RU2236054C1 - Composition for normalizing radiation environment - Google Patents

Abstract

FIELD: environment protection against radioactive pollution.

SUBSTANCE: proposed composition has film-forming material based on aqueous or water- alcohol solution of polyvinyl alcohol, or on organic solution of perchlorovinyl resin, as well as plasticizer and filler. Used as plasticizer is industrial or castor oil, or poorly soluble corrosion inhibitor; filler is titanium dioxide and/or lead oxide. Proportion of composition ingredients is as follows, mass percent: film-forming material, 5.0 - 18.0; plasticizer, 0.5 -0 1.0; filler, 3.0 - 5.0; solvent, the rest.

EFFECT: enlarged functional capabilities; enhanced reliability of physical, chemical, and mechanical characteristics of produced coating.

9 cl, 6 tbl

Description

The invention relates to polymer compositions for normalizing the radiation situation (NRA) of natural and man-made objects under conditions of contamination with radioactive substances during operation and decommissioning of nuclear power plants (NPPs), namely, insulating, localizing and deactivating compositions. Normalization of the radiation environment is a process of applying decontamination, isolation and containment technologies using polymer coatings (films). The applied polymer coatings make it possible to carry out technological processes of NRA with a real reduction in the personnel dose, and further non-proliferation of radioactive contaminants.

Depending on the purpose, three main groups of polymer coatings (films) are classified, namely: deactivating, insulating and localizing [A.D. Zimon, V.K. Pikalov "Decontamination", M., Publishing House, 1994, p. 186]. This classification is based on the ratio of films to radioactive contamination. Insulating films and non-removable coatings perceive radioactive contamination, screen the surface in contrast to localizing ones, which are applied to an already contaminated surface. The action of deactivating films consists in the penetration of radionuclides into the film material and in the removal of the film together with the radioactive contamination held in it.

The choice of material for the films is determined by the characteristics of the object, the state of aggregation and the isotopic composition of the radioactive contamination. As films for various purposes, paints and varnishes, water-repellent compositions, polymer compositions, dispersed systems, including sorbents, in the form of suspensions, pastes and gels are used.

Known film-forming composition for a waterproof decontamination coating, described in and.with. USSR No. 1688714, cl. G 21 F 9/34, published in 2000, based on methylol polyamide resin, ethyl alcohol and ammonium chloride. Surface material - stainless steel, duralumin; pollution - aqueous solutions of cesium-137 and strontium-90. Ammonium chloride ingredient increases the deactivating ability of the composition. However, this film-forming composition is used only for decontamination.

Also known film-forming composition for the decontamination of paint surfaces (RF patent No. 1271267, CL G 21 F 9/16, publ. 1998), containing polyvinyl alcohol, potassium hydroxide and water. The reason limiting its use is the narrow scope of the destination.

A known method of protecting the surfaces of equipment and facilities described in the patent of the Russian Federation No. 2039778, class. C 09 D 129/04, 5/20, publ. 1993, RU, used for temporary protection of the surfaces of equipment and premises of nuclear power plants with a film-forming composition based on polyvinyl alcohol with the addition of glycerin, water, ethyl alcohol. The surface is pre-coated with a primer with reinforcing material (gauze). Surface material - metal, polymeric materials, painted surfaces. Pollution - β-radionuclides. The reasons that impede the widespread use of the above film-forming composition include the need for reinforcement, the limited life of the formed coating (co-peeling in less than 1 month).

Known Japanese application No. 8573210, class. G 21 F 9/00, publ. 1996, describing a method of preventing radioactive contamination of rooms in which work with radioactive materials is carried out. In the room, the floor is covered with a film of polyvinyl butyral with a degree of butyralization of 62-68 mol.%, A thickness of 0.03-0.2 mm. After completion of work, the contaminated film is removed. In this case, the film is used to isolate radioactive contamination only for the duration of the work and cannot be used for long-term surface protection.

Known PCT application No. 92/18984, class. G 21 F 1/10, C 09 D 133/06, publ. 1994, describing a method of reducing the background of radon indoors. The contaminated surface is covered with an aqueous solution of a copolymer of vinylidene chloride-acrylic ester, which also contains a non-ionic surfactant - a copolymer of vinyl pyrrolidone and an antifoam. The coating is dried. This coating is used as a localization and only to reduce the background of radon indoors.

Known Japanese application No. 86-77935, class. G 21 F 9/00, publ. 1996, describing a film that prevents the dispersion of radioactive dust and other substances into the environment. A film for gluing the floor and walls of nuclear power plants during maintenance and repair to protect them from radioactive contamination and then removed and destroyed contains a base on which adhesive layers are formed on the front and back sides with a certain adhesive force. Such a film is used as localizing and can not be used neither for decontamination, nor for insulation of surfaces contaminated with radionuclides.

Thus, domestic and foreign compositions for decontamination, isolation and localization from radioactive contamination of surfaces of equipment, premises, etc. are known. However, all known compositions are used for any one task: either decontamination, or isolation, or localization, and do not solve the complex problem.

The basis of the invention is the task of creating a composition to normalize the radiation environment, which would be universal and cover the multivariate solution to the problem of NRA.

The closest technical solution to the claimed composition for normalizing the radiation situation for the totality of the essential features and the technical result achieved is the information on polymer coatings that deactivate, isolate and localize, described in the book [A. Zimon, V. Pikalov "Decontamination", M., Publishing house, 1994, p.186], which are selected as a prototype. In the proposed prototype, it is indicated that aqueous and aqueous-alcoholic solutions of polymers are used as the polymer base for such compositions, which include polyvinyl alcohol, polyvinyl butyral, latex dispersion, polyvinyl acetate emulsion, etc. To give the films physical and chemical properties (necessary elasticity, strength and adhesion) plasticizers (glycerin, tributyl phosphate, etc.) and fillers (surfactants, pigments, rarely sorbents) are introduced into the polymer composition. To bind the radionuclides in accordance with the properties of the films and their purpose, chemical reagents are introduced into the polymer compositions, including mineral and organic acids, oxidizing agents, complexing agents, etc. Despite the different functional purpose, a wide range of materials for the films, the identity of physic -chemical processes of deposition, formation and removal of films, as well as their interaction with radioactive contamination.

The essence of the proposed technical solution is to normalize the radiation environment due to the versatility of the composition, which at the same time allows solving the problems of decontamination, isolation and localization by varying the qualitative and quantitative composition within one composition. This ensures the constancy of physico-chemical and physico-mechanical properties of the formed coating for the entire period of operation. It should also be noted the absence of liquid radioactive waste. The resulting solid radioactive waste compactly coagulates and is prepared for disposal. Application of the claimed composition can be carried out using painting equipment manufactured in the Russian Federation.

The specified technical result when using the invention is achieved in that the composition for normalizing the radiation environment, including a film-forming substance based on an aqueous or aqueous-alcoholic solution of polyvinyl alcohol (PVA), or an aqueous-alcoholic solution of polyvinyl butyral (PVB), or based on an organic solution of perchlorovinyl resin (PVC resin), a plasticizer and a filler, characterized in that as a plasticizer contains industrial, or castor oil, or sparingly soluble corrosion inhibitor and, and as a filler contains titanium dioxide and / or lead oxide in the following ratios of components, wt.%:

film-forming substance 5.0-18.0

plasticizer 0.5-1.0

filler 0.5-1.0

solvent rest

Moreover, the above composition may further comprise alumina in an amount of 0.5-2.0 wt.%; cobalt nitrate in an amount of 0.2-0.5 wt.%; nitric or phosphoric acid in an amount of 0.1-0.4 wt.%; sulfonol in an amount of 0.1-0.3 wt.%; polymethylsiloxane liquid (permanent residence) in an amount of 0.1-0.4 wt.%; rhodamine 6G in an amount of 0.01-0.05 wt.%; citric, or oxalic or ethylenediaminetetraacetic acid (EDTA) in an amount of 0.2-0.8 wt.%; glycerin in an amount of 1.0-3.0 wt.%.

The signs given in the claims are necessary and sufficient to achieve the specified technical result, that is, they are essential.

The analysis of the levels of technology carried out by the applicant, including a search by patent and scientific and technical sources of information and identification of sources containing information about analogues of the claimed invention, allowed to establish that the applicant did not find an analogue characterized by features identical to all existing features of the claimed invention. The presence of distinctive features in relation to the selected prototype indicates the compliance of the claimed technical solution with the criterion of "novelty" according to current legislation.

To verify the conformity of the claimed invention to the requirements of the inventive step, the applicant conducted an additional search for known solutions in order to identify coinciding with the distinguishing features of the prototype features of the claimed invention, the results of which show that no solutions are found from the prior art that similarly solve the problem.

Therefore, the claimed technical solution meets the requirement of "inventive step".

Information confirming the possibility of carrying out the invention to obtain the above technical result is illustrated by examples.

The list of components used to prepare the proposed composition:

Polyvinyl alcohol - GOST 10779-78.

Polyvinyl butyral - GOST 9439-85.

Polyvinyl chloride resin in the form of varnish ХВ-784 - GOST 7313-75 or enamel ХВ-124 GOST 10144-89.

Industrial oil I-20A - GOST 20799-88.

Castor oil - GOST 6990-75.

Sparingly soluble corrosion inhibitors:

Additive AKOR-1 - GOST 15171-78, slamin TU 38401753-89, mincor-2 TU 38401753-89.

Titanium Dioxide GOST 9808-84.

Lead oxide GOST 19151-73.

Aluminum oxide (Procal ^TM ) - TU 1711-040-00196368-98.

Cobalt nitrate GOST 4528-78.

Nitric acid - GOST 4461-77.

Phosphoric acid - GOST 6562-80.

Sulfonol TU 6-01-1001-75.

PMS-100 polymethylsiloxane liquid GOST 13032-77.

Dye 6Zh TU 6-09-2463-82.

Citric acid - GOST 3652-69.

Oxalic acid - GOST 22180-76.

Ethylenediaminetetraacetic acid TU 6-09-2356-75.

Technical ethyl alcohol - GOST 17299-78.

Glycerin - GOST 6259-96.

The organic solution is in the form of a solvent R-4A GOST 7827-74.

The proposed composition can be applied to surfaces of any configuration made of various materials (structural steel, corrosion-resistant steel, alloys, rubber, plastic, plexiglass, glass, asphalt, concrete, surfaces painted with oil, alkyd, epoxy and other paints and others.).

Preparation and application of the composition:

1. In an aqueous or aqueous-alcoholic solution of PVA, made on an electric food kettle of the KPE-60-1 brand at a temperature of 60 ° C to 80 ° C and cooled to 40 ° C, the components are added sequentially with stirring according to the recipe (corresponds to Sec. 1 of the claims followed by the addition of components from the dependent claims).

2. In a water-alcohol solution of PVB, made on an electric kettle KPE-60-1 brand at a temperature of 60 ° C to 80 ° C and cooled to 40 ° C, the components according to the recipe are introduced sequentially with stirring.

3. In a solution of polyvinyl chloride resin based on organic solvents, located in an electric kettle KPE-60-1, the components are added sequentially with stirring according to the recipe.

The prepared composition is applied to the surface by all known paint and varnish methods.

Before applying the composition, the level of the initial radioactive contamination of the surface is measured.

The quantitative proportions of the components in the composition are presented in table 1, 2, 3, where examples No. 1-24 - the proposed composition.

Carrying out work to normalize the radiation situation

The made composition with working viscosity is applied to the contaminated surface by pneumatic spraying, and, if necessary, by brush or roller. The formed film is removed in the case of decontamination operations. When localized, the film is removed based on technological needs. With insulation, the film's operating time is 6 months.

Determination of deactivating ability

The deactivating ability is determined according to GOST R 50773-95. The deactivation coefficient (K _d ) is calculated by the formula:

,

,

where A _ref is the initial activity, And _ost is the residual activity.

Determination of isolating ability

The time of the protective action of the composition is determined according to GOST R 50773-95.

During the protective action of the coating, take the time during which the radioactive substance penetrates through the protective coating onto the substrate.

Decontamination, insulation and localization of metal surfaces was performed according to GOST R 50773-95.

The compositions were applied in a single layer.

The initial activity of the samples was measured; after deactivation, the residual activity of the samples was measured.

When isolating clean surfaces, the protective action time was measured by the operating life.

During localization, the time of the protective action was measured by the service life.

The test results for determining the special properties of the composition are presented in table 4, 5, 6.

Determination of physical and mechanical properties

The physicomechanical properties of coatings obtained from compositions for normalizing the radiation environment are characterized by tensile strength σ _p (film tensile strength), MPa, determined according to GOST 14236-81, and film hardness by a pendulum device σ _tv , determined according to GOST 5233 -89. The quality of removable coatings based on the proposed composition was determined according to GOST 27891-88. The test results are also presented in tables 4, 5, 6.

Test Results Analysis

The amount of PVA 5.0-18.0 wt.% Is optimal. A decrease in the amount of PVA below 5.0 wt.% And an increase in excess of 18.0 wt.% Leads to a deterioration of the whole complex of properties, in particular to the formation of very thin films and the formation of a highly viscous composition, which leads to technological difficulties in its application, respectively.

The introduction of industrial oil, castor oil or a sparingly soluble corrosion inhibitor as plasticizers: additives AKOR-1, or Slamin, or Minkor-2 in an amount of 0.5-1.0 wt.% Provides the necessary and sufficient physical and mechanical properties of the coating and easy removal film from the surface, and also gives conservation properties, prevents corrosion. A decrease in the amount of plasticizer below 0.5 wt.% Leads to a deterioration in the physico-mechanical properties of the film, in particular tensile strength. An increase in the amount of plasticizer above 1.0 wt.% Reduces the hardness of the film below the required value.

Compositions including Slamin or Minkor-2 are not reflected in Tables 1 and 2, since the nature of their influence on the coating properties is exactly the same as AKOR-1 additives.

The introduction of fillers of titanium oxide and / or lead oxide in an amount of 3.0-5.0 wt.% Is also optimal. A decrease in the amount of filler below 3.0 wt.% And an increase in excess of 5.0 wt.% Leads to a deterioration in the insulating properties of the coating formed from the composition and manufacturability when applying the composition, respectively. A similar picture is observed when analyzing the quantitative ratios of components and their influence on the change in the properties of coatings from compositions based on PVB and PVC.

The introduction of cobalt nitrate in an amount of 0.2-0.5 wt.%, Nitric or phosphoric acid in an amount of 0.1-0.4 wt.%, Citric or oxalic, or ethylenediaminetetraacetic acid (EDTA) in an amount of 0.2-0 , 8 wt.% According to the results of Tables 4, 5, 6 provides a sufficiently high degree of cleaning of the decontaminated surface (K _d for β and α-active contaminants increases with the introduction of these components), and with isolation and localization the protective action time is 5- 8 months (with the introduction of these components, the protective action time also increases from 4 to 5-8 months ant for various polymeric bases). At values below the indicated amounts of components, the deactivating, insulating and localizing properties of the coatings sharply worsen and above do not lead to a further increase in these properties. Adding a component from the above set of components to the composition has a specific purpose, for example, when introducing cobalt nitrate without the addition of acids, it ensures the absence of an oxidizing effect on the surface; mineral acids are added to treat rusty surfaces, and organic acids are preferred for stainless steel surfaces; painted with alkyd, epoxy and other paints.

Introduction to the proposed composition of aluminum oxide improves the processability of preparation, prevents clumping and facilitates the application of the composition (hiding power), and also gives the composition flame retardant properties due to the fact that when the temperature rises above 100 ° C, 34% of the water in the coating formed from the composition is released previously bound in alumina. The amount of alumina of 0.5-2.0 wt.% In the composition is the most effective, and an increase in its amount over 2.0 wt.% Does not lead to a further increase in the effectiveness of these properties, and a decrease in its amount is below 0.5 wt.% does not improve the manufacturability of the preparation and application of the composition.

The introduction of the proposed composition of sulfonol in an amount of 0.1-0.3 wt.% Allows you to apply it on dusty surfaces, with traces of oils and other technological impurities. A decrease in the amount of sulfonol below 0.1 wt.% And an increase in excess of 0.3 wt.% Does not allow to achieve effective wetting of the surface when applied to the surface with traces of technological dirt.

In the process of preparing the composition for foam suppression, it is preferable to introduce polymethylsiloxane liquid (PM) in an amount of 0.1-0.4 wt.%, A decrease in the amount of permanent residence below 0.1 wt.% And an increase of more than 0.4 wt.% Does not lead to an effect foam suppression.

To give color, which is convenient for some types of work requiring the indication of already treated areas, rhodamine 6Zh dye is additionally added to the composition in an amount of 0.01-0.05 wt.%. The introduction of rhodamine 6G in these quantities is optimal. In addition, with a certain ratio of radionuclides of the fragmentation group, rhodamine 6G increases the effectiveness of decontamination. The introduction of rhodamine 6G in amounts below 0.01 wt.% And above 0.05 wt.% Leads to insufficient color intensity and inappropriate color intensity, respectively.

In the case of work at low temperatures, the introduction of glycerol in an amount of 1.0-3.0 wt.% Is allowed. A decrease in the amount of glycerol below 1.0 wt.% And an increase in excess of 3.0 wt.% Does not impart antifreeze properties and leads to a deterioration in the physicomechanical properties of the coating, respectively.

The analysis of table 4, 5, 6 shows that the compositions according to examples 1-24 have a fairly high degree of purification of the decontaminated surface, and during isolation the protective action time is 5-8 months. The prototype does not possess such qualities. The examples described above as the proposed compositions confirm that the use of components in amounts that do not correspond to those indicated in the claims leads to a decrease in the protective action time for coatings based on PVB and PVA, to a decrease in the deactivating ability - for coatings based on PCV resin, to reduction of physical and mechanical properties - for coatings based on PVA, PVB and PVC resin. Coatings based on the proposed composition have the strength and hardness necessary and sufficient for easy removal from the surface, which is confirmed by such a technological indicator as the quality of removability.

The coatings based on the compositions described in the prototype do not provide multifunctionality (deactivating ability, isolating ability, localizing ability), but have only either deactivating properties, or insulating properties, or localizing properties.

Thus, the implementation of the proposed composition to normalize the radiation environment provides a high degree of decontamination, isolation and localization of surfaces from radioactive contamination at the same time, while maintaining the stability of physico-mechanical properties throughout the entire operation period.

The composition is intended for use at nuclear facilities (AT), provides a reduction in dose loads for personnel and prevents the unauthorized spread of radioactive contamination, which was confirmed by testing in real conditions of AT facilities.

Therefore, the claimed technical solution is aimed at solving the problem and at the same time meets the requirement of "industrial applicability" under the current law.

Claims (9)

1. Composition for normalizing the radiation environment, including a film-forming substance based on an aqueous or aqueous-alcoholic solution of polyvinyl alcohol, or an aqueous-alcoholic solution of polyvinyl butyral, or on the basis of an organic solution of perchlorovinyl resin, a plasticizer and a filler, characterized in that it contains an industrial plasticizer or castor oil, or sparingly soluble corrosion inhibitor, and as a filler contains titanium dioxide and / or lead oxide in the following ratios of comp onents, wt.%: Film-forming substance 5.0-18.0 Plasticizer 0.5-1.0 Filler 3.0-5.0 Solvent Else 2. The composition according to claim 1, characterized in that it further comprises aluminum oxide in an amount of 0.5-2.0 wt.%. 3. The composition according to claim 1, characterized in that it further comprises cobalt nitrate in an amount of 0.2-0.5 wt.%. 4. The composition according to claim 1 or 3, characterized in that it further comprises nitric or phosphoric acid in an amount of 0.1-0.4 wt.%. 5. The composition according to claim 1, characterized in that it further comprises sulfanol in an amount of 0.1-0.3 wt.%. 6. The composition according to claim 5, characterized in that it further comprises polymethylsiloxane liquid in an amount of 0.1-0.4 wt.%. 7. The composition according to claim 1, characterized in that it further comprises citric, or oxalic, or ethylenediaminetetraacetic acid in an amount of 0.2-0.8 wt.%. 8. The composition according to claim 1, characterized in that it further comprises rhodamine 6G in an amount of 0.01-0.05 wt.%. 9. The composition according to claim 1, characterized in that it further comprises glycerin in an amount of 1.0-3.0 wt.%

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