A real-time monitoring method and system for biaxial creep of nuclear fuel cladding tubes

Abstract

The present invention relates to the field of creep monitoring technology, specifically a method and system for real-time monitoring of biaxial creep of nuclear fuel cladding tubes, comprising the following steps: obtaining displacement increments, calculating angular offset rates, generating configuration angle change rate data, detecting four-quadrant displacement increments, generating cross-sectional torsional asymmetry, extracting interference peaks, obtaining creep response signal delay trends, collecting temperature change rates, obtaining temperature-stress coupling growth trend analysis results, and issuing biaxial creep configuration instability warning information. In the present invention, by extracting and judging the joint evolution trajectory of real-time spatial structural behavior and physical channel states, channel response switching can be triggered at the initial stage of structural change, establishing a feedback link between material behavior identification and method scheduling response, and constructing a linkage control model driven by multi-dimensional spatiotemporal characteristics to achieve a deep collaborative control effect between structural state and method response.

Description

Technical Field

[0001] The present invention relates to the technical field of creep monitoring, and in particular to a method and system for real-time monitoring of biaxial creep of a nuclear fuel cladding tube. Background Art

[0002] The field of creep monitoring technology encompasses a variety of methods and devices used to observe and analyze the deformation and failure behavior of materials under long-term stress. Its core focus is on evaluating and predicting the stability and lifespan of materials in high-temperature and high-pressure environments, particularly in high-performance engineering materials and critical structural components. Creep monitoring typically involves long-term data collection, using sensors and other measuring devices to continuously track minute dimensional changes in materials. Furthermore, these techniques rely on precise data analysis and physical models to interpret the monitoring data and predict the material's future performance.

[0003] The real-time biaxial creep monitoring method for nuclear fuel cladding tubes is a technology specifically designed for monitoring the material properties of nuclear fuel cladding tubes within nuclear reactors. It focuses on capturing and analyzing the deformation behavior of nuclear fuel cladding tubes in real time after being subjected to stress in the nuclear reactor operating environment. This typically involves directly or indirectly measuring the deformation after stress using high-temperature and high-pressure sensors, followed by preliminary data processing for real-time monitoring. This monitoring method focuses on early diagnosis of creep behavior that may occur during operation to prevent potential structural failure.

[0004] While existing creep monitoring technologies can capture the deformation and failure behavior of materials under long-term stress, they often fail to respond promptly to rapid, dynamic environmental changes. For example, when monitored data is subject to sudden environmental disturbances (such as sudden temperature fluctuations or mechanical shock), traditional technologies, relying on slow data processing and update mechanisms, may not be able to adjust immediately, resulting in inaccurate or time-sensitive data capture. Furthermore, existing technologies often fail to effectively correlate signal channel stability with material deformation trends, leading to unstable data transmission at critical moments and compromising the early warning capabilities of the entire monitoring system. These shortcomings are particularly prominent in the monitoring of critical engineering materials such as nuclear fuel cladding tubes, where any monitoring errors pose serious safety risks. This lack of rapid dynamic response and comprehensive data processing capabilities effectively prevents accurate early warnings under extreme or unusual operating conditions, hindering the effective prevention of structural failure. Summary of the Invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a real-time monitoring method and system for biaxial creep of nuclear fuel cladding tubes.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a real-time monitoring method for biaxial creep of nuclear fuel cladding tubes, comprising the following steps:

[0007] S1: Obtain the axial displacement increment and circumferential displacement increment of the nuclear fuel cladding tube, detect the displacement change of adjacent monitoring points, extract the periodic direction angle value, calculate the angle offset rate, and generate the configuration angle change rate data;

[0008] S2: Based on the configuration angle change rate data, detect the displacement increments of the four quadrants of the cladding tube cross section, calculate the sum of the displacement increment differences of the symmetric quadrants, determine the single-cycle cross section torsional asymmetry, judge the continuous growth trend, and generate the cross section torsional asymmetry;

[0009] S3: extracting the peak value of the monitoring signal interference amplitude based on the cross-sectional torsional asymmetry, recording the direction of the offset change in the continuous cycle, analyzing the increasing trend of the interference intensity, and obtaining the creep response signal delay trend;

[0010] S4: Based on the creep response signal delay trend, collecting the temperature change rate of the outer surface of the cladding tube, extracting the biaxial stress increment, judging the synchronous growth trend, and obtaining the temperature-stress coupling growth trend analysis result;

[0011] S5: Based on the analysis results of the temperature-stress coupling growth trend, the configuration angle change rate data and the cross-sectional torsional asymmetry are combined to comprehensively judge the creep trend, trigger the configuration instability warning mechanism, and issue a biaxial creep configuration instability warning message.

[0012] As a further solution of the present invention, the configuration angle change rate data includes a two-dimensional direction vector, a direction angle value, and an angle offset rate; the section torsional asymmetry includes the sum of the symmetrical quadrant displacement increment differences, the four-quadrant displacement increment total value, and a continuous growth trend; the creep response signal delay trend includes the interference amplitude peak, the offset change direction, the signal return delay characteristic value, and the delay offset trend; the temperature stress coupling growth trend analysis results include the temperature change rate, the biaxial stress increment, and the synchronous growth trend; and the biaxial creep configuration instability warning information includes the configuration angle change rate data, the section torsional asymmetry, and the temperature stress coupling growth trend analysis results.

[0013] As a further solution of the present invention, the specific steps for obtaining the configuration angle change rate data are:

[0014] S111: Obtaining the displacement data of monitoring points of the nuclear fuel cladding tube in a single cycle in the reactor working environment, constructing a two-dimensional coordinate system based on the center position of the cladding tube as the origin, calling the axial displacement increment and the circumferential displacement increment values ​​of each monitoring point in the current cycle, calculating the relative displacement change of each adjacent monitoring point in the two-dimensional coordinate system, and generating relative displacement increment data;

[0015] S112: Based on the relative displacement increment data, performing a combined calculation of the axial and circumferential components of the relative displacement changes of adjacent monitoring points in the two-dimensional coordinate system, obtaining the two-dimensional direction vector value corresponding to each pair of monitoring points, calling all direction vectors in the current cycle, and obtaining the direction angle value of each direction vector according to the coordinate system origin reference benchmark to generate a direction angle data set;

[0016] S113: Read the directional angle data group of the current cycle and the previous cycle, and for the directional angle value under the corresponding monitoring point number, count the change in the directional angle of each monitoring point, and calculate the angle offset rate corresponding to each monitoring point based on the time interval between adjacent cycles to generate configuration angle change rate data.

[0017] As a further solution of the present invention, the specific steps for obtaining the cross-sectional torsional asymmetry are:

[0018] S211: Based on the configuration angle change rate data, detecting displacement increments of the cladding tube cross section in four quadrants under the reactor operation state, arranging the displacement increments of the corresponding monitoring points in each quadrant in order from the first quadrant to the fourth quadrant, sequentially filling the displacement increments of the corresponding monitoring points in each quadrant into a two-dimensional array structure, and constructing a quadrant displacement increment matrix with the quadrant position as the index dimension;

[0019] S212: Based on the quadrant displacement increment matrix, performing paired subtraction on the displacement increments in the first and third quadrants, and the second and fourth quadrants, respectively, calculating the displacement increment difference between the two groups of symmetrical quadrants, and simultaneously obtaining the sum of all displacement increment values ​​in the four quadrants, calculating the ratio of the sum of the differences to the total displacement value, and obtaining the torsional asymmetry of the single-period section;

[0020] S213: Read the single-cycle cross-section torsional asymmetry of three consecutive cycles, arrange the asymmetry values ​​corresponding to each cycle in chronological order, and judge the trend of the value change of the three cycles. If the asymmetry values ​​of the last three cycles are in a continuous rising state, the evolution state is recorded as torsional imbalance, and the cross-section torsional asymmetry is established.

[0021] As a further solution of the present invention, the specific steps for obtaining the creep response signal delay trend are:

[0022] S311: Extracting the interference amplitude data of each cycle in the biaxial creep monitoring signal channel of the cladding tube based on the cross-sectional torsional asymmetry, detecting the amplitude change of the interference signal in each cycle and obtaining the amplitude peak, calling the channel reference signal amplitude as a reference value, performing a comparison between the peak signal of each cycle and the reference value, recording the direction of the offset change in each cycle, and obtaining a cycle amplitude offset direction sequence;

[0023] S312: Based on the periodic amplitude offset direction sequence, the consistency of the interference amplitude change direction in consecutive periods is determined, the amplitude change values ​​are extracted and arranged in a time series, the amplitude differences within any three consecutive periods are accumulated and compared with the zero deviation value to determine whether the signs are consistent, and the interference signal strength change trend is obtained;

[0024] S313: Based on the interference intensity change trend, extract the start time and end time of the signal return of each cycle, calculate the return delay characteristic value within the cycle, and arrange the multi-cycle delay time values ​​in chronological order to obtain the change in the delay time of each cycle, perform symbol judgment and sequence coherence identification on the change, and establish the creep response signal delay trend.

[0025] As a further solution of the present invention, the return delay characteristic value within the period is calculated using the formula:

[0026] ;

[0027] Calculate, where Representative The return delay characteristic value of the cycle, Representative The start time of the periodic signal, Representative The end time of the periodic signal, Representative The amplitude change of the cycle (that is, the absolute value of the difference between the current cycle peak value and the reference value), Represents the sum of the absolute values ​​of the amplitude changes of the current and previous two cycles, 、 、 They represent the absolute value of the difference between the current period and the amplitude change during the previous two weeks.

[0028] As a further solution of the present invention, the specific steps for obtaining the temperature stress coupling growth trend analysis result are:

[0029] S411: Based on the creep response signal delay trend, collecting temperature measurement data per unit time at each monitoring point on the outer surface of the cladding tube, extracting temperature change values ​​for consecutive time periods within each cycle, and calculating the temperature change rate in each cycle in combination with the time interval to obtain a temperature change rate per unit time group;

[0030] S412: Extracting a stress value sequence of the biaxial stress monitoring point in each cycle based on the temperature change rate group per unit time, calculating the biaxial stress increment in each cycle, recording the sign of the change direction of the temperature change rate in the corresponding cycle, determining whether the change directions of the two are consistent, and establishing a stress-temperature co-directional change sequence;

[0031] S413: Based on the stress-temperature unidirectional change sequence, extract the directional consistency results under two consecutive cycles, calculate the directional consistency recorded in the two cycles and perform a Boolean judgment. If the judgment result is a continuous unidirectional mark, it is confirmed that stress-temperature rise coupling behavior exists, and the temperature-stress coupling growth trend analysis result is established.

[0032] As a further solution of the present invention, the Boolean judgment of the direction consistency flags recorded in two cycles is performed using the formula:

[0033] ;

[0034] Calculate, where Represents the coupling consistency trend value of the current cycle, Represents the consistency mark of the temperature and stress change direction of the current cycle. The value is 1 for the same direction, -1 for the opposite direction, and 0 for an invalid record. Represents the directional consistency mark of the previous cycle, Represents the absolute average value of the temperature change rate in the current cycle, Represents the average absolute value of the temperature change rate in the previous cycle, Represents the average absolute value of stress change in the current cycle, Represents the average absolute value of stress change in the previous cycle.

[0035] As a further solution of the present invention, the specific steps for obtaining the biaxial creep configuration instability warning information are as follows:

[0036] S511: Based on the analysis results of the temperature-stress coupling growth trend, combined with the configuration angle change rate data and the cross-sectional torsional asymmetry in the current cycle, a continuous cycle sequence corresponding to the three data items is extracted, and the values ​​of any two adjacent cycles in each data sequence are subjected to difference judgment. The change signs are recorded and the number of positive changes is counted to obtain the number of incremental matching of the three parameters.

[0037] S512: Based on the number of incremental matches of the three parameters, determine whether each parameter has a positive change flag within three consecutive cycles, set a judgment threshold, and perform a judgment equal to the number of matches. If the judgment result is yes, mark the current state as a configuration trend unstable state, and obtain a configuration instability trend state flag;

[0038] S513: According to the configuration instability trend state mark, extract the data period time point marked as the configuration trend instability state, perform the warning trigger mark write operation on the time point, and output the creep state type corresponding to the current period, record the state type as the biaxial creep configuration instability state, and issue the biaxial creep configuration instability warning information.

[0039] A real-time monitoring system for biaxial creep of nuclear fuel cladding tubes, comprising:

[0040] The angle monitoring module obtains the axial and circumferential displacement increments, constructs two-dimensional coordinates, detects the displacement change, calculates the direction vector and direction angle, compares the angle offset rates of adjacent cycles, and generates configuration angle change rate data;

[0041] The torsion analysis module extracts the four-quadrant displacement increments based on the configuration angle change rate data, constructs a data matrix, calculates the ratio of the symmetric difference to the total value, determines the growth trend, and generates the cross-sectional torsional asymmetry under biaxial stress;

[0042] The signal interference module extracts the signal interference peak value according to the cross-section torsional asymmetry, compares the reference amplitude difference, detects the return delay, and obtains the creep response signal delay trend;

[0043] The coupling determination module collects the temperature change rate per unit time based on the delay trend of the creep response signal, extracts the biaxial stress increment, determines the synchronous improvement trend, and obtains the temperature-stress coupling growth trend analysis result;

[0044] The instability warning module determines the increasing trend based on the temperature-stress coupling growth trend analysis result, combines the configuration angle change rate data and the cross-sectional torsional asymmetry, triggers the warning mechanism, and issues a biaxial creep configuration instability warning information.

[0045] Compared with the prior art, the advantages and positive effects of the present invention are:

[0046] In the present invention, a configuration behavior identification mechanism with vector rotation angle continuity and cross-sectional torsional asymmetry as the core is linked with the interference gradient trend, temperature-voltage mutation coupling and delay offset prediction mechanism of the signal channel. By extracting and judging the joint evolution trajectory of real-time spatial structural behavior and physical channel state, channel response switching can be triggered at the early stage of structural change, opening up the feedback link between material behavior identification and method scheduling response, and being able to construct a linkage control model driven by multi-dimensional spatiotemporal characteristics to achieve a deep collaborative control effect between structural state and method response. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of the steps of the present invention;

[0048] Figure 2 It is a system module diagram of the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0050] In the description of the present invention, it should be understood that the terms "length," "width," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," and the like, indicating positions or relationships, are based on the positions or relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, in the description of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

[0051] See also Figure 1 A real-time monitoring method for biaxial creep of a nuclear fuel cladding tube comprises the following steps:

[0052] S1: Obtain the axial displacement increment and circumferential displacement increment of the nuclear fuel cladding tube in a single cycle in the reactor working environment, construct a two-dimensional coordinate system with the center of the cladding tube as the origin, detect the displacement changes of adjacent monitoring points, calculate the two-dimensional direction vector based on the changes, and extract the direction angle value of each cycle. Calculate the angular deviation rate of the direction angle between the current cycle and the previous cycle to generate configuration angle change rate data;

[0053] S2: Based on the configuration angle change rate data, the four-quadrant displacement increments of the cladding tube cross section under the reactor operation state are detected. The data are arranged in quadrant order to form a two-dimensional data matrix. The difference in the displacement increments of the symmetrical quadrants is calculated and summed. This is compared with the total value of the four-quadrant displacement increments to determine the single-cycle cross-sectional torsional asymmetry. The asymmetry over multiple cycles is recorded and the continuous growth trend is determined. If it shows stable growth within three cycles, it is determined to be torsional unbalanced evolution, and the cross-sectional torsional asymmetry under biaxial stress is generated.

[0054] S3: Based on the cross-sectional torsional asymmetry, the peak value of the interference amplitude in the cladding tube biaxial creep monitoring signal channel is extracted and compared with the channel reference signal amplitude. The direction of the offset change in the continuous cycle is recorded, the increasing trend of the interference intensity is analyzed, and the channel signal return delay characteristic value is synchronously detected to extract the delay offset trend and obtain the creep response signal delay trend.

[0055] S4: Based on the creep response signal delay trend, the temperature change rate per unit time on the outer surface of the cladding tube is collected, the biaxial stress increment is extracted, and the change directions of the two are compared to determine whether they are consistent. The synchronous growth trend is then determined. If the two increase in the same direction within two cycles, it is confirmed to be a stress-temperature rise coupling feature, and the temperature-stress coupling growth trend analysis results are obtained;

[0056] S5: Based on the results of the temperature-stress coupling growth trend analysis, combined with the configuration angle change rate data and the cross-sectional torsional asymmetry, a comprehensive judgment is made on the biaxial stress creep trend of the cladding tube under the current working conditions. If all three results show an increasing trend, the configuration instability warning mechanism is triggered and a biaxial creep configuration instability warning information is issued.

[0057] The configuration angle change rate data includes two-dimensional direction vector, direction angle value, and angle offset rate. The section torsional asymmetry includes the sum of the displacement increment differences of the symmetrical quadrants, the total value of the four-quadrant displacement increments, and the continuous growth trend. The creep response signal delay trend includes the interference amplitude peak, offset change direction, signal return delay characteristic value, and delay offset trend. The temperature-stress coupling growth trend analysis results include the temperature change rate, biaxial stress increment, and synchronous growth trend. The biaxial creep configuration instability warning information includes the configuration angle change rate data, section torsional asymmetry, and temperature-stress coupling growth trend analysis results.

[0058] The specific steps of S1 are:

[0059] S111: Obtaining the displacement data of monitoring points of the nuclear fuel cladding tube in a single cycle in the reactor working environment, constructing a two-dimensional coordinate system based on the center position of the cladding tube as the origin, calling the axial displacement increment and the circumferential displacement increment values ​​of each monitoring point in the current cycle, calculating the relative displacement change of each adjacent monitoring point in the two-dimensional coordinate system, and generating relative displacement increment data;

[0060] To obtain the displacement data of the monitoring points in a single cycle when the nuclear fuel cladding tube is running in the reactor, it is necessary to first retrieve the axial displacement increment and circumferential displacement increment values ​​of each monitoring point in the cycle from the monitoring system, set the center point of the cladding tube as the origin of the two-dimensional coordinate system, and establish a rectangular coordinate system with the axial direction as the vertical axis and the circumferential direction as the horizontal axis. Then, the position of each monitoring point at the beginning of the cycle is used as the reference point, and the coordinate position of the current cycle is updated according to the corresponding axial and circumferential increments. Then, any pair of adjacent monitoring points is selected, and the updated position coordinates of the two points in this cycle are obtained respectively. The change values ​​of the two points in the axial and circumferential directions are compared to calculate the The relative displacement change between two points within the cycle. For example, if two points are located on two adjacent monitoring rings in the middle of the cladding tube, and their axial positions differ by 5 mm, the two points will be displaced by approximately 0.12 mm and 0.01 radians in the axial and circumferential directions respectively within a certain cycle. After conversion, the relative displacement change of the two monitoring points in the two-dimensional coordinate system is an increase of approximately 5.06 mm in the axial direction, and the surface distance corresponding to the change in the circumferential direction is 0.23 mm. In this way, the relative displacement change data of adjacent monitoring points are obtained pair by pair, and the results of all monitoring point pairs are organized into an overall relative displacement increment data set within the cycle.

[0061] S112: Based on the relative displacement increment data, a joint calculation of the axial and circumferential components of the relative displacement changes of adjacent monitoring points in the two-dimensional coordinate system is performed to obtain the two-dimensional direction vector value corresponding to each pair of monitoring points. All direction vectors in the current cycle are called, and the direction angle value of each direction vector is obtained according to the coordinate system origin reference benchmark to generate a direction angle data set.

[0062] Based on the relative displacement increment data of each adjacent monitoring point pair in the two-dimensional coordinate system obtained in the previous stage, the axial and circumferential displacement differences between each group of adjacent monitoring points need to be combined as the components of a direction vector. By calculating the increment sizes in the two directions, the direction information of the monitoring point pair in the current cycle is constructed. When constructing the direction information, the coordinate system established at the center of the cladding tube is used as the reference, and the angular position of the vector in the coordinate system is determined according to the incremental direction of the vector. The angle can be obtained by comparing the incremental values ​​in the two directions to reflect the movement trend between adjacent monitoring points. For example, in a certain cycle, a point pair The axial displacement difference is 5.06 mm, and the circumferential difference is 0.23 mm. The directional angle value of the point pair is the angle corresponding to the ratio of the two increments. This angle characterizes the directional trend of the displacement of the monitoring point. Direction information is generated in this way for all monitoring point pairs. The directional angles formed by all monitoring point pairs in the cycle are numbered and organized to form a directional angle data group. In this process, a tolerance standard for directional angle changes should be set. For example, point pairs with a directional angle deviation of less than 0.5 degrees are identified as relatively stable areas. All monitoring point pairs execute the above steps to obtain a complete directional angle data group for the current cycle.

[0063] S113: Read the direction angle data sets of the current cycle and the previous cycle, count the direction angle changes of each monitoring point for the direction angle values ​​under the corresponding monitoring point numbers, calculate the angle deviation rate corresponding to each monitoring point based on the time interval between adjacent cycles, and generate configuration angle change rate data;

[0064] The directional angle data sets obtained in the current cycle and the previous cycle are matched one by one according to the monitoring point pair numbers. The changes in the directional angles of the same monitoring point pair in the two cycles are compared, and the angle change values ​​are recorded. Then, based on the time interval between the two cycles, for example, set to 30 minutes, the angular offset rate of each pair of monitoring points per unit time is calculated. This rate value represents the speed at which the angle of the monitoring point changes during the configuration change process. For example, if the directional angle of a monitoring point pair changes from 2.58 degrees in the previous cycle to 3.10 degrees in the current cycle, the angular offset rate is 1.04 degrees per hour. The same calculation steps are performed on all monitoring point pairs to form the angular offset rate data set of the monitoring points in the cycle. To facilitate the identification of change trends, a rate judgment benchmark value should be set. For example, if the angular offset rate is greater than 1.5 degrees per hour, the monitoring point can be marked as a high variation area. After all monitoring point pairs have completed the above steps, the results are summarized to generate configuration angle change rate data.

[0065] The specific steps of S2 are:

[0066] S211: Based on the configuration angle change rate data, detect the displacement increments of the cladding tube cross section in the four quadrants under the reactor operation state, arrange the displacement increments of the corresponding monitoring points in each quadrant in order from the first quadrant to the fourth quadrant, and sequentially fill the displacement increments of the corresponding monitoring points in each quadrant into a two-dimensional array structure. Use the quadrant position as the index dimension to construct a quadrant displacement increment matrix;

[0067] Based on the configuration angle change rate data, the circular cross-section of the cladding tube is first divided into the first to fourth quadrants according to the standard rectangular coordinate system. According to the monitoring point number and its corresponding position in the configuration angle change rate data, all monitoring points contained in each quadrant are screened. By reading the displacement increment values ​​of these monitoring points in the two-dimensional coordinate system during the period, the corresponding axial and circumferential displacements are obtained respectively. After the monitoring points in each quadrant are arranged in ascending order according to the number, the displacement increment of each monitoring point is extracted in turn as the value of the corresponding cell in the matrix. The arrangement order of the matrix rows and columns is constructed with the quadrant number as the row label and the monitoring point number as the column label, forming a matrix with The two-dimensional array structure represented by the structure, where is the number of monitoring points in each quadrant. For example, if there are three monitoring points numbered 1, 2, and 3 in the first quadrant, and their displacement increments are 0.12, 0.15, and 0.10 mm, respectively, the row vector of the array corresponding to the first quadrant is , and so on to obtain the displacement increment data of the monitoring points in the second to fourth quadrants respectively, fill the above four array rows into the matrix structure in sequence, and use the quadrant number as the row index of the matrix to complete the quadrant displacement increment matrix under this cycle.

[0068] S212: Based on the quadrant displacement increment matrix, the displacement increments in the first and third quadrants, and the second and fourth quadrants are paired and subtracted, and the displacement increment differences between the two groups of symmetrical quadrants are calculated. The sum of all displacement increment values ​​in the four quadrants is obtained, and the ratio of the sum of the differences to the total displacement value is calculated to obtain the torsional asymmetry of the single-period section.

[0069] According to the quadrant displacement increment matrix constructed in the previous stage, the displacement increments of the monitoring points under the same column index in the first and third quadrants, and the second and fourth quadrants are paired respectively, and the bitwise subtraction operation is performed to obtain the displacement increment difference of the symmetrical quadrants. The corresponding columns of the first quadrant and the same columns of the third quadrant are subtracted from each other to obtain the difference vector A, and the same columns of the second quadrant and the fourth quadrant are subtracted to obtain the difference vector B. Then, the absolute value of each value in the difference vectors A and B is taken and accumulated to obtain the sum of the differences. At the same time, the displacement increment data of all monitoring points in the four quadrants are summed up element by element to calculate the total displacement. On this basis, the difference summation is performed. The ratio of the sum divided by the total displacement is the cross-sectional torsional asymmetry under the period. For example, if the sum of the differences is 1.20 mm and the total displacement of the four quadrants is 12.0 mm, then the periodic torsional asymmetry is 0.10. In order to facilitate quantitative analysis, the judgment interval is set. Asymmetry values ​​between 0 and 0.05 are considered mild, and the corresponding interval is [0, 0.05); between 0.05 and 0.15 are moderate, and the corresponding interval is [0.05, 0.15); and values ​​above 0.15 are considered severe, and the corresponding interval is [0.15, 1]. The same processing steps are performed on all quadrants and the results are uniformly aggregated to form the periodic torsional asymmetry results.

[0070] S213: Read the single-cycle cross-section torsional asymmetry for three consecutive cycles, arrange the asymmetry values ​​corresponding to each cycle in chronological order, and judge the trend of the value changes in the three cycles. If the asymmetry values ​​in the last three cycles show a continuous increase, the evolution state is recorded as torsional imbalance, and the cross-section torsional asymmetry is established;

[0071] Read the cross-sectional torsional asymmetry results corresponding to three consecutive cycles of the same monitoring object, arrange and compare the values ​​of the three cycles in chronological order, and set the current cycle as the cycle, then read forward and The historical asymmetry data of two cycles are used to compare the three groups of asymmetry values ​​one by one. First, it is determined whether the value of the second cycle is higher than that of the first cycle, and then whether the value of the third cycle is higher than that of the second cycle. When the two continuous growth relationships are satisfied, the trend is marked as a continuously rising state. The interval between the three-value difference is further calculated. If the difference between each two adjacent cycles is greater than a set evolution threshold, for example, the threshold is set to 0.02, then if the torsional asymmetry of the first, second, and third cycles is 0.06, 0.09, and 0.14 respectively, that is, the two differences are 0.03 and 0.05 respectively, which are all higher than the evolution threshold, the monitored object is marked as a torsional imbalance state, and its cross-sectional torsional asymmetry identification result is established as the basic data content for subsequent deformation trend tracking analysis.

[0072] The specific steps of S3 are:

[0073] S311: Extract the interference amplitude data of each cycle in the biaxial creep monitoring signal channel of the cladding tube based on the cross-sectional torsional asymmetry, detect the amplitude change of the interference signal in each cycle and obtain the amplitude peak value, use the channel reference signal amplitude as a reference value, compare the peak signal of each cycle with the reference value, record the deviation change direction in each cycle, and obtain the cycle amplitude deviation direction sequence;

[0074] According to the object identified by the cross-sectional torsional asymmetry, the interference amplitude data corresponding to each cycle is extracted in the biaxial creep monitoring signal channel of the cladding tube, the complete signal time series in each cycle is read, the local extreme value of the signal amplitude is extracted by point-by-point scanning, the maximum amplitude value in each cycle is identified and recorded as the peak amplitude of the current cycle, and the preset reference signal amplitude of the channel is called at the same time. The reference value is set with reference to the average amplitude data of the five-cycle signal in the initial stage of normal operation and a fixed percentage threshold is set downward. For example, the initial average value is 0.45 volts, and the downward floating percentage is set to 5%, then the reference value is 0.427 5 volts, and compare the peak value of each cycle with the reference value one by one. When the peak value is higher than the reference value, it is marked as a positive offset; when it is lower than the reference value, it is marked as a negative offset; when the two values ​​are equal, it is marked as no offset. By traversing all cycles and completing the comparison operation in sequence and recording the offset sign, a cycle amplitude offset direction sequence arranged in a time series is constructed. For example, the peak values ​​of a monitoring point for five consecutive cycles are 0.42, 0.48, 0.44, 0.41, and 0.50 volts, respectively. After comparing with the reference value of 0.4275 volt, the corresponding offset direction sequence is negative, positive, positive, negative, and positive. This sequence is used for subsequent interference trend identification.

[0075] S312: Based on the periodic amplitude offset direction sequence, the consistency of the interference amplitude change direction in consecutive periods is determined. The amplitude change values ​​are extracted and arranged in a time series. The amplitude differences within any three consecutive periods are accumulated and compared with the zero deviation value to determine whether the signs are consistent, thereby obtaining the interference signal strength change trend.

[0076] Based on the aforementioned periodic amplitude offset direction sequence, the consistency of the offset direction between consecutive periods in the sequence is determined group by group. The sliding window length is set to three periods, and each group of three periods forms a subsequence. The peak value of each period is extracted and the amplitude difference between adjacent periods is calculated. The two differences of the three periods are then added to obtain the cumulative amplitude change. The sign of this cumulative value is compared with the zero value. If the signs are consistent, the current window is marked as a stable change trend. Otherwise, it is marked as a fluctuating change. For example, the peak values ​​of the three periods are 0.42, 0.48, and 0. If the peak values ​​of the three cycles are 0.44, 0.38 and 0.43 volts, the differences are -0.06 and 0.05 respectively, and the cumulative value is 0.09. The positive signs are consistent, which is determined to be an interference enhancement trend. If the peak values ​​of the three cycles are 0.44, 0.38 and 0.43 volts, the differences are -0.06 and 0.05 respectively, and the cumulative value is -0.01, the interference change is unstable because the signs of the previous and subsequent differences are inconsistent. The window sliding operation is continuously executed and the difference signs of all three cycle combinations are determined in turn to be consistent. Finally, a time series mark of the interference signal strength change trend is formed to distinguish the periodic segments with upward, downward or uncertain trends.

[0077] S313: Based on the interference intensity variation trend, extract the return start and end time of each cycle signal, calculate the return delay characteristic value within the cycle, arrange the multi-cycle delay time values ​​in chronological order, obtain the change in the delay time of each cycle, perform sign judgment and sequence coherence identification on the change, and establish the creep response signal delay trend;

[0078] The return delay characteristic value within a cycle is calculated using the formula:

[0079] ;

[0080] Calculate, where Representative The return delay characteristic value of the cycle, Representative The start time of the periodic signal, Representative The end time of the periodic signal, Representative The amplitude change of the cycle (that is, the absolute value of the difference between the current cycle peak value and the reference value), Represents the sum of the absolute values ​​of the amplitude changes of the current and previous two cycles, 、 、 They represent the absolute value of the difference between the current period and the amplitude change during the previous two weeks.

[0081] No. The start time of the cycle The end time is 180.05 seconds. The time data is 180.61 seconds. This time data is acquired by a high-frequency vibration monitoring system at a sampling rate of 10kHz and calibrated by the time index of the interference start and end points in the signal. The amplitude peak is extracted by scanning each cycle signal point by point. The peak value of the current cycle is 0.478 volts, and the baseline value is 0.4275 volts. The difference between the two is 0.0505 volts, so:

[0082] ;

[0083] The peak amplitudes of the first two cycles are 0.455 volts and 0.419 volts, respectively, corresponding to the difference:

[0084] ;

[0085] ;

[0086] Substitute the first part of the return delay time of the current cycle to calculate:

[0087] ;

[0088] ;

[0089] ;

[0090] The first item is:

[0091] ;

[0092] The second term is the average of the differences of the three amplitude changes, which are calculated separately:

[0093] ;

[0094] ;

[0095] ;

[0096] The average is:

[0097] ;

[0098] Final result:

[0099] ;

[0100] The results show that the return delay characteristic value of the 6th cycle is 1.482. The numerical value combined with the amplitude intensity and its changing trend reflects the disturbance response structure of the signal within the cycle. This value will be used as an item in the time series to participate in the judgment of the delay change trend in subsequent cycles.

[0101] The return delay eigenvalue is a comprehensive characteristic quantity used to describe the dynamic change trend of a periodic signal. Based on the amplitude change of a single-cycle signal during the return phase, the disturbance response characteristics of the signal are reflected by combining the return delay time length, the amplitude change intensity and the continuity change trend. Specifically, the return delay eigenvalue not only considers the absolute size of the amplitude change of the current cycle, but also calculates the sum of the absolute values ​​of the amplitude changes of the current and previous two cycles, and further measures the average level of the amplitude change differences between the three cycles, so as to take into account both the amplitude change and the stability of the fluctuation. At the same time, the normalization of the return time is introduced in the eigenvalue calculation to avoid deviations in the results caused by different cycle durations. Ultimately, the return delay eigenvalue can comprehensively reflect the strength of the amplitude change of the periodic signal during the disturbance process, the stability of the trend and its evolution rhythm, providing an important basis for subsequent dynamic characteristic analysis such as signal anomaly detection and trend identification.

[0102] The operational logic of the formula is based on the quantification of the dynamic characteristics of the disturbance response process in the creep monitoring signal. First, the return delay time within a single cycle is multiplied by the amplitude variation of the disturbance signal in that cycle to reflect the coupling relationship between delay and response strength. By performing a square root operation on the amplitude variation, the severity of the response strength is nonlinearly compressed to avoid amplification bias caused by large amplitude values. The product is then divided by the sum of the absolute values ​​of the amplitude variations in the current and previous two cycles to form a normalized proportional structure. This is used to eliminate the scale effect caused by the fluctuation differences between cycles and ensure that the calculated return delay results are comparable across cycles. The average value of the amplitude variation difference over three cycles is then introduced, and the absolute values ​​of the three terms are added and averaged to supplement the continuous variation information of the signal disturbance. This component is not included in the normalization process and is directly added to fully retain the information content of the non-stable signal fluctuations. This component, added with the aforementioned normalized main term, constitutes a complete expression of the delay characteristic. The sum of the two terms reflects the comprehensive dynamic characteristics of the interweaving of stable disturbance response and fluctuating disturbance.

[0103] The specific steps of S4 are:

[0104] S411: Based on the creep response signal delay trend, collect temperature measurement data per unit time at each monitoring point on the outer surface of the cladding tube, extract the temperature change values ​​of consecutive time periods within each cycle, calculate the temperature change rate in each cycle based on the time interval, and obtain a temperature change rate per unit time group;

[0105] Based on the delay trend of the creep response signal, temperature measurement data per unit time is collected from each monitoring point arranged on the outer surface of the cladding tube. First, a fixed time sampling interval is set for each monitoring point, for example, temperature data is collected every 5 seconds. After obtaining the complete time series in a single cycle, the continuous time period data of the temperature change value is extracted. For example, a total of 60 temperature data points are collected from the starting point to the end point in a certain cycle to form a continuous temperature sequence with a length of 5 minutes. The temperature difference between two adjacent time points is selected and the corresponding time difference is recorded. The temperature change rate within the period is calculated based on this time interval, and the latter temperature minus the former temperature is used as the temperature difference. The change is divided by the time difference between the two sampling points to obtain the temperature change rate per unit time. The same operation is performed on all adjacent pairs of temperature points in the entire cycle, and finally a complete set of temperature change rate values ​​per unit time is obtained. Under actual working conditions, if the temperature of a certain point is 460.2 degrees Celsius at the 10th second and 462.7 degrees Celsius at the 15th second, the change value is 2.5 degrees Celsius, the time difference is 5 seconds, and the change rate is 0.5 degrees Celsius per second. Continue to perform this processing on all continuous measurement data in the cycle, store the temperature change rate group of each monitoring point in the cycle in sequence, and mark the cycle number to which it belongs for subsequent coupling relationship operations.

[0106] S412: Extract the stress value sequence of the biaxial stress monitoring point in each cycle based on the temperature change rate group per unit time, calculate the biaxial stress increment in each cycle, record the change direction sign of the temperature change rate in the corresponding cycle, determine whether the change directions are consistent, and establish a stress-temperature co-directional change sequence;

[0107] According to the acquired temperature change rate group per unit time, read the stress measurement sequence of the biaxial stress monitoring point corresponding to each cycle, subtract the stress data between two adjacent time points in each cycle to obtain the stress increment, use the same time reference to compare the temperature change rate data points, and compare the temperature change rate value and the stress increment value at the corresponding moment point by point to determine whether the change directions of the two are consistent. The condition for the consistent direction is that the temperature change is positive and the stress increment is positive, or the temperature change is negative and the stress increment is negative. If either direction is opposite, it is considered inconsistent. For example, within a certain cycle, a certain monitoring The temperature change rate of the measuring point is +0.6 degrees Celsius per second, the stress increases from 150 MPa to 160 MPa, the stress increment is +10 MPa, and the change direction is consistent, which is marked as the same direction change. If the temperature change in another cycle is -0.4 degrees Celsius per second and the stress drops by 8 MPa, it is also recorded as the same direction. Conversely, if the temperature change is +0.5 and the stress change is -6 MPa, it is recorded as the opposite direction. By traversing the directional consistency results of all monitoring points in all cycles, the Boolean marks of consistent or opposite directions are recorded item by item to construct a complete stress-temperature same-direction change sequence to reveal the synergistic performance between the changes of two variables.

[0108] S413: Based on the stress-temperature co-directional change sequence, extract the directional consistency results under two consecutive cycles, calculate the directional consistency of the records within the two cycles, and perform a Boolean judgment. If the judgment result is a continuous co-directional mark, it is confirmed that stress-temperature rise coupling behavior exists, and the temperature-stress coupling growth trend analysis result is established;

[0109] Perform Boolean judgment on the direction consistency flags recorded in two cycles using the formula:

[0110] ;

[0111] Calculate, where Represents the coupling consistency trend value of the current cycle, Represents the consistency mark of the temperature and stress change direction of the current cycle. The value is 1 for the same direction, -1 for the opposite direction, and 0 for an invalid record. Represents the directional consistency mark of the previous cycle, Represents the absolute average value of the temperature change rate in the current cycle, Represents the average absolute value of the temperature change rate in the previous cycle, Represents the average absolute value of stress change in the current cycle, Represents the average absolute value of stress change in the previous cycle.

[0112] The current cycle is numbered g, and the previous cycle is numbered h. The temperature change direction consistency mark η is numerically determined by the synchronous relationship between the temperature change rate and the stress change direction. The temperature change rate is obtained by the difference of the series measured every 5 seconds by the temperature monitoring system. The direction is consistent and marked as 1, the opposite direction is -1, and the invalid or fluctuating period is 0.

[0113] The temperature data of the current cycle is 423.1 degrees Celsius rising to 425.8 degrees Celsius, and the stress rises from 142.6 MPa to 147.3 MPa. The temperature change rate in the 5-second sampling period is: (425.8-423.1) / 5=0.54 degrees Celsius per second, and the stress increment is 147.3-142.6=4.7 MPa, so The value is 1. In the previous cycle, the temperature increased from 421.2 to 422.5, and the stress increased from 139.2 to 142.1. The temperature change rate is (422.5-421.2) / 5=0.26, and the stress increment is 2.9. The value is 1.

[0114] The absolute value of the temperature change rate in each cycle is calculated by the average of the sampling points in the cycle. There are 12 segments in the current cycle, and the average is =0.52, the previous period is 12 periods, the average is =0.28. Average value of the absolute value of stress increment is 4.1 MPa, It is 2.7 MPa. The above data are calculated from the values ​​of adjacent sampling points in multiple cycles.

[0115] The process of entering the formula is as follows:

[0116] + =1+1=2;

[0117] | + |=|2|=2;

[0118] ;

[0119] ;

[0120] ;

[0121] The results show that the temperature and stress changes between the current cycle and the previous cycle are consistent in direction, and the average change intensity of the two variables has a high degree of coupling. The coupling consistency trend value is 0.981, which provides a reference for judging whether temperature rise and stress coupling behavior occurs between consecutive cycles. A value higher than 0.9 can be used as an identification condition for stable growth in the same direction, and trend segments are divided and marked based on this value.

[0122] The coupling consistency trend value is a characteristic metric used to measure the degree of consistency between the direction of temperature and stress changes within two consecutive cycles. It reflects the coordination of the changing trends between the periodic signals. The coupling consistency trend value is calculated by calculating the consistency flag for the direction of temperature and stress changes within each cycle (a value of 1 indicates the same direction, -1 indicates the opposite direction, and 0 indicates an invalid record) and combining it with the average absolute value of the temperature and stress change rates within the two cycles. This characteristic value comprehensively considers the consistency of direction (i.e., changes in the same direction) and the average level of change intensity, reflecting both the consistency of the direction of temperature and stress changes and the degree of consistency or difference in the magnitude of the changes. When the direction and intensity of two consecutive cycles are consistent, the coupling consistency trend value is high; otherwise, it is low. Ultimately, this characteristic value is used to identify whether the temperature and stress change trends are stable and consistent, and to determine whether there is warming coupling between the periodic signals, providing a basis for subsequent trend classification and anomaly analysis.

[0123] The operational logic of the formula is based on the joint characterization of the relationship between the consistency of the direction of temperature and stress changes and the intensity of the changes in two consecutive cycles. and The form of addition and absolute value is used to determine whether the directions remain the same within two cycles. The value range is from 0 to 2, corresponding to the three states of inconsistency, single-cycle consistency, and double-cycle consistency, which serves as the basic factor of the coupling relationship; the average temperature change rate and the average stress change in the current cycle are multiplied and squared to construct the square root product, aiming to balance the change intensity of the two physical variables and avoid overall bias caused by one of them being too high or too low. The square root structure is used to balance the dimension and numerical distribution, so that the product value regresses to a scale close to that of a single variable; the denominator is directly added by the average temperature and stress change values ​​of the previous cycle to normalize the coupling strength of the current cycle and construct a cross-cycle stable comparison structure. The formula as a whole uses a combination of multiplication, division and square roots to express the degree of coordination between directional consistency and coupling strength, ultimately forming a quantitative reflection of the coupling trend.

[0124] The specific steps of S5 are:

[0125] S511: Based on the results of the temperature-stress coupling growth trend analysis, combined with the configuration angle change rate data and the cross-sectional torsional asymmetry in the current cycle, the continuous cycle sequence corresponding to the three data items is extracted. The values ​​of any two adjacent cycles in each data sequence are subjected to difference judgment, the change signs are recorded, and the number of positive changes is counted to obtain the number of incremental matching times of the three parameters.

[0126] According to the analysis results of the temperature-stress coupling growth trend, combined with the configuration angle change rate data and the cross-section torsion asymmetry data in the current cycle, the historical record sequence of the three parameters in the continuous cycle is first extracted, the analysis window length is set to three cycles, and the numerical sequence of each parameter in the window is read. The difference operation is performed on the two adjacent cycle values ​​of each parameter, and the size relationship between the current cycle value and the previous cycle value is compared. When the value of the latter cycle is greater than the value of the previous cycle, it is recorded as a positive change mark. If it is less than, it is recorded as a negative change mark. If they are equal, no mark value is recorded. Taking cycles 6, 7, and 8 as examples, if the temperature-stress coupling trend values ​​are respectively is 0.32, 0.41, and 0.46, then period 7 is positive relative to 6, and period 8 is also positive relative to 7, and the number of positive changes of this parameter is recorded as 2 times. If the configuration angle change rate values ​​are 4.2, 4.5, and 4.4, then the 7th period is positive, the 8th period is negative, and the number of positive changes is 1 time. If the section torsional asymmetry is 0.08, 0.12, and 0.15, respectively, then two consecutive changes are positive, which is recorded as 2 times. Record the number of positive changes of the above three parameters in the current three-period analysis window respectively, and count the positive count value of each parameter in list form to obtain the number of incremental matches of the three parameters.

[0127] S512: Based on the increasing number of matches of the three parameters, it is determined whether each parameter has a positive change indicator within three consecutive cycles. The judgment threshold is set to 3 full matches and is equal to the number of matches. If the judgment result is yes, the current state is marked as a configuration trend unstable state, and a configuration instability trend state flag is obtained;

[0128] Based on the aforementioned statistically calculated number of increasing matches of the three parameters, a logical consistency judgment is performed on the values ​​in the current analysis window. The judgment threshold is set to that all three parameters have achieved at least one continuous positive change, that is, each parameter has at least one positive change mark in three cycles. The judgment condition is further strengthened and set to that all three parameters are marked as positive changes in all period pairs within three cycles, that is, each count value is equal to 2. This is a strict standard for determining whether the configuration trend is unstable. The parameter count value is compared with the set value. If all parameter count values ​​are 2, that is, the three parameters are in a positive growth state in two groups of adjacent cycles, the analysis window in the current cycle is marked as a state of unstable configuration trend. On the contrary, if any parameter does not meet this condition, the current cycle window is not marked. For example, if the count values ​​of the three parameters in a certain analysis window are 2, 2, and 2 respectively, the current state is marked as unstable. If any of them is 1, the threshold condition is not met and the state is not marked, thus obtaining a state mark of configuration instability trend.

[0129] S513: Based on the configuration instability trend state flag, extract the data cycle time point marked as the configuration trend instability state, perform a warning trigger flag write operation on the time point, output the creep state type corresponding to the current cycle, record the state type as biaxial creep configuration instability state, and issue a biaxial creep configuration instability warning message;

[0130] According to the results of the cycles marked as unstable configuration trend states, the cycle numbers of all cycles marked as unstable are extracted, the data time point corresponding to each mark is determined, the cycle index value of the time point is read and its position in the original time series is located, and the warning trigger mark writing operation is performed for each marked time point. The mark content is written into the warning system record table. The corresponding fields include timestamp, monitoring point number and mark type. At the same time, the creep state type corresponding to the cycle is output. This type is defined as biaxial creep configuration instability state. When output, it is recorded in a preset format and added to the state classification summary table. For example, if a cycle number is the 24th cycle and its three parameters are all continuously positive, the system marks the cycle as unstable configuration trend. After executing the write action, the cycle number 24, the state type "biaxial creep configuration instability" and the warning state "triggered" are written into the database to form a warning record, and finally the process of issuing biaxial creep configuration instability warning information is completed.

[0131] See also Figure 2, a real-time monitoring system for biaxial creep of nuclear fuel cladding tubes, comprising:

[0132] The angle monitoring module obtains the axial and circumferential displacement increments, constructs two-dimensional coordinates, detects the displacement change, calculates the direction vector and direction angle, compares the angle offset rates of adjacent cycles, and generates configuration angle change rate data;

[0133] The torsion analysis module extracts the four-quadrant displacement increments based on the configuration angle change rate data, constructs a data matrix, calculates the ratio of the symmetric difference to the total value, determines the growth trend, and generates the cross-sectional torsional asymmetry under biaxial stress.

[0134] The signal interference module extracts the signal interference peak value according to the cross-section torsional asymmetry, compares the baseline amplitude difference, detects the return delay, and obtains the creep response signal delay trend;

[0135] The coupling judgment module collects the temperature change rate per unit time based on the creep response signal delay trend, extracts the biaxial stress increment, determines the synchronous improvement trend, and obtains the temperature-stress coupling growth trend analysis results;

[0136] The instability warning module judges the three increasing trends based on the analysis results of the temperature-stress coupling growth trend, combines the configuration angle change rate data and the cross-sectional torsional asymmetry, triggers the warning mechanism, and issues a biaxial creep configuration instability warning information.

[0137] The above are merely preferred embodiments of the present invention and do not limit the present invention in any other form. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A real-time monitoring method for biaxial creep of nuclear fuel cladding tubes, characterized in that: The following steps are involved: S1: Obtain the axial displacement increment and circumferential displacement increment of the nuclear fuel cladding tube, detect the displacement change of adjacent monitoring points, extract the periodic direction angle value, calculate the angle offset rate, and generate the configuration angle change rate data; S2: Based on the configuration angle change rate data, detect the displacement increments of the four quadrants of the cladding tube cross section, calculate the sum of the displacement increment differences of the symmetric quadrants, determine the single-cycle cross section torsional asymmetry, judge the continuous growth trend, and generate the cross section torsional asymmetry; S3: extracting the peak value of the monitoring signal interference amplitude based on the cross-sectional torsional asymmetry, recording the direction of the offset change in the continuous cycle, analyzing the increasing trend of the interference intensity, and obtaining the creep response signal delay trend; S4: Based on the creep response signal delay trend, collecting the temperature change rate of the outer surface of the cladding tube, extracting the biaxial stress increment, judging the synchronous growth trend, and obtaining the temperature-stress coupling growth trend analysis result; S5: Based on the analysis results of the temperature-stress coupling growth trend, the configuration angle change rate data and the cross-sectional torsional asymmetry are combined to comprehensively judge the creep trend, trigger the configuration instability warning mechanism, and issue a biaxial creep configuration instability warning message.

2. The method for real-time monitoring of biaxial creep of nuclear fuel cladding tubes according to claim 1, characterized in that: The configuration angle change rate data includes a two-dimensional direction vector, a direction angle value, and an angle offset rate; the section torsional asymmetry includes the sum of the symmetrical quadrant displacement increment differences, the total value of the four-quadrant displacement increments, and a continuous growth trend; the creep response signal delay trend includes the interference amplitude peak, the offset change direction, the signal return delay characteristic value, and the delay offset trend; the temperature-stress coupling growth trend analysis results include the temperature change rate, the biaxial stress increment, and the synchronous growth trend; and the biaxial creep configuration instability warning information includes the configuration angle change rate data, the section torsional asymmetry, and the temperature-stress coupling growth trend analysis results.

3. The method for real-time monitoring of biaxial creep of nuclear fuel cladding tubes according to claim 1, characterized in that: The specific steps for obtaining the configuration angle change rate data are as follows: S111: Obtaining the displacement data of monitoring points of the nuclear fuel cladding tube in a single cycle in the reactor working environment, constructing a two-dimensional coordinate system based on the center position of the cladding tube as the origin, calling the axial displacement increment and the circumferential displacement increment values ​​of each monitoring point in the current cycle, calculating the relative displacement change of each adjacent monitoring point in the two-dimensional coordinate system, and generating relative displacement increment data; S112: Based on the relative displacement increment data, performing a combined calculation of the axial and circumferential components of the relative displacement changes of adjacent monitoring points in the two-dimensional coordinate system, obtaining the two-dimensional direction vector value corresponding to each pair of monitoring points, calling all direction vectors in the current cycle, and obtaining the direction angle value of each direction vector according to the coordinate system origin reference benchmark to generate a direction angle data set; S113: Read the directional angle data group of the current cycle and the previous cycle, and for the directional angle value under the corresponding monitoring point number, count the change in the directional angle of each monitoring point, and calculate the angle offset rate corresponding to each monitoring point based on the time interval between adjacent cycles to generate configuration angle change rate data.

4. The method for real-time monitoring of biaxial creep of nuclear fuel cladding tubes according to claim 1, characterized in that: The specific steps for obtaining the cross-sectional torsional asymmetry are as follows: S211: Based on the configuration angle change rate data, detecting displacement increments of the cladding tube cross section in four quadrants under the reactor operation state, arranging the displacement increments of the corresponding monitoring points in each quadrant in order from the first quadrant to the fourth quadrant, sequentially filling the displacement increments of the corresponding monitoring points in each quadrant into a two-dimensional array structure, and constructing a quadrant displacement increment matrix with the quadrant position as the index dimension; S212: Based on the quadrant displacement increment matrix, performing paired subtraction on the displacement increments in the first and third quadrants, and the second and fourth quadrants, respectively, calculating the displacement increment difference between the two groups of symmetrical quadrants, and simultaneously obtaining the sum of all displacement increment values ​​in the four quadrants, calculating the ratio of the sum of the differences to the total displacement value, and obtaining the torsional asymmetry of the single-period section; S213: Read the single-cycle cross-section torsional asymmetry of three consecutive cycles, arrange the asymmetry values ​​corresponding to each cycle in chronological order, and judge the trend of the value change of the three cycles. If the asymmetry values ​​of the last three cycles are in a continuous rising state, the evolution state is recorded as torsional imbalance, and the cross-section torsional asymmetry is established.

5. The method for real-time monitoring of biaxial creep of nuclear fuel cladding tubes according to claim 1, characterized in that: The specific steps for obtaining the creep response signal delay trend are: S311: Extracting the interference amplitude data of each cycle in the biaxial creep monitoring signal channel of the cladding tube based on the cross-sectional torsional asymmetry, detecting the amplitude change of the interference signal in each cycle and obtaining the amplitude peak, calling the channel reference signal amplitude as a reference value, performing a comparison between the peak signal of each cycle and the reference value, recording the direction of the offset change in each cycle, and obtaining a cycle amplitude offset direction sequence; S312: Based on the periodic amplitude offset direction sequence, the consistency of the interference amplitude change direction in consecutive periods is determined, the amplitude change values ​​are extracted and arranged in a time series, the amplitude differences within any three consecutive periods are accumulated and compared with the zero deviation value to determine whether the signs are consistent, and the interference signal strength change trend is obtained; S313: Based on the change trend of the interference signal strength, the start time and end time of the signal return in each cycle are extracted, the return delay characteristic value within the cycle is calculated, and the multi-cycle delay time values ​​are arranged in chronological order. The change in the delay time of each cycle is obtained, the sign judgment and sequence coherence identification are performed on the change, and the creep response signal delay trend is established.

6. The method for real-time monitoring of biaxial creep of nuclear fuel cladding tubes according to claim 5, characterized in that: The return delay characteristic value within the period is calculated using the formula: ； Calculate, where Representative The return delay characteristic value of the cycle, Representative The start time of the periodic signal, Representative The end time of the periodic signal, Representative The amplitude change of the cycle, Represents the sum of the absolute values ​​of the amplitude changes of the current and previous two cycles, 、 、 They represent the absolute value of the difference between the current period and the amplitude change during the previous two weeks.

7. The method for real-time monitoring of biaxial creep of nuclear fuel cladding tubes according to claim 1, characterized in that: The specific steps for obtaining the temperature-stress coupling growth trend analysis results are as follows: S411: Based on the creep response signal delay trend, collecting temperature measurement data per unit time at each monitoring point on the outer surface of the cladding tube, extracting temperature change values ​​for consecutive time periods within each cycle, and calculating the temperature change rate in each cycle in combination with the time interval to obtain a temperature change rate per unit time group; S412: Extracting a stress value sequence of the biaxial stress monitoring point in each cycle based on the temperature change rate group per unit time, calculating the biaxial stress increment in each cycle, recording the sign of the change direction of the temperature change rate in the corresponding cycle, determining whether the change directions of the two are consistent, and establishing a stress-temperature co-directional change sequence; S413: Based on the stress-temperature unidirectional change sequence, extract the directional consistency results under two consecutive cycles, calculate the directional consistency recorded in the two cycles and perform a Boolean judgment. If the judgment result is a continuous unidirectional mark, it is confirmed that stress-temperature rise coupling behavior exists, and the temperature-stress coupling growth trend analysis result is established.

8. The method for real-time monitoring of biaxial creep of nuclear fuel cladding tubes according to claim 7, characterized in that: A Boolean judgment is performed on the direction consistency flags recorded in the two cycles using the formula: ； Calculate, where Represents the coupling consistency trend value of the current cycle, Represents the consistency mark of the temperature and stress change direction of the current cycle. The value is 1 for the same direction, -1 for the opposite direction, and 0 for an invalid record. Represents the directional consistency mark of the previous cycle, Represents the absolute average value of the temperature change rate in the current cycle, Represents the average absolute value of the temperature change rate in the previous cycle, Represents the average absolute value of stress change in the current cycle, Represents the average absolute value of stress change in the previous cycle.

9. The method for real-time monitoring of biaxial creep of nuclear fuel cladding tubes according to claim 1, characterized in that: The specific steps for obtaining the biaxial creep configuration instability warning information are as follows: S511: Based on the analysis results of the temperature-stress coupling growth trend, combined with the configuration angle change rate data and the cross-sectional torsional asymmetry in the current cycle, a continuous cycle sequence corresponding to the three data items is extracted, and the values ​​of any two adjacent cycles in each data sequence are subjected to difference judgment. The change signs are recorded and the number of positive changes is counted to obtain the number of incremental matching of the three parameters. S512: Based on the number of incremental matches of the three parameters, determine whether each parameter has a positive change flag within three consecutive cycles, set a judgment threshold, and perform a judgment equal to the number of matches. If the judgment result is yes, mark the current state as a configuration trend unstable state, and obtain a configuration instability trend state flag; S513: According to the configuration instability trend state mark, extract the data period time point marked as the configuration trend instability state, perform the warning trigger mark write operation on the time point, and output the creep state type corresponding to the current period, record the state type as the biaxial creep configuration instability state, and issue the biaxial creep configuration instability warning information.

10. A real-time monitoring system for biaxial creep of nuclear fuel cladding tubes, characterized in that: The system is used to implement the real-time monitoring method for biaxial creep of nuclear fuel cladding tubes according to any one of claims 1 to 9, and the system comprises: The angle monitoring module obtains the axial and circumferential displacement increments, constructs two-dimensional coordinates, detects the displacement change, calculates the direction vector and direction angle, compares the angle offset rates of adjacent cycles, and generates configuration angle change rate data; The torsion analysis module extracts the four-quadrant displacement increments based on the configuration angle change rate data, constructs a data matrix, calculates the ratio of the symmetric difference to the total value, determines the growth trend, and generates the cross-sectional torsional asymmetry under biaxial stress; The signal interference module extracts the signal interference peak value according to the cross-section torsional asymmetry, compares the reference amplitude difference, detects the return delay, and obtains the creep response signal delay trend; The coupling determination module collects the temperature change rate per unit time based on the delay trend of the creep response signal, extracts the biaxial stress increment, determines the synchronous improvement trend, and obtains the temperature-stress coupling growth trend analysis result; The instability warning module determines the increasing trend based on the temperature-stress coupling growth trend analysis result, combines the configuration angle change rate data and the cross-sectional torsional asymmetry, triggers the warning mechanism, and issues a biaxial creep configuration instability warning information.

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