EP0589781B1 - Dekontaminierendes Reduktorgel und seine Verwendung zur Dekontamination von Oberflächen - Google Patents

Dekontaminierendes Reduktorgel und seine Verwendung zur Dekontamination von Oberflächen Download PDF

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Publication number
EP0589781B1
EP0589781B1 EP19930402307 EP93402307A EP0589781B1 EP 0589781 B1 EP0589781 B1 EP 0589781B1 EP 19930402307 EP19930402307 EP 19930402307 EP 93402307 A EP93402307 A EP 93402307A EP 0589781 B1 EP0589781 B1 EP 0589781B1
Authority
EP
European Patent Office
Prior art keywords
gel
oxidizing
agent
mol
reducing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19930402307
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English (en)
French (fr)
Other versions
EP0589781A1 (de
Inventor
Jean-Paul Gauchon
Paul Fuentes
Jean-Pierre Cizel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Original Assignee
Commissariat a lEnergie Atomique CEA
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Publication of EP0589781A1 publication Critical patent/EP0589781A1/de
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Classifications

    • 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

Definitions

  • the subject of the present invention is a reducing decontaminating gel usable for decontamination radioactive from surfaces, in particular of metallic surfaces covered by a layer very adherent surface of metallic oxides.
  • the metal surfaces of these primary circuits which are usually made of stainless steel, Incoloy® or Inconel®, are generally covered with deposits of iron, chromium and nickel oxides which can be in various forms, for example in the form of nickel ferrite NiFe 2 O 4 , magnetite Fe 3 O 4 , nickel ferrite and chromium, chromium ferrite FeCr 2 O 4 , nickel chromite NiCr 2 O 4 and chromium oxide Cr 2 O 3 .
  • an oxidizing decontaminating gel can be used, as described in FR-A-2 656 949.
  • this oxidizing gel which makes it possible to remove the radioactive elements deposited on the part as well as the encrusted elements on its surface, does not have sufficient effectiveness with respect to the adherent metal oxide layers deposited on the surface of alloys such as austenitic steels, the Inconel 600 and the Incoloy.
  • the oxide layers deposited on these metal surfaces contain radioactive elements such as 58 Co, 60 Co and 51 Cr which are emitters of gamma photons which it is therefore important to eliminate.
  • the present invention has precisely for object a reducing decontaminating gel which allows to remove these adherent metal oxide layers.
  • a gel is a solution colloidal whose phases are difficult to define due to the molecular weight of the colloid and its state of significant dispersion in solution.
  • This gel structure is obtained by adding component a) to an aqueous solution, that is to say an inorganic gelling agent which does not oxidize, resists components b) and c), and has a high specific surface. , for example greater than 100m 2 / g.
  • the content of gelling agent in the solution colloidal is chosen so as to obtain a viscosity sufficient to maintain the gel in layers on the surface of a room.
  • the gel has a viscosity at least equal to 350mPa.s at the time of use to be able to apply it easily on the surface of a part, for example by projection with a pistol.
  • the agent content gelling agent represents 20 to 30% by weight of the solution ; it depends in particular on the gelling agent used.
  • the gelling agent is based on alumina Al 2 O 3 and it can be obtained by hydrolysis at high temperature.
  • a gelling agent which can be used mention may be made of the product sold under the trade name Alumina C.
  • the inorganic base used in the gel decontaminant of the invention can be in particular NaOH or KOH.
  • NaOH is used in particular at concentrations from 7 to 10mol / l to obtain a pH at least 13.
  • the reducing agent used in the gel of the invention is a reducing agent having a normal redox potential E 0 less than -600mV / ENH (normal hydrogen electrode) in a strong base medium (pH ⁇ 13).
  • reducing agents borohydrides, sulfites, hydrosulfites, sulfides, hypophosphites, zinc and hydrazine.
  • the pH of the colloidal solution is preferably greater than or equal to 14 for that the borohydride remains stable.
  • Decontaminant reducing gels the invention can be prepared in a simple way adding to an aqueous solution of the constituent b), i.e. inorganic base, the agent reducing agent and gelling agent. Generally, we add the reducing agent before the gelling agent.
  • the use, in the first step, of a reducing gel at pH ⁇ 13 according to the invention makes it possible to weaken and move the adherent surface metal oxide layers which are not sensitive to the action oxidizing decontaminating gels.
  • oxides such as nickel ferrite NiFe 2 O 4 and magnetite Fe 3 O 4 to reduce Fe III to Fe II .
  • the action of the oxidizing gel in an acid medium for example HNO 3 at a concentration of 5 to 10 mol / l, makes it possible to oxidize the chromites which are rather within the deep oxide layer.
  • an acid medium for example HNO 3 at a concentration of 5 to 10 mol / l
  • an oxidizing gel is used the decontaminating gels described in particular in FR-A-2 656 949.
  • oxidizing gels we may cite those in which the gelling agent is silica based, inorganic acid is acid nitric and the oxidizing agent is cerium sulfate.
  • the action of the reducing gel in the first step alone is not decisive, but following of this first step of reducing treatment, the application of the oxidizing gel in an acid medium allows achieve average decontamination factors 2.7 instead of 1.2 when using the oxidizing gel only.
  • decontamination factors can be reached from 20 to 50.
  • the process of the invention is therefore very interesting because it allows obtaining excellent results, cold and with small quantities of reagent.
  • the application of the different gels to the metal surface to be decontaminated can be carried out by conventional methods, for example by spraying with a spray gun, by soaking and draining, by packaging or even by means of a brush.
  • the gel is applied by spraying with a spray gun, for example under a pressure (Airless compressor) at the level of the injector ranging from 50 to 100 kg / cm 2 .
  • the reducing gel R1 is deposited thereon by spraying with a spray gun so as to deposit 800g of gel per m 2 of surface and the gel is kept on the surface for 2 hours. .
  • a rinse is then carried out with demineralized water using 5 l of water per m 2 of surface.
  • the oxidizing gel 01 is then applied to the thus rinsed surface by spraying with a spray gun as above and it is also maintained on the surface of the part for 2 hours using an amount of 800 g of gel per m 2 of surface.
  • a rinse is then carried out with demineralized water as above.
  • the oxidizing gel is the oxidizing gel 02 of table 2.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Food Science & Technology (AREA)
  • Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Detergent Compositions (AREA)
  • Chemically Coating (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Adhesives Or Adhesive Processes (AREA)

Claims (10)

  1. Reduzierendes dekontaminierendes Gel, bestehend aus einer kolloidalen Lösung mit einem pH von zumindest 13, enthaltend:
    a) 20 bis 30 Gew.-% eines anorganischen gelbildenden Reagens,
    b) 0,1 bis 14 mol/l einer anorganischen Base und
    c) 0,1 bis 4,5 mol/l eines Reduktionsmittels, das im stark basischen Medium (pH ≥ 13) ein Redoxpotential Eg, bezogen auf die Normalwasserstoffelektrode, kleiner als -600 mV hat.
  2. Gel nach Anspruch 1, dadurch gekennzeichnet, daß das gelbildende Reagens Aluminiumoxid als Grundlage hat.
  3. Gel nach einem der Ansprüche 1 und 2, dadurch gekennzeichnet, daß die anorganische Base NaOH oder KOH ist.
  4. Gel nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß das Reduktionsmittel unter den Borhydriden, den Sulfiten, den Hydrosulfiten (Dithioniten), den Sulfiden, den Hypophosphiten, Zink und Hydrazin gewählt wird.
  5. Gel nach Anspruch 1, dadurch gekennzeichnet, daß das Reduktionsmittel Natriumborhydrid ist und daß der pH der kolloidalen Lösung größer als oder gleich 14 ist.
  6. Dekontaminierendes Gel nach Anspruch 1, dadurch gekennzeichnet, daß das gelbildende Reagens Aluminiumoxid als Grundlage hat, daß die anorganische Base NaOH ist und daß das Reduktionsmittel Natriumborhydrid, Natriumsulfid, Natriumhydrosulfit (Natriumdithionit) oder Hydrazin ist.
  7. Verfahren zur Dekontaminaation einer metallischen Oberfläche, dadurch gekennzeichnet, daß es nacheinander die folgenden Schritte umfaßt:
    1) Auftragen eines reduzierenden dekontaminierenden Gels nach einem der Ansprüche 1 bis 6 auf die zu dekontaminierende Oberfläche, Belassen dieses Gels auf der Oberfläche während einer Zeitdauer, die von 10 min bis 5 h geht, und Abspülen der metallischen Oberfläche, um dieses reduzierende Gel zu entfernen, und
    2) Auftragen eines im sauren Medium oxidierenden Gels auf die so behandelte Oberfläche, Belassen dieses Gels auf der Oberfläche während einer Zeitdauer, die von 30 min bis 5 h geht, und Abspülen der metallischen Oberfläche, um dieses oxidierende Gel zu entfernen.
  8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß das oxidierende Gel aus einer kolloidalen Lösung besteht, enthaltend:
    a) 8 bis 25 Gew.-% eines anorganischen gelbildenden Reagens,
    b) 3 bis 10 mol/l einer anorganischen Säure und
    c) 0,1 bis 1 mol/l eines Oxidationsmittels, das im stark sauren Medium (pH < 1) ein Redoxpotential Eg, bezogen auf die Normalwasserstoffelektrode, größer als 1400 mV hat.
  9. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß das oxidierende Gel aus einer kolloidalen Lösung besteht, enthaltend:
    a) 8 bis 25 Gew.-% eines anorganischen gelbildenden Reagens,
    b) 3 bis 10 mol/l einer anorganischen Säure,
    c) 0,1 bis 1 mol/l der reduzierten Form eines Oxidationsmittels, das im stark sauren Medium (pH < 1) ein Redoxpotential E0, bezogen auf die Normalwasserstoffelektrode, größer als 1400 mV hat, und
    d) 0,1 bis 1 mol/l einer Verbindung, die imstande ist, die reduzierte Form dieses Oxidationsmittels zu oxidieren.
  10. Verfahren nach einem der Ansprüche 8 und 9, dadurch gekennzeichnet, daß in diesem oxidierenden Gel das gelbildende Reagens Siliciumdioxid als Grundlage hat, daß die anorganische Säure Salpetersäure ist und daß das Oxidationsmittel Cersulfat ist.
EP19930402307 1992-09-23 1993-09-21 Dekontaminierendes Reduktorgel und seine Verwendung zur Dekontamination von Oberflächen Expired - Lifetime EP0589781B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9211317 1992-09-23
FR9211317A FR2695839B1 (fr) 1992-09-23 1992-09-23 Gel décontaminant réducteur et son utilisation pour la décontamination de surface notamment d'installations nucléaires.

Publications (2)

Publication Number Publication Date
EP0589781A1 EP0589781A1 (de) 1994-03-30
EP0589781B1 true EP0589781B1 (de) 1999-03-31

Family

ID=9433783

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19930402307 Expired - Lifetime EP0589781B1 (de) 1992-09-23 1993-09-21 Dekontaminierendes Reduktorgel und seine Verwendung zur Dekontamination von Oberflächen

Country Status (4)

Country Link
EP (1) EP0589781B1 (de)
DE (1) DE69324203T2 (de)
ES (1) ES2132203T3 (de)
FR (1) FR2695839B1 (de)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2746328B1 (fr) * 1996-03-21 1998-05-29 Stmi Soc Tech Milieu Ionisant Gel organomineral de decontamination et son utilisation pour la decontamination de surfaces
FR2798603B1 (fr) * 1999-09-20 2002-03-01 Tech En Milieu Ionisant Stmi S Gel organique de decontamination et son utilisation pour la decontamination de surfaces
US6852903B1 (en) * 2000-05-31 2005-02-08 The United States Of America As Represented By The Secretary Of The Army Decontamination of chemical warfare agents using a reactive sorbent
FR2827530B1 (fr) 2001-07-17 2004-05-21 Commissariat Energie Atomique Procede de traitement d'une surface par un gel de traitement, et gel de traitement
FR2891470B1 (fr) * 2005-10-05 2007-11-23 Commissariat Energie Atomique Gel aspirable pour la decontamination de surfaces et utilisation
FR2962046B1 (fr) * 2010-07-02 2012-08-17 Commissariat Energie Atomique Gel de decontamination biologique et procede de decontamination de surfaces utilisant ce gel.

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3080262A (en) * 1959-04-07 1963-03-05 Purex Corp Process for removal of radioactive contaminants from surfaces
FR2641895A1 (fr) * 1989-01-19 1990-07-20 Commissariat Energie Atomique Procede de decontamination radioactive de surface metallique, notamment de portions de circuits primaires de reacteurs nucleaires refroidis a l'eau
FR2656949B1 (fr) * 1990-01-09 1994-03-25 Commissariat A Energie Atomique Gel decontaminant et son utilisation pour la decontamination radioactive de surfaces.
US5078894A (en) * 1990-04-30 1992-01-07 Arch Development Corporation Formulations for iron oxides dissolution

Also Published As

Publication number Publication date
ES2132203T3 (es) 1999-08-16
FR2695839A1 (fr) 1994-03-25
DE69324203T2 (de) 1999-09-30
FR2695839B1 (fr) 1994-10-14
EP0589781A1 (de) 1994-03-30
DE69324203D1 (de) 1999-05-06

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