Calculation method for heat release rate of isotope irradiation target of pebble-bed high-temperature gas cooled reactor

Abstract

The invention provides a method for calculating the heat release rate of an isotope irradiation target of a pebble-bed high-temperature gas cooled reactor, and the method comprises the steps: constructing a reactor model of the pebble-bed high-temperature gas cooled reactor through a special design application, so as to calculate the nuclear fuel component distribution of a reactor core; carrying out two times of non-uniform arrangement on the reactor core fuel distribution through the MC application program to construct a reactor core MC model, and transmitting the nuclear fuel component distribution of the reactor core to the reactor core MC model; calculating a plurality of energy deposition heat release rates of the isotope irradiation target through a target Monte Carlo model for isotope irradiation production, and calculating a plurality of decay heat release rates of isotopes generated by irradiation; and adding the multiple energy deposition heat release rates and the multiple decay heat release rates to obtain the isotope irradiation target heat release rate of the pebble-bed high-temperature gas cooled reactor. According to the method, the heat release rate of the isotope irradiation target can be accurately calculated according to the characteristics of dual heterogeneity and non-stop refueling of the pebble-bed high-temperature gas cooled reactor.

Description

Technical Field

[0001] The present application relates to the technical field of calculation of physical thermal parameters of radioactive isotope targets, and in particular to a method for calculating the heat release rate of isotope irradiation targets of a pebble bed high temperature gas-cooled reactor. Background Art

[0002] At present, pebble bed high temperature gas-cooled reactors generally use spherical fuel elements (referred to as fuel balls), such as Figure 1 As shown in the figure, the hemisphere after the fuel ball is cut includes an outer fuel-free area 11 and an inner fuel area 12. The fuel area 12 has a plurality of coated fuel particles. The fuel particles include outer dense P y C layer 13, SiC layer 14, inner dense P y C layer 15, loose P y C Tier 16 and UO 2 The core structure of the pebble bed high temperature gas-cooled reactor can be simply described as a cylindrical pebble bed in the middle of the core with spherical fuel elements randomly stacked. Figure 2 As shown, the outside of the pebble bed is composed of graphite internal components, carbon internal components, metal internal components and reactor pressure vessel. The graphite internal components include a top reflection layer 21, a side reflection layer 22 and a bottom reflection layer 23. Figure 3 As shown, a control rod channel 31, an absorption ball channel 32, a cold helium gas channel 33, a neutron source channel 34 and a physical starting device channel 35 are arranged in the side reflection layer 22 of the graphite pile internal component.

[0003] When the pebble bed high temperature gas-cooled reactor reaches the first critical state, the neutron source channel 34 and the physical start-up device channel 35 (the structures and distribution circle diameters of the two are the same) are equipped with neutron sources and neutron counter tubes for physical start-up. During the operation of the reactor after the critical state, the neutron source and the neutron counter tubes for physical start-up will be moved out of the side reflection layer 22, that is, the corresponding neutron source channel and physical start-up device channel are empty.

[0004] According to the calculation of reactor physical parameters, the thermal neutron flux in the neutron source channel and the physical starter channel is considerable, which is equivalent to the thermal neutron flux in the reactor core. Figure 4 As shown. Therefore, the above two channels can be used for isotope production through modification. For the newly built pebble bed high temperature gas-cooled reactor, isotope production can be considered in the side reflector layer in the design. The isotope irradiation target is loaded into the channel for irradiation to produce the corresponding isotope. Furthermore, through the production of isotopes, the revenue of the pebble bed high temperature gas-cooled reactor nuclear power plant can be increased, greatly improving the operating efficiency of the nuclear power plant.

[0005] In practical applications, since the isotope irradiation target undergoes nuclear reaction and nuclear radiation during the irradiation process, heat will be generated, causing the target temperature to rise. In order to avoid excessive temperature of the target during the irradiation process, which may lead to thermal damage and deformation of the material, equipment failure, radioactive leakage, and affect the safety of reactor operation, it is necessary to calculate the heat release rate of the isotope irradiation target and analyze the temperature distribution of the irradiated target. However, since the pebble bed high temperature gas-cooled reactor is a new type of reactor, there is currently no precedent for using this type of reactor for isotope irradiation production. Therefore, the relevant technology lacks a solution for calculating the heat release rate of the pebble bed high temperature gas-cooled reactor isotope irradiation target. Summary of the invention

[0006] The present application aims to solve one of the technical problems in the related art at least to some extent.

[0007] To this end, the first purpose of the present application is to propose a method for calculating the heat release rate of isotope irradiation targets in a pebble bed type high temperature gas-cooled reactor. This method, in view of the dual non-uniformity and non-stop material replacement characteristics of the pebble bed type high temperature gas-cooled reactor, clarifies how to carry out the calculation of the heat release rate of targets under isotope irradiation production in a pebble bed type high temperature gas-cooled reactor, and can accurately calculate the heat release rate of isotope irradiated targets.

[0008] The second objective of the present application is to provide a calculation system for the heat release rate of isotope irradiation targets in a pebble bed high temperature gas-cooled reactor.

[0009] A third object of the present application is to provide a non-transitory computer-readable storage medium.

[0010] To achieve the above-mentioned purpose, the first aspect of the present application is to propose a method for calculating the heat release rate of isotope irradiation targets of a pebble bed high temperature gas-cooled reactor, comprising the following steps:

[0011] A reactor model of a pebble-bed high-temperature gas-cooled reactor to be calculated is constructed through a special design application for a pebble-bed high-temperature gas-cooled reactor, and the distribution of nuclear fuel components in the core is calculated based on the reactor model;

[0012] Through the Monte Carlo MC application program, the core fuel distribution of the pebble bed high temperature gas-cooled reactor is arranged twice in a non-uniform manner to construct a core MC model, and the nuclear fuel composition distribution of the core is transferred to the core MC model to obtain a target Monte Carlo model for isotope irradiation production;

[0013] Calculating multiple energy deposition heat release rates of the isotope irradiation target of the pebble bed high temperature gas-cooled reactor by using the target Monte Carlo model, and calculating multiple decay heat release rates of the isotopes generated by irradiation by using the relevant calculation results of the Monte Carlo MC application program;

[0014] The multiple energy deposition heat release rates and the multiple decay heat release rates are added together to obtain the isotope irradiation target heat release rate of the pebble bed high temperature gas-cooled reactor.

[0015] Optionally, in one embodiment of the present application, the reactor model includes a VSOP calculation model, and the calculation of the nuclear fuel composition distribution of the core based on the reactor model includes: dividing the core of the spherical bed high temperature gas-cooled reactor into a plurality of units based on the VSOP calculation model, wherein the plurality of units include different reflection layers and channels of the core; inputting material composition information of each of the units into the VSOP calculation model, and calculating the nuclear fuel composition distribution of the core through the operation program of the VSOP calculation model.

[0016] Optionally, in one embodiment of the present application, the fuel composition distribution of the core includes: nuclear fuel composition information of each batch in different areas, and the nuclear fuel composition distribution of the core is transferred to the core MC model, including: matching the coordinates of the core MC model and the VSOP calculation model to correspond to the fuel element model architecture of different areas; mapping the nuclear fuel composition information of each batch in each area calculated by the VSOP calculation model to the core MC model through a script program.

[0017] Optionally, in one embodiment of the present application, the core fuel distribution of the pebble bed type high temperature gas-cooled reactor is arranged non-uniformly twice, including: using the Monte Carlo MC application to perform geometric coordinate sampling of the coated fuel particles in a single spherical fuel element in the core, and establishing a fuel element model that conforms to the probability distribution of the coated fuel particles; arranging the pebble bed in the core with a preset filling rate, and using the Monte Carlo MC application to perform geometric coordinate sampling of the spherical fuel elements in the pebble bed, and establishing the core MC model containing isotope targets.

[0018] Optionally, in one embodiment of the present application, the calculation of multiple decay heat release rates of isotopes generated by irradiation includes: respectively determining the equations for the change of the pronucleon number with time of any isotope and the isotope target that produces the any isotope; determining the nuclear density function of the any isotope and the isotope target with respect to time based on the corresponding equation for the change of the pronucleon number with time; constructing a nuclear density balance equation based on the fact that the decay rate of any isotope is equal to the generation rate; and calculating the decay heat release rate of any isotope by combining the relevant calculation results of the Monte Carlo MC application, the nuclear density function and the nuclear density balance equation.

[0019] Optionally, in one embodiment of the present application, determining the nuclear density function of any isotope and the isotope target with respect to time includes: determining the nuclear density of any isotope and the isotope target at an initial moment, substituting the nuclear density of any isotope and the isotope target at the initial moment into the corresponding change equation, respectively, and solving the nuclear density function of any isotope and the isotope target.

[0020] Optionally, in one embodiment of the present application, the relevant calculation results of the Monte Carlo MC application program include: the thermal neutron fluence rate and the equilibrium concentration corresponding to the thermal neutron fluence rate, and the calculation of the decay heat release rate of any isotope species includes: substituting the thermal neutron fluence rate, the equilibrium concentration and the nuclear density function into the nuclear density equilibrium equation to calculate the time value for reaching nuclear density equilibrium; calculating the nuclear density and decay rate of any isotope at the time value, and calculating the decay heat release rate of any isotope based on the calculated nuclear density and decay rate at the time value.

[0021] To achieve the above-mentioned purpose, the second aspect of the present application further proposes a calculation system for the heat release rate of isotope irradiation targets of a pebble bed high temperature gas-cooled reactor, comprising the following modules:

[0022] The first construction module is used to construct a reactor model of a pebble bed high temperature gas-cooled reactor to be calculated through a special design application for a pebble bed high temperature gas-cooled reactor, and calculate the distribution of nuclear fuel components in the core based on the reactor model;

[0023] The second construction module is used to perform two non-uniform arrangements on the core fuel distribution of the pebble bed high temperature gas-cooled reactor through a Monte Carlo MC application program to construct a core MC model, and transfer the nuclear fuel composition distribution of the core to the core MC model to obtain a target Monte Carlo model for isotope irradiation production;

[0024] A first calculation module is used to calculate multiple energy deposition heat release rates of the isotope irradiation target of the pebble bed high temperature gas-cooled reactor by using the target Monte Carlo model, and to calculate multiple decay heat release rates of the isotopes generated by irradiation by using the relevant calculation results of the Monte Carlo MC application program;

[0025] The second calculation module is used to add the multiple energy deposition heat release rates and the multiple decay heat release rates to obtain the isotope irradiation target heat release rate of the pebble bed high temperature gas-cooled reactor.

[0026] In order to implement the above-mentioned embodiments, the third aspect of the present application also proposes a non-temporary computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the method for calculating the heat release rate of the isotope irradiation target of the pebble bed high-temperature gas-cooled reactor in the above-mentioned first aspect is implemented.

[0027] The technical solution provided by the embodiment of the present application brings at least the following beneficial effects: the present application comprehensively considers the dual non-uniformity and non-stop refueling characteristics of the pebble bed high temperature gas-cooled reactor, first calculates the composition distribution of the reactor core fuel through the pebble bed high temperature gas-cooled reactor special design software, then calculates the various energy deposition heat release rates of the high temperature gas-cooled reactor isotope irradiation target through the Monte Carlo model, and then uses the calculation results of the Monte Carlo model to calculate the various isotope decay heat release rates, and finally calculates the total heat release rate of the isotope irradiation target by combining the two heat release rates. Therefore, the present application accurately calculates various types of heat generation of the isotope target during the irradiation process based on the characteristics of the pebble bed high temperature gas-cooled reactor, and significantly reduces the error in the calculation results. The present application clarifies the calculation process of the heat release rate of the isotope irradiation target, and ensures the accuracy of the calculation results of the heat release rate of the isotope irradiation target, providing a data basis for the subsequent temperature analysis of the irradiated target. Therefore, the present application is conducive to the irradiation production of isotopes in a pebble bed type high temperature gas-cooled reactor, and helps to improve the safety of the irradiation production process of isotopes in a pebble bed type high temperature gas-cooled reactor.

[0028] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0030] Figure 1 A schematic diagram of the structure of a pebble bed high temperature gas-cooled reactor fuel element provided as an example of this application;

[0031] Figure 2 A schematic diagram of the core structure of a pebble bed high temperature gas-cooled reactor provided as an example of this application;

[0032] Figure 3 A schematic diagram of the pore structure of the side reflector layer of a pebble bed high temperature gas-cooled reactor provided as an example of the present application;

[0033] Figure 4 A thermal neutron flux distribution diagram of a core of a pebble bed high temperature gas-cooled reactor provided as an example of the present application;

[0034] Figure 5 A flow chart of a method for calculating the heat release rate of a target for isotope irradiation in a pebble bed high temperature gas-cooled reactor proposed in an embodiment of the present application;

[0035] Figure 6 A schematic diagram of a VSOP calculation model proposed in an embodiment of the present application;

[0036] Figure 7 A schematic diagram of the principle of nuclear fuel component transfer between a VSOP model and a MC model proposed in an embodiment of the present application;

[0037] Figure 8 A schematic diagram of a fuel element model constructed based on the MC program proposed in an embodiment of the present application;

[0038] Fig. 9 A schematic diagram of a core MC model including an isotope target proposed in an embodiment of the present application;

[0039] Fig.10 A schematic diagram of the structure of a system for calculating the heat release rate of isotope irradiation targets in a pebble bed high temperature gas-cooled reactor proposed in an embodiment of the present application. DETAILED DESCRIPTION

[0040] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0041] It should be noted that the present application analyzes and studies the heat generated by the nuclear reaction and nuclear radiation of the isotope irradiated target during the irradiation process, and determines that the generated heat includes the heat generated by the target core material, cladding material and structural parts, and the heat generation rate is mainly related to factors such as the operating power of the nuclear reactor, the nuclear properties of the material and the irradiation position. According to the energy deposition time, it can be divided into two parts: prompt and delayed. The neutron fission generated during the irradiation process in the pile and the photons generated during the neutron capture process are the main sources of prompt heat; while the delayed heat mainly comes from neutron activation products and fission products. According to the form of energy deposition, nuclear heating can be divided into neutron (abbreviated as n) collision heat, gamma ray (γ) heat of prompt neutron (n), gamma ray (γ) heat of delayed neutron (n) and decay heat of radioactive isotopes. Among them, the decay heat of isotopes includes different types of decay heat such as helium nuclei (α), electrons (β) and gamma (γ) of isotopes.

[0042] Based on this, the present application proposes a method for calculating the heat release rate of isotope irradiation targets in a pebble bed high temperature gas-cooled reactor, so as to facilitate the isotope irradiation production in a pebble bed high temperature gas-cooled reactor and improve the safety of isotope irradiation production.

[0043] The following describes a method and system for calculating the heat release rate of an isotope irradiation target of a pebble bed high temperature gas-cooled reactor proposed in an embodiment of the present application with reference to the accompanying drawings.

[0044] Figure 5 A flow chart of a method for calculating the heat release rate of a target for isotope irradiation in a pebble bed high temperature gas-cooled reactor proposed in an embodiment of the present application, as shown in FIG. Figure 5 As shown, the method comprises the following steps:

[0045] Step S101, constructing a reactor model of a pebble bed high temperature gas-cooled reactor to be calculated through a special design application for a pebble bed high temperature gas-cooled reactor, and calculating the distribution of nuclear fuel composition in the core based on the reactor model.

[0046] Specifically, a reactor operation model is established using dedicated design software for pebble bed high temperature gas-cooled reactors (e.g., VSOP program), and then the material distribution of the reactor core fuel is calculated based on the reactor operation model, so that the calculated data can be used as modeling input for subsequent Monte Carlo models.

[0047] It should be noted that, since the pebble bed high temperature gas-cooled reactor adopts the technology of continuous loading and refueling, the fuel elements in the core are constantly moving, and there are different batches of fuel elements in the core, and the burnup and material composition of each batch of fuel elements are different. However, the Monte Carlo software used in the subsequent application cannot accurately input the nuclear fuel composition, so this step uses the special design software for the pebble bed high temperature gas-cooled reactor to obtain the nuclear fuel composition of the core, which is used as the nuclear fuel composition input for the Monte Carlo modeling in the subsequent steps.

[0048] In one embodiment of the present application, the constructed reactor model includes a VSOP calculation model, and the nuclear fuel composition distribution of the core is calculated based on the reactor model, including: dividing the core of the spherical bed high temperature gas-cooled reactor into multiple units based on the VSOP calculation model, wherein the multiple units include different reflection layers and channels of the core; inputting the material composition information of each unit into the VSOP calculation model, and calculating the nuclear fuel composition distribution of the core through the operation program of the VSOP calculation model.

[0049] Specifically, as an example, one can construct Figure 6 The VSOP calculation model of the pebble bed high temperature gas-cooled reactor shown in the figure is composed of Figure 6 It can be seen that this model is used to divide the core into different layers and channels. Figure 6 The material composition of each unit is filled in the model, including the molecular formula, density and other information of the unit material, and then the VSOP program can calculate the distribution of the core fuel.

[0050] Step S102, through the Monte Carlo MC application, the core fuel distribution of the pebble bed high temperature gas-cooled reactor is arranged twice in a non-uniform manner to construct a core MC model, and the nuclear fuel composition distribution of the core is transferred to the core MC model to obtain a target Monte Carlo model for isotope irradiation production.

[0051] Specifically, a Monte Carlo (MC) model of isotope irradiation production of a pebble bed high temperature gas-cooled reactor is established using Monte Carlo (MC) software, such as MCNP or OpenMC, and the reactor nuclear material composition calculated in step S101, that is, the target Monte Carlo model in this application.

[0052] It should be noted that the design software of the pebble bed high temperature gas-cooled reactor cannot calculate the neutron collision heat of the isotope target, the gamma ray heat of the prompt neutron, and the gamma ray heat of the delayed neutron due to functional reasons. Therefore, the present application uses the Monte Carlo program to calculate the energy deposition heat release rate of the irradiated target. In addition, the Monte Carlo program can be used to refine the modeling and solve the dual non-uniformity problem of the subordinate pebble bed high temperature gas-cooled reactor.

[0053] In the specific implementation, the core nuclear fuel composition data calculated in step S101 is first mapped to the constructed MC model according to the spatial coordinates based on the existing VSOP grid division scheme, so as to calculate the relevant heat release of the irradiated target based on the high-precision characteristics of the MC algorithm.

[0054] In one embodiment of the present application, the fuel composition distribution of the core calculated in the above steps includes: nuclear fuel composition information of each batch in different areas, and the nuclear fuel composition distribution of the core is transferred to the core MC model, including: matching the coordinates of the core MC model and the VSOP calculation model to correspond to the fuel element model architecture of different areas; mapping the nuclear fuel composition information of each batch in each area calculated by the VSOP calculation model to the core MC model through a script program.

[0055] Specifically, in this embodiment, the first step is to use the MC algorithm to sample the positions of the spherical elements in the core layout plan, and then match them with the coordinates (including R coordinates and Z coordinates) of the above VSOP model to correspond to the fuel element model of the region. In the VSOP model, R and Z are usually used to describe the geometric structure of the reactor and the coordinate direction in the neutron transport process. The second step is, Figure 7As shown, the VSOP model above calculates the nuclear fuel composition information of each batch in each region, and the nuclear fuel composition information of each region is mapped to the MC model preliminarily constructed in the first step through a python script to achieve the unification of the nuclear fuel composition within the region.

[0056] It should be noted that the MC program has a built-in sampling algorithm. If relevant settings are made in the input card of the MC program, the program can perform sampling as required. The first step in this embodiment is to obtain the framework structure of the fuel element model calculated by VSOP through coordinate matching after sampling, and then fill in the specific nuclear fuel composition information in the MC model through the mapping operation of the second step, so as to obtain the final target Monte Carlo model. Therefore, this application couples the VSOP program and the MC algorithm for calculation, which can give full play to the strengths of the two programs.

[0057] It should also be noted that the pebble bed high temperature gas-cooled reactor adopts non-stop loading and unloading, which is different from the conventional reactor with shutdown and unloading. Its core pebble bed has the characteristics of random discreteness and macroscopic uniformity. In addition, Figure 1 As shown, there are tens of thousands of coated fuel particles (TRISO) in the spherical fuel elements of the pebble bed high temperature gas-cooled reactor. The distribution of these particles will cause errors when calculated using a uniform distribution model. The above two points are called the dual non-uniformity of the pebble bed high temperature gas-cooled reactor.

[0058] Based on the material layout of the pebble bed high temperature gas-cooled reactor, the use of the interval nuclide uniform distribution model will lead to large errors in the diffusion length and the slowing down length, which will lead to deviations in the macroscopic cross section and affect the accuracy of the calculation results. For this reason, this application adopts two non-uniform layouts.

[0059] That is, in one embodiment of the present application, the core fuel distribution of a pebble bed high-temperature gas-cooled reactor is arranged non-uniformly twice, including: first, a Monte Carlo MC application is used to sample the geometric coordinates of the coated fuel particles in a single spherical fuel element in the core, and a fuel element model that conforms to the probability distribution of the coated fuel particles is established; and then the pebble bed in the core is arranged at a preset filling rate, and the Monte Carlo MC application is used to sample the geometric coordinates of the spherical fuel elements in the pebble bed, and a core MC model containing isotope targets is established.

[0060] Specifically, this embodiment can be a specific implementation scheme for the first step of sampling in the above embodiment. The first non-uniform arrangement is to construct a spherical fuel element model, and through the geometric coordinate sampling of the MC program, a fuel element model in which TRISO particles meet the probability distribution is established. Its geometric model is as follows: Figure 8Compared with the arrangement scheme of homogenized materials of fuel elements, the refined geometric model constructed in this application can improve the accuracy of burnup calculation while meeting the accuracy of migration length.

[0061] The second non-uniform arrangement is to build a pebble bed core model. The pebble bed is arranged with a filling rate of 0.61. The geometric coordinates of the spherical fuel elements are sampled according to the same algorithm of the MC program. The core model of the pebble bed high temperature gas-cooled reactor containing isotope targets is established as follows: Fig. 9 shown.

[0062] Step S103, calculating various energy deposition heat release rates of isotope irradiation targets of the pebble bed high temperature gas-cooled reactor by using the target Monte Carlo model, and calculating various decay heat release rates of isotopes generated by irradiation by using the relevant calculation results of the Monte Carlo MC application program.

[0063] Specifically, the energy deposition heat release rate of the pebble bed high temperature gas-cooled reactor isotope target is calculated. After the target Monte Carlo model is established in step S102, the above-mentioned various energy depositions of the high temperature gas-cooled reactor isotope irradiation target are accurately calculated through the MC program.

[0064] For example, by calculating the target Monte Carlo model 130 Production of Radioisotopes by Irradiation of Te Targets in a Pebble Bed High Temperature Gas-Cooled Reactor 131 The energy deposition of I is about 0.42 W cm -3 .

[0065] Furthermore, the isotope decay heat is calculated.

[0066] It should be noted that the MC program can only calculate the energy deposition of neutrons, gamma rays and electrons, and cannot track the decay of isotopes generated by irradiation. Isotopes generated by irradiation may decay into α, β and γ and various combinations thereof to release heat, which can be obtained by theoretical calculation. The relevant data such as the thermal neutron injection rate of the target used in the calculation process can be calculated by the MC program in step S102.

[0067] The calculation method of heat released by various types of decay of each irradiated isotope is the same. To facilitate the description of the calculation process, as an example, the following is combined with radioactive isotopes 131 The calculation process of β heat release of I is explained in detail.

[0068] In one embodiment of the present application, calculating multiple decay heat release rates of isotopes generated by irradiation includes the following steps:

[0069] The first step is to respectively determine the equations for the change of the number of pronuclei of any isotope and the isotope target used to produce the isotope over time.

[0070] Specifically, in this example, currently, irradiation is generally performed in a reactor. 130 Te Target Production of Radioisotopes 131 I. 130 Te(n,γ) 131 I generated 131 I will continue to β decay to produce 131 Xe releases decay heat and determines the nuclide 130 Te and 131 The equations for the change of the number of nucleons of I with time are shown in the following formulas:

[0071]

[0072] Among them, N 1 and N 2 At time t 130 Te, 131 I's nuclear density (the number of nuclei per cubic centimeter); σ 1 for 130 Te thermal neutron capture cross section (b); is the thermal neutron flux rate (n·cm -2 ·s -1 ); 2 for 131 The decay constant of I (s -1 );t is time (s).

[0073] The second step is to determine the nuclear density function of any isotope and isotope target with respect to time based on the corresponding equation for the change of the number of pronucleons with time.

[0074] In one embodiment of the present application, determining the nuclear density function of any isotope and isotope target with respect to time includes: determining the nuclear density of any isotope and isotope target at an initial moment, substituting the nuclear density of any isotope and isotope target at the initial moment into the corresponding change equation, and solving the nuclear density function of any isotope and isotope target.

[0075] Specifically, in this example, determine N 1 (0) = N 10 , N 2 (0) = 0, N 10 yes 130 The number of Te atoms at the initial moment can be determined by relevant detection methods. 1 (0) = N 10 and N 2 Substitute (0)=0 into the equation of the change of the number of pronuclear electrons over time in the first step, and we get 130 Te and131 The atomic nuclear density functions of I are shown in the following formulas:

[0076]

[0077]

[0078] The third step is to construct the nuclear density balance equation based on the fact that the decay rate of any isotope is equal to the production rate.

[0079] Specifically, in this example, when 131 The decay rate λ of I 2 N 2 (t) is equal to the generation rate When 131 I The density of nuclei reaches equilibrium. 131 The penetration ability of the β particles produced by I decay is weak, and all of its β decay heat is deposited in the target material. Therefore, the nuclear density balance equation is constructed as follows:

[0080] The fourth step is to calculate the decay heat release rate of any isotope by combining the relevant calculation results of the Monte Carlo MC application, the nuclear density function and the nuclear density balance equation.

[0081] In one embodiment of the present application, the decay heat release rate of any isotope species is calculated, including: substituting the thermal neutron fluence rate, equilibrium concentration and nuclear density function into the nuclear density equilibrium equation to calculate the time value for reaching nuclear density equilibrium; calculating the nuclear density and decay rate of any isotope at the time value, and calculating the decay heat release rate of any isotope based on the calculated nuclear density and decay rate at the time value.

[0082] Specifically, in this example, the MC application in step S102 can calculate the current hour, 131 The equilibrium concentration of I is about 1.48 Ci / g. Substituting the two obtained data and the nuclear density function determined in the second step into the third step, we get the nuclear density equilibrium equation The time value t that makes the nuclear density equilibrium equation valid can be calculated. Then the calculated time value t is substituted into the calculation formula of the nuclear density and decay rate in the second and third steps above to obtain the nuclear density and decay rate under the time value t, and then the result can be calculated. 131 For example, under the above values ​​of thermal neutron flux rate and corresponding equilibrium concentration, the calculated 131 The β decay heat of I is about 1.01×10 -5 W cm -3 .

[0083] It should be noted that in a nuclear reactor, the heat release rate in the fuel element is proportional to the nuclear density N. After calculating the nuclear density and decay rate at the above time value t, the decay heat release rate can be calculated through relevant algorithms.

[0084] Step S104, adding a plurality of energy deposition heat release rates and a plurality of decay heat release rates to obtain the isotope irradiation target heat release rate of the pebble bed high temperature gas-cooled reactor.

[0085] Specifically, the energy deposition heat release rate of the high temperature gas-cooled reactor isotope irradiation target and the isotope decay heat release rate calculated in step S103 are added together to obtain the total heat release rate of the pebble bed high temperature gas-cooled reactor isotope irradiation target.

[0086] Continuing with the above example, 130 Production of Radioisotopes by Irradiation of Te Targets in a Pebble Bed High Temperature Gas-Cooled Reactor 131 The total heat release rate of I is 0.42+1.01×10 -5 =0.4200101W·cm -3 .

[0087] Therefore, the method for calculating the heat release rate of the isotope irradiation target of the pebble bed high temperature gas-cooled reactor of the present application can be smoothly executed in the required program software and theoretical calculations, and has the feasibility of accurately calculating the heat release rate of the isotope irradiation target.

[0088] In summary, the calculation method of the heat release rate of the isotope irradiation target of the pebble bed high temperature gas-cooled reactor in the embodiment of the present application comprehensively considers the dual non-uniformity and non-stop refueling characteristics of the pebble bed high temperature gas-cooled reactor. The composition distribution of the nuclear fuel in the reactor is first calculated by the special design software for the pebble bed high temperature gas-cooled reactor, and then the various energy deposition heat release rates of the isotope irradiation target of the high temperature gas-cooled reactor are calculated by the Monte Carlo model. Then, the calculation results of the Monte Carlo model are used to calculate the heat release rates of various isotope decays, and finally the total heat release rate of the isotope irradiation target is calculated by combining the two heat release rates. Therefore, this method accurately calculates various types of heat generation of the isotope target during the irradiation process according to the characteristics of the pebble bed high temperature gas-cooled reactor, and significantly reduces the error in the calculation results. This method clarifies the calculation process of the heat release rate of the isotope irradiation target, and ensures the accuracy of the calculation results of the heat release rate of the isotope irradiation target, providing a data basis for the subsequent temperature analysis of the irradiated target. Therefore, this method is conducive to the irradiation production of isotopes in the pebble bed type high temperature gas-cooled reactor, and helps to improve the safety of the irradiation production process of isotopes in the pebble bed type high temperature gas-cooled reactor.

[0089] In order to implement the above embodiment, the present application also proposes a calculation system for the heat release rate of isotope irradiation targets of a pebble bed high temperature gas-cooled reactor. Fig.10A schematic diagram of a calculation system for the heat release rate of a target for isotope irradiation in a pebble bed high temperature gas-cooled reactor proposed in an embodiment of the present application is shown in FIG. Fig.10 As shown, the system includes: a first building module 100 , a second building module 200 , a first computing module 300 and a second computing module 400 .

[0090] Among them, the first construction module 100 is used to construct a reactor model of the pebble bed high temperature gas-cooled reactor to be calculated through a special design application for the pebble bed high temperature gas-cooled reactor, and calculate the nuclear fuel composition distribution of the core based on the reactor model.

[0091] The second construction module 200 is used to perform two non-uniform arrangements of the core fuel distribution of the pebble bed high temperature gas-cooled reactor through a Monte Carlo MC application to construct a core MC model, and transfer the nuclear fuel composition distribution of the core to the core MC model to obtain a target Monte Carlo model for isotope irradiation production.

[0092] The first calculation module 300 is used to calculate various energy deposition heat release rates of isotope irradiation targets of a pebble bed high temperature gas-cooled reactor through a target Monte Carlo model, and to calculate various decay heat release rates of isotopes generated by irradiation using relevant calculation results of a Monte Carlo MC application program.

[0093] The second calculation module 400 is used to add a plurality of energy deposition heat release rates and a plurality of decay heat release rates to obtain the isotope irradiation target heat release rate of the pebble bed high temperature gas-cooled reactor.

[0094] Optionally, in one embodiment of the present application, the first construction module 100 is specifically used to: divide the core of the spherical bed high temperature gas-cooled reactor into a plurality of units based on the VSOP calculation model, wherein the plurality of units include different reflection layers and channels of the core; input the material composition information of each unit into the VSOP calculation model, and calculate the nuclear fuel composition distribution of the core through the operation program of the VSOP calculation model.

[0095] Optionally, in one embodiment of the present application, the second construction module 200 is specifically used to: match the coordinates of the core MC model and the VSOP calculation model to correspond to the fuel element model architecture of different regions; and map the nuclear fuel composition information of each batch in each region calculated by the VSOP calculation model to the core MC model through a script program.

[0096] Optionally, in one embodiment of the present application, the second construction module 200 is further used to: perform geometric coordinate sampling of coated fuel particles in a single spherical fuel element in the core through a Monte Carlo MC application, and establish a fuel element model that conforms to the probability distribution of the coated fuel particles; arrange the pebble bed in the core with a preset filling rate, perform geometric coordinate sampling of the spherical fuel elements in the pebble bed through a Monte Carlo MC application, and establish a core MC model containing isotope targets.

[0097] Optionally, in one embodiment of the present application, the first calculation module 300 is specifically used to: determine the equations for the change of the number of pronucleons of any isotope and the isotope target for producing any isotope with time; determine the nuclear density function of any isotope and the isotope target with respect to time based on the corresponding equations for the change of the number of pronucleons with time; construct the nuclear density balance equation based on the fact that the decay rate of any isotope is equal to the generation rate; and calculate the decay heat release rate of any isotope by combining the relevant calculation results of the Monte Carlo MC application, the nuclear density function and the nuclear density balance equation.

[0098] Optionally, in one embodiment of the present application, the first calculation module 300 is specifically used to: substitute the thermal neutron fluence rate, equilibrium concentration and nuclear density function into the nuclear density equilibrium equation to calculate the time value for reaching nuclear density equilibrium; calculate the nuclear density and decay rate of any isotope at the time value, and calculate the decay heat release rate of any isotope based on the calculated nuclear density and decay rate at the time value.

[0099] It should be noted that the above explanation of the embodiment of the method for calculating the heat release rate of isotope irradiation target of a pebble bed high temperature gas-cooled reactor is also applicable to the system of this embodiment and will not be repeated here.

[0100] In summary, the calculation system of the heat release rate of the isotope irradiation target of the pebble bed high temperature gas-cooled reactor in the embodiment of the present application comprehensively considers the dual non-uniformity and non-stop refueling characteristics of the pebble bed high temperature gas-cooled reactor, and accurately calculates the various types of heat generation of the isotope target during the irradiation process according to the characteristics of the pebble bed high temperature gas-cooled reactor, significantly reducing the error in the calculation results. The system clarifies the calculation process of the heat release rate of the isotope irradiation target, and ensures the accuracy of the calculation results of the heat release rate of the isotope irradiation target, providing a data basis for the subsequent temperature analysis of the irradiated target.

[0101] In order to implement the above-mentioned embodiments, the present application also proposes a non-temporary computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, it implements the method for calculating the heat release rate of the isotope irradiation target of a pebble bed high-temperature gas-cooled reactor as described in any one of the above-mentioned first aspect embodiments.

[0102] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0103] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0104] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0105] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute the instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0106] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0107] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0108] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0109] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for calculating the heat release rate of isotope irradiation targets in a pebble bed high temperature gas-cooled reactor, characterized in that: The following steps are involved: A reactor model of a pebble-bed high-temperature gas-cooled reactor to be calculated is constructed through a special design application for a pebble-bed high-temperature gas-cooled reactor, and the distribution of nuclear fuel components in the core is calculated based on the reactor model; Through the Monte Carlo MC application program, the core fuel distribution of the pebble bed high temperature gas-cooled reactor is arranged twice in a non-uniform manner to construct a core MC model, and the nuclear fuel composition distribution of the core is transferred to the core MC model to obtain a target Monte Carlo model for isotope irradiation production; Calculating multiple energy deposition heat release rates of the isotope irradiation target of the pebble bed high temperature gas-cooled reactor by using the target Monte Carlo model, and calculating multiple decay heat release rates of the isotopes generated by irradiation by using the relevant calculation results of the Monte Carlo MC application program; The multiple energy deposition heat release rates and the multiple decay heat release rates are added together to obtain the isotope irradiation target heat release rate of the pebble bed high temperature gas-cooled reactor.

2. The method according to claim 1, characterized in that The reactor model includes a VSOP calculation model, and the calculation of the nuclear fuel composition distribution of the core based on the reactor model includes: Dividing the core of a spherical bed high temperature gas-cooled reactor into a plurality of units based on the VSOP calculation model, wherein the plurality of units include different reflection layers and channels of the core; The material composition information of each unit is input into the VSOP calculation model, and the nuclear fuel composition distribution of the core is calculated through the operation program of the VSOP calculation model.

3. The method according to claim 2, characterized in that The fuel composition distribution of the core includes: nuclear fuel composition information of each batch in different regions, and the transferring of the nuclear fuel composition distribution of the core to the core MC model includes: Matching the coordinates of the core MC model with those of the VSOP calculation model to correspond to the fuel element model frameworks of different regions; The nuclear fuel composition information of each batch in each area calculated by the VSOP calculation model is mapped to the core MC model through a script program.

4. The method according to claim 1, characterized in that: The method of performing two non-uniform arrangements on the core fuel distribution of the pebble bed type high temperature gas-cooled reactor comprises: By using the Monte Carlo MC application program, geometric coordinate sampling is performed on coated fuel particles in a single spherical fuel element in a core, and a fuel element model conforming to the probability distribution of the coated fuel particles is established; The pebble bed in the core is arranged at a preset filling rate, and the geometric coordinates of the spherical fuel elements in the pebble bed are sampled by the Monte Carlo MC application program to establish the core MC model containing isotope targets.

5. The method according to claim 1, characterized in that The calculation of multiple decay heat release rates of isotopes generated by irradiation includes: Determine respectively the equation of the change of the number of pronuclei of any isotope and the isotope target for producing said any isotope with time; Determining the atomic nucleus density function of any one of the isotopes and the isotope target with respect to time according to the corresponding equation of the change of the number of pronuclei with time; Based on the decay rate of any isotope being equal to the generation rate, constructing a nuclear density balance equation; The decay heat release rate of any isotope is calculated by combining the relevant calculation results of the Monte Carlo MC application, the atomic nuclear density function and the atomic nuclear density balance equation.

6. The method according to claim 5, characterized in that The determining of the nuclear density function of any one of the isotopes and the isotope target with respect to time comprises: Determine the nuclear density of any isotope and the isotope target at the initial moment, substitute the nuclear density of any isotope and the isotope target at the initial moment into the corresponding change equation, and solve the nuclear density function of any isotope and the isotope target.

7. The method according to claim 5, characterized in that The relevant calculation results of the Monte Carlo MC application program include: thermal neutron fluence rate and the equilibrium concentration corresponding to the thermal neutron fluence rate, and the calculation of the decay heat release rate of any isotope species includes: Substituting the thermal neutron fluence rate, the equilibrium concentration and the atomic nucleus density function into the atomic nucleus density equilibrium equation to calculate the time value for reaching atomic nucleus density equilibrium; Calculate the atomic nuclear density and decay rate of any one of the isotopes at the time value, and calculate the decay heat release rate of any one of the isotopes based on the calculated atomic nuclear density and decay rate at the time value.

8. A calculation system for the heat release rate of isotope irradiation targets in a pebble bed high temperature gas-cooled reactor, characterized in that: Includes the following modules: The first construction module is used to construct a reactor model of a pebble bed high temperature gas-cooled reactor to be calculated through a special design application for a pebble bed high temperature gas-cooled reactor, and calculate the distribution of nuclear fuel components in the core based on the reactor model; The second construction module is used to perform two non-uniform arrangements on the core fuel distribution of the pebble bed high temperature gas-cooled reactor through a Monte Carlo MC application program to construct a core MC model, and transfer the nuclear fuel composition distribution of the core to the core MC model to obtain a target Monte Carlo model for isotope irradiation production; A first calculation module is used to calculate multiple energy deposition heat release rates of the isotope irradiation target of the pebble bed high temperature gas-cooled reactor by using the target Monte Carlo model, and to calculate multiple decay heat release rates of the isotopes generated by irradiation by using the relevant calculation results of the Monte Carlo MC application program; The second calculation module is used to add the multiple energy deposition heat release rates and the multiple decay heat release rates to obtain the isotope irradiation target heat release rate of the pebble bed high temperature gas-cooled reactor.

9. The system according to claim 8, characterized in that The first building module is specifically used for: Dividing the core of a spherical bed high temperature gas-cooled reactor into a plurality of units based on the VSOP calculation model, wherein the plurality of units include different reflection layers and channels of the core; The material composition information of each unit is input into the VSOP calculation model, and the nuclear fuel composition distribution of the core is calculated through the operation program of the VSOP calculation model.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for calculating the heat release rate of an isotope irradiated target of a pebble bed high temperature gas-cooled reactor as described in any one of claims 1 to 7 is implemented.

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