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

Abstract

The invention relates to a fuel assembly oxide film thickness measuring device and a temperature compensation method thereof, and the method comprises the steps: obtaining the measurement thickness outputted when the fuel assembly oxide film thickness measuring device measures a standard thickness piece at a first set temperature, and recording the measurement thickness as a first high-temperature standard thickness; obtaining the measurement thickness output by the fuel assembly oxide film thickness measurement device when the fuel assembly oxide film thickness measurement device measures the standard thickness piece from the first set temperature to the second set temperature, and recording the measurement thickness as a second high-temperature standard thickness; fitting a compensation quantity 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; acquiring the real-time temperature of the fuel assembly oxidation film thickness measuring device; and compensating the measured thickness output by the fuel assembly oxide film thickness measuring device according to the real-time temperature and the compensation quantity linear fitting function. According to the invention, the temperature compensation of the measured thickness is realized, and the measurement accuracy of the measurement device is improved.

Description

Technical Field

[0001] The invention relates to the technical field of film thickness measurement, and in particular to a fuel assembly oxide film thickness measurement device and a temperature compensation method thereof. Background Art

[0002] Fuel assemblies are important equipment for controlling reactor power. Since they work in a high temperature environment for a long time, an oxide film of a certain thickness is easily formed on their surface, and these oxide films will affect the working efficiency of the fuel assemblies. In order to accurately control the reactor, nuclear power plants need to measure the thickness of the oxide film of the fuel assemblies in order to optimize the reactor control logic in a targeted manner to achieve precise control of the reactor power. However, since the fuel assemblies are close to the reactor and the temperature is high, the measurement accuracy of the existing film thickness measurement device is greatly affected by the temperature of the device, resulting in poor accuracy in the measurement of the oxide film, which affects the stability of the reactor power control. Therefore, nuclear power plants are in urgent need of a solution that can perform temperature compensation for the measured thickness. Summary of the invention

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

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

[0005] Obtaining the measured 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;

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

[0007] Fitting a compensation 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;

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

[0009] The measured thickness output by the fuel assembly oxide film thickness measuring device is compensated according to the real-time temperature and the compensation amount linear fitting function.

[0010] Preferably, the compensation 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, wherein 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 a temperature 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 tested fuel assembly, and output a measurement signal capable of characterizing 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, used to output a real-time temperature according to the temperature of the probe;

[0020] The compensation unit comprises 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 comprises an opening, the first end of the sleeve is inserted into the housing through the opening, and under the support of the elastic member, the second end of the sleeve protrudes from the opening, the cover body is covered on the second end of the sleeve, the standard reference member is arranged in the sleeve, and cooperates with the cover body to form a cavity;

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

[0024] The amplifier circuit is electrically connected to the detection coil and the reference coil to perform differential amplification processing on the detection signal and the reference signal to obtain a measurement signal that can represent the thickness of the oxide film to be measured.

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

[0026] The inner wall of the first end portion of the first cylinder extends and bulges inward 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 barrel, a third barrel and a fourth barrel;

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

[0030] The elastic member comprises a spring, and the spring is sleeved outside the third cylinder and is compressed between the fourth cylinder and the locking member to make the cover protrude from the opening through elastic force.

[0031] Preferably, the second cylinder, the third cylinder and the fourth cylinder are 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 thermal insulation film; wherein the thermal insulation film is made of non-metallic thermal insulation material, and the isolation cylinder is made of plastic.

[0032] Preferably, a coil frame for fixing the detection coil and the reference coil is also provided in the cavity.

[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] The excitation unit is electrically connected to the detection coil via the first matching inductor in one path and electrically connected to the reference coil via the second matching inductor in another path, so as to provide an excitation signal to the detection coil and the reference coil;

[0035] A connection point between the first matching inductor and the detection coil and a connection point between the second matching inductor and the reference coil are electrically connected to the amplifier circuit.

[0036] Preferably, the amplifier circuit includes a differential amplifier circuit and a positive phase amplifier circuit;

[0037] The positive end of the differential amplifier circuit is electrically connected to the connection point between the first matching inductor and the detection coil to receive the detection signal, the negative end is electrically connected to the connection point between the second matching inductor and the reference coil to receive the reference signal, and the output end is electrically connected to the positive phase amplifier circuit;

[0038] The positive phase amplifier circuit is electrically connected to the measuring unit, and the positive phase amplifier circuit is used to amplify the differential signal output by the differential amplifier circuit to obtain the measurement signal.

[0039] The implementation of the present invention has the following beneficial effects: a temperature compensation method is provided, by obtaining the first high-temperature standard measurement thickness output by the fuel assembly oxide film thickness measuring device when measuring the standard thickness part at a first set temperature, and obtaining the second high-temperature measurement thickness output by the fuel assembly oxide film thickness measuring device when measuring the standard thickness part when the temperature drops from the first set temperature to the second set temperature; then fitting a linear fitting function of the 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; finally compensating the measurement thickness output by the fuel assembly oxide film thickness measuring device according to the real-time temperature, thereby realizing temperature compensation for the measurement thickness of the fuel assembly oxide film thickness measuring device and significantly improving the measurement accuracy of the measuring device. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0041] Figure 1 is a flow chart of a temperature compensation method in some embodiments of the present invention;

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

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

[0044] Figure 4 is a circuit schematic diagram of a fuel assembly oxide film thickness measuring device in some embodiments of the present invention;

[0045] Figure 5 is a circuit schematic diagram of an amplifier circuit in some embodiments of the present invention. DETAILED DESCRIPTION

[0046] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

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

[0048] 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 may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0049] The present invention provides a temperature compensation method, which is used in a fuel assembly oxide film thickness measuring device, and can compensate the measured thickness output by the fuel assembly oxide film thickness measuring device according to the temperature thereof, thereby improving the measurement accuracy. Figure 1 As shown, the temperature compensation method may include step S10, step S20, step S30, step S40 and step 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 the 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°C to 80°C. The purpose of this step is to heat the fuel assembly oxide film thickness measuring device to a temperature relatively close to the environment where the fuel assembly is located (the setting range of the first set temperature can be 60°C to 80°C), so that the subsequent steps can accurately compensate for 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 ambient temperature of the fuel assembly being measured, so that the data used for temperature compensation in subsequent steps is closer to the actual application scenario of the fuel assembly oxide film thickness measurement 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 part when the temperature drops from the first set temperature to the second set temperature, and recording it as the second high temperature standard thickness. From a macroscopic 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 closer to the first set temperature. Further, the second set temperature can be equal to the product of the first set temperature and the set coefficient, wherein the range of the set coefficient is 0.92 to 0.98, and the set coefficient is preferably 0.95.

[0053] In order to further improve the compensation accuracy, the standard thickness part is preferably a sheet part made of the same material as the surface material of the fuel assembly, and an oxide film of fixed thickness is provided on the surface of the sheet part. The oxide film on the standard thickness part can be configured to be similar in thickness to the oxide film thickness of the fuel assembly under test. To facilitate calibration, the staff can prepare standard thickness parts of various standard thicknesses in advance, specifically including four standard thickness parts with oxide film thicknesses of 0μm, 24μm, 48μm and 72μm, respectively. The staff can then select a suitable thickness based on experience or the previous measured thickness of the fuel assembly under test. For example, if the thickness of the fuel assembly under test was measured last time was 18μm, then the standard thickness part of 24μm, which is closest to this thickness, can be selected as the standard thickness part for this compensation.

[0054] Step S30 includes: 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.

[0055] In some embodiments, the compensation 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 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.

[0059] In some embodiments, the expression for the measured thickness may be: h=h1+ΔT, wherein h represents the measured thickness after compensation, and h1 represents the measured thickness before compensation.

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

[0061] Step S41 includes: looping through steps S10 to S30 based on standard thickness parts with different oxide film thicknesses to obtain a plurality of compensation linear fitting functions corresponding to standard thickness parts with various oxide film thicknesses. Specifically, taking a 24μm standard thickness part as an example, firstly, the measured thickness output by the fuel assembly oxide film thickness measuring device when measuring a 24μm standard thickness part at the first set temperature is obtained, which is recorded as the first sub-high temperature standard thickness; then, the measured thickness output by the fuel assembly oxide film thickness measuring device when measuring a 24μm standard thickness part when the temperature drops from the first set temperature to the second set temperature is obtained, which is recorded as the second sub-high temperature standard thickness; finally, according to the first set temperature, the first sub-high temperature standard thickness, the second set temperature, and the second sub-high temperature standard thickness, a compensation linear fitting function related to the real-time temperature of the measuring device and corresponding to the 24μm standard thickness part can be fitted.

[0062] Step S42 includes: obtaining a selection instruction, wherein the selection instruction can be obtained by the staff based on experience or by operating a human-computer interaction unit (such as a key, mouse, keyboard, touch screen, etc.) when the fuel assembly being measured was last measured.

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

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

[0065] It can be understood that the present invention obtains the first high-temperature standard measurement thickness output by the fuel assembly oxide film thickness measuring device when measuring the standard thickness part at the first set temperature, and obtains the second high-temperature measurement thickness output by the fuel assembly oxide film thickness measuring device when measuring the standard thickness part when the temperature drops from the first set temperature to the second set temperature; then the influence of temperature on the measuring device during the period when the fuel assembly oxide film thickness measuring device drops from the first set temperature to the second set temperature is regarded as a linear change, and then a linear fitting function of the compensation amount related to the real-time temperature of the measuring device is fitted; finally, the measured thickness output by the fuel assembly oxide film thickness measuring device is compensated according to the real-time temperature, thereby realizing temperature compensation for the measured thickness of the fuel assembly oxide film thickness measuring device, and significantly improving 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 tested fuel assembly, and output a measurement signal capable of characterizing the thickness of the oxide film according to the thickness of the oxide film.

[0068] In some embodiments, 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 amplifier circuit 16 (not shown).

[0069] See also 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, and 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, and 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, Figure 3 As shown, the housing 11 may include a first barrel 111 and a locking member 112. The inner wall of the first end of the first barrel 111 extends and protrudes inward to form an opening 113, and the sleeve 12 is inserted from the second end of the first barrel 111. The locking member 112 is disposed on the second end of the first barrel 111, and the locking member 112 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 covered on the first end of the second barrel 121, and the standard reference member 15 is covered on the second end of the second barrel 121, so that the interior of the second barrel 121 forms the cavity. The third barrel 122 is arranged through the through hole of the locking member 112, and the fourth barrel 123 is mechanically connected between the second barrel 121 and the third barrel 122, and the outer diameter of the fourth barrel 123 is greater than the aperture of the opening 113, so that the fourth barrel 123 is restricted to slide in 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 is compressed between the fourth barrel 123 and the locking member 112, so that the cover protrudes out of the opening 113 by elastic force.

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

[0073] In some embodiments, the cover 14 may be Figure 3 The arc-shaped sapphire lens shown in the figure, 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 14 can maintain the closest contact with the surface of the fuel assembly (i.e., the oxide film) under the action of the elastic member 13, so that the distance between the detection coil 17 and the oxide film is kept as consistent as possible, which helps to improve the thickness measurement accuracy. The arc-shaped structure can reduce the friction between the cover 14 and the surface of the fuel assembly.

[0074] In some embodiments, the second barrel 121 , the third barrel 122 , and the fourth barrel 123 are an integrated structure.

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

[0076] See also Figure 3 , a detection coil 17 arranged near the cover 14 and a reference coil 18 arranged near the standard reference part 15 are provided in the cavity. When the detection coil 17 is excited, the magnetic field generated by it passes through the cover 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 by it acts on the standard reference part 15, and generates a reference signal according to the thickness of the standard reference part 15. It should be noted that during measurement, the cover 14 will abut against the oxide film to be measured, and the detection coil 17 and the reference coil 18 have a certain distance, so that the magnetic field generated by the detection coil 17 can act on the oxide film to be measured but not on the standard reference part 15, and the magnetic field generated by the reference coil 18 can act on the standard reference part 15 but not on the oxide film to be measured.

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

[0078] Furthermore, in order to prevent the heat diffusion in the cavity from affecting the temperature compensation effect, a heat insulation film may be provided on the inner wall of the isolation tube 124. The heat insulation film may be made of a non-metallic heat insulation material with a thickness of about 0.1 mm.

[0079] In some embodiments, the standard reference part 15 may be a circular sheet-shaped part made of the same material as the surface of the fuel assembly and having no oxide film on the surface, and may be sealed and covered on the second end of the second cylinder 121 .

[0080] In some embodiments, Figure 3 As shown, the cavity may also be provided with a coil frame 19 for fixing the detection coil 17 and the reference coil 18. Specifically, the coil frame 19 is in a hollow cylindrical shape, and two annular grooves for fixing the detection coil 17 or the reference coil 18 are respectively provided at both ends thereof.

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

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

[0083] See also Figure 4 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 that can represent the thickness of the oxide film to be measured.

[0084] In some embodiments, Figure 4 As shown, the fuel assembly oxide film thickness measuring device may 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 via the first matching inductor 6 and is electrically connected to the reference coil 18 via the second matching inductor 7 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.

[0085] In some embodiments, Figure 4 As shown, the amplifier circuit 16 includes a differential amplifier circuit 161 and a positive phase amplifier circuit 162 .

[0086] See also Figure 5 , 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 access the detection signal, the negative end of the differential amplifier circuit 161 is electrically connected to the connection point between the second matching inductor 7 and the reference coil 18 to access the reference signal, and the output end of the differential amplifier circuit 161 is electrically connected to the positive phase amplifier circuit 162. It should be noted that the reference signal can represent the environmental noise component of the environment where the detection coil 17 is located, and the differential amplifier circuit 161 will perform a differential operation on the detection signal and the reference signal, which can filter out the environmental noise component in the detection signal, thereby improving the credibility of the differential signal output by the output end of the differential amplifier circuit 161.

[0087] In some embodiments, Figure 5 As shown, the differential amplifier 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. The power supply terminal of the first operational amplifier U1 is also connected to the ground through the first capacitor C1, and the first capacitor C1 plays a filtering role.

[0088] like Figure 5 As shown, the positive phase amplifier circuit 162 is electrically connected to the measuring 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 a measurement signal. Since the differential signal is usually an electrical signal with a relatively small voltage value, the function of the positive phase amplifier circuit 162 is to amplify the voltage amplitude of the differential signal, so that the measuring unit 2 can more accurately detect the voltage magnitude of the measurement signal, thereby obtaining relevant information about the oxide film thickness.

[0089] In some embodiments, Figure 5As shown, the positive phase amplifier circuit 162 may 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 amplifier 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, and the other path is electrically connected to the output terminal of the second operational amplifier U2 via the seventh resistor R7, 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 measuring unit 2 via the coaxial line 8. It should be noted that in this embodiment, the excitation unit 5, the first matching inductor 6, the second matching inductor 7 and the amplifying circuit 16 are not arranged in the cavity or the first to fourth cylinders, but can be arranged on the side of the measuring unit 2, and the first matching inductor 6 and the second matching inductor 7 are also electrically connected to the corresponding coils via the coaxial line 8. For details, please refer to Figure 4 .

[0091] The measuring unit 2 is used to output the measured thickness according to the measurement signal. Specifically, the method for the measuring unit 2 to output the measured thickness according to the measurement signal may include: firstly, the real part and the imaginary part in the measurement signal are quantified, and then the real part and the imaginary part are substituted into the thickness fitting function to obtain the measured thickness. The thickness fitting function is expressed as: h = cosθ*f(Re)+sinθ*g(Im), where h represents the measured thickness, θ represents the phase angle of the measurement signal, Re is the real signal, and Im is the imaginary signal.

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

[0093] The compensation unit 4 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 provided in the embodiment of the present invention are implemented.

[0094] In order to further improve the credibility of the measurement signal, in some embodiments, Figure 4 As shown, the fuel assembly oxide film thickness measuring device may also include a phase-locked amplifier 20. The phase-locked amplifier 20 is electrically connected to the excitation unit 5, the amplifying circuit 16 and the measuring unit 2. The function of the phase-locked amplifier 20 is to perform phase-locked processing on the measurement signal output by the amplifying circuit 16 according to the excitation signal frequency output by the excitation unit 5, that is, to extract the component with a frequency close to the excitation signal frequency in the measurement signal to avoid noise of other frequencies from reducing the thickness measurement accuracy. Specifically, the phase-locked amplifier 20 may be an existing phase-locked amplifier 20, and its phase-locked frequency may range from 0.9K to 1.1K, where K corresponds to the excitation signal frequency output by the excitation unit 5.

[0095] In this specification, each embodiment is 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. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0096] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0097] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed 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 implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the coverage of the claims of the present invention.

Claims

1. A temperature compensation method for a fuel assembly oxide film thickness measuring device, characterized in that: The method comprises: Obtaining the measured 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 measured thickness output by the fuel assembly oxide film thickness measuring device when measuring the standard thickness piece when the temperature drops from the first set temperature to the second set temperature, and recording it as the second high temperature standard thickness; Fitting a compensation 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; The measured thickness output by the fuel assembly oxide film thickness measuring device is compensated according to the real-time temperature and the compensation amount linear fitting function.

2. The temperature compensation method according to claim 1, characterized in that: The compensation linear fitting function is: 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; The expression for measuring thickness is: h=h1+ΔT, wherein h represents the measured thickness after compensation, and h1 represents the measured thickness before compensation.

3. The temperature compensation method according to claim 1 or 2, characterized in that: The first set temperature is configured to be a temperature 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.

4. 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 under test, and output a measurement signal capable of characterizing 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), used for outputting 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 any one of claims 1 to 3 when executing the computer program.

5. The fuel assembly oxide film thickness measuring device according to claim 4, 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) comprises 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 close to the cover (14) and a reference coil (18) arranged close to 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 amplifier 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 capable of representing the thickness of the oxide film being measured.

6. The fuel assembly oxide film thickness measuring device according to claim 5, 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) comprises a through hole; The sleeve (12) comprises a second cylinder (121), a third cylinder (122) and a fourth cylinder (123); The cover body (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), the fourth cylinder (123) is mechanically connected between the second cylinder (121) and the third cylinder (122) and its outer diameter is 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) comprises 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.

7. The fuel assembly oxide film thickness measuring device according to claim 6, 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.

8. The fuel assembly oxide film thickness measuring device according to claim 5, characterized in that: A coil frame (19) for fixing the detection coil (17) and the reference coil (18) is also provided in the cavity.

9. The fuel assembly oxide film thickness measuring device according to any one of claims 4 to 8, 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) in one path, and is electrically connected to the reference coil (18) via the second matching inductor (7) in another 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).

10. The fuel assembly oxide film thickness measuring device according to claim 9, characterized in that: The amplifier circuit (16) comprises 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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