JP2013104745A - Moisture concentration measuring apparatus, measuring method thereof, hydrogen gas concentration measuring system, and measuring method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moisture concentration measuring apparatus and a measuring method thereof dispensing with dehumidification of gas and sampling from the outside of a reactor container.SOLUTION: A moisture concentration measuring apparatus 30 according to one embodiment causes a plurality of γ-ray detectors 3 to detect γ rays generated by pair annihilation caused by collision of a positron emitted from a positron source 1 in a reactor container 70 with a water molecule contained in an atmosphere. A coincidence circuit 5 outside the reactor container 70 measures the γ rays detected by the plurality of γ-ray detectors 3 in time series and identifies the locations of the γ-ray detectors that have detected the pair of two γ rays generated by the pair annihilation. A first signal processing unit 6a calculates a range of the positron from the identified γ-ray detectors and obtains the concentration of water molecule on the basis of the correlation between the concentration of water molecule and the range of the positron.

Description

  Embodiments described herein relate generally to a moisture concentration measuring device and a measuring method thereof, and a hydrogen gas concentration measuring system and a measuring method thereof.

In general, the atmosphere monitor in a nuclear reactor containment vessel measures radiation, hydrogen gas (H ₂ ) concentration, oxygen gas (O ₂ ) concentration, etc., mainly for the purpose of measurement at the time of an accident Yes. Among these, for the hydrogen gas concentration measurement, the gas inside the reactor containment vessel is drawn out of the reactor containment vessel by the sampling device, cooled and dehumidified, and then passed through a hydrogen gas analyzer to analyze the hydrogen gas concentration doing.

  However, it is necessary to dehumidify the gas so that it can be measured with such a hydrogen gas analyzer. Moreover, measurement may be impossible for a loss of cooling water source for cooling and dehumidification or gas conditions exceeding the design specifications. In addition, it is necessary to draw the gas to be sampled outside the reactor containment vessel in order to perform cooling and dehumidification, and measurement may not be possible due to external factors such as damage to the sampling pipe or loss of the AC power supply of the sampling pump.

  In the gas concentration measuring device that measures the concentration of the component gas present in the reactor containment vessel, the gas present in the reactor containment vessel is taken out by a sample pump or the like and the gas is cooled and dehumidified. And the like, and the component concentration is measured with an analyzer, and after the measurement, the gas is returned into the reactor containment vessel with a return pump.

Japanese Patent Publication No. 4-14318

  In the hydrogen gas analyzer described above, when measuring the concentration of hydrogen gas, it is necessary to draw the gas to be sampled outside the reactor containment vessel. In addition, before measurement with a hydrogen gas analyzer, it is necessary to cool and dehumidify the gas drawn out to remove water molecules. Furthermore, since it is a polluted gas, it must be returned to the reactor containment vessel after measurement. For this reason, a cooling water source for dehumidification and a sampling pipe for extracting and returning gas are required. In the event of an accident, it is affected by external factors such as damage to the sampling pipe, loss of the cooling water source, loss of AC power source such as pumps, etc. Thus, it becomes difficult to measure the concentration of hydrogen gas.

On the other hand, when measuring the hydrogen gas concentration without dehumidification, it is important to know the moisture (H ₂ O concentration) in the atmosphere, but the moisture in the reactor containment vessel even under the high temperature environment at the time of the accident No device is known that can measure the concentration of

  The problem to be solved by the present invention has been made in response to the above-described circumstances, and provides a moisture concentration measuring apparatus and a measuring method thereof that do not require gas dehumidification and sampling outside the reactor containment vessel. There is to do.

  Another object of the present invention is to provide a hydrogen gas concentration measurement system that does not require gas dehumidification and sampling outside the reactor containment vessel, and a measurement method therefor.

  In order to solve the above-described problem, the moisture concentration measuring device according to the embodiment is a moisture concentration measuring device that measures the concentration of water molecules contained in the atmosphere in the reactor containment vessel. The moisture concentration measuring device includes a positron source that is disposed in the reactor containment vessel and generates positrons, and a water that is disposed in the reactor containment vessel and contains positrons emitted from the positron source in the atmosphere. A plurality of γ-ray detectors arranged side by side along the positron emission direction to detect γ-rays generated by pair annihilation caused by collision with molecules; and two of the plurality of γ-ray detectors When the γ-ray detector detects γ-rays at the same time, the coincidence counting circuit disposed outside the reactor containment vessel that analyzes the positions of the two γ-ray detectors, and the two γ-rays The position of the pair annihilation is determined as a position where a straight line connecting the positions of the detectors and the passage through which the positron passes, thereby calculating the range of the positron as the distance from the positron source to the position of the pair annihilation. Outside the reactor containment vessel And the range of the water molecules calculated from the range of the positrons calculated by the range calculation unit based on the correlation previously determined between the range of water molecules and the range of water molecules and the range of positrons. And a moisture concentration calculation unit arranged outside the reactor containment vessel for calculating the concentration.

  Further, the moisture concentration measuring method of the embodiment is a moisture concentration measuring method for measuring the concentration of water molecules contained in the atmosphere in the reactor containment vessel. The moisture concentration measurement method includes a plurality of γ-ray detectors arranged side by side in a positron emission direction in the reactor containment vessel, and positrons emitted from a positron source arranged in the reactor containment vessel. Γ-ray detection processing step for detecting γ-rays generated by pair annihilation caused by collision with water molecules contained in the atmosphere, and after the γ-ray detection processing step, two of the plurality of γ-ray detectors When the γ-ray detectors detect γ-rays simultaneously, a coincidence processing step for analyzing the positions of the two γ-ray detectors, and after the coincidence processing step, the two analyzed The position of the pair annihilation is determined as a position where a straight line connecting the positions of the γ-ray detectors and the passage through which the positron passes, and thereby the range of the positron as the distance from the positron source to the position of the pair annihilation Calculated range After the calculation processing step and the range calculation processing step, based on the correlation obtained in advance between the concentration of water molecules and the range of positrons, the concentration of the water molecules from the calculated range of the positrons And a moisture concentration calculation processing step for calculating

  The hydrogen gas concentration measurement system according to the embodiment includes a moisture concentration measurement device, a hydrogen atom concentration measurement device, and a hydrogen gas concentration calculation unit, and measures the concentration of hydrogen gas contained in the atmosphere in the reactor containment vessel. This is a hydrogen gas concentration measurement system. In the hydrogen gas concentration measuring system, the moisture concentration measuring device is disposed in the reactor containment vessel and generates a positron, and is disposed in the reactor containment vessel and emitted from the positron source. A plurality of γ-ray detectors arranged side by side along the positron emission direction to detect γ-rays generated by pair annihilation generated by collision of positrons with water molecules contained in the atmosphere, and the plurality of γ-rays A coincidence counting circuit disposed outside the containment vessel for analyzing the positions of the two gamma ray detectors when two gamma ray detectors of the detectors simultaneously detect gamma rays. And the position of the pair annihilation is determined as a position where a straight line connecting the positions of the two γ-ray detectors and a passage through which the positron passes, and thereby a distance from the positron source to the position of the pair annihilation Positron Calculated by the range calculation unit based on a predetermined correlation between the range of the water molecule and the range of the positrons, and the range calculation unit arranged outside the reactor containment vessel. A water concentration calculation unit disposed outside the reactor containment vessel for calculating the concentration of the water molecules from the range of the positrons, and the hydrogen atom concentration measuring device is provided in the reactor containment vessel. The concentration of hydrogen atoms contained in the atmosphere is measured, and the hydrogen gas concentration calculation unit is configured so that the concentration of water molecules measured from the moisture concentration measuring device and the concentration of hydrogen atoms measured from the hydrogen atom concentration measuring device are measured. Based on the above, the concentration of hydrogen gas in the reactor containment vessel is calculated and arranged outside the reactor containment vessel.

  In addition, the hydrogen gas concentration measurement method of the embodiment is a hydrogen gas concentration measurement method for measuring the concentration of hydrogen gas contained in the atmosphere in the reactor containment vessel. The hydrogen gas concentration measuring method was emitted from a plurality of γ-ray detectors arranged side by side in the positron emission direction in the reactor containment vessel from a positron source arranged in the reactor containment vessel. Γ-ray detection processing step for detecting γ-rays generated by pair annihilation caused by collision of positrons with water molecules contained in the atmosphere, and after the γ-ray detection processing step, of the plurality of γ-ray detectors When two γ-ray detectors detect γ-rays at the same time, a coincidence processing step for analyzing the positions of the two γ-ray detectors, and after the coincidence processing step, the analyzed 2 The position of the pair annihilation is determined as a position where a straight line connecting the positions of the γ-ray detectors and a passage through which the positron passes, and thereby the range of the positron as the distance from the positron source to the position of the pair annihilation Calculate After the range calculation processing step and the range calculation processing step, based on the correlation obtained in advance between the concentration of water molecules and the range of positrons, from the calculated range of the positrons, A moisture concentration calculation processing step for calculating a concentration, and heat generated by collision of fast neutrons emitted from a neutron source arranged in the reactor containment vessel with a gas contained in the atmosphere in the reactor containment vessel A thermal neutron detection processing step for detecting neutrons, a hydrogen atom concentration calculation processing step for calculating the concentration of the hydrogen atoms based on the detected thermal neutrons after the thermal neutron processing step, and the moisture concentration calculation processing step And after the hydrogen atom concentration calculation processing step, based on the calculated concentration of the water molecule and the calculated concentration of the hydrogen atom, Characterized in that it comprises a hydrogen gas concentration calculation processing step of calculating the concentration of hydrogen gas in the inner, the.

  According to the embodiment of the moisture concentration measuring apparatus according to the present invention, the concentration of water molecules can be measured without performing dehumidification of gas and sampling outside the reactor containment vessel.

  Moreover, according to the embodiment of the moisture concentration measuring method according to the present invention, the concentration of water molecules can be measured without performing dehumidification of gas and sampling outside the reactor containment vessel.

  Further, according to the embodiment of the hydrogen gas concentration measurement system of the present invention, the concentration of hydrogen gas can be measured without performing dehumidification of gas and sampling outside the reactor containment vessel.

  Further, according to the embodiment of the hydrogen gas concentration measuring method according to the present invention, the concentration of hydrogen gas can be measured without performing dehumidification of gas and sampling outside the reactor containment vessel.

The block diagram in embodiment of the hydrogen gas concentration measurement system which concerns on this invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. The block diagram of the hydrogen atom concentration measuring apparatus in embodiment of FIG.

  Hereinafter, a hydrogen gas concentration measurement system according to an embodiment of the present invention will be specifically described with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and redundant description is omitted. The following embodiment described here will be described by taking an example of a hydrogen gas concentration measurement system in a reactor containment vessel.

  Hereinafter, an embodiment of a hydrogen gas concentration measurement system according to the present invention will be described with reference to FIGS. 1 to 3. The hydrogen gas concentration measurement system of the embodiment is for measuring the hydrogen gas concentration in a reactor containment vessel 70 that stores a nuclear reactor 71, and includes a water concentration measurement device 30 and a hydrogen atom concentration measurement device 50. I have. Here, FIG. 1 and FIG. 2 are configuration diagrams mainly of the moisture concentration measuring device 30 in the embodiment, and in particular, FIG. 1 shows a part of the moisture concentration measuring device 30 in a longitudinal sectional view, and FIG. FIG. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 3 shows the configuration of the hydrogen atom concentration measuring apparatus 50 shown in FIG.

  As shown in FIG. 1, the moisture concentration measuring device 30 of the embodiment includes a positron source 1, a collimator 2, a plurality of γ-ray detectors 3, a first inter-unit cable 4a, and first to fourth units. γ-ray detector cable groups 41a, 41b, 41c and 41d, a coincidence counting circuit 5, a first signal processing unit 6a, and a first shielding body 7a are provided.

  The positron source 1, the collimator 2, the plurality of γ-ray detectors 3, and the first shielding body 7 a are installed in the space above the reactor 71 inside the reactor containment vessel 70, for example. On the other hand, the coincidence counting circuit 5, the first signal processing unit 6a, and the first inter-unit cable 4a are installed outside the reactor containment vessel 70.

  The first to fourth γ-ray detector cable groups 41a, 41b, 41c, and 41d extend through the wall of the reactor containment vessel 70 to the inside and outside thereof.

  The first shielding body 7a is a container having an opening. The first shielding body 7a prevents the radiation radiated in the reactor containment vessel 70 outside the first shielding body 7a from being transmitted into the first shielding body 7a. For this purpose, the first shielding body 7a is made of a material such as lead (Pb) that can shield radiation such as γ rays, and is formed in a cylindrical shape, for example.

  The first shielding body 7a is disposed in the reactor containment vessel 70 so as to cover the positron source 1, the collimator 2, the plurality of γ-ray detectors 3 and the like. The opening of the first shielding body 7 a does not face the reactor 71 and opens toward the wall of the reactor containment vessel 70. Thereby, the 1st shielding body 7a is preventing that the gamma ray which flies from the exterior of the 1st shielding body 7a is detected with the some gamma ray detector 3. FIG.

The positron source 1 generates positrons. Positron source 1 is a radioisotope element that decays by β ⁺ , and ²² Na or the like is used.

  The collimator 2 emits positrons in a predetermined positron emission direction 21 from the positrons generated from the positron source 1. For the collimator 2, lead (Pb), tungsten (W), or the like provided with one linear through hole is used.

  The plurality of γ-ray detectors 3 detect γ-rays in each detector. The plurality of γ-ray detectors 3 are arranged along the positron emission direction 21 in order to detect γ-rays generated by pair annihilation generated when the positrons emitted from the positron source 1 collide with water molecules contained in the atmosphere. Be placed.

  Specifically, as shown in FIGS. 1 and 2, the plurality of γ-ray detectors 3 are arranged in a ring shape on a plane perpendicular to the positron emission direction 21 defined by the collimator 2, and further, a plurality of rings Are arranged in a row along the positron emission direction 21. A plurality of γ-ray detectors 3 that can operate even at high temperatures during an accident are used. For example, a scintillation detector, a cloud chamber, or the like is used.

  Hereinafter, the configuration of the plurality of γ-ray detectors 3 will be described in detail with reference to FIGS. 1 and 2.

  FIG. 2 shows one ring-shaped arrangement among the plurality of γ-ray detectors 3 in the cross section of the first shielding body 7a of FIG. As shown in FIG. 2, the plurality of γ-ray detectors 3 are arranged at regular intervals from the center Pc on the central axis of the container of the first shielding body 7a, for example, γ-ray detectors 31a, 32a, 33a,. -311a and 312a (31a-312a) are made into the gamma ray detector group 3a of a ring. The ring γ-ray detector groups 3a are arranged, for example, on the same circumference and at equal intervals.

  Similarly to the γ-ray detectors 31a to 312a (also referred to as 31a to 37a) of the ring γ-ray detector group 3a, γ-ray detectors 31b to 37b, γ-ray detectors 31c to 37c, and γ-ray detection The γ-ray detector groups 3 b, 3 c and 3 d of each ring comprising the devices 31 d to 37 d are further arranged in a line along the positron emission direction 21. The number of γ-ray detectors shown in FIG. 1 and FIG. 2 is schematically shown for ease of explanation, and the number of detectors arranged in a ring and in the column direction are shown. The number of rings is not limited to this embodiment.

  Between the plurality of γ-ray detectors 3 and the coincidence counting circuit 5, first to fourth γ-ray detector cable groups 41a, 41b, 41c and 41d are connected. For example, one end of a corresponding cable in the first γ-ray detector cable group 41a shown in FIG. 1 is connected to each of the γ-ray detectors (31a to 37a) of the γ-ray detector group 3a of the ring shown in FIG. Are connected and the other end is connected to the coincidence counting circuit 5. Γ-ray detectors (31b to 37b˜) of the other ring γ-ray detector group 3b, γ-ray detectors (31c to 37c˜) of the ring γ-ray detector group 3c, and ring γ-ray detector group 3d Similarly, the second γ-ray detector cable group 41b, the third γ-ray detector cable group 41c, and the fourth γ-ray detector cable group 41d are also provided for the γ-ray detectors (31d to 37d). It is connected. These first to fourth γ-ray detector cable groups 41a, 41b, 41c, and 41d extend through the wall of the reactor containment vessel 70 to the inside and outside thereof.

  Further, a first inter-unit cable 4a is connected between the coincidence counting circuit 5 and the first signal processing unit 6a. The first inter-unit cable 4 a is laid outside the reactor containment vessel 70.

  The coincidence circuit 5 measures γ-rays detected by a plurality of γ-ray detectors 3 in time series, and identifies a γ-ray detector that detects two pairs of γ-rays generated by pair annihilation. . The coincidence circuit 5 is disposed outside the reactor containment vessel 70.

  The coincidence circuit 5 sequentially receives γ-ray detection signals from the plurality of γ-ray detectors 3 through the first to fourth γ-ray detector cable groups 41a to 41d. The coincidence circuit 5 calculates a detection signal detected at the same time by time series comparison based on these received detection signals, and refers to the positions of the plurality of γ-ray detectors 3 stored in advance. Thus, the position of the detector that has detected two pairs of γ rays generated by pair annihilation is specified. In the coincidence circuit 5, for example, when comparing the same time when γ-rays are detected, each cable of the first to fourth γ-ray detector cable groups 41a to 41d from the reception time of the received detection signal. The propagation delay time due to the length may be corrected and calculated.

  Specifically, the coincidence counting circuit 5 includes, for example, a plurality of γ-ray detectors 3 positioned on different rings or on the same ring on the circumference of a circle having a center Pc as shown in FIG. By projecting, two γ-ray detectors that are paired are identified. For example, in the example shown in FIGS. 1 and 2, two γ-rays that are paired are simultaneously detected from the γ-ray detector 37b and the γ-ray detector 31c that are positioned in directions opposite to each other by 180 degrees. Is determined.

  The coincidence circuit 5 is configured by combining, for example, circuits having functions such as filter processing, peak detection processing, logical operation processing, and storage processing. In this case, the coincidence circuit 5 is a circuit having a processing capability such as sufficient time resolution and frequency resolution for the detection signal to be time-series processed.

  As described above, the coincidence counting circuit 5 analyzes the positions of the two γ-ray detectors when two γ-ray detectors of the plurality of γ-ray detectors 3 simultaneously detect the γ-rays. Can do.

  The first signal processing unit 6 a receives the analysis information of the positions of the two γ-ray detectors identified from the coincidence counting circuit 5. For this purpose, the first signal processing unit 6a includes a range calculation unit 61a, a moisture concentration calculation unit 62a, and a conversion table 63a.

  The range calculation unit 61a determines the position of the pair annihilation as the position where the straight line connecting the positions of the two γ-ray detectors as a pair specified by the coincidence circuit 5 and the path through which the positron passes.

  For example, the range calculation unit 61a projects a plurality of γ-ray detectors 3 on a surface in a direction perpendicular to the positron emission direction 21, and on the surface on which the positions of two paired γ-ray detectors are projected. In the case of the diagonal direction, the pair annihilation position Xs is determined from the positions of the two γ-ray detectors.

  Thereby, the range calculation part 61a calculates the range of a positron as a distance from the positron source 1 to the pair annihilation position Xs.

  The water concentration calculation unit 62a calculates the concentration of water molecules from the range of positrons calculated by the range calculation unit 61a based on the correlation obtained in advance between the concentration of water molecules and the range of positrons. For example, the correlation previously obtained between the concentration of water molecules and the range of positrons is stored in the conversion table 63a as described later.

The conversion table 63a stores data on the correlation between the concentration of water molecules and the range of positrons. These data are prepared and stored in advance in the conversion table 63a. For example, the atmosphere in the reactor containment vessel 70 at the time of an accident mainly contains nitrogen gas (N ₂ ), hydrogen gas (H ₂ ), oxygen gas (O ₂ ), and water molecules (H ₂ O). Is assumed. In such a case, since the scattering cross section with the positron is the largest for water molecules, the range of the positron strongly depends on the concentration of water molecules contained in the gas. For this reason, a correlation between the concentration of water molecules and the range of positrons is obtained in advance, and data about this correlation is stored in advance in the conversion table 63a.

  Thereby, the moisture concentration calculation part 62a can obtain | require the density | concentration of a water molecule from the range of a positron based on the data stored in the conversion table 63a. A conversion formula or the like may be used instead of the conversion table 63a.

  FIG. 3 is a configuration diagram of the hydrogen atom concentration measuring apparatus 50 of the embodiment shown in FIG. The hydrogen atom concentration measuring apparatus 50 of the embodiment includes a neutron source 10, a neutron detector 11, a neutron detector cable 42, a second signal processing unit 6b, and a second shielding body 7b. .

The hydrogen atom concentration measuring device 50 measures the concentration of hydrogen atoms (H) in the atmosphere containing water molecules (H ₂ O), hydrogen gas (H ₂ ), etc. in the reactor containment vessel 70.

  The second shielding body 7b is disposed in the vicinity of the first shielding body 7a in the reactor containment vessel 70, and the neutron source 10 and the neutron source so as to shield radiation from outside the second shielding body 7b. The detector 11 is covered. The second shielding body 7b is made of a material such as lead (Pb), for example, and is formed in a cylindrical shape so as to have an opening.

  The opening of the second shielding body 7 b does not face toward the reactor 71 and opens toward the wall of the reactor containment vessel 70. Thus, the second shielding body 7b prevents thermal neutrons flying from the outside of the second shielding body 7b from being detected by the neutron detector 11.

The neutron source 10 is a radioisotope element that emits fast neutrons, and ²⁵² Cf or the like is used.

The neutron detector 11 detects thermal neutrons generated when fast neutrons emitted from the neutron source 10 collide with gas contained in the atmosphere in the reactor containment vessel 70. The neutron detector 11 is a device that detects thermal neutrons, and a ³ He counter tube or the like is used.

  The neutron detector cable 42 is connected between the neutron detector 11 and the second signal processing unit 6b. This neutron detector cable 42 penetrates the wall of the reactor containment vessel 70 and extends in and out.

  The second signal processing unit 6 b receives a thermal neutron detection signal from the neutron detector 11 through the neutron detector cable 42. The second signal processing unit (hydrogen atom concentration calculator) 6b calculates the concentration of hydrogen atoms based on the detected thermal neutron detection signal. The second signal processing unit 6 b is installed outside the reactor containment vessel 70.

  The second inter-unit cable 4b is connected between the first signal processing unit 6a and the third signal processing unit 6c. The third signal processing unit 6c receives information on the concentration of water molecules calculated from the first signal processing unit 6a through the second inter-unit cable 4b.

  The third inter-unit cable 4c is connected between the second signal processing unit 6b and the third signal processing unit 6c. The third signal processing unit 6c receives information on the hydrogen atom concentration calculated from the second signal processing unit 6b through the third inter-unit cable 4c.

  The third signal processing unit (hydrogen gas concentration calculation unit) 6c is based on the concentration of water molecules calculated from the water concentration measurement device 30 and the concentration of hydrogen atoms calculated from the hydrogen atom concentration measurement device 50. The concentration of hydrogen gas in the reactor containment vessel 70 is calculated. The third signal processing unit 6 c is installed outside the reactor containment vessel 70.

Here, since the hydrogen atom (H) has a higher neutron moderating ability than other atoms, the thermal neutron detection intensity is a hydrogen atom contained in hydrogen molecules (H ₂ ) and water molecules (H ₂ O) in the gas. It strongly depends on the concentration of (H). For this reason, the correlation between the concentration of hydrogen atoms contained in the gas and the detected thermal neutron intensity is obtained in advance, and the second signal processing unit 6b includes the detected thermal neutron intensity in the gas based on this correlation. The concentration of hydrogen atoms can be determined.

  In the above description, the operation and effect in the case where the neutron source 10 is installed inside the reactor containment vessel 70 have been described. However, neutrons that emit fast neutrons having energy that can pass through the partition walls of the reactor containment vessel 70. Even if the source 10 is installed outside the reactor containment vessel 70, the same operation and effect can be obtained.

The third signal processing unit 6c uses the concentration of water molecules calculated by the first signal processing unit 6a and the concentration of hydrogen atoms (H) calculated by the second signal processing unit 6b to generate gas. The concentration of hydrogen gas (H ₂ ) is calculated. That is, hydrogen in the gas is calculated from the concentration of water molecules (H ₂ O) in the gas determined by the moisture concentration measuring device 30 and the concentration of hydrogen atoms (H) in the gas determined by the hydrogen atom concentration measuring device 50. The concentration of gas (H ₂ ) can be determined.

  Next, the flow of processing in the hydrogen gas concentration measurement system of the embodiment will be described.

  In the moisture concentration measuring device 30, a large number of positrons emitted from the positron source 1 are cut out in a beam shape by the collimator 2. The positrons that have passed through the holes of the collimator 2 repeatedly collide with electrons contained in the gas in the reactor containment vessel 70 to gradually lose kinetic energy, and finally combine with surrounding electrons to cause pair annihilation. . Simultaneously with the occurrence of the pair annihilation, two γ rays having an energy of about 511 eV equal to the total mass energy are emitted in directions opposite to each other at 180 degrees.

  Two γ-rays that form a pair emitted by pair annihilation are detected by any one of the plurality of γ-ray detectors 3. When a plurality of γ-ray detectors 3 detect these γ-rays, the detected γ-ray detectors transmit a detection signal to the coincidence counting circuit 5 through the first to fourth γ-ray detector cable groups 41a to 41d. To do.

  The coincidence circuit 5 analyzes the detection positions of the two γ-rays detected at the same time based on the detection signals transmitted through the first to fourth γ-ray detector cable groups 41a to 41d. The coincidence circuit 5 transmits this result as analysis information to the first signal processing unit 6a.

  For example, as shown in FIG. 2, the range calculation unit 61a of the first signal processing unit 6a uses the analysis information of the γ-ray detector 37b and the γ-ray detector 31c as detection positions of two γ-rays that form a pair. Receive. The range calculation unit 61a, based on the received analysis information, tracks γ rays 9 defined by straight lines connecting the positions of the γ ray detector 37b and the γ ray detector 31c, and a straight line passing through the hole of the collimator 2. The annihilation position Xs (shown in FIG. 1), which is a crossing point, is calculated from the positron track 8 defined by

  Thus, the range calculation unit 61a calculates the distance from the position of the positron source 1 to the calculated pair annihilation position Xs as the range of positrons.

  Next, the moisture concentration calculation unit 62a receives the calculation result of the positron range from the range calculation unit 61a. The moisture concentration calculator 62a refers to the conversion table 63a and calculates the concentration of water molecules corresponding to the range of the positron. The moisture concentration calculator 62a sends the calculation result to the third signal processing unit 6c for the concentration of water molecules.

  On the other hand, in parallel with the processing of the water concentration measuring device 30, in the processing of the hydrogen atom concentration measuring device 50, fast neutrons emitted from the neutron source 10 repeatedly collide with the atoms contained in the gas and give kinetic energy. It gradually loses and becomes a thermal neutron through the neutron track 13 and is detected by the neutron detector 11.

  The neutron detector 11 transmits the detected thermal neutron detection intensity signal to the second signal processing unit 6b through the neutron detector cable 42.

  Next, the second signal processing unit 6b performs signal processing on the received thermal neutron detection intensity signal to calculate the thermal neutron detection intensity. The second signal processing unit 6b calculates the thermal neutron detection intensity from the calculated thermal neutron detection intensity based on the stored correlation between the concentration of hydrogen atoms contained in the gas and the thermal neutron detection intensity in advance. The concentration of hydrogen atoms contained in is calculated. The second signal processing unit 6b sends the calculation result of the hydrogen atom concentration to the third signal processing unit 6c.

The third signal processing unit 6c uses the concentration of water molecules calculated by the first signal processing unit 6a and the concentration of hydrogen atoms calculated by the second signal processing unit 6b to generate hydrogen in the gas. The concentration of gas (H ₂ ) is calculated.

That is, in the hydrogen gas concentration measurement system of the embodiment, the concentration of water molecules (H ₂ O) in the gas calculated by the moisture concentration measuring device 30 and the hydrogen atoms in the gas calculated by the hydrogen atom concentration measuring device 50 From the concentration of (H), the concentration of hydrogen gas (H ₂ ) in the gas in the reactor containment vessel 70 can be obtained.

  As described above, according to the moisture concentration measuring apparatus of the embodiment, since the gas detection unit is installed inside the reactor containment vessel, it is not necessary to draw the sampled gas to the outside of the reactor containment vessel. It becomes. Further, since the concentration of water molecules contained in the gas in the reactor containment vessel can be obtained, dehumidification of the gas is not required. Therefore, the concentration of water molecules can be measured without dehumidifying the gas and sampling outside the reactor containment vessel. Further, the concentration of water molecules can be measured even when the concentration of water molecules contained in the gas in the reactor containment vessel is high humidity in a high temperature environment.

  Moreover, according to the moisture concentration measuring method of the embodiment, since the gas detection unit is installed inside the reactor containment vessel, it is not necessary to draw the sampled gas outside the reactor containment vessel. Further, since the concentration of water molecules contained in the gas in the reactor containment vessel can be obtained, dehumidification of the gas is not required. Therefore, the concentration of water molecules can be measured without dehumidifying the gas and sampling outside the reactor containment vessel. Further, the concentration of water molecules can be measured even when the concentration of water molecules contained in the gas in the reactor containment vessel is high humidity in a high temperature environment.

  Further, according to the hydrogen gas concentration measurement system of the embodiment, since the gas detection unit is installed inside the reactor containment vessel, it is not necessary to draw the sampling gas outside the reactor containment vessel. . Further, since the concentration of hydrogen gas can be obtained by measuring the concentration of water molecules and hydrogen atoms contained in the gas in the reactor containment vessel, dehumidification of the gas is not required. Therefore, the concentration of hydrogen gas can be measured without dehumidifying the gas and sampling outside the reactor containment vessel. Further, the concentration of hydrogen gas can be measured even when the concentration of water molecules contained in the gas in the reactor containment vessel is high in a high temperature environment and high humidity.

  Further, according to the hydrogen gas concentration measuring method of the embodiment, since the gas detection unit is installed inside the reactor containment vessel, it is not necessary to draw the sampling gas outside the reactor containment vessel. . Further, since the concentration of hydrogen gas can be obtained by measuring the concentration of water molecules and hydrogen atoms contained in the gas in the reactor containment vessel, dehumidification of the gas is not required. Therefore, the concentration of hydrogen gas can be measured without dehumidifying the gas and sampling outside the reactor containment vessel. Further, the concentration of hydrogen gas can be measured even when the concentration of water molecules contained in the gas in the reactor containment vessel is high in a high temperature environment and high humidity.

[Other Embodiments]
As mentioned above, although embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof as well as included in the scope and gist of the invention.

  A hydrogen gas concentration measurement system may be configured by combining the moisture concentration measurement device and another conventional hydrogen atom concentration measurement device.

  DESCRIPTION OF SYMBOLS 1 ... Positron source, 2 ... Collimator, 3 ... Several gamma ray detectors, 3a, 3b, 3c, 3d ... Gamma ray detector group of a ring, 4a ... Cable between 1st units, 4b ... Between 2nd units Cable, 4c ... third unit cable, 5 ... simultaneous counting circuit, 6a ... first signal processing unit, 6b ... second signal processing unit, 6c ... third signal processing unit, 7a ... first shielding Body 7b second shield 8 positron track 9 gamma ray track 10 neutron source 11 neutron detector 13 neutron track 21 positron emission direction 30 moisture concentration Measuring device 31a, 32a, 33a, 34a, 35a, 36a, 37a, 38a, 39a, 310a, 311a, 312a, 31b, 37b, 31c, 37c, 31d, 37d ... γ-ray detector, 41a ... first γ Line detector case Group 41b ... second γ-ray detector cable group 41c ... third γ-ray detector cable group 41d ... fourth γ-ray detector cable group 42 ... neutron detector cable 50 ... hydrogen atom Concentration measuring device 61a ... range calculation unit 62a ... moisture concentration calculation unit 63a ... conversion table 70 ... reactor containment vessel 71 ... reactor

Claims (10)

A moisture concentration measuring device that measures the concentration of water molecules contained in the atmosphere inside the reactor containment vessel,
A positron source disposed in the reactor containment vessel for generating positrons;
Arranged in the positron emission direction to detect γ-rays generated by pair annihilation generated by collision of positrons emitted from the positron source with water molecules contained in the atmosphere. A plurality of gamma ray detectors arranged in
When two γ-ray detectors of the plurality of γ-ray detectors detect γ-rays at the same time, the positions of the two γ-ray detectors are analyzed and arranged outside the reactor containment vessel A coincidence counting circuit,
The position of the pair annihilation is determined as a position where a straight line connecting the positions of the two γ-ray detectors and a passage through which the positron passes, and thereby the distance from the positron source to the position of the pair annihilation is determined. A range calculation unit disposed outside the containment vessel for calculating a range;
The reactor containment vessel that calculates the concentration of the water molecule from the range of the positron calculated by the range calculation unit based on a correlation obtained in advance between the concentration of the water molecule and the range of the positron. A moisture concentration calculator disposed outside the
A moisture concentration measuring device comprising: The plurality of γ-ray detectors are arranged in a ring shape centered on an axis of the positron emission direction in a direction perpendicular to the positron emission direction, and a plurality of ring shapes are formed along the positron emission direction. It is arrange | positioned. The water concentration measuring apparatus of Claim 1 characterized by the above-mentioned. The range calculation unit projects the plurality of γ-ray detectors onto a plane in a direction perpendicular to the positron emission direction, and the positions of the two γ-ray detectors are diagonal directions on the projected plane. The water concentration measuring device according to claim 1, wherein the pair annihilation position is determined as a central position of the two γ-ray detectors. The water content according to any one of claims 1 to 3, further comprising a collimator arranged in the reactor containment vessel and emitting positrons generated from the positron source in the positron emission direction. Concentration measuring device. And a shielding body that is disposed in the reactor containment vessel with an opening, and that houses the positron source, the plurality of γ-ray detectors, and the collimator and shields radiation. The water concentration measuring device according to any one of claims 1 to 4. A moisture concentration measurement method for measuring the concentration of water molecules contained in the atmosphere in a reactor containment vessel,
Water containing positrons emitted from a positron source disposed in the reactor containment vessel from a plurality of γ-ray detectors arranged side by side in the reactor containment vessel along the positron emission direction. Γ-ray detection processing step for detecting γ-rays generated by pair annihilation caused by collision with molecules;
When two γ-ray detectors of the plurality of γ-ray detectors simultaneously detect γ-rays after the γ-ray detection processing step, simultaneously analyze the positions of the two γ-ray detectors. Counting step;
After the coincidence processing step, the position of the pair annihilation is determined as a position where a straight line connecting the analyzed positions of the two γ-ray detectors and a path through which the positron passes, and thereby the positron source A range calculation processing step for calculating a range of positrons as a distance from the position of the pair annihilation,
After the range calculation processing step, based on the correlation obtained in advance between the concentration of water molecules and the range of positrons, the concentration of water that calculates the concentration of water molecules from the calculated range of the positrons A calculation processing step;
A method for measuring moisture concentration, comprising: A hydrogen gas concentration measurement system that has a moisture concentration measurement device, a hydrogen atom concentration measurement device, and a hydrogen gas concentration calculation unit, and measures the concentration of hydrogen gas contained in the atmosphere in the reactor containment vessel,
The moisture concentration measuring device is
A positron source disposed in the reactor containment vessel for generating positrons;
Arranged in the positron emission direction to detect γ-rays generated by pair annihilation generated by collision of positrons emitted from the positron source with water molecules contained in the atmosphere. A plurality of gamma ray detectors arranged in
When two γ-ray detectors of the plurality of γ-ray detectors detect γ-rays at the same time, the positions of the two γ-ray detectors are analyzed and arranged outside the reactor containment vessel A coincidence counting circuit,
The position of the pair annihilation is determined as a position where a straight line connecting the positions of the two γ-ray detectors and a passage through which the positron passes, and thereby the distance from the positron source to the position of the pair annihilation is determined. A range calculation unit disposed outside the containment vessel for calculating a range;
The concentration of the water molecule is calculated from the range of the positrons calculated by the range calculation unit based on the correlation obtained in advance between the concentration of water molecules and the range of positrons. A moisture concentration calculator disposed on the outside,
The hydrogen atom concentration measuring device measures the concentration of hydrogen atoms contained in the atmosphere in the reactor containment vessel,
The hydrogen gas concentration calculation unit is configured to generate hydrogen in the reactor containment vessel based on the water molecule concentration calculated from the water concentration measurement device and the hydrogen atom concentration measured from the hydrogen atom concentration measurement device. A hydrogen gas concentration measurement system characterized in that a gas concentration is calculated and disposed outside the reactor containment vessel. The hydrogen atom concentration measuring device is:
A neutron source disposed in the reactor containment vessel for generating fast neutrons;
A neutron detector that is arranged in the reactor containment vessel and detects thermal neutrons generated by collision of fast neutrons emitted from the neutron source with a gas contained in the atmosphere in the reactor containment vessel;
A hydrogen atom concentration calculation unit disposed outside the reactor containment vessel, which calculates the concentration of the hydrogen atoms based on the detected thermal neutrons;
The hydrogen gas concentration measurement system according to claim 7, comprising: A first shielding body disposed in the reactor containment vessel having an opening, containing the positron source, the plurality of γ-ray detectors, and the collimator, and shielding radiation;
A second shielding body disposed in the reactor containment vessel having an opening, containing the neutron source and the neutron detector, and shielding radiation;
The hydrogen gas concentration measurement system according to claim 8, further comprising: A hydrogen gas concentration measurement method for measuring the concentration of hydrogen gas contained in the atmosphere in a reactor containment vessel,
Water containing positrons emitted from a positron source disposed in the reactor containment vessel from a plurality of γ-ray detectors arranged side by side in the reactor containment vessel along the positron emission direction. Γ-ray detection processing step for detecting γ-rays generated by pair annihilation caused by collision with molecules;
When two γ-ray detectors of the plurality of γ-ray detectors simultaneously detect γ-rays after the γ-ray detection processing step, simultaneously analyze the positions of the two γ-ray detectors. Counting step;
After the coincidence processing step, the position of the pair annihilation is determined as a position where a straight line connecting the analyzed positions of the two γ-ray detectors and a path through which the positron passes, and thereby the positron source A range calculation processing step for calculating a range of positrons as a distance from the position of the pair annihilation,
After the range calculation processing step, based on the correlation obtained in advance between the concentration of water molecules and the range of positrons, the concentration of water that calculates the concentration of water molecules from the calculated range of the positrons A calculation processing step;
Thermal neutron detection processing step for detecting thermal neutrons generated by collision of fast neutrons emitted from a neutron source disposed in the reactor containment vessel with a gas contained in the atmosphere in the reactor containment vessel;
After the thermal neutron treatment step, based on the detected thermal neutrons, a hydrogen atom concentration calculation processing step for calculating the concentration of the hydrogen atoms,
After the moisture concentration calculation processing step and the hydrogen atom concentration calculation processing step, based on the calculated concentration of the water molecule and the calculated concentration of the hydrogen atom, hydrogen gas in the reactor containment vessel Hydrogen gas concentration calculation processing step for calculating the concentration of
A hydrogen gas concentration measurement method comprising:

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