A method for supervising the aging of a sample of a spent fuel storage rack of a nuclear power plant

Abstract

The application belongs to the technical field of nuclear power plant aging management, and aims to solve the problem of occupying the storage cell of the spent fuel storage rack by the existing sample supervision method. The application discloses a spent fuel storage rack aging sample supervision method. Adjacent storage cells in the spent fuel storage rack are selected, the spent fuel storage rack side plates between the adjacent storage cells are removed, the aging sample piece is installed on the aging sample device, the aging sample device replaces the removed spent fuel storage rack side plates to absorb neutrons, the aging sample device is regularly taken out from the spent fuel storage pool, the sample piece is taken off for sampling detection, the aging state of the spent fuel storage rack material is evaluated, the new sample piece is installed on the aging sample device, and the aging sample device is reinstalled to the aging sample device installation position. The application can effectively supervise the aging state of the spent fuel storage rack without occupying the storage cell in the spent fuel storage rack.

Description

Technical Field

[0001] This application belongs to the field of nuclear power plant aging management technology, and in particular relates to a method for monitoring the aging of spent fuel storage racks in nuclear power plants. Background Technology

[0002] The spent fuel storage racks in nuclear power plants are made of boron-containing stainless steel or boron-aluminum alloy to absorb neutrons and control the reactivity of spent fuel in the storage pool. 10 Boron is a major neutron-absorbing element. With the long-term storage of spent fuel in spent fuel storage racks, the material within the spent fuel storage racks... 10 The boron content gradually decreases, and the neutron absorption capacity of the spent fuel storage rack material also decreases accordingly. Therefore, in order to ensure that spent fuel can be maintained in a subcritical state throughout the entire lifespan of the nuclear power plant (including extended operation), it is necessary to carry out aging status monitoring of the spent fuel storage rack material to ensure the safe storage of spent fuel in the nuclear power plant.

[0003] Currently, the main method for aging and sampling spent fuel storage racks in domestic nuclear power plants involves placing an aging sampling device in the storage compartment of the spent fuel storage rack and periodically taking samples to conduct tests to monitor the aging status of the spent fuel storage rack materials. Because the size design of the aging sampling device is basically the same as that of the fuel assembly, when the aging sampling device is placed inside the spent fuel storage rack, it occupies one storage compartment of the rack, making it impossible to store spent fuel in that compartment. Summary of the Invention

[0004] The purpose of this application is to provide a method for monitoring the aging of spent fuel storage racks in nuclear power plants by taking samples, which solves the problem of existing sampling and monitoring methods occupying the storage compartments of spent fuel storage racks, and enables effective monitoring of the aging status of spent fuel storage racks without occupying the storage compartments within the racks.

[0005] To achieve the above objectives, this application provides the following technical solution: A method for monitoring the aging of spent fuel storage racks in nuclear power plants includes the following steps: S1: Select two adjacent storage compartments in the spent fuel storage rack, remove the side plate of the spent fuel storage rack between the two adjacent storage compartments to form the installation position of the aging sample retention device; S2: Install the aging sample piece onto the aging sample retention device; S3: Install the aging sample retention device with the sample installed to the aging sample retention device installation position, so that the aging sample retention device replaces the removed spent fuel storage rack side plate to absorb neutrons. S4: In accordance with the monitoring plan, the aging sampling device shall be removed from the spent fuel storage pool periodically, and samples shall be taken from the aging sampling device for sampling and testing to evaluate the aging status of the spent fuel storage grid material. S5: After sampling and testing are completed, install the new sample onto the aging retention device, and then reinstall the aging retention device to its original position.

[0006] As one feasible approach, the aging sample retention device is installed between two adjacent storage chambers.

[0007] As an feasible approach, the overall dimensions of the aging sample retention device are consistent with the dimensions of the side panels of the removed spent fuel storage rack.

[0008] As an feasible approach, the aging sample retention device is provided with concave slot structures on both sides of the installation position for fixing the aging sample retention device.

[0009] As an feasible approach, the aging sample retention device includes a support plate with a sample storage slot on the support plate. The side wall of the sample storage slot has a slot, through which the sample is embedded and fixed on the support plate.

[0010] As one feasible approach, the sample storage slot is a rectangular through hole opened on the surface of the support plate body. The length direction of the sample storage slot is consistent with the long axis direction of the support plate, and the slots are set on both sides of the length direction of the sample storage slot.

[0011] As an feasible approach, there are six or more sample storage slots.

[0012] As one feasible approach, the top of the support plate is provided with a circular hole for hoisting the aging sample retention device.

[0013] As an feasible approach, both the aging sample retention device and the sample are made of the same material as the spent fuel storage rack.

[0014] As one feasible approach, the material is boron aluminum plate or boron stainless steel plate.

[0015] As one feasible approach, the sample is a rectangular plate-like structure, and the size of the sample is smaller than the size of the sample storage slot.

[0016] As an feasible approach, the storage compartment is a hollow cavity with a square cross-section, and the size of the storage compartment is larger than that of the spent fuel assembly. The top of the storage compartment is an open design.

[0017] As one feasible approach, in S3, the aging sample retention device with the sample installed is placed in the aging sample retention device installation position directly above the spent fuel storage rack.

[0018] As an feasible approach, in S4, the aging sampling device is lifted out of the spent fuel storage pool through the round hole on the aging sampling device, and sampling is carried out in the sampling sequence.

[0019] As an feasible approach, in S4, sampling and testing includes transporting the removed samples to a laboratory for aging testing and analysis.

[0020] As an feasible approach, in S5, after installing the new sample onto the aging sample retention device, the aging sample retention device is returned to its installation position, so that the new sample replaces the removed sample in absorbing neutrons.

[0021] Compared with existing technologies, the method for monitoring the aging of spent fuel storage racks in nuclear power plants provided in this application has the following advantages: This application can be used to monitor the aging status of spent fuel storage racks in nuclear power plants. By setting up aging monitoring samples inside the spent fuel storage racks in nuclear power plants and taking samples periodically for testing, the aging status of the spent fuel storage racks can be monitored to ensure the safe storage of spent fuel.

[0022] This application achieves the goal of not occupying the storage compartments inside the spent fuel storage racks, while effectively monitoring the aging status of the spent fuel storage racks, filling a gap in this technical field in China.

[0023] This application does not require occupying the storage compartment within the spent fuel storage rack, overcoming the defect of the spent fuel storage rack aging sample retention device occupying the storage compartment within the spent fuel storage rack, and does not affect the normal storage of spent fuel.

[0024] Furthermore, this application replaces the side plate of the spent fuel storage grid with an aging sample retention device, which, as part of the spent fuel storage grid, can directly contact the spent fuel assembly and more effectively represent the material state of the spent fuel grid.

[0025] Furthermore, the spent fuel storage grid aging sampling device of this application has a simple structure, few parts, and no easily loosened small parts, which effectively reduces the risk of foreign objects in the spent fuel storage pool.

[0026] Furthermore, the installation and sampling of the spent fuel storage rack aging sampling device of this application are simple, do not require the use of equipment such as new fuel lifts, and have low on-site safety and foreign object risks. Attached Figure Description

[0027] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the technical description will be briefly introduced below.

[0028] Figure 1 A flowchart illustrating the method for monitoring the aging of spent fuel storage racks in nuclear power plants, as provided in this application; Figure 2 Top view of the spent fuel storage rack provided in this application; Figure 3 A front view of the spent fuel storage rack provided in this application; Figure 4 A front view of the aging sample retention device provided in this application; Figure 5 A side view of the chemical sample retention device provided in this application; Figure 6 A cross-sectional view of the sample retention device provided for this application; Figure 7 A schematic diagram of the sample provided in this application.

[0029] Explanation of reference numerals in the attached figures: 1. Storage chamber; 2. Installation location of aging sample retention device; 3. Side plate of spent fuel storage rack; 4. Round hole; 5. Support plate; 6. Sample storage slot; 7. Card slot; 8. Sample. Detailed Implementation

[0030] The following detailed description provides further details on specific implementation methods.

[0031] like Figures 1 to 7 As shown, this application provides a method for monitoring the aging of spent fuel storage racks in nuclear power plants, comprising the following steps: S1: Select two adjacent storage compartments 1 in the spent fuel storage rack, remove the side plate 3 of the spent fuel storage rack between the two adjacent storage compartments to form the installation position 2 of the aging sample retention device; S2: Install the aging sample 8 onto the designed aging sample retention device; S3: Install the aging sample retention device with the sample installed to the aging sample retention device installation position 2, so that the aging sample retention device replaces the removed spent fuel storage rack side plate to absorb neutrons. S4: In accordance with the monitoring plan, the aging sampling device shall be removed from the spent fuel storage pool periodically, and samples shall be taken from the aging sampling device for sampling and testing to evaluate the aging status of the spent fuel storage grid material. S5: After sampling and testing are completed, install the new sample onto the aging sample retention device, and then reinstall the aging sample retention device at the aging sample retention device installation position 2.

[0032] In this application, a single spent fuel storage rack is composed of multiple storage chambers 1 spliced ​​together in a regular matrix. Each storage chamber 1 has a spent fuel storage rack side plate 3 on all four sides. Each storage chamber 1 is a hollow cavity with a square cross-section, and its size is slightly larger than that of the spent fuel assembly. The storage chamber 1 has a bottom plate at the bottom and an open design at the top, which allows the spent fuel assembly to be placed in from the top opening.

[0033] The aging monitoring device is installed at position 2 between two adjacent storage compartments 1. The design removes the spent fuel storage rack side plate 3 between these two adjacent storage compartments 1, and a concave slot structure is provided on both sides of the original spent fuel storage rack side plate 3 along its length to fix the aging monitoring device.

[0034] The aging sample retention device includes a support plate 5, a sample storage slot 6 is provided on the support plate 5, and a slot 7 is provided on the side wall of the sample storage slot 6. The sample 8 is embedded and fixed on the support plate 5 through the slot 7.

[0035] Specifically, the support plate 5 has 6 or more rectangular through holes on its surface. The through holes are regular rectangles of equal width and length, with the hole walls perpendicular to the surface of the support plate 5. The length direction of the holes is consistent with the long axis direction of the support plate 5. The rectangular through holes are sample storage slots 6. The sample storage slots 6 have slots 7 on both sides along their length. The slots 7 are concave. The aging monitoring sample 8 can be inserted into and fixed on the support plate 5 from the top position of the sample storage slot 6.

[0036] The aging sample retention device and sample 8 are both made of the same material as the spent fuel storage rack, which is boron aluminum plate or boron stainless steel plate.

[0037] Sample 8 is made of boron aluminum plate or boron stainless steel plate, and has a rectangular plate structure, with a size slightly smaller than sample storage slot 6.

[0038] Storage chamber 1 is a hollow cavity with a square cross-section. The size of the storage chamber is larger than that of the spent fuel assembly, and the top of the storage chamber is an open design.

[0039] In S3, the aging sample retention device with the sample installed is placed from directly above the spent fuel storage rack into aging sample retention device installation position 2.

[0040] In S4, the aging sampling device is lifted out of the water surface from the spent fuel storage pool through the round hole 4 on the aging sampling device, and sampling is carried out in the sampling sequence.

[0041] In S4, sampling and testing includes transporting the removed samples to the laboratory for aging testing and analysis.

[0042] In S5, after the new sample is installed on the aging sample retention device, the aging sample retention device is returned to the aging sample retention device installation position 2, so that the new sample replaces the sample that was taken away to absorb neutrons.

[0043] For example, this method is used to monitor the aging of spent fuel storage rack materials during the design, manufacturing, installation, and operation phases of nuclear power plants, including: (1) When designing and manufacturing spent fuel storage racks, reserve an aging sample retention device in the spent fuel storage racks for monitoring the aging of spent fuel storage rack materials.

[0044] (2) During the installation phase, six or more aging sample pieces 8 are installed into the sample storage slot 6 of the aging sample retention device. The sample pieces 8 are embedded in the sample storage slot 6 on the support plate 5 through the slot 7.

[0045] (3) Use the factory crane to place the aging sample retention device containing sample 8 from directly above the spent fuel storage grid into the aging sample retention device installation position 2, and then lift the spent fuel storage grid into the spent fuel storage pool.

[0046] (4) During the operation phase, according to the aging sampling plan, the plant crane is used to lift the aging sampling device out of the spent fuel storage pool through the round hole 4 of the aging sampling device, and the sampling work is carried out in accordance with the sampling sequence.

[0047] (5) After sampling is completed, the new sample 8 is placed back into the original sampling location sample storage slot 6 to replace the sample that was taken away and continue to absorb neutrons. Then the aging sample retention device is placed back into the aging sample retention device installation position 2.

[0048] (6) Transport the aged sample pieces to the laboratory, carry out aging testing and analysis, and evaluate the aging status of the spent fuel storage rack material.

[0049] When designing and manufacturing spent fuel storage racks, two adjacent storage compartments 1 are selected. The side panel 3 of the spent fuel storage rack between these two adjacent storage compartments 1 is removed, reserving a location 2 for installing an aging monitoring device. This device is used to monitor the aging of the spent fuel storage rack material. The aging sampling device is installed at the original location of the side panel of the spent fuel storage rack, without affecting the subsequent storage of spent fuel in the two adjacent storage compartments.

[0050] The aging sample 8 is installed into the sample storage slot 6 of the aging sample retention device. The sample 8 is embedded into the sample storage slot 6 on the support plate 5 through the slot 7 of the sample storage slot 6 to prevent the sample from falling off and to facilitate subsequent periodic sampling of the sample.

[0051] An aging sample retention device containing sample 8 is placed at aging sample retention device installation position 2 directly above the spent fuel storage grid. It is used to replace the side plate 3 of the spent fuel storage grid to absorb neutrons and monitor the aging status of the spent fuel storage grid material.

[0052] According to the monitoring plan, the aging sample retention device is periodically removed from the spent fuel storage pool for sampling tests to evaluate the aging status of the spent fuel storage grid material. After sampling, a new sample is placed back into the pool to replace the removed sample, continuing to absorb neutrons without affecting the subsequent function of the spent fuel storage grid.

[0053] It should be noted that the above embodiments are only one preferred embodiment of the present invention, and other embodiments are also possible. For example, the number of sample storage slots is not limited to 6, and can be increased or decreased according to actual monitoring needs; the installation and sampling operation of the aging sample retention device are not limited to using a factory crane, and other equipment with equivalent lifting functions can also be used. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

[0054] The above description is only a specific embodiment of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application.

Claims

1. A method for monitoring the aging of spent fuel storage racks in nuclear power plants, characterized in that, include: S1: Select an adjacent storage cell in the spent fuel storage rack, remove the side plate of the spent fuel storage rack between the adjacent storage cells to form the installation position of the aging sample retention device; S2: Install the aging sample piece onto the aging sample retention device; S3: Install the aging sample retention device with the sample installed to the aging sample retention device installation position, so that the aging sample retention device replaces the removed spent fuel storage rack side plate to absorb neutrons. S4: Periodically remove the aging sampling device from the spent fuel storage pool, take samples from the aging sampling device for sampling and testing, and evaluate the aging status of the spent fuel storage grid material; S5: After sampling and testing are completed, install the new sample onto the aging retention device, and then reinstall the aging retention device to its original position.

2. The method for monitoring the aging of spent fuel storage racks in nuclear power plants according to claim 1, characterized in that, The aging sample retention device is installed between two adjacent storage chambers.

3. The method for monitoring the aging of spent fuel storage racks in nuclear power plants according to claim 1, characterized in that, The aging sample retention device has concave slot-type structures on both sides of the installation position.

4. The method for monitoring the aging of spent fuel storage racks in nuclear power plants according to claim 1, characterized in that, The aging sample retention device has a support plate with a sample storage slot on the support plate. The side wall of the sample storage slot has a slot, through which the sample is embedded and fixed on the support plate.

5. The method for monitoring the aging of spent fuel storage racks in nuclear power plants according to claim 1, characterized in that, The aging sample retention device and the sample pieces are made of the same material as the spent fuel storage rack.

6. The method for monitoring the aging of spent fuel storage racks in nuclear power plants according to claim 1, characterized in that, The sample is a rectangular plate structure, and the size of the sample is smaller than the size of the sample storage slot.

7. The method for monitoring the aging of spent fuel storage racks in nuclear power plants according to claim 1, characterized in that, The storage compartment is a hollow cavity with a square cross-section, and its size is larger than that of the spent fuel assembly.

8. The method for monitoring the aging of spent fuel storage racks in nuclear power plants according to claim 1, characterized in that, In S3, the aging sample retention device with the sample installed is placed from above the spent fuel storage rack into the aging sample retention device installation position.

9. The method for monitoring the aging of spent fuel storage racks in nuclear power plants according to claim 1, characterized in that, In S4, the aging sampling device is lifted out of the water from the spent fuel storage pool and samples are taken in the sampling sequence.

10. The method for monitoring the aging of spent fuel storage racks in nuclear power plants according to claim 1, characterized in that, In S5, after the new sample is installed on the aging sample retention device, the aging sample retention device is returned to its installation position, so that the new sample replaces the sample that was taken away to absorb neutrons.

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