Neutron flux detector and neutron flux detection device of zero-power reactor

Abstract

The invention relates to the technical field of reactor physical test and measurement, in particular to a neutron flux detector and a neutron flux detection device of a zero-power reactor, the neutron flux detector comprises a CLYC scintillator, a reflecting layer, a photoelectric conversion multiplier and front-end electronics, the photoelectric conversion multiplier is attached to a certain side face of the scintillator, and the front-end electronics are arranged on the side face of the CLYC scintillator. The reflecting layer is attached to the remaining side face of the CLYC scintillator, and the photoelectric conversion multiplier is electrically connected with the front-end electronics. The device comprises a neutron flux detector, a multi-path data acquisition system, a connector and a lifting device, according to the invention, efficient online measurement of the neutron flux is realized in a zero-power reactor environment, the limitation that a traditional method depends on off-line measurement is overcome, and the detector has excellent thermal neutron response capability based on the miniaturized design of the CLYC crystal and a tungsten alloy shielding structure, and is suitable for a complex high gamma background environment of a reactor.

Description

Technical Field

[0001] The invention relates to the technical field of reactor physical testing and measurement, and in particular to a neutron flux detector and a neutron flux detection device for a zero-power reactor. Background Art

[0002] Reactor neutron flux distribution measurement test is a basic topic in reactor physics research. Accurately measuring the distribution of reactor core neutron flux is a prerequisite for ensuring the safe operation and effective use of the reactor. Not only are the layout of the coolant flow in the reactor, the safety limit of the nuclear fuel elements and other technical issues of the reactor itself closely related to the spatial distribution of the neutron flux in the reactor, but the neutron flux distribution in the reactor also provides parameters for reactor design and safe operation. For example, in order to increase the average power density of the core, the neutron flux distribution in the core needs to be flattened as much as possible. How to verify whether the neutron flux in the core is flat needs to be verified through direct measurement.

[0003] At present, the methods used to measure the distribution of reactor neutron flux mainly include activation method, nuclear fission method and self-powered detector method. For zero-power reactors, due to their very low flux level, nuclear fission detectors and self-powered detectors cannot obtain a signal level of sufficient intensity, and the radiation intensity is relatively low. After the reactor is shut down, the radioactivity level can be quickly restored to the background level. Therefore, the activation method is more commonly used in zero-power reactors.

[0004] The activation method is to place a large number of activated detection foils in the core. After the core is irradiated with neutrons, the detection foils are taken out for activation measurement to inversely calculate the core neutron flux. This is an offline measurement method that cannot measure the core neutron flux in real time.

[0005] Therefore, in view of the low neutron flux of zero-power reactors and the shortcomings of the activation method, self-powered method and fission chamber method, this paper proposes a method for measuring the neutron flux of zero-power reactors. Summary of the invention

[0006] In order to solve the above problems, the present invention aims to provide a neutron flux detector and a neutron flux detection device for a zero-power reactor, thereby realizing online measurement of the neutron flux of the zero-power reactor.

[0007] The present invention is achieved through the following technical solutions:

[0008] A neutron flux detector for a zero-power reactor comprises: a CLYC scintillator, a reflective layer, a photoelectric conversion multiplier device and front-end electronics, wherein the photoelectric conversion multiplier device is optically coupled to a side surface of the scintillator, the reflective layer is attached to the remaining side surface of the CLYC scintillator, and the photoelectric conversion multiplier device is electrically connected to the front-end electronics.

[0009] Specifically, the CLYC scintillator adopts nat Li-CLYC crystal, the reflective layer adopts a tungsten alloy shielding layer.

[0010] Optionally, the size of the CLYC scintillator is φ3mm*3mm.

[0011] Specifically, the front-end electronics include: a SiPM power supply module, an operational amplifier power supply module, a temperature feedback module, and a signal preamplifier module, and the photoelectric conversion multiplier device, the SiPM power supply module, the operational amplifier power supply module, the temperature feedback module, and the signal preamplifier module are all connected to a PCB board.

[0012] Furthermore, the neutron flux detector also includes a sealed aluminum alloy shell, and the CLYC scintillator, the reflective layer, the photoelectric conversion multiplier device, the front-end electronics and the PCB board are all arranged in the aluminum alloy shell, and the diameter of the aluminum alloy shell is smaller than the reactor core through hole.

[0013] A neutron flux detection device for a zero-power reactor comprises a neutron flux detector, a multi-channel data acquisition system, a connector and a lifting device, wherein the connector is fixedly connected to the lifting end of the lifting device, a plurality of neutron flux detectors are mounted on the connector and correspond to a plurality of reactor core through holes, and the signal output ends of the neutron flux detectors are all electrically connected to the signal input ends of the multi-channel data acquisition system.

[0014] Specifically, the connector includes: a mounting bracket and a connecting rod, the upper ends of multiple connecting rods are connected to the mounting bracket, and the multiple neutron flux detectors are respectively connected to the lower ends of multiple connecting rods. The connecting rod is a hollow rod, and the cable between the multi-channel data acquisition system and the neutron flux detector is arranged in the connecting rod.

[0015] Specifically, the lifting device includes: a base, a vertical lifting assembly and a horizontal telescopic assembly, the lower end of the vertical lifting assembly is fixedly connected to the base, the first end of the horizontal telescopic assembly is fixedly connected to the lifting end of the vertical lifting assembly, and the connector is connected to the second end of the horizontal telescopic assembly.

[0016] Specifically, the vertical lifting assembly includes:

[0017] A lifting frame is vertically arranged, and the lower end of the lifting frame is fixedly connected to the base;

[0018] A lifting arm, which is slidably connected to the lifting frame up and down;

[0019] A pulley block, which is arranged at the upper end of the lifting frame;

[0020] A drum and a steel rope, wherein the steel rope is wound on the drum, and the free end of the steel rope passes around the pulley block and is fixedly connected to the lifting arm, and the drum is driven to rotate by the lifting motor.

[0021] Specifically, the horizontal telescopic component includes:

[0022] An outer cylinder, one end of which is fixedly connected to the lifting arm, and the outer cylinder is provided with a slot along its axial direction;

[0023] An inner cylinder is arranged inside the outer cylinder, and the inner cylinder is provided with a through hole adapted to the slot, and the inner cylinder slides relative to the outer cylinder in the axial direction;

[0024] A locking nut passes through the slot and the through hole, and the locking nut applies a pre-tightening force to the outer cylinder and the inner cylinder.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] The device provided by the present invention is mainly composed of a CLYC scintillator, a photoelectric conversion multiplication device and a front-end electronic module, wherein the CLYC scintillator adopts nat The Li-CLYC crystal is coated with a tungsten alloy reflective layer to enhance neutron detection efficiency and reduce gamma-ray interference. The detector is encapsulated in an aluminum alloy casing and connected to a lifting device to achieve real-time measurement of the axial and radial neutron fluxes in the core.

[0027] The present invention realizes efficient online measurement of neutron flux in a zero-power reactor environment, overcoming the limitation of traditional methods that rely on offline measurement. Based on the miniaturized design of CLYC crystal and tungsten alloy shielding structure, the detector has excellent thermal neutron response capability and is suitable for the complex high-γ background environment of the reactor. At the same time, the application of the multi-channel data acquisition system enables the detector to transmit nuclear pulse signals in real time and accurately, improving the accuracy of neutron and gamma ray discrimination. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, are used to explain the principles of the present invention. These drawings are included to provide a further understanding of the present invention, and the accompanying drawings are included in and constitute a part of this specification and do not constitute a limitation of the embodiments of the present invention.

[0029] Figure 1 It is a schematic structural diagram of a neutron flux detector for a zero-power reactor according to the present invention.

[0030] Figure 2 3 is a diagram showing the detection efficiency of thermal neutrons by CLYC crystals of different thicknesses according to the present invention.

[0031] Figure 3 It is a hardware block diagram of the overall design of the multi-channel data acquisition system according to the present invention.

[0032] Figure 4 It is a schematic diagram of the structure of the mounting bracket according to the present invention.

[0033] Figure 5 It is a schematic structural diagram of the lifting device according to the present invention.

[0034] Figure 6 It is a schematic structural diagram of the vertical lifting assembly according to the present invention.

[0035] Reference numerals:

[0036] 1-base, 2-lifting frame, 3-reel, 4-lifting motor, 5-steel rope, 6-pulley block, 7-buffer head, 8-buffer pad, 9-outer cylinder, 10-inner cylinder, 11-slot, 12-locking nut, 13-lifting head, 14-connector, 16-vertical sensor, 17-lifting arm, 18-limit switch, 21-CLYC scintillator, 22-reflection layer, 23-photoelectric conversion multiplier device, 24-front-end electronics, 25-housing. DETAILED DESCRIPTION

[0037] To make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and implementation methods. It is understood that the specific implementation methods described herein are only used to explain the relevant content, rather than to limit the present invention.

[0038] It should also be noted that, for the convenience of description, only the parts related to the present invention are shown in the drawings.

[0039] In the absence of conflict, the embodiments and features of the embodiments of the present invention may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0040] Embodiment 1

[0041] Generally, CLYC neutron detectors are mostly used for space neutron detection. However, research has found that in reactors, even in zero-power reactors, the neutron flux is several orders of magnitude higher than that of space neutrons, and is accompanied by a large number of gamma rays. Under high neutron flux density and strong gamma radiation fields, CLYC pulse signals will accumulate seriously, resulting in problems such as decreased pulse effective counting rate, prolonged dead time, and reduced energy resolution. Therefore, it is necessary to reduce the thermal neutron detection efficiency through the design of CLYC crystals and add gamma ray shielding to alleviate the pulse accumulation phenomenon.

[0042] like Figure 1 As shown, a neutron flux detector for a zero-power reactor is provided, comprising: a CLYC scintillator 21, a reflective layer 22, a photoelectric conversion multiplier device 23 and front-end electronics 24, wherein the photoelectric conversion multiplier device 23 is optically coupled to a certain side surface of the scintillator, the reflective layer 22 is attached to the remaining side surface of the CLYC scintillator 21, and the photoelectric conversion multiplier device 23 is electrically connected to the front-end electronics 24.

[0043] Scintillator is a scintillation crystal material containing lithium-6 that generates charged particles by reacting with neutrons, thereby producing a fluorescent signal. Figure 2 As shown, at the same thickness, 95% 6 The thermal neutron detection efficiency of Li-CLYC crystal is much greater than nat Li-CLYC, choose small size, nat Li-CLYC is used to reduce the thermal neutron detection efficiency of the detector and increase the upper limit of the thermal neutron flux measurement of the detector. Therefore, CLYC scintillator 21 is used nat Li-CLYC crystal.

[0044] Common gamma-ray shielding materials include lead, tungsten, bismuth, etc. Among them, tungsten alloy has better gamma-ray shielding ability than lead and bismuth, has high mechanical strength, and is non-toxic and environmentally friendly. In this embodiment, by adding a tungsten alloy shield outside the CLYC crystal, the interference of gamma rays on neutron detection is reduced, that is, the reflective layer 22 uses a tungsten alloy shielding layer. The reflective layer 22 is bonded to the side of the CLYC scintillator 21 that is not bonded to the optoelectronic device, which further enhances the directional collection and signal-to-noise ratio of the neutron signal.

[0045] Meanwhile, in order to adapt to the miniaturization of the reactor, the size of the CLYC scintillator 21 is φ3 mm*3 mm.

[0046] The photoelectric conversion multiplier 23 (SiPM) can convert the weak light signal generated by the scintillator into an electrical signal. The SiPM is composed of multiple micro photodiodes and has extremely high gain, which is suitable for detecting low light signals. The SiPM is attached to one side of the CLYC scintillator 21 to achieve effective collection of light signals and conversion of electrical signals, and output to the subsequent front-end electronics 24 module.

[0047] Neutrons react with the CLYC scintillator 21 to generate alpha particles and tritium nuclei, and generate optical signals in the process. The optical signals are captured by the SiPM attached to one side of the scintillator and converted into electrical signals. The reflective layer 22 is used to reduce the interference of background gamma rays on the scintillator, ensuring that the optical signals caused by neutrons are purer. The SiPM converts the optical signals into electrical signals and amplifies the output, and the front-end electronics 24 further amplifies and stabilizes the electrical signals.

[0048] Embodiment 2

[0049] The front-end electronics 24 include: SiPM power supply module, operational amplifier power supply module, temperature feedback module, signal preamplifier module, and the photoelectric conversion multiplier device 23, SiPM power supply module, operational amplifier power supply module, temperature feedback module and signal preamplifier module are all connected to the PCB board.

[0050] The external power input supplies power to the SiPM and preamplifier. The optical signal is converted into a current signal by the SiPM array, and then the preamplifier outputs the analog signal to the acquisition system through I / V conversion and preliminary amplification. Since the SiPM gain has a linear relationship with temperature, changes in the measurement environment temperature will cause the peak position of the detector output spectrum to drift. In order to reduce the impact of temperature on the detector performance, bias temperature compensation is adopted for the SiPM gain. When the temperature changes, the bias of the SiPM is changed to adjust the gain.

[0051] The SiPM power supply module is used to provide a stable bias voltage for the SiPM to ensure that the SiPM can work properly. Since the gain of the SiPM is proportional to the supply voltage, its performance will fluctuate with the change of the supply voltage. Therefore, the SiPM power supply module uses a high-precision voltage stabilization circuit, which can fine-tune the voltage according to the actual working environment of the detector, ensuring that the detector maintains a stable gain under different ambient temperatures or power supply fluctuations, thereby ensuring the accuracy and reliability of neutron flux detection.

[0052] The operational amplifier power supply module provides stable power support for the operational amplifier (Op-Amp) in the preamplifier module, ensuring that the linear amplification process of the signal is not affected by power supply fluctuations. Since the electrical signal output by the detector is usually relatively weak, in order to ensure that the subsequent data acquisition system can accurately receive the signal, the operational amplifier power supply module adopts a low-noise, voltage-stabilized design, which reduces the impact of power supply ripple and noise on the operational amplifier circuit, thereby improving the stability of the signal amplification effect. In a high-sensitivity detection environment, any power supply fluctuation will directly affect the accuracy of the amplified signal. Therefore, the present invention adds filtering and voltage stabilization measures to the operational amplifier power supply module, so that the operational amplifier power supply module can also work stably within a wide voltage range.

[0053] The gain of SiPM fluctuates with temperature, so a temperature feedback module is added to the detector. The temperature feedback module monitors the ambient temperature around SiPM in real time and feeds back the temperature signal to the control system, thereby automatically adjusting the bias voltage of SiPM to compensate for the gain fluctuation caused by temperature changes. Specifically, when the temperature rises, the gain of SiPM will decrease. At this time, the temperature feedback module will increase the bias voltage to improve the gain; conversely, when the temperature decreases, the module will reduce the bias voltage to prevent the gain from being too high. The application of the temperature feedback module ensures the stability of the detector under different temperature conditions, so that the electrical signal output by SiPM always remains within the set range, thereby improving the accuracy of the measurement.

[0054] The signal preamplifier module is responsible for the preliminary amplification of the primary electrical signal output by the SiPM so that the subsequent data acquisition system can accurately identify and process the signal. In nuclear detection applications, electrical signals are usually very weak, and direct transmission to the data acquisition system will result in a decrease in signal quality, so they need to be amplified by the preamplifier module. This module uses a low-noise operational amplifier to perform current-to-voltage (I / V) conversion and amplification processing on the current signal output by the SiPM, raising the weak electrical signal to an amplitude range that can be recognized by subsequent equipment. The high gain and low noise characteristics of the preamplifier module design enable the amplified signal to maintain a high signal-to-noise ratio even in a strong gamma-ray background, effectively improving the accuracy and reliability of neutron flux measurements.

[0055] The neutron flux detector also includes a sealed aluminum alloy shell 25, in which the CLYC scintillator 21, the reflective layer 22, the photoelectric conversion multiplier device 23, the front-end electronics 24 and the PCB board are all arranged. The diameter of the aluminum alloy shell 25 is smaller than the reactor core through hole.

[0056] The entire detector is encapsulated in a sealed aluminum alloy shell 25, which has high mechanical strength, radiation resistance and corrosion resistance, providing the necessary physical protection for the detector. The diameter of the shell 25 is designed to be smaller than the diameter of the through hole of the reactor core, so that it can be flexibly moved in the core to meet the neutron flux measurement requirements at different locations. In addition, the sealing of the aluminum alloy shell 25 also ensures that the internal components are protected from contamination and damage by the external environment, which helps to improve the overall life and stability of the detector.

[0057] In addition, in order to facilitate the installation of the entire device, the housing 25 can be divided into an end cover, a coverless housing, a sealing ring, etc. After the remaining components are placed in the coverless housing, the housing 25 is sealed by the end cover and the sealing ring. At the same time, a cable lead-out interface of the PCB board is provided on the end cover to facilitate the electrical connection of the entire neutron flux detector with the outside.

[0058] Embodiment 3

[0059] like Figure 4 , Figure 5 and Figure 6 As shown, a neutron flux detection device for a zero-power reactor is provided, including a neutron flux detector, a multi-channel data acquisition system, a connector 14 and a lifting device, wherein the connector 14 is fixedly connected to the lifting end of the lifting device, a plurality of neutron flux detectors are mounted on the connector 14 and correspond to a plurality of reactor core through holes, and the signal output ends of the neutron flux detectors are electrically connected to the signal input ends of the multi-channel data acquisition system.

[0060] The neutron flux detector is responsible for capturing neutron flux signals inside the reactor core. Multiple detectors are installed at positions corresponding to multiple core through holes to ensure that neutron flux data at different positions can be collected. The detector converts the captured neutron flux signal into an electrical signal through photomultiplier technology and front-end electronics 24 system, providing the original signal source for subsequent processing by the data acquisition system.

[0061] The multi-channel data acquisition system is used to synchronously process signals from multiple neutron flux detectors. The system has high-precision and high-speed pulse signal processing capabilities, and can digitize and store the electrical signals generated by the detectors for subsequent analysis. The system is electrically connected to the signal output terminals of each neutron flux detector through multiple signal input terminals, realizing parallel acquisition of neutron flux data at different locations, thereby supporting real-time monitoring of multiple point data in the core.

[0062] The cooperation of the lifting device and the connector 14 realizes the axial movement of the detector in the core. The lifting device can adjust the height position of the detector according to the measurement requirements, complete the neutron flux measurement at different axial positions of the core, and improve the measurement coverage and flexibility.

[0063] Embodiment 4

[0064] The multi-channel data acquisition system in this embodiment is used to realize the accurate acquisition, transmission and processing of the high-speed nuclear pulse signal captured by the detector. The system has a high sampling rate and high precision, and can support the synchronous acquisition and real-time monitoring of multi-channel signals, so that the accuracy and stability of the measurement data can still be guaranteed in the zero-power reactor environment with low flux level. Specifically, the multi-channel data acquisition system in the present invention is constructed based on a high sampling rate ADC (analog-to-digital converter) and an FPGA (field programmable gate array). The sampling rate of the data acquisition system reaches 250MSPS, and the sampling accuracy is 14 bits. Through high-speed sampling of each detector signal, subtle changes in the nuclear pulse signal can also be accurately captured. Figure 3 Provide the overall hardware block diagram for the multi-channel data acquisition system.

[0065] The multi-channel data acquisition system is designed with CAEN's DT5725 module to achieve multi-channel data synchronous acquisition. The DT5725 module integrates a high-precision ADC and a programmable FPGA control module, which can sample and process the output signals of each neutron flux detector in real time. This module can not only identify the pulse waveform of gamma-neutron signals, but also has the functions of amplitude analysis, zero-length encoding and dynamic acquisition window, making data processing more flexible and efficient. In addition, the firmware of this module supports the n / γ discrimination algorithm, which classifies and processes various types of nuclear pulse signals by identifying the differences in the pulse waveforms of gamma and neutron signals, effectively improving the accuracy of neutron and gamma ray signal discrimination.

[0066] The 250M high-speed continuous sampling ADC is used for data processing, and the high-speed FPGA is used for trapezoidal digital filtering to obtain the energy spectrum of gamma and neutron signals. Based on the device DPP-PSD firmware for n / γ discrimination, the digital delay circuit, digital constant ratio timing, and digital TDC generated by the high-speed FPGA are used. Compared with the traditional solution, a fully digital design is realized, and the parameter adjustment is more flexible and more compact.

[0067] In the multi-channel data acquisition system, the original analog signal collected by the high-speed ADC will be converted into a digital signal in real time, and then the complex digital signal processing will be performed by FPGA. In particular, the trapezoidal digital filtering algorithm is applied in the processing process to ensure that the energy spectrum of the gamma and neutron signals is clearer. This filtering algorithm can effectively suppress the high-frequency noise in the signal and maintain the stability and accuracy of the signal, making the detector more sensitive and reliable in the complex radiation field environment. Compared with traditional analog signal processing, the advantage of digital filtering is that the parameter adjustment is more flexible and the system miniaturization effect is significant.

[0068] In the multi-channel data acquisition system of the present invention, n / γ signal discrimination is a key step to ensure measurement accuracy. Based on the gamma-neutron pulse waveform recognition function of the DPP-PSD firmware, the system performs digital delay, constant ratio timing and digital time difference measurement (TDC) on the collected signals to distinguish between gamma ray and neutron signals. Compared with traditional signal discrimination schemes, the digital processing method can more efficiently screen and classify signals, especially in complex reactor environments with high gamma background, and can ensure accurate discrimination of neutron signals.

[0069] After signal processing, the digitized nuclear pulse signal will be transmitted to the data storage unit in real time for subsequent data analysis and reactor status monitoring. The system's built-in high-speed data bus supports the rapid transmission of large amounts of data and can achieve parallel transmission of multi-channel signals, ensuring that the detector signal is stored and read without distortion.

[0070] Embodiment 5

[0071] like Figure 4 As shown, the connector 14 includes: a mounting bracket and a connecting rod, the upper ends of multiple connecting rods are connected to the mounting bracket, and multiple neutron flux detectors are respectively connected to the lower ends of the multiple connecting rods. The connecting rod is a hollow rod, and the cable between the multi-channel data acquisition system and the neutron flux detector is arranged in the connecting rod.

[0072] The mounting bracket is responsible for fixing the upper ends of the multiple connecting rods, and the position of the mounting bracket is directly connected to the lifting end of the lifting device, ensuring that when the lifting device moves, the connector 14 and each neutron flux detector can move synchronously, thereby realizing the neutron flux measurement at different height positions of the reactor.

[0073] The connecting rod is used to install the neutron flux detector at its lower end, and its upper end is connected to the mounting bracket, which plays the role of fixing the detectors one by one in a specific position. The connecting rod is designed as an aluminum alloy hollow structure to facilitate internal wiring. The hollow part of each connecting rod accommodates the signal transmission cable from the detector to the multi-channel data acquisition system to reduce the possibility of external interference. The optional lengths are 60cm, 80cm, 100cm, 120cm, etc.

[0074] like Figure 5 and Figure 6 As shown, in order to realize the axial movement of the neutron detector in the core and realize the online measurement of neutron flux at different heights, an adjustable lifting device is designed, which includes: a base 1, a vertical lifting assembly and a horizontal telescopic assembly. The lower end of the vertical lifting assembly is fixedly connected to the base 1, the first end of the horizontal telescopic assembly is fixedly connected to the lifting end of the vertical lifting assembly, and the connector 14 is connected to the second end of the horizontal telescopic assembly.

[0075] The base 1 is the supporting structure of the entire lifting device and is usually fixed on one side of the reactor. It is used to stably support the entire lifting device and provide a fixing point for the vertical lifting assembly. In order to reduce vibration, a buffer pad 8 is provided between the vertical lifting assembly and the base 1.

[0076] The vertical lifting assembly includes: a lifting frame 2, a lifting arm 17, a pulley block 6, a drum 3 and a steel rope 5. The lifting frame 2 is vertically arranged, and the lower end of the lifting frame 2 is fixedly connected to the base 1; the lifting arm 17 is connected to the lifting frame 2 for vertical sliding; the pulley block 6 is arranged at the upper end of the lifting frame 2; the steel rope 5 is wound on the drum 3, and the free end of the steel rope 5 passes through the pulley block 6 and is fixedly connected to the lifting arm 17. The drum 3 is driven to rotate by the lifting motor 4, driving the steel rope 5 to pull or release, thereby realizing the up and down sliding of the lifting arm 17.

[0077] The horizontal telescopic assembly includes: an outer cylinder 9, an inner cylinder 10, and a locking nut 12. One end of the outer cylinder 9 is fixedly connected to the lifting arm 17, and the outer cylinder 9 is provided with a slot 11 along its axial direction; the inner cylinder 10 is arranged in the outer cylinder 9, and the inner cylinder 10 is provided with a through hole adapted to the slot 11, and the inner cylinder 10 slides in the axial direction relative to the outer cylinder 9; the locking nut 12 passes through the slot 11 and the through hole, and the locking nut 12 applies a pre-tightening force to the outer cylinder 9 and the inner cylinder 10 to ensure that the inner cylinder 10 and the outer cylinder 9 can be firmly locked after positioning adjustment to prevent unnecessary movement of the inner cylinder 10 in the horizontal position.

[0078] The vertical lifting assembly controls the reel 3 to rotate through the lifting motor 4, drives the steel rope 5 to rise and fall, and makes the lifting arm 17 slide up and down along the lifting frame 2 to achieve the height adjustment of the detector. The horizontal telescopic assembly adjusts the lateral position of the detector through the relative sliding of the outer cylinder 9 and the inner cylinder 10. When the locking nut 12 is at the target position, it applies a pre-tightening force to the inner and outer cylinders 9 to ensure the stability of the position.

[0079] A vertical sensor is installed on the lifting frame 2 to detect the real-time height position of the detector in the pile. A magnetic slider is fixed on the steel rope 5. The position change of the magnetic slider during the lifting process will be sensed by the sensor and generate a signal, thereby displaying the current height of the detector. In order to ensure the safe operation of the detector during the lifting or lowering process, limit switches 18 are respectively set at the top and bottom of the lifting frame 2, and the output signal of the limit switch 18 is connected to the control system of the lifting motor 4. When the detector approaches the top or bottom of the core, the limit switch 18 automatically triggers a signal to control the lifting motor 4 to stop running, so as to prevent the detector from being lifted out of the pile or falling too low and being damaged. In addition, in order to prevent the lifting arm 17 from descending to the bottom too quickly, a buffer head 7 is set at the bottom.

[0080] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments / methods or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments / methods or examples described in this specification and the features of the different embodiments / methods or examples, unless they are contradictory.

[0081] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0082] It should be understood by those skilled in the art that the above embodiments are only for the purpose of clearly illustrating the present invention, and are not intended to limit the scope of the present invention. For those skilled in the art, other changes or modifications may be made based on the above invention, and these changes or modifications are still within the scope of the present invention.

Claims

1. A neutron flux detector for a zero power reactor, characterized in that: include: A CLYC scintillator (21), a reflective layer (22), a photoelectric conversion multiplier device (23) and front-end electronics (24), wherein the photoelectric conversion multiplier device (23) is optically coupled to a side surface of the scintillator, the reflective layer (22) is attached to the remaining side surface of the CLYC scintillator (21), and the photoelectric conversion multiplier device (23) is electrically connected to the front-end electronics (24).

2. A neutron flux detector for a zero power reactor according to claim 1, characterized in that: The CLYC scintillator (21) adopts nat Li-CLYC crystal, the reflective layer (22) adopts a tungsten alloy shielding layer.

3. A neutron flux detector for a zero power reactor according to claim 2, characterized in that: The size of the CLYC scintillator (21) is φ3 mm*3 mm.

4. A neutron flux detector for a zero power reactor according to claim 3, characterized in that: The front-end electronics (24) include: a SiPM power supply module, an operational amplifier power supply module, a temperature feedback module, and a signal preamplifier module, and the photoelectric conversion multiplier device (23), the SiPM power supply module, the operational amplifier power supply module, the temperature feedback module, and the signal preamplifier module are all connected to a PCB board.

5. A neutron flux detector for a zero power reactor according to claim 1, characterized in that: It also comprises a sealed aluminum alloy shell (25), wherein the CLYC scintillator (21), the reflective layer (22), the photoelectric conversion multiplier device (23), the front-end electronics (24) and the PCB board are all arranged in the aluminum alloy shell (25), and the diameter of the aluminum alloy shell (25) is smaller than the reactor core through hole.

6. A neutron flux detection device for a zero power reactor, characterized in that: It comprises a neutron flux detector as described in any one of claims 1 to 5, a multi-channel data acquisition system, a connector (14) and a lifting device, wherein the connector (14) is fixedly connected to the lifting end of the lifting device, a plurality of neutron flux detectors are mounted on the connector (14) and correspond to a plurality of reactor core through holes, and the signal output ends of the neutron flux detectors are electrically connected to the signal input ends of the multi-channel data acquisition system.

7. A neutron flux detection device for a zero power reactor according to claim 6, characterized in that: The connector (14) comprises: a mounting bracket and a connecting rod, the upper ends of the plurality of connecting rods are connected to the mounting bracket, the plurality of neutron flux detectors are respectively connected to the lower ends of the plurality of connecting rods, the connecting rod is a hollow rod, and the cables between the multi-channel data acquisition system and the neutron flux detectors are arranged in the connecting rod.

8. The neutron flux detection device for a zero power reactor according to claim 6, characterized in that: The lifting device comprises: a base (1), a vertical lifting assembly and a horizontal telescopic assembly, the lower end of the vertical lifting assembly being fixedly connected to the base (1), the first end of the horizontal telescopic assembly being fixedly connected to the lifting end of the vertical lifting assembly, and the connector (14) being connected to the second end of the horizontal telescopic assembly.

9. A neutron flux detection device for a zero power reactor according to claim 8, characterized in that: The vertical lifting assembly comprises: A lifting frame (2) is arranged vertically, and the lower end of the lifting frame (2) is fixedly connected to the base (1); A lifting arm (17) which is slidably connected to the lifting frame (2) up and down; A pulley block (6) arranged at the upper end of the lifting frame (2); A drum (3) and a steel rope (5), wherein the steel rope (5) is wound around the drum (3), and the free end of the steel rope (5) passes around the pulley block (6) and is fixedly connected to the lifting arm (17), and the drum (3) is driven to rotate by a lifting motor (4).

10. A neutron flux detection device for a zero power reactor according to claim 9, characterized in that: The horizontal telescopic component comprises: An outer cylinder (9), one end of which is fixedly connected to the lifting arm (17), and the outer cylinder (9) is provided with a slot (11) along its axial direction; an inner cylinder (10) arranged inside the outer cylinder (9), and the inner cylinder (10) is provided with a through hole adapted to the slot (11), and the inner cylinder (10) slides in an axial direction relative to the outer cylinder (9); A locking nut (12) passes through the slot (11) and the through hole, and the locking nut (12) applies a pre-tightening force to the outer cylinder (9) and the inner cylinder (10).

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