Yield calculation method suitable for research reactor irradiation production of iride-192

Abstract

The invention relates to the technical field of nuclear industry, in particular to a yield calculation method suitable for researching reactor irradiation production of iride-192. The method mainly comprises the steps that the neutron fluence rate and the reaction rate of the target nuclear position of a target piece are obtained through Monte Carlo critical calculation; target nuclear burnup is obtained, a target nuclear material is adjusted based on target nuclear burnup changes, and the neutron fluence rate and the reaction rate are recalculated; and after multiple iterations in one irradiation period, outputting the yield of the iride-192. By means of the method, the neutron fluence rate and the reaction rate of the target material and the target nucleus can be determined in the mode of establishing the models of the research reactor and the irradiation device, and the yield of the iridium 192 produced in the research reactor through irradiation can be accurately calculated in the mode of completing multi-time iterative calculation by dividing burnup steps.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear industry, and in particular to a yield calculation method suitable for producing iridium-192 by irradiation of a research reactor. Background Art

[0002] Iridium is a Group VIII transition metal element, with a content of one part in ten million in the earth's crust. There are two isotopes in nature, iridium-191 and iridium-193. The artificial radioactive isotope iridium-192 is obtained by neutron radiation of the stable element iridium-191, and is commonly used in radiotherapy, industry, scientific research and other fields.

[0003] Iridium-191 can be converted into iridium-192 through the (n, γ) reaction after neutron irradiation. The reaction cross section is large. Therefore, in the process of producing iridium-192 by research reactor irradiation, if the target material is arranged too densely, it will cause the local thermal neutron fluence rate to decrease, thus affecting the yield of the target product iridium-192. Therefore, in the process of calculating the yield of iridium-192 produced by research reactor irradiation, it is necessary not only to calculate the neutron fluence rate of the irradiation environment in the research reactor, but also to accurately calculate the neutron fluence rate of the target material. Since the target material is a circular thin sheet with extremely small size, and different material enrichment will also affect the final yield calculation result, it is necessary to establish a yield calculation method for iridium-192 irradiation production.

[0004] Ways to increase the yield of iridium-192 include extending the irradiation time and increasing the ion injection rate in the irradiation environment, of which the former is more flexible. If the irradiation production of iridium-192 in a research reactor with a long irradiation cycle is carried out without considering the change in the target core's burnup over the irradiation time, the yield calculation will be too high, making it impossible to accurately calculate the yield. Summary of the invention

[0005] The purpose of the present invention is to provide a yield calculation method suitable for producing iridium-192 by irradiation in a research reactor to solve the above-mentioned problems in the prior art.

[0006] The present invention is achieved through the following technical solutions:

[0007] A yield calculation method for iridium-192 produced by research reactor irradiation, including:

[0008] The neutron injection rate and reaction rate of the target core position are obtained through Monte Carlo critical calculation;

[0009] Obtain target nuclear burnup, adjust target nuclear material based on target nuclear burnup changes, and recalculate neutron injection rate and reaction rate;

[0010] Output of iridium-192 production after multiple iterations within an irradiation cycle.

[0011] Preferably, it also includes:

[0012] Obtain the core loading basic data, fuel burnup distribution and critical rod position of the target research reactor, and establish a full core Monte Carlo model at different combustion times based on the core loading basic data, fuel burnup distribution and critical rod position;

[0013] Preferably, it includes establishing a Monte Carlo model of the Iridium-192 irradiation device based on the full-core Monte Carlo model.

[0014] Preferably, different types of in-core components of the research reactor are obtained for geometric modeling and material modeling, and based on the balanced cycle core loading, fuel burnup distribution and critical rod positions, the full-core Monte Carlo model is constructed by describing the positions in the reactor one by one.

[0015] Preferably, the Monte Carlo model of the Iridium-192 irradiation device comprises:

[0016] Determine the position of the fuel element closest to the core center and the positioning point of the irradiation device;

[0017] A target material, an aluminum clamp block and an aluminum cladding are constructed, wherein the target material is arranged in the aluminum cladding, and the aluminum cladding is arranged in the aluminum clamp block.

[0018] Preferably, a single target is modeled based on a full core Monte Carlo model and an Iridium-192 irradiator Monte Carlo model.

[0019] Preferably, the neutron fluence rate includes:

[0020]

[0021] Wherein, Φ(r) is the neutron fluence rate at position r, dN is the number of neutrons passing through a unit area in a certain time period, dA is the unit area, and dt is the time interval.

[0022] Preferably, the reaction rate includes:

[0023] R(r)=∫σ(E)Φ(E,r)f(E)dE

[0024] Where R(r) is the reaction rate at position r, σ(E) is the reaction cross section, Φ(E, r) is the neutron fluence rate with energy E at position r, and f(E) is the neutron energy spectrum distribution function.

[0025] Preferably, the multiple iterations within one irradiation cycle include:

[0026] Determine the irradiation cycle, divide the burnup distribution, obtain the neutron injection rate and reaction rate of the target nuclear material adjusted and recalculated based on the target nuclear burnup change, calculate the yield of the first burnup step, and obtain the first calculation result;

[0027] According to the first calculation result, the target nuclear material is adjusted based on the change of target nuclear burnup and the neutron injection rate and reaction rate are recalculated to calculate the yield of the several burnup steps and the several calculation results;

[0028] Set the number of iterations and output the N calculation results of the final iteration.

[0029] Preferably, the determining of the irradiation cycle and the division of the fuel consumption distribution includes:

[0030] Determine the target output power and fuel efficiency, and use the reactor kinetic model to calculate the neutron flux and power output at different irradiation times;

[0031] Determine the fuel layout in the reactor and divide the fuel in the reactor into different cloths.

[0032] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0033] The method provided by the present invention mainly includes obtaining the neutron fluence rate and reaction rate of the target core position of the target through Monte Carlo critical calculation; obtaining the target core burnup, adjusting the target core material based on the change of the target core burnup and recalculating the neutron fluence rate and reaction rate; and outputting the iridium-192 yield after multiple iterations in one irradiation cycle. Through the above method, the neutron fluence rate and reaction rate of the target core can be determined by establishing a model of the research reactor and the irradiation device, and the yield of iridium-192 produced by irradiation in the research reactor can be accurately calculated by dividing the burnup step to complete multiple iterations. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 This is a schematic diagram of the Monte Carlo modeling of the Iridium-192 irradiation device of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0037] The modules or submodules described independently may be physically separated or not: they may be implemented by software or hardware, and some modules or submodules may be implemented by software, and the processor may call the software to implement the functions of these modules or submodules, and other modules or submodules may be implemented by hardware, such as by hardware circuits. In addition, some or all of the modules may be selected according to actual needs to achieve the purpose of the present application.

[0038] Please refer to Figure 1 The present invention provides a method for calculating the yield of iridium-192 produced by research reactor irradiation, comprising:

[0039] S101: Obtain the neutron injection rate and reaction rate of the target core position through Monte Carlo critical calculation;

[0040] Detailed modeling of the core and irradiation device: First, a detailed Monte Carlo modeling is performed for the various types of internal components (fuel elements, burnable poisons, beryllium blocks, aluminum blocks, stainless steel blocks, control rods, etc.) in the research reactor, and the Monte Carlo modeling of the whole core at different core burnup times is completed based on the balanced cycle core loading, fuel burnup distribution, critical rod position and other information. Then, the Monte Carlo modeling of the iridium-192 irradiation device is performed, and the detailed modeling of the target material, aluminum cladding, and aluminum clamp block is completed. The iridium-192 irradiation device is placed at different positions in the core to complete the detailed modeling of the core and irradiation device.

[0041] S102: Obtain target nuclear burnup, adjust target nuclear material based on target nuclear burnup change, and recalculate neutron injection rate and reaction rate;

[0042] Neutron injection rate and reaction rate calculation: Based on the core and irradiation device detailed model established in the previous step, the neutron injection rate and reaction rate of each target in the irradiation environment are obtained through Monte Carlo critical calculation. 191 Ir(n,γ) 192 Ir reaction rate.

[0043] S103: After multiple iterations in one irradiation cycle, output the iridium-192 yield.

[0044] Yield calculation: After determining the irradiation cycle, divide it into multiple burnup steps, based on the target information of the above steps and the neutron injection rate and 191 Ir(n,γ) 192 Ir reaction rate, multiple iterations, complete the accurate calculation of iridium-192 production.

[0045] The method provided by the present invention mainly includes obtaining the neutron fluence rate and reaction rate of the target core position of the target through Monte Carlo critical calculation; obtaining the target core burnup, adjusting the target core material based on the change of the target core burnup and recalculating the neutron fluence rate and reaction rate; and outputting the iridium-192 yield after multiple iterations in one irradiation cycle. Through the above method, the neutron fluence rate and reaction rate of the target core can be determined by establishing a model of the research reactor and the irradiation device, and the yield of iridium-192 produced by irradiation in the research reactor can be accurately calculated by dividing the burnup step to complete multiple iterations.

[0046] An exemplary embodiment of the present invention further includes:

[0047] Obtain the core loading basic data, fuel burnup distribution and critical rod position of the target research reactor, and establish a full core Monte Carlo model at different combustion times based on the core loading basic data, fuel burnup distribution and critical rod position;

[0048] Specifically, core modeling: The high-flux research reactor provides an irradiation production environment for the production of iridium-192. The core active area height of the high-flux reactor is 100 cm. The fuel uses low-enriched uranium multilayer sleeve fuel assemblies, water is used as a moderator, and beryllium is used as a reflector. Its reactivity control is mainly achieved by rod control, and its control rod structure is an absorber (Ag-In-Cd) + transition section (stainless steel) + follower (Be). First, geometric modeling and material modeling are carried out for different types of internal components of a typical high-flux research reactor (fuel assemblies, burnable poisons, beryllium blocks, aluminum blocks, stainless steel blocks, control rods, etc.). Based on the balanced cycle core loading and fuel consumption distribution, critical rod position and other information, the above-mentioned modeling is completed by describing the position in the reactor one by one.

[0049] An exemplary embodiment of the present invention includes establishing a Monte Carlo model of an iridium-192 irradiation device based on the full-core Monte Carlo model.

[0050] The iridium-192 irradiator is designed to be placed in the center hole of the fuel element for irradiation. Taking the typical core of the high-flux research reactor as an example, first determine the position of the fuel element closest to the center of the core, determine the positioning point of the irradiator, and there is an irradiation space with a diameter of 1.4 cm in the center of the multi-layered tube fuel assembly that can be used for isotope target irradiation. Figure 1As shown, the irradiation device is designed to consist of three parts: target material, aluminum clamp block, and aluminum cladding. The target material is designed to be a pure iridium circular sheet with a diameter of 2.7mm and a thickness of 0.15mm. The aluminum clamp block is a special-shaped cylinder with a central hole. The inner diameter of the clamp block is 0.4cm and the outer diameter is 0.8cm. The internal central hole is filled with helium. The aluminum cladding is a special-shaped cylinder with a central hole. The inner diameter of the cladding is 0.8cm and the outer diameter is 1.0cm. The clamp block and the cladding together play the role of positioning and fixing the target material, and the composition is 6061 aluminum alloy. The design height of the device is 400mm, placed at a height of 300-700mm (starting from the bottom of the active area). The entire device can load up to 344 targets, totaling 6.88g.

[0051] Preferably, a single target is modeled based on a full core Monte Carlo model and an Iridium-192 irradiator Monte Carlo model.

[0052] Preferably, the neutron fluence rate includes:

[0053]

[0054] Wherein, Φ(r) is the neutron fluence rate at position r, dN is the number of neutrons passing through a unit area in a certain time period, dA is the unit area, and dt is the time interval.

[0055] In an exemplary embodiment of the present invention, the reaction rate includes:

[0056] R(r)=∫σ(E)Φ(E,r)f(E)dE

[0057] Where R(r) is the reaction rate at position r, σ(E) is the reaction cross section, Φ(E, r) is the neutron fluence rate with energy E at position r, and f(E) is the neutron energy spectrum distribution function.

[0058] In an exemplary embodiment of the present invention, multiple iterations within one irradiation cycle include:

[0059] Determine the irradiation cycle, divide the burnup distribution, obtain the neutron injection rate and reaction rate of the target nuclear material adjusted and recalculated based on the target nuclear burnup change, calculate the yield of the first burnup step, and obtain the first calculation result;

[0060] According to the first calculation result, the target nuclear material is adjusted based on the change of target nuclear burnup and the neutron injection rate and reaction rate are recalculated to calculate the yield of the several burnup steps and the several calculation results;

[0061] Set the number of iterations and output the N calculation results of the final iteration.

[0062] The irradiation cycle of the High Flux Research Reactor is 28.75 days, and the irradiation cycle is divided into 8 burnup steps according to the core physics calculation process. Based on the thermal neutron injection rate and reaction rate of the target material obtained in step 2, the yield calculation of iridium-192 in the first burnup step is carried out. In the process of yield calculation, the production and consumption of iridium-192 must be considered at the same time. It is known that iridium-192 is converted from iridium-191 through the (n, γ) reaction, and iridium-192 can undergo β decay and convert 192 Pt and 192 Os, iridium-192 can undergo (n, γ) reaction to be converted into 193Ir. Using the calculated isotope content of each burnup chain as input, the calculation process from step S101 to step S103 is repeated to complete the yield calculation of 8 burnup steps, and the iridium-192 yield calculation results are shown in Table 1.

[0063] In an exemplary embodiment of the present invention, determining the irradiation period and dividing the fuel consumption distribution includes:

[0064] Determine the target output power and fuel efficiency, and use the reactor kinetic model to calculate the neutron flux and power output at different irradiation times;

[0065] Determine the fuel layout in the reactor and divide the fuel in the reactor into different cloths.

[0066] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0067] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. The computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of various embodiments of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0068] Table 1 Calculation results of iridium-192 production

[0069]

[0070] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for calculating the yield of iridium-192 produced by research reactor irradiation, characterized in that: include: The neutron injection rate and reaction rate of the target core position are obtained through Monte Carlo critical calculation; Obtain target nuclear burnup, adjust target nuclear material based on target nuclear burnup changes, and recalculate neutron injection rate and reaction rate; Output of iridium-192 production after multiple iterations within an irradiation cycle.

2. A method for calculating the yield of iridium-192 suitable for production by research reactor irradiation according to claim 1, characterized in that: Also includes: The basic data of core loading, fuel burnup distribution and critical rod position of the target research reactor are obtained, and a full-core Monte Carlo model at different combustion times is established based on the basic data of core loading, fuel burnup distribution and critical rod position.

3. A method for calculating the yield of iridium-192 suitable for production by research reactor irradiation according to claim 2, characterized in that: The method comprises establishing a Monte Carlo model of an iridium-192 irradiation device based on the full core Monte Carlo model.

4. A method for calculating the yield of iridium-192 suitable for production by research reactor irradiation according to claim 3, characterized in that: The full core Monte Carlo model includes: Different types of in-core components of the research reactor are obtained for geometric modeling and material modeling. Based on the balanced cycle core loading, fuel burnup distribution and critical rod positions, the Monte Carlo model of the full core is constructed by describing the positions in the reactor one by one.

5. A method for calculating the yield of iridium-192 suitable for production by research reactor irradiation according to claim 4, characterized in that: The Monte Carlo model of the Iridium-192 irradiation device includes: Determine the position of the fuel element closest to the core center and the positioning point of the irradiation device; A target material, an aluminum clamp block and an aluminum cladding are constructed, wherein the target material is arranged in the aluminum cladding, and the aluminum cladding is arranged in the aluminum clamp block.

6. A method for calculating the yield of iridium-192 suitable for production by research reactor irradiation according to claim 5, characterized in that: A single target material is modeled based on the Monte Carlo model of the whole core and the Monte Carlo model of the Iridium-192 irradiator.

7. A method for calculating the yield of iridium-192 suitable for production by irradiation of a research reactor according to claim 6, characterized in that: The neutron fluence rate includes: Wherein, Φ(r) is the neutron fluence rate at position r, dN is the number of neutrons passing through a unit area in a certain time period, dA is the unit area, and dt is the time interval.

8. A method for calculating the yield of iridium-192 suitable for production by research reactor irradiation according to claim 7, characterized in that: The response rates include: R(r)=∫σ(E)Φ(E,r)f(E)dE Where R(r) is the reaction rate at position r, σ(E) is the reaction cross section, Φ(E, r) is the neutron fluence rate with energy E at position r, and f(E) is the neutron energy spectrum distribution function.

9. A method for calculating the yield of iridium-192 suitable for production by research reactor irradiation according to claim 8, characterized in that: The multiple iterations within one irradiation cycle include: Determine the irradiation cycle, divide the burnup distribution, obtain the neutron injection rate and reaction rate of the target nuclear material adjusted and recalculated based on the target nuclear burnup change, calculate the yield of the first burnup step, and obtain the first calculation result; According to the first calculation result, the target nuclear material is adjusted based on the change of target nuclear burnup and the neutron injection rate and reaction rate are recalculated to calculate the yield of the several burnup steps and the several calculation results; Set the number of iterations and output the N calculation results of the final iteration.

10. The method for calculating the yield of iridium-192 produced by irradiation in a research reactor according to claim 1, characterized in that: Determining the irradiation cycle and dividing the fuel consumption distribution includes: Determine the target output power and fuel efficiency, and use the reactor kinetic model to calculate the neutron flux and power output at different irradiation times; Determine the fuel layout in the reactor and divide the fuel in the reactor into different cloths.

Images