JP2022550787A - Method for decontaminating gas-containing metal parts using laser irradiation in liquid media - Google Patents

Abstract

Kind Code: A1 The present invention relates to a method for decontaminating gas-containing metal parts (1) in a liquid medium (2) and to a device implementing this contamination method. A method of the present invention is a method for decontaminating a gas-containing metal part (1) by laser irradiation in a liquid medium (2), wherein the metal part (1) is a liquid medium (2) A glass interface (5) placed in and able to pass the pulsed laser beam wavelength is placed in the liquid medium at a distance of 10 mm to 250 mm from said part, between the interface and the metal part (1) 1, a circulation system (8) for the liquid medium (2), capable of directing the arranged liquid medium (2), is arranged in whole or in part in the liquid medium (2) along said parts; 000 nm to 1,080 nm wavelength, fluence of 30 J/cm to 200 J/cm, and power peak of 1.2 kW to 7.5 kW, travel speed of 3,000 mm/s to 20,000 mm/s. It relates to a method, wherein a beam of laser is applied to a metal part (1). [Selection drawing] Fig. 1

Description

The present invention relates to a method for decontaminating gas-containing metal parts, especially in the nuclear field. In particular, the present invention relates to a method of decontaminating metal parts containing gases, which may be radioactive, using laser irradiation in liquid media.

In the nuclear industry, metal parts present in nuclear installations, especially those in contact with carrier liquids containing radioactive compounds, may be contaminated with radioactive substances. This contamination can be superficial or internal. In order to avoid contamination of the environment during the closure of nuclear installations, or to limit human exposure to radioactivity emitted by these components during maintenance work or during closure of these installations. It is often necessary to decontaminate metal parts present in

Currently, there are various solutions for decontaminating radioactive surfaces of metal parts, for example using chemicals, hydromechanical techniques based on high-pressure water jets, or using lasers.

It can also decontaminate a thin layer of contaminants on the surface of the metal waste but not inside it, as described in EP0091646, and the application of the laser tends to redeposit radioactive aerosols. Reference can be made to the method of decontamination with a pulsed laser carried out in air, in which a molten zone is produced on this surface.

Among the radioactive materials that can contaminate metal parts found within nuclear facilities, whether nuclear reactors, fusion facilities, or spent fuel processing units, are radioactive isotopes of hydrogen, Radioactive gases such as tritium ( ³ H) are found that can diffuse into and lodge in the base metal of metal parts.

Tritiated waste is found mostly in solid form and is used in defense activities, research activities of the Atomic Energy and Alternative Energy Agency, and the ITER fusion device (International Thermal Energy Agency), a nuclear fusion reactor project using deuterium and tritium as fuel. It will result in the near future operation and decontamination activities at the nuclear fusion experimental reactor. Given the ability of tritium to diffuse into materials, management of tritiated waste by containment is difficult and decontamination techniques on the surface of the waste, especially metals, are not suitable.

Management of tritiated metal waste involves the final storage of this waste. Nonetheless, it is necessary to perform initial treatment of the waste to reduce its tritium content and degassing level. These treatments may consist of simply removing this waste and then storing it in an upstream facility and/or subjecting it to heat or melt treatment.

For example, reference can be made to the method described in EP 0204634, which proposes to melt tritiated metal waste, extract the adsorbed gases in the waste mass and subject it to a detritification process. Nonetheless, in order to accomplish this task, it is necessary to recover the emitted radioactive gas from dispersing in the air or in nearby components and from recontaminating the metal waste. be.

Thus, a solution that allows effective decontamination of metal parts containing gases that can be radioactive, such as tritium, while limiting the risk of this gas dispersing into the air and thus of environmental and human contamination. measures are needed. There is also a need to prevent and/or limit the risk of radioactive gases redepositing onto and into metal waste and adjacent components.

It is therefore an object of the present application to enable effective decontamination of metal parts containing a gas, which may be radioactive, such as tritium, i.e. metal parts whose base metal has adsorbed this gas, while at the same time is dispersed in the air, reducing the risk of redeposition of gas particles on the surface of the component and further contamination of the component by diffusion into the material.

To do this, the invention proposes a method for decontaminating gas-containing metal parts by laser irradiation in a liquid medium, and a device implementing this method.

A first object of the present invention is a method of decontaminating gas-containing metal parts by laser irradiation in a liquid medium, comprising:
A metal part is placed in a liquid medium,
a glass interface that is permeable to the pulsed laser beam wavelength is positioned in the liquid medium, the interface being positioned between the metal part and the beam at a distance of 10 mm to 250 mm from the metal part;
all or part of a liquid medium circulation system capable of directing a liquid medium disposed between the interface and the metal part is disposed in the liquid medium along said part;
A beam of a pulsed laser, emitting at a wavelength of 1,000 nm to 1,080 nm, a fluence of 30 J/cm ² to 200 J/cm ² , and a power peak of 1.2 kW to 7.5 kW, is applied to the metal part. The beam is applied to the metal part at a travel speed of 3,000 mm/s to 20,000 mm/s.

A second object of the present invention is a device for decontaminating gas-containing metal parts by means of a laser in a liquid medium, the device comprising:
a chamber containing a liquid medium in which the metal part is immersed;
A pulsed laser capable of emitting a pulsed laser beam at a wavelength of 1,000 nm to 1,080 nm, a fluence of 30 J/cm ² to 200 J/cm ² , and a power peak of 1.2 kW to 7.5 kW. a laser with an irradiation head;
a glass interface permeable to the pulsed laser beam wavelength, disposed in a liquid medium, the interface being immersed in the liquid medium and disposed between the metal part and the beam;
a liquid medium circulation system disposed in whole or in part between the component and the glass interface and capable of directing the liquid medium disposed between the interface and the metal component along the component; comprising, relating to a device.

FIG. 1 is a diagram of a device according to the invention, realized according to an embodiment, not immersed in a liquid medium, comprising a metal part (1), a liquid medium (2) and a chamber containing the liquid medium (3). , the device including a pulsed laser head (4), a glass interface (5), a nozzle (6), a motor (7), a circulation system (8) and a hook support (9). is. FIG. 1 shows a device according to the invention, realized according to an embodiment, immersed in a liquid medium, comprising a metal part (1), a liquid medium (2) and a chamber containing the liquid medium (3). , a pulsed laser head (4), a glass interface (5), a nozzle (6), a motor (7), a circulation system (8), a hook support (9), and a closed chamber (10). 1 is a diagram of a device, including

The method proposed by the present inventors for decontaminating metal parts containing radioactive gases by laser irradiation in a liquid medium, and the device implementing this method, are advantageously designed to contain gases that can be radioactive. While allowing effective decontamination of metal parts adsorbed from materials and reducing the risk of this potentially radioactive gas dispersing into the air and thus of environmental and human contamination, It also reduces further contamination of the part by redeposition of gas particles on the surface and their diffusion into the material. In particular, the purpose of the present application makes it possible to avoid or reduce the drawbacks of implementing the use of pulsed lasers in liquid media, such as reduced decontamination efficiency and fume generation at the liquid surface. . Indeed, when implementing the present invention, certain drawbacks associated with irradiating a part with a laser beam in a liquid medium have been identified. In particular, mention may be made of the presence of eddy current phenomena in the liquid medium at the surface of the component, which prevents effective and homogeneous decontamination of the component without altering the surface.

In fact, the inventors have found that the liquid flows laminarly between the interface and the surface of the metal part, with the glass interface existing between the metal part and the pulsed laser beam in close proximity to the part. It has been shown that decontamination of metal parts containing gases, which may be radioactive, can be advantageously and effectively achieved in a liquid medium using a circulation system of the liquid medium that can be attached.

A first object of the present invention therefore relates to a method for decontaminating gas-containing metal parts by laser irradiation in a liquid medium,
A metal part is placed in a liquid medium,
a glass interface that is permeable to the pulsed laser beam wavelength is positioned in the liquid medium, the interface being positioned between the metal part and the beam at a distance of 10 mm to 250 mm from the metal part;
all or part of a liquid medium circulation system capable of directing a liquid medium disposed between the interface and the metal part is disposed in the liquid medium along said part;
A beam of a pulsed laser, emitting at a wavelength of 1,000 nm to 1,080 nm, a fluence of 30 J/cm ² to 200 J/cm ² , and a power peak of 1.2 kW to 7.5 kW, is applied to the metal part. The beam is applied to the metal part at a travel speed of 3,000 mm/sec to 20,000 mm/sec.

A pulsed laser has an irradiation head. A coherent light source producing a pulsed laser beam and optics for focusing and directing this beam at least along an axis along the surface of the part to be decontaminated, by a "laser head" or "laser head" means module. By "gas-containing metal part" is meant a metal part whose base metal, i.e. not only the surface but also the metallic material of which the part is composed, contains a gas such as the radioactive gas hydrogen or even tritium. .

The present invention is of particular interest in decontaminating metal parts containing radioactive gases, since radioactive gases, especially tritium, have the ability to diffuse into metallic materials to depths of 35 μm and even 50 μm. In particular, tritium can contaminate metal parts to a depth of about 10 μm. Preferably, the metal part realized within the scope of the invention is a metal part containing a radioactive gas, more preferably said gas is tritium.

The ability of a method to effectively decontaminate a gas-containing metal part in a liquid medium depends on the ability of the method to strip or ablate the metal part, and in particular to remove all or part of the gas present in the material. Determined by the depth of ablation of the part, which must be sufficient to release. A method according to the invention is considered effective when it is possible to ablate the base metal of the component by at least 10 μm.

By "base metal" is meant the metal material that makes up the metal part.

The metal part may be in direct or indirect contact with the nuclear installation and may be subjected to the method according to the invention in separate or whole form. The base metal from which the part is constructed is, for example, a metal alloy such as stainless steel, black steel, or even INCONEL® 600, 625, 718, which contain high proportions of nickel, chromium and iron. be able to.

Although this application refers to metal parts in the singular for clarity, it is possible to implement methods using one or more metal parts simultaneously or sequentially.

The liquid medium may be contained in a chamber whose size and composition are adapted to the metal part, to the liquid medium in question and to the method according to the invention.

The liquid medium may be water, pure water, a highly concentrated chemical containing cerium, or a nitrifying liquid. Preferably, the liquid medium of interest within the scope of the present invention is water, preferably pure water.

Within the scope of the method according to the invention, the metal part, the glass interface and the circulation system of the liquid medium are independent of each other and may be completely or partially immersed in the liquid medium. Nevertheless, care is taken to ensure that the part of the component undergoing the decontamination process is completely immersed in the medium. The glass interface may, for example, be completely immersed in the liquid medium or placed on the surface of this medium.

The glass interface used in the method according to the invention may comprise an antireflection surface, for example made of fused silica and having a refractive index between 1.20 and 1.45.

The thickness of this interface may vary depending on the part to be decontaminated, the liquid medium in which the part is found, the gas contaminating the part, or even the parameters of the method. For example, the thickness of the glass interface may be between 5 mm and 100 mm, preferably between 10 mm and 50 mm.

In particular, the glass interface is connected in a permanent or separable manner to the irradiation head of the pulsed laser by means of a hook system or incorporated into the laser irradiation head, preferably on the front face of said head.

The fluence corresponds to the energy density of the laser per unit of surface and, according to a preferred embodiment of the method according to the invention, the fluence may be between 50 J/cm ² and 150 J/cm ² .

The power peak in Watts corresponds to the ratio of the energy per pulse in Joules to the pulse duration in seconds, and according to a preferred embodiment of the method according to the invention the power peak is between 1.2 kW and 7.5 kW. There may be.

Advantageously, the width of the pulsed laser beam is adapted to modulate and adapt to the dimensions of the metal parts to be decontaminated.

Preferably, the pulsed laser applied in the method according to the invention is a Nd:YAG laser emitting at a wavelength of 1064 nm.

In a particular embodiment of the invention, the wavelength is 1064 nm, the fluence is 50 J/cm ² to 150 J/cm ² , the power peak is 2 kW to 4 kW, and the travel speed is 3,000 mm/sec to 20,000 mm/sec.

Travel speed or scan speed refers to the speed at which the pulsed laser beam is applied to the metal part. According to a preferred embodiment of the method according to the invention, the moving speed is between 5,000 mm/s and 10,000 mm/s.

In the method according to the invention, the pulsed laser beam is applied at sufficient times and sufficient to release the gas from the material, i.e. to ablate the base metal of the component to a depth where all or part of the gas is found. applied to metal parts for a long period of time.

The number of passes depends on the laser parameters, the dimensions of the metal part, and the gas type and depth of contamination by the gas. In particular, the laser beam in the method according to the invention is applied to the part 10 to 150 times, preferably 30 to 100 times, at the same location.

By "at the same place" is meant that each pass is performed at the same place as the previous pass. Preferably, the pulsed laser beam is applied to the metal part in the same direction for each pass.

In a particular aspect, the invention relates to a method according to the first object, wherein the liquid medium is water, the glass interface is placed in water at a distance of 10 mm to 50 mm from said part, the wavelength is 1064 nm, the fluence is 100 J/cm ² to 150 J/cm ² , with a power peak of 2 kW to 4 kW, the laser beam is applied to the metal part 30 to 60 times at a travel speed of 5,000 mm/sec to 10,000 mm/sec.

During the implementation of the method according to the invention, the pulsed laser head is placed at a sufficient focal distance from the metal part that the use of the laser is effective. This focal length corresponds to the distance between the focusing device of the laser irradiation head and the surface of the metal part to be decontaminated.

In particular, the pulsed laser head is placed at a focal length that increases in value by 25% with respect to the value of the distance between the metal part and the surface of the liquid.

The method according to the invention may be realized according to an immersion mode, ie according to a non-immersion mode in which the laser irradiation head is completely or partially immersed in the liquid medium or the head is not immersed in the liquid medium.

According to a particular embodiment, the laser irradiation head, to which the glass interface is connected via a hook system, is arranged outside the liquid medium. Preferably, according to this embodiment, the glass interface is arranged at the surface of the liquid.

According to another particular embodiment, the laser irradiation head, to which the glass interface is connected or incorporated via a hook system, is completely or partially immersed in the liquid medium. In this particular embodiment, the irradiation head is enclosed in a closed chamber.

In particular, the liquid circulation system realized by the method according to the invention comprises a motor and a nozzle, said nozzle being immersed in a liquid medium and extending along an axis parallel to the metal part between the interface and the metal part. placed. The motor may also be immersed in the liquid medium with a closed chamber enclosing it.

As mentioned above, the circulation system of the liquid medium advantageously circulates the liquid medium arranged between the interface and the metal part precisely at the surface of the part and over the length of the part, i.e. along the length of the part. Allows to be oriented with laminar flow along the directional axis.

In particular, according to the invention, the nozzles of the circulation system are arranged between the interface and the part so as to ensure the direction of the liquid medium over the length of the part, using laminar flow, along the longitudinal axis of the part. placed at a sufficient distance from

The motors of the circulation system have sufficient power to ensure said orientation of the liquid medium.

A method according to the invention may comprise an additional step of recovering the liquid medium, wherein the gas after decontaminating the part is placed through a recovery system in contact with the liquid medium.

Preferably, the collection system comprises a tube having one end in contact with the liquid medium and the other end in contact with the chamber for collecting the contaminated liquid, said system being directly or indirectly connected to said tube to collect the liquid. A pump is provided that can draw and direct toward the collection chamber.

The step of recovering the gas-containing liquid medium may be performed during or after, preferably before implementing the decontamination method.

In one aspect, the recovered liquid medium is placed in a tank to reduce the radioactivity of tritium by simple radioactive decay. For example, the liquid medium may be placed for a period equal to its radioactive decay time of 12.3 years such that the activity of tritium is reduced by a factor of two.

In another aspect, the method according to the invention comprises an additional decontamination step of the liquid medium containing the recovered gas, in particular radioactive gas.

This step may be performed using any one of the methods known in the art for decontaminating liquid effluents containing radioactive gases such as tritium.

An example of a liquid decontamination method is based on differences in volatility between water isotopes, or even ions in the electrolyte leading to differences in electrolytic pressure and decomposition of tritium into gaseous dioxygen and dihydrogen. Reference can be made to vacuum distillation, which is based on the separation of tritium by direct electrolysis in water, based on the diffusion of . Also, the step of transferring the tritiated liquid, particularly in water, in the presence of a platinum-based catalyst, to a circulating gaseous dihydrogen stream in countercurrent, followed by cryogenic distillation, in particular, to remove gaseous tritium. We can refer to a chemical exchange process that includes two main steps, the steps of separating and concentrating the .

The invention also relates to a device implementing the method according to the first object. The device according to the invention comprises a chamber (1) containing a liquid medium, a pulsed laser, a glass interface (5) and a liquid medium circulation system (8).

More precisely, the second object of the invention relates to a device for decontaminating gas-containing metallic parts (1) by means of a laser in a liquid medium (2), the device comprising
a chamber (3) containing a liquid medium in which the metal parts are immersed;
A pulsed laser capable of emitting a pulsed laser beam at a wavelength of 1,000 nm to 1,080 nm, a fluence of 30 J/cm ² to 200 J/cm ² , and a power peak of 1.2 kW to 7.5 kW. a laser with an irradiation head (4);
a glass interface (5) which is immersed in a liquid medium (2) and which is immersed in a liquid medium (2) and which is capable of passing the pulsed laser beam wavelength and which is positioned between the metal part and said beam;
of the liquid medium, wholly or partially disposed between the interface and the metal part, and capable of directing the liquid medium disposed between the interface (5) and the metal part (1) along said part. a circulation system (8).

Elements described above with respect to the properties, definitions, structures, configurations, advantages of the method according to the first object of the invention apply equally as these same properties to the device according to the second object of the invention.

The dimensions of the chamber depend on the dimensions of the metal parts to be decontaminated.

Preferably, the pulsed laser applied in the method according to the invention is a laser whose amplification medium consists of neodymium-doped yttrium aluminum garnet, commonly known as a Nd:YAG laser. Even more preferably, the pulsed laser is a Nd:YAG laser emitting at a wavelength of 1064 nm.

In a particular embodiment, the glass interface (5) is coupled in a permanent or separable manner to the irradiation head (4) of the pulsed laser by means of a hook system (9), or It is preferably built into the front face of the head.

According to a particular embodiment, the laser irradiation head (4) to which the glass interface (5) is attached via a hook system (9) is placed outside the liquid medium (Fig. 1). Preferably, according to this embodiment, the glass interface (5) is arranged on the surface of the liquid medium (2).

According to another particular embodiment, the laser irradiation head (4), to which the glass interface (5) is attached or incorporated via a hook system (9), is completely or partially displaced into the liquid medium (2). is immersed in In another particular aspect of this embodiment of the device according to the invention, the irradiation head (4) is enclosed by a closed chamber (10) (Fig. 2). Complete or partial immersion of the irradiation head (4) in the liquid medium allows a simple implementation of the method according to the invention in various forms.

In particular, the liquid medium circulation system (8) comprises a motor (7) and a nozzle (6) immersed in the liquid medium (2) and along an axis parallel to the metal parts, the interface (5) ) and the metal part (1).

In a particular embodiment, a device according to the invention is connected directly or indirectly to a tube having one of its ends in contact with the liquid medium and the other end in contact with the chamber for collecting the liquid, and a pump capable of aspirating liquid.

The invention also relates to the use of the device according to the invention for decontaminating metal parts containing gases, in particular tritium, by means of a laser in a liquid medium.

The following examples are given for the purpose of illustrating the invention without limiting its scope in any way.

Example 1 Realization of a method for decontaminating metal parts in a liquid medium with a pulsed laser without a glass plate and without a liquid circulation system.

This study will allow us to macroscopically observe whether pulsed lasers have the ability to decontaminate metal parts in liquid media. The ability to decontaminate a metal part is evaluated here first in comparison with the ability of the method to remove paint marks from the surface of the part.

MATERIALS AND METHODS An Inox 304L metal plate containing no radioactive gases was used for this test and a paint marking zone was provided. These plates were immersed in a chamber containing pure water as the liquid medium.

The pulsed laser used emits at a wavelength of 1064 nm, has a power of 100 W, a frequency of 100 KHz and a focal length of 100 mm. Several distances between the metal part and the surface of the liquid were tested. Ten consecutive passes were performed with a total duration of approximately 80 seconds and 10% coverage.

Results: Efficiency of the method was assessed visually.

The realized method fails to strip the sample efficiently and homogeneously in the presence of water, regardless of the distance between the part and the liquid surface. A bubble of delaminated material is seen to form on the surface of the metal part. It has also been found that fumes are present on the surfaces of chambers containing liquid media and in which metal parts are placed. The tested method cannot ablate the base metal of the part.

To be able to avoid phenomena associated with the formation of bubbles of material on the surface of metal parts and thus to make available a method by which samples can be homogeneously decontaminated and ablated in the presence of water. , the applied method needs to be optimized.

Example 2 Realization of an optimized method of decontaminating metal parts in a liquid medium by a pulsed laser with a liquid circulation system.

This study is similar to that performed in Example 1 and reduces phenomena associated with the formation of bubbles of material on the surface of metal parts and thus homogenizes the sample in the presence of water. A system has been realized which makes it possible to circulate a liquid on the surface of a metal part intended for delamination.

Materials and Methods The same material and method conditions as in Example 1 were applied.

In addition, a liquid circulation system was applied in this method. The system consists of a motor and rotating blades immersed in a liquid chamber and positioned along the horizontal axis of the metal part.

Results: Efficiency of the method was assessed visually.

These results demonstrate that the presence of a liquid circulation system does not prevent the formation of bubbles of material on the surface of metal parts, thus leading to uneven delamination and mark formation. The tested method cannot ablate the base metal of the part.

To be able to avoid phenomena associated with the formation of bubbles of material on the surface of metal parts and thus to make available a method by which samples can be homogeneously decontaminated and ablated in the presence of water. , the applied method needs to be optimized.

Example 3 Implementation of the decontamination method for metal parts according to the present invention.

The purpose of this study was to determine the efficiency of a pulsed laser to decontaminate metal parts containing gas on the base metal in a liquid medium in the presence of a glass plate and a liquid circulation system. Ablation of the base metal of the component to a depth of at least 6 μm is taken to represent the depth of contamination of the metal component with tritium.

Materials and Methods Inox 304L metal plates containing no radioactive gases and with a small amount of paint were used for this test.

In this study, the metal parts were immersed in a chamber containing pure water as the liquid medium with a glass interface that was 5 mm thick and transparent at the laser wavelength of 1064 nm. A glass interface is placed at the surface of the liquid medium between the pulsed laser beam and the metal part. The metal parts are placed 25 mm below the surface of the water level.

The liquid circulation system comprises a motor and a nozzle submerged in the chamber and positioned between the interface and the part along an axis parallel to the part.

The pulsed laser used during this study emits a wavelength of 1064 nm, has a power of 100 W, a frequency of 100 KHz and a focal length of 140.3 mm. Multiple passes of the laser beam were tested over the same area of the part.

The ability of the method to prevent the formation of bubbles of material on the surface of metal parts and the formation of fumes on the surface of liquids was visually analyzed.

Morphological analysis of the surface by 3D optical measurements was performed in the same direction as the laser treatment and a profile width of 0.5 mm to define the step height between the reference surface and the exfoliated surface. The step height is the difference in surface height between the non-laser treated part and the laser treated part.

result

These results show that there appears to be a linear relationship between the number of passes and the height of material removed. Thirty passes of the laser beam over a metal part placed 25 mm below the surface of the liquid medium is sufficient to ablate the part to a depth of about 6 μm, and to a depth of about 10 μm. A case was found to be 50 passes.

Furthermore, no phenomena related to the formation of bubbles of material on the surface of the part were observed and no fume formation on the surface of the liquid was observed, thus the metal parts were effectively ablated and homogeneous.

It is therefore possible to decontaminate metal parts in a liquid medium using the pulsed laser decontamination method according to the invention.

Claims (10)

A method for decontaminating gas-containing metal parts by laser irradiation in a liquid medium, comprising:
the metal component is placed in the liquid medium;
a glass interface that is permeable to a pulsed laser beam wavelength is positioned in the liquid medium, the interface being positioned between the part and the beam at a distance of 10 mm to 250 mm from the metal part;
all or part of a liquid medium circulation system capable of directing the liquid medium disposed between the interface and the metal component is disposed in the liquid medium along the component;
A pulsed laser beam is applied to the metal part, emitting at a wavelength of 1,000 nm to 1,080 nm, a fluence of 30 J/cm ² to 200 J/cm ² , and a power peak of 1.2 kW to 7.5 kW; A method, wherein the beam is applied to the metal part at a travel speed of 3,000 mm/sec to 20,000 mm/sec. The wavelength is 1064 nm, the fluence is 50 J/cm ² to 150 J/cm ² , the power peak is 2 kW to 4 kW, and the moving speed is 3,000 mm/sec to 20,000 mm/sec. 1. The method according to 1. 3. A method according to claim 1 or 2, wherein the laser beam is applied to the part 10 to 150 times, preferably 30 to 100 times, at the same location. The liquid medium is water, the glass interface is placed in the water at a distance of 10 to 50 mm from the part, the wavelength is 1064 nm and the fluence is 100 J/cm ² to 150 J/cm. ² , said power peak is between 2 kW and 4 kW, and said laser beam is applied to said metal part 30 to 60 times at a moving speed of between 5,000 mm/sec and 10,000 mm/sec. 4. The method according to any one of 1 to 3. 3. The liquid circulation system comprises a motor and a nozzle, the nozzle being immersed in the liquid medium and arranged between the interface and the metal part along an axis parallel to the metal part. Item 5. The method according to any one of Items 1 to 4. 1. A device for decontaminating gas-containing metal parts with a laser in a liquid medium, comprising:
a chamber (3) containing a liquid medium in which the metal part is immersed;
A pulsed laser capable of emitting a pulsed laser beam at a wavelength of 1,000 nm to 1,080 nm, a fluence of 30 J/cm ² to 200 J/cm ² , and a power peak of 1.2 kW to 7.5 kW. a laser with an irradiation head (4);
a glass interface (5) capable of passing a pulsed laser beam wavelength and positioned between said metal part and said beam and immersed in said liquid medium (2);
A liquid medium circulation system (8), wholly or partly located between the part and the glass interface, between the interface (5) and the metal part (1) a liquid medium circulation system (8) capable of directing said liquid medium along said component disposed in said device. Said glass interface (5) is connected in a permanent or separable manner to said irradiation head (4) of said pulsed laser by means of a hook system (9) or to said laser irradiation head, preferably 7. The device of claim 6, wherein is incorporated into the front face of the head. 8. Device according to claim 6 or 7, wherein the irradiation head (4) is enclosed in a closed chamber (10). said circulation system (8) of said liquid medium comprising a motor (7) and a nozzle (6) immersed in said liquid medium (2) along an axis parallel to said metal part, Device according to any one of claims 6 to 8, arranged between said interface (5) and said metal part (1). a tube having one end in contact with the liquid medium and the other end in contact with a chamber for collecting the liquid; and a pump directly or indirectly connected to the tube and capable of aspirating the liquid. 10. A device according to any one of claims 6 to 9, comprising a liquid recovery system.

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