Multistage deep tritium removal system and method for helium-3 gas after tritium decay

Abstract

The invention discloses a multistage deep tritium removal system and method for helium-3 gas after tritium decay. The multistage deep tritium removal system comprises an online chromatography, a first-stage subsystem, a second-stage subsystem and a third-stage subsystem, a hydrogen absorption isotope device, a catalytic oxidation device, a water adsorption device, a low-temperature adsorption device, an on-line chromatography and an on-line ionization chamber are combined, and tritium in helium-3 gas is efficiently removed by adopting a subsystem design. Through the design of the three-stage subsystem, the tritium concentration is gradually reduced from the first-stage subsystem, the second-stage subsystem and the third-stage subsystem, all the systems are connected through valves, and the problem that tritium is difficult to remove due to the fact that the whole system is polluted due to tritium pollution is effectively solved. The three subsystems can operate independently and simultaneously and do not influence each other, so that the purification efficiency is improved.

Description

Technical Field

[0001] This patent relates to the technical field of helium-3 gas production, and specifically to a multi-stage deep detritiation system and method for helium-3 gas after tritium decay. Background Art

[0002] Helium-3 on Earth is mainly produced by tritium decay, and its natural reserves are extremely small. Helium-3 has a wide range of applications in nuclear fusion, medicine, cryogenic refrigeration, and neutron science. Helium-3 is produced during the extraction and storage of tritium. Since the helium-3 produced by tritium decay is inevitably accompanied by a small amount of tritium, its volume ratio is generally between 0.01 and 0.05%. Tritium itself is radioactive and can easily cause radiation damage to people during operation. The presence of tritium also affects the use of helium-3 gas. For example, in a helium-3 proportional counter tube, tritium will increase the measurement background of the proportional counter tube and reduce its use value. The tritium volume ratio required in helium-3 is generally less than 10 -11 , which is a very small value.

[0003] The main purpose of helium-3 purification is to remove tritium. Since it has not yet been industrialized, there is no special purification device. Methods for removing tritium include hydrogen storage isotope material adsorption, catalytic oxidation, etc. The principle of hydrogen absorbing isotope material adsorption is to use the hydrogen absorbing isotope characteristics of hydrogen absorbing isotope materials to remove trace tritium in helium-3. Commonly used hydrogen absorbing isotope materials include ZrCo alloy, ZrFe alloy, sponge titanium, metallic uranium, etc. Generally, hydrogen absorbing isotope metals with low hydrogen absorbing isotope platform pressure are selected. Metallic uranium is rarely used because it is a controlled nuclear material.

[0004] The principle of the catalytic oxidation method is that in the presence of oxygen, the palladium-platinum catalyst can oxidize the trace tritium remaining in helium-3 to generate tritiated water, and the water is adsorbed by water-absorbing materials, such as calcium chloride particles, calcium oxide particles, water-absorbing color-changing silica gel, molecular sieves, etc., thereby achieving further purification of trace tritium.

[0005] The principle of low temperature adsorption is that the boiling point of helium is much lower than that of impurities in the air, including neon, oxygen, nitrogen, carbon dioxide, methane, water, etc. All impurities can be removed at one time by low temperature adsorption at liquid nitrogen temperature. The adsorbent can be fine porous silica gel, alumina, molecular sieve or porous activated carbon. Low temperature adsorption plays a major role in the deep removal of tritium-containing water in the detritium removal process.

[0006] According to the principle of metal hydrogen absorption, when the hydrogen partial pressure is high, the metal material mainly absorbs hydrogen. When the hydrogen partial pressure of the gas in the system decreases, the metal material will slowly release the adsorbed hydrogen. In this way, when the system continues to be used for detritium removal, the slowly released tritium will be mixed into the gas to be purified, affecting the purification effect. Since the system pipes, valves, containers, etc. are made of stainless steel as the main material, when tritium is purified, a small amount of tritium will be adsorbed on the surface of the stainless steel material of the system, causing contamination. This will make it difficult to remove tritium from the system. Therefore, the system is designed in stages so that the gas purified by the previous system enters the next system for re-purification to avoid tritium contamination.

[0007] This paper designs a method for removing trace tritium and other impurities in helium-3 gas. This method mainly uses hydrogen isotope material adsorption, low-temperature adsorption, catalytic oxidation and other methods to remove trace tritium. By designing subsystems and combining them into a whole, it is difficult to remove trace tritium caused by tritium contamination. Summary of the invention

[0008] The purpose of the present invention is to provide a multi-stage deep detritium removal system and method for helium-3 gas after tritium decay in order to solve the problem of detritium in helium-3 and the problem of tritium contamination of the system. The system combines a hydrogen isotope absorption device, a catalytic oxidation device, a water adsorption device, a low-temperature adsorption device, an online chromatograph and an online ionization chamber, and adopts a subsystem design to efficiently remove tritium from helium-3 gas.

[0009] The technical solution of the present invention is as follows: a multi-stage deep detritium removal system for helium-3 gas after tritium decay, comprising an online chromatograph and a primary subsystem, a secondary subsystem, and a tertiary subsystem;

[0010] The primary subsystem comprises a high-range ionization chamber measuring cavity, a raw gas tank, a circulation pump A, a hydrogen isotope absorption device, a catalytic oxidation device A, a water absorption device A, and a vacuum pump group A; wherein the outlet of the raw gas tank is connected to the inlet of the circulation pump A, the outlet of the circulation pump A is connected to the inlet of the hydrogen isotope absorption device, the inlet of the catalytic oxidation device A, and the gas charging port of the secondary subsystem raw gas tank, the outlet of the hydrogen isotope absorption device is connected to the inlet of the high-range ionization chamber measuring cavity and the online chromatogram, the outlet of the catalytic oxidation device A is connected to the inlet of the water absorption device A, the outlet of the water absorption device A is connected to the inlet of the high-range ionization chamber measuring cavity and the online chromatogram injection port, and the vacuum pump group A is respectively connected to the outlets of the high-range ionization chamber measuring cavity, the hydrogen isotope absorption device, the catalytic oxidation device A, and the water absorption device A through a vacuum pipeline;

[0011] The secondary subsystem includes a mid-range ionization chamber measuring cavity, a secondary subsystem raw gas tank, a circulation pump B, a catalytic oxidizer B, a water absorption device B, and a vacuum pump group B; wherein the outlet of the raw gas tank is connected to the inlet of the circulation pump B, the outlet of the circulation pump B is connected to the inlet of the catalytic oxidizer B and the inlet of the tertiary subsystem raw gas tank, the outlet of the catalytic oxidizer B is connected to the inlet of the water absorption device B, and the outlet of the water absorption device B is connected to the inlet of the mid-range ionization chamber measuring cavity and the online chromatographic inlet; the vacuum pump group B is connected to the mid-range ionization chamber measuring cavity, the catalytic oxidizer B, and the water absorption device B;

[0012] The tertiary subsystem includes a low-range ionization chamber measuring cavity, a tertiary subsystem raw gas tank, a circulating pump C, a catalytic oxidation device C, a water absorption device C, a low-temperature adsorption device, a vacuum pump group C, and a product tank; wherein the outlet of the tertiary subsystem raw gas tank is connected to the inlet of the circulating pump C, the outlet of the circulating pump C is connected to the inlet of the catalytic oxidation device C, the inlet of the low-temperature adsorption device and the sample inlet of the product tank, the outlet of the catalytic oxidation device C is connected to the inlet of the water absorption device C, the outlet of the water absorption device C is connected to the inlet of the low-range ionization chamber measuring cavity and the online chromatogram; the outlet of the low-temperature adsorption device is connected to the inlet of the low-range ionization chamber measuring cavity and the inlet of the online chromatogram; the vacuum pump group C is connected to the low-range ionization chamber measuring cavity, the catalytic oxidation device C, the water absorption device C, and the low-temperature adsorption device.

[0013] The online chromatograph is equipped with a purge gas and is a one-way measurement without recycling the measuring gas.

[0014] Vacuum pump group A, vacuum pump group B and vacuum pump group C all include a mechanical vacuum pump and a molecular pump.

[0015] The hydrogen absorbing isotope device is filled with one of ZrCo alloy, ZrFe, or titanium sponge.

[0016] Catalytic oxidation device A, catalytic oxidation device B and catalytic oxidation device C are loaded with palladium-platinum catalysts.

[0017] The water absorption device A, the water absorption device B and the water absorption device C are filled with one of molecular sieves, water-absorbing color-changing silica gel, calcium chloride particles or calcium oxide particles; the low-temperature adsorption device is located in the cold trap, and the cold trap is filled with liquid nitrogen.

[0018] A method for removing tritium and other impurities from helium-3 gas, comprising the following steps:

[0019] S1: Leak detection is performed on the hydrogen isotope absorption device, the chemical oxidation device A, the catalytic oxidation device B, the catalytic oxidation device C, the water absorption device A, the water absorption device B, and the water absorption device C, and vacuum is continuously drawn under heating;

[0020] S2: Connect the purified raw gas tank to the first-level subsystem, start the vacuum pump group A to evacuate the high-range ionization chamber measurement cavity 1, the hydrogen isotope absorption device, the catalytic oxidation device A, and the water absorption device A;

[0021] S3: Start the circulation pump of the first-level subsystem to pump the raw gas in the raw gas tank into the hydrogen isotope absorption device. After being purified in the hydrogen isotope absorption device, the raw gas is sent to the online chromatography to analyze the hydrogen isotope and other impurity contents;

[0022] S4: When the content of hydrogen isotopes and other impurities in the hydrogen isotope absorption device in the online chromatographic analysis is ≤10ppm, stop feeding the raw gas into the hydrogen isotope absorption device, and let the raw gas in the raw gas tank pass through the catalytic oxidation device of the primary subsystem, then through the water absorption device, and then through the high-range ionization chamber measurement cavity to measure the radioactivity;

[0023] S5: When the radioactivity measured by the high-range ionization chamber is ≤10 9 Bq / m 3 , turn off the catalytic oxidation device and water absorption device of the first-level subsystem, and fill the gas purified by the first-level subsystem into the raw gas tank of the second-level subsystem through the first-level subsystem circulation pump;

[0024] S6: Start vacuum pump group B to evacuate the measuring chamber of the mid-range ionization chamber, catalytic oxidizer B, and water absorption device B; send the raw gas in the secondary subsystem raw gas tank to the catalytic oxidizer B through the circulation pump B, and then send it to the measuring chamber of the mid-range ionization chamber to measure the radioactivity after passing through the water absorption device B; when the radioactivity is ≤10 7 Bq / m 3 When the catalytic oxidation device B and the water absorption device B are turned off, the gas purified by the secondary subsystem is charged into the raw gas tank of the tertiary subsystem;

[0025] S7: Start the vacuum pump group C to evacuate the low-range ionization chamber measurement chamber, catalytic oxidation device C, water absorption device C, and low-temperature adsorption device; send the raw gas in the raw gas tank of the tertiary subsystem to the catalytic oxidation device C through the circulation pump C, and then send it to the low-range ionization chamber measurement chamber to measure the radioactivity after passing through the water absorption device C. When the radioactivity is ≤10 5 Bq / m 3 When the catalytic oxidation device C and the water absorption device C are closed, the raw gas enters the low-temperature adsorption device;

[0026] S8: Analyze hydrogen isotopes and other impurities and radioactive activity in the cryogenic adsorption device through online chromatography and low-range ionization chamber measurement cavity; after reaching the technical indicators, close the cryogenic adsorption device, online chromatography and low-range ionization chamber measurement cavity, and fill the raw gas into the product tank.

[0027] In the S1 and S2, the vacuum is evacuated to a vacuum degree of <20Pa; in the S6, the vacuum is evacuated to a vacuum degree of ≤1Pa.

[0028] In S5, when the radioactivity measured by the high-range ionization chamber measurement cavity is greater than 109 Bq / m 3 The raw gas continues to circulate in the primary subsystem; in S6, when the radioactivity measured by the high-range ionization chamber measurement cavity is greater than 10 7 Bq / m 3 At the same time, the raw gas continues to circulate in the second stage.

[0029] In S8, the technical indicators are: helium-3 gas purity ≥ 99.999%, radioactivity ≤ 10 5 Bq / m 3 .

[0030] The remarkable effects of the present invention are:

[0031] Through the three-level subsystem design, the tritium concentration is gradually reduced from the primary, secondary and tertiary subsystems. The systems are connected by valves, which effectively solves the problem of overall system contamination caused by tritium contamination and the subsequent difficulty in removing tritium.

[0032] The three subsystems can operate independently and simultaneously without affecting each other, which increases the purification efficiency.

[0033] Optimize the fillers of each purification equipment to achieve the purpose of rapid and deep purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of a multi-stage deep detritiation system for helium-3 gas after tritium decay;

[0035] In the figure: 1 high-range ionization chamber measurement cavity; 2 raw gas tank; 3 circulation pump A; 4 hydrogen isotope absorption device; 5 catalytic oxidation device A; 6 water absorption device A; 7 vacuum pump group A; 8 medium-range ionization chamber measurement cavity; 9 secondary subsystem raw gas tank; 10 circulation pump B; 11 catalytic oxidation device B; 12 water absorption device B; 13 vacuum pump group B; 14 low-range ionization chamber measurement cavity; 15 tertiary subsystem raw gas tank; 16 circulation pump C; 17 catalytic oxidation device C; 18 water absorption device C; 19 low-temperature adsorption device; 20 vacuum pump group C; 21 product gas tank; 22 online chromatograph. DETAILED DESCRIPTION

[0036] Many specific details are described in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present application, so the present application is not limited by the specific implementation disclosed below.

[0037] The terms used in one or more embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit one or more embodiments of the present application. The singular forms of "a", "said" and "the" used in one or more embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used in one or more embodiments of the present application refers to and includes any or all possible combinations of one or more associated listed items.

[0038] It should be understood that, although the terms first, second, etc. may be used to describe various information in one or more embodiments of the present application, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of one or more embodiments of the present application, the first may also be referred to as the second, and similarly, the second may also be referred to as the first.

[0039] The present patent is further described below in conjunction with the accompanying drawings;

[0040] A system for removing tritium impurities from helium-3 gas comprises an online chromatograph 22 and a primary subsystem, a secondary subsystem, and a tertiary subsystem, wherein the primary subsystem comprises a high-range ionization chamber measuring chamber 1, a raw gas tank 2, a circulation pump A3, a hydrogen isotope absorption device 4, a catalytic oxidation device A5, a water absorption device A6, and a vacuum pump group A7. The outlet of the raw gas tank 2 is connected to the inlet of the circulation pump A3, the outlet of the circulation pump A3 is connected to the inlet of the hydrogen isotope absorption device 4, the inlet of the catalytic oxidation device A5, and the gas charging port of the secondary subsystem raw gas tank 9, the outlet of the hydrogen isotope absorption device 4 is connected to the inlet of the high-range ionization chamber measuring chamber 1 and the online chromatograph 22, the outlet of the catalytic oxidation device A5 is connected to the inlet of the water absorption device A6, the outlet of the water absorption device A6 is connected to the inlet of the high-range ionization chamber measuring chamber 1, and the inlet of the online chromatograph 22, and the vacuum pump group A7 is respectively connected to the outlets of the high-range ionization chamber measuring chamber 1, the hydrogen isotope absorption device 4, the catalytic oxidation device A5, and the water absorption device A6 through a vacuum pipeline.

[0041] The secondary subsystem includes a mid-range ionization chamber measuring chamber 8, a secondary subsystem raw gas tank 9, a circulating pump B10, a catalytic oxidation device B11, a water absorption device B12, and a vacuum pump group B13. The outlet of the raw gas tank 9 is connected to the inlet of the circulating pump B10, the outlet of the circulating pump B10 is connected to the inlet of the catalytic oxidation device B11 and the inlet of the tertiary subsystem raw gas tank 15, the outlet of the catalytic oxidation device B11 is connected to the inlet of the water absorption device B12, and the outlet of the water absorption device B12 is connected to the inlet of the mid-range ionization chamber measuring chamber 8 and the inlet of the online chromatograph 22; the vacuum pump group B13 is connected to the mid-range ionization chamber measuring chamber 8, the catalytic oxidation device B11, and the water absorption device B12;

[0042] The tertiary subsystem includes a low-range ionization chamber measurement chamber 14, a tertiary subsystem raw gas tank 15, a circulation pump C16, a catalytic oxidation device C17, a water absorption device C18, a cryogenic adsorption device 19, a vacuum pump group C20, and a product tank 21. The outlet of the tertiary subsystem raw gas tank 15 is connected to the inlet of the circulation pump C16, the outlet of the circulation pump C16 is connected to the inlet of the catalytic oxidation device C17, the inlet of the cryogenic adsorption device 19 and the sample inlet of the product tank 21, the outlet of the catalytic oxidation device C17 is connected to the inlet of the water absorption device C18, the outlet of the water absorption device C18 is connected to the inlet of the low-range ionization chamber measurement chamber 14 and the online chromatogram 22; the outlet of the cryogenic adsorption device 19 is connected to the inlet of the low-range ionization chamber measurement chamber 14 and the inlet of the online chromatogram 22. The vacuum pump group C20 is connected to the low-range ionization chamber measurement chamber 14, the catalytic oxidation device C17, the water absorption device C18, and the cryogenic adsorption device 19;

[0043] The ionization chamber is divided into a high-range ionization chamber measurement chamber 1, a medium-range ionization chamber measurement chamber 8, and a low-range ionization chamber measurement chamber 14, which are respectively installed on the primary subsystem, the secondary subsystem, and the tertiary subsystem circulation loops. The signal lines used in the measurement chambers are all introduced into the same current analysis device, and the measurement chambers have a self-purification function;

[0044] The high-range ionization chamber measuring chamber 1, the mid-range ionization chamber measuring chamber 8, and the low-range ionization chamber measuring chamber 14 are used to measure radioactivity; and the online chromatograph 22 is used to measure the content of hydrogen isotopes and other impurities;

[0045] The online chromatograph 22 is equipped with a purge gas, and the online chromatograph is a one-way measurement, and the measurement gas is not recycled;

[0046] The devices are connected by reliable sealing connection, such as VCR connection or organic pad connection;

[0047] The hydrogen isotope absorption device, catalytic oxidation device, water absorption device, and low-temperature adsorption device are all cylindrical, filled with different fillers to achieve different functions, and are welded into one piece. A heating device is used to provide high temperature for its operation or degassing. The low-temperature adsorption device is also equipped with a liquid nitrogen cold trap to provide a low-temperature working environment.

[0048] Necessary pressure detection devices, vacuum detection devices, valves, etc. are installed at corresponding positions in the system. Pneumatic valves can be used to realize various functions of the system.

[0049] The vacuum pump group includes a mechanical vacuum pump and a molecular pump.

[0050] Mechanical vibration devices such as vacuum pump units and circulation pumps are protected against vibration by effective shock-absorbing methods such as cast iron bases.

[0051] A method for removing tritium and other impurities from helium-3 gas, comprising the following steps:

[0052] S1: Load and weld each device, where the hydrogen absorption isotope device 4 is loaded with one of ZrCo alloy, ZrFe or titanium sponge; the catalytic oxidation device (catalytic oxidation device A5, catalytic oxidation device B11, catalytic oxidation device C17) is loaded with palladium platinum catalyst; the water absorption device (water absorption device A6, water absorption device B12, water absorption device C18) is loaded with one of molecular sieve, water absorption color-changing silica gel, calcium chloride particles or calcium oxide particles; after loading, welding, leak detection and other work are carried out, and after confirmation, the system is loaded and continuously vacuumed under heating. Evacuate until the vacuum degree is <20Pa or lower, and adjust its temperature to the working temperature for standby.

[0053] S2: Connect the purified raw gas tank 2 to the first-level subsystem, start the vacuum pump group A7 to evacuate the high-range ionization chamber measurement cavity 1, the hydrogen isotope absorption device 4, the catalytic oxidation device A5, and the water absorption device A6 to <20Pa or lower.

[0054] S3: Start the primary subsystem circulation pump 3 to pump the raw gas in the raw gas tank 2 to the hydrogen isotope absorption device 4. After being purified in the hydrogen isotope absorption device 4, the raw gas is sent to the online chromatograph 22 for analysis of tritium and other impurities.

[0055] When the online chromatograph 22 analyzes that the content of tritium and other impurities in the hydrogen isotope device 4 is ≤10ppm, the introduction of raw gas into the hydrogen isotope device 4 is stopped, and the raw gas in the raw gas tank 2 passes through the catalytic oxidation device 5 of the primary subsystem, and then is purified through the water absorption device 6, and then the radioactivity is measured through the high-range ionization chamber measurement cavity 1.

[0056] S5: When the radioactivity measured by the high-range ionization chamber measurement chamber 1 is ≤10 9 Bq / m 3 , turn off the catalytic oxidation device 5 and the water absorption device 6 of the primary subsystem, and fill the gas purified by the primary subsystem into the secondary subsystem raw gas tank 9 through the primary subsystem circulation pump 3, otherwise it continues to circulate in the primary subsystem;

[0057] S6: Start the vacuum pump group B13 to evacuate the measuring chamber 8 of the mid-range ionization chamber, the catalytic oxidation device B11, and the water absorption device B12 (≤1Pa); send the raw gas in the secondary subsystem raw gas tank 9 to the catalytic oxidation device B11 through the circulation pump B10, and then send it to the measuring chamber 8 of the mid-range ionization chamber to measure the radioactivity after passing through the water absorption device B12; when the radioactivity is ≤10 7 Bq / m 3 When the catalytic oxidation device B11 and the water absorption device B12 are closed, the gas purified by the secondary subsystem is charged into the raw gas tank 15 of the tertiary subsystem, otherwise it continues to circulate in the secondary subsystem;

[0058] S7: Start the vacuum pump group C20 to evacuate the low-range ionization chamber measurement chamber 14, the catalytic oxidation device C17, the water absorption device C18, and the low-temperature adsorption device 19; send the raw gas in the three-stage subsystem raw gas tank 15 to the catalytic oxidation device C17 through the circulation pump C16, and then send it to the low-range ionization chamber measurement chamber 14 to measure the radioactivity after passing through the water absorption device C18. When the radioactivity is ≤10 5 Bq / m 3 When the catalytic oxidation device C17 and the water absorption device C18 are closed, the raw gas is allowed to enter the cryogenic adsorption device 19 for deep cold purification (the cold trap of the cryogenic adsorption device 19 is filled with liquid nitrogen);

[0059] S8: Analyze tritium and other impurities and radioactivity in the cryogenic adsorption device 19 through the online chromatograph 22 and the low-range ionization chamber measuring cavity 14; after reaching the technical indicators (helium-3 gas purity ≥ 99.999%, radioactivity ≤ 10 5 Bq / m 3 ), close the low-temperature adsorption device 19, the online chromatograph 22 and the low-range ionization chamber measurement cavity 14, and allow the gas to be filled into the product tank 21.

[0060] Experimental test results:

[0061] The single-stage system and the independent multi-stage system were used to detect the radioactivity of tritium at 10 12 Bq / m 3 The detritium removal test was carried out using helium-3 gas. The raw gas volume of both systems was 20L, and the running time was 12h. After the test, the ionization chamber and ultra-trace tritium detector were used for detection. The experimental results are as follows:

[0062]

[0063] It can be seen that after the multi-stage deep detritiation system and method of this patent, the radioactive activity of the purified gas has been greatly reduced, meeting the relevant requirements.

[0064] The above description is only a preferred embodiment of this patent and is not intended to limit this patent. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this patent should be included in the scope of protection of this patent.

[0065] It should be noted that, for the convenience of description, the aforementioned method embodiments are all described as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described action sequence, because according to the present application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

[0066] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0067] The preferred embodiments of the present application disclosed above are only used to help explain the present application. The optional embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of the present application. The present application selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can understand and use the present application well.

Claims

1. A multi-stage deep detritium removal system for helium-3 gas after tritium decay, characterized in that: It includes an online chromatograph (22) and a primary subsystem, a secondary subsystem, and a tertiary subsystem; The primary subsystem comprises a high-range ionization chamber measuring chamber (1), a raw gas tank (2), a circulation pump A (3), a hydrogen isotope absorption device (4), a catalytic oxidation device A (5), a water absorption device A (6), and a vacuum pump group A (7); wherein the outlet of the raw gas tank (2) is connected to the inlet of the circulation pump A (3), the outlet of the circulation pump A (3) is connected to the inlet of the hydrogen isotope absorption device (4), the inlet of the catalytic oxidation device A (5) and the charging port of the raw gas tank (9) of the secondary subsystem, and the hydrogen isotope absorption device ( 4) the outlet is connected to the inlet of the high-range ionization chamber measurement chamber (1) and the online chromatograph (22); the outlet of the catalytic oxidation device A (5) is connected to the inlet of the water absorption device A (6); the outlet of the water absorption device A (6) is connected to the inlet of the high-range ionization chamber measurement chamber (1) and the inlet of the online chromatograph (22); the vacuum pump group A (7) is connected to the outlets of the high-range ionization chamber measurement chamber (1), the hydrogen isotope absorption device (4), the catalytic oxidation device A (5) and the water absorption device A (6) through vacuum pipes; The secondary subsystem comprises a mid-range ionization chamber measuring chamber (8), a secondary subsystem raw gas tank (9), a circulation pump B (10), a catalytic oxidation device B (11), a water absorption device B (12), and a vacuum pump group B (13); wherein the outlet of the raw gas tank (9) is connected to the inlet of the circulation pump B (10), the outlet of the circulation pump B (10) is connected to the inlet of the catalytic oxidation device B (11) and the sample inlet of the tertiary subsystem raw gas tank (15), the outlet of the catalytic oxidation device B (11) is connected to the inlet of the water absorption device B (12), and the outlet of the water absorption device B (12) is connected to the inlet of the mid-range ionization chamber measuring chamber (8) and the sample inlet of the online chromatogram (22); the vacuum pump group B (13) is connected to the mid-range ionization chamber measuring chamber (8), the catalytic oxidation device B (11), and the water absorption device B (12); The tertiary subsystem comprises a low-range ionization chamber measurement chamber (14), a tertiary subsystem raw gas tank (15), a circulation pump C (16), a catalytic oxidation device C (17), a water absorption device C (18), a cryogenic adsorption device (19), a vacuum pump group C (20), and a product tank (21); wherein the outlet of the tertiary subsystem raw gas tank (15) is connected to the inlet of the circulation pump C (16), and the outlet of the circulation pump C (16) is connected to the inlet of the catalytic oxidation device C (17), the inlet of the cryogenic adsorption device (19), and the product tank (21). ) inlet, the outlet of the catalytic oxidation device C (17) is connected to the inlet of the water absorption device C (18), and the outlet of the water absorption device C (18) is connected to the inlet of the low-range ionization chamber measurement chamber (14) and the online chromatograph (22); the outlet of the low-temperature adsorption device (19) is connected to the inlet of the low-range ionization chamber measurement chamber (14) and the inlet of the online chromatograph (22); the vacuum pump group C (20) is connected to the low-range ionization chamber measurement chamber (14), the catalytic oxidation device C (17), the water absorption device C (18), and the low-temperature adsorption device (19).

2. A multi-stage deep detritium removal system for helium-3 gas after tritium decay according to claim 1, characterized in that: The online chromatograph (22) is equipped with a purge gas and is a single-pass measurement without recycling the measurement gas.

3. A multi-stage deep detritium removal system for helium-3 gas after tritium decay according to claim 1, characterized in that: The vacuum pump group A (7), the vacuum pump group B (13) and the vacuum pump group C (20) all include a mechanical vacuum pump and a molecular pump.

4. A multi-stage deep detritium removal system for helium-3 gas after tritium decay according to claim 1, characterized in that: The hydrogen isotope absorbing device (4) is filled with one of ZrCo alloy, ZrFe, or titanium sponge.

5. A multi-stage deep detritium removal system for helium-3 gas after tritium decay according to claim 4, characterized in that: The catalytic oxidation device A (5), the catalytic oxidation device B (11) and the catalytic oxidation device C (17) are loaded with palladium-platinum catalysts.

6. A multi-stage deep detritium removal system for helium-3 gas after tritium decay according to claim 5, characterized in that: The water absorption device A (6), the water absorption device B (12), and the water absorption device C (18) are filled with molecular sieves, water-absorbing color-changing silica gel, calcium chloride particles, or calcium oxide particles; the low-temperature adsorption device (19) is located in the cold trap, and the cold trap is filled with liquid nitrogen.

7. A method for removing tritium and other impurities from helium-3 gas, using the multi-stage deep detritiation system for helium-3 gas after tritium decay as claimed in claim 5, characterized in that: The following steps are involved: S1: Leak detection is performed on the hydrogen isotope absorption device (4), the chemical oxidation device A (5), the catalytic oxidation device B (11), the catalytic oxidation device C (17), the water absorption device A (6), the water absorption device B (12), and the water absorption device C (18), and vacuum is continuously drawn under heating; S2: Connect the purified raw gas tank (2) to the primary subsystem, start the vacuum pump group A (7) to evacuate the high-range ionization chamber measurement cavity (1), the hydrogen isotope absorption device (4), the catalytic oxidation device A (5), and the water absorption device A (6); S3: Start the primary subsystem circulation pump (3) to pump the raw gas in the raw gas tank (2) into the hydrogen isotope absorption device (4), and after purification in the hydrogen isotope absorption device (4), send it to the online chromatograph (22) to analyze the hydrogen isotope and other impurity contents; S4: When the hydrogen isotope and other impurity contents in the hydrogen isotope absorption device (4) analyzed by the online chromatograph (22) are less than or equal to 10 ppm, the introduction of the raw gas into the hydrogen isotope absorption device (4) is stopped, and the raw gas in the raw gas tank (2) is passed through the catalytic oxidation device (5) of the primary subsystem, then through the water absorption device (6), and then through the high-range ionization chamber measurement cavity (1) to measure the radioactivity; S5: When the radioactivity measured by the high-range ionization chamber measurement chamber (1) is ≤10 9 Bq / m 3 , closing the catalytic oxidation device (5) and the water absorption device (6) of the first-level subsystem, and charging the gas purified by the first-level subsystem into the raw gas tank (9) of the second-level subsystem through the first-level subsystem circulation pump (3); S6: Start the vacuum pump group B (13) to evacuate the measuring chamber (8) of the mid-range ionization chamber, the catalytic oxidation device B (11), and the water absorption device B (12); send the raw gas in the secondary subsystem raw gas tank (9) to the catalytic oxidation device B (11) through the circulation pump B (10), and then send it to the measuring chamber (8) of the mid-range ionization chamber to measure the radioactivity after passing through the water absorption device B (12); when the radioactivity is ≤10 7 Bq / m 3 When the catalytic oxidation device B (11) and the water absorption device B (12) are closed, the gas purified by the secondary subsystem is charged into the raw gas tank (15) of the tertiary subsystem; S7: Start the vacuum pump group C (20) to evacuate the low-range ionization chamber measurement chamber (14), the catalytic oxidation device C (17), the water absorption device C (18), and the low-temperature adsorption device (19); send the raw gas in the tertiary subsystem raw gas tank (15) to the catalytic oxidation device C (17) through the circulation pump C (16), and then send it to the low-range ionization chamber measurement chamber (14) through the water absorption device C (18) to measure the radioactivity. When the radioactivity is ≤10 5 Bq / m 3 When the catalytic oxidation device C (17) and the water absorption device C (18) are closed, the raw gas is allowed to enter the low-temperature adsorption device (19); S8: Analyze the hydrogen isotopes and other impurities and radioactive activities in the low-temperature adsorption device (19) through the online chromatograph (22) and the low-range ionization chamber measuring cavity (14); after reaching the technical indicators, close the low-temperature adsorption device (19), the online chromatograph (22) and the low-range ionization chamber measuring cavity (14), and allow the raw material gas to be filled into the product tank (21).

8. The method for removing tritium and other impurities from helium-3 gas according to claim 7, characterized in that: In the S1 and S2, the vacuum is evacuated to a vacuum degree of <20Pa; in the S6, the vacuum is evacuated to a vacuum degree of ≤1Pa.

9. The method for removing tritium and other impurities from helium-3 gas according to claim 7, characterized in that: In S5, when the radioactivity measured by the high-range ionization chamber measurement chamber (1) is greater than 10 9 Bq / m 3 When the raw gas continues to circulate in the primary subsystem; in said S6, when the radioactivity measured by the high-range ionization chamber measurement chamber (1) is greater than 10 7 Bq / m 3 At the same time, the raw gas continues to circulate in the second stage.

10. The method for removing tritium and other impurities from helium-3 gas according to claim 7, characterized in that: In S8, the technical indicators are: helium-3 gas purity ≥ 99.999%, radioactivity ≤ 10 5 Bq / m 3 .

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