Target Nuclide Search Method for Isotope Production Based on Bidirectional Transmutation

Abstract

The present invention relates to a target nuclide search method for isotope production based on bidirectional transmutation, wherein the method determines all nuclide production paths of the target isotope based on bidirectional transmutation, as well as the conversion rate of each nuclide in each production path to the final isotope yield, thereby determining the optimal target nuclide composition for irradiating the isotope. Compared with the prior art, the method of the present invention can quickly and effectively determine the target nuclide composition of the production isotope without any prior information or multiple tentative Monte Carlo burnup calculations, greatly reducing the consumption of computing resources and simplifying the determination process of the target nuclide composition, thereby effectively supporting the design of irradiated targets and improving the economy of isotope irradiation production. In particular, it has unique advantages when determining the production plan of new isotopes with less production experience.

Description

Technical Field

[0001] The invention relates to the technical field of target design for isotope production, and in particular to a target nuclide search method for isotope production based on bidirectional transmutation. Background Art

[0002] The quality of irradiation targets directly determines the economic efficiency of isotope irradiation production. The traditional method of determining the nuclide composition of irradiation targets relies on experience and requires a large number of Monte Carlo burnup calculations to verify the production effect, which has low design efficiency. At the same time, for new isotopes without actual production experience, there is no experience to refer to for the selection of target nuclide composition, and it can only be selected blindly, resulting in low nuclide conversion rate. Therefore, there is an urgent need for a method that can quickly and effectively determine the nuclide composition of targets used to produce isotopes. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a target nuclide search method for isotope production based on bidirectional transmutation, which can quickly and effectively determine the target nuclide composition for isotope production. In view of the problem that the traditional method for determining the nuclide composition of irradiated targets relies on experience and is inefficient, all nuclide production paths of the target isotope and the conversion rate of each nuclide in each production path to the final isotope yield are determined based on bidirectional transmutation, so as to quantify the production effect of all candidate nuclides. The traditional method for determining the nuclide composition of irradiated targets relies on experience to select target nuclides and performs multiple Monte Carlo-burnup calculations to quantify their production effects. The present invention directly starts from the target nuclide, first performs reverse transmutation, so as to find all candidate nuclides at one time, and then performs forward transmutation on all candidate nuclides to quantify their production effects. Therefore, the present invention can quantify the production effects of all candidate nuclides by only performing a "bidirectional transmutation" on the isotopes that need to be produced, avoiding multiple blind nuclide selections and the required yield evaluation based on Monte Carlo burnup calculations, greatly reducing the consumption of computing resources, and simplifying the process of determining the target nuclide composition, thereby effectively supporting the design of irradiation targets and improving the economy of isotope irradiation production.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] The object of the present invention is to provide a target nuclide search method for isotope production based on bidirectional transmutation, wherein the method determines all nuclide production paths of the target isotope based on bidirectional transmutation, as well as the conversion rate of each nuclide in each production path to the final isotope yield, thereby determining the optimal target nuclide composition for irradiating the isotope.

[0006] Furthermore, the method comprises the following steps:

[0007] Step 1: Perform reverse transmutation on the target isotope;

[0008] Step 2: Screen candidate target nuclides according to nuclide conversion rate;

[0009] Step 3: Perform forward transmutation calculation on candidate target nuclides;

[0010] Step 4: Record the conversion path and conversion rate of the candidate target nuclides;

[0011] Step 5: Compare the production results of alternative target nuclides.

[0012] Furthermore, in step 1, the specific process of performing reverse transmutation on the target isotope is as follows:

[0013] Perform reverse transmutation calculations with the target nuclide density as the initial nuclide density N 0 , the total time T of nuclide transmutation is divided into m small time steps Δt, where T = m × Δt, the nuclide generation rate is the decay constant λ, and the nuclide density obeys the exponential decay law, then the formula: N 1 =N 0 e -λΔt Calculate the nuclide density N of the target isotope in the next time step 1 At the same time, the target isotope's nuclide density decreases by N 0 (1-e -λΔt ) is the initial nuclide density of the parent nuclide of the target isotope in the next time step. This iterative process is repeated until all m-step iterations are completed.

[0014] Furthermore, in step 2, the specific process of screening candidate target nuclides according to nuclide conversion rate is as follows:

[0015] Record the conversion rates of all nuclides after the iteration in step 1 and the target isotopes after the iteration, sort the conversion rates of all nuclides after the iteration from high to low, and select the nuclides with conversion rates ranked before the set position as candidate target nuclides according to the sorting relationship.

[0016] Furthermore, the set rank may be any integer value between 2 and 8. For example, when the rank is set to 4, the nuclides with the top 4 (including the 4th) conversion rates are selected as candidate target nuclides according to the ranking relationship.

[0017] Furthermore, the candidate target nuclides refer to target nuclides that can be used as the target nuclide composition for producing the target isotope.

[0018] Furthermore, in step 3, the specific process of performing forward transmutation calculation on the candidate target nuclides is as follows:

[0019] Perform forward transmutation calculation, taking the candidate target nuclide density as the initial nuclide density N 0 , taking the disappearance rate of the nuclide as the decay constant λ, the same iterative process as the reverse transmutation calculation is performed.

[0020] Furthermore, in step 3, after all iteration steps are completed, the nuclide density of the target isotope is recorded as the theoretical yield of the target nuclide produced by the candidate target nuclide.

[0021] Furthermore, the nuclide transformation pathway refers to: a nuclide transformation chain formed via an intermediate nuclide during the transformation process from one nuclide to another nuclide.

[0022] Furthermore, in step 4, recording the nuclide transformation path and transformation rate of the candidate target is specifically recording the nuclide transformation path and transformation rate of the candidate target nuclide to the target isotope in step 3.

[0023] Furthermore, in step 5, the specific process of comparing the production effects of the candidate target nuclides is as follows:

[0024] The advantages and disadvantages of different candidate target nuclides are evaluated according to their conversion rates. The production effect of the candidate target nuclides is positively correlated with the conversion rate of the candidate target nuclides to the target nuclides.

[0025] Furthermore, in step 5, the specific process of comparing the production effects of the candidate target nuclides is as follows:

[0026] The advantages and disadvantages of different candidate target nuclides are evaluated according to their conversion rates. The production effect of the candidate target nuclides is positively correlated with the conversion rate of the candidate target nuclides to the target nuclides. Specifically, it is believed that the higher the conversion rate of the candidate target nuclides to the target nuclides, the better the production effect, and the more suitable it is as a production target for the target isotope. At the same time, the nuclide conversion path provided in the bidirectional transmutation can be used for further isotope production plan analysis.

[0027] Furthermore, it is necessary to perform forward transmutation calculation on all candidate target nuclides screened in step 2, record the transformation path and transformation rate corresponding to each candidate target nuclide, and complete the calculation of all candidate target nuclides.

[0028] Furthermore, between step 4 and step 5, step A is also included:

[0029] Determine whether the calculation of all candidate targets is completed. If yes, proceed to step 5; otherwise, return to step 3 to analyze the next candidate target nuclide.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1) The target nuclide search method for isotope production based on bidirectional transmutation provided by the technical solution solves the problem that the traditional method for determining the nuclide composition of irradiated targets relies on experience and is inefficient. Compared with the traditional method, the present invention can quickly and effectively determine the nuclide composition of the target for producing isotopes without any prior information or multiple tentative Monte Carlo burnup calculations, greatly reducing the consumption of computing resources and simplifying the process of determining the nuclide composition of the target, thereby effectively supporting the design of irradiated targets and improving the economic efficiency of isotope irradiation production. It has unique advantages, especially when determining the production plan for new isotopes with less production experience.

[0032] 2) The target nuclide search method for isotope production based on bidirectional transmutation provided by the technical solution directly starts from the target nuclide, first performs reverse transmutation, thereby finding all candidate nuclides at one time, and then performs forward transmutation on all candidate nuclides to quantify their production effects. Therefore, the present invention can quantify the production effects of all candidate nuclides by only performing a "bidirectional transmutation" on the isotopes to be produced, avoiding multiple blind nuclide selections and the required yield evaluation based on Monte Carlo-burnup calculation, greatly reducing the consumption of computing resources, simplifying the process of determining the target nuclide composition, and thus effectively supporting the design of irradiation targets and improving the economy of isotope irradiation production. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a flow chart of an embodiment of the present invention;

[0034] Figure 2 Schematic diagram of the nuclide conversion path from Cm244 to Cf252 in an embodiment of the present invention;

[0035] Figure 3 Schematic diagram of the nuclide conversion path from Cm246 to Cf252 in an embodiment of the present invention;

[0036] Figure 4 Schematic diagram of the nuclide transformation path from Pu244 to Cf252 in an embodiment of the present invention;

[0037] Figure 5 Schematic diagram of the nuclide transformation pathway from Pu246 to Cf252 according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The features such as component models, material names, connection structures, control methods, etc. that are not clearly described in this technical solution are all regarded as common technical features disclosed in the prior art.

[0039] The present invention relates to a target nuclide search method for isotope production based on bidirectional transmutation, which specifically comprises the following steps:

[0040] Step 1: Perform reverse transmutation: Take the nuclide density of the target isotope as the initial nuclide density N 0 , the total time T of nuclide transmutation is divided into m small time steps Δt, where T = m × Δt, and the nuclide generation rate is the decay constant λ. According to the exponential decay law of nuclide density, the formula is: N 1 =N 0 e -λΔt The nuclide density N of the target isotope in the next time step can be calculated 1 At the same time, the target isotope's nuclide density decreases by N 0 (1-e -λΔt ) is the initial nuclide density of its parent nuclide in the next time step. Repeat this iterative process until all m steps of iteration are completed.

[0041] Step 2: Record all the nuclides and the conversion rates of these nuclides and the target isotopes after the iteration in step 1, sort the conversion rates of the nuclides from high to low, and select the nuclides with higher conversion rates as candidate target nuclides.

[0042] The candidate target nuclides refer to target nuclides that can be used as the target nuclide composition for producing the target isotope.

[0043] Step 3: Perform forward transmutation: Take the candidate target nuclide density as the initial nuclide density N0, take the nuclide disappearance rate as the decay constant λ, and perform the same iterative process as reverse transmutation. After completing all iterative steps, record the nuclide density of the target isotope, and use this value as the theoretical yield of the target isotope produced by this candidate target nuclide.

[0044] Step 4: Record the nuclide conversion path and conversion rate from the candidate target nuclide to the target isotope in step 3. When all candidate target nuclides are calculated, proceed to step 5.

[0045] Step 5: Evaluate the advantages and disadvantages of different candidate target nuclides according to the conversion rates of different target nuclides. It is believed that the higher the conversion rate of candidate target nuclides to target nuclides, the better the production effect and the more suitable the target nuclides composition as the target isotope. At the same time, the nuclide conversion path provided in the two-way transmutation can be used for further isotope production plan analysis.

[0046] The nuclide transformation path refers to: a nuclide transformation chain formed via an intermediate nuclide during the transformation process from one nuclide to another nuclide.

[0047] Example

[0048] This embodiment takes the production of isotope Cf252 as an example. Figure 1 As shown, it is a flow chart of the target nuclide search method for isotope production based on bidirectional transmutation involved in this embodiment, which specifically includes:

[0049] Step 1: Take Cf252 nuclide as the target nuclide, nuclide density N 0 =1×10 24 Pieces / cm 3 , total irradiation time T = 1 day, neutron flux density of irradiation environment φ = 3.55 × 10 16 Pieces / (cm 2 ·s), perform reverse transmutation calculations, and obtain the conversion rates of all nuclides and Cf252.

[0050] Step 2: By comparing the conversion rates of various nuclides with Cf252, four nuclides, Cm244, Cm246, Pu244 and Pu246, are selected as candidate target nuclides.

[0051] Step 3: Take Cm244, Cm246, Pu244 and Pu246 as the initial nuclides, and the initial nuclide density N 0 =1×10 24 Pieces / cm 3 , total irradiation time T = 90 days, neutron flux density φ = 3.55 × 10 16 Pieces / (cm 2 ·s), taking Cf252 as the target isotope, performing forward transmutation, obtaining and recording the Cf252 yield of each elemental nuclide and its nuclide conversion path and conversion rate to Cf252, such as Figure 2-5 shown.

[0052] Step 4: By analyzing the nuclide transformation path and transformation rate of the candidate target nuclides, it is believed that the higher the transformation rate, the better the theoretical production effect, and the more suitable it is as the target nuclide for producing the target isotope.

[0053] In this embodiment, the selected candidate target nuclides are verified by ignition consumption calculation, the yield obtained by ignition consumption calculation is compared with the yield and conversion rate obtained by "bidirectional transmutation", and the calculated results are compared with the mixed target currently used for Cf252 production. The verification results are shown in Table 1.

[0054] Table 1 Calculation results of the alternative target nuclides of this embodiment and the mixed target currently used for Cf252 production in the comparative example.

[0055]

[0056]

[0057] As shown in Table 1, the Cf252 yields of the four candidate target nuclides obtained using ignition consumption calculation and "bidirectional transmutation" are basically the same, proving that "bidirectional transmutation" has high accuracy.

[0058] The nuclide yields of these four candidate targets are no less than that of the existing mixed target, proving that "bidirectional transmutation" can effectively determine the nuclide composition of the target and improve the efficiency and economy of isotope production.

[0059] At the same time, Pu244 and Pu246 are nuclides not included in the existing mixed targets, and the theoretical yield of candidate target nuclides calculated by transmutation is also positively correlated with the nuclide conversion rate. Therefore, the technology of the present invention finds a variety of candidate target nuclides through only one "two-way transmutation", and can quantitatively give the conversion rate of various candidate target nuclides and the complete nuclide conversion path, simplifying the process of determining the target nuclide composition, thereby effectively supporting the design of irradiation targets and improving the economy of isotope irradiation production.

[0060] Comparative Example

[0061] This comparative example provides a mixed target currently used in Cf252 production, and the atomic density percentages of the target nuclides are shown in Table 2.

[0062] Table 2 Atomic density percentage of target nuclides in this comparative example.

[0063]

[0064]

[0065] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A target nuclide search method for isotope production based on bidirectional transmutation, characterized in that: The method determines all the nuclide production paths of the target isotope based on bidirectional transmutation, as well as the conversion rate of each nuclide in each production path to the final isotope yield, thereby determining the optimal target nuclide composition for irradiating the isotope; The method comprises the following steps: Step 1: Perform reverse transmutation on the target isotope; Step 2: Screen candidate target nuclides according to nuclide conversion rate; Step 3: Perform forward transmutation calculation on candidate target nuclides; Step 4: Record the conversion path and conversion rate of the candidate target nuclides; Step 5: Compare the production results of alternative target nuclides.

2. The target nuclide search method for isotope production based on bidirectional transmutation according to claim 1, characterized in that: In step 1, the specific process of performing reverse transmutation on the target isotope is as follows: Perform reverse transmutation calculation, take the target nuclide density as the initial nuclide density N0, divide the total time T of nuclide transmutation into m small time steps Δt, where T = m × Δt, take the nuclide generation rate as the decay constant λ, and according to the nuclide density obeying the exponential decay law, then by the formula: N1 = N0e -λΔt The target isotope nuclide density N1 in the next time step is calculated. At the same time, the target isotope nuclide density decrease N0 (1-e -λΔt ) is the initial nuclide density of the target isotope's parent nuclide in the next time step, completing all m-step iterations.

3. The target nuclide search method for isotope production based on bidirectional transmutation according to claim 2, characterized in that: In step 2, the specific process of selecting candidate target nuclides according to nuclide conversion rate is as follows: Record the conversion rates of all nuclides after the iteration in step 1 and the target isotopes after the iteration, sort the conversion rates of all nuclides after the iteration from high to low, and select the nuclides with conversion rates ranked before the set position as candidate target nuclides according to the sorting relationship.

4. The target nuclide search method for isotope production based on bidirectional transmutation according to claim 3, characterized in that: In step 3, the specific process of performing forward transmutation calculation on the candidate target nuclides is as follows: Perform forward transmutation calculation, take the candidate target nuclide density as the initial nuclide density N0, take the nuclide disappearance rate as the decay constant λ, and perform the same iterative process as the reverse transmutation calculation.

5. The target nuclide search method for isotope production based on bidirectional transmutation according to claim 4, characterized in that: In step 3, after all iterations are completed, the nuclide density of the target isotope is recorded, and this value is used as the theoretical yield of the target isotope produced by the candidate target nuclide.

6. The target nuclide search method for isotope production based on bidirectional transmutation according to claim 4, characterized in that: The nuclide transformation path refers to: a nuclide transformation chain formed via an intermediate nuclide during the transformation process from one nuclide to another nuclide.

7. The target nuclide search method for isotope production based on bidirectional transmutation according to claim 4, characterized in that: In step 4, recording the nuclide transformation path and transformation rate of the candidate target is specifically recording the nuclide transformation path and transformation rate of the candidate target nuclide to the target isotope in step 3.

8. The target nuclide search method for isotope production based on bidirectional transmutation according to claim 7, characterized in that: In step 5, the specific process of comparing the production effects of the candidate target nuclides is as follows: The advantages and disadvantages of different candidate target nuclides are evaluated according to their conversion rates. The production effect of the candidate target nuclides is positively correlated with the conversion rate of the candidate target nuclides to the target nuclides.

9. The target nuclide search method for isotope production based on bidirectional transmutation according to claim 1, characterized in that: Perform forward transmutation calculation on all candidate target nuclides selected in step 2, record the transformation path and transformation rate corresponding to each candidate target nuclide, and complete the calculation of all candidate target nuclides.

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