Radioactive waste gas treatment system and treatment method suitable for miniature reactor

Abstract

The invention provides a radioactive waste gas treatment system and method suitable for a miniature reactor, the waste gas treatment system comprises a gas exhaust pipeline, a retention bed, a gas cavity, a vacuum source and a high efficiency filter, the retention bed is communicated with the gas exhaust system through the gas exhaust pipeline, and the gas cavity is communicated with the retention bed through the gas exhaust pipeline; the vacuum source is communicated with the air cavity through an exhaust pipeline; the high-efficiency filter is arranged between the air cavity and the vacuum source; the waste gas treatment system is in a negative pressure state through vacuumizing of the vacuum source, radioactive waste gas generated by the exhaust system enters the retention bed and the high-efficiency filter through the exhaust pipeline under the action of negative pressure and then gradually decays after being intercepted, and the decayed radioactive gas enters the downstream exhaust system through the exhaust valve. According to the radioactive waste gas treatment system, passive purification and safe emission of reactor radioactive waste gas can be achieved, and the treatment capacity and safety of the system are improved.

Description

Technical Field

[0001] The present application relates to the field of nuclear industry technology, and in particular to a radioactive waste gas treatment system and method suitable for micro reactors. Background Art

[0002] Microreactors feature high inherent safety, ease of modularization and expansion, transportability, convenient deployment, and autonomous operation, making them suitable for powering remote islands, mining areas, border defense bases, and other locations. Microreactors generate radioactive materials during operation, some of which enter the gas phase through coolant transport and other processes. Most microreactors employ a closed design, meaning they emit little or no radioactive waste gas during operation. However, during reactor shutdowns for refueling, maintenance, or certain abnormal operating conditions, the radioactive waste gas must be purged to ensure the safety of the facility and personnel. Summary of the Invention

[0003] In view of this, the present application provides a radioactive waste gas treatment system and treatment method suitable for micro reactors, which solves the technical problem in the prior art that the closed-design micro reactors need to effectively treat the radioactive waste gas generated by the reactor when they are shut down for material replacement, maintenance or some abnormal operating conditions.

[0004] According to the first aspect of the present application, the present application provides a radioactive waste gas treatment system suitable for a micro reactor, the waste gas treatment system is used to treat the radioactive waste gas generated by the exhaust system of the micro reactor during operation, the waste gas treatment system includes: an exhaust pipeline; a retention bed, the retention bed is connected to the reactor exhaust system through the exhaust pipeline; an air cavity, the air cavity is connected to the retention bed through the exhaust pipeline; a vacuum source, the vacuum source is connected to the air cavity through the exhaust pipeline; a high-efficiency filter, the high-efficiency filter is arranged on the exhaust pipeline between the air cavity and the vacuum source; wherein, the waste gas treatment system is vacuumed by the vacuum source to form a negative pressure state, and the radioactive waste gas generated by the exhaust system enters the retention bed through the exhaust pipeline and is intercepted by the high-efficiency filter under the action of negative pressure and gradually decays, and the decayed radioactive gas enters the downstream exhaust system.

[0005] In one possible implementation, the waste gas treatment system further includes: an air intake valve, which is installed on the exhaust pipeline and is used to control the radioactive waste gas discharged by the exhaust system to enter the exhaust pipeline; a gas cooler, which is installed on the exhaust pipeline and is located between the air intake valve and the retention bed, and is used to reduce the temperature of the radioactive waste gas; a valve, which is installed at the air flow outlet of the retention bed; a vacuum source isolation valve, which is installed at the air flow inlet of the vacuum source; and the high-efficiency filter is arranged between the valve and the vacuum source isolation valve.

[0006] In one possible implementation, the air inlet valve is a spring-loaded pressure control valve; and / or, the gas cooler is a finned coil cooler; and / or, the retention bed is a solid adsorption bed, and the interior of the retention bed is filled with coconut shell-based activated carbon; and / or, the air cavity is a stainless steel pressure vessel; and / or, the high-efficiency filter is a pipeline glass fiber high-efficiency filter; and / or, the vacuum source is a vacuum pump group or a vacuum chamber.

[0007] In one possible implementation, the exhaust gas treatment system also includes: an exhaust branch, which is arranged on the exhaust pipe between the high-efficiency filter and the vacuum source isolation valve, and the exhaust branch is equipped with an exhaust valve and a vacuum pump. The exhaust gas treated by the high-efficiency filter enters the downstream exhaust system through the exhaust valve under the action of the vacuum pump, wherein the exhaust valve is a spring-loaded pressure control valve.

[0008] In a possible implementation, the preset pressure of the exhaust valve is 20% higher than the preset pressure of the intake valve.

[0009] In one possible implementation, the exhaust gas treatment system further includes: a retained bed pipe, which passes through the retained bed and is arranged on the outer wall of the retained bed; a first monitoring device, which is installed on the retained bed pipe and is used to monitor the temperature and pressure in the retained bed; an air cavity pipe, which passes through the air cavity and is arranged on the outer wall of the air cavity, and a second monitoring device, which is installed on the air cavity pipe and is used to monitor the temperature and pressure in the air cavity.

[0010] According to the second aspect of the present application, the present application provides a radioactive waste gas treatment method suitable for a micro reactor, wherein the waste gas treatment method uses the waste gas treatment system described above to treat the radioactive waste gas, and before the exhaust system is operated, a vacuum source is used to evacuate the pressure of the waste gas treatment system to form a negative pressure state. When the exhaust system starts to exhaust, the radioactive waste gas is sucked into the retention bed and air cavity in the negative pressure state, wherein radioactive iodine and inert gas are adsorbed by the activated carbon in the retention bed, and radioactive aerosols are intercepted by high-efficiency filters. During the exhaust interval, the radioactive gas gradually decays, and the decayed radioactive gas enters the downstream exhaust system through the exhaust valve.

[0011] In one possible implementation, the preset pressure of the air intake valve is 0.05-1 MPa. When the pressure of the radioactive waste gas generated by the exhaust system exceeds the preset pressure of the air intake valve, the air intake valve opens; when the pressure of the radioactive waste gas generated by the exhaust system is lower than the preset pressure of the air intake valve, the air intake valve closes.

[0012] In a possible implementation, the volume of the air cavity is greater than 1 / 2 of the volume of the retention bed; and / or the pressure of the air cavity is -0.1 to 1.0 MPa.

[0013] In one possible implementation, the inert gas includes argon, krypton-85, and xenon-133; and / or the retention bed has a decontamination coefficient greater than 10 for radioactive argon, krypton, and xenon. 4 and / or, the retention bed has a decontamination coefficient of radioactive iodine greater than 10 6 ; and / or, the decontamination coefficient of the high efficiency filter for radioactive aerosols is greater than 10 3 .

[0014] In a possible implementation, the activated carbon has a dynamic adsorption coefficient of krypton-85 greater than 18 ml / g and a dynamic adsorption coefficient of xenon-133 greater than 330 ml / g under nitrogen or helium carrier gas, room temperature, and -10 kPa conditions.

[0015] The present application provides a radioactive waste gas treatment system and treatment method suitable for a micro reactor. The waste gas treatment system includes an exhaust pipeline, a retention bed, an air cavity, a vacuum source and a high-efficiency filter. The retention bed is connected to the reactor exhaust system through the exhaust pipeline, and the air cavity is connected to the retention bed through the exhaust pipeline; the vacuum source is connected to the air cavity through the exhaust pipeline; the high-efficiency filter is arranged between the air cavity and the vacuum source; the waste gas treatment system is evacuated by the vacuum source to form a negative pressure state, and the radioactive waste gas generated by the exhaust system enters the retention bed and the high-efficiency filter through the exhaust pipeline under the action of negative pressure and gradually decays after being intercepted. The decayed radioactive gas enters the downstream exhaust system through the exhaust valve. The radioactive waste gas treatment system does not require human control during operation, can realize passive purification and safe discharge of reactor radioactive waste gas, and increases the system's processing capacity and safety through the vacuum air cavity. At the same time, it adopts a modular design, can be flexibly arranged and transported with the reactor, and can realize sharing of multiple reactors in adjacent facilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Shown is a structural schematic diagram of a radioactive waste gas treatment system provided in one embodiment of the present application.

[0017] Description of reference numerals:

[0018] 1. Exhaust pipeline; 2. Inlet valve; 3. Gas cooler; 4. Retention bed; 41. Retention bed pipe; 5. First monitoring device; 6. Air cavity; 61. Air cavity pipe; 7. Second monitoring device; 8. Valve; 9. HEPA filter; 10. Vacuum source isolation valve; 11. Exhaust valve; 12. Vacuum pump; 13. Vacuum source; 14. Downstream exhaust system; 15. Exhaust branch. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. In the description of the present invention, it should be noted that the term "or" is generally used in the sense of including "and / or" unless the content clearly indicates otherwise.

[0020] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or a magnetic connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between the two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. In addition, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three or more, etc., unless otherwise clearly specified and limited.

[0021] Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] Figure 1 FIG. 1 is a schematic diagram of the structure of a radioactive waste gas treatment system provided in an embodiment of the present application. Figure 1 As shown, the waste gas treatment system is used to treat radioactive waste gas generated by the exhaust system of the micro reactor during operation. The waste gas treatment system includes: an exhaust pipe 1, which is connected to the exhaust system; a retention bed 4, which is connected to the reactor exhaust system through the exhaust pipe 1; an air cavity 6, which is connected to the retention bed 4 through the exhaust pipe 1; a vacuum source 13, which is connected to the air cavity 6 through the exhaust pipe 1; a high-efficiency filter 9, which is arranged on the exhaust pipe between the air cavity 6 and the vacuum source 13; wherein, the vacuum source 13 Vacuuming creates a negative pressure state in the waste gas treatment system. Under the action of negative pressure, the radioactive waste gas generated by the exhaust system passes through the exhaust pipe 1 into the retention bed 4 and is intercepted by the high-efficiency filter 9 and gradually decays. The decayed radioactive gas enters the downstream exhaust system. The radioactive waste gas treatment system does not require human control during operation and can achieve passive purification and safe discharge of the reactor's radioactive waste gas. The air cavity increases the system's processing capacity and safety. At the same time, it adopts a modular design, which can be flexibly arranged and transported along with the reactor, and can be shared by multiple reactors in adjacent facilities.

[0023] As a preferred embodiment, the vacuum source 13 can be arranged separately from the exhaust gas treatment system and can be detachably connected to the system only when the exhaust gas treatment system needs to be vacuumed.

[0024] In one possible implementation, the waste gas treatment system further includes: an air intake valve 2, which is installed on the exhaust pipeline 1 and is used to control the radioactive waste gas discharged from the emission system to enter the exhaust pipeline 1; a gas cooler 3, which is installed on the exhaust pipeline 1 and is located between the air intake valve 2 and the retention bed 4, and is used to reduce the temperature of the radioactive waste gas; a valve 8, which is installed at the air flow outlet of the air cavity 6; a vacuum source isolation valve 10, which is installed at the air flow inlet of the vacuum source 13; and a high-efficiency filter 9 arranged between the valve 8 and the vacuum source isolation valve 10.

[0025] As a preferred embodiment, the air intake valve 2 is installed on the exhaust pipeline 1. The preset pressure of the air intake valve 2 is preferably 0.05-1 MPa. When the pressure of the radioactive waste gas generated by the exhaust system exceeds the preset pressure of the air intake valve (0.05-1 MPa), the air intake valve 2 opens, and the radioactive waste gas is sucked into the retention bed 4 and the air cavity 6 in a negative pressure state. Radioactive iodine, argon, krypton-85, and xenon-133 are adsorbed by the activated carbon in the retention bed, and radioactive aerosols are intercepted by the high-efficiency filter 9. Since the exhaust is intermittent, the intercepted radioactive substances will gradually decay during the exhaust interval, eventually reducing the radioactive substances to an acceptable level. When the pressure of the radioactive waste gas generated by the exhaust system is lower than the preset pressure of the air intake valve 2 (0.05-1 MPa), the air intake valve 2 closes.

[0026] In one possible implementation, the intake valve 2 is preferably a spring-loaded pressure control valve; preferably, the spring-loaded pressure control valve can manually set the valve trip pressure value, and when the pressure of the radioactive waste gas generated by the exhaust system is higher or lower than the preset pressure of the intake valve 2, the spring-loaded pressure control valve can automatically open or close.

[0027] As a preferred embodiment, the gas cooler 3 is preferably a finned coil cooler; preferably, the gas cooler 3 is mounted on the exhaust pipe 1 via a flange and can be replaced regularly; preferably, the gas cooler 3 adopts air cooling to dissipate heat, and the finned coil cooler is preferably made of copper with good heat dissipation performance and equipped with a cooling fan, which can reduce the temperature of the radioactive waste gas to below 30°C;

[0028] As a preferred embodiment, the retention bed 4 is preferably a solid adsorption bed. Preferably, the interior of the retention bed 4 is filled with coconut shell-based activated carbon; the coconut shell-based activated carbon has a dynamic adsorption coefficient of krypton-85 greater than 18 ml / g and a dynamic adsorption coefficient of xenon-133 greater than 330 ml / g under carrier gas, room temperature, and -10 kPa conditions; the retention bed 4 has a decontamination coefficient of greater than 10 for radioactive argon, krypton-85, and xenon-133. 4 , the decontamination factor of radioactive iodine is greater than 10 6 .

[0029] As a preferred embodiment, the carrier gas can be nitrogen, hydrogen or helium;

[0030] As a preferred embodiment, when the coolant of the microreactor is water, the carrier gas is nitrogen or hydrogen;

[0031] As a preferred embodiment, when the microreactor is a gas-cooled reactor, the carrier gas is helium or argon.

[0032] As a preferred embodiment, the air cavity 6 is preferably a stainless steel pressure vessel. Preferably, the air cavity 6 can withstand a pressure of -0.1 to 1.0 MPa. After the retention bed 4 adsorbs radioactive gas nuclides such as radioactive iodine, argon-41, krypton-85, and xenon-133, the treated radioactive gas enters the air cavity 6. The volume of the air cavity 6 is greater than 1 / 2 of the volume of the retention bed. After the interior of the retention bed 4 is filled with coconut shell-based activated carbon, the gas space in the retention bed 4 is 1 / 2 of the volume before filling, and the volume of the air cavity 6 is greater than 1 / 2 of the volume of the retention bed. Specifically, the volume of the air cavity 6 is greater than the gas space of the retention bed 4 after the coconut shell-based activated carbon is filled. The radioactive waste gas in the air cavity 6 that has been treated with activated carbon can be introduced into the air cavity 6, thereby increasing the processing capacity and safety of the waste gas treatment system.

[0033] As a preferred embodiment, the high efficiency filter 9 is preferably a pipeline glass fiber high efficiency filter. Preferably, the high efficiency filter 9 has a decontamination coefficient of more than 10 for radioactive aerosols. 3 The pipeline glass fiber high efficiency filter is small in size and easy to disassemble and assemble.

[0034] As a preferred embodiment, the vacuum source 13 is preferably a vacuum pump group. Preferably, the gauge pressure (i.e., relative pressure) of the system is reduced to below -100 kPa by the vacuum pump, thereby forming a negative pressure state. When the exhaust system starts to exhaust, the radioactive waste gas is sucked into the retention bed and air cavity in the negative pressure state, thereby adsorbing or intercepting the radioactive substance, so that the radioactive substance after the radioactive substance gradually decays enters the downstream exhaust system through the exhaust valve 11.

[0035] In one possible implementation, the exhaust gas treatment system also includes: an exhaust branch 15, which is arranged between the high-efficiency filter 9 and the isolation valve of the vacuum source 13. The exhaust branch 15 is equipped with an exhaust valve 11 and a vacuum pump 13. The exhaust gas treated by the high-efficiency filter 9 enters the downstream exhaust system through the exhaust valve 11 under the action of the vacuum pump 13.

[0036] As a preferred embodiment, as the exhaust volume increases, the vacuum degree of the exhaust gas treatment system gradually decreases, and the pressure of the exhaust gas treatment system is finally maintained at a set micro-positive pressure value through the exhaust valve 11, and the purified exhaust gas is discharged into the downstream exhaust system. An external vacuum pump 13 can also be connected to increase the system's external exhaust flow rate and assist in exhausting the exhaust gas treatment system.

[0037] In a possible implementation, the preset pressure of the exhaust valve 11 is 20% higher than the preset pressure of the intake valve 2 .

[0038] As a preferred embodiment, the exhaust valve 11 is preferably a spring-loaded pressure control valve. The spring-loaded pressure control valve can manually set the starting pressure value of the exhaust valve 11. When the pressure at the front end of the exhaust valve 11 exceeds the preset threshold value of the exhaust valve 11, the exhaust valve 11 automatically opens. When the pressure at the front end of the exhaust valve 11 is lower than the preset threshold value of the exhaust valve 11, the exhaust valve 11 automatically closes. As the exhaust volume increases, the system vacuum gradually decreases, and the pressure of the exhaust gas treatment system is finally maintained at a set micro-positive pressure value through the exhaust valve 11. Micro-positive pressure means that the pressure of the conveyed air is less than or equal to 0.2Mpa, and the purified exhaust gas is discharged into the downstream exhaust system.

[0039] In one possible implementation, the exhaust gas treatment system also includes: a retention bed pipe 41, which passes through the retention bed 41 and is arranged on the outer wall of the retention bed 41; a first monitoring device 5, which is installed on the retention bed pipe 41 and is used to monitor the temperature and pressure in the retention bed 4; an air cavity pipe 61, which passes through the air cavity 6 and is arranged on the outer wall of the air cavity 6; a second monitoring device 7, which is installed on the air cavity pipe 61 and is used to monitor the temperature and pressure in the air cavity 6.

[0040] As a preferred embodiment, the first monitoring device 5 monitors the temperature and pressure inside the retention bed. A retention bed pipe 41 is provided on the outer wall of the retention bed 4 to communicate with the interior of the retention bed 4. The retention bed pipe 41 can be connected to the temperature and pressure monitoring device to monitor the temperature and pressure inside the retention bed 4.

[0041] As a preferred embodiment, the second monitoring device 7 monitors the thermometer pressure inside the air cavity 6. An air cavity pipe 61 is provided on the outer wall of the air cavity 6 to connect to the interior of the air cavity 6. The air cavity pipe 61 can be connected to the temperature and pressure monitoring device to monitor the temperature and pressure inside the air cavity 6.

[0042] The present application also provides a method for treating radioactive waste gas from a microreactor, using the aforementioned waste gas treatment system to treat the radioactive waste gas. The method includes using a vacuum source 13 to pump the system pressure to below -100 kPa.g before the exhaust system is operational, creating a negative pressure state. When the exhaust system begins exhausting, the radioactive waste gas is drawn into the negatively pressurized retention bed 4 and air cavity 6. Radioactive iodine and inert gas are adsorbed by the activated carbon in the retention bed, and radioactive aerosols are intercepted by a high-efficiency filter 9. During the exhaust interval, the radioactive gas gradually decays and enters the downstream exhaust system through an exhaust valve. This radioactive waste gas treatment method requires no human control during operation and can achieve passive purification and safe discharge of reactor radioactive waste gas.

[0043] In one possible implementation, the preset pressure of the intake valve 2 is 0.05-1 MPa. When the pressure of the radioactive waste gas generated by the exhaust system exceeds the preset pressure of the intake valve 2, the intake valve 2 opens; when the pressure of the radioactive waste gas generated by the exhaust system is lower than the preset pressure of the intake valve 2, the intake valve 2 closes, thereby achieving automatic opening or closing of the intake valve 2.

[0044] In a possible implementation, the volume of the air cavity is greater than 1 / 2 of the volume of the retention bed; and the pressure of the air cavity is -0.1 to 1.0 MPa.

[0045] In one possible implementation, the inert gas includes argon, krypton-85, and xenon-133; and / or the decontamination coefficient of the retention bed 4 for radioactive argon, krypton, and xenon is greater than 10. 4 and / or, the decontamination factor of the retention bed 4 for radioactive iodine is greater than 10 6 ; and / or, the HEPA filter 9 has a decontamination coefficient of greater than 10 for radioactive aerosols 3 .

[0046] In one possible implementation, the activated carbon has a dynamic adsorption coefficient for krypton-85 greater than 18 ml / g and a dynamic adsorption coefficient for xenon-133 greater than 330 ml / g under nitrogen or helium carrier gas, room temperature, and -10 kPa conditions.

[0047] The specific implementation of the exhaust gas treatment system is as follows:

[0048] Before the exhaust gas treatment system is put into operation, the retention bed 4 and the gas cavity 6 must be evacuated using the vacuum source 13, the vacuum source isolation valve 10 must be opened, the system pressure must be reduced to below -100 kPa.g using the vacuum source 13, and the valve 8 must be opened; the exhaust pipe 1 must be connected to the reactor exhaust system.

[0049] When the reactor exhaust system starts to exhaust, the pressure in front of the intake valve 2 will gradually increase. When the pressure in front of the intake valve 2 exceeds the valve setting value of 0.05-1 MPa, the intake valve 2 will automatically open, and the exhaust gas containing radioactive substances will enter the gas cooler 3 under negative pressure. The gas cooler 3 is a fin coil cooler, which uses air cooling to dissipate heat and is equipped with a cooling fan to reduce the temperature of the radioactive exhaust gas to below 30°C. The cooled radioactive exhaust gas then enters the retention bed 4. The retention bed 4 is densely packed with coconut shell-based activated carbon. Most of the radioactive iodine, argon-41, krypton-85, xenon-133 and other reflective gas nuclides in the radioactive exhaust gas are adsorbed by the activated carbon in the retention bed 4. The radioactive exhaust gas after adsorption enters the air cavity 6. The gas entering the air cavity 6 is basically non-radioactive. The gas in the air cavity 6 enters the high-efficiency filter 9 through the valve 8. The high-efficiency filter 9 is a ducted glass fiber high-efficiency filter. Most of the radioactive aerosols in the exhaust gas are adsorbed by the high-efficiency filter 9. When the exhaust volume of the exhaust system decreases, the system operating pressure can always maintain a slight negative pressure of -30 to -10 kPa. When the exhaust volume of the exhaust system continues to increase, the pressure in the retention bed 4 and the air cavity 6 gradually increases. When the pressure in the retention bed 4 and the air cavity 6 exceeds the pressure set by the exhaust valve 11, the exhaust valve 11 automatically opens and begins to exhaust to the downstream exhaust system. After the exhaust is completed, the radioactive components adsorbed by the activated carbon will gradually decay. Before the next exhaust, the radioactive iodine, krypton, and xenon will decay to extremely low levels. The remaining very small amount of radioactive components will be slowly released with the next exhaust. The radioactivity level can meet the emission standards. The radioactivity level in the exhaust gas of this system is always maintained at an acceptable, low level, thereby achieving purification of the reactor radioactive waste gas.

[0050] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A radioactive waste gas treatment system suitable for a micro reactor, characterized in that: The waste gas treatment system is used to treat the radioactive waste gas generated by the exhaust system of the micro reactor during operation, and the waste gas treatment system includes: an exhaust pipeline, the exhaust pipeline being connected to the reactor exhaust system; a retention bed, the retention bed being connected to the exhaust system via the exhaust pipeline; an air cavity, the air cavity being in communication with the retention bed through the exhaust pipe; a vacuum source, the vacuum source being connected to the air cavity through the exhaust pipeline; A high efficiency filter, the high efficiency filter is arranged on the exhaust pipeline between the air cavity and the vacuum source; The waste gas treatment system is evacuated by the vacuum source to form a negative pressure state. The radioactive waste gas generated by the exhaust system enters the retention bed through the exhaust pipeline under the action of negative pressure and is intercepted by the high-efficiency filter and gradually decays. The decayed radioactive gas enters the downstream exhaust system.

2. The radioactive waste gas treatment system according to claim 1, characterized in that: It also includes an air intake valve, which is installed on the exhaust pipeline and is used to control the radioactive waste gas discharged by the exhaust system to enter the exhaust pipeline; A gas cooler, the gas cooler being installed on the exhaust pipeline, the gas cooler being located between the air inlet valve and the retention bed, and the gas cooler being used to reduce the temperature of the radioactive waste gas; A valve, which is installed at the air flow outlet of the air cavity; A vacuum source isolation valve is installed at the air flow inlet of the vacuum source; and the high efficiency filter is arranged between the valve and the vacuum source isolation valve.

3. The radioactive waste gas treatment system according to claim 2, characterized in that: The air intake valve is a spring-loaded pressure control valve; And / or, the gas cooler is a fin coil cooler; And / or, the retention bed is a solid adsorption bed, and the interior of the retention bed is filled with coconut shell-based activated carbon; And / or, the air cavity is a stainless steel pressure vessel; And / or, the high efficiency filter is a pipeline glass fiber high efficiency filter; And / or, the vacuum source is a vacuum pump set or a vacuum chamber.

4. The radioactive waste gas treatment system according to claim 1, characterized in that: Also includes: An exhaust branch is provided on the exhaust pipeline between the high-efficiency filter and the vacuum source isolation valve. The exhaust branch is equipped with an exhaust valve and a vacuum pump. The exhaust gas treated by the high-efficiency filter enters the downstream exhaust system through the exhaust valve under the action of the vacuum pump, wherein the exhaust valve is a spring-loaded pressure control valve.

5. The radioactive waste gas treatment system according to claim 4, characterized in that: The preset pressure of the exhaust valve is 20% higher than the preset pressure of the intake valve.

6. The radioactive waste gas treatment system according to claim 1, characterized in that: Also includes: A retention bed pipe, the retention bed pipe passes through the retention bed and is arranged on an outer wall of the retention bed; A first monitoring device, the first monitoring device is installed on the retention bed pipe, and the first monitoring device is used to monitor the temperature and pressure in the retention bed; An air cavity pipe, the air cavity pipe passes through the air cavity and is arranged on the outer wall of the air cavity; A second monitoring device is installed on the air cavity connecting pipe, and is used to monitor the temperature and pressure in the air cavity.

7. A method for treating radioactive waste gas suitable for a micro reactor, characterized in that: The radioactive waste gas is treated using the waste gas treatment system described in any one of claims 1 to 6, the method comprising: using a vacuum source to evacuate the pressure of the waste gas treatment system to below -100 kPa.g to form a negative pressure state before the exhaust system is operated; after the exhaust system starts exhausting, the radioactive waste gas is sucked into the retention bed and the air cavity in the negative pressure state, wherein radioactive iodine and inert gas are adsorbed by the activated carbon in the retention bed, and radioactive aerosols are intercepted by the high-efficiency filter; during the exhaust interval, the radioactive gas gradually decays, and the decayed radioactive gas enters the downstream exhaust system through the exhaust valve.

8. The method for treating radioactive waste gas according to claim 7, characterized in that: The preset pressure of the air intake valve is 0.05-1Mpa. When the pressure of the radioactive waste gas generated by the exhaust system exceeds the preset pressure of the air intake valve, the air intake valve opens; when the pressure of the radioactive waste gas generated by the exhaust system is lower than the preset pressure of the air intake valve, the air intake valve closes.

9. The method for treating radioactive waste gas according to claim 7, characterized in that: The volume of the air cavity is greater than 1 / 2 of the volume of the retention bed; and / or, the pressure of the air cavity is -0.1 to 1.0 MPa.

10. The method for treating radioactive waste gas according to claim 7, characterized in that: The inert gas includes argon, krypton-85 and xenon-133; and / or the retention bed has a decontamination coefficient greater than 10 for radioactive argon, krypton and xenon. 4 ; and / or, the retention bed has a decontamination factor of radioactive iodine greater than 10 6 ; and / or, the decontamination coefficient of the high efficiency filter for radioactive aerosols is greater than 10 3 .

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