Neutron noise signal-based abnormal vibration control rod positioning method and system, and medium

Abstract

The invention discloses an abnormal vibration control rod positioning method and system based on neutron noise signals and a medium. Relates to the technical field of control rod monitoring. According to neutron noise signal data measured by a self-powered neutron detector, whether the control rod has abnormal vibration or not is evaluated, and the cause of the abnormal vibration is determined; then calculating a transfer function between the control rod and a neutron detector by using a neutron transport equation, and determining the position of the control rod with abnormal vibration through a minimization algorithm theory; the problem that abnormal vibration of the in-reactor control rod cannot be monitored is solved, abnormal vibration of the control rod is avoided, and safety and reliability of the reactor control rod are powerfully guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of control rod monitoring, and in particular to a method, system and medium for positioning an abnormally vibrating control rod based on a neutron noise signal. Background Art

[0002] The control rod is an important part of the internal components of a nuclear power plant. It is also one of the important components for controlling the reactor power and the reactivity of the reactor core. It is an important safety facility to ensure that the reactor can safely enter the shutdown state under accident conditions. The reliability of its function is an important condition for ensuring the safe operation of nuclear power plants and the stable operation of nuclear submarines. In recent years, some cases of control rod drive mechanism failures have occurred in various types of reactors at home and abroad, including control rod jamming, component wear, pitting, abnormal rod drop and other failures, which have buried major safety hazards for the normal operation of the reactor. In 1985, abnormal vibration of the No. 4 control rod was discovered in the Paks-2 pressurized water reactor in Hungary.

[0003] Since the control rods are located inside the reactor, the surrounding radioactivity is high and the space is small, it is impossible to arrange vibration detectors inside the reactor to detect the vibration state of the control rods. As an important means of measuring core power and thermal hydraulic parameters, the self-powered detector is not only sensitive to thermal hydraulic phenomena (standing acoustic waves, coolant boiling, and transportation of temperature fluctuations at the coolant speed from the reactor inlet), but also sensitive to mechanical vibration phenomena (vibration of pressure vessels, core baskets, and control rods), and can effectively detect abnormal vibrations of control rods. Summary of the invention

[0004] The technical problem to be solved by the present invention is that the control rod is located in the reactor core, the surrounding radioactive activity is high, and the space is small, so it is impossible to arrange a vibration detector in the reactor to detect the vibration state of the control rod; the purpose of the present invention is to provide an abnormal vibration control rod positioning method, system and medium based on neutron noise signals, by arranging multiple self-powered neutron detectors in the reactor to monitor neutron noise signal data, and judging whether the control rod has abnormal vibration based on the neutron noise signal data, combining the neutron transport equation to construct the transfer function between the control rod and the self-powered neutron detector, and determining the position of the abnormal vibration control rod with the minimization algorithm theory; the problem that the abnormal vibration of the control rod in the reactor cannot be monitored is solved, the abnormal vibration of the control rod is avoided, and the safety and reliability of the reactor control rod is effectively guaranteed.

[0005] The present invention is achieved through the following technical solutions:

[0006] This solution provides a method for locating abnormal vibration control rods based on neutron noise signals, including:

[0007] Arrange a plurality of self-powered neutron detectors in the reactor to collect neutron noise signal data measured by the respective powered neutron detectors;

[0008] Preprocessing the neutron noise signal data;

[0009] Judging whether there is abnormal vibration of the control rod based on the preprocessed neutron noise signal data;

[0010] The transfer function between the control rod and the self-powered neutron detector is constructed based on the neutron transport equation;

[0011] The position of abnormally vibrating control rod is determined based on the minimization algorithm theory and the transfer function between the control rod and the self-powered neutron detector.

[0012] Working principle of this scheme: the control rod is located in the reactor core, the surrounding radioactive activity is high, and the space is small, so it is impossible to arrange a vibration detector in the reactor to detect the vibration state of the control rod; the purpose of the present invention is to provide an abnormal vibration control rod positioning method, system and medium based on neutron noise signals, by arranging multiple self-powered neutron detectors in the reactor to monitor neutron noise signal data, and judging whether the control rod has abnormal vibration based on the neutron noise signal data, combining the neutron transport equation to construct the transfer function between the control rod and the self-powered neutron detector, and determining the position of the abnormal vibration control rod with the minimization algorithm theory; solves the problem that the abnormal vibration of the control rod in the reactor cannot be monitored, avoids the abnormal vibration of the control rod, and effectively guarantees the safety and reliability of the reactor control rod.

[0013] A further optimization scheme is that the multiple self-powered neutron detectors are arranged in the reactor, including the following method:

[0014] The first control rod assembly and the second control rod assembly are determined according to condition a; condition a: there is no control rod assembly around the first control rod assembly or the first control rod assembly is the second control rod assembly;

[0015] A plurality of self-powered neutron detectors are arranged at a central position of the first control rod assembly and at equal depth intervals along a control rod insertion direction.

[0016] A further optimization solution is that the neutron noise signal data includes neutron current signal noise data.

[0017] The specific neutron noise signal data δφ(r,t) is:

[0018] δφ(r,t)=cδi(r,t)=c[i(r,t)-E(i(r,t))]

[0019] Wherein, δi(r,t) represents the neutron current signal noise data; E(·) represents the time-scale mean of the signal; i(r,t) represents the neutron current signal; r represents the position of the core; t represents time; c represents the linear conversion coefficient of the self-powered neutron detector; it is obtained according to the characteristics of the self-powered detector for collecting neutron noise signals.

[0020] A further optimization scheme is that the neutron noise signal data is preprocessed, including the method:

[0021] Separating an AC signal and a DC signal from the neutron noise signal data, and amplifying the AC signal;

[0022] The DC signal and the amplified AC signal are sampled respectively, and the amplified AC signal is filtered to obtain a first AC signal;

[0023] The first AC signal is divided by the DC signal.

[0024] A further optimization scheme is that the method of judging whether the control rod has abnormal vibration based on the preprocessed neutron noise signal data includes:

[0025] Obtain neutron noise signals of different self-powered detectors deployed at the same depth;

[0026] Calculate the cross-correlation function between self-powered detectors at the same depth based on neutron noise signals;

[0027] Determine whether the control rod has abnormal vibration based on the cross-correlation function:

[0028] Obtain the natural frequency of each control rod;

[0029] At the natural frequency of the control rod, a cross-correlation threshold is preset, and when the cross-correlation function is greater than the cross-correlation threshold, it is determined that an abnormality exists in the control rod.

[0030] A further optimization scheme is that the cross-correlation function between self-powered detectors at the same depth is calculated based on the neutron noise signal, including the following method:

[0031] The cross-correlation function R(r,ω) between the self-powered detector x and the self-powered detector y at depth z is:

[0032]

[0033] In the formula, S xx (r,ω) represents the power spectrum density of the self-powered detector x at depth z; S yy (r,ω) represents the power spectrum density of the self-powered detector y at depth S; S xy(r, ω) represents the cross power spectrum density of the self-powered detector x and the self-powered detector y at depth z; r represents the position of the self-powered neutron detector, and ω represents the circular frequency of the neutron noise signal.

[0034] A further optimization scheme is that the transfer function between the control rod and the self-powered neutron detector is constructed based on the neutron transport equation; including the method:

[0035] Based on neutron transport theory, the neutron noise equation caused by the fluctuation of the absorption cross section is:

[0036]

[0037] Where L is an operator defined on the Hilbert space, S(r,ω) is the disturbance source caused by the control rod vibration, and D is the neutron diffusion coefficient; δφ(r,ω) represents the collected neutron noise signal; r represents the position of the self-powered neutron detector, and ω represents the circular frequency of the neutron noise signal;

[0038] Based on the Green's function theory, the Green's function solution G(r,r′,ω) of the neutron noise equation is the transfer function between the control rod vibration and the neutron flux at the neutron detector:

[0039] δφ(r,ω)=∫G(r,r′,ω)S(r′,ω)dr′

[0040] Where r′ represents the position of the control rod; S(r′,ω) represents the disturbance source caused by the vibration of the control rod;

[0041] A further optimization scheme is that the position of the abnormally vibrating control rod is determined based on the minimization algorithm theory and the transfer function between the control rod and the self-powered neutron detector, including the following method:

[0042] Acquire basic evaluation data, the basic evaluation data including: self-power spectrum density of self-powered detector i, self-powered detector j, and self-powered detector k at depth S; mutual power spectrum density between self-powered detector i, self-powered detector j, and self-powered detector k; and transfer functions of different abnormal vibration control rods to self-powered detector i, self-powered detector j, and self-powered detector k; i≠j≠k;

[0043] Calculate the evaluation function Δ(r) based on the evaluation basic data:

[0044]

[0045] In the formula, G ij (r p ) represents the transfer function between the self-powered detector i and the self-powered detector j; G jk (r p) represents the transfer function between the self-powered detector i and the self-powered detector k; Represents G ij (r p ) inverse operator; Represents G jk (r p ) inverse operator; Represents G ij (r p )’s adjoint operator; Represents G jk (r p ) is the inverse operator of the adjoint operator; S ij represents the neutron noise spectrum matrix of self-powered detector i and self-powered detector j; S jk represents the neutron noise spectrum matrix of self-powered detector j and self-powered detector k; r p represents the position of the control rod p; r p ={x p ,y p};

[0046] in,

[0047]

[0048] In the formula, represents the self-power spectral density of the self-powered detector i; represents the self-power spectrum density of the self-powered detector j; represents the cross power spectral density of the self-powered detector j and represents the self-powered detector i; represents the cross power spectral density of the self-powered detector i and the self-powered detector j; φ0(r p ) represents r p Neutron flux level at the location; G(r i ,r p ,ω) represents the Green function solution of the neutron noise equation of the self-powered detector i; G(r j ,r p ,ω) represents the Green’s function solution of the neutron noise equation of the self-powered detector j.

[0049] Take the r with the minimum evaluation function p As abnormal vibration control rod position.

[0050] The present invention also provides an abnormal vibration control rod positioning system based on neutron noise signals, which is used to implement the above-mentioned abnormal vibration control rod positioning method based on neutron noise signals. The system includes:

[0051] An acquisition module is used to arrange multiple self-powered neutron detectors in the reactor and collect neutron noise signal data measured by each powered neutron detector;

[0052] A preprocessing module, used for preprocessing the neutron noise signal data;

[0053] A judgment module, used for judging whether the control rod has abnormal vibration based on the preprocessed neutron noise signal data;

[0054] A construction module for constructing a transfer function between a control rod and a self-powered neutron detector based on a neutron transport equation;

[0055] The positioning module is used to determine the position of the abnormally vibrating control rod based on the minimization algorithm theory and the transfer function between the control rod and the self-powered neutron detector.

[0056] The present solution also provides a computer-readable medium having a computer program stored thereon, and the computer program is executed by a processor to implement the above-mentioned abnormal vibration control rod positioning method based on neutron noise signals.

[0057] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0058] The present invention provides a method, system and medium for positioning an abnormal vibration control rod based on a neutron noise signal. The method evaluates whether the control rod has abnormal vibration based on neutron noise signal data measured by a self-powered neutron detector, and determines the cause of the abnormal vibration. The neutron transport equation is then used to calculate the transfer function between the control rod and the neutron detector, and the position of the control rod having abnormal vibration is determined through a minimization algorithm theory. The problem that abnormal vibration of the control rod in the reactor cannot be monitored is solved, and abnormal vibration of the control rod is avoided, which effectively ensures the safety and reliability of the reactor control rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0060] Figure 1 The figure is a flow chart of a method for locating abnormal vibration control rods based on neutron noise signals;

[0061] Figure 2 This is the structural diagram of the abnormal vibration control rod positioning system based on neutron noise signal;

[0062] Figure 3This is a schematic flow chart of the abnormal vibration control rod positioning method of Example 4. DETAILED DESCRIPTION

[0063] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0064] Since the control rods are located in the reactor, the surrounding radioactivity is high and the space is small, it is impossible to arrange vibration detectors in the reactor to detect the vibration state of the control rods; in view of this, the present invention provides the following embodiments to solve the above technical problems:

[0065] Example 1

[0066] This embodiment provides a method for locating abnormal vibration control rods based on neutron noise signals, such as Figure 1 As shown, including:

[0067] Step 1: deploy multiple self-powered neutron detectors in the reactor and collect neutron noise signal data measured by each powered neutron detector;

[0068] The method of arranging a plurality of self-powered neutron detectors in a reactor includes:

[0069] The first control rod assembly and the second control rod assembly are determined according to condition a; condition a: there is no control rod assembly around the first control rod assembly or the first control rod assembly is the second control rod assembly;

[0070] At the center position of the first control rod assembly, a plurality of self-powered neutron detectors are arranged at equal depth intervals along the control rod insertion direction; as a preferred embodiment, at least 7 self-powered neutron detectors are arranged; the specific control rod assembly is distributed with control rods, stainless steel rods and fuel rods, and the 7 self-powered neutron detectors are evenly installed at different depths of the instrument tube grid element; the control rod assemblies around the first control rod assembly where the self-powered neutron detectors are arranged do not need to be installed with self-powered neutron detectors, so the second control rod assemblies are distributed around the first control rod assembly.

[0071] The neutron noise signal data includes neutron current signal noise data.

[0072] The specific neutron noise signal data δφ(r,t) is:

[0073] δφ(r,t)=cδi(r,t)=c[i(r,t)-E(i(r,t))]

[0074] Wherein, δi(r,t) represents the neutron current signal noise data; E(·) represents the time-scale mean of the signal; i(r,t) represents the neutron current signal; r represents the position of the core; t represents time; c represents the linear conversion coefficient of the self-powered neutron detector; it is obtained according to the characteristics of the self-powered detector for collecting neutron noise signals.

[0075] Step 2: preprocessing the neutron noise signal data; specifically including the following method:

[0076] Separating an AC signal and a DC signal from the neutron noise signal data, and amplifying the AC signal;

[0077] The DC signal and the amplified AC signal are sampled respectively, and the amplified AC signal is filtered to obtain a first AC signal;

[0078] The first AC signal is divided by the DC signal.

[0079] Step 3: judging whether the control rod has abnormal vibration based on the preprocessed neutron noise signal data; the specific method includes:

[0080] S31, obtaining neutron noise signals of different self-powered detectors deployed at the same depth;

[0081] S32, calculating the cross-correlation function between the self-powered detectors at the same depth based on the neutron noise signal;

[0082] The cross-correlation function R(r,ω) between the self-powered detector x and the self-powered detector y at depth z is:

[0083]

[0084] In the formula, S xx (r,ω) represents the power spectrum density of the self-powered detector x at depth z; S yy (r,ω) represents the power spectrum density of the self-powered detector y at depth S; S xy (r, ω) represents the cross power spectrum density of the self-powered detector x and the self-powered detector y at depth z; r represents the position of the self-powered neutron detector, and ω represents the circular frequency of the neutron noise signal.

[0085] S33, judging whether the control rod has abnormal vibration based on the cross-correlation function:

[0086] Obtain the natural frequency of each control rod; in this embodiment, it is 1.1 Hz;

[0087] At the natural frequency of the control rod, the cross-correlation threshold is preset to 0.9, and when the cross-correlation function is greater than the cross-correlation threshold, it is determined that the control rod is abnormal;

[0088] The cross-correlation spectrum of the two detectors at the same height is obtained to exceed the frequency corresponding to the threshold. If the frequency is the natural frequency of the control rod, it is determined that the abnormal vibration of the control rod is caused by the looseness of its own fasteners.

[0089] If the frequency is not the natural frequency of the control rod, then the frequency value is compared with the main pump and other power equipment, turbulent excitation, acoustic standing waves caused by the interaction between the tube bundle and the coolant, and the vibration frequency of the core basket. By analyzing the frequency range of the frequency corresponding to the abnormal cross-correlation function, combined with the amplitude, phase and auto-power spectrum density of the cross-power spectrum density, the cause of the abnormal vibration is determined. For example, if the value near 16Hz is too large, it can be approximately considered that the abnormal forced vibration of the control rod caused by the acoustic standing wave excited by the main pump. At this time, the cause of the abnormality can be further determined by checking the operation of the main pump or the fluid design of the reactor primary circuit.

[0090] Step 4: construct the transfer function between the control rod and the self-powered neutron detector based on the neutron transport equation; the specific method includes:

[0091] S41, based on neutron transport theory, the neutron noise equation caused by the fluctuation of the absorption cross section is:

[0092]

[0093] Where L is the operator defined on the Hilbert space, S(r,ω) is the disturbance source caused by the control rod vibration, D is the neutron diffusion coefficient; δφ(r,ω) is the neutron noise signal acquired;

[0094] S42, based on Green's function theory, the Green's function solution G(r,r′,ω) of the neutron noise equation is the transfer function between the control rod vibration and the neutron flux at the neutron detector:

[0095] δφ(r,ω)=∫G(r,r′,ω)S(r′,ω)dr′

[0096] Where r′ represents the position of the control rod; S(r′,ω) represents the disturbance source caused by the vibration of the control rod;

[0097] Step 5: determining the position of the abnormally vibrating control rod based on the minimization algorithm theory and the transfer function between the control rod and the self-powered neutron detector; specifically, the method includes:

[0098] Acquire basic evaluation data, wherein the basic evaluation data includes: self-power spectrum density of every three self-powered detectors at depth S, cross-power spectrum density between every three self-powered detectors, and transfer functions from different abnormal vibration control rods to the three self-powered detectors;

[0099] Calculate the evaluation function Δ(r) based on the evaluation basic data:

[0100]

[0101] In the formula, G ij (r p ) represents the transfer function between the self-powered detector i and the self-powered detector j; G jk (r p ) represents the transfer function between the self-powered detector i and the self-powered detector k; Represents G ij (r p )'s inverse operator; Represents G jk (r p )'s inverse operator; Represents G ij (r p )'s adjoint operator; Represents G jk (r p )'s adjoint operator; S ij represents the neutron noise spectrum matrix of self-powered detector i and self-powered detector j; S jk represents the neutron noise spectrum matrix of self-powered detector j and self-powered detector k; r p represents the position of the control rod p;

[0102] in,

[0103]

[0104] In the formula, represents the self-power spectral density of the self-powered detector i; represents the self-power spectrum density of the self-powered detector j; represents the cross power spectral density of the self-powered detector j and represents the self-powered detector i; represents the cross power spectral density of the self-powered detector i and the self-powered detector j; φ0(r p ) represents r p Neutron flux level at the location; G(r i ,r p ,ω) represents the Green function solution of the neutron noise equation of the self-powered detector i; G(r j ,r p ,ω) represents the Green’s function solution of the neutron noise equation of the self-powered detector j.

[0105] The r with the minimum evaluation function p As abnormal vibration control rod position.

[0106] This embodiment evaluates whether there is abnormal vibration of the control rod based on the neutron noise signal data measured by the self-powered neutron detector in the reactor, and determines the cause of the abnormal vibration; uses the neutron transport equation to calculate the transfer function between the control rod and the neutron detector, and determines the position of the control rod where the abnormal vibration occurs through the minimization algorithm theory; the overall logic is clear, easy to implement and promote application, solves the problem that the abnormal vibration of the control rod in the reactor cannot be monitored, avoids the abnormal vibration of the control rod, and effectively guarantees the safety and reliability of the reactor control rod.

[0107] Example 2

[0108] This embodiment provides an abnormal vibration control rod positioning system based on neutron noise signals, which is used to implement the abnormal vibration control rod positioning method based on neutron noise signals in embodiment 1, such as Figure 2 As shown, the system comprises:

[0109] An acquisition module is used to arrange multiple self-powered neutron detectors in the reactor and collect neutron noise signal data measured by each powered neutron detector;

[0110] The acquisition module includes a self-powered neutron detector;

[0111] The preprocessing module is used to preprocess the neutron noise signal data; the preprocessing module includes an amplifier circuit, a filter circuit and a DC isolation circuit, etc. The DC isolation circuit separates the AC signal and the DC signal of the neutron noise signal data, the amplifier circuit is used to amplify the AC signal, and the filter circuit is used to filter the amplified AC signal.

[0112] A judgment module, used for judging whether the control rod has abnormal vibration based on the preprocessed neutron noise signal data;

[0113] A construction module for constructing a transfer function between a control rod and a self-powered neutron detector based on a neutron transport equation;

[0114] The positioning module is used to determine the position of the abnormally vibrating control rod based on the minimization algorithm theory and the transfer function between the control rod and the self-powered neutron detector.

[0115] Example 3

[0116] This embodiment provides a computer readable medium, on which a computer program is stored. The computer program is executed by a processor to implement the abnormal vibration control rod positioning method based on neutron noise signal as in Embodiment 1. Specifically, the following steps are performed:

[0117] Step 1: Collect neutron noise signal data measured by each energized neutron detector;

[0118] Step 2: preprocessing the neutron noise signal data;

[0119] Step 3: judging whether there is abnormal vibration of the control rod based on the preprocessed neutron noise signal data;

[0120] Step 4: Construct the transfer function between the control rod and the self-powered neutron detector based on the neutron transport equation;

[0121] Step 5: Determine the position of the abnormally vibrating control rod based on the minimization algorithm theory and the transfer function between the control rod and the self-powered neutron detector.

[0122] Example 4

[0123] In this embodiment, the neutron noise signal of the self-powered detector is used to analyze the abnormal vibration of the control rod. First, the neutron noise signal data measured by the self-powered neutron detector in the reactor is obtained; whether the control rod has abnormal vibration and the cause of the abnormal vibration is determined; the transfer function between the control rod and the self-powered neutron detector is calculated using the neutron transport equation; the position of the control rod where the abnormal vibration occurs is determined by the minimization algorithm theory; in this embodiment, the rhodium self-powered neutron detector is used, and the specific process is as follows: Figure 3 As shown:

[0124] Firstly, the neutron current data measured by the Rhodium Self-Powered Neutron Detector in the pile is obtained and the signal is DC-isolated, filtered and amplified. Then, the conversion coefficient H(ω) of the Rhodium Self-Powered Neutron Detector is calculated by the response mode of the Rhodium Self-Powered Neutron Detector to the neutron flux:

[0125]

[0126] In the formula, λ1 and λ2 represent the elements and elements The decay constants are 0.016s -1 and 0.0027s -1 ; N(ω) represents the neutron flux density at the rhodium self-powered neutron detector; I(ω) represents the output current of the rhodium self-powered neutron detector; a1 and a2 represent the element and elements The current share caused by; c represents the instantaneous response component of the rhodium self-powered neutron detector current, which is less than 1. The value of ω is in the fuel vibration range (4π, 120π). In this range, the first-order and second-order terms of the transfer function are much smaller than the constant term. The fluctuation component of the neutron current signal is approximately linearly related to the neutron noise signal data, that is:

[0127]

[0128] δφ(r,t)=cδi(r,t)=c(i(r,t)-E(i(r,t)))

[0129] Determine whether there is abnormal vibration of the control rod and determine the cause of the abnormal vibration. Since the neutron noise signal is caused by the abnormal self-excited vibration of the control rod, acoustic standing waves caused by the interaction between the main pump and other power equipment, turbulent excitation, tube bundle and coolant, and the core basket vibration, the control rod forced vibration signal is transmitted to each detection component through the system transfer function, causing the fluctuation of the measurement signal. Through the cyclic cross-correlation function between the signals, the random signal in the core can be filtered out (the cross-correlation between random signals is 0), so that the characteristic signal caused by the abnormal forced vibration of the control rod can be highlighted. By analyzing the frequency range of the corresponding frequency of the abnormal cross-correlation function, the cause of the abnormal vibration is determined by combining the cross-power spectrum density amplitude, phase and auto-power spectrum density. For example, the frequency peak around 9Hz corresponds to the abnormal forced vibration of the control rod caused by the vibration of the core basket.

[0130] The transfer function between the control rod and the neutron detector is calculated using the neutron transport equation. If the single-group neutron approximation is used, the neutron noise equation caused by the fluctuation of the absorption cross section is:

[0131]

[0132] In the formula is a vector differential operator, B(ω) is the geometric curvature of the reactor, S(r,ω) is the disturbance source caused by the vibration of the control rod, and D is the neutron diffusion coefficient.

[0133] According to the Green's function theory, the Green's function solution G(r,r′,ω) of the neutron noise equation is the transfer function between the control rod vibration and the neutron flux at the neutron detector.

[0134] δφ(r,ω)=∫G(r,r′,ω)S(r′,ω)dr′

[0135] Solve the Green's function of the differential equation using the Fourier transform method:

[0136]

[0137] In the formula, δ(rr p ) is the Dirac function, the position of the detector is r, and the position of the control rod is r p ={x p ,y p}, ε (t) is the two-dimensional displacement near the equilibrium position, and its Fourier transform result is ε(ω)={ε x (ω),ε y (ω)}.

[0138] Finally, the position of the control rod where abnormal vibration occurs is determined by the minimization algorithm theory; under ideal conditions, the neutron noise spectrum amplitude δφ(r,ω) of a single sensor is equal to the ratio of its transfer function amplitude.

[0139] δφ(r,ω)=γ{ε x (ω)G x (r,r p ,ω)+ε y (ω)G y (r,r p ,ω)}

[0140] Where:

[0141]

[0142] In engineering applications, considering a certain error, at the location where abnormal vibration of the control rod occurs, the square of the difference between the above two equations is the smallest. In order to reduce the influence of random signals on the desired results, the Wiener-Khinchin theorem is used to consider using the auto-power spectrum APSD of the detector signal δφ (r i ,ω) and cross power spectrum CPSD δφ (r i ,r j ,ω) and the auto-power spectrum and cross-power spectrum S of the vibration components xx (ω), S yy (ω) and S xy (ω) replaces the spectrum value to eliminate the unknown variable S xx (ω), S yy (ω), S xy The influence of (ω) and γ is taken into consideration, and the relationship between the auto-power spectrum and cross-power spectrum of the neutron noise signal of the rhodium self-powered neutron detector and the transfer function is obtained. The neutron noise signals of the rhodium self-powered neutron detector at three different positions {r1, r2, r3} are taken together.

[0143]

[0144] CPSD δφ (r1,r2,ω)=γ 2 {G 1x G 2x S xx +G 1y G 2y S yy +(G 1x G 2y +G 2x G 1y )S xy}

[0145] CPSDδφ (r2,r3,ω)=γ 2 {G 2x G 3x S xx +G 2y G 3y S yy +(G 2x G 3y +G 3x G 2y )S xy}

[0146] CPSD δφ (r1,r3,ω)=γ 2 {G 1x G 3x S xx +G 1y G 3y S yy +(G 1x G 3y +G 3x G 1y )S xy}

[0147] Where:

[0148] G ix ≡G x (r i ,r p ,ω); i=1,2,3

[0149] G iy ≡G y (r i ,r p ,ω); i=1,2,3

[0150] Solve the above equations simultaneously to eliminate the unknown variable S xx (ω), S yy (ω), S xy The influence of (ω) and γ.

[0151]

[0152] Where S ij is the neutron noise spectrum matrix of Rh self-powered neutron detector i and Rh self-powered neutron detector j;

[0153]

[0154] G ij is the transfer function matrix between the Rhodium self-powered neutron detector i and the Rhodium self-powered neutron detector j;

[0155]

[0156] In order to obtain the minimum estimate, while considering the signal interference of the sensors in the project, four rhodium self-powered neutron detectors are polled to obtain the optimal evaluation function, namely:

[0157]

[0158] Make the evaluation function take the minimum r p The value is the position of the control rod where abnormal vibration occurs.

[0159] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for locating abnormal vibration control rods based on neutron noise signals, characterized in that: include: Arrange a plurality of self-powered neutron detectors in the reactor to collect neutron noise signal data measured by the respective powered neutron detectors; Preprocessing the neutron noise signal data; Judging whether there is abnormal vibration of the control rod based on the preprocessed neutron noise signal data; The transfer function between the control rod and the self-powered neutron detector is constructed based on the neutron transport equation; The position of abnormally vibrating control rod is determined based on the minimization algorithm theory and the transfer function between the control rod and the self-powered neutron detector.

2. The abnormal vibration control rod positioning method based on neutron noise signal according to claim 1 is characterized in that: The method of arranging a plurality of self-powered neutron detectors in a reactor includes: The first control rod assembly and the second control rod assembly are determined according to condition a; condition a: there is no control rod assembly around the first control rod assembly or the first control rod assembly is the second control rod assembly; A plurality of self-powered neutron detectors are arranged at a central position of the first control rod assembly and at equal depth intervals along a control rod insertion direction.

3. The abnormal vibration control rod positioning method based on neutron noise signal according to claim 1 is characterized in that: The neutron noise signal data includes neutron current signal noise data; The neutron noise signal data δφ(r,t) is: δφ(r,t)=cδi(r,t)=c[i(r,t)-E(i(r,t))] Where δi(r,t) represents the neutron current signal noise data; E(·) represents the time-scale mean of the signal; i(r,t) represents the neutron current signal; r represents the position of the core; t represents time; and c represents the linear conversion coefficient of the self-powered neutron detector.

4. The abnormal vibration control rod positioning method based on neutron noise signal according to claim 1 is characterized in that: The preprocessing of the neutron noise signal data comprises a method: Separating an AC signal and a DC signal from the neutron noise signal data, and amplifying the AC signal; The DC signal and the amplified AC signal are sampled respectively, and the amplified AC signal is filtered to obtain a first AC signal; The first AC signal is divided by the DC signal.

5. The abnormal vibration control rod positioning method based on neutron noise signal according to claim 2 is characterized in that: The method of judging whether the control rod has abnormal vibration based on the preprocessed neutron noise signal data includes: Obtain neutron noise signals of different self-powered detectors deployed at the same depth; Calculate the cross-correlation function between self-powered detectors at the same depth based on neutron noise signals; Determine whether the control rod has abnormal vibration based on the cross-correlation function: Obtain the natural frequency of each control rod; At the natural frequency of the control rod, a cross-correlation threshold is preset, and when the cross-correlation function is greater than the cross-correlation threshold, it is determined that an abnormality exists in the control rod.

6. The abnormal vibration control rod positioning method based on neutron noise signal according to claim 5 is characterized in that: The method of calculating the cross-correlation function between self-powered detectors at the same depth based on the neutron noise signal includes: The cross-correlation function R(r,ω) between the self-powered detector x and the self-powered detector y at depth z is: In the formula, S xx (r,ω) represents the power spectrum density of the self-powered detector x at depth z; S yy (r,ω) represents the power spectrum density of the self-powered detector y at depth S; S xy (r, ω) represents the cross power spectrum density of the self-powered detector x and the self-powered detector y at depth z; r represents the position of the self-powered neutron detector, and ω represents the circular frequency of the neutron noise signal.

7. The abnormal vibration control rod positioning method based on neutron noise signal according to claim 1 is characterized in that: The transfer function between the control rod and the self-powered neutron detector is constructed based on the neutron transport equation; including the method: Based on neutron transport theory, the neutron noise equation caused by the fluctuation of the absorption cross section is: Where L is an operator defined on the Hilbert space, S(r,ω) is the disturbance source caused by the control rod vibration, D is the neutron diffusion coefficient; δφ(r,ω) represents the neutron noise signal; r represents the position of the self-powered neutron detector, and ω represents the circular frequency of the neutron noise signal; Based on the Green's function theory, the Green's function solution G(r,r′,ω) of the neutron noise equation is the transfer function between the control rod vibration and the neutron flux at the neutron detector: Where r′ represents the position of the control rod; S(r′,ω) represents the disturbance source caused by the vibration of the control rod.

8. The abnormal vibration control rod positioning method based on neutron noise signal according to claim 7 is characterized in that: The method of determining the position of the abnormally vibrating control rod based on the minimization algorithm theory and the transfer function between the control rod and the self-powered neutron detector includes: Acquire basic evaluation data, the basic evaluation data including: self-power spectrum density of self-powered detector i, self-powered detector j, and self-powered detector k at depth S; mutual power spectrum density between self-powered detector i, self-powered detector j, and self-powered detector k; and transfer functions of different abnormal vibration control rods to self-powered detector i, self-powered detector j, and self-powered detector k; i≠j≠k; Calculate the evaluation function Δ(r) based on the evaluation basic data: In the formula, G ij (r p ) represents the transfer function between the self-powered detector i and the self-powered detector j; G jk (r p ) represents the transfer function between the self-powered detector i and the self-powered detector k; Represents G ij (r p ) inverse operator; Represents G jk (r p ) inverse operator; Represents G ij (r p )’s adjoint operator; Represents G jk (r p ) is the inverse operator of the adjoint operator; S ij represents the neutron noise spectrum matrix of self-powered detector i and self-powered detector j; S jk represents the neutron noise spectrum matrix of self-powered detector j and self-powered detector k; r p represents the position of the control rod p; The r with the minimum evaluation function p As abnormal vibration control rod position.

9. Abnormal vibration control rod positioning system based on neutron noise signal, characterized in that: The system is used to implement the abnormal vibration control rod positioning method based on neutron noise signals as described in any one of claims 1 to 8, and comprises: An acquisition module is used to arrange multiple self-powered neutron detectors in the reactor and collect neutron noise signal data measured by each powered neutron detector; A preprocessing module, used for preprocessing the neutron noise signal data; A judgment module, used for judging whether the control rod has abnormal vibration based on the preprocessed neutron noise signal data; A construction module for constructing a transfer function between a control rod and a self-powered neutron detector based on a neutron transport equation; The positioning module is used to determine the position of the abnormally vibrating control rod based on the minimization algorithm theory and the transfer function between the control rod and the self-powered neutron detector.

10. A computer readable medium having a computer program stored thereon, characterized in that: The computer program is executed by a processor to implement the abnormal vibration control rod positioning method based on neutron noise signals as described in any one of claims 1 to 8.

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