JP7447031B2 - water monitor - Google Patents

Description

The present invention relates to water monitors.

Water monitors are used to measure radioactivity in wastewater from nuclear power plants, etc. Conventional measurement methods include a method using a liquid scintillator, a method using an ionization chamber, and a method of measuring characteristic X-rays.

According to Non-Patent Document 1, a measurement sample is dissolved in a liquid scintillator prepared by adding a solute (phosphor) and additives to an organic solvent such as xylene or toluene. In Non-Patent Document 1, luminescence of a liquid scintillator due to beta rays emitted from tritium in a measurement sample is measured using a photomultiplier tube. Since water is immiscible with toluene and xylene, which are standard solvents for liquid scintillators, emulsion scintillators with added surfactants are widely used.

In Non-Patent Document 2, tritium in a gas is measured by collecting ion pairs of gas molecules generated by the interaction between beta rays and gas on an electrode in an ionization chamber and measuring the amount of charge. Unlike proportional counter tubes and GM tubes, the gases that can be used in an ionization chamber are not only rare gases such as argon and helium, but also atmospheric gases such as air and nitrogen. Suitable for measuring tritium concentration. The method of Non-Patent Document 2 allows almost real-time measurement and has been used as a room monitor for a long time.

Non-Patent Document 3 uses a beta-ray induced X-ray detection method (BIXS) that measures X-rays induced by tritium beta rays. In Non-Patent Document 3, the tritium amount near the stainless steel surface and the tritium concentration distribution inside the stainless steel are determined non-destructively using BIXS.

Patent Document 1 uses a method of measuring beta rays emitted from tritium using a solid scintillator. In Patent Document 1, two flat solid scintillators are installed at positions sandwiching a measurement sample, and the tritium concentration is continuously measured by spraying the measurement sample onto the surface of the solid scintillators or the sample introduction plate.

Patent No. 4659612

Ministry of Education, Culture, Sports, Science and Technology, Radioactivity Measurement Series 9 “Tritium Analysis Method”, Japan Analysis Center (2002) Kenji Okuno, "Tritium Detection Technology and Quantitative Evaluation" Journal of the Japan Society for Plasma and Nuclear Fusion, Vol. 72, No. 12 (1996), p. 1376-1385 Torikai and 4 others, “Application of BIXS method to measurement of tritium-contaminated materials” University of Toyama Hydrogen Isotope Science Research Center Research Report 24 (2004) p.29-39

In the method described in Non-Patent Document 1, continuous monitoring is difficult because it is necessary to sample a measurement sample from wastewater and mix a liquid scintillator with the sampled measurement sample to cause it to emit light. Furthermore, in Non-Patent Document 3, since it is necessary to treat the sample mixed with the liquid scintillator as waste liquid after measurement, there are problems with the processing cost and the environment.

In the method of Non-Patent Document 2, for example, when measuring tritium as a beta-ray emitting nuclide, wastewater is electrolyzed to generate a gas containing tritium, and the generated gas is ionized to measure the gaseous radioactive substance. It is necessary to put it into a device such as a box. In Non-Patent Document 2, in order to electrolyze wastewater, it is necessary to add an electrolyte such as sodium hydroxide or sulfuric acid to the wastewater, which poses processing costs and environmental problems.

In the method of Non-Patent Document 3, the object to be measured is only metal, and there is no example of measuring liquid. Furthermore, since the energy of beta rays emitted from tritium is very low, Non-Patent Document 3 can only measure the amount of tritium present in a very thin region of the metal surface.

The method of Patent Document 1 requires a mechanism for spraying the measurement sample onto the surface of the solid scintillator or sample introduction plate. Furthermore, in Patent Document 1, when continuously measuring a sample, it is necessary to reduce the background. In other words, in Patent Document 1, the previously sprayed sample adheres to the surface of the solid scintillator and remains, creating a background, so before spraying a new sample onto the solid scintillator, tritium-free water is removed. need to be sprayed.

As described above, there is still no technology for online monitoring of beta-ray-emitting nuclides such as tritium contained in wastewater from nuclear power plants.

The present invention has been made in view of the above problems, and an object thereof is to provide a water monitor capable of online monitoring of beta-ray emitting nuclides in wastewater.

In order to solve the above problems, a water monitor according to one aspect of the present invention is a water monitor that monitors radioactive substances in waste water, and is designed to face the waste water in the drain channel via a gas layer in the drain channel. The radiation detector is equipped with a radiation detector installed in the drainage canal, and a gas bubble generator that mixes a plurality of gas bubbles into the drainage water in the drainage canal. It detects characteristic X-rays generated by the reaction between beta rays emitted from nuclides and predetermined elements constituting the gas.

According to the present invention, the beta rays from the beta ray emitting nuclide react with a predetermined element constituting the gas in the gas layer or gas bubble to generate characteristic X-rays, so the characteristic X-rays are detected by a radiation detector. By doing so, beta-ray emitting nuclides in wastewater can be measured with high accuracy.

An explanatory diagram of a water monitor. FIG. 3 is an explanatory diagram showing how characteristic X-rays are generated and detected by a radiation detector. A graph showing an example of measurement of characteristic X-rays. FIG. 2 is a configuration diagram of a system including a water monitor according to a second embodiment. FIG. 3 is a configuration diagram of a system including a water monitor according to a third embodiment. FIG. 4 is a configuration diagram of a system including a water monitor according to a fourth embodiment. FIG. 7 is a configuration diagram of a system including a water monitor according to a fifth embodiment. 8 is a sectional view seen from the direction of arrow VIII in FIG. 7. FIG. FIG. 7 is a configuration diagram of a system including a water monitor according to a sixth embodiment. 9 is a sectional view seen from the direction of arrow X in FIG. 9. FIG. FIG. 7 is an explanatory diagram showing an installation example of a gas bubble generator according to a seventh embodiment. 12 is a sectional view seen from the direction of arrow XII in FIG. 11. FIG. FIG. 8 is a sectional view showing an example of installation of a gas bubble generator according to an eighth embodiment. 14 is a sectional view seen from the direction of arrow XIV in FIG. 13. FIG.

Embodiments of the present invention will be described below based on the drawings. The water monitor according to this embodiment does not directly detect beta rays from beta ray emitting nuclides, but generates characteristic X-rays by reacting beta rays from beta ray emitting nuclides with elements constituting gas. , measuring beta-ray emitting nuclides by detecting characteristic X-rays.

The water monitor WM according to the present embodiment includes, for example, a radiation detector 1 and a gas bubble generator 30, and the radiation detector 1 is installed with respect to the drainage water 40 in the drainage channel 50 via the gases 10 and 20. do. Further, in the water monitor of this embodiment, a gas bubble generator 30 that mixes bubble-shaped gas 20 into the waste water 40 is installed near the drain channel 50, and beta rays emitted from beta ray emitting nuclides in the waste water are combined with the water monitor. A radiation detector 1 measures characteristic X-rays generated by the reaction with the gas and the elements constituting the gas bubble.

According to this embodiment, characteristic X-rays generated through a plurality of paths are incident on the radiation detector 1. The characteristic X-rays generated in one path are generated by the reaction between beta rays emitted from beta ray-emitting nuclides in the wastewater and the gas between the wastewater and the radiation detector 1 . Characteristic X-rays generated through another route are generated by a reaction between beta rays emitted from beta ray-emitting nuclides in the wastewater and gas bubbles 20 in the wastewater.

Since the range of beta rays in wastewater is very short, if there are no gas bubbles 20, there will be fewer beta ray emitting nuclides that contribute to the production of characteristic X-rays. However, when the gas bubble 20 is present in the drainage channel as in the present embodiment, the contact area between the gas and the drainage increases, so the amount of beta-ray emitting nuclides that contribute to the generation of characteristic X-rays increases significantly. do.

Therefore, according to the present embodiment, the characteristic X-ray flux incident on the radiation detector 1 increases, so that the measurement accuracy of beta-ray emitting nuclides in wastewater is improved.

The range of characteristic X-rays in waste water or gas is very long compared to the range of beta rays in waste water or gas. Therefore, in this embodiment, the characteristic X-rays generated by the reaction between the gas bubbles present at a certain depth in the wastewater and the beta rays emitted from the beta-ray emitting nuclides in the surrounding wastewater are also used for radiation detection. It is possible to enter the vessel 1. In this embodiment, by increasing the characteristic X-ray flux incident on the radiation detector 1, the measurement accuracy of beta-ray emitting nuclides in wastewater is improved.

Furthermore, in this embodiment, since the gas layer 10 exists between the wastewater and the radiation detector 1, the radiation detector 1 and the beta-ray emitting nuclide in the wastewater do not come into direct contact. Alternatively, the membrane separating the radiation detector 1 and the gas layer 10 does not come into direct contact with the beta-ray emitting nuclide in the waste water. Therefore, in this embodiment, it is possible to suppress an increase in the background due to attachment of beta-ray emitting nuclides to the radiation detector 1 or the film separating the radiation detector and the gas layer 10, and to detect beta-ray emitting nuclides with high accuracy. can be measured.

In this embodiment, as described above, in a water monitor including the radiation detector 1 and the gas bubble generator 30, the radiation detector 1 is installed with respect to the drainage water 40 in the drainage channel 50 via the gas layer 10, and A gas bubble generator 30 that mixes bubble-shaped gas (gas bubbles) 20 into drainage water is installed near the drainage channel 50.

As the radiation detector 1, for example, a germanium detector, a silicon drift detector, a silicon semiconductor detector, or a compound semiconductor detector may be used.

The gas bubble generator 30 may generate gas bubbles 20 with a radius of 1 mm or more, or may generate gas bubbles 20 with a small bubble diameter such as microbubbles. Gas bubbles 20 can be generated in multiple ways. For example, as one method, gas bubbles can be generated by introducing gas into waste water and swirling the waste water into which the gas has been introduced at high speed. As another method, gas bubbles may be generated, for example, by configuring a pipe that supplies gas into the waste water to include an ultrasonic vibrator. The method of generating gas bubbles does not matter.

The gas supplied into the waste water may be recovered from the waste water and reused as a gas for generating new gas bubbles.

The waste water in the drainage channel is caused to flow at a constant flow rate, and the gas bubbles are generated from the gas bubble generator 30 so that the density of the gas bubbles 20 generated by the gas bubble generator 30 is maximum immediately below the radiation detector 1. The generation position and gas bubble diameter of 20 may be adjusted. The flow rate of the wastewater may be adjusted so that the density of the gas bubbles 20 generated by the gas bubble generator 30 is maximized immediately below the radiation detector 1. "Maximum" here is an example of "more than a predetermined value".

When beta rays emitted from beta ray-emitting nuclides in the wastewater enter the gas (gas layer 10) between the wastewater and the radiation detector 1, the elements constituting the gas react with the beta rays. As a result, characteristic X-rays are emitted.

As an example, a case will be explained in which the beta ray emitting nuclide is tritium and argon gas is used as the gas. The reaction between tritium in the waste water and argon releases characteristic X-rays with an energy of about 3 keV.

The thickness of the gas layer 10 between the wastewater and the radiation detector 1 may be set to be equal to or less than the range in the gas at the maximum energy of beta rays emitted from beta-ray emitting nuclides in the wastewater. When tritium is the measurement target as a beta ray emitting nuclide and argon is used as the gas, the maximum energy of the beta rays emitted from tritium is 18 keV, so the thickness of the gas layer 10 between the wastewater and the radiation detector 1 is The length may be set to about 12 mm or less.

As described above, the beta rays emitted from the beta ray emitting nuclides in the wastewater also emit characteristic X-rays when they react with the gas constituting the gas bubbles 20 in the wastewater. The range of characteristic X-rays in waste water is much larger than that of beta rays of similar energy. Therefore, the radiation detector 1 can measure the characteristic X-rays generated at a depth where the beta rays emitted from the beta-ray emitting nuclides in the wastewater do not reach the gas layer 10.

In this embodiment, the characteristic X-rays generated by the reaction between beta rays emitted from beta-ray emitting nuclides in wastewater and the elements constituting the gas layer 10 and the gas bubbles 20 are transmitted to the radiation detector 1. Measured by

The radiation detector 1 measures the peak value spectrum of characteristic X-rays and derives the count rate of the peak corresponding to the energy of the characteristic X-rays of the elements constituting the gas in the peak value spectrum. By using a database showing the relationship between the beta-ray emitting nuclide concentration in wastewater and the peak count rate, which has been measured in advance, the beta-ray emitting nuclide concentration can be calculated from the measurement result of the peak count rate. It is also possible to calculate changes in the concentration of beta-ray emitting nuclides from changes in the peak count rate over time. It is also possible to calculate the time change of the average value for each certain period of time, which is obtained by shifting the time.

A first embodiment will be described using FIGS. 1 to 3. FIG. 1 shows an example of the configuration of the water monitor WM of this embodiment. The water monitor WM includes, for example, a radiation detector 1 and a gas bubble generator 30. The drainage channel 50 has a drainage channel structure 51, through which the drainage water 40 flows in the direction of the arrow 42. A gas bubble generator 30 is provided upstream of the radiation detector 1 . A gas layer 10 is formed between the liquid level 41 of the drainage water 40 in the drainage channel 50 and the upper inner surface of the drainage channel structure 51.

The radiation detector 1 of the water monitor WM is installed in the drainage channel 50 so as to face the drainage water 40 in the drainage channel 50 with the gas layer 10 interposed therebetween. The gas bubble generator 30 of the water monitor WM is a device that mixes bubble-shaped gas (gas bubbles 20) into the waste water 40, and is installed near the drainage channel.

As the radiation detector 1, for example, a germanium detector, a silicon drift detector, a silicon semiconductor detector, or a compound semiconductor detector can be used. The surface (detection area) of the radiation detector 1 facing the gas layer 10 is in direct contact with the gas layer 10 without the drainage channel structure 51, or is in contact with the gas layer 10 through a thin film.

As shown on the left side of FIG. 2, an example in which characteristic X-rays are generated is shown. When beta rays 70 emitted from beta ray-emitting nuclides 80 in the waste water 40 enter the gas layer 10 between the waste water 40 and the radiation detector 1, characteristic X-rays 60 are generated by reaction with the elements constituting the gas. is released. When argon is used as the gas, characteristic X-rays with an energy of about 3 keV are emitted. Argon is contained in the air at 0.93%, and even if used argon is released into the atmosphere, it will not pose an environmental problem. Since the solubility of argon in water at 20° C. is 0.0336 mL/mL, a large amount of the supplied argon does not dissolve in the waste water.

As shown on the right side of FIG. 2, the beta rays 70 emitted from the beta ray emitting nuclide 80 in the waste water 40 also emit characteristic X-rays 60 by reaction with the gas constituting the gas bubbles 20 in the waste water 40. do. The range of the characteristic X-rays 60 in the waste water 40 is very large compared to the range of beta rays 70 of similar energy. Therefore, the characteristic X-rays 60 generated at a depth where the beta rays 70 emitted from the beta-ray emitting nuclide 80 in the waste water 40 do not reach the gas layer 10 can be measured by the radiation detector 1.

The radiation detector 1 measures characteristic X-rays 60 generated by the reaction between the beta rays 70 emitted from the beta-ray emitting nuclides 80 in the waste water 40 and the elements constituting the gas layer 10 and the gas bubbles 20 .

A thin film 11 may be provided on the surface of the radiation detector 1 in contact with the gas layer 10. The thin film 11 is made of a material having an atomic number of 15 or less or a combination of a plurality of materials having an atomic number of 15 or less and having a thickness thinner than the range of the characteristic X-ray 60 in the thin film.

FIG. 3 shows an example of measurement results of characteristic X-rays in the water monitor WM. In the radiation detector 1, the peak value spectrum is measured, and the count rate of the peak corresponding to the energy of the characteristic X-ray of the element constituting the gas in the peak value spectrum is derived. The concentration of beta-ray emitting nuclides in the wastewater is derived from the measurement results of this peak count rate.

This embodiment configured as described above includes a radiation detector 1 provided in the drainage channel so as to face the drainage water 40 in the drainage channel via the gas layer 10 in the drainage channel 50, and a radiation detector 1 provided in the drainage channel to face the drainage water 40 in the drainage channel. The radiation detector 1 includes a gas bubble generator 30 that mixes gas bubbles 20 into the wastewater, and the radiation detector 1 is configured to detect beta rays generated by the reaction between beta rays 70 emitted from beta ray emitting nuclides 80 in wastewater and elements constituting the gas. A characteristic X-ray 60 is detected. Therefore, the water monitor WM of this embodiment can monitor beta-ray emitting nuclides in wastewater online.

The water monitor WM of this embodiment not only detects the characteristic X-rays 60 generated by the incidence of beta rays 70 into the gas layer 10, but also detects the beta rays 70 in the gas bubbles 20 at a position deeper than a predetermined distance from the liquid surface 41. The characteristic X-rays 60 generated by entering the inside can also be measured by the radiation detector 1. A position deeper than a predetermined distance from the liquid level 41 means a distance from the beta ray emitting nuclide 80 to the liquid level 41 (to the gas layer 10) than the range of the beta rays 70 from the beta ray emitting nuclide 80 in the waste water 40. This is the position where the distance (distance) becomes longer.

The water monitor WM of this embodiment uses the gas layer 10 and the gas bubbles 20 to generate characteristic X-rays derived from beta rays from the beta-ray emitting nuclide 80, and transmits the generated characteristic X-rays to a radiation detector. Detected by 1. Therefore, according to this embodiment, not only the beta ray emitting nuclide 80 near the liquid surface 41 but also the beta ray emitting nuclide 80 at a deeper position can be measured, improving the sensitivity and accuracy of measurement.

Furthermore, in this embodiment, since the radiation detector 1 is attached to the drainage channel 50 so that the detection area of the radiation detector 1 does not directly touch the drainage water 40, the beta ray emitting nuclide 80 is detected by the radiation detector 1. It is possible to prevent it from adhering to the area and becoming a background.

A second embodiment will be described using FIG. 4. In each of the following embodiments including this embodiment, differences from the first embodiment will be mainly described.

In the water monitor WM of this embodiment, a pump 90 and a gas bubble generator 30 are installed in the drainage channel 50. The generation of gas bubbles in the gas bubble generator 30 is controlled by a control device 100 that controls the flow rate and gas bubble generation.

The drainage channel 50 is provided parallel or substantially parallel to the ground. The gas bubble generator 30 is located downstream of the pump 90 and provided below the drainage channel 50. A gas cylinder 31 is connected to the gas bubble generator 30 via a pipe 32. The radiation detector 1 is located downstream of the gas bubble generator 30 and provided above the drainage channel 50.

In this embodiment, in the gas bubble generator 30, gas supplied from a gas cylinder 31 through a pipe 32 is introduced into waste water, and the waste water into which the gas has been introduced is swirled at high speed, thereby generating gas bubbles. .

Here, the rate at which the gas bubble rises in the waste water differs depending on the bubble diameter. Rising is movement in a direction perpendicular to the ground. Further, the gas bubbles move in the direction 42 of the wastewater flow depending on the flow rate of the wastewater.

In this embodiment, the flow rate and gas bubble diameter of the waste water are adjusted so that the density of the gas bubbles generated by the gas bubble generator 30 is maximum near the surface of the waste water directly under the radiation detector 1. and adjustment using the gas bubble generation control device 100.

The thickness of the radiation detector 1 and the gas layer 10 may be adjusted using the flow rate and gas bubble generation control device 100. By adjusting the density of the gas bubbles to be maximum in the vicinity of the surface of the wastewater directly under the radiation detector 1, the measurement performance of the beta-ray emitting nuclide concentration in the wastewater can be improved. This embodiment configured in this manner also provides the same effects as the first embodiment.

A third embodiment will be described using FIG. 5. In this embodiment, the gas mixed in the waste water is recovered and reused.

In this embodiment as well, the gas bubble generator 30 is installed in the drainage channel 50. The gas bubbles generated by the gas bubble generator 30 rise in the drainage toward the upper side of the drainage channel 50 at a speed according to the bubble diameter, and move in the direction 42 of the drainage according to the flow velocity of the drainage. do.

The gas bubbles rising in the drainage water form a gas layer 10 at the top within the drainage channel 50. The radiation detector 1 is installed at a position a certain distance away from the installation position of the gas bubble generator 30 in the direction 42 in which the wastewater flows.

It is preferable that the thickness of the gas layer 10 between the wastewater and the radiation detector 1 be equal to or less than the range in the gas of the maximum energy of beta rays emitted from beta-ray emitting nuclides in the wastewater. This prevents beta rays from entering the radiation detector 1, so background in characteristic X-ray measurements can be reduced.

A gas recovery pipe 33 is attached to a drainage channel 50 at a position a certain distance away from the radiation detector 1 in the direction 42 in which the drainage water flows. The gas recovery pump 34 sucks gas from the gas layer 10 in the drainage channel 50 via the gas recovery pipe 33 and supplies it to the gas bubble generator 30 via the gas supply pipe 32. The gas bubble generator 30 generates gas bubbles from the gas recovered by the gas recovery pump 34 and supplies them to the drainage channel 50 .

This embodiment configured in this manner also provides the same effects as the first embodiment. Furthermore, in this embodiment, the gas supplied to the drainage channel 50 is recovered and reused, so that the cost of gas consumption can be reduced.

A fourth example will be described using FIG. 6. In this embodiment, flow velocity data and gas bubble diameter data are input from the flow rate and gas bubble generation control device 100 to the beta ray emitting nuclide concentration calculation unit 3 that calculates the beta ray emitting nuclide concentration in wastewater.

A measurement signal from the radiation detector 1 is input to a data collection/analysis device 2. The data collection/analysis device 2 calculates the peak count rate of the characteristic X-ray in the peak value spectrum, and inputs the calculated peak count rate of the characteristic X-ray to the beta-ray emitting nuclide concentration calculation unit 3.

The beta-ray emitting nuclide concentration calculation unit 3 uses the beta-ray emitting nuclide concentration in the wastewater and a predetermined database 4 from the flow rate data, the gas bubble diameter data, and the characteristic X-ray peak count rate. The concentration of the beta-ray emitting nuclide in the inside is calculated, and the calculated concentration is displayed on the display device 5. A predetermined database 4 shows the relationship between the concentration of beta-ray emitting nuclides in wastewater and the peak count rate of characteristic X-rays with respect to flow velocity and gas bubble diameter.

The display device 5 may display time changes in the concentration of beta-ray emitting nuclides in the wastewater. The display device 5 may display the average value of the beta-ray emitting nuclide concentration in the wastewater at certain fixed time intervals while shifting the time. This embodiment configured in this manner also has the same effects as the first embodiment.

A fifth embodiment will be described using FIGS. 7 and 8. FIG. 8 is a cross-sectional view of FIG. 7. In the water monitor of this embodiment, a plurality of radiation detectors 1(1) to 1(n) are placed above a drainage channel 50 having a circular cross section in the longitudinal direction of the drainage channel 50 (in the direction 42 in which the drainage water flows). Place along. Hereinafter, if a plurality of radiation detectors are not particularly distinguished, they will be referred to as radiation detectors 1.

This embodiment configured in this manner also provides the same effects as the first embodiment. Furthermore, in this embodiment, since a plurality of radiation detectors 1 are arranged along the flow direction 42 of the wastewater, the measurement sensitivity of beta-ray emitting nuclides can be increased. Thereby, the performance of the water monitor can be improved.

A sixth embodiment will be described using FIGS. 9 and 10. FIG. 10 is a cross-sectional view of FIG. 9. In the water monitor of this embodiment, a plurality of radiation detectors 1 are arranged in a matrix above a drainage channel 50 having a rectangular cross section. That is, in this embodiment, a plurality of radiation detectors 1 are provided in the direction 42 in which the drainage water flows (the longitudinal direction of the drainage channel 50) and in the direction perpendicular to the direction 42 in the same plane (the width direction of the drainage channel 50). Set up. In the illustrated example, n radiation detectors 1 are arranged in the longitudinal direction of the drainage channel 50, and m radiation detectors 1 are arranged in the width direction of the drainage channel 50.

This embodiment configured in this manner also provides the same effects as the first embodiment. Furthermore, in this embodiment, since the plurality of radiation detectors 1 are arranged two-dimensionally (arranged in a matrix) above the drainage channel 50, the measurement sensitivity of beta-ray emitting nuclides can be further improved. Thereby, the performance of the water monitor can be improved.

A seventh embodiment will be described using FIGS. 11 and 12. FIG. 12 is a cross-sectional view of FIG. 11. In the water monitor of this embodiment, a plurality of gas bubble generators 30(1) to 30(n) are installed at the bottom of a drainage channel 50 having a circular cross section in the longitudinal direction of the drainage channel 50 (in the direction 42 of the flow of wastewater). Place along. Hereinafter, if a plurality of gas bubble generators are not distinguished, they will be referred to as gas bubble generators 30.

This embodiment configured in this manner also provides the same effects as the first embodiment. Furthermore, in this embodiment, since a plurality of gas bubble generators 30 are arranged along the flow direction 42 of the waste water, the density of the gas bubbles 20 or the volume ratio of the gas bubbles 20 to water can be increased. Thereby, the performance of the water monitor can be improved.

An eighth embodiment will be described using FIGS. 13 and 14. FIG. 14 is a cross-sectional view of FIG. 13. The water monitor of this example is
A plurality of gas bubble generators 30 are arranged in a matrix below a drainage channel 50 having a rectangular cross section. In this embodiment, a plurality of gas bubble generators 30 are provided in the direction 42 in which the drainage water flows (the longitudinal direction of the drainage channel 50) and in the direction perpendicular to the direction 42 in the same plane (the width direction of the drainage channel 50). Install. In the illustrated example, n gas bubble generators 30 are arranged in the longitudinal direction of the drainage channel 50, and m gas bubble generators 30 are arranged in the width direction of the drainage channel 50.

This embodiment configured in this manner also provides the same effects as the first embodiment. Furthermore, in this embodiment, since a plurality of gas bubble generators 30 are arranged two-dimensionally (arranged in a matrix) at the lower part of the drainage channel 50, the density of the gas bubbles 20 or the volume with respect to water in the water is further improved. The ratio can be increased and the performance of the water monitor can be improved.

Note that the present invention is not limited to the embodiments described above. Those skilled in the art can make various additions and changes within the scope of the present invention. The embodiments described above are not limited to the configuration examples illustrated in the accompanying drawings. The configuration and processing method of the embodiment can be modified as appropriate within the scope of achieving the purpose of the present invention.

Moreover, each component of the present invention can be selected arbitrarily, and inventions having selected configurations are also included in the present invention. Furthermore, the configurations described in the claims can be combined in ways other than the combinations specified in the claims.

1: Radiation detector, 2: Data collection/analysis device, 3: Beta-ray emitting nuclide concentration calculation unit in wastewater, 4: Database, 5: Display device, 10: Gas, 11: Thin film, 20: Gas bubble, 30 : Gas bubble generator, 31: Gas cylinder, 32: Gas supply piping, 33: Gas recovery piping, 34: Gas recovery pump, 40: Drainage water, 41: Drainage surface, 42: Direction of drainage flow, 50: Drainage channel , 51: drainage channel structure, 60: characteristic X-ray, 70: beta ray, 80: beta ray emitting nuclide, 90: pump, 100: flow velocity and gas bubble generation control device, WM: water monitor

Claims (13)

A water monitor that monitors radioactive substances in wastewater,
a radiation detector provided in the drainage channel so as to face the drainage in the drainage channel via a gas layer in the drainage channel;
a gas bubble generator that mixes a plurality of gas bubbles, which are the gas bubbles, into the drainage water in the drainage channel;
Equipped with
The radiation detector detects characteristic X-rays generated by a reaction between beta rays emitted from beta ray-emitting nuclides in the wastewater and a predetermined element constituting the gas.
water monitor. The gas bubble generator is set such that the density of the gas bubbles or the ratio of the volume of the gas to the waste water in a predetermined area near the detection area of the radiation detector is a predetermined value or more.
A water monitor according to claim 1. The gas bubble generator generates the gas bubble by supplying the gas to the waste water in the drainage channel from the upstream side of the radiation detector and swirling the waste water to which the gas has been supplied.
A water monitor according to claim 1. The gas bubble generator generates the gas bubbles by supplying the gas from the upstream side of the radiation detector to the drainage in the drainage channel via a supply pipe having an ultrasonic vibrator.
A water monitor according to claim 1. The thickness of the gas layer is set to be equal to or less than the range in the gas of the maximum energy of beta rays emitted from the beta ray emitting nuclide;
A water monitor according to claim 1. A predetermined thin film is provided in the detection area of the radiation detector,
The thin film has a thickness thinner than the range of the characteristic X-ray and is formed of either a material with an atomic number of 15 or less or a material containing a plurality of materials with an atomic number of 15 or less.
A water monitor according to claim 1. adjusting the thickness of the gas layer by controlling at least one of the generation position of the gas bubble, the diameter of the gas bubble, or the flow rate of the waste water;
A water monitor according to claim 1. Calculating the concentration of beta-ray emitting nuclides in the wastewater based on the peak count rate corresponding to the energy of the characteristic X-ray in the peak value spectrum, the flow rate of the wastewater, and the diameter of the gas bubble;
A water monitor according to claim 1. The radiation detector is located in the upper part of the drainage channel, and a plurality of radiation detectors are arranged in the longitudinal direction of the drainage channel.
A water monitor according to claim 1. The radiation detector is located at the upper part of the drainage channel, and a plurality of radiation detectors are arranged in the longitudinal direction of the drainage channel and in the width direction of the drainage channel, respectively.
A water monitor according to claim 1. The gas bubble generator is located at a lower part of the drainage channel, and a plurality of the gas bubble generators are arranged in the longitudinal direction of the drainage channel.
A water monitor according to claim 1. The gas bubble generator is located at a lower part of the drainage channel, and a plurality of the gas bubble generators are arranged in the longitudinal direction of the drainage channel and in the width direction of the drainage channel, respectively.
A water monitor according to claim 1. The beta ray emitting nuclide is tritium, and the gas is argon gas.
A water monitor according to claim 1.

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