EP0675973B1 - Verfahren zum auflösung von auf einem metallsubstrat aufgeschiedenen oxyde - Google Patents

Verfahren zum auflösung von auf einem metallsubstrat aufgeschiedenen oxyde Download PDF

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Publication number
EP0675973B1
EP0675973B1 EP94902858A EP94902858A EP0675973B1 EP 0675973 B1 EP0675973 B1 EP 0675973B1 EP 94902858 A EP94902858 A EP 94902858A EP 94902858 A EP94902858 A EP 94902858A EP 0675973 B1 EP0675973 B1 EP 0675973B1
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Prior art keywords
reducing
oxidizing
oxides according
dissolving oxides
dissolving
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EP94902858A
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French (fr)
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EP0675973A1 (de
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Henri Spychala
Didier Noel
Jacques Gregoire
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Electricite de France SA
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Electricite de France 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
    • 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
    • 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
    • C23G1/088—Iron or steel solutions containing organic acids
    • 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
    • C23G1/14—Cleaning or pickling metallic material with solutions or molten salts with alkaline solutions
    • C23G1/19—Iron or steel

Definitions

  • the present invention relates to a method for dissolving oxides deposited on a metal substrate, this method being intended more particularly for the decontamination of metal parts, contaminated during their exposure in a hot zone.
  • radioactivity in the primary circuit is due to corrosion products which are activated in the reactor core, then which are precipitated and incorporated into the oxide, deposited in the form of successive layers, on the walls of the circuit.
  • the radioactive materials are mainly 60 Co, 58 Co, 51 Cr, 54 Mn, 59 Fe, 121 Sb, 124 Sb, 110 mAg.
  • the deposition process is cumulative and in a few years, the parts of the primary circuit have a very high radioactivity.
  • the problem is particularly acute at the level of the water box of the steam generator, part of the primary circuit in which interventions are the longest. It is therefore very important to have a process for rapidly decontaminating components or parts of the primary circuit on which the personnel must intervene, during cold stops.
  • Decontamination consists in eliminating the layers of deposit formed on the walls of the circuit during its use. To decontaminate, it is necessary to remove not only the external layer of oxide which is generally thin and not very adherent, but also the internal, compact and strongly adherent layer on the metal walls.
  • Chemical decontamination consists in using chemical solutions to dissolve the oxide layer adhering to the metal walls, then to treat the collected solutions, so as to concentrate them and obtain only low volume waste. This waste can then be easily stored in landfill systems suitable for this purpose, that is to say protected and where the radioactivity is controlled.
  • the oxides formed on the walls are generally very rich in iron and chromium. However, chromium oxide and especially spinels are difficult to dissolve.
  • the method optionally includes a subsequent step of treating the effluents obtained at the end of the reducing and oxidizing attacks, by passing these effluents over a cation exchange resin.
  • This process is not effective enough to completely remove the oxide layers deposited on the walls of the treated metal pipes.
  • the reducing phase will dissolve these oxides the less they are loaded with chromium. As a result, a greater amount of chromium oxide remains in this case on the walls, after the reducing phase, thus making decontamination imperfect.
  • the efficiency of the process is greatly reduced by the excessively high pH value of the reducing phase which decreases the solubility of the spinels loaded with chromium.
  • a complexing agent such as oxalic acid constitutes an important source of pollution since this acid remains partly trapped in the state of cationic complexes on the cation exchange resins, after the treatment of the effluents or in the sludge in the case of treatment on an evaporator.
  • the oxidative and reducing attacks are carried out at pH values too high to be effective.
  • the second step of the process simply makes it possible to reduce the residual MnO 4 K and the MnO 2 formed during the oxidizing phase.
  • Document FR 2 590 716 also discloses a process for decontaminating the walls of nuclear reactors, in particular the walls of the primary circuit of nuclear reactors with a pressurized water circuit. This process consists in increasing the efficiency of renewal of the solution by the emission of ultrasound throughout the duration of the oxidizing and reducing phases. Moreover, the effectiveness of ultrasound appears especially in the oxidizing phase where the penetration of the solution in depth plays a greater role than in the reducing phase.
  • This method also has a number of drawbacks. Only the surfaces directly in the vicinity of the ultrasonic probes are well decontaminated. In addition, the positioning of the ultrasonic probes is difficult to set up. It may even be impossible with certain surface profiles to be decontaminated (pipes of small diameters, presence of elbows, ).
  • the object of the invention is to solve the drawbacks mentioned above.
  • the invention relates to a method for dissolving oxides deposited on a metal substrate not containing Inconel.
  • the oxidative attack is carried out at a pH of between 1.8 and 2.
  • the oxidative attack is carried out using a solution comprising a permanganate anion and sodium hydroxide, at a pH greater than or equal to 12, this pH being maintained throughout the duration of the oxidative attack.
  • the oxidative attack is thus adapted according to the nature of the substrate.
  • the reducing agent is chosen from dehydroascorbic acid, aldols, diacids, reducing sugars or better still ascorbic acid.
  • the permanganate anion is introduced in the form of potassium permanganate.
  • the pH of the oxidizing phase is maintained at a sufficiently acidic level so as to increase the efficiency of the oxidizing phase. Maintaining the pH is ensured by the addition of nitric acid. Furthermore, at the start of each cycle, it is checked that the oxidizing power is always close to 100% and the permanganate anion is added accordingly.
  • the pH is further lowered to keep it sufficiently acid, using nitric acid so as to dissolve the oxides charged with chromium still present at the start of said reducing phase.
  • the reducing power is also maintained in the vicinity of 100% by adding reducer, at the start of each new cycle.
  • this method makes it possible to improve the decontamination factor Fd from 2.5 to 5 times compared with what was obtained with the methods of the prior art.
  • This decontamination factor corresponds to the ratio of the activities measured before and after treatment. More precisely, the quantity of radioactive elements present in the oxide is measured before and after decontamination.
  • This decontamination factor being increased, the process for dissolving oxides is effective in a shorter time than the processes of the prior art (here about 5 hours of oxidizing phase per cycle and 1 to 3 treatment cycles).
  • nitric acid is used in concentrations such that it is not corrosive to metallic substrates.
  • the use of nitric acid avoids the use of complexing agents, the drawbacks of which have been mentioned above.
  • the substrates on which the oxide deposits are likely to be carried out are mainly stainless steels of the 308 L or 316 L type, the Inconel 600 and stellites. These substrates can also be made of Inconel 82, bronze, copper, graphite, zircaloy 4 and titanium. Finally, these substrates can be seals.
  • the thickness of the deposits is generally close to 1 to 2 ⁇ m but can reach 8 to 10 ⁇ m.
  • a decontamination tank 1 in which is placed the metal substrate to be treated by the method according to the invention. Also shown are storage tanks 3 and 5, respectively, oxidizing and reducing solutions, a filter 7 and a cation exchange resin 9.
  • a filter of approximately 3 ⁇ m will be chosen for the oxidizing phase and 0 , About 45 ⁇ m for the reducing phase.
  • the oxidizing solution preferably contains approximately 0.5 to 1 g / l of nitric acid and 0.7 to 1 g / l of potassium permanganate or better still approximately 1 g / l of nitric acid and 1 g / l of permanganate potassium.
  • This oxidizing solution is therefore at a pH between 1.8 and 2.3.
  • This solution initially at a pH between 1.8 and 2, is mainly suitable for stainless steel substrates or more generally for all the substrates previously mentioned and not containing Inconel.
  • the oxidizing solution is alkaline. It then contains approximately between 0.5 and 1 g / l or better 1 g / l of potassium permanganate and at least 1 g / l or better approximately 1 g / l of sodium hydroxide.
  • the pH of this solution is greater than or equal to 12.
  • the reducing solution contains a reducing agent chosen from one of those mentioned above and nitric acid. It preferably contains approximately between 0.5 and 1 g / l of nitric acid and 0.7 to 2 g / l of ascorbic acid or better still 1 g / l of nitric acid and 1 g / l of acid ascorbic.
  • This reducing solution has a pH of less than 2.
  • the oxidizing solution is heated to a temperature between 80 and 85 ° C, preferably 80 ° C and it is injected through a line 11 into the decontamination tank 1.
  • the oxidative attack lasts approximately 5 hours during which the pH is maintained either at values between 1.8 and 2.3 and the permanganate content between 0.7 and 1 g / l in the case of an acid attack, or at values greater than or equal to 12 in the case of an alkaline attack, so that the efficiency of the oxidizing phase is maximum.
  • the pH is maintained between 1.8 and 2.
  • the pH directly influences the kinetics of the reaction.
  • the lower the pH the faster the kinetics of the reaction. Pores of the metal to be treated tend to be blocked by the MnO 2 formed during the reaction. So the faster the reaction, the more the metal can be treated before its pores are closed.
  • the oxidative attack generally begins at pH 1.8 and ends at pH 2, since the pH tends to increase during the reaction.
  • the oxidizing solution is recovered and conveyed via a line 13 to the filter 7, before being reintroduced into the storage tank 3 of oxidizing solution by a line 15.
  • the reducing solution is heated to a temperature between 80 and 85 ° C, preferably 80 ° C, then it is injected into the decontamination tank 1.
  • This reducing attack is maintained for about 5 hours and optionally added nitric acid to maintain the pH always below 2 and ascorbic acid to maintain a reducing power vis-à-vis iron III equivalent to an ascorbic acid content of between 0.7 and 1 g / l .
  • the reducing solution recovered after passing through the decontamination tank 1 is conveyed to the filter 7 and the cation exchange resin 9 then to the storage tank 5, via a line 17.
  • the residual radioactivity of the substrate is then measured to determine if a second cycle is necessary; in the affirmative, the operations which have just been described are repeated without having checked the pH and the oxidizing or reducing powers of the solutions used.
  • the oxides present on the substrates to be treated consist of a spinel composed of iron, chromium and nickel.
  • Nickel spinel dissolving well in a reducing medium, we will only consider the case of chromium spinel (mixture of iron chromite and magnetite).
  • This oxidation reaction makes it possible to dissolve the chromium.
  • the oxidation is preferably carried out in an alkaline medium and the chemical reaction is as follows: 7MnO 4 - + 3FeCr 2 O 4 + 8OH - ----- 7MnO 2 + 6CrO 4 2- + 3FeO 3 H 2 - + H 2 O (2)
  • MnO 2 is formed , either directly in an alkaline medium, or indirectly in an acidic medium, from the oxidation of water catalyzed by the Mn 2+ ions, according to the following reaction: MnO 4 - + H + ---- MnO 2 + 3 / 4O 2 + 1 / 2H 2 O (3)
  • the MnO 2 formed tends to deposit on the walls and to limit the efficiency of the oxidative phase over time. It is therefore necessary to start the oxidative attack at low pH so as to have a rapidly effective attack and to be able to limit the duration of this phase to approximately 5 or 6 hours. In the prior art, the oxidative phases lasted approximately 15 hours, because the oxidative phase was less effective at the start of the attack.
  • the decontamination of oxidizing and reducing solutions is carried out using a cationic resin 9.
  • the oxidizing phase makes it possible to recover approximately 10% of the radioactive materials while the reducing phase makes it possible to recover approximately 90%. Consequently, it is above all this latter solution which can be decontaminated on the resin 9, possibly after each cycle.
  • the cation exchange resin also lowers the pH. The oxidizing solution will not be decontaminated until after the last cycle on a cation exchange resin.
  • the resins 9 and 18 are generally formed by a single resin.
  • the radioactive materials and the cations were retained on these resins.
  • the oxidizing and reducing solutions are then extracted from their respective storage tanks 3 and 5 and conveyed by pipes 19 to a mixing tank 21. After treatment of the mixture on cation exchange resin or evaporator, the final solution obtained is no longer radioactive and has a low COD in compliance with current pollution standards, which allows its elimination to the site's disposal facilities.
  • the cation exchange resins 9 and 18 on which the radioactive elements are concentrated are either transferred to the reservoirs storage site for used resins, then treated by the PRECED process (registered trademark), or packaged in appropriate drums and treated by the COMET process (registered trademark). These two methods consist in mixing the ion exchange resins with a polymer which, once solidified, ensures the stability of the mixture.
  • Test 1 measurements of the decontamination factor (Fd) :
  • the decontamination factor Fd was measured for several substrates of the stainless steel or Inconel type, by carrying out radioactivity measurements before and after a given treatment. These treatments were carried out with various oxidizing and reducing solutions, at different concentrations and at different pHs. The results are given in Table 1 below.
  • Test 2 measurements of the quantities of chromium and iron in the reducing phase :
  • Tests numbers 4 and 5 corresponding to the process according to the invention show that the Cr / iron ratio is significantly increased compared to the process of the prior art. This means that the lowering of the pH in the reducing phase has made it possible to dissolve oxides still charged with chromium present in the reducing phase and which would not have been at a higher pH.
  • Test 3 corrosion measurements of the substrate :
  • Tests numbers 5 and 6 correspond to those carried out by the method according to the invention. It is noted that the loss of thickness measured in microns, after 5 hours is very low compared to what could be obtained in tests 3 and 4 corresponding to the process of the prior art described in the patent application EP 0 406 098. This trend is also confirmed after 20 hours since the loss of thickness hardly changes.
  • chromium content of stainless steel and Inconel being greater than 12%, in an aqueous medium a passive layer is created, formed of a mixture of oxides and hydroxides of iron and chromium, with bonds under bridge shape.
  • the compounds thus created are relatively stable and protective with respect to the NO 3 - and H + ions.
  • the corrosion of the base metal in the reducing phase depends on the prior oxidation. In all cases, it remains very low (maximum value of 0.1 ⁇ m in 20 hours) and does not change significantly until the first hours.

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  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
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  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Treatment Of Water By Oxidation Or Reduction (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
  • Oxygen, Ozone, And Oxides In General (AREA)

Claims (16)

  1. Verfahren zur Auflösung von Oxiden, die an einem metallischen Substrat, welches kein Inconel enthält, abgeschieden sind, dadurch gekennzeichnet, daß es mindestens einen Zyklus umfaßt, bestehend aus:
    a) Durchführen eines oxidierenden Angriffs bei einer Temperatur zwischen 80 und 85 °C mittels einer Lösung, die ein Permanganatanion und Salpetersäure enthält, bei einem pH zwischen 1,8 und 2,3, wobei dieser pH während der gesamten Dauer des oxidierenden Angriffs beibehalten wird,
    b) Durchführen eines reduzierenden Angriffs mittels einer Lösung, die ein Reduktionsmittel und Salpetersäure umfaßt, bei einem pH von weniger als 2 und bei einer Temperatur zwischen 80 und 85 °C.
  2. Verfahren zur Auflösung von Oxiden nach Anspruch 1, dadurch gekennzeichnet, daß der oxidierende Angriff bei einem pH zwischen 1,8 und 2 durchgeführt wird.
  3. Verfahren zur Auflösung von Oxiden, die an einem metallischen Substrat, welches mindestens einen aus Inconel gefertigten Teil umfaßt, abgeschieden sind, dadurch gekennzeichnet, daß es mindestens einen Zyklus umfaßt, bestehend aus:
    a) Durchführen eines oxidierenden Angriffs mittels einer Lösung, die ein Permanganatanion und Natriumhydroxid umfaßt, bei einem pH größer oder gleich 12, wobei dieser pH während der gesamten Dauer des oxidierenden Angriffs beibehalten wird,
    b) Durchführen eines reduzierenden Angriffs mittels einer Lösung, die ein Reduktionsmittel und Salpetersäure umfaßt, bei einem pH von weniger als 2 und bei einer Temperatur zwischen 80 und 85 °C.
  4. Verfahren zur Auflösung von Oxiden nach Anspruch 1 oder 3, dadurch gekennzeichnet, daß das Reduktionsmittel Ascorbinsäure ist.
  5. Verfahren zur Auflösung von Oxiden nach Anspruch 1 oder 3, dadurch gekennzeichnet, daß das Permanganatanion in Form von Kaliumpermanganat eingebracht wird.
  6. Verfahren zur Auflösung von Oxiden nach den Ansprüchen 1 und 5, dadurch gekennzeichnet, daß die oxidierende Lösung ungefähr zwischen 0,5 und 1 g/l Salpetersäure und zwischen 0,7 und 1 g/l Kaliumpermanganat enthält.
  7. Verfahren zur Auflösung von Oxiden nach Anspruch 6, dadurch gekennzeichnet, daß die oxidierende Lösung ungefähr 1 g/l Salpetersäure und 1 g/l Kaliumpermanganat enthält.
  8. Verfahren zur Auflösung von Oxiden nach den Ansprüchen 3 und 5, dadurch gekennzeichnet, daß die oxidierende Lösung ungefähr zwischen 0,5 und 1 g/l Kaliumpermanganat und mindestens 1 g/l Natriumhydroxid enthält.
  9. Verfahren zur Auflösung von Oxiden nach Anspruch 8, dadurch gekennzeichnet, daß die oxidierende Lösung ungefähr 1 g/l Kaliumpermanganat und 1 g/l Natriumhydroxid enthält.
  10. Verfahren zur Auflösung von Oxiden nach Anspruch 4, dadurch gekennzeichnet, daß die reduzierende Lösung ungefähr 0,5 bis 1 g/l Salpetersäure und 0,7 bis 2 g/l Ascorbinsäure enthält.
  11. Verfahren zur Auflösung von Oxiden nach Anspruch 10, dadurch gekennzeichnet, daß die reduzierende Lösung ungefähr 1 g/l Salpetersäure und 1 g/l Ascorbinsäure enthält.
  12. Verfahren zur Auflösung von Oxiden nach Anspruch 1, 2 oder 3, dadurch gekennzeichnet, daß die Dauer des oxidierenden Angriffs und des reduzierenden Angriffs jeweils ungefähr 5 Stunden beträgt.
  13. Verfahren zur Auflösung von Oxiden nach Anspruch 1, 2 oder 3, dadurch gekennzeichnet, daß die Temperatur der oxidierenden und reduzierenden Phasen nahe bei 80 °C liegt.
  14. Verfahren zur Auflösung von Oxiden nach Anspruch 1 oder 3, dadurch gekennzeichnet, daß vor einem neuen Zyklus die bereits verwendete reduzierende Lösung getrennt an einem Kationenaustauscherharz (9) behandelt wird, um an diesem die radioaktiven Elemente zu sammeln und den pH-Wert abzusenken.
  15. Verfahren zur Auflösung von Oxiden nach Anspruch 1 oder 3, dadurch gekennzeichnet, daß am Ende des letzten Behandlungszyklus die oxidierenden und reduzierenden Lösungen vermischt und in einem Verdampfer behandelt werden.
  16. Verfahren zur Auflösung von Oxiden nach Anspruch 1 oder 3, dadurch gekennzeichnet, daß am Ende des letzten Behandlungszyklus die oxidierenden und reduzierenden Lösungen vermischt und an einem Kationenaustauscherharz behandelt werden.
EP94902858A 1992-12-24 1993-12-23 Verfahren zum auflösung von auf einem metallsubstrat aufgeschiedenen oxyde Expired - Lifetime EP0675973B1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
FR9215722 1992-12-24
FR9215722A FR2699936B1 (fr) 1992-12-24 1992-12-24 Procédé de dissolution d'oxydes déposés sur un substrat métallique.
PCT/FR1993/001298 WO1994015001A2 (fr) 1992-12-24 1993-12-23 Procede de dissolution d'oxydes deposes sur un substrat metallique
CN94101670A CN1039037C (zh) 1992-12-24 1994-02-05 沉积在金属基体的氧化物的溶解方法

Publications (2)

Publication Number Publication Date
EP0675973A1 EP0675973A1 (de) 1995-10-11
EP0675973B1 true EP0675973B1 (de) 1997-08-06

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EP94902858A Expired - Lifetime EP0675973B1 (de) 1992-12-24 1993-12-23 Verfahren zum auflösung von auf einem metallsubstrat aufgeschiedenen oxyde

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EP (1) EP0675973B1 (de)
CN (1) CN1039037C (de)
DE (1) DE69312966T2 (de)
ES (1) ES2107798T3 (de)
FR (1) FR2699936B1 (de)
WO (1) WO1994015001A2 (de)

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US6454870B1 (en) * 2001-11-26 2002-09-24 General Electric Co. Chemical removal of a chromium oxide coating from an article
FR2850673B1 (fr) * 2003-02-04 2006-09-08 Electricite De France Procede de dissolution d'oxydes deposes sur un substrat metallique stellite
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CN112700900A (zh) * 2020-12-10 2021-04-23 中国辐射防护研究院 一种注锌反应堆部件放射性沉积氧化物的清洗方法
CN113737191A (zh) * 2021-08-19 2021-12-03 中国辐射防护研究院 一种低碳马氏体镍铬不锈钢的去污方法
EP4269657B1 (de) * 2022-04-29 2025-06-04 Technochim SA Verfahren zum lösen von metalloxiden aus life-science-ausrüstung
FR3143177B1 (fr) 2022-12-07 2024-12-13 Electricite De France Procédé de dissolution d’oxydes contenant une contamination en argent et cobalt sur un substrat métallique

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DE102013102331B3 (de) * 2013-03-08 2014-07-03 Horst-Otto Bertholdt Verfahren zum Abbau einer Oxidschicht
EP2787509A1 (de) 2013-03-08 2014-10-08 Horst-Otto Bertholdt Verfahren zum Abbau einer Oxidschicht

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ES2107798T3 (es) 1997-12-01
DE69312966T2 (de) 1998-02-19
CN1039037C (zh) 1998-07-08
WO1994015001A2 (fr) 1994-07-07
CN1106472A (zh) 1995-08-09
DE69312966D1 (de) 1997-09-11
EP0675973A1 (de) 1995-10-11
FR2699936A1 (fr) 1994-07-01
FR2699936B1 (fr) 1995-01-27
WO1994015001A3 (fr) 1994-10-13

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