CN118230991A - Fuel rod for transition circulation of pressurized water reactor nuclear power station - Google Patents
Fuel rod for transition circulation of pressurized water reactor nuclear power station Download PDFInfo
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- CN118230991A CN118230991A CN202211655206.9A CN202211655206A CN118230991A CN 118230991 A CN118230991 A CN 118230991A CN 202211655206 A CN202211655206 A CN 202211655206A CN 118230991 A CN118230991 A CN 118230991A
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- Prior art keywords
- fuel
- uranium
- fuel rod
- pressurized water
- nuclear power
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- 239000000446 fuel Substances 0.000 title claims abstract description 112
- 230000007704 transition Effects 0.000 title claims abstract description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 19
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 claims description 53
- 239000008188 pellet Substances 0.000 claims description 50
- 229910052770 Uranium Inorganic materials 0.000 claims description 32
- 238000005253 cladding Methods 0.000 claims description 15
- 238000009434 installation Methods 0.000 claims description 12
- 239000000919 ceramic Substances 0.000 claims description 10
- OOAWCECZEHPMBX-UHFFFAOYSA-N oxygen(2-);uranium(4+) Chemical compound [O-2].[O-2].[U+4] OOAWCECZEHPMBX-UHFFFAOYSA-N 0.000 claims description 4
- 239000000843 powder Substances 0.000 claims description 4
- 238000005245 sintering Methods 0.000 claims description 4
- FCTBKIHDJGHPPO-UHFFFAOYSA-N uranium dioxide Inorganic materials O=[U]=O FCTBKIHDJGHPPO-UHFFFAOYSA-N 0.000 claims description 4
- 230000000712 assembly Effects 0.000 abstract description 15
- 238000000429 assembly Methods 0.000 abstract description 15
- 239000003758 nuclear fuel Substances 0.000 abstract description 10
- 230000004992 fission Effects 0.000 description 6
- 230000006872 improvement Effects 0.000 description 4
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
Abstract
The invention belongs to the technical field of nuclear fuel assemblies, and particularly relates to a fuel rod for transition circulation of a pressurized water reactor nuclear power station. The top end of the fuel rod is provided with an upper end plug, and the bottom end of the fuel rod is provided with a lower end plug. The reactor core power distribution flattening device can flatten the reactor core power distribution when the reactor is loaded with fuel assemblies with different active area lengths, and ensure the safe and stable operation of the mixed reactor core.
Description
Technical Field
The invention belongs to the technical field of nuclear fuel assemblies, and particularly relates to a fuel rod for transition circulation of a pressurized water reactor nuclear power station.
Background
The nuclear fuel is an energy source of a nuclear power plant, and the nuclear fuel of a pressurized water reactor nuclear power plant is stored in a fuel assembly, which is composed of a plurality of fuel rods. The fuel rods are loaded with fuel pellets of a certain enrichment in which a fission reaction takes place to release energy. Therefore, the power generation capacity of a nuclear power plant is mainly dependent on the load of nuclear fuel. In order to further improve the economic benefit of the operation of the nuclear power station and increase the generated energy, technical improvement measures such as power improvement or period of refueling can be adopted, and all the technical improvement measures need to increase the nuclear fuel loading capacity in the reactor. One way to increase the loading of nuclear fuel is to directly increase the loading of UO 2 in the fuel rod, i.e., the height of the region of the fuel rod where UO 2 is loaded (commonly referred to as the active region) without a change in the diameter of the fuel rod.
Because the pressurized water reactor nuclear power station adopts a split-region and batch refueling mode to load the nuclear fuel, namely, a batch of nuclear fuel assemblies can use 2-4 fuel cycles, and each refueling only needs to discharge the fuel assemblies with fuel burnup approaching the limit value. Since some of the technical improvements require a direct increase in UO 2 loading, there is a transition from loading low UO 2 loading to high UO 2 loading, i.e., growth from short to long active areas, and thus, a hybrid core will appear that is loaded with fuel assemblies of different active area lengths simultaneously.
Abnormal distribution of axial power of the reactor core occurs due to inconsistent lengths of the active areas, so that safe and stable operation of the nuclear power station is affected. The patent of the invention provides a design of a fuel rod for transition circulation of a pressurized water reactor nuclear power station, which flattens the power distribution of a reactor core when fuel assemblies with different active area lengths are loaded in the reactor, and ensures the safe and stable operation of a mixed reactor core.
Disclosure of Invention
Object of the Invention
Aiming at the defects of the prior art, the invention provides a fuel rod for transition circulation of a pressurized water reactor nuclear power station, which can flatten the power distribution of a reactor core when the reactor is loaded with fuel assemblies with different active area lengths, and ensure the safe and stable operation of a mixed reactor core.
The technical scheme of the invention is as follows:
the fuel rod for the transition cycle of the pressurized water reactor nuclear power station comprises an upper end plug, a fuel rod cladding, a fuel pellet installation area, a spring and a lower end plug, wherein the fuel pellet installation area is arranged in the fuel rod cladding, and the spring is arranged above the fuel pellet installation area; the top end of the fuel rod cladding is provided with an upper end plug, and the bottom end of the fuel rod cladding is provided with a lower end plug.
Two uranium-depleted regions and one uranium-enriched region are arranged in the fuel pellet installation region.
The enriched uranium region is arranged between the two depleted uranium regions.
And the enriched uranium zone is internally filled with enriched uranium fuel pellets, and a short active zone fuel assembly is arranged in the enriched uranium zone.
And the depleted uranium zone is internally provided with depleted uranium fuel pellets with low enrichment degree, and a long active zone fuel assembly is arranged in the depleted uranium zone.
The depleted uranium fuel pellet is a cylindrical ceramic pellet which is formed by sintering uranium dioxide (UO 2) powder, and a central hole is formed in the middle of the ceramic pellet; the depleted uranium fuel pellet U 235 adopts natural uranium, and the enrichment degree is 0.711%.
The spring holds the fuel pellet in the fuel pellet mounting zone in a specified position.
The invention has the beneficial effects that:
1. the axial power distribution of the transition circulating reactor core is improved by arranging a uranium-depleted zone on the fuel rod;
2. By loading the fuel assembly consisting of the designed fuel rods, the reactor core is stably transited from a short active area to a long active area, and the safe and stable operation of the reactor is ensured;
Drawings
FIG. 1 is a schematic diagram of a fuel rod structure for transition cycle of a pressurized water reactor nuclear power plant;
FIG. 2 is an elevation view of a uranium depleted fuel pellet according to the present invention;
FIG. 3 is a top view of a uranium depleted fuel pellet according to the present invention;
Wherein: 1-an upper end plug; 2-fuel rod cladding; 3-a spring; 4-uranium enrichment area; 5-a lower end plug; a zone of depleted uranium; 7-ceramic pellets; 8-a central hole.
Detailed Description
The following describes a fuel rod for transition cycle of pressurized water reactor nuclear power plant in detail with reference to the accompanying drawings and examples.
The fuel rod for transition circulation of the pressurized water reactor nuclear power station comprises an upper end plug 1, a fuel rod cladding 2, a fuel pellet installation area, a spring 3 and a lower end plug 5, wherein the fuel pellet installation area is arranged in the fuel rod cladding 2, and the spring 3 is arranged above the fuel pellet installation area; the top end of the fuel rod cladding 2 is provided with an upper end plug 1, and the bottom end of the fuel pellet cladding 2 is provided with a lower end plug 5.
Two uranium-depleted regions 6 and one uranium-enriched region 4 are arranged in the fuel pellet installation region.
The enriched uranium zone 4 is arranged between two depleted uranium zones 6.
And the enriched uranium zone 4 is internally provided with enriched uranium fuel pellets, and a short active zone fuel assembly is arranged in the enriched uranium zone 4.
The depleted uranium zone 6 is loaded with depleted uranium fuel pellets with low enrichment, and a long active zone fuel assembly is arranged in the depleted uranium zone 6.
The depleted uranium fuel pellet is a cylindrical ceramic pellet 7 formed by sintering uranium dioxide (UO 2) powder, and a central hole 8 is formed in the middle of the ceramic pellet 7; the depleted uranium fuel pellet U 235 adopts natural uranium, and the enrichment degree is about 0.711%.
The spring 3 holds the fuel pellet in the fuel pellet mounting area in a specified position.
Examples
As shown in fig. 1, the fuel rod structure for transition cycle in this embodiment has a generally rod-like structure, and includes:
an upper end plug 1 engaged with the jig during manufacturing for pushing in/out the fuel rod;
a fuel rod cladding 2 for containing fuel pellets, confining fission products generated by a nuclear fission reaction within the cladding;
a spring 3 for holding the fuel pellet at a specified position by the pressure of the spring 3;
The enriched uranium zone 4 is used for loading enriched uranium fuel pellets, and the enrichment degree of U 235 of the enriched uranium zone 4 is higher;
a lower end plug 5 for fixing the fuel rods to prevent the fuel rods from moving under the impact of the core coolant;
A depleted uranium zone 6 for loading depleted uranium fuel pellets; uranium depleted fuel pellets may be arranged at different elevations of the fuel rods depending on the arrangement of uranium enriched fuel pellets in the short active region fuel rods.
In the embodiment, the fuel core block structure of the uranium-depleted zone is shown in fig. 2, and is generally a cylindrical ceramic core block 1, wherein the ceramic core block 1 is formed by sintering uranium dioxide (UO 2) powder; the ceramic core block 1 is provided with a central hole 2, and the central hole 2 is used for improving heat transfer and avoiding overheating of the center of the core block.
The local fission reaction rate (i.e., local power) of the reactor core is affected by the enrichment of the fissile nuclides (e.g., U 235、Pu239, etc.) in the fuel pellets in the fuel rods at that location, the higher the enrichment, the higher the local power, and generally the greater the enrichment of U 235 in the fuel pellets. Under the working condition of a mixed reactor core simultaneously loaded with fuel assemblies with different active area lengths, in an active area length extension area, the long active area fuel assemblies generate certain fission reaction due to the nuclear fuel at the height, and the short active area fuel assemblies do not generate fission reaction at the height, so that the power distribution distortion in the axial direction of the reactor core is caused, and the flattening and control of the power distribution of the reactor core are not facilitated.
To improve the axial power distribution of the hybrid core, the present invention provides a uranium-depleted region in the extension of the fuel assembly active region, i.e., where fuel pellets with a low enrichment (typically natural uranium is used, with a U 235 enrichment of about 0.711%) are loaded. At the beginning of the transition cycle, by loading the fuel assemblies with the depleted uranium zone, a mixed reactor core composed of the fuel assemblies with the short active zone and the fuel assemblies with the long active zone with the depleted uranium zone is formed, and the fuel assemblies with the long active zone can not form power peaks in the extension zone due to low enrichment degree of the depleted uranium zone, so that the distortion degree of axial power distribution of the reactor core is reduced.
The embodiments of the present invention have been described in detail, but the present invention is not limited to the above examples, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present invention.
Claims (7)
1. The utility model provides a pressurized water reactor nuclear power station transition is fuel rod for circulation which characterized in that: the fuel rod comprises an upper end plug (1), a fuel rod cladding (2), a fuel pellet installation area, a spring (3) and a lower end plug (5), wherein the fuel pellet installation area is arranged inside the fuel rod cladding (2), and the spring (3) is arranged above the fuel pellet installation area; an upper end plug (1) is arranged at the top end of the fuel rod cladding (2), and a lower end plug (5) is arranged at the bottom end of the fuel rod cladding (2).
2. The fuel rod for transition cycle of pressurized water reactor nuclear power plant according to claim 1, wherein: two uranium-depleted regions (6) and one uranium-enriched region (4) are arranged in the fuel pellet installation region.
3. The fuel rod for transition cycle of pressurized water reactor nuclear power plant according to claim 2, wherein: the enriched uranium zone (4) is arranged between the two depleted uranium zones (6).
4. A pressurized water reactor nuclear power plant transition cycle fuel rod as defined in claim 3, wherein: the enriched uranium zone (4) is loaded with enriched uranium fuel pellets.
5. A pressurized water reactor nuclear power plant transition cycle fuel rod as defined in claim 3, wherein: the depleted uranium zone (6) is loaded with depleted uranium fuel pellets with a low enrichment.
6. The fuel rod for transition cycle of pressurized water reactor nuclear power plant according to claim 1, wherein: the depleted uranium fuel pellet is a cylindrical ceramic pellet (7) formed by sintering uranium dioxide (UO 2) powder, and a central hole (8) is formed in the middle of the ceramic pellet (7); the enrichment degree of the uranium-depleted fuel pellets U 235 is 0.711%.
7. The fuel rod for transition cycle of pressurized water reactor nuclear power plant according to claim 1, wherein: the springs (3) hold the fuel pellets in the fuel pellet mounting area in a specified position.
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN118230991A true CN118230991A (en) | 2024-06-21 |
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