Preparation and verification method of standard rod for helium pressure nondestructive testing

Abstract

The invention relates to the field of fuel rods, in particular to a preparation and verification method of a standard rod for helium pressure nondestructive testing. The method comprises the steps that under the same standard temperature environment temperature, in the welding process, nitrogen is filled, meanwhile, nitrogen pressure is corrected, and standard rods of three specifications are prepared and formed; the appearance is checked; calibrating the standard rod in a stable environment; and the verification confidence coefficient is 0.95. According to the preparation method, calibration is carried out synchronously, and the calibrated standard rod can be matched with helium pressure nondestructive testing equipment, so that subsequent helium pressure nondestructive testing is facilitated.

Description

Technical Field

[0001] This invention relates to the field of fuel rods, and more particularly to a method for preparing and verifying a standard rod for helium pressure nondestructive testing. Background Technology

[0002] Fuel rods are core components of a nuclear power plant, and their quality is crucial to the normal operation of the plant. To ensure the internal structure of the fuel rods and regulate pressure changes, the fuel rods need to be filled with helium gas at a certain pressure.

[0003] Currently, the puncture method is commonly used to test whether the helium pressure meets the requirements. After puncturing the fuel rod, the pressure inside the fuel rod is measured using a pressure gauge. The advantage of this method is its speed, but its disadvantages are that it is a destructive test, not economical, and it is a sampling method for process assurance, so it cannot test all fuel rods.

[0004] Compared to puncture methods, non-destructive testing (NDT) offers advantages such as cost-effectiveness and repeatability. Specifically, the NDT method involves heating one end of the fuel rod, utilizing the thermal convection generated by helium gas within the fuel rod, detecting temperature changes at appropriate locations, and deriving a model based on Fourier's formula to obtain the helium pressure value.

[0005] To test fuel rods using non-destructive testing (NDT), it is necessary to design standard rods of different specifications and feed them into a helium pressure NDT equipment. A model is built based on the results of multiple measurements, and the algorithm is determined. In addition, standard rods are required for calibration of the helium pressure NDT equipment after its design and during its actual use.

[0006] After the standard rod is prepared, it needs to be verified. Therefore, it is urgent to study a standard rod preparation technology and verification method. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method for preparing and verifying a standard rod for helium pressure nondestructive testing, wherein the standard rod is verified simultaneously during preparation, and the verified standard rod can be matched with helium pressure nondestructive testing equipment, thereby facilitating subsequent helium pressure nondestructive testing.

[0008] This invention provides a method for preparing and calibrating a standard rod for helium pressure nondestructive testing, comprising the following steps:

[0009] Step 1: Under the same standard temperature and ambient temperature, three standard rods of different specifications are prepared. During the preparation process, the lower end plug is welded to the shell tube using a pressure resistance welding machine. After welding, helium gas at different pressures is filled into the three shell tubes respectively, and then the upper end plug is welded to the shell tube. During the welding process, the gas pressure sensor in the pressure resistance welding machine measures the absolute pressure of helium gas in the standard rod in real time. Under non-standard stable ambient temperature and humidity, the absolute pressure value of helium gas in the standard rod is corrected, thereby increasing or decreasing the amount of helium gas filled to make it infinitely close to the standard value.

[0010] Step 2: After the standard rods are prepared, their appearance is inspected;

[0011] Step 3: Verify the standard bar in a stable environment:

[0012] Taking into account the deviation of the gas pressure sensor, the deviation of the atmospheric pressure measurement, the deviation between the standard ambient temperature and the temperature during helium filling, and the deviation of the temperature and humidity instrument, the gas pressure deviation range ΔP of the standard rod is calculated.

[0013] If the gas pressure deviation range ΔP is less than the standard threshold, the standard rod is qualified and the prepared standard rod meets the requirements; if the gas pressure deviation range ΔP is greater than the standard threshold, the standard rod is unqualified and the prepared standard rod does not meet the requirements, and the parameters need to be readjusted to prepare the standard rod.

[0014] The confidence level of the test is 0.95.

[0015] In one specific embodiment of the present invention, the standard values ​​of helium pressure in the three specifications of standard rods are 0.98MPa, 1.76MPa, and 2.45MPa, respectively.

[0016] In one specific embodiment of the present invention, the method for calculating the gas pressure deviation range ΔP is as follows:

[0017]

[0018] △P 传感器 This is due to the deviation of the pressure sensor and the deviation of the gas pressure measurement channel in the welding chamber, in MPa.

[0019] △P 仪表 The deviation in the temperature and humidity instrument measurement results is indicated in MPa.

[0020] △P 大气 The deviation in atmospheric pressure measurement is expressed in MPa.

[0021] △P 温度 MP represents the deviation between the standard ambient temperature and the temperature during helium filling.

[0022] In one specific embodiment of the present invention, the △P 温度 The calculation is performed using the following formula:

[0023]

[0024] Where: △T is the ambient temperature measurement deviation during the production of the standard bar, in °C;

[0025] △P 设定 To determine the deviation between the absolute pressure value of helium gas filled into a standard rod in a pressure resistance welding machine at standard ambient temperature and the actual pressure value.

[0026] In one specific embodiment of the present invention, the standard ambient temperature is 25°C.

[0027] In one specific embodiment of the present invention, the requirements for the stable environment are: ambient temperature of 10-40°C, atmospheric pressure of 0.86-1.04 MPa, and relative humidity of 55%-85%.

[0028] In one specific embodiment of the present invention, a temperature detector is used to measure the temperature in a stable environment, a humidity detector is used to measure the humidity in a stable environment, and a pressure detector is used to measure atmospheric pressure.

[0029] The requirements for the temperature detector are: temperature measurement range -20℃ to 70℃, measurement deviation ±0.5℃;

[0030] The requirements for humidity detectors are a relative air humidity measurement range of 2% to 98% and an absolute measurement deviation of ±2%.

[0031] The pressure detector is required to have an atmospheric pressure measurement range of (0~2×10⁻⁶). 5 Pa, absolute measurement deviation ±5×10 2 Pa.

[0032] In one specific embodiment of the present invention, the method for correcting the absolute pressure value of helium gas inside the standard rod is as follows:

[0033] After measuring the real-time temperature in a stable environment, and under standard ambient temperature, the absolute pressure of helium gas to be filled into the standard rod using a pressure resistance welding machine is set to the value P. 设定 ,

[0034] Under non-standard stable ambient temperatures, the absolute pressure value of helium gas inside the standard rod needs to be corrected.

[0035]

[0036] P 设定 —Gas pressure setpoint in the standard rod, MPa;

[0037] P 检定 —Gas pressure verification value in the standard rod, MPa;

[0038] P 大气 —Atmospheric pressure, MPa;

[0039] T 稳定环境 —The temperature of the stable environment during the production of the standard bar, ℃.

[0040] In one specific embodiment of the present invention, it further includes:

[0041] Step 4: Standard rod sealing check; sealing check once a year.

[0042] Compared with the prior art, the preparation and verification method of the standard rod for helium pressure nondestructive testing of the present invention can provide a basis for whether the standard rod is qualified and provide a reliable guarantee for the use of the final helium pressure nondestructive testing equipment. Detailed Implementation

[0043] To further understand the present invention, embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the present invention.

[0044] An embodiment of the present invention discloses a method for preparing and verifying a standard rod for helium pressure nondestructive testing, comprising the following steps:

[0045] Step 1: Prepare three standard rods of the same specifications under the same standard temperature environment. The three standard rods have the same shape and size, only differing in internal filling pressure. It is best to prepare the three standard rods continuously. During the preparation process, a pressure resistance welding machine is used to weld the lower plug to the shell tube. After welding, helium gas at different pressures is filled into the three shell tubes respectively, and then the upper plug is welded to the shell tube. During the welding process, the gas pressure sensor in the pressure resistance welding machine measures the absolute pressure of the helium gas inside the standard rod in real time to ensure that the filled helium gas pressure meets the standard requirements.

[0046] During real-time measurement, the absolute pressure value of helium in the standard rod is corrected under non-standard stable environmental temperature and humidity conditions, thereby increasing or decreasing the amount of helium charged to make it infinitely close to the standard value.

[0047] The method for correcting the absolute pressure value of helium gas inside the standard rod is as follows:

[0048] At standard ambient temperature, the absolute pressure of helium gas to be filled into the standard rod using a pressure resistance welding machine is set to the value P. 设定 The standard ambient temperature is 25℃;

[0049] Under non-standard stable ambient temperatures, the absolute pressure value of helium gas inside the standard rod needs to be corrected.

[0050]

[0051] P 设定 —Gas pressure setpoint in the standard rod, MPa;

[0052] P 检定 —Gas pressure verification value in the standard rod, MPa;

[0053] P 大气 —Atmospheric pressure, MPa;

[0054] T 稳定环境 —The temperature of the stable environment during the production of the standard bar, ℃.

[0055] P 设定 Not exceeding 2.5 MPa.

[0056] The standard rod is made of Zr-Nb alloy and consists of a lower plug, a casing tube, and an upper plug, with helium gas at a certain pressure inside.

[0057] Each set of three standard bars is prepared and tested sequentially within a unified time frame, preferably in a continuous manner.

[0058] During the preparation process, the helium pressure in the standard rod must be guaranteed with a confidence level of 0.95, the allowable deviation must not exceed the standard threshold, and the temperature must be controlled at 20±5℃.

[0059] The standard helium pressure values ​​inside the three specifications of standard bars are 0.98MPa, 1.76MPa, and 2.45MPa, respectively.

[0060] Step 2: After the standard rods are prepared, their appearance is inspected;

[0061] Specifically, check whether the appearance matches the design drawings; if they match, proceed to the next step; if they do not match, it is deemed unqualified.

[0062] Step 3: Verify the standard bar in a stable environment:

[0063] Taking into account the deviation of the gas pressure sensor, the deviation of the atmospheric pressure measurement, the deviation between the standard ambient temperature and the temperature during helium filling, and the deviation of the temperature and humidity instrument, the gas pressure deviation range ΔP of the standard rod is calculated.

[0064] If the gas pressure deviation range ΔP is less than the standard threshold, the standard rod is qualified and the prepared standard rod meets the requirements; if the gas pressure deviation range ΔP is greater than the standard threshold, the standard rod is unqualified and the prepared standard rod does not meet the requirements, and the parameters need to be readjusted to prepare the standard rod; the confidence level of the test is 0.95.

[0065] The method for calculating the gas pressure deviation range ΔP is as follows:

[0066]

[0067] △P 传感器 This is due to the deviation of the pressure sensor and the deviation of the gas pressure measurement channel in the welding chamber, in MPa.

[0068] △P 仪表 The deviation in the temperature and humidity instrument measurement results is indicated in MPa.

[0069] △P 大气 The deviation in atmospheric pressure measurement is expressed in MPa.

[0070] △P 温度 MP represents the deviation between the standard ambient temperature and the temperature during helium filling.

[0071] The △P 温度 The calculation is performed using the following formula:

[0072]

[0073] Where: △T is the ambient temperature measurement deviation during the production of the standard bar, in °C;

[0074] △P 设定 To determine the deviation between the absolute pressure value of helium gas filled into a standard rod in a pressure resistance welding machine at standard ambient temperature and the actual pressure value.

[0075] The requirements for the stable environment are: ambient temperature of 10–40℃, atmospheric pressure of 0.86–1.04 MPa, and relative humidity of 55%–85%.

[0076] A temperature detector is used to measure the temperature in a stable environment, a humidity detector is used to measure the humidity in a stable environment, and a pressure detector is used to measure atmospheric pressure.

[0077] The requirements for the temperature detector are: temperature measurement range -20℃ to 70℃, measurement deviation ±0.5℃;

[0078] The requirements for humidity detectors are a relative air humidity measurement range of 2% to 98% and an absolute measurement deviation of ±2%.

[0079] The pressure detector is required to have an atmospheric pressure measurement range of (0~2×10⁻⁶).5 Pa, absolute measurement deviation ±5×10 2 Pa.

[0080] Because the environment and equipment have a significant impact on the deviation, the confidence level of the test can only be achieved at 0.95 under the above-mentioned environmental and equipment conditions.

[0081] The verification process also includes:

[0082] Step 4: Standard rod sealing check; sealing check once a year.

[0083] The standard rod has a service life of 6 years;

[0084] Once the verification results are normal, a metrological verification certificate will be issued. A sealing check must be conducted annually, and an extension can only be applied for after the certificate passes the inspection, until the service life is reached.

[0085] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0086] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing and verifying a standard rod for helium pressure nondestructive testing, characterized in that, Includes the following steps: Step 1: Under the same standard temperature and ambient temperature, three standard rods of different specifications are prepared. During the preparation process, the lower end plug is welded to the shell tube using a pressure resistance welding machine. After welding, helium gas at different pressures is filled into the three shell tubes respectively, and then the upper end plug is welded to the shell tube. During the welding process, the gas pressure sensor in the pressure resistance welding machine measures the absolute pressure of helium gas in the standard rod in real time. Under non-standard stable ambient temperature and humidity, the absolute pressure value of helium gas in the standard rod is corrected, thereby increasing or decreasing the amount of helium gas filled to make it infinitely close to the standard value. Step 2: After the standard rods are prepared, their appearance is inspected; Step 3: Verify the standard bar in a stable environment: Taking into account the deviation of the gas pressure sensor, the deviation of the atmospheric pressure measurement, the deviation between the standard ambient temperature and the temperature during helium filling, and the deviation of the temperature and humidity instrument, the gas pressure deviation range ΔP of the standard rod is calculated. If the gas pressure deviation range ΔP is less than the standard threshold, the standard rod is qualified and the prepared standard rod meets the requirements; if the gas pressure deviation range ΔP is greater than the standard threshold, the standard rod is unqualified and the prepared standard rod does not meet the requirements, and the parameters need to be readjusted to prepare the standard rod. The confidence level of the test is 0.

95.

2. The method for preparing and verifying a standard rod for helium pressure nondestructive testing according to claim 1, characterized in that, The standard helium pressure values ​​inside the three specifications of standard bars are 0.98MPa, 1.76MPa, and 2.45MPa, respectively.

3. The method for preparing and verifying a standard rod for helium pressure nondestructive testing according to claim 1, characterized in that, The method for calculating the gas pressure deviation range ΔP is as follows: △P 传感器 The deviations are those of the pressure sensor and the gas pressure measurement channel in the welding chamber, measured in MPa and ΔP. 仪表 The deviation in the temperature and humidity instrument measurement results is indicated in MPa. △P 大气 The deviation in atmospheric pressure measurement is expressed in MPa. △P 温度 MP represents the deviation between the standard ambient temperature and the temperature during helium filling.

4. The method for preparing and verifying a standard rod for helium pressure nondestructive testing according to claim 3, characterized in that, The △P 温度 The calculation is performed using the following formula: Where: △T is the ambient temperature measurement deviation during the production of the standard bar, in °C; △P 设定 To determine the deviation between the absolute pressure value of helium gas filled into a standard rod in a pressure resistance welding machine at standard ambient temperature and the actual pressure value.

5. The method for preparing and verifying a standard rod for helium pressure nondestructive testing according to claim 3, characterized in that, The standard ambient temperature is 25°C.

6. The method for preparing and verifying a standard rod for helium pressure nondestructive testing according to claim 1, characterized in that, The requirements for the stable environment are: ambient temperature of 10–40℃, atmospheric pressure of 0.86–1.04 MPa, and relative humidity of 55%–85%.

7. The method for preparing and verifying a standard rod for helium pressure nondestructive testing according to claim 1, characterized in that, A temperature detector is used to measure the temperature in a stable environment, a humidity detector is used to measure the humidity in a stable environment, and a pressure detector is used to measure atmospheric pressure. The requirements for the temperature detector are: temperature measurement range -20℃ to 70℃, measurement deviation ±0.5℃; The requirements for humidity detectors are a relative air humidity measurement range of 2% to 98% and an absolute measurement deviation of ±2%. The pressure detector is required to have an atmospheric pressure measurement range of (0~2×10⁻⁶). 5 Pa, absolute measurement deviation ±5×10 2 Pa.

8. The method for preparing and verifying a standard rod for helium pressure nondestructive testing according to claim 1, characterized in that, The method for correcting the absolute pressure value of helium gas inside the standard rod is as follows: After measuring the real-time temperature in a stable environment, and under standard ambient temperature, the absolute pressure of helium gas to be filled into the standard rod using a pressure resistance welding machine is set to the value P. 设定 , Under non-standard stable ambient temperatures, the absolute pressure value of helium gas inside the standard rod needs to be corrected. P 设定 —Gas pressure setpoint in the standard rod, MPa; P 检定 —Gas pressure verification value in the standard rod, MPa; P 大气 —Atmospheric pressure, MPa; T 稳定环境 —The temperature of the stable environment during the production of the standard bar, ℃.

9. The method for preparing and verifying a standard rod for helium pressure nondestructive testing according to claim 1, characterized in that, Also includes: Step 4: Standard rod sealing check; sealing check once a year.

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