EP1520279A2

EP1520279A2 - Composition, foam and method for surface decontamination

Info

Publication number: EP1520279A2
Application number: EP03763928A
Authority: EP
Inventors: Sylvain Faure; Bruno Fournel; Paul Fuentes
Original assignee: Commissariat a lEnergie Atomique CEA; Compagnie Generale des Matieres Nucleaires SA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA; Orano Demantelement SAS
Priority date: 2002-07-08
Filing date: 2003-07-04
Publication date: 2005-04-06
Anticipated expiration: 2023-07-04
Also published as: WO2004008463A2; US7662754B2; AU2003260656A8; WO2004008463A3; US20060211592A1; EP1520279B1; UA83801C2; AU2003260656A1; RU2333556C2; ES2363081T3; DE60336397D1; CN1666299A; FR2841802A1; JP2005537462A; FR2841802B1; ATE502387T1; RU2005102937A; JP5214841B2; CN100351359C

Abstract

The invention concerns a composition for obtaining a gelled aqueous foam capable of decontaminating, stripping or degreasing a surface. The inventive composition comprises one or more surfactants, one or more acid or basic reagents and a gelling agent. The decontaminating foam derived from said composition has long life spans, generally ranging between 1 and 10 hours, ensuring prolonged action on the surface and high decontaminating efficacy. Said foams can be used for eliminating radioactivity from a large size inaccessible installation with complex shape by being simply filled or simply sprayed onto an accessible surface.

Description

COMPOSITION, FOAM AND METHOD FOR DECONTAMINATION OF

SURFACES

Description The subject of the present invention is a composition, a solution and a decontamination foam. The composition and the solution of the present invention make it possible to obtain an acidic or basic gelled aqueous foam which can be used to decontaminate surfaces.

The present invention finds for example an application in the decontamination of metallic surfaces contaminated for example by grease, by radioactive mineral deposits, by a very adherent oxide layer or in the mass.

It is particularly of great interest in radioactive decontamination, for example of large-volume nuclear installations, of complex geometry or inaccessible for which an economy of chemical reagents and liquid effluents used is necessary. For example, decontaminating the interior of large-volume tanks, for example from 20 to 100 m ³ , of spent fuel reprocessing plants containing fission product solutions is difficult because it is a medium very radiating. In fact, the dose rate can reach up to 40 GyH at the bottom of the tank, at a depth of -7.5 m. This level of irradiation practically prohibits any modification of existing tank equipment. In addition, the presence of numerous cooling coils in the tanks does not allow the introduction of tools for the application of decontamination treatments. Finally, the contaminated fluid cannot be extracted from the tanks with a view to recycling the foam without very costly additional arrangements. The means of transfer and the evacuation lines of the existing fluids must therefore be used.

PRIOR ART Numerous compositions and foams intended for surface treatments, in particular for cleaning, degreasing and / or radioactive decontamination of surfaces, have been developed. Unfortunately, they all have the same drawbacks: they have too short lifetimes and are difficult to control. Indeed, the foams of the prior art drain quickly, in a few minutes, and have a lifespan, defined as the time necessary for the total transformation of a given volume of foam into liquid, generally ranging from 1 to 10 minutes. .

This often leads, to ensure the effectiveness of the treatment, that it is necessary to repeatedly apply the foam to the surface to be treated. The amount of cleaning effluents and the difficulty of treatment are therefore increased.

In addition, the duration of contact of the foam with the surface being limited due to the short lifespan of the foams, the cleaning and treatment agents used must often be chosen so as to be very active in a very short time. Only high concentrations of products, or more corrosive products can therefore be used. This results in a limitation of the type of surface that can be treated, greater pollution, increased difficulties in rinsing the surfaces, and an increase in the cost of treatment.

There is therefore a real need for a foaming composition which makes it possible to overcome the drawbacks of the compositions of the prior art, that is to say which in particular makes it possible to prolong and control the life of the foam, to reduce the quantity of effluents, to use less corrosive cleaning agents, to use these agents in lower concentration, as well as to reduce the difficulty, the pollution as well as the cost of the treatment.

Exhibition of the invention

The object of the present invention is precisely to provide a solution to the numerous problems of the prior art by providing a composition intended for preparing an aqueous foaming solution making it possible to generate a foam which does not have the drawbacks of the prior art.

The composition of the present invention comprises:

- a foaming organic surfactant or a mixture of foaming surfactants,

- a gelling agent, and optionally,

- a decontamination agent. The foams generated from the composition of the present invention therefore comprise an agent gelling. Indeed, unexpectedly, the life of this foam is considerably increased compared to the foams of the prior art, and the foam thus prepared has a markedly improved ability, compared to the foams of the prior art, to remain in contact with a surface, even vertical, for several hours thus making it possible to ensure the decontamination of said surface in static or in spraying mode. This unexpected result leads to greater efficiency in the treatment of the surface, if necessary with lower concentrations of decontamination agents, for example cleaning, degreasing or decontamination, and a reduction in the quantity of effluents produced. In addition, it is possible to use active decontamination agents which are less corrosive than those of the prior art because the contact of the foam of the present invention with the surface to be treated is prolonged.

Advantageously, the composition of the present invention is an aqueous solution which comprises per liter of solution:

- 0.2 to 2% by weight of a foaming organic surfactant or of a mixture of foaming surfactants, - from 0.1 to 1.5% by weight of a gelling agent, and optionally,

- 0.2 to 7 moles of a decontamination agent.

This solution can be very easily prepared, for example at room temperature, by simple mixing, by adding to an aqueous solution, for example water, the surfactant (s), the gelling agent and, if it is useful, the decontamination agent for the composition of the present invention. According to the present invention, the gelling agent is preferably biodegradable. It is advantageously a thickening organic agent exhibiting a rheological behavior of the pseudoplastic type. According to the invention, the gelling agent can be chosen, for example, from the group comprising a water-soluble polymer or a hydrocolloid, a heteropolysaccharide chosen, for example, from the family of polyglucoside polymers with branched trisaccharide chains, such as xanthan gum, for example Rhodopol. 23 (trademark) marketed by the company Rhodia. It can also be chosen from the group comprising cellulose derivatives such as carboxymethylcellulose or a polysaccharide containing glucose as the only monomer, for example Amigel (trademark) sold by the company Alban Muller International.

According to the invention, the surfactant can be a nonionic foaming surfactant, chosen for example from the family of alkylpolyglucosides or alkylpolyetherglucosides. These surfactants are derived from natural glucose and have the advantage of being biodegradable. By way of example, there may be mentioned in particular the surfactants "Oramix CG-110" (trademark) sold by the company SEPPIC, "Glucopon. 215" (trademark) sold by the company AMI. According to the invention, the surfactant can be an amphoteric surfactant, chosen for example from the family of sulfobetaines, the family of alkylamidopropylhydroxysulfobetaines, for example Amonyl 675 SB (trademark) marketed by SEPPIC, or from the family of amine-oxides, for example Aromox MCD-W (trademark), or cocodimethylamine oxide sold by the company Akzo Nobel. The composition of the present invention may comprise a single surfactant or a mixture of surfactants chosen, for example, from the abovementioned families.

The composition of the present invention is presented mainly as a composition for generating a decontamination foam on a surface. Of course, the present invention also covers any composition making it possible to generate a foam, whatever its use, provided that it comprises a surfactant and a gelling agent.

For example, the composition of the present invention may also be a composition only comprising these two elements, and for preparing a rinsing foam, or ^a composition further comprising a surface treatment agent for preparing a foam surface treatment. The surface treatment agent can be, for example, an antioxidant, an antiseptic, etc.

The decontamination agent, when present, is chosen according to the use for which the composition is intended. When the composition is intended to generate a decontamination foam, the active agent is chosen in particular according to the nature of the contamination and the surface to be decontaminated, for example an acid or a mixture of acids, a base or a mixture bases, an oxidant, for example H ₂ 0 ₂ , a reducing agent, a disinfectant, etc. Those skilled in the art will know how to choose the decontamination agent according to their needs.

According to the invention, the active decontamination agent can be an acid or a mixture of acids, for example inorganic (s), advantageously chosen from the group comprising hydrochloric acid, nitric acid, sulfuric acid phosphoric acid and oxalic acid. According to the invention, the acid is advantageously present at a concentration of 0.2 to 7 moles, preferably from 0.3 to 7 moles, more preferably from 1 to 4 moles. These concentration ranges obviously relate to the concentration of H ⁺ ions. In addition, they are given for the preparation of 1 liter of foaming solution. They therefore represent the concentration in moles / 1 in 1 liter of foaming solution prepared from this composition.

According to the invention, the active decontamination agent can be a base or a mixture of bases, for example inorganic (s), advantageously chosen from the group comprising soda, potash, sodium carbonate, etc. According to the invention, the base is advantageously present at a concentration less than 2 mol.l ^"1 , preferably ranging from 0.5 to 1.5 mol.l ^{" 1} . These concentration ranges obviously relate to the concentration of OH ^" ions. In addition, they are given for the preparation of 1 liter of foaming solution. They therefore represent the concentration in moles / 1 in 1 liter of foaming solution prepared from this composition.

Thus, according to the aforementioned composition chosen, in accordance with the present invention, an acid or alkaline foam may have either dissolution properties of irradiating radioactive deposits, for example for the elimination of contaminations which are not fixed on a surface, or corrosion properties. surface checked for contamination attached to it.

Advantageously, the composition of the present invention has a viscosity at 0.3 rpm (Brookfield LVT, module x) of between 100 and 50,000 cP. This viscosity in fact allows an extended lifetime of the foam, as well as the possibility of projecting this solution by means of a nozzle, or of passing it through a porous lining to generate a foam.

The foam can be generated from this foaming solution by any foam generation system of the prior art: mechanical agitation, bubbling, static ball mixer or any other device ensuring the gas-liquid mixture, such as the devices described in FR-A-2 817 170, or a device using a spray or spray nozzle, etc. The foam generated can act static, it has a long lifespan, generally between 1 and 10 hours, and allows a duration of action on the controlled surface due to the control of the drainage time thanks to the gelling agent.

The present invention also relates to a method for decontaminating a surface comprising a step consisting in bringing the surface to be decontaminated into contact with a foam prepared from the composition of the present invention, that is to say with a foaming solution. according to the present invention.

The invention relates generally to the treatment, in particular to the decontamination, of surfaces of all types, for example glass, plastic, metal, etc., which may be large, which are not necessarily horizontal, but which can be tilted or even vertical. It can be used, for example, to decontaminate tanks, ventilation ducts, storage pools, glove boxes, vapor generators, pipes, floors, etc.

The decontamination foams can be used both in the context of periodic maintenance of existing industrial installations and in the context of dismantling such installations. These installations can for example be nuclear or industrial chemistry installations in general. The contacting of the foam with the surface to be treated can be done by conventional methods of filling, for example of a tank, a tank or a pipe, the walls of which are to be decontaminated; spraying or spraying onto the surface to be decontaminated; circulating the foam in an installation whose surfaces are to be decontaminated; etc.

For example, the foam can be applied to the surface to be decontaminated by any conventional spraying method using a pump and a nozzle. For spraying, the bursting of the foam jet on the surface to be decontaminated can be obtained for example with a flat jet or round jet nozzle. The short recovery time of the viscosity of the composition of the present invention allows the sprayed foam to adhere sufficiently long to the surface on which the foam is sprayed.

For example, to decontaminate a tank, the method of the present invention can simply consist in filling the tank with the foam of the present invention so that its surfaces are in contact with the foam. The foam then degrades naturally "static" under the effect of its gravitational drainage. The term "static" is then opposed to the dynamic application of foams consisting of a circulation or a spraying. The foam can also be applied only to the surfaces of the tank without necessarily filling it.

Also, the invention also relates to a process for decontaminating an installation which comprises the simple introduction of the foam by simple filling inside the installation, the "static" maintenance of this foam inside the volume, for example at a temperature of between 20 ° C. and 50 ° C., during the duration of drainage of the foam, most often between 1 and 10 hours, and sufficient to guarantee decontamination, then finally elimination of the drained liquid by simple emptying.

The surface decontamination treatment can consist of several applications of the same foam or with foams of different nature applied successively. Each of these treatments may include filling the volume to be decontaminated or spraying the foam onto a surface, keeping the foam static for several hours during its drainage and eliminating the liquid drained by simple draining. The inventors have noted, however, that, because of the lifetime of the foam of the present invention, which is longer than that of the foams of the prior art, a reduced number of applications, even a single application, is sufficient to obtain an effective treatment of a surface, where several applications were necessary with the foams of the prior art.

The duration of contacting will essentially depend on the nature of the decontamination, the composition and the nature of the foam, and the nature of the surface. Generally, a duration of contact which can range from 15 minutes to 10 hours is sufficient for effective treatment. This duration will be adapted as necessary in the application made of the present invention. The present invention guarantees an effective treatment, in particular decontamination, because the life of the foam, and therefore the time of contact of the foam with the wall is increased and adjusted by the addition of the gelling agent which delays drainage. In addition, on vertical surfaces, or even ceilings, the foams of the present invention, due to the presence of the gelling agent, adhere better than the foams of the prior art, which further increases the effectiveness of treatment or decontamination on these surfaces.

The drained liquid obtained at the end of the life of the foam of the present invention can be easily evacuated by draining and treated by conventional channels for decontaminating liquid effluents. It can also be regenerated, for example as described in document FR-A-2 817 170, to reconstitute a foam.

The method of the present invention may further comprise, after the step of bringing the surface to be decontaminated into contact with the foam, a step of rinsing said surface using a foam or a rinsing solution. The foam or the rinsing solution may be any foam or solution suitable depending on the nature of the decontamination foam and / or the surface to be rinsed. It may simply be a conventional rinsing foam, or a rinsing foam in accordance with the present invention, that is to say simply comprising a surfactant and a gelling agent, and, optionally, a conventional buffer compound allowing to neutralize the acid or basic decontamination previously used or a surface treatment compound. It can also be an aqueous solution, for example water. The advantages of such a treatment called "gelled foam" in accordance with the present invention compared to existing treatments are numerous.

First, there are the conventional advantages of foam treatment, that is to say in particular the reduction in the volume of effluents produced. Indeed, the foam consists of a dispersion of air bubbles in liquid and can be characterized by its expansion "F" defined under normal conditions of temperature and pressure by the following relation (1):

F = (Vg _az + liquid / liquid ⁼ "foam /" liquid in which V represents a volume of liquid, gas or foam as indicated.

The decontamination foams prepared from the composition of the present invention advantageously have an expansion of the order of 10 to 15. They therefore make it possible to decontaminate a large volume, for example of 100 m ³ , with less than 10 m ³ liquid.

Another advantage, in particular in the case of decontamination by spraying gelled foam onto surfaces of radioactive installations, is that the gelled foam of the present invention produces smaller amounts of radioactive effluents due to its long lifespan. , while projections of aqueous solutions or foams of the prior art produce large quantities of radioactive effluents for limited effectiveness due to the short contact time with the treated surfaces.

Another advantage of the present invention resides in the fact that following the natural drainage of the foam of the present invention, the contaminated drained liquid is recovered, and the surface only needs to be rinsed with very little water, c is to say approximately 1 liter / m ² . Thus, less liquid effluents to be treated are generated subsequently. This results in a simplification in terms of the overall contamination treatment chain, and a reduction in pollution.

Other characteristics and advantages of the present invention will become apparent on reading the following examples given, of course, by way of nonlimiting illustration with reference to the appended figures.

Brief description of the figures

Figure 1 is a schematic representation of the device used by the inventors to generate a foam from an aqueous solution of the composition of the present invention, and to measure the kinetics of drainage of the foam obtained.

FIG. 2 is a graph illustrating the kinetics of drainage expressed in fractions (F) of recovered liquid (in g) as a function of time (t) (in minutes), for different foams obtained from different compositions of the present invention.

Figure 3 is a graph illustrating kinetics of drainage expressed in volumes (V) of drained liquid (in ml) as a function of time (t) (in minutes), for different foams obtained on the one hand from different compositions of the present invention and on the other hand from compositions without ge1ifying agent.

Figure 4 is a schematic representation of the device used by the inventors to generate a foam from a composition of the present invention, and to implement a method of decontaminating a surface according to the present invention.

Figure 5 is a graph illustrating the influence of the quantity of xanthan gum (Xant) (in g / 1), on the delay in drainage (foam stability): height of liquid drained (H) (in mm) as a function of time (t) (in minutes). In this figure, the legend indicates the different foaming solutions tested, F denotes the expansion of each foam obtained.

EXAMPLES

EXAMPLE 1: BACKGROUND FOAMS The drainage and efficiency properties of foams prepared from five foaming solutions were each studied, each containing a reference mixture of two surfactants: Oramix (trademark) at 8 g / 1. and Amoyl (trademark) at 3 g / 1.

A formulation, called the reference formulation (allowing the generation of a reference foam), did not contain a decontamination agent.

The other four formulations differed in the nature of the decontamination agent: 5 _ ^1st formulation: sodium carbonate at a concentration of 1 mol.l ^"1 ,

- ^2nd formulation: a mixture of hydrofluoric acid at a concentration of 0.05 mol.l ^"1 and nitric acid at a concentration of

10. 2 mol.l ^"1 ,

- ^3rd formulation: a mixture of oxalic acid at a concentration of 0.6 mol.l ^"1 and nitric acid at a concentration of 0.5 ^{mol.l" 1,}

- 4 ^th formulation: a mixture of hydrogen peroxide to 15, a concentration of 1 mol.l ^"1 and nitric acid at a concentration of 3 ^{mol.l" 1.}

No cloud point was observed between 20 and 50 ° C

These foaming solutions were then

20 used to generate controlled expansion foams using a static glass ball generator (Ql = flow rate of foaming solution, Qg = air flow rate, F = (Qg + Ql) / Ql).

An experimental protocol has been developed for tracing the drainage kinetics of each of the foams under conditions close to an industrial reality by means of the device (I) shown diagrammatically in FIG. 1. In this figure, the following references indicate the elements following of the device (I): 30 (3): tank for preparing the foaming solution; (5): foaming solution; (7): agitator mechanical ; (9) pump; (11): compressed air supply system; (13): flow regulator; (15): foam generator; (17) pipes; (19): foam receiving tank; (21): foam; (23): manual valve; and (25): drained liquid recovery tank.

Each of the five formulations has excellent foamability since foams with an expansion of more than 10 have been prepared. It appears from the kinetic studies that the presence of the decontamination agents does not or hardly modify the drainage kinetics with respect to the reference foam without decontamination agent as shown in FIG. 2. Over all of the formulations prepared, more than the half of the liquid drains in less than 8 minutes and the lifespans of each of the formulations remain short (15 to 25 minutes).

EXAMPLE 2 FOAMS OF THE PRESENT INVENTION

The addition of a small amount, that is to say 0.1% by weight or 1 g / l, of xanthan gum, used as a gelling agent within the meaning of the present invention, to the various formulations of foaming solutions of Example 1 stabilizes all of the foams as shown in Figure 3.

The addition of 1 g / 1 of xanthan gum has the effect of considerably delaying the drainage of each of the foam formulations and thereby increasing the life of the foam.

Table 1 below collates the time tχ ₂ necessary so that half of the liquid contained in the foam drains and the lifespan ti the time so that all the liquid of the foam drains for the various foams studied.

Table 1: Lifetime ti and time tχ _{/ 2} for different foam formulations

With an amount of 1 g / 1 of xanthan gum, the time tχ _{/ 2} is approximately 20 minutes for the two acid formulations containing hydrogen peroxide and hydrofluoric acid. The foam containing oxalic acid is the most stable of the acid foams with a time tχ _{/ 2} of almost 40 minutes. Finally, the alkaline foam drains very slowly since it takes almost an hour and a half to recover half of the liquid.

These results show that the addition of a small amount of xanthan gum, 0.1% by weight or 1 g / 1, stabilizes all of the formulations of Example 1.

In fact, very substantial gains on the stability of the formulations are obtained since shelf lives of between 50 and 120 minutes have been observed with the simple addition of a small amount of gum, of xanthan.

Tests have been carried out to demonstrate the link between the amount of gelling agent and the life of the foam.

Figure 5 is a graph illustrating the influence of the amount of xanthan gum on the delay in drainage (foam stability).

As long as the liquid does not drain, the foam is stable. The foam does not drain for 20 minutes for 1 g / 1 of xanthan gum, 60 minutes for 2 g / 1 of xanthan gum and 120 minutes for 3 g / 1 of xanthan gum. It also appears on this graph that the foaming solutions without gelling agent drain immediately (t = 0 minutes).

EXAMPLE 3 TREATMENT OF A SURFACE WITH FOAMS OF THE PRESENT INVENTION

The effectiveness of the foams of Example 2 was also tested for the decontamination of surfaces.

The objective is indeed to demonstrate that the foams prepared with the foaming solutions of the present invention can, for example, dissolve a deposit of reconstituted insolubles simulating a real irradiating deposit adhering to a wall. Stainless steel plates covered with adherent deposits are suspended in a 30-liter plexiglass column in the device (II) shown diagrammatically in FIG. 4. In this figure, the following references indicate the following elements of the device (II):

(40): plexiglass column; (42): suspended steel plates; (44): valve; (46) glass bead bed foam generator; (48): compressed air supply system; (50): pipe for supplying the foam generated in the column (40); (52): pipe for recovering the drainage liquid; (54) valve; (56): pump; (58): pulsation damper; (60): filter; (62): sampling tube; (64): reactor for preparing the foaming solution; (66) foaming solution; (68): mechanical stirrer; (70): thermometer; (72): water supply line; (74): supply line for compounds of the foaming solution; (76): supply line for the foam generator (46) in foaming solution; (78) alcohol tank; (80) alcohol metering pump; (82) foam recovery line.

The two plates (42) covered with the deposit to be dissolved are voluntarily placed in the center of the column. The column is filled until the samples are completely immersed and the generation is stopped when the highest edge of each of the two plates is at a depth of 10 cm in the foam. This level of foam corresponds to 20 liters of foam and is deliberately limited to quantify the effectiveness of the upper part of the foam.

The low immersion of the plates is detrimental since the foam dries up from the top under the effect of gravitational drainage. The foam / deposit contact times are then shorter and may prove to be insufficient to ensure effective dissolution. However, if the dissolution is important in the upper part of the foam, it will be even more so within the foam. The stopwatch is started when the column has been filled with 20 liters of foam and the foam is left to act statically. The sample is removed after a given time in order to evaluate the dissolution of the deposit by weighing. If two samples have been placed, one can be removed after one hour of immersion for example, the other after two hours.

To carry out these deposit dissolution experiments, the foams are obtained successively in the following manner. 4 liters of a solution containing one of the three reactants, the surfactants and the xanthan gum are prepared. The solution is placed under stirring in the reactor (64) thermostatically controlled between 20 and 50 ° C. Then, a gas-liquid mixture of known proportion is then generated through a bed of glass beads: approximately 12 liters per hour of acid solution are mixed with a controlled gas flow of 180 liters per hour of air to generate a relatively moist foam of known expansion close to 14. Tests in the foam phase were carried out for example with the foaming carbonate formulation and containing 1.5 g / 1 of xanthan gum, of the brand Rhodopol 23. The life of the foam is then of the order of 2 to 3 hours.

A first adherent deposit, sample 1, with a thickness of 0.5 mm, or 1 g per 25 cm ² , is placed within the column. The objective of the test is to allow a carbonated foam to act statically and to recover the sample once the foam has returned to the liquid state. The test is carried out by preheating the foaming solution to 50 ° C, which allows a temperature within the foam to be obtained of 33 ° C. After one hour, the temperature of the foam is 30 ° C, and after two hours 28 ° C. After 3 hours, the temperature is that of the laboratory (27 ° C) and the carbonated foam, obtained from a 1 M solution, has completely drained.

The sample, invisible at first because immersed in the foam, appears to be completely free of the deposit.

This qualitative result, very positive, motivated the introduction of two thicker deposits of MoZr approximately 1.2 mm thick so as to quantify the speed of dissolution over the first two hours of treatment. One deposit is removed after one hour of contact with the foam, the other after two hours. The results are collated in Table 2 on the next page.

It appears that the mass dissolved in two hours, i.e. 0.74 g or 0.71 g, is almost double that dissolved in the first hour, ie 0.42 g (slightly lower since the average temperature over the second hour is 3 ° C lower). At an average temperature of the foam of 30 ° C, the dissolution rate of a deposit of 25 cm ² in contact with the foam is of the order of 0.4 g / h, or again 0.2 mm / h , to compare with 0.8 g / h obtained in the liquid phase at 30 ° C. This dissolution rate, almost constant over the first two hours, shows, as in the case of the liquid phase, that the dissolution is regular and homogeneous on the surface. It advantageously makes it possible to completely dissolve an irradiating deposit of 0.5 mm in 3 hours at 30 ° C.

This result makes it possible to consider using, rather than rinsing with sodium carbonate in the liquid phase, a rinsing in the foam phase according to the invention which makes it possible to reduce the amount of sodium used which is detrimental for the ultimate formation of the packaging glasses. .

Table 2: Mass losses of a MoZr deposit on contact with a static foam containing sodium carbonate (1 M)

Claims

1. Use of an aqueous solution which comprises per liter of solution: - 0.2 to 2% by weight of organic foaming surfactant or of a mixture of foaming surfactants,

- 0.1 to 1.5% by weight of gelling agent, and optionally, - 0.2 to 7 moles of acid or inorganic base of radioactive decontamination or mixture of acids or inorganic bases of radioactive decontamination , in a radioactive decontamination process of a surface.

2. Use according to claim 1 or 2, wherein the surfactant is a nonionic foaming surfactant.

3. Use according to claim 1, in which the surfactant is a nonionic foaming surfactant chosen from the family of alkylpolyglucosides or alkylpolyetherglucosides.

4. Use according to claim 1, wherein the surfactant is an amphoteric surfactant.

5. Use according to claim 1, in which the surfactant is a surfactant amphoteric chosen from the family of sulfobetaines, from the family of alkylamidopropylhydroxysulfobetaines or from the family of amine oxides.

6. Use according to claim 1, in which the acid is chosen from the group comprising hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid and oxalic acid, or is a mixture of acids of this group.

7. Use according to claim 1, wherein the acid is in an amount of 0.3 to 7 moles.

8. Use according to claim 1, wherein the acid is in an amount of 1 to 4 moles.

9. Use according to claim 1, in which the base is chosen from the group comprising sodium hydroxide, potassium hydroxide, sodium carbonate, or is a mixture of bases from this group.

10. Use according to claim 1, wherein the base is in an amount less than 2 moles.

11. Use according to claim 1, wherein the base is in an amount of 0.5 to 1.5 moles.

12. Use according to claim 1, in which the gelling agent is an organic thickening agent exhibiting a rheological behavior of the pseudo-plastic type.

13. Use according to claim 1, in which the gelling agent is chosen from the group comprising a water-soluble polymer, a hydrocolloid, a heteropolysaccharide, or from the group comprising cellulose derivatives.

14. Use according to claim 1, in which the gelling agent is chosen from the group comprising heteropolysaccharides chosen from the family of polyglucoside polymers with branched trisaccharide chains; cellulose derivatives such as carboxymethylcellulose or a polysaccharide containing glucose as the only monomer.

15. Use according to claim 1, in which the gelling agent is xanthan gum.

16. A method for decontaminating a surface comprising a step consisting in bringing the surface to be decontaminated into contact with a foam prepared from a composition according to any one of claims 1 to 15.

17. A method of decontaminating a surface according to claim 16, in which bringing the surface to be decontaminated into contact with the foam lasts from 1 to 10 hours.

18. A method of decontaminating a surface according to claim 16, further comprising, after the step of bringing the surface to be decontaminated into contact with the foam, a step of rinsing said surface using a rinsing solution .

19. The decontamination method according to claim 16, 17 or 18, wherein the decontamination is a radioactive decontamination.