JP5075748B2 - Radiation monitoring device - Google Patents

Description

  The present invention relates to a radiation monitoring apparatus for measuring a radioactivity concentration in exhaust gas at a nuclear power plant.

Conventionally, in nuclear power plants, for example, for the purpose of monitoring fuel damage, measurement of radioactivity concentration in exhaust gas, for example, radioactivity analysis of rare gas nuclides has been performed (see Patent Documents 1 and 2).
By the way, this exhaust gas is obtained by recombining hydrogen and oxygen generated by radiolysis contained in a non-condensable gas extracted from a condenser using an air extractor into water with an exhaust gas recombiner, The water generated by the recombination is removed by a dehumidifying cooler and returned to the condenser, and the remaining non-condensable gas is guided to the activated carbon rare gas hold-up device to attenuate the radioactivity of the short-lived radioactive rare gas. After that, it is diffused and released from the main exhaust tower into the atmosphere.

Confirmation that the recombination of hydrogen and oxygen in the exhaust gas recombiner is normal is performed by measuring the hydrogen concentration with a hydrogen sensor arranged on the downstream side of the exhaust gas recombiner. The health of the vessel is checked online.
Japanese Patent Laid-Open No. 10-222143 JP 2001-141871 A

However, the measurement of the hydrogen concentration by the hydrogen sensor has low sensitivity, and its detection sensitivity is in the order of ppm. From the viewpoint of early detection of performance deterioration of the exhaust gas recombiner, detection sensitivity is low, and a higher sensitivity is desired. Yes.
By the way, the inventors analyzed the radionuclide contained in the non-condensable gas extracted by the air extractor and the non-condensable gas after passing through the dehumidifying cooler. We found the fact that N-13) and fluorine-18 (F-18) are included, whereas the latter contains almost no F-18. This is because F-18 easily binds to hydrogen and exists in the form of hydrogen fluoride, and hydrogen fluoride is extremely soluble in water. Therefore, the exhaust gas recombiner operates normally and efficiently combines hydrogen and oxygen. This is probably because hydrogen fluoride is absorbed in the produced water and F-18 hardly remains in the non-condensable gas.
Therefore, it was found that the performance deterioration of the exhaust gas recombiner can be monitored by measuring the concentration of F-18 without directly measuring the concentration of hydrogen.

N-13 and F-18 are both positron emitting nuclides. (1) When the emitted positron annihilates an electron pair, it emits a gamma ray pair with energy of 511 keV, so it was detected by a radiation detector. N-13 and F-18 cannot be distinguished from the energy of γ rays. (2) The half-life of N-13 is as short as about 10 minutes, whereas the half-life of F-18 is about 110 minutes. Because of the relatively long time, the inventors considered using a method for calculating the concentration of radionuclide using the difference in half-life (decay constant) in measuring the radioactivity in exhaust gas. None of the radiation monitoring devices that monitor radiation by continuously flowing a sample use the half-life difference online.
In addition, even in the case of measuring radioactivity by confining a sample in a sample container or the like for a certain period of time as described in paragraph [0039] of Patent Document 2, the purpose is to emit radionuclides having a short half-life contained in the sample. It was to reduce the background when the gamma ray energy was measured by attenuating the performance.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a radiation monitoring apparatus having a simple configuration that can detect performance deterioration of an exhaust gas recombiner or the like with high sensitivity.

The invention according to claim 1 is a γ-ray detector, a pulse height analyzing means for analyzing a pulse height based on a peak value of a γ-ray detection signal from the γ-ray detector, and a signal processing means for processing the counting result subjected to the pulse height analysis. And a radiation monitoring apparatus that monitors the leakage of radioactivity by measuring the concentration of nuclides that emit γ-rays contained in a continuously flowing sample, and is arranged to face the γ-ray detector. And a first measurement pipe connected to the front and back of the first flow cell to flow the sample at a predetermined flow rate, connected to the front and back of the second flow cell, and the first flow cell. A second measuring pipe arranged in parallel with the measuring pipe; a confinement means for introducing and confining the sample into the second flow cell; and a shield having a movable opening disposed around the γ-ray detector. And the opening of the shield is the first An actuator that can be switched to the flow cell side or the second flow cell side, and a control unit that controls the operations of the confinement unit, the actuator, and the signal processing unit, and the signal processing unit Comprises storage means for storing the counting results in time series,
In the normal measurement state, the control unit causes the actuator to set the opening of the shield on the first flow cell side, and causes the signal processing unit to apply γ rays from the sample flowing through the first flow cell. In addition to processing the counting results based thereon, in the confinement measurement state, the confinement means is controlled to confine after introducing the sample into the second flow cell, and the actuator is controlled to control the opening of the shield. And counting the specific peak value in the γ-ray detection signal obtained for the sample confined in the second flow cell by the signal processing means. The result is stored in the storage means in time series, and the signal processing means is controlled by the control means and is based on the count results stored in the time series. Then, the concentration of a plurality of radionuclides having different decay constants that emit γ-rays of energy corresponding to the specific peak value is quantitatively analyzed.

According to a second aspect of the present invention, there is provided a γ-ray detector, a pulse height analyzing means for analyzing a pulse height based on a peak value of a γ-ray detection signal from the γ-ray detector, and a signal processing means for processing the counting result subjected to the pulse height analysis. A radiation monitoring apparatus that monitors the leakage of radioactivity by measuring the concentration of nuclides that emit γ-rays contained in a continuously flowing sample, and the first γ-ray detector as the γ-ray detector And a second γ-ray detector, and further, a first flow cell disposed facing the first γ-ray detector and a second flow cell disposed facing the second γ-ray detector. Two flow cells, a first measurement pipe connected before and after the first flow cell to flow the sample at a predetermined flow rate, and connected before and after the second flow cell and parallel to the first measurement pipe The sample is introduced into the second measurement pipe and the second flow cell closed. Means confinement put, and a control means for controlling said containment means and said signal processing means, said signal processing means includes a storage means for time-sequentially storing the count result,
The control means causes the signal processing means to process the counting result based on the γ rays from the sample flowing through the first flow cell in the normal measurement state, and controls the confinement means in the confinement measurement state. Then, the sample is introduced into the second flow cell and confined, and at least the γ-ray detection signal obtained for the sample confined in the second flow cell is specified in the signal processing means. Storing the counting result of the crest value of the time series in the storage means,
The signal processing means includes a plurality of positron emitting nuclides having different decay constants that emit γ-rays having energy corresponding to 511 keV as the specific peak value based on the stored count result controlled by the control means. It is characterized by quantitative analysis of the concentration of a certain radionuclide.

According to a third aspect of the present invention, there is provided a γ-ray detector, a pulse height analyzing means for analyzing a pulse height based on a peak value of a γ-ray detection signal from the γ-ray detector, and a signal processing means for processing the counting result subjected to the pulse height analysis. And a radiation monitoring apparatus that monitors the leakage of radioactivity by measuring the concentration of nuclides that emit γ-rays contained in a continuously flowing sample, and is arranged to face the γ-ray detector. And a first measurement pipe connected to the front and back of the first flow cell to flow the sample at a predetermined flow rate, connected to the front and back of the second flow cell, and the first flow cell. A second measurement pipe arranged in parallel with the measurement pipe, a confinement means for introducing and confining the sample into the second flow cell, an opening and closing of the confinement means, and a control means for controlling the operation of the signal processing means, The signal processing The means has storage means for storing the counting results in time series,
In the normal measurement state, the control means opens the confinement means, causes the signal processing means to process the counting result based on the γ-rays from the sample flowing through the first flow cell, and the confinement measurement state. Then, the confining means is closed for a predetermined time, and the signal processing means counts the specific peak value in the γ-ray detection signal obtained for the sample confined in the second flow cell. Results are stored in the storage means in time series, and the signal processing means is controlled by the control means, and based on the stored count results, energy γ rays corresponding to 511 keV as the specific peak value It is characterized by quantitatively analyzing the concentration of radionuclides that are a plurality of positron emitting nuclides with different decay constants.

According to a fourth aspect of the present invention, there is provided a γ-ray detector, a pulse height analyzing means for analyzing a pulse height based on a peak value of a γ-ray detection signal from the γ-ray detector, and a signal processing means for processing the counting result subjected to the pulse height analysis. And a radiation monitoring device that monitors the leakage of radioactivity by measuring the concentration of nuclides that emit γ-rays contained in a continuously flowing sample, and a flow cell disposed facing the γ-ray detector; A measurement pipe connected to the front and rear of the flow cell and flowing the sample at a predetermined flow rate; provided in the measurement pipe; provided on the upstream side and the downstream side of the flow cell, respectively, for introducing the sample into the flow cell; A confinement means for confinement, a control means for controlling the operation of the signal processing means, and a control means for controlling the operation of the signal processing means, the signal processing means having storage means for storing the counting results in time series,
The control means opens the confinement means in a normal measurement state, causes the signal processing means to process the counting result based on γ rays from the sample flowing through the flow cell, and in the confinement measurement state, the control means The confinement means is closed for a predetermined time, and the counting result of a specific peak value of the γ-ray detection signal obtained for the sample confined in the flow cell by the signal processing means is stored in the storage means. Memorize in time series,
The signal processing means includes a plurality of positron emitting nuclides having different decay constants that emit γ-rays having energy corresponding to 511 keV as the specific peak value based on the stored count result controlled by the control means. It is characterized by quantitative analysis of the concentration of a certain radionuclide.

  According to the inventions according to claims 1 to 4, the concentrations of radionuclides having the same γ-ray energy and different half-lives can be easily calculated. For example, N− When F-18 is included in addition to 13, the concentration of F-18 can be easily calculated, and the performance deterioration of the exhaust gas recombiner can be detected at an early stage.

According to a fifth aspect of the present invention, there is provided a γ-ray detector, a pulse height analyzing means for analyzing a pulse height based on a peak value of a γ-ray detection signal from the γ-ray detector, and a signal processing means for processing the counting result subjected to the pulse height analysis. And a radiation monitoring apparatus that monitors the leakage of radioactivity by measuring the concentration of nuclides that emit γ-rays contained in a continuously flowing sample, and is arranged to face the γ-ray detector. And a first measurement pipe connected to the front and back of the first flow cell to flow the sample at a predetermined flow rate, and a predetermined connection connected downstream of the first measurement pipe. A delay opening having a length, a second measurement pipe connected before and after the second flow cell and connected to the downstream side of the delay pipe, and a gamma ray detector. A shield having a portion and the opening of the shield is the first An actuator that can be set by switching to the flow cell side or the second flow cell side, and a control unit that controls the operation of the actuator and the operation of the signal processing unit, wherein the signal processing unit Storing means for storing;
In the normal measurement state, the control unit causes the actuator to set the opening of the shield on the first flow cell side, and causes the signal processing unit to apply γ rays from the sample flowing through the first flow cell. The counting result based on is stored in the storage means as a first counting result in time series, and the actuator is controlled at a predetermined frequency so that the opening of the shield is set to the second flow cell side. In this state, in the signal processing means, the counting result based on the γ rays from the sample flowing through the second flow cell is stored in the storage means as a second counting result, and the signal processing means includes the control means To emit γ-rays of energy corresponding to a specific peak value based on the stored second count result and the first count result a predetermined time ago. Wherein the quantitative analysis of the concentration of different radionuclides 壊定 number.

According to a sixth aspect of the present invention, there is provided a γ-ray detector, a pulse height analyzing means for analyzing a pulse height based on a peak value of a γ-ray detection signal from the γ-ray detector, and a signal processing means for processing the counting result subjected to the pulse height analysis. A radiation monitoring apparatus that monitors the leakage of radioactivity by measuring the concentration of nuclides that emit γ-rays contained in a continuously flowing sample, and the first γ-ray detector as the γ-ray detector And a second γ-ray detector, and further, a first flow cell disposed facing the first γ-ray detector and a first flow cell disposed facing the first γ-ray detector. Two flow cells, a first measurement pipe connected before and after the first flow cell to flow the sample at a predetermined flow rate, and a delay of a predetermined length connected to the downstream side of the first measurement pipe Connected to the pipe, before and after the second flow cell, and connected downstream of the delay pipe. A second measurement pipe has, and a control means for controlling the operation of said signal processing means, said signal processing means includes a storage means for storing the count result,
In the normal measurement state, the control means causes the signal processing means to store the count result based on the first γ-ray detector in the storage means in time series as a first count result, and at a predetermined frequency. In the signal processing means, the counting result based on the second γ-ray detector is stored in the storage means as a second counting result, and the signal processing means is controlled by the control means and stored. Based on the second count result and the first count result a predetermined time before, quantitatively analyzing the concentrations of a plurality of radionuclides having different decay constants that emit gamma rays of energy corresponding to a specific peak value. Features.

According to a seventh aspect of the present invention, there is provided a γ-ray detector, a pulse height analyzing means for analyzing a pulse height based on a peak value of a γ-ray detection signal from the γ-ray detector, and a signal processing means for processing the counting result subjected to the pulse height analysis. And a radiation monitoring apparatus that monitors the leakage of radioactivity by measuring the concentration of nuclides that emit γ-rays contained in a continuously flowing sample, and is disposed in front of the γ-ray detector. A first flow cell and a second flow cell; a first measurement pipe connected before and after the first flow cell to flow the sample at a predetermined flow rate; and a predetermined connection connected downstream of the first measurement pipe. A delay pipe having a length of, a bypass pipe connected in parallel with the delay pipe downstream of the first measurement pipe, a second measurement pipe connected before and after the second flow cell, and Dividing the sample through the delay pipe and the bypass pipe A flow switching unit that switches the sample flow path to be supplied to the second measurement pipe, and a control unit that controls operations of the signal processing unit and the flow switching unit, the signal processing unit comprising: And storing means for storing the counting result,
In the normal measurement state, the control means causes the flow switching means to be in a state in which the sample flows through the delay pipe in the second measurement pipe. In the signal processing means, the first and second The counting result based on the sample flowing in the flow cell is stored in the storage means in time series as a first counting result, and the flow switching means is connected to the second measurement pipe at a predetermined frequency via the bypass pipe. The signal is made to flow, and the signal processing means stores the counting result based on the sample flowing through the first and second flow cells in the storage means as a second counting result, and the signal processing means Is controlled by the control means, and based on the stored second count result and the first count result a predetermined time ago, γ-rays of energy corresponding to a specific peak value The concentration of the different radionuclides decay constant of releasing characterized by quantitative analysis.

According to the inventions according to claims 5 to 7, it is possible to easily calculate the concentration of radionuclides having the same γ-ray energy and different half-life lengths, that is, different decay constants. When F-18 is contained in addition to N-13, the concentration of F-18 can be easily calculated, and the performance deterioration of the exhaust gas recombiner can be detected at an early stage.
Furthermore, since the concentration reduction of the radionuclide having a short half-life due to the time while passing through the delay pipe is used without confining the sample, it is convenient to perform radiation monitoring while continuously flowing the sample.

  ADVANTAGE OF THE INVENTION According to this invention, the radiation monitoring apparatus of the simple structure which can detect the performance degradation of an exhaust gas recombiner with high sensitivity can be provided.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings as appropriate.
《Gas waste treatment system》
FIG. 1 is a schematic diagram of a primary plant in a boiling water nuclear power plant to which a radiation monitoring apparatus according to an embodiment of the present invention is applied, a device layout diagram of a gas waste treatment system, and a gas waste treatment system. It is a block diagram of a radiation monitoring apparatus.

  In FIG. 1, the nuclear fuel in the core 2 loaded in the nuclear reactor 1 generates heat by the fission reaction, and the reactor water is boiled. Steam generated in the nuclear reactor 1 flows into the turbine 4 through the main steam pipe 3, rotates the turbine 4, and drives a generator (not shown) to generate power. The steam that has rotated the turbine 4 is dumped and condensed in the condenser 5 to return to water, and is sent to the feed water heater (not shown) by the condensate pump 21 through the condensate pipe 27 and further to the feed water pump (not shown). Then, water is supplied to the reactor 1 through the water supply pipe 26.

  Most of the gas flowing in the main steam pipe 3 is water vapor generated by boiling the reactor water, and in this, the reactor water is generated by radiolysis due to the radiation energy generated by nuclear fuel fission. Radioactive gas generated slightly from hydrogen gas, oxygen gas, and nuclear fuel, and non-condensable gas such as air (in-leak air) entering from pipes and equipment connected to the condenser 5 are also included.

  After these non-condensable gases flow into the condenser 5, they are extracted to the gaseous waste treatment system side by the air extractor 7 using a part of the reactor steam through the main steam extraction pipe 6 branched from the main steam pipe 3. Is done. From the air extractor 7, the driving steam and non-condensable gas used for extraction flow out together and flow into the exhaust gas preheater 9. In the exhaust gas preheater 9, the inflowing steam and the non-condensable gas are heated and sent to the exhaust gas recombiner 10.

In the exhaust gas recombiner 10, hydrogen (oxygen) gas generated by radiolysis of the reactor water becomes water (steam) by the action of the catalyst filled in the exhaust gas recombiner 10. Next, the driving steam, recombined water, in-leak air, and the like are introduced into the exhaust gas condenser 11 and cooled therein, so that the driving steam and the recombined water are condensed through the exhaust gas condenser drain pipe 19. It is collected in the vessel 5. The non-condensable gas that has passed through the exhaust gas condenser 11 has moisture, and the moisture is removed by the dehumidifying cooler 12. The moisture removed here is also collected in the condenser 5 through the exhaust gas condenser drain pipe 19.
On the other hand, non-condensable gas mainly composed of radioactive rare gas generated from inleak air and nuclear fuel passes through the exhaust gas system pipe 25 and passes through individual holdup tanks 13a to 13c constituting the activated carbon type rare gas holdup device 13, Further, after passing through the exhaust gas filter 14, it is guided to the main exhaust cylinder 16 by the exhaust gas extractor 15 and released into the atmosphere.

The activated carbon rare gas hold-up device 13 is designed so that the radioactive rare gas is attenuated while adsorbing and desorbing, and when released from the main exhaust cylinder 16, the radioactive concentration level of the radioactive rare gas becomes a certain value or less. ing.
In FIG. 1, in the exhaust gas system pipe 25 on the downstream side of the dehumidifying cooler 12, the radiation monitor device 30 is branched from the exhaust gas system pipe 25 and will be described later (in FIG. 1, the radiation monitor device 30A of the first embodiment described later). The sampling pipe (collecting) 22 for supplying the sample gas to the configuration (specifically shown) and the sampling pipe (return) 23 for returning the sample returned from the radiation monitoring device 30 to the exhaust gas system pipe 25 are connected. .

  The nuclear fuel assembly loaded in the core 2 of the nuclear reactor 1 generates a slight amount of radioactive noble gas even during normal operation due to contaminated uranium adhering to the fuel surface. When the cladding tube of the filled fuel rod is damaged, the amount of generated radioactive noble gas increases.

  In order to monitor the damage of the nuclear fuel assembly in the nuclear reactor 1, the outlet gas of the dehumidifying cooler 12 is changed by the sampling pipe (collecting) 22 provided at the inlet of the activated carbon type rare gas holdup device 13 of the exhaust gas system pipe 25. (Sample) Collected and introduced into the on-site placement device portion of the radiation monitoring device 30 including a germanium radiation detector 32 (hereinafter referred to as Ge detector) which is a γ-ray detector, and γ-ray detection from the Ge detector 32 The signal height is analyzed, and the change in the counting result, that is, the change in the radioactivity concentration is displayed on the operation display unit 38 of the radiation monitoring device 30 arranged in the central operation room (not shown) of the nuclear power plant. It is monitored by recording it in a built-in storage device.

  In the sampling pipe (return) 23, for example, a pump 59 is used so that the exhaust gas return gas from the radiation monitoring device 30 flows into the exhaust gas system pipe 25, and the exhaust gas flow rate is controlled to the sampling pipe (collection) 22 side. Therefore, a flow rate adjusting valve 57 and a flow meter 58 are provided. Then, a flow rate signal of the flow meter 58 is input to the control unit 37 which will be described later, and the opening degree of the flow rate adjusting valve 57 is controlled by the control unit 37 according to the flow rate signal, and the exhaust gas flow rate in the sampling pipe (collecting) 22 Is preferably maintained in order to detect a change in radioactivity concentration in the exhaust gas due to fuel damage.

  Although the operation display unit 38 is displayed as a personal computer in FIG. 1, it is not limited thereto. The counting result may be recorded on a recording sheet using a recorder.

  In the present embodiment, the exhaust gas radioactivity concentration is continuously measured by performing gamma ray nuclide analysis by the radiation monitoring device 30, but the radioactivity concentration of the nuclide type in the exhaust gas is illustrated periodically or irregularly. An exhaust gas sample may be sampled using a non-vial vial sample bottle, the vial sample bottle may be removed, and γ-ray nuclide analysis may be performed.

<< First Embodiment >>
Next, a radiation monitoring apparatus 30A that is a first embodiment of the radiation monitoring apparatus according to the present invention will be described.
The radiation monitoring apparatus 30A includes a measurement line (for normal use) 51, a measurement line (for confinement) 52, a Ge detector 32, a movable shield 33, a wave height analysis apparatus (wave height analysis) installed in a place with a low background level. Means) 35, a signal processing device (signal processing means) 36, a control unit (control means) 37, and the like, and an operation display unit 38 installed in the central operation room.
The sampling pipe (collection) 22 guides the exhaust gas to a place with a low background level, branches to a measurement line (for normal use) 51 and a measurement line (for confinement) installed there by a three-way valve 53A, and then branches to three-way. The valve 53B joins and is connected to the sampling pipe (return) 23.
The measurement line (for normal use) 51 includes a flow cell 31A, and the flow cell 31A is configured as a passage having a volume capable of storing a certain amount of exhaust gas as a sample.
Similarly, the measurement line (for confinement) 52 includes a flow cell 31B, and the flow cell 31B is also configured as a passage having a volume capable of accommodating a certain amount of exhaust gas as a sample.
Here, the measurement line (for normal use) 51 is in the “first measurement piping” described in the claims, the measurement line (for confinement) 52 is in the “second measurement piping” in the claims, and the flow cell 31A is The flow cell 31B corresponds to the “second flow cell” described in the claims, and the three-way valves 53A and 53B correspond to the “containment means” described in the claims.

  The three-way valves 53 </ b> A and 53 </ b> B are solenoid valve switching valves that are energized and controlled by the control unit 37. When the three-way valve 53A is not energized, the exhaust gas from the sampling pipe (collecting) 22 flows into the measurement line (for normal use) 51, and when energized, the exhaust gas from the sampling pipe (collecting) 22 is shown as indicated by the arrow in the measurement line (confinement). ). When the three-way valve 53B is not energized, the exhaust gas from the measurement line (for normal use) 51 flows into the sampling pipe (return) 23, and when energized, the exhaust gas is sampled from the measurement line (confinement) 52 as indicated by the arrow (return). 23.

A Ge detector 32 is disposed between the flow cells 31A and 31B so as to be surrounded by a movable shield (shield) 33 having an opening 33a. The Ge detector 32 detects radiation (γ rays) from the flow cell 31A or the flow cell 31B through the opening 33a.
The movable shield 33 can be rotated by an actuator 34 whose operation is controlled by the control unit 37, and the opening 33a can be directed to the flow cell 31A side or the flow cell 31B side.
Here, the entire movable shield 33 is configured to be rotatable. However, the present invention is not limited thereto, and the openings provided on the respective sides of the flow cell 31A and the flow cell 31B of the movable shield 33 are provided. The structure 33a may be openable and closable by the actuator 34.

  Incidentally, the Ge detector 32 is cooled by, for example, an electronic cooling device (not shown) arranged in the movable shield 33, or one of the field arrangement devices of the radiation monitoring device 30A outside the movable shield 33. It is cooled by a circulating refrigerant cooled by an electronic cooling device (not shown) provided as a part.

In order to suppress absorption of low energy gamma rays, the peripheral walls of the flow cells 31A and 31B are preferably made of a material having a low mass number such as aluminum (Al), and the window thickness on the Ge detector 32 side is extremely thin. It is said that. Thereby, the radiation from the exhaust gas guided to the flow cells 31A and 31B is converted into an electric signal having a magnitude proportional to the energy by the Ge detector 32.
A pulse height analyzer 35 and a signal processor 36 are sequentially connected to the Ge detector 32, and an operation display unit 38 is further connected. The signal processing device 36 is also connected to the control unit 37 and operates under the control of the control unit 37. Incidentally, the signal processing device 36 has a storage device (storage means) 36a. Further, the control unit 37 is connected to the operation display unit 38 and can receive a command input from the input device of the operation display unit 38 as necessary.

  Note that the background level is further reduced by covering the flow cells 31A and 31B together with the Ge detector 32 with a shield (not shown).

In such a configuration, in the normal measurement state, the control unit 37 sets the opening 33a of the movable shield 33 to face the flow cell 31A side, the three-way valves 53A and 53B are not energized, and the sampling pipe ( Exhaust gas is guided to the flow cell 31A via the sampling 22 and radiation measurement is performed by the Ge detector 32. The gamma ray detection signal from the Ge detector 32 is energy discriminated by the wave height analyzer 35, and the energy window As the count value, the timing is controlled by the signal processing device 36 and integrated for a predetermined time interval (predetermined time window). The signal processing device 36 reads the count value for each energy window from the wave height analyzer 35 every predetermined time, and calculates the count rate for the predetermined time window for each target radionuclide corresponding to the preset energy window. The count rate for each target radionuclide remains as the count rate or is converted into the radioactivity concentration by the detection efficiency and stored in the storage device 36a, and the time series information is displayed on the display device of the operation display unit 38. .
Incidentally, the energy window corresponding to 511 keV γ-ray energy by N-13 and F-18 is also included in this preset energy window.
Here, the count rate or the one converted from the count rate into the radioactivity concentration corresponds to the “count result” described in the claims.

  Therefore, by monitoring the trend of the time series information in the operation display unit 38, it is possible to monitor the fuel damage.

(Calculation of N-13 and F-18 concentrations)
Next, a method for measuring N-13 and F-18 concentrations in the exhaust gas will be described with reference to FIGS. 1 and 3 as appropriate with reference to FIG.
FIG. 2 is a flowchart of a control flow for calculating the concentrations of radionuclides, for example, N-13 and F-18, which confine a sample and emit γ-rays of the same energy corresponding to a predetermined energy window.
FIG. 3 is a diagram showing decay curves of both radioactivity in the presence of two radionuclides with different half-life lengths.
The control unit 37 confines the exhaust gas in the measurement line (for confinement) 52 and the flow cell 31B at a preset frequency of a predetermined time, for example, once an hour, and measures γ rays from the flow cell 31B. The program is controlled so as to perform “confinement measurement”, and it is checked whether or not it is the timing to start confinement measurement (step S11). If it is the timing of confinement measurement start (Yes), the process proceeds to step S12, and if not (No), step S11 is repeated.

  In step S12, the control unit 37 outputs an instruction for confinement measurement to the actuator 34, the signal processing device 36, and the three-way valves 53A and 53B. Specifically, the actuator 34 has a control signal for rotating the movable shield 33 so that the opening 33a is set to the flow cell 31A until the opening 33a is set to the flow cell 31B. The signal processing device 36 is instructed to switch from the normal measurement state until then to the confinement measurement state, and the three-way valves 53A and 53B are energized. Then, the three-way valves 53A and 53B are temporarily energized, and the exhaust gas is guided to the flow cell 31B through the sampling pipe (collecting) 22, and the exhaust gas that has remained in the measurement line (for confinement) 52 and the flow cell 31B from before is Scavenged.

In step S13, the control unit 37 waits for a time when the exhaust gas in the measurement line (for confinement) 52 and the flow cell 31B is completely replaced with the current flowing through the sampling pipe (collecting) 22 after a predetermined time has elapsed. Then, the three-way valves 53A and 53B are turned off again, and the exhaust gas is confined in the measurement line (for confinement) 52 and the flow cell 31B (“closed by introducing exhaust gas into the measurement line (for confinement)”).
At this time, the exhaust gas begins to flow again at a predetermined flow rate in the measurement line (for normal use) 51.
In step S14, the actuator 34 receives a control signal from the control unit 37, and the movable part 33 is movable so that the opening 33a of the movable shield 33 that has been set so far faces the flow cell 31A. The shield 33 is rotated (“the opening of the movable shield is set in the flow cell on the measurement line (for confinement) side”).

  In step S15, the control unit 37 starts a timer t and causes the signal processing device 36 to measure radiation at predetermined time intervals. Specifically, during steps S11 to S15, the Ge detector 32 continuously outputs the γ-ray detection signal to the wave height analyzer 35, and the wave height analyzer 35 discriminates the energy of the γ-ray detection signal by energy discrimination. The count value for each window is integrated for a predetermined time interval. The signal processing device 36 receives the output of the confinement measurement in step S12, and at the same time, from the wave height analyzer 35 in steps S11 to S15. Reading of the count value for each energy window is stopped, and reading of the count value for each energy window is started again from the wave height analyzer 35 at the time of step S16, and the positron emission decay of preset N-13 and F-18 is started. The count rate corresponding to the energy window of 511 keV gamma rays at the time is calculated. The count rate of 511 keV γ rays remains as the count rate or is converted into the radioactivity concentration by the detection efficiency and stored in the storage device 36a.

As a result, the storage device 36a, the time _t 1 in the containment measurement _{state, t 2, ···, t i} , ···, count rate _C m for _{t n (t 1), C} m (t 2) ,..., C _m (t _i ),..., C _m (t _n ) are stored in such a manner that the count rate decreases over time as plotted points indicated by crosses as shown in FIG. The
In FIG. 3, the horizontal axis shows the time after the start t _{0 of the} confinement measurement, and the vertical axis shows the logarithm of the counting rate C _m (corresponding to the radioactivity) for each elapsed time. Short radionuclide Curve C _A half-life, that is, show the contribution of N-13, the curve C _B Long radionuclide half-life, that is, indicating the contribution of the F-18.
T _A and T _B in FIG. 3 indicate half-lives.

In step S17, the control unit 37 checks whether the timer t has reached the end time T ₁ of the measurement confinement. When it reaches the end time _{T 1} (Yes), the process proceeds to step S18, if it has not reached (No), continue to step S16. In step S18, the control unit 37 resets the timer t, proceeds to step S19, and outputs a normal measurement instruction to the actuator 34.

  In step S20, the actuator 34 receives a control signal from the control unit 37, and the movable shield 33 is set so that the opening 33a of the movable shield 33 is directed toward the flow cell 31B so that the movable shield is directed toward the flow cell 31A. The body 33 is rotated (“the opening of the movable shield is set in the flow cell on the measurement line (normal) side”).

  In step S21, the signal processing device 36 reads out the count rates stored in the time series in the storage device 36a in step S16, so that two radionuclides having different half-lives as shown in FIG. As the radioactive decay curve, constants A and B indicating the respective concentrations are calculated by the method of least squares (“Analyze N-13 and F-18 concentrations”).

式（２）で示した差分の二乗の総和が最小となる定数Ａ，Ｂを求めるものである。
そして、得られた定数Ａ，ＢがＮ−１３，Ｆ−１８それぞれの濃度に対応する。 Here, the method for calculating the constants A and B by the least square method is a well-known method, and the evaluation function C (t _i ) of the decay curve of the count rate is assumed as the following equation (1):

Constants A and B that minimize the sum of the squares of the differences shown in Expression (2) are obtained.
The obtained constants A and B correspond to the respective densities of N-13 and F-18.

In step S22, the signal processor 36, whether the F-18 concentration is equal to or larger than the threshold, that is, the constant B of the curve C _B in FIG. 3, it is checked whether the threshold or more. If it is equal to or greater than the threshold (Yes), the process proceeds to step S23, and an alarm is output to the operation display unit 38. For example, the operation display unit 38 is caused to display “Exhaust gas recombiner, exhaust gas condenser, dehumidifying cooler abnormal!”. Here, as the F-18 concentration, it is more appropriate to use the relative ratio (B / A) based on the constants A and B than to use the constant B itself calculated in step S21.
If it is less than the threshold value in step S22 (No), the signal processing device 36 ends the series of confinement measurement processes and starts the normal measurement process.
Upon completion of the confinement measurement processing, the signal processing device 36 transmits the calculated F-18 concentration to the operation display unit 38, and the operation display unit 38 monitors the trend of time series information of the F-18 concentration. By performing, you may make it monitor continuously whether the waste gas recombiner 10, the waste gas condenser 11, and the dehumidification cooler 12 are in a normal state.

  When the series of confinement measurement processes is completed, the signal processing device 36 outputs a signal for each energy window output from the wave height analyzer 35 with respect to the γ-ray detection signal based on the γ-ray from the flow cell 31A of the measurement line (for normal use) 51. The count value is read, and the count rate for each target radionuclide corresponding to the preset energy window is calculated. The target count rate for each radionuclide is converted to the radioactivity concentration as it is or based on the detection efficiency, stored in the storage device 36a, and the time series information is sent to the operation display unit 38.

According to the radiation monitoring apparatus 30A of the present embodiment, the concentration of F-18 can be calculated at predetermined time intervals, and if the exhaust gas recombiner 10, the exhaust gas condenser 11, and the dehumidifying cooler 12 are healthy, F- 18 is returned to the exhaust gas condenser drain pipe 19 in the chemical form of hydrogen fluoride, and the alarm output in step S23 is not made. When performance deterioration or abnormality occurs in the exhaust gas recombiner 10, the exhaust gas condenser 11, or the dehumidifying cooler 12, the collected non-condensable gas is mixed with hydrogen fluoride or included in the moisture that has not been removed. Thus, it can be determined that the performance deterioration or abnormality of the exhaust gas recombiner 10, the exhaust gas condenser 11, and the dehumidifying cooler 12 has occurred.
In particular, since the concentration of F-18 can be detected from the count rate with respect to the peak value corresponding to 511 keV γ-rays rather than detecting with the hydrogen concentration, it is possible to detect performance deterioration or abnormality with high sensitivity.

  Further, in the present embodiment, when the confinement measurement is performed in the measurement line (for confinement) 52, since a predetermined amount of exhaust gas flows through the measurement line (for normal use) 51, the sampling pipe ( Even if the sampling) 22 and the sampling pipe (return) 23 are long, the exhaust gas currently flowing in the exhaust gas system pipe 25 continues to be collected only by a time delay due to the length. When the confinement measurement is completed in the flowchart of FIG. 2 and normal measurement is started, it can be used as a result of reliable measurement of the exhaust gas radioactivity.

  In addition to automatically performing such concentration analysis of N-13 and F-18 at a predetermined time interval, the control unit 37 may perform step S12 at any time by an operation from the input unit of the operation display unit 38. An instruction for confinement measurement may be output.

<< Second Embodiment >>
Next, a radiation monitoring apparatus 30B that is a second embodiment of the radiation monitoring apparatus according to the present invention will be described with reference to FIG.
FIG. 4 is a configuration diagram of the radiation monitoring apparatus according to the second embodiment.
The radiation monitoring apparatus 30B of the present embodiment is different from the radiation monitoring apparatus 30A of the first embodiment in that a single Ge detector 32 is used as a γ-ray detector for the flow cells 31A and 31B in the first embodiment. In the present embodiment, the setting of the opening 33a of the movable shield 33 is switched by the actuator 34. In this embodiment, two Ge detectors (first γ-ray detectors) 32A and (second γ-ray detectors) ) 32B is arranged facing the respective flow cells 31A and 31B, and the combination of the Ge detector 32A and the flow cell 31A and the combination of the Ge detector 32B and the flow cell 31B are separated from each other by the fixed shield 50. This is to prevent the background from becoming high during measurement.

Corresponding to such a configuration, the movable shield 33 and the actuator 34 are not required in this embodiment. In the present embodiment, the γ-ray detection signals from the Ge detector 32A and the Ge detector 32B are first input to the input switching device 40. The input switching device 40 is controlled by the control unit 37 to input the γ-ray detection signal from the Ge detector 32A to the wave height analyzer 35 in the normal measurement state and to the Ge detector 32B in the confinement measurement state. Is input to the wave height analyzer 35.
Other configurations are the same as those of the first embodiment, and the same configurations as those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted.
In the present embodiment, steps S14 and S20 in the flowchart of FIG. 2 are not necessary.

  In the present embodiment, the measurement line (for normal use) 51 is a flow cell 31A in the “first measurement piping” described in the claims, and the measurement line (for confinement) 52 is the “second measurement piping” in the claims. Corresponds to the “first flow cell” recited in the claims, the flow cell 31B corresponds to the “second flow cell” recited in the claims, and the three-way valves 53A and 53B correspond to the “confining means” recited in the claims.

  In the present embodiment, as in the first embodiment, when the concentration of F-18 that is not normally detected is deteriorated in performance, abnormality or the like in the exhaust gas recombiner 10, the exhaust gas condenser 11, and the dehumidifying cooler 12, Performance of the exhaust gas recombiner 10, the exhaust gas condenser 11, and the dehumidifying cooler 12 when hydrogen fluoride is mixed with non-condensable gas or when hydrogen fluoride contained in moisture that has not been removed is detected. It can be determined that deterioration or abnormality has occurred.

According to this embodiment, since the movable shield 33 and the actuator 34 are not used, the number of components that are mechanically driven is reduced, and the reliability is improved.
In this embodiment, the wave height analyzer 35 is used as one unit, and the input switching device 40 switches and inputs the γ-ray detection signals from the two Ge detectors 32A and 32B. However, the present invention is not limited to this. The input switching device 40 may be eliminated, and the γ-ray detection signals from the Ge detectors 32A and 32B may be input to the two wave height analyzers 35.

<< Third Embodiment >>
Next, a radiation monitoring apparatus 30C, which is a third embodiment of the radiation monitoring apparatus according to the present invention, will be described with reference to FIGS.
FIG. 5 is a configuration diagram of the radiation monitoring apparatus according to the third embodiment. FIG. 6 shows a steady state of decay curves of both activities when two radionuclides having different half-lives are present. It is a figure which shows the relationship superimposed on the radioactivity at the time of normal measurement.
The radiation monitoring apparatus 30C of this embodiment differs from the radiation monitoring apparatus 30A of the first embodiment in that (1) the movable shield 33 and the actuator 34 are deleted, and (2) the three-way valves 53A and 53B. Instead, as shown in FIG. 5, in the piping configuration branched to the parallel measurement line (for normal use) 51 and measurement line (for containment) 52, on the upstream side and downstream side of the flow cell 31 </ b> B of the measurement line (for containment) 52. This is the point of providing valves 55A and 55B, which are solenoid valves of a ball-shaped valve.

The valves 55A and 55B are, for example, “open” when not energized and “closed” electromagnetically, and are controlled by the control unit 37 to be open when in a normal measurement state, and closed when performing confinement measurement.
Other configurations are the same as those of the first embodiment, and the same configurations as those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted.
In the present embodiment, steps S14 and S20 in the flowchart of FIG. 2 are not necessary.

In the normal measurement state, the exhaust gas collected by the sampling pipe (collection) 22 is in the open state of the valves 55A and 55B, so that both the measurement line (for normal use) 51 and the measurement line (for confinement) 52 etc. Flow distributed in quantity. The Ge detector 32 detects radiation from both the flow cells 31 </ b> A and 31 </ b> B and outputs a γ-ray detection signal to the wave height analyzer 35.
On the other hand, in the case of confinement measurement, the exhaust gas collected by the sampling pipe (collection) 22 flows through the measurement line (normal use) 51 because the valves 55A and 55B are closed. The Ge detector 32 detects radiation from both the flow cells 31 </ b> A and 31 </ b> B and outputs a γ-ray detection signal to the wave height analyzer 35.
Therefore, the Ge detector 32 detects radiation from the exhaust gas flowing through the flow cell 31A and the exhaust gas confined in the flow cell 31B.

  In the present embodiment, the measurement line (for normal use) 51 is a flow cell 31A in the “first measurement piping” described in the claims, and the measurement line (for confinement) 52 is the “second measurement piping” in the claims. Corresponds to the “first flow cell” recited in the claims, the flow cell 31B corresponds to the “second flow cell” recited in the claims, and the valves 55A and 55B correspond to the “confining means” recited in the claims.

As described above in the first embodiment, the sample pipe (return) 23 is provided with the pump 59, provided with a flow meter and a flow control valve, and the flow meter and the flow control valve are connected to the control unit 37. The sample pipe (collection) 22 is provided with a flow rate adjustment valve 57 and a flow meter 58, and the opening degree of the flow rate adjustment valve 57 is controlled by the control unit 37, so that the sample pipe (collection) 22 and sample pipe ( Return) It is assumed that the flow rate is controlled so that the exhaust gas flow velocity of 23 becomes the same as that in the normal measurement state.
Moreover, the flow path resistance of the measurement line 51 including the flow cell 31A and the measurement line 52 including the flow cell 31B is small, and the time-average atomic number density of the exhaust gas in the flow cell 31A is the same in the normal measurement state and the confinement measurement state. .

In FIG. 6, the horizontal axis represents time, and the vertical axis represents a logarithmic display of the count rate C _m (corresponding to radioactivity) for each elapsed time. Short radionuclide Curve C _A half-life, that is, show the contribution of N-13, the curve C _B Long radionuclide half-life, that is, indicating the contribution of the F-18.
Each _T A, _{T B} is in the Figure 6 shows the half-life of N-13, F-18.
By adopting such a configuration, when the concentrations A and B of N-13 and F-18 contained in the exhaust gas are in a steady state, when switching from the normal measurement state to the confinement measurement state at time t ₀ , N-13, The counting rate C _m (t _i ) corresponding to the 511 keV γ-ray energy associated with F-18 positron emission is due to the contribution from both flow cells 31A and 31B in the normal measurement state as shown in FIG. When the confinement measurement starts at the level of {2 × (A + B)}, the flow cell 31A continues to contribute to the (A + B) level, but the contribution of the flow cell 31B starts from the level of (A + B) to the curve C. It switched to _{which a} and curve C _B is summed.

式（２）で示した差分の二乗の総和を最小となる定数Ａ，Ｂを求める。そして、得られた定数Ａ，ＢがＮ−１３，Ｆ−１８それぞれの濃度に対応する。 Therefore, the evaluation function C (t _i ) can be replaced by the following equation (3):

Constants A and B that minimize the sum of the squares of the differences shown in Expression (2) are obtained. The obtained constants A and B correspond to the respective densities of N-13 and F-18.

  In this embodiment as well as the first embodiment, if the concentration of F-18 that is not normally detected is deteriorated in performance, abnormality or the like in the exhaust gas recombiner 10, the exhaust gas condenser 11, and the dehumidifying cooler 12, non-detection occurs. Degradation of performance of exhaust gas recombiner 10, exhaust gas condenser 11, and dehumidifying cooler 12 due to hydrogen fluoride mixed with condensable gas or hydrogen fluoride contained in moisture that has not been removed. Alternatively, it can be determined that an abnormality has occurred.

  According to this embodiment, since the movable shield 33 and the actuator 34 are not used, the number of components that are mechanically driven is reduced, and the reliability is improved.

<< Fourth Embodiment >>
As described above, in the first to third embodiments, the measurement line (for normal use) 51 and the measurement line (for confinement) 52 are provided, and in principle, the sampling pipe (collecting) 22 and the sampling pipe (return) 23 are provided. However, the present invention is not limited to this.
In the radiation monitoring apparatus 30C having the configuration of the third embodiment shown in FIG. 5, the measurement line (for normal use) 51 may be deleted and only the measurement line (for confinement) 52 may be used.
In the radiation monitoring apparatus having such a configuration, in the normal measurement state, the valves 55A and 55B are opened and the radiation is detected by the Ge detector 32, and in the confinement measurement, the valves 55A and 55B are closed and the Ge detection is performed. The detector 32 detects radiation.

The valves 55 </ b> A and 55 </ b> B in the present embodiment correspond to “confining means” recited in the claims.
In this case, the evaluation function C (t _i ) is expressed by the equation (1), and the concentrations of N-13 and F-18 are easily calculated.

In the radiation detection apparatus of the present embodiment, the pump 59 provided in the sampling pipe (return) 23 described above, the flow rate adjustment valve 57 provided in the sampling pipe (collection) 23, and the flow meter 58 are provided in the control unit 37. When connected and in the confinement measurement state, the pump is stopped under the control of the control unit 37, and the control operation of the flow rate adjusting valve 57 is stopped.
When the confinement measurement state is switched to the normal measurement state, the pump 59 is started under the control of the control unit 37, and the control operation of the flow rate adjustment valve 57 is started. Even when normal measurement is resumed, the control unit 37 keeps the count rate of the exhaust gas until the exhaust gas staying in the sampling pipe (collecting) 22 in the confined measurement state by the timer control passes through the flow cell 31B. It is assumed that the signal processing device 36 does not transmit it to the operation display unit 38 so that it is not used as monitoring data.

<< Fifth Embodiment >>
Next, a radiation monitoring apparatus 30D, which is a fifth embodiment of the radiation monitoring apparatus according to the present invention, will be described with reference to FIGS.
FIG. 7 is a configuration diagram of the radiation monitoring apparatus according to the fifth embodiment. FIG. 8 is acquired by the signal processing apparatus in accordance with the control unit controlling the setting of the opening of the movable shield. FIG. 9 is a time chart showing whether the counting result is one of two flow cells, and FIG. 9 is a flowchart showing a control flow of “normal measurement” and “calculation of N-13 and F-18 concentrations”.
The radiation monitoring device 30D of this embodiment is different from the radiation monitoring device 30A of the first embodiment in that a three-way valve 53A is provided for a measurement line (for normal use) 51 and a measurement line (for confinement) 52 in the first embodiment. 53B, the flow of the exhaust gas as the sample can be switched, the exhaust gas is introduced into the measurement line (for confinement) 52, confined, and confinement measurement is performed. In this embodiment, the sampling pipe (collection) 22 is used. Is connected to a measurement line 51A having a flow cell 31A, then connected in the order of a delay pipe 54 and a measurement line 52A having a flow cell 31B, and finally a sampling pipe (return) 23 is connected to the downstream side of the measurement line 52A. As shown in FIG. 7, a Ge detector 32 surrounded by a movable shield (shield) 33 is disposed between the flow cell 31A and the flow cell 31B, as in the first embodiment.

  Other configurations are the same as those of the first embodiment, and the same configurations as those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  In the present embodiment, the measurement line 51A is the “first measurement pipe” described in the claims, the measurement line 52A is the “second measurement pipe” described in the claims, and the flow cell 31A is the “first measurement pipe”. The flow cell 31B corresponds to the “second flow cell” recited in the claims.

The length of the delay pipe is set according to the flow rate of the exhaust gas in the normal measurement state. For example, if the exhaust gas that has passed through the flow cell 31A is set to pass through the flow cell 31B after about 10 minutes, N-13 Since the half-life is about 10 minutes, it is sufficient for the counting rate of the Ge detector 32 for 511 keV energy γ rays emitted from the flow cell 31A and 511 keV energy γ rays emitted from the flow cell 31B. It is convenient to make a difference.
At least when passing through the flow cell 31B, the emission of γ-rays of energy of 511 keV from N-13 is reduced to about ½ of that when passing through the flow cell 31A.

Further, the control unit 37 according to the present embodiment uses the symbols (1) to (9) from the wave height analyzer 35 based on the radiation emitted from the flow cell 31A by the signal processor 36 as shown in the time chart of FIG. Nine sets of counting results of a predetermined time window Δt, for example, a count rate (first counting result) for a predetermined time window Δt for each target radionuclide corresponding to a preset energy window of 1 minute A set of the predetermined times indicated by reference numeral (10) from the wave height analyzer 35 based on the radiation emitted from the flow cell 31B after being periodically acquired from the analyzer 35 and stored in the storage device 36a in time series. The setting of the opening 33a of the movable shield 33 is controlled so as to obtain the window count result.
Incidentally, this preset energy window includes an energy window corresponding to 511 keV γ-ray energy by N-13 and F-18.
Accordingly, during the opening 33a is time [Delta] T _X movable shield 33 is open toward the flow cell 31A side, during the time [Delta] T _X in subsequent time Delta] t, the opening 33a of the movable shield 33 is a flow cell It opens toward the 31B side. After that, the opening 33a opens again toward the flow cell 31A and obtains the count results of nine sets of predetermined time windows Δt from the reference (11), and then opens toward the flow cell 31B and opens one set of predetermined time windows. It repeats acquiring the counting result of Δt.
In FIG. 8, the time required for setting the opening 33a by rotating the movable shield 33 by the actuator 34 is schematically shown.

Ｔ_Ａ，Ｔ_ＢはそれぞれＮ−１３，Ｆ−１８の半減期を示す。
式（４），（５）を定数Ａ，Ｂを未知数とした１次２元連立方程式として、信号処理装置３６において行列式計算で解いて、定数Ａ，Ｂを算出すれば、定数Ａ，ＢがＮ−１３，Ｆ−１８それぞれの濃度に対応する。 Here, if the counting result of 511 keV γ-rays corresponding to the code (1) is the count rate C ₁ (t _i ), the count rate C ₁ (t _i ) is expressed as the following equation (4), and the code ( If the counting result of 511 keV γ rays corresponding to 10) is the counting rate C ₂ (t _i + ΔT _X ), the counting rate C ₂ (t _i + ΔT _X ) is expressed as the following equation (5).

T _A and T _B represent the half-lives of N-13 and F-18, respectively.
If equations (4) and (5) are solved as a linear simultaneous equation with constants A and B as unknowns by determinant calculation in signal processor 36 and constants A and B are calculated, constants A and B Corresponds to the concentrations of N-13 and F-18, respectively.

(Control of “normal measurement” and “calculation of N-13 and F-18 concentrations”)
Next, the flow of control of “normal measurement” and “calculation of N-13 and F-18 concentrations” in the wave height analyzer 35, the signal processor 36, and the controller 37 will be described with reference to FIG.
The control unit 37 is program-controlled so as to calculate the concentration of N-13 and F-18 at a preset frequency for a predetermined time, for example, once every 10 minutes including the normal measurement state. Is checked (step S31). If it is the normal measurement timing (Yes), the process proceeds to step S32; otherwise (No), the process proceeds to step S37.

In step S32, the control unit 37 outputs a control signal of "Normal Measurement" to the signal processor 36, along with a timer is started t _A in the signal processing device 36, the count start from the signal processing unit 36 to the pulse height analyzer 35 A timing signal is output ("timer t _A start"). In the pulse height analyzer 35, the γ-ray detection signal from the Ge detector 32 is subjected to energy discrimination and integrated as a count value for each energy window (step S33; “radiation measurement at a predetermined time window Δt”). Next, the signal processing device 36 checks whether or not the timer t _A is equal to or greater than Δt (step S34). If it is equal to or greater than Δt (Yes), the process proceeds to step S35, and if it is less than Δt (No), the process proceeds to step S33. repeat.

  In step S35, the signal processing device 36 reads the count value for each energy window from the wave height analyzer 35, and counts the count rate (counting result) for the predetermined time window Δt for each target radionuclide corresponding to the preset energy window. ) And is stored in the storage device 36a together with the measurement start time data of the predetermined time window Δt (step S35; “store the counting result together with the measurement start time data”). Then, the signal processing device 36 resets the timer (step S36) and returns to step S31.

If the result of step S31 is No and the process proceeds to step S37, the control unit 37 controls the actuator 34 so that the opening 33a of the movable shield 33 is set to the flow cell 31A so far. ("Set the opening of the movable shield in the flow cell downstream from the delay pipe)).
In step S38, a measurement control signal on the flow cell 31B side is output to the signal processing device 36, the timer t _A is started in the signal processing device 36, and the timing for starting the counting from the signal processing device 36 to the wave height analyzer 35 is obtained. A signal is output (“timer t _A start”). In the pulse height analyzer 35, the γ-ray detection signal from the Ge detector 32 is subjected to energy discrimination and integrated as a count value for each energy window (step S39; “radiation measurement at a predetermined time window Δt”). Next, the signal processing device 36 checks whether or not the timer t _A is equal to or greater than Δt (step S40). If it is equal to or greater than Δt (Yes), the process proceeds to step S41, and if it is less than Δt (No), the process proceeds to step S39. repeat.

  In step S41, the signal processing device 36 reads the count value for each energy window from the wave height analyzer 35, and the second count rate (second count) for the predetermined time window Δt corresponding to the energy window of 511 keV γ-ray energy. Result) is calculated and stored in the storage device 36a together with the measurement start time data of the predetermined time window Δt (step S41; “second count result is stored together with measurement start time data”). Then, the signal processing device 36 resets the timer (step S42).

In step S43, the control unit 37 outputs a control signal to the actuator 34 so that the opening 33a of the movable shield 33 that has been set so as to face the flow cell 31B is movable so as to face the flow cell 31A. The type shield 33 is rotated (“the opening of the movable shield is set in the flow cell upstream of the delay pipe”).
In step S44, the signal processing device 36 reads the second count rate stored together with the measurement start time data in the storage device 36a from the storage device 36a in step S41, and then in step S34, the measurement start time is stored in the storage device 36a. Among the count rates stored together with the data, the first count rate (first count) corresponding to the 511 keV energy window of the count start time data that is back by ΔT _X from the count start time data of the second count rate Results) are read from the storage device 36a, and the constants A and B are calculated by solving the simultaneous equations (4) and (5) described above ("Analyzing N-13 and F-18 concentrations").

In step S45, the signal processing device 36 checks whether or not the F-18 density is greater than or equal to a threshold value. If it is equal to or greater than the threshold (Yes), the process proceeds to step S46, and an alarm is output to the operation display unit 38. For example, the operation display unit 38 is caused to display “Exhaust gas recombiner, exhaust gas condenser, dehumidifying cooler abnormal!”. Here, as the F-18 concentration, it is more appropriate to use the relative ratio (B / A) based on the constants A and B than to use the constant B itself calculated in step S44.
If it is less than the threshold value in step S45 (No), the signal processing device 36 ends the series of confinement measurement processes and starts the normal measurement process.
Upon completion of the confinement measurement processing, the signal processing device 36 transmits the calculated F-18 concentration to the operation display unit 38, and the operation display unit 38 monitors the trend of time series information of the F-18 concentration. By performing, you may make it monitor continuously whether the waste gas recombiner 10, the waste gas condenser 11, and the dehumidification cooler 12 are in a normal state.

  When the radiation measurement for the analysis of the N-13 and F-18 concentrations in steps S37 to S46 and the subsequent calculation process are completed, the signal processing device 36 applies the γ-ray detection signal from the flow cell 31A of the measurement line 51A. The count value for each energy window output from the wave height analyzer 35 is read, and the count rate for each target radionuclide corresponding to the preset energy window is calculated. The target count rate for each radionuclide is converted to the radioactivity concentration as it is or based on the detection efficiency, stored in the storage device 36a, and the time series information is sent to the operation display unit 38.

According to the radiation monitoring apparatus 30D of this embodiment, the concentration of F-18 can be calculated at predetermined time intervals, and if the exhaust gas recombiner 10, the exhaust gas condenser 11, and the dehumidifying cooler 12 are healthy, F- 18 is returned to the exhaust gas condenser drain pipe 19 in the chemical form of hydrogen fluoride, and the concentration of F-18 which is not normally detected is a non-condensable gas collected when performance deterioration or abnormality occurs in them. As a result, hydrogen fluoride contained in moisture that has not been removed is detected, and the performance deterioration or abnormality of the exhaust gas recombiner 10, the exhaust gas condenser 11, and the dehumidifying cooler 12 is detected. It can be determined that it has occurred.
In particular, since the concentration of the radionuclide can be detected from the count rate with respect to the peak value corresponding to 511 keV γ-rays, it can be detected with higher sensitivity than the detection with the hydrogen concentration.

  Further, in the present embodiment, even when normal measurement is performed, the measurement lines 51A and 52A are also included in radiation measurement for analysis of N-13 and F-18 concentrations and subsequent calculation processing. Since a predetermined amount of exhaust gas flows, even if the sampling pipe (collecting) 22 and the sampling pipe (return) 23 are long, there is only a time delay due to the length of the sampling pipe (collecting) 22 and the sampling pipe (return) 23. Since the state of continuously collecting the exhaust gas continues, the radiation measurement for the analysis of the N-13 and F-18 concentrations and the subsequent calculation processing are completed in the flowchart of FIG. Can be used as a result of reliable measurement of the exhaust gas radioactivity.

  Moreover, since the three-way valves 53A and 53B used in the first and second embodiments are not necessary, the mechanical reliability of the radiation monitoring apparatus 30D is improved.

<< Sixth Embodiment >>
Next, a radiation monitoring apparatus 30E that is a sixth embodiment of the radiation monitoring apparatus according to the present invention will be described with reference to FIG.
FIG. 10 is a configuration diagram of the radiation monitoring apparatus according to the sixth embodiment.
The radiation monitoring apparatus 30E of this embodiment is different from the radiation monitoring apparatus 30D of the fifth embodiment in that, in the first embodiment, one Ge detector 32 is used as a γ-ray detector for the flow cells 31A and 31B. In the present embodiment, the setting of the opening 33a of the movable shield 33 is switched by the actuator 34. In this embodiment, two Ge detectors (first γ-ray detectors) 32A and (second γ-ray detectors) ) 32B is arranged in each of the flow cells 31A and 31B, and the combination of the Ge detector 32A and the flow cell 31A and the combination of the Ge detector 32B and the flow cell 31B are separated by the fixed shield 50, so that the mutual radiation measurement can be performed. It is a point that does not raise the ground.

Corresponding to such a configuration, the movable shield 33 and the actuator 34 are not required in this embodiment. In the present embodiment, the γ-ray detection signals from the Ge detector 32A and the Ge detector 32B are first input to the input switching device 40. The input switching device 40 is controlled by the control unit 37 to input the γ-ray detection signal from the Ge detector 32A to the wave height analyzer 35 during normal measurement and to the Ge detector during measurement on the flow cell 31B side. The γ-ray detection signal from 32B is input to the wave height analyzer 35.
Other configurations are the same as those of the fifth embodiment, and the same configurations as those of the fifth embodiment are denoted by the same reference numerals, and redundant description is omitted.
In the present embodiment, steps S37 and S43 in the flowchart of FIG. 9 are not necessary.

  In the present embodiment, the measurement line 51A is the “first measurement pipe” described in the claims, the measurement line 52A is the “second measurement pipe” described in the claims, and the flow cell 31A is the “first measurement pipe”. The flow cell 31B corresponds to the “second flow cell” recited in the claims.

  In the present embodiment as well as in the fifth embodiment, if the concentration of F-18 that is not normally detected is deteriorated in performance, abnormality or the like in the exhaust gas recombiner 10, the exhaust gas condenser 11, and the dehumidifying cooler 12, non-detection occurs. Degradation of performance of exhaust gas recombiner 10, exhaust gas condenser 11, and dehumidifying cooler 12 due to hydrogen fluoride mixed with condensable gas or hydrogen fluoride contained in moisture that has not been removed. Alternatively, it can be determined that an abnormality has occurred.

According to this embodiment, since the movable shield 33 and the actuator 34 are not used, the number of components that are mechanically driven is reduced, and the reliability is improved.
In this embodiment, the wave height analyzer 35 is used as one unit, and the input switching device 40 switches and inputs the γ-ray detection signals from the two Ge detectors 32A and 32B. However, the present invention is not limited to this. The input switching device 40 may be eliminated, and the γ-ray detection signals from the Ge detectors 32A and 32B may be input to the two wave height analyzers 35.

<< Seventh Embodiment >>
Next, a radiation monitoring apparatus 30F, which is a seventh embodiment of the radiation monitoring apparatus according to the present invention, will be described with reference to FIG.
FIG. 11 is a configuration diagram of the radiation monitoring apparatus according to the seventh embodiment.
The radiation monitoring apparatus 30F of the present embodiment is different from the radiation monitoring apparatus 30D of the fifth embodiment in that (1) the movable shield 33 and the actuator 34 are deleted, and (2) as shown in FIG. A branch point that branches off to the bypass pipe 63 and the delay pipe 54 is provided downstream of the measurement line 51A, and the three-way valve 61 is arranged there, and the downstream sides of the bypass pipe 63 and the delay pipe 54 join to connect to the measurement line 52A. This is the point.

(Configuration for measuring pipe flow switching)
A configuration for switching the flow by the three-way valve 61 will be described below.
The three-way valve 61 is a solenoid valve switching valve that is energized and controlled by the control unit 37. When the three-way valve 61 is not energized, the exhaust gas from the measurement line 51A flows through the delay line 54 to the measurement line 52A, and when energized, the exhaust gas from the measurement line 51A flows through the bypass pipe 63 to the measurement line 52A.

  In the case of normal measurement, the exhaust gas collected by the sampling pipe (collection) 22 is the exhaust gas after passing through the measurement line 51A because the three-way valve 61 is open in the direction (white display direction) as shown in FIG. Flows through the delay pipe 54 and then through the measurement line 52A.

  Accordingly, the Ge detector 32 detects, from the exhaust gas passing through the flow cell 31B, the radiation from the exhaust gas having a reduced radioactivity concentration that passed through the flow cell 31A about 10 minutes ago and the exhaust gas currently passing through the flow cell 31A. Thus, a γ-ray detection signal is output to the wave height analyzer 35.

  On the other hand, in the case of a radiometer for analyzing N-13 and F-18 concentrations, the three-way valve 61 is indicated by an arrow as shown in FIG. The exhaust gas after passing through the measurement line 51A flows to the bypass pipe 63 side by the three-way valve 61 and then flows through the measurement line 52A.

  Accordingly, the Ge detector 32 detects radiation from the exhaust gas having substantially the same radioactive concentration as the exhaust gas passing through the flow cell 31A from both the flow cells 31A and 31B, and outputs a γ-ray detection signal to the wave height analyzer 35.

  In the present embodiment, the measurement line 51A is the “first measurement pipe” described in the claims, the measurement line 52A is the “second measurement pipe” described in the claims, and the flow cell 31A is the “first measurement pipe”. The flow cell 31B corresponds to the “second flow cell” recited in the claims, and the three-way valve 61 corresponds to the “flow switching means” recited in the claims.

(Radiation measurement method)
Next, the control in which the control unit 37 performs “normal measurement” and “measurement for N-13 and F-18 concentration analysis” using the above-described flow switching configuration of the measurement line 52A will be described.
At the time of normal measurement, the control unit 37 puts the three-way valve 61 in a non-energized state, causes the exhaust gas that has passed through the delay pipe 54 to flow through the measurement line 52A, and a predetermined time window for each target radionuclide corresponding to a preset energy window. The count rate (first count result) with respect to Δt is periodically acquired from the wave height analyzer 35 by the signal processing device 36 and is stored in the storage device 36a in time series and transmitted to the operation display unit 38. .
Incidentally, this preset energy window includes an energy window corresponding to 511 keV γ-ray energy by N-13 and F-18.

  Then, the control unit 37 energizes the three-way valve 61 for a period of time equal to or longer than the predetermined time window Δt at a constant time interval, for example, about once every 20 minutes, and connects the bypass pipe 63 to the measurement line 52A. The exhaust gas that has passed is sent to the signal processing unit 36 from the wave height analyzer 35 and the count rate corresponding to the energy window corresponding to 511 keV γ-ray energy by N-13 and F-18 of the predetermined time window Δt (second count result) It is acquired and stored in the storage device 36a.

Here, the time required to reach the flow cell 31B via the delay pipe 54 after passing through the flow cell 31A is ΔT _X, and the time required to reach the flow cell 31B via the bypass pipe 63 after passing through the flow cell 31A is ΔT _Y And
By the way, ΔT _Y is the value of the order of seconds. Further, it is assumed that the concentrations of N-13 and F-18 in the exhaust gas are in a steady state with little fluctuation at a time length of interest, for example, a time width of about 10 minutes. Then, the count rate C ₃ (t _i ) corresponding to the energy window of 511 keV at the normal measurement immediately before the measurement for F-18 concentration analysis is expressed by the following equation (6), and N−13, F− The count rate C ₄ (t _J ) corresponding to the energy window of 511 keV at the time of measurement for 18 concentration analysis is expressed by the following equation (7).

The simultaneous equations with the constants A and B displayed in equations (6) and (7) as unknowns can be easily solved by performing determinant calculations in the signal processing device 36.
Based on the calculated constants A and B corresponding to the radioactivity concentration, as in the fifth embodiment, the control unit 37 determines whether the relative ratio (B / A) is equal to or greater than a threshold value. If it is after the threshold value, an alarm is output to the operation display unit 38. Further, every time the calculated relative ratio (B / A) is obtained, the control unit 37 transmits to the operation display unit 38, and the operation display unit 38 monitors the trend of the time series information of the F-18 concentration. You may make it monitor continuously whether the exhaust gas recombiner 10, the exhaust gas condenser 11, and the dehumidification cooler 12 are in a normal state.

  After the “measurement for concentration analysis of N-13 and F-18” is completed, when returning to “normal measurement”, the three-way valve 61 causes the exhaust gas from the measurement line 51A to flow to the delay pipe 54 side. To be precise, since there is exhaust gas that has accumulated during the "measurement for concentration analysis of N-13 and F-18" in the delay pipe 54, until all the exhaust gas passes through the flow cell 31B. The result of the “normal measurement” for about 10 minutes will have an error. Therefore, the measurement result of the first 10 minutes of “normal measurement” after the completion of “measurement for N-13 and F-18 concentration analysis” is used as a reference value, and the measurement of “normal measurement” for 10 minutes thereafter. The value is preferably a positive measured value.

  In this embodiment as well as the first embodiment, if the concentration of F-18 that is not normally detected is deteriorated in performance, abnormality or the like in the exhaust gas recombiner 10, the exhaust gas condenser 11, and the dehumidifying cooler 12, non-detection occurs. Degradation of performance of exhaust gas recombiner 10, exhaust gas condenser 11, and dehumidifying cooler 12 due to hydrogen fluoride mixed with condensable gas or hydrogen fluoride contained in moisture that has not been removed. Alternatively, it can be determined that an abnormality has occurred.

  According to this embodiment, since the movable shield 33 and the actuator 34 are not used, the number of components that are mechanically driven is reduced, and the reliability is improved.

FIG. 1 is a schematic diagram of a primary plant in a boiling water nuclear power plant to which a radiation monitoring apparatus according to an embodiment of the present invention is applied, a device layout diagram of a gas waste treatment system, and a radiation monitoring apparatus installed in the gas waste treatment system. FIG. It is a flowchart of the flow of control which calculates the density | concentration of the radionuclide which confine | seals a sample and discharge | releases the gamma ray of the same energy corresponding to a predetermined | prescribed energy window, for example, N-13 and F-18. It is a figure which shows the decay curve of both the radioactivity in case two radionuclides from which the length of a definite period differs exist. It is a block diagram of the radiation monitoring apparatus of 2nd Embodiment. It is a block diagram of the radiation monitoring apparatus of 3rd Embodiment. It is a figure which shows the relationship with which the decay curve of both radioactivity is superimposed with the radioactivity at the time of normal measurement of a steady state in case two radionuclides with different half-life length exist. It is a block diagram of the radiation monitoring apparatus of 5th Embodiment. The time chart which shows which of the two flow cells the count result acquired with a signal processing apparatus according to a control part controlling the setting of the opening part of a movable shield. It is a flowchart which shows the flow of control of "normal measurement" and "calculation of the density | concentration of N-13 and F-18." It is a block diagram of the radiation monitoring apparatus of 6th Embodiment. It is a block diagram of the radiation monitoring apparatus of 7th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reactor 2 Core 3 Main steam pipe 4 Turbine 5 Condenser 6 Main steam extraction piping 7 Air extractor 8 Extraction pipe 9 Exhaust gas preheater 10 Exhaust gas recombiner 11 Exhaust gas condenser 12 Dehumidification cooler 13 Activated carbon type rare gas Hold-up device 13a Hold-up tank 14 Exhaust gas filter 15 Exhaust gas extractor 16 Main exhaust pipe 19 Exhaust gas condenser drain pipe 22 Sampling pipe (collecting)
23 Sampling piping (return)
25 Exhaust gas piping 30, 30A, 30B, 30C, 30D, 30E, 30F Radiation monitoring device 31A Flow cell (first flow cell)
31B flow cell (second flow cell)
32 Ge detector (γ-ray detector)
32A Ge detector (first γ-ray detector)
32B Ge detector (second γ-ray detector)
33 Movable shield (shield)
33a Opening 34 Actuator 35 Wave height analyzer (wave height analyzer)
36 Signal processing device (signal processing means)
36a Storage device (storage means)
37 Control part (control means)
38 Operation display unit 40 Input switching device 50 Fixed shield 51, 51A Measurement line (for normal use) (first measurement pipe)
52,52A Measurement line (for confinement) (second measurement pipe)
53A, 53B Three-way valve (confinement means)
54 Delay piping 55A, 55B Valve (containment means)
57 Flow control valve 58 Flow meter 59 Pump 61 Three-way valve (flow switching means)
63 Bypass pipe

Claims (8)

a γ-ray detector, a wave height analyzing means for analyzing the wave height based on the crest value of the γ-ray detection signal from the γ-ray detector, and a signal processing means for processing the counting result subjected to the wave height analysis, and continuously In a radiation monitoring device that monitors the leakage of radioactivity by measuring the concentration of nuclides that emit gamma rays contained in the flowing sample,
A first flow cell and a second flow cell arranged facing the γ-ray detector;
A first measurement pipe connected before and after the first flow cell to flow the sample at a predetermined flow rate;
A second measurement pipe connected before and after the second flow cell and parallel to the first measurement pipe;
Confinement means for introducing and confining the sample into the second flow cell;
A shield disposed around the γ-ray detector and having a movable opening;
An actuator that can be set by switching the opening of the shield to the first flow cell side or the second flow cell side;
Control means for controlling the respective operations of the confinement means, the actuator, and the signal processing means,
The signal processing means has storage means for storing the counting results in time series,
The control means includes
In the normal measurement state, the actuator is configured to set the opening of the shield on the first flow cell side, and the signal processing means is configured to output the counting result based on the γ rays from the sample flowing through the first flow cell. As well as processing
In the confinement measurement state, the confinement means is controlled so that the sample is introduced into the second flow cell and confined, and the actuator is controlled so that the opening of the shield is located on the second flow cell side. The counting result of a specific peak value of the γ-ray detection signal obtained for the sample confined in the second flow cell by the signal processing means is set in the storage means in time series. Remember
The signal processing means is controlled by the control means, and a plurality of radioactive materials having different decay constants that emit γ-rays of energy corresponding to the specific peak value based on the counting results stored in time series. Radiation monitoring device characterized by quantitative analysis of nuclide concentration. a γ-ray detector, a wave height analyzing means for analyzing the wave height based on the crest value of the γ-ray detection signal from the γ-ray detector, and a signal processing means for processing the counting result subjected to the wave height analysis, and continuously In a radiation monitoring device that monitors the leakage of radioactivity by measuring the concentration of nuclides that emit gamma rays contained in the flowing sample,
A first γ-ray detector and a second γ-ray detector as the γ-ray detector;
Furthermore,
A first flow cell disposed facing the first γ-ray detector and a second flow cell disposed facing the second γ-ray detector;
A first measurement pipe connected before and after the first flow cell to flow the sample at a predetermined flow rate;
A second measurement pipe connected before and after the second flow cell and parallel to the first measurement pipe;
Confinement means for introducing and confining the sample into the second flow cell;
Control means for controlling the confinement means and the signal processing means,
The signal processing means has storage means for storing the counting results in time series,
The control means includes
In the normal measurement state, the signal processing means processes the counting result based on the γ rays from the sample flowing through the first flow cell,
In the confinement measurement state, the confinement means is controlled to confine after introducing the sample into the second flow cell, and the signal processing means obtains at least the sample confined in the second flow cell. Storing the counting result of a specific peak value in the γ-ray detection signal received in the storage means in time series,
The signal processing means includes a plurality of positron emitting nuclides having different decay constants that emit γ-rays having energy corresponding to 511 keV as the specific peak value based on the stored count result controlled by the control means. A radiation monitoring apparatus characterized by quantitatively analyzing the concentration of a certain radionuclide. a γ-ray detector, a wave height analyzing means for analyzing the wave height based on the crest value of the γ-ray detection signal from the γ-ray detector, and a signal processing means for processing the counting result subjected to the wave height analysis, and continuously In a radiation monitoring device that monitors the leakage of radioactivity by measuring the concentration of nuclides that emit gamma rays contained in the flowing sample,
A first flow cell and a second flow cell arranged facing the γ-ray detector;
A first measurement pipe connected before and after the first flow cell to flow the sample at a predetermined flow rate;
A second measurement pipe connected before and after the second flow cell and parallel to the first measurement pipe;
Confinement means for introducing and confining the sample into the second flow cell;
Control means for controlling opening and closing of the confinement means and operation of the signal processing means;
With
The signal processing means has storage means for storing the counting results in time series,
The control means includes
In the normal measurement state, the confinement means is opened, and the signal processing means is allowed to process the counting result based on the γ rays from the sample flowing through the first flow cell,
In the confinement measurement state, the confinement means is closed for a predetermined time, and a specific peak value of the γ-ray detection signal obtained for the sample confined in the second flow cell by the signal processing means is obtained. The counting results of the above are stored in the storage means in time series,
The signal processing means includes a plurality of positron emitting nuclides having different decay constants that emit γ-rays having energy corresponding to 511 keV as the specific peak value based on the stored count result controlled by the control means. A radiation monitoring apparatus characterized by quantitatively analyzing the concentration of a certain radionuclide. a γ-ray detector, a wave height analyzing means for analyzing the wave height based on the crest value of the γ-ray detection signal from the γ-ray detector, and a signal processing means for processing the counting result subjected to the wave height analysis, and continuously In a radiation monitoring device that monitors the leakage of radioactivity by measuring the concentration of nuclides that emit gamma rays contained in the flowing sample,
A flow cell arranged facing the γ-ray detector;
A measurement pipe connected to the front and rear of the flow cell to flow the sample at a predetermined flow rate;
A confining means provided in the measurement pipe, provided on the upstream side and the downstream side of the flow cell, respectively, for introducing and confining the sample into the flow cell;
Control means for controlling opening and closing of the confinement means and operation of the signal processing means;
With
The signal processing means has storage means for storing the counting results in time series,
The control means includes
In the normal measurement state, the confinement means is opened, and the signal processing means is configured to process the counting result based on γ rays from the sample flowing through the flow cell,
In the confinement measurement state, the confinement means is closed for a predetermined time, and the signal processing means counts a specific peak value in the γ-ray detection signal obtained for the sample confined in the flow cell. The results are stored in the storage means in time series,
The signal processing means includes a plurality of positron emitting nuclides having different decay constants that emit γ-rays having energy corresponding to 511 keV as the specific peak value based on the stored count result controlled by the control means. A radiation monitoring apparatus characterized by quantitatively analyzing the concentration of a certain radionuclide. a γ-ray detector, a wave height analyzing means for analyzing the wave height based on the crest value of the γ-ray detection signal from the γ-ray detector, and a signal processing means for processing the counting result subjected to the wave height analysis, and continuously In a radiation monitoring device that monitors the leakage of radioactivity by measuring the concentration of nuclides that emit gamma rays contained in the flowing sample,
A first flow cell and a second flow cell arranged facing the γ-ray detector;
A first measurement pipe connected before and after the first flow cell to flow the sample at a predetermined flow rate;
A delay pipe having a predetermined length connected to the downstream side of the first measurement pipe;
A second measurement pipe connected before and after the second flow cell and connected downstream of the delay pipe;
A shield disposed around the γ-ray detector and having a movable opening;
An actuator that can be set by switching the opening of the shield to the first flow cell side or the second flow cell side;
Control means for controlling the operation of the actuator and the operation of the signal processing means,
The signal processing means has storage means for storing the counting result,
The control means includes
In the normal measurement state, the actuator has the opening of the shield set on the first flow cell side, and the signal processing means causes the counting result based on the γ-rays from the sample flowing through the first flow cell. Storing the first counting result in the storage means in time series,
The actuator is controlled at a predetermined frequency so as to change the setting of the opening of the shield to the second flow cell side, and in that state, the signal processing means causes γ rays from the sample flowing through the second flow cell. Storing the counting result based on the second counting result in the storage means;
The signal processing means is controlled by the control means, and based on the stored second count result and the first count result before a predetermined time, γ-rays of energy corresponding to a specific peak value A radiation monitoring apparatus characterized in that the concentration of a plurality of radionuclides with different decay constants is quantitatively analyzed. a γ-ray detector, a wave height analyzing means for analyzing the wave height based on the crest value of the γ-ray detection signal from the γ-ray detector, and a signal processing means for processing the counting result subjected to the wave height analysis, and continuously In a radiation monitoring device that monitors the leakage of radioactivity by measuring the concentration of nuclides that emit gamma rays contained in the flowing sample,
A first γ-ray detector and a second γ-ray detector as the γ-ray detector;
Furthermore,
A first flow cell disposed facing the first γ-ray detector and a second flow cell disposed facing the first γ-ray detector;
A first measurement pipe connected before and after the first flow cell to flow the sample at a predetermined flow rate;
A delay pipe having a predetermined length connected to the downstream side of the first measurement pipe;
A second measurement pipe connected before and after the second flow cell and connected downstream of the delay pipe;
Control means for controlling the operation of the signal processing means,
The signal processing means has storage means for storing the counting result,
The control means includes
In the normal measurement state, the signal processing means stores the counting result based on the first γ-ray detector in the storage means in time series as the first counting result,
Storing the counting result based on the second γ-ray detector in the signal processing means at a predetermined frequency in the storage means as a second counting result;
The signal processing means is controlled by the control means to generate γ-rays of energy corresponding to a specific peak value based on the stored second count result and the first count result a predetermined time ago. A radiation monitoring apparatus characterized by quantitatively analyzing the concentration of a plurality of radionuclides having different decay constants. a γ-ray detector, a wave height analyzing means for analyzing the wave height based on the crest value of the γ-ray detection signal from the γ-ray detector, and a signal processing means for processing the counting result subjected to the wave height analysis, and continuously In a radiation monitoring device that monitors the leakage of radioactivity by measuring the concentration of nuclides that emit gamma rays contained in the flowing sample,
A first flow cell and a second flow cell arranged facing the γ-ray detector;
A first measurement pipe connected before and after the first flow cell to flow the sample at a predetermined flow rate;
A delay pipe having a predetermined length connected to the downstream side of the first measurement pipe;
A bypass pipe connected in parallel with the delay pipe on the downstream side of the first measurement pipe;
A second measurement pipe connected before and after the second flow cell;
A flow switching means for switching the sample diversion through the delay pipe and the sample diversion through the bypass pipe to supply to the second measurement pipe;
Control means for controlling the operation of the signal processing means and the flow switching means,
The signal processing means has storage means for storing the counting result,
The control means includes
In the normal measurement state, the flow switching means is set to a state in which the sample via the delay pipe flows through the second measurement pipe, and the sample flowing through the first and second flow cells in the signal processing means. Storing the counting result based on the time series in the storage means as a first counting result,
Based on the sample flowing through the first and second flow cells in the signal processing means, the flow switching means is brought into a state where the sample via the bypass pipe flows in the second measurement pipe at a predetermined frequency. Storing the counting result in the storage means as a second counting result;
The signal processing means is controlled by the control means to generate γ-rays of energy corresponding to a specific peak value based on the stored second count result and the first count result a predetermined time ago. A radiation monitoring apparatus characterized by quantitatively analyzing the concentration of a plurality of radionuclides having different decay constants. The different from the plurality of radioactive nuclides decay constant that emit γ-rays of energy corresponding to a particular peak value, according to claim 1 and claim characterized in that it is a positron-emitting nuclide which emits γ-rays of 511 keV 5 the radiation monitoring device according to any one of claims 7.

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