Water radionuclide identification and alpha / beta total radioactivity on-line measurement device

Abstract

The invention discloses a water radionuclide identification and alpha / beta radioactivity total specific activity online measurement device, which comprises a water container, a water inlet and a water outlet which are communicated with the interior of the water container are arranged on the water container, and a scintillator optical fiber array detector is fixedly arranged in the water container; the water container is further provided with an anti-Compton gamma spectrometer, a shell of the water container is provided with a sealing channel for a power line and a signal line to penetrate through, and the scintillator optical fiber array detector and the anti-Compton gamma spectrometer are connected with the processor through the signal line. According to the device, the water container is arranged, the scintillator optical fiber array detector is arranged in the water container, the device can be connected into water flow, the scintillator optical fiber array detector directly gives the total specific activity of alpha / beta in water through pulse signal counting, and therefore online measurement of the total specific activity of alpha / beta radioactivity in water is achieved. Radionuclide identification is synchronously carried out on the water flow through the anti-Compton gamma spectrometer; the measuring process is simple and convenient and the practicability is strong.

Description

Technical Field

[0001] The invention belongs to the field of detection technology, and in particular relates to a device for identifying radioactive nuclides in water and measuring the total α / β radioactive specific activity online. Background Art

[0002] Identification of radionuclides in water and monitoring of total specific activity are important measures to ensure water resource safety. Radionuclides in natural water mainly come from uranium series, thorium series, actinium uranium series and potassium-40 in the strata; among them, uranium series, thorium series and actinium uranium series mainly emit α rays, potassium-40 mainly emits β rays, and these nuclides also emit characteristic γ rays during decay; in recent years, with the continuous development of nuclear energy and other nuclear technology applications, facilities that apply nuclear energy and nuclear technology may release the above-mentioned radionuclides and other radionuclides, which will affect water resources through natural cycles; therefore, the identification of radionuclides in water and the monitoring of α / β radioactive specific activity are receiving more and more attention.

[0003] At present, the identification of radionuclides in water and the monitoring of α / β specific activity are mainly carried out directly or indirectly by liquid scintillator detectors, α / β special measuring instruments, high-purity germanium semiconductor detectors and other equipment; for example, the main steps of measuring with liquid scintillator detectors or α / β special measuring instruments include sampling, concentration, transfer, washing, burning, ashing, weighing, sample preparation and other cumbersome processes, which not only makes the measurement process complicated and the sample easily contaminated, but also can only measure the total α / β specific activity, and cannot realize the identification of radionuclides; for another example, the main steps of measuring with high-purity germanium semiconductor detectors also include sampling, concentration, transfer, washing, burning, ashing, weighing, sample preparation and other cumbersome processes, and this method indirectly gives the total α / β specific activity by measuring the characteristic γ-ray spectrum of the radionuclides in the prepared sample through characteristic γ-ray activity measurement and nuclide identification calculation; the main disadvantages of these measurement methods are that the measurement process is complicated, the measurement time is long, and it is sampling measurement, and online monitoring cannot be realized. Summary of the invention

[0004] The object of the present invention is to provide a device for identifying radioactive nuclides in water and measuring the total specific activity of α / β radioactivity online, so as to solve the problems raised by the above-mentioned background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: comprising a water container, the water container is provided with a water inlet and a water outlet connected to the inside of the water container, a scintillator fiber array detector is fixedly arranged inside the water container; the scintillator fiber array detector comprises a scintillator fiber array, a packaging flange and a first photomultiplier tube, the scintillator fiber array is composed of a plurality of scintillator optical fibers bundled in a shuttle shape, the two ends of the scintillator fiber array are respectively coupled and connected with the first photomultiplier tube, and the two ends of the scintillator fiber array are packaged by a packaging flange and a sealant, an anti-Compton gamma spectrometer for identifying radioactive nuclides is also arranged on the water container, a sealed channel for passing power lines and signal lines of the scintillator fiber array, the first photomultiplier tube and the anti-Compton gamma spectrometer is arranged on the shell of the water container, and the scintillator fiber array detector and the anti-Compton gamma spectrometer are connected to the processor via the signal line.

[0006] Preferably, the anti-Compton gamma spectrometer includes a LaBr3 scintillator detector and a plurality of BGO scintillator detectors evenly distributed around the LaBr3 scintillator detector, and a second photomultiplier tube is fixedly connected to the end of each BGO scintillator detector, and an aluminum thin-walled gamma ray window is fixedly installed below the anti-Compton gamma spectrometer.

[0007] The scattered γ pulse signal of the BGO scintillator detector is anti-coincident with the γ pulse signal of the LaBr3 scintillator detector to output a characteristic γ energy spectrum. The purpose is to lower the Compton plateau on the characteristic γ energy spectrum, making the characteristic γ peak more significant, which is more conducive to identifying radioactive nuclides in water through the characteristic γ peak.

[0008] Preferably, the detection end of the inverse Compton gamma spectrometer is arranged inside the water container.

[0009] The detection end of the anti-Compton gamma spectrometer is arranged inside the water container to collect the characteristic gamma rays emitted by the radioactive nuclides in the water to the maximum extent.

[0010] Furthermore, the outer layer of the water container is provided with a lead shielding layer.

[0011] The lead shielding layer absorbs radiation in the environment to form a low-background measurement environment to reduce the impact of environmental radiation on the measurement results.

[0012] Preferably, the sealant is made of epoxy resin, and the interior of the sealing channel is sealed by the epoxy resin.

[0013] Epoxy resin has strong adhesion, wear resistance, chemical corrosion resistance, and good bonding performance, which can effectively increase the service life of the device.

[0014] The system energy calibration method using the above-mentioned water radionuclide identification and α / β radioactive total specific activity online measurement device is as follows: S1. Fill the water container with high-purity water, measure the background count rate with a scintillation fiber array detector, and measure the background gamma spectrum with an inverse Compton gamma spectrometer; S2. Use high-purity water to prepare aqueous solutions of americium-241 and potassium chloride containing different specific activities, inject them into a water container, perform system energy calibration, and obtain a calibration curve of the scintillation fiber array detector system count rate and α / β radioactive total specific activity; S3. After the system energy calibration is completed, high-purity water is injected into the water container for multiple cleanings.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention sets a water container, and sets a scintillator fiber array detector inside the water container. The device can be connected to the water flow. The water flows into the container from the water inlet of the water container and flows out from the water outlet of the water container. The α / β rays emitted by the radioactive nuclides in the water directly interact with the scintillating fiber to cause the scintillating fiber to emit light. The photons are transmitted to the first photomultiplier tube connected to it through the scintillating fiber. The photons generate electrons through the photoelectric effect at the cathode of the first photomultiplier tube. After the electrons are multiplied in the first photomultiplier tube, a pulse signal is output from the anode thereof. The total specific activity of α / β in the water is directly given by recording the count of the pulse signal, thereby realizing the online measurement of the total specific activity of α / β radioactivity in the water. In addition, the present invention can also synchronously identify the radioactive nuclides in the water flow passing through the water container through an inverse Compton γ spectrometer. 2. The present invention provides a shuttle-shaped scintillator fiber array so that the central part of the scintillator fiber array is raised and becomes loose, so that water can easily enter the gaps between the scintillator fibers, thereby effectively improving the accuracy of measuring the total α / β specific activity in water. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a front cross-sectional view of a device for identifying radionuclides in water and measuring α / β total specific activity of radioactivity online provided by an embodiment of the present invention; Figure 2 It is a schematic diagram of the arrangement structure of the LaBr3 scintillator detector and the BGO scintillator detector provided in an embodiment of the present invention; In the figure, 1-water container, 2-scintillator fiber array detector, 3-anti-Compton gamma spectrometer, 11-lead shielding layer, 12-water inlet, 13-water outlet, 14-sealing channel, 21-scintillator fiber array, 22-packaging flange, 23-first photomultiplier tube, 31-LaBr3 scintillator detector, 32-BGO scintillator detector, 33-second photomultiplier tube, 34-aluminum thin-walled gamma ray window. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] See also Figure 1-Figure 2 The present invention provides a technical solution: an online measurement device for identifying radioactive nuclides in water and measuring the total specific activity of α / β radioactivity, comprising a water container 1, the outer layer of the water container 1 is wrapped with a lead shielding layer 11 to reduce the influence of environmental rays on the inside of the water container 1, the water container 1 is provided with a water inlet 12 and a water outlet 13 connected to the inside of the water container 1, and a scintillator optical fiber array detector 2 is fixedly arranged inside the water container 1; The scintillator fiber array detector 2 includes: a scintillator fiber array 21, a packaging flange 22 and a first photomultiplier tube 23; the scintillator fiber array 21 is formed by binding a plurality of scintillator fibers in a shuttle shape, and the two ends of the scintillator fiber array 21 are respectively coupled to the first photomultiplier tube 23, and the two ends of the scintillator fiber array 21 are packaged by the packaging flange 22 and sealed by epoxy resin. An anti-Compton gamma spectrometer 3 for identifying radioactive nuclides is also provided on the water container 1, and the detection end of the anti-Compton gamma spectrometer 3 is arranged inside the water container 1. A sealed channel 14 for passing the power line and signal line of the scintillator fiber array 21, the first photomultiplier tube 23, and the anti-Compton gamma spectrometer 3 is provided on the shell of the water container 1, and after the power line and the signal line are passed through the sealed channel 14, the sealed channel 14 is sealed by epoxy resin filling, and the scintillator fiber array 21, the first photomultiplier tube 23, and the anti-Compton gamma spectrometer 3 are connected to the processor through the signal line.

[0019] In the present invention, the measurement principle of the scintillation fiber array detector 2 is as follows: the α / β rays emitted by the radioactive nuclides in the measured water sample react with the scintillation fiber to cause luminescence, and the luminescent photons are transmitted to the photocathode of the first photomultiplier tube 23 through the optical fiber, and electrons are generated through the photoelectric effect. The electrons are multiplied in the first photomultiplier tube 23 and a pulse signal is output from its anode. The pulse signal count is recorded by the processor to realize the measurement of the total specific activity of α / β in water, and its measurement sensitivity can reach 0.1Bq / L.

[0020] The anti-Compton gamma spectrometer 3 includes a LaBr3 scintillator detector 31 and a plurality of BGO scintillator detectors 32 evenly distributed around the LaBr3 scintillator detector 31, and a second photomultiplier tube 33 is fixedly connected to the end of each BGO scintillator detector 32; the anti-Compton gamma spectrometer 3 realizes the identification of radionuclides in water by measuring the characteristic gamma ray energy spectrum emitted by radionuclides in water, wherein the gamma pulse signal scattered by the BGO scintillator detector 32 is anti-coincident with the gamma pulse signal of the LaBr3 scintillator detector 31 to output the characteristic gamma energy spectrum, the purpose of which is to suppress the Compton plateau on the characteristic gamma energy spectrum, so that the characteristic gamma peak is more prominent, which is more conducive to identifying the radionuclides in water through the characteristic gamma peak; An aluminum thin-walled gamma-ray window 34 is fixedly provided below the anti-Compton gamma spectrometer 3. The aluminum thin-walled gamma-ray window 34 isolates the water flow to prevent water from corroding the anti-Compton gamma spectrometer 3, while not affecting the rays, allowing the rays to be emitted through the window. Aluminum is used because aluminum has a low atomic number and will not produce excessive shielding effect on gamma rays.

[0021] It should be noted that the inverse Compton gamma spectrometer 3 of the present invention needs to use multiple standard gamma sources to complete the system energy calibration before use. The specific method is: 1. Fill the water container 1 with high-purity water, measure the background count rate with a scintillation fiber array detector 2, and measure the background γ spectrum with an inverse Compton γ spectrometer 3 so as to deduct the background effect during data processing; 2. Use high-purity water to prepare americium-241 with different specific activities ( 241 Am, alpha emitter) and potassium chloride (KCl, of which 40 K is a β emitter) aqueous solution, injected into water container 1, system energy calibration is performed, and a calibration curve of the system count rate and the total α / β radioactive specific activity of the scintillation fiber array detector 2 is obtained; 3. After the calibration is completed, use high-purity water to fill the water container 1 for multiple cleanings to eliminate 241 Am and 40 Effect of K residue on measurement.

[0022] It should be noted that the scintillation optical fiber, LaBr3 scintillator detector 31, BGO scintillator detector 32, photomultiplier tube and processor in the present invention are all commercial components purchased on the market. Their specific models and specifications need to be selected and determined based on the actual specifications of the device. The selection calculation method adopts the existing technology in the field, so it will not be described in detail.

[0023] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for identifying radionuclides in water and measuring the total specific activity of α / β radioactivity online, characterized in that: It comprises a water container, which is provided with a water inlet and a water outlet connected with the inside of the water container, and a scintillator fiber array detector is fixedly arranged inside the water container; the scintillator fiber array detector comprises a scintillator fiber array, a packaging flange and a first photomultiplier tube, the scintillator fiber array is composed of a plurality of scintillator optical fibers bundled in a shuttle shape, the two ends of the scintillator fiber array are respectively coupled and connected to the first photomultiplier tube, and the two ends of the scintillator fiber array are packaged by a packaging flange and a sealant, the water container is also provided with an anti-Compton gamma spectrometer for identifying radioactive nuclides, and the shell of the water container is provided with a sealed channel for passing the power cord and signal line of the scintillator fiber array, the first photomultiplier tube and the anti-Compton gamma spectrometer, and the scintillator fiber array detector and the anti-Compton gamma spectrometer are connected to the processor via the signal line.

2. The device for identifying radionuclides in water and measuring the total specific activity of α / β radioactivity online according to claim 1, characterized in that: The anti-Compton gamma spectrometer comprises a LaBr3 scintillator detector and a plurality of BGO scintillator detectors evenly distributed around the LaBr3 scintillator detector, and a second photomultiplier tube is fixedly connected to the end of each BGO scintillator detector. An aluminum thin-walled gamma ray window is fixedly arranged below the anti-Compton gamma spectrometer.

3. The device for identifying radionuclides in water and measuring the total specific activity of α / β radioactivity online according to claim 2, characterized in that: The detection end of the anti-Compton gamma spectrometer is arranged inside the water container.

4. The device for identifying radionuclides in water and measuring the total specific activity of α / β radioactivity according to claim 3, characterized in that: The outer layer of the water container is provided with a lead shielding layer.

5. The device for identifying radionuclides in water and measuring the total specific activity of α / β radioactivity online according to claim 1, characterized in that: The sealant is epoxy resin, and the inside of the sealing channel is sealed by the epoxy resin.

6. A system energy calibration method using the device for identifying radionuclides in water and measuring the total specific activity of α / β radioactivity online according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Fill the water container with high-purity water, measure the background count rate with a scintillation fiber array detector, and measure the background gamma spectrum with an inverse Compton gamma spectrometer; S2. Use high-purity water to prepare aqueous solutions of americium-241 and potassium chloride containing different specific activities, inject them into a water container, perform system energy calibration, and obtain a calibration curve of the scintillation fiber array detector system count rate and α / β radioactive total specific activity; S3. After the system energy calibration is completed, high-purity water is injected into the water container for multiple cleanings.

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