JP2017116349A - β RAY GAS MONITOR AND MONITORING METHOD FOR GAS CONTAINING NUCLEAR SPECIES EMITTING β RAY - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a β ray gas monitor capable of monitoring concentration of radioactivity under a measurement condition suitable for a gas containing nuclear species emitting β ray to be measured, and a monitoring method for the gas containing nuclear species emitting β ray.SOLUTION: A β ray gas monitor 10 comprises: a hollow body 11 with one open end closed; a β-ray detector 12 arranged in the body 11, for detecting β ray and outputting a detection signal s; a variable barrier 13 provided in a position opposite a detection port of the β-ray detector 12 movably along an inner surface of the body 11, set in a barrier position corresponding to a sample gas to be measured, and forming a sample space 14 separated from outer space with the inner surface of the body 11; a counting rate counter 17 measuring a counting rate based on the detection signal s detected from the sample gas introduced into the sample space 14; and a concentration of radioactivity calculation part 36 acquiring concentration of radioactivity of the sample gas based on the measured counting rate and the volume of the sample space 14.SELECTED DRAWING: Figure 1

Description

  Embodiments of the present invention include a β-ray gas monitor that detects β-decaying radionuclides released into the atmosphere at a nuclear power plant or facility and measures radioactivity concentration in the atmosphere, and a nuclide that emits β-rays The present invention relates to a gas monitoring method.

  The radiation detector of the radioactive gas monitor installed in the building of a nuclear power plant or nuclear facility has a high radiation emission rate per decay in order to measure the radionuclide in the gas to be measured with high sensitivity. The line is the measurement target.

  In a general radioactive gas monitor, a radioactive gas to be measured is usually introduced into a sample space, and β-rays emitted by decay of radionuclides (for example, Kr-85, Xe-133, etc.) contained in the gas. And the radioactivity concentration in the gas is calculated based on the detected value.

  Conventionally, a highly reliable radioactive gas monitor that detects β rays with high accuracy, such as downsizing the sample space, has been studied. Recently, a calculation code that simulates the behavior of radiation using a Monte Carlo method such as PHITS has been developed.

JP 2010-78319 A Japanese Patent Laid-Open No. 11-64527 Japanese Utility Model Publication No. 62-88974

  By the way, the energy of β-rays emitted by the decay of radionuclides differs for each nuclide. For this reason, if β-ray energy is different, response characteristics such as detection efficiency in the radiation detector also change.

  In other words, there are optimum measurement conditions depending on the β-ray energy, but many conventional methods for monitoring gases containing nuclides that emit β-rays are based on empirical rules, and radiation detection according to β-ray energy. The response characteristics of the vessel were not fully considered.

  The present invention has been made in view of such circumstances, and a β-ray gas monitor capable of monitoring a radioactivity concentration under measurement conditions suitable for a gas containing a nuclide that emits β-rays to be measured. And it aims at providing the monitoring method of the gas containing the nuclide which emits a beta ray.

  A β-ray gas monitor according to an embodiment of the present invention includes a hollow main body with one open end sealed, and a β-ray detector that is disposed inside the main body, detects β-rays, and outputs a detection signal. And movably provided along the inner surface of the main body at a position facing the detection port of the β-ray detector, set at a partition wall position corresponding to the sample gas to be measured, and separated from the external space A variable partition that forms the sample space together with the inner surface of the main body, a count rate meter that measures a count rate based on the detection signal detected from the sample gas introduced into the sample space, and the measured A radioactivity concentration calculation unit for obtaining the radioactivity concentration of the sample gas based on the count rate and the volume of the sample space.

  A method for monitoring a gas containing a nuclide that emits β-rays according to an embodiment of the present invention includes a hollow main body whose one open end is sealed, and disposed inside the main body to detect β-rays, A β-ray detector for outputting a detection signal, and a partition wall position corresponding to the sample gas to be measured, provided to be movable along the inner surface of the main body at a position facing the detection port of the β-ray detector. The count rate is set based on the detection signal detected from the sample gas introduced into the sample space using a variable partition that is formed with the inner surface of the main body to form a sample space separated from the external space. And measuring the radioactivity concentration of the sample gas based on the measured count rate and the volume of the sample space.

  According to an embodiment of the present invention, a β-ray gas monitor capable of monitoring a radioactivity concentration under a measurement condition suitable for a gas containing a nuclide that emits β rays to be measured, and a nuclide that emits β rays A gas monitoring method is provided.

The lineblock diagram of the beta ray gas monitor concerning a 1st embodiment. (A) is an enlarged view showing the configuration of the sampler section and the partition wall drive section in the first embodiment, and (B) is a II cross-sectional view. The simulation calculation result of the detection efficiency of the beta ray gas monitor concerning this embodiment when the energy of electrons is 0.1, 0.2, 0.3, 0.5, and 1.0 MeV. The graph which showed each detection efficiency by the relative value with the detection efficiency in the setting position of a variable partition wall set to 1 with respect to the calculation result shown in FIG. The flowchart which shows the operation | movement procedure of the beta ray gas monitor which concerns on 1st Embodiment. The lineblock diagram of the beta ray gas monitor concerning a 2nd embodiment. (A) is a diagram setting position of the variable partition wall showing a state of the sampler in L _1, (B) is a diagram setting position of the variable partition wall showing a state of the sampler in L _2. The flowchart which shows the operation | movement procedure of the beta ray gas monitor which concerns on 2nd Embodiment. The block diagram of the sampler part applied to the beta ray gas monitor concerning a 3rd embodiment.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
As shown in FIG. 1, the β-ray gas monitor 10 according to the first embodiment has a sample space formed by a variable partition wall 13 in which a β-ray detector 12 is disposed in a main body 11 and is movable along the inner surface of the main body 11. 14, the sampler unit 15 for introducing the sample gas to be measured, the partition wall drive unit 16 for moving the variable partition wall 13 to the set partition wall position, and the count rate based on the β-ray detection signal s. A counting rate meter 17 and a calculator 18 for calculating the radioactive concentration of the sample gas based on the position setting of the variable partition wall 13 and the measured β ray counting rate are provided.

  The β-ray gas monitor 10 according to the first embodiment is variable to an optimum position for β-ray measurement according to the energy of β-rays emitted from the sample gas (hereinafter, unless otherwise indicated, means average energy). The partition wall 13 is moved to determine the radioactivity concentration of the sample gas.

First, the configuration of the sampler unit 15 and the partition wall drive unit 16 will be described.
FIG. 2A is an enlarged view of the configuration of the sampler unit 15 and the partition wall driving unit 16, and FIG. 2B shows a cross section taken along the line II in FIG.

  The sampler unit 15 includes a main body 11, a β-ray detector 12, a variable partition wall 13, a rear shielding plug 19, an incident window 20, a gas introduction line 21, and a gas discharge line 22.

  The main body 11 is formed in a hollow shape, and one open end is sealed with a back shielding plug 19. The main body 11 is composed of a base 23 made of a material that blocks radiation such as lead and having a cylindrical cavity formed therein, and a protective layer 24 covering the entire surface of the base 23 with a coating material such as iron. Yes.

  The main body 11 can be produced by, for example, hollowing a rectangular parallelepiped lead block into a cylindrical shape and coating the outside and the inside after hollowing with a coating material such as iron.

  As with the main body 11, the back shielding plug 19 is formed by protecting the surface of a substrate made of a material that blocks radiation such as lead with a coating material such as iron. By connecting the rear shielding plug 19 to the open end of the main body 11 by welding or the like, one open end of the main body 11 is sealed.

  The β-ray detector 12 is inserted into the main body 11 with the detection port 25 facing the open side of the main body 11. And it fixes and arrange | positions through the fixing member (illustration omitted) to the side surface of the back shielding plug 19 or the main body 11. FIG.

  The β-ray detector 12 is a cylindrical detector configured by connecting a plastic scintillator that emits fluorescence when β-rays are incident, and a photomultiplier tube that converts the light generated by the scintillator into an electrical signal and outputs it. is there.

  The β-ray detector 12 is accommodated in a detector case 26 in which a circular detection port 25 is formed. The detector case 26 is made of a light shielding material such as aluminum in order to prevent light from entering the detector.

  In the β-ray detector 12, a plastic scintillator is disposed on the detection port 25 side, and a photomultiplier tube is disposed at a position far from the detection port 25.

  The β-ray detector 12 is electrically connected to the counting rate meter 17 (FIG. 1), detects β-rays, and sends a detection signal s generated when the β-rays are detected to the counting rate meter 17. Output. The β-ray detector 12 is supplied with power from the counting rate meter 17.

  Note that the β-ray detector 12 is not limited to a combination of a plastic scintillator and a photomultiplier tube, but an ionization chamber or GM tube that detects β-rays emitted from the gas by converting them into electrical signals. Etc. may be used.

  The entrance window 20 is a circular plate made of a material such as iron, and an opening having a diameter larger than that of the detection port 25 of the β-ray detector 12 is formed at the center position. The incident window 20 is provided in the vicinity of or in contact with the detector case 26 on the detection surface side of the β-ray detector 12 in order to form the boundary of the sample space 14.

  The variable partition wall 13 is a circular plate member having a diameter smaller than the inner diameter of the main body 11 (a diameter that allows the inner surface of the main body 11 to slide). And it arrange | positions in the position which opposes the detection opening 25 of the beta ray detector 12, and the inner surface of the main body 11 is provided so that a movement along the axial direction of the main body 11 is possible.

  As with the main body 11, the surface of the variable partition wall 13 is protected by a partition coating layer 28 made of a coating material such as iron on a partition base 27 made of a material that blocks radiation such as lead.

  The variable partition wall 13 forms a boundary with the outer space together with the inner surface of the main body 11 and the entrance window 20 to form a sample space 14 separated from the outer space.

  The variable partition wall 13 is moved back and forth along the axial direction on the inner surface of the main body 11 by the partition wall drive unit 16, so that the distance from the incident window 20 to the variable partition wall 13 (hereinafter referred to as the partition wall position) and the sample space 14. The volume of can be changed. The partition wall position may be a distance from the detection port 25 of the β-ray detector 12 to the variable partition wall 13.

  The gas introduction line 21 is provided with an open valve that is opened when gas is introduced. Similarly, the gas discharge line 22 is provided with an exhaust pump and an open valve that is opened when the gas is discharged. The illustration of the exhaust pump and the open valves provided in each line is omitted.

  At the time of measuring the radioactivity concentration, the exhaust pump is driven to introduce the sample gas into the sample space 14 via the gas introduction line 21 and fill the sample space 14 with the gas, and the sample via the gas discharge line 22. The sample gas in the space 14 is discharged.

  The partition wall drive unit 16 moves the variable partition wall 13 to a partition position L set by the computer 18 (FIG. 1), a drive shaft 29 connected to the variable partition wall 13, a stepping motor 30 that drives the drive shaft 29 back and forth. And a motor control unit 31 that transmits a position control signal to the stepping motor 30.

  The rotational movement by the stepping motor 30 is converted into a linear movement that moves the variable partition wall 13 forward and backward by the drive shaft 29. Note that, instead of the drive shaft 29 and the stepping motor 30, the variable partition wall 13 may be moved back and forth using a hydraulic or pneumatic cylinder or the like. Instead of setting the partition wall position L from the computer 18, the variable partition wall 13 may be moved to the partition wall position L set by the user by using a configuration in which the motor control unit 31 can accept input by the user.

Returning to FIG. 1, the description will be continued.
The calculator 18 includes an input unit 32, an optimum position information storage unit 33, a partition wall position setting unit 34, a count rate reception unit 35, and a radioactivity concentration calculation unit 36.

  The input unit 32 receives an input of β-ray energy released from the sample gas from the user. Specifically, the β-ray energy of the radionuclide assumed to be included in the sample gas is received from the user based on the correspondence relationship with the β-ray energy generated when each of the radionuclides undergoes β-ray decay. Moreover, it is good also as a structure which receives the kind of radionuclide from a user, and outputs the energy of (beta) ray produced when the nuclide decays (beta) ray to the partition position setting part 34. FIG.

  The optimum position information storage unit 33 obtains the optimum position of the partition wall position L in advance by simulation calculation according to each of the set β-ray energies and stores it as optimum position information. A plurality of β-ray energies to be set are set in a range of β-ray energies expected to be emitted.

  The simulation calculation for obtaining the optimum position information is performed using a Monte Carlo calculation code such as PHITS, MCNP, EGS5, etc., with β-ray energy and partition wall position L as parameters, and a detailed configuration of the sampler unit 15 as a calculation condition. Done. By using these calculation codes, the response of the β-ray detector 12 under complicated setting conditions can be obtained with high accuracy.

  FIG. 3 shows the result of simulation calculation of the detection efficiency of the β-ray gas monitor 10 when the electron energy is 0.1, 0.2, 0.3, 0.5, and 1.0 MeV.

In the simulation calculation, the history of calculation in each setting is set to 100,000 using PHITS which is a Monte Carlo calculation code. The unit of detection efficiency is indicated by cps / (Bq / cm ³ ).

  Further, as the setting conditions of the sampler unit 15, the diameter of the detection port 25 of the β-ray detector 12 is set to 200 mm, the diameter of the opening portion in the incident window 20 is set to 210 mm, and the diameter of the sample space 14 is set to 280 mm. It is supposed to pass on the axis. The thickness of the plastic scintillator of the β-ray detector 12 is 0.25 mm, and the thickness of the protective film is 0.044 mm.

  With such a configuration, the detection efficiency is calculated for each β-ray energy by changing the partition wall position L of the variable partition wall 13.

  FIG. 4 is a graph showing the detection efficiency as a relative value with the detection efficiency when the setting position of the variable partition wall 13 is 100 cm as 1 with respect to the calculation result shown in FIG.

  As can be seen from the result of FIG. 4, for 0.1 MeV having the lowest energy, the detection efficiency is saturated when the position of the variable partition wall 13 is about 10 cm, while the position of the variable partition wall 13 is 10 cm at other energies higher than that. When the partition wall position L is larger (when the position of the variable partition wall 13 is far from the detection port 25), high detection efficiency is obtained.

  In other words, the partition wall position L that is optimal for measurement differs for each β-ray energy, and in the case of a gas that emits low-energy β-rays, high detection efficiency can be obtained even when the partition wall position L is small. Furthermore, since the replacement of the gas in the sample space 14 becomes faster, the response time of the detector can also be made faster.

  On the other hand, in the case of a gas that emits high energy β-rays, increasing the partition wall position L increases the volume of the sample space 14, thereby delaying the response time of the detector but obtaining high detection efficiency. be able to.

  Therefore, when measuring a gas containing a nuclide that emits β-rays with β-ray energy of about 100 keV, the partition wall position L = 10 cm is the optimum position, while β-rays with energy higher than 100 keV are emitted. For the measurement of the gas containing the nuclide, the partition wall position L = 20 cm to 45 cm is the optimum position.

  By performing such a simulation calculation, at least one of the detection efficiency and the detection response time of the β-ray detector 12 becomes higher (exceeds a certain target value) for each of the β-ray energy. Is obtained and stored in the optimum position information storage unit 33.

  The partition wall position setting unit 34 (FIG. 1) refers to the optimum position information stored in the optimum position information storage unit 33 and determines the optimum position corresponding to the input β-ray energy to the partition wall position L of the variable partition wall 13. Set to.

  After the variable partition wall 13 is moved to the partition wall position L set by the partition wall position setting unit 34 and the sample gas is introduced into the sample space 14, the measurement is started.

  The count rate meter 17 measures the count rate based on the β-ray detection signal s detected by the β-ray detector 12. The measured count rate is transmitted to the count rate receiving unit 35 of the computer 18.

  The radioactivity concentration calculation unit 36 calculates the radioactivity concentration of the sample gas based on the measured count rate and the volume of the sample space 14.

  FIG. 5 shows a flowchart showing an operation procedure of the β-ray gas monitor 10 according to the first embodiment (see FIG. 1 as appropriate).

  The optimum position information storage unit 33 calculates the optimum partition wall position according to the set β-ray energy and stores it as optimum position information (S10).

  The input unit 32 receives an input of β-ray energy released from the sample gas from the user (S11).

  The partition wall position setting unit 34 sets a position corresponding to the β-ray energy input with reference to the optimum position information as the partition wall position (S12).

  The partition drive unit 16 moves the variable partition 13 to the set partition position (S13). Then, after the sample gas is introduced into the sample space 14, the measurement is started.

  The count rate meter 17 measures the count rate based on the β-ray detection signal s detected by the β-ray detector 12 (S14).

  The radioactivity concentration calculation unit 36 calculates the radioactivity concentration of the sample gas based on the volume of the sample space 14 corresponding to the partition wall position and the measured count rate (S15).

  Thus, the optimum partition position corresponding to the β-ray energy is obtained by calculation, and the variable partition 13 is moved to the partition position corresponding to the β-ray energy in the gas to be measured, so that the optimum measurement is performed. Radioactivity concentration can be monitored under conditions.

(Second Embodiment)
FIG. 6 shows a configuration diagram of the β-ray gas monitor 10 according to the second embodiment. In FIG. 6, portions having the same configuration or function as those of the first embodiment (FIG. 1) are denoted by the same reference numerals, and redundant description is omitted.

  In the first embodiment, the configuration in which the radioactivity concentration is monitored when the energy of β rays emitted from the gas to be measured is known has been described. On the other hand, in the second embodiment, a method for estimating the energy of β rays emitted from the gas when the nuclide component contained in the gas is unknown will be described.

  From the calculation result of FIG. 4, for example, the ratio of the β ray count rate when the partition wall position of the variable partition wall 13 is 5 cm and the β ray count rate when the partition wall position is 20 cm is high when the energy of the β ray is high. It can be seen that the difference between the low case and the low case. That is, the ratio of the β ray count rate between the partition walls has a different value depending on the energy of the β ray.

  Using this property, in the second embodiment, β-ray count rates are measured at a plurality of partition wall positions, and β-ray energy is estimated based on the ratio of β-ray count rates between partition wall positions.

  The computer 18 according to the second embodiment further includes a partition wall position changing unit 37, a data association unit 38, a ratio calculation unit 39, a correlation information storage unit 40, a collation unit 41, and a display unit 42.

  The partition wall position changing unit 37 sets a plurality of partition wall positions. The partition wall position changing unit 37 changes the setting to the next partition wall position after the variable partition wall 13 is moved to the set partition wall position and the concentration measurement is completed.

  The data association unit 38 associates the set partition wall position with the count rate measured at each partition wall position.

  The ratio calculator 39 calculates the ratio of the count rate between the partition positions after the measurement is completed at the partition positions at a plurality of positions.

  The correlation information storage unit 40 (FIG. 6) obtains the ratio of the count rate between the set partition wall positions by simulation calculation in advance according to each of the β-ray energy and stores it as correlation information. The partition wall position set in the simulation calculation is set to the same position as the position set by the partition wall position changing unit 37.

  The simulation calculation for obtaining the correlation information is the same as the above-mentioned optimum position information, and the Monte Carlo calculation such as PHITS, MCNP, EGS5, etc. with the detailed configuration of the sampler unit 15 as the calculation condition using the β-ray energy and the partition wall position as parameters. Use code.

  The collating unit 41 collates the ratio calculated by the ratio calculating unit 39 with the correlation information ratio between the same partition wall positions, and outputs β-ray energy corresponding to the matching ratio. The display unit 42 displays the output β-ray energy as an estimated value.

The process of deriving the β-ray energy by deriving the count rate ratio will be specifically described with reference to FIG. Here, a case where the partition wall positions are set at two locations L ₁ and L ₂ by the partition wall position changing unit 37 will be considered.

Figure 7 (A) shows the state of the sampler section 15 when the partition wall position is L _1, FIG. 7 (B) shows a state of the sampler section 15 in the case where the partition wall position is L _2.

First, when the partition position is set to L ₁ by the partition position changing unit 37, the sample gas is introduced into the sample space A ₁ after the movement of the partition is completed. Then, the counting rate based on the β-ray detection signal s ₁ is measured. The data association unit 38 associates the count rate based on the detection signal s ₁ corresponding to the partition wall position L ₁ .

After the measurement of the partition position is in L _1, the partition wall position by a partition position changing part 37 is changed to L _2, after the movement of the partition wall is completed, the sample gas is introduced into the sample space A _2. Then, the counting rate based on the β-ray detection signal s ₂ is measured. The data association unit 38 associates a count rate based on the detection signal s ₂ corresponding to the partition wall position L ₂ .

Ratio calculation unit 39 calculates the ratio of the count rates at the bulkhead position L ₁ and the partition position L _2.
The collation unit 41 collates the ratio calculated by the ratio calculation unit 39 with the ratio of the count rate between the partition wall positions L ₁ and L ₂ stored for each β-ray energy by the correlation information storage unit 40. . Then, the collation unit 41 outputs β-ray energy corresponding to the matching ratio.

  In addition, it is desirable that the partition positions set by the partition position changing unit 37 be set to more positions because the accuracy of the collation is increased by acquiring a plurality of ratios.

  FIG. 8 shows a flowchart showing an operation procedure of the β-ray gas monitor 10 according to the second embodiment (see FIG. 6 as appropriate).

  The correlation information storage unit 40 calculates the ratio of the count rate between the set partition wall positions in advance according to each β-ray energy and stores it as correlation information (S20).

  The partition wall position changing unit 37 changes the partition wall position of the variable partition wall 13. At this time, the counting rate of β rays is measured at each changed partition wall position (S21).

  The data association unit 38 associates the set partition wall positions with the count rate measured at each partition wall position (S22).

  The ratio calculator 39 calculates the ratio of the count rate between the partition wall positions (S23).

  The collation unit 41 collates the calculated ratio with the ratio of the correlation information between the same partition wall positions (S24).

  The collation unit 41 outputs β-ray energy corresponding to the matching ratio (S25). The display unit 42 displays the output β-ray energy as an estimated value.

  As described above, the β-ray count rate is measured at a plurality of partition wall positions, and the β-ray count rate ratio between the partition wall positions is obtained, whereby the unknown β-ray energy can be estimated.

  In addition, the correlation information storage unit 40 may calculate the ratio of the count rate between the set partition wall positions in advance according to each of the continuous energies of different radionuclides and store it as correlation information.

  In this case, the collating unit 41 can estimate the radionuclide by collating the ratio calculated by the ratio calculating unit 39.

  Alternatively, the correlation information storage unit 40 calculates in advance the ratio of the counting rate between the partition walls according to each of the set composition ratios of the radionuclides on the assumption that a plurality of types of radionuclides are mixed in the sample gas. And may be stored as correlation information. In addition, the continuous energy when a plurality of types of radionuclides coexist is calculated by a combination of continuous energies of individual radionuclides.

  And the collation part 41 collates the ratio calculated in the ratio calculation part 39 with the ratio of the correlation information between the same partition positions, and outputs the composition ratio corresponding to the matching ratio.

  In this way, by measuring the β-ray count rate at a plurality of partition wall positions and obtaining the ratio of the β-ray count rate between the partition wall positions, it is possible to estimate the radionuclide or the composition ratio when multiple types of radionuclides are mixed. Can also be estimated.

(Third embodiment)
FIG. 9 shows a configuration diagram of the sampler unit 15 applied to the β-ray gas monitor 10 according to the third embodiment. In addition, since the whole structure of the beta ray gas monitor 10 in 3rd Embodiment becomes the same as 2nd Embodiment (FIG. 6), description is abbreviate | omitted and description is abbreviate | omitted about the overlapping structure or function.

  The β-ray gas monitor 10 according to the third embodiment has a check valve 43 in each of the gas introduction line 21 for introducing the sample gas into the sample space 14 and the gas discharge line 22 for discharging the sample gas from the sample space 14. .

  By having the check valve 43, intake and exhaust can be automatically performed by the back and forth movement of the variable partition wall 13. Thereby, the pump for exhaust_gas | exhaustion is abbreviate | omitted and the structure of the beta ray gas monitor 10 can be simplified.

  In addition, when the β ray count rate is measured at a plurality of partition wall positions and the β ray count rate ratio between the partition wall positions is obtained as in the second embodiment, acquisition of the count rate can be continuously obtained. Thereby, estimation of β-ray energy can be performed in a short time.

  According to the β-ray monitor of each embodiment described above, the optimum partition wall position corresponding to the β-ray energy is obtained by calculation, and the variable partition wall is located at the partition wall position corresponding to the β-ray energy of the gas to be measured. By moving 13, the radioactivity concentration can be monitored under measurement conditions suitable for a gas containing a nuclide that emits β-rays to be measured. Even if the β-ray energy is unknown, the β-ray energy can be estimated based on the ratio of the count rates measured by a plurality of sample volumes.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  Each configuration of the computer 18 may be realized by executing a predetermined program code in an electronic circuit such as a processor, and is not limited to such software processing. For example, an electronic circuit such as an ASIC is used. It may be configured as a unit or computer realized by hardware processing, or may be configured as a unit or computer realized by combining software processing and hardware processing.

10 ... beta ray gas monitor, 11 ... main body, 12 ... beta-ray detector, 13 ... variable partition wall, 14 ₍₁₄ 1, 14 ₂₎ ... sample space, 15 ... sampler, 16 ... partition wall driving unit, 17 ... counting rate meter , 18 ... computer, 19 ... back shielding plug, 20 ... entrance window, 21 ... gas introduction line, 22 ... gas discharge line, 23 ... base, 24 ... protective layer, 25 ... detection port, 26 ... detector case, 27 ... Partition base, 28 ... partition coating layer, 29 ... drive shaft, 30 ... stepping motor, 31 ... motor control unit, 32 ... input unit, 33 ... optimum position information storage unit, 34 ... partition position setting unit, 35 ... count rate reception , 36 ... Radioactivity concentration calculation part, 37 ... Partition position changing part, 38 ... Data association part, 39 ... Ratio calculation part, 40 ... Correlation information storage part, 41 ... Collation part, 42 ... Display part, 43 ... Check Valve, 39 ... ratio calculation unit, 40 ... Seki information storage section, 41 ... matching section, 42 ... display unit, 43 ... check _{valve, s (s 1, s 2} ) ... detection _{signal, L (L 1, L 2} ) ... bulkhead position.

Claims (9)

A hollow body with one open end sealed;
A β-ray detector that is arranged inside the main body, detects β-rays, and outputs a detection signal;
The β-ray detector is provided so as to be movable along the inner surface of the main body at a position facing the detection port of the β-ray detector, set to a partition position corresponding to the sample gas to be measured, and separated from the external space. A variable partition that forms a sample space with the inner surface of the body;
A count rate meter that measures a count rate based on the detection signal detected from the sample gas introduced into the sample space;
A β-ray gas monitor, comprising: a radioactivity concentration calculation unit that obtains the radioactivity concentration of the sample gas based on the measured count rate and the volume of the sample space.   The β-ray gas monitor according to claim 1, further comprising a partition drive unit that moves the variable partition to the partition position. An optimum position information storage unit for obtaining the optimum position of the partition wall in advance by calculation according to each of the set β-ray energies and storing it as optimum position information;
The partition position setting unit configured to set the optimum position corresponding to the energy of β rays in the input sample gas to the partition position with reference to the optimum position information. The β-ray gas monitor according to claim 1 or 2. A partition wall position changing section for setting a plurality of the partition wall positions;
A data association unit that associates the set partition wall positions with the count rate measured at each partition wall position;
4. The β-ray gas monitor according to claim 1, further comprising: a ratio calculation unit that calculates a ratio of the count rate between the partition wall positions. 5. A correlation information storage unit that determines the ratio of the counting rate between the partition wall positions according to each of the set β-ray energies and stores it as correlation information;
A collation unit that collates the ratio calculated by the ratio calculation unit with the ratio of the correlation information between the same partition wall positions, and outputs β-ray energy corresponding to the matching ratio; The β-ray gas monitor according to claim 4, wherein A correlation information storage unit for determining the ratio of the counting rate between the partition wall positions according to each of the continuous energies of different radionuclides and storing it as correlation information;
A collation unit that collates the ratio calculated by the ratio calculation unit with a ratio of the correlation information between the same partition wall positions, and outputs the radionuclide corresponding to the matching ratio; The β-ray gas monitor according to claim 4. Assuming that the ratio of the counting rate between the partition wall positions is a plurality of radionuclides in the sample gas, a correlation information storage unit that obtains and stores as correlation information according to each of the composition ratios of the radionuclides; ,
A collation unit that collates the ratio calculated by the ratio calculation unit with a ratio of the correlation information between the same partition wall positions, and outputs the composition ratio corresponding to the matching ratio; The β-ray gas monitor according to claim 4.   8. A check valve is provided in each of a gas introduction line for introducing the sample gas into the sample space and a gas discharge line for discharging the sample gas from the sample space. The β-ray gas monitor according to one item. A hollow main body with one open end sealed, a β-ray detector arranged inside the main body for detecting β-rays and outputting a detection signal, and facing a detection port of the β-ray detector A sample space separated from the external space is formed together with the inner surface of the main body by being set at a partition wall position corresponding to the sample gas to be measured. With a variable bulkhead,
Measuring a counting rate based on the detection signal detected from the sample gas introduced into the sample space;
Obtaining a radioactivity concentration of the sample gas based on the measured count rate and the volume of the sample space, and a method for monitoring a gas containing a nuclide that emits β rays.

Images