Fuel rod slip monitoring system based on tellurium-zinc-cadmium detector assembly array

Abstract

The invention discloses a fuel rod sliding monitoring system based on a cadmium zinc telluride detector assembly array, and belongs to the technical field of nuclear radiation fuel rod monitoring. Comprising a cadmium zinc telluride detector assembly array; the tellurium-zinc-cadmium detector assembly array comprises a plurality of groups of tellurium-zinc-cadmium detector assemblies, each group of tellurium-zinc-cadmium detector assemblies independently works and is in parallel communication with the host module through an independent communication interface, the host module is used for processing data returned by the tellurium-zinc-cadmium detector assemblies in parallel, and the tellurium-zinc-cadmium detector assemblies are arranged around the fuel rod in a surrounding manner; the host module is used for setting assembly parameters of the tellurium-zinc-cadmium detector assembly, monitoring data returned by the tellurium-zinc-cadmium detector assembly in real time, and starting the alarm control device and triggering emergency measures if abnormity is found. A plurality of groups of independent tellurium-zinc-cadmium semiconductor detector assemblies are used to form an annular array, so that the detection area of the system is increased, and the detection sensitivity of the fuel rod is improved.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear radiation fuel rod monitoring, and in particular to a fuel rod sliding monitoring system based on a cadmium zinc telluride detector assembly array. Background Art

[0002] During the assembly process of fuel rods at a nuclear site, fuel rods may slip. If a fuel rod slips, emergency measures need to be taken quickly to respond to the slip.

[0003] The on-site environment is covered by aerosol dust and pipelines. The traditional infrared or laser monitoring method is easily affected by the environment, resulting in equipment failure. The fuel rods produce low-energy gamma rays of no less than 20KeV, and the sliding process is in the millisecond level. The gamma radiation dose rate generated by the fuel rods ranges from 0.1uSV / h to 10SV / h. There are many types of gamma radiation measurement equipment on the market, but none of them has the characteristics of fast response, low energy measurement, wide measurement range, high sensitivity and small size at the same time. Summary of the invention

[0004] The object of the present invention is to overcome the deficiencies of the prior art and provide a fuel rod sliding monitoring system based on a cadmium zinc telluride detector assembly array.

[0005] The objective of the present invention is achieved through the following technical solutions: a fuel rod sliding monitoring system based on a CdZnTe detector assembly array, comprising a CdZnTe detector assembly array, wherein the CdZnTe detector assembly array is connected to a host module, and the host module is connected to a PC server and an alarm control device; the CdZnTe detector assembly array comprises a plurality of groups of CdZnTe detector assemblies, each group of CdZnTe detector assemblies works independently, and communicates in parallel with the host module through an independent communication interface, and the host module processes data sent back by the CdZnTe detector assemblies in parallel, and the CdZnTe detector assemblies are placed around the fuel rods; the host module is used to set the assembly parameters of the CdZnTe detector assembly, and monitor the data sent back by the CdZnTe detector assembly in real time, and if an abnormality is found, the alarm control device is started to trigger emergency measures.

[0006] Preferably, the CdZnTe detector assembly comprises a detector preamplifier circuit, the detector preamplifier circuit is connected to a power module and a microprocessor module, and the microprocessor module is connected to the detector preamplifier circuit, the power module and the host module.

[0007] Preferably, the component parameters include a high voltage threshold and a radiation threshold.

[0008] Preferably, the detector preamplifier circuit includes a CdZnTe detector, an IV conversion circuit, a signal amplification circuit, an ADC circuit and an adjustable high-voltage module; the input end of the IV conversion circuit is connected to the output end of the CdZnTe detector, the output end of the IV conversion circuit is connected to the input end of the signal amplification circuit, the output end of the signal amplification circuit is connected to the input end of the ADC circuit, and the output end of the ADC circuit is connected to a microprocessor module; the input end of the adjustable high-voltage module is connected to the microprocessor module, and the output end of the adjustable high-voltage module is connected to the input end of the CdZnTe detector; when the gamma ray hits the CdZnTe detector, the charge generated is output to the IV conversion circuit, the IV conversion circuit converts the current signal into a first-level voltage signal and outputs it to the signal amplification circuit, the signal amplification circuit amplifies the first-level voltage signal into a second-level voltage signal and outputs it to the ADC circuit, the ADC circuit converts the second-level voltage signal into a digital signal and outputs it to the microprocessor module; the adjustable high-voltage module is used to generate the bias voltage required by the CdZnTe detector.

[0009] Preferably, the microprocessor module includes an FPGA module and an SDRAM memory, and the FPGA module is connected to the SDRAM memory, the detector preamplifier circuit, the power supply module and the host module; the FPGA module is used to perform amplitude discrimination and dose rate conversion on the signal input by the detector preamplifier circuit and set component parameters according to the control signal transmitted by the host module. Preferably, the FPGA module sets a main communication protocol and a backup communication protocol.

[0010] Preferably, the main communication protocol is the CAN communication protocol, and the backup communication protocol is the RS-485 protocol.

[0011] Preferably, the CdZnTe detector assembly array has 8 groups of CdZnTe detector assemblies.

[0012] Preferably, each group of CdZnTe detector components is connected to the host module via an independent cable.

[0013] The beneficial effects of the present invention are: 1) The use of multiple independent CdZnTe semiconductor detector components to form a ring array increases the system detection area and the detection sensitivity of the fuel rods; it can measure low-energy gamma rays of no less than 20KeV; the CdZnTe detector has a fast response time and a wide dose rate measurement range; the detector components are independent of each other, and the increase in system area does not increase the leakage current and the system noise.

[0014] 2) Each component is connected to the host via an independent cable. The host has 8 independent communication interfaces and FPGA for parallel communication, which solves the problem of slow system response time.

[0015] 3) Use miniature cadmium zinc telluride detectors in a ring layout around the fuel rods, which are smaller in size than other types of detectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The block diagram of the fuel rod fall monitoring system based on the cadmium zinc telluride detector assembly array is shown; Figure 2 This is the principle block diagram of the cadmium zinc telluride detector assembly; Figure 3 Installation layout diagram for the CdZnTe detector assembly array; Figure 4 This is a rendering of the fuel rod fall monitoring system based on the cadmium zinc telluride detector assembly array. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0018] The present invention requires a rapid response to the instantaneous slipping event of the fuel rod in an aerosol dust environment, so the detector must have the following characteristics at the same time. Short response time; ability to measure lower energy rays; wide dose rate detection range; high sensitivity; small size. At present, there are four main types of detectors for measuring gamma rays, ionization chamber detectors, Geiger Mueller counter tube detectors (hereinafter referred to as GM detectors), scintillator detectors and semiconductor detectors. They each have different performances in response time, energy measurement lower limit, dose rate measurement range, sensitivity and volume. Described below are the characteristics of various detectors in the application scenarios of the present invention.

[0019] The response time of ionization chamber detectors is usually long, which is determined by their working principle. When nuclear radiation rays pass through the ionization chamber, gas molecules are ionized to generate electrons and positive ions. These charges move under the action of the electric field and generate current. The charge collection process in the ionization chamber takes a certain amount of time, so the response time is longer than that of other detectors. The shell of the ionization chamber detector is stainless steel, which has a certain degree of blocking of low-energy gamma rays and is not suitable for the measurement of low-energy rays. The ionization chamber detector has a wide dose rate measurement range, but the method of increasing the measurement range by switching the gain resistor in the signal circuit will increase the system response time. Studies on the energy absorption of X or gamma rays by air show that under the conditions of temperature of +20℃ and atmospheric pressure of 101.3KP, 1cm3 of dry air absorbs a dose rate of 10uSV / h, and after all the positive and negative ions generated are collected, a current of 9.8X10-17A can be obtained. At present, the measurement circuit of the domestic ionization chamber can measure the current lower limit of 2X10-15A under ideal conditions. To complete the measurement of dose rate of 0.1uSV / h, an ionization chamber volume of at least 3000 cm3 is required to meet this requirement. Therefore, the ionization chamber detector is relatively large.

[0020] The basic structure of the GM detector includes a sealed tube filled with gas and a conductive central electrode in the center of the tube. When radiation particles enter the tube and interact with gas atoms, ionization occurs, forming current pulses between the central electrode and the tube wall, which are converted into readable signals by electronic circuits. Due to the physical characteristics of the GM detector, there is a measurement dead time, during which the detector is inactive, so the response time for transient response is longer. The GM detector requires energy response compensation for the detector, and the measurement effect of low-energy rays is not good. The measurement range of the GM detector is low and is not suitable for high-dose measurement. The GM detector has high sensitivity. The GM detector is small in size.

[0021] The working principle of scintillator detectors is that when radiation particles interact with scintillator materials, photons are stimulated, which are then detected by photomultiplier tubes. Scintillator detectors have a short response time. Scintillator detectors can measure low-energy gamma rays. Due to the physical characteristics of scintillator detectors, the signal is easily saturated. Therefore, this detector is mainly used for low-dose nuclear radiation measurement and is not suitable for wide dose rate measurement scenarios. Scintillator detectors have high sensitivity. Scintillator detectors are composed of scintillators and photomultiplier tubes, require high voltage to work, and the system volume is large.

[0022] Characteristics of CdZnTe detectors: Semiconductor detectors for measuring gamma rays mainly include CdZnTe detectors, high-purity germanium detectors, and silicon photodiode detectors. CdZnTe detectors are a type of semiconductor detector. High-purity germanium detectors need to be measured in a low-temperature environment and are not suitable for the application environment of the present invention. The physical characteristics of silicon photodiode detectors cannot accurately measure low-energy gamma rays. CdZnTe detectors are compound semiconductor detectors based on ionizing radiation and have very fast response times, generally at the nanosecond level or even faster. This is because CdZnTe detectors work based on the photoelectric effect. When gamma rays hit CdZnTe detectors, electron-hole pairs can be quickly generated and quickly collected by the electric field to generate current signals. This fast response characteristic makes CdZnTe detectors very suitable for application scenarios that require high-speed response. CdZnTe detectors have high material density, so they can effectively detect low-energy gamma rays exceeding 20keV, while traditional silicon-based detectors cannot detect these gamma ray energies. By adopting the CdZnTe detector component array, the sensitivity of the CdZnTe detector can be significantly improved, and the measurement range of 0.1uSV / h to 10SV / h of the present invention can be met. The CdZnTe detector area used in the present invention is 5mmX5mm, and the overall volume of the system is small.

[0023] The performance comparison of ionization chamber detectors, GM tube detectors, scintillator detectors and CdZnTe detectors is shown in Table 1. It is necessary to respond to the changes in low-energy gamma dose rate caused by instantaneous sliding events in an aerosol dust environment, and the detector range should be able to cover the working dose rate range. Only a gamma measurement system based on a CdZnTe detector component array can meet this technical requirement.

[0024] Table 1 Detector performance comparison See also Figure 1-Figure 4 The present invention provides a technical solution: a fuel rod sliding monitoring system based on a CdZnTe detector assembly array, comprising a CdZnTe detector assembly array, wherein the CdZnTe detector assembly array is connected to a host module, and the host module is connected to a PC server and an alarm control device; the CdZnTe detector assembly array comprises a plurality of groups of CdZnTe detector assemblies, each group of CdZnTe detector assemblies works independently, and communicates in parallel with the host module through an independent communication interface, and the host module processes data sent back by the CdZnTe detector assemblies in parallel, and the CdZnTe detector assemblies are placed around the fuel rods; the host module is used to set assembly parameters of the CdZnTe detector assembly, and monitor the data sent back by the CdZnTe detector assembly in real time, and if an abnormality is found, the alarm control device is started to trigger emergency measures.

[0025] In this embodiment, the fuel rod sliding monitoring system based on the CdZnTe detector assembly array is used in a test environment with aerosol dust. Figure 1 As shown in the figure, the CdZnTe detector assembly array is composed of 8 groups of CdZnTe detector assemblies. The CdZnTe detector assembly array is connected to the host through a cable. The host completes the message sending and receiving through the communication module and the communication module of the CdZnTe detector assembly. The host can complete the functions of high voltage setting, radiation threshold setting, data reading, etc. of the CdZnTe assembly. The host uploads the real-time data to the remote PC server. The host monitors the dose rate data sent back by the CdZnTe detector assembly array in real time. Once the dose rate is abnormal, the alarm and control device is activated to trigger the corresponding emergency measures. In order to respond quickly to the instantaneous slipping of the fuel rod, in addition to the CdZnTe detector assembly being able to detect the radiation signal in time, the subsequent electronic circuit must also ensure the response to the event. The response speed of the microprocessor affects the response time of the entire system. At present, the conventional embedded single-chip microcomputers on the market are more inclined to software. They are designed and developed on the chip of the existing solidified circuit. They are sequentially executed internally. One execution is completed before the next one is executed. The program statement also needs to wait for the single-chip microcomputer cycle to execute, so the speed is relatively slow and the response time is relatively long.

[0026] The present invention uses FPGA to process data. FPGA is based on hardware circuits, which are parallel inside. All circuit logics work under the same clock trigger. The operating speed directly depends on the crystal oscillator speed. The system is stable, particularly suitable for high-speed interface circuits, and has a fast response time. The present invention uses FPGA to process the parallel signals input by the CdZnTe detector. Eight groups of CdZnTe detector components work independently. Each component is connected to the host through an independent cable. The host has eight independent communication interfaces and communicates with the FPGA in parallel, which solves the problem of slow system response time. In nuclear-related sites, fuel rods are arranged in a certain number and supported at multiple points by positioning grids. Eight groups of CdZnTe detector components are placed around the fuel rods in a surrounding manner, and each group of CdZnTe detector components is connected to the corresponding plug of the host through an independent cable. The layout is as follows: Figure 3 shown.

[0027] The PC server and the control alarm device are connected to the host computer via cables.

[0028] In some embodiments, the CdZnTe detector assembly includes a detector preamplifier circuit, the detector preamplifier circuit is connected to a power module and a microprocessor module, and the microprocessor module is connected to the detector preamplifier circuit, the power module and the host module.

[0029] In this embodiment, the CdZnTe detector assembly is the core of the entire system. Since the detector area is proportional to the leakage current, the larger the detector leakage current, the greater the noise of the detector signal processing circuit. After the gamma rays are incident on the surface of the CdZnTe detector and interact with each other, a group of electron-hole pairs (i.e., carriers) are generated, and the amount of charge generated is proportional to the energy of the gamma rays. The lower the energy of the gamma rays, the smaller the charge, and the lower the signal amplitude generated by the sensitive charge amplifier circuit. In order to ensure that low-energy gamma rays can be measured, the detector leakage current is required to be as low as possible. If the area of ​​the detector needs to be increased to improve the sensitivity, the increase in the detector area will cause the leakage current to increase, thereby submerging the effective signal. The present invention adopts a circular arrangement of 8 groups of CdZnTe detector assemblies. Each detector uses an independent signal processing circuit, and finally sends the 8-way signal circuit to the microprocessor for parallel processing. The 8 groups of CdZnTe detector assemblies work simultaneously, and the detection area is increased by 8 times without increasing the leakage current. The block diagram of the CdZnTe detector assembly is shown as follows. Figure 2 shown.

[0030] In some embodiments, the component parameters include a high voltage threshold and a radiation threshold.

[0031] In some embodiments, the detector preamplifier circuit includes a CdZnTe detector, an IV conversion circuit, a signal amplification circuit, an ADC circuit and an adjustable high-voltage module; the input end of the IV conversion circuit is connected to the output end of the CdZnTe detector, the output end of the IV conversion circuit is connected to the input end of the signal amplification circuit, the output end of the signal amplification circuit is connected to the input end of the ADC circuit, and the output end of the ADC circuit is connected to a microprocessor module; the input end of the adjustable high-voltage module is connected to the microprocessor module, and the output end of the adjustable high-voltage module is connected to the input end of the CdZnTe detector; when the gamma ray hits the CdZnTe detector, the charge generated is output to the IV conversion circuit, the IV conversion circuit converts the current signal into a first-level voltage signal and outputs it to the signal amplification circuit, the signal amplification circuit amplifies the first-level voltage signal into a second-level voltage signal and outputs it to the ADC circuit, the ADC circuit converts the second-level voltage signal into a digital signal and outputs it to the microprocessor module; the adjustable high-voltage module is used to generate the bias voltage required by the CdZnTe detector.

[0032] In this embodiment, the detector pre-discharge circuit is composed of IV conversion, signal amplification, ADC and adjustable high-voltage module. The charge generated by the gamma ray hitting the CdZnTe detector is output to the first-stage IV conversion. IV conversion converts the weak current signal to be measured into a voltage signal. The second-stage signal amplification further amplifies the first-stage voltage signal and outputs it to the ADC, which converts the analog voltage signal into a digital signal. The adjustable high-voltage module generates the bias voltage required by the CdZnTe detector. The core of the microprocessor module is FPGA, which performs amplitude discrimination and dose rate conversion on the detector signal input to the preamplifier circuit. The converted dose rate data is output to the host through the communication module. The power module is used to convert the host input voltage into the power required by the detector preamplifier circuit and the microprocessor module.

[0033] In some embodiments, the microprocessor module includes an FPGA module and an SDRAM memory, and the FPGA module is connected to the SDRAM memory, the detector preamplifier circuit, the power module and the host module; the FPGA module is used to perform amplitude discrimination and dose rate conversion on the signal input by the detector preamplifier circuit and set component parameters according to the control signal transmitted by the host module. In some embodiments, the FPGA module sets a main communication protocol and a backup communication protocol.

[0034] In some embodiments, the main communication protocol is the CAN communication protocol, and the backup communication protocol is the RS-485 protocol.

[0035] In some embodiments, the CdZnTe detector assembly array has 8 groups of CdZnTe detector assemblies.

[0036] In some embodiments, each set of CdZnTe detector assemblies is connected to the host module via an independent cable.

[0037] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A fuel rod sliding monitoring system based on a cadmium zinc telluride detector assembly array, characterized in that: The invention comprises a CdZnTe detector assembly array, wherein the CdZnTe detector assembly array is connected to a host module, and the host module is connected to a PC server and an alarm control device; the CdZnTe detector assembly array comprises a plurality of groups of CdZnTe detector assemblies, each group of CdZnTe detector assemblies works independently, and communicates in parallel with the host module through an independent communication interface, and the host module processes data sent back by the CdZnTe detector assemblies in parallel, and the CdZnTe detector assemblies are placed around the fuel rods; the host module is used to set the assembly parameters of the CdZnTe detector assemblies, and monitor the data sent back by the CdZnTe detector assemblies in real time, and if an abnormality is found, the alarm control device is started to trigger emergency measures.

2. The fuel rod sliding monitoring system based on the CdZnTe detector assembly array according to claim 1 is characterized in that: The cadmium zinc telluride detector assembly comprises a detector preamplifier circuit, the detector preamplifier circuit is connected to a power module and a microprocessor module, and the microprocessor module is connected to the detector preamplifier circuit, the power module and the host module.

3. The fuel rod sliding monitoring system based on the CdZnTe detector assembly array according to claim 1, characterized in that: The component parameters include a high voltage threshold and a radiation threshold.

4. The fuel rod sliding monitoring system based on the CdZnTe detector assembly array according to claim 2 is characterized in that: The detector preamplifier circuit comprises a CdZnTe detector, an IV conversion circuit, a signal amplification circuit, an ADC circuit and an adjustable high-voltage module; the input end of the IV conversion circuit is connected to the output end of the CdZnTe detector, the output end of the IV conversion circuit is connected to the input end of the signal amplification circuit, the output end of the signal amplification circuit is connected to the input end of the ADC circuit, and the output end of the ADC circuit is connected to a microprocessor module; the input end of the adjustable high-voltage module is connected to the microprocessor module, and the output end of the adjustable high-voltage module is connected to the input end of the CdZnTe detector; when the gamma ray hits the CdZnTe detector, the charge generated is output to the IV conversion circuit, the IV conversion circuit converts the current signal into a first-level voltage signal and outputs it to the signal amplification circuit, the signal amplification circuit amplifies the first-level voltage signal into a second-level voltage signal and outputs it to the ADC circuit, the ADC circuit converts the second-level voltage signal into a digital signal and outputs it to the microprocessor module; the adjustable high-voltage module is used to generate the bias voltage required by the CdZnTe detector.

5. The fuel rod sliding monitoring system based on the CdZnTe detector assembly array according to claim 2, characterized in that: The microprocessor module includes an FPGA module and an SDRAM memory, wherein the FPGA module is connected to the SDRAM memory, the detector preamplifier circuit, the power module and the host module; the FPGA module is used to perform amplitude discrimination and dose rate conversion on the signal input by the detector preamplifier circuit and to set component parameters according to the control signal transmitted by the host module.

6. The fuel rod sliding monitoring system based on the CdZnTe detector assembly array according to claim 5 is characterized in that: The FPGA module is configured with a main communication protocol and a backup communication protocol.

7. The fuel rod sliding monitoring system based on the CdZnTe detector assembly array according to claim 1, characterized in that: The main communication protocol is the CAN communication protocol, and the backup communication protocol is the RS-485 protocol.

8. The fuel rod sliding monitoring system based on the CdZnTe detector assembly array according to any one of claims 1 to 7, characterized in that: The CdZnTe detector assembly array comprises 8 groups of CdZnTe detector assemblies.

9. The fuel rod sliding monitoring system based on the CdZnTe detector assembly array according to any one of claims 1 to 7, characterized in that: Each set of CdZnTe detector components is connected to the host module via an independent cable.

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