Device and method for separating and purifying krypton-85 in nuclear facility gaseous effluent and environment

Abstract

The invention provides a device and a method for separating and purifying krypton-85 in nuclear facility gaseous effluent and environment, and belongs to the technical field of krypton-85 purification determination, the device comprises an extraction and recovery system communicated with a gas inlet system and a separation, purification and freezing collection system communicated with the extraction and recovery system; the extraction and recovery system comprises a particle filter and a 4A molecular sieve column; an inlet of the particle filter is communicated with an outlet of the air inlet system; an inlet of the 4A molecular sieve column is communicated with an outlet of the particle filter; the separating, purifying, freezing and collecting system comprises a krypton selective adsorption column of which the inlet is communicated with the outlet of the 4A molecular sieve column, and a chromatographic column of which the inlet is communicated with the outlet of the krypton selective adsorption column; and the outlet of the chromatographic column is communicated with the inlet of the krypton automatic packaging system. The separation and purification device for the nuclear facility gaseous effluent and the krypton-85 in the environment and the separation and purification method of the separation and purification device are low in energy, efficient and capable of being carried out on line.

Description

Technical Field

[0001] This invention relates to the field of krypton-85 purification and determination technology, and particularly to a krypton-85 separation and purification device and method in gaseous effluents and the environment from nuclear facilities. Background Technology

[0002] 85 Kr is a beta radionuclide with a half-life of 10.752 ± 0.023 years. Its beta rays have a maximum energy of 687 keV, and it emits gamma rays with an energy of 514 keV upon decay. Its branching ratio is only 0.435%. Kr is released into the environment from the nuclear fuel cycle. 85 Kr is much larger than that produced by nature. 85 Kr quantity. In the nuclear fuel cycle, Kr is released due to damage and defects in fuel elements within the reactor. 85 Kr accounts for less than 1%, the vast majority 85 Kr is released into the environment during spent fuel processing. By the end of 2009, human activities had cumulatively released Kr into the atmosphere. 85 Kr activity reached 5500 PBq. Therefore, Kr activity must be monitored in effluents from nuclear power plants and other nuclear facilities, as well as in environmental impact assessments. 85 Kr paid attention to this.

[0003] Currently, my country's nuclear power plants are managing gaseous effluents... 85 Kr was analyzed using gamma spectroscopy, but its detection limit was only 10⁵ Bq / m³. 3 The magnitude cannot be accurately given. 85 The analytical method urgently needs improvement to determine the actual emissions of Kr and assess its public radiation dose. Because... 85 The β-rays emitted during Kr decay have a high branching ratio, and liquid scintillation spectrometers have high detection efficiency for β-rays. Therefore, liquid scintillation measurement can be used to reduce the branching ratio of β-rays. 85 The detection limit for Kr analysis is limited because the abundance of Kr-85 in air or nuclear power plant air is extremely low, making direct measurement using liquid scintillation impossible. This necessitates the detection of Kr in the sample. 85 Kr is separated and purified before measurement. After separation and purification, β-rays can also be measured using a proportional counter. The complexity of the gas composition and... 85 The low level of Kr made sample purification difficult. 85 The challenges of Kr analysis lie in obtaining measurable Kr gas samples, which require separation and purification, including dehydration, removal of CO2, O2, and N2, followed by absorption by a scintillation liquid and measurement on a liquid scintillation spectrometer.

[0004] Currently, activated carbon is commonly used as the adsorbent in the adsorption process, which necessitates operation at a low temperature of -196℃. 85Adsorption of Kr is energy-intensive. Furthermore, the current practice of using liquid nitrogen as a refrigerant prevents separation and purification equipment from being used for sampling and purification in the field. Additionally, current methods typically involve collecting and fixing silica gel at liquid nitrogen temperatures. 85 Kr has a lower yield.

[0005] Therefore, there is an urgent need for a low-energy, high-efficiency, online separation and purification device and method for krypton-85 in gaseous effluents and the environment from nuclear facilities. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a low-energy, high-efficiency, online separation and purification device and method for gaseous effluents and environment of nuclear facilities.

[0007] To solve the above-mentioned technical problems, the present invention provides a krypton-85 separation and purification device for gaseous effluents and the environment of nuclear facilities, including an extraction and recovery system connected to the gas inlet system and a separation, purification, freezing and collection system connected to the extraction and recovery system. The extraction and recovery system includes a particulate filter whose inlet is connected to the outlet of the air intake system and a 4A molecular sieve column whose inlet is connected to the outlet of the particulate filter. The separation, purification, and cryogenic collection system includes a krypton-selective adsorption column whose inlet is connected to the outlet of the 4A molecular sieve column, and a chromatographic column whose inlet is connected to the outlet of the krypton-selective adsorption column. The outlet of the chromatographic column is connected to the inlet of the krypton automated packaging system.

[0008] Furthermore, a molecular sieve adsorption tube is provided between the krypton selective adsorption column and the chromatographic column, with the inlet of the molecular sieve adsorption tube connected to the outlet of the krypton selective adsorption column and the outlet of the molecular sieve adsorption tube connected to the inlet of the chromatographic column.

[0009] Furthermore, the extraction and recovery system and the separation, purification, freezing, and collection system are respectively connected to the refrigeration system, the regeneration system, and the automatic control system, and the krypton automatic packaging system is connected to the automatic control system.

[0010] Furthermore, the refrigeration system uses refrigerant refrigeration, and the krypton automatic packaging system is a krypton packaging bottle.

[0011] Furthermore, the solid particles in the particulate filter are metal ceramics, and the filling material in the A molecular sieve column is silicon aluminum oxide.

[0012] This invention also provides a method for separating and purifying krypton-85 from gaseous effluents and the environment of nuclear facilities, comprising the following steps: Pass a gas sample from the intake system into the particulate filter; The gas sample obtained after passing through the particle filter is passed into a 4A molecular sieve column; The gas sample obtained after passing through the 4A molecular sieve column was passed into the krypton selective adsorption column. The gas sample obtained after passing through the krypton selective adsorption column is passed into the chromatographic column through a molecular sieve adsorption tube to achieve the purification of krypton-85. Purified krypton-85 was immobilized in a solid porous material and then encapsulated in a krypton encapsulation bottle for liquid scintillation determination.

[0013] Furthermore, the air intake system is a sample container for holding gaseous effluent samples from a nuclear facility or an air compressor for extracting ambient air samples.

[0014] Furthermore, the gas injection rate in the sample container is no greater than 1 L / min, and the rated flow rate of the air compressor is no greater than 10 L / min.

[0015] Furthermore, when the gas sample obtained through the 4A molecular sieve column is passed into the krypton selective adsorption column, the temperature of the krypton selective adsorption column is controlled at -50℃ to -100℃ for krypton adsorption. After adsorbing krypton, the krypton selective adsorption column is then heated to 40℃ to release krypton.

[0016] Furthermore, when the gas sample obtained by the krypton selective adsorption column is introduced into the chromatographic column, the temperature of the chromatographic column is controlled at 20℃~40℃.

[0017] This invention provides a device and method for separating and purifying krypton-85 from gaseous effluents of nuclear facilities and the environment. The gaseous effluent sample from the nuclear facility or ambient air sample is sequentially passed through a particulate filter, a 4A molecular sieve column, a krypton-selective adsorption column, and a chromatographic column. After being immobilized by a solid porous material, it is sealed in a krypton-encapsulated bottle for liquid scintillation determination. This process utilizes krypton-selective adsorbents and novel krypton-immobilized adsorbents such as activated carbon, molecular sieves, MOF materials, and COF materials, enabling efficient separation and purification of krypton-85 in the gaseous sample.

[0018] Furthermore, the present invention provides a krypton-85 separation and purification device and method for gaseous effluents and the environment of nuclear facilities, which can monitor the krypton peak value in real time through a thermal conductivity detector (TCD) of gas chromatography, thereby realizing the separation and purification of krypton-85 in gaseous effluents and the environment of nuclear facilities and achieving online analysis of krypton gas.

[0019] Meanwhile, the present invention provides a krypton-85 separation and purification device and method in gaseous effluents and the environment of nuclear facilities. Compared with the traditional liquid nitrogen refrigeration method, which requires adsorption of krypton-85 at a low temperature of -196℃ and takes 12 to 24 hours, the refrigeration system of the present invention uses refrigerant refrigeration and can complete the adsorption of krypton-85 in about 6 hours at a temperature of -120℃. It not only has a relatively high effective adsorption temperature, which can save energy consumption, but also has a relatively short adsorption process time, making it energy-saving and efficient. Attached Figure Description

[0020] Figure 1 A flowchart illustrating the structure of a device and method for separating and purifying krypton-85 from gaseous effluents and the environment of a nuclear facility, provided as an embodiment of the present invention. Detailed Implementation

[0021] See Figure 1 The present invention provides a krypton-85 separation and purification device for gaseous effluents from nuclear facilities and the environment, comprising an extraction and recovery system connected to an inlet system and a separation, purification, cryogenic collection system connected to the extraction and recovery system.

[0022] The extraction and recovery system includes a particulate filter whose inlet is connected to the outlet of the air intake system and a 4A molecular sieve column whose inlet is connected to the outlet of the particulate filter.

[0023] The separation, purification, and cryogenic collection system includes a krypton-selective adsorption column whose inlet is connected to the outlet of the 4A molecular sieve column, and a chromatographic column whose inlet is connected to the outlet of the krypton-selective adsorption column.

[0024] The outlet of the chromatographic column is connected to the inlet of the krypton automated packaging system.

[0025] The solid particles in the particulate filter are made of metal ceramic and are used to remove aerosols from the gas sample entering the particulate filter. The packing material in the A molecular sieve column is silicon aluminum oxide and is used to remove moisture, nitrogen oxides, carbon dioxide, and other gases from the gas sample entering the A molecular sieve column.

[0026] A molecular sieve adsorption tube is installed between the krypton selective adsorption column and the chromatographic column. This serves as a buffer, controlling the rate at which the gas from the krypton selective adsorption column enters the chromatographic column and ensuring the purity of the krypton. Specifically, the inlet of the molecular sieve adsorption tube is connected to the outlet of the krypton selective adsorption column, and the outlet of the molecular sieve adsorption tube is connected to the inlet of the chromatographic column.

[0027] The extraction and recovery system and the separation, purification, freezing and collection system are respectively connected to the refrigeration system, the regeneration system and the automatic control system, and the krypton automatic packaging system is connected to the automatic control system.

[0028] The refrigeration system uses refrigerant, specifically R14 and / or FC-14.

[0029] This invention provides a device and method for separating and purifying krypton-85 from gaseous effluents and the environment of nuclear facilities. Through an automatic control system, the extraction and recovery system and the separation, purification, and cryogenic collection system are intelligently controlled, making the separation and purification of krypton-85 from gaseous effluents and the environment of nuclear facilities more intelligent, convenient, simple, and efficient. Furthermore, the extraction and recovery system and the separation, purification, and cryogenic collection system are each connected to a refrigeration system for cooling. Compared to traditional liquid nitrogen refrigeration, which requires krypton-85 adsorption at a low temperature of -196°C and 12–24 hours, the refrigeration system of this invention uses R14 and / or FC-14 as the refrigerant, requiring only about 6 hours of peak elution at -120°C to complete krypton-85 adsorption. This not only results in a relatively high effective adsorption temperature, saving energy, but also a relatively short adsorption process time, making it energy-efficient and highly effective.

[0030] Among them, the krypton automated packaging system is a krypton packaging bottle.

[0031] The solid particles in the particulate filter are metal ceramics, and the filling material in the A molecular sieve column is silicon aluminum oxide.

[0032] This invention provides a method for separating and purifying krypton-85 from gaseous effluents and the environment of nuclear facilities, comprising the following steps: Step 1) Pass the gas sample from the intake system into the particulate filter, where the particulate filter is filled with metal-ceramic particles to remove aerosols from the gas sample.

[0033] The air intake system is either a sample container for holding gaseous effluent samples from a nuclear facility or an air compressor for extracting ambient air samples.

[0034] In order to control the rate at which the gas sample enters the particle filter, 4A molecular sieve column, krypton selective adsorption column and chromatographic column, so as to more fully and effectively separate and purify krypton-85 in the gas sample, the gas injection flow rate in the sample tank shall not exceed 1L / min, and the rated flow rate of the air compressor shall not exceed 10L / min.

[0035] Step 2) Pass the gas sample obtained through the particle filter into the 4A molecular sieve column. The 4A molecular sieve column is filled with silicon aluminum oxide, which can remove impurities such as moisture, nitrogen oxides, and carbon dioxide from the gas sample.

[0036] Step 3) Pass the gas sample obtained through the 4A molecular sieve column into the krypton selective adsorption column.

[0037] In the process of passing the gas sample obtained through the 4A molecular sieve column into the krypton selective adsorption column, the temperature of the krypton selective adsorption column is controlled at -50℃ to -100℃ for krypton adsorption. After adsorbing krypton, the krypton selective adsorption column is then heated to 40℃ to release krypton.

[0038] To further adsorb and purify krypton, the krypton-selective adsorption column after adsorption is heated to release krypton, which can then be passed into a second krypton-selective adsorption column at -50℃ to -100℃. The second krypton-selective adsorption column after adsorption is heated to 40℃ to release krypton gas with higher purity.

[0039] Step 4) Pass the gas sample obtained from the krypton selective adsorption column through a molecular sieve adsorption tube into the chromatographic column to purify krypton-85; When the gas sample obtained by the krypton selective adsorption column is introduced into the chromatographic column, the temperature of the chromatographic column is controlled between 20℃ and 40℃.

[0040] Step 5) The purified krypton-85 is immobilized in a solid porous material and then encapsulated in a krypton encapsulation bottle for liquid scintillation determination.

[0041] In this process, the gas is adsorbed by a solid adsorbent, added to a liquid scintillation solution, and then sealed in a krypton bottle for subsequent liquid scintillation determination.

[0042] Among them, solid porous materials include activated carbon, molecular sieves, MOF materials, COF materials, etc.

[0043] This invention provides a device and method for separating and purifying krypton-85 in gaseous effluents from nuclear facilities and the environment. The gaseous effluent sample from the nuclear facility or ambient air sample is sequentially passed through a particulate filter, a 4A molecular sieve column, a krypton-selective adsorption column, and a chromatographic column. After being immobilized by a solid porous material, it is sealed in a krypton encapsulation bottle for liquid scintillation determination. This process utilizes novel krypton-selective adsorbents and novel krypton immobilization adsorbents such as activated carbon, molecular sieves, MOF materials, and COF materials, enabling efficient separation and purification of krypton-85 in the gaseous sample.

[0044] Furthermore, the present invention provides a krypton-85 separation and purification device and method for gaseous effluents and the environment of nuclear facilities, which can monitor the krypton peak value in real time through TCD, realize the separation and purification of krypton-85 in gaseous effluents and the environment of nuclear facilities, and realize online analysis of krypton gas.

[0045] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be noted that these descriptions are only for further illustrating the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention.

[0046] Example 1 like Figure 1As shown in the illustration, an embodiment of the present invention provides a krypton-85 separation and purification device for gaseous effluents and the environment from a nuclear facility, comprising an extraction and recovery system connected to an inlet system and a separation, purification, and cryogenic collection system connected to the extraction and recovery system. Specifically, the extraction and recovery system includes a particulate filter whose inlet is connected to the outlet of the inlet system and a 4A molecular sieve column whose inlet is connected to the outlet of the particulate filter. The solid particles in the particulate filter are metal ceramics, used to remove aerosols from the gas sample entering the particulate filter. The filling material in the A molecular sieve column is silicon aluminate oxide, used to remove moisture, nitrogen oxides, carbon dioxide, and other gases from the gas sample entering the A molecular sieve column.

[0047] Specifically, the separation, purification, and cryogenic collection system includes a krypton-selective adsorption column whose inlet is connected to the outlet of the 4A molecular sieve column, and a chromatographic column whose inlet is connected to the outlet of the krypton-selective adsorption column.

[0048] A molecular sieve adsorption tube is installed between the krypton selective adsorption column and the chromatographic column to act as a buffer, controlling the rate at which the gas from the krypton selective adsorption column enters the chromatographic column and ensuring the purity of krypton. Specifically, the inlet of the molecular sieve adsorption tube is connected to the outlet of the krypton selective adsorption column, and the outlet of the molecular sieve adsorption tube is connected to the inlet of the chromatographic column. After the gas sample is purified by the chromatographic column, the purified krypton-85 is immobilized in a solid porous material such as activated carbon, molecular sieve, MOF material, or COF material, and then sealed in a krypton encapsulation bottle for liquid scintillation determination.

[0049] The extraction and recovery system and the separation, purification, freezing and collection system are respectively connected to the refrigeration system, the regeneration system and the automatic control system, and the krypton automatic packaging system is connected to the automatic control system.

[0050] The refrigeration system uses refrigerant, specifically R14 and / or FC-14.

[0051] Compared to traditional liquid nitrogen refrigeration, which requires adsorption of krypton-85 at a low temperature of -196℃ and takes 12 to 24 hours, the refrigeration system of this invention uses R14 or / and FC-14 as the refrigerant. It only needs to reach peak temperature of -120℃ for about 6 hours to complete the adsorption of krypton-85. Not only is the effective adsorption temperature relatively high, which can save energy consumption, but the adsorption process time is also relatively short, making it energy-saving and efficient.

[0052] Example 2 Using the apparatus of Example 1, in the environment 85 Separation, purification, and collection of Kr.

[0053] 1) Extraction and recycling An air compressor is used to pass the gas through a particulate filter at a flow rate not exceeding 10 L / min to remove aerosols. The gas then passes through a 4A molecular sieve to remove CO2 and H2O. Next, the gas is passed through a krypton selective adsorption column (-80℃), where the temperature is slowly increased to remove O2 and N2. When the temperature reaches 45℃... 85 Kr releases gas and carries it into the chromatographic column via a carrier gas.

[0054] 2) Separation and purification The gas is separated and purified by passing it through a chromatographic column at room temperature. 85 Kr.

[0055] 3) Krypton encapsulation The separated and purified gas is adsorbed by a solid adsorbent, and then encapsulated using an automated encapsulation system after the addition of liquid flash liquid.

[0056] The entire process takes approximately 3 hours, and the krypton recovery rate is approximately 80%.

[0057] Example 3 Using the apparatus of Example 1, in the environment 85 Separation, purification, and collection of Kr.

[0058] 1) Extraction and recycling An air compressor was used to pass the gas through a 4A molecular sieve at a flow rate not exceeding 5 L / min to remove CO2 and H2O. The gas was then passed through a krypton selective adsorption column (-80℃), where the temperature was slowly increased to remove O2 and N2. When the temperature reached 45℃... 85 Kr releases gas and carries it into the chromatographic column via a carrier gas.

[0059] 2) Separation and purification The gas is separated and purified by passing it through a chromatographic column at room temperature. 85 Kr.

[0060] 3) Krypton encapsulation The separated and purified gas is adsorbed by a solid adsorbent, and then encapsulated using an automated encapsulation system after the addition of liquid flash liquid.

[0061] The entire process takes approximately 5 hours, and the krypton recovery rate is approximately 85%.

[0062] Example 4 Using the apparatus of Example 1, to process gaseous effluent from nuclear facilities 85 Separation, purification, and collection of Kr.

[0063] 1) Sample collection Krypton was collected from radioactive gaseous effluents from nuclear facilities using 5L gas sampling cylinders.

[0064] 2) Extraction and recycling The gaseous effluent is carried by a carrier gas at a flow rate of 0.5 L / min through a 4A molecular sieve to remove CO2 and H2O. The gas is then passed through a krypton selective adsorption column (-80℃), where O2 and N2 are removed by slow heating. When the temperature reaches 45℃... 85 Kr releases gas and carries it into the chromatographic column via a carrier gas.

[0065] 3) Separation and purification The gas is separated and purified by passing it through a chromatographic column at room temperature. 85 Kr.

[0066] 4) Krypton encapsulation The separated and purified gas is adsorbed by a solid adsorbent, and then encapsulated using an automated encapsulation system after the addition of liquid flash liquid.

[0067] The entire process takes approximately 4 hours, and the krypton recovery rate is approximately 90%.

[0068] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A device for separating and purifying krypton-85 from gaseous effluents and the environment from a nuclear facility, characterized in that, It includes an extraction and recovery system connected to the air intake system and a separation, purification, freezing, and collection system connected to the extraction and recovery system; The extraction and recovery system includes a particulate filter whose inlet is connected to the outlet of the air intake system and a 4A molecular sieve column whose inlet is connected to the outlet of the particulate filter. The separation, purification, and cryogenic collection system includes a krypton-selective adsorption column whose inlet is connected to the outlet of the 4A molecular sieve column, and a chromatographic column whose inlet is connected to the outlet of the krypton-selective adsorption column. The outlet of the chromatographic column is connected to the inlet of the krypton automated packaging system.

2. The krypton-85 separation and purification device for gaseous effluents and the environment from nuclear facilities according to claim 1, characterized in that, A molecular sieve adsorption tube is provided between the krypton selective adsorption column and the chromatographic column. The inlet of the molecular sieve adsorption tube is connected to the outlet of the krypton selective adsorption column, and the outlet of the molecular sieve adsorption tube is connected to the inlet of the chromatographic column.

3. The apparatus for separating and purifying krypton-85 from gaseous effluents and the environment of nuclear facilities according to claim 1, characterized in that, The extraction and recovery system and the separation, purification, freezing and collection system are respectively connected to the refrigeration system, the regeneration system and the automatic control system, and the krypton automatic packaging system is connected to the automatic control system.

4. The krypton-85 separation and purification device for gaseous effluents and the environment from nuclear facilities according to claim 3, characterized in that, The refrigeration system uses refrigerant refrigeration, and the krypton automatic packaging system is a krypton packaging bottle.

5. The apparatus for separating and purifying krypton-85 from gaseous effluents and the environment of nuclear facilities according to claim 3, characterized in that, The solid particles in the particulate filter are metal ceramics, and the filling material in the A molecular sieve column is silicon aluminum oxide.

6. A method for separating and purifying krypton-85 from gaseous effluents and the environment of a nuclear facility, characterized in that, Includes the following steps: Pass a gas sample from the intake system into the particulate filter; The gas sample obtained after passing through the particle filter is passed into a 4A molecular sieve column; The gas sample obtained after passing through the 4A molecular sieve column was passed into the krypton selective adsorption column. The gas sample obtained after passing through the krypton selective adsorption column is passed into the chromatographic column through a molecular sieve adsorption tube to achieve the purification of krypton-85. Purified krypton-85 was immobilized in a solid porous material and then encapsulated in a krypton encapsulation bottle for liquid scintillation determination.

7. The method for separating and purifying krypton-85 from gaseous effluents and the environment of nuclear facilities according to claim 6, characterized in that, The air intake system is a sample container for holding gaseous effluent samples from a nuclear facility or an air compressor for extracting ambient air samples.

8. The method for separating and purifying krypton-85 from gaseous effluents and the environment of nuclear facilities according to claim 7, characterized in that, The gas injection rate in the sample container shall not exceed 1 L / min, and the rated flow rate of the air compressor shall not exceed 10 L / min.

9. The method for separating and purifying krypton-85 from gaseous effluents and the environment of nuclear facilities according to claim 6, characterized in that, When the gas sample obtained through the 4A molecular sieve column is passed into the krypton selective adsorption column, the temperature of the krypton selective adsorption column is controlled at -50℃ to -100℃ for krypton adsorption. After adsorbing krypton, the krypton selective adsorption column is then heated to 40℃ to release krypton.

10. The method for separating and purifying krypton-85 from gaseous effluents and the environment of nuclear facilities according to claim 9, characterized in that, When the gas sample obtained by the krypton selective adsorption column is passed into the chromatographic column, the temperature of the chromatographic column is controlled at 20℃~40℃.

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