, daß der Aufwand für die chemische Dekontamination vor allem in bezug auf die radioaktiven Korrosionsprodukte, im wesentlichen also die Gamma-Strahler Co-58, Co-60, Cr-51, Mn-54, Zn-65 , Sb-124 und Ce-144, erheblich verringert ist.The known method does not show how the electrolytic liquid is treated after decontamination without the radioactive waste which arises and which in turn eliminates it in a radiation-safe manner must not become extensive as well. Therefore, the object of the invention is a decontamination, in which only small amounts of waste to be ultimately disposed of. Removal should also be as simple as possible. In addition, the new method should be designed so that the effort for chemical decontamination, especially in relation to the radioactive corrosion products, essentially the gamma emitters Co-58, Co-60, Cr-51, Mn-54, Zn -65, Sb-124 and Ce-144, is significantly reduced.

Gemäß der Erfindung ist vorgesehen, daß die Elektrolytflüssigkeit während der Dekontaminationsbehandlung in einem Kreislauf über ein Filter geführt wird.According to the invention it is provided that the electrolyte liquid is passed through a filter in a circuit during the decontamination treatment.

Bei der Erfindung kommt man zu einer Verringerung der Menge der Elektrolytflüssigkeit, weil das Flüssigkeitsvolumen durch die ständige Filtration gereinigt wird. Man erhält eine weitgehende Konzentration der Aktivitätsträger im Filter. Somit kann die Elektrolytflüssigkeit länger und öfters eingesetzt werden. So wird der radioaktive Abfall (Sekundärwaste) reduziert. Es genügt im wesentlichen, verbrauchte Filter strahlungssicher zu beseitigen. Dabei hat sich die Erfindung mit guten Dekontaminationsergebnissen bewährt.In the invention there is a reduction in the amount of electrolyte liquid because the liquid volume is cleaned by the constant filtration. An extensive concentration of the activity carriers in the filter is obtained. This means that the electrolyte fluid can be used longer and more often. In this way the radioactive waste (secondary waste) is reduced. It is essentially sufficient to remove used filters with radiation protection. The invention has proven itself with good decontamination results.

Als Filter sind bei der Verwirklichung der Erfindung Kerzenfilter aus einem säurefesten Material, insbesondere aus Kunststoff, geeignet. Wichtig ist eine möglichst geringe Porenweite, um die in der Elektrolytflüssigkeit gelösten Oxidpartikelchen abscheiden zu können. Die Porenweite sollte höchstens 1,5 pm betragen. Noch günstigere Ergebnisse erhält man mit einem Filter, dessen Porenweite 1,2 µm oder weniger beträgt. Wegen der ständigen Reinigung kommt man bei der Erfindung mit wenig aggressiven Elektrolytflüssigkeiten aus. Deshalb kommen verschiedene organische oder anorganische Säuren geringer Konzentration in Frage. Man kann auch mit Laugen arbeiten. Der Elektrolytgehalt in einer wäßrigen Lösung braucht nur wenige Gewichtsprozent zu betragen. Besonders geeignet für die Behandlung austenitischer Werkstoffe ist Phosphorsäure mit einer Konzentration von 8 bis 15 Gewichtsprozent, insbesondere 10 Gewichtsprozent.Candle filters made of an acid-resistant material, in particular plastic, are suitable as filters in the implementation of the invention. It is important to have the smallest possible pore size in order to be able to separate the oxide particles dissolved in the electrolyte liquid. The pore size should not exceed 1.5 pm. Even more favorable results are obtained with a filter whose pore size is 1.2 µm or less. Because of the constant cleaning, the invention makes do with less aggressive electrolyte liquids. Therefore various organic or inorganic acids of low concentration are possible. You can also work with alkalis. The electrolyte content in an aqueous solution need only be a few percent by weight. Phosphoric acid with a concentration of 8 to 15 percent by weight, in particular 10 percent by weight, is particularly suitable for the treatment of austenitic materials.

Zusätzlich zur elektrochemischen Lösung der konta- minierten Oxidschicht auf den metallischen Komponenten kann die Dekontamination vorteilhaft durch eine mechanische Einwirkung verstärkt werden. Dazu kann einmal mit Ultraschall, vorzugsweise im Kilohertz-Bereich, eine Relativbewegung zwischen Elektrolytflüssigkeit und Komponente erzeugt werden. Ferner kann man durch hohen Elektrolytdurchsatz große Strömungsgeschwindigkeiten (>1m/s) mit einer erosiven Wirkung an der zu dekontaminierenden Oberfläche erzeugen, insbesondere dadurch, daß man die Strömungsauerschnitte für den Elektrolytdurchsatz als enge Spalten ausbildet. Als weitere Möglichkeit kann die Elektrolytflüssigkeit auch mit Hilfe einer Elektrode längs der Komponente bewegt werden. Dazu ist besonders eine mit einem Wischmittel gefüllte trogförmige Elektrode geeignet. Sie bildet mit der Komponente einen die Elektrolytflüssigkeit begrenzenden Raum. Als Wischmittel und Träger der Elektrolytflüssigkeit wird vorteilhaft ein Kunststoffschwamm aus Polyester oder Polypropylen verwendet. Man kann aber auch mit einer Kunststoffbürste arbeiten, um die mechanische Wirkung zu verbessern, die zu einem Aufbrechen der kontaminierten Oxidschicht beiträgt.In addition to the electrochemical solution of konta - undermined oxide layer on the metallic components, the decontamination can advantageously by a mechanical action amplified. For this purpose, a relative movement between the electrolyte liquid and the component can be generated with ultrasound, preferably in the kilohertz range. Furthermore, high flow rates (> 1m / s) with an erosive effect on the surface to be decontaminated can be generated by high electrolyte throughput, in particular by forming the flow cross sections for the electrolyte throughput as narrow gaps. As a further possibility, the electrolyte liquid can also be moved along the component with the aid of an electrode. A trough-shaped electrode filled with a wiping agent is particularly suitable for this. Together with the component, it forms a space delimiting the electrolyte fluid. As a wiping agent and carrier of the electrolyte liquid a plastic sponge made of polyester or polypropylene is advantageously used. But you can also work with a plastic brush to improve the mechanical effect, which contributes to breaking up the contaminated oxide layer.

Die zu dekontaminierende Komponente kann in einer Kunststoffwanne behandelt werden, aus der die Elektrolytflüssigkeit in den Filter geführt wird. Dies gilt besonders für den Fall, daß Außenflächen zu dekontaminieren sind, die wegen ihrer Oberflächenform mit einer Elektrode nicht so dicht eingeschlossen werden können, daß praktisch keine Elektrolytflüssigkeit austreten kann. Bei Komponenten mit einem zu dekontaminierenden Hohlraum kann man diesen bis auf einen Auslaß für die Elektrolytflüssigkeit verschließen, so daß die Komponente in bekannter Weise selbst als Behälter verwendet wird. Es ist aber auch möglich, beides zu kombinieren, um Verunreinigungen durch austretende Elektrolytflüssigkeit zu vermeiden.The component to be decontaminated can be treated in a plastic tub from which the electrolyte liquid is fed into the filter. This is especially true in the event that external surfaces are to be decontaminated which, because of their surface shape, cannot be enclosed with an electrode so tightly that practically no electrolyte liquid can escape. In the case of components with a cavity to be decontaminated, this can be closed except for an outlet for the electrolyte liquid, so that the component itself is used in a known manner as a container. However, it is also possible to combine the two in order to avoid contamination by escaping electrolyte liquid.

Die Größe der trogförmigen Elektroden richtet sich nach der Krümmung der zu behandelnden Oberflächen. Bei schwachen Krümmungen kann man großflächige Elektroden verwenden. Andererseits ist es auch möglich, zur Vergrößerung der insgesamt wirksamen Elektrodenflächen mehrere Elektroden mit einer gemeinsamen Spannungsquelle und einem gemeinsamen Filter parallel zu betreiben.The size of the trough-shaped electrodes depends on the curvature of the surfaces to be treated. Large electrodes can be used for weak curvatures. On the other hand, it is also possible to operate a plurality of electrodes with a common voltage source and a common filter in parallel in order to enlarge the overall effective electrode areas.

Zur näheren Erläuterung der Erfindung wird im folgenden ein Ausführungsbeispiel beschrieben, das in der Figur schematisch dargestellt ist.In order to explain the invention in more detail, an exemplary embodiment is described below, which is shown schematically in the figure.

Das zu dekontaminierende Rohrstück 1 ist als Anode mit einer Gleichspannungsquelle 2 verbunden. Die Kathode ist als Trog 3 ausgebildet, der einen Schwammkörper 4 aus Polyester umschließt. Die Elektrode 3 ist zu diesem Zweck aus einer Grundplatte 6 mit Kreisquerschnitt und einem diese und den Schwammkörper 4 umschließenden umgebördelten Randstreifen 7 zusammengesetzt, über den der Schwammkörper 4 hinausragt. An der Grundplatte 6 ist ein Griff 8 angebracht, mit dem die Elektrode 3 von Hand längs der Innenfläche des Rohres 1 geführt werden kann, so daß der Schwammkörper 4 auf der Innenfläche 9 des Rohrstückes 1 entlangwischt.The pipe section 1 to be decontaminated is an anode connected to a DC voltage source 2. The cathode is designed as a trough 3, which encloses a sponge body 4 made of polyester. For this purpose, the electrode 3 is composed of a base plate 6 with a circular cross section and a flanged edge strip 7 which surrounds this and the sponge body 4 and over which the sponge body 4 projects. A handle 8 is attached to the base plate 6, with which the electrode 3 can be guided by hand along the inner surface of the tube 1, so that the sponge body 4 wipes along the inner surface 9 of the tube piece 1.

Durch die Grundplatte 6 führt eine Leitung 10, durch die in Richtung der Pfeile 11 als Elektrolytflüssigkeit Phosphorsäure mit einer Konzentration von 10 Gewichtsprozent in einem Kreis umläuft. Der Kreis schließt neben dem Schwammkörper 4 ein Kerzenfilter 12 und eine Elektrolytpumpe 13 sowie eine Kunststoffwanne 14 ein, aus der die aus dem Schwammkörper 4 austretende Elektrolytflüssigkeit abgesaugt wird. Mit Hilfe einer Unterlage 15 ist das Rohrstück 1 über der Kunststoffwanne 14 schräg gelagert, so daß die Elektrolytflüssigkeit einseitig abfließt.A line 10 leads through the base plate 6, through which, in the direction of the arrows 11, phosphoric acid with a concentration of 10 percent by weight circulates as an electrolyte liquid in a circle. In addition to the sponge body 4, the circle includes a candle filter 12 and an electrolyte pump 13 and a plastic trough 14 from which the electrolyte liquid emerging from the sponge body 4 is sucked off. With the help of a pad 15, the pipe section 1 is mounted obliquely over the plastic trough 14, so that the electrolyte liquid flows off on one side.

Die Elektrolytflüssigkeit hat eine Temperatur von 25 bis 40°C, weil sie sich bei der Dekontamination erwärmt. Die Stromflächenbelastung liegt bei etwa 20 Ampere/ dm2. Behandelt man mit diesen Werten zum Beispiel austenitischen Stahl DIN 1.4550, wobei 10 bis 15 Minuten für eine Fläche von 6 dm2 aufgewendet werden, so verringert sich eine vor der Dekontamination vorliegende Strahlenbelastung von mehr als 600 mR/h auf Werte von weniger als 20 mR/h. Die Rohrinnenfläche zeigt sich anschließend metallisch blank. Die dabei abgelöste Oxidschicht ist in der Filterkerze 12 mit einer Porenweite von <1,2 pm mit 90% der Aktivität abgeschieden.The electrolyte liquid has a temperature of 25 to 40 ° C because it heats up during decontamination. The current surface load is approximately 20 amperes / dm 2 . If, for example, austenitic steel DIN 1.4550 is treated with these values, 10 to 15 minutes being used for an area of 6 dm 2 , the radiation exposure before decontamination is reduced by more than 600 mR / h to values of less than 20 mR /H. The inner surface of the pipe then appears to be shiny metallic. The detached oxide layer is deposited in the filter candle 12 with a pore size of <1.2 pm with 90% of the activity.

Vor der Wiederverwendung muß das Rohr gespült werden, damit es chemisch neutral ist. Diese Spülung kann viel weniger aufwendig sein, wenn als Elektrolyt eine beim Normalbetrieb des Rohres 1 ohnehin vorhandene Chemikalie, zum Beispiel die in einem Druckwasserreaktor zur Reaktivitätsregelung verwendete Borsäure, eingesetzt wird.Before re-use, the tube must be rinsed so that it is chemically neutral. This flushing can be much less complex if a chemical which is already present during normal operation of the tube 1, for example the boric acid used in a pressurized water reactor for reactivity control, is used as the electrolyte.

Die Beseitigung der bei der Dekontaminierung anfallenden abgelösten Aktivitätsträger erfolgt bei der Erfindung durch eine Endlagerung der Filterkerze 12 mit bekannten Mitteln. Die Elektrolytflüssigkeit selbst kann für weitere Anwendungen erhalten bleiben.In the case of the invention, the detached activity carriers resulting from the decontamination are removed by a final storage of the filter candle 12 using known means. The electrolyte liquid itself can be retained for further applications.

Claims (13)

1. Verfahren zum Dekontaminieren metallischer Komponenten einer kerntechnischen Anlage durch Elektropolieren mit Hilfe von Elektroden und einer Elektrolytflüssigkeit, dadurch gekennzeichnet, daß die Elektrolytflüssigkeit während der Dekontaminationsbehandlung in einem Kreislauf über einen Filter geführt wird.1. A method for decontaminating metallic components of a nuclear plant by electropolishing with the aid of electrodes and an electrolyte liquid, characterized in that the electrolyte liquid is passed through a filter during the decontamination treatment in a circuit. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß ein Filter mit einer Porenweite von 1,5 µm oder weniger verwendet wird.2. The method according to claim 1, characterized in that a filter with a pore size of 1.5 microns or less is used. 3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß als Elektrolytflüssigkeit eine wäßrige Lösung mit einer Elektrolytkonzentration von höchstens 20 Gewichtsprozent verwendet wird.3. The method according to claim 1 or 2, characterized in that an aqueous solution with an electrolyte concentration of at most 20 percent by weight is used as the electrolyte liquid. 4. Verfahren nach Anspruch 3, dadurch gekennzeichnet, daß Phosphorsäure mit einer Konzentration von 8 bis 15 Gewichtsprozent verwendet wird.4. The method according to claim 3, characterized in that phosphoric acid is used at a concentration of 8 to 15 weight percent. 5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß mit Ultraschall eine Relativbewegung zwischen Elektrolytflüssigkeit und Komponente erzeugt wird.5. The method according to any one of claims 1 to 4, characterized in that a relative movement between the electrolyte liquid and the component is generated with ultrasound. 6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß durch hohen Elektrolytdurchsatz große Strömungsgeschwindigkeiten (>1m/s) mit einer erosiven Wirkung an der zu dekontaminierenden Oberfläche erzeugt werden.6. The method according to any one of claims 1 to 5, characterized in that high flow rates (> 1m / s) are generated with an erosive effect on the surface to be decontaminated by high electrolyte throughput. 7. Verfahren nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß die Elektrolytflüssigkeit mit Hilfe einer Elektrode längs der Komponente bewegt wird.7. The method according to any one of claims 1 to 6, characterized in that the electrolyte liquid is moved along the component with the aid of an electrode. 8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß eine trogförmige Elektrode verwendet wird, die mit einem Wischmittel gefüllt ist, und daß die Elektrolytflüssigkeit durch das Wischmittel geführt wird.8. The method according to claim 7, characterized in that a trough-shaped electrode is used, which is filled with a wiping agent, and that the electrolyte liquid is passed through the wiping agent. 9. Verfahren nach Anspruch 8, dadurch gekennzeichnet, daß als Wischmittel ein feinporiger Kunststoffschwamm aus Polyester oder Polypropylen verwendet wird.9. The method according to claim 8, characterized in that a fine-pored plastic sponge made of polyester or polypropylene is used as the wiping agent. 10. Verfahren nach Anspruch 8, dadurch gekennzeichnet, daß als Wischmittel ein saugfähiges Kunststoffvlies aus Polyester oder Polypropylen verwendet wird.10. The method according to claim 8, characterized in that an absorbent plastic fleece made of polyester or polypropylene is used as the wiping agent. 11. Verfahren nach einem der Ansprüche 1 bis 10, dadurch gekennzeichnet, daß die Komponente in einer Kunststoffwanne behandelt wird, aus der die Elektrolytflüssigkeit in den Filter geführt wird.11. The method according to any one of claims 1 to 10, characterized in that the component is treated in a plastic tub, from which the electrolytic liquid is fed into the filter. 12. Verfahren nach einem der Ansprüche 1 bis 11, dadurch gekennzeichnet, daß eine Komponente mit einem Hohlraum bis auf einen Auslaß für die Elektrolytflüssigkeit verschlossen ist.12. The method according to any one of claims 1 to 11, characterized in that a component is closed with a cavity except for an outlet for the electrolyte liquid. 13. Verfahren nach einem der Ansprüche 1 bis 12, dadurch gekennzeichnet, daß mehrere Elektroden mit einer gemeinsamen Spannungsquelle und einem gemeinsamen Filter parallel betrieben werden.13. The method according to any one of claims 1 to 12, characterized in that several electrodes are operated in parallel with a common voltage source and a common filter.
EP84113995A 1983-11-30 1984-11-19 Process for decontaminating metallic components of a nuclear plant Expired - Lifetime EP0144036B1 (en)

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DE19833343396 DE3343396A1 (en) 1983-11-30 1983-11-30 METHOD FOR DECONTAMINATING METALLIC COMPONENTS OF A NUCLEAR TECHNICAL PLANT
DE3343396 1983-11-30

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EP0144036A2 true EP0144036A2 (en) 1985-06-12
EP0144036A3 EP0144036A3 (en) 1985-07-17
EP0144036B1 EP0144036B1 (en) 1990-03-07

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EP (1) EP0144036B1 (en)
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FR2696864A1 (en) * 1992-10-13 1994-04-15 Gradient Rech Royallieu Method for anodic electro-decontamination of the interior of metallic hollow bodies, in particular of primary circuit tubes of a nuclear power plant, and installation for implementing said method.
WO1995034079A1 (en) * 1994-06-09 1995-12-14 Steringer, Anton Electrochemical method for decontaminating radioactively contaminated surfaces of metal components in nuclear plants
WO2011121291A1 (en) * 2010-04-01 2011-10-06 University Of Dundee Decontamination method

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FR2609352A1 (en) * 1987-01-05 1988-07-08 Commissariat Energie Atomique METHOD FOR DECONTAMINATING THE SURFACE OF A TRITIUM-CONTAMINATED METAL PART AND DEVICE USABLE THEREFOR
EP0274329A1 (en) * 1987-01-05 1988-07-13 Commissariat A L'energie Atomique Process for decontaminating the surface of a metallic component contaminated by tritium, and device for using said process
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FR2696864A1 (en) * 1992-10-13 1994-04-15 Gradient Rech Royallieu Method for anodic electro-decontamination of the interior of metallic hollow bodies, in particular of primary circuit tubes of a nuclear power plant, and installation for implementing said method.
WO1994009496A1 (en) * 1992-10-13 1994-04-28 Association Gradient Process for anodic electro-decontamination of hollow metal body interiors, especially the tubes of nuclear power station primary circuits and plant for carrying out said process
WO1995034079A1 (en) * 1994-06-09 1995-12-14 Steringer, Anton Electrochemical method for decontaminating radioactively contaminated surfaces of metal components in nuclear plants
WO2011121291A1 (en) * 2010-04-01 2011-10-06 University Of Dundee Decontamination method
GB2493295A (en) * 2010-04-01 2013-01-30 Univ Dundee Decontamination method
GB2493295B (en) * 2010-04-01 2015-06-10 Univ Dundee Decontamination method

Also Published As

Publication number Publication date
JPH0458919B2 (en) 1992-09-18
DE3481530D1 (en) 1990-04-12
EP0144036B1 (en) 1990-03-07
EP0144036A3 (en) 1985-07-17
DE3343396A1 (en) 1985-06-05
US4632740A (en) 1986-12-30
JPS60135799A (en) 1985-07-19

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