Automatic measurement system for tritium in radioactive gaseous effluent

Abstract

The utility model provides a kind of automatic measurement system of tritium in radioactive gaseous effluent, including tritium-containing gas sampling unit, for tritium-containing gas is dissolved in sampling liquid, tritium-containing liquid is made, and is mixed uniformly;Tritium-containing liquid sample preparation unit is used to proportionally fill the measuring bottle with tritium-containing liquid and scintillation liquid;Sample sending operation unit is used to control the moving position of measuring bottle;Automatic measurement unit is used to measure the scintillation spectrum of the measuring bottle put in it, and calculate the activity of tritium after measurement.The utility model can realize the automatic sampling, automatic sample preparation, automatic sample sending and automatic measurement of tritium in air, realize the automatic online monitoring of gaseous tritium, which is beneficial to improve monitoring efficiency;It can realize unmanned, long-time automatic sampling and measurement of tritium in atmospheric environment and gaseous effluent, realize online monitoring of low-concentration tritium in air;It can be quickly started when nuclear radiation accident occurs, and improve the response speed of nuclear emergency monitoring.

Description

Technical Field

[0001] This utility model relates to the field of environmental radiation measurement technology, and in particular to an automatic measurement system for tritium in radioactive gaseous effluents. Background Technology

[0002] tritium( 3 Tritium (H) is a radioactive element produced and released during the production process of nuclear power plants and nuclear fuel processing plants. It decays, releasing beta rays with a maximum energy of 18.6 keV and an average energy of 5.7 keV. Due to its low energy, beta rays have a short range in air, making measurement difficult. Current tritium measurement techniques mainly include:

[0003] (1) Ionization Chamber Method: A sampled gas containing gaseous tritium is passed into a tritium ionization chamber. The β particles produced by tritium decay interact with the medium within the chamber, causing ionization of the medium molecules and generating electron-ion pairs. A voltage is applied between the electrodes of the ionization chamber to create an electric field. Under the influence of this electric field, the generated positive and negative ions drift towards the negative and positive electrodes, respectively, forming an ionization current. The magnitude of the ionization current is proportional to the tritium activity. By measuring the magnitude of the ionization current, the tritium activity can be determined. Because background ionizing radiation exists in the air, a compensation ionization chamber is needed to eliminate the influence of background ionizing radiation and provide real-time monitoring capabilities.

[0004] (2) “Sampling + liquid scintillation measurement” method: First, gaseous tritium is converted into tritium water by catalytic oxidation. Then, tritium water in the air is collected by bubbling, condensation, freezing and adsorption methods to form a tritium-containing liquid sample. Finally, the sample is mixed with scintillation liquid and sent to an automatic measurement unit to measure the tritium activity. Finally, the concentration of tritium in the air is calculated based on the volume of collected air. This method has a low measurement limit, but it requires offline sampling, sample preparation and measurement, which leads to monitoring lag and cannot meet the requirements of online rapid response.

[0005] "Sampling + liquid flash measurement" is a common method for measuring low-level tritium concentrations in the air. The technologies involved mainly include tritium catalytic oxidation technology, tritized water collection technology, and tritium-containing liquid measurement technology.

[0006] Tritium catalytic oxidation technology uses a catalyst to react gaseous tritium (HT, T2) with oxygen at high temperatures to generate water tritide (HTO), making it easier for tritium in the air to be adsorbed and treated. The catalysts used are mainly metal oxide catalysts (such as copper oxide, cerium oxide, etc.) and noble metal catalysts (such as platinum, palladium, etc.).

[0007] Tritium water can be collected through various methods, including bubbling, condensation, freezing, and adsorption. Bubbling involves passing air through a collection system containing water or other non-aqueous solvents, allowing the tritium water vapor to be absorbed by the solvent, thus capturing the tritium water. Condensation uses a dehumidifier as a collector; airborne tritium (HTO) is drawn into the dehumidifier and condensed into liquid water, which is then collected directly from the dehumidifier's outlet. Freezing uses a cold trap (semiconductor, liquid nitrogen) as a collector; the sampled air passes through a cold trap cooled below its freezing point, freezing the HTO in the collection container. After sampling, a heating system melts the captured frozen water before collection. Drying uses a desiccant as a collector; HTO in the air is adsorbed as it passes through a desiccant adsorption column. Commonly used desiccants include silica gel, molecular sieves, anhydrous calcium sulfate, and activated alumina. The adsorbed HTO forms a hydrated compound with the adsorbent, requiring distillation or heating to desorb it before it can be used as a sample for measurement.

[0008] The basic principle of liquid scintillator spectrometry is based on the fluorescence effect generated by the interaction of radiation and matter. When radioactive particles emitted by a radioactive isotope collide with solvent molecules in the scintillator fluid, the solvent molecules absorb the radiation energy and transition to an excited state. Subsequently, during their return to the ground state, they transfer energy to the scintillator molecules. As the scintillator molecules return from the excited state to the ground state, they emit fluorescent photons. These fluorescent photons are received by a photomultiplier tube and converted into photoelectrons. After multiplication, they are collected at the anode and ultimately output as pulse signals. By coinciding, amplifying, analyzing, and displaying these pulse signals, the intensity and magnitude of radioactivity in the sample liquid can be reflected.

[0009] However, while ionization chambers can measure tritium concentration in the air in real time, their detection limit is relatively high (≥3.7 × 10⁻⁶). 4 Bq / m 3 This cannot meet the requirement of low concentration (≤1×10⁻⁶). 3 Bq / m 3 It has monitoring needs and is susceptible to interference from radon and cosmic rays.

[0010] While the "sampling + measurement" method can collect tritium in the air over a long period of time and has a low detection limit, the samples need to be collected, prepared, and sent to a liquid scintillation spectrometer for measurement. This method has a low degree of automation and cannot achieve online monitoring. Utility Model Content

[0011] The purpose of this invention is to provide an automatic tritium measurement system in radioactive gaseous effluents, which solves the problem that monitoring low concentrations of tritium in the air requires manual sampling, sample preparation, and measurement, which is labor-intensive and cannot achieve online monitoring.

[0012] This invention provides an automatic tritium measurement system for radioactive gaseous effluents, comprising: a tritium-containing gas sampling unit for dissolving tritium-containing gas in a sampling liquid to prepare a tritium-containing liquid and mixing it uniformly; a tritium-containing liquid sample preparation unit for adding the tritium-containing liquid and scintillation fluid in a specified ratio to a measurement bottle; a sample delivery operation unit for controlling the movement position of the measurement bottle; and an automatic measurement unit for measuring the scintillation spectrum of the measurement bottle placed therein and calculating the tritium activity after measurement.

[0013] Furthermore, the tritium-containing gas sampling unit includes a tritium catalytic oxidation component, which is used to convert gaseous tritium into tritized water.

[0014] Furthermore, the tritium catalytic oxidation assembly includes a gas pump, a flow meter, and a catalytic oxidation furnace connected in sequence.

[0015] Furthermore, the tritium-containing gas sampling unit includes a tritium enrichment component, which is used to dissolve tritized water in the sampling liquid.

[0016] Furthermore, the tritium enrichment assembly includes a sampling bottle and a bubbler, the bubbler being disposed inside the sampling bottle.

[0017] Furthermore, the tritium-containing liquid sample preparation unit includes a water pump and a pure water tank, and the pure water tank is connected to the sampling bottle through the water pump.

[0018] Furthermore, the tritium-containing liquid sample preparation unit includes a first peristaltic pump, a second peristaltic pump, and a scintillation liquid storage tank. The sampling bottle is connected to the measurement bottle through the first peristaltic pump, and the scintillation liquid storage tank is connected to the measurement bottle through the second peristaltic pump.

[0019] Furthermore, the sample delivery unit includes a guide rail, an operating gripper, and a rotating gripper, with the operating gripper movably mounted on the guide rail. Within the operating range of the guide rail and the operating gripper, there are a measurement bottle storage tank, a scintillation liquid filling port, a sampling liquid filling port, an automatic measurement unit inlet, and a measurement bottle collection box. The operating range of the rotating gripper is located within the operating range of the operating gripper, and the rotating gripper is used to unscrew and tighten the cap of the measurement bottle.

[0020] Furthermore, the automatic measurement unit is equipped with a measurement bottle support plate and a light-shielding cover. After the measurement bottle enters the sample inlet of the automatic measurement unit, the automatic measurement unit releases the measurement bottle support plate to allow the measurement bottle to enter the measurement station. Then, the light-shielding cover is closed, and a photomultiplier tube is used to measure the scintillation spectrum. After the measurement is completed, the activity of tritium is calculated.

[0021] The technical solution of this utility model enables the automatic sampling of tritium in the air to form a tritium-containing liquid through a tritium-containing gas sampling unit, which then mixes the liquid evenly. A tritium-containing liquid sample preparation unit automatically prepares the sample, and a sample delivery unit automatically delivers the prepared sample vial to an automatic measurement unit for measurement. Therefore, this utility model achieves automatic sampling, sample preparation, sample delivery, and measurement of tritium in the air, eliminating reliance on manual operations for sample preparation and delivery. It enables automatic online monitoring of gaseous tritium, improving monitoring efficiency. It allows for unattended, long-term, fully automatic sampling and measurement of tritium in the atmospheric environment and gaseous effluents, achieving online monitoring of low concentrations of tritium in the air. Furthermore, it can be quickly activated in the event of a nuclear radiation accident, improving the response speed of nuclear emergency monitoring. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the overall system of this utility model;

[0024] Explanation of reference numerals in the attached figures:

[0025] 1-Air pump; 2-Flow meter; 3-Catalytic oxidation furnace; 4-First sampling bottle; 5-Second sampling bottle; 6-Bubbler; 7-Water pump; 8-Pure water tank; 9-First solenoid valve; 10-Sampling liquid mixing tank; 11-Scintillation liquid storage tank; 12-First peristaltic pump; 13-Second peristaltic pump; 14-Second solenoid valve; 15-Guide rail; 16-Slider; 17-Extension arm; 18-Measuring bottle storage tank; 19-Measuring bottle; 20-Rotating gripper; 21-Operating gripper; 211-Measuring bottle gripping position; 212-Bottle cap operating position; 213-Scintillation liquid filling position; 214-Sampling liquid filling position; 215-Automatic measurement unit inlet; 216-Measuring bottle collection position; 22-Measuring bottle collection box; 23-Waste liquid tank; 24-Automatic measurement unit. Detailed Implementation

[0026] The technical solution of this utility model will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0027] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the system or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0029] Example 1

[0030] like Figure 1 As shown, this utility model provides an automatic tritium measurement system in radioactive gaseous effluents, comprising: a tritium-containing gas sampling unit, which dissolves tritium-containing gas in a sampling liquid to prepare a tritium-containing liquid, and mixes it uniformly through a sampling liquid mixing tank 10; a tritium-containing liquid sample preparation unit, which adds the tritium-containing liquid and scintillation fluid in a specific ratio to a measurement bottle 19; a sample delivery operation unit, which controls the movement position of the measurement bottle 19; and an automatic measurement unit 24, which measures the scintillation spectrum of the measurement bottle 19 placed therein and calculates the tritium activity after measurement.

[0031] Specifically, the tritium-containing gas sampling unit can automatically sample tritium from the air to prepare a tritium-containing liquid, which is then uniformly mixed in a sampling liquid mixing tank 10. The tritium-containing liquid sample preparation unit can automatically prepare the sample, and the sample delivery unit can automatically deliver the prepared sample to the liquid scintillation spectrometer 19 for automatic measurement. Thus, this invention enables automatic sampling, sample preparation, sample delivery, and measurement of tritium in the air, eliminating reliance on manual operations for sample preparation and delivery, achieving automatic online monitoring of gaseous tritium, and improving monitoring efficiency. It also enables unattended, long-term, fully automatic sampling and measurement of tritium in the atmospheric environment and gaseous effluents, achieving online monitoring of low concentrations of tritium in the air; and it can be quickly activated in the event of a nuclear radiation accident, improving the response speed of nuclear emergency monitoring.

[0032] Example 2

[0033] The tritium-containing gas sampling unit includes a tritium catalytic oxidation component, which converts gaseous tritium into tritized water. The tritium catalytic oxidation component includes a gas pump 1, a flow meter 2, and a catalytic oxidation furnace 3 connected in sequence. The tritium-containing gas sampling unit also includes a tritium enrichment component, which dissolves tritized water in the sampling liquid. The tritium enrichment component includes sampling bottles (4, 5) and a bubbler 6, which is disposed within the sampling bottles (4, 5).

[0034] Specifically, the gas pump 1 is used to deliver the gas to be measured into the system; the flow meter 2 is used to measure the gas flow rate; the catalytic oxidation furnace 3 is used to convert gaseous tritium (T2, HT) into tritized water; there are two sampling bottles, namely the first sampling bottle 4 and the second sampling bottle 5 connected in series along the tritized water path. The two sampling bottles (4, 5) are equipped with a bubbler 6. The gas passes through the bubbler 6 to dissolve the tritized water into the sampling liquid (pure water 8), thereby achieving the sampling and enrichment of tritium.

[0035] Example 3

[0036] The tritium-containing liquid sample preparation unit includes a water pump 7 and a pure water tank 8, which is connected to the sampling bottle (4, 5) via the water pump 7. The tritium-containing liquid sample preparation unit includes a first peristaltic pump 12, a second peristaltic pump 13, and a scintillation fluid storage tank 11. The sampling bottle (4, 5) is connected to the measuring bottle 19 via the first peristaltic pump 12, and the scintillation fluid storage tank 11 is connected to the measuring bottle 19 via the second peristaltic pump 13.

[0037] Specifically, water pump 7 is used to draw a certain amount of purified water 8 from purified water tank 8 and add it to the first sampling bottle 4 and the second sampling bottle 5 respectively. After sampling, a certain amount of purified water 8 is drawn from purified water tank 8 in 2-3 times to rinse the sampling bottles (4, 5). The first sampling bottle 4 and the second sampling bottle 5 are mixed through sampling liquid mixing tank 10 and controlled by the first solenoid valve 9. The first peristaltic pump 12 draws 8 ml of liquid from sampling bottles (4, 5) through sampling liquid mixing tank 10 and adds it to scintillation measurement bottle 19. The second peristaltic pump 13 is used to draw 12 ml of scintillation liquid from scintillation liquid storage tank 11 and add it to scintillation measurement bottle 19. The remaining mixed sampling liquid in sampling liquid mixing tank 10 is discharged into waste liquid tank 23 through pipeline and the second solenoid valve 14.

[0038] Example 4

[0039] The sample delivery unit includes a guide rail 15 and an operating gripper 21. The operating gripper 21 is mounted on an extension arm 17, which is movably mounted on the guide rail 15 via a slider 16. The linear guide rail 15 is driven by a motor screw mechanism. Within the operating range of the guide rail 15 and the operating gripper 21, there are a measuring bottle storage tank 18, a scintillation liquid filling port, a sampling liquid filling port, an automatic measuring unit inlet 215, and a measuring bottle collection box 22. The sample delivery unit also includes a rotating gripper 20, whose operating range is within the operating range of the operating gripper 21. The rotating gripper 20 is used to unscrew and tighten the cap of the measuring bottle 19.

[0040] Specifically, after tritium collection is completed, the operating gripper 21, driven by the linear guide rail 15, sequentially completes the following operations: gripping an empty measuring bottle 19 from the measuring bottle gripping position 211 below the measuring bottle storage tank 18; reaching the bottle cap operating position 212 (by rotating the gripper 20) to unscrew the bottle cap; reaching the scintillation liquid filling position 213 to fill the scintillation liquid; reaching the sampling liquid filling position 214 to fill the tritium-containing liquid; returning to the bottle cap operating position 212 (by rotating the gripper 20) to tighten the bottle cap; shaking the measuring bottle 19 (by operating the gripper 21); sending the measuring bottle 19 to the liquid scintillation spectrometer inlet; and releasing the gripper.

[0041] After the automatic measurement unit 24 completes the measurement, the operating gripper 21, driven by the linear guide rail 15, sequentially completes the operations of picking up the measurement bottle 19 from the sample inlet 215 of the automatic measurement unit, reaching the measurement bottle collection position 216 of the measurement bottle collection box 22, and releasing the gripper.

[0042] Example 5

[0043] The automatic measurement unit 24 is equipped with a support plate for the measurement bottle 19 and a light-shielding cover. After the measurement bottle 19 enters the sample inlet 215 of the automatic measurement unit, the automatic measurement unit 24 releases the support plate for the measurement bottle 19, allowing the measurement bottle 19 to enter the measurement station. Then, the light-shielding cover is closed, and the scintillation spectrum is measured using a photomultiplier tube. After the measurement is completed, the activity of tritium is calculated.

[0044] Specifically, the automatic measurement unit 24 uses an RLS400P liquid scintillation spectrometer with a measurement range of 1×10⁻⁶. 3 ~1×10 5 Bq / m 3 Detection efficiency ≥25%.

[0045] The measurement method of the automatic tritium measurement system in radioactive gaseous effluents of this utility model:

[0046] Tritium-containing air is collected by air pump 1 and sent to catalytic oxidation furnace 3. In catalytic oxidation furnace 3, gaseous tritium is converted into tritized water and further sent to sampling bottle. The gas in the sampling bottle is bubbled by bubbler 6 to dissolve the tritized water into the sampling liquid (pure water 8), thus achieving tritium sampling and enrichment. The first peristaltic pump 12 draws 8 ml of liquid from the sampling bottle and adds it to the scintillation measurement bottle 19; the second peristaltic pump 13 draws 12 ml of scintillation liquid from the scintillation liquid storage tank 11 and adds it to the scintillation measurement bottle 19. Driven by the linear guide rail 15, the operating gripper 21 picks up an empty measuring bottle 19 from below the measuring bottle storage tank 18, and carries the measuring bottle 19 to the cap operation position 212. The cap is then unscrewed by rotating the gripper 20, and the bottle is moved to the scintillation liquid filling position 213 to add scintillation liquid. Next, the bottle is moved to the sampling liquid filling position 214 to add tritium-containing liquid, and then back to the cap operation position 212. The cap is tightened by rotating the gripper 20, and the measuring bottle 19 is shaken to deliver it to the automatic measurement unit inlet 215. The gripper then releases the bottle, allowing it to fall into the automatic measurement unit 24. After the measuring bottle 19 enters the automatic measurement unit inlet 215, the scintillation spectrum is measured, and the tritium activity is calculated after the measurement. After the automatic measurement unit 24 completes the measurement, the operating gripper 21, driven by the linear guide rail 15, picks up the measuring bottle 19 from the automatic measurement unit inlet 215, and carries it to the measuring bottle collection box 22. The gripper then releases the bottle, allowing it to fall into the measuring bottle collection box 22.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. An automatic measurement system for tritium in radioactive gaseous effluents, characterized in that, include: A tritium-containing gas sampling unit is used to dissolve tritium-containing gas in a sampling liquid to prepare a tritium-containing liquid and mix it evenly. A tritium-containing liquid sample preparation unit is used to mix and add tritium-containing liquid and scintillation fluid into a measuring bottle; A sample delivery unit is used to control the movement position of the measuring bottle; An automatic measurement unit is used to measure the scintillation spectrum of a measurement bottle placed inside, and then calculate the activity of tritium. The tritium-containing gas sampling unit includes a tritium catalytic oxidation component, which is used to convert gaseous tritium into tritized water; the tritium catalytic oxidation component includes a gas pump, a flow meter and a catalytic oxidation furnace connected in sequence, which is used to convert gaseous tritium into tritized water; The tritium-containing gas sampling unit includes a tritium enrichment component, which is used to dissolve tritized water in the sampling liquid. The tritium enrichment component includes a sampling bottle and a bubbler. The bubbler is disposed inside the sampling bottle. The sampling bottles are a first sampling bottle and a second sampling bottle connected in series along the path of tritized water. The bubbler is installed in both sampling bottles, and the bubbler dissolves the tritized water in the sampling liquid.

2. The automatic tritium measurement system in radioactive gaseous effluents according to claim 1, characterized in that, The tritium-containing liquid sample preparation unit includes a water pump and a pure water tank, and the pure water tank is connected to the sampling bottle through the water pump.

3. The automatic tritium measurement system in radioactive gaseous effluents according to claim 2, characterized in that, The tritium-containing liquid sample preparation unit includes a first peristaltic pump, a second peristaltic pump, and a scintillation liquid storage tank. The sampling bottle is connected to the measurement bottle through the first peristaltic pump, and the scintillation liquid storage tank is connected to the measurement bottle through the second peristaltic pump.

4. The automatic tritium measurement system in radioactive gaseous effluents according to claim 3, characterized in that, The sample delivery unit includes a guide rail, an operating gripper, and a rotating gripper, wherein the operating gripper is movably mounted on the guide rail. Within the operating range of the guide rail and the operating gripper, there are a measuring bottle storage tank, a scintillation liquid filling port, a sampling liquid filling port, an automatic measuring unit inlet, and a measuring bottle collection box; The operating range of the rotating gripper is within the operating range of the operating jaw, and the rotating gripper is used to open and tighten the cap of the measuring bottle.

5. The automatic tritium measurement system in radioactive gaseous effluents according to claim 4, characterized in that, The automatic measurement unit is equipped with a measurement bottle support plate and a light-shielding cover. After the measurement bottle enters the sample inlet of the automatic measurement unit, the automatic measurement unit releases the measurement bottle support plate, allowing the measurement bottle to enter the measurement station. Then, the light-shielding cover is closed, and a photomultiplier tube is used to measure the scintillation spectrum. After the measurement is completed, the activity of tritium is calculated.

Images