Automatic Calibration Method for Consistency of Detector Arrays in Nuclear Fuel Rod Detection Systems

Abstract

The present invention relates to the technical field of detector consistency calibration, and particularly to an automatic calibration method for the consistency of a detector array in a nuclear fuel rod detection system. In view of the fact that the current detection of nuclear fuel rods requires manual calibration, which has low work efficiency and inaccurate manual calibration, the following solutions are proposed, including the following steps: detector gating, PID adaptive calibration. The purpose of the present invention is to improve work efficiency and the accuracy of detector calibration through the automatic calibration of the nuclear fuel rod detector array, and to provide an accurate detector output signal for the detection of the enrichment degree of nuclear fuel rods.

Description

Technical Field

[0001] The present invention relates to the technical field of automatic calibration of detectors, and particularly to a method for automatically calibrating the consistency of a detector array in a nuclear fuel rod detection system. Background Art

[0002] In the currently used nuclear fuel rod detection system, due to the inconsistency of the performance parameters of each detector, such as the circuit parameters of the amplifier circuit being inconsistent, the supply voltage of the detector being inconsistent, and the detection efficiency of the detector being different, etc., even when the set parameters of each part are theoretically the same, there is still a situation where the energy spectrum full-energy peak channel addresses of the nuclear pulse signals output by each detector are inconsistent, resulting in a counting rate error and inaccurate nuclear fuel rod detection. Therefore, before each detection by the detection personnel, it is necessary to manually calibrate the consistency of the detector array, and the work efficiency is low. Therefore, we propose a method for automatically calibrating the consistency of a detector array in a nuclear fuel rod detection system. Summary of the Invention

[0003] The purpose of the present invention is to solve the problems that all detectors in the existing nuclear fuel rod detection system need to be manually calibrated for consistency, with low work efficiency and low accuracy of manual calibration, and to propose a new method for automatically calibrating the consistency of a nuclear detector array.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for automatically calibrating the consistency of a detector array in a nuclear fuel rod detection system includes the following steps:

[0006] Detector gating: Since the nuclear fuel rod detection system needs to use a group of detectors to form a detector array simultaneously, it is necessary to calibrate all detectors in the detector array before nuclear fuel rod detection. The automatic calibrator sequentially gates one detector at a time to output a nuclear pulse signal to a multi-channel pulse amplitude analyzer for signal amplitude analysis, and the energy spectrum is displayed on the PC host computer to obtain the full-energy peak peak channel address;

[0007] PID Adaptive Calibration: First, obtain the reference full-energy peak channel address based on the nuclear pulse signal output by the reference standard detector, and calculate the amplifier feedback resistance value to be set. Then, through the digital control analog electronic switch in the automatic calibrator, select a nuclear pulse signal output by a detector to be calibrated and send it to the multi-channel pulse amplitude analyzer. Read the full-energy peak channel address of the signal output by the detector to be calibrated through the upper computer software of the multi-channel pulse amplitude analyzer, compare it with the reference standard full-energy peak channel address, calculate the difference e between the two channel addresses, and then adjust the feedback resistance value in the detector preamplifier circuit through the PID adaptive calibration method, so as to adjust the corresponding energy spectrum peak value of the detector output signal. After several cycles of calibration, until the full-energy peak channel address of the nuclear pulse signal output by the detector to be calibrated in this path is consistent with the reference standard channel address, thus completing the calibration process of one detector. Then, select the next detector to be calibrated through the digital control analog electronic switch in the automatic calibrator and perform the calibration of the next detector. Through this method, complete the calibration of all detectors in the detector array.

[0008] Preferably, during the detector selection process, the automatic calibrator sequentially selects the nuclear pulse signal output by one of the detectors through the digital control analog electronic switch and sends it to the multi-channel pulse amplitude analyzer for signal amplitude analysis, and displays the energy spectrum on the PC upper computer to obtain the full-energy peak channel address;

[0009] Preferably, during the PID adaptive calibration process, calculate the voltage magnitude to be adjusted according to the formula, and the calculation formula is:

[0010]

[0011] And obtain the feedback resistance change according to the gain of the preamplifier. The relationship between the feedback resistance and the output voltage is as follows:

[0012]

[0013] In the above formula, U i is the input voltage at the front end of the amplifier. By adjusting the amplifier feedback resistance R f obtain the amplifier output voltage U 0 corresponding to the standard energy spectrum peak address, thus completing the automatic calibration function of the detector array;

[0014] Preferably, during the PID adaptive calibration process, according to the formula:

[0015]

[0016] Obtain the ratio of the adjusted preamplifier output voltage to the standard preamplifier output voltage as follows:

[0017]

[0018] In actual detection, due to the inconsistency of the performance parameters of various parts in the detector, such as the inconsistency of the circuit parameters of the amplifier circuit and the different detection efficiencies of the detector, etc., even when the theoretically set parameters of each part module are the same, the energy spectrum full-energy peak channel addresses of the output nuclear pulse signals still vary. It is necessary to correct through the PID control method to achieve the automatic calibration function of the detector array.

[0019] Preferably, during the PID adaptive calibration process, single-neuron PID control is adopted to achieve the automatic calibration function of the automatic calibrator. Mark the full-energy peak peak channel address of the nuclear pulse signal output by the detector to be calibrated as N 1 , and the reference full-energy peak peak channel address obtained from the nuclear pulse signal output by the reference standard detector is N 2 . Then, the single-chip microcomputer in the automatic calibrator performs single-neuron PID control on the feedback resistor R f of the detector to be calibrated to make N 1 = N 2 , and the specific method is as follows:

[0020] First, according to marking the full-energy peak peak channel address of the nuclear pulse signal output by the detector to be calibrated as N 1 and the reference full-energy peak peak channel address obtained from the nuclear pulse signal output by the reference standard detector as N 2 , the state variables x 1 , x 2 , x 3 required for neuron learning are obtained through the single-chip microcomputer;

[0021]

[0022] In the above formula: e(k) = N 2 - N 1 .

[0023] The signal u(k) transmitted by the single-chip microcomputer to the digital potentiometer in the feedback circuit of the detector preamplifier at time k:

[0024]

[0025]

[0026] In the above formula: ω i (k) is the weight coefficient corresponding to x i (k); K is the neuron gain coefficient, and K > 0.

[0027] The key to realizing adaptive control by single-neuron PID control lies in that the controller can autonomously learn and online adjust the weighting coefficients ω iThe value is equivalent to an adaptive adjustment of the control strengths of the proportional, integral, and derivative links of the PID. In this design, a supervised Hebb learning rule is adopted, and the specific learning rule is as follows:

[0028]

[0029] In the above formula: η i is the integral learning rate; η p is the proportional learning rate; η d is the derivative learning rate.

[0030] Considering that the online learning of the PID parameters during the control process is mainly related to e(k) and Δe(k), the weighted coefficient learning rule is optimized, and x i (k) is replaced with e(k) + Δe(k):

[0031]

[0032] In the above formula, Δe(k) = e(k) - e(k - 1).

[0033] According to the signal u(k) transmitted by the single-chip microcomputer to the digital potentiometer in the feedback circuit of the detector preamplifier at the kth moment input by the single-neuron PID controller, the size of the feedback resistor R f is adjusted until N 1 = N 2 completes the calibration.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] 1. Changing manual calibration to automatic calibration reduces labor costs, reduces harm to operators, reduces calibration time, and improves work efficiency.

[0036] 2. By realizing the automatic calibration of the detector array of the nuclear fuel rod detector, the calibration accuracy of the detector is improved compared with manual calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a flowchart of the method for automatically calibrating the consistency of the detector array of the nuclear fuel rod detection system proposed by the present invention.

[0038] Figure 2 is a flowchart of the operation of the automatic calibrator proposed by the present invention.

[0039] Figure 3 is the calibration process of the automatic calibrator in the present invention. Among them, N1 is the full-energy peak channel address of the energy spectrum obtained by using the detector to be calibrated; N2 is the reference standard full-energy peak channel address; Rf is the feedback resistor of the amplifier of the detector to be calibrated.

[0040] Figure 4 This is the circuit diagram of the preamplifier in the present invention.

[0041] Figure 5 This is the detailed structure diagram of the present invention.

[0042] Figure 6 This is the flow chart of single neuron PID control.

Claims

1. Automatic calibration method for detector array consistency in nuclear fuel rod detection system, Characterized in that, It includes the following steps: Detector gating: Since a nuclear fuel rod detection system needs to use a group of detectors to form a detector array simultaneously, before nuclear fuel rod detection, it is necessary to perform consistency calibration on all detectors in the detector array. The automatic calibrator needs to sequentially gate the nuclear pulse signals output by one of the detectors to the multi-channel pulse amplitude analyzer through a numerically controlled analog electronic switch for signal amplitude analysis, display the energy spectrum on the PC host computer to obtain the full-energy peak channel address, and then achieve the consistency calibration of this detector; PID adaptive calibration: First, obtain the reference full-energy peak channel address based on the nuclear pulse signals output by the reference standard detector. Then, gate the nuclear pulse signals output by one detector to be calibrated to the multi-channel pulse amplitude analyzer, compare the peak channel address of the full-energy peak of the energy spectrum corresponding to this nuclear pulse signal with the reference channel address number to obtain the channel address difference e. Then, adjust the feedback resistance value in the detector preamplifier circuit through the PID adaptive calibration method, so as to adjust the peak channel address of the energy spectrum corresponding to the detector output signal. After several cycles of calibration, until the full-energy peak channel address of the energy spectrum of the nuclear pulse signals output by this detector to be calibrated is consistent with the reference standard channel address, thus completing the calibration process of one detector; In the above-mentioned PID adaptive calibration, first obtain the reference full-energy peak channel address based on the nuclear pulse signals output by the reference standard detector, and calculate the feedback resistance value of the amplifier to be set; then, through the numerically controlled analog electronic switch in the automatic calibrator, gate the nuclear pulse signals output by one detector to be calibrated to the multi-channel pulse amplitude analyzer, read the full-energy peak channel address of the energy spectrum of the output signal of the detector to be calibrated through the upper computer software of the multi-channel pulse amplitude analyzer, compare it with the reference standard full-energy peak channel address, calculate the difference e between the two channel addresses, and then adjust the feedback resistance value in the detector preamplifier circuit through the PID adaptive calibration method, so as to adjust the peak value of the energy spectrum corresponding to the detector output signal. After several cycles of calibration, until the full-energy peak channel address of the energy spectrum of the nuclear pulse signals output by this detector to be calibrated is consistent with the reference standard channel address, thus completing the calibration process of one detector. Then, through the numerically controlled analog electronic switch in the automatic calibrator, gate the next detector to be calibrated to perform the calibration of the next detector. By this method, the calibration of all detectors in the detector array is completed; Calculate the magnitude of the voltage to be adjusted according to the formula, where the calculation formula is: And obtain the change of the feedback resistance according to the gain of the preamplifier. The relationship between the feedback resistance and the output voltage is as follows: In the above formula, U i is the input voltage at the front end of the amplifier. By adjusting the feedback resistor R f of the amplifier, the output voltage U 0 of the amplifier corresponding to the peak channel address of the standard energy spectrum full energy peak is obtained, thereby completing the automatic calibration function of the detector array; According to the formula: Obtain the ratio of the output voltage of the preamplifier before adjustment to the output voltage of the standard preamplifier as follows: In actual detection, due to the inconsistency of the performance parameters of each part of the detector, the circuit parameters of the amplifier circuit, and the different detection efficiencies of the detectors, even when the theoretically set parameters of each part of the module are the same, there will still be different full-energy peak channel addresses of the output nuclear pulse signals, which need to be corrected by the PID control method to achieve the automatic calibration function of the detector array; Implement single neuron PID control through a single-chip microcomputer to achieve the automatic calibration function of the automatic calibrator, and mark the full-energy peak peak channel address of the nuclear pulse signal output by the detector to be calibrated as N 1 , and the reference full-energy peak peak channel address obtained from the nuclear pulse signal output by the reference standard detector is N 2 , and then the feedback resistor R of the detector to be calibrated by the single-chip microcomputer in the automatic calibrator f performs single neuron PID control to make N 1 = N 2 , and the specific method is as follows: First, the full-energy peak peak channel address of the nuclear pulse signal marked by the detector to be calibrated is N 1 and the reference full-energy peak peak channel address obtained from the nuclear pulse signal output by the reference standard detector is N 2 The state quantity x required for neuron learning is obtained through the single-chip microcomputer 1 , x 2 , x 3 ; In the above formula: e(k) = N 2 -N 1 ; The signal u(k) transmitted by the single-chip microcomputer to the digital potentiometer in the feedback circuit of the detector preamplifier at time k: In the above formula: ω i (k) is the weight coefficient corresponding to x i (k); K is the neuron gain coefficient, and K > 0; The key to realizing adaptive control by single neuron PID control lies in that the controller can autonomously learn and online adjust the weighting coefficients ω of each component, which is equivalent to adaptively adjusting the control intensities of the proportional, integral, and differential links of PID. In this design, a supervised Hebb learning rule is adopted, and the specific learning rule is as follows: i The value is equivalent to adaptively adjusting the control intensities of the proportional, integral, and differential links of PID. In this design, a supervised Hebb learning rule is adopted, and the specific learning rule is as follows: In the above formula: η i is the integral learning rate; η p is the proportional learning rate; η d is the differential learning rate; Considering that the online learning of PID parameters in the control process is mainly related to e(k) and Δe(k), the learning rule of the weighting coefficient is optimized, and x i (k) is replaced by e(k) + Δe(k): In the above formula, Δe(k) = e(k) - e(k - 1); Adjust the magnitude of the feedback resistor R according to the signal u(k) transmitted by the single-chip microcomputer to the digital potentiometer in the feedback circuit of the detector preamplifier at the k-th moment input by the single-neuron PID controller f until N 1 = N 2 to complete the calibration.

2. The automatic calibration method for the detector array consistency of the nuclear fuel rod detection system according to claim 1, characterized in that in the detector signal gating, a numerically controlled analog electronic switch is used to gate the detector, and the nuclear pulse signal of the gated detector is transmitted to a multi-channel pulse amplitude analyzer for energy spectrum display, and the channel address number corresponding to the full energy peak of the energy spectrum of the nuclear pulse signal output by the detector is obtained.

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