EP1794762B1 - Liquid concentrate set - Google Patents

Description

The invention relates to a novel liquid concentrate set for use in the decontamination of radioactively contaminated surfaces.

After the release of radioactive substances into the environment, radioactive fallout (fallout, rainout, washout) contaminates radioactive contamination of large areas and thus also of people staying there, their equipment, vehicles, etc. When decontaminating articles that are very different in terms of material, surface texture, size, etc., should be treated. This includes not only clothing and personal equipment of the contaminated persons large equipment, vehicles or weapons.

The contamination conditions to be considered are very different, as are the nuclides occurring as well as their chemical and physical form.

In the past, so-called A decontamination center I was optimized for the scenario "nuclear weapon contamination" in the form of alkylarylsulfonate and EDTA either alone or in admixture with each other.

Although the result achievable with the aid of these decontamination agents was satisfactory, these decontamination agents must no longer be used because of their heavy environmental impact, in particular during exercises, trials or disaster relief. For the meanwhile broader range of use of the decontamination agents to be defined and the resulting diverse contamination scenarios, the A-type decontamination agents of conventional embossing are therefore less suitable.

As an alternative, therefore, in the German utility model DE 94 208 66 U1 proposed a decontamination solution for blasting of radioactively contaminated surfaces, which includes as active ingredients citric acid or its salts, a surfactant from the group of fatty alcohol sulfates and another surfactant from the group of sulfosuccinic monoesters. The total formulation contains the active ingredients in total with 1 wt .-%, the remaining 99 wt .-% consist of water.

The provision and transport of such solutions naturally make high logistical demands, because the finished cleaning solution must be kept as such and transported to the respective application points.

Alternatively, it would be conceivable to mix the powdery constituents in water only at the place of use. However, the powdery ingredients are dusting substances and unfavorable to handle, which causes Doslerungsprobleme and additional complex steps are required.

From the point of view of environmental compatibility, the decontamination solution proposed in the German utility model has clear advantages over the previously used so-called A decontamination agents.

In the US 4,752,467 For example, an agent for improving the condition of hair based on a combination of betaine and at least one aliphatic organic acid is described, wherein citric acid can be used as the aliphatic organic acid.

From the US 4,226,640 discloses a process for the chemical decontamination of radioactive material contaminated plants in which the plants are treated with a solution containing a citrate.

In the US 2002/0196891 A1 and the US 2004/0149310 A1 For example, methods for treating and removing scale and other deposits in heat exchange systems are described wherein a cleaning solution which may include citric acid as a reductant is introduced into the heat exchange system.

In the US 5,640,703 there is proposed a method of treating solid waste material contaminated with plutonium or plutonium compounds or suspected of such contamination. In this case, the solid waste material is brought into contact with a liquid medium which may contain citric acid as a complexing agent.

The object of the present invention is to provide means for the decontamination of radioactively contaminated surfaces which are simple in use, storage-stable and unproblematic in terms of logistics requirements.

This object is achieved by the liquid concentrate set according to claim 1.

The liquid concentrate set according to the invention significantly reduces the capacities required for storage and transport, since dilution to the use concentration can only be made on demand and then on site. Up to this point in time, the two liquid concentrates (complexing agent concentrate and surfactant concentrate) are stored separately and brought together only during the production of the decontamination solution used. The invention thus provides a set of two liquid concentrates which can be added to the cleaning fluid, ie generally water, very easily, especially on site. In particular, the liquid concentrates can also be added automatically to the cleaning fluid, in particular also when using high-pressure cleaners.

The liquid concentrate set according to the invention makes it possible to produce decontamination solutions with which very good decontamination results are already achieved at temperatures of 15 ° C., whereas in the abovementioned A decontamination agents hitherto application temperatures of 60 ° C. have been required.

The concentrates of the liquid concentrate set according to the invention allow a problem-free storage of the active ingredients including citric acid or its salts, without causing flocculation, deposits or crystallization of active ingredients, so that the concentrates are ready for use even after prolonged storage. The decontamination agents in question require storage periods of 10 years or more.

The storage stability is achieved in particular because one of the liquid concentrates contains the citric acid component in high concentration as a complexing agent, while the other liquid concentrate contains a biodegradable surfactant packaged separately.

The citrate ion of the citric acid component, like the EDTA used in the prior art, reacts with a variety of cations of charge +2 and +3. Although the complexation constants for the citrate ion are significantly below those of EDTA, its complexing activity proves to be sufficient in extensive experiments.

The surfactant concentrate (B) may optionally contain further proportions of a complexing agent, in particular also the citric acid component, so that it is not necessary to work with highly concentrated solutions when formulating the complexing agent concentrate. However, the content of the complexing agent concentrate (A) in the citric acid component is preferably at least about 20% by weight. Nevertheless, small amounts of liquid concentrate are sufficient for achieving a sufficiently high concentration of active ingredients in the decontamination solution used, in particular also based on the citric acid component.

Preferably, the complexing agent concentrate (A) contains the citric acid component as citrate (e.g., as the trisodium salt), while the acidified surfactant concentrate (B1) contains the citric acid component as the citric acid monohydrate.

The liquid concentrate set according to the invention can be used for a wide range of possible contamination scenarios. The active ingredients required to achieve the decontamination effect, each separately as a liquid concentrate in stock, allows the selection of the active ingredients used also from the point of view of their environmental compatibility, so that total formulations can be used, for which the water hazard class 1 (WGK1) applies.

Thus, the decontamination agents of the invention are suitable for most conceivable decontamination scenarios, ranging from nuclear fallout to contamination from industrial sources or a terrorist spread of radioactive material, such as e.g. through a so-called "dirty bomb".

Due to the possibility of keeping very high active ingredient contents in liquid form in the concentrates, only a small amount of concentrate has to be added to the cleaning fluid, resulting in considerable logistical advantages.

The citric acid component, which plays the role of the complexing agent, is an optimum solution in the sum of its properties such as environmental compatibility, price, availability, handling and effectiveness in decontamination.

Suitable preservatives for the complexing agent concentrate (A) are, inter alia, formaldehyde-based preparations, such as those obtainable, for example, under the trade name ACTICIDE FS from Thor GmbH, Germany.

A reducing agent suitable for the complexing agent concentrate is e.g. the thiosulfate, which is preferably used in a proportion of at least 0.2 wt .-% in the concentrate. Considerably higher proportions are possible, but from a practical point of view, the proportion of thiosulphate will not be higher than about 3% by weight.

When selecting the biodegradable surfactants for the surfactant concentrate (B), it is possible to make use of various surfactants, preference being given to those surfactants which are likewise assigned to WGK 1. The surfactant concentrates can be adjusted to alkaline or acidic.

For acidified surfactant concentrates (B1) so-called sugar surfactants are used. Sugar surfactants are not only ecologically harmless to a high degree; Moreover, they have outstanding performance properties, in particular good foaming properties, cleaning action and miscibility with water.

Preferred sugar surfactants are alkylpolyglycosides based on natural fatty alcohols.

These are preferably selected from C ₈ -C ₁₄ -, C ₈ -C ₁₀ , C ₁₂ -C ₁₄ fatty alcohols based Alkylpolyglucoslden.

A preferred acidified surfactant concentrate (B1) comprises from 20% to 55% by weight of one or more sugar surfactants.

In addition, the acidified surfactant concentrate (B1) may additionally contain 10 to 25% by weight of complexing agent, in particular also in the form of the citric acid component described above.

For some decontamination scenarios, the use of alkaline surfactant concentrates (B2) is recommended.

Alkali surfactant concentrates (B2) contain surfactants selected from alkyl polyethylene glycol ethers, fatty alcohol ethoxylates and carboxyalkyl fatty acid derivatives.

Typical representatives of the aforementioned surfactants are, for example, alkyl (C ₁₀ ) polyethylene glycol ether + 8EO; Fatty alcohol (C ₁₃ -C ₁₅ ) ethoxylate + 8EO; N-2-hydroxyethyl-N-carboxymethyl fatty acid, amidoethylamine Na salt.

The proportion of the surfactants in the surfactant concentrate (B2) is preferably 5 to 20% by weight.

A preferred alkaline surfactant concentrate (B2) contains from 2.5% to 10% by weight of one or more alkyl polyethylene glycol ethers and from 2.5% to 10% by weight of one or more fatty alcohol ethoxylates.

The alkaline surfactant concentrate (B2) may also contain a complexing agent, with a proportion of from 10 to 25% by weight being preferred.

A preferred complexing agent here is the nitrilotriacetate.

Another alternative of an alkaline surfactant concentrate (B2) contains 5 to 10 wt .-% of one or more Carboxylalkylfettsäurederviate, a corrosion inhibitor in the form of 5 to 10 wt .-% alkali metal silicate and optionally up to 2.5 wt .-% alkylbenzenesulfonic acid.

Furthermore, the concentrates (A) and (B) may contain a solubilizer, which in particular can further improve the storage stability of the concentrates.

The invention further relates to the use of the previously described liquid concentrate sets for the decontamination of radioactively contaminated surfaces.

When using the liquid concentrate sets, the concentrates (A) and (B1) are preferably used in the ratio of 5: 7 to 5: 12.

The liquid concentrate sets containing the concentrate (A) and concentrate (B2) are preferably used with a ratio of these components of 1:10 to 3:10.

The total concentration of the Konze ntratkomponenten (A) and (B) or (B1) or (B2) in a cleaning fluid, in particular water, is preferably 0.5 to 5 wt .-%.

When using the acidified surfactant concentrates (B1), the pH of the final decontamination fluid is preferably 4 to 6.5. If a ratio of citric acid: trisodium salt of 1: 4 is set via the mixing ratio (A) :( B1), a well-puffed pH of approx. 5.6 results in the cleaning fluid. This pH therefore remains largely constant when using various raw waters (e.g., surface water).

If alkaline surfactant concentrates are used, a pH of 10 to 12 is sought in the cleaning fluid.

The invention further relates to a method for the decontamination of radioactively contaminated surfaces using a high-pressure cleaner, wherein a liquid concentrate set as described above is added to the auszubringende of the high-pressure cleaner fluid substantially continuously during the discharge of the fluid. The discharge of the fluid is preferably done as a foam.

As mentioned above, the fluids are often aqueous fluids, especially water, although surface water can also be used.

The concentrate set is preferably added to the cleaning fluid so that a total concentration of 0.5 to about 5 wt .-% is achieved in the cleaning fluid.

These and other advantages of the invention will be explained in more detail below with reference to examples.

Determination of the decontamination effect

Appropriate tests are carried out with the formulations for liquid concentrate sets described below, in which their decontamination effect (cleaning effect) is determined on coated test panels which have been (contaminated) with a standardized test soil in a part of the tests.

Standardized test soil

Table 1: Composition of the standardized test soil Mix Shares (as a mass) description supplier 5% Pulsorb GW 65 (activated carbon) Chemviron in Neu-Isenburg 10% White clay Art. 1906 Th. Geyer (Merck) 10% Slate flour N7 Schieferwerke Bacherbach GmbH 77422 Bacherbach 10% Mica 4/0 Grinder Neubauer 20% Siliplast 800 K (feldspar sand) Amberger Kaolinwerke, Hi rschau Eduard Kick GmbH & Co. KG 10% Talc H 60 Herkommer & Bangert, UI m 10% Plasorit Naintsch S Herkommer & Bangert, UI m 20% Kaolin TEC 2 Amberger Kaolinwerke, Hi rschau Eduard Kick GmbH & Co. KG 5% Special bitumen C German Shell Hamburg

The test soil is mixed together under stirring in the order mentioned in Table 1. The special bitumen C must be pulverized with a mortar before mixing.

• Eine ausreichende Menge Testschmutz wird gleichmäßig auf die Lackoberfläche verteilt. Der Testschmutz darf nicht in den Lack eingerieben werden. Ein vorsichtiges Verteilen mit einem Wattebausch hat sich hier bewährt.
• Der aufgebrachte Testschmutz wird mit einem Wassersprühnebel fixiert.
• Überschüssiger Testschmutz wird durch einen drucklosen Wasserstrahl abgewaschen.
• Das Testblech wird bei 55 °C im Trockenschrank 10 Minuten getrocknet.

The application of the test dirt on the paint surface takes place in the following manner:

• A sufficient amount of test soil is evenly distributed on the paint surface. The test dirt must not be rubbed into the paint. A careful distribution with a cotton ball has proven itself here.
• The applied test soil is fixed with a water spray.
• Excess test dirt is washed off by a pressureless water jet.
• The test sheet is dried at 55 ° C in a drying oven for 10 minutes.

Contamination of Testsusbtrate

• Contamination: lanthanum - 140,
  Irrigation 1 h,
  at least 2 hours of drying
• Test surface: lacquered panels, 35 x 45 cm or 50 x 50 cm
  • on clean plates
  • on plates with test soil

Carrying out the decontamination

Preparation and application of the ready-to-use decontaminant from the example formulations described below for liquid concentrates according to the invention is carried out by metering the respective concentrates to the decontamination water using Kärcher high-pressure cleaner (for example type HDS798C) and using the Kärcher foam nozzle (part no .: 2.637-926).

After the selected exposure time of the decontamination foam, a pressure-free (water line pressure) rinsing follows.

The assessment of the decontamination success is done by measuring the radioactive residual activity, based on the original contamination activity and is given in%.

Recipe Example 1: Complexing Concentrate (A)

30% by weight trisodium citrate 1% by weight sodium thiosulfate 0.2% by weight Preservative ACTICIDE FS Rest demineralized water

The components of the complexing agent concentrate (A) can be mixed together without special measures.

Formulation Example 2: Acid Surfactant Concentrate (B1)

40% by weight Sugar surfactant in the form of alkylpolyglycoside based on a natural fatty alcohol C ₈ -C ₁₀ (for example Glucopon ^® 215 CS UP Cognis BV, The Netherlands) 18% by weight Citric acid monohydrate Rest demineralized water

The components of the complexing agent concentrate (B1) can be mixed together without special measures.

Recipe Example 3: Acid Surfactant Concentrate (B1)

30% by weight Sugar surfactant in the form of alkylpolyglycoside based on a natural fatty alcohol C ₈ -C ₁₄ (for example Glucopon 215 CSUP ^® and / or Glucopon ^® 215 DK / HH Cognis BV) 5% by weight Sugar surfactant in the form of alkylpolyglycoside based on a natural fatty alcohol C ₈ -C ₁₀ (for example Glucopon ^® 600 EC UP Cognis BV) 19.5% by weight Citric acid monohydrate Rest demineralized water

The components of the complexing agent concentrate (B1) can be mixed together without special measures.

Formulation Example 4: Alkaline surfactant concentrate (B2)

15% by weight Trisodium nitrilotriacetate as complexing agent 3% by weight Alkyl (C ₁₀ ) polyethylene glycol ether + 8EO 3% by weight Fatty alcohol (C ₁₃ -C ₁₅ ) ethoxylate + 8EO Rest demineralized water pH = 12.5 (at 20 ° C), in 1% dilution pH = 10

The constituents of the complexing agent concentrate (B2) can be mixed with one another without special measures.

Formulation Example 5: Alkaline surfactant concentrate (B2)

8% by weight Alkyl (C ₁₀ ) polyethylene glycol ether + 8EO 8% by weight Fatty alcohol (C ₁₃ -C ₁₅ ) ethoxylate + 8EO 5% by weight N-2-hydroxyethyl-N-carboxymethyl fatty acid, amidoethylamine, Na salt (30% aqueous) 6% by weight alkali silicate 1% by weight alkyl benzene sulfonic acid Rest demineralized water pH = 13 (at 20 ° C); in 1% dilution pH = 11

The constituents of the complexing agent concentrate (B2) can be mixed with one another without special measures.

In the above formulation examples 1 to 5, the storage stability can be further improved by conventional auxiliaries.

Application Example 1

The complexing agent concentrate (A) from Example 1 is added together with the surfactant concentrate (B1) from Example 2 to the water stream delivered by a high-pressure cleaning device (eg Kärcher HDS789C) in the ratio (A) :( B1) = 5:10, so that in one case Total concentration of the two concentrates of 2 in the other case 5 wt .-% results.

The decontamination results on clean and test soil contaminated test plates are given in Table 2. The values given apply to decontamination fluids with a temperature of 15 ° C and an exposure time of 5 min.

Application Example 2:

The complexing agent concentrate (A) of Example 1 is applied together with the surfactant concentrate (B1) of Example 3 as described in Application Example 1 in a ratio (A1) :( B1) = 5:10. The decontamination results are given in Table 2.

Application Example 3

The complexing agent concentrate (A) of Example 1 is applied together with the surfactant concentrate (B2) of Example 4 as described in Application Example 1 in a ratio (A) :( B2) = 1.5: 10. The decontamination results are given in Table 2.

Application Example 4:

The complexing agent concentrate (A) of Example 1 is applied together with the surfactant concentrate (B2) of Example 5 as described in Application Example 1 in a ratio (A) :( B2) = 2.3: 10. The decontamination results are given in Table 2.

An exposure time of 5 minutes is sufficient in many cases. Longer reaction times bring further improved decontamination results, with exposure times of more than 10 min hardly show any greater effects.

Experiments conducted at a temperature of 50 ° C show that the decontamination results are only slightly dependent on the temperature. The achievable residual activity as a measure of the decontamination success depends, inter alia, on the type of contamination, on the material properties and on the type and condition of the surface to be decontaminated and on the decontamination agents and processes. On the one hand, it is therefore an objective indicator of the quality of decontamination. On the other hand, it is a relative size, since the effectiveness of decontamination can only be compared under uniform conditions, ie for one and the same system (radioactive material - surface - decontamination process).

• Adhäsion fester oder flüssiger radioaktiver Stoffe
• Adsorption, Ionenaustausch, Adsorption/Chemisorption von Radionukliden
• Diffusion und Eindringen von Radionukliden in die Tiefe der Oberfläche.

The success of decontamination depends on the adherence of the radioactive substances to the surface. This is determined by the various physico-chemical processes that accompany the contamination of the relevant surfaces and ultimately determine the type of decontamination. Thus, in practice a combination of different types of contamination may occur, such as:

• Adhesion of solid or liquid radioactive substances
• Adsorption, ion exchange, adsorption / chemisorption of radionuclides
• Diffusion and penetration of radionuclides into the depth of the surface.

Under the conditions of radioactive fall-out or rain-out after nuclear weapon detonations or accidents or accidents in nuclear facilities is usually a free settling of carriers of radioactive substances from the air in the form of solid particles or drops. Due to the different inclination of the surfaces, there is an uneven contamination of the outer surface of the affected objects.

The phases of the decontamination process in the case of contamination of surfaces with radioactive particles consists in the demolition of the particles (first phase) and their transport beyond the limits of the surface to be decontaminated (second phase).

In particular, the first phase depends critically on the nature of the decontaminant (irradiation). When using the aqueous surfactant and complexing agent concentrates according to the invention, the desired decontamination effect on the surface to be decontaminated can be ensured with optimum contact time. However, the success of decontamination requires that the second phase of decontamination (e.g., by effective high pressure water jet aftertreatment) reliably ensure removal of the detached radioactive particles from the surface.

Against this background, it becomes clear that the effectiveness of decontamination does not depend solely on the type of decontamination agent, but on the optimal consideration of all influencing factors relevant for decontamination. Thus, the decontamination process is always holistic.

The decontamination processes required in the ABC defense must therefore be universally usable for all expected operating conditions. This requires optimal interaction between highly effective decontamination agents (radiation agents) and adequate application and after-treatment systems. From this, the importance of being able to deploy the liquid concentrate set according to the invention with high-pressure jet devices becomes apparent.

Claims (25)

1. Liquid concentrate set for use in decontaminating radioactively contaminated surfaces, comprising an aqueous complexing agent concentrate and an aqueous surfactant concentrate, wherein

   (A) the complexing agent concentrate comprises

   (a) up to 35% by weight of a citric acid component comprising citric acid and/or one or more salts thereof; and

   (b) optionally, small amounts of a preservative agent and/or reducing agent;
   and wherein

   (B) the surfactant concentrate comprises one or more biodegradable surfactants;
   wherein the surfactant concentrate is an acidified surfactant concentrate (B1) or an alkalinized surfactant concentrate (B2);
   wherein the surfactant concentrate (B1) comprises as a surfactant one or more sugar-based surfactants, in particular in the form of natural fatty alcohol based alkyl polyglycosides, and wherein the surfactant concentrate (B2) comprises surfactants selected from alkyl polyethylene glycol ethers, fatty alcohol ethoxylates and carboxyalkyl fatty acid derivatives.
2. Liquid concentrate set in accordance with claim 1, characterized in that the complexing agent concentrate (A) comprises at least 20% by weight of citric acid component.
3. Liquid concentrate set in accordance with claim 1 or 2, characterized in that the complexing agent concentrate (A) comprises as a reducing agent at least 0.2% by weight of thiosulfate.
4. Liquid concentrate set in accordance with claim 3, characterized in that the proportion of thiosulfate in the complexing agent concentrate (A) is no more than 3% by weight.
5. Liquid concentrate set in accordance with any one of claims 1 to 4, characterized in that the alkyl polyglycosides of the surfactant concentrate (B1) are based on C₈-C₁₄, C₈-C₁₀ and/or C₁₂-C₁₄ fatty alcohols.
6. Liquid concentrate set in accordance with any one of claims 1 to 5, characterized in that the surfactant concentrate (B1) contains the sugar-based surfactants at a proportion from 20% to 55% by weight.
7. Liquid concentrate set in accordance with any one of claims 1 to 6, characterized in that the surfactant concentrate (B1) contains a proportion of a complexing agent.
8. Liquid concentrate set in accordance with claim 7, characterized in that the surfactant concentrate (B1) contains the complexing agent at a proportion from 10% to 25% by weight.
9. Liquid concentrate set in accordance with any one of claims 1 to 8, characterized in that the proportion of the surfactants in the surfactant concentrate (B2) is from 5% to 20% by weight.
10. Liquid concentrate set in accordance with claim 9, characterized in that the surfactant concentrate (B2) comprises from 2.5% to 10% by weight of one or more alkyl polyethylene glycol ethers and from 2.5% to 10% by weight of one or more fatty alcohol ethoxylates.
11. Liquid concentrate set in accordance with claim 10, characterized in that the surfactant concentrate (B2) comprises a proportion of a complexing agent.
12. Liquid concentrate set in accordance with claim 11, characterized in that the surfactant concentrate (B2) contains the complexing agent at a proportion from 10% to 25% by weight.
13. Liquid concentrate set in accordance with claim 11 or 12, characterized in that the complexing agent comprises nitrilo triacetate.
14. Liquid concentrate set in accordance with any one of claims 1 to 13, characterized in that the surfactant concentrate (B2) comprises a corrosion inhibitor.
15. Liquid concentrate set in accordance with claim 14, characterized in that the surfactant concentrate (B2) comprises in combination: 5% to 10% by weight of one or more carboxymethyl fatty acid derivatives, 5% to 10% by weight alkali silicate as a corrosion inhibitor and up to 2.5% by weight alkylbenzene sulfonic acid.
16. Use of a liquid concentrate set in accordance with any one of claims 1 to 15 for decontaminating radioactively contaminated surfaces.
17. Use in accordance with claim 16 characterized in that the concentrates (A) and (B1) are used in a ratio from 5:7 to 5: 12.
18. Use in accordance with claim 16 characterized in that the concentrates (A) and (B2) are used in a ratio from 1:10 to 3:10.
19. Use in accordance with claim 17 or 18 characterized in that the concentrates (A) and (B), (A) and (B1), or (A) and (B2) are in each case added in a total concentration from 0.5% to 5% by weight into a cleaning fluid, in particular water.
20. Method for decontaminating radioactively contaminated surfaces using a high-pressure cleaner, wherein a liquid concentrate set in accordance with any one of claims 1 to 15 is substantially continuously metered into a fluid to be applied by the high-pressure cleaner as the fluid is applied.
21. Method in accordance with claim 20, characterized in that the fluid is an aqueous fluid.
22. Method in accordance with claim 21, characterized in that the aqueous fluid is water.
23. Method in accordance with any one of claims 20 to 22, characterized in that the concentrate set is metered into the fluid to obtain a total concentration from 0.5% to 5% by weight in the fluid.
24. Method in accordance with any one of claims 20 to 23, characterized in that the concentrates (A) and (B1) are used in a ratio from 5:7 to 5:12.
25. Method in accordance with any one of claims 20 to 23, characterized in that the concentrates (A) and (B2) are used in a ratio from 1:10 to 3:10.