RU2756175C1 - Robotic laser complex and method of dismantling metal structures of npp - Google Patents

Abstract

FIELD: technological processes.SUBSTANCE: invention relates to removal of large-size metal structures of nuclear power plant units decommissioned and subject to recycling. Robotic laser system includes environmental protection means (9) configured to arrange closed air space (10), in which cutting object (5) is placed and the cutting products output into the environment is prevented. Complex comprises at least one laser module (1) with output of radiation to transport optical fibre (2), to distal end of which is connected output optical module (3) with focusing lens (4), arranged on robotic manipulator (11) with three-coordinate movement. At least one auxiliary robot manipulator (12) is introduced to move fragments (13) of the cutting object. Preferably, laser cutting is carried out in at least two modes differing with cutting width. At that, by means of gas-dynamic channel (17) high-speed jet of air (20) is formed, which is directed to zone of laser cutting at an angle to axis of focused laser beam (6).EFFECT: technical result is creation of high-efficiency environmentally safe technology of dismantling NPP power units.26 cl, 3 dwg

Description

FIELD OF TECHNOLOGY

The invention relates to the field of dismantling large-sized metal structures, namely, decommissioned nuclear power plant units, mainly by means of laser cutting. More specifically, the invention relates to the dismantling of pressurized water power reactors (VVER).

PRIOR ART

The urgency of the problem of remote cutting into fragments of nuclear reactor vessels and other thick-walled (from 60 mm and more) metal structures with a large surface area (about 100 m ² and more) is due to the growing need to decommission them after 30 years of operation. Water-cooled pressurized water-cooled power nuclear reactors are one of the most successful branches of the development of nuclear power plants that are widespread in the world. The common name for reactors of this type in other countries is PWR, they are the backbone of the world nuclear power. VVER - Russian representatives of this type of the most common reactors have a vessel diameter of 4.5 m and a height of about 10 m.

Fragmentation of radioactive metal structures of nuclear power plants by mechanical methods, known, for example, from patent RU 2687048, publ. 05/07/2019, Bul. No. 13, is ineffective due to the need for frequent change of equipment - cutting tools (diamond saws, circular and milling cutters, hydraulic shears, etc.) in hard-to-reach conditions of radiation exposure.

Traditional thermal methods, for example, gas cutting, plasma, electric spark cutting, etc., also have the disadvantage of high labor intensity, duration of equipment preparation and work.

Mobile laser systems, known, for example, from patent RU 2485287, publ. 06/20/2013 Bul. No. 17, have an optimally high power and allow laser cutting of metal structures at a large (up to 70 m) distance of the focusing lens from the cutting object. This makes these laser systems highly efficient means of eliminating accidents, for example, at oil and gas fields. However, they are not designed for highly efficient cutting of radioactive structures with ensuring environmental safety standards.

This drawback is partially devoid of the device and method for underwater laser cutting of radioactive long elements of a nuclear reactor, known from patent application JP 200315693, published 05/30/2003. However, the disadvantage of the solution disclosed in the invention is the impossibility of its application to dismantling a nuclear reactor vessel due to the impossibility of filling it with water due to leakage and the threat of a large volume of water turning into liquid radioactive waste.

The device and method for dismantling reactor equipment using laser cutting in a high-speed process gas stream coaxial with a laser beam, known from patent application JP 2001166090, published on June 22, 2001, are largely devoid of these drawbacks. High purity of the process gas is necessary because exceeding the permissible impurity value adversely affects the optics of the focusing lens of the output optical module. The specified method and device is intended for highly efficient cutting of in-reactor equipment having different thicknesses.

However, the optimal modes of laser cutting of the reactor vessels themselves and other large-sized objects have not been determined.

In addition, the specified method and device do not ensure the environmental safety of dismantling large metal structures of nuclear power plants. This is because laser cutting produces contaminants as an unwanted by-product, which include:

- slag adhering to the surface of the cut material, which is solid particles formed by the ejection of the molten material and its compounds formed during melting from the cut;

- precipitated slag, which does not stick to the surface of the cut material and falls under the action of gravity;

- aerosols or solid particles formed during the evaporation of a part of the material from the cut, and compounds formed during oxidation during the melting of the cut material, remaining in suspension in the surrounding gas environment due to the insignificant falling speed.

These contaminants, especially aerosols, are extremely harmful, since they are radioactive and can penetrate into the environment.

Another disadvantage is the need for a high flow rate (~ 1000 l / min or more) of clean process gas for its injection into the cutting zone coaxially with the laser beam, which can be burdensome for cutting large-sized metal structures of nuclear power plants.

SUMMARY OF THE INVENTION

The technical problem and technical result of the invention is the creation of a highly efficient technology for dismantling NPP power units by laser cutting, ensuring the safety of work and reliable protection of the environment from radioactive contamination.

Achievement of these goals is possible with the help of the method of dismantling the metal structures of the nuclear power plant, including the fragmentation of the cutting object with a focused laser beam and the movement of the cut fragments from the laser cutting zone. The difference between the method is that the transport optical fiber is used to transmit laser radiation from a remote laser module to an output optical module (PTO) with a focusing lens, a focused laser beam is used to cut out a fragment of the cutting object when the PTO is moved by a robotic manipulator with three-coordinate movement; at least one auxiliary robotic manipulator with three-dimensional movement removes a fragment of the cutting object, and using environmental protection means, made with the function of organizing a closed air space around the cutting object, purify the air released into the environment from contaminating cutting products.

Preferably, the cutting object is fragmented, which belongs to the largest metal structures of the nuclear power plant, including the power units and steam generators of the nuclear power plant.

In embodiments of the invention, a pure gas jet is formed directed to the laser cutting zone coaxially with the focused laser beam.

Preferably, a high-speed air jet is formed directed into the laser cutting zone at an angle to the axis of the laser beam.

Preferably, objects with a wall thickness varying from 50 to 400 mm are cut.

Depending on the wall thickness of the object, laser cutting can be performed in at least two different modes, differing in the cutting width.

In another aspect, the invention relates to a device that includes: at least one laser module with outputting laser radiation into a transport optical fiber, to the distal end of which an output optical module with a focusing lens is connected, intended for fragmentation of the cutting object with a focused laser beam.

The difference between the device lies in the fact that the output optical module is placed on a robotic manipulator with three-dimensional movement and is made with the function of cutting the largest metal structures of nuclear power plants, including power units and steam generators of nuclear power plants, at least one auxiliary robotic manipulator with three-coordinate movement, made with the function moving the fragments of the cutting object, and introduced environmental protection means, made with the function of organizing a closed air space, in which the large-sized metal structure of the nuclear power plant is located and the release of cutting products into the environment is prevented.

Preferably, said environmental protection includes a purification ventilation system equipped with replaceable air filters for trapping radioactive aerosols and volatile laser cut products.

Preferably, the purification ventilation system is equipped with replaceable air filters for trapping radioactive aerosols and volatile laser cutting products.

Preferably, a system is introduced for transporting the fragments of the power unit outside the enclosed space.

Preferably, the device is made with the function of dismantling the NPP metal structures, the surface area of which is not less than 100 m ² .

The device can be made with the function of dismantling the NPP metal structures, in which the surface area of the cut fragments does not exceed 0.1 m ² .

In embodiments of the invention, the device is made with the function of cutting the metal structures of nuclear power plants having different thicknesses in the range from 50 to 400 mm.

Preferably, the laser module comprises an Iterbium fiber laser with a wavelength of 1.06-1.8 μm and an output power of more than 20 kW. These lasers have a record efficiency of conversion of electrical energy into optical energy up to 50%, the ability to transmit radiation over long distances via optical fiber, and the highest reliability.

In preferred embodiments of the invention, the device is made with a cutting function characterized by a power density of the laser beam at the focus of more than 1.5⋅10 ⁵ W / cm ² and a focal spot size of no more than 5 mm.

In embodiments of the invention, the device is made with a cutting function characterized by a power density of the laser beam in focus from n⋅10 ³ to n⋅10 ⁴ W / cm ² ,

where n = 2-4, and the focal spot size is more than 5 mm.

In embodiments of the invention, the focusing lens of the output optical module is made with a variable focal length.

In embodiments of the invention, a pure gas supply system is introduced coaxially with a focused laser beam.

Preferably, the pure gas belongs to the group of gases including: air, nitrogen, inert gases, oxygen, carbon dioxide.

In embodiments of the invention, a gas-dynamic path is introduced containing a compressor and a nozzle for forming a high-speed air jet directed to the laser cutting zone.

In embodiments of the invention, at least part of the air intake into the cleaning ventilation system is performed by an air intake located on the robotic manipulator, installed in the path of a high-speed air jet leaving the laser cutting zone.

In embodiments of the invention, a cassette system for changing optical filters is introduced, designed to protect the focusing lens from contamination.

In embodiments of the invention, the laser complex contains two or more laser modules.

In embodiments of the invention, the device is made with the possibility of cutting from the inside out and / or from the outside to the inside.

In embodiments of the invention, auxiliary robotic arms are located both outside and inside the cutting object.

In embodiments of the invention, robotic arms are attached to one or more mobile devices.

When performing the method and device for dismantling the NPP metal structures in the proposed form, the following are achieved:

- remote cutting of thick-walled (up to 400 mm) metal structures;

- minimization of radiation pollution of the ambient air by aerosols,

accompanying laser cutting of metal structures;

- protection of the optics of the output optical module from spatter emanating from the cut zone

heated metal;

- complete elimination of the dose load on the service personnel

- elimination of the burdensome need for high flow rates (~ 1000 l / min and

more) clean process gas for its injection into the cut zone coaxially with the laser beam.

These advantages are realized through the following solutions:

- robotization, remote control and management,

- organization of a closed air space around a large-sized cutting object with the use of a cleaning ventilation system that captures aerosols coming from the cutting zone;

- removal of the metal melt from the cutting zone when cutting thick-walled structures, stimulated by an increase in the power density of the laser beam to 1.5⋅10 ⁵ W / cm ² and more, which causes the melt to boil and be carried away by the vapor recoil pressure,

- providing in preferred embodiments of the invention a process gas flow with an optimally high flow rate (~ 1000 l / min and more) due to the use of a powerful compressor that creates a high-speed jet of compressed air directed at a certain angle ~ 60 ° to the laser beam axis. This ensures fragmentation of thick cut objects, as well as carry-over of contaminated products from the PTO shaft. Additionally, a cassette system of replaceable optical filters can be used to protect the PTO focusing lens from dirt.

The foregoing and other objects, advantages and features of the present invention will become clearer from the following non-limiting description of illustrative embodiments thereof, given by way of example only with reference to the accompanying drawings.

Since the device for dismantling the metal structures of nuclear power plants, made in accordance with the present invention, is a robotic laser complex, further in the description the designation of the device as a complex is used.

BRIEF DESCRIPTION OF DRAWINGS

The essence of the invention is illustrated by drawings, in which:

FIG. 1, Fig. 2 is a schematic view of a robotic laser complex for dismantling large-sized metal structures of nuclear power plants in accordance with embodiments of the invention,

FIG. 3 is a schematic representation of a part of a robotic laser complex near the cutting zone.

References in FIGS. 1 to 3 indicate the following:

1 - laser module;

2 - transport fiber;

3 - optical output module (PTO);

4 - focusing lens;

5 - cutting object;

6 - focused laser beam;

7 - cleaning ventilation system;

8 - control and monitoring system;

9 - environmental protection means;

10 - closed air space;

11 - robotic manipulator;

12 - auxiliary robotic manipulator;

13 - cut fragments of the cutting object;

14 - replaceable air filters;

15 - system for transporting fragments;

16 - pure gas supply system;

17 - gas-dynamic path;

18 - compressor;

19 - nozzle;

20 - high-speed air jet;

21 - laser cutting area;

22 - robotic arm;

23 - air intake;

24 - optical filters;

25 - cassette system for changing optical filters;

26 - mobile device of a robotic arm.

MODES FOR CARRYING OUT THE INVENTION

The following is an embodiment of the invention, which is a non-exhaustive example of the claimed invention and cannot limit the scope of the invention.

The robotic laser complex, a variant of which is shown in Fig. 1, has at least one laser module 1 with the output of laser radiation into the transport optical fiber 2, to the distal end of which an output optical module 3 with a focusing lens 4 is connected, which performs fragmentation of the cutting object 5 by a focused laser beam 6. The processes of the laser complex are controlled by the control and monitoring system 8.

The object of cutting 5 is preferably large-sized metal structures of nuclear power plants decommissioned from operation, including power units (Fig. 1) and steam generators

The advantage of the claimed laser complex is that it is equipped with environmental protection means 9, which are made with the function of organizing a closed air space 10, in which a large-sized cutting object 5 is located and the release of cutting products into the environment is prevented. FIG. 1 shows a variant of using for this purpose a dome over a mine, in which the cutting object is located - the body of the NPP power unit.

Environmental protection means 9 include a purification ventilation system 7 equipped with replaceable air filters 14 for trapping radioactive aerosols and volatile laser cutting products.

To ensure the safety of work, the output optical module 3 is placed on a robotic manipulator 11 with three-dimensional movement, which ensures the cutting of metal structures according to a given program in an automated mode.

To separate and move fragments 13 of cutting objects, at least one auxiliary robotic manipulator 12 with three-dimensional movement is introduced.

To remove the separated fragments 13, a system has been introduced for transporting 15 fragments of the cutting object outside the closed air space 10. When cutting the bodies of NPP power units, the technological channels of the reactor can be used to transport the fragments. The transportation system can be equipped with simplified analogs of atmospheric locks that prevent radioactive aerosols from escaping to the outside.

Typical operating modes of the complex: the surface area of the cutting object is not less than 100 m ² , the thickness of the cutting object is in the range from 50 to 400 mm. In the case when the object of cutting is a VVER-1000 reactor vessel, its height is about 10 m, its diameter is about 4.5 m. In this case, the vessel is placed in the reactor shaft with a depth of about 20 m.

In embodiments of the invention, the surface area of the cut fragment does not exceed 0.1 m ² . This condition may be associated with the transportation of fragments 13 through the technological channels of the reactor, which has a limited flow area.

The provision of optimal power of the output optical module is achieved through the use of a ytterbium fiber laser with a wavelength of 1.06-1.8 μm, in which the output power of the laser module is not less than 16 kW.

To optimize the process of laser cutting and protect the PTO optics from the volatile fraction of the cutting products, a system 16 for supplying pure gas coaxially with a focused laser beam 6 can be introduced into the complex.

FIG. 2 schematically shows an embodiment of a robotic laser complex, in which a cover is used to organize a closed air space 10, which is installed above the room, in particular, above the reactor shaft, in which the cutting object 5 is located.

The pure gas supply system 16 may contain a cylinder with a gas pressure reducer and a flexible hose laid to the cutting site together with a transport optical fiber 2 and a flexible cable of the control and monitoring system.

Pure gas belongs to the group of gases, including: air, nitrogen, inert gases, oxygen, carbon dioxide.

The cutting mode is mainly used, characterized by a power density of the laser beam in the focus above 1.5⋅10 ⁵ W / cm ² and a focal spot size of no more than 5 mm. In this mode, boiling of the melt is achieved and its removal is stimulated by the vapor recoil pressure. The focus of the laser beam is preferably about ½ the thickness of the object to be cut.

For the thickest walls of the cutting object, reaching 400 mm, the cutting mode is used with a laser beam power density at the focus n⋅10 ³ to n⋅10 ⁴ W / cm ² , where n = 2 ÷ 4, and the focal spot size is not less than 5 mm. In this mode, metal removal from the cut zone is stimulated by the fact that the gravity forces of the molten metal exceed the surface tension forces.

An increase in the width of the cut ensures that the gas jet blowing out the melt reaches the far wall of the cut without a significant loss of pressure. However, the required gas flow rates become very large, over 1000 l / min, and expensive if pure gas is used.

In this regard, in order to reduce operating costs in preferred embodiments of the invention, the complex is equipped with a gas-dynamic path containing a compressor 18 and a nozzle 19 attached to the robotic arm 11 to form a high-speed air jet 20 directed to the laser cutting zone 21.

Air intake into the purification ventilation system, namely into one of the channels of the purification ventilation system 7 with replaceable air filters 14, is carried out by an air intake 23 located on the manipulator 22, installed on the way out of the cutting zone 21 of polluting products, which include aerosols and non-sticking slags.

FIG. 3 schematically shows a part of a robotic laser complex near the cutting zone. In the embodiment shown in FIG. 3, the compressor 18 is fixed on the same support as the robotic arm 11. The air is supplied to the compressor from a clean environment using a corrugated hose, the length of which from the point of intake to the point of cutting can exceed 20 m. In this case, the maximum pressure of the high-speed air jet is provided. 20, which, when interacting with the cutting area, branches into two jets 20a and 20b, which facilitate the cutting process and the removal of contaminants from the cutting area. In this case, the jet 20b helps to protect the optics of the focusing lens, deflecting contaminants directed towards it from the laser cutting zone.

In embodiments of the invention, in order to improve reliability and ensure uninterrupted operation of the complex, a cassette system 25 for changing optical filters 24, designed for additional protection of the focusing lens 4 from contamination, is introduced into it, FIG. 3.

In embodiments of the invention, a PTO focusing lens with a variable focal length is used for various cutting modes, which makes it possible to perform laser cutting in various modes.

In other embodiments of the invention, the complex can be used using at least two laser modules that are designed for at least two different cutting modes.

Output optical modules (PTO) can be used for cutting from the inside out, in particular, when cutting the bodies of NPP power units, Fig. 1, Fig. 2.

In other embodiments of the invention, the PTO can be used for cutting from outside to inside, for example, for cutting objects 5 such as steam generators.

Auxiliary robotic arms 12 can be positioned both outside and inside the cutting object.

FIG. 2 depicts the attachment of robotic arms, preferably to one or more mobile devices 26, which may have suspension supports. When this mobile device 26 can move linearly in two coordinates, or be rotary.

The method of dismantling NPP structures using a robotic laser complex is as follows. The output optical module 3 is moved to the laser cutting zone by a robotic manipulator 11 with three-dimensional movement. With the help of the transport fiber 2, the laser radiation is transported to the output optical module 3. With the help of the focusing lens 4, the laser beam 6 is focused so that the focusing area of the laser beam is preferably located at about 1/2 of the thickness of the cutting object, by the robotic manipulator 11, using the control and monitoring system 8 cutting out a fragment 13 is carried out according to a given program, the subsequent removal of the fragment by at least one auxiliary controlled robotic manipulator 12 with three-dimensional movement, while the air coming out to the surface is cleaned by means of environmental protection 9, 7, 14 with the function of organizing a closed air space 10 around the object to be cut 5.

In embodiments of the invention, a high-speed jet of pure gas is formed using the pure gas supply system 6, 16 directed to the laser cutting zone coaxially with the focused laser beam.

In preferred embodiments, using the gas-dynamic path 17, a high-speed air jet 20 is formed, directed into the laser cutting zone at an angle to the axis of the focused laser beam 6.

Depending on the wall thickness of the object, laser cutting is performed in at least two different modes, differing in the cutting width.

INDUSTRIAL APPLICABILITY

The invention is intended for use in dismantling large-sized metal structures of nuclear power plant units that are being decommissioned and subject to disposal.

Claims (26)

1. A method for dismantling metal structures of nuclear power plants (NPP), including fragmentation of the cutting object with a focused laser beam and moving the cut fragments from the cutting zone, characterized in that the transport optical fiber is used to transmit laser radiation from a remote laser module to an output optical module with a focusing lens; the output optical module is moved by a robotic manipulator with three-dimensional movement and a focused laser beam; fragmentation of the cutting object is performed, at least one auxiliary robotic manipulator with three-coordinate movement is removed a fragment of the cutting object, and by means of environmental protection means made with the function of organizing a closed air space around of the cutting object, purify the air released into the environment from polluting cutting products. 2. The method of dismantling according to claim 1, characterized in that the cutting object is fragmented, which belongs to the largest metal structures of the nuclear power plant, including the power units and steam generators of the nuclear power plant. 3. The method of dismantling according to any one of paragraphs. 1 or 2, characterized in that they form a high-speed jet of pure gas directed to the laser cutting zone coaxially with the focused laser beam. 4. A method of dismantling according to any of the preceding claims, characterized in that a high-speed air jet is formed directed into the laser cutting zone at an angle to the axis of the focused laser beam. 5. Dismantling method according to any of the preceding claims, characterized in that objects with a wall thickness varying from 50 to 400 mm are cut. 6. A method of dismantling according to any of the preceding claims, characterized in that, depending on the wall thickness of the object, laser cutting is performed in at least two different modes, differing in the cutting width. 7. Device for implementing the method of dismantling metal structures of nuclear power plants according to any one of paragraphs. 1-6, containing at least one laser module (1) with the output of laser radiation into the transport optical fiber (2), to the distal end of which an output optical module (3) with a focusing lens (4) is connected, intended for fragmentation of the cutting object (5) a focused laser beam (6), characterized in that the output optical module (3) is placed on a robotic manipulator (11) with three-dimensional movement and is made with the function of cutting the largest metal structures of nuclear power plants, including power units and steam generators of nuclear power plants, introduced at least at least one auxiliary robotic manipulator (12) with three-dimensional movement, made with the function of moving fragments (13) of the cutting object (5), and introduced means (9) for environmental protection, made with the function of organizing a closed air space (10), in which a large-sized metal structure of the NPP was placed and the release of cutting products into the environment was prevented. 8. The device according to claim. 7, in which the means (9) of environmental protection include a cleaning ventilation system (7) equipped with replaceable air filters (14) for trapping radioactive aerosols and volatile laser cutting products. 9. Device according to any one of paragraphs. 7 or 8, in which a system of transportation (15) of cutting fragments outside the confined space is introduced. 10. Device according to any one of paragraphs. 7-9 with the function of dismantling the NPP metal structures, the surface area of which is not less than 100 m ² . 11. Device according to any one of paragraphs. 7-10 with the function of dismantling the NPP metal structures, in which the surface area of the cut fragments does not exceed 0.1 m ² . 12. Device according to any one of paragraphs. 7-11 with the function of cutting NPP metal structures with various thicknesses ranging from 50 to 400 mm. 13. Device according to any one of paragraphs. 7-12, in which the laser module contains a ytterbium fiber laser with a wavelength of 1.06-1.8 μm. 14. Device according to any one of paragraphs. 7-13, in which the output power of the laser module is more than 20 kW. 15. Device according to any one of paragraphs. 7-14 with the cutting function at a laser beam power density in the focus above 1.5⋅10 ⁵ W / cm ² and a focal spot size of no more than 5 mm. 16. Device according to any one of paragraphs. 7-15 with the cutting function at a laser beam power density in the focus from n⋅10 ³ to n⋅10 ⁴ W / cm ² , where n = 2 ÷ 4, and a focal spot size of more than 5 mm. 17. Device according to any one of paragraphs. 7-16, in which the focusing lens of the output optical module is made with a variable focal length. 18. Device according to any one of paragraphs. 7-17, in which a system (16) of pure gas supply is introduced coaxially with a focused laser beam (6). 19. The device according to claim. 18, in which the pure gas belongs to the group of gases, including: air, nitrogen, inert gases, oxygen, carbon dioxide. 20. Device according to any one of paragraphs. 7-19, in which a gas-dynamic path (17) is introduced, containing a compressor (18) and a nozzle (19) for the formation of a high-speed air jet (20a) directed to the laser cutting zone (21). 21. A device according to claim 20, in which at least part of the air intake into the cleaning ventilation system is performed by an air intake (23) placed on the robotic arm (22), installed in the path of a high-speed air jet (20b) leaving the cutting zone. 22. Device according to any one of paragraphs. 7-21, in which a cassette system (24) for changing optical filters (25) is introduced, designed to protect the focusing lens (4) from contamination. 23. Device according to any one of paragraphs. 7-22 with two or more laser modules. 24. Device according to any one of paragraphs. 7-23 with the possibility of cutting from the inside - out and / or outside - in. 25. Device according to any one of paragraphs. 7-24, in which auxiliary robotic arms are located both outside and inside the cutting object. 26. Device according to any one of paragraphs. 7-25, in which robotic arms are attached to one or more mobile devices (26).

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