A containment penetration seal integrity detection evaluation calibration test device and method

Abstract

The application discloses a correction testing device and method for containment penetration sealing detection and evaluation, and belongs to the field of nuclear safety. The device comprises a main simulation module (radiation-resistant acrylic cylinder), a pore simulation module (a plurality of diameter thin wires form a preformed through hole), a pressurized sealing module, a sound insulation anti-interference module and a measurement adaptation module. By establishing a'sound intensity-leakage rate' calibration curve in the laboratory and combining with the field environment background correction, the quantitative evaluation of the leakage rate of BC type penetration under low pressure conditions based on the ultrasonic leak detection method is realized. The method flow is as follows: device sealing verification, flow supplement method for determining standard leakage rate, ultrasonic measurement for recording test sound intensity and background, calculating net sound intensity, establishing a calibration model by cubic polynomial fitting, measuring the field measurement environment background and calculating the linear amplitude correction coefficient, and substituting the calibration model to obtain the field leakage rate. The device takes into account the influence of field noise, is convenient for online rapid detection of nuclear island, reduces detection cost and radiation exposure risk of personnel.

Description

Technical Field

[0001] This invention relates to the technical field of nuclear safety, and in particular to a calibration test apparatus and method for evaluating the sealing performance of containment penetrations. Background Technology

[0002] Containment penetrations are a critical component of the final safety barrier of a nuclear reactor. They are classified into A, B, and C categories based on their safety importance. While Class BC penetrations have a lower safety level than Class A (such as reactor coolant pipes), they must remain sealed under Design Basis Accident (DBA) conditions to prevent leakage of radioactive materials or intrusion of external media. Existing penetration sealing testing technologies and their challenges are as follows: 1. Limitations of traditional evaluation methods: For example, the "Evaluation Method for Sealing Test of High and Low Pressure Safety Injection Penetrations in Nuclear Power Plants" disclosed in CN111028962A only targets the specific Class A penetrations of high and low pressure safety injection, relies on pressure conversion and leakage rate determination principles, does not involve the quantitative detection of minute leaks in Class B and C penetrations, and cannot be adapted to the complex environment of the nuclear island. Although the "Operating System and Method for Sealing Test of Containment Penetrations in Nuclear Power Plants" in CN114061855A can measure the leakage rate of isolation valves, it requires the cooperation of a liquid phase leak detector and a liquid storage tank, which is complicated to operate and not suitable for rapid online detection of Class B and C penetrations.

[0003] 2. Insufficient adaptability of mechanical penetration test system: CN113405739A's "Method and System for Testing the Sealing Performance of Mechanical Penetration" achieves testing through test blind plates and sealing devices, but focuses on general mechanical penetrations and does not design a simulation structure for the "multiple sealing surfaces and small pores" characteristics of BC type penetrations. In addition, it lacks a correction mechanism for the field environment (noise, radiation), resulting in a large detection error.

[0004] 3. Quantitative deficiencies in acoustic testing technology: CN118535894A's "Acoustic testing method and system based on the geometric features of leak holes" focuses on identifying geometric parameters such as the aspect ratio of leak holes, but does not establish a quantitative relationship of "sound intensity-leakage rate" specific to Class BC penetrations; CN119132660A's "Loop detection method for sealing and plugging cable holes at containment boundaries" involves the relationship between sound intensity and leakage rate, but it only applies to cable holes and cannot be adapted to structural differences such as wall thickness and equivalent diameter of Class BC penetrations, and it does not solve the problem of interference from background noise on site.

[0005] 4. Limited application scenarios of calibration devices: CN119124492A's "Calibration device for gas leak detector for nuclear power unit penetration sealing test" is only used for on-site calibration of gas leak detectors and has poor compatibility with ultrasonic testing technology; CN217059172U's "Auxiliary device for containment penetration sealing test" focuses on temperature and pressure monitoring and adjustment before the test and cannot achieve quantitative correction of leakage rate detection.

[0006] 5. Special testing requirements for Class BC penetrating components: Class BC penetrating components are often located in radiation control areas (local radiation dose ≤10). 4 In environments with ambient temperature (Gy) or normal temperature, traditional contact testing equipment (such as helium mass spectrometers) is complex to operate and costly. Traditional ultrasonic testing relies solely on laboratory calibration models and does not have a correction mechanism designed for the noise and radiation environment at the nuclear island site. This results in a large deviation in the 'sound intensity-leakage rate' relationship, which cannot meet the quantitative requirements for micro-leakage in Class BC penetrating components.

[0007] In summary, existing technologies lack specific calibration schemes for the structural characteristics of Class BC penetrations and the nuclear island field environment. There is an urgent need for a fast, reliable, and economical ultrasonic testing and calibration device and method to fill the technical gap in the quantitative assessment of the sealing performance of Class BC penetrations. Summary of the Invention

[0008] (a) Technical issues To address the problems of poor adaptability of BC-type penetrations, significant interference from the on-site environment, and inability to quantify acoustic detection in existing technologies, this invention provides a calibration test device and method for evaluating the sealing performance of BC-type penetrations in containment structures. By providing specific gas boundary conditions through a dedicated simulation device and combining ultrasonic detection with on-site calibration, a quantitative relationship between "sound intensity and leakage rate" is established, enabling accurate detection of the leakage rate of BC-type penetrations in nuclear island sites.

[0009] (II) Technical Solution 1. Calibrate the testing device This device is a sealed simulation system adapted for Class BC penetrating components, including a main simulation module, a pore simulation module, a pressure sealing module, a sound insulation and interference immunity module, and a measurement adapter module. The structure and parameters of each module are as follows: Device assembly process: 1. Fix two high-density foam boards (20mm thick) to both ends of the acrylic cylindrical tube with high-temperature resistant sealant (bonding strength ≥0.5MPa), and make a Φ20mm grouting hole in the center of one of the foam boards; 2. Tensile 6 polytetrafluoroethylene (PTFE) thin wires evenly between the two foam boards (tension ≥ 5N), and fix the two ends of the thin wires through the pre-reserved slots in the foam boards; 3. Pour high-density silicone rubber into the acrylic cylinder (filling the inside of the cylinder and flush with the end), and remove the thread and foam board after it solidifies; 4. The auxiliary pressure cylinder is rigidly bonded to one end of the acrylic cylindrical tube using high-temperature resistant sealant, and the metal blind flange is sealed to the other end of the auxiliary pressure cylinder using a sealing ring; 5. Attach sound insulation cotton to the outside of the auxiliary pressure cylinder and cover it with a sound insulation cover to complete the device assembly.

[0010] 2. Calibration Test Method This method is based on the core logic of "laboratory fitting modeling + field calibration". It obtains the standard leakage rate through the flow compensation method and establishes the "sound intensity-leakage rate" relationship by combining ultrasonic detection. Finally, it realizes the quantitative detection of leakage rate of Class BC penetrations in the field. The specific steps are as follows: Step 1: Device Sealing Verification 1. Seal all pre-made gaps with steel needles; pressurize the device to 5 kPa (gauge) through the air nozzle of the metal blind flange and maintain it for 30 minutes; 2. Use a local leak detector to measure the overall leakage rate. If the measured value is less than or equal to the minimum detectable flow rate of the instrument (example 500 NmL / min or as per the instrument instructions), the device is considered to be in good condition. If it is not in good condition, check the bonding and sealing rings point by point, repair them, and then retest.

[0011] Step 2: Standard Leakage Rate Measurement (Flow Compensation Method) 1. Open the seal of a single pre-fabricated pore individually, pressurize the device to 5 kPa (gauge) ± 0.1 kPa, and maintain the pressure for 10 minutes; continuously read the leakage rate 3 times. (Unit: NmL / min), take the average value as the standard leakage rate Q of the pore.

[0012] 2. Close the pore and reseal it, then test the other pores in sequence, ensuring that each pore is measured independently.

[0013] Step 3: Ultrasonic Measurement and Environmental Background Recording 1. After depressurization, scan a 20cm area around the specimen at a speed of 5mm / s ± 1mm / s, and continuously measure the environmental background reading 5 times. (Unit: dBµV), take the minimum value as the environmental background. .

[0014] 2. Align the ultrasonic probe with the pre-made aperture at a distance of 5mm ± 0.5mm from the baseline and an angle of 90° ± 5°, and take three consecutive measurements. (Unit: dBµV), take the maximum value as the sound intensity of the pore test. .

[0015] Step 4: Net Asset Value Calculation and Fitting 1. Calculation (Unit: dB), or convert the I value to a linear amplitude V and calculate. (µV), fitting the relationship between Q and net value according to the selected x-axis form; 2. Perform cubic polynomial fitting using the least squares method (Example: R 2 =0.9774; This formula applies when ΔI∈[ (Valid within the 10dB, 27dB range).

[0016] Step 5: On-site calibration and leakage rate calculation 1. On-site measurement of the baseline of the blank area (5 minimum values); and Calculate the correction factor after converting to linear amplitude. .

[0017] 2. Take measurements at the suspected leak point on site. (Take the maximum value from 3 times), calculate the corresponding net amplitude (in the form of the abscissa used in the fitting), and then use... The corresponding correction method adjusts the input value or model coefficients, and finally substitutes them into the fitting equation to obtain the on-site leakage rate Q'.

[0018] (III) Beneficial Effects 1. High adaptability, exclusive to Class BC penetrations: This device uses "acrylic cylinder + polytetrafluoroethylene thin wire" to simulate the wall thickness, equivalent diameter and micro-pores of Class BC penetrations, and its adaptability covers passive auxiliary pipes, ventilation interfaces and other scenarios.

[0019] 2. Outstanding anti-interference ability and high precision: By using "sound insulation cotton + sound insulation cover" (noise reduction ≥20dB) and "on-site correction coefficient K", the noise and radiation interference problems on the nuclear island are solved. The fitting model R²≥0.9774 and the quantitative error of micro-leakage (0.1mm pore) ≤6%.

[0020] 3. Easy to operate and low cost: No complex equipment such as liquid phase leak detectors and storage tanks are required, nor is the calibration process of gas leak detectors required. Only a local leak detector and an ultrasonic instrument are needed. The operation can be completed by a single person. The detection time is shortened by 80% compared with helium mass spectrometry and the equipment cost is reduced by 60%.

[0021] 4. Rigorous quantitative logic and traceability: Through a closed-loop process of "sealing verification → standard data acquisition → fitting modeling → on-site calibration", each step has clear parameters (such as test pressure 5kPa(g)±0.1kPa(g) and scanning speed 5mm / s±1mm / s), and the data is traceable, meeting the compliance requirements in the field of nuclear safety.

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the flow compensation method measurement of the present invention, showing the connection between the local leak detector and the metal blind flange nozzle, and marking the test pressure and pressure holding time parameters; Figure 2 This is a schematic diagram of ultrasonic intensity measurement according to the present invention, showing the distance and angle between the ultrasonic probe and the baseline, and marking the environmental background scanning range and the experimental sound intensity measurement position; Figure 3 This is the net sound intensity value-leakage rate fitting curve of the present invention (net sound intensity value unit: dBµV, leakage rate unit: NmL / min). Figure 4 This is a schematic diagram of the leakage path and ultrasonic detection location of the BC type through-hole component of the instrument control cable channel of the present invention. 1-5: Leakage path number; j: Ultrasonic detection location point. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Explanation of unified symbols: : The sound pressure voltage displayed at the test point, in dBµV (relative to 1µV). : The displayed value of the ambient background sound intensity, in dBµV; :correspond Linear voltage amplitude, in µV, calculation method ; :correspond The linear voltage amplitude, in µV. ; : Linear net amplitude (if linear subtraction is used); if If no valid signal is detected, then it is determined that there is no valid signal. Clear sound strength, In the formula, Net sound intensity (unit: dBµV). The measured sound intensity value is given in dBµV. This represents the environmental background value (unit: dBµV). It can also be expressed in dB (when using net amplitude as the x-axis) or directly. (When using dB difference as the x-axis, the same units must be used for fitting and the linear / logarithmic meaning must be explained.) : Laboratory environmental background value, taken as the minimum value of n measurements (unit: dBµV). Results in µV; : This is the background value of the on-site environment, taken as the minimum value of n measurements (unit: dBµV). Results in µV; The conversion formulas for I (dBµV) and V (µV) are as follows: ; K is the field correction factor, and the correction factor is defined as follows: ; When expressed in dB, if a ratio is calculated using dB, then it is: .

[0027] Please see Figures 1 to 4 In this embodiment of the invention, a calibration test device for evaluating the sealing performance of a containment penetration includes a main body simulation module, a pore simulation module, a pressure sealing module, a sound insulation and anti-interference module, and a measurement adapter module. The main simulation module is a radiation-resistant acrylic cylindrical tube with an outer diameter of 450 mm, a length of 1200 mm, a wall thickness of ≥10 mm, and a radiation resistance dose of ≥10. 4 Gy; The pore simulation module consists of six polytetrafluoroethylene (PTFE) thin wires with diameters of 0.1 mm, 0.2 mm, 0.3 mm, 0.5 mm, 0.8 mm, and 1.0 mm, respectively, stretched between foam boards at both ends of the main simulation module with a tension ≥ 5 N. The pressurization and sealing module includes an auxiliary pressurization cylinder, a metal blind plate, and a nitrile rubber sealing ring. The auxiliary pressurization cylinder is made of acrylic material, with a diameter of 500mm and a length of 150mm, and is rigidly bonded to the main simulation module. The metal blind plate is made of 304 stainless steel and has a G1 / 4 internal threaded air nozzle, which is sealed to the auxiliary pressurization cylinder through the sealing ring. The sound insulation and anti-interference module includes 5mm thick sound insulation cotton (noise reduction ≥20dB) and a detachable sound insulation cover, which covers the outside of the auxiliary pressure cylinder; The measurement adapter module includes an ultrasonic measurement baseline marked on the outside of the main simulation module (5mm away from the pore simulation area), and a quick connector for adapting to a local leak detector.

[0028] The foam boards at both ends of the main simulation module are bonded with high-temperature resistant sealant with a bonding strength ≥0.5MPa. A Φ20mm grouting hole is opened in the center of one of the foam boards for injecting high-density silicone rubber.

[0029] A calibration test method for evaluating the sealing performance of a Class BC containment penetration based on the above-mentioned device, characterized by comprising the following steps: Step 1: Device sealing verification - Seal all the fine wire holes with a steel needle, pressurize the device to 5 kPa (g) and maintain the pressure for 30 min. If the overall leakage rate measured by the local leak detector is ≤500 NmL / min (consistent with the unit of leakage rate in the subsequent standard), the device is deemed to be in good condition. Step 2: Data Acquisition – Remove the single thin wire plug, pressurize to 5 kPa(g) ± 0.1 kPa(g) and hold for 10 minutes. Take the average of three leakage rates as the standard leakage rate Q. After depressurization, scan a 20 cm range at 5 mm / s ± 1 mm / s and take the minimum value five times as the environmental background value I0. Take the maximum value three times with the probe distance from the baseline at 5 mm ± 0.5 mm and the included angle at 90° ± 5° as the test sound intensity value I. j ; Step 3: Fitting and Modeling – Calculating Net Sound Intensity Values , with I k The model is obtained by fitting Q as the x-axis and Q as the y-axis. ; Where Q is in NmL / min; I k The unit is dBµV (or dB, if...). (expressed in dB).

[0030] Step 4: On-site calibration – Measure the baseline value of the blank area on site. Calculate the correction coefficient ; Measure the sound intensity value in the field test ,calculate Substitute correction model , Output Q' as the leakage rate result.

[0031] In step 2, after data acquisition of each pore is completed, it is necessary to re-seal it with a steel needle before testing the next pore to avoid errors caused by disassembly and reassembly of the device.

[0032] In step 4, during on-site sound intensity measurement, the ultrasonic probe scans along the sealing surface of the BC type through-hole component and locates the point where the "beep beep" sound is most pronounced to read the sound. .

[0033] Specific embodiments of the present invention (divided into three main stages) Phase 1: Complete fabrication of the calibration testing device (including material selection and precision control) 1.1 Material Preparation and Pretreatment 1.2 Device Assembly and Silicone Rubber Injection (Step-by-Step Precision Control) 1. Assembly of foam board and thin thread Fix two foam boards to both ends of the acrylic cylinder with sealant: apply sealant with a thickness of 2mm ± 0.5mm, align them and fix them with clamps (4 clamps, evenly distributed along the circumference), and place them in an environment of 25℃ to cure for 24 hours. Insert the PTFE thread: Thread both ends of the thread through the slots of the two foam boards respectively, straighten it with tweezers, and ensure that the thread is parallel to the axis of the acrylic cylinder (deviation ≤1°); leave a length of 10mm±2mm at both ends and temporarily fix it with tape (to prevent loosening).

[0034] 2. Silicone rubber infusion and curing Place the mold vertically: Fix the assembled acrylic cylinder vertically (grouting hole facing upwards), and calibrate the bottom with a level (levelness ≤ 0.5°) to prevent uneven distribution of rubber during grouting; Injection procedure: Pour silicone rubber into the grouting funnel (Φ50mm) and slowly inject it at a rate of 50mL / min±10mL / min. Pause for 30s after every 100mL of injection to release air bubbles. After filling, use a scraper to smooth the surface until it is flush with the end of the acrylic cylinder. Solidification control: Place in a constant temperature and humidity chamber at 25℃±2℃ and 50%±5% humidity for 24 hours; after solidification, test with a ShoreA hardness tester to ensure that the hardness is ≥60 (if it is not qualified, extend the solidification time until the hardness meets the standard).

[0035] 3. Fine thread removal and porosity inspection Removing the thread: Hold one end of the thread with pointed tweezers and slowly pull it out along the axis (parallel to the thread) at a speed of 3mm / s±1mm / s; if the thread breaks (probability ≤5%), use a Φ0.08mm steel needle to pull out the remaining segment from the other end. Pore ​​accuracy inspection: Observe the pore cross section with an optical microscope (magnification 50x) to ensure that the diameter is consistent with the thin wire (error ≤0.05mm); blow the pores with compressed air (pressure 0.1MPa). If the airflow is uniform and the flow meter reading is stable, the pore permeability is deemed to be qualified.

[0036] 4. Assembly of pressurization module and sound insulation module Auxiliary pressure cylinder bonding: Apply sealant (10mm width, 2mm thickness) to one end of the acrylic cylinder, insert and align the auxiliary pressure cylinder, fix it with clamps, and cure for 24 hours; Metal blind flange installation: Place a nitrile rubber sealing ring (Φ500mm, 3mm thickness) on the contact surface between the blind flange and the auxiliary pressure cylinder, and tighten it evenly with four M8 bolts (torque 5N). m), ensure a tight seal; Sound insulation module installation: Attach 5mm thick sound insulation cotton (model: centrifugal glass wool-80kg / m³) to the outside of the auxiliary pressure cylinder, and seal the seams with sound insulation tape; cover the outside with a detachable sound insulation cover (10mm thick, noise reduction 25dB).

[0037] Phase 2: Laboratory "Sound Intensity-Leakage Rate" Fitting Modeling 2.1 Preparation of test equipment and calibration of parameters Local leak detector: Model JLY-Ⅳ, preheated by powering on 24 hours in advance; calibrated using a standard leak pore size (1000 NmL / min, accuracy 1%) to ensure measurement error ≤2%; Ultrasonic leak detector: Model SDT200, connected to a dedicated headset (38kHz filtered); calibrated with a standard sound source (38kHz, sound intensity 0dBμV) to ensure that the displayed value error is ≤0.5dBμV; Pressure control equipment: air compressor (model: GA37) + pressure regulating valve (accuracy ±0.01kPa), output pressure is stable at 5kPa(g)±0.05kPa.

[0038] 2.2 Data Acquisition The calibration test apparatus for ultrasonic non-destructive testing of the sealing performance of Class BC penetrations of containment structures, provided by this invention, has an acrylic cylinder with an outer diameter of 450 mm and a length of 1200 mm. Table 1 shows the leakage rates of 12 prefabricated gaps (leakage pores) obtained using a local leak detector suitable for the flow compensation method under a low pressure of 5 kPa(g), and the sound intensity values ​​of the 12 prefabricated gaps (leakage pores) and the ambient background sound intensity values ​​measured by the ultrasonic leak detector.

[0039] Table 1: Sound intensity values ​​corresponding to different leakage rates Using the following formula: The net acoustic intensity values ​​obtained by the ultrasonic leak detector after processing are shown in Table 2.

[0040] Table 2: Net Sound Intensity Values ​​at Each Test Point The 12 sets of data in Table 2 were fitted, with the net sound intensity at the leakage point on the x-axis (in dB) and the air leakage rate under 5 kPa (g) standard conditions on the y-axis (in N mL / min). Figure 3 As shown, the formula for the relationship between leakage rate and sound intensity is as follows: (Determination coefficient R² = 0.9774) Where Q is the air leakage rate (unit: NmL / min) under standard conditions of 5 kPa (g), and I k Net sound intensity (unit: dBµV).

[0041] The goodness of fit of the above leakage rate-sound intensity relationship formula has reached over 0.9, therefore, the leakage rate-sound intensity relationship can be considered reliable under the condition of cubic fitting. Since the leakage rate range of this experiment can be conservatively considered to cover the actual leakage situation (6L / min is sufficiently significant, and leaks can be detected and repaired through other means), the measurement results under this laboratory environment can guide the determination of leakage rate measurement in the field.

[0042] The above formula for fitting the leakage rate-sound intensity relationship can be rewritten as: Since this fitting formula was derived under laboratory ambient noise conditions, the coefficients should be corrected when used in field tests to ensure the smallest possible uncertainty.

[0043] The SDT200 ultrasonic leak detector is equipped with a dedicated headset to receive a 38kHz sound source and convert it into regular "beep" sounds. The headset can clearly detect the ambient noise generated by sound waves of various frequencies in the testing environment. Therefore, this feature can be utilized to perform preliminary leak detection tests by first sealing the entire cable / hole with the sound source and headset. The ultrasonic probe then scans the entire sealed surface, marking the locations where "beep" sounds are detected.

[0044] If no 38kHz sound source is detected on the entire sealing surface and the ultrasonic leak detector reading does not fluctuate significantly, then the leakage rate of the entire sealing surface is considered to be within an acceptable range.

[0045] If a continuous "beep" sound is detected near a point, it proves that there is a crack-shaped leak. Based on the sound heard through the headphones and the display value of the ultrasonic leak detector, the point where the "beep" sound is the loudest and the display value is also the highest is the detection value of the leak point at the crack-shaped location.

[0046] Leak points that need to be marked must meet the following requirements: (a) No sound was detected around the leak point when the probe was used for measurement; (b) A small area where sound is continuously detected is considered a leak point.

[0047] The number of leakage paths at each sealing point is n (n≥1, and each path is independent of the others); the experimental model assumes that the leakage rate per unit area is equal to the sum of the leakage rates per unit path of all independent paths within the unit area, i.e. .

[0048] Data validation rules: If the error of parallel tests is ≤5% (e.g., error 3.2% for serial numbers 1 and 2), the data is considered valid; if the error is >5% (e.g., error 8% due to pore blockage in a certain group), the pores should be cleared and the test repeated. Anomaly Handling: In test number 11, the environmental background value I0 was -7.9 dBμV (higher than other groups). After investigation, it was found to be due to noise interference from laboratory ventilation. After turning off the ventilation, I0 was remeasured and found to be -10.5 dBμV to ensure data consistency.

[0049] 2.3 Fitting Model Establishment and Accuracy Verification Fitting calculation: Using Origin 2023 software, a cubic polynomial fit was performed on the 12 sets of data to obtain the model: Accuracy verification: A supplementary experiment was conducted using a 0.4mm diameter fine wire pore size that was not included in the fitting. The measured value was Q = 1650 NmL / min. k =5.8dBμV; Substituting into the model, the calculated Q =1632NmL / min, with a relative error of 1.1% (≤2%), the model accuracy is deemed to meet the standard.

[0050] Phase 3: On-site testing in multiple scenarios (covering typical applications of Class B and C through-hole components) 3.1 Scenario 1: Instrumentation and control cable channel (annular crack leakage) Test object: Instrumentation and control cable channel (Class BC) of the containment structure of Unit 3 of a nuclear power plant, with an outer diameter of 450mm, a wall thickness of 1200mm, and the same sealant type as the laboratory (Dow Corning SE4485). On-site environment: temperature 28℃, humidity 60%, ambient noise 65dB (including mechanical pump vibration noise), radiation dose 0.1mSv / h; Testing steps: 1. On-site background measurement: I0' = -8.5dBμV (5 minimum values) was measured on a concrete wall (without leakage) 1m away from the passage. K = (-10) / (-8.5)≈1.18 was calculated. 2. Probe Scanning: Use the SDT200 probe to scan clockwise along the sealing surface of the cable channel (speed 5mm / s). A continuous "beep" sound is detected at the "3 o'clock position," and the location is pinpointed to point I, where the sound intensity is at its maximum. j =9.2dBμV; 3. Leakage rate calculation: ; Substitute into the correction model: ; 4. Verification: The leakage rate of this channel was directly measured using a local leak detector (JLY-Ⅳ). The measured value of Q was 2180 NmL / min, and the relative error was 1.4% (≤2%). The test result was deemed reliable.

[0051] 3.2 Scenario 2: Passive auxiliary pipeline (point pore leakage) Inspection object: Auxiliary pipeline (Class BC) of passive safety system of Unit 2 of a nuclear power plant, with an outer diameter of 300mm, a wall thickness of 1000mm, and the flange sealing surface is sealed with silicone rubber; On-site environment: temperature 32℃, humidity 55%, ambient noise 70dB (including fan noise), radiation dose 0.15mSv / h; Testing steps: 1. On-site background measurement: I0' = -7.2dBμV was measured on a metal support (without leakage) 2m away from the pipeline, and K = (-10) / (-7.2)≈1.39 was calculated; 2. Probe scanning: Radial scanning along the flange sealing surface (speed 4mm / s), a dotted "beep" sound was detected at "flange bolt hole position 12", locating to I. j =5.3dBμV; 3. Leakage rate calculation: ; Substitute into the correction model: ; 4. Verification: After disassembling the flange, a Φ1.2mm pore was found in the sealant. After repair, the Q' was retested and found to be 380 NmL / min (less than the qualified threshold of 500 NmL / min for device sealing), confirming that the leak point was accurately located.

[0052] 3.3 On-site interference handling measures Electromagnetic noise interference: If the probe reading fluctuates by more than 2dBμV, wrap copper foil (0.1mm thick) around the probe cable and ground it to reduce electromagnetic interference (such as motor radiation). High temperature environment (>40℃): Cover the probe with an aluminum heat sink (2mm thick) to prevent the probe sensitivity from decreasing due to high temperature; Radiation dose exceeds the limit (>0.5mSv / h): Use an extension rod (1.5m long) to connect the probe, and personnel should operate outside the radiation control area to reduce the radiation dose.

[0053] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A calibration test apparatus for evaluating the sealing performance of containment penetrations, characterized in that, include: The main body simulation module, pore simulation module, pressure sealing module, sound insulation and interference suppression module, and measurement adapter module are included. The main simulation module is a radiation-resistant cylindrical structure equivalent to the BC-type penetrator under test. The main simulation module is made of radiation-resistant PMMA or an equivalent material, with a radiation resistance dose ≥10. 4 Gy; The equivalent outer diameter and length of the cylinder are adjustable to match the equivalent diameter of the field penetration and the wall thickness; The pore simulation module includes at least one set of fine wires of different diameters that can form through pores. The fine wires are polytetrafluoroethylene (PTFE) wires. The pore simulation module is formed by injecting high-density silicone rubber into the main simulation module and waiting for it to solidify. Then, the PTFE wires are slowly pulled out along the axial direction at a speed of 3 mm / s ± 1 mm / s to form tiny through pores in the solidified silicone rubber matrix. The tiny through pores are used to simulate the leakage pores of BC type through parts. The pressurization and sealing module is used to provide low-pressure pressurization and pressure holding to the main simulation module; The sound insulation and interference suppression module includes sound insulation cotton and a detachable sound insulation cover, which is used to eliminate the interference of ultrasonic sound source propagating into the air and reduce the impact of ambient background noise on sound intensity measurement. The measurement adapter module is used to locate the baseline of the ultrasonic probe and quickly connect to the local leak detector, thereby obtaining the standard leakage rate and ultrasonic intensity value of each prefabricated pore on the main simulation module. This is used to establish a calibration curve between the sound intensity and the leakage rate, and combined with the background correction of the on-site environment, to realize the quantitative assessment of the leakage rate of Class BC penetrations in the nuclear island under low-pressure conditions.

2. The calibration test device for evaluating the sealing performance of containment penetrations according to claim 1, characterized in that, The main simulation module is a radiation-resistant acrylic cylindrical tube with an outer diameter of 450 mm, a length of 1200 mm, and a wall thickness of ≥10 mm. The pore simulation module consists of six polytetrafluoroethylene (PTFE) thin wires with diameters of 0.1 mm, 0.2 mm, 0.3 mm, 0.5 mm, 0.8 mm, and 1.0 mm, respectively, which are tensioned between foam boards at both ends of the main simulation module with a tension ≥ 5 N. The pressurization and sealing module includes an auxiliary pressurization cylinder, a metal blind plate, and a nitrile rubber sealing ring. The auxiliary pressurization cylinder is made of acrylic material, with a diameter of 500mm and a length of 150mm, and is rigidly bonded to the main simulation module. The metal blind plate is made of 304 stainless steel and has a G1 / 4 internal threaded air nozzle, which is sealed to the auxiliary pressurization cylinder through the sealing ring. The sound insulation and anti-interference module includes 5mm thick sound insulation cotton and a detachable sound insulation cover, which covers the outside of the auxiliary pressure cylinder; The measurement adapter module includes an ultrasonic measurement baseline marked on the outside of the main simulation module, and a quick connector for adapting to a local leak detector.

3. A calibration test method based on the device described in claim 1, characterized in that, Includes the following steps: Step A: Device sealing verification; Step B: For each pre-fabricated pore, the standard leakage rate is determined at the standard test pressure using the flow compensation method, and the average value is recorded; Step C: After depressurization, use an ultrasonic leak detector to measure and record the ambient background value and the test sound intensity of each pore. Step D: After converting the sound intensity from decibels to linear amplitude, calculate the net amplitude and perform cubic polynomial least squares fitting with the net amplitude as the abscissa and the leakage rate as the ordinate to obtain the basic calibration model. Step E: During on-site testing, first measure the background of the on-site environment, and use the ratio of the linear amplitude corresponding to the on-site background to the laboratory background amplitude as a correction factor. Calculate the ratio of the linear amplitude of the on-site environmental background to the laboratory background, i.e., the correction coefficient K. After correcting the fitting model with K, substitute it into the on-site measured sound intensity to obtain the on-site leakage rate. The test pressure was 5 kPa ± 0.1 kPa; the leakage rate for each group was the average of three readings; the environmental background was the minimum of five measurements; and the test sound intensity was the maximum of three measurements. The ultrasonic leak detector displays data in dBµV, and the linear amplitude is calculated according to... The conversion is used for fitting and correction calculations; Step 1: Device sealing verification - Seal all the fine wire holes with a steel needle, pressurize the device to 5 kPa (g) and maintain the pressure for 30 min. If the overall leakage rate measured by the local leak detector is ≤500 NmL / min, it is considered qualified. Step 2: Data Acquisition – Remove the single thin wire plug, pressurize to 5 kPa(g) ± 0.1 kPa(g) and hold for 10 minutes. Take the average of three leakage rates as the standard leakage rate Q. After depressurization, scan a 20 cm range at 5 mm / s ± 1 mm / s and take the minimum value five times as the environmental background value I0. Take the maximum value three times with the probe distance from the baseline at 5 mm ± 0.5 mm and the included angle at 90° ± 5° as the test sound intensity value I. j ; Step 3: Fitting and Modeling – Calculating Net Sound Intensity Values ， Take I k The model is obtained by fitting Q as the x-axis and Q as the y-axis. ； Step 4: On-site calibration – Measure the baseline value of the blank area on site. Calculate the correction coefficient ； Measure the sound intensity value in the field test ,calculate Substitute correction model ， Output Q' as the leakage rate result.

4. The calibration test method according to claim 3, characterized in that, In step 2, after data acquisition of each pore is completed, it needs to be resealed with a steel needle before testing the next pore to avoid errors caused by disassembly and reassembly of the device.

5. The calibration test method according to claim 3, characterized in that, In step 4, during on-site sound intensity measurement, the ultrasonic probe scans along the sealing surface of the BC type through-hole component and locates the point where the "beacon sound" is most prominent to read the signal. .

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