Design method and system for pressurized water reactor heavy nuclide formant distribution

Abstract

The invention belongs to the technical field of nuclear power, and discloses a pressurized water reactor weight nuclide formant distribution design method and system, comprising hundreds of groups of novel energy group structures, using the energy group structures and combining a subgroup method to further divide subgroups according to the cross section size on the basis of hundreds of groups, the calculation precision equivalent to that of tens of thousands of superfine groups is achieved through hundreds of groups; and selecting a proper energy group structure so as to realize accurate description of formant distribution. The energy group structure provided by the invention can accurately describe formants, and when the energy group structure provided by the invention is used for subgroup resonance calculation, the calculation precision equivalent to that of tens of thousands of superfine groups can be realized on the scale of hundreds of groups, and the calculation efficiency is greatly improved. According to the energy group structure provided by the invention, the effective resonance cross section of common resonance nuclides of the pressurized water reactor can be accurately calculated, the resonance peak distribution and the resonance interference phenomenon can be accurately described through subgroup resonance calculation, and compared with a traditional resonance interference processing method, the calculation precision is higher.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power, and in particular relates to a design method and system for the distribution of resonance peaks of heavy nuclides in a pressurized water reactor. Background Art

[0002] The development of nuclear power technology has gradually increased the requirements for high-fidelity simulation technology of reactors. Reactor numerical calculations include coupling research between multiple disciplines and multiple physical fields such as neutronics, thermal hydraulics and fuel performance analysis. Among them, neutronic calculations provide information such as effective proliferation factors, neutron flux density and power distribution for reactor analysis by accurately solving the Boltzmann transport equation, which is a key link in high-fidelity calculations of reactors.

[0003] Neutron calculations require the integration and differentiation of neutron flux density in multiple dimensions such as energy, angle, space and time. It is extremely difficult to directly solve the neutron transport equation analytically for the complex geometric structure and material composition of the actual reactor. The commonly used neutron transport equation calculation methods currently include the Monte Carlo method and the deterministic method. The Monte Carlo method simulates the behavior of neutrons in the reactor through random particles, and invests a large number of particles for multiple iterative calculations to obtain numerical information such as neutron flux density with statistical deviations that meet the accuracy requirements. The Monte Carlo method is currently the most accurate core physics calculation method, but a large number of statistical processes make the overall calculation efficiency extremely low, which cannot meet the efficiency requirements of large-scale component or core-level scientific research calculations. The deterministic method is the calculation method currently used by mainstream commercial programs in the world. This method introduces a series of approximations to perform discrete calculations on dimensions such as energy, angle, space and time. For steady-state calculations of reactors, the influence of the time dimension can be ignored. Transport calculation methods represented by characteristic line method, discrete ordinate method, collision probability method, etc. can realize discrete calculations on spatial and angular dimensions. For the energy dimension, the deterministic method realizes the discretization of energy through grouping approximation. Neutrons are divided into different energy groups according to their energy size, and the equivalent average cross section of each energy group is calculated by continuous energy cross section integral, as shown in formula (1):

[0004]

[0005] Where: σ is the microscopic cross section; x is the reaction channel type; is the neutron angular flux density; Ω is the direction of neutron movement; r is the spatial position of the neutron; E is the energy; g is the energy group number.

[0006] Among the materials commonly used in pressurized water reactors, the cross sections of most nuclides vary relatively slowly with energy. In a specific energy range, the cross section value can be considered to remain constant with energy, and the multi-group cross section obtained by merging equation (1) is independent of the energy spectrum. This part of the multi-group cross section can be directly stored in the multi-group database, and the actual calculation can be interpolated according to the temperature. However, for some heavy nuclides, such as 235 U or 238 U, etc., neutrons will form metastable composite nuclei after hitting the nuclei of these nuclides. When the incident neutron is at a specific energy point, the probability of the neutron reacting with the nucleus will increase sharply, while the probability of the reaction deviating from this energy range will show a sharp downward trend. Therefore, the neutron reaction cross section will fluctuate violently within a specific energy range, such as Figure 1 As shown in Figure 1. This phenomenon is called the resonance phenomenon in reactor physics. The nuclides and energy groups that have the resonance phenomenon are called resonant nuclides and resonance groups, and each cross-section peak is called a resonance peak. For pressurized water reactor problems, the resonance phenomenon usually occurs in the range of 1 to 104 eV. Due to the huge cross-section value, a large number of neutrons near the resonance peak are absorbed, so the neutron energy spectrum drops sharply in this energy range. This effect, which is similar to neutron shielding, is called the resonance self-screening effect. In actual reactors, due to the complexity of materials and geometry, the resonance self-screening effect is also very complex. The effective resonance cross section calculated by formula (1) has a strong correlation with the energy spectrum. Therefore, the resonance cross section cannot be prefabricated and stored in a multi-group database, but needs to be calculated according to the actual problem. Resonance self-screening calculation, or resonance calculation for short. In order to accurately describe the resonance peak distribution in the resonance energy range, the resonance cross section curve must be accurately discretized according to the energy size, which usually requires tens of thousands or even hundreds of thousands of energy group structures, resulting in low calculation efficiency and difficulty in application in actual reactor physics analysis calculations.

[0007] The technical problems brought about by existing technologies in industrial applications mainly include the following aspects:

[0008] 1. Low computational efficiency: In order to accurately describe the resonance peak distribution of the resonance energy segment, the existing technology must discretize the resonance cross-section curve very finely, usually requiring the use of tens of thousands or even hundreds of thousands of energy group structures. This high-precision discretization leads to a sharp increase in the amount of calculation, which significantly reduces the computational efficiency. In particular, when dealing with complex reactor physics problems, the calculation time is too long and it is difficult to meet the timeliness requirements in engineering applications.

[0009] 2. Real-time reactor physics analysis cannot be achieved: Due to the complexity of the resonance self-screening effect and the characteristics of the cross-section value fluctuating violently with energy, the existing technology cannot pre-fabricate the resonance cross section and store it in a multi-group database, but needs to re-calculate the resonance self-screening according to the actual problem each time. This process is not only time-consuming, but also increases the computational complexity, making it difficult to achieve real-time reactor physics analysis and simulation, which brings inconvenience to the operation and decision support in actual engineering.

[0010] 3. High resource consumption: High-precision energy group discretization not only increases the computing time, but also places higher requirements on computing resources, including greater storage requirements and stronger computing power. This will lead to higher hardware costs and energy consumption in practical applications, reducing the economy and sustainability of computing.

[0011] 4. Poor engineering applicability: Due to the above problems, the application of existing technologies in dealing with actual reactor physics analysis is limited, especially under complex geometric and material conditions. The resonance calculation process is too cumbersome and time-consuming, and the results cannot be obtained quickly, which in turn affects the efficiency and effectiveness of key industrial applications such as reactor design, operation optimization and safety analysis.

[0012] These technical problems pose great challenges to reactor physics analysis and calculations in industrial applications. There is an urgent need to solve the problems of low computing efficiency and real-time analysis to meet the modern nuclear industry's demand for efficient and accurate simulation technology. Summary of the invention

[0013] In view of the problems existing in the prior art, the present invention provides a design method and system for the resonance peak distribution of heavy nuclides in a pressurized water reactor.

[0014] The present invention is implemented as follows: a design method for the resonance peak distribution of heavy nuclides in a pressurized water reactor includes a novel energy group structure of hundreds of groups. The energy group structure is used in combination with a subgroup method to further divide subgroups based on the cross-sectional size on the basis of hundreds of groups, and the calculation accuracy equivalent to that of tens of thousands of ultrafine groups is achieved through hundreds of groups; a suitable energy group structure is selected to achieve a more accurate description of the resonance peak distribution.

[0015] Furthermore, the energy group structure is based on the SHEM-361 energy group structure, the resonance energy range is adjusted, the resonance group structure is remade, and the number of resonance energy groups and energy group boundaries are redefined and allocated. A new energy group structure is formulated that can accurately describe the distribution of resonance peaks of heavy nuclides in pressurized water reactors.

[0016] Furthermore, in order to accurately calculate the effective resonance cross section of the strong resonance peak, further energy discretization is adopted in the energy range of 22.5~100eV, and the resonance peak is divided and discretized into multiple resonance groups; the energy group discretization is mainly concentrated in the energy range of the strong resonance peak of each resonant nuclide, and the original resonance group is divided by the equal le width principle, and the resonance peak distribution of uranium-238 is described in detail; the change law of the resonance cross section with the background cross section after discretization is similar to that in the indistinguishable resonance zone, and the second-level discretization of the resonance group can be accurately completed through 2~3 subgroups; on the other hand, the SHEM-361 energy group structure is extremely finely divided below 22.5eV, and the temperature interpolation is directly used to calculate the cross section in this energy range.

[0017] Furthermore, the energy group structure optimization mainly follows two principles: one is to fully describe the distribution of the resonance peaks of each nuclide; the other is to retain the interface for resonance group and group calculations.

[0018] Furthermore, the overall resonance energy range is selected as 1.8554-9118 eV, and the SHEM-361 energy group structure has 242 groups in this range, and the optimized energy group structure has 289 groups in this range. The fast group and thermal group of the energy group structure still use the original SHEM-361 energy group structure, which are 56 groups and 63 groups respectively, so the total number of energy groups is 408 groups.

[0019] Another object of the present invention is to provide a precise description system of the resonance peak distribution of heavy nuclides in a pressurized water reactor using the design method of the resonance peak distribution of heavy nuclides in a pressurized water reactor, comprising:

[0020] Subgroup division module, which is used to use the new energy group structure of hundreds of groups, combined with the subgroup method, to further divide subgroups according to the cross-sectional size on the basis of hundreds of groups, and achieve the calculation accuracy equivalent to that of tens of thousands of ultrafine groups through hundreds of groups;

[0021] The energy group structure selection module is used to select a suitable energy group structure to achieve a more accurate description of the resonance peak distribution.

[0022] Another object of the present invention is to provide a computer device, the computer device includes a memory and a processor, the memory stores a computer program, when the computer program is executed by the processor, the processor executes the steps of the design method of the resonance peak distribution of heavy nuclides in a pressurized water reactor.

[0023] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to execute the steps of the method for designing the resonance peak distribution of heavy nuclides in a pressurized water reactor.

[0024] Another object of the present invention is to provide an information data processing terminal, which is used to implement the accurate description system of the resonance peak distribution of heavy nuclides in pressurized water reactors.

[0025] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0026] First, in view of the technical problems existing in the above-mentioned prior art, some creative technical effects are brought about after solving the problems. The specific description is as follows:

[0027] 1) Improved computational efficiency: Resonance calculations need to be based on an accurate energy group structure. The energy group structure proposed in the present invention can accurately describe the resonance peak. Using the energy group structure proposed in the present invention to perform subgroup resonance calculations can achieve computational accuracy comparable to that of tens of thousands of ultrafine groups on a scale of hundreds of groups, greatly improving computational efficiency.

[0028] 2) Accurate calculation accuracy: The energy group structure proposed in the present invention can accurately calculate the effective resonance cross section of common resonant nuclides in pressurized water reactors, and can accurately describe the resonance peak distribution and resonance interference phenomenon through subgroup resonance calculation, which has higher calculation accuracy than traditional resonance interference processing methods.

[0029] 3) Wide application scope: The energy group structure proposed in the present invention is not only applicable to subgroup resonance calculations, but also to other methods such as equivalent theoretical methods and embedded resonance calculation methods. It also sets energy group boundaries for common multi-group or small-group structures to facilitate energy group merging, and can be applied to reactor physics analysis calculations in various scenarios.

[0030] second,

[0031] The design method and system for the resonance peak distribution of heavy nuclides in a pressurized water reactor proposed in the present invention significantly improve the calculation efficiency while ensuring the calculation accuracy by optimizing the energy group structure and combining the subgroup method, and has the following significant technical effects and advantages:

[0032] 1) High-precision description of the resonance peak distribution of heavy nuclides in pressurized water reactors:

[0033] First, the present invention adopts a new energy group structure of hundreds of groups. Compared with the traditional structure of dozens of groups, the new energy group structure divides the energy range more finely and can accurately describe the resonance peak distribution of each nuclide, especially the strong resonance peak area.

[0034] Secondly, based on hundreds of groups of new energy group structures, a strategy of further discretization using subgroup method is proposed. This strategy further divides subgroups according to the cross-sectional size, thereby further refining the energy range, making the resonance peak distribution clearer and the calculation accuracy higher.

[0035] 2) Ability to efficiently calculate the effective resonance cross section of heavy nuclides in pressurized water reactors:

[0036] Firstly, the present invention further discretizes the new energy group structure through the subgroup method, and can achieve calculation accuracy equivalent to that of tens of thousands of ultrafine groups on the scale of hundreds of groups, which greatly reduces the amount of calculation and improves the calculation efficiency.

[0037] Secondly, the present invention can avoid the additional processing of the resonance self-screening effect in the traditional method. The fine energy group structure and subgroup method can accurately describe the resonance peak distribution and its interference phenomenon, which can effectively avoid the calculation of the resonance self-screening effect and further improve the calculation efficiency.

[0038] 3) The resonance cross section calculation of heavy nuclides in pressurized water reactors has a wide range of applications:

[0039] First, the present invention is applicable to a variety of resonance self-screening calculation methods. The energy group structure proposed by the present invention is not only applicable to subgroup resonance calculation, but also can be applied to other methods such as equivalent theory method, embedded resonance calculation method, etc., and has wide applicability.

[0040] Secondly, the energy group structure proposed by the present invention is easy to merge energy groups. The energy group boundaries of common multi-group or small group structures are set to facilitate energy group merging, which can be applied to reactor physics analysis and calculation in various scenarios.

[0041] Third, as auxiliary evidence of the inventiveness of the claims of the present invention, it is also reflected in the following important aspects:

[0042] (1) The expected benefits and commercial value of the technical solution of the present invention after transformation are:

[0043] 1) Improving reactor design efficiency: The present invention can be used in reactor design, safety analysis, performance optimization, etc. to improve calculation efficiency, shorten design cycle, and reduce design cost.

[0044] 2) Improving reactor operation safety: The present invention can be used in reactor operation monitoring, accident analysis, safety assessment, etc. to improve calculation accuracy and improve reactor operation safety.

[0045] 3) Promote the development of nuclear power technology: The present invention provides key technical support for high-fidelity simulation of reactors, which will promote the development of nuclear power technology to a higher level.

[0046] (2) The technical solution of the present invention fills the technical gap in the industry at home and abroad:

[0047] 1) Make up for technical shortcomings: The energy group structure optimization method and subgroup calculation method proposed in the present invention make up for the technical shortcomings in the accurate description of the resonance peak distribution of heavy nuclides in pressurized water reactors at home and abroad.

[0048] 2) Solving technical problems: The present invention effectively solves the problems of low efficiency and insufficient precision of traditional effective resonant self-screen cross-section calculation methods, and provides strong support for high-fidelity simulation of reactors.

[0049] 3) Breaking through technical bottlenecks: The present invention breaks through the technical bottleneck of low computational efficiency that is inevitably caused by the traditional fine energy group structure, and achieves a balance between high precision and high efficiency.

[0050] Fourth, the technical effects of the design method of the resonance peak distribution of heavy nuclides in pressurized water reactors in industrial applications mainly include the following aspects:

[0051] 1. Significantly improve the calculation accuracy: By introducing a new energy group structure of hundreds of groups and combining it with the subgroup method for detailed energy discretization, this method can achieve the same calculation accuracy as the traditional ultrafine group structure of tens of thousands of groups while maintaining the calculation efficiency. In particular, in the treatment of the energy segment near the resonance peak, the resonance peak distribution of heavy nuclides such as uranium-235 and uranium-238 is accurately described, making the calculation results closer to the actual situation and ensuring the accuracy of reactor physics analysis.

[0052] 2. Optimize computational efficiency: Compared with the traditional ultrafine group method, this method greatly reduces the time and resource consumption required for calculation by optimizing the energy group structure and reducing the number of subgroups. In particular, when accurately calculating the effective resonance cross section of the strong resonance peak, by refining the energy discretization and using the equal width principle for segmentation, an efficient calculation process is achieved, which significantly improves the overall computational efficiency. This is of great significance for industrial applications that require frequent reactor physics simulations.

[0053] 3. Enhance the flexibility of reactor design and safety analysis: In the process of optimizing the energy group structure, this method follows the principle of accurately describing the resonance peak distribution while retaining the resonance group and group calculation interface, making this method highly adaptable. It can flexibly respond to the reactor physics calculation requirements under different nuclides, geometric shapes and material conditions, thereby providing reliable data support in reactor design, optimization and safety analysis, and improving the flexibility and effectiveness of design and analysis.

[0054] 4. Reduced reliance on computing resources: By reducing reliance on ultrafine group structures and optimizing the computing process, this method reduces the requirements for computing resources, including storage requirements and computing power. For large-scale simulation computing tasks in industrial applications, this method can reduce hardware investment and operating costs while ensuring accuracy, thereby improving the economy and sustainability of computing.

[0055] 5. Promote technological progress in the nuclear energy industry: By providing efficient and accurate calculation tools, this method helps to improve the overall level of reactor physics calculations in the nuclear energy industry. This not only speeds up the process of new reactor design and nuclear fuel development, but also enhances the safety monitoring and emergency response capabilities in nuclear reactor operation, promoting technological progress and safety improvement in the nuclear energy industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0057] Figure 1 The embodiment of the present invention provides 235 U and 238 U total cross section changing trend with energy;

[0058] Figure 2 is a diagram of a single gate cell structure provided by an embodiment of the present invention;

[0059] Figure 3 is a graph of calculation results of a single cell problem provided by an embodiment of the present invention;

[0060] Figure 4 This is the VERA 1B example provided by the embodiment of the present invention. 238 U Relative deviation of absorption cross section;

[0061] Figure 5 This is the VERA 1B example provided by the embodiment of the present invention. 235 Relative deviation of U cross section: (a) absorption cross section; (b) fission fraction. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0063] Industrial application example: Optimized design of nuclear fuel assemblies

[0064] Background: The design and optimization of nuclear fuel assemblies are crucial links in the operation of nuclear power plants. The performance of fuel assemblies directly affects the efficiency, safety and fuel utilization of the reactor. Traditional design methods rely on the calculation structure of tens of thousands of ultra-fine groups to accurately describe the resonance peak distribution of nuclides in specific energy ranges. However, this method is computationally intensive and time-consuming, and it is difficult to meet the needs of rapid iterative design.

[0065] By adopting this design method for the distribution of resonance peaks of heavy nuclides in pressurized water reactors, designers can significantly improve the computational efficiency and accuracy in the optimization design of nuclear fuel assemblies. This method uses a new energy group structure of hundreds of groups, combined with a subgroup method, to carefully discretize the energy of the resonance peaks of heavy nuclides such as uranium-235 and uranium-238, ensuring that the changes in the neutron reaction cross section can be accurately simulated during the operation of the reactor.

[0066] In actual applications, designers used this method to quickly evaluate the impact of different fuel rod arrangements, cladding materials, and coolant conditions on reactor performance. Through efficient calculation processes, designers were able to complete multiple rounds of design evaluation and optimization in a short period of time. Ultimately, this method helped the design team improve fuel utilization and reduce the production cost of fuel assemblies while ensuring reactor safety.

[0067] Technical effect:

[0068] 1. Shortened design cycle: Compared with traditional methods, the design cycle of fuel assemblies is shortened by about 50%, allowing new fuel assemblies to enter the experimental and application stages more quickly.

[0069] 2. Improved fuel utilization: Through accurate description of resonance peak distribution, the optimized fuel assembly shows higher fuel utilization in actual operation and reduces nuclear fuel consumption.

[0070] 3. Computational resource saving: This method significantly reduces the demand for computing resources, reduces hardware costs, and saves computing time and energy consumption.

[0071] 4. Enhanced decision support: Accurate simulation results provide strong data support for design decisions, improving the feasibility and safety of design solutions.

[0072] This embodiment demonstrates the practical application value of this method in the design of nuclear fuel assemblies, and provides strong support for the efficient operation and economy of nuclear power plants.

[0073] In view of the problems existing in the prior art, the present invention provides a design method and system for the resonance peak distribution of heavy nuclides in a pressurized water reactor. The present invention is described in detail below in conjunction with the accompanying drawings.

[0074] The design method of the resonance peak distribution of heavy nuclides in pressurized water reactors achieves a high-precision description of the distribution of the resonance peaks of nuclides by optimizing the energy group structure. First, the method introduces a new energy group structure of hundreds of groups based on the traditional energy group structure, divides the energy range in a more detailed way, and combines the subgroup method to further refine the energy discreteness on the basis of hundreds of groups, so as to achieve a calculation accuracy equivalent to that of tens of thousands of ultra-fine groups. This detailed energy group division enables the distribution characteristics of the resonance peaks to be more accurately reflected in the calculation process, especially in the resonance energy segment where the neutron cross section changes dramatically.

[0075] Secondly, this method is based on the SHEM-361 energy group structure, and redefines and distributes the energy group boundaries and group numbers within the resonance energy range. By adjusting the resonance energy range and remaking the resonance group structure, the energy group structure can more accurately describe the resonance peak distribution of heavy nuclides in pressurized water reactors. This adjustment not only optimizes the calculation efficiency, but also ensures the accurate description of the resonance phenomenon in different energy segments, especially the strong resonance peak distribution of heavy nuclides such as uranium-235 and uranium-238 at specific energy points.

[0076] When accurately calculating the effective resonance cross section of the strong resonance peak, this method takes further energy discretization for the energy range of 22.5 to 100 eV, and divides the energy range where the resonance peak is located into multiple resonance groups using the equal width principle. This refined energy group division, especially the detailed description of the uranium-238 resonance peak, makes the law of the change of the resonance cross section with the background cross section more accurate, so that the second-level discretization of the resonance group can be achieved with a smaller number of subgroups, which significantly improves the calculation accuracy. At the same time, this method makes extremely detailed divisions in the energy range below 22.5 eV, and calculates the cross section by temperature interpolation, further enhancing the ability to describe the distribution of the resonance peak.

[0077] In addition, this method mainly follows two important principles when optimizing the energy group structure: first, it is necessary to fully describe the distribution of the resonance peaks of each nuclide to ensure the accurate reflection of the resonance phenomenon in the calculation; second, it is necessary to retain the interface for the resonance group and group calculation, so that the energy group structure can flexibly adapt to different calculation requirements in complex reactor physics calculations. This optimization method enables the energy group structure to have both high-precision description capabilities and retain the flexibility of calculation efficiency.

[0078] Finally, this method refined the overall resonance energy range and optimized the SHEM-361 energy group structure in the range of 1.8554 to 9118 eV from 242 groups to 289 groups. On the basis of keeping the fast group and hot group structure unchanged, the total number of energy groups increased to 408 groups by increasing the number of resonance groups. This optimization enables the energy group structure to more accurately reflect the resonance peak distribution while maintaining the original accuracy, and significantly improves the calculation efficiency, which is suitable for accurate simulation and calculation in pressurized water reactor physics analysis.

[0079] Compared with the WLUP-69 or HELIOS-47 energy group structure, a variety of more refined energy group structures have also been proposed internationally, such as the WLUP-172 and SHEM-281 energy group structures and the more refined SHEM-361 energy group structure. Under the refined energy group structure, the resonance cross section distribution within each resonance group is relatively flat, and the phenomenon of overlapping resonance peaks of different nuclides is greatly reduced. Based on the above method, the energy group structure proposed in the present invention is based on the SHEM-361 energy group structure, adjusts the resonance energy range, remakes the resonance group structure, and redefines and allocates the number of resonance energy groups and energy group boundaries, and formulates a new energy group structure that can accurately describe the distribution of resonance peaks of heavy nuclides in pressurized water reactors.

[0080] The energy range of the resonance group in the traditional multi-group database represented by the WLUP-69 group is 4 to 9118 eV. For typical UO2 fuel, this energy range can better cover the distribution of the main resonance peaks. However, 242 Other actinide nuclides such as Pu still have extremely strong resonance peaks in the energy range close to the thermal group. The present invention refers to the energy group structure of the HELIOS-47 group database and extends the lower limit of the resonance energy range to 1.8554 eV. At the same time, since the resonance interference effect is mainly caused by 238 The resonance peak of U affects the cross section calculation of other resonance nuclides, so the energy group structure needs to be adjusted. 238 The resonance peak distribution of U is described in detail. Table 1 gives the main resonance peak distribution energy points of typical actinide nuclides. 238 U has strong resonance peaks distributed throughout the entire resonance energy range, while the resonance peaks of other actinide nuclides are mainly distributed in the range below 100eV, so the resonance interference effect in the low resonance energy range is stronger. The new energy group structure fully considers the influence of the above resonance peaks.

[0081] Table 1 Distribution of main resonance peaks of typical actinide nuclides

[0082]

[0083]

[0084] The present invention reproduces the SHEM-361 energy group structure in the energy range of 1.8554 to 100.6 eV. On the one hand, in order to accurately calculate the effective resonance cross section of the strong resonance peak, the present invention adopts further energy discretization for the energy range of 22.5 to 100 eV, and divides the resonance peak into multiple resonance groups. The energy group discretization is mainly concentrated in the energy interval of the strong resonance peak of each resonant nuclide, and the original resonance group is divided by the equal width principle, and the resonance peak distribution of uranium-238 is described in detail. The variation law of the resonance cross section with the background cross section after discretization is similar to that of the indistinguishable resonance zone, and the second-level discretization of the resonance group can be accurately completed by 2 to 3 subgroups. On the other hand, the SHEM-361 energy group structure is extremely finely divided below 22.5 eV, and the temperature interpolation is directly used to calculate the cross section in this energy range. The present invention expands the lower limit of the subgroup resonance calculation to 1.8554 eV, and the original fine energy group boundary of this energy range can be merged. For the energy around 2.7eV and 6.7eV, since the resonance peaks are very significant and the interference effect is strong, a detailed structure is selected for this part of the energy group, so that the alignment can be completed through the detailed energy group. 238 Calculation of the resonance cross section of nuclides such as U. Compared with the original SHEM-361 resonance group, the energy group distribution of the remade energy group structure between 1.855 and 100.6 eV is shown in Table 2:

[0085] Table 21. Reproduction energy group structure in the energy range of 8554 to 100.6 eV

[0086]

[0087]

[0088] On the whole, the optimization of energy group structure mainly follows two principles: one is to fully describe the distribution of the resonance peaks of each nuclide; the other is to retain the interface for the calculation of the resonance group and the group. The energy boundary of the energy group should include the energy boundaries of the resonance groups in the common multi-group database, such as WLUP-69, HELIOS-47 energy group structure, etc. By introducing subgroup resonance calculations in the energy range of 1.8554-22.5eV, the number of energy groups in this range is reduced from 124 to 81. The resonance peaks in the energy range of 22.5-100.6eV are encrypted, and the number of energy groups in this range is increased from 46 to 136. The present invention selects the overall resonance energy range as 1.8554-9118eV. The SHEM-361 energy group structure has a total of 242 groups within this range, and the optimized energy group structure has 289 groups within this range. The fast group and thermal group of the energy group structure still use the original SHEM-361 energy group structure, which are 56 groups and 63 groups respectively, so the total number of energy groups is 408 groups.

[0089] The energy group boundaries of the energy group structure proposed by the present invention within the energy range of 1.855 to 100 eV are shown in the following table:

[0090] Table 3 Energy group boundaries of energy group structures in the energy range of 1.855 to 100 eV

[0091]

[0092]

[0093]

[0094] Example:

[0095] The implementation case selected a single-cell problem with the structure shown in the figure. The geometric structure of the problem is as follows Figure 4 As shown, the fuel rod, cladding radius and grid element half-side length are 0.412, 0.476 and 0.6325 cm respectively. The cladding material is natural zirconium, the moderator is cold water, and the calculation temperature is 300K. Four calculation problems are selected, and the fuel region of each problem has only one nuclide, namely uranium-235, uranium-238, plutonium-239, and plutonium-241. The energy group structure proposed in the present invention is used to calculate the resonance cross section.

[0096] Using the multi-group database produced by the present invention, subgroup resonance calculation is performed on the above problem. First, Figure 5 The calculation deviation of the fuel rod absorption cross section calculated by using the database proposed in this invention compared with the benchmark solution is given. 238 Taking U as an example, compared with the benchmark solution, the maximum, average and root mean square deviations of the calculated absorption cross sections in all resonance groups are -2.14%, -0.01% and 0.43% respectively. Large deviations only occur in very few energy groups and have little impact on the overall situation. The calculation deviations of the vast majority of other energy groups are within ±0.5%, which has a high calculation accuracy. 238 Compared with U, 235 U. 239 Pu and 241 Pu has higher calculation accuracy, and the cross-section root mean square deviation is 0.27%, 0.28% and 0.26% respectively. Since the energy group structure proposed by the present invention can accurately describe the distribution of the resonance peak, the resonance phenomenon in each group is greatly weakened, and the subgroup resonance method can obtain accurate calculation results.

[0097] An application embodiment of the present invention provides a computer device, which includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor executes the steps of a design method for heavy nuclide resonance peak distribution in a pressurized water reactor.

[0098] An application embodiment of the present invention provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the steps of a method for designing a resonance peak distribution of heavy nuclides in a pressurized water reactor.

[0099] The application embodiment of the present invention provides an information data processing terminal, which is used to realize an accurate description system of the resonance peak distribution of heavy nuclides in a pressurized water reactor.

[0100] The design method and system for the resonance peak distribution of heavy nuclides in pressurized water reactors proposed in the present invention have wide feasibility and effectiveness in practical applications, can effectively improve the accuracy and efficiency of reactor physics analysis and calculation, provide strong support for reactor design, safety analysis, performance optimization, etc., and have important technical value and application prospects. The details are as follows:

[0101] 1) Reactor core design:

[0102] The present invention can be used to accurately calculate the resonance cross section of each nuclide in reactor fuel, analyze the resonance peak distribution and resonance interference phenomenon, provide reliable calculation data for reactor fuel assembly design, optimize the geometric structure, material selection and other parameters of the fuel assembly, and improve the overall performance and safety of the reactor.

[0103] 2) Reactor control scheme optimization

[0104] The present invention can be used to accurately calculate the resonance cross section in the control rod material, which is beneficial to accurately analyze the influence of the control rod on the neutron flux and the effective multiplication factor, optimize the control rod lifting scheme, and improve the control efficiency and safety of the control rod.

[0105] 3) Reactor safety analysis

[0106] The present invention can be used to accurately calculate the critical state of the reactor, analyze the influence of the resonance peak on the critical characteristics, provide reliable calculation data for reactor safety analysis, evaluate the critical safety margin of the reactor, and ensure the safety of reactor operation.

[0107] 4) Nuclear reactor accident analysis

[0108] The present invention can be used to analyze the change of neutron flux in reactor accidents, evaluate the influence of resonance peaks on accident consequences, provide reliable calculation data for accident analysis, and provide a scientific basis for accident handling.

[0109] 5) Reactor performance optimization

[0110] The invention can be used to accurately calculate the resonance cross section of each nuclide during the reactor burnup process, analyze the influence of the resonance peak on the burnup characteristics, provide reliable calculation data for reactor burnup calculation, optimize the operating parameters of the reactor, and improve the economy and safety of the reactor.

[0111] 6) Reactor operating power distribution analysis

[0112] The present invention can be used to analyze reactor power distribution, evaluate the influence of resonance peak on power distribution, provide reliable calculation data for power distribution optimization during reactor operation, optimize reactor operation parameters, and improve reactor operation efficiency and safety.

[0113] 7) Nuclear data research:

[0114] The present invention can be used to evaluate the resonance cross section data of each nuclide in the nuclear database, analyze the description accuracy of the resonance peak, provide reliable calculation data for nuclear data evaluation, and improve the quality and reliability of the nuclear database. It can also be used to generate new nuclear data, especially fine resonance cross section data, to provide new tools and methods for nuclear data research. 3. Evidence of the effects related to the embodiments. The embodiments of the present invention have achieved some positive effects during the research and development or use process, and do have great advantages over the prior art. The following content is described in conjunction with the data, charts, etc. of the experimental process.

[0115] In order to verify the advantages of the present invention, the VERA core physics benchmark problems 1A to 1D released by the Ork Ridge National Laboratory in the United States were selected for calculation verification. In these cases, the fuel enrichment is unified at 3.1%, but there are differences in fuel temperature, moderator temperature and density, so that the accuracy of the single gate element calculation of the present invention under various working conditions can be verified. In addition to the present invention, two energy group structures, the traditional WLUP-69 energy group structure and the ultrafine group 34000 group energy group structure, were also used for comparison. The resonance cross section calculations of the three methods all adopt the subgroup method, and the transport methods all adopt the characteristic line method to ensure the consistency of the calculation conditions. Table 1 shows the effective proliferation factor k for each case. eff The results show that the four cases k of the present invention eff The calculation deviation is controlled within the range of ±50pcm, which is similar to the calculation accuracy of the ultrafine group method, but the number of energy groups required by the present invention is much smaller than that of the ultrafine group. The calculation deviation of the WLUP-69 energy group structure is generally more than 200pcm.

[0116]

[0117] Further exploring the VERA 1B case, Figure 4 and Figure 5 The resonant nuclides in the fuel are shown respectively 238 The calculated average absorption cross section of U, and 235Calculation results and deviation analysis of the absorption cross section and fission fraction of U. The analysis results show that at most energy levels, the errors between the resonance cross section calculated based on the present invention and the ultrafine group technology are limited to less than 1%, while the calculation results of the traditional WLUP-69 group energy group structure are not accurate in this regard. According to the data provided in Table 2, the present invention shows excellent calculation accuracy in the calculation of the deviation of the nuclide resonance group cross section of the VERA1B and 1C cases, whether it is the maximum deviation, average deviation or root mean square deviation. This result shows that the program of the present invention can maintain a high degree of accuracy in the calculation of different gate element conditions and cross section types.

[0118] In general, compared with the traditional 69-group structure, the present invention has higher calculation accuracy. At the same time, the present invention uses the 408-group energy group structure to achieve a calculation accuracy equivalent to that of the ultrafine group 34,000 groups, and the calculation efficiency is greatly improved.

[0120] Figure 4 VERA 1B Example 238 U Absorption cross section relative deviation

[0122] Figure 5 VERA 1B Example 235 U cross section relative deviation: (a) absorption cross section; (b) fission share It should be noted that the embodiments of the present invention can be implemented by hardware, software or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated design hardware. A person of ordinary skill in the art will understand that the above-mentioned devices and methods can be implemented using computer executable instructions and / or contained in a processor control code, such as a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. Such code is provided on a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The device and its modules of the present invention can be implemented by hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, and can also be implemented by a combination of the above-mentioned hardware circuits and software, such as firmware.

[0123] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the field of the present invention within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for designing the resonance peak distribution of heavy nuclides in a pressurized water reactor, characterized in that: Through the new energy group structure of hundreds of groups, combined with the subgroup method, the resonance peaks of heavy nuclides such as uranium-235 and uranium-238 are carefully discretized. In this way, during the nuclear fuel assembly design process, multiple rounds of design scheme evaluation and optimization can be completed in a relatively short period of time, thereby improving fuel utilization. A new energy group structure including hundreds of groups is used. Based on hundreds of groups, the subgroup method is combined to further divide the subgroups according to the cross-sectional size, and the calculation accuracy of hundreds of groups is comparable to that of tens of thousands of ultrafine groups. Select a suitable energy group structure to achieve a more accurate description of the resonance peak distribution.

2. The design method for the resonance peak distribution of heavy nuclides in a pressurized water reactor according to claim 1, characterized in that: The energy group structure is based on the SHEM-361 energy group structure, adjusts the resonance energy range, remakes the resonance group structure, redefines and allocates the number of resonance energy groups and energy group boundaries, and formulates a new energy group structure that can accurately describe the distribution of resonance peaks of heavy nuclides in pressurized water reactors.

3. The design method for the resonance peak distribution of heavy nuclides in a pressurized water reactor according to claim 1, characterized in that: In order to accurately calculate the effective resonance cross section of the strong resonance peak, further energy discretization is adopted in the energy range of 22.5~100eV, and the resonance peak is divided and discretized into multiple resonance groups; the energy group discretization is mainly concentrated in the energy range of the strong resonance peak of each resonant nuclide, and the original resonance group is divided by the equal le width principle, and the resonance peak distribution of uranium-238 is described in detail; the change law of the resonance cross section with the background cross section after discretization is similar to that in the indistinguishable resonance zone, and the second-level discretization of the resonance group can be accurately completed through 2~3 subgroups; on the other hand, the SHEM-361 energy group structure is extremely finely divided below 22.5eV, and the temperature interpolation is directly used to calculate the cross section in this energy range.

4. The design method for the resonance peak distribution of heavy nuclides in a pressurized water reactor according to claim 1, characterized in that: The optimization of energy group structure mainly follows two principles: one is to fully describe the distribution of resonance peaks of each nuclide; the other is to retain the interface for resonance group and group calculation.

5. The design method for the resonance peak distribution of heavy nuclides in a pressurized water reactor according to claim 1, characterized in that: The overall resonance energy range is selected as 1.8554-9118 eV. The SHEM-361 energy group structure has 242 groups in this range, and the optimized energy group structure has 289 groups in this range. The fast group and thermal group of the energy group structure still use the original SHEM-361 energy group structure, which are 56 groups and 63 groups respectively, so the total number of energy groups is 408 groups.

6. A system for accurately describing the resonance peak distribution of heavy nuclides in a pressurized water reactor using the design method for the resonance peak distribution of heavy nuclides in a pressurized water reactor as claimed in any one of claims 1 to 5, characterized in that: include: Subgroup division module, which is used to use the new energy group structure of hundreds of groups, combined with the subgroup method, to further divide subgroups according to the cross-sectional size on the basis of hundreds of groups, and achieve the calculation accuracy equivalent to that of tens of thousands of ultrafine groups through hundreds of groups; The energy group structure selection module is used to select a suitable energy group structure to achieve a more accurate description of the resonance peak distribution.

7. A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method for designing the resonance peak distribution of heavy nuclides in a pressurized water reactor as claimed in any one of claims 1 to 5.

8. A computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to execute the steps of the method for designing the resonance peak distribution of heavy nuclides in a pressurized water reactor as claimed in any one of claims 1 to 5.

9. An information data processing terminal, used for realizing the accurate description system of the resonance peak distribution of heavy nuclides in a pressurized water reactor as claimed in claim 6.

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