Method for measuring displacement of fuel pellets within a fuel rod during shearing of a fuel assembly

Abstract

Embodiments of the present application relate to the technical field of spent fuel reprocessing, and particularly to a method for measuring displacement of fuel rod inner pellets when fuel assembly is sheared, comprising: providing a plurality of force measuring connectors and a plurality of force measuring devices; arranging the force measuring connectors in a part of the gas cavity of the fuel rod, and connecting one end of the force measuring connectors with the fuel pellets; connecting the plurality of force measuring devices with the plurality of force measuring connectors one by one at the end of the shell close to the gas cavity, and contacting the other end of the force measuring connectors with the force measuring devices; when the fuel assembly is sheared, the axial displacement force towards the gas cavity is generated due to the extrusion of the fuel pellets, the force measuring connectors transmit the displacement force to the force measuring devices, and the displacement force measured by the force measuring devices is collected and recorded. The measurement method in the embodiments of the present application can measure the displacement force generated by the extrusion of the fuel pellets when the fuel assembly is sheared, so as to modify the shearing process parameters and achieve better shearing effect.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of spent fuel reprocessing technology, specifically to a method for measuring the displacement of the core block inside the fuel rod during fuel assembly shearing. Background Technology

[0002] The statements herein are provided merely as background information relating to the invention and do not necessarily constitute prior art. The reprocessing of spent fuel assemblies generally includes shearing of the spent fuel assembly, chemical dissolution of fuel segments, chemical separation, and tailing of uranium and plutonium. During the shearing process of spent fuel assemblies, the shearing device needs to cut the ends and fuel segments of the spent fuel assembly to obtain short segments of a predetermined length for subsequent chemical dissolution processing. Summary of the Invention

[0003] This invention provides a method for measuring the displacement of fuel pellets within a fuel rod during fuel assembly shearing, used to measure the displacement of the fuel pellets during fuel assembly shearing. The fuel assembly includes: a housing; and multiple fuel rods disposed within the housing. Each fuel rod includes a fuel pellet and a sheath. The fuel pellet is disposed within a portion of the sheath, extending axially from one end of the sheath to the middle of the sheath. The remaining portion within the sheath forms a gas cavity.

[0004] The method for measuring the displacement of fuel pellets inside fuel rods during fuel assembly shearing provided in the embodiments of the present invention includes: providing multiple force-measuring connectors and multiple force-measuring devices; before shearing the fuel assembly, setting force-measuring connectors in the gas chamber of a portion of the fuel rods, and connecting one end of the force-measuring connectors to the fuel pellets; connecting multiple force-measuring devices to one end of the housing near the gas chamber, with each force-measuring device corresponding to one of the multiple force-measuring connectors, and contacting the other end of the force-measuring connectors with the force-measuring devices; when shearing the fuel assembly, an axial displacement force is generated towards the gas chamber due to the compression of the fuel pellets, the force-measuring connectors transmit the displacement force to the force-measuring devices, and the displacement force measured by the force-measuring devices is collected and recorded.

[0005] The measurement method in this embodiment of the invention connects one end of multiple force-measuring connectors to the fuel pellet and the other end to multiple force-measuring devices. During the shearing of the fuel assembly, the force-measuring connectors transmit the detected displacement force to the force-measuring devices to obtain the displacement force measurement result. This allows for modification of the shearing process parameters, ensuring that the sheared fuel segment meets the predetermined length and achieves a better shearing effect. Furthermore, by corresponding each force-measuring connector to a different force-measuring device, the displacement force generated when the fuel rod is sheared at different locations can be obtained, satisfying the multi-point measurement requirement of displacement force and ensuring the accuracy and reliability of the measurement results. Attached Figure Description

[0006] Other objects and advantages of the invention will become apparent from the following description of embodiments of the invention with reference to the accompanying drawings, and will help to provide a comprehensive understanding of the invention.

[0007] Figure 1 This is a schematic diagram of the structure of a fuel assembly according to an embodiment of the present invention.

[0008] Figure 2 This is a flowchart illustrating a method for measuring the displacement of fuel pellets during the shearing of a fuel assembly according to an embodiment of the present invention.

[0009] Figure 3 This is a schematic diagram of the layout of a measuring device according to an embodiment of the present invention.

[0010] Figure 4 yes Figure 3 Enlarged view of the layout of the measuring device.

[0011] Figure 5 This is an internal schematic diagram of a force measuring device according to an embodiment of the present invention.

[0012] Figure 6 This is a schematic diagram of the layout of a displacement measuring device according to an embodiment of the present invention.

[0013] Explanation of reference numerals in the attached figures:

[0014] 10. Shell;

[0015] 20. Fuel rod; 21. Fuel pellet; 22. Sheath; 23. Gas chamber; 24. End plug; 25. Elastic element; 26. Pad;

[0016] 30. Force-measuring connector; 40. Force-measuring device;

[0017] 50. Mounting plate; 51. Screws;

[0018] 60. Fixing plate; 61. Connecting cylinder; 80. Displacement measuring component.

[0019] It should be noted that the accompanying drawings are not necessarily drawn to scale, but are shown only in a schematic manner without affecting the reader's understanding. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only one embodiment of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the described embodiments of this application without creative effort are within the scope of protection of this application.

[0021] It should be noted that, unless otherwise defined, the technical or scientific terms used in this application should have the ordinary meaning understood by a person with ordinary skill in the art to which this application pertains. Where the terms "first," "second," etc., are used throughout the text, they are used only to distinguish similar objects and should not be construed as indicating or implying their relative importance, order of precedence, or implicitly specifying the number of technical features indicated. It should be understood that the data described by "first," "second," etc., can be interchanged where appropriate. Where "and / or" appears throughout the text, it means including three parallel solutions. Taking "A and / or B" as an example, it includes solution A, or solution B, or a solution that satisfies both A and B. Furthermore, for ease of description, spatial relative terms such as "above," "below," "top," "bottom," etc., may be used here, only to describe the spatial positional relationship between one device or feature as shown in the figure and other devices or features. It should be understood that this also includes different orientations in use or operation besides those shown in the figure.

[0022] It should also be noted that, in order to avoid obscuring the invention with unnecessary details, only the device structure and / or processing steps closely related to the solution according to the invention are shown in the accompanying drawings, while other details that are not closely related to the invention are omitted.

[0023] The inventors of this invention have discovered that during the shearing process of the fuel assembly, each shearing causes the fuel pellets inside the assembly to move towards the unsheared portion due to compression, thereby generating displacement force and displacement distance. This can easily lead to uneven lengths of the fuel segments obtained from the shearing, thus affecting the shearing effect.

[0024] like Figure 1 As shown, the fuel assembly in this embodiment includes a housing 10 and a plurality of fuel rods 20. The plurality of fuel rods 20 are disposed within the housing 10. Each fuel rod 20 includes a fuel pellet 21 and a casing 22. The fuel pellet 21 is disposed within a portion of the casing 22, extending axially from one end of the casing 22 to the middle of the casing 22. The remaining portion within the casing 22 forms a gas chamber 23, that is, the gas chamber 23 extends axially from the middle of the casing 22 to the other end of the casing 22.

[0025] like Figure 1 As shown, in some embodiments, the fuel rod 20 may further include an end plug 24 and an elastic member 25. The end plug 24 is connected to the end of the casing 22 away from the gas chamber 23 to seal the fuel rod 20. For example, the end plug 24 and the casing 22 may be connected by welding. The elastic member 25 abuts between the fuel pellet 21 and the end plug 24 to provide preload to the fuel pellet 21 and prevent the fuel pellet 21 from moving axially during use.

[0026] like Figure 5As shown, in some embodiments, the fuel rod 20 may also include a pad 26, which is disposed at one end of the fuel core 21 of the fuel rod 20 near the gas chamber 23, and the pad 26 has a through hole in the axial direction.

[0027] The method for measuring the displacement of the fuel core block inside the fuel rod during fuel assembly shearing provided in the embodiments of the present invention is used to measure the displacement distance of the fuel core block and the displacement force generated by it when the fuel assembly of any embodiment of the present invention is sheared.

[0028] Please see Figure 2 The method for measuring the displacement of the fuel rod core during fuel assembly shearing provided in the embodiments of the present invention includes the following steps S100 to S400.

[0029] Step S100: Provide multiple force measuring connectors 30 and multiple force measuring devices 40.

[0030] Step S200: Before shearing the fuel assembly, a force measuring connector 30 is installed in the gas chamber 23 of a portion of the fuel rod 20, and one end of the force measuring connector 30 is connected to the fuel pellet 21.

[0031] Step S300: Connect multiple force measuring devices 40 to one end of the housing 10 near the air chamber 23. Each force measuring device 40 corresponds to a force measuring connector 30. The other end of the force measuring connector 30 is then brought into contact with the force measuring device 40.

[0032] Step S400: When the fuel assembly is sheared, an axial displacement force is generated towards the gas chamber 23 due to the compression of the fuel pellet 21. The force measuring connector 30 transmits the displacement force to the force measuring device 40, and collects and records the displacement force measured by the force measuring device 40.

[0033] In embodiments of the present invention, by connecting one end of multiple force-measuring connectors 30 to the fuel pellet 21 and the other end to multiple force-measuring devices 40, the force-measuring connectors 30 transmit the detected displacement force to the force-measuring devices 40 during the shearing of the fuel assembly, thereby obtaining the displacement force measurement result. This allows for modification of the shearing process parameters, ensuring that the sheared fuel segment conforms to the predetermined length and achieves a better shearing effect. Furthermore, by configuring multiple force-measuring connectors 30 and multiple force-measuring devices 40 in a one-to-one correspondence, the displacement force generated when the fuel rod 20 is sheared at different positions can be obtained, satisfying the multi-point measurement requirement of displacement force and ensuring the accuracy and reliability of the measurement results.

[0034] In some embodiments, when a force-measuring connector 30 is provided within a portion of the fuel rod 20 in step S200, one end of the force-measuring connector 30 can pass through the gas chamber 23 of the fuel rod 20 and be connected to the fuel pellet 21. The force-measuring connector 30 is a linkage-type force transmission mechanism. For example, the force-measuring connector 30 can be a force transmission rod.

[0035] like Figure 5 As shown, in some embodiments, when a force-measuring connector 30 is provided within a portion of the fuel rod 20 in step S200, one end of the force-measuring connector 30 can be connected to the pad 26 of the fuel rod 20. During the shearing of the fuel assembly, the axial displacement force towards the gas chamber 23 generated by compressing the fuel pellet 21 is transmitted to the force-measuring connector 30 through the pad 26, so that the force-measuring connector 30 is uniformly stressed, thereby improving the accuracy of the measurement results.

[0036] like Figure 3 and Figure 4 As shown, in some embodiments, when multiple force measuring devices 40 are connected to one end of the housing 10 near the air cavity 23 in step S300, the specific steps include: Step S310, detachably connecting the multiple force measuring devices 40 to one side of the mounting plate 50. Step S320, connecting the mounting plate 50 to one end of the housing 10 near the air cavity 23, wherein the side connected to the force measuring devices 40 faces the housing 10, so as to facilitate contact between the force measuring devices 40 and the force measuring connector 30, thereby realizing the transmission of displacement force.

[0037] In some embodiments, when the plurality of force measuring devices 40 are detachably connected to one side of the mounting plate 50 in step S310, the method may further include: providing the mounting plate 50, wherein one side of the mounting plate 50 is configured to connect the plurality of force measuring devices 40. In this embodiment, the plurality of force measuring devices 40 are threadedly connected to the mounting plate 50 to ensure the reliability of the connection and to facilitate the disassembly and installation of the force measuring devices 40.

[0038] In this embodiment, in step S310, multiple force measuring devices 40 are detachably connected to one side of the mounting plate 50 so that the mounting plate 50 can support and fix the force measuring devices 40, preventing them from moving or loosening during the shearing process and causing measurement errors. Furthermore, detachably connecting the force measuring devices 40 to one side of the mounting plate 50 facilitates the disassembly and replacement of one or more force measuring devices 40 in case of malfunction, improving work efficiency.

[0039] like Figure 3 and Figure 4As shown, in some embodiments, when the mounting plate 50 is connected to the end of the housing 10 near the air cavity 23 in step S320, it specifically includes: step S321, connecting a fixing plate 60 to the end of the housing 10 near the air cavity 23, so that the fixing plate 60 closes the housing 10, wherein the fixing plate 60 has a plurality of through holes, and the plurality of through holes correspond one-to-one with a plurality of force measuring connectors 30. When connecting the fixing plate 60, the force measuring connectors 30 are passed through the through holes so that they extend outside the housing 10 so as to contact the force measuring device 40; step S322, connecting the mounting plate 50 parallel to the side of the fixing plate 60 away from the housing 10, so that the force measuring device 40 on the mounting plate 50 corresponds one-to-one with the force measuring connectors 30 and contacts them, so as to realize the transmission of displacement force.

[0040] In some embodiments, the fixing plate 60 may be configured to match the shape and size of the housing 10 so that the fixing plate 60 can close the housing 10.

[0041] In some embodiments, in step S321, when the fixing plate 60 is connected to one end of the housing 10 near the gas chamber 23, for example, the fixing plate 60 and the housing 10 can be fixedly connected by welding so that the fixing plate 60 seals the housing 10 of the fuel assembly.

[0042] like Figure 4 As shown, in some embodiments, when connecting the mounting plate 50 to the fixing plate 60 in step S322, the mounting plate 50 can be detachably connected to the fixing plate 60 by screws 51, so as to facilitate the disassembly and replacement of the mounting plate 50.

[0043] In some embodiments, when connecting the fixing plate 60, the casing 22 of the fuel rod 20 can be fixedly connected to the fixing plate 60 to secure the casing 22, thereby ensuring the stability of the fuel assembly structure and preventing the fuel rod 20 in the fuel assembly from loosening or moving during shearing. For example, the casing 22 of the fuel rod 20 can be fixedly connected to the fixing plate 60 by welding.

[0044] In some embodiments, a connecting cylinder 61 is formed on one side of the fixing plate 60. The connecting cylinder 61 has the same shape and size as the housing 10. A receiving space is formed between the fixing plate 60, the connecting cylinder 61 and the mounting plate 50 so that the force measuring device 40 is received in the receiving space, thereby so that the multiple force measuring connectors 30 and the multiple force measuring devices 40 correspond to and contact each other in the receiving space.

[0045] In some embodiments, a mounting plate 50 to which the force measuring device 40 is connected is detachably connected to the end of the connecting cylinder 61 away from the fixed plate 60, wherein the side of the mounting plate 50 to which the force measuring device 40 is connected faces the connecting cylinder 61, so that a receiving space is formed between the fixed plate 60, the connecting cylinder 61 and the mounting plate 50, thereby allowing the force measuring device 40 to be received within the receiving space.

[0046] like Figure 6 As shown, in some embodiments, the measurement method may further include: step S510, providing a plurality of displacement measuring elements 80; step S520, movably setting the displacement measuring element 80 in the gas cavity 23 of another portion of the fuel rod 20, and connecting one end of the displacement measuring element 80 to the fuel pellet 21, and extending the other end to the outside of the housing 10; step S530, when shearing the fuel assembly, the displacement force drives the fuel pellet 21 to move toward the gas cavity 23, and drives the displacement measuring element 80 to move; step S540, after each shearing, measuring the length of the portion of the displacement measuring element 80 located outside the housing 10; step S550, determining the displacement of the fuel pellet 21 based on the length of the portion of the displacement measuring element 80 located outside the housing 10.

[0047] In this embodiment, a force-measuring connector 30 is installed in the gas chamber 23 of a portion of the fuel rods 20, and a force-measuring device 40 is installed in a one-to-one correspondence with the force-measuring connector 30 to measure the displacement force. A displacement measuring device 80 is installed in the gas chamber 23 of another portion of the fuel rods 20 to measure the displacement amount. Specifically, when the fuel assembly is sheared, the displacement force drives the fuel pellets 21 of the fuel rods 20 to move towards the gas chamber 23, causing the force-measuring connector 30 in the portion of the fuel rods 20 equipped with the force-measuring connector 30 to transmit the displacement force to the force-measuring device 40. By collecting and recording the data measured by the force-measuring device 40, displacement force data is obtained. Additionally, the displacement measuring device 80 in the other portion of the fuel rods 20 equipped with the displacement measuring device 80 is moved, and by measuring the length of the displacement measuring device 80 located outside the housing 10, displacement amount data is obtained. Thus, displacement data of the fuel rods 20 at different positions in the fuel assembly are obtained, achieving simultaneous measurement of displacement force and displacement amount.

[0048] In some embodiments, when a displacement measuring element 80 is provided in another portion of the fuel rod 20 in step S520, one end of the displacement measuring element 80 can pass through the gas chamber 23 of the fuel rod 20 and be connected to the fuel pellet 21. For example, the displacement measuring element 80 can be a connecting rod or an extension rod.

[0049] In some embodiments, when a displacement measuring element 80 is provided in another portion of the fuel rod 20 in step S520, one end of the displacement measuring element 80 can be connected to the pad 26 of the fuel rod 20. During the shearing of the fuel assembly, the axial displacement force towards the gas chamber 23 generated by compressing the fuel pellet 21 is transmitted to the displacement measuring element 80 through the pad 26, so that the displacement measuring element 80 is uniformly stressed, thereby causing the displacement measuring element 80 to produce axial displacement.

[0050] In some embodiments, the mounting plate 50 at one end of the housing 10 has a plurality of through holes corresponding to the displacement measuring element 80. When connecting the mounting plate 50, the displacement measuring element 80 passes through the corresponding through holes so that it protrudes from the surface of the mounting plate 50 away from the housing 10. After each shearing, the length of the portion of the displacement measuring element 80 protruding from the mounting plate 50 is measured, and the displacement of the fuel pellet 21 is determined based on this length, thereby achieving the measurement of the displacement of the fuel pellet 21 of the fuel rod 20.

[0051] In some embodiments, the housing 10 is a regular hexagonal cylinder, and a plurality of fuel rods 20 are arranged in an array inside the housing 10. A plurality of force measuring connectors 30 are disposed in the fuel rods 20 at different positions relative to the central axis of the housing 10, so as to obtain displacement force data generated by the compression of fuel pellets 21 in the fuel rods 20 at different positions.

[0052] In this embodiment, the fuel rod 20 in the fuel assembly that does not have a force measuring connector 30 inside is a fuel rod 20 that has a displacement measuring component 80 inside, so as to simultaneously measure the displacement force and displacement amount generated by the compression of the fuel pellet 21 in the fuel rod 20 at different positions.

[0053] In some embodiments, when arranging multiple force measuring devices 40, the multiple force measuring devices 40 can be arranged in a straight line at one end of the housing 10, or the multiple force measuring devices 40 can be arranged in an array at one end of the housing 10, thereby realizing the measurement of the displacement force of the fuel rod 20 at different positions.

[0054] In this embodiment, both displacement force and displacement amount are measured continuously and without interruption to obtain all displacement force and displacement amount data during the shearing of the fuel assembly. Specifically, after each shearing of the fuel assembly, the control system collects and records the displacement force measured by each force measuring device 40 to obtain the displacement force, and manually measures the length of the displacement measuring component 80 protruding from the mounting plate 50 to obtain the displacement amount. Finally, after shearing is completed, the displacement force and displacement amount obtained from each shearing are summarized, and the fuel rod with the maximum displacement force and the largest displacement amount are selected as references for modifying the shearing process parameters, thereby adjusting the shearing parameters to achieve a better shearing effect.

[0055] In this embodiment, the displacement force is measured by setting a force measuring device 40 at the end of the fuel assembly, rather than by setting the measuring device inside the fuel assembly. This ensures the integrity of the main structure of the fuel assembly and enables efficient and convenient measurement of the displacement of the fuel pellet 21. In addition, using an external structure to measure the displacement facilitates the disassembly and replacement of the measuring device, reducing measurement costs.

[0056] Regarding the embodiments of the present invention, it should also be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to obtain new embodiments.

[0057] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for measuring the displacement of the core block inside the fuel rod during fuel assembly shearing, characterized in that, The fuel assembly includes: case; Multiple fuel rods are disposed within the housing. Each fuel rod includes a fuel pellet and a casing. The fuel pellet is disposed within a portion of the casing and extends axially from one end of the casing to the middle of the casing. The remaining portion within the casing forms a gas chamber. The method includes: Provides multiple force-measuring connectors and multiple force-measuring devices; Before shearing the fuel assembly, a force-measuring connector is provided in the gas chamber of a portion of the fuel rods, and one end of the force-measuring connector is connected to the fuel pellet. Multiple force measuring devices are connected to one end of the housing near the air cavity. Each force measuring device corresponds to a force measuring connector, and the other end of the force measuring connector is in contact with the force measuring device. When the fuel assembly is sheared, an axial displacement force is generated towards the gas chamber due to the compression of the fuel pellet. The force measuring connector transmits the displacement force to the force measuring device, which collects and records the displacement force measured by the force measuring device.

2. The method according to claim 1, characterized in that, The method of connecting multiple force measuring devices at one end of the housing near the air cavity includes: The plurality of force measuring devices are detachably connected to one side of the mounting plate; The mounting plate is connected to the end of the housing near the air chamber, wherein the side connected to the force measuring device faces the housing.

3. The method according to claim 2, characterized in that, The step of connecting the mounting plate to the end of the housing near the air cavity includes: A fixing plate is connected to one end of the housing near the air cavity to close the housing; wherein the fixing plate has a plurality of through holes, each of which corresponds to a plurality of force-measuring connectors; when connecting the fixing plate, the force-measuring connectors are passed through the through holes to extend to the outside of the housing. The mounting plate is connected parallel to the side of the fixing plate away from the housing, so that the force measuring device on the mounting plate corresponds to and contacts the force measuring connector.

4. The method according to claim 3, characterized in that, When connecting the fixing plate, the fuel rod casing is fixedly connected to the fixing plate to secure the casing.

5. The method according to claim 3, characterized in that, A connecting cylinder is formed on one side of the fixing plate. The connecting cylinder has the same shape and size as the housing. A receiving space is formed between the fixing plate, the connecting cylinder and the mounting plate so that the force measuring device can be accommodated in the receiving space.

6. The method according to claim 5, characterized in that, The mounting plate to which the force measuring device is connected is detachably connected to the end of the connecting cylinder away from the fixed plate.

7. The method according to any one of claims 1-6, characterized in that, Also includes: Provides multiple displacement measuring elements; The displacement measuring element is movably disposed in the gas chamber of another portion of the fuel rod, and one end of the displacement measuring element is connected to the fuel pellet, while the other end extends to the outside of the housing; When the fuel assembly is sheared, the displacement force drives the fuel pellet to move toward the gas chamber, and also moves the displacement measuring element. After each shearing, the length of the displacement measuring element located outside the housing is measured; The displacement of the fuel pellet is determined based on the length.

8. The method according to claim 7, characterized in that, The mounting plate at one end of the housing has multiple through holes corresponding to the displacement measuring element; wherein, When connecting the mounting plate, the displacement measuring element is passed through the corresponding through hole so that the displacement measuring element protrudes from the surface of the mounting plate away from the housing. After each cut, the length of the displacement measuring element protruding from the mounting plate is measured; The displacement of the fuel pellet is determined based on the length.

9. The method according to claim 1, characterized in that, The shell is a regular hexagonal cylinder, and multiple fuel rods are arranged in an array inside the shell; Multiple force-measuring connectors are disposed within fuel rods at different positions relative to the central axis of the housing.

10. The method according to claim 9, characterized in that, The plurality of the force measuring devices are arranged in a straight line at one end of the housing; or... Multiple force measuring devices are arranged in an array at one end of the housing.

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