A one-loop pressure boundary leakage radiation monitoring device and a monitoring method thereof

Abstract

The present application relates to the technical field of nuclear power plant radiation monitoring, and particularly relates to a primary loop pressure boundary leakage radiation monitoring device and a monitoring method thereof. 18 F has a long half-life, positron annihilation and other characteristics, and the gamma-gamma digital coincidence measurement technology is applied to the primary loop pressure boundary leakage monitoring, quantitative monitoring of the primary loop pressure boundary leakage rate is realized, the anti-interference capability of the system is improved, the detection lower limit of the system is reduced, and the system is miniaturized to a certain extent.

Description

Technical Field

[0001] This invention relates to the field of radiation monitoring technology in nuclear power plants, specifically to a primary loop pressure boundary leakage radiation monitoring device and its monitoring method. Background Technology

[0002] The primary circuit pressure boundary leakage monitoring device is an important component of the nuclear power plant process radiation monitoring system. By continuously monitoring the primary circuit pressure boundary of the nuclear power plant, it can determine the leakage situation of the primary circuit pressure boundary and provide data reference for nuclear power plant operators.

[0003] Commonly used monitoring methods for the primary loop pressure boundary in nuclear power plants include radioactive aerosol monitoring, iodine and inert gas monitoring, and... 13 Nitrogen (N) monitoring methods. Radioactive aerosol, iodine, and inert gas monitoring methods, by monitoring corrosion products in the coolant (…). 59 Fe、 51 Cr, etc.) and fission products ( 131 I, 85 Kr、 133 Xe, etc.), thereby qualitatively judging the leakage situation at the primary circuit pressure boundary; 13 Nitrogen (N) monitoring method, which monitors the nitrogen content in the coolant. 13 N-activated products were used to quantitatively determine the leakage rate at the primary loop pressure boundary. However, due to... 13 Nitrogen has a short half-life (approximately 9.96 min), making it impossible to measure the leakage rate within the required time for lower leakage levels, resulting in a high lower limit of measurement.

[0004] Therefore, it is necessary to design a primary loop pressure boundary leakage radiation monitoring device and its monitoring method to solve the above-mentioned existing technical problems. Summary of the Invention

[0005] This invention relates to a primary loop pressure boundary leakage radiation monitoring device and method, which addresses the challenges of traditional primary loop pressure boundary leakage monitoring methods. 13 The N-monitoring method has a high measurement lower limit, which is a technical problem.

[0006] The technical solution of this invention:

[0007] A primary loop pressure boundary leakage radiation monitoring device includes: a sampling container, two LaBr3 detectors, a gamma detector digital coincidence measurement device, a radiation monitoring processing cabinet, several data cables, and several pipelines. Each side of the sampling container has a LaBr3 detector. Both LaBr3 detectors are connected to the gamma detector digital coincidence measurement device via data cables. The gamma detector digital coincidence measurement device is connected to the radiation monitoring processing cabinet via data cables.

[0008] The sampling container comprises a sampling tube, a sampling inlet and a sampling outlet; the sampling tube is connected with the sampling inlet, and the sampling container is further connected with a sampling flow control meter and a sampling instrument pipe respectively;

[0009] The sampling instrument pipe is arranged in a vertical direction, and the horizontal pipeline connected with the sampling instrument pipe and the sampling container maintains a 5-degree slope.

[0010] The LaBr3 detector is used for measuring gamma rays; the sampling container is provided with a sliding support, and two LaBr3 detectors are installed in a face-to-face manner on the sampling container through the sliding support, and the distance between the two LaBr3 detectors can be dynamically adjusted according to actual requirements.

[0011] The gamma-ray coincidence measurement device comprises an electronic readout module, a data preprocessing module, a coincidence event processing module, a communication module and a time synchronization module.

[0012] The front-end electronic readout module comprises analog circuits such as a preamplifier, a main amplifier and a shaping circuit, and realizes undistorted and high-multiple amplification of the detector signal;

[0013] The data preprocessing module is used for time measurement and energy measurement of data, so as to obtain the arrival time and energy information of a pulse;

[0014] The coincidence event processing module is used for screening and processing of true coincidence events and exclusion of false coincidence events.

[0015] The communication module adopts Modbus RS485 and Modbus TCP / IP protocols to meet the communication requirements of different occasions.

[0016] The time synchronization module is used for adopting a high-precision low-jitter crystal oscillator or a high-precision clock source chip to ensure that the clock signal meets the system requirements.

[0017] The sampling container is connected with an air suction pump.

[0018] The sampling container is further connected with a flushing circuit, and the sampling container is connected with the air suction pump and the flushing circuit through pipelines to form a sampling circuit.

[0019] A monitoring method of the loop pressure boundary leakage radiation monitoring device, comprising the following steps:

[0020] Step one, start the air suction pump, sample from the corresponding position in the containment, and the sampling gas medium is transmitted from the sampling tube to the sampling container through the sampling inlet; the sampling gas flow is dynamically controlled by the sampling flow meter, and the sampling gas flows out through the sampling outlet and is monitored by the LaBr3 detector;

[0021] Step two, when the LaBr3 detector is used for activity monitoring, in the case that the nuclear power is greater than 20%, the leakage radiation monitoring device of the primary circuit pressure boundary selects 18 F as a radioactive tracer, by measuring the radioactivity of 18 F, and then converting through the leakage conversion coefficient, and further calculating the leakage rate value; in the case that the nuclear power is less than 20% FP, the leakage radiation monitoring device of the primary circuit pressure boundary measures the total gamma count rate, and then converts through the conversion coefficient, and further calculates the leakage rate value;

[0022] Step three, the radioactivity of 18 F or the total gamma count rate calculated in step two is converted with the sampling circuit transmission coefficient to quantitatively obtain the leakage rate value.

[0023] The beneficial effects of the present application are as follows:

[0024] The present application utilizes another activation product 18 F in the primary coolant, utilizes the long half-life (about 109.74 min) and positron annihilation of 18 F, applies the gamma-gamma coincidence measurement technology to the primary circuit pressure boundary leakage monitoring, thereby realizing quantitative monitoring of the leakage rate of the primary circuit pressure boundary, which can not only improve the anti-interference ability of the system, but also reduce the lower limit of detection of the system, and to a certain extent, realize the miniaturization of the system.

[0025] The present application proposes a gamma-gamma coincidence measurement method, which realizes quantitative measurement and reduces the lower limit of system measurement and the volume of equipment. The method samples the places prone to leakage of the primary circuit pressure boundary, such as the welds, joints, flanges and other weak parts of the heat transfer side pipes of the steam generator, the pressure stabilizer, the pressure vessel, the main pump and its pipes and valves, etc., the sampling medium enters the sampling container through the sampling pipeline, and the gamma-gamma coincidence detector measures the radioactivity of 18 F aerosol, and finally calculates the leakage rate value of the leakage place by converting with the sampling circuit transmission coefficient.

[0026] The present application uses the activation product 18 F as a radioactive tracer, uses the gamma-gamma coincidence measurement device to monitor the gamma photons generated by 18 F, measures the radioactivity of 18 F, and finally accurately obtains the leakage monitoring of the primary circuit pressure boundary, realizing quantitative monitoring of the primary circuit pressure boundary. At the same time, by using the gamma-gamma coincidence measurement technology, the influence of the environmental background can be greatly reduced, the amount of lead shielding used can be reduced, and the miniaturization of the system can be realized to a certain extent. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Structure diagram of a loop pressure boundary leakage radiation monitoring device designed for the application

[0028] Figure 2 Operation flow chart of a loop pressure boundary leakage radiation monitoring device designed for the application

[0029] Wherein: 1-sampling container, 2-LaBr3 detector, 3-γ coincidence measurement device, 4-radiation monitoring processing cabinet DETAILED DESCRIPTION

[0030] The loop pressure boundary leakage radiation monitoring device and the monitoring method thereof will be described in detail below in combination with the drawings and examples.

[0031] A loop pressure boundary leakage radiation monitoring device, comprising: a sampling container 1, two LaBr3 detectors 2, a γ coincidence measurement device 3, a radiation monitoring processing cabinet 4, a plurality of data lines and a plurality of pipelines, one LaBr3 detector 2 is arranged on each side of the sampling container 1, the two LaBr3 detectors 2 are connected with the γ coincidence measurement device 3 through data lines, and the γ coincidence measurement device 3 is connected with the radiation monitoring processing cabinet 4 through data lines.

[0032] The sampling container comprises a sampling pipe, a sampling inlet and a sampling outlet; the sampling pipe is connected with the sampling inlet, and the sampling container is further connected with a sampling flow control meter and a sampling instrument pipe respectively;

[0033] The sampling instrument pipe is arranged in a vertical direction, and the horizontal pipeline connecting the sampling container and the sampling instrument pipe is kept at a slope of 5 degrees.

[0034] The LaBr3 detector 2 is used for measuring γ rays; a sliding bracket is arranged on the sampling container, and the two LaBr3 detectors 2 are installed on the sampling container in a face-to-face manner through the sliding bracket, and the distance between the two LaBr3 detectors 2 can be dynamically adjusted according to actual requirements.

[0035] The γ coincidence measurement device comprises an electronic readout module, a data preprocessing module, a coincidence event processing module, a communication module and a time synchronization module,

[0036] The front-end electronic readout module comprises an analog circuit such as a preamplifier, a main amplifier and a shaping circuit, and realizes undistorted and high-multiple amplification of the detector signal;

[0037] The data preprocessing module is used for time measurement and energy measurement of data, so as to obtain the arrival time and energy information of a pulse;

[0038] The matching case processing module is used to filter true matching cases and exclude false matching cases.

[0039] The communication module adopts Modbus RS485 and Modbus TCP / IP protocols to meet the communication needs of different occasions;

[0040] The time synchronization module is used to employ a high-precision, low-jitter crystal oscillator or a high-precision clock source chip to ensure that the clock signal meets the system requirements.

[0041] The sampling container 1 is connected to an air pump.

[0042] The sampling container 1 is also connected to a rinsing circuit. The sampling container 1 is connected to the air pump and the rinsing circuit through pipelines to form a sampling circuit.

[0043] A monitoring method for a primary loop pressure boundary leakage radiation monitoring device as described above includes the following steps:

[0044] Step 1: Start the vacuum pump and take a sample from the corresponding location inside the containment. The sample gas medium is transferred from the sampling tube through the sampling inlet to the sampling container. The sampling gas flow rate is dynamically controlled by the sampling flow meter. The sampling gas flows out through the sampling outlet and its activity is monitored by the LaBr3 detector 2.

[0045] Step 2: When the LaBr3 detector 2 performs activity monitoring, under conditions where the nuclear power is greater than 20%, the primary loop pressure boundary leakage radiation monitoring device is selected. 18 F is used as a radioactive tracer to measure... 18 The radioactivity of F is measured, and then converted using a leakage conversion factor to calculate the leakage rate. When the nuclear power is less than 20% FP, the primary loop pressure boundary leakage radiation monitoring device measures the total gamma count rate, and then converts it using a conversion factor to calculate the leakage rate.

[0046] Step 3: Calculate the results in Step 2. 18 The radioactivity or total gamma count rate of F is converted with the sampling loop transmission coefficient to obtain the leakage rate value quantitatively.

[0047] A monitoring method for a primary loop pressure boundary leakage radiation monitoring device as described above includes the following functions:

[0048] (1) 18 F-monitoring and total gamma monitoring functions: When nuclear power exceeds 20%, the primary loop pressure boundary leakage radiation monitoring device is selected. 18 F is used as a radioactive tracer to measure... 18The radioactivity of F is converted by a leakage conversion coefficient, and then the leakage rate value is calculated; in the case that the nuclear power is less than 20%FP, the leakage radiation monitoring device of the primary pressure boundary measures the total gamma count rate, and then converts by a conversion coefficient, and then calculates the leakage rate value.

[0049] (2) Data storage function: the leakage radiation monitoring device of the primary pressure boundary can automatically record or store monitoring data for a certain length of time, and can draw monitoring curves or monitoring tables, so as to facilitate users to call back data for data processing and analysis in time.

[0050] (3) Alarm function: the leakage radiation monitoring device of the primary pressure boundary has functions of fault alarm, primary alarm and secondary alarm, and the alarm threshold is continuously adjustable in the measurement range.

[0051] A monitoring method of the leakage radiation monitoring device of the primary pressure boundary as described above, and the technical indexes are as follows:

[0052] (1) Energy range:

[0053] 1) 18 F monitoring channel: 0.511 MeV;

[0054] 2) Total gamma monitoring channel: 0.2 MeV-2.2 MeV.

[0055] (2) Measurement range:

[0056] 1) 18 F monitoring channel: 1L / h-3000L / h;

[0057] 2) Total gamma monitoring channel: 1cps-10 5 cps.

[0058] (3) Performance indexes of the gamma spectrometer:

[0059] 1) Energy range: 0.2 MeV-2.2 MeV;

[0060] 2) Channel number: 2048 or more;

[0061] 3) Linearity: ±1 channel;

[0062] 4) Spectrum stability: ≤1%.

[0063] (4) Alarm: the alarm value is continuously adjustable in the measurement range, and the alarm threshold can be displayed on site.

[0064] In order to ensure the reliability of the system, two completely same air extraction pumps are connected in parallel, only one of which works in a certain time, and the other one is standby; if the air extraction system fails, the standby air extraction pump is started immediately.

[0065] The present application adopts two identical LaBr3 detectors which are placed face to face to measure the radioactivity of F in the sampling container, and then the leakage rate is obtained by conversion with the transmission coefficient. 18 The radioactivity of F is measured, and then the leakage rate is obtained by conversion with the transmission coefficient. 18 The present application adopts two identical LaBr3 detectors which are placed face to face to measure the radioactivity of F in the sampling container, and then the leakage rate is obtained by conversion with the transmission coefficient.

[0066] The above detailed description is only an embodiment of the present application, and the present application is not limited to the above examples. Various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. A primary loop pressure boundary leakage radiation monitoring device, characterized in that, include: The sampling container (1), two LaBr3 detectors (2), a γ-γ digital coincidence measurement device (3), a radiation monitoring and processing cabinet (4), several data cables and several pipelines are provided. There is a LaBr3 detector (2) on each side of the sampling container (1). Both LaBr3 detectors (2) are connected to the γ-γ digital coincidence measurement device (3) through data cables. The γ-γ digital coincidence measurement device (3) is connected to the radiation monitoring and processing cabinet (4) through data cables. The LaBr3 detector (2) is used to measure gamma rays; the sampling container is provided with a sliding bracket, and the two LaBr3 detectors (2) are installed face to face on the sampling container through the sliding bracket, and the distance between the two LaBr3 detectors (2) can be dynamically adjusted according to actual needs; The γ-γ digital coincidence measurement device includes an electronics readout module, a data preprocessing module, a coincidence event processing module, a communication module, and a time synchronization module; The electronic readout module includes analog circuits such as a preamplifier, a main amplifier, and a shaping circuit, which enables distortion-free and high-magnification amplification of the detector signal; The data preprocessing module is used to perform time and energy measurements on the data to obtain the arrival time and energy information of the pulse. The matching case processing module is used to filter true matching cases and exclude false matching cases. The communication module adopts Modbus RS485 and Modbus TCP / IP protocols to meet the communication needs of different occasions; The time synchronization module is used to employ a high-precision, low-jitter crystal oscillator or a high-precision clock source chip to ensure that the clock signal meets the system requirements.

2. The primary loop pressure boundary leakage radiation monitoring device according to claim 1, characterized in that: The sampling container includes a sampling tube, a sampling inlet, and a sampling outlet; the sampling tube is connected to the sampling inlet, and the sampling container is also connected to a sampling flow controller and a sampling instrument tube; the sampling instrument tube is vertically oriented, and the horizontal pipeline connecting the sampling container and the sampling instrument tube maintains a 5‰ slope.

3. The primary loop pressure boundary leakage radiation monitoring device according to claim 2, characterized in that: The sampling container (1) is connected to an air pump.

4. The primary loop pressure boundary leakage radiation monitoring device according to claim 3, characterized in that: The sampling container (1) is also connected to a flushing circuit. The sampling container (1) is connected to the air pump and the flushing circuit through pipelines to form a sampling circuit.

5. A monitoring method for a primary loop pressure boundary leakage radiation monitoring device according to any one of claims 1 to 4, characterized in that... Includes the following steps: Step 1: Start the vacuum pump and take a sample from the corresponding position inside the containment. The sample gas medium is transferred from the sampling tube through the sampling inlet to the sampling container. The sampling gas flow rate is dynamically controlled by the sampling flow meter. The sampling gas flows out through the sampling outlet and the activity is monitored by the LaBr3 detector (2). Step two, when the LaBr3 detector (2) is used for activity monitoring, the leakage radiation monitoring device for primary circuit pressure boundary is selected 18 F as a radioactive tracer by measuring the radioactivity of 18 F, and then converting through the leakage conversion coefficient to calculate the leakage rate value; in the case of less than 20% FP nuclear power, the leakage radiation monitoring device for the primary circuit pressure boundary measures the total gamma count rate, and then converts through the conversion coefficient to calculate the leakage rate value; Step 3: Calculate the results in Step 2. 18 The leakage rate value is quantitatively obtained by converting the radioactivity or total gamma count rate of F with the sampling loop transmission coefficient.

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