EP0090680B1 - Verfahren zur Dekontamination radioaktiv verunreinigter Oberflächen - Google Patents

Verfahren zur Dekontamination radioaktiv verunreinigter Oberflächen Download PDF

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Publication number
EP0090680B1
EP0090680B1 EP19830400370 EP83400370A EP0090680B1 EP 0090680 B1 EP0090680 B1 EP 0090680B1 EP 19830400370 EP19830400370 EP 19830400370 EP 83400370 A EP83400370 A EP 83400370A EP 0090680 B1 EP0090680 B1 EP 0090680B1
Authority
EP
European Patent Office
Prior art keywords
film forming
process according
aqueous solution
varnish
washing
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
Application number
EP19830400370
Other languages
English (en)
French (fr)
Other versions
EP0090680A1 (de
Inventor
Lucien Henrion
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.)
Lorraine De Peintures Et Vernis (slpv) Sa Ste
Original Assignee
Lorraine De Peintures Et Vernis (slpv) Sa Ste
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Lorraine De Peintures Et Vernis (slpv) Sa Ste filed Critical Lorraine De Peintures Et Vernis (slpv) Sa Ste
Publication of EP0090680A1 publication Critical patent/EP0090680A1/de
Application granted granted Critical
Publication of EP0090680B1 publication Critical patent/EP0090680B1/de
Expired legal-status Critical Current

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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 present invention relates to radioactive decontamination of polluted surfaces by depositing contaminating agents, in particular in the form of dust.
  • radioactive decontamination (or D.R.A.) consists in ridding the surfaces of deposited radioactive dust, or at least ridding it sufficiently to no longer represent a danger to the operator.
  • the object of the present invention is to allow radioactive decontamination of surfaces while avoiding the drawbacks and handicaps of the usual practice or of known techniques.
  • the subject of the invention is a method for radioactive decontamination of polluted surfaces by depositing contaminating agents, in particular in the form of dust, according to which before exposing the surfaces to contaminating agents, a coating is applied to them.
  • film-forming material which, after drying, forms an adherent coating and, after contamination, the contaminated surfaces are subjected to washing with a solution in which said film-forming material has good solubility so as to dissolve the film-forming coating sufficiently so that it eliminating it carries with it the contaminating agents, a process characterized in that the adherent film-forming coating which is formed on the surfaces is, on the one hand, insoluble in water or in any aqueous solution having a pH of between 6 and 8 approximately and, on the other hand, has good solubility in an aqueous solution whose pH is outside the range of values mentioned above, and in that said aqueous solution is used as a solution for washing contaminated surfaces.
  • the film-forming coating that is formed is perfectly soluble in water added with a base, so as to preferably have a pH at a value of approximately 9 or more, and this solution is used.
  • basic aqueous as washing liquid for contaminated surfaces.
  • dust is therefore meant to qualify, not only powdery solid fragments, but any other substance, in any form whatsoever (droplets, mist, vapor, etc.) capable of being deposited on the surfaces, by example by condensation.
  • the invention results, among other things, from the following considerations: it is clear that the dust, which is deposited on the surfaces, adheres to it with a resistance to removal which depends on the surface condition of the support.
  • a “thin layer” is a layer whose thickness is less than approximately 50 ⁇ m and, preferably equal to or slightly less than 20 ⁇ m.
  • an advantageous implementation of the invention consists in using a liquid varnish which is spread over the surfaces to be coated and which, after drying, will form the desired film.
  • the coating film be applied in a thin layer, in which case coatings of heterogeneous character (for example the paints themselves) can in all rigor be used according to the method. of the invention.
  • coatings of heterogeneous character for example the paints themselves
  • the choice of a film-forming coating in a homogeneous thin layer constitutes an implementation of the method according to the invention which is both easy and economical, and therefore particularly advantageous.
  • a varnish is prepared composed, as basic constituents, of a resin (or binder) formed by a vinyl copolymer of crotonic acid and a solvent formed by ethyl (or isopropyl) alcohol.
  • Adjuvants are then added in an adequate quantity to improve the quality of the varnish, namely: a diluent, such as ethyl glycol acetate (or butyl glycol) as well as a plasticizer, for example phthalate dioctyl (or octyl sebacate).
  • varnish solution comprising, by weight, approximately 25% of vinylic copolymer of crotonic acid, between 2.5 and 3% approximately of dioctyl phthalate, the rest being constituted by the solvent (ethyl alcohol) and the diluent (ethyl glycol acetate).
  • the diluent and the plasticizer are determined so that after drying, the resin (or dry extract •) is capable of forming, in a single layer and without sagging or the like, a film of minimum thickness offering good protection .
  • the varnish once ready, is applied to clean and dry surfaces, preferably by spraying with a pneumatic gun.
  • the varnish After drying, the varnish forms a continuous film, without breaking or cracking and with a thickness of about fifteen microns on average.
  • the above-mentioned value represents a practical and economic optimum, but by no means a technical minimum necessary for the execution of the method according to the invention.
  • the equipment after proper drying of the varnish, the equipment, the surfaces of which are thus coated, can be put into service, and in particular be exposed to an atmosphere having in suspension the radioactive dust.
  • the protective resin film will slowly load into dust without, however, deteriorating or deteriorating, since the vinyl copolymer which constitutes it, being insoluble in the usual solvents as well as in any aqueous solution at pH below about 8, therefore remains perfectly stable and chemically inert in contact with the atmosphere prevailing in the enclosures and cells where the material is used.
  • a basic aqueous solution having a pH preferably at least one point above the solubility threshold of the resin.
  • a aqueous solution is prepared containing 3 g of sodium hydroxide (Na OH) per liter of water, corresponding to a pH close to 9.
  • an appropriate surfactant can be added to impart to the solution. an additional detergent action.
  • this solution is then projected onto the contaminated surfaces using injection lances.
  • the varnish dissolves easily, carrying with it the contaminating dust which had settled there.
  • a period of washing which can range from half an hour to an hour and a half depending on the extent of the initial contamination of the surfaces, the latter are completely free of radioactive dust.
  • a new layer of varnish is applied to them and the equipment is ready for a new start-up.
  • the dissolution of the varnish in the soda solution has the advantage of being irreversible, that is to say that the varnish, once dissolved, no longer regains its initial film-forming quality, but occurs after water evaporation, in powder form.
  • This absence of gelation in the washing solution constitutes an additional advantage for the final conditioning of the contaminated effluents.
  • the solid residue which appears in small quantity on these surfaces can be easily removed by simple dry cleaning, for example by light brushing.
  • the method according to the invention has many other advantages and advantages, some of which are now mentioned.
  • the state of the surface to be decontaminated is perfectly known, given that it consists of the film-forming coating which is controlled totally both the application and the stability and that one can, at the desired time, easily dissolve and eliminate whatever the nature, the quantity, the distribution and especially the adhesion of the contaminants which are deposited there.
  • the amount of base to be used (e.g. soda) is less than that consumed with usual practice due not only to the less amount of washing required, but also because the concentration of liquid in soda can be adjusted to its minimum value, sufficient to slightly exceed the pH threshold from which the applied coating is perfectly soluble.
  • the residual concentrate composed of the dry extract of the varnish (the resin), soda and contaminants, can be easily calcined and thus waste of a minimum volume is obtained.
  • varnish additives having electrostatic properties which oppose by their effects the tendency to deposit dust and thus making it possible to modify in the direction desired the amount of dust deposited, or even their geographic distribution on the surfaces.
  • constituent elements of the film-forming material to be applied in particular varnish when this type of product is used, can vary within a wide range of possibilities, among which the skilled person will be able to make a choice according to his wishes or necessities.
  • the process according to the invention can be carried out with washing of the contaminated surfaces with a solution not only basic but also with an acid solution.
  • temporary film-forming coating will be made accordingly so that it can be removed by dissolving in an acidic washing solution, preferably at a pH of at least 5.
  • the washing operation carried out for this purpose can be carried out, not only by jets with a lance, as is imperatively the case in current current practice, but also (although less easy to implement and may be generally less effective) statically, in a "dead bath", by immersion in a swimming pool.
  • the field of application of the method according to the invention extends beyond the reprocessing of irradiated fuels and in fact relates to radioactive decontamination in general. within the limit however where the contamination originates from the deposition on surfaces, or other supports, of irradiated dust or condensables.
  • the method according to the invention can find civil applications, for example in equipment and installations located in sensitive areas in nuclear power plants, or for laboratory devices on which can flow. solutions loaded with radioactive particles during handling.
  • the method according to the invention can also find military applications, in particular of the same type as civil applications for sensitive areas (for example in nuclear powered submarines) or for various military materials which may be contaminated by dust from a nuclear explosion, during atmospheric tests, etc.

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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)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Sampling And Sample Adjustment (AREA)

Claims (9)

1. Verfahren zur Dekontamination von Oberflächen, die durch den Niederschlag kontaminierender Stoffe, insbesondere in Staubform, radioaktiv verunreinigt sind, bei dem die Oberflächen, bevor sie den kontaminierenden Stoffen ausgesetzt werden, mit einer filmbildenden Materie versehen werden, die nach Trocknung eine haftende Schicht bildet und bei dem nach der Kontamination die kontaminierten Oberflächen einer Waschung mit einer Lösung unterworfen werden, in der die filmbildende Materie eine gute Löslichkeit aufweist, so daß sich die filmbildende Schicht ausreichend auflöst und bei ihrem Ablösen die kontaminierenden Stoffe mitnimmt, dadurch gekennzeichnet, daß die auf den Oberflächen gebildete haftende filmbildende Schicht einerseits im Wasser oder jeglicher wässrigen Lösung mit einem pH-Wert zwischen 6 und 8 ungefähr unlöslich ist und andererseits eine gute Löslichkeit in einer wässrigen Lösung aufweist, deren pH-Wert außerhalb des genannten Wertbereiches liegt und daß diese wässrige Lösung als Waschlösung für die kontaminierten Oberflächen verwendet wird.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die gebildete haftende filmbildende Schicht in einer basischen wässrigen Lösung vollständig löslich ist und daß diese Lösung als Waschlösung für die Oberflächen verwendet wird.
3. Verfahren nach Anspruch 2, dadurch gekennzeichnet, daß die gebildete haftende filmbildende Schicht in einer basischen wässrigen Lösung vollständig löslich ist, deren pH-Wert ungefähr 9 oder mehr beträgt.
4. Verfahren nach Ansprüchen 1, 2 oder 3, dadurch gekennzeichnet, daß eine filmbildende Materie verwendet wird, die zusätzlich elektrostatische Eigenschaften aufweist, deren Wirkungen dem Niederschlag von kontaminierenden Stoffen entgegenwirken.
5. Verfahren nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die verwendete filmbildende Materie ein flüssiger Firnis ist, der auf die zu beschichtenden Oberflächen derart aufgebracht wird, daß nach Trocknung ein fester Film als kontinuierliche homogene und dünne Schicht gebildet wird.
6. Verfahren nach Ansprüchen 3 und 5, dadurch gekennzeichnet, daß die verwendete filmbildende Materie ein flüssiger Firnis ist, der ein Harz aufweist, das aus einem Vinyl-Copolymer der Crotonsäure oder einer Mischung von mehreren derartigen Copolymeren besteht und daß als Waschflüssigkeit für die Oberflächen eine basische wässrige Lösung verwendet wird, deren pH-Wert in der Nähe von 9 oder mehr liegt.
7. Verfahren nach Anspruch 6, dadurch gekennzeichnet, daß der zur Beschichtung verwendete Firnis außerdem ein Lösungsmittel aufweist, das aus einem Alkohol besteht wie z. B. Ethylalkohol oder Isopropylalkohol.
8. Verfahren nach Ansprüchen 6 oder 7, dadurch gekennzeichnet, daß der verwendete Firnis außerdem ein Verdünnungsmittel aufweist, das aus einem Ethylglykol-Acetat und/oder einem Butylglykol-Acetat besteht.
9. Verfahren nach Ansprüchen 6, 7 oder 8, dadurch gekennzeichnet, daß der verwendete Firnis außerdem einen Weichmacher enthält, der aus Dioktylphthalat oder Sebacinsäureoktylester besteht.
EP19830400370 1982-03-02 1983-02-23 Verfahren zur Dekontamination radioaktiv verunreinigter Oberflächen Expired EP0090680B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8203561 1982-03-02
FR8203561A FR2522869B1 (fr) 1982-03-02 1982-03-02 Procede pour la decontamination radioactive des surfaces

Publications (2)

Publication Number Publication Date
EP0090680A1 EP0090680A1 (de) 1983-10-05
EP0090680B1 true EP0090680B1 (de) 1986-12-03

Family

ID=9271564

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19830400370 Expired EP0090680B1 (de) 1982-03-02 1983-02-23 Verfahren zur Dekontamination radioaktiv verunreinigter Oberflächen

Country Status (4)

Country Link
EP (1) EP0090680B1 (de)
JP (1) JPS58161897A (de)
DE (1) DE3368143D1 (de)
FR (1) FR2522869B1 (de)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61209398A (ja) * 1985-03-13 1986-09-17 上村工業株式会社 放射能汚染廃棄物の除染方法
FR2690163A1 (fr) * 1992-04-17 1993-10-22 Commissariat Energie Atomique Procédé de décontamination de la couche superficielle d'un sol recouvert de particules polluantes et solution de décontamination.
FR2717709B1 (fr) * 1994-03-22 1996-04-26 Commissariat Energie Atomique Gel capable de retenir une contamination radioactive et son utilisation pour protéger ou décontaminer une surface.
CN111028970B (zh) * 2019-12-26 2025-06-06 中国人民解放军军事科学院国防工程研究院工程防护研究所 一种具有去污和辐射屏蔽功能的压制去污剂及其制备方法

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2877131A (en) * 1946-05-06 1959-03-10 Donald C Overholt Method and coating composition for protecting and decontaminating surfaces
FR1303673A (fr) * 1960-08-16 1962-09-14 Atomic Energy Authority Uk Agents d'assainissement pour purifier des surfaces contaminées par des matières radio-actives
FR2380624A1 (fr) * 1977-02-09 1978-09-08 Commissariat Energie Atomique Procede de decontamination radioactive d'une piece
DE3028884A1 (de) * 1980-07-30 1982-02-25 Brown, Boveri & Cie Ag, 6800 Mannheim Kontaminationsschutz

Also Published As

Publication number Publication date
EP0090680A1 (de) 1983-10-05
JPS58161897A (ja) 1983-09-26
FR2522869A1 (fr) 1983-09-09
DE3368143D1 (en) 1987-01-15
FR2522869B1 (fr) 1988-08-12

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