Tungsten dispersion state zirconium-based standard rod and manufacturing method thereof

Abstract

The invention belongs to the technical field of nuclear power, and particularly relates to a tungsten dispersion state zirconium-based standard rod and a manufacturing method thereof. According to the tungsten dispersion state zirconium-based standard rod and the manufacturing method thereof, qualitative and quantitative detection of the tungsten content of a fuel rod or other zirconium alloy matrixes is achieved. The method is suitable for checking the tungsten content of sealing welding spots of various types of zirconium alloy fuel rods, so that the technical problem that the tungsten content of the fuel rod cannot be quantitatively detected by X-ray fluorescence online detection of the nuclear fuel rod is solved. The method can be applied to actual manufacturing of the tungsten dispersion state zirconium-based standard rod, the produced standard rod is applied to detection of corresponding fuel rods, the effect is good, and the measurement result meets the expectation.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power, and in particular relates to a tungsten dispersed zirconium-based 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 pressurized water reactor fuel rods 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.

[0003] In response to the above problems, the relevant technology uses X-ray fluorescence technology and a matching tungsten inclusion standard rod to achieve online inspection of fuel rod sealing welding, but it is still unable to detect the actual tungsten content of the fuel rod. In addition, there is no method for manufacturing quantitative standard samples of tungsten content in fuel rods in the industry. Therefore, it is urgent to establish an effective online non-destructive detection of tungsten inclusions in fuel rod sealing welds. Summary of the invention

[0004] In order to overcome the problems existing in the related art, a tungsten dispersed zirconium-based standard rod and a manufacturing method thereof are provided, the method comprising:

[0005] According to one aspect of an embodiment of the present disclosure, a method for manufacturing a tungsten dispersed zirconium-based standard rod is provided, the method comprising:

[0006] Step 1, preparation of tungsten-containing samples, homogenizing tungsten powder and zirconium powder of a preset ratio in an argon-protected glove box to form a mixed powder after homogenization, wherein the particle size of the tungsten powder and the zirconium powder is not higher than 75 μm; cold pressing and vacuum sintering of the mixed powder after homogenization are performed, and then lathe processing is performed to obtain tungsten-containing samples, and test samples are extracted from the tungsten-containing samples for chemical composition analysis, and the tungsten content of the standard rod is finally determined;

[0007] Step 2: standard rod production: assembling and welding the tungsten-containing sample and the cladding tube according to the fuel rod production process to form a tungsten-containing standard rod;

[0008] Step 3: Perform functional verification and evaluation on the standard rod at a preset period of no more than 12 months. The evaluation of the standard rod includes: whether there are scratches, dents, or pits on the surface of the tungsten-containing sample.

[0009] In a possible implementation, step 1 includes:

[0010] Step 11, multi-stage premixing, operating in a glove box, in an argon or helium protective atmosphere, mixing tungsten powder and zirconium powder in a preset ratio, and repeating the grinding method of first mixing in a conical flask for 5 to 8 minutes and then grinding in a grinding mortar for 5 to 8 minutes for three to five times;

[0011] Step 12, ball milling, mixing the premixed powder formed in step 11 again by ball milling to form a mixed powder after homogenization;

[0012] Step 13, uniformity detection, the mixed powder after homogenization treatment is divided into multiple samples in a glove box protected by argon or helium for chemical composition detection to detect the actual content of tungsten in each sample;

[0013] Step 14, cold pressing, using a hydraulic universal material test press to cold press the homogenized mixed powder into a plurality of columnar samples;

[0014] Step 15, vacuum sintering, sintering each columnar sample to form a sintered sample, and the sintering is performed under a vacuum environment;

[0015] Step 16, machining and forming, machining each sintered sample by turning to form a tungsten-containing sample matching the shape of the fuel rod end assembly;

[0016] Step 17, inspect the appearance and dimensions of the tungsten-containing sample to ensure that there are no scratches, dents or pits on the surface of the tungsten-containing sample;

[0017] Step 18, destructive testing of tungsten-containing samples, extract test samples from the same batch of tungsten-containing samples, take the head, middle and tail of the tungsten-containing samples respectively, process them into block samples, package and label the processed block samples, and then process the block samples into debris, mix them evenly and send them for chemical composition analysis, and finally determine the tungsten content of the standard rod.

[0018] In one possible implementation, in step 11, the multi-stage premixing process will adopt a multi-stage mixing method; first, a 10000 ppm tungsten dispersed powder is prepared, and then the 10000 ppm tungsten dispersed powder and zirconium powder are mixed to prepare a 1000 ppm tungsten dispersed powder, and finally the 1000 ppm tungsten dispersed powder and zirconium powder are mixed to prepare a 100 ppm tungsten dispersed powder.

[0019] In a possible implementation, in step 12, an omnidirectional planetary ball mill is used, the ball mill jar and the ball mill beads are made of 304 stainless steel balls, the ball mill jar is filled with argon or helium for protection, the ball milling time is 2 to 5 hours, and the material-to-ball ratio is 1:5 to 1:15.

[0020] In a possible implementation, in step 14, the molding mold is a floating female mold capable of bidirectional pressing, and the loading process is performed in a glove box protected by argon or helium.

[0021] In a possible implementation, in step 14, the molding pressure is controlled at 2-4t, the diameter of the female mold is 10mm, and the sample height is controlled at 14-15mm.

[0022] In a possible implementation, in step 15, the sintering temperature is controlled at 1000° C., and the sintering time is controlled at 10 minutes.

[0023] In a possible implementation, step 2 includes:

[0024] Step 21, pressing the lower end plug into the cladding tube according to the fuel rod plugging process parameters;

[0025] Step 22, welding the lower end plug and the cladding tube according to the fuel rod ring welding process parameters;

[0026] Step 23, after the cladding tube with the lower end plug welded thereto is loaded with the molybdenum core body and the air cavity spring, 1.96MPa to 2.6MPa of helium is filled in, and the tungsten-containing sample is pressed into the cladding tube according to the plugging process parameters of the fuel rod;

[0027] Step 24, welding the tungsten-containing sample to the cladding tube according to the fuel rod welding process parameters;

[0028] Step 25, such as Figure 1 As shown, the marking position of the standard rod is carried out in the area 10 mm away from the weld at the upper end of the standard rod.

[0029] According to another aspect of the embodiment of the present disclosure, a tungsten-dispersed zirconium-based standard rod is provided, and the tungsten-dispersed zirconium-based standard rod is manufactured by the method as described above.

[0030] In a possible implementation, the tungsten dispersed zirconium-based standard rod includes: a lower end plug, a molybdenum core block, a cladding tube, an air cavity spring, and a tungsten-containing sample;

[0031] The cladding tube is wrapped around the outside of the molybdenum core block, the lower end plug is embedded in the port at one end of the cladding tube, the tungsten-containing sample is embedded in the port at the other end of the cladding tube, and the air cavity spring is arranged in the cladding tube between the molybdenum core block and the tungsten-containing sample.

[0032] The beneficial effects of the present disclosure are as follows: the tungsten dispersed zirconium-based standard rod and its manufacturing method provided by the present disclosure realize the qualitative and quantitative detection of the tungsten content of the fuel rod or other zirconium alloy matrix. It is suitable for the inspection of the tungsten content of the sealing welds of various types of zirconium alloy fuel rods, thereby solving the technical problem that the online detection of nuclear fuel rod X-ray fluorescence cannot quantitatively detect the tungsten content of the fuel rod. It can be applied to the actual production of tungsten dispersed zirconium-based standard rods, and the produced standard rods have been used in the detection of corresponding fuel rods, with good results and the measurement results meeting expectations. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of a tungsten-dispersed zirconium-based standard rod shown in an embodiment of the present disclosure.

[0034] Figure 2 It is a schematic diagram of a tungsten-containing sample shown in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0035] The present disclosure is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Unless otherwise defined, the technical and scientific terms used in the present disclosure have the same meanings as those generally understood by those skilled in the art to which the present disclosure belongs; the terms used in the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure; the term "including" and any variations thereof in the present disclosure are intended to cover non-exclusive inclusions. Obviously, the embodiments described in the present disclosure are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative efforts are within the scope of protection of the present disclosure.

[0037] Reference to "embodiments" in this disclosure means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the disclosure. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0038] Figure 1 It is a schematic diagram of a tungsten-dispersed zirconium-based standard rod shown in an embodiment of the present disclosure. Figure 2 is a schematic diagram of a tungsten-containing sample shown in an embodiment of the present disclosure. Figure 1 and Figure 2The tungsten dispersed zirconium-based standard rod comprises: a lower end plug 1, a molybdenum core block 2, a cladding tube 3, an air cavity spring 4, and a tungsten-containing sample 6; the cladding tube 3 is wrapped around the outside of the molybdenum core block, the lower end plug 1 is embedded in the port at one end of the cladding tube 3, the tungsten-containing sample 6 is embedded in the port at the other end of the cladding tube 3, and the air cavity spring 4 is arranged in the cladding tube 3 between the molybdenum core block 2 and the tungsten-containing sample 6. The upper end weld position 5 is located outside the tungsten-containing sample 6. The manufacturing process of the tungsten dispersed zirconium-based standard rod comprises the following steps.

[0039] Step 1, preparation of tungsten-containing samples, homogenizing tungsten powder and zirconium powder in a preset ratio in an argon-protected glove box to form a homogenized mixed powder; cold pressing and vacuum sintering the homogenized mixed powder, and then turning the tungsten-containing sample.

[0040] In a possible implementation, step 1 includes the following steps.

[0041] Step 11, multi-stage premixing, operate in a glove box, under an argon or helium protective atmosphere, mix tungsten powder and zirconium powder in a preset ratio, and repeat the grinding method of first mixing in a conical flask for 5 to 8 minutes, and then grinding in a grinding mortar for 5 to 8 minutes for three to five times. In step 11, in order to reduce the weighing error of tungsten and the loss of tungsten during the operation process, the multi-stage premixing process will adopt a multi-stage mixing method. The particle size of tungsten powder and zirconium powder is not higher than 75μm. First, prepare 10000ppm tungsten dispersed powder, then mix 1000ppm tungsten dispersed powder and zirconium powder to prepare 1000ppm tungsten dispersed powder, and finally mix 1000ppm tungsten dispersed powder and zirconium powder to prepare 100ppm tungsten dispersed powder.

[0042] Step 12, ball milling and mixing. To ensure uniform dispersion of tungsten powder in zirconium matrix, the premixed powder formed in step 11 is mixed again by ball milling to form a homogenized mixed powder. A full-range planetary ball mill is used. The ball milling jar and ball milling beads are made of 304 stainless steel balls. Argon (or helium) is filled into the ball milling jar for protection. The ball milling time is 2 to 5 hours, and the material-ball ratio is 1:5 to 1:15.

[0043] Step 13, uniformity detection, the mixed powder after homogenization treatment is divided into multiple samples in a glove box protected by argon or helium for chemical composition detection to detect the actual tungsten content of each sample.

[0044] Step 14, cold pressing, using a hydraulic universal material test press, cold pressing the homogenized mixed powder into multiple columnar samples. The forming mold is a floating female mold that can achieve bidirectional pressing, and the loading process is carried out in a glove box protected by argon or helium. The forming pressure is controlled at 2-4t, the female mold diameter is Φ10mm, and the sample height is controlled at 14-15mm.

[0045] Step 15, vacuum sintering, sintering each columnar sample to improve the strength of the green block to form a sintered sample. To avoid oxidation of the columnar sample during sintering, sintering is performed in a vacuum environment. The sintering temperature is controlled at about 1000°C and the sintering time is controlled at about 10 minutes.

[0046] Step 16, processing and forming, such as Figure 2 As shown, each sintered sample is prepared by turning to form a tungsten-containing sample that matches the shape of the fuel rod end assembly.

[0047] Step 17, check the appearance and size of the tungsten-containing sample to ensure that there are no scratches, dents or pits on the surface of the tungsten-containing sample.

[0048] Step 18, destructive testing of tungsten-containing samples, extract test samples from the same batch of tungsten-containing samples, take the head, middle and tail of the tungsten-containing samples respectively, process them into block samples, package and label the processed block samples, and then process the block samples into debris, mix them evenly and send them for chemical composition analysis, and finally determine the tungsten content of the standard rod.

[0049] Step 2, standard rod production, assembling and welding the tungsten-containing sample and the cladding tube according to the fuel rod production process to form a tungsten-containing standard rod. For example, step 2 may include the following steps.

[0050] Step 21, pressing the lower end plug into the cladding tube according to the fuel rod plugging process parameters.

[0051] Step 22, welding the lower end plug to the cladding tube according to the fuel rod ring welding process parameters.

[0052] Step 23, after the cladding tube with the lower end plug welded thereto is loaded with the molybdenum core and the air cavity spring, 1.96MPa to 2.6MPa of helium is filled in, and the tungsten-containing sample is pressed into the cladding tube according to the plugging process parameters of the fuel rod.

[0053] Step 24, welding the tungsten-containing sample to the cladding tube according to the fuel rod welding process parameters.

[0054] Step 25, such as Figure 1 As shown, the marking position of the standard rod is carried out in the area 10 mm away from the weld at the upper end of the standard rod.

[0055] Step 3: Perform functional verification and evaluation on the standard rod at a preset period, which shall not exceed 12 months. The evaluation of the standard rod includes: whether there are scratches, dents, or pits on the surface of the tungsten-containing sample.

[0056] The embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for manufacturing a tungsten dispersed zirconium-based standard rod, characterized in that: The method comprises: Step 1, preparation of tungsten-containing samples, homogenizing tungsten powder and zirconium powder of a preset ratio in an argon-protected glove box to form a mixed powder after homogenization, wherein the particle size of the tungsten powder and the zirconium powder is not higher than 75 μm; cold pressing and vacuum sintering of the mixed powder after homogenization are performed, and then lathe processing is performed to obtain tungsten-containing samples, and test samples are extracted from the tungsten-containing samples for chemical composition analysis, and the tungsten content of the standard rod is finally determined; Step 2: standard rod production: assembling and welding the tungsten-containing sample and the cladding tube according to the fuel rod production process to form a tungsten-containing standard rod; Step 3: Perform functional verification and evaluation on the standard rod at a preset period of no more than 12 months. The evaluation of the standard rod includes: whether there are scratches, dents, or pits on the surface of the tungsten-containing sample.

2. The method according to claim 1, characterized in that Step 1 includes: Step 11, multi-stage premixing, operating in a glove box, in an argon or helium protective atmosphere, mixing tungsten powder and zirconium powder in a preset ratio, and repeating the grinding method of first mixing in a conical flask for 5 to 8 minutes and then grinding in a grinding mortar for 5 to 8 minutes for three to five times; Step 12, ball milling, mixing the premixed powder formed in step 11 again by ball milling to form a mixed powder after homogenization; Step 13, uniformity detection, the mixed powder after homogenization treatment is divided into multiple samples in a glove box protected by argon or helium for chemical composition detection to detect the actual content of tungsten in each sample; Step 14, cold pressing, using a hydraulic universal material test press to cold press the homogenized mixed powder into a plurality of columnar samples; Step 15, vacuum sintering, sintering each columnar sample to form a sintered sample, and the sintering is performed under a vacuum environment; Step 16, machining and forming, machining each sintered sample by turning to form a tungsten-containing sample matching the shape of the fuel rod end assembly; Step 17, inspect the appearance and dimensions of the tungsten-containing sample to ensure that there are no scratches, dents or pits on the surface of the tungsten-containing sample; Step 18, destructive testing of tungsten-containing samples, extract test samples from the same batch of tungsten-containing samples, take the head, middle and tail of the tungsten-containing samples respectively, process them into block samples, package and label the processed block samples, and then process the block samples into debris, mix them evenly and send them for chemical composition analysis, and finally determine the tungsten content of the standard rod.

3. The method according to claim 1, characterized in that In step 11, the multi-stage premixing process will adopt a multi-stage mixing method; first, a 10000ppm tungsten dispersed powder is prepared, and then the 10000ppm tungsten dispersed powder and zirconium powder are mixed to prepare a 1000ppm tungsten dispersed powder, and finally the 1000ppm tungsten dispersed powder and zirconium powder are mixed to prepare a 100ppm tungsten dispersed powder.

4. The method according to claim 1, characterized in that: In step 12, an omnidirectional planetary ball mill is used, the ball mill jar and the ball mill beads are made of 304 stainless steel balls, the ball mill jar is filled with argon or helium for protection, the ball milling time is 2 to 5 hours, and the material-to-ball ratio is 1:5 to 1:

15.

5. The method according to claim 1, characterized in that In step 14, the molding mold is a floating female mold capable of realizing bidirectional pressing, and the loading process is carried out in a glove box protected by argon or helium.

6. The method according to claim 1, characterized in that In step 14, the molding pressure is controlled at 2-4t, the diameter of the female mold is 10mm, and the sample height is controlled at 14-15mm.

7. The method according to claim 1, characterized in that In step 15, the sintering temperature is controlled at 1000° C. and the sintering time is controlled at 10 minutes.

8. The method according to claim 1, characterized in that: Step 2 includes: Step 21, pressing the lower end plug into the cladding tube according to the fuel rod plugging process parameters; Step 22, welding the lower end plug and the cladding tube according to the fuel rod ring welding process parameters; Step 23, after the cladding tube with the lower end plug welded thereto is loaded with the molybdenum core body and the air cavity spring, 1.96MPa to 2.6MPa of helium is filled in, and the tungsten-containing sample is pressed into the cladding tube according to the plugging process parameters of the fuel rod; Step 24, welding the tungsten-containing sample to the cladding tube according to the fuel rod welding process parameters; Step 25, as shown in FIG1, marks the position of the standard rod in an area 10 mm away from the weld at the upper end of the standard rod.

9. A tungsten-dispersed zirconium-based standard rod, characterized in that: The tungsten dispersed zirconium-based standard rod is manufactured by the method described in any one of claims 1-8.

10. The tungsten dispersed zirconium-based standard rod according to claim 9, characterized in that: The tungsten dispersed zirconium-based standard rod comprises: Lower end plug, molybdenum pellet, cladding tube, air cavity spring, tungsten-containing sample; The cladding tube is wrapped around the outside of the molybdenum core block, the lower end plug is embedded in the port at one end of the cladding tube, the tungsten-containing sample is embedded in the port at the other end of the cladding tube, and the air cavity spring is arranged in the cladding tube between the molybdenum core block and the tungsten-containing sample.

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