Temperature compensation method, temperature compensation device, and fuel assembly film thickness measurement system

Abstract

The present application relates to a temperature compensation method, a temperature compensation device and a fuel assembly film thickness measurement system, the method comprising: obtaining measurement signals output by an eddy current sensor when detecting film thickness of a calibration piece at different temperatures and temperature change data of the eddy current sensor to obtain measurement data; generating a temperature compensation function according to the measurement data; obtaining a current output signal of the eddy current sensor when measuring film thickness of a fuel assembly and a current temperature of the eddy current sensor; and compensating the current output signal according to the current temperature and the temperature compensation function. The present application can compensate the measurement signals output by the eddy current sensor, thereby assisting workers to quickly and accurately measure the film thickness of the fuel assembly.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing technology, and in particular to a temperature compensation method, a temperature compensation device, and a fuel assembly film thickness measurement system. Background Technology

[0002] To ensure the safety of nuclear power plants, the thickness of the film layer on the surface of fuel assemblies needs to be measured regularly. Currently, the common method is to measure the film thickness using eddy current sensors. After the fuel assemblies are removed from the reactor, they need to be cooled in the spent fuel pool. If the fuel assemblies are measured before reaching room temperature, the high temperature will cause changes in the physical and electrical properties of the film layer (such as thickness and conductivity). Simultaneously, the performance of the eddy current sensor will also change with temperature, leading to instability and increased error in immediate film thickness measurements. Furthermore, environmental factors during film layer measurement (such as electromagnetic interference) further increase measurement noise. Currently, nuclear power plants urgently need a solution to improve the measurement results of eddy current sensors. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a temperature compensation method, a temperature compensation device, and a fuel assembly film thickness measurement system.

[0004] The technical solution adopted by this invention to solve its technical problem is: constructing a temperature compensation method, comprising: The measurement data is obtained by acquiring the measurement signal output by the eddy current sensor when detecting the film thickness of the calibration component at different temperatures, as well as the temperature change data of the eddy current sensor; A temperature compensation function is generated based on the measurement data; Acquire the current output signal of the eddy current sensor when measuring the thickness of the fuel assembly film, and the current temperature of the eddy current sensor; The current output signal is compensated based on the current temperature and the temperature compensation function.

[0005] Preferably, acquiring the measurement signal output by the eddy current sensor when detecting the film thickness of the calibration component at different temperatures, and the temperature change data of the eddy current sensor, includes: The film thickness of the calibration piece after preheating is measured by contact with an eddy current sensor. After the eddy current sensor contacts the calibration element, the measurement signal output by the eddy current sensor and the temperature change data of the eddy current sensor are acquired to obtain measurement data.

[0006] Preferably, the process of measuring the film thickness of the preheated calibration element by contacting it with an eddy current sensor further includes: The eddy current sensor contacts the middle section of the calibration component and remains fixed.

[0007] Preferably, generating the temperature compensation function based on the measurement data includes: Based on the film thickness of the calibration component and the quadratic fitting method, curve fitting is performed on the real and imaginary signals in the measurement data to obtain the real temperature error curve and the imaginary temperature error curve.

[0008] Preferably, the real part temperature error curve is expressed as: E(RE) = a1T 2 + b1T+c1, E(RE) represents the real part temperature error value, a1 represents the first coefficient, b1 represents the second coefficient, c1 represents the third coefficient, and T represents the current temperature; The imaginary part temperature error curve is expressed as: E(Im) = a²T 2 + b2T+c2, E(Im) represents the imaginary part temperature error value, a2 represents the fourth coefficient, b2 represents the fifth coefficient, and c2 represents the sixth coefficient.

[0009] Preferably, the step of compensating the current output signal based on the current temperature and the temperature compensation function includes: Substitute the current temperature into the real part temperature error curve and the imaginary part temperature error curve respectively to obtain the real part temperature error value and the imaginary part temperature error value corresponding to the current temperature; The real part of the current output signal is subtracted from the real part temperature error value to obtain the compensated real part. The imaginary part of the current output signal is subtracted from the imaginary part temperature error value to obtain the compensated imaginary part.

[0010] The present invention also constructs a temperature compensation device, comprising: Eddy current sensor, used to acquire the current output signal of the eddy current sensor when measuring the thickness of the film layer of the fuel assembly; The data acquisition unit is used to acquire the measurement signal output by the eddy current sensor when detecting the film thickness of the calibration component at different temperatures, as well as the temperature change data of the eddy current sensor, to obtain measurement data; A calibration unit is used to generate a temperature compensation function based on the measurement data; A temperature sensor is used to acquire the current temperature of the eddy current sensor when the eddy current sensor is measuring the thickness of the film layer of the fuel assembly; The compensation unit is used to compensate the current output signal according to the current temperature and the temperature compensation function.

[0011] Preferably, the eddy current sensor includes a housing, the housing having a first end face for contacting the fuel assembly and a second end face opposite to the first end face, and the housing having a detection coil disposed near the first end face and a reference coil disposed near the second end face.

[0012] Preferably, the temperature sensor is disposed inside the housing and close to the detection coil.

[0013] Furthermore, the present invention also constructs a fuel assembly film thickness measurement system, comprising: The temperature compensation device described above; and The thickness calculation module is used to calculate the thickness of the film being measured based on the compensated real part and the compensated imaginary part.

[0014] Implementing this invention has the following beneficial effects: it can compensate for the measurement signal output by the eddy current sensor, thereby assisting staff in quickly and accurately measuring the film thickness of fuel assemblies, which plays a positive role in improving the safety of nuclear power plants. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a flowchart of a temperature compensation method in some embodiments of the present invention; Figure 2 These are schematic diagrams of the temperature compensation device in some embodiments of the present invention; Figure 3 This is a schematic diagram of the structure of an eddy current sensor in some embodiments of the present invention. Detailed Implementation

[0016] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0017] It should be noted that the flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0018] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0019] Figure 1This is a flowchart illustrating the temperature compensation method in some embodiments of the present invention. This method can compensate for the measurement signal output by the eddy current sensor, thereby assisting personnel in quickly and accurately measuring the film thickness of fuel assemblies, playing a positive role in improving the safety of nuclear power plants.

[0020] like Figure 1 As shown, the temperature compensation method may include steps S10, S20, S30, and S40.

[0021] Step S10 includes: acquiring the measurement signal output by the eddy current sensor when detecting the film thickness of the calibration component at different temperatures, and the temperature change data of the eddy current sensor, to obtain measurement data. The calibration component can be a fuel assembly with a known film thickness or another fuel rod model with a known film thickness.

[0022] In some embodiments, the measurement data can be obtained by performing the following steps: contacting the calibrator with an eddy current sensor to measure the film thickness of the preheated calibrator; after the eddy current sensor contacts the calibrator, acquiring the measurement signal output by the eddy current sensor and the temperature change data of the eddy current sensor to obtain the measurement data.

[0023] Specifically, the fuel assembly, when first moved to the spent fuel pool, retains residual heat and can be considered a heat source. Similarly, after the calibration component is heated, its temperature remains relatively stable for a certain period, also serving as a heat source. This simulates the state of the fuel assembly immediately after being moved to the spent fuel pool, helping to improve the confidence level of the measurement data. When the eddy current sensor contacts the calibration component, the calibration component heats the eddy current sensor, causing it to gradually heat up. In this embodiment, the measurement signal output by the eddy current sensor after contacting the calibration component (characterizing the film thickness) and the temperature change data during the heating process of the eddy current sensor can be recorded. By combining the measurement signal output by the eddy current sensor during this process and the temperature change data, the aforementioned measurement data can be obtained.

[0024] In addition, the calibration component can be preheated using existing heating devices (such as water bath heating devices). To ensure that the temperature compensation function can be applied over a sufficiently wide temperature range, the temperature of the calibration component after heating is preferably greater than the maximum temperature of the fuel assembly after it is moved to the spent fuel pool during normal operation. This ensures that the temperature compensation function determined in subsequent steps can be applied to the temperature of the fuel assembly during field testing.

[0025] Since eddy current sensors reach thermal equilibrium after heating to a certain temperature, in order to reduce the amount of data, in some embodiments, the measurement signal output by the eddy current sensor and the temperature change data of the eddy current sensor can be obtained by performing the following steps: setting the moment when the eddy current sensor contacts the calibration component as the start time of the measurement data; after the eddy current sensor contacts the calibration component, monitoring the temperature change data of the eddy current sensor, and setting the moment when the heating rate of the eddy current sensor is less than the set temperature change rate as the end time of the measurement data; obtaining the measurement signal output by the eddy current sensor as a function of temperature during the period from the start time to the end time to obtain the measurement data.

[0026] Specifically, after the eddy current sensor comes into contact with the calibration component, the temperature change data of the eddy current sensor is monitored in real time. The real-time heating rate of the eddy current sensor is calculated based on the temperature change data. Understandably, the greater the temperature difference between the eddy current sensor and the calibration component, the greater the heating rate of the eddy current sensor. When the heating rate is less than the set temperature change rate, it indicates that the temperature of the eddy current sensor tends to stabilize, and it can be determined that the eddy current sensor has reached thermal equilibrium. This moment can be set as the end time of the measurement data.

[0027] In some embodiments, during the process of contacting and measuring the film thickness of the calibration component using an eddy current sensor, the following steps may also be performed: contacting the middle section of the calibration component with the eddy current sensor and keeping the relative position of the eddy current sensor and the calibration component fixed. It should be noted that the surface temperature of the calibration component (which may be an existing fuel assembly with accurately measured film thickness, in the form of a rod) is uneven, while the temperature at the middle section of the calibration component is relatively high and the temperature distribution is relatively uniform. Therefore, selecting the middle section as the sampling point for collecting measurement data helps to reduce the adverse effects of uneven surface temperature of the fuel assembly, helps to ensure the reliability of the data when collecting measurement data in subsequent steps, and plays a positive role in improving compensation accuracy.

[0028] Step S20 includes: generating a temperature compensation function based on the measurement data.

[0029] In some embodiments, a temperature compensation function can be generated based on the measurement data by performing the following steps: curve fitting of the real part signal and the imaginary part signal in the measurement data based on the film thickness of the calibration component and a quadratic term fitting method, respectively, to obtain the real part temperature error curve and the imaginary part temperature error curve.

[0030] In this embodiment, based on the measurement signal in the measurement data and existing thickness measurement algorithms (refer to existing schemes for measuring film thickness based on eddy current sensors), the theoretical real thickness and theoretical imaginary thickness of the same film thickness calibration component at different temperatures can be calculated. Next, the film thickness of the calibration component is measured in advance at room temperature using an eddy current sensor to obtain the standard real thickness and standard imaginary thickness. Then, based on the standard real thickness and the theoretical real thickness at different temperatures, the error between the standard real thickness and the theoretical real thickness at each temperature is calculated, as is the error between the standard imaginary thickness and the theoretical imaginary thickness at each temperature. Finally, based on the quadratic term fitting method and the error between the standard real thickness and the theoretical real thickness at different temperatures, a real temperature error curve representing the change of the real signal with temperature can be fitted. Similarly, based on the quadratic term fitting method and the error between the standard imaginary thickness and the theoretical imaginary thickness at different temperatures, an imaginary temperature error curve representing the change of the imaginary signal with temperature can be fitted.

[0031] In some embodiments, the real part temperature error curve can be expressed as: E(RE) = a1T 2 + b1T+c1, E(RE) represents the real part temperature error value, a1 represents the first coefficient, b1 represents the second coefficient, c1 represents the third coefficient, and T represents the current temperature. The imaginary part temperature error curve can be represented as: E(Im)=a2T 2 + b2T+c2, E(Im) represents the imaginary part of the temperature error value, a2 represents the fourth coefficient, b2 represents the fifth coefficient, and c2 represents the sixth coefficient. Understandably, in this embodiment, the values ​​of the first to sixth coefficients can be calculated based on the measurement data using quadratic fitting methods such as the least squares method.

[0032] It should be noted that the membrane thickness measurement of the fuel assembly is carried out at the spent fuel pool. Electromagnetic interference, air pressure, humidity and other factors at the spent fuel pool site may affect the accuracy of the membrane thickness measurement. The temperature compensation function calibration process usually only takes a few minutes (most of the time is spent waiting for the eddy current sensor to reach thermal equilibrium), which has the characteristics of high efficiency. Therefore, in some embodiments, steps S10 and S20 can be performed once before each measurement of the membrane thickness of the fuel assembly, which is equivalent to calibrating the temperature compensation function once in the current environment. In this way, the temperature compensation function takes into account the current environmental factors, which helps to further improve the compensation accuracy.

[0033] Step S30 includes: acquiring the current output signal of the eddy current sensor when measuring the film thickness of the fuel assembly, and the current temperature of the eddy current sensor. In this step, the current temperature of the fuel assembly measured by the eddy current sensor can be acquired using an existing temperature sensor.

[0034] Step S40 includes: compensating the current output signal based on the current temperature and a temperature compensation function.

[0035] In some embodiments, the current output signal can be compensated according to the current temperature and the temperature compensation function by performing the following steps: substituting the current temperature into the real part temperature error curve and the imaginary part temperature error curve respectively to obtain the real part temperature error value and the imaginary part temperature error value corresponding to the current temperature; subtracting the real part of the current output signal from the real part temperature error value to obtain the compensated real part; and subtracting the imaginary part of the current output signal from the imaginary part temperature error value to obtain the compensated imaginary part.

[0036] Specifically, the expression for the real part after compensation can be: V C_Re = V Re –(a1T 2 + b1T+c1), V C_Re V represents the real part after compensation. Re This represents the real part of the current output signal. The expression for the compensated imaginary part can be: V C_Im = V Im –(a2T 2 + b2T+c2), V C_Im V represents the imaginary part after compensation. Im This represents the imaginary part of the current output signal.

[0037] In some embodiments, the temperature compensation method may further include: step S50, calculating the thickness of the film layer under test based on the compensated real part and the compensated imaginary part. It should be noted that measuring the thickness of the film layer in the cockpit based on the output of the eddy current sensor is a mature technology, and specific details can be found in existing technologies, which will not be elaborated here.

[0038] Please refer to Tables 1 and 2. By compensating for the measurement signal output by the eddy current sensor, the present invention can significantly reduce the error in the measurement of the real part thickness and the imaginary part thickness, thereby effectively improving the measurement accuracy of the film thickness of the fuel assembly.

[0039] Table 1. Results of the real voltage (Re) Table 2 Results of the imaginary voltage (Im) like Figure 2 As shown, the present invention also provides a temperature compensation device, which may include a data acquisition unit 1, a calibration unit 2, an eddy current sensor 3, a temperature sensor 4, and a compensation unit 5.

[0040] Data acquisition unit 1 is used to acquire the measurement signal output by eddy current sensor 3 when detecting the film thickness of the calibration component at different temperatures, as well as the temperature change data of eddy current sensor 3, to obtain measurement data. The specific data acquisition process can be referred to above, and will not be repeated here.

[0041] Calibration unit 2 is used to generate a temperature compensation function based on the measurement data; Eddy current sensor 3 is used to acquire the current output signal of eddy current sensor 3 when measuring the thickness of the film layer of fuel assembly.

[0042] Temperature sensor 4 is used to acquire the current temperature of eddy current sensor 3 when eddy current sensor 3 is measuring the thickness of the fuel assembly film. Temperature sensor 4 can be a PT100 temperature sensor.

[0043] Compensation unit 5 is used to compensate the current output signal based on the current temperature and a temperature compensation function. The compensation process implemented by compensation unit 5 can be referred to above, and will not be repeated here.

[0044] In some embodiments, such as Figure 3 As shown, the eddy current sensor 3 may include a housing 31, which includes a first end face 311 for contacting the fuel assembly and a second end face 312 opposite to the first end face 311. The housing 31 is provided with a detection coil 313 near the first end face 311 and a reference coil 314 near the second end face 312.

[0045] In this embodiment, the reference coil 314 is used to detect background noise, and the differential signal obtained by subtracting the output signal of the reference coil 314 from the output signal of the detection coil 313 is the output signal of the eddy current sensor 3.

[0046] In some embodiments, such as Figure 3 As shown, the temperature sensor 4 is disposed inside the housing 31 and close to the detection coil 313.

[0047] The present invention also provides a fuel assembly film thickness measurement system, which includes a thickness calculation module and a temperature compensation device provided in the embodiments of the present invention. The thickness calculation module is used to calculate the thickness of the film being measured based on the compensated real part and the compensated imaginary part.

[0048] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0049] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0050] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0051] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A temperature compensation method, characterized in that, include: Before each measurement of the film thickness of the fuel assembly, the measurement signal output by the eddy current sensor when detecting the film thickness of the calibration component at different temperatures and the temperature change data of the eddy current sensor are obtained to obtain the measurement data. A temperature compensation function is generated based on the measurement data; Acquire the current output signal of the eddy current sensor when measuring the thickness of the fuel assembly film, and the current temperature of the eddy current sensor; The current output signal is compensated based on the current temperature and the temperature compensation function; The step of generating a temperature compensation function based on the measurement data includes: performing curve fitting on the real part signal and the imaginary part signal in the measurement data based on the film thickness of the calibration component and a quadratic term fitting method, respectively, to obtain the real part temperature error curve and the imaginary part temperature error curve.

2. The temperature compensation method according to claim 1, characterized in that, The acquisition of the measurement signal output by the eddy current sensor when detecting the film thickness of the calibration component at different temperatures, and the temperature change data of the eddy current sensor, includes: The film thickness of the calibration piece after preheating is measured by contact with an eddy current sensor. After the eddy current sensor contacts the calibration element, the measurement signal output by the eddy current sensor and the temperature change data of the eddy current sensor are acquired to obtain measurement data.

3. The temperature compensation method according to claim 2, characterized in that, The process of measuring the film thickness of the preheated calibration element by contacting it with an eddy current sensor also includes: The eddy current sensor contacts the middle section of the calibration component and remains fixed.

4. The temperature compensation method according to claim 2, characterized in that, The real part temperature error curve is expressed as: E(RE)=a1T 2 + b1T+c1, E(RE) represents the real part temperature error value, a1 represents the first coefficient, b1 represents the second coefficient, c1 represents the third coefficient, and T represents the current temperature; The imaginary part temperature error curve is expressed as: E(Im) = a²T 2 + b2T+c2, E(Im) represents the imaginary part temperature error value, a2 represents the fourth coefficient, b2 represents the fifth coefficient, and c2 represents the sixth coefficient.

5. The temperature compensation method according to claim 4, characterized in that, The step of compensating the current output signal based on the current temperature and the temperature compensation function includes: Substitute the current temperature into the real part temperature error curve and the imaginary part temperature error curve respectively to obtain the real part temperature error value and the imaginary part temperature error value corresponding to the current temperature; The real part of the current output signal is subtracted from the real part temperature error value to obtain the compensated real part. The imaginary part of the current output signal is subtracted from the imaginary part temperature error value to obtain the compensated imaginary part.

6. A temperature compensation device, characterized in that, include: Eddy current sensor, used to acquire the current output signal of the eddy current sensor when measuring the thickness of the film layer of the fuel assembly; The data acquisition unit is used to acquire the measurement signal output by the eddy current sensor when detecting the film thickness of the calibration component at different temperatures and the temperature change data of the eddy current sensor before each measurement of the film thickness of the fuel assembly, so as to obtain the measurement data. The calibration unit is used to generate a temperature compensation function based on the measurement data, including: performing curve fitting on the real part signal and the imaginary part signal in the measurement data based on the film thickness of the calibration component and a quadratic term fitting method, respectively, to obtain the real part temperature error curve and the imaginary part temperature error curve; A temperature sensor is used to acquire the current temperature of the eddy current sensor when the eddy current sensor is measuring the thickness of the film layer of the fuel assembly; The compensation unit is used to compensate the current output signal according to the current temperature and the temperature compensation function.

7. The temperature compensation device according to claim 6, characterized in that, The eddy current sensor includes a housing, which includes a first end face for contacting the fuel assembly and a second end face opposite to the first end face. The housing contains a detection coil disposed near the first end face and a reference coil disposed near the second end face.

8. The temperature compensation device according to claim 7, characterized in that, The temperature sensor is disposed inside the housing and close to the detection coil.

9. A fuel assembly film thickness measurement system, characterized in that, include: The temperature compensation device as described in any one of claims 6 to 8; as well as The thickness calculation module is used to calculate the thickness of the film being measured based on the compensated real part and the compensated imaginary part.

Images