Test apparatus and test method

Abstract

To evaluate the performance of a fuel assembly.SOLUTION: A testing device for testing the dispersion state of a fuel dispersed from a fuel rod of a fuel aggregate includes: a test body including a test target tube filled with particles corresponding to a fuel pellet and a simulated fuel rod as a simulated fuel aggregate arranged around the test target tube; a mobile device for moving the test body; a heating furnace arranged in the moving range of the mobile body; and a controller for controlling the movement of the mobile device and controlling the heating state of the test body in the heating furnace.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a test apparatus and a test method.

Background Art

[0002] Techniques for evaluating the characteristics of a nuclear reactor are known. For example, Patent Document 1 describes a test method for testing the performance of a cladding tube of a fuel rod. Patent Document 1 discloses a test method for a fuel cladding tube test piece, in which an internal heater is inserted into a fuel cladding tube test piece with hydrogen added, the fuel cladding tube test piece is sealed in a pressure vessel, and then the fuel cladding tube test piece is heated with the internal heater and the internal pressure of the fuel cladding tube test piece is increased to a predetermined pressure, and the fuel cladding tube test piece is adjusted to a predetermined temperature by an external heater and a cooling tube provided outside the pressure vessel.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] With the test method described in Patent Document 1, the performance of a fuel cladding tube can be evaluated. However, the characteristics of a nuclear reactor have various characteristics, and it is necessary to evaluate the performance other than that of the fuel cladding tube.

[0005] The present disclosure solves the above-described problems, and an object thereof is to provide a test apparatus and a test method capable of evaluating the performance of a fuel assembly.

Means for Solving the Problems

[0006] The test apparatus according to the present disclosure is a test apparatus for testing the scattering state of fuel scattered from the fuel rods of a fuel assembly, and includes a test object tube filled with particles corresponding to fuel pellets, and a simulated fuel rod arranged around the test object tube to simulate the fuel assembly, a test body including the simulated fuel rod, a moving device for moving the test body, a heating furnace arranged in the moving range of the test body, and a control device for controlling the movement of the moving device and the heating state of the test body by the heating furnace.

[0007] The test method according to the present disclosure is a test method for testing the scattering state of fuel scattered from the fuel rods of a fuel assembly, and includes a step of fixing a test body including a test object tube filled with particles corresponding to fuel pellets and a simulated fuel rod arranged around the test object tube to simulate the fuel assembly to a moving device, and a step of moving the test body relative to a heating furnace by the moving device, controlling the heating of the test body by the heating furnace, and rupturing the test object tube.

Advantages of the Invention

[0008] According to the present disclosure, the performance of the fuel assembly can be evaluated.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

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Figure 8

[0010] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Note that the present disclosure is not limited by this embodiment, and when there are a plurality of embodiments, those configured by combining each embodiment are also included.

[0011] FIG. 1 is a schematic diagram showing the schematic configuration of the test apparatus. FIG. 2 is an enlarged view showing the test piece and the heating furnace in an enlarged manner. FIG. 3 is a perspective view showing the schematic configuration of the test target tube of the test piece and the simulated fuel rod. FIG. 4 is a schematic diagram showing the schematic configuration of the test target tube. The test apparatus of this embodiment is a test apparatus that simulates a fuel rod when a Loss of Coolant Accident (LOCA) occurs in a nuclear reactor. Specifically, it is an apparatus that tests and evaluates the scattering of fuel pellet pieces discharged from the fuel rod into the interior of the fuel assembly when the cladding tube of the fuel rod ruptures. The test apparatus 10 includes a test piece 12, a moving device 14, a heating furnace 16, a control device 18, and an evaluation device 19. In addition, the test apparatus 10 of this embodiment has heat insulating materials 70 and 72. Note that it is preferable for the test apparatus 10 to include at least one of the heat insulating materials 70 and 72, but it may not include them.

[0012] The test piece 12 is a structure that simulates a fuel assembly. The test piece 12 includes a frame 20, a test target tube 22, a simulated fuel rod 24, a scattering guard 26, and a temperature sensor 28.

[0013] The frame 20 is a structure that supports the test target tube 22 and the simulated fuel rod 24. The frame 20 has a plate-like bottom surface that supports the test target tube 22 and the lower surface in the vertical direction of the simulated fuel rod 24. The bottom surface of the frame 20 corresponds to a plate-like member that supports the fuel assembly 24.

[0014] The test specimen 12 has a test target tube 22 and a simulated fuel rod 24 arranged in a frame 20 in an arrangement simulating the fuel rods of the fuel assembly to be evaluated. Here, the fuel assembly is formed in a square cross-sectional shape and is composed of, for example, 17×17 cells. And among the 17×17 cells, control rods are inserted into 24 cells respectively, and for example, in-core instrumentation is inserted into the cell at the center of the assembly. At this time, the cell into which the control rod is inserted is called a control rod guide tube, and the cell into which the in-core instrumentation is inserted is called an instrumentation guide tube. In addition, fuel rods are inserted into the other cells respectively. When the fuel assembly is used in a boiling water reactor (BWR), the outside of the fuel assembly is covered with a channel box. On the other hand, when the fuel assembly is used in a pressurized water reactor (PWR), the outside of the fuel assembly is open. And in the case of BWR, there is an inter-assembly gap outside the channel box, and in the case of PWR, there is an inter-assembly gap outside the fuel assembly.

[0015] As shown in FIG. 3, in the test specimen 12 of the present embodiment, at least one of the positions where the fuel rods are arranged is the test target tube 22. Further, in the test specimen 12, simulated fuel rods 24 are arranged at the positions where the fuel rods are arranged and at the positions where the instrumentation guide tubes are arranged.

[0016] If the test target tube 22 ruptures during the test, granular or fragmental objects corresponding to fuel (hereinafter referred to as granular bodies) will scatter. As shown in Fig. 4, the test target tube 22 has a coating tube 30, granular pellets 32, and a solid body 34. The coating tube 30 is a cylindrical structure that simulates the fuel cladding tube of a fuel rod. The coating tube is preferably formed of the same material as the fuel cladding tube, but a material that causes the same rupture as the fuel cladding tube during LOCA under the new temperature conditions may also be used. The granular pellets 32 are arranged inside the coating tube 30 and are a substance that simulates pellets (scattering granular or fragmental objects) that become granular bodies inside the fuel rod when LOCA occurs. For the granular pellets 32, a material that does not liquefy when heated in the test apparatus 10, for example, ceramic powder, can be used. The granular pellets 32 can use a granular substance with a long side of 2 mm. The length of the long side is not limited to 2 mm. A granular substance with a particle size of about 0.1 to 4 mm, or more, which is assumed to be practical, can be used. In the test, for example, granular pellets with a mesh opening of 1 to 3 mm are used. The solid body 34 is arranged in the area of the coating tube 30 where the granular pellets 32 are not filled. The solid body 34 is arranged in the area where no cracks occur in the coating tube 30. The area where no cracks occur can be specified based on the test conditions. Note that the test target tube 22 may be filled only with the granular pellets 32 without arranging the solid body 34 inside.

[0017] Returning to Figs. 1 and 2, the description of the test apparatus 10 will be continued. The simulated fuel rod 24 is an annular structure with an outer diameter corresponding to that of a fuel rod and an instrumentation guide tube. The simulated fuel rod 24 is a structure for arranging the structure around the test target tube 22 in the same arrangement as a fuel assembly. The simulated fuel rod 24 is arranged in the space around the test target tube 22 and only needs to have the same arrangement as the fuel rods and instrumentation guide tubes in the fuel assembly. It may be a tube with a hollow inside or a solid cylinder inside. The simulated fuel rod 24 may have a heater or measuring equipment arranged inside.

[0018] The scattering guard 26 is arranged on the frame 20 and is a cylinder that covers the periphery of the side surface of the area where the test target tube 22 and the simulated fuel rod 24 are arranged. The test target tube 22 and the simulated fuel rod 24 are arranged inside the cylinder of the scattering guard 26.

[0019] The temperature sensor 28 measures the temperature inside the test body 12. The temperature sensor 28 of the present embodiment measures the temperature of the test target tube 22. Note that the number and arrangement positions of the temperature sensors 28 are not limited. The temperature sensor 28 may be arranged at a position where the temperature at a desired position of the test body 12 can be specified by calculation based on the detection result.

[0020] The moving device 14 supports the test body 12 and moves the test body 12 along the uniaxial direction 56 with respect to the heating furnace 16. The moving device 14 includes a stage 50, a drive shaft 52, and a drive source 54. The stage 50 is a table on which the test body 12 is placed. The drive shaft 52 is a rod-shaped member connected to the stage 50. The drive source 54 moves the stage 50 by moving the drive shaft 52 along the uniaxial direction 56. The drive source 54 only needs to move the drive shaft 52 in the uniaxial direction 56. As long as the position of the stage 50 can be controlled, an electric linear motion mechanism, a hydraulic cylinder, or an air cylinder may be used.

[0021] The heating furnace 16 heats the test body 12. The heating furnace 16 includes a housing 60, a heating source 62, and a furnace core tube 64. The housing 60 is arranged within the moving range of the stage 50 of the moving device 14, and an opening through which the stage 50 can move is formed at a position facing the stage 50. A part of the inside of the housing 60 serves as a heating region 66. The heating source 62 is an electric heater that generates heat by electricity. The heating source 62 is arranged around the heating region 66 of the housing 60. In the heating furnace 16, the heating region 66 is heated to a predetermined temperature by the heat generation of the heating source 62. Note that a temperature distribution may be formed in the heating region 66 in the uniaxial direction 56. The furnace core tube 64 is a cylindrical structure arranged on the inner wall of the housing 66. The furnace core tube 64 is formed of, for example, quartz. The furnace core tube 64 insulates the heating region 66 of the heating furnace 16. In the present embodiment, the heating source 62 is an electric heater heated by electricity, but the type of the heating source 62 is not limited. The heating source 62 may have a structure in which a heating fluid is supplied inside, or a structure in which fuel is burned to raise the temperature.

[0022] The heat insulating material 70 is disposed on the upper surface of the test piece 12 (the surface opposite to the moving device 14), that is, one end of the test piece 12 in the moving direction. The heat insulating material 70 insulates the upper surface of the test piece 12 in the vertical direction. Further, the heat insulating material 70 holds members such as wiring of measuring instruments inside to suppress temperature rise. The heat insulating material 72 is disposed on the lower surface of the test piece 12 (the surface on the moving device 14 side), that is, the other end of the test piece 12 in the moving direction. The heat insulating material 72 of the present embodiment is fixed to the drive shaft 52. The heat insulating material 72 insulates the lower surface of the test piece 12 in the vertical direction. By providing the heat insulating materials 70 and 72, the test device 10 can appropriately manage the temperature around the test piece 12. Further, by reducing heat dissipation, the energy used for heating can be reduced.

[0023] The control device 18 controls the movement of the test piece 12 by the moving device 14. The control device 18 includes, for example, an arithmetic circuit such as a CPU (Central Processing Unit), a memory that stores various information such as arithmetic contents and programs, for example, at least one of a main storage device such as a RAM (Random Access Memory) and a ROM (Read Only Memory), and an external storage device such as an HDD (Hard Disk Drive). The control device 18 controls the moving device 14 based on preset conditions and the detection result of the temperature sensor 28 to control the position of the test piece 12 in the heating furnace 16.

[0024] The evaluation device 19 evaluates the test result of the test piece 12. The evaluation device 19 includes an arithmetic processing device that inputs and analyzes the test result, a photographing device that acquires an image of the test result, a measuring device that measures the test result, and the like. The evaluation device 19 acquires information on the test result of the test piece 12 and outputs an evaluation result obtained by evaluating the acquired test result and the test result. Examples of the output device include a display device and an output device such as a printer.

[0025] (Test method) FIG. 5 is a flowchart for explaining the processing flow of the test apparatus according to the present embodiment. FIG. 6 is an explanatory diagram for explaining an example of the test method. FIG. 7 is a schematic diagram showing an example of the evaluation result of the evaluation apparatus. The processing shown in FIG. 5 is executed by the work of an operator, the control of the control device 18, and the processing by the evaluation device 19.

[0026] First, an operator manufactures a test piece (step S12). For example, the operator creates a structure in which the simulated fuel pipe 24 is arranged on the frame 20. Next, the operator fills the inside of the test target pipe 22 with granular pellets 22 and fixes the test target pipe 22 at a predetermined position on the frame 20. Further, the test target pipe 22 may be fixed to the heat insulating material 70, and the heat insulating material 70 may be fixed to the frame 20. Also, a temperature sensor 28 is installed at a necessary position of the test piece 12. Note that the test piece 12 may be reusable except for the test target pipe 22.

[0027] Next, the operator installs the test piece 12 on the moving device 14 (step S14). The operator installs the test piece 12 on the stage 50 of the moving device 14.

[0028] Next, the test apparatus 10 starts heating the heating furnace 16 (step S16). The heating of the heating furnace 16 may be performed before step S14.

[0029] Next, after the heating region 66 of the heating furnace 16 reaches a predetermined temperature, the test apparatus 10 moves the test piece 12 to the heating region 66 of the heating furnace 16 (step S18). As shown in FIG. 6, the test apparatus 10 moves the test piece 12 to the heating region 66. The test apparatus 10 can control the temperature of the test piece 12 by moving the test piece 12 to the heating region 66 while controlling the moving speed with the moving device 14, and can simulate the heating state of the fuel assembly at the time of LOCA occurrence.

[0030] Next, the test apparatus 10 determines whether it is necessary to move the position of the test piece (step S20). The test apparatus 10 determines whether it is necessary to move the position of the test piece within the heating region 66 based on preset conditions. Also, the test apparatus 10 determines whether it is necessary to move the position of the test piece 12 based on the detection result of the temperature sensor 28 and the heating conditions.

[0031] If the test apparatus 10 determines that it is necessary to move the position of the test piece (Yes in step S20), it moves the test piece with the moving device (step S22). If the test apparatus 10 determines that it is not necessary to move the position of the test piece (No in step S20), it proceeds to step S24.

[0032] After performing the process of step S22 or when it determines No in step S20, the test apparatus 10 determines whether heating has ended (step S24). As criteria for determining whether heating has ended, for example, whether heating for a preset time has ended, whether the test target tube 22 has ruptured, etc. can be used.

[0033] If the test apparatus 10 determines that heating has not ended (No in step S24), it returns to step S20. By repeating steps S20 to S24, the test apparatus 10 can heat the test piece under the set conditions.

[0034] If the test apparatus 10 determines that heating has ended (Yes in step S24), it takes out the test piece 12 from the heating furnace 16. The test apparatus 10, for example, moves the test piece 12 to the position shown in Figure 2 (step S26).

[0035] Next, the test apparatus 10 evaluates the test specimen (step S28). For example, it measures the state of rupture of the test tube 22 of the test specimen 12. Also, it measures the state of scattering of the granular pellets 32 inside the test specimen 12. The measurement can be performed, for example, by analyzing an image captured by an imaging device. The test apparatus 10 measures the state of adhesion of the granular pellets 32 to the simulated fuel rod 24 with the granular pellets 32 attached and to the surface of the bottom plate of the frame 20. The test apparatus 10 outputs the evaluation result with the evaluation device 19. The evaluation device 19, for example, displays the image 110 shown in FIG. 7. The image 110 shows the arrangement position 122 of the test tube 22 in the region where the cells (test tube 22, simulated fuel rod 24) of the test specimen are arranged. Also, the image 110 displays an arrow indication 124 in the direction in which the test tube 22 ruptured. Further, the image 110 marks 140 the positions where the granular pellets 32 discharged from the test tube 22 were detected. Note that the image acquired as the evaluation result may be displayed.

[0036] The test apparatus 10 can control the heating state of the test specimen 12 by moving the test specimen 12 relative to the heating furnace 16 with the moving device 14, and can suitably test the heating state at the time of LOCA occurrence. That is, the heating state can be controlled with higher responsiveness than the temperature control of the heat source 62 of the heating furnace 16, and the heating state at the time of LOCA occurrence where a rapid temperature rise is assumed can be suitably tested. Also, since it can be heated by the heating furnace 16, the test can be performed without performing processes such as filling the gas that expands inside the test tube 22 to make the coating tube 30 easier to rupture. In the present embodiment, the test specimen 12 is moved relative to the heating furnace 16 with the moving device 14, but the heating furnace 16 and the test specimen 12 may be relatively moved, or the heating furnace 16 may be moved with the moving device 14. Also, with the moving device 14, both the moving body 12 and the heating furnace 16 may be moved.

[0037] FIG. 8 is an explanatory diagram showing an example of the relationship between the movement and heating of the test specimen. In FIG. 8, the horizontal axis represents the stage position and the vertical axis represents the temperature of the coating tube. The line segment 180 and the line segment 182 shown in FIG. 8 show the relationship between the stage position and the temperature of the coating tube when the rising speed of the stage is different. The line segment 182 has a faster rising speed than the line segment 180, that is, the line segment 182 reaches the heating region 66 earlier. As shown in FIG. 8, by controlling the speed at which the test specimen is moved by the moving device 14, the temperature rise of the test target tube can be made at different speeds. Also, by increasing the moving speed, that is, shortening the time until reaching the heating region 66, the temperature of the test specimen can be rapidly increased.

[0038] The test device 10 can simulate a test when a fuel rod is damaged in a fuel assembly by configuring the test specimen 12 to have a structure in which the simulated fuel rods 24 are arranged around the test target tube 22.

[0039] (Effect) The test device according to the first aspect of the present disclosure is a test device for testing the scattering state of fuel scattered from a fuel rod of a fuel assembly, including a test target tube filled with particles corresponding to fuel pellets, and a simulated fuel rod arranged around the test target tube to simulate the fuel assembly, a test specimen including the simulated fuel rod, a moving device for moving the test specimen, a heating furnace arranged in the moving range of the test specimen, and a control device for controlling the movement of the moving device and controlling the heating state of the test specimen by the heating furnace. According to the present disclosure, by controlling the position of the test specimen with respect to the heating furnace by the moving device, the heating of the test specimen can be controlled by the movement of the moving device. Thereby, the temperature change during LOCA can be suitably reproduced. Also, by making the test specimen a test target tube filled with particles corresponding to fuel pellets and a simulated fuel rod arranged around the test target tube to simulate the fuel assembly, the scattering (scattering distance, deposition amount) of fuel in the fuel assembly can be evaluated.

[0040] The test apparatus according to the second aspect of the present disclosure is the test apparatus according to the first aspect, wherein the control device controls the movement of the moving device, simulates the heating state of the fuel assembly before the occurrence of LOCA, heats the test piece, and ruptures the test target tube. According to the present disclosure, it is possible to suitably test the scattering of fuel due to the rupture of the fuel cladding tube during LOCA.

[0041] The test apparatus according to the third aspect of the present disclosure is the test apparatus according to the first or second aspect, and has a temperature sensor disposed on the test piece that simulates the fuel assembly. The control device controls the heating state of the test piece based on the detection result of the temperature sensor. According to the present disclosure, based on the temperature of the test piece, the position can be adjusted and the heating can be controlled. Thereby, the test piece can be heated more appropriately, and a test closer to a desired test can be performed.

[0042] The test apparatus according to the fourth aspect of the present disclosure is the test apparatus according to any one of the first to third aspects, wherein the heating furnace is an electric furnace. According to the present disclosure, it is easy to control heating. Further, by not controlling the temperature in the heating furnace, even when an electric furnace is used, the test piece can be appropriately heated.

[0043] The test apparatus according to the fifth aspect of the present disclosure is the test apparatus according to any one of the first to fourth aspects, wherein the heating furnace has a core tube that extends in the vertical direction and is open at the bottom. According to the present disclosure, by using the core tube, the temperature in the heating region can be appropriately managed.

[0044] The test apparatus according to the sixth aspect of the present disclosure is the test apparatus according to any one of the first to fifth aspects, wherein the test piece has a scattering guard that covers the periphery of the space in which the test target tube and the simulated fuel rod are disposed. According to the present disclosure, by providing the scattering guard, it is possible to suppress the scattering of granular pellets outside the test piece. Further, the environment inside the test piece 12 can be made uniform.

[0045] The test apparatus according to the seventh aspect of the present disclosure is the test apparatus according to any one of the first aspect to the sixth aspect, wherein the moving device has a heat insulating material disposed at at least one of both ends in the moving direction of the test body. According to the present disclosure, by disposing the heat insulating material, it is possible to suppress a decrease in the temperature of the heating region, and the test body can be efficiently heated. In addition, the heat retention property is improved, and the energy required for heating can be reduced.

[0046] The test method according to the eighth aspect of the present disclosure is a test method for testing the scattering state of fuel scattered from fuel rods of a fuel assembly, including a test target tube filled with particles corresponding to fuel pellets, and a simulated fuel rod disposed around the test target tube to simulate the fuel assembly. A step of fixing the test body including the test target tube and the simulated fuel rod to a moving device, and a step of moving the test body with the moving device relative to a heating furnace, controlling the heating of the test body by the heating furnace, and rupturing the test target tube. According to the present disclosure, by controlling the position of the test body relative to the heating furnace with the moving device, the heating of the test body can be controlled by the movement of the moving device. Thereby, the temperature change at the time of LOCA can be suitably reproduced. Further, by using a test target tube filled with particles corresponding to fuel pellets and a simulated fuel rod disposed around the test target tube to simulate the fuel assembly as the test body, the scattering of fuel in the fuel assembly can be evaluated.

[0047] The test method according to the ninth aspect of the present disclosure is the test method according to the eighth aspect, further including a step of measuring the scattering state of the particles corresponding to the fuel pellets in the test body. According to the present disclosure, the scattering of fuel can be appropriately evaluated.

[0048] As described above, the embodiments of the present disclosure have been described, but the embodiments are not limited by the contents of these embodiments. Further, the above-described components include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those within the so-called equivalent range. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or changes of the components can be made without departing from the gist of the above-described embodiments.

Description of Symbols

[0049] 10 Test apparatus 12 Specimen 14 Moving device 16 Heating furnace 18 Control device 19 Evaluation device 20 Frame 22 Test target tube 24 Simulated fuel rod 26 Scattering guard 28 Temperature sensor 30 Cladding tube 32 Granular pellet 34 Solid body 50 Stage 52 Drive shaft 54 Drive source 60 Housing 62 Heat source 64 Core tube 66 Heating region 70, 72 Heat insulation material

Claims

1. A test apparatus for testing the scattering state of fuel scattered from fuel rods of a fuel assembly, comprising: a test body including a test target tube filled with particles corresponding to fuel pellets, and simulated fuel rods arranged around the test target tube to simulate the fuel assembly; a moving device for moving the test body; a heating furnace arranged in the moving range of the test body; a control device for controlling the movement of the moving device and controlling the heating state of the test body by the heating furnace.

2. The test apparatus according to claim 1, wherein the control device controls the movement of the moving device, heats the test body by simulating the heating state of the fuel assembly during the occurrence of a LOCA, and ruptures the test target tube.

3. having a temperature sensor arranged in the test body simulating the fuel assembly, The test apparatus according to claim 1, wherein the control device controls the heating state of the test body based on the detection result of the temperature sensor.

4. The test apparatus according to claim 1, wherein the heating furnace is an electric furnace.

5. The test apparatus according to claim 1, wherein the heating furnace has a core tube extending in the vertical direction and open at the bottom.

6. The test apparatus according to claim 1, wherein the test body has a scattering guard covering the periphery of the space where the test target tube and the simulated fuel rods are arranged.

7. The test apparatus according to claim 1, wherein the moving device has a heat insulating material arranged at at least one of both ends in the moving direction of the test body.

8. A test method for testing the scattering state of fuel scattered from fuel rods of a fuel assembly, comprising: fixing a test body including a test target tube filled with particles corresponding to fuel pellets and simulated fuel rods arranged around the test target tube to simulate the fuel assembly to a moving device; moving the test body relative to a heating furnace by the moving device, controlling the heating of the test body by the heating furnace, and rupturing the test target tube.

9. The test method according to claim 8, further comprising measuring the scattering state of the particles corresponding to the fuel pellets in the test body.

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