A method of layered processing of plate-shaped dispersion fuel elements

Abstract

The application discloses a layered processing method for plate-shaped dispersion fuel elements and belongs to the technical field of nuclear reactor physics analysis. The method is aimed at solving the power distortion problem of the existing reactivity equivalent physical conversion method used for plate-shaped fuel elements. The method first calculates the initial effective multiplication factor of a double non-uniform system containing poison and fuel particles, and the system containing only fuel particles after removing the poison; then sets the layer number n, divides the fuel particles equally and symmetrically gathers them to each equal line position, and adjusts the material similarity ratio to make the system multiplication factor equal; finally, gathers the poison particles according to the same logic and adjusts the similarity ratio to make the system multiplication factor equal. The application avoids the neutron flux distribution distortion and ensures the rationality of the power distribution through layered equal division and gathering and two-step similarity ratio optimization. Moreover, the application can accurately simulate the particle self-screening effect and realizes high-precision conversion of the double non-uniform system into a single non-uniform system.

Description

Technical Field

[0001] This invention relates to a layered processing method for plate-shaped dispersed fuel elements, belonging to the field of nuclear reactor core technology. Background Technology

[0002] In 2005, Kim Y. of South Korea proposed the Reactivity-equivalent Physical Transformation (RPT) method to address the dual inhomogeneity problem. This method first compresses the dispersed fuel region into a smaller area to ensure system reactivity conservation at the beginning of the lifespan, followed by local volume homogenization to simulate the self-shielding effect of particulate materials. This transforms the dual inhomogeneous system into a single inhomogeneous system. This method is simple and feasible, requiring only simple geometric equivalence, and has therefore been widely used in the physics analysis of dispersed particulate cores. Subsequently, for the coexistence of dispersed particulate poisons and dispersed fuel, Tsinghua University proposed an improved IRPT method. Lou Lei of the China Nuclear Power Research and Design Institute further proposed numerous improvements to the RPT method, including a toroidal RPT method that better simulates the stratification effect of combustible poisons, a toroidal RPT method for the coexistence of dispersed fuel and combustible poisons, and RPT methods for fuel cells of different shapes. Zhu Tong had previously conducted a preliminary exploration of the application of the RPT method in plate-shaped fuel elements. Meanwhile, Li Peijun et al. from Harbin Engineering University compared the applications of the traditional annular RPT method, the IRPT method, and the hybrid RPT method in plate-shaped fuel elements and proposed the reactive equivalent physical conversion (DRPT) method based on particle diameter.

[0003] However, in practice, it has been found that while the RPT method can compress the fuel region to make the particulate material more dense, thus simulating the self-shielding effect of dispersed particulate systems and achieving the effect of increasing the effective value of the equivalent particulate model, it also brings problems such as excessive distortion of the neutron flux distribution. Significant changes in the thermal neutron flux distribution lead to changes in the power distribution, which is detrimental to using the RPT equivalent model as a general analytical model. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a layered processing method for plate-shaped dispersed fuel elements. This invention effectively avoids neutron flux distribution distortion and ensures the rationality of power distribution by layered equal-division aggregation and two-step similarity ratio optimization. Moreover, by maintaining mass conservation and reactivity equivalence, this invention can accurately simulate the particle self-shielding effect and achieve high-precision conversion from a dual non-uniform system to a single non-uniform system.

[0005] To achieve the above objectives, the technical solution provided by this invention is: a layered treatment method for plate-shaped dispersed fuel elements, comprising the following steps:

[0006] (1) Calculate the effective proliferation coefficient For a dual non-uniform system of plate-shaped dispersed fuel elements containing both fuel particles and poison particles, calculate the effective multiplication coefficient k at the beginning of the system's lifetime. inf1 ;

[0007] (2) Calculate the effective proliferation coefficient Remove all poison particles from the dual non-uniform system described in step (1) to obtain a dispersed fuel element system containing only fuel particles, and then calculate the effective multiplication coefficient at the beginning of the system's lifespan. ;

[0008] (3) Determine the number of layers :set up Divide the initial total particle dispersion region into equal parts by dividing the long side of the region into equal parts. Divide the fuel into equal parts to define the fuel accumulation area; divide all fuel particles into equal parts. One, of which The fuel particles are symmetrically aggregated in a rectangular pattern at each of the bisectors, with half of each particle aggregated on each side of the plate. The area after the fuel particles aggregate is called the particulate fuel zone, and the thickness of the particulate fuel zone remains the same as the initial total particle dispersion area thickness. ;

[0009] (4) Determine the similarity ratio of fuel particle materials Maintain the thickness of the fuel accumulation zone. The length of the longer side of the initial total particle dispersion region remains unchanged. The length of the fuel accumulation area is compressed proportionally to... , ,in For similarity ratio, The search range is , The volume fraction of fuel particulate material in the initial fuel distribution region; the particulate fuel and non-fuel matrix are volume homogenized within the compressed fuel aggregation region to obtain a fuel-matrix mixture; the similarity ratio is adjusted. Until the effective multiplication coefficient at the beginning of the adjusted system's lifespan. The effective proliferation coefficient described in step (2) Equal to determine a unique fuel particle material similarity ratio ;

[0010] (5) Determine the similarity ratio of toxic particulate materials Keeping the fuel particle material distribution obtained in step (4) and the number of layers n determined in step (3) unchanged, the poison particles are divided into toxic particle aggregation regions according to the equidistant lines in step (3); the length of the toxic particle aggregation region is compressed proportionally to , ,in For similarity ratio, The search range is , The volume percentage of the toxic particulate material in the initial distribution area; then the similarity ratio is adjusted. Until the effective multiplication coefficient at the beginning of the adjusted system's lifespan. The effective proliferation coefficient described in step (1) Equal to determine the unique similarity ratio of toxic particulate materials. .

[0011] The further improvement to the above technical solution is as follows:

[0012] Effective proliferation coefficient in steps (1) and (2) and Obtained through a high-fidelity deterministic procedure or a Monte Carlo procedure.

[0013] In step (3), all fuel particles are divided equally. The specific steps for collecting and gathering the samples to the appropriate locations are as follows:

[0014] (3.1) Total fuel volume statistics and data extraction: Based on the dual non-uniform system model of the plate-shaped dispersed fuel element established in step (1) or step (2), the geometric information of all fuel particles in the calculation area is traversed, and the total volume of all fuel particles is statistically analyzed, denoted as Determine the geometric parameters of the initial total particle dispersion region, including the length of the long side. ,thickness And the spatial coordinate range of the region;

[0015] (3.2) Geometric division and bisector setting of fuel zone: based on the preset number of layers Spatial meshes are created within the initial total particle dispersion area, with meshes set along the long side. The bisectors divide the initial region geometrically into two equal parts. There are sub-regions, each with a length of . ;

[0016] (3.3) Determination of single-layer fuel volume: According to the principle of volume conservation, the total fuel volume obtained in step (3.1) is determined. Distribute equally Divide into portions and calculate the volume of each portion. ,Right now Among them, two regions located at the two edges of the plate-shaped dispersed fuel element are each allocated The volume share, the middle Each region is allocated The volume share ensures the total volume Conservation after distribution;

[0017] (3.4) Geometric reconstruction and aggregation of particulate fuel zone: maintaining thickness Without changing, the sub-regions divided in step (3.2) are defined as particulate fuel regions, and the fuel volume calculated in step (3.3) is assigned to the corresponding regions;

[0018] Located in the middle of the plate-shaped dispersed fuel element plate Each region: Centered on each bisector, construct a region of length... Thickness is A rectangular region with a volume of The fuel particle model is equivalently filled into the rectangular area, that is, in the calculation model, the original matrix material in the area is replaced by fuel mixture material of equal volume;

[0019] Two regions located on both sides of the edge of the plate-shaped dispersed fuel element: at the beginning and end of the plate, respectively, with a construction length of [missing information]. Thickness is A rectangular region with a volume of The fuel particle model is equivalently filled into this region;

[0020] (3.5) Generation and updating of the computational model: After completing the reconstruction in steps (3.1)-(3.4) above, a new geometric model is generated. In the new model, the original random dispersed particles are removed, and a new model is generated. The particulate fuel zone is symmetrically distributed in a layered manner, and the spatial distribution of all fuel particulate materials has been determined in accordance with the above steps (3.1)-(3.4).

[0021] The specific steps for determining the similarity ratio of the toxic particle material in step (5) are as follows:

[0022] (5.1) Statistical analysis and extraction of toxic particle data: Based on the original dual non-uniform system model, the geometric parameters of all toxic particles were extracted.

[0023] The total volume of all toxic particles within the calculated area is denoted as . Determine the distribution characteristics of toxic particles in the initial total dispersion area, and obtain the initial long side length of the region where the toxic particles are located. ;

[0024] (5.2) Spatial division of the toxic particle aggregation area: maintain the number of layers set in step (3). Without changing, refer to the equidistant line logic in step (3) to delineate the location of the toxic particle aggregation area;

[0025] If the toxic particles and fuel particles are spatially separated, then a boundary is set along the long side between the fuel accumulation areas. An area where toxic substances accumulate;

[0026] If toxic particles and fuel particles are distributed together, the toxic accumulation area will overlap with the fuel accumulation area.

[0027] (5.3) Calculation of the volume of a single layer of toxic substances: According to the principle of volume conservation, all toxic substance particles are divided into equal parts. Each portion has a target volume of [number] portions. Among them, half of the toxic particles are allocated to the toxic particle accumulation areas located on both sides of the edge of the plate-shaped dispersed fuel element, i.e., the volume is 0.5 × V. tox_layer Each of the toxic particle accumulation areas located in the middle of the plate-shaped dispersed fuel element is allocated a portion of toxic particles, i.e., a volume of 1×V. tox_layer ;

[0028] (5.4) Geometric reconstruction and compression of the toxic particle aggregation region: The length of the toxic particle aggregation region is proportionally compressed to l2. ,in For similarity ratio, The search range is , The volume percentage of the toxic particulate material in the initial distribution area; maintaining the thickness of the plate-shaped element. The compressed toxic substance aggregation area remains unchanged, but the toxic substance particle mixing area is redefined as the toxic substance particle mixing area.

[0029] (5.5) Volume homogenization of poison particles and matrix-fuel mixture: In the poison particle mixing region determined in step (5.4), a volume homogenization operation is performed; the poison particles and the matrix-fuel mixture in the region are regarded as a mixing system, the total mass of the material in the region is kept constant, and the discrete poison particles and matrix-fuel mixture are replaced with an equivalent poison-matrix-fuel mixture with homogeneous material properties; wherein, the matrix-fuel mixture is the fuel and matrix mixture homogenized in step (4);

[0030] (5.6) Adjust the similarity ratio s2 and calculate Maintain the fuel particle material distribution determined in step (4) and the number of layers set in step (3). The similarity ratio of the toxic particle material remains unchanged, but will be gradually adjusted. Size; adjust each time Then, repeat steps (5.4) and (5.5) to update the geometry of the poison particle mixing region and the material parameters of the poison-matrix-fuel mixture; calculate the effective multiplication coefficient at the beginning of the adjusted system's lifespan using a high-fidelity deterministic program or a Monte Carlo program, denoted as . ;

[0031] (5.7) Determine the unique toxic material similarity ratio S2: compare with the ratio calculated in step (5.6). The effective multiplication coefficient of the original dual non-uniform system in step (1) ;when and When the deviation meets the preset convergence accuracy, the search stops; the corresponding value at this time is... The value was determined as the unique similarity ratio of the toxic material. ;

[0032] The number of layers n mentioned in step (3) is a positive integer greater than 1, and is reasonably selected according to the size of the plate-shaped dispersed fuel element and the distribution density of fuel particles.

[0033] The volume homogenization process described in step (4) maintains the conservation of the total mass of the material within the region.

[0034] The plate-shaped dispersed fuel element has a cladding and a moderator arranged sequentially on the outside of the fuel zone.

[0035] As can be seen from the above technical solution, the layered treatment method for plate-shaped dispersed fuel elements provided by the present invention first calculates the effective multiplication coefficient at the beginning of the life of a dual non-uniform system containing poisons and fuel particles using a high-fidelity deterministic program or a Monte Carlo program. And the effective multiplication coefficient of a system containing only fuel particles after the removal of toxins. Secondly, set the number of layers. The fuel particles are divided into equal parts. The fuel particles are symmetrically aggregated at the bisectors while maintaining a constant thickness, by adjusting the similarity ratio of the fuel particles. The aggregation region is compressed and its volume homogenized until the effective multiplication coefficient of the system is equal to that of the aggregation region. Equal; finally, based on the determined fuel distribution, the poison particles are aggregated according to the same logic, and the similarity ratio of the poison particle materials is adjusted. Compress and homogenize until the final effective multiplication coefficient of the system is equal to... Equivalently, this completes the layered reactive equivalent physical transformation of the plate-shaped dispersed fuel element containing toxic particles and fuel particles. This invention has the following advantages over the prior art:

[0036] (1) Because the technical solution adopted in this invention processes fuel particles and poison particles by layering and equally dividing them, it avoids the problem of significant distortion of neutron flux distribution caused by a single compression region in the traditional RPT method, ensures the rationality of power distribution, and makes the equivalent model more suitable for general analysis scenarios.

[0037] (2) Because the technical solution adopted in this invention ensures the reactivity equivalence of the detoxification system and the original system through a two-step similarity ratio optimization process, and the volume homogenization process maintains mass conservation, it can accurately simulate the self-shielding effect of particles, and the effective proliferation coefficient of the converted system and the deviation of the refined particle model are maintained within the acceptable range of engineering.

[0038] (3) Because the technical solution adopted in this invention can complete the conversion between a dual non-uniform system and a single non-uniform system, the converted system is a single non-uniform system that can be processed by traditional neutronics calculation programs. There is no need to modify the existing calculation software, which lowers the threshold for engineering applications and is suitable for the core physics analysis of plate-shaped dispersed fuel elements in research reactors and power reactors. Attached Figure Description

[0039] Figure 1 Flowchart of the layered treatment method for plate-shaped dispersed fuel elements;

[0040] Figure 2 A schematic diagram of the layered processing of plate-shaped dispersed fuel elements.

[0041] In the diagram: 1. Fuel particles; 2. Toxic particles; 3. Matrix; 4. Fuel and matrix mixture. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0043] In the technical solution provided by this invention, there is a layered processing method for plate-shaped dispersed fuel elements, such as... Figure 1 and Figure 2 As shown, the specific steps include:

[0044] (1) Calculate the effective proliferation coefficient For a dual non-uniform system of plate-shaped dispersed fuel elements containing both fuel particles and poison particles, calculate the effective multiplication coefficient k at the beginning of the system's lifetime. inf1 Effective proliferation coefficient Obtained through a high-fidelity deterministic procedure or a Monte Carlo procedure.

[0045] (2) Calculate the effective proliferation coefficient Remove all poison particles from the dual non-uniform system described in step (1) to obtain a dispersed fuel element system containing only fuel particles, and then calculate the effective multiplication coefficient at the beginning of the system's lifespan. Effective proliferation coefficient Obtained through a high-fidelity deterministic procedure or a Monte Carlo procedure.

[0046] (3) Determine the number of layers :set up Divide the initial total particle dispersion region into equal parts by dividing the long side of the region into equal parts. Divide the fuel into equal parts to define the fuel accumulation area; divide all fuel particles into equal parts. One, of which The fuel particles are symmetrically aggregated in a rectangular pattern at each of the bisectors, with half of each particle aggregated on each side of the plate. The area after the fuel particles aggregate is called the particulate fuel zone, and the thickness of the particulate fuel zone remains the same as the initial total particle dispersion area thickness. The number of layers n is a positive integer greater than 1, and should be reasonably selected based on the size of the plate-shaped dispersed fuel element and the distribution density of fuel particles.

[0047] Divide all fuel particles equally The specific steps for collecting and gathering the samples to the appropriate locations are as follows:

[0048] (3.1) Total fuel volume statistics and data extraction: Based on the dual non-uniform system model of the plate-shaped dispersed fuel element established in step (1) or step (2), the geometric information of all fuel particles in the calculation area is traversed, and the total volume of all fuel particles is statistically analyzed, denoted as Determine the geometric parameters of the initial total particle dispersion region, including the length of the long side. ,thickness And the spatial coordinate range of the region;

[0049] (3.2) Geometric division and bisector setting of fuel zone: based on the preset number of layers Spatial meshes are created within the initial total particle dispersion area, with meshes set along the long side. The bisectors divide the initial region geometrically into two equal parts. There are sub-regions, each with a length of . ;

[0050] (3.3) Determination of single-layer fuel volume: According to the principle of volume conservation, the total fuel volume obtained in step (3.1) is determined. Distribute equally Divide into portions and calculate the volume of each portion. ,Right now Among them, two regions located at the two edges of the plate-shaped dispersed fuel element are each allocated The volume share, the middle Each region is allocated The volume share ensures the total volume Conservation after distribution;

[0051] (3.4) Geometric reconstruction and aggregation of particulate fuel zone: maintaining thickness Without changing, the sub-regions divided in step (3.2) are defined as particulate fuel regions, and the fuel volume calculated in step (3.3) is assigned to the corresponding regions;

[0052] Located in the middle of the plate-shaped dispersed fuel element plate Each region: Centered on each bisector, construct a region of length... Thickness is A rectangular region with a volume of The fuel particle model is equivalently filled into the rectangular area, that is, in the calculation model, the original matrix material in the area is replaced by fuel mixture material of equal volume;

[0053] Two regions located on both sides of the edge of the plate-shaped dispersed fuel element: at the beginning and end of the plate, respectively, with a construction length of [missing information]. Thickness is A rectangular region with a volume of The fuel particle model is equivalently filled into this region;

[0054] (3.5) Generation and updating of the computational model: After completing the reconstruction in steps (3.1)-(3.4) above, a new geometric model is generated. In the new model, the original random dispersed particles are removed, and a new model is generated. The particulate fuel zone is symmetrically distributed in a layered manner, and the spatial distribution of all fuel particulate materials has been determined in accordance with the above steps (3.1)-(3.4).

[0055] (4) Determine the similarity ratio of fuel particle materials Maintain the thickness of the fuel accumulation zone. The length of the longer side of the initial total particle dispersion region remains unchanged. The length of the fuel accumulation area is compressed proportionally to... , ,in For similarity ratio, The search range is , The volume fraction of fuel particulate material in the initial fuel distribution region; the particulate fuel and non-fuel matrix are volume homogenized within the compressed fuel aggregation region to obtain a fuel-matrix mixture; the similarity ratio is adjusted. Until the effective multiplication coefficient at the beginning of the adjusted system's lifespan. The effective proliferation coefficient described in step (2) Equal to determine a unique fuel particle material similarity ratio The volume homogenization process maintains the conservation of the total mass of the material within the region.

[0056] (5) Determine the similarity ratio of toxic particulate materials Keeping the fuel particle material distribution obtained in step (4) and the number of layers n determined in step (3) unchanged, the poison particles are divided into toxic particle aggregation regions according to the equidistant lines in step (3); the length of the toxic particle aggregation region is compressed proportionally to , ,in For similarity ratio, The search range is , The volume percentage of the toxic particulate material in the initial distribution area; then the similarity ratio is adjusted. Until the effective multiplication coefficient at the beginning of the adjusted system's lifespan. The effective proliferation coefficient described in step (1) Equal to determine the unique similarity ratio of toxic particulate materials. .

[0057] The specific steps for determining the similarity ratio of toxic particle materials are as follows:

[0058] (5.1) Statistical analysis and extraction of toxic particle data: Based on the original dual non-uniform system model, the geometric parameters of all toxic particles were extracted.

[0059] The total volume of all toxic particles within the calculated area is denoted as . Determine the distribution characteristics of toxic particles in the initial total dispersion area, and obtain the initial long side length of the region where the toxic particles are located. If toxic particles and fuel particles are co-distributed, then The length of the long side of the initial fuel distribution region same;

[0060] (5.2) Spatial division of the toxic particle aggregation area: maintain the number of layers set in step (3). Without changing, refer to the equidistant line logic in step (3) to delineate the location of the toxic particle aggregation area;

[0061] If the toxic particles and fuel particles are spatially separated, then a boundary is set along the long side between the fuel accumulation areas. An area where toxic substances accumulate;

[0062] If toxic particles and fuel particles are distributed together, the toxic accumulation area will overlap with the fuel accumulation area.

[0063] (5.3) Calculation of the volume of a single layer of toxic substances: According to the principle of volume conservation, all toxic substance particles are divided into equal parts. Each portion has a target volume of [number] portions. Among them, half of the toxic particles are allocated to the toxic particle accumulation areas located on both sides of the edge of the plate-shaped dispersed fuel element, i.e., the volume is 0.5 × V. tox_layerEach of the toxic particle accumulation areas located in the middle of the plate-shaped dispersed fuel element is allocated a portion of toxic particles, i.e., a volume of 1×V. tox_layer ;

[0064] (5.4) Geometric reconstruction and compression of the toxic particle aggregation region: The length of the toxic particle aggregation region is proportionally compressed to l2. ,in For similarity ratio, The search range is , The volume percentage of the toxic particulate material in the initial distribution area; maintaining the thickness of the plate-shaped element. The compressed toxic substance aggregation area remains unchanged, but the toxic substance particle mixing area is redefined as the toxic substance particle mixing area.

[0065] (5.5) Volume homogenization of poison particles and matrix-fuel mixture: In the poison particle mixing region determined in step (5.4), a volume homogenization operation is performed; the poison particles and the matrix-fuel mixture in the region are regarded as a mixing system, the total mass of the material in the region is kept constant, and the discrete poison particles and matrix-fuel mixture are replaced with an equivalent poison-matrix-fuel mixture with homogeneous material properties; wherein, the matrix-fuel mixture is the fuel and matrix mixture homogenized in step (4);

[0066] (5.6) Adjust the similarity ratio s2 and calculate Maintain the fuel particle material distribution determined in step (4), i.e., the length l1 of the fuel aggregation region after compression by similarity ratio S1, the homogenized fuel-matrix mixture, and the number of layers set in step (3). The similarity ratio of the toxic particle material remains unchanged, but will be gradually adjusted. Size; adjust each time Then, repeat steps (5.4) and (5.5) to update the geometry of the poison particle mixing region and the material parameters of the poison-matrix-fuel mixture; calculate the effective multiplication coefficient at the beginning of the adjusted system's lifespan using a high-fidelity deterministic program or a Monte Carlo program, denoted as . ;

[0067] (5.7) Determine the unique toxic material similarity ratio S2: compare with the ratio calculated in step (5.6). The effective multiplication coefficient of the original dual non-uniform system in step (1) ;when and When the deviation meets the preset convergence accuracy, the search stops; the corresponding value at this time is... The value was determined as the unique similarity ratio of the toxic material. In this embodiment, the preset convergence accuracy is a deviation of less than 10. -5 .

[0068] The plate-shaped dispersed fuel element has a cladding and moderator arranged sequentially on the outside of the fuel zone, which conforms to the actual fuel element structure design of a nuclear reactor.

[0069] Example 1

[0070] This embodiment focuses on a plate-shaped dispersed fuel element, whose fuel region has a long side The shorter side (thickness) Volume ratio of fuel particles in the initial fuel region It contains two types of dispersed particles: fuel particles and toxic particles, which are converted using the layered processing method of this invention:

[0071] The effective multiplication factor at the beginning of the lifetime of the original dual non-uniform system was calculated using the Monte Carlo procedure. .

[0072] After removing toxic particles, the effective multiplication factor at the beginning of the lifespan of the fuel particle-only system was calculated using the Monte Carlo program. .

[0073] Select the number of layers Nine equidistant lines were determined, dividing the long side of the fuel zone into ten equal parts. The fuel particles were divided into ten equal parts, and nine parts were symmetrically gathered at the nine equidistant lines. 0.5 parts were gathered on each side of the plate. After gathering, the thickness of the fuel particle zone was still 0.51 mm.

[0074] Determine the similarity ratio of fuel materials : The search range is Right now The corresponding similarity ratio range, according to the formula The length of the compressed aggregation region is increased, and the fuel particles within the compressed region are homogenized with the matrix, adjusting... To the system Finally determined .

[0075] Determine the similarity ratio of toxic materials Keeping the above material distribution and n constant, treat the toxic particles in the same way, and adjust s2 to the system. Finally determined .

[0076] After conversion, a single non-uniform system was obtained. The burnup was calculated using a traditional neutronics calculation program. The results showed that the deviation of the system reactivity from the original particle model was less than 75 pcm throughout the entire lifetime, which is far better than the deviation level of the traditional RPT method. Moreover, the power distribution distortion was reduced by more than 70%.

[0077] As can be seen from the results of the embodiments, through the standardized process of "poison statistics - region division - volume equalization - geometric compression - mixing homogenization - parameter adjustment", the present invention achieves equivalent mixing of poison particles and matrix-fuel mixture, ensuring that the final layered model is strictly equivalent to the original dual non-uniform system in terms of neutronics properties. The plate-shaped dispersed fuel element dual non-uniform system has been reactivity equivalently converted into a single non-uniform system. The converted system can be directly modeled and calculated using traditional neutronics calculation programs.

Claims

1. A layered treatment method for plate-shaped dispersed fuel elements, characterized in that, Includes the following steps: (1) Calculate the effective proliferation coefficient For a dual non-uniform system of plate-shaped dispersed fuel elements containing both fuel particles and poison particles, calculate the effective multiplication coefficient k at the beginning of the system's lifetime. inf1 ; (2) Calculate the effective proliferation coefficient Remove all poison particles from the dual non-uniform system described in step (1) to obtain a dispersed fuel element system containing only fuel particles, and then calculate the effective multiplication coefficient at the beginning of the system's lifespan. ; (3) Determine the number of layers :set up Divide the initial total particle dispersion region into equal parts by dividing the long side of the region into equal parts. Divide the fuel into equal parts to define the fuel accumulation area; divide all fuel particles into equal parts. One, of which The fuel particles are symmetrically aggregated in a rectangular pattern at each of the bisectors, with half of each particle aggregated on each side of the plate. The area after the fuel particles aggregate is called the particulate fuel zone, and the thickness of the particulate fuel zone remains the same as the initial total particle dispersion area thickness. ; (4) Determine the similarity ratio of fuel particle materials Maintain the thickness of the fuel accumulation zone. The length of the longer side of the initial total particle dispersion region remains unchanged. The length of the fuel accumulation area is compressed proportionally to... , ,in For similarity ratio, The search range is , The volume fraction of fuel particulate material in the initial fuel distribution region; the particulate fuel and non-fuel matrix are volume homogenized within the compressed fuel aggregation region to obtain a fuel-matrix mixture; the similarity ratio is adjusted. Until the effective multiplication coefficient at the beginning of the adjusted system's lifespan. The effective proliferation coefficient described in step (2) Equal to determine a unique fuel particle material similarity ratio ; (5) Determine the similarity ratio of toxic particulate materials Keeping the fuel particle material distribution obtained in step (4) and the number of layers n determined in step (3) unchanged, the poison particles are divided into toxic particle aggregation regions according to the bisectors in step (3); the length of the toxic particle aggregation region is compressed proportionally to... , ,in For similarity ratio, The search range is , The volume percentage of the toxic particulate material in the initial distribution area; then the similarity ratio is adjusted. Until the effective multiplication coefficient at the beginning of the adjusted system's lifespan. The effective proliferation coefficient described in step (1) Equal to determine the unique similarity ratio of toxic particulate materials. .

2. The layered treatment method for plate-shaped dispersed fuel elements according to claim 1, characterized in that: Effective proliferation coefficient in steps (1) and (2) and Obtained through a high-fidelity deterministic procedure or a Monte Carlo procedure.

3. The layered treatment method for plate-shaped dispersed fuel elements according to claim 1, characterized in that, In step (3), all fuel particles are divided equally. The specific steps for collecting and gathering the samples to the appropriate locations are as follows: (3.1) Total fuel volume statistics and data extraction: Based on the dual non-uniform system model of the plate-shaped dispersed fuel element established in step (1) or step (2), the geometric information of all fuel particles in the calculation area is traversed, and the total volume of all fuel particles is statistically analyzed, denoted as Determine the geometric parameters of the initial total particle dispersion region, including the length of the long side. ,thickness And the spatial coordinate range of the region; (3.2) Geometric division and bisector setting of fuel zone: based on the preset number of layers Spatial meshes are created within the initial total particle dispersion area, with meshes set along the long side. The bisectors divide the initial region geometrically into two equal parts. There are sub-regions, each with a length of . ; (3.3) Determination of single-layer fuel volume: According to the principle of volume conservation, the total fuel volume obtained in step (3.1) is determined. Distribute equally Divide into portions and calculate the volume of each portion. ,Right now Among them, two regions located at the two edges of the plate-shaped dispersed fuel element are each allocated The volume share, the middle Each region is allocated The volume share ensures the total volume Conservation after distribution; (3.4) Geometric reconstruction and aggregation of particulate fuel zone: maintaining thickness Without changing, the sub-regions divided in step (3.2) are defined as particulate fuel regions, and the fuel volume calculated in step (3.3) is assigned to the corresponding regions; Located in the middle of the plate-shaped dispersed fuel element plate Each region: Centered on each bisector, construct a region of length... Thickness is A rectangular region with a volume of The fuel particle model is equivalently filled into the rectangular area, that is, in the calculation model, the original matrix material in the area is replaced by fuel mixture material of equal volume; Two regions located on both sides of the edge of the plate-shaped dispersed fuel element: at the beginning and end of the plate, respectively, with a construction length of [missing information]. Thickness is A rectangular region with a volume of The fuel particle model is equivalently filled into this region; (3.5) Generation and updating of the computational model: After completing the reconstruction in steps (3.1)-(3.4) above, a new geometric model is generated. In the new model, the original random dispersed particles are removed, and a new model is generated. The particulate fuel zone is symmetrically distributed in a layered manner, and the spatial distribution of all fuel particulate materials has been determined in accordance with the above steps (3.1)-(3.4).

4. The layered treatment method for plate-shaped dispersed fuel elements according to claim 1, the specific steps for determining the similarity ratio of poison particles in step (5) are as follows: (5.1) Statistical analysis and extraction of toxic particle data: Based on the original dual non-uniform system model, the geometric parameters of all toxic particles were extracted. The total volume of all toxic particles within the calculated area is denoted as . Determine the distribution characteristics of toxic particles in the initial total dispersion area, and obtain the initial long side length of the region where the toxic particles are located. ; (5.2) Spatial division of the toxic particle aggregation area: maintain the number of layers set in step (3). Without changing, refer to the equidistant line logic in step (3) to delineate the location of the toxic particle aggregation area; If the toxic particles and fuel particles are spatially separated, then a boundary is set along the long side between the fuel accumulation areas. An area where toxic substances accumulate; If toxic particles and fuel particles are distributed together, the toxic accumulation area will overlap with the fuel accumulation area. (5.3) Calculation of the volume of a single layer of toxic substances: According to the principle of volume conservation, all toxic substance particles are divided into equal parts. Each portion has a target volume of [number] portions. ;in, The toxic particle accumulation areas located on both sides of the plate-shaped dispersed fuel element plate are each allocated half a portion of the toxic particles, i.e., a volume of 0.5 × V. tox_layer Each of the toxic particle accumulation areas located in the middle of the plate-shaped dispersed fuel element is allocated a portion of toxic particles, i.e., a volume of 1×V. tox_layer ; (5.4) Geometric reconstruction and compression of the toxic particle aggregation region: The length of the toxic particle aggregation region is proportionally compressed to l2. ,in For similarity ratio, The search range is , The volume percentage of the toxic particulate material in the initial distribution area; maintaining the thickness of the plate-shaped element. The compressed toxic substance aggregation area remains unchanged, but the toxic substance particle mixing area is redefined as the toxic substance particle mixing area. (5.5) Volume homogenization of poison particles and matrix-fuel mixture: In the poison particle mixing region determined in step (5.4), a volume homogenization operation is performed; the poison particles and the matrix-fuel mixture in the region are regarded as a mixing system, the total mass of the material in the region is kept constant, and the discrete poison particles and matrix-fuel mixture are replaced with an equivalent poison-matrix-fuel mixture with homogeneous material properties; wherein, the matrix-fuel mixture is the fuel and matrix mixture homogenized in step (4); (5.6) Adjust the similarity ratio s2 and calculate Maintain the fuel particle material distribution determined in step (4) and the number of layers set in step (3). The similarity ratio of the toxic particle material remains unchanged, but will be gradually adjusted. Size; adjust each time Then, repeat steps (5.4) and (5.5) to update the geometry of the poison particle mixing region and the material parameters of the poison-matrix-fuel mixture; calculate the effective multiplication coefficient at the beginning of the adjusted system's lifespan using a high-fidelity deterministic program or a Monte Carlo program, denoted as . ; (5.7) Determine the unique toxic material similarity ratio S2: compare with the ratio calculated in step (5.6). The effective multiplication coefficient of the original dual non-uniform system in step (1) ;when and When the deviation meets the preset convergence accuracy, the search stops; the corresponding value at this time is... The value was determined as the unique similarity ratio of the toxic material. .

5. The layered treatment method for plate-shaped dispersed fuel elements according to claim 1, characterized in that: The number of layers n mentioned in step (3) is a positive integer greater than 1, and is reasonably selected according to the size of the plate-shaped dispersed fuel element and the distribution density of fuel particles.

6. The layered treatment method for plate-shaped dispersed fuel elements according to claim 1, characterized in that: The volume homogenization process described in step (4) maintains the conservation of the total mass of the material within the region.

7. The layered treatment method for plate-shaped dispersed fuel elements according to claim 1, characterized in that: The plate-shaped dispersed fuel element has a cladding and a moderator arranged sequentially on the outside of the fuel zone.

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