Mo-99 Irradiation Production and Energy Spectrum Optimization Method Based on Reactor Activation
By optimizing the energy spectrum through a three-dimensional neutronics and fuel consumption coupling model, selectively filtering nuclides to increase Mo-99 production, the bottleneck of production and the risk of impurities in Mo-99 production were solved, and efficient Mo-99 production was achieved.
Patent Information
- Application Number
- CN202610288419.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-10
- Publication Date
- 2026-06-02
AI Technical Summary
Current Mo-99 production faces bottlenecks in yield and the risk of introducing radioactive impurities, which cannot be effectively addressed by existing energy dispersive spectroscopy (EDS) filtering technologies, and also increase post-processing costs and complexity.
By using a three-dimensional high-fidelity neutronics coupled with a burnup model for refined energy spectrum analysis, key energy regions are identified and nuclides are selectively filtered. The energy spectrum is optimized to increase Mo-99 yield and reduce impurity risk. Filter materials are used to selectively absorb during irradiation, avoiding additional post-processing steps.
This approach increases Mo-99 production and reduces the risk of radioactive impurities without adding post-processing steps, enabling industrial supply of Mo-99 for various reactor platforms.
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Figure CN122136051A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a technology in the field of nuclear engineering, specifically a method for producing Mo-99 by reactor activation irradiation and optimizing the energy spectrum. Background Technology
[0002] Mo-99 is a key parent nuclide in technetium-99m (Tc-99m) generator systems, and clinical diagnostic examinations such as single-photon emission computed tomography (SPECT) are highly sensitive to its supply stability. Mo-99 production currently relies primarily on fission, but this involves uranium targets and fission product reprocessing, presenting challenges such as significant nuclear proliferation and waste source terms. Summary of the Invention
[0003] This invention is aimed at 98 Mo(n,γ) 99 The production bottleneck caused by the small reaction cross section of Mo and the mismatch between the neutron energy spectrum of the irradiation channel and the target neutron energy spectrum, as well as the fact that existing energy spectrum filtering technology can only screen out single nuclides, making it extremely difficult to obtain and costly, while the addition of filter materials actually introduces impurities into the production system, requiring additional impurity removal processes, increasing post-processing costs and having the drawback of losses, are addressed by proposing a method for Mo-99 irradiation production and energy spectrum optimization based on reactor activation. Through integrated energy spectrum optimization, including refined energy spectrum analysis, filtering of nuclides, determination of the optimal energy spectrum control scheme, and impurity assessment, Mo-99 production can be increased without adding additional post-processing processes, and the risk of radioactive impurity introduction can be reduced. This method is applicable to the industrial and regional supply of Mo-99 for various reactor platforms, including commercial reactors and research reactors.
[0004] This invention is achieved through the following technical solution:
[0005] This invention relates to a method for Mo-99 irradiation production and energy spectrum optimization based on reactor activation. By establishing a three-dimensional high-fidelity neutronics and burnup coupling model of the reactor and irradiation channels, the full-energy neutron region is divided into covered areas. The energy range of MeV includes 238 energy regions, including the thermal neutron energy region, the resonance energy region, and the fast neutron energy region. By perturbing the flux of a single energy region, the importance index and importance curve of Mo-99 yield to the flux change of each energy region are obtained, thereby identifying the positive and negative important performance regions. For the negative important performance regions, filter nuclides are screened from the absorption cross-section characteristics of natural isotopes, and burnup calculations are performed at different doping levels to obtain the yield gain. Then, the isotope scheme is converted into a natural abundance material scheme to determine the optimal filter material and loading method.
[0006] The aforementioned three-dimensional high-fidelity neutronics and burnup coupling model refers to: establishing a three-dimensional core-channel-target model based on the actual geometry and material composition of the reactor, using neutron transport calculations to obtain the flux and reaction rate of each energy region, and iteratively coupling it with burnup / decay calculations within a discrete time step to obtain a calculation model for nuclide evolution and Mo-99 cumulative yield during irradiation.
[0007] The reactor activation method refers to the following: Mo-98 enriched target is placed in the reactor neutron flux field for continuous irradiation, so that Mo-98 is converted into Mo-99 through (n,γ) reaction, and after irradiation, Mo-99 product that meets the loading requirements of medical generator is obtained by cooling and conventional alkaline dissolution-solid-liquid separation / purification process.
[0008] The perturbation refers to: completing a three-dimensional transport-burnup coupling calculation under baseline operating conditions to obtain the baseline neutron flux in 238 energy regions. After adjusting the baseline Mo-99 terminal output Y, only the flux in energy region i is perturbed by single-energy region flux, i.e., according to... Scaling is performed while keeping the flux in other energy regions constant; the perturbed Mo-99 terminal yield Y' is obtained by repeated burnup calculations under the same irradiation strategy, target and material arrangement conditions.
[0009] The irradiation strategy is continuous irradiation for 5–12 days, preferably about 7 days under CANDU reactor conditions or about 9 days under JRR3 research reactor conditions.
[0010] The importance indicators ,in: , respectively, represent the neutron flux in energy region i before and after the perturbation.
[0011] The aforementioned importance curve refers to a curve with the lower bound of the energy region as the horizontal axis and the importance index as the horizontal axis. The curve plotted on the ordinate is used to characterize the contribution of flux changes in each energy region to the final yield of Mo-99.
[0012] The target is a molybdenum trioxide (MoO3) target enriched with Mo-98 or a composite target containing MoO3.
[0013] The aforementioned negative performance region refers to: importance index This means that an increase in flux in this energy region will reduce Mo-99 production.
[0014] The aforementioned screening of filter nuclides from the absorption cross-section characteristics of natural isotopes refers to the following: the filter material is difficult to dissolve in the NaOH alkaline dissolution process or can be removed through the solid-liquid separation step, thereby meeting the Mo-99 radioactivity purity requirements without adding additional chemical separation processes. It also comprehensively considers the natural abundance of candidate nuclides, material availability, cost, and the half-life of irradiation activation products to limit the burden of post-irradiation shielding and waste disposal.
[0015] The filtered nuclides include the molybdenum system nuclides Mo-95 and Mo-96, which achieve spectral filtration through selective absorption in the negative performance region without the risk of introducing new elemental impurities.
[0016] For the CANDU stack, the filter material is praseodymium metal, antimony metal, silver metal, lanthanum oxide, lead sulfide, samarium oxide, or a combination thereof.
[0017] For the JRR-3 stack, the filter material is erbium oxide, tantalum pentoxide, indium sulfide, tellurium disulfide, dysprosium oxide, cerium dioxide, samarium oxide, metallic iridium, metallic gold, metallic rhenium, strontium sulfate, neodymium oxide, or a combination thereof.
[0018] The loading method of the filter material is: in-target dispersion doping, adding the filter material during the MoO3 powder forming or sintering stage.
[0019] Technical effect
[0020] This invention achieves quantitative identification of the energy range contributing to Mo-99 production through energy region importance index, avoiding reliance solely on experience in material selection and spectrum tuning. By selectively absorbing negative performance regions, it achieves energy spectrum redistribution, increasing effective yield without increasing reactor power and total flux. It also prioritizes the selection of insoluble or solid-liquid separable materials, reducing the risk of impurities entering the alkali-soluble post-treatment system and minimizing additional processing steps. Attached Figure Description
[0021] Figure 1 This is a flowchart of the present invention;
[0022] Figure 2 A schematic diagram of the geometry modeling of the CANDU reactor core;
[0023] Figure 3 A schematic diagram of the geometry modeling of the JRR3 reactor core;
[0024] Figure 4 A schematic diagram of the saturation curve of Mo-99 production as a function of irradiation time;
[0025] Figure 5 This is a schematic diagram of the importance curve of Mo-99 production capacity under CANDU reactor conditions;
[0026] Figure 6A schematic diagram of the importance curve of Mo-99 production energy zone under the operating conditions of the JRR3 research reactor. Detailed Implementation
[0027] Example 1
[0028] like Figure 1 As shown, this embodiment relates to energy dispersive spectroscopy (EDS) analysis and filter material determination under CANDU stack pore conditions, including:
[0029] Step 1: Taking the typical irradiation channels of the CANDU reactor as the object, a three-dimensional transport-burnup coupled model was established, including the reactor core, channels, and MoO3 target enriched with Mo-98. The irradiation time was determined by the accumulation of Mo-99 production over time, and a 7-day irradiation strategy was finally set.
[0030] Step 2: Divide the neutron full-energy region into 238 energy regions, apply a flux perturbation of uniform amplitude to each energy region in sequence, calculate the importance index of each energy region and obtain the importance curve.
[0031] Step 3: After identifying the negative performance region, filter nuclides with significant absorption peaks in the energy range are screened from the natural isotope absorption cross section library, and the doping amount is scanned and calculated. The effective filter nuclides are shown in Table 1.
[0032] Table 1. CANDU stack filtration effect on nuclides
[0033] Step 4: Convert the effective isotope scheme into a material scheme and consider the compatibility of post-alkali dissolution treatment. The available materials and optimization effects are shown in Table 2.
[0034] Table 2. Effect of CANDU stack filter material
[0035] Example 2
[0036] like Figure 1 As shown, this embodiment relates to energy dispersive spectroscopy (EDS) analysis and filter material determination under the pore conditions of the JRR3 research reactor, including:
[0037] Step 1: Taking the typical irradiation channel of the JRR3 research reactor as the object, a three-dimensional transport-burnup coupling model was established and the saturation trend of Mo-99 production over time was calculated. An engineering-operable irradiation strategy (9 days) was selected.
[0038] Step 2: Divide the neutron full-energy region into 238 energy regions, apply a flux perturbation of uniform amplitude to each energy region in sequence, calculate the importance index of each energy region and obtain the importance curve.
[0039] Step 3: After identifying the negative performance region, filter nuclides with significant absorption peaks in the energy range are screened from the natural isotope absorption cross section library, and the doping amount is scanned and calculated. The effective filter nuclides are shown in Table 3.
[0040] Table 3. Effect of JRR3 research reactor on filtration of nuclides
[0041] Step 4: Convert the effective isotope scheme into a material scheme and consider the compatibility of post-alkali dissolution treatment. The available materials and optimization effects are shown in Table 4.
[0042] Table 4. Effects of filter materials on the JRR3 research pile
[0043] Compared with existing technologies, this method increases Mo-99 yield and reduces the risk of radioactive impurity introduction without adding additional post-processing steps. It is suitable for industrial and regional supply of Mo-99 to various reactor platforms, including commercial and research reactors. In the CANDU reactor, 0.000454 g / cm³ is added. 3 The addition of praseodymium metal can increase Mo-99 production by 23.269%; in the JRR3 stack, adding 0.03 g / cm³... 3 Erbium oxide can increase the yield of Mo-99 by 45.956%.
[0044] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.
Claims
1. A method for Mo-99 irradiation production and energy spectrum optimization based on reactor activation, characterized in that, After establishing a three-dimensional high-fidelity neutronics and burnup coupling model of the reactor and irradiation channels, the full-energy neutron region was divided into covered areas. The energy range of MeV includes 238 energy regions, including the thermal neutron energy region, the resonance energy region, and the fast neutron energy region. By perturbing the flux of a single energy region, the importance index and importance curve of Mo-99 yield to the flux change of each energy region are obtained, thereby identifying the positive and negative important performance regions. For the negative important performance regions, filter nuclides are screened from the absorption cross-section characteristics of natural isotopes, and burnup calculations are performed at different doping levels to obtain the yield gain. Then, the isotope scheme is converted into a natural abundance material scheme to determine the optimal filter material and loading method. The aforementioned three-dimensional high-fidelity neutronics and burnup coupling model refers to: establishing a three-dimensional core-channel-target model based on the actual geometry and material composition of the reactor, using neutron transport calculations to obtain the flux and reaction rate of each energy region, and iteratively coupling it with burnup / decay calculations within a discrete time step to obtain a calculation model for nuclide evolution and Mo-99 cumulative yield during irradiation.
2. The method for Mo-99 irradiation production and energy spectrum optimization based on reactor activation as described in claim 1, characterized in that, The reactor activation method refers to the following: Mo-98 enriched target is placed in the reactor neutron flux field for continuous irradiation, so that Mo-98 is converted into Mo-99 through (n,γ) reaction, and after irradiation, Mo-99 product that meets the loading requirements of medical generator is obtained by cooling and conventional alkaline dissolution-solid-liquid separation / purification process.
3. The method for Mo-99 irradiation production and energy spectrum optimization based on reactor activation as described in claim 1, characterized in that, The perturbation refers to: completing a three-dimensional transport-burnup coupling calculation under baseline operating conditions to obtain the baseline neutron flux in 238 energy regions. After adjusting the baseline Mo-99 terminal output Y, only the flux in energy region i is perturbed by single-energy region flux, i.e., according to... Scaling is performed while keeping the flux in other energy regions constant; the perturbed Mo-99 terminal yield Y' is obtained by repeated burnup calculations under the same irradiation strategy, target and material arrangement conditions.
4. The method for Mo-99 irradiation production and energy spectrum optimization based on reactor activation as described in claim 3, characterized in that, The irradiation strategy is 7 days under CANDU reactor conditions or 9 days under JRR3 research reactor conditions.
5. The method for Mo-99 irradiation production and energy spectrum optimization based on reactor activation as described in claim 1 or 3, characterized in that, The importance indicators ,in: and These represent the neutron flux in energy region i before and after the perturbation, respectively. The aforementioned importance curve refers to a curve with the lower bound of the energy region as the horizontal axis and the importance index as the horizontal axis. The curve plotted on the ordinate is used to characterize the contribution of flux changes in each energy region to the final yield of Mo-99. The aforementioned negative performance region refers to: importance index This means that an increase in flux in this energy region will reduce Mo-99 production.
6. The method for Mo-99 irradiation production and energy spectrum optimization based on reactor activation as described in claim 1, characterized in that, The aforementioned screening of filter nuclides from the absorption cross-section characteristics of natural isotopes refers to the following: the filter material is difficult to dissolve in the NaOH alkaline dissolution process or can be removed through the solid-liquid separation step, thereby meeting the Mo-99 radioactivity purity requirements without adding additional chemical separation processes. It also comprehensively considers the natural abundance of candidate nuclides, material availability, cost, and the half-life of irradiation activation products to limit the burden of post-irradiation shielding and waste disposal.
7. The method for Mo-99 irradiation production and energy spectrum optimization based on reactor activation as described in any one of claims 1-6, characterized in that, The filtered nuclides include the molybdenum system nuclides Mo-95 and Mo-96, which achieve spectral filtration through selective absorption in the negative performance region without the risk of introducing new elemental impurities.
8. The method for Mo-99 irradiation production and energy spectrum optimization based on reactor activation as described in any one of claims 1-6, characterized in that, The filter material is: For CANDU reactors, praseodymium metal, antimony metal, silver metal, lanthanum oxide, lead sulfide, samarium oxide, or combinations thereof are used. For the JRR-3 reactor, erbium oxide, tantalum pentoxide, indium sulfide, tellurium disulfide, dysprosium oxide, cerium dioxide, samarium oxide, metallic iridium, metallic gold, metallic rhenium, strontium sulfate, neodymium oxide, or combinations thereof are used.
9. The method for Mo-99 irradiation production and energy spectrum optimization based on reactor activation as described in any one of claims 1-6, characterized in that, Add 0.000454 g / cm³ to the CANDU heap. 3 Praseodymium metal, or 0.03 g / cm³ added to the JRR3 pile. 3 Erbium oxide can increase the yield of Mo-99 by 45.956%.