EP0555127B1 - Verfahren und Einrichtung zur Dekontaminierung eines gebrauchten nuklearen Dampferzeugers - Google Patents

Verfahren und Einrichtung zur Dekontaminierung eines gebrauchten nuklearen Dampferzeugers Download PDF

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Publication number
EP0555127B1
EP0555127B1 EP19930400219 EP93400219A EP0555127B1 EP 0555127 B1 EP0555127 B1 EP 0555127B1 EP 19930400219 EP19930400219 EP 19930400219 EP 93400219 A EP93400219 A EP 93400219A EP 0555127 B1 EP0555127 B1 EP 0555127B1
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Prior art keywords
solution
tubes
decontaminating
bundle
sub
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French (fr)
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EP0555127A1 (de
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Michel Dubourg
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Areva NP SAS
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Framatome SA
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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
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
    • C23G1/08—Iron or steel
    • C23G1/085—Iron or steel solutions containing HNO3
    • 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
    • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
    • F22B37/48—Devices for removing water, salt, or sludge from boilers; Arrangements of cleaning apparatus in boilers; Combinations thereof with boilers
    • F22B37/483—Devices for removing water, salt, or sludge from boilers; Arrangements of cleaning apparatus in boilers; Combinations thereof with boilers specially adapted for nuclear steam generators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/02—Header boxes; End plates

Definitions

  • the present invention relates to a method and an installation for decontamination of the primary part of a used steam generator of a pressurized light water nuclear reactor.
  • This primary part comprises heat exchange elements, in particular a bundle of U-shaped tubes, the ends of which are connected to a water box and are fixed in a tubular plate.
  • the external surface of the tubes of this bundle is in contact with the supply water of a secondary circuit.
  • the bundle tubes are subjected to significant stresses which can damage the tubes and cause leaks between the primary part and the secondary circuit.
  • the out-of-service steam generator emits high activity radiation reaching several hundred curies. This radiation makes transporting the steam generator very difficult and expensive.
  • the highly radioactive steam generator must be subject to periodic radiological monitoring. To avoid having to monitor the generator steam out of service, and to remedy various storage problems, it was envisaged to dismantle this generator so as to reduce the volume of waste stored and to recover or recycle certain noble materials contained in the generator, in particular the Inconel usually used for the manufacture of bundle tubes.
  • the radioactive contamination of the steam generator is mainly distributed over the internal surface of the bundle tubes and the water box.
  • This contamination is due in particular to the presence of a layer of oxides containing radionuclides such as cobalt 60, cobalt 58 and manganese 54.
  • the contamination is concentrated in the thickness of the oxide layer (3 to 5 ⁇ m approximately) and superficially in the metal wall of the tubes over a thickness of approximately 3 ⁇ m.
  • the cerium solution constitutes an aggressive and strongly oxidizing chemical medium making it possible to erode the oxide layer and the contaminated surface.
  • the cerium is reduced to valence III and then regenerated to valence IV by injecting ozone into the solution.
  • the temperature of the solution must be below 60 ° C so as not to inadvertently destroy the injected ozone.
  • the object of the invention is to effectively decontaminate the primary part of a steam generator, especially the tube bundle, using a limited volume of decontamination solution, without creating an overpressure inside the primary part, without raising the temperature of the solution beyond 60 ° C and minimizing the volumes of waste products.
  • the primary part of the steam generator comprises a bundle of U-shaped tubes forming heat exchange elements, the tubes having their two ends connected respectively to the two compartments of a water box.
  • the bundle includes healthy tubes with open ends and defective tubes with plugged ends.
  • the liquid effluents are dried by first carrying out a centrifugation of the effluents so as to collect the insoluble waste from the effluents, and secondly by performing a vacuum evaporation of the effluents so as to collect the waste soluble.
  • the invention also relates to an installation for decontamination of the primary part of a used steam generator of a pressurized light water nuclear reactor, this primary part comprising a plurality of heat exchange elements, the installation comprising a closed-loop decontamination circuit, characterized in that the closed-loop decontamination circuit comprises removable connection means designed to be connected to the upstream and downstream ends of a subset of contaminated elements of the primary part of the steam generator, the circuit comprising a reservoir for circulation of an acid decontamination solution comprising valence cerium IV in the form of Ce4+ ions, and means for setting in place circulation of the solution connected between the reservoir and said removable connection means intended to be connected to the upstream end of the subset of contaminated elements of the primary part of the steam generator, the installation further comprising means of ozonation of the decontamination solution.
  • FIG. 1 shows a decontamination installation for implementing the method according to the invention, designated by the general reference 10.
  • This installation 10 is connected to contaminated elements of a primary part of a steam generator 12 out of service of a pressurized light water nuclear reactor.
  • This steam generator 12 is stored horizontally on cradles 14,16 in an enclosure (not shown in the figures) built on the site of the nuclear power plant from which the disused steam generator comes.
  • the primary part of the steam generator comprises a bundle 18 of U-shaped tubes made of Inconel.
  • the imaginary envelope of the bundle 18 is shown in dashed lines.
  • the ends of the tubes of the bundle 18 are fixed in a tubular plate 20 and are connected to a water box 22 comprising two compartments 22A, 22B.
  • the defective or suspect tubes of the bundle have their ends closed by plugs (not shown in the figures). Healthy bundle tubes have their ends open.
  • Each compartment 22A, 22B of the water box has a sleeve 23A, 23B for connection to primary water pipes.
  • the pipes were disconnected from the steam generator when it was taken out of service.
  • the sleeves 23A, 23B delimit orifices making it possible to introduce tools or equipment into the water box.
  • the installation 10 comprises a decontamination circuit 24 in which circulates in a closed loop a predetermined volume of decontamination solution, and means 25 for ozonation of the decontamination solution.
  • the circuit 24 includes a circulation tank 26 intended to contain at least part of the volume of decontamination solution, connected by a conduit 28 to the suction of a circulation pump 30.
  • the pump 30 is connected to a discharge conduit 32 connected by first removable connection means 34A, 34B to a first end of a subset of contaminated elements of the primary part of the steam generator. This subset of contaminated elements will be described in more detail later.
  • the circuit 24 also includes filtration means 36 supplied upstream by a conduit 38 connected by second removable connection means 34A, 34B at the second end of the subset of contaminated elements of the primary part of the steam generator.
  • the filtration means 36 are connected downstream by a conduit 40 to the circulation tank 26.
  • the filtration means 36 comprise two filters 42, 44 connected in parallel to the conduits 38 and 40. Each filter 42, 44 can be isolated from the circuit 24 by two valves 46, 48 arranged respectively upstream and downstream of the filter. A valve 50 bypass valve 42, 44 is connected between the conduits 38 and 40.
  • Means 52 for reversing the direction of circulation of the decontamination solution in the elements of the primary part connect the connection means 34A, 34B, on the one hand to the pipe 32 for discharging the pump 30 and on the other hand to the conduit 38 for supplying filters 42.44.
  • a valve 54 for bypassing the elements of the primary part is connected between the pipe 32 for discharging the pump 30 and the pipe 38 for supplying the filters 42, 44.
  • the ozonization means 25 comprise an ozonator 58 connected by a conduit 60 to an injection circuit 62 with a horn 64.
  • the ozonator 58 is connected to a reservoir 66 for supplying oxygen by a conduit 68 provided with a valve 69 with safety valve.
  • the injection circuit 62 comprises an injection pump 70, the suction of which is connected by a conduit 72 to the circulation tank 26 and the discharge of which is connected to the upstream end of the tube 64 by a conduit 74. downstream end of the tube 64 is connected by a conduit 76 to the circulation tank 26.
  • the conduits 72, 76 are respectively provided with valves 72A, 76A for isolating the means 25 for ozonation of the circuit 24 for circulation of the solution.
  • the installation 10 further comprises an auxiliary tank 78 connected to the circulation tank 26 by means 80 of content transfer.
  • This tank 78 the internal volume of which is substantially between 4 and 8 m3, is intended in particular for the preparation of the decontamination solution and for the intermediate storage of this solution after emptying the circulation tank 26.
  • the transfer means 80 comprise a conduit 82 connecting the circulation 26 and auxiliary 78 tanks to each other, provided with a reversible pump 84.
  • Agitation means 86 arranged in the auxiliary tank 78, make it possible in particular to mix the various constituents of the solution during its preparation.
  • auxiliary tank 78 The upper part of the auxiliary tank 78 is connected by a conduit 88 to means 90 for processing and evacuating the gaseous atmosphere contained in the tank above the level of liquid.
  • means 90 comprise a very high efficiency filter 92, of known type, connected in series with an ozone destroyer 94 opening into the open air.
  • the upper part of the circulation tank 26 is connected to the upper part of the auxiliary tank 78 by a conduit 96 provided with a valve 98 with safety valve, allowing the communication of the gaseous atmospheres of the two circulation tanks 26 and auxiliary 78 .
  • the lower part of the auxiliary reservoir 78 is connected to means 100 for draining the solution from the reservoir comprising a conduit 102 provided with a drainage valve 104.
  • a first end of the conduit 102 is connected to the bottom of the reservoir 78 and the second end of the conduit 102 is connected to a collector of liquid effluents, not shown in the figures.
  • the bundle 18 is subdivided into several sub-assemblies each comprising a substantially identical number of tubes.
  • each sub-assembly comprises approximately four hundred tubes and the entire bundle comprises approximately eight to nine tube sub-assemblies.
  • FIG. 1 There is shown in solid line in FIG. 1 an imaginary envelope delimiting a sub-assembly 106 of neighboring tubes.
  • connection means 34A, 34B comprise flexible conduits 108 whose first end is connected to the decontamination circuit 24 and whose second end is connected to a removable collector 110, shown in more detail in FIG. 2.
  • the conduits 108 pass through the orifices delimited by the sleeves 23A, 23B of the water box 22.
  • the collectors 110 have the general shape of a bell and are pressed against the tube plate with a gasket 20.
  • a first manifold 110 is disposed opposite the upstream ends and a second manifold 110 is disposed opposite the downstream ends of the tubes of the subassembly 106.
  • FIG. 2 shows one of the collectors 110 connected to the sub-assembly 106 of the bundle 18.
  • This manifold 110 is positioned to the right of the open ends of healthy tubes 18A and possibly to the right of the closed ends of defective tubes 18B.
  • the manifold 110 has a double edge 112, provided with a seal 114, delimiting a channel 116 for collecting possible leaks of the solution flowing through the manifold 110.
  • the channel 116 is connected by an orifice 118, formed through the wall of the manifold 110, to a conduit 120 for draining leaks.
  • This conduit 120 is connected to a collector of liquid effluents, not shown in the figures.
  • the collectors 110 are positioned in the compartments of the water box and pressed against the tube plate 20 by known means; in particular by means of a robot with an articulated carrier arm of the type sold under the name "ROMEO", placed in the water box.
  • the contour of the edge 112 of a manifold has a variable shape as a function of the arrangement of the ends of the tubes in the tube plate 20.
  • the outline of the manifold 110 has a substantially square shape or substantially complementary to the outline of the wall of the water box.
  • the subassemblies 106 of tubes of the bundle are successively decontaminated by connecting them one after the other to the decontamination circuit 24 by means of the collectors 110 described above.
  • a volume of approximately 3 m3 of decontamination solution is initially prepared in the auxiliary tank 78. mination. This volume of solution makes it possible in particular to fill all of the healthy tubes of the subassembly that we want to decontaminate.
  • the decontamination solution comprises nitric acid imposing a pH of the solution between 0.5 and 1, and cerium nitrate in a proportion of 8 to 10 g / l.
  • cerium nitrate can be replaced by cerium sulfate.
  • each sub-assembly of tubes is subjected to the following steps.
  • the solution is put into circulation in the decontamination circuit 24 in a closed loop by means of the circulation pump 30. This solution is circulated simultaneously through all the healthy tubes of the same sub-assembly for a duration T of between 6 and 24 hours.
  • the latter is supplied with ozone using the ozonization means 25 so as to maintain an ozone concentration in the solution of approximately 2.5 ppm.
  • the decontamination solution reacts with the oxide layer covering the internal surface of the tubes and with the surface layer of the metal constituting the tubes.
  • the valence II iron of the oxide layer is oxidized to valence III and the valence III chromium of the oxide layer is oxidized to chromium of valence VI according to the chemical reaction below: 6 Ce4+ + Cr2O3 + 11 H2O ⁇ 2 H2CrO4 + 6 Ce3+ + 6 H3O+ ⁇
  • the valence III iron and the valence VI chromium are dissolved in the solution.
  • the cerium of valence III (Ce3+ ions) is regenerated to valence IV cerium (Ce4+ ions) by ozone according to the chemical reaction below: 6 H3O+ + O3 + 6 Ce3+ ⁇ 6 Ce4+ + 9 H2O.
  • the temperature of the solution is maintained between 20 and 30 ° in order to ensure a sufficient lifetime of the ozone in the solution allowing it to regenerate the valence III cerium.
  • the speed of circulation of the decontamination solution in the tubes of the bundle is between 2.5 cm / s and 25 cm / s so as to prevent the contaminated particles torn from the surface of the tubes from being redeposited in these same tubes.
  • the Inconel wall of the bundle tubes is superficially eroded by the decontamination solution, which in particular produces Cr6+, Fe3+ and Ni+ ions.
  • the erosion of the internal surface of the bundle tubes is homogenized by reversing the direction of circulation of the decontamination solution in these tubes approximately every hour, using inversion means 52.
  • the filtration means 36 make it possible to capture a part of the particles torn from the primary part of the steam generator.
  • the pressure drop across the operational filter becomes too large, it switches from one filter to another by means of valves 46,48 for isolating the filters. It is also possible, after a certain period of circulation of the solution, to stop the filtration by isolating the filters from the decontamination circuit 24 and by opening the bypass valve 50.
  • the injection of ozone in the solution is stopped and the entire volume of solution contained in the bundle tubes and in the decontamination circuit 24 is emptied.
  • the decontamination solution is transferred to the auxiliary tank 78 by means of the pump 84, to be temporarily stored there.
  • the drainage valve 104 is opened and the solution is drained to an effluent collector liquids to be treated subsequently according to steps which will be described later.
  • the same solution can be used to decontaminate three subsets of about four hundred tubes. Decontamination of all the sound tubes in the bundle is carried out in approximately eight to nine passes using approximately 9 m3 of decontamination solution.
  • the tubes of the bundle sub-assembly are rinsed with a solution comprising demineralized water and oxygenated water.
  • the rinsing solution is introduced into the circulation tank 26 by known means, not shown in the figures, and the rinsing solution is circulated, by means of the circulation pump 30, through the healthy tubes of the subassembly. of the beam.
  • the hydrogen peroxide H2O2 reacts with the residual cerium of valence IV and reduces it to cerium of valence III, according to the following chemical reaction: H2O2 + 2 Ce4+ ⁇ 2 Ce3+ + O2 + 2 H+.
  • the rinsing solution After rinsing the tubes, the rinsing solution is drained by known means, not shown in the figures. The drained rinsing solution is collected in a liquid effluent collector to be treated subsequently according to steps which will be described later.
  • the decontamination circuit 24 After decontaminating and rinsing the healthy tubes of a sub-assembly of the bundle, the decontamination circuit 24 is connected to another sub-assembly of tubes to which the decontamination and rinsing steps described above are subjected.
  • the same decontamination solution is used or a new charge of the solution of substantially identical volume is prepared.
  • the two ends of the decontaminated healthy tubes are plugged and the caps of the defective tubes not decontaminated are pierced.
  • the two compartments 22A, 22B of the water box are connected by the defective open tubes.
  • the decontamination circuit 24 is connected to a sub-assembly 121 of the primary part of the steam generator comprising the two compartments 22A, 22B of the water box and the defective tubes uncorked from the bundle. For reasons of clarity, there is shown in Figure 3, a single defective tube 18B.
  • the sleeves 23A, 23B of the water box are closed by plates 122A, 122B provided with orifices for connection to conduits 108 connecting the water box to the decontamination circuit 24.
  • Decontamination of the water box and defective tubes is carried out by circulating through them a volume of decontamination solution of the type described above, following steps similar to those of decontamination of healthy tubes.
  • Faulty tubes present a risk of leakage at pressures in the region of 148 atm (150 bar). On the other hand, this risk of leakage is eliminated by circulating in the defective tubes the decontamination solution at a pressure substantially equal to atmospheric pressure.
  • the volume of solution used is a function of the total volume delimited by the compartments 22A, 22B of the water box and by the defective tubes which must be filled with solution.
  • the water box and the defective tubes are rinsed at the end of their decontamination with a rinsing solution of the type described above, following steps analogous to those of rinsing the healthy tubes of the bundle.
  • liquid effluents comprising the altered decontamination and rinsing solutions are collected in a collector, not shown in the figures, for further treatment.
  • An agent comprising oxygenated water is injected into the liquid effluents in order to reduce the Ce4+ ions in Ce3+ ions and subsequently store the cerium at valence III.
  • liquid effluents are then neutralized by injection of an agent comprising sodium hydroxide, then transferred to a drying installation (not shown in the figures) in which they are subjected to evaporation under vacuum.
  • the liquid effluents can be drained by first carrying out a centrifugation of the effluents so as to collect the insoluble waste, and secondly by carrying out a vacuum evaporation of the effluents so as to collect the soluble waste. .
  • the dried effluents are confined in known type enclosures suitable for the storage of low and medium activity nuclear waste. These enclosures can be concrete or metallic. In the example described, the total mass of dried effluents after decontamination of the entire bundle and the water box is approximately 1500 Kg.
  • the clogged filters used in the decontamination circuit are compacted. These filters collect around 50% of the solid particles torn off by the decontamination solution from the primary part of the steam generator.
  • the total volume of waste comprising compacted filters, dried effluents and containment concrete is approximately 5 m3.
  • the decontamination process according to the invention makes it possible to obtain a decontamination factor, defined by the ratio of the radiation field before decontamination to the radiation field after decontamination, greater than 1000 and may reach or even exceed 15000.
  • the decontamination solution may also contain sulfuric acid. You can also replace the nitric acid in the solution with sulfuric acid.
  • the decontamination of the elements of the primary water circuit is carried out without overpressure, at a temperature below 60 ° C.
  • the decontamination process according to the invention makes it possible to simultaneously decontaminate a group of tubes in the bundle and to reduce the volume of waste produced by the decontamination to a few cubic meters.
  • effluents produced can be stored in standard enclosures.
  • the decontamination solution that has been described has a composition suitable for optimally decontaminating a bundle of primary water tubes made of Inconel, but this solution can also be used to decontaminate stainless steel elements.
  • the decontamination process according to the invention can also be applied to a steam generator comprising a bundle of straight primary water tubes. These tubes are connected at each end to a tube plate and to a water box.
  • a tube sub-assembly is connected to the decontamination circuit by means of collectors fixed to the tubular plates of the ends of the bundle.

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Claims (23)

  1. Verfahren zur Dekontamination des Primärteils eines in einem Druck stehenden Leichtwasser-Kernreaktor verwendeten Dampferzeugers (12), wobei der Primärteil mehrere Wärmetauscherelemente (18A, 18B) aufweist, wobei das Verfahren umfaßt das Inkontaktbringen der kontaminierten Oberflächen des Primärteils mit einer sauren Dekontaminationslösung, die vierwertiges Cer in Form von Ionen Ce⁴⁺ aufweist, dadurch gekennzeichnet, daß die mehreren kontaminierten Wärmetauscherelemente in einige Unteranordnungen (106, 121) unterteilt werden und daß nacheinander an jeder Unteranordnung (106, 121) die folgenden Dekontaminationsschritte vorgenommen werden:
    - man läßt in einem geschlossenen Kreislauf ein vorbestimmtes Volumen der Dekontaminationslösung durch die kontaminierten Elemente (18A, 18B) der Unteranordnung (106, 121) für eine Dauer T zirkulieren, wobei der Lösung kontinuierlich Ozon zugegeben wird,
    - man läßt die Dekontaminationslösung ab,
    - man läßt eine Spüllösung in der Unteranordnung der kontaminierten Elemente zirkulieren,
    - man läßt die Spüllösung ab.
  2. Verfahren nach Anspruch 1, wobei das Primärteil des Dampferzeugers ein Bündel (18) von U-Röhren aufweist, die die Wärmetauscherelemente bilden, wobei die beiden Enden der Röhren jeweils mit einem Bereich (22A, 22B) eines Wassertanks (22) verbunden sind, wobei das Bündel (18) ordnungsgemäße Röhren (18A) aufweist, deren Enden offen sind, und fehlerhafte Röhren (18B), deren Enden durch Pfropfen verschlossen sind,
    dadurch gekennzeichnet, daß
    - man das Bündel (18) in mehrere Unteranordnungen (106) unterteilt, die jeweils eine Anzahl von im wesentlichen identischen Röhren aufweisen,
    - man die Dekontaminationslösung nacheinanderfolgend durch jede Unteranordnung (106) der Röhren gleichzeitig durch alle ordnungsgemäßen Röhren (18A) der gleichen Unteranordnung zirkulieren läßt,
    - und daß nach der Dekontamination aller ordnungsgemäßen Röhren' (18A) des Bündels
    - man die zwei Enden der dekontaminierten ordnungsgemäßen Röhren verschließt,
    - man die Pfropfen der fehlerhaften, nicht dekontaminierten Röhren durchstößt,
    - man die Dekontaminationslösung durch die zwei Bereiche (22A, 22B) des Wassertanks und durch die fehlerhaften Röhren (18B) zirkulieren läßt.
  3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, daß die Dekontaminationslösung Salpetersäure enthält, die der Lösung einen pH-Wert zwischen 0,5 und 1 verleiht, Cernitrat im Bereich zwischen 8 und 10 g/l, und Ozon einer Konzentration von 2,5 ppm.
  4. Verfahren nach Anspruch 2 oder 3, dadurch gekennzeichnet, daß die Temperatur der Lösung zwischen 20 und 30 °C liegt.
  5. Verfahren nach einem der Ansprüche 2 bis 4, dadurch gekennzeichnet, daß jede Unteranordnung (106) des Bündels etwa 400 Röhren aufweist, und daß das Volumen der Dekontaminationslösung etwa 3 m³ ist.
  6. Verfahren nach einem der Ansprüche 2 bis 5, dadurch gekennzeichnet, daß die Dauer T des Zirkulierens der Dekontaminationslösung in jeder Unteranordnung (106) der Röhren des Bündels zwischen 6 und 24 h liegt.
  7. Verfahren nach einem der Ansprüche 2 bis 6, dadurch gekennzeichnet, daß man die Strömungsrichtung der Dekontaminationslösung in den Röhren des Bündels (18) etwa stündlich umkehrt.
  8. Verfahren nach einem der Ansprüche 2 bis 7, dadurch gekenhzeichnet, daß die Zirkulationsgeschwindigkeit der Dekontaminationslösung in den Röhren des Bündels (18) zwischen 2,5 cm/s und 25 cm/s liegt.
  9. Verfahren nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, daß die Spüllösung voll entsalztes Wasser und Wasserstoffperoxid aufweist.
  10. Verfahren nach einem der Ansprüche 1 bis 9, dadurch gekennzeichnet, daß die in den kontaminierten Elementen des Primärteils zirkulierende Dekontaminationslösung durch zumindest einen Filter (42, 44) gefiltert wird, der die von der Lösung im Primärteil losgelösten Partikel auffängt, solange der Druckverlust am Filter (42, 44) kleiner als ein vorbestimmter Wert ist.
  11. Verfahren nach einem der Ansprüche 1 bis 10, dadurch gekenmnzeichnet, daß man die flüssigen Rückstände, die die Dekontaminationslösung und die Spüllösung umfassen, nach ihrer Verwendung im Primärteil behandelt, indem die folgenden Schritte vorgenommen werden:
    - man leitet in die flüssigen Rückstände ein Mittel ein, das die Ce⁴⁺-Ionen auf Ce³⁺-Ionen reduziert,
    - man leitet ein Mittel ein, das die Lösung neutralisiert,
    - man trocknet die flüssigen Rückstände,
    - man schließt die getrockneten Rückstände in einer Hülle ein, die für die Lagerung von Rückständen schwacher und mittlerer Radioaktivität geeignet ist.
  12. Verfahren nach Anspruch 11, dadurch gekennzeichnet, daß das Mittel zur Reduktion der Ce⁴⁺-Ionen zu Ce³⁺-Ionen Wasserstoffperoxid umfaßt.
  13. Verfahren nach Anspruch 11 oder 12, dadurch gekennzeichnet, daß das Mittel zur Neutralisierung der Rückstände Natriumcarbonat aufweist.
  14. Verfahren nach einem der Ansprüche 11. bis 13, dadurch gekennzeichnet, daß man die flüssigen Rückstände durch Unterdruckverdampfung trocknet.
  15. Verfahren nach einem der Ansprüche 11 bis 13, dadurch gekennzeichnet, daß man die flüssigen Rückstände trocknet, indem man zuerst die Rückstände derart zentrifugiert, daß die unlöslichen Rückstände der Rückstände aufgefangen werden, und daß als zweites eine Unterdruckverdampfung der Rückstände so durchgeführt wird, daß die löslichen Rückstände aufgefangen werden.
  16. Einrichtung zur Dekontamination des Primärteils eines Dampferzeugers (12), der in einem unter Druck stehenden Leichtwasser-Kernreaktor verwendet wird, wobei der Primärteil mehrere Wärmetauscherelemente (18A, 18B) aufweist, wobei die Einrichtung einen eine geschlossene Schleife bildenden Dekontaminationskreislauf aufweist, dadurch gekennzeichnet, daß der eine geschlossene Schleife bildende Dekontaminationskreislauf (24) veränderliche Verbindungseinrichtungen (34A, 34B) aufweist, die zur Verbindung mit stromaufwärtigen und stromabwärtigen Enden einer Unteranordnung (106, 121) kontaminierter Elemente des Primärteils des Dampferzeugers vorgesehen sind, wobei der Kreislauf (24) einen Zirkulationsbehälter (26) für eine saure Dekontaminationslösung aufweist, die vierwertiges Cer in Form von Ionen Ce⁴⁺ aufweist, und eine Einrichtung (30) zum Zirkulieren der Lösung, die zwischen den Behälter (26) und die veränderliche Verbindungseinrichtung gelegt ist, die dazu vorgesehen ist, mit dem stromaufwärtigen Ende der Unteranordnung der kontaminierten Elemente (106, 121') des Primärteils des Dampferzeugers verbunden zu werden, wobei die Einrichtung außerdem eine Einrichtung (25) aufweist, um die Dekontaminationslösung mit Ozon zu versehen.
  17. Einrichtung nach Anspruch 16, dadurch gekennzeichnet, daß der eine geschlossene Schleife bildende Dekontaminationskreislauf (24) eine Filtereinrichtung (36) aufweist, die sich befindet zwischen dem Zirkulationsreservoir (26) und der veränderlichen Verbindungseinrichtung, die dazu vorgesehen ist, mit dem stromabwärtigen Ende der Unteranordnung der kontaminierten Elemente (106, 121) des Primärteils verbunden zu werden.
  18. Einrichtung nach Anspruch 16 oder 17, dadurch gekennzeichnet, daß sie eine Einrichtung zum Umkehren der Strömungsrichtung der Dekontaminationslösung in der Unteranordnung der kontaminierten Elemente (106, 121) des Primärteils des Dampferzeugers aufweist.
  19. Einrichtung nach einem der Ansprüche 16 bis 18, dadurch gekennzeichnet, daß die Einrichtung (36) zur Filtrierung zumindest zwei Filter (42, 44) aufweisen, die parallel geschaltet sind, eine Einrichtung (46, 48) zum Isolieren eines jeden Filters vom Dekontaminationskreislauf und eine Einrichtung (50) zum Umgehen der Filter.
  20. Einrichtung nach einem der Ansprüche 16 bis 19, dadurch gekennzeichnet, daß die Einrichtung zum Zusetzen von Ozon (25) einen Ozonisator (58) aufweist, der mit einem Mischer (64) verbunden ist, dessen stromaufwärtiges Ende mit der Dekontaminationslösung durch eine Pumpe (70) versorgt wird, die mit dem Zirkulationsreservoir (26) verbunden ist, und dessen stromabwärtiges Ende mit dem Zirkulationsreservoir (26) verbunden ist.
  21. Einrichtung nach einem der Ansprüche 16 bis 20, dadurch gekennzeichnet, daß sie ein Hilfsreservoir (78) aufweist, das mit dem Zirkulationsreservoir (26) über eine Einrichtung zum Übertragen des Inhalts verbunden ist, das insbesondere für die Vorbereitung der Dekontaminationslösung und zum Zwischenspeichern der Dekontaminationslösung nach dem Ablassen des Zirkulationsreservoirs (26) vorgesehen ist.
  22. Einrichtung nach einem der Ansprüche 16 bis 21, wobei der Primärteil des Dampferzeugers ein Bündel (18) von U-Röhren aufweist, die die Wärmetauscherelemente bilden, dadurch gekenmnzeichnet, daß die Verbindungseinrichtung (34A, 34B) zwei veränderliche Sammler (110) aufweisen, die dazu vorgesehen sind, jeweils mit stromaufwärtigen und stromabseitigen Enden einer Unteranordnung (106) der Röhren des Bündels im Dekontaminationskreislauf (24) verbunden zu werden, wobei der Rand (112) der Sammler (110) dazu vorgesehen ist, beschichtet zu werden, um dicht an einem Rohrboden (20) zur Befestigung der Enden der Röhren des Bündels anzuliegen, wobei von den beiden Sammlern (110) der eine bei den stromaufwärtigen Enden und der andere bei den stromabwärtigen Enden der Röhren der Unteranordnung (106) angebracht ist.
  23. Einrichtung nach Anspruch 22, dadurch gekennzeichnet, daß die Sammler (110) der Verbindung jeweils einen doppelten Rand (112) aufweisen, der einen Kanal (116) begrenzt, der zum Auffangen von möglicherweise auftretender Leckflüssigkeit der im Kollektor (110) zirkulierenden Lösung vorgesehen ist, wobei der Kanal mit einem Sammler für Leckflüsisigkeiten verbunden ist.
EP19930400219 1992-02-03 1993-01-28 Verfahren und Einrichtung zur Dekontaminierung eines gebrauchten nuklearen Dampferzeugers Expired - Lifetime EP0555127B1 (de)

Applications Claiming Priority (2)

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FR9201171A FR2687005B1 (fr) 1992-02-03 1992-02-03 Procede et installation de decontamination de la partie primaire d'un generateur de vapeur usage d'un reacteur nucleaire a eau ordinaire sous pression.
FR9201171 1992-02-03

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FR2706217A1 (fr) * 1993-06-08 1994-12-16 Framatome Sa Procédé de remise en état d'un échangeur de chaleur de centrale nucléaire, notamment d'un échangeur de chaleur de circuit auxiliaire de refroidissement d'un réacteur nucléaire à l'arrêt.
FR2710182B1 (fr) * 1993-09-16 1995-12-08 Framatome Sa Procédé de démantèlement d'un générateur de vapeur usagé d'un réacteur nucléaire à eau sous pression.
FR2711898B1 (fr) * 1993-11-05 1995-12-29 Oreal Pinceau pour appliquer du vernis à ongles, ou un produit analogue.
FR2730641B1 (fr) * 1995-02-20 1997-03-14 Commissariat Energie Atomique Mousse de decontamination a l'ozone, et procede de decontamination utilisant cette mousse
DE19541501A1 (de) * 1995-11-07 1997-05-15 Siemens Ag Verfahren und Vorrichtung zum Entsorgen eines nuklearen Dampferzeugers
BE1011754A3 (fr) * 1998-02-20 1999-12-07 En Nucleaire Etabilissement D Procede et installation de decontamination de surfaces metalliques.
DE102016122513B3 (de) 2016-11-22 2017-03-16 Areva Gmbh Verfahren zum Demontieren eines Dampferzeugers oder Wärmetauschers, insbesondere eines Dampferzeugers oder Wärmetauschers eines Kernkraftwerks
CN112481624B (zh) * 2019-09-11 2024-03-22 中冶南方工程技术有限公司 酸再生系统浓缩酸管路自动净化装置及其使用方法

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US4217192A (en) * 1979-06-11 1980-08-12 The United States Of America As Represented By The United States Department Of Energy Decontamination of metals using chemical etching
US4963293A (en) * 1983-06-07 1990-10-16 Westinghouse Electric Corp. Flow control method for decontaminating radioactively contaminated nuclear steam generator
SE451915B (sv) * 1984-03-09 1987-11-02 Studsvik Energiteknik Ab Forfarande for dekontaminering av tryckvattenreaktorer
ZA853531B (en) * 1984-05-29 1985-12-24 Westinghouse Electric Corp Ceric acid decontamination of nuclear reactors
US4676201A (en) * 1984-07-25 1987-06-30 Westinghouse Electric Corp. Method and apparatus for removal of residual sludge from a nuclear steam generator
SE465142B (sv) * 1988-08-11 1991-07-29 Studsvik Ab Foerfarande foer dekontaminering av korrosionsprodukter i kaernkraftsreaktorer

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HUT66988A (en) 1995-01-30
HU213081B (en) 1997-02-28
CZ11093A3 (en) 1993-08-11
SK5693A3 (en) 1993-09-09
DE69302290D1 (de) 1996-05-30
FR2687005B1 (fr) 1994-10-21
EP0555127A1 (de) 1993-08-11
HU9300267D0 (en) 1993-06-28
BG97390A (en) 1994-03-24
DE69302290T2 (de) 1996-09-19
FR2687005A1 (fr) 1993-08-06

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