High temperature chemical decontamination system and method

Abstract

The application discloses a high-temperature chemical decontamination system and method, wherein a first electromagnetic heating coil is arranged in a small equipment reaction kettle, a second electromagnetic heating coil is arranged in a large equipment reaction kettle, and a third electromagnetic heating coil is arranged in a long strip equipment reaction kettle; the outlet of the small equipment reaction kettle, the outlet of the large equipment reaction kettle and the outlet of the long strip equipment reaction kettle are connected with the tube side inlet of a heat exchanger, the tube side outlet of the heat exchanger is connected with the inlet of an activated carbon adsorber through a high-efficiency particle filter, the outlet of the activated carbon adsorber is divided into two paths, one of which is connected with a carbon monoxide combustor through an exhaust valve, and the other is connected with the inlet of a fan through a recirculation valve, the outlet of the fan is connected with the shell side inlet of the heat exchanger, and the shell side outlet of the heat exchanger is connected with the inlet of the small equipment reaction kettle, the inlet of the large equipment reaction kettle and the inlet of the long strip equipment reaction kettle, so that radioactive pollution can be avoided.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of graphite dust decontamination of high temperature gas cooled reactor, and relates to a high temperature chemical decontamination system and method. BACKGROUND

[0002] The high temperature gas cooled reactor has the characteristics of large core thermal capacity and good inherent safety, and is one of the reactor types with the characteristics of the fourth generation nuclear reactor. The core structure of the high temperature gas cooled reactor adopts nuclear carbon bricks as the shielding layer and nuclear reflector material, and the fuel element adopts a spherical coated particle fuel. Graphite is also the main component of the fuel sphere. The fuel sphere circulates in the core and is affected by multiple factors such as neutron irradiation, gravity extrusion and friction, and a certain amount of graphite dust is generated. Due to the effects of fission products and neutron activation, the graphite dust carries a large amount of radionuclides. These radioactive graphite dusts circulate with helium and deposit on the pipes, equipment and components connected to the primary loop, causing radioactive contamination.

[0003] At present, the main decontamination methods all adopt liquid decontamination methods, which use chemical corrosion stripping to remove radioactive substances adhered to the surface of equipment components. For example, the invention disclosed in CN202111049941.0 uses an acidic solution to decontaminate equipment components and removes radioactive substances by water rinsing. This process generates a large amount of radioactive wastewater that needs to be treated, increasing the cost of radioactive treatment. The invention disclosed in CN202210951227.9 uses an oxidizing decontamination gel to decontaminate radioactive contaminated metals. After the decontamination gel strips the radionuclides, the equipment components do not need to be washed with water, but the radionuclides carried by the dried gel still need to be treated. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art and provide a high temperature chemical decontamination system and method that can avoid radioactive contamination.

[0005] To achieve the above purpose, the high temperature chemical decontamination system according to the present application comprises a small equipment reaction kettle, a large equipment reaction kettle, a long strip type equipment reaction kettle, a heat exchanger, a high efficiency particle filter, an activated carbon adsorber, an exhaust valve, a carbon monoxide burner, a recirculation valve and a fan.

[0006] The first electromagnetic heating coil is arranged in the small equipment reaction kettle, the second electromagnetic heating coil is arranged in the large equipment reaction kettle, and the third electromagnetic heating coil is arranged in the long strip type equipment reaction kettle. The first electromagnetic heating coil, the second electromagnetic heating coil and the third electromagnetic heating coil are connected with an alternating current power supply.

[0007] The outlet of the small equipment reaction kettle, the outlet of the large equipment reaction kettle and the outlet of the long strip type equipment reaction kettle are connected with the tube side inlet of the heat exchanger, the tube side outlet of the heat exchanger is connected with the inlet of the active carbon adsorber through the high-efficiency particle filter, the outlet of the active carbon adsorber is divided into two ways, one way is connected with the carbon monoxide burner through the exhaust valve, the other way is connected with the inlet of the fan through the recirculation valve, the outlet of the fan is connected with the shell side inlet of the heat exchanger, and the shell side outlet of the heat exchanger is connected with the inlet of the small equipment reaction kettle, the inlet of the large equipment reaction kettle and the inlet of the long strip type equipment reaction kettle.

[0008] The carbon dioxide supply pipeline is connected with the inlet of the fan, and a carbon dioxide supply valve is arranged on the carbon dioxide supply pipeline.

[0009] A radiation detection instrument is arranged on the pipeline between the active carbon adsorber and the recirculation valve.

[0010] A first reaction kettle inlet valve is arranged at the shell side inlet of the small equipment reaction kettle, and a first reaction kettle outlet valve is arranged at the shell side outlet of the small equipment reaction kettle.

[0011] A second reaction kettle inlet valve is arranged at the shell side inlet of the large equipment reaction kettle, and a second reaction kettle outlet valve is arranged at the shell side outlet of the large equipment reaction kettle.

[0012] A third reaction kettle inlet valve is arranged at the shell side inlet of the long strip type equipment reaction kettle, and a third reaction kettle outlet valve is arranged at the shell side outlet of the long strip type equipment reaction kettle.

[0013] A first reaction kettle cover plate is arranged at the top opening of the small equipment reaction kettle.

[0014] A second reaction kettle cover plate is arranged at the top opening of the large equipment reaction kettle.

[0015] A third reaction kettle cover plate is arranged at the top opening of the long strip type equipment reaction kettle.

[0016] The high-temperature chemical decontamination method provided by the application comprises the following steps:

[0017] 1) carbon dioxide is introduced into the reaction kettle to purge and replace the air in the reaction kettle, and when the carbon dioxide content in the reaction kettle exceeds a preset content, step 2) is performed;

[0018] 2) the decontaminated equipment is placed in the reaction kettle, the inside of the reaction kettle is heated by the electromagnetic heating coil in the reaction kettle, so that the decontaminated equipment is heated to a preset temperature;

[0019] 3) carbon dioxide is introduced into the reactor, so that the graphite dust on the decontamination equipment reacts with the carbon dioxide to form carbon monoxide gas, the radioactive particles and radionuclides on the decontamination equipment are discharged to the outside of the reactor with the formed carbon monoxide gas, and then filtered and adsorbed by the high-efficiency particle filter and the activated carbon adsorber, and the filtered and adsorbed carbon monoxide is burned by the carbon monoxide burner and then discharged into the atmosphere.

[0020] The present application has the following beneficial effects:

[0021] The high-temperature chemical decontamination system and method of the present application have the following beneficial effects: BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The present application has the following beneficial effects:

[0023] Among them, 1 is an alternating current power supply, 2 is a small equipment reactor, 3 is a large equipment reactor, 4 is a long strip equipment reactor, 2-1 is a first reactor inlet valve, 3-1 is a second reactor inlet valve, 4-1 is a third reactor inlet valve, 2-2 is a first reactor outlet valve, 3-2 is a second reactor outlet valve, 4-2 is a third reactor outlet valve, 2-3 is a first electromagnetic heating coil, 3-3 is a second electromagnetic heating coil, 4-3 is a third electromagnetic heating coil, 2-4 is a first reactor cover plate, 3-4 is a second reactor cover plate, 4-4 is a third reactor cover plate, 5 is a heat exchanger, 6 is a high-efficiency particle filter, 7 is an activated carbon adsorber, 8 is an exhaust valve, 9 is a carbon monoxide burner, 10 is a radiation detection instrument, 11 is a recirculation valve, 12 is a fan, and 13 is a carbon dioxide supply valve. DETAILED DESCRIPTION

[0024] In order to make the person skilled in the art better understand the technical scheme of the present application, the technical scheme in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments, and are not intended to limit the scope of the present application. In addition, in the following description, the description of the known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0025] The structural schematic diagram according to the disclosed embodiments of the present application is shown in the drawings. These drawings are not drawn to scale, in which some details are enlarged for the purpose of clear expression, and some details can be omitted. The shapes of various regions, layers and their relative size and positional relationship shown in the drawings are only exemplary, and in actuality, there can be deviations due to manufacturing tolerances or technical limitations, and the regions / layers with different shapes, sizes and relative positions can be additionally designed by those skilled in the art according to actual needs.

[0026] Reference Figure 1 The high-temperature chemical decontamination system described in the present application includes an alternating current power supply 1, a small equipment reaction kettle 2, a large equipment reaction kettle 3, a long strip type equipment reaction kettle 4, a first reaction kettle inlet valve 2-1, a second reaction kettle inlet valve 3-1, a third reaction kettle inlet valve 4-1, a first reaction kettle outlet valve 2-2, a second reaction kettle outlet valve 3-2, a third reaction kettle outlet valve 4-2, a first electromagnetic heating coil 2-3, a second electromagnetic heating coil 3-3, a third electromagnetic heating coil 4-3, a first reaction kettle cover plate 2-4, a second reaction kettle cover plate 3-4, a third reaction kettle cover plate 4-4, a heat exchanger 5, a high-efficiency particle filter 6, an activated carbon adsorber 7, an exhaust valve 8, a carbon monoxide burner 9, a radiation detection instrument 10, a recirculation valve 11, a fan 12 and a carbon dioxide supply valve 13.

[0027] The first reaction kettle cover plate 2-4 is arranged at the top opening of the small equipment reaction kettle 2, the second reaction kettle cover plate 3-4 is arranged at the top opening of the large equipment reaction kettle 3, and the third reaction kettle cover plate 4-4 is arranged at the top opening of the long strip type equipment reaction kettle 4.

[0028] The first electromagnetic heating coil 2-3 is arranged in the small equipment reaction kettle 2, the second electromagnetic heating coil 3-3 is arranged in the large equipment reaction kettle 3, and the third electromagnetic heating coil 4-3 is arranged in the long strip type equipment reaction kettle 4. The first electromagnetic heating coil 2-3, the second electromagnetic heating coil 3-3 and the third electromagnetic heating coil 4-3 are all connected with the alternating current power supply 1.

[0029] The outlet of the small equipment reaction kettle 2, the outlet of the large equipment reaction kettle 3 and the outlet of the long strip type equipment reaction kettle 4 are communicated with the tube side inlet of the heat exchanger 5, the tube side outlet of the heat exchanger 5 is communicated with the inlet of the activated carbon adsorber 7 through the high-efficiency particle filter 6, the outlet of the activated carbon adsorber 7 is divided into two ways, one way is communicated with the carbon monoxide combustor 9 through the exhaust valve 8, the other way is communicated with the inlet of the fan 12 through the recirculation valve 11, the outlet of the fan 12 is communicated with the shell side inlet of the heat exchanger 5, the shell side outlet of the heat exchanger 5 is communicated with the inlet of the small equipment reaction kettle 2, the inlet of the large equipment reaction kettle 3 and the inlet of the long strip type equipment reaction kettle 4, the carbon dioxide supply pipeline is communicated with the inlet of the fan 12, and the carbon dioxide supply valve 13 is arranged on the carbon dioxide supply pipeline.

[0030] The first reaction kettle inlet valve 2-1 is arranged at the shell side inlet of the small equipment reaction kettle 2, the first reaction kettle outlet valve 2-2 is arranged at the shell side outlet of the small equipment reaction kettle 2, the second reaction kettle inlet valve 3-1 is arranged at the shell side inlet of the large equipment reaction kettle 3, the second reaction kettle outlet valve 3-2 is arranged at the shell side outlet of the large equipment reaction kettle 3, the third reaction kettle inlet valve 4-1 is arranged at the shell side inlet of the long strip type equipment reaction kettle 4, and the third reaction kettle outlet valve 4-2 is arranged at the shell side outlet of the long strip type equipment reaction kettle 4.

[0031] The radiation detection instrument 10 is arranged on the pipeline between the activated carbon adsorber 7 and the recirculation valve 11.

[0032] The high-temperature chemical decontamination method comprises the following steps:

[0033] 1) Before decontaminating the equipment, the suitable reaction kettle is selected according to the shape of the equipment, that is, the small equipment reaction kettle 2, the large equipment reaction kettle 3 or the long strip type equipment reaction kettle 4, and the valves at the inlet and outlet of the selected reaction kettle are opened;

[0034] 2) Carbon dioxide is introduced into the selected reaction kettle through the carbon dioxide supply valve 13, air is purged and replaced, and when the carbon dioxide content exceeds 80%, the exhaust valve 8 is closed;

[0035] 3) The reaction kettle cover plate of the selected reaction kettle is opened, and then the equipment to be decontaminated is put in;

[0036] 4) After the equipment to be decontaminated is put in, the reaction kettle cover plate of the selected reaction kettle is closed, the electromagnetic heating coil in the selected reaction kettle is powered by the alternating power supply 1, and the equipment to be decontaminated is heated to a certain temperature;

[0037] 5) open the recirculation valve 11, start the fan 12 to circulate the carbon dioxide gas, and when the carbon dioxide and graphite dust high-temperature reaction is completed to form carbon monoxide gas, the carbon dioxide can be supplemented according to the need through the carbon dioxide supply valve 13, and the supplemented carbon dioxide is preheated through the heat exchanger 5 and then enters the reaction kettle;

[0038] 6) when the carbon dioxide and graphite dust high-temperature reaction is completed to form carbon monoxide, and the radioactive particles or radionuclides are filtered and adsorbed by the high-efficiency particle filter 6 and the activated carbon adsorber 7 respectively. When the data measured by the radiation detection instrument 10 shows no radioactivity, open the exhaust valve 8 to discharge the carbon monoxide to the carbon monoxide combustor 9, and after the carbon monoxide is combusted, the products formed are finally discharged to the atmosphere. At this time, the carbon dioxide supply valve 13 is opened to continuously supply carbon dioxide to the selected reaction kettle, and the selected reaction kettle and the decontamination equipment are cooled.

[0039] Among them, when the filter core processing performance of the high-efficiency particle filter 6 and the activated carbon adsorber 7 is saturated, the nuclear power plant solid radioactive waste is compressed and packaged for processing.

[0040] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it, although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that: the specific embodiments of the present application can still be modified or replaced by the equivalent, without departing from the spirit and scope of the present application, any modification or equivalent replacement, which should be covered in the protection scope of the claims of the present application.

Claims

1. A high temperature chemical decontamination system characterized by, The device comprises a small equipment reaction kettle (2), a large equipment reaction kettle (3), a long strip type equipment reaction kettle (4), a heat exchanger (5), a high efficiency particle filter (6), an activated carbon adsorber (7), an exhaust valve (8), a carbon monoxide burner (9), a recirculation valve (11) and a fan (12); The first electromagnetic heating coil (2-3) is arranged in the small equipment reaction kettle (2), the second electromagnetic heating coil (3-3) is arranged in the large equipment reaction kettle (3), and the third electromagnetic heating coil (4-3) is arranged in the long strip type equipment reaction kettle (4). The first electromagnetic heating coil (2-3), the second electromagnetic heating coil (3-3) and the third electromagnetic heating coil (4-3) are connected with the alternating current power supply (1). The outlet of the small equipment reaction kettle (2), the outlet of the large equipment reaction kettle (3) and the outlet of the long strip type equipment reaction kettle (4) are connected with the tube side inlet of the heat exchanger (5). The tube side outlet of the heat exchanger (5) is connected with the inlet of the activated carbon adsorber (7) through the high efficiency particle filter (6). The outlet of the activated carbon adsorber (7) is divided into two paths. One path is connected with the carbon monoxide burner (9) through the exhaust valve (8), and the other path is connected with the inlet of the fan (12) through the recirculation valve (11). The outlet of the fan (12) is connected with the shell side inlet of the heat exchanger (5). The shell side outlet of the heat exchanger (5) is connected with the inlet of the small equipment reaction kettle (2), the inlet of the large equipment reaction kettle (3) and the inlet of the long strip type equipment reaction kettle (4). The carbon dioxide supply pipeline is connected with the inlet of the fan (12), and the carbon dioxide supply valve (13) is arranged on the carbon dioxide supply pipeline.

2. The high temperature chemical decontamination system of claim 1, wherein, The radiation detection instrument (10) is arranged on the pipeline between the activated carbon adsorber (7) and the recirculation valve (11).

3. The high temperature chemical decontamination system of claim 1, wherein, The first reaction kettle inlet valve (2-1) is arranged at the shell side inlet of the small equipment reaction kettle (2), and the first reaction kettle outlet valve (2-2) is arranged at the shell side outlet of the small equipment reaction kettle (2).

4. The high temperature chemical decontamination system of claim 1, wherein, The second reaction kettle inlet valve (3-1) is arranged at the shell side inlet of the large equipment reaction kettle (3), and the second reaction kettle outlet valve (3-2) is arranged at the shell side outlet of the large equipment reaction kettle (3).

5. The high temperature chemical decontamination system of claim 1, wherein, The third reaction kettle inlet valve (4-1) is arranged at the shell side inlet of the long strip type equipment reaction kettle (4), and the third reaction kettle outlet valve (4-2) is arranged at the shell side outlet of the long strip type equipment reaction kettle (4).

6. The high temperature chemical decontamination system of claim 1, wherein, The first reaction kettle cover plate (2-4) is arranged at the top opening of the small equipment reaction kettle (2).

7. The high temperature chemical decontamination system of claim 1, wherein, The second reaction kettle cover plate (3-4) is arranged at the top opening of the large equipment reaction kettle (3).

8. The high temperature chemical decontamination system of claim 1, wherein, The third reaction kettle cover plate (4-4) is arranged at the top opening of the long strip type equipment reaction kettle (4).

9. A high temperature chemical decontamination process characterized by, The device comprises the following steps: 1) Carbon dioxide is introduced into the reaction kettle to purge and replace the air in the reaction kettle. When the carbon dioxide content in the reaction kettle exceeds the preset content, step 2) is performed; 2) The decontamination equipment is placed in the reaction kettle, and the electromagnetic heating coil in the reaction kettle is used to heat the inside of the reaction kettle, so that the decontamination equipment is heated to a preset temperature; 3) carbon dioxide is introduced into the reactor, so that the graphite dust on the decontamination equipment reacts with the carbon dioxide to form carbon monoxide gas, the radioactive particles and radionuclides on the decontamination equipment are discharged to the outside of the reactor with the formed carbon monoxide gas, and then filtered and adsorbed by the high-efficiency particle filter (6) and the activated carbon adsorber (7), and the filtered and adsorbed carbon monoxide is burned by the carbon monoxide burner (9) and then discharged into the atmosphere.

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