A gamma ray monitoring system and method based on SiC semiconductor

Abstract

The application discloses a kind of gamma ray monitoring system and method based on SiC semiconductor, monitoring system includes gamma ray detection device and wireless transmission module, gamma ray detection device is configured as the pulse signal output converted from gamma ray signal, wireless transmission module includes laser emission end and laser receiving end, laser emission end includes light emitting diode, laser drive circuit and laser light source collimating unit, laser drive circuit is configured as the voltage drive signal of light emitting diode according to the pulse signal output of gamma ray detection device, light emitting diode adjusts the laser signal output in real time according to voltage drive signal, and the laser signal output is aimed at laser receiving end by laser light source collimating unit, laser receiving end is output after photoelectric conversion processing is carried out to received laser signal.The monitoring system and method provided by the application can realize high-energy resolution, radiation resistance high temperature resistance, wireless real-time continuous gamma ray monitoring.

Description

Technical Field

[0001] This invention relates to the field of reactor radiation detection technology, and in particular to a gamma-ray monitoring system and method based on SiC semiconductors. Background Technology

[0002] In recent years, with the rapid development of nuclear technology applications, the demand for radiation detectors that can operate stably for extended periods in extremely complex environments such as space environments and nuclear reactor cores under intense radiation and complex temperatures has become increasingly urgent. Semiconductor detectors possess unparalleled advantages over other detectors, including high energy resolution, high detection efficiency, small size, and fast response time. Their principle involves using semiconductor materials as the detection medium. Incident rays ionize within the semiconductor medium, forming electron-hole pairs. An external electric field causes these electron-hole pairs to drift, generating an output signal in the output circuit to complete the ray detection. However, traditional silicon and germanium semiconductor detectors can only be stored and operated at room temperature or low temperatures, and cannot function in harsh environments such as high temperatures and strong radiation fields.

[0003] SiC semiconductor material is a novel semiconductor material developed in the 21st century. Due to its unique characteristics such as a large bandgap, high critical breakdown field strength, strong thermal stability, high electron mobility, high thermal conductivity, and excellent radiation resistance, it is a suitable replacement for traditional radiation detectors based on silicon, germanium, cadmium telluride, and cadmium zinc telluride. It is also considered a wide-bandgap semiconductor material with great potential for fabricating high-temperature, high-frequency, high-power, and radiation-resistant devices. Since 1998, when Frank H. Ruddy's team in the United States developed a nuclear radiation detector using SiC crystals grown by chemical vapor deposition, SiC material growth and device fabrication processes have gradually matured, achieving good detection results in alpha particles, X-rays, gamma rays, and neutrons. However, in the complex environments of nuclear power plants, existing wireless transmission methods are often easily distorted by radiation interference. How to stably and accurately transmit the detection results to safe areas remains a problem that urgently needs to be solved.

[0004] The above background information is provided only to assist in understanding the inventive concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application, nor does it necessarily provide technical teaching. In the absence of clear evidence that the above information was disclosed before the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a γ-ray monitoring system and method based on SiC semiconductors, the specific technical solution of which is as follows:

[0006] On one hand, a gamma-ray monitoring system and method based on SiC semiconductors is provided, including a gamma-ray detection device and a wireless transmission module. The gamma-ray detection device detects gamma rays around a nuclear power plant based on SiC semiconductors and is configured to convert gamma-ray signals into pulse signals for output. The wireless transmission module includes a laser transmitter and a laser receiver. The laser transmitter is located in a radiation hazard zone, and the laser receiver is located in a radiation safe zone. The laser transmitter includes a light-emitting diode (LED), a laser driving circuit, and a laser source collimation unit. The laser driving circuit is configured to control the voltage driving signal of the LED according to the pulse signal output by the gamma-ray detection device. The LED adjusts the output laser signal in real time according to the voltage driving signal and aligns the output laser signal to the laser receiver through the laser source collimation unit. The laser receiver performs photoelectric conversion processing on the received laser signal and outputs it.

[0007] Furthermore, the light-emitting diode is a GaN light-emitting diode, and the laser driving circuit superimposes the pulse signal to be transmitted with a DC bias signal, and changes the light intensity of the laser emitted by the light-emitting diode in real time through a potentiometer.

[0008] Furthermore, the receiving module includes a laser beam focusing unit, a photodiode, an amplifier circuit, and a data reading circuit. The laser beam focusing unit is used to focus the intensity of the laser signal so that it completely covers the surface of the photodiode to complete the signal reception. The photodiode is used for photoelectric conversion to output an electrical signal. The amplifier circuit amplifies the electrical signal and inputs it into the data reading circuit for reading.

[0009] Furthermore, multiple gamma-ray detection devices are set at different detection points around the nuclear reactor. The multiple gamma-ray detection devices periodically output pulse signals to the laser receiver through the same laser emitting end in a time-division manner, and the multiple gamma-ray detection devices do not interfere with each other.

[0010] Furthermore, the laser transmitter and the laser receiver can communicate bidirectionally, and staff can remotely adjust the preset parameters of the gamma-ray detection device and the laser transmitter through the wireless transmission module.

[0011] Furthermore, the gamma-ray detection device includes a SiC detector, a preamplifier, and a filtering and digital shaping circuit connected in sequence.

[0012] The design of the SiC detector includes the following steps:

[0013] The process involves determining the thickness and dimensions of the SiC semiconductor epitaxial layer; determining the net doping rate of the SiC semiconductor epitaxial layer; determining the electrode material and contact method of the SiC semiconductor epitaxial layer; determining the SiC detector packaging method and PCB circuit design; determining the range of gamma-ray energies that the SiC detector can measure, and thus determining the pulse amplitude of the voltage signal it generates.

[0014] The filtering and digital shaping circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, a second capacitor, and an operational amplifier. The first resistor, the second resistor, and the positive input terminal of the operational amplifier are electrically connected in sequence. One end of the third resistor is grounded, and the other end is connected to the negative input terminal of the operational amplifier. One end of the fourth resistor is connected to the negative input terminal of the operational amplifier, and the other end is connected to the output terminal of the operational amplifier. One end of the first capacitor is grounded, and the other end is connected to the positive input terminal of the operational amplifier. One end of the second capacitor is connected between the first resistor and the second resistor, and the other end is connected to the output terminal of the operational amplifier.

[0015] On the other hand, a γ-ray monitoring method based on SiC semiconductor is provided. Based on the aforementioned γ-ray monitoring system, the monitoring method includes the following steps:

[0016] The radiation field is measured using a SiC detector, and the generated signal is processed into a pulse signal for input to the laser emitter.

[0017] In the laser emitting end, the laser driving circuit drives the light-emitting diode to emit laser signals of different intensities according to the pulse signal, and sends them to the laser receiving end through the laser source collimation unit;

[0018] At the laser receiver, the laser signal is converted into an electrical signal after being focused and detected by photoelectric detection.

[0019] The electrical signal is amplified, filtered, and digitally shaped in sequence before being sent to an industrial control computer for processing and analysis, so as to achieve real-time output to the human-machine interface for display.

[0020] Furthermore, multiple gamma-ray detection devices are set up in the same radiation field. These multiple gamma-ray detection devices periodically output pulse signals to the same laser receiving end through the same laser emitting end in a time-division manner. Based on the different distances between the gamma-ray detection devices and the nuclear power plant radiation source, a theoretical ranking of the gamma-ray irradiation intensity detected by the different gamma-ray detection devices is obtained. If the actual ranking of the detection results of multiple gamma-ray detection devices does not conform to the theoretical ranking for a specified period of time, an alarm is issued and relevant personnel are notified to verify the situation.

[0021] Compared with the prior art, the present invention has the following advantages: compared with radio frequency communication, laser communication is less susceptible to the effects of radiation and electromagnetic interference, and can realize high energy resolution, radiation resistance and high temperature resistance, and wireless real-time continuous gamma-ray monitoring. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the circuit topology of the gamma-ray detection device in the SiC semiconductor-based gamma-ray monitoring system provided in this embodiment of the invention.

[0023] Figure 2 This is a circuit diagram of filtering and digital shaping in a SiC semiconductor-based gamma-ray monitoring system provided in an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the wireless transmission module's workflow in a SiC semiconductor-based gamma-ray monitoring system provided in an embodiment of the present invention. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0027] In one embodiment of the present invention, a SiC semiconductor-based gamma-ray monitoring system is provided, including a gamma-ray detection device and a wireless transmission module. The gamma-ray detection device, based on SiC semiconductor, detects gamma rays around a nuclear power plant and is configured to convert gamma-ray signals into pulse signals for output. The wireless transmission module includes a laser transmitter and a laser receiver. The laser transmitter is located in a radiation hazard zone, and the laser receiver is located in a radiation safe zone. The laser transmitter includes a light-emitting diode (LED), a laser driving circuit, and a laser source collimation unit. The laser driving circuit is configured to control a voltage driving signal of the LED according to the pulse signal output by the gamma-ray detection device. The LED adjusts its output laser signal in real time according to the voltage driving signal, and the laser source collimation unit aligns the output laser signal to the laser receiver. The laser receiver performs photoelectric conversion processing on the received laser signal and then outputs it.

[0028] Among them, see Figure 1 The gamma-ray detection device includes a SiC detector, a preamplifier, and a filtering and digital shaping circuit connected in sequence. The SiC detector interacts with gamma rays in the space environment to generate electron-hole pairs and form a voltage signal. The design of the SiC detector includes the following steps:

[0029] The thickness and dimensions of the SiC semiconductor epitaxial layer are determined, followed by the net doping rate of the SiC semiconductor epitaxial layer, then the electrode material and contact method of the SiC semiconductor epitaxial layer, and finally the packaging method and PCB circuit design of the SiC detector. The range of gamma-ray energy that the SiC detector can measure is determined, and then the pulse amplitude of the voltage signal it generates is determined.

[0030] The preamplifier is used to amplify the weak voltage signal output by the SiC detector. The design of the preamplifier includes the following steps: determining the preamplifier amplification factor based on the pulse amplitude of the voltage signal; and determining the preamplifier circuit structure and electronic device parameters based on the preamplifier amplification factor.

[0031] Filtering and digital shaping circuits are used to remove noise from signals and improve the pulse waveform of signals. Digital shaping circuits can convert exponential signals into digital pulse signals. The design of filtering and digital shaping circuits includes the following steps: determining the spectral characteristics of the signal and noise; determining the optimal filtering parameters based on the spectral characteristics of the signal and noise; determining the pulse shape of the filtered voltage signal based on the optimal filtering parameters; and determining the structure of the digital shaping circuit and the parameters of the electronic components based on the pulse shape of the filtered voltage signal.

[0032] Specifically, see Figure 2The filtering and digital shaping circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, a second capacitor C2, and an operational amplifier. The first resistor, the second resistor, and the positive input terminal of the operational amplifier are connected in sequence. One end of the third resistor is grounded, and the other end is connected to the negative input terminal of the operational amplifier. One end of the fourth resistor is connected to the negative input terminal of the operational amplifier, and the other end is connected to the output terminal of the operational amplifier. One end of the first capacitor is grounded, and the other end is connected to the positive input terminal of the operational amplifier. One end of the second capacitor is connected between the first resistor and the second resistor, and the other end is connected to the output terminal of the operational amplifier.

[0033] The design of the wireless transmission module includes the following steps: determining the input signal frequency, transmission distance, and operating environment, and then determining the transmission method. The wireless transmission module employs radiation-resistant real-time optical communication technology based on gallium nitride light-emitting diodes (GaN). See [link to relevant documentation]. Figure 3 It includes a laser transmitter and a laser receiver.

[0034] The laser emitting end includes a light-emitting diode (LED), a laser driving circuit, and a laser source collimation unit. The laser driving circuit converts the signal into a light intensity signal emitted by the LED. In pulse driving, a GaN-based laser diode is selected as the transmitter. The laser driving circuit is designed to superimpose the desired pulse signal with a DC bias, and the light intensity emitted by the laser diode can be changed by adjusting a potentiometer in the circuit, thus converting the pulsed electrical signal into a light intensity signal from the laser diode. The laser source collimation unit is used to collimate and shape the emitted beam to meet the requirements of long-distance communication. In source collimation, by calculating the focal length of the lens and the divergence angle of the laser diode, a threaded hole concentric with the lens is designed in the aluminum alloy housing. The lens is encapsulated using a housing with an external thread of M9×0.5, which can be screwed into the aluminum alloy housing. The distance between the lens and the laser diode can be adjusted according to the required spot size, thereby adjusting the spot size. This optically solves the problem of laser source collimation.

[0035] The receiving module includes a laser beam focusing unit, a photodiode, an amplifier circuit, and a data reading circuit. The laser beam focusing unit is used to focus the intensity of the laser signal so that it completely covers the surface of the photodiode to complete the signal reception. In the laser beam focusing process, by calculating the focal length of the lens and the size of the focused beam, a housing corresponding to the lens size is designed and connected to the receiver housing via an M9×1.25 thread. The focused beam completely covers the surface of the photodiode, thereby achieving the purpose of focusing and receiving the optical signal.

[0036] The photodiode is used for photoelectric conversion to output electrical signals. In photoelectric detection, a photodiode with appropriate responsivity is selected based on the frequency of the green light emitted by the light-emitting diode at the emitting end and the light intensity after long-distance transmission. For example, a PIN photodiode is used. The PIN photodiode has a high modulation bandwidth. The incident photon energy meets the band transition conditions of the semiconductor material. Electrons in the valence band of the active region are excited and jump to the conduction band, while holes are formed in the valence band. The electron-hole pairs formed are drawn to both ends of the device under the action of the built-in electric field, thereby forming a photocurrent.

[0037] The amplification circuit amplifies the signal and then inputs it into the data reading circuit for reading. In the signal amplification, based on the actual input signal and the current and voltage of the required output signal, in order to recover the weak electrical signal detected by the photodiode into a pulse signal, a corresponding transimpedance amplifier is designed, which can amplify the received signal within a certain range. The amplification factor can be adjusted by the potentiometer in the circuit.

[0038] In one embodiment of the present invention, multiple gamma-ray detection devices are positioned at different detection points around the nuclear power plant. These devices periodically output pulse signals to the laser receiver via a shared laser emitter, saving costs. The multiple gamma-ray detection devices do not interfere with each other; for example, five gamma-ray detection devices may sequentially emit signals for 2 seconds each. The laser emitter and laser receiver can communicate bidirectionally, allowing staff to remotely adjust preset parameters of the gamma-ray detection devices and the laser emitter via a wireless transmission module, facilitating parameter adjustments for non-compliance.

[0039] In one embodiment of the present invention, a γ-ray monitoring method based on SiC semiconductor is provided. Based on the aforementioned γ-ray monitoring system, the monitoring method includes the following steps:

[0040] The radiation field is measured using a SiC detector, and the generated signal is processed into a pulse signal for input to the laser emitter.

[0041] In the laser emitting end, the laser driving circuit drives the light-emitting diode to emit laser signals of different intensities according to the pulse signal, and sends them to the laser receiving end through the laser source collimation unit;

[0042] At the laser receiver, the laser signal is converted into an electrical signal after being focused and detected by photoelectric detection.

[0043] The electrical signal is amplified, filtered, and digitally shaped in sequence before being sent to the FPGA in the industrial control computer for processing and analysis, so as to achieve real-time output to the human-machine interface for display.

[0044] In a preferred embodiment, multiple gamma-ray detection devices are set up within the same radiation field. These devices periodically output pulse signals to a single laser receiver via a shared laser emitter. Based on the different distances between the gamma-ray detection devices and the nuclear reactor radiation source, a theoretical ranking of the detected gamma-ray irradiation intensities is obtained. If the actual ranking of the detection results from multiple gamma-ray detection devices consistently deviates from the theoretical ranking within a specified time, an alarm is issued, and relevant personnel are notified to verify the situation. For example, according to distance theory, the gamma-ray irradiation intensity at point A is greater than that at point B; however, the actual situation is the opposite. If this situation persists for an extended period, it indicates a problem with the detection end, requiring contact with technical personnel for verification.

[0045] The γ-ray monitoring system and method based on SiC semiconductor provided by this invention have the following advantages:

[0046] (1) The third-generation semiconductor material SiC is used for γ-ray monitoring, giving full play to its unique characteristics such as large band gap, high critical breakdown field strength, strong thermal stability, high electron mobility, high thermal conductivity, and superior radiation resistance, thus overcoming the problem that traditional semiconductor detectors cannot work in harsh environments such as high temperature and strong radiation fields.

[0047] (2) Using GaN light-emitting diodes to realize wireless real-time optical communication technology, the transmitted signal is error-free and lossless. Compared with radio frequency communication and microwave communication, it is less susceptible to radiation and electromagnetic interference. It has advantages such as not occupying frequency band, large communication capacity, high transmission rate, resistance to electromagnetic interference and prevention of eavesdropping.

[0048] (3) A preamplifier and filtering and digital shaping circuit were designed based on the signal characteristics of the SiC detector to improve the signal-to-noise ratio of the entire detection system, change the pulse shape, and obtain better performance indicators.

[0049] (4) It has achieved high energy resolution, radiation resistance, high temperature resistance, and wireless real-time continuous γ-ray monitoring.

[0050] The above description is merely a preferred embodiment of the present invention and does not limit its patent scope. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, whether directly or indirectly applied to other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A γ-ray monitoring system based on SiC semiconductor, characterized in that, The system includes a gamma-ray detection device and a wireless transmission module. The gamma-ray detection device, based on SiC semiconductors, detects gamma rays around a nuclear power plant and is configured to convert gamma-ray signals into pulse signals for output. The wireless transmission module includes a laser transmitter and a laser receiver. The laser transmitter is located in a radiation hazard zone, while the laser receiver is located in a radiation safe zone. The laser transmitter includes a laser diode, a laser driving circuit, and a laser source collimation unit. The laser driving circuit is configured to control the voltage driving signal of the laser diode according to the pulse signal output by the gamma-ray detection device. The laser diode adjusts its output laser signal in real time according to the voltage driving signal and aligns the output laser signal to the laser receiver through the laser source collimation unit. The laser receiver performs photoelectric conversion processing on the received laser signal and then outputs it.

2. The gamma-ray monitoring system according to claim 1, characterized in that, The laser diode is a GaN laser diode. The laser driving circuit superimposes the pulse signal to be transmitted with a DC bias signal and changes the intensity of the laser emitted by the laser diode in real time through a potentiometer.

3. The gamma-ray monitoring system according to claim 1, characterized in that, The receiving module includes a laser beam focusing unit, a photodiode, an amplifier circuit, and a data reading circuit. The laser beam focusing unit is used to focus the intensity of the laser signal so that it completely covers the surface of the photodiode to complete the signal reception. The photodiode is used for photoelectric conversion to output an electrical signal. The amplifier circuit amplifies the electrical signal and inputs it into the data reading circuit for reading.

4. The gamma-ray monitoring system according to claim 1, characterized in that, Multiple gamma-ray detection devices are set up at different detection points around the nuclear reactor. The multiple gamma-ray detection devices periodically output pulse signals to the laser receiver through the same laser emitting end in a time-division manner, and the multiple gamma-ray detection devices do not interfere with each other.

5. The gamma-ray monitoring system according to claim 1, characterized in that, The laser transmitter and the laser receiver can communicate bidirectionally, and staff can remotely adjust the preset parameters of the gamma-ray detection device and the laser transmitter through the wireless transmission module.

6. The gamma-ray monitoring system according to claim 1, characterized in that, The gamma-ray detection device includes a SiC detector, a preamplifier, and a filtering and digital shaping circuit connected in sequence.

7. The gamma-ray monitoring system according to claim 6, characterized in that, The design of the SiC detector includes the following steps: The process involves determining the thickness and dimensions of the SiC semiconductor epitaxial layer; determining the net doping rate of the SiC semiconductor epitaxial layer; determining the electrode material and contact method of the SiC semiconductor epitaxial layer; determining the SiC detector packaging method and PCB circuit design; determining the range of gamma-ray energies that the SiC detector can measure, and thus determining the pulse amplitude of the voltage signal it generates.

8. The gamma-ray monitoring system according to claim 6, characterized in that, The filtering and digital shaping circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, a second capacitor, and an operational amplifier. The first resistor, the second resistor, and the positive input terminal of the operational amplifier are electrically connected in sequence. One end of the third resistor is grounded, and the other end is connected to the negative input terminal of the operational amplifier. One end of the fourth resistor is connected to the negative input terminal of the operational amplifier, and the other end is connected to the output terminal of the operational amplifier. One end of the first capacitor is grounded, and the other end is connected to the positive input terminal of the operational amplifier. One end of the second capacitor is connected between the first resistor and the second resistor, and the other end is connected to the output terminal of the operational amplifier.

9. A method for monitoring gamma rays based on SiC semiconductors, characterized in that, Based on the γ-ray monitoring system according to any one of claims 1-8, the monitoring method includes the following steps: The radiation field is measured using a SiC detector, and the generated signal is processed into a pulse signal for input to the laser emitter. In the laser emitting end, the laser driving circuit drives the laser diode to emit laser signals of different intensities according to the pulse signal, and sends them to the laser receiving end through the laser source collimation unit; At the laser receiver, the laser signal is converted into an electrical signal after being focused and detected by photoelectric detection. The electrical signal is amplified, filtered, and digitally shaped in sequence before being sent to an industrial control computer for processing and analysis, so as to achieve real-time output to the human-machine interface for display.

10. The γ-ray monitoring method based on SiC semiconductor according to claim 9, characterized in that, Multiple gamma-ray detection devices are set up in the same radiation field. The multiple gamma-ray detection devices periodically output pulse signals to the same laser receiving end through the same laser emitting end in a time-division manner. According to the different distances between the gamma-ray detection devices and the nuclear power plant radiation source, the theoretical ranking of the gamma-ray irradiation intensity detected by the different gamma-ray detection devices is obtained. If the actual ranking of the detection results of multiple gamma-ray detection devices does not match the theoretical ranking for a specified time, an alarm is issued and relevant personnel are notified to verify the situation.

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