Fuel assembly oxide film thickness measuring device and temperature compensation method thereof

Abstract

The present application relates to fuel assembly oxide film thickness measuring device and its temperature compensation method, and the method comprises the following steps: obtaining the measuring thickness output by the fuel assembly oxide film thickness measuring device when measuring the standard thickness piece at the first set temperature, and recording it as the first high-temperature standard thickness; obtaining the measuring thickness output by the fuel assembly oxide film thickness measuring device when measuring the standard thickness piece from the first set temperature to the second set temperature, and recording it as the second high-temperature standard thickness; fitting the compensation amount linear fitting function related to the real-time temperature of the measuring device according to the first set temperature, the first high-temperature standard thickness, the second set temperature and the second high-temperature standard thickness; obtaining the real-time temperature of the fuel assembly oxide film thickness measuring device; and compensating the measuring thickness output by the fuel assembly oxide film thickness measuring device according to the real-time temperature and the compensation amount linear fitting function. The present application realizes the temperature compensation of the measuring thickness, and improves the measurement accuracy of the measuring device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thin film thickness measurement, in particular to a fuel assembly oxide film thickness measurement device and a temperature compensation method thereof. BACKGROUND

[0002] The fuel assembly is an important device for controlling the power of the reactor. Since it works in a high-temperature environment for a long time, an oxide film with a certain thickness is easily formed on its surface, which affects the working efficiency of the fuel assembly. In order to accurately control the reactor, the nuclear power plant needs to measure the thickness of the oxide film of the fuel assembly in order to optimize the reactor control logic and achieve precise control of the reactor power. However, since the fuel assembly is close to the reactor and the temperature is high, the measurement accuracy of the existing thin film thickness measurement device is greatly affected by the temperature of the device, resulting in poor oxide film measurement accuracy, which affects the stability of the reactor power control. Therefore, the nuclear power plant urgently needs a scheme that can compensate for the temperature of the measured thickness. SUMMARY

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

[0004] The technical solution adopted by the present application to solve the technical problem is: a temperature compensation method is constructed for a fuel assembly oxide film thickness measurement device, the method comprising:

[0005] Obtaining the measurement thickness output by the fuel assembly oxide film thickness measurement device when measuring a standard thickness piece at a first set temperature, and recording it as a first high-temperature standard thickness;

[0006] Obtaining the measurement thickness output by the fuel assembly oxide film thickness measurement device when measuring the standard thickness piece from the first set temperature to a second set temperature, and recording it as a second high-temperature standard thickness;

[0007] Fitting a compensation amount linear fitting function related to the real-time temperature of the measurement device according to the first set temperature, the first high-temperature standard thickness, the second set temperature and the second high-temperature standard thickness;

[0008] Obtaining the real-time temperature of the fuel assembly oxide film thickness measurement device;

[0009] Compensating the measurement thickness output by the fuel assembly oxide film thickness measurement device according to the real-time temperature and the compensation amount linear fitting function.

[0010] Preferably, the compensation amount linear fitting function is:

[0011] ΔT=(T-T3)*(h3-h4) / (T2-T3);

[0012] Wherein, ΔT represents the compensation amount, T represents the real-time temperature, T3 represents the second set temperature, h3 represents the first high-temperature standard thickness, T2 represents the first set temperature, and h4 represents the second high-temperature standard thickness;

[0013] The expression for measuring thickness is:

[0014] h=h1+ΔT, where h represents the measured thickness after compensation, and h1 represents the measured thickness before compensation.

[0015] Preferably, the first set temperature is configured to be close to or the same as the ambient temperature of the fuel assembly being tested, and the second set temperature is equal to the product of the first set temperature and a set coefficient, wherein the range of the set coefficient is 0.92 to 0.98.

[0016] The present invention also constructs a fuel assembly oxide film thickness measuring device, comprising:

[0017] The probe is used to emit a test alternating magnetic field acting on the oxide film of the fuel assembly under test, and output a measurement signal capable of representing the thickness of the oxide film according to the thickness of the oxide film;

[0018] a measuring unit, configured to output a measured thickness according to the measurement signal;

[0019] A temperature sensor, configured to output a real-time temperature according to the temperature of the probe;

[0020] The compensation unit includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the temperature compensation method described above are implemented.

[0021] Preferably, the probe comprises a housing, a sleeve, an elastic member, a cover, a standard reference member and an amplifying circuit;

[0022] The housing includes an opening, the first end of the sleeve is inserted into the housing through the opening, and the second end of the sleeve is protruded from the opening under the support of the elastic member, the cover is disposed on the second end of the sleeve, and the standard reference member is disposed in the sleeve and cooperates with the cover to form a cavity;

[0023] The cavity is provided with a detection coil disposed near the cover and a reference coil disposed near the standard reference piece. When the detection coil is excited, the magnetic field generated by the detection coil acts on the oxide film through the cover and generates a detection signal according to the thickness of the oxide film. When the reference coil is excited, the magnetic field generated by the reference coil acts on the standard reference piece and generates a reference signal according to the thickness of the standard reference piece.

[0024] The amplification circuit is electrically connected to the detection coil and the reference coil to differentially amplify the detection signal and the reference signal to obtain a measurement signal representing the thickness of the oxide film.

[0025] Preferably, the shell comprises a first cylinder and a locking member;

[0026] The inner wall of the first end of the first cylinder extends inwardly to form the opening;

[0027] The locking member is arranged on the second end of the first cylinder, and the locking member comprises a through hole;

[0028] The sleeve comprises a second cylinder, a third cylinder and a fourth cylinder;

[0029] The cover is arranged on the first end of the second cylinder, the standard reference member is arranged on the second end of the second cylinder, the third cylinder is arranged through the through hole of the locking member, the fourth cylinder is mechanically connected between the second cylinder and the third cylinder, and the outer diameter of the fourth cylinder is greater than the hole diameter of the opening, so that the fourth cylinder is limited to slide in the shell and drives the second cylinder and the third cylinder during the sliding;

[0030] The elastic member comprises a spring, the spring is sleeved outside the third cylinder and is arranged in compression between the fourth cylinder and the locking member to make the cover protrude out of the opening by the elastic force.

[0031] Preferably, the second cylinder, the third cylinder and the fourth cylinder are in an integrated structure, the inner wall of the sleeve is provided with an isolation cylinder for preventing the coil from contacting the sleeve, and the inner wall of the isolation cylinder is provided with a heat insulation film; wherein the heat insulation film is made of a non-metal heat insulation material, and the isolation cylinder is made of plastic.

[0032] Preferably, the cavity is further provided with a coil skeleton for fixing the detection coil and the reference coil.

[0033] Preferably, the fuel assembly oxide film thickness measuring device further comprises an excitation unit, a first matching inductor and a second matching inductor;

[0034] One way of the excitation unit is electrically connected to the detection coil through the first matching inductor, and the other way is electrically connected to the reference coil through the second matching inductor to provide excitation signals to the detection coil and the reference coil;

[0035] The connection points of the first matching inductor and the detection coil and the connection points of the second matching inductor and the reference coil are electrically connected to the amplification circuit.

[0036] Preferably, the amplification circuit comprises a differential amplification circuit and a non-inverting amplification circuit;

[0037] The positive terminal of the differential amplification circuit is electrically connected to the connection point of the first matching inductor and the detection coil to access the detection signal, the negative terminal is electrically connected to the connection point of the second matching inductor and the reference coil to access the reference signal, and the output terminal is electrically connected to the non-inverting amplification circuit.

[0038] The non-inverting amplification circuit is electrically connected to the measurement unit, and is configured to amplify the differential signal output by the differential amplification circuit to obtain the measurement signal.

[0039] The present application has the following beneficial effects: a temperature compensation method is provided, which obtains a first high-temperature standard measurement thickness output by a fuel assembly oxide film thickness measurement device when measuring the standard thickness piece at a first set temperature, and obtains a second high-temperature measurement thickness output by the fuel assembly oxide film thickness measurement device when measuring the standard thickness piece from the first set temperature to a second set temperature; then a compensation amount linear fitting function related to the real-time temperature of the measurement device is fitted according to the first set temperature, the first high-temperature standard thickness, the second set temperature and the second high-temperature standard thickness; finally, the measurement thickness output by the fuel assembly oxide film thickness measurement device is compensated according to the real-time temperature, the measurement thickness of the fuel assembly oxide film thickness measurement device is temperature-compensated, and the measurement accuracy of the measurement device is significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0040] The present application will be further described below with reference to the accompanying drawings and examples, in which:

[0041] Figure 1 is a program flowchart of the temperature compensation method in some embodiments of the present application;

[0042] Figure 2 is a circuit structure block diagram of the fuel assembly oxide film thickness measurement device in some embodiments of the present application;

[0043] Figure 3 is a structure schematic diagram of the probe in some embodiments of the present application;

[0044] Figure 4 is a circuit principle diagram of the fuel assembly oxide film thickness measurement device in some embodiments of the present application;

[0045] Figure 5 is a circuit principle diagram of the amplification circuit in some embodiments of the present application. DETAILED DESCRIPTION

[0046] In order to have a clearer understanding of the technical features, objects and effects of the present application, the specific embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0047] It should be noted that the flowcharts shown in the drawings are only illustrative, and do not necessarily include all the contents and operations / steps, nor are they necessarily executed in the order described. For example, some operations / steps can be further decomposed, and some operations / steps can be combined or partially combined, so the actual execution order can be changed according to the actual situation.

[0048] The block diagrams shown in the drawings are only functional entities, and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software form, or in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0049] The present application provides a temperature compensation method for a fuel assembly oxide film thickness measuring device, which can compensate the measured thickness output by the fuel assembly oxide film thickness measuring device according to the temperature of the fuel assembly oxide film thickness measuring device, thereby improving the measurement accuracy. As shown in the figure, Figure 1 The temperature compensation method can include steps S10, S20, S30, S40 and S50.

[0050] Step S10 includes obtaining the measured thickness output by the fuel assembly oxide film thickness measuring device when measuring the standard thickness piece at a first set temperature, and recording it as the first high-temperature standard thickness. Since the fuel assembly is close to the reactor, the ambient temperature is relatively high, generally up to 60-80°C. The purpose of this step is to warm up the fuel assembly oxide film thickness measuring device to a temperature relatively close to the environment of the fuel assembly (the set range of the first set temperature can be 60-80°C), so that the subsequent steps can accurately compensate the measured thickness output by the measuring device.

[0051] In some embodiments, the first set temperature can be configured to be close to or the same as the temperature of the environment of the measured fuel assembly, so that the data used for temperature compensation in the subsequent steps is closer to the actual application scenario of the fuel assembly oxide film thickness measuring device, which helps to improve the compensation accuracy.

[0052] Step S20 includes obtaining the measured thickness output by the fuel assembly oxide film thickness measuring device when measuring the standard thickness piece from the first set temperature to the second set temperature, and recording it as the second high-temperature standard thickness. From a macro perspective, the fuel assembly oxide film thickness measuring device is nonlinearly affected by temperature, so in order to improve the compensation accuracy, the second set temperature should be configured to be relatively close to the first set temperature. Further, the second set temperature can be equal to the product of the first set temperature and a set coefficient, wherein the range of the set coefficient is 0.92-0.98, and the set coefficient is preferably 0.95.

[0053] In order to further improve the compensation accuracy, the standard thickness piece is preferably a sheet made of the same material as the surface material of the fuel assembly, and an oxide film with a fixed thickness is arranged on the surface of the sheet. The oxide film on the standard thickness piece can be configured to have a thickness similar to the oxide film thickness of the fuel assembly to be measured. In order to facilitate calibration, the staff can prepare a plurality of standard thickness pieces with different standard thicknesses in advance, which can specifically include four standard thickness pieces with oxide film thicknesses of 0 μm, 24 μm, 48 μm and 72 μm. Then, the staff can select a suitable thickness according to experience or the previous measurement thickness of the fuel assembly to be measured. For example, if the fuel assembly to be measured is measured at a thickness of 18 μm last time, the standard thickness piece with a standard thickness of 24 μm closest to the thickness can be selected as the standard thickness piece for compensation this time.

[0054] Step S30 includes fitting a compensation amount linear fitting function related to the real-time temperature of the measuring device according to the first set temperature, the first high-temperature standard thickness, the second set temperature and the second high-temperature standard thickness.

[0055] In some embodiments, the compensation amount linear fitting function can be expressed as:

[0056] ΔT = (T-T3)*(h3-h4) / (T2-T3); wherein ΔT represents the compensation amount, T represents the real-time temperature, T3 represents the second set temperature, h3 represents the first high-temperature standard thickness, T2 represents the first set temperature, and h4 represents the second high-temperature standard thickness.

[0057] Step S40 includes obtaining the real-time temperature of the fuel assembly oxide film thickness measuring device.

[0058] Step S50 includes compensating the measurement thickness output by the fuel assembly oxide film thickness measuring device according to the real-time temperature and the compensation amount linear fitting function.

[0059] In some embodiments, the expression of the measurement thickness can be h = h1+ΔT, wherein h represents the compensated measurement thickness, and h1 represents the measurement thickness before compensation.

[0060] Considering that the compensation amount linear fitting functions obtained by using standard thickness pieces with different oxide film thicknesses to perform steps S10 to S30 can be different, in some embodiments, steps S41, S42 and S43 can be included before step S50.

[0061] The step S41 comprises: performing the steps S10-S30 cyclically based on the standard thickness pieces of different oxide film thicknesses to obtain a plurality of compensation amount linear fitting functions corresponding to the standard thickness pieces of a plurality of oxide film thicknesses. Specifically, taking the standard thickness piece of 24 μm as an example, first, the measurement thickness output by the fuel assembly oxide film thickness measuring device when measuring the standard thickness piece of 24 μm at the first set temperature is obtained, denoted as the first high-temperature standard thickness; then, the measurement thickness output by the fuel assembly oxide film thickness measuring device when measuring the standard thickness piece of 24 μm from the first set temperature to the second set temperature is obtained, denoted as the second high-temperature standard thickness; finally, the first set temperature, the first high-temperature standard thickness, the second set temperature and the second high-temperature standard thickness are used to fit the compensation amount linear fitting function corresponding to the real-time temperature of the measuring device and the standard thickness piece of 24 μm.

[0062] The step S42 comprises: obtaining a selection instruction. The selection instruction can be obtained by the staff based on experience or the last measurement operation of the measured fuel assembly through the man-machine interaction unit (such as a key, a mouse, a keyboard and a touch screen, etc.).

[0063] The step S43 comprises: selecting one of the plurality of compensation amount linear fitting functions as the compensation amount linear fitting function for compensation according to the selection instruction. Correspondingly, the step S50 comprises: compensating the measurement thickness output by the fuel assembly oxide film thickness measuring device according to the real-time temperature and the compensation amount linear fitting function for compensation.

[0064] It should be noted that the compensation amount linear fitting function corresponding to each oxide film thickness standard thickness piece can be reused, that is, the compensation amount linear fitting function of a standard thickness piece of a certain thickness only needs to be confirmed once and then stored in the memory, so that the staff can directly call after inputting the selection instruction, which helps to improve the compensation efficiency and reduce the operation amount of the processor.

[0065] It can be understood that the present application obtains the first high-temperature measurement thickness output by the fuel assembly oxide film thickness measuring device when measuring the standard thickness piece at the first set temperature, and the second high-temperature measurement thickness output by the fuel assembly oxide film thickness measuring device when measuring the standard thickness piece from the first set temperature to the second set temperature; then the influence of the temperature of the fuel assembly oxide film thickness measuring device from the first set temperature to the second set temperature on the measuring device is regarded as a linear change, and then the compensation amount linear fitting function related to the real-time temperature of the measuring device is fitted; finally, the measurement thickness output by the fuel assembly oxide film thickness measuring device is compensated according to the real-time temperature, which realizes the temperature compensation of the measurement thickness of the fuel assembly oxide film thickness measuring device and significantly improves the measurement accuracy of the measuring device.

[0066] The present invention also provides a fuel assembly oxide film thickness measuring device. Figure 2 As shown, the fuel assembly oxide film thickness measuring device may include a probe 1 , a measuring unit 2 , a temperature sensor 3 and a compensation unit 4 .

[0067] The probe 1 is used to emit a test alternating magnetic field acting on the oxide film of the fuel assembly under test, and output a measurement signal capable of representing the thickness of the oxide film according to the thickness of the oxide film.

[0068] In some embodiments, as Figure 3 As shown, the probe 1 includes a housing 11 , a sleeve 12 , an elastic member 13 , a cover 14 , a standard reference member 15 and an amplifying circuit 16 (not shown).

[0069] See Figure 3 The shell 11 includes an opening 113. The first end of the sleeve 12 is inserted into the shell 11 through the opening 113. Under the support of the elastic member 13, the second end of the sleeve 12 protrudes from the opening 113. The cover body 14 is covered on the second end of the sleeve 12. The standard reference member 15 is arranged in the sleeve 12 and cooperates with the cover body 14 to form a cavity.

[0070] In some embodiments, as Figure 3 As shown, the housing 11 may include a first cylindrical body 111 and a locking member 112. The inner wall of the first end of the first cylindrical body 111 extends inwardly and protrudes to form an opening 113, and the sleeve 12 is inserted from the second end of the first cylindrical body 111. The locking member 112 is provided on the second end of the first cylindrical body 111 and includes a through hole.

[0071] Furthermore, if Figure 3 As shown, the sleeve 12 may include a second barrel 121, a third barrel 122, and a fourth barrel 123. The cover 14 is mounted on the first end of the second barrel 121, and the standard reference member 15 is mounted on the second end of the second barrel 121, so that the interior of the second barrel 121 forms the aforementioned cavity. The third barrel 122 is disposed through the through hole of the locking member 112. The fourth barrel 123 is mechanically connected between the second barrel 121 and the third barrel 122. The outer diameter of the fourth barrel 123 is larger than the aperture of the opening 113, so that the fourth barrel 123 is restricted from sliding within the housing 11 and drives the second barrel 121 and the third barrel 122 during the sliding process. The elastic member 13 includes a spring, which is sleeved outside the third barrel 122 and compressed between the fourth barrel 123 and the locking member 112, so that the elastic force causes the cover to protrude from the opening 113.

[0072] It can be understood that, when assembling the sleeve 12, the elastic member 13 is first sleeved on the third sleeve body 122, then the first end of the second sleeve body 121 is inserted into the first sleeve body 111 from the second end of the first sleeve body 111, and finally the locking member 112 is sleeved on the third sleeve body 122 and fixed to the second end of the first sleeve body 111 in the form of screwing or the like, so as to compress the elastic member 13. Under the action of the elastic member 13, the first end of the second sleeve body 121 can pass through the opening 113 and protrude.

[0073] In some embodiments, the cover body 14 can be an arc-shaped sapphire lens as shown in the drawings. When the measuring device measures the oxide film thickness, the machine will automatically sink the measuring device into the fuel assembly, so that the cover body 14 can be kept in close contact with the surface (i.e. the oxide film) of the fuel assembly under the action of the elastic member 13, so as to keep the distance between the detection coil 17 and the oxide film consistent as much as possible, which helps to improve the thickness measurement accuracy. The arc-shaped structure can reduce the friction between the cover body 14 and the surface of the fuel assembly. Figure 3

[0074] In some embodiments, the second sleeve body 121, the third sleeve body 122 and the fourth sleeve body 123 are integrated.

[0075] In some embodiments, the first sleeve body 111, the locking member 112, the second sleeve body 121, the third sleeve body 122, the fourth sleeve body 123 and the elastic member 13 can be made of metal materials such as stainless steel.

[0076] Please refer to Figure 3 , the cavity is provided with a detection coil 17 close to the cover body 14 and a reference coil 18 close to the standard reference member 15. When the detection coil 17 is excited, the magnetic field generated thereby passes through the cover body 14 and acts on the oxide film, and generates a detection signal according to the thickness of the oxide film. When the reference coil 18 is excited, the magnetic field generated thereby acts on the standard reference member 15, and generates a reference signal according to the thickness of the standard reference member 15. It should be noted that, during measurement, the cover body 14 is in contact with the measured oxide film, and the detection coil 17 and the reference coil 18 are at a certain distance, so that the magnetic field generated by the detection coil 17 can act on the measured oxide film but not on the standard reference member 15, and the magnetic field generated by the reference coil 18 can act on the standard reference member 15 but not on the measured oxide film.

[0077] In order to protect the detection coil 17 and the reference coil 18 from the metal sleeve, the inner wall of the sleeve 12 can be provided with an isolation cylinder 124 for preventing the coils from contacting the sleeve 12. The heat insulation film is made of non-metal heat insulation material such as PA66, and the isolation cylinder 124 is made of plastic.

[0078] ​Further, in order to avoid the influence of heat diffusion in the cavity on the temperature compensation effect, a heat insulation film can be arranged on the inner wall of the isolation cylinder 124. The heat insulation film can be made of a non-metallic heat insulation material with a thickness of about 0.1 mm.

[0079] In some embodiments, the standard reference piece 15 can be a circular sheet made of the same material as the surface of the fuel assembly and without an oxide film on the surface, which can be tightly arranged on the second end of the second cylinder body 121.

[0080] In some embodiments, as shown in Figure 3 , a coil skeleton 19 for fixing the detection coil 17 and the reference coil 18 can be arranged in the cavity. Specifically, the coil skeleton 19 is in the shape of a hollow cylinder, and two annular grooves for fixing the detection coil 17 or the reference coil 18 are arranged at the two ends of the coil skeleton 19.

[0081] In some embodiments, as shown in Figure 3 , a through groove 114 consistent with the axial direction of the first cylinder body 111 is further arranged on the side wall of the first cylinder body 111, and a part (referred to as a manual sliding part) of the fourth cylinder body 123 can slide in the through groove 114, so that the worker can control the length of the second cylinder body 121 protruding from the opening 113 by operating the manual sliding part. In order to make it more convenient for the worker to operate the manual sliding part, a positioning bolt 115 is further arranged on the manual sliding part, so that the worker can operate the positioning bolt 115 to drive the entire sleeve 12 to slide.

[0082] In some embodiments, the probe 1 can further include a tail cover 125 mechanically connected to the third cylinder body 122. The tail cover 125 can be fixed to the end of the third cylinder body 122 away from the second cylinder body 121 by screwing, so as to fix the cable electrically connected to the detection coil 17 and the reference coil 18.

[0083] As shown in Figure 4 , the amplification circuit 16 is electrically connected to the detection coil 17 and the reference coil 18, so as to differentially amplify and process the detection signal and the reference signal to obtain a measurement signal capable of representing the thickness of the oxide film of the fuel assembly.

[0084] In some embodiments, as shown in Figure 4 , the fuel assembly oxide film thickness measuring device can further include an excitation unit 5, a first matching inductor 6 and a second matching inductor 7. The excitation unit 5 is electrically connected to the detection coil 17 through the first matching inductor 6 and is electrically connected to the reference coil 18 through the second matching inductor 7, so as to provide excitation signals to the detection coil 17 and the reference coil 18. The connection points of the first matching inductor 6 and the detection coil 17 and the connection points of the second matching inductor 7 and the reference coil 18 are electrically connected to the amplification circuit 16.

[0085] In some embodiments, asFigure 4 As shown, the amplification circuit 16 includes a differential amplification circuit 161 and a non-inverting amplification circuit 162.

[0086] Please refer to Figure 5 The positive terminal of the differential amplification circuit 161 is electrically connected to the connection point of the first matching inductor 6 and the detection coil 17 to access the detection signal, the negative terminal of the differential amplification circuit 161 is electrically connected to the connection point of the second matching inductor 7 and the reference coil 18 to access the reference signal, and the output terminal of the differential amplification circuit 161 is electrically connected to the non-inverting amplification circuit 162. It should be noted that the reference signal can represent the environmental noise component of the environment in which the detection coil 17 is located, and the differential amplification circuit 161 can perform differential operation on the detection signal and the reference signal, thereby filtering out the environmental noise component in the detection signal and improving the reliability of the differential signal output from the output terminal of the differential amplification circuit 161.

[0087] In some embodiments, as Figure 5 shown, the differential amplification circuit 161 includes a first operational amplifier U1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a first capacitor C1. The negative input terminal of the first operational amplifier U1 is electrically connected to the reference coil 18 through the first resistor R1 to access the reference signal, and is electrically connected to the output terminal of the first operational amplifier U1 through the second resistor R2. The positive input terminal of the first operational amplifier U1 is electrically connected to the detection coil 17 through the third resistor R3 to access the detection signal, and is electrically connected to the ground through the fourth resistor R4. The output terminal of the first operational amplifier U1 outputs a differential signal, and the power supply terminal of the first operational amplifier U1 is also connected to the ground through the first capacitor C1, which functions as a filter.

[0088] As Figure 5 shown, the non-inverting amplification circuit 162 is electrically connected to the measurement unit 2. The non-inverting amplification circuit 162 is used to amplify the differential signal output by the differential amplification circuit 161 to obtain a measurement signal. Since the differential signal is usually an electrical signal with a small voltage value, the role of the non-inverting amplification circuit 162 is to amplify the voltage amplitude of the differential signal, so that the measurement unit 2 can more accurately detect the voltage of the measurement signal, thereby obtaining information related to the thickness of the oxide film.

[0089] In some embodiments, as Figure 5As shown, the positive-phase amplification circuit 162 can include a second operational amplifier U2, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. The positive input terminal of the second operational amplifier U2 is electrically connected to the differential amplification circuit 161 via the fifth resistor R5 to access the differential signal, the negative input terminal of the second operational amplifier U2 is electrically connected to the ground via the sixth resistor R6 in one way and electrically connected to the output terminal of the second operational amplifier U2 via the seventh resistor R7 in another way, and the output terminal of the second operational amplifier U2 is connected to the measurement unit 2 to output the measurement signal to the measurement unit 2.

[0090] To improve the signal quality, the detection coil 17 and the reference coil 18 are preferably connected to the measurement unit 2 through the coaxial line 8. It should be noted that in the present embodiment, the excitation unit 5, the first matching inductor 6, the second matching inductor 7, and the amplification circuit 16 are not arranged in the cavity or the first to fourth barrels, but can be arranged on the side of the measurement unit 2, and the first matching inductor 6 and the second matching inductor 7 are also electrically connected to the corresponding coils through the coaxial line 8. For details, please refer to Figure 4 .

[0091] The measurement unit 2 is configured to output the measurement thickness according to the measurement signal. Specifically, the method for outputting the measurement thickness according to the measurement signal by the measurement unit 2 can include: first, measuring the real part and the imaginary part of the measurement signal, and then substituting the real part and the imaginary part into a thickness fitting function, so as to obtain the measurement thickness. The thickness fitting function is expressed as: h = cosθ * f(Re) + sinθ * g(Im), where h represents the measurement thickness, θ represents the phase angle of the measurement signal, Re is the real part signal, and Im is the imaginary part signal.

[0092] The temperature sensor 3 is configured to output the real-time temperature according to the temperature of the probe 1. The temperature sensor 3 can include a thermistor with a model number of PT1000. Since the detection coil is closest to the oxide film of the measured fuel assembly and the alternating magnetic field acting on the oxide film is provided by the detection coil 17, the temperature affecting the operation of the detection coil 17 is the main cause of the inaccuracy of the thickness measurement of the measurement device. In order to better achieve temperature compensation, in some embodiments, the thermistor is arranged close to the detection coil 17 (the closer the better), so that the thermistor can accurately reflect the temperature change (i.e., the real-time temperature) of the detection coil 17. Further, the real-time resistance of the thermistor can be calculated by the prior art (for example, by inputting a constant current signal to the thermistor, and then detecting the voltage across the thermistor, the real-time resistance of the thermistor can be calculated according to Ohm's law), and then the real-time temperature can be calculated by using a temperature fitting formula, which is expressed as: T = 257.48 * R - 257.01, where T represents the real-time temperature, and R represents the real-time resistance of the thermistor.

[0093] The compensation unit 4 comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the temperature compensation method provided by the embodiments of the application when executing the computer program.

[0094] To further improve the reliability of the measurement signal, in some embodiments, as shown in Figure 4 The fuel assembly oxide film thickness measurement device can further comprise a lock-in amplifier 20, which is electrically connected to the excitation unit 5, the amplification circuit 16, and the measurement unit 2. The lock-in amplifier 20 performs lock-in processing on the measurement signal output by the amplification circuit 16 according to the frequency of the excitation signal output by the excitation unit 5, that is, extracts the component with a frequency close to that of the excitation signal in the measurement signal, to avoid noise of other frequencies reducing the accuracy of the thickness measurement. Specifically, the lock-in amplifier 20 can be an existing lock-in amplifier 20, and the lock-in frequency range thereof can be 0.9K to 1.1K, K corresponding to the frequency of the excitation signal output by the excitation unit 5.

[0095] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other.

[0096] Those skilled in the art will further appreciate that the units and algorithm steps of the 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 examples have been described in general terms, consistent with the principles of the application. Whether the functions are performed in hardware or software depends on the particular application and design constraints. Those skilled in the art can use different methods to implement the described functions for each particular application, but such implementation should not be considered beyond the scope of the application.

[0097] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be directly implemented in hardware, software modules executed by a processor, or a combination of both. The software modules can be stored in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0098] It can be understood that the above embodiments only express the preferred embodiments of the present application, the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the present application; it should be pointed out that for ordinary skilled in the art, the above technical features can be freely combined without departing from the concept of the present application, and several modifications and improvements can be made, which belong to the protection scope of the present application; therefore, any equivalent transformation and modification made with the patent claim scope of the present application shall belong to the coverage of the patent claim of the present application.

Claims

1. A temperature compensation method for a fuel assembly oxide film thickness measuring device, characterized in that: The method comprises: Obtaining a measured thickness output by the fuel assembly oxide film thickness measuring device when measuring a standard thickness piece at a first set temperature, and recording the measured thickness as a first high-temperature standard thickness; obtaining a measured thickness output by the fuel assembly oxide film thickness measuring device when measuring the standard thickness member when the temperature drops from the first set temperature to a second set temperature, and recording the measured thickness as a second high-temperature standard thickness; Fitting a linear fitting function of a compensation amount related to the real-time temperature of the measuring device according to the first set temperature, the first high-temperature standard thickness, the second set temperature, and the second high-temperature standard thickness; Obtaining the real-time temperature of the fuel assembly oxide film thickness measuring device; Compensating the measured thickness output by the fuel assembly oxide film thickness measuring device according to the real-time temperature and the compensation amount linear fitting function; The compensation linear fitting function is: ; in, Indicates the compensation amount, represents the real-time temperature, represents the second set temperature, Indicates the first high temperature standard thickness, represents the first set temperature, Indicates the second high temperature standard thickness; The expression for measuring thickness is: ,in, Indicates the measured thickness after compensation, Indicates the measured thickness before compensation; The first set temperature is configured to be close to or the same as the ambient temperature of the fuel assembly being tested, and the second set temperature is equal to the product of the first set temperature and a set coefficient, wherein the range of the set coefficient is 0.92 to 0.

98.

2. A fuel assembly oxide film thickness measuring device, characterized in that: include: The probe (1) is used to emit a test alternating magnetic field acting on the oxide film of the fuel assembly to be tested, and output a measurement signal capable of representing the thickness of the oxide film according to the thickness of the oxide film; A measuring unit (2), configured to output a measured thickness according to the measurement signal; A temperature sensor (3) is used to output a real-time temperature according to the temperature of the probe (1); A compensation unit (4) comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the temperature compensation method according to claim 1 when executing the computer program.

3. The fuel assembly oxide film thickness measuring device according to claim 2, characterized in that: The probe (1) comprises a housing (11), a sleeve (12), an elastic member (13), a cover (14), a standard reference member (15) and an amplifying circuit (16); The housing (11) includes an opening (113), the first end of the sleeve (12) is inserted into the housing (11) through the opening (113), and under the support of the elastic member (13), the second end of the sleeve (12) protrudes from the opening (113), the cover (14) is covered on the second end of the sleeve (12), and the standard reference member (15) is arranged in the sleeve (12) and cooperates with the cover (14) to form a cavity; The cavity is provided with a detection coil (17) arranged near the cover (14) and a reference coil (18) arranged near the standard reference piece (15); the magnetic field generated by the detection coil (17) when excited passes through the cover (14) and acts on the oxide film, and generates a detection signal according to the thickness of the oxide film; the magnetic field generated by the reference coil (18) when excited acts on the standard reference piece (15), and generates a reference signal according to the thickness of the standard reference piece (15); The amplifying circuit (16) is electrically connected to the detection coil (17) and the reference coil (18) to perform differential amplification processing on the detection signal and the reference signal to obtain a measurement signal representing the thickness of the oxide film being measured.

4. The fuel assembly oxide film thickness measuring device according to claim 3, characterized in that: The housing (11) comprises a first cylinder (111) and a locking member (112); The inner wall of the first end portion of the first cylinder (111) extends and bulges inward to form the opening (113); The locking member (112) is arranged on the second end of the first cylinder (111), and the locking member (112) includes a through hole; The sleeve (12) comprises a second cylinder (121), a third cylinder (122) and a fourth cylinder (123); The cover (14) is covered on the first end of the second cylinder (121), the standard reference member (15) is covered on the second end of the second cylinder (121), the third cylinder (122) is arranged through the through hole of the locking member (112), and the fourth cylinder (123) is mechanically connected between the second cylinder (121) and the third cylinder (122) and has an outer diameter larger than the aperture of the opening (113), so that the fourth cylinder (123) is restricted to slide in the housing (11) and drives the second cylinder (121) and the third cylinder (122) during the sliding process; The elastic member (13) includes a spring, which is sleeved outside the third cylinder (122) and is compressed between the fourth cylinder (123) and the locking member (112) to cause the cover (14) to protrude from the opening (113) through elastic force.

5. The fuel assembly oxide film thickness measuring device according to claim 4, characterized in that: The second cylinder (121), the third cylinder (122) and the fourth cylinder (123) are an integrated structure. The inner wall of the sleeve (12) is provided with an isolation cylinder (124) for preventing the coil from contacting the sleeve (12). The inner wall of the isolation cylinder (124) is provided with a heat-insulating film; wherein the heat-insulating film is made of a non-metallic heat-insulating material, and the isolation cylinder (124) is made of plastic.

6. The fuel assembly oxide film thickness measuring device according to claim 3, characterized in that: A coil frame (19) for fixing the detection coil (17) and the reference coil (18) is also provided in the cavity.

7. The fuel assembly oxide film thickness measuring device according to any one of claims 2 to 6, characterized in that: It also includes an excitation unit (5), a first matching inductor (6) and a second matching inductor (7); The excitation unit (5) is electrically connected to the detection coil (17) via the first matching inductor (6) on one path and electrically connected to the reference coil (18) via the second matching inductor (7) on the other path, so as to provide an excitation signal to the detection coil (17) and the reference coil (18); The connection point between the first matching inductor (6) and the detection coil (17) and the connection point between the second matching inductor (7) and the reference coil (18) are electrically connected to the amplifier circuit (16).

8. The fuel assembly oxide film thickness measuring device according to claim 7, characterized in that: The amplifier circuit (16) includes a differential amplifier circuit (161) and a positive-phase amplifier circuit (162); The positive end of the differential amplifier circuit (161) is electrically connected to the connection point between the first matching inductor (6) and the detection coil (17) to receive the detection signal, the negative end is electrically connected to the connection point between the second matching inductor (7) and the reference coil (18) to receive the reference signal, and the output end is electrically connected to the positive phase amplifier circuit (162); The positive phase amplifier circuit (162) is electrically connected to the measurement unit (2), and the positive phase amplifier circuit (162) is used to amplify the differential signal output by the differential amplifier circuit (161) to obtain the measurement signal.

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