Fuel rod tungsten inclusion standard rod and manufacturing method thereof

Abstract

The invention provides a manufacturing method of a tungsten inclusion standard rod of a fuel rod. The manufacturing method comprises the following steps: manufacturing a tungsten inclusion standard sample; performing X-ray fluorescence detection on the upper end plug sealing welding tungsten inclusion sample, and recording the counting rate of the tungsten content of the upper end plug sealing welding spot; performing a water corrosion test on all the detected upper end plug sealing welding samples; checking the surface condition of the upper end plug seal welding sample after the water corrosion sample; taking the sample with the maximum counting rate value and the appearance of the off-white corrosion product on the sealing weld surface as a tungsten inclusion standard sample; performing plug pressing on the tungsten inclusion standard sample and the cladding tube according to normal plug pressing process parameters to prepare a tungsten inclusion standard rod; regularly carrying out functional verification and evaluation on the tungsten inclusion standard sample; and evaluating the appearance and sealing welding tungsten inclusion. The method can be used for manufacturing the tungsten inclusion standard rod of the fuel rod, the tungsten inclusion standard rod is applied to detection of the corresponding fuel rod, the effect is good, and the measurement result meets the expectation.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear fuel element detection for nuclear power plants, and in particular to a fuel rod tungsten inclusion standard rod and a manufacturing method thereof. Background Art

[0002] Fuel rods are an important part of fuel assemblies and a barrier to the reactor, which is of great significance to nuclear safety. Most of the sealed welds of fuel rods in pressurized water reactors are welded by TIG welding. If the tungsten electrode is overheated and melted or the tungsten electrode contacts the molten pool during TIG welding, tungsten-containing defects may be formed in the sealed welds, which will reduce the corrosion resistance of the fuel rod welds in the reactor during operation in the reactor, thereby causing damage to the fuel rods and triggering nuclear fuel leakage. Therefore, it is necessary to establish an online non-destructive detection method for tungsten inclusions in fuel rod sealed welds.

[0003] At present, the equipment for online X-ray fluorescence detection of fuel rods has been developed, which fills the technical gap of online X-ray fluorescence detection of fuel rods in this industry. Therefore, it is necessary to produce tungsten inclusion standard rods; to establish the control limit and rejection limit of fuel rod products, and to qualitatively detect the tungsten inclusion defects of fuel rod sealing welds. The production of tungsten inclusion standard rods for fuel rods is of great significance to the application of online X-ray fluorescence detection methods for fuel rods and to ensure the quality of fuel rods. Summary of the invention

[0004] The main purpose of the present invention is to provide a method for manufacturing a fuel rod tungsten inclusion standard rod, so as to obtain a fuel rod sealing weld point tungsten inclusion standard rod that meets the requirements, which is used to establish the control limit and rejection limit of the fuel rod product, and realize the qualitative inspection of the fuel rod sealing weld point tungsten inclusion.

[0005] Another object of the present invention is to provide a fuel rod tungsten inclusion standard rod, the prepared standard rod meets the tungsten inclusion requirements of the fuel rod sealing weld.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for manufacturing a fuel rod tungsten inclusion standard rod comprises the following steps:

[0008] Step 1: Prepare a tungsten inclusion standard sample;

[0009] Step 2: Perform X-ray fluorescence detection on the tungsten inclusion sample of the upper end plug sealing weld, and record the counting rate of the tungsten content of the upper end plug sealing weld;

[0010] Step 3: Perform a water corrosion test on all tested upper end plug seal welding samples;

[0011] Step 4: Check the surface condition of the upper plug seal welding sample after the water corrosion test specimen;

[0012] Step 5: The sample with the largest count rate value and gray-white corrosion products on the seal weld surface is used as the tungsten inclusion standard sample;

[0013] Step 6: The tungsten inclusion standard sample and the cladding tube are plugged according to normal plugging process parameters to form a tungsten inclusion standard rod;

[0014] Step 7: Regularly perform functional verification and evaluation on tungsten inclusion standard samples;

[0015] Step 8: Assess appearance and seal weld for tungsten inclusions.

[0016] In step 1, a number of upper end plugs made of the same material as the fuel rod to be inspected are selected, and sealing welding is performed according to the welding process parameters of the process appraisal.

[0017] Furthermore, during welding, the inter-electrode distance was reduced to different degrees, and several upper end plug sealed welded tungsten inclusion samples were prepared.

[0018] In step 2, the upper end plug sealing weld tungsten inclusion sample is detected by an X-ray fluorescence spectrometer detection system.

[0019] In step 3, the water corrosion test parameters are:

[0020] Test temperature: 360℃±6℃;

[0021] Test pressure: 18.7MPa±1.4MPa;

[0022] Trial duration: 14 days.

[0023] In step 5, the sample with the maximum count rate value and gray-white corrosion products on the sealing weld surface detected by the X-ray fluorescence spectrometer is selected as the standard sample.

[0024] In step 7, the verification and assessment period shall not exceed 12 months.

[0025] In step 8, the assessment includes:

[0026] Appearance inspection: There are no scratches, dents or pits on the sealing weld surface;

[0027] Detection of tungsten inclusions in seal welds: Measure the tungsten inclusion standard sample 20 times, and the relative standard deviation of the measured values ​​shall not exceed 10%.

[0028] In addition, the present invention also provides a fuel rod tungsten inclusion standard rod, which is manufactured by the above manufacturing method.

[0029] Furthermore, the fuel rod tungsten inclusion standard rod comprises a cladding tube, an air cavity spring is provided in the cladding tube, a molybdenum core block is arranged between the air cavity spring and the lower end plug, and the upper end plug and the lower end plug are respectively arranged at the upper and lower ends of the cladding tube.

[0030] Compared with the prior art, the fuel rod tungsten inclusion standard rod and the manufacturing method thereof provided by the present invention have the following beneficial effects:

[0031] The method provided by the present invention can produce a fuel rod tungsten inclusion standard rod, and the present invention is applied to the production of a fuel rod tungsten inclusion standard rod, and has been evaluated. The tungsten inclusion standard rod has been applied to the detection of corresponding fuel rods, with good effects, and the measurement results are in line with expectations. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for the technical description.

[0033] Figure 1 This is a schematic structural diagram of the fuel rod tungsten inclusion standard rod provided by the present invention.

[0034] Description of reference numerals:

[0035] 1-lower end plug; 2-molybdenum core block; 3-cladding tube; 4-air cavity spring; 5-upper end plug; 6-upper end plug sealing welding point. DETAILED DESCRIPTION

[0036] The following is further explained in detail through specific implementation methods.

[0037] The present invention provides a method for manufacturing a fuel rod tungsten inclusion standard rod, comprising the following steps:

[0038] Step 1: Prepare a tungsten inclusion standard sample;

[0039] Select several upper end plugs of the same material as the fuel rod to be inspected, and perform sealing welding according to the welding process parameters of the process identification. During welding, reduce the inter-electrode spacing to varying degrees, and prepare several upper end plug sealing welding tungsten inclusion samples.

[0040] Step 2: Send the upper end plug sealing weld tungsten inclusion sample to the X-ray fluorescence spectrometer detection system for detection, and record the counting rate of the tungsten inclusion sample.

[0041] Step 3: All upper end plug sealing weld samples tested by X-ray fluorescence spectrometer are subjected to water corrosion test. The water corrosion test parameters are:

[0042] Test temperature: 360℃±6℃;

[0043] Test pressure: 18.7MPa±1.4MPa;

[0044] Trial duration: 14 days.

[0045] Step 4: Visually inspect the surface condition of the upper end plug tungsten inclusion sample after water corrosion test specimen.

[0046] Step 5: Select the sample with the largest count rate value shown by the X-ray fluorescence spectrometer and gray-white corrosion products appearing on the surface of the sealing weld as the tungsten inclusion standard sample.

[0047] Step 6: The tungsten inclusion standard sample and the cladding tube with a lower end plug are plugged according to normal plugging process parameters (the cladding tube is already equipped with a molybdenum core and an air cavity spring) to form a tungsten inclusion standard rod.

[0048] Step 7: The tungsten inclusion standard rod needs to be functionally verified and evaluated regularly, and the time period should not exceed 12 months.

[0049] Step 8: Evaluate the appearance and tungsten inclusions of the sealed welds. The evaluation contents shall include but are not limited to the following:

[0050] Appearance inspection: There are no scratches, dents, pits or other appearance defects on the sealed weld surface.

[0051] Detection of tungsten inclusions in seal welds: Measure the tungsten inclusion standard rod 20 times, and the relative standard deviation of the measured values ​​shall not exceed 10%.

[0052] In addition, the present invention manufactures a fuel rod tungsten inclusion standard rod based on the above method, such as Figure 1 As shown, the fuel rod tungsten inclusion standard rod provided by the present invention comprises a lower end plug 1, a molybdenum pellet 2, a cladding tube 3, an air cavity spring 4, and an upper end plug 5. An air cavity spring 4 is provided in the cladding tube 3, and a molybdenum pellet 2 is arranged between the air cavity spring 4 and the lower end plug 1. The upper end plug 5 and the lower end plug 1 are respectively arranged at the upper and lower ends of the cladding tube 3. The function of the air cavity spring 4 is to fix the molybdenum pellet to prevent the molybdenum pellet from moving.

[0053] The function of the sealing weld 6 is to seal the fuel rod after a certain pressure of helium is filled into the fuel rod so that the rod reaches a specified internal pressure, thereby reducing the interaction between the pellet and the cladding and improving heat transfer.

[0054] The fuel rod cladding tube and the upper and lower end plugs of the present invention are made of zirconium alloy material. Select a number of upper end plugs of the same material as the fuel rod to be measured, and weld them according to the welding parameters of the process identification. During welding, reduce the inter-electrode distance to varying degrees, and prepare a number of upper end plug sealed weld tungsten inclusion samples. All upper end plug sealed weld samples detected by X-ray fluorescence spectrometer are subjected to water corrosion test. The sample with the largest count rate value displayed by X-ray fluorescence spectrometer and the gray-white corrosion products appearing on the sealed weld surface is selected as the tungsten inclusion standard sample. After the cladding tube welded with the lower end plug is loaded with the molybdenum core block and the air cavity spring, the tungsten inclusion standard sample is pressed with the cladding tube according to the normal pressing process parameters to make it a tungsten inclusion standard rod.

[0055] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for manufacturing a fuel rod tungsten inclusion standard rod, characterized in that: The following steps are involved: Step 1: Prepare a tungsten inclusion standard sample; Step 2: Perform X-ray fluorescence detection on the tungsten inclusion sample of the upper end plug sealing weld, and record the counting rate of the tungsten content of the upper end plug sealing weld; Step 3: Perform a water corrosion test on all tested upper end plug seal welding samples; Step 4: Check the surface condition of the upper plug seal welding sample after the water corrosion test specimen; Step 5: The sample with the largest count rate value and gray-white corrosion products on the seal weld surface is used as the tungsten inclusion standard sample; Step 6: The tungsten inclusion standard sample and the cladding tube are plugged according to normal plugging process parameters to form a tungsten inclusion standard rod; Step 7: Regularly verify and evaluate the functionality of the tungsten inclusion standard rod; Step 8: Assess appearance and seal weld for tungsten inclusions.

2. The method for manufacturing a fuel rod tungsten inclusion standard rod according to claim 1, characterized in that: In step 1, a number of upper end plugs made of the same material as the fuel rod to be inspected are selected, and sealing welding is performed according to the welding process parameters of the process appraisal.

3. The method for manufacturing a fuel rod tungsten inclusion standard rod according to claim 2, characterized in that: During welding, the inter-electrode distance was reduced to different degrees, and several upper end plug sealed welding tungsten inclusion samples were prepared.

4. The method for manufacturing a fuel rod tungsten inclusion standard rod according to claim 1, characterized in that: In step 2, the upper end plug sealing weld tungsten inclusion sample is detected by an X-ray fluorescence spectrometer detection system.

5. The method for manufacturing a fuel rod tungsten inclusion standard rod according to claim 1, characterized in that: In step 3, the water corrosion test parameters are: Test temperature: 360℃±6℃; Test pressure: 18.7MPa±1.4MPa; Trial duration: 14 days.

6. The method for manufacturing a fuel rod tungsten inclusion standard rod according to claim 1, characterized in that: In step 5, select the sample with the maximum count rate value and gray-white corrosion products on the sealing weld surface detected by X-ray fluorescence spectrometer.

7. The method for manufacturing a fuel rod tungsten inclusion standard rod according to claim 1, characterized in that: In step 7, the verification and assessment period shall not exceed 12 months.

8. The method for manufacturing a fuel rod tungsten inclusion standard rod according to claim 1, characterized in that: In step 8, the assessment includes: Appearance inspection: There are no scratches, dents or pits on the sealing weld surface; Detection of tungsten inclusions in seal welds: Measure the tungsten inclusion standard sample 20 times, and the relative standard deviation of the measured values ​​shall not exceed 10%.

9. A fuel rod tungsten inclusion standard rod, characterized in that: The method is prepared by any one of claims 1 to 8.

10. The fuel rod tungsten inclusion standard rod according to claim 9, characterized in that: The invention comprises a cladding tube (3), wherein an air cavity spring (4) is arranged inside the cladding tube (3), a molybdenum core block (2) is arranged between the air cavity spring (4) and a lower end plug (1), and an upper end plug (5) and the lower end plug (1) are respectively arranged at the upper and lower ends of the cladding tube (3).

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