A neutron flux probe and neutron flux probe device for a zero power reactor

Abstract

The application belongs to the technical field of reactor physics test and measurement, and particularly relates to a neutron flux detector and a neutron flux detection device for a zero-power reactor. The neutron flux detector comprises a CLYC scintillator, a reflection layer, a photoelectric conversion multiplier device and front-end electronics. The photoelectric conversion multiplier device is attached to one side of the scintillator, the reflection layer is attached to the remaining side of the CLYC scintillator, and the photoelectric conversion multiplier device is electrically connected to the front-end electronics. The detection device comprises a neutron flux detector, a multi-channel data acquisition system, a connector and a lifting device. The application realizes efficient online measurement of neutron flux in a zero-power reactor environment, overcomes the limitations of traditional methods relying on offline measurement, and based on the miniaturized design of the CLYC crystal and the tungsten alloy shielding structure, the detector has excellent thermal neutron response capability and is suitable for the complex high-gamma background environment of the reactor.

Description

Technical Field

[0001] The present 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 tests are a fundamental topic in reactor physics research. Accurately measuring the neutron flux distribution in the reactor core is a prerequisite for ensuring safe and effective reactor operation. Not only are the spatial distribution of the neutron flux in the reactor itself closely related to technical aspects such as the coolant flow arrangement and the operational safety limits of nuclear fuel elements, but the neutron flux distribution in the reactor also provides parameters for reactor design and safe operation. For example, to increase the average power density in the core, the neutron flux distribution in the core needs to be flattened as much as possible. Verifying this flattening requires direct measurement.

[0003] Currently, the main methods used to measure reactor neutron flux distribution include activation, nuclear fission, and self-powered detectors. For zero-power reactors, due to their very low flux levels, nuclear fission and self-powered detectors cannot generate sufficient signal strength. Consequently, radiation intensity is relatively low, and radioactivity levels can quickly return to background levels after shutdown. 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 and 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. 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 includes a neutron flux detector, a multi-channel data acquisition system, a connector, and a lifting device. 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. 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 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 assembly, 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 axis;

[0023] an inner cylinder, which is arranged in the outer cylinder and 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 mainly consists 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 is connected to a lifting device to achieve real-time measurement of the axial and radial neutron fluxes in the core.

[0027] This invention achieves efficient online measurement of neutron flux in a zero-power reactor environment, overcoming the limitations of traditional methods that rely on offline measurements. Furthermore, thanks to the miniaturized design of the CLYC crystal and its tungsten alloy shielding structure, the detector exhibits excellent thermal neutron response, making it suitable for the complex, high-gamma-ray background environment of a reactor. Furthermore, the use of a multi-channel data acquisition system enables the detector to accurately transmit nuclear pulse signals in real time, 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 structural schematic 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 This is a hardware block diagram of the overall design of the multi-channel data acquisition system according to the present invention.

[0032] Figure 4 2 is a schematic structural diagram of the mounting bracket according to the present invention.

[0033] Figure 5 2 is a schematic structural diagram of a 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-reflective layer, 23-photoelectric conversion multiplier device, 24-front-end electronics, 25-housing. DETAILED DESCRIPTION

[0037] To make the purpose, technical solutions 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 embodiments. It should be understood that the specific embodiments described herein are only used to explain the relevant content and are not intended 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 can 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] Example 1

[0041] CLYC neutron detectors are typically used for space neutron detection. However, research has found that in reactors, even at zero power, the neutron flux is several orders of magnitude higher than that of space neutrons, and is accompanied by a large number of gamma rays. High neutron flux density and strong gamma radiation fields can lead to severe CLYC pulse signal accumulation, resulting in a decrease in the effective pulse count rate, an increase in dead time, and reduced energy resolution. Therefore, it is necessary to reduce the thermal neutron detection efficiency through the design of the CLYC crystal and to add gamma ray shielding to alleviate the pulse pileup 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. 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.

[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 improve the upper limit of the thermal neutron flux measurement of the detector. Therefore, CLYC scintillator 21 adopts nat Li-CLYC crystal.

[0044] Common gamma-ray shielding materials include lead, tungsten, and bismuth. Tungsten alloys offer superior gamma-ray shielding capabilities compared to lead and bismuth, possess high mechanical strength, and are non-toxic and environmentally friendly. In this embodiment, a tungsten alloy shield is added to the exterior of the CLYC crystal to reduce gamma-ray interference with neutron detection. Specifically, the reflective layer 22 is constructed of a tungsten alloy shield. Laminating the reflective layer 22 to the side of the CLYC scintillator 21 not bonded to the optoelectronic device further enhances directional neutron signal collection and the signal-to-noise ratio.

[0045] At the same time, in order to adapt to the miniaturization of the reactor, the size of the CLYC scintillator 21 is φ3mm*3mm.

[0046] The photoelectric multiplier (SiPM) 23 converts the weak optical signal generated by the scintillator into an electrical signal. Composed of multiple microphotodiodes, the SiPM offers extremely high gain, making it suitable for detecting low-light signals. The SiPM adheres to one side of the CLYC scintillator 21, effectively collecting the optical signal and converting it into an electrical signal, which is then output to the subsequent front-end electronics 24 module.

[0047] Neutrons react with the CLYC scintillator 21, generating alpha particles and tritium nuclei, generating a light signal. This light signal is captured by the SiPM attached to one side of the scintillator and converted into an electrical signal. The reflective layer 22 reduces interference from background gamma rays on the scintillator, ensuring a purer light signal from the neutrons. The SiPM converts the light signal into an electrical signal and amplifies it for output. The front-end electronics 24 then further amplifies and stabilizes the electrical signal.

[0048] Example 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] An external power supply is used to power the SiPM and preamplifier. The optical signal is converted into a current signal by the SiPM array. The preamplifier then undergoes I / V conversion and preliminary amplification to output an analog signal to the acquisition system. Because SiPM gain has a linear relationship with temperature, changes in the measurement environment temperature can cause the peak position of the detector output spectrum to shift. To minimize the impact of temperature on detector performance, bias temperature compensation is implemented for the SiPM gain. When the temperature changes, the SiPM bias voltage is adjusted to adjust the gain.

[0051] The SiPM power supply module provides a stable bias voltage for the SiPM, ensuring its proper operation. Because the SiPM's gain is proportional to the supply voltage, its performance fluctuates with changes in the supply voltage. Therefore, the SiPM power supply module utilizes a high-precision voltage stabilization circuit that fine-tunes the voltage based on the detector's actual operating environment. This ensures stable gain under varying ambient temperatures and power supply fluctuations, thereby guaranteeing accurate and reliable neutron flux detection.

[0052] The op-amp 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 op-amp power supply module adopts a low-noise, voltage-stabilized design, which reduces the impact of power supply ripple and noise on the op-amp 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 op-amp power supply module, so that the op-amp power supply module can also work stably within a wide voltage range.

[0053] The gain of the SiPM fluctuates with temperature, so a temperature feedback module has been added to the detector. The temperature feedback module monitors the ambient temperature around the SiPM in real time and feeds the temperature signal back to the control system, automatically adjusting the SiPM's bias voltage to compensate for gain fluctuations caused by temperature changes. Specifically, when the temperature rises, the SiPM's gain decreases, at which point the temperature feedback module increases the bias voltage to boost the gain. Conversely, when the temperature drops, the module decreases the bias voltage to prevent excessive gain. The use of the temperature feedback module ensures the stability of the detector under different temperature conditions, allowing the electrical signal output by the SiPM to always remain within the set range, thereby improving measurement accuracy.

[0054] The signal preamplifier module is responsible for the initial 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 often very weak, and direct transmission to the data acquisition system will result in a decrease in signal quality. Therefore, 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 enclosed in a sealed aluminum alloy housing 25. This housing features high mechanical strength, radiation resistance, and corrosion resistance, providing essential physical protection for the detector. The housing's diameter is smaller than the diameter of the reactor core's through-hole, allowing for flexible movement within the core to meet neutron flux measurement requirements at various locations. Furthermore, the aluminum alloy housing's sealing ensures that internal components are protected from contamination and damage from the external environment, contributing to the overall lifespan and stability of the detector.

[0057] Furthermore, to facilitate installation of the entire device, housing 25 can be divided into an end cap, an uncovered housing, and a sealing ring. After the remaining components are placed within the uncovered housing, housing 25 is sealed with the end cap and sealing ring. Furthermore, a cable lead-out port for the PCB is provided on the end cap to facilitate external electrical connection of the entire neutron flux detector.

[0058] Example 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. The connector 14 is fixedly connected to the lifting end of the lifting device. Multiple neutron flux detectors are installed on the connector 14 and correspond to multiple reactor core through holes. 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.

[0060] Neutron flux detectors are responsible for capturing neutron flux signals within the reactor core. Multiple detectors are installed at locations corresponding to various core apertures, ensuring neutron flux data can be collected from various locations. Using photomultiplier technology and front-end electronics, the detectors convert captured neutron flux signals into electrical signals, providing the raw 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. Featuring high-precision and high-speed pulse signal processing, the system digitizes and stores the electrical signals generated by the detectors for subsequent analysis. Multiple signal inputs are electrically connected to the signal outputs of each neutron flux detector, enabling parallel acquisition of neutron flux data at different locations, thus supporting real-time monitoring of multiple points within the core.

[0062] The cooperation between 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] Example 4

[0064] The multi-channel data acquisition system in this embodiment is used to accurately collect, transmit, and process high-speed nuclear pulse signals captured by the detectors. The system boasts a high sampling rate and high precision, supporting the simultaneous acquisition and real-time monitoring of multi-channel signals. This ensures the accuracy and stability of measurement data even in low-flux, zero-power reactor environments. Specifically, the multi-channel data acquisition system in this invention is constructed based on a high-sampling-rate ADC (analog-to-digital converter) and an FPGA (field-programmable gate array). The data acquisition system achieves a sampling rate of 250 MSPS and a sampling accuracy of 14 bits. By sampling each detector signal at high speed, even subtle changes in the nuclear pulse signals can 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 utilizes CAEN's DT5725 module, enabling simultaneous multi-channel data acquisition. The DT5725 module integrates a high-precision ADC and a programmable FPGA control module, enabling real-time sampling and processing of the output signals from each neutron flux detector. This module not only performs pulse waveform recognition on gamma-neutron signals but also features amplitude analysis, zero-length encoding, and dynamic acquisition windowing, making data processing more flexible and efficient. Furthermore, the module's firmware supports an n / gamma discrimination algorithm, which classifies various nuclear pulse signals by identifying differences in the pulse waveforms of gamma and neutron signals, effectively improving the accuracy of neutron and gamma-ray signal discrimination.

[0066] A 250MHz high-speed continuous sampling ADC is used for data processing, and a high-speed FPGA is used for trapezoidal digital filtering to obtain the energy spectra of gamma and neutron signals. The device's DPP-PSD firmware is used for n / gamma discrimination. The system utilizes a digital delay circuit, digital constant ratio timing, and digital TDC generated by a high-speed FPGA. Compared to traditional solutions, this fully digital design offers more flexible parameter adjustment and a more compact design.

[0067] In the multi-channel data acquisition system, the raw analog signals collected by the high-speed ADC are converted to digital signals in real time, followed by complex digital signal processing using an FPGA. In particular, a trapezoidal digital filtering algorithm is applied during this processing to ensure a clearer energy spectrum for the gamma and neutron signals. This filtering algorithm effectively suppresses high-frequency noise in the signal while maintaining signal stability and accuracy, making the detector's response to neutron flux more sensitive and reliable in complex radiation field environments. Compared to traditional analog signal processing, digital filtering offers the advantages of more flexible parameter adjustment and significant system miniaturization.

[0068] In the multi-channel data acquisition system of this invention, n / γ signal discrimination is a key step in ensuring 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 acquired signals to distinguish gamma-ray and neutron signals. Compared to traditional signal discrimination schemes, this digital processing method enables more efficient signal screening and classification, especially in complex reactor environments with high gamma background, ensuring accurate discrimination of neutron signals.

[0069] After signal processing, the digitized nuclear pulse signal is transmitted in real time to a data storage unit 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 enables the parallel transmission of multi-channel signals, ensuring that detector signals are stored and read without distortion.

[0070] Example 5

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

[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] Connecting rods are used to mount neutron flux detectors at their lower ends, while their upper ends connect to mounting brackets, securing each detector in its specific position. The connecting rods are designed with a hollow aluminum alloy structure to facilitate internal wiring. The hollow portion of each connecting rod accommodates the signal transmission cable from the detector to the multi-channel data acquisition system, reducing the possibility of external interference. Available lengths include 60cm, 80cm, 100cm, and 120cm.

[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. The lifting device 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, usually fixed to one side of the reactor, 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 set 6, a drum 3 and a steel rope 5. The lifting frame 2 is arranged vertically, 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 up and down sliding; the pulley set 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 around the pulley set 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 lift assembly controls the rotation of the drum 3 via the lift motor 4, driving the steel rope 5 up and down, causing the lift arm 17 to slide up and down along the lift frame 2 to adjust the detector's height. The horizontal telescopic assembly adjusts the detector's lateral position through the relative sliding of the outer and inner cylinders 9 and 10. When in the target position, the lock nut 12 applies a preload to the inner and outer cylinders 9 to ensure position stability.

[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, thereby preventing 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" 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 expressions 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 an appropriate manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine different embodiments / methods or examples described in this specification and the features of different embodiments / methods or examples, unless they are contradictory.

[0081] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0082] It should be understood by those skilled in the art that the above embodiments are merely for the purpose of illustrating the present invention clearly, 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); The CLYC scintillator (21) adopts nat Li-CLYC crystal, the reflective layer (22) adopts a tungsten alloy shielding layer.

2. A neutron flux detector for a zero-power reactor according to claim 1, characterized in that: The size of the CLYC scintillator (21) is φ3mm*3mm.

3. A neutron flux detector for a zero-power reactor according to claim 2, characterized in that: The front-end electronics (24) includes: 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.

4. A neutron flux detector for a zero-power reactor according to claim 1, characterized in that: It also includes 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.

5. A neutron flux detection device for a zero-power reactor, characterized in that: The invention comprises a neutron flux detector according to any one of claims 1 to 4, 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 the 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 all electrically connected to the signal input ends of the multi-channel data acquisition system.

6. The neutron flux detection device for a zero-power reactor according to claim 5, 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 cable between the multi-channel data acquisition system and the neutron flux detector is arranged in the connecting rod.

7. The neutron flux detection device for a zero-power reactor according to claim 5, characterized in that: The lifting device comprises: a base (1), a vertical lifting assembly and a horizontal telescopic assembly, wherein 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.

8. The neutron flux detection device for a zero-power reactor according to claim 7, characterized in that: The vertical lifting assembly includes: 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) slidably connected to the lifting frame (2) in an up-and-down manner; A pulley assembly (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 on the drum (3), and the free end of the steel rope (5) is passed around the pulley block (6) and fixedly connected to the lifting arm (17), and the drum (3) is driven to rotate by the lifting motor (4).

9. The neutron flux detection device for a zero-power reactor according to claim 8, characterized in that: The horizontal telescopic component includes: An outer cylinder (9), one end of which is fixedly connected to the lifting arm (17), and a slot (11) is provided on the outer cylinder (9) along its axial direction; an inner cylinder (10) disposed in the outer cylinder (9), and provided with a through hole adapted to the slot (11), the inner cylinder (10) sliding 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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