Study on the method of multi-group cross-section homogenization correction for irradiation channels of research reactors

Abstract

This application proposes a calculation method for homogenization correction of multi-group cross-sections in irradiated channels for research reactors, comprising: obtaining geometric and material parameters of the irradiated channel region and the non-irradiated channel region under preset operating conditions; establishing a three-dimensional geometric model of the research reactor based on the geometric and material parameters using a Monte Carlo program; constructing a first grid homogenized region for the irradiated channel region according to an adaptive homogenization rule, and constructing a second grid homogenized region for the non-irradiated channel region according to a preset homogenization rule based on the three-dimensional geometric model; calculating the statistical physical quantities of a specified energy group based on the first grid homogenized region and the second grid homogenized region, and generating an initial multi-group cross-section based on the statistical physical quantities; iteratively optimizing the initial multi-group cross-section using a super homogenization correction factor until the super homogenization correction factor converges to obtain the multi-group cross-section.

Description

Technical Field

[0001] This application mainly relates to the field of nuclear power plants, and in particular to a calculation method for multi-group cross-section homogenization correction of reactor irradiation channels. Background Technology

[0002] Research reactors play an irreplaceable role in fundamental nuclear physics research, fuel and material irradiation testing, radioactive isotope production, and nuclear medicine. A research reactor typically consists of irradiation channels, standard fuel assemblies, follower fuel assemblies with control rods, a heavy water tank, and heavy water that serves as both coolant and moderator. Within the reflector zone of the research reactor, several irradiation channels are located to accommodate various targets; the insertion and removal of targets is one of the fundamental operations in the daily operation of a research reactor.

[0003] Because the neutronics properties of the target material inside the irradiation channel are significantly different from those of the surrounding moderator, changes in the target under different loading conditions will cause the reconstruction of the local reactivity and power distribution of the reactor core, which in turn directly affects the reliability of the multi-group cross-section calculation results and the accuracy of the physical analysis of the reactor.

[0004] In engineering practice, to balance computational efficiency, deterministic three-dimensional diffusion programs are typically used for physical calculations and analyses of research reactors. These programs often employ mesh homogenization methods, dividing the irradiation channel region into regular orthogonal grids. However, the actual center position of the irradiation channel is often difficult to precisely align with the fuel assembly grid boundary, resulting in a single channel being subdivided into multiple adjacent grids. In this situation, if the mesh homogenization method of deterministic three-dimensional diffusion programs is used, it cannot accurately describe the local perturbation effects of the irradiation channel under different operating conditions (such as target insertion or removal), thus limiting the accuracy and reliability of the physical analysis results.

[0005] Furthermore, during the conversion from a non-uniform fine model to a homogenized multi-group model, the generated multi-group cross section introduces a non-negligible systematic error due to various approximations such as spatial homogenization, energy group merging, isotropic scattering approximation, and flux separability approximation.

[0006] In summary, there is an urgent need for a multi-group cross-section calculation method for research reactors capable of handling the physical characteristics of complex irradiation channels. Summary of the Invention

[0007] Based on the above problems, this application proposes a calculation method for homogenization correction of multi-group cross-sections in the study of irradiation channels for reactors, so as to improve the accuracy of multi-group cross-section calculation.

[0008] Firstly, this application proposes a multi-group cross-section homogenization correction calculation method for irradiation channels in a research reactor. The research reactor includes at least one irradiation channel, a standard fuel assembly, a follower fuel assembly with control rods, a heavy water tank, and heavy water. The method includes the following steps: S1: Obtaining the geometric and material parameters of the irradiation channel region and the non-irradiation channel region under preset operating conditions; S2: Based on the geometric and material parameters, establishing a three-dimensional geometric model of the research reactor using a Monte Carlo program; S3: Based on the three-dimensional geometric model, constructing a first grid homogenization region for the irradiation channel region according to adaptive homogenization rules, and then... The non-irradiated channel region is constructed into a second grid homogenized region according to a preset homogenization rule; S4: Statistical physical quantities of a specified energy group are calculated based on the first grid homogenized region and the second grid homogenized region, and an initial multi-group cross section is generated according to the statistical physical quantities; S5: The initial multi-group cross section is iteratively optimized using a super homogenization correction factor until the super homogenization correction factor converges to obtain the multi-group cross section; wherein, the irradiated channel region includes the heavy water tank, the heavy water, and the at least one irradiated channel, and the non-irradiated channel region includes the standard fuel assembly and the follower fuel assembly with control rods.

[0009] Secondly, this application also proposes an electronic device comprising: a memory for storing instructions executable by a processor; and a processor for executing the instructions to implement the method described in the first aspect.

[0010] Thirdly, this application also proposes a computer storage medium storing computer program code that, when executed by a processor, implements the method described in the first aspect.

[0011] Compared with the prior art, the beneficial effects of this application are as follows: (1) Based on the proposed adaptive homogenization rule, this application constructs a first grid homogenization region based on the irradiation channel, so that in the process of calculating multiple cross sections, it can more accurately describe the local disturbance effect caused by the state change of each irradiation channel under different working conditions. (2) By using the super homogenization correction factor, the systematic error introduced in the process of generating multi-group cross sections is reduced, thereby improving the calculation accuracy of multi-group cross sections. Attached Figure Description

[0012] The accompanying drawings are included to provide a further understanding of this application; they are incorporated into and constitute a part of this application. The drawings illustrate embodiments of this application and, together with this specification, serve to explain the principles of this application. In the drawings: Figure 1 This is a schematic diagram of a research reactor structure, illustrating the calculation method for multi-group cross-section homogenization correction of irradiation channels for research reactors provided in this application embodiment. Figure 2 This is a flowchart illustrating the calculation method for multi-group cross-section homogenization correction of irradiation channels for research reactors provided in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of the first grid non-homogenized region and the second grid non-homogenized region of the research reactor, which is a multi-group cross-section homogenization correction calculation method for irradiation channels of the research reactor provided in this application embodiment. Figure 4 This is a schematic diagram of the structure of the first grid homogenization region and the second grid homogenization region of the research reactor provided in the embodiment of the present application for the calculation method of multi-group cross-section homogenization correction of irradiation channels for research reactors. Figure 5 This is a flowchart illustrating the calculation method for the multi-group cross-section homogenization correction calculation method of the research reactor irradiation channel provided in the embodiments of this application. Figure 6 This is a flowchart illustrating the calculation method for correcting the multi-group cross-section homogenization of the irradiation channel for the research reactor provided in this application embodiment, which introduces a super homogenization correction factor to correct the multi-group cross-section. Figure 7 This is a comparative schematic diagram of the effective growth factor values ​​of the multi-group cross-section homogenization correction calculation method for irradiation channels in research reactors provided in the embodiments of this application; Figure 8 This is a schematic diagram of the relative error percentage of component power in a research reactor based on the multi-group cross-section homogenization correction calculation method for irradiation channels provided in this application embodiment. Figure 9 This is a block diagram of an electronic device for calculating a multi-group cross-section homogenization correction method for irradiation channels used in a research reactor, as provided in an embodiment of this application.

[0013] Reference numerals: Irradiation channel 210, Standard fuel assembly 220, Follower fuel assembly with control rod 230, Heavy water tank 240, Heavy water 250, First grid non-homogenized region 320, Second grid non-homogenized region 330, First grid homogenized region 420, Second grid homogenized region 430, First non-homogenized grid 301, Second non-homogenized grid 302, Third non-homogenized grid 303, Fourth non-homogenized grid 304, Fifth non-homogenized grid 305, Sixth non-homogenized grid 306, Seventh non-homogenized grid 307, Eighth non-homogenized grid 308, Ninth non-homogenized grid 309, Tenth non-homogenized grid 310, Eleventh non-homogenized grid 311 12th Unhomogenized Mesh 312, 13th Unhomogenized Mesh 313, 14th Unhomogenized Mesh 314, 15th Unhomogenized Mesh 315, 1st Homogenized Mesh 401, 2nd Homogenized Mesh 402, 3rd Homogenized Mesh 403, 4th Homogenized Mesh 404, 5th Homogenized Mesh 405, 6th Homogenized Mesh 406, 7th Homogenized Mesh 407, 8th Homogenized Mesh 408, 9th Homogenized Mesh 409, 10th Homogenized Mesh 410, 11th Homogenized Mesh 411, 12th Homogenized Mesh 412, 13th Homogenized Mesh 413, 14th Homogenized Mesh 414, 15th Homogenized Mesh 415, 1st Polyline 710, Baseline 720. Detailed Implementation

[0014] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this application. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0015] As indicated in this application, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0016] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0017] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0018] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0019] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. In addition, although the terminology used in this application is selected from commonly known and used terms, some terms mentioned in this application's specification may have been chosen by the applicant according to his or her judgment, and their detailed meanings are explained in the relevant sections of this description. Moreover, this application should be understood not only through the actual terms used, but also through the meaning implied by each term.

[0020] Flowcharts are used in this application to illustrate the operations performed by the system according to embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, various steps can be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more steps may be removed from these processes.

[0021] The following specific examples illustrate the calculation method for multi-group cross-section homogenization correction of irradiation channels used in research reactors.

[0022] The following approach is commonly used in research reactor physics analysis: First, a sophisticated neutron transport calculation method (such as the continuous energy Monte Carlo transport simulation method) is used to model and calculate the non-uniform research reactor, generating a multi-group cross-section database; then, the multi-group cross-section data is input into a three-dimensional diffusion program to perform three-dimensional diffusion calculations for the entire reactor.

[0023] However, when using the above method for three-dimensional analysis and calculation of the research pile, the following technical bottlenecks exist. For computational efficiency, three-dimensional diffusion programs typically employ a pre-defined homogenized mesh generation method, dividing the research pile into regular and orthogonal meshes (such as square or hexagonal meshes). However, as... Figure 1 As shown, the arrangement of irradiation channels 210 in the research reactor is not uniform. According to the aforementioned pre-defined homogenization grid division method, a single irradiation channel 210 may be divided into multiple adjacent grids by the grid boundaries. In addition, due to the significant differences in neutronics properties between the target material and the surrounding moderator, the insertion or removal of the target will significantly change the local reactivity and power distribution of the research reactor. Therefore, if the pre-defined homogenization grid division method is used, the irradiation channel 210 may be divided into multiple regions, which will destroy the geometrical integrity between the irradiation channel 210 and the surrounding moderator. This will result in the homogenization section within each grid failing to accurately reflect the refined impact of target state changes (insertion / removal) on local neutron flux and power within the irradiation channel, and thus failing to accurately describe the local perturbation effect caused by target state changes within a single irradiation channel.

[0024] In addition, during the conversion from a non-homogeneous research reactor 3D model to a homogenized model, the use of various approximations such as mesh homogenization, energy group merging, isotropic scattering approximation, and flux separability approximation will introduce non-negligible systematic errors into the generated multi-group cross sections.

[0025] For the reasons mentioned above, this application proposes a multi-group cross-section homogenization correction calculation method for studying reactor irradiation channels. This method constructs a mesh homogenization region by using an adaptive mesh homogenization rule that better reflects the true geometric location of each irradiation channel. This allows for a more accurate description of the local perturbation effects caused by changes in state under different operating conditions (e.g., target insertion or target extraction) within a single irradiation channel. Simultaneously, by using an iterative correction method with a superhomogenization (SPH) correction factor, the systematic errors introduced by mesh homogenization and energy group merging are significantly eliminated, improving the accuracy of multi-group cross-section calculations.

[0026] Reference Figure 2 The calculation method for multi-group cross-section homogenization correction of irradiation channels for research reactors proposed in this application includes... Figure 2 Steps S1 to S5 in the process.

[0027] Step S1: Obtain the geometric and material parameters of the irradiated and non-irradiated pore regions under preset operating conditions.

[0028] For details, please refer to Figure 1 The research reactor includes at least one irradiation channel 210, a standard fuel assembly 220, a follower fuel assembly with control rods 230, a heavy water tank 240, and heavy water 250. The geometric and material parameters of these assemblies are obtained. The geometric parameters include the geometric position, shape, and size of the assemblies, while the material parameters include density, thermal conductivity, specific heat capacity, and coefficient of thermal expansion.

[0029] In step S2, a three-dimensional geometric model of the research reactor is established using the Monte Carlo program based on geometric and material parameters.

[0030] Specifically, based on the geometric and material parameters of the research reactor obtained in step S1, a Monte Carlo simulation is used to establish a refined three-dimensional geometric model of the research reactor. Furthermore, during the establishment of the three-dimensional geometric model, each irradiation channel 210 is kept at its true geometric center without any artificial offset. This provides an accurate model foundation for subsequent multi-group cross-section calculations.

[0031] In step S3, based on the three-dimensional geometric model of the research pile, a first grid homogenization region 420 is constructed for the irradiated channel region according to an adaptive homogenization rule, and a second grid homogenization region 430 is constructed for the non-irradiated channel region according to a preset homogenization rule.

[0032] For details, please refer to Figure 1 The irradiation channel region includes a heavy water tank 240, heavy water 250 and at least one irradiation channel 210, while the non-irradiation channel region includes a standard fuel assembly 220 and a follower fuel assembly 230 with a control rod.

[0033] In some embodiments, the adaptive homogenization rule includes adaptively dividing at least one geometrically adjacent irradiation channel 210 into a first grid non-homogeneous region 320, wherein the number of irradiation channels in the first grid non-homogeneous region 320 is adaptively adjusted according to the geometric parameters and geometric positions of the irradiation channel 210, the first grid non-homogeneous region 320 includes a heavy water tank 240 and heavy water 250, and homogenizing the first grid non-homogeneous region 320 into a first grid homogenized region 420.

[0034] For details, please refer to Figure 3 The irradiated channel region of the research reactor is adaptively divided into a first grid inhomogeneous region 320, which includes first inhomogeneous grid 301, second inhomogeneous grid 302, third inhomogeneous grid 303, fourth inhomogeneous grid 304, fifth inhomogeneous grid 305, sixth inhomogeneous grid 306, seventh inhomogeneous grid 307, eighth inhomogeneous grid 308, ninth inhomogeneous grid 309, tenth inhomogeneous grid 310, eleventh inhomogeneous grid 311, twelfth inhomogeneous grid 312, thirteenth inhomogeneous grid 313, fourteenth inhomogeneous grid 314, and fifteenth inhomogeneous grid 315. The non-irradiated channel region of the research reactor is divided into a second grid inhomogeneous region 330, which is located in the middle of the first grid inhomogeneous region 320. (Reference) Figure 3 and Figure 4 The ununiformed region 320 of the first grid and the ununiformed region 330 of the second grid are homogenized into a homogenized region 420 of the first grid and a homogenized region 430 of the second grid, respectively. The homogenized region 420 of the first grid includes a first homogenized grid 401, a second homogenized grid 402, a third homogenized grid 403, a fourth homogenized grid 404, a fifth homogenized grid 405, a sixth homogenized grid 406, a seventh homogenized grid 407, an eighth homogenized grid 408, a ninth homogenized grid 409, a tenth homogenized grid 410, an eleventh homogenized grid 411, a twelfth homogenized grid 412, a thirteenth homogenized grid 413, a fourteenth homogenized grid 414, and a fifteenth homogenized grid 415. The ununiformed grids 301 to 315 correspond one-to-one with the homogenized grids 401 to 415.

[0035] The irradiation channel region of the research reactor is homogenized into a first grid homogenized region 420 by an adaptive homogenization rule. The adaptive homogenization rule is as follows: if multiple irradiation channels 210 are geometrically adjacent and have the same geometric size, the multiple irradiation channels 210 and the nearby heavy water tanks 240 and heavy water 250 are divided into a grid, namely the first grid unhomogenized region 320, and then the first grid unhomogenized region 320 is homogenized into the first grid homogenized region 420. For example, the seven irradiation channels 210 within the third non-homogenized grid 303, along with the nearby heavy water tank 240 and heavy water 250, can be divided into one grid, and then the third non-homogenized grid 303 can be homogenized into a third homogenized grid 403. If multiple irradiation channels 210 are geometrically adjacent but have different geometric dimensions, they can be divided into one grid. For example, the four irradiation channels 210 within the fifteenth non-homogenized grid 315, along with the nearby heavy water tank 240 and heavy water 250, can be divided into one grid, and then the fifteenth non-homogenized grid 315 can be homogenized into a fifteenth homogenized grid 415. Alternatively, the division into the same grid can be determined according to actual needs and accuracy. The number of irradiation channels within the first grid homogenization region 420 is defined as follows: For example, one irradiation channel 210 within the fifth non-homogenized grid 305, along with the nearby heavy water tank 240 and heavy water 250, are divided into the same grid, and then the fifth non-homogenized grid 305 is homogenized into the fifth homogenized grid 405. Similarly, three irradiation channels 210 within the ninth non-homogenized grid 309, along with the nearby heavy water tank 240 and heavy water 250, are divided into the same grid, and then the ninth non-homogenized grid 309 is homogenized into the ninth homogenized grid 409. Furthermore, a second non-homogenized grid 302 without irradiation channels 210 is included, and the heavy water tank 240 and heavy water 250 within the second non-homogenized grid 302 are homogenized into the second homogenized grid 402. In other words, during the formation of the first grid homogenization region 420, the real area space corresponding to each irradiation channel 210 is mapped one-to-one to the center of the homogenized grid closest to the real center of each irradiation channel 210 within the first grid homogenization region 420. Constructing the first grid homogenization region 420 according to the above method can prevent the irradiation channel 210 from being divided into multiple adjacent grids by the grid boundary, so as to more accurately describe the local disturbance effect caused by the change of target state within the irradiation channel 210.

[0036] In some embodiments, reference Figure 4The preset homogenization rule is the same as that used in the deterministic research reactor three-dimensional diffusion program. The preset homogenization rule divides the non-irradiated channel region into orthogonal grids (such as square or hexagonal grids) and then homogenizes them to form a second grid homogenized region 430. This second grid homogenized region 430 is formed differently from the first grid homogenized region 420. Besides accurately describing the local disturbance effects caused by changes in the target state within the irradiated channel 210, it also improves the accuracy of multi-group cross-section calculations.

[0037] In some embodiments, the volume and material composition of the first mesh homogenized region 420 in the three-dimensional geometric model are the same as those of the corresponding first mesh non-homogenized region 320 in the three-dimensional geometric model, and the volume and material composition of the second mesh homogenized region 430 in the three-dimensional geometric model are the same as those of the corresponding second mesh non-homogenized region 330 in the three-dimensional geometric model. The material composition may include fuel materials (such as uranium-235) or moderator materials (such as heavy water). This provides an accurate geometric basis for subsequent multi-group cross-section calculations. Furthermore, the consistent volume and material composition ensures the strict validity of the reaction rate conservation principle, resulting in high fidelity multi-group cross-section calculations based on this principle.

[0038] In step S4, statistical physical quantities of a specified energy group are calculated based on the first grid homogenization region 420 and the second grid homogenization region 430, and an initial multi-group cross section is generated based on the statistical physical quantities.

[0039] In some embodiments, such as Figure 5 The steps for generating initial multigroup cross sections based on statistical physical quantities include: Figure 5 Steps S41 and S42 in the process.

[0040] In step S41, statistical physical quantities are calculated based on the first grid homogenization region 420 and the second grid homogenization region 430 using the continuous energy Monte Carlo transport simulation method. The statistical physical quantities include the total reaction rate of each grid homogenization region and each reaction type, the total standard flux of each grid homogenization region, and the neutron transfer probability of the energy group of the scattering reaction.

[0041] Specifically, based on the continuous energy Monte Carlo transport simulation method, statistical physical quantities are calculated in the first grid homogenization region 420 and the second grid homogenization region 430, as well as in the specified multi-group energy group G. These statistical physical quantities include reaction... ,area Total reaction rate ,area Total standard flux It also includes the scattering reaction from the first Group to the The neutron transition probability of the group, where the region This represents the region divided within the first grid homogenization region 420 and the second grid homogenization region 430, reflecting... It represents multiple reaction types.

[0042] In step S42, based on the principle of reaction rate conservation, the initial multi-group cross section is calculated using the energy group neutron transfer probability, the total reaction rate, and the total standard flux. The initial multi-group cross section includes at least the multi-group absorption cross section, the multi-group scattering cross section, and the multi-group fission neutron production cross section. The multi-group scattering cross section is generated using the energy group neutron transfer probability, and the multi-group fission neutron production cross section is generated using the fission neutron production rate.

[0043] Specifically, based on the principle of reaction rate conservation, the initial multi-group cross section is calculated according to formula (1). (1) in, In energy group G, the reaction ,area The initial multi-group cross section, In energy group G, the reaction and region The overall reaction rate Indicates the energy group G and region Total standard throughput.

[0044] The scattering matrix in the multi-group scattering cross section is statistically generated based on the neutron transfer probability of the energy group. The fission spectrum in the multi-group fission neutron production cross section is statistically generated based on the fission neutron production rate, and the statistical physical quantity includes the fission neutron production rate.

[0045] In step S5, based on the first grid homogenization region 420 and the second grid homogenization region 430, the initial multi-group cross section is iteratively optimized using the super homogenization correction factor until the super homogenization correction factor converges to obtain the multi-group cross section.

[0046] In some embodiments, step S5 includes Figure 6 Steps S51 to S510 in the process.

[0047] In step S51, the reference neutron flux is obtained using the continuous energy Monte Carlo transport simulation method based on the three-dimensional geometric model.

[0048] Specifically, using the continuous energy Monte Carlo transport simulation method, based on a three-dimensional geometric model, the region is calculated. He Nengqun Reference neutron flux in .

[0049] In step S52, based on the first grid homogenization region 420 and the second grid homogenization region 430, a multi-group neutron transport method is adopted to obtain the multi-group neutron flux through the initial multi-group cross section.

[0050] Specifically, using the multi-group neutron transport method, in the constructed first grid homogenization region 420 and second grid homogenization region 430, the neutron transport in the region is calculated. He Nengqun Multigroup neutron flux .

[0051] In step S53, the super-homogenization correction factor is calculated based on the multi-group neutron flux and the reference neutron flux.

[0052] Specifically, the super-homogenization correction factor is calculated according to formula (2): (2) in, This is a super-homogenization correction factor. For the region The reference neutron flux of energy group G, For energy group G and region neutron flux in multiple groups.

[0053] In some embodiments, the super-homogenization correction factor may include a normalization factor. When the boundary condition of the three-dimensional geometric model is a reflection boundary condition, the reference neutron flux of all regions of the three-dimensional geometric model is summed to obtain the sum of reference neutron flux; the multi-group neutron flux of all regions of the first grid homogenization region 420 and the second grid homogenization region 430 is summed to obtain the sum of multi-group neutron flux; the normalization factor is calculated based on the sum of reference neutron flux and the sum of multi-group neutron flux; when the boundary condition of the three-dimensional geometric model is other boundary conditions, the normalization factor takes a preset normalization value.

[0054] Specifically, the super-homogenization correction factor can be calculated according to formula (3): (3) in, As a normalization factor, when the boundary conditions of the three-dimensional geometric model are reflection boundary conditions, the normalization factor is calculated according to formula (4). (4) in, The sum of reference neutron fluxes represents the sum of fluxes over all regions. of Summation, The sum of neutron fluxes across multiple groups represents the sum of fluxes over all regions. of Summation is performed. When the boundary conditions of the 3D geometric model are other boundary conditions, specifically including vacuum boundary conditions, periodic boundary conditions, albedo boundary conditions, extrapolation boundary conditions, and radiation boundary conditions, the normalization factor takes a preset normalization value, which can be 1. This improves the convergence of the super-homogenization correction factor iteration, meaning that results meeting accuracy requirements can be obtained with fewer iteration steps, and further enhances the computational accuracy of multi-group cross-sectional data of the research reactor containing irradiated channels 210.

[0055] In step S54, the initial multi-group cross section is corrected using a super-homogenization correction factor to obtain the corrected initial multi-group cross section.

[0056] Specifically, the correction process can be represented by formula (5).

[0057] (5)

[0058] in, The reaction before correction using the super-homogenization correction factor ,area The multigroup cross section of energy group G, i.e., in formula (1) , The reaction after correction using the super-homogenization correction factor ,area The initial multigroup cross section of energy group G.

[0059] In step S55, the updated multi-group neutron flux is obtained based on the corrected initial multi-group cross section.

[0060] Specifically, based on the first grid homogenization region 420 and the second grid homogenization region 430, a multi-group neutron transport method is adopted to obtain the updated multi-group neutron flux through the modified initial multi-group cross section.

[0061] In step S56, the super-homogenization correction factor is updated based on the updated multi-group neutron flux and the reference neutron flux to obtain the updated super-homogenization correction factor.

[0062] Specifically, the updated multi-group neutron flux and reference neutron flux are substituted into formula (2) or (3) in step S53 to obtain the updated super-homogenization correction factor.

[0063] In step S57, it is determined whether the absolute value of the difference between the super-homogenization correction factor and the updated super-homogenization correction factor is less than a preset correction threshold.

[0064] In step S58, if the determination is yes, then the updated super-homogenization correction factor is used as the converged super-homogenization correction factor. In the current iteration, the absolute value of the difference between the super homogenization correction factor in step S53 and the updated super homogenization correction factor in step S56 is calculated. When the absolute value of the difference is less than the preset correction threshold, it indicates that the iterative optimization calculation has converged, and the updated super homogenization correction factor is used as the converged super homogenization correction factor.

[0065] In step S59, the multi-group cross section is obtained based on the converged super-homogenization correction factor.

[0066] Specifically, based on the converged super-homogenization correction factor, the multi-group cross section is calculated using formula (5).

[0067] In step S510, if the determination is negative, the updated super-homogenization correction factor is used as the super-homogenization correction factor, and the process returns to step S54.

[0068] Specifically, if the judgment in step S57 is negative, the updated super-homogenization correction factor of the current iteration is used as the super-homogenization correction factor to execute step S54 for the next iteration calculation, until the iterative optimization calculation converges.

[0069] In some embodiments, the accuracy of the generated multi-group cross-sections is verified, referring to... Figure 2 It also includes Figure 2 Steps S6 to S9 in the process.

[0070] In step S6, a multi-group neutron transport method is used to obtain a first effective multiplication factor based on the first grid homogenization region 420 and the second grid homogenization region 430. In step S7, a continuous energy Monte Carlo transport simulation method is used to obtain a second effective multiplication factor based on a three-dimensional geometric model. In step S8, the absolute value of the relative deviation between the first and second effective multiplication factors is calculated. In step S9, it is determined whether the absolute value of the relative deviation is less than a preset deviation threshold. If it is, the multi-group cross-section is determined to meet the accuracy requirements. Specifically, the preset deviation threshold can be 300 pcm, for reference... Figure 7 In the figure, the vertical axis represents the value of the effective proliferation factor, and the horizontal axis represents the number of iterations. In each iteration step of the super-homogenization correction factor iterative convergence calculation, the first effective proliferation factor based on the first grid homogenization region 420 and the second grid homogenization region 430 is calculated. The calculation results of each iteration step form a broken line, denoted as the first broken line 710. The baseline 720 represents the second effective proliferation factor calculated based on the three-dimensional geometric model (as a reference). As can be seen from the figure, with the increase of the number of iterations, the super-homogenization correction factor gradually converges. After convergence, the difference between the first broken line 710 and the baseline 720 is less than the preset deviation threshold.

[0071] In some embodiments, firstly, the power distribution of each fuel assembly is calculated based on a three-dimensional geometric model of the research reactor using a continuous energy Monte Carlo transport simulation method, and this result is used as a verification benchmark. Subsequently, the power distribution of each fuel assembly in the research reactor is recalculated using the obtained multi-group cross-section data and a three-dimensional diffusion procedure of the research reactor. The relative error of the power distribution of each fuel assembly relative to the benchmark value is calculated to verify the accuracy of the generated multi-group cross-section calculation results.

[0072] refer to Figure 8 , Figure 8 The relative error distribution (values ​​are percentages) is obtained based on the calculation of 4 groups, showing that the maximum relative error is 3.2%. In nuclear reactor physics calculations, the engineering acceptance standard for component power error is usually less than or equal to 5%, therefore the obtained multi-group cross-sections meet the accuracy requirements.

[0073] Using the reference neutron flux calculated by the continuous energy Monte Carlo transport simulation method as a reference, the super homogenization correction factor is continuously updated iteratively in the multi-group neutron transport calculation. The updated super homogenization correction factor is used to correct the multi-group cross section in the iteration until the iteration process converges. In this way, by using the super homogenization correction factor, the systematic error introduced in the process of generating the multi-group cross section can be reduced, and the accuracy of the multi-group cross section calculation can be improved.

[0074] In some embodiments, the preset working conditions include a target insertion into the irradiation channel and a target removal from the irradiation channel. Specifically, the process of obtaining the multi-group cross-sections described above is calculated under both the target insertion into the irradiation channel and target removal from the irradiation channel conditions, and the accuracy of the multi-group cross-section calculation results is verified.

[0075] An embodiment of this application also proposes a method such as Figure 9 The electronic device 800 is shown. According to... Figure 9 The electronic device 800 may include an internal communication bus 801, a processor 802, a read-only memory (ROM) 803, a random access memory (RAM) 804, and a communication port 805. When used in a personal computer, the electronic device 800 may also include a hard disk 806. The internal communication bus 801 enables data communication between components of the electronic device 800. The processor 802 can perform judgments and issue prompts. In some embodiments, the processor 802 may consist of one or more processors. The communication port 805 enables data communication between the electronic device 800 and external devices. In some embodiments, the electronic device 800 can send and receive information and data from a network through the communication port 805.

[0076] Electronic device 800 may also include different forms of program storage units and data storage units, such as hard disk 806, read-only memory (ROM) 803, and random access memory (RAM) 804, capable of storing various data files used for computer processing and / or communication, as well as possible program instructions executed by processor 802. Processor 802 executes these instructions to cause electronic device 800 to perform a multi-group cross-section homogenization correction calculation method for irradiation channels in a research reactor. The results processed by processor 802 are transmitted to user equipment via communication port 805 and displayed on the user interface.

[0077] In addition, this application also proposes a computer-readable medium storing computer program instructions, which, when executed alone or together by at least one processor of an electronic device, cause the electronic device to perform a calculation method for multi-group cross-sectional homogenization correction of irradiation channels for a research reactor.

[0078] Some aspects of this application can be executed entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. The aforementioned hardware or software may be referred to as a "data block," "module," "engine," "unit," "component," or "system." The processor may be one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DAPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, or combinations thereof. Furthermore, aspects of this application may manifest as computer products residing in one or more computer-readable media, including computer-readable program code. For example, computer-readable media may include, but are not limited to, magnetic storage devices (e.g., hard disks, floppy disks, magnetic tapes, etc.), optical discs (e.g., compressed CDs, digital multifunction DVDs, etc.), smart cards, and flash memory devices (e.g., cards, sticks, key drives, etc.).

[0079] A computer-readable medium may contain a propagated data signal containing computer program code, for example, on baseband or as part of a carrier wave. This propagated signal may take various forms, including electromagnetic, optical, and so on, or suitable combinations thereof. A computer-readable medium can be any computer-readable medium other than a computer-readable storage medium, which can be connected to an instruction execution system, apparatus, or device to enable communication, propagation, or transmission of a program for use. The program code located on the computer-readable medium can be propagated through any suitable medium, including radio, cable, fiber optic cable, radio frequency signals, or similar media, or any combination of the above media.

[0080] The basic concepts have been described above. It is clear that the above disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, various modifications, improvements, and corrections may be made to this application by those skilled in the art. Such modifications, improvements, and corrections are suggested in this application and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0081] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0082] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the present application requires more features than those mentioned. In fact, the embodiments have fewer features than all the features of the single embodiments disclosed above.

[0083] Although this application has been described with reference to specific embodiments, those skilled in the art should recognize that the above embodiments are only used to illustrate this application, and various equivalent changes or substitutions can be made without departing from the spirit of this application. Therefore, any changes or modifications to the above embodiments within the scope of the essential spirit of this application will fall within the scope of this application.

Claims

1. A calculation method for multi-group cross-section homogenization correction of an irradiation channel for a research reactor, the research reactor comprising at least one irradiation channel, a standard fuel assembly, a follower fuel assembly with control rods, a heavy water tank, and heavy water, characterized in that, The method includes the following steps: S1: Obtain the geometric and material parameters of the irradiated and non-irradiated pore regions under preset working conditions; S2: Based on the geometric parameters and the material parameters, establish a three-dimensional geometric model of the research pile using the Monte Carlo program; S3: Based on the three-dimensional geometric model, a first grid homogenization region is constructed for the irradiation channel region according to an adaptive homogenization rule, and a second grid homogenization region is constructed for the non-irradiation channel region according to a preset homogenization rule. The adaptive homogenization rule includes adaptively dividing at least one irradiation channel with adjacent geometric positions into a first grid non-homogenized region. The number of irradiation channels in the first grid non-homogenized region is adaptively adjusted according to the geometric parameters and geometric positions of the irradiation channel, and the first grid non-homogenized region is homogenized into the first grid homogenized region. The preset homogenization rule is to divide the non-irradiation channel region according to an orthogonal grid and then perform homogenization processing to form the second grid homogenized region. S4: Calculate the statistical physical quantities of the specified energy group based on the first grid homogenization region and the second grid homogenization region, and generate an initial multi-group cross section based on the statistical physical quantities; S5: Iteratively optimize the initial multi-group cross section using the super-homogenization correction factor until the super-homogenization correction factor converges to obtain the multi-group cross section; The irradiation channel region includes the heavy water tank, the heavy water, and at least one irradiation channel, while the non-irradiation channel region includes the standard fuel assembly and the follower fuel assembly with control rods.

2. The calculation method for multi-group cross-section homogenization correction of irradiation channels for research reactors as described in claim 1, characterized in that, Step S4 includes: S41: Using the continuous energy Monte Carlo transport simulation method, the statistical physical quantities are calculated based on the first grid homogenization region and the second grid homogenization region. The statistical physical quantities include the total reaction rate of each grid homogenization region and each reaction type, the total standard flux of each grid homogenization region, and the energy group neutron transfer probability of the scattering reaction. S42: Based on the principle of reaction rate conservation, the initial multi-group cross section is calculated using the statistical physical quantities. The initial multi-group cross section includes at least a multi-group absorption cross section, a multi-group scattering cross section, and a multi-group fission neutron production cross section. The multi-group scattering cross section is generated using the energy group neutron transfer probability, and the multi-group fission neutron production cross section is generated using the fission neutron production rate.

3. The calculation method for multi-group cross-section homogenization correction of irradiation channels for research reactors as described in claim 2, characterized in that, Step S5 includes: S51: Based on the aforementioned three-dimensional geometric model, the reference neutron flux is obtained using the continuous energy Monte Carlo transport simulation method; S52: Based on the first grid homogenization region and the second grid homogenization region, a multi-group neutron transport method is adopted to obtain the multi-group neutron flux through the initial multi-group cross section; S53: Calculate the super-homogenization correction factor based on the multi-group neutron flux and the reference neutron flux; S54: Use the super homogenization correction factor to correct the initial multi-group cross section to obtain the corrected initial multi-group cross section; S55: Obtain the updated multi-group neutron flux based on the corrected initial multi-group cross section; S56: Update the super homogenization correction factor according to the updated multi-group neutron flux and the reference neutron flux to obtain the updated super homogenization correction factor; S57: Determine whether the absolute value of the difference between the super homogenization correction factor and the updated super homogenization correction factor is less than a preset correction threshold; S58: If the determination is yes, then the updated super-homogenization correction factor is used as the converged super-homogenization correction factor. S59: The multi-group cross section is obtained based on the converged super-homogenization correction factor.

4. The calculation method for multi-group cross-section homogenization correction of irradiation channels for research reactors as described in claim 3, characterized in that, Step S5 also includes: S510: If the determination is negative, use the updated super-homogenization correction factor as the super-homogenization correction factor, and return to execute step S54.

5. The calculation method for multi-group cross-section homogenization correction of irradiation channels for research reactors as described in claim 4, characterized in that, The super-homogenization correction factor includes a normalization factor, wherein: When the boundary condition of the three-dimensional geometric model is a reflection boundary condition, the reference neutron flux of all regions of the three-dimensional geometric model is summed to obtain the sum of reference neutron flux; the multi-group neutron flux of all regions of the first grid homogenization region and the second grid homogenization region is summed to obtain the sum of multi-group neutron flux; the normalization factor is calculated based on the sum of reference neutron flux and the sum of multi-group neutron flux. When the boundary conditions of the three-dimensional geometric model are other boundary conditions, the normalization factor takes a preset normalization value.

6. The calculation method for multi-group cross-section homogenization correction of irradiation channels for research reactors as described in claim 1, characterized in that, Constructing a first grid homogenization region for the irradiated channel region according to an adaptive homogenization rule includes: At least one of the irradiation channels that are geometrically adjacent is adaptively divided into a first grid non-uniform region, wherein the number of irradiation channels in the first grid non-uniform region is adaptively adjusted according to the geometric parameters and geometric positions of the irradiation channels, and the first grid non-uniform region includes the heavy water tank and the heavy water. The non-uniformed region of the first grid is uniformized into a uniform region of the first grid.

7. The calculation method for multi-group cross-section homogenization correction of irradiation channels for research reactors as described in claim 6, characterized in that, The volume and material composition of the first mesh homogenized region in the three-dimensional geometric model are the same as the volume and material composition of the corresponding first mesh non-homogenized region in the three-dimensional geometric model, and the volume and material composition of the second mesh homogenized region in the three-dimensional geometric model are the same as the volume and material composition of the corresponding second mesh non-homogenized region in the three-dimensional geometric model.

8. The calculation method for multi-group cross-section homogenization correction of irradiation channels for research reactors as described in claim 3, characterized in that, It also includes the following steps: S6: Using the multi-group neutron transport method, a first effective multiplication factor is obtained based on the first grid homogenization region and the second grid homogenization region; S7: Using the continuous energy Monte Carlo transport simulation method, a second effective proliferation factor based on the three-dimensional geometric model is obtained; S8: Calculate the absolute value of the relative deviation between the first effective proliferation factor and the second effective proliferation factor; S9: Determine whether the absolute value of the relative deviation is less than a preset deviation threshold. If the determination is yes, then determine that the multi-group cross-section meets the accuracy requirements.

9. The calculation method for multi-group cross-section homogenization correction of irradiation channels for research reactors as described in claim 1, characterized in that, The preset operating conditions include the target insertion into the irradiation channel and the target removal from the irradiation channel.

10. An electronic device, characterized in that, include: Memory is used to store instructions that can be executed by the processor; as well as A processor for executing the instructions to implement the method as described in any one of claims 1-9.

11. A computer storage medium storing computer program code, characterized in that, The computer program code, when executed by a processor, implements the method as described in any one of claims 1-9.

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