A method and system for optimizing the structure of an isotope target of a high-temperature gas-cooled reactor and improving economic benefits

Abstract

The application relates to the technical field of nuclear reactor isotope irradiation production, and discloses a high-temperature gas-cooled reactor isotope target structure optimization and economic benefit improvement method and system, wherein the method comprises the following steps: classifying target pieces according to the thermal neutron absorption cross sections of the target pieces; performing structure optimization design on the target pieces; using a Monte Carlo program to calculate the relative change rate Delta Phi of the average thermal neutron fluence rate of the target piece core under different candidate cladding material conditions, and sorting the priority of the cladding materials according to the size of |Delta Phi|, wherein the cladding material with the smallest |Delta Phi| is the optimal one; establishing a target piece irradiation economic benefit comprehensive evaluation model, performing economic calculation on the obtained target piece scheme according to the model, and comparing the target piece schemes to select the optimal target piece scheme; and the application has the advantages of realizing the maximization of isotope yield and the optimization of comprehensive economic benefits under the premise of ensuring thermal safety by establishing a cross section classification-structure optimization-cladding material matching-normalized economic benefit evaluation technical chain.

Description

Technical Field

[0001] This invention belongs to the field of nuclear reactor isotope irradiation production technology. Specifically, it relates to a target structure optimization method and system that classifies target materials based on their thermal neutron absorption cross-section, uses thin-walled ring structures or large-diameter solid structures for differentiated optimization, and simultaneously matches low-absorption cladding materials and establishes a normalized economic benefit evaluation model. It is particularly suitable for maximizing isotope yield and optimizing irradiation economic benefits in the side reflector irradiation channels of pebble bed type high-temperature gas-cooled reactors. Background Technology

[0002] The pebble bed high-temperature gas-cooled reactor is an advanced reactor type with fourth-generation nuclear power characteristics. It employs fully ceramic-coated spherical fuel elements, helium coolant, and a graphite moderation structure, possessing inherent safety. Its core active zone consists of tens of thousands of randomly stacked spherical fuel elements, surrounded by a graphite side reflector layer. Within the side reflector layer, there are pre-set control rod channels, absorber sphere channels, cold helium gas channels, and dedicated or reserved channels for isotope irradiation, providing an ideal neutron field environment for isotope production: the thermal neutron fluence rate peaks in this region, and due to the effect of the reflector layer, the neutron energy spectrum is relatively soft, which is conducive to utilizing (n, γ) or (n, α) reactions to efficiently produce a variety of radioactive isotopes.

[0003] In existing technologies, the thermal neutron absorption cross-sections of different isotope targets vary greatly. For example, 6 Li has a thermal neutron absorption cross section of up to 940 Å (n, α), while 176 The (n, γ) thermal neutron absorption cross section of Yb is only about 2.85b. 130 The thermal neutron absorption cross section of TeO2 is only about 0.29b. This difference in cross section leads to the following main technical challenges in the design of existing target components: 1. High absorption cross-section targets – the self-shielding effect leads to extremely low target utilization. For 6 Strong absorbing targets such as LiAlO2 exhibit a high thermal neutron capture probability in their cores, resulting in the absorption of thermal neutrons almost immediately at the target's outer surface. Consequently, the thermal neutron flux rate within the target core decays exponentially, creating a spatial self-shielding effect. This makes it difficult for the target material inside the core to effectively participate in nuclear reactions, leading to significant waste of target material. Unconverted target material after irradiation becomes difficult-to-dispose-of radioactive waste. To address this, existing technologies, such as Chinese patent application CN202210990303.7, disclose a multi-layered target with self-shielding capabilities. While attempting to solve the shielding effect by using a multi-layered target tube structure, this invention does not yet propose a thin-walled annular optimization scheme and a technical approach for synergistic matching of cladding materials for strong absorbing targets in high-temperature gas-cooled reactors.

[0004] 2. Low Absorption Cross-Section Targets – Good Neutron Penetration but Limited Single-Bulk Load. For weakly absorbing targets such as TeO2 and Yb2O3, thermal neutrons can penetrate the entire target almost uniformly, but due to the low absorption probability, the number of nuclear reactions per unit volume is low, resulting in a lower yield for the same irradiation time. If the target diameter is too small, the fuel load will be insufficient, limiting the total yield. Therefore, existing research reactors typically employ irradiation spheres, finned structures, or rod bundles to increase the contact area between neutrons and fuel. These designs focus more on cooling and uniformity, rather than on maximizing the economic optimization of single-bulk load by utilizing large-size solid structures during mass production.

[0005] 3. The influence of neutron absorption by cladding materials is generally overlooked. Traditional target design primarily considers structural strength and corrosion resistance when selecting cladding materials, neglecting their significant impact on the neutron fluence of the target core. Studies show that, under the same geometric conditions, using Inconel cladding reduces the average thermal neutron fluence of the target core by approximately 22% compared to cladding with zirconium alloys (such as Zirlo alloys). Existing literature does not incorporate the neutron matching of cladding materials into the relevant considerations for target optimization design.

[0006] 4. Lack of differentiated target structure optimization methods. Existing target designs mostly adopt uniform solid cylinders or simple rod bundle structures, without differentiated optimization based on the cross-sectional characteristics of the target material. For high-absorption cross-section targets, thin-walled annular designs are not used to reduce the self-shielding effect; for low-absorption cross-section targets, large-diameter solid designs are not used to increase the charge capacity.

[0007] 5. Lack of a comprehensive economic evaluation system. Existing technologies, such as the invention patent with Chinese patent application number 202310916052.2, disclose a method for optimizing the energy spectrum of scarce isotope irradiation production based on layered targets. It proposes that by performing critical calculations on targets of different radii, the radial energy spectrum self-shielding effect of targets with different radii can be quantified based on the "total energy spectrum value" to improve production efficiency. However, it lacks a normalized economic benefit evaluation method that includes multiple factors such as target production costs, waste disposal costs, and operating costs, making it difficult to guide the engineering selection of target structures. Furthermore, common optimization methods in existing technologies mainly focus on energy spectrum optimization or self-shielding effect suppression, enrichment determination, and output calculation, failing to form a complete closed-loop optimization system encompassing "section classification - structural design - cladding matching - economic evaluation." Summary of the Invention

[0008] To address the aforementioned problems in existing technologies, this invention provides a method and system for optimizing the structure and improving the economic benefits of isotope targets in high-temperature gas-cooled reactors. By classifying targets, designing differentiated geometries, screening neutron matching properties of cladding materials, and establishing a normalized economic benefit evaluation index, the invention maximizes isotope yield, minimizes target waste, and optimizes overall economic benefits.

[0009] The technical solution of the present invention is as follows: In a first aspect, the present invention provides a method for optimizing the structure and improving the economic benefits of isotope targets in high-temperature gas-cooled reactors, comprising the following steps: Step 1: Classification of target thermal neutron absorption cross section (σ_thermal); Targets are classified according to their neutron absorption cross-section into the following three categories: High absorption cross-section target (Class H): σ_thermal ≥ 100b. Typical example: 6 LiAlO2 (used for) 3 H production), boron-containing compounds, etc. These targets have extremely large thermal neutron absorption cross sections, severe self-shielding effects, and extremely low thermal neutron fluence inside the core.

[0010] Low absorption cross-section targets (L-type): σ_thermal < 10b. Typical example: TeO2 (used for...) 131 I production), Yb2O3 (used in) 177 (Lu production), etc. These types of targets have extremely small thermal neutron absorption cross sections, good neutron penetration, and uniform thermal neutron flux distribution inside and outside the core.

[0011] Medium-absorption cross-section target (Class M): 10b ≤ σ_thermal < 100b. Typical example: 59 Co (used for) 60 Co production, etc. Step 2: Optimization of the differentiated structure of the target component; Based on the target types identified in the first step, corresponding structural optimization designs are performed for different types of targets. The specific optimization designs are as follows: (1) H-type target - thin-walled ring structure optimization: The target core is fabricated as a hollow cylindrical ring. The wall thickness δ can be determined based on the neutron mean free path λ. For Class H targets, the wall thickness is typically 1~2λ, but δ ≤ 0.2R_out is recommended, where R_out is the outer diameter of the target. It should be noted that the neutron mean free path (λ) is the average statistical distance a neutron travels between two consecutive nuclear reactions (including elastic scattering, inelastic scattering, and absorption) in the target medium. It is a physical quantity characterizing the average spatial distance a neutron travels before interacting with the medium (including scattering and absorption). It is the theoretical basis for determining the wall thickness δ.

[0012] Initially, we can quantitatively set δ=(1~2) / Σ_t, where Σ_t is the total macroscopic cross section of the target material.

[0013] To enhance target cooling and reduce thermal stress, a central through-hole air gap or a low-density inert medium (such as helium) can be provided within the ring. The thin-walled annular structure of the target effectively reduces the spatial self-shielding effect of the core, allowing more internal target material to be effectively irradiated.

[0014] (2) Optimization of L-type target parts - coarse diameter solid structure: The target core adopts a solid cylinder or a large-diameter multi-bar bundle structure, with its outer diameter close to the inner diameter of the irradiation channel (leaving room for the cladding layer and cooling gaps) to maximize the target loading volume. The large-diameter solid design allows for a larger loading volume of target material, producing more isotopes within the same irradiation time. If the heat generation rate during irradiation is high, axial cooling channels can be incorporated within the core, or a multi-bar bundle distribution can be used to improve cooling efficiency.

[0015] (3) M-type target components – no optimization or comprehensive structural optimization required: M-type targets may not require optimization, or the target core may be optimized by referring to the engineering rules for the boundary values ​​of high-absorption cross-section targets and low-absorption cross-section targets, taking into account the advantages and disadvantages of thin-walled ring structures and large-diameter solid structures. The specific settings can be selected according to the actual situation.

[0016] Meanwhile, for some M-type targets (such as...) 59 For Co targets (σ≈37.2b), in scenarios with high heat release per unit volume (decay heat) during irradiation, a thick-walled annular structure can be used to ensure thermal safety while also considering neutron economy. Its wall thickness δ_M is determined according to the following neutron physics rules: δ_M=(2~3) / Σ_t=(2~3)λ That is, the wall thickness is taken as 2 to 3 neutron mean free path (λ).

[0017] The physical basis for this thickness setting is that the absorption cross-section of M-type targets is one order of magnitude smaller than that of H-type targets, resulting in a greater penetration depth of thermal neutrons within the target material. If the (1~2)λ thin-wall design of H-type targets is adopted, the excessively thin wall thickness will cause a large number of thermal neutrons to directly penetrate the core without being absorbed, resulting in a waste of neutron resources. However, if (2~3)λ is used, approximately 86.5% (1-e) of the thermal neutrons can be absorbed. - ³) to 95.0% (1-e) - The incident thermal neutrons (²) are effectively absorbed by the core.

[0018] Step 3: Neutron matching screening of the cladding material; For targets after the first step of classification and the second step of structural optimization design, the relative change rate ΔΦ of the average thermal neutron fluence of the target core under different candidate cladding materials (including Zirlo alloy, Zr-4 alloy, Inconel, stainless steel 316L, etc.) is calculated using a Monte Carlo program (e.g., RMC program). The cladding materials are prioritized according to the magnitude of |ΔΦ|, and the cladding material that minimizes |ΔΦ| (i.e., minimizes the loss of measurable neutron fluence) is selected as the optimal choice for the corresponding target. Other cladding materials are considered as alternatives. For H-type targets, Zirlo or Zr-4 alloy is recommended as the preferred material. For L-type targets, Zirlo or Zr-4 alloy is also preferred, but due to their smaller thermal neutron absorption cross-section, stainless steel or Inconel can also be selected based on engineering requirements such as structural strength and cost. For M-type targets, Zr-4 alloy is selected as the cladding material. The purpose of this step is to minimize the absorption of thermal neutrons by the cladding material.

[0019] Step 4: Establishment of a comprehensive evaluation model for the economic benefits of target irradiation; A comprehensive evaluation model for the economic benefits of target irradiation is established. Based on this model, the economic calculation of the target scheme obtained in step S3 is performed, specifically as follows: The normalized economic efficiency index is defined as follows: NEI=P isotope / (C target +C waste +C operation ) In the formula, NEI represents the normalized economic efficiency index; P isotope The value of isotopes produced by a single batch of irradiation (in yuan) is calculated by coupling burnup using a Monte Carlo program, taking into account the target geometry, local neutron flux distribution, and the number of product atoms and market unit price after irradiation time. C target This represents the manufacturing cost of a single target (in yuan), which includes the cost of target raw materials, core manufacturing, and shell processing, etc. The specific cost is determined based on the actual situation. C waste The cost (in yuan) for radioactive waste disposal after irradiation of a single target is related to the volume of unconverted target material and the level of radioactivity, and is determined based on the actual situation. C operation This represents the irradiation operating cost (in yuan), which includes the cost of irradiation channel occupancy time, etc., and the specific cost will be determined based on the actual situation. The normalized economic efficiency index (NEI) is used to calculate the economic viability of all target designs obtained in step three, and the NEI is compared. The target design with the highest NEI is selected as the optimal target design. Then, the normalized economic efficiency index is used to calculate the economic viability of the initial target designs, and their NEI is compared with the NEI of the selected optimal target design. The NEI of the optimal target design must be greater than that of the initial target design. If it is less, the process returns to step two and repeats the process sequentially to reselect.

[0020] Step 5: Engineering verification and iterative optimization; The optimal target design selected in step four (i.e., the selected target structure, dimensional parameters, and cladding material) is used as the optimization result. If multiple NEI-similar designs exist, other engineering parameters (such as the difficulty of post-irradiation processing and the impact of target heat rate on core temperature) can be further compared. This optimization result is then fed back to the target sample fabrication process, and safety verification is performed through reactor physics-thermal coupling procedures to ensure the target meets thermal safety limits. If the verification fails to meet the safety threshold, the process returns to step two and repeats the process to reselect the target.

[0021] In a second aspect, the present invention provides a system for optimizing the structure and improving the economic benefits of isotope targets in high-temperature gas-cooled reactors, which is used to execute the aforementioned method for optimizing the structure and improving the economic benefits of isotope targets in high-temperature gas-cooled reactors. The system specifically includes: Irradiation target classification module: used to classify targets according to their neutron absorption cross section, dividing them into H / L / M categories; Differentiated geometry optimization module: Built-in standard optimization templates such as H-type thin-walled ring, L-type large-diameter solid, and M-type comprehensive structure, automatically generate target CAD model and dimensional parameters based on the input target outer diameter and channel size, so as to perform corresponding structural optimization design on the target output by the irradiated target classification module; Cladding material selection module: Based on the neutron fluence rate variation parameter ΔΦ, it automatically simulates and calculates and outputs a ranking of recommended cladding materials to recommend the optimal cladding material for the target after optimization by the differential geometry optimization module; Economic benefit assessment module: It has a built-in NEI calculation model that can automatically extract parameters such as output, manufacturing cost, waste disposal cost, and operating cost to perform economic calculations on target solutions and compare multiple solutions.

[0022] Decision output module: Used to output the optimal result and feed this result back to the target sample trial production for safety verification, ensuring that the target meets the thermal safety limit requirements.

[0023] The present invention has the following beneficial effects: 1. This invention proposes a target structure differentiation and optimization strategy based on thermal neutron absorption cross-section, filling the theoretical gap in differentiated optimization design of targets for pebble-bed high-temperature gas-cooled reactors. Existing technologies mainly focus on suppressing self-shielding effects, flattening the total neutron energy spectrum value, or utilizing the space of multilayer target tubes, without establishing differentiated design rules based on reaction cross-section thresholds as engineering standards. This invention classifies targets into three categories—H, L, and M—based on thermal neutron absorption cross-section, and matches thin-walled annular and large-diameter solid structures to H-type and L-type targets respectively, accurately matching neutron physical properties and significantly improving neutron economy.

[0024] 2. This invention establishes a collaborative optimization method that combines the neutron matching properties of the cladding material, quantifies the ΔΦ index for engineering optimization, and solves the deficiency of existing technologies that neglect the influence of the cladding material. In existing literature, the cladding material is mainly used as a component of the target structure support and cooling channels, without being collaboratively optimized from the perspective of neutron absorption matching. This invention, by systematically comparing the effects of different cladding materials on the core neutron fluence, deeply couples structural optimization with cladding material optimization. Calculations show that Zirlo cladding can increase the thermal neutron fluence of the high-absorber target core by approximately 23% compared to Inconel cladding.

[0025] 3. This invention establishes a comprehensive evaluation model for the economic benefits of target irradiation, constructing an optimization system encompassing cross-section classification, structural design, cladding matching, and economic evaluation. This overcomes the limitations of existing technologies that focus on single energy spectrum optimization or output calculation. Existing literature primarily focuses on energy spectrum optimization, self-shielding effect suppression, or enrichment determination, but none of these incorporate target production costs, waste disposal fees, operating costs, and output value into a unified evaluation system or establish a closed-loop optimization process. This invention incorporates multiple economic indicators into target design decisions, filling a gap in the application of engineering economics in the field of high-temperature gas-cooled reactor isotope irradiation.

[0026] 4. This invention forms a closed-loop method and process of "Monte Carlo program fine modeling + differentiated structural design + NEI economic comparison + safety verification feedback", which has cross-reactor type promotion value and can be used as a toolkit to promote the target design improvement of other reactor types with side reflector irradiation channels (such as research reactors and high flux reactors).

[0027] 5. The calculations involved in this invention only use Monte Carlo programs and conventional thermal analysis software, both of which are mature commercial or open-source tools in the nuclear engineering field, requiring no specific software development. Differentiated geometric models can be modeled using standard CAD design libraries. Thin-walled annular targets can be formed by powder metallurgy pressure molding or precision centrifugal casting. Coarse-diameter solid targets with an outer diameter close to the pore diameter can be mass-produced through bar extrusion or sintering processes. Cladding materials can be encapsulated through standard welding processes. Manufacturers can complete the manufacturing of new targets without major equipment modifications. Optimizing the target outer diameter to match the original irradiation pores does not change the reactor core structure or neutron shielding conditions, resulting in extremely low modification risk and good compatibility. The input-output ratio is significant, based on the annual production of HTR-PM. 3 According to calculations, the thin-walled annular + Zirlo cladding scheme, compared to the solid Inconel cladding scheme, increases yield by approximately 22%, reduces waste by 51%, and generates a net economic benefit of over 15 million yuan per year. The large-diameter TeO2 target scheme can... 131 Output increased by approximately 60%, and overall economic benefits increased by approximately 97%. Attached Figure Description

[0028] Figure 1 A flowchart illustrating the method for optimizing the structure and improving the economic benefits of isotope targets for high-temperature gas-cooled reactors provided by this invention. Figure 2 For different encapsulation cases 6 The distribution of average thermal neutron fluence rate in the LiAlO2 core. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0030] Example: Please refer to Figure 1 This embodiment combines the production within the irradiation channels of the side reflector in the pebble bed high-temperature gas-cooled reactor demonstration project (HTR-PM). 3 H used 6 LiAlO2 target (high absorption cross-section target, σ_thermal≈940b) and production 131 The method for optimizing the structure and improving the economic benefits of isotope targets for high-temperature gas-cooled reactors provided by this invention is illustrated in detail using a TeO2 target (low absorption cross-section target, σ_thermal≈0.29b).

[0031] I. High Absorption Cross-Section Target ( 6 Differentiated optimization of LiAlO2; Step 1: Classification of target thermal neutron absorption cross-section; 6 The LiAlO2 core has an effective σ_thermal≈940b, belonging to the H-class target.

[0032] Step 2: Optimization of the differentiated structure of the target component; Initial design: solid cylindrical structure (radius 1.0cm, length 50cm), encased in Inconel (thickness 0.05cm).

[0033] Optimized design scheme: thin-walled annular structure (outer diameter 2.0cm matching the channel, inner diameter 1.6cm, wall thickness δ=0.2cm, δ / R_out=0.1), core with high enrichment. 6 A LiAlO2 ceramic ring with a central through-hole filled with helium to reduce thermal stress and provide space for gas expansion. The cladding material was simultaneously optimized to a Zirlo alloy.

[0034] Step 3: Neutron matching screening of the cladding material; Calculate solid using RMC separately 6 The core-average thermal neutron fluence of LiAlO2 targets under three conditions: no cladding, Inconel cladding, and Zirlo cladding. Calculation data show (under different cladding conditions) 6 The average thermal neutron fluence rate at the LiAlO2 core is shown below. Figure 2 The average thermal neutron fluence at the target core location was 4.25 × 10⁻⁶ under the three conditions. 13 n / (cm 2 ·s), 3.28×10 13 n / (cm 2 ·s), 4.21×10 13 n / (cm 2 Compared to the unclad target, using Inconel as the cladding material significantly reduces the average thermal neutron fluence at the target core, by approximately 22.8%; while using Zirlo alloy as the cladding material results in a smaller change in the average thermal neutron fluence, with a decrease of only about 1.0%. Furthermore, the average thermal neutron fluence at the core of the target clad with Inconel is approximately 77.9% of that under Zirlo alloy cladding. This indicates that Inconel has a stronger absorption and shielding effect on thermal neutrons, significantly reducing the thermal neutron fluence entering the target core region, which is detrimental to the neutron economy of the target. In contrast, Zirlo alloy has a weaker influence on the thermal neutron field, thus offering an advantage in the selection of target cladding materials.

[0035] Step 4: Establishment of a comprehensive evaluation model for the economic benefits of target irradiation; (1) Output calculation: The RMC fuel consumption calculation is used to calculate the output after 420 days of irradiation: Original solid + Inconel encapsulation solution 3 H yield approximately 15.6g; optimized thin-walled ring + Zirlo solution. 3 H production increased to 20.1g.

[0036] (2) Cost and waste estimation: The original plan was not converted. 6 Li accounts for approximately 60%, resulting in large waste volume and high treatment costs; the thin-walled ring scheme has not been converted. 6 The proportion of lithium has been reduced to about 25%, directly reducing the amount of waste by about 50% and the cost of waste treatment by about 55%.

[0037] (3) NEI index calculation: The original scheme NEI≈0.65; after optimization, NEI increased to about 1.28, an increase of about 97%.

[0038] Step 5: Engineering verification and iterative feedback; The final optimization parameters of the target ( 6 LiAlO2 (outer diameter 20mm, inner diameter 16mm, Zirlo cladding thickness 0.5mm) was submitted to the target manufacturing department for thermal safety verification. After the verification was passed, it was incorporated into the production plan.

[0039] II. Differentiated optimization of low-absorption cross-section targets (TeO2); Step 1: Classification of target thermal neutron absorption cross-section The TeO2 core has an effective σ_thermal≈0.29b, which belongs to the L-class target.

[0040] Step 2: Optimization of the differentiated structure of the target component; Initial design: a small-diameter solid cylinder (radius 0.5cm) with a small filling capacity.

[0041] Optimized design scheme: outer diameter increased to 2.0cm (maximum allowable), core is a solid column formed by pressing natural TeO2 powder, and shell is 316L stainless steel.

[0042] Step 3: Neutron matching screening of the cladding material; TeO2 targets belong to the L category, and the cladding absorption cross section has a relatively small impact. Conventional 316L stainless steel is selected to meet the structural strength and cooling requirements.

[0043] Step 4: Establishment of a comprehensive evaluation model for the economic benefits of target irradiation; Original plan 131 I output ≈ 300 Ci; after optimization, output increases to approximately 510 Ci, an increase of approximately 70%. The NEI index assessment improves by approximately 96%.

[0044] Step 5: Engineering Feedback Optimization The final optimized parameters of the target (TeO2: outer diameter 2.0cm, cladding 316L stainless steel) were submitted to the target manufacturing department and thermal safety verification was carried out. After the verification was passed, it was incorporated into the production plan.

[0045] As can be seen from the above implementation examples, the present invention can achieve structural optimization and economic benefit improvement of isotope irradiation targets for high-temperature gas-cooled reactors, and has important engineering application value.

[0046] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for optimizing the structure and improving the economic benefits of isotope targets in high-temperature gas-cooled reactors, characterized in that: Includes the following steps: Step S1: Classify the targets according to their thermal neutron absorption cross-section; Step S2: Based on the target types classified in Step S1, perform corresponding structural optimization design for different types of targets; Step S3: For the target after classification in Step S1 and structural optimization design in Step S2, use the Monte Carlo program to calculate the relative change rate ΔΦ of the average thermal neutron fluence of the target core under different candidate cladding materials. Sort the cladding materials according to the priority of |ΔΦ|, and select the cladding material with the smallest |ΔΦ| as the best choice. Step S4: Establish a comprehensive evaluation model for the economic benefits of target irradiation. Based on this model, perform economic calculations on all target schemes obtained in Step S3 and compare them to select the optimal target scheme.

2. The method for optimizing the structure and improving the economic benefits of isotope targets in high-temperature gas-cooled reactors according to claim 1, characterized in that: The classification method in step S1 includes the following steps: The targets are classified into high absorption cross-section targets, low absorption cross-section targets, and medium absorption cross-section targets; The thermal neutron absorption cross section of the high absorption cross section target is greater than or equal to 100 μb; The thermal neutron absorption cross section of the low absorption cross section target is less than 10b; The thermal neutron absorption cross section of the target with medium absorption cross section is greater than or equal to 10b but less than 100b.

3. The method for optimizing the structure and improving the economic benefits of isotope targets in high-temperature gas-cooled reactors according to claim 2, characterized in that: The structural optimization design in step S2 includes the following steps: For targets with high absorption cross-sections, a thin-walled ring structure is used for optimization. For targets with low absorption cross-sections, a large-diameter solid structure is used for optimization. For targets with medium absorption cross-sections, no optimization is required.

4. The method for optimizing the structure and improving the economic benefits of isotope targets in high-temperature gas-cooled reactors according to claim 3, characterized in that: The optimization of the thin-walled annular structure includes the following steps: The target core is made into a hollow cylindrical ring, and the wall thickness is determined based on the mean free path of the neutron.

5. The method for optimizing the structure and improving the economic benefits of isotope targets in high-temperature gas-cooled reactors according to claim 3, characterized in that: The optimization of the coarse-diameter solid structure includes the following steps: The target core adopts a solid cylindrical structure, and only a cladding layer and a cooling gap are reserved between the outer diameter of the target core and the inner diameter of the irradiation channel.

6. The method for optimizing the structure and improving the economic benefits of isotope targets in high-temperature gas-cooled reactors according to claim 1, characterized in that: The model building method in step S4 includes the following steps: The normalized economic efficiency index is defined as follows: IN=P isotope / (C target +C waste +C operation ) In the formula, NEI represents the normalized economic efficiency index, and P... isotope This represents the isotope production value per batch produced by irradiation, C target C represents the manufacturing cost of a single target component. waste C represents the cost of radioactive waste disposal after irradiation of a single target. operation This indicates the operating cost of irradiation; The normalized economic benefit index is used to calculate the economic efficiency of all target schemes obtained in step S3 and compare the NEI. The target scheme with the largest NEI is selected as the optimal target scheme.

7. The method for optimizing the structure and improving the economic benefits of isotope targets in high-temperature gas-cooled reactors according to claim 6, characterized in that: Step S4 further includes the following steps: The normalized economic efficiency index (NEI) is used to calculate the economic efficiency of the initial target scheme, and its NEI is compared with the NEI of the selected optimal target scheme. The NEI of the optimal target scheme must be greater than the NEI of the initial target scheme. If it is less, return to step S2 and repeat the process to select a new target scheme.

8. The method for optimizing the structure and improving the economic benefits of isotope targets in high-temperature gas-cooled reactors according to claim 7, characterized in that: The method further includes the following steps: Step S5: The optimal target design selected in step S4 is used as the optimization result. This result is fed back to the target sample trial production for safety verification to ensure that the target meets the thermal safety limit requirements. If the verification does not meet the safety threshold, the process returns to step S2 and is repeated to select a new target.

9. A system for optimizing the structure and improving the economic benefits of isotope targets in high-temperature gas-cooled reactors, characterized in that: The system is used to perform the method as described in any one of claims 1 to 8; The system includes: Irradiation target classification module: used to classify targets according to their neutron absorption cross section; Differentiated geometry optimization module: used to perform corresponding structural optimization design on the targets classified and output by the irradiated target classification module; Cladding Material Selection Module: Used to recommend the optimal cladding material for the target after it has been optimized by the Differentiated Geometry Optimization Module; Economic benefit assessment module: used to perform economic calculations on target design schemes and to compare multiple schemes.

10. A system for optimizing the structure and improving the economic benefits of isotope targets in high-temperature gas-cooled reactors, characterized in that: The system also includes: Decision output module: Used to output the optimal result and feed this result back to the target sample trial production for safety verification, ensuring that the target meets the thermal safety limit requirements.

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