EP0404928A1 - Method for radioactive decontamination of metal surfaces, particularly portions of primary circuits of water-cooled nuclear reactors - Google Patents

Method for radioactive decontamination of metal surfaces, particularly portions of primary circuits of water-cooled nuclear reactors

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Publication number
EP0404928A1
EP0404928A1 EP90902274A EP90902274A EP0404928A1 EP 0404928 A1 EP0404928 A1 EP 0404928A1 EP 90902274 A EP90902274 A EP 90902274A EP 90902274 A EP90902274 A EP 90902274A EP 0404928 A1 EP0404928 A1 EP 0404928A1
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EP
European Patent Office
Prior art keywords
solution
choh
water
decontamination
molar composition
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP90902274A
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German (de)
French (fr)
Inventor
Guy Résidence ''Les Muriers Blancs'' BRUNEL
Christine Chabrand
Jean-Paul Gauchon
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Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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Application filed by Commissariat a lEnergie Atomique CEA filed Critical Commissariat a lEnergie Atomique CEA
Publication of EP0404928A1 publication Critical patent/EP0404928A1/en
Ceased legal-status Critical Current

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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
    • 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
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/001—Decontamination of contaminated objects, apparatus, clothes, food; Preventing contamination thereof
    • G21F9/002—Decontamination of the surface of objects with chemical or electrochemical processes
    • G21F9/004—Decontamination of the surface of objects with chemical or electrochemical processes of metallic surfaces

Definitions

  • the present invention relates generally to the field of water-cooled nuclear reactors, in particular under pressure.
  • the primary circuit which carries the hot water leaving the core and which is most often made up largely of stainless steels (such as, for example, 304 L steel, 316 steel L and / or inconel 600) is internally covered with a layer of metal oxides enclosing radioelements which it is necessary to get rid of due to the radioactivity which they contain, which can be troublesome for the personnel during operations maintenance carried out when the reactor is shut down, see even when it is dismantled.
  • a tiny part of the metallic elements constituting the alloys of the primary circuit of a pressurized water reactor is in solution or in suspension in the water of this circuit in the form of oxides (corrosion products).
  • the repeated passage of these elements in the neutron flux of the reactor core activates them.
  • CITROX a chemical process known as the "CITROX” process is used to decontaminate the interior surface of the primary circuit of such a water reactor.
  • the "CITROX” process which uses an oxidizing pretreatment from potassium permanganate and sodium hydroxide, followed by a reducing phase with oxalic acid and citric acid at pH 3 to 4, is described in particular in the British document “Review of dilute chemical decontamination processes for water cooled in nuclear reactors" NP 1033, Research Project, 828-1, March 1979.
  • the present invention specifically relates to a radioactive decontamination process of metal surfaces just as simple and effective as the method of the prior art previously mentioned, but which has the very important additional advantage of being devoid of corrosive action on the surfaces to be decontaminated.
  • the solution has a molar composition of between 0.006 M and 0.1 M MnO 4 K and a molar composition of between 0.035 M and 0.1 M in nitric acid HNO 3 , the temperature being of the order of 80 ° C. and the duration of the pretreatment of the order of 24 h.
  • the reduction treatment phase in basic medium is carried out using a solution having a molar composition of between 0.05 M and 1 M in sodium gluconate and a molar composition of between 0.1 M and 1 hour in NaOH sodium hydroxide, the temperature of the solution being of the order of 80 ° C. and its pH being close to 11.
  • the alkali metal used is preferably chosen from sodium and potassium; as for the pH of the reducing treatment solution, it is preferably chosen between extreme values of the order of 9 and 13.
  • the temperature is for the oxidative pretreatment phase as well as for the reducing treatment phase, preferably of the order of 80 ° C to within plus or minus 5 ° C.
  • the durations of the oxidative pretreatment and the reduction treatment are generally of the same order of magnitude and vary, depending on the pickling desired, between 6 h and 24 h, it being understood that it is up to the skilled person to choose their duration in each particular case depending on the effect he seeks.
  • the intermediate rinsing between the two treatments using demineralized water can last, for example, an hour, but again, it is up to the skilled person to give it the precise value which he can consider to be the most effective.
  • the effectiveness of the decontamination process which is the subject of the invention stems, among other considerations, from the fact that the pretreatment weakens the oxide layer by oxidizing the insoluble compounds into soluble compounds, in particular by oxidizing chromium III, present in large quantities. and whose oxide is hardly soluble, in chromium VI whose bichromate ions are easily soluble.
  • alkaline gluconates are generally corrosion inhibitors.
  • the process which is the subject of the invention therefore has an additional and beneficial side effect with regard to the protection of the pickled surface from corrosion. It is exactly, as we have seen previously, the opposite of the "CITROX" process of the known art which had the essential drawback of accentuating the corrosion of the sensitive areas of the treated surface.
  • the alkaline gluconates are perfectly biodegradable and have no toxicity character, which avoids pollution of the environment and allows a very easy and less dangerous implementation of the decontamination process object of the invention.
  • the invention will be better understood by referring to the following description of two examples of implementation, which are given mainly by way of illustration and not limitation.
  • Type of surface treated 316 L stainless steel.
  • Duration of treatment 24 h.
  • Duration of treatment 24 h.
  • the erosion obtained is 1.28 ⁇ m, i.e.
  • Type of surface treated 316 L stainless steel.
  • Sodium gluconate solution of which molarity is equal to 0.5 M and soda whose molarity is equal to 0.1 M.
  • Duration of treatment 24 h.
  • the erosion obtained is 0.05 ⁇ m, or 0.04 g / m 2 .

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • General Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Electrochemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Food Science & Technology (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
  • Mechanical Engineering (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Detergent Compositions (AREA)

Abstract

Procédé de décontamination radioactive de surfaces métalliques, notamment de portions de circuits primaires de réacteurs nucléaires refroidis à l'eau, caractérisé en ce qu'il consiste à soumettre lesdites surfaces aux étapes successives de prétraitement oxydant à l'aide d'une solution de permanganate de potassium MnO4K et d'acide nitrique; rinçage à l'eau déminéralisée, puis traitement réducteur en milieu basique à l'aide d'une solution d'un gluconate de métal alcalin de formule HOH2C - CHOH - CHOH - CHOH - CHOH - COOM, dans laquelle M est un métal alcalin choisi parmi le Na et le K, et de soude NaOH.Process for radioactive decontamination of metal surfaces, in particular portions of primary circuits of water-cooled nuclear reactors, characterized in that it consists in subjecting said surfaces to successive oxidative pretreatment steps using a permanganate solution potassium MnO4K and nitric acid; rinsing with demineralized water, then reducing treatment in a basic medium using a solution of an alkali metal gluconate of formula HOH2C - CHOH - CHOH - CHOH - CHOH - COOM, in which M is a chosen alkali metal among Na and K, and sodium hydroxide NaOH.

Description

PROCEDE DE DECONTAMINATION RADIOACTIVE  RADIOACTIVE DECONTAMINATION PROCESS
DE SURFACE METALLIQUE, NOTAMMENT DE PORTIONS DE  OF METAL SURFACE, ESPECIALLY PORTIONS OF
CIRCUITS PRIMAIRES DE REACTEURS NUCLEAIRES REFROIDIS A L'EAU  PRIMARY CIRCUITS OF WATER-COOLED NUCLEAR REACTORS
La présente invention se rapporte d'une façon générale au domaine des réacteurs nucléaires refroidis à l'eau, notamment sous pression.  The present invention relates generally to the field of water-cooled nuclear reactors, in particular under pressure.
Lors du fonctionnement prolongé de tels réacteurs, le circuit primaire qui véhicule l'eau chaude sortant du coeur et qui est le plus souvent constitué en grande partie par des aciers inoxydables (tels que par exemple. l'acier 304 L, l'acier 316 L et/ou l'inconel 600) se recouvre intérieurement d'une couche d'oxydes métalliques enfermant des radioéléments dont il est nécessaire de se débarrasser en raison de la radioactivité qu'ils renferment, laquelle peut être gênante pour le personnel lors des opérations de maintenance effectuées à l'arrêt du réacteur, voir même lors du démantèlement de celui-ci.  During prolonged operation of such reactors, the primary circuit which carries the hot water leaving the core and which is most often made up largely of stainless steels (such as, for example, 304 L steel, 316 steel L and / or inconel 600) is internally covered with a layer of metal oxides enclosing radioelements which it is necessary to get rid of due to the radioactivity which they contain, which can be troublesome for the personnel during operations maintenance carried out when the reactor is shut down, see even when it is dismantled.
L'élimination ou la réduction d'une telle couche d'oxyde métallique renfermant des radioéléments constitue l'opération que l'on appelle la décontamination de la surface et c'est précisément l'objet essentiel de la présente invention que de fournir un tel procédé de décontamination plus performant que ceux de l'art antérieur.  The elimination or reduction of such a layer of metal oxide containing radioelements constitutes the operation known as surface decontamination and it is precisely the essential object of the present invention to provide such a decontamination process more efficient than those of the prior art.
Une partie infime des éléments métalliques constituant les alliages du circuit primaire d'un réacteur à eau sous pression, se trouve en solution ou en suspension dans l'eau de ce circuit sous forme d'oxydes (produits de corrosion). Le passage répété de ces éléments dans le flux neutronique du coeur du réacteur les active.  A tiny part of the metallic elements constituting the alloys of the primary circuit of a pressurized water reactor is in solution or in suspension in the water of this circuit in the form of oxides (corrosion products). The repeated passage of these elements in the neutron flux of the reactor core activates them.
Par le processus de solubilisation-précipitation dû au gradient de température existant dans le circuit primaire entre son point le plus chaud qui est de l'ordre de 350°C et son point le plus froid, à l'arrêt du réacteur qui peut descendre jusqu'à 40°C ou 50°C, il se forme un dépôt des produits de corrosion sur les parois des tuyauteries. By the solubilization-precipitation process due to the existing temperature gradient in the primary circuit between its hottest point which is around 350 ° C and its coldest point, when the reactor stops which can go down to 40 ° C or 50 ° C, it forms a deposit of corrosion products on the walls of the pipes.
Ce sont ces dépôts, renfermant des éléments activés tels que le manganèse 54, le cobalt 58 et le cobalt 60 (émetteurs de rayonnements ɤ ) qui peuvent être responsables, pour une grande part, de l'irradiation du personnel durant les travaux de maintenance du réacteur, et notamment du circuit primaire de ce dernier.  It is these deposits, containing activated elements such as manganese 54, cobalt 58 and cobalt 60 (emitters of radiation ɤ) which can be responsible, for a large part, for the irradiation of personnel during maintenance work on the reactor, and in particular of the primary circuit of the latter.
Il est donc important de pouvoir supprimer ou réduire cette activité parasite en éliminant la couche d'oxydes formée.  It is therefore important to be able to suppress or reduce this parasitic activity by eliminating the oxide layer formed.
Dans la technique connue jusqu'à ce jour, on utilise pour décontaminer la surface intérieure du circuit primaire d'un tel réacteur à eau, un procédé chimique connu sous le nom de procédé "CITROX". Le procédé "CITROX" qui met en oeuvre un prétraitement oxydant à partir de permanganate de potassium et de soude, suivi d'une phase réductrice avec de l'acide oxalique et de l'acide citrique à pH 3 à 4, est décrit notamment dans le document britannique "Review of dilute chemical decontamination processes for water cooled in nuclear reactors" NP 1033, Research Project, 828-1, Mars 1979.  In the technique known to date, a chemical process known as the "CITROX" process is used to decontaminate the interior surface of the primary circuit of such a water reactor. The "CITROX" process which uses an oxidizing pretreatment from potassium permanganate and sodium hydroxide, followed by a reducing phase with oxalic acid and citric acid at pH 3 to 4, is described in particular in the British document "Review of dilute chemical decontamination processes for water cooled in nuclear reactors" NP 1033, Research Project, 828-1, March 1979.
Cependant ce procédé connu, efficace au point de vue de la décontamination, peut provoquer une corrosion intergranulaire sur certaines zones sensibles de la surface traitée, qui peut être à l'origine d'une corrosion, certes localisée, mais relativement grave notamment pour des structures qui doivent être soumises à des températures et des pressions élevées (exemple : dans les REP : T 350°C; P 160 bars). La présente invention a précisément pour objet un procédé de décontamination radioactive de surfaces métalliques tout aussi simple et efficace que le procédé de l'art antérieur précédemment rappelé, mais qui possède l'avantage complémentaire très important d'être dépourvu d'action corrosive sur les surfaces à décontaminer. However, this known process, effective from the point of view of decontamination, can cause intergranular corrosion on certain sensitive areas of the treated surface, which can be the cause of corrosion, admittedly localized, but relatively serious in particular for structures. which must be subjected to high temperatures and pressures (example: in PWRs: T 350 ° C; P 160 bars). The present invention specifically relates to a radioactive decontamination process of metal surfaces just as simple and effective as the method of the prior art previously mentioned, but which has the very important additional advantage of being devoid of corrosive action on the surfaces to be decontaminated.
Ce procédé de décontamination se caractérise principalement en ce qu'il consiste à soumettre lesdites surfaces aux étapes successives de :  This decontamination process is mainly characterized in that it consists in subjecting said surfaces to the successive stages of:
prétraitement oxydant à l'aide d'une solution de permanganate de potassium MnO4K et d'acide nitrique ; oxidative pretreatment using a solution of potassium permanganate MnO 4 K and nitric acid;
- rinçage à l'eau déminéralisée, puis - rinsing with demineralized water, then
- traitement réducteur en milieu basique à l'aide d'une solution d'un gluconate de métal alcalin de formule HOH2C - CHOH - CHOH - CHOH - CHOH - COOM, dans laquelle M est un métal alcalin choisi parmi le Na et le K, et de soude NaOH. - reducing treatment in basic medium using a solution of an alkali metal gluconate of formula HOH 2 C - CHOH - CHOH - CHOH - CHOH - COOM, in which M is an alkali metal chosen from Na and K, and NaOH soda.
L'intérêt de ce procédé résulte essentiellement dans la phase de traitement réducteur en milieu basique à l'aide d'une solution de gluconate de métal alcalin. En effet, alors que le traitement réducteur de l'art antérieur était effectué en milieu fortement acide (pH de 3 à 4), le fait de travailler dans le procédé selon l'invention en milieu basique avec un sel de l'acide gluconique, permet d'utiliser au maximum la chelation qui résulte de l'existence des quatre fonctions hydroxyles de cet acide. lesquelles peuvent alors intervenir pleinement. En milieu acide en effet, seule la fonction carboxylique pourrait participer à la chelation, ce qui ne permettrait pas d'obtenir le plein pouvoir complexant du gluconate de métal alcalin utilisé. Selon une autre caractéristique du procédé, objet de l'invention, lors du prétraitement oxydant, la solution a une composition molaire comprise entre 0,006 M et 0,1 M en MnO4K et une composition molaire comprise entre 0,035 M et 0,1 M en acide nitrique HNO3, la température étant de l'ordre de 80°C et la durée du prétraitement de l'ordre de 24 h. The advantage of this process results essentially in the reducing treatment phase in basic medium using an alkali metal gluconate solution. Indeed, while the reducing treatment of the prior art was carried out in a strongly acid medium (pH 3 to 4), the fact of working in the process according to the invention in basic medium with a salt of gluconic acid, allows maximum use of the chelation which results from the existence of the four hydroxyl functions of this acid. which can then intervene fully. In an acid medium, in fact, only the carboxylic function could participate in chelation, which would not make it possible to obtain the full complexing power of the alkali metal gluconate used. According to another characteristic of the method, object of the invention, during the oxidative pretreatment, the solution has a molar composition of between 0.006 M and 0.1 M MnO 4 K and a molar composition of between 0.035 M and 0.1 M in nitric acid HNO 3 , the temperature being of the order of 80 ° C. and the duration of the pretreatment of the order of 24 h.
Selon l'invention, la phase de traitement réducteur en milieu basique est effectuée à l'aide d'une solution ayant une composition molaire comprise entre 0,05 M et 1 M en gluconate de sodium et une composition molaire comprise entre 0,1 M et 1 H en soude NaOH, la température de la solution étant de l'ordre de 80°C et son pH étant voisin de 11.  According to the invention, the reduction treatment phase in basic medium is carried out using a solution having a molar composition of between 0.05 M and 1 M in sodium gluconate and a molar composition of between 0.1 M and 1 hour in NaOH sodium hydroxide, the temperature of the solution being of the order of 80 ° C. and its pH being close to 11.
C'est grâce à l'adjonction de soude NaOH dans la solution que celle-ci a un caractère basique marqué (puisque le pH peut être voisin de 11) et que l'on obtient le maximum de pouvoir complexant des différentes fonctions hydroxyles contenues dans le gluconate de métal alcalin.  It is thanks to the addition of sodium hydroxide NaOH in the solution that the latter has a marked basic character (since the pH may be close to 11) and that the maximum complexing power of the various hydroxyl functions contained in alkali metal gluconate.
Selon l'invention et de façon pratique, le métal alcalin utilisé est choisi de préférence parmi le sodium et le potassium ; quant au pH de la solution de traitement réducteur, il est de préférence choisi entre des valeurs extrêmes de l'ordre de 9 et 13. Enfin, la température est pour la phase de prétraitement oxydant aussi bien que pour la phase de traitement réducteur, de préférence de l'ordre de 80°C à plus ou moins 5°C près.  According to the invention and in a practical manner, the alkali metal used is preferably chosen from sodium and potassium; as for the pH of the reducing treatment solution, it is preferably chosen between extreme values of the order of 9 and 13. Finally, the temperature is for the oxidative pretreatment phase as well as for the reducing treatment phase, preferably of the order of 80 ° C to within plus or minus 5 ° C.
Les durées du prétraitement oxydant et du traitement réducteur sont en général du même ordre de grandeur et varient, en fonction du décapage souhaité, entre 6 h et 24 h, étant bien entendu qu'il appartient à l'homme de métier de choisir leur durée dans chaque cas particulier en fonction de l'effet qu'il recherche. Le rinçage intermédiaire entre les deux traitements à l'aide d'eau déminéralisée peut durer par exemple une heure, mais là encore, il appartient à l'homme de métier de lui donner la valeur précise qu'il pourra considérer comme la plus efficace. The durations of the oxidative pretreatment and the reduction treatment are generally of the same order of magnitude and vary, depending on the pickling desired, between 6 h and 24 h, it being understood that it is up to the skilled person to choose their duration in each particular case depending on the effect he seeks. The intermediate rinsing between the two treatments using demineralized water can last, for example, an hour, but again, it is up to the skilled person to give it the precise value which he can consider to be the most effective.
L'efficacité du procédé de décontamination objet de l'invention, découle, entre autres considérations, du fait que le prétraitement fragilise la couche d'oxydes en oxydant les composés insolubles en composés solubles, notamment en oxydant le chrome III, présent en grande quantité et dont l'oxyde est difficilement soluble, en chrome VI dont les ions bichromates sont facilement solubles.  The effectiveness of the decontamination process which is the subject of the invention stems, among other considerations, from the fact that the pretreatment weakens the oxide layer by oxidizing the insoluble compounds into soluble compounds, in particular by oxidizing chromium III, present in large quantities. and whose oxide is hardly soluble, in chromium VI whose bichromate ions are easily soluble.
L'effet obtenu à l'aide du traitement réducteur en milieu basique à l'aide d'une solution de gluconate alcalin a été déjà expliqué précédemment et découle quant à lui directement de l'augmentation des pouvoirs complexants de ce corps en milieu basique.  The effect obtained using the reducing treatment in basic medium using an alkaline gluconate solution has already been explained previously and results directly from the increase in the complexing powers of this body in basic medium.
On peut noter en outre, que les gluconates alcalins sont d'une façon générale des inhibiteurs de corrosion. Le procédé, objet de l'invention présente par conséquent un effet secondaire supplémentaire et bénéfique quant à la protection de la surface décapée vis-à-vis de la corrosion. C'est exactement, comme on l'a vu précédemment, le contraire du procédé "CITROX" de l'art connu qui avait comme inconvénient essentiel d'accentuer la corrosion des zones sensibles de la surface traitée.  It may further be noted that the alkaline gluconates are generally corrosion inhibitors. The process which is the subject of the invention therefore has an additional and beneficial side effect with regard to the protection of the pickled surface from corrosion. It is exactly, as we have seen previously, the opposite of the "CITROX" process of the known art which had the essential drawback of accentuating the corrosion of the sensitive areas of the treated surface.
De plus, les gluconates alcalins sont parfaitement biodégradables et ne présentent aucun caractère de toxicité, ce qui évite la pollution de l'environnement et permet une mise en oeuvre très facile et moins dangereuse du procédé de décontamination objet de l'invention. De' toute façon l'invention sera mieux comprise en se référant à la description qui suit de deux exemples de mise en oeuvre, lesquels sont donnés surtout à titre illustratif et non limitatif. In addition, the alkaline gluconates are perfectly biodegradable and have no toxicity character, which avoids pollution of the environment and allows a very easy and less dangerous implementation of the decontamination process object of the invention. Anyway the invention will be better understood by referring to the following description of two examples of implementation, which are given mainly by way of illustration and not limitation.
Ces deux exemples concernent le traitement d'une surface contaminée d'acier inoxydable de nuance 316 L.  These two examples relate to the treatment of a contaminated surface of 316 L grade stainless steel.
EXEMPLE 1  EXAMPLE 1
Nature de la surface traitée: acier inoxydable 316 L.  Type of surface treated: 316 L stainless steel.
- Prétraitement oxydant en milieu acide:  - Oxidizing pretreatment in an acid medium:
Solution en KMnO4, dont la molarité est égale à 0,006 H et de HNO3 dont la molarité est égale à 0,035 M. Solution in KMnO 4 , whose molarity is equal to 0.006 H and of HNO 3 whose molarity is equal to 0.035 M.
Température de la solution : 80°C;  Solution temperature: 80 ° C;
Durée du traitement : 24 h.  Duration of treatment: 24 h.
- Rinçage à l'eau déminéralisée : 1 h.  - Rinsing with demineralized water: 1 h.
- Traitement réducteur :  - Reducing treatment:
Solution de gluconate de sodium, dont la molarité est égale à 1 M, et de soude dont la molarité est égale à 0,25 M.  Solution of sodium gluconate, whose molarity is equal to 1 M, and of sodium hydroxide whose molarity is equal to 0.25 M.
Température de la solution 80°C.  Solution temperature 80 ° C.
pH = 11  pH = 11
Durée de traitement : 24 h.  Duration of treatment: 24 h.
L'érosion obtenue est de 1,28 μm, soit The erosion obtained is 1.28 μm, i.e.
10 g/m2. 10 g / m 2 .
EXEMPLE 2  EXAMPLE 2
Nature de la surface traitée: acier inxoydable 316 L.  Type of surface treated: 316 L stainless steel.
- Prétraitement oxydant en milieu acide :  - Oxidizing pretreatment in an acid medium:
Solution et conditions identiques à celles de l'exemple 1,  Solution and conditions identical to those of Example 1,
- Rinçage à l'eau déminéralisée : 1h.  - Rinsing with demineralized water: 1h.
- Traitement réducteur :  - Reducing treatment:
Solution de gluconate de sodium, dont la molaraité est égale à 0,5 M et de soude dont la molarité est égale à 0,1 M. Sodium gluconate solution, of which molarity is equal to 0.5 M and soda whose molarity is equal to 0.1 M.
Température de la solution 80°C.  Solution temperature 80 ° C.
pH = 11.  pH = 11.
Durée du traitement : 24 h.  Duration of treatment: 24 h.
Résultat : l'érosion obtenue est de 0,05 μm, soit 0,04 g/m2. Result: the erosion obtained is 0.05 μm, or 0.04 g / m 2 .

Claims

REVENDICATIONS
1. Procédé de décontamination radioactive de surfaces métalliques, notamment de portions de circuits primaires de réacteurs nucléaires refroidis à l'eau, comportant deux étapes préliminaires de prétraitement oxydant à l'aide d'une solution de permanganate de potassium MnO4K et d'acide nitrique, puis de rinçage à l'eau déminéralisée, caractérisé en ce qu'il consiste à soumettre ensuite les dites surfaces à un traitement réducteur en milieu basique à l'aide d'une solution d'un gluconate de métal alcalin de formule HOH2C - CHOH - CHOH - CHOH - CHOH - COOM, dans laquelle M est un métal alcalin choisi parmi le Na et le K, et de soude NaOH. 1. Method for radioactive decontamination of metal surfaces, in particular portions of primary circuits of water-cooled nuclear reactors, comprising two preliminary stages of oxidative pretreatment using a solution of potassium permanganate MnO 4 K and nitric acid, then rinsing with demineralized water, characterized in that it consists in then subjecting said surfaces to a reducing treatment in basic medium using a solution of an alkali metal gluconate of formula HOH 2 C - CHOH - CHOH - CHOH - CHOH - COOM, in which M is an alkali metal chosen from Na and K, and sodium hydroxide NaOH.
2. Procédé de décontamination selon la revendication 1, caractérisé en ce que, lors du prétraitement oxydant, la solution a une composition molaire comprise entre 0,006 M et 0,1 M en MnO4K et une composition molaire comprise entre 0,035 M et 0,1 M en acide nitrique HNO3, la température étant de l'ordre de 80°C et la durée du prétraitement de l'ordre de 24 h. 2. Decontamination process according to Claim 1, characterized in that, during the oxidative pretreatment, the solution has a molar composition of between 0.006 M and 0.1 M MnO 4 K and a molar composition of between 0.035 M and 0, 1 M in nitric acid HNO 3 , the temperature being of the order of 80 ° C. and the duration of the pretreatment of the order of 24 h.
3. Procédé de décontamination selon l'une quelconque des revendications 1 et 2, caractérisé en ce que le traitement réducteur en milieu basique est effectué à l'aide d'une solution ayant une composition molaire comprise entre 0,05 M et 1 M en gluconate de sodium et une composition molaire comprise entre 0,1 M et 1 M en soude NaOH, la température de la solution étant de l'ordre de 80°C et son pH étant voisin de 11.  3. decontamination method according to any one of claims 1 and 2, characterized in that the reducing treatment in basic medium is carried out using a solution having a molar composition of between 0.05 M and 1 M in sodium gluconate and a molar composition of between 0.1 M and 1 M in sodium hydroxide NaOH, the temperature of the solution being of the order of 80 ° C. and its pH being close to 11.
4. Procédé de décontamination selon l'une quelconque des revendications 1 et 2, caractérisé en ce que le traitement réducteur en milieu basique est effectué à l'aide d'une solution ayant une composition molaire voisine de 0,5 M en glueonate de sodium et une composition molaire voisine de 0,1 M en soude NaOH, la température de la solution étant de l'ordre de 80ºC et son pH voisin de 11. 4. decontamination method according to any one of claims 1 and 2, characterized in that the reducing treatment in basic medium is carried out using a solution having a composition molar in the region of 0.5 M in sodium glueonate and a molar composition in the region of 0.1 M in sodium hydroxide NaOH, the temperature of the solution being of the order of 80ºC and its pH around 11.
EP90902274A 1989-01-19 1990-01-18 Method for radioactive decontamination of metal surfaces, particularly portions of primary circuits of water-cooled nuclear reactors Ceased EP0404928A1 (en)

Applications Claiming Priority (2)

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FR8900604A FR2641895A1 (en) 1989-01-19 1989-01-19 METHOD FOR RADIOACTIVE DECONTAMINATION OF METAL SURFACE, PARTICULARLY PORTIONS OF PRIMARY CIRCUITS OF WATER-COOLED NUCLEAR REACTORS
FR8900604 1989-01-19

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Families Citing this family (9)

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Publication number Priority date Publication date Assignee Title
FR2695839B1 (en) * 1992-09-23 1994-10-14 Commissariat Energie Atomique Reducing decontaminating gel and its use for surface decontamination, in particular of nuclear installations.
FR2696440B1 (en) * 1992-10-02 1995-02-10 Dumez Lyonnaise Eaux Method and installation for treating liquid effluents containing in particular pollutants in solution by membrane and gravity separations.
US5678232A (en) * 1995-07-31 1997-10-14 Corpex Technologies, Inc. Lead decontamination method
US5591270A (en) * 1995-07-31 1997-01-07 Corpex Technologies, Inc. Lead oxide removal method
US5814204A (en) * 1996-10-11 1998-09-29 Corpex Technologies, Inc. Electrolytic decontamination processes
JP3977963B2 (en) 1999-09-09 2007-09-19 株式会社日立製作所 Chemical decontamination method
FR2873848B1 (en) * 2004-08-02 2006-11-17 Tech En Milieu Ionisant Stmi S METHOD FOR DECONTAMINATING LEAD OBJECTS
FR2937054B1 (en) 2008-10-13 2010-12-10 Commissariat Energie Atomique METHOD AND DEVICE FOR DECONTAMINATING A METAL SURFACE
JP6796587B2 (en) 2015-02-05 2020-12-09 フラマトム ゲゼルシャフト ミット ベシュレンクテル ハフツング How to decontaminate metal surfaces with a nuclear reactor cooling system

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3258429A (en) * 1963-09-19 1966-06-28 Ronald D Weed Decontamination solution and method
US3873362A (en) * 1973-05-29 1975-03-25 Halliburton Co Process for cleaning radioactively contaminated metal surfaces
US4226640A (en) * 1978-10-26 1980-10-07 Kraftwerk Union Aktiengesellschaft Method for the chemical decontamination of nuclear reactor components
ATE18822T1 (en) * 1981-06-17 1986-04-15 Central Electr Generat Board PROCESSES FOR THE CHEMICAL DECOMPOSITION OF OXIDE DEPOSITS.
US4476047A (en) * 1982-03-22 1984-10-09 London Nuclear Limited Process for treatment of oxide films prior to chemical cleaning
US4587043A (en) * 1983-06-07 1986-05-06 Westinghouse Electric Corp. Decontamination of metal surfaces in nuclear power reactors
FR2562710B1 (en) * 1984-04-05 1989-02-17 Electricite De France PROCESS FOR REMOVING DEPOSITS FORMED IN A PRESSURIZED WATER NUCLEAR REACTOR VAPOR GENERATOR

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9008385A1 *

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FR2641895A1 (en) 1990-07-20
KR910700531A (en) 1991-03-15
US5093072A (en) 1992-03-03

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