Method for calculating heat release rate of isotope irradiation target in pebble bed high temperature gas cooled reactor

Abstract

The application provides a calculation method of a pebble bed high-temperature gas cooled reactor isotope irradiation target heat release rate, which comprises the following steps: constructing a reactor model of the pebble bed high-temperature gas cooled reactor through a special design application to calculate the nuclear fuel composition distribution of the reactor core; performing twice non-uniform arrangement on the fuel distribution of the reactor core through an MC application program to construct a reactor core MC model and transferring the nuclear fuel composition distribution of the reactor core to the reactor core MC model; calculating the energy deposition heat release rate of the isotope irradiation target through a Monte Carlo model for isotope irradiation production and the decay heat release rate of the isotope generated by irradiation; and adding the energy deposition heat release rate and the decay heat release rate to obtain the isotope irradiation target heat release rate of the pebble bed high-temperature gas cooled reactor. The method can accurately calculate the heat release rate of the isotope irradiation target in view of the double non-uniformity and the non-stop reactor refueling characteristics of the pebble bed high-temperature gas cooled reactor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of physical and thermal parameter calculation of radioisotope targets, and particularly relates to a method for calculating heat release rate of an isotope irradiation target of a pebble bed high temperature gas cooled reactor. BACKGROUND

[0002] At present, a pebble bed high temperature gas cooled reactor generally adopts spherical fuel elements (referred to as fuel balls), as shown in FIG. 1. Figure 1 As shown in FIG. 2, a half ball after cutting of the fuel ball includes a fuel-free area 11 on the outside and a fuel area 12 on the inside, and the fuel area 12 has a plurality of coated fuel particles, which include, from the outside to the inside, an outer dense PC layer 13, a SiC layer 14, an inner dense PC layer 15, a loose PC layer 16 and a UO2 core. y As shown in FIG. 2, a half ball after cutting of the fuel ball includes a fuel-free area 11 on the outside and a fuel area 12 on the inside, and the fuel area 12 has a plurality of coated fuel particles, which include, from the outside to the inside, an outer dense PC layer 13, a SiC layer 14, an inner dense PC layer 15, a loose PC layer 16 and a UO2 core. y As shown in FIG. 2, a half ball after cutting of the fuel ball includes a fuel-free area 11 on the outside and a fuel area 12 on the inside, and the fuel area 12 has a plurality of coated fuel particles, which include, from the outside to the inside, an outer dense PC layer 13, a SiC layer 14, an inner dense PC layer 15, a loose PC layer 16 and a UO2 core. y The core structure of the pebble bed high temperature gas cooled reactor can be simply described as a cylindrical pebble bed in the core center randomly stacked by spherical fuel elements, as shown in FIG. 3. Figure 2 As shown in FIG. 4, the outside of the pebble bed is sequentially provided with a graphite internal structure, a carbon internal structure, a metal internal structure and a reactor pressure vessel. The graphite internal structure includes a top reflection layer 21, a side reflection layer 22 and a bottom reflection layer 23, as shown in FIG. 5. Figure 3 As shown in FIG. 5, the side reflection layer 22 of the graphite internal structure is provided with a control rod hole 31, an absorbing ball hole 32, a cold helium gas hole 33, a neutron source hole 34 and a physical starting device hole 35.

[0003] Among them, at the first criticality of the pebble bed high temperature gas cooled reactor, the neutron source hole 34 and the physical starting device hole 35 (the structure and distribution diameters of the two are the same) are provided with a neutron source and a physical starting neutron counting tube. In the running process after the reactor is critical, the neutron source and the physical starting neutron counting tube will be moved out of the side reflection layer 22, that is, the corresponding neutron source hole and the physical starting device hole are empty.

[0004] According to the reactor physics parameter calculation, the thermal neutron flux of the neutron source hole and the physical starting device hole is considerable, and is comparable to the thermal neutron flux in the reactor core, as shown in FIG. 6. Figure 4 Therefore, the two holes can be used for isotope production through modification. For a newly built pebble bed high temperature gas cooled reactor, isotope production in the side reflection layer can be considered in the design. The isotope irradiation target is loaded into the hole for irradiation, and the corresponding isotope can be produced. Further, through the production of isotopes, the revenue of the pebble bed high temperature gas cooled reactor nuclear power plant can be increased, and the operation benefit of the nuclear power plant is greatly improved.

[0005] In practical applications, the isotope irradiation target will generate heat during the irradiation process due to nuclear reactions and nuclear radiation, resulting in an increase in the temperature of the target. In order to avoid problems such as material thermal damage and deformation, equipment failure, radioactive leakage, and impact on the safe operation of the reactor during the irradiation process, it is necessary to calculate the heat release rate of the isotope irradiation target and analyze the temperature distribution of the irradiation target. However, since the pebble bed high temperature gas cooled reactor is a new type of reactor, there is currently no precedent for using such a reactor for isotope irradiation production, and therefore there is a lack of calculation schemes for the heat release rate of the isotope irradiation target of the pebble bed high temperature gas cooled reactor in the related art. SUMMARY

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

[0007] To this end, a first object of the present application is to propose a method for calculating the heat release rate of an isotope irradiation target of a pebble bed high temperature gas cooled reactor. The method takes into account the dual non-uniformity and non-stop refueling characteristics of the pebble bed high temperature gas cooled reactor, and clearly defines how to carry out the heat release rate calculation of the target under isotope irradiation production in the pebble bed high temperature gas cooled reactor, so as to accurately calculate the heat release rate of the isotope irradiation target.

[0008] A second object of the present application is to propose a system for calculating the heat release rate of an isotope irradiation target of a pebble bed high temperature gas cooled reactor.

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

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

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

[0012] The fuel distribution of the core of the pebble bed high temperature gas cooled reactor is arranged twice for non-uniformity through a Monte Carlo (MC) application program, to construct a core MC model, and the nuclear fuel composition distribution of the core is transmitted to the core MC model to obtain a target Monte Carlo model for isotope irradiation production;

[0013] A plurality of energy deposition heat release rates of the isotope irradiation target of the pebble bed high temperature gas cooled reactor are calculated through the target Monte Carlo model, and a plurality of decay heat release rates of the isotope generated by irradiation are calculated using the relevant calculation results of the Monte Carlo MC application program;

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

[0015] Optionally, in an embodiment of the present application, the reactor model comprises a VSOP calculation model, and the calculation of the nuclear fuel composition distribution of the reactor core based on the reactor model comprises: dividing the reactor core of the pebble bed high temperature gas cooled reactor into a plurality of units based on the VSOP calculation model, wherein the plurality of units comprise different reflector layers and channels of the reactor core; inputting material composition information of each unit into the VSOP calculation model, and calculating the nuclear fuel composition distribution of the reactor core by an operation program of the VSOP calculation model.

[0016] Optionally, in an embodiment of the present application, the fuel composition distribution of the reactor core comprises nuclear fuel composition information of each batch in different regions, and the transmission of the nuclear fuel composition distribution of the reactor core into the reactor core MC model comprises: matching the reactor core MC model with coordinates of the VSOP calculation model to correspond to fuel element model architectures of different regions; and mapping the nuclear fuel composition information of each batch in each region calculated by the VSOP calculation model into the reactor core MC model by a script program.

[0017] Optionally, in an embodiment of the present application, the twice non-uniform arrangement of the fuel distribution of the reactor core of the pebble bed high temperature gas cooled reactor comprises: sampling geometric coordinates of coated fuel particles in a single spherical fuel element in the reactor core by a Monte Carlo (MC) application program to establish a fuel element model conforming to a probability distribution of the coated fuel particles; arranging a pebble bed in the reactor core at a preset filling rate, sampling geometric coordinates of spherical fuel elements in the pebble bed by the Monte Carlo (MC) application program to establish the reactor core MC model containing isotope targets.

[0018] Optionally, in an embodiment of the present application, the calculation of the plurality of decay heat release rates of the generated isotopes comprises: respectively determining a time-varying equation of a number of nuclei of any isotope and an isotope target producing the any isotope; determining a time-varying nuclear density function of the any isotope and the isotope target based on the corresponding time-varying equation of the number of nuclei; constructing a nuclear density balance equation based on the fact that a decay rate of the any isotope is equal to a generation rate; and combining a related calculation result of the Monte Carlo (MC) application program, the nuclear density function and the nuclear density balance equation to calculate the decay heat release rate of the any isotope.

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

[0020] Optionally, in an embodiment of the present application, the relevant calculation result of the Monte Carlo (MC) application program comprises: a thermal neutron fluence rate and a corresponding equilibrium concentration of the thermal neutron fluence rate, and the calculation of the decay heat release rate of the any isotope comprises: substituting the thermal neutron fluence rate, the equilibrium concentration and the nuclear density function into the nuclear density balance equation to calculate a time value at which the nuclear density reaches balance; calculating the nuclear density and decay rate of the any isotope at the time value, and calculating the decay heat release rate of the any isotope based on the calculated nuclear density and decay rate at the time value.

[0021] To achieve the above object, a second aspect of the present application further provides a calculation system for heat release rate of an isotope irradiation target of a pebble bed high temperature gas cooled reactor, comprising the following modules:

[0022] A first construction module is configured to construct a reactor model of a pebble bed high temperature gas cooled reactor to be calculated by using a special design application of the pebble bed high temperature gas cooled reactor, and calculate a nuclear fuel composition distribution of a core based on the reactor model;

[0023] A second construction module is configured to perform twice non-uniform arrangement on a fuel distribution of the core of the pebble bed high temperature gas cooled reactor by using a Monte Carlo (MC) application program to construct a core MC model, and transfer the nuclear fuel composition distribution of the core into the core MC model to obtain a target Monte Carlo model for isotope irradiation production;

[0024] A first calculation module is configured to calculate a plurality of energy deposition heat release rates of an isotope irradiation target of the pebble bed high temperature gas cooled reactor by using the target Monte Carlo model, and calculate a plurality of decay heat release rates of an irradiation generated isotope by using a relevant calculation result of the Monte Carlo (MC) application program;

[0025] A second calculation module is configured to add the plurality of energy deposition heat release rates and the plurality of decay heat release rates to obtain a heat release rate of the isotope irradiation target of the pebble bed high temperature gas cooled reactor.

[0026] To achieve the above-embodiment, the third aspect of the present application also provides a non-transitory computer-readable storage medium having a computer program stored thereon, wherein the computer program is executed by a processor to implement the method for calculating the heat release rate of the pebble bed high temperature gas cooled reactor isotope irradiation target in the first aspect.

[0027] The technical scheme provided by the embodiment of the present application at least brings the following beneficial effects: the double non-uniformity and the non-stop refueling characteristics of the pebble bed high temperature gas cooled reactor are comprehensively considered, the composition distribution of the core fuel in the reactor is calculated through the special design software for the pebble bed high temperature gas cooled reactor, the energy deposition heat release rate of the high temperature gas cooled reactor isotope irradiation target is calculated through the Monte Carlo model, then the calculation results of the Monte Carlo model are used to calculate the isotope decay heat release rate, and finally the total heat release rate of the isotope irradiation target is calculated by comprehensively calculating the two kinds of heat release rates. Thus, the present application accurately calculates various types of heat generated by the isotope target during irradiation according to the characteristics of the pebble bed high temperature gas cooled reactor, and significantly reduces the error in the calculation results. The present application clearly defines the calculation process of the isotope irradiation target heat release rate, and ensures the accuracy of the calculation results of the isotope irradiation target heat release rate, which provides a data basis for subsequent temperature analysis of the irradiation target. Thus, the present application is conducive to the irradiation production of isotopes of the pebble bed high temperature gas cooled reactor, and helps to improve the safety of the isotope irradiation production process of the pebble bed high temperature gas cooled reactor.

[0028] Additional aspects and advantages of the present application will be made apparent from the following description, which proceeds with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

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

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

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

[0032] Figure 3 A schematic diagram of a side reflector channel structure of a pebble bed high temperature gas cooled reactor is provided for an example of the present application;

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

[0034] Figure 5 A flowchart of a method for calculating the heat release rate of an isotope irradiation target of a pebble bed high temperature gas cooled reactor is provided for an embodiment of the present application;

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

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

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

[0038] Figure 9 A schematic diagram of a core MC model containing an isotope target proposed for an embodiment of the present application;

[0039] Figure 10 A structural schematic diagram of a calculation system for the heat release rate of an isotope irradiation target of a pebble bed type high temperature gas cooled reactor proposed for an embodiment of the present application. DETAILED DESCRIPTION

[0040] Embodiments of the present application are described in detail below with reference to examples thereof illustrated in the attached drawings, in which the same or similar components have the same or similar designations throughout, and a description of an embodiment described below by reference to the drawings is intended to explain the present application, and cannot be understood as a limitation thereof.

[0041] It should be noted that the present application analyzes and studies the heat generated by nuclear reactions and nuclear radiation of an isotope irradiation target during irradiation, determines the generated heat including heat generation of the target core material, the cladding material and the structural member, and the heat generation rate is mainly related to the nuclear reactor operation power, the material nuclear characteristics and the irradiation position and other factors. According to the energy deposition time, it can be divided into two parts of prompt and delayed. The neutrons generated in the process of neutron fission and neutron capture during the in-core irradiation process are the main source of prompt heat; and the delayed heat is mainly derived from neutron activation products and fission products. According to the energy deposition form, the nuclear heat can be divided into four parts of neutron (n) collision heat, prompt neutron (n) gamma ray (γ) heat, delayed neutron (n) gamma ray (γ) heat and decay heat of radioisotopes, wherein the decay heat of isotopes includes different types of decay heat of helium nuclei (α), electrons (β) and gamma rays (γ).

[0042] Based on this, the present application proposes a calculation method for the heat release rate of an isotope irradiation target of a pebble bed type high temperature gas cooled reactor, so as to carry out the isotope irradiation production of the pebble bed type high temperature gas cooled reactor and improve the safety of the isotope irradiation production.

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

[0044] Figure 5 This is a flowchart illustrating a method for calculating the heat release rate of an isotope irradiation target in a pebble bed type high-temperature gas-cooled reactor, as proposed in an embodiment of this application. Figure 5 As shown, the method includes the following steps:

[0045] Step S101: Using the dedicated design application for pebble bed high-temperature gas-cooled reactors, construct the reactor model of the pebble bed high-temperature gas-cooled reactor to be calculated, and calculate the nuclear fuel composition distribution of the reactor 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 (such as the VSOP program). The material distribution of the reactor core fuel is then calculated based on the reactor operation model, so that the calculated data can be used as input for subsequent Monte Carlo modeling.

[0047] It should be noted that, because pebble bed high-temperature gas-cooled reactors employ continuous refueling technology, the fuel elements in the core are constantly in motion. Different batches of fuel elements exist within the core, each with varying burnup and material composition. Since the Monte Carlo software subsequently used in this application cannot accurately input the nuclear fuel composition, this step employs specialized design software for pebble bed high-temperature gas-cooled reactors to obtain the core's nuclear fuel composition, which will then serve as the input for Monte Carlo modeling in subsequent steps.

[0048] In one embodiment of this application, the constructed reactor model includes a VSOP calculation model. The calculation of the nuclear fuel composition distribution of the reactor core based on the reactor model includes: dividing the core of the ball-bed high-temperature gas-cooled reactor into multiple units based on the VSOP calculation model, wherein the multiple units include different reflector 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 calculation program of the VSOP calculation model.

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

[0050] In step S102, the core fuel distribution of the pebble bed type high temperature gas cooled reactor is arranged twice by a Monte Carlo (MC) application program to construct a core MC model, and the nuclear fuel composition distribution of the core is transmitted to the core MC model to obtain a target Monte Carlo model for isotope irradiation production.

[0051] Specifically, a Monte Carlo (MC) software such as MCNP or OpenMC is used to establish a Monte Carlo model for isotope irradiation production of the pebble bed type high temperature gas cooled reactor, i.e., the target Monte Carlo model in the present application, by using the nuclear material composition of the reactor calculated in step S101.

[0052] It should be noted that the design software of the pebble bed type 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 Monte Carlo program is used to calculate the energy deposition heat release rate of the irradiation target. Moreover, the Monte Carlo program can be used to establish a fine model to solve the double non-uniformity problem of the pebble bed type high temperature gas cooled reactor.

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

[0054] In an embodiment of the present application, the fuel composition distribution of the core calculated in the above step includes the nuclear fuel composition information of each batch in different regions. Transmitting the nuclear fuel composition distribution of the core to the core MC model includes matching the coordinates of the core MC model and the VSOP calculation model to correspond to the fuel element model architecture of different regions, and mapping the nuclear fuel composition information of each batch in each region calculated by the VSOP calculation model to the core MC model by a script program.

[0055] Specifically, in the present embodiment, in the first step, the position of the spherical element in the core arrangement scheme is sampled by using the MC algorithm, and then matched 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 coordinates of the reactor geometry and the coordinate direction in the neutron transport process. In the second step, the nuclear fuel composition information of each batch in each region calculated by the VSOP model is mapped to the core MC model by using a script program. Figure 7As shown, for the VSOP model calculation of each batch of nuclear fuel composition information in each region, 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 realize the unification of the nuclear fuel composition in the region.

[0056] It should be noted that the MC program has a built-in sampling algorithm, and the relevant settings are made in the input card of the MC program, and the program can sample according to the requirements. The first step in the embodiment is to correspond to the frame structure of the fuel element model calculated by VSOP after sampling through coordinate matching, and then fill the specific nuclear fuel composition information in the MC model through the mapping operation of the second step, thereby obtaining the final target Monte Carlo model. Therefore, the VSOP program and the MC algorithm are coupled for calculation, which can fully exert the advantages of the two programs.

[0057] It should be further noted that the spherical bed type high temperature gas cooled reactor adopts non-stop charging and discharging, which is different from the conventional stop charging and discharging reactor, and the core spherical bed has the characteristics of random dispersion and macroscopic uniformity. In addition, as shown in Figure 1 As shown, the spherical fuel element of the spherical bed type high temperature gas cooled reactor has tens of thousands of coated fuel particles (TRISO), and the distribution of these particles will bring errors when calculated by a uniform distribution model. The above two points are called double non-uniformity of the spherical bed type high temperature gas cooled reactor.

[0058] Further based on the material arrangement scheme of the spherical bed type high temperature gas cooled reactor, using the interval nuclide uniform distribution model will cause large errors in the diffusion length and the moderation length, and further cause deviations in the macroscopic cross section, affecting the calculation result precision. Therefore, the application adopts two non-uniformity arrangements.

[0059] That is, in an embodiment of the application, the core fuel distribution of the spherical bed type high temperature gas cooled reactor is arranged twice, including: first, the coated fuel particles in a single spherical fuel element in the core are sampled by the Monte Carlo MC application program to establish a fuel element model conforming to the probability distribution of the coated fuel particles; and second, the spherical bed in the core is arranged at a preset filling rate, and the spherical fuel element in the spherical bed is sampled by the Monte Carlo MC application program to establish a core MC model containing an isotope target.

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

[0061] The second non-homogeneous arrangement involved constructing a pebble bed core model. The pebble bed was arranged with a fill factor of 0.61. Geometric coordinate sampling of the spherical fuel elements was performed using the same algorithm as in the MC program. The resulting pebble bed high-temperature gas-cooled reactor core model, including isotope targets, is shown below. Figure 9 As shown.

[0062] Step S103: Calculate the various energy deposition heat release rates of the isotope irradiation target of the pebble bed type high-temperature gas-cooled reactor using the target Monte Carlo model, and calculate the various decay heat release rates of the irradiated isotopes using the relevant calculation results from the Monte Carlo MC application.

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

[0064] For example, calculations using a target Monte Carlo model 130 Te targets are used to produce radioisotopes by irradiation within a pebble bed type high-temperature gas-cooled reactor. 131 The energy deposition of I is approximately 0.42 W·cm⁻¹ -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; it cannot track the decay of irradiated isotopes. Irradiated isotopes may undergo α, β, and γ decays, as well as various combinations thereof, releasing heat; this heat can be calculated theoretically. The thermal neutron fluence rate and other relevant data of the target used in this calculation can be obtained through the MC program in step S102.

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

[0068] In one embodiment of this application, calculating the various decay heat release rates of irradiated isotopes includes the following steps:

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

[0070] Specifically, in this example, it is currently generally done by irradiating inside the reactor. 130 Te target for producing radioisotopes 131 I. 130 Te(n,γ) 131 I generated 131 I will continue to decay into beta and generate 131 Xe releases decay heat to determine the nuclide. 130 Te and 131 The equations for the change of the nucleon number of I over time are shown in the following formulas:

[0071]

[0072] Where N1 and N2 are at time t respectively 130 Te、 131 The atomic nucleus density of I (number of atomic nuclei per cubic centimeter); σ1 is 130 Te thermal neutron capture section (b); Thermal neutron fluence rate (n·cm) -2 ·s -1 ); λ2 is 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 isotopic target with respect to time, based on the corresponding equation for the change of the number of pronucleons over time.

[0074] In one embodiment of this 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 time, substituting the nuclear density of any isotope and isotope target at the initial time into the corresponding change equation, and solving for the nuclear density function of any isotope and isotope target.

[0075] Specifically, in this example, we determine that N1(0) = N 10 N2(0) = 0, N 10 yes 130 The initial number of atoms in Te can be determined through relevant detection methods. Furthermore, N1(0) = N 10 Substituting N2(0)=0 into the equation for the change of the number of pronucleons over time in the first step, we obtain 130 Te and 131 The nuclear density functions of I are shown in the following formulas:

[0076]

[0077]

[0078] The third step is to construct a nuclear density equilibrium equation based on the premise that the decay rate of any isotope is equal to its generation rate.

[0079] Specifically, in this example, when 131 The decay rate λ²N²(t) of I is equal to the generation rate. At that time, it can be considered 131 The density of I atom nuclei has reached equilibrium. 131 The β particles produced by I decay have weak penetrating power, and their β decay heat is entirely deposited in the target material. Therefore, the nuclear density equilibrium equation can be constructed as follows:

[0080] The fourth step involves combining the relevant calculation results from the Monte Carlo (MC) application, the nuclear density function, and the nuclear density equilibrium equation to calculate the decay heat release rate of any isotope.

[0081] In one embodiment of this application, calculating the decay heat release rate of any isotope includes: 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 when hour, 131 The equilibrium concentration of I is approximately 1.48 Ci / g. Substituting these two data points and the nuclear density function obtained in step two above into step three, we obtain the nuclear density equilibrium equation. The time value t that makes the nuclear density equilibrium equation hold can be calculated. Substituting this calculated time value t into the formulas for calculating nuclear density and decay rate in steps two and three above, the nuclear density and decay rate at that time value t can be obtained, and thus, the following can be calculated: 131 The β-heat exothermic result of I. For example, under the above-mentioned values ​​of thermal neutron fluence and corresponding equilibrium concentration, the calculated... 131 The β decay heat of I is approximately 1.01 × 10⁻⁶. -5 W·cm -3 .

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

[0084] Step S104, adding the plurality of energy deposition heat release rates and the plurality of decay heat release rates to obtain the isotopic 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 isotopic irradiation target calculated in step S103 is added to the isotopic decay heat release rate to obtain the total heat release rate of the pebble bed high temperature gas cooled reactor isotopic irradiation target.

[0086] Continuing to refer to the above example, 130 Production of radioactive isotopes by irradiating Te target in pebble bed high temperature gas cooled reactor 131 The total heat release rate of I is 0.42+1.01x10 -5 =0.4200101W·cm -3 .

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

[0088] In summary, the method for calculating the heat release rate of the pebble bed high temperature gas cooled reactor isotopic irradiation target of the present application takes into account the double non-uniformity and the continuous refueling characteristics of the pebble bed high temperature gas cooled reactor, first calculates the composition distribution of the reactor core fuel by using the special design software for the pebble bed high temperature gas cooled reactor, then calculates the various energy deposition heat release rates of the high temperature gas cooled reactor isotopic irradiation target by using the Monte Carlo model, then calculates the various isotopic decay heat release rates by using the calculation results of the Monte Carlo model, and finally calculates the total heat release rate of the isotopic irradiation target by comprehensively considering the two heat release rates. Therefore, the method accurately calculates various types of heat generation of the isotopic target during the irradiation process according to the characteristics of the pebble bed high temperature gas cooled reactor, significantly reduces the error in the calculation results. The method clearly defines the calculation process of the isotopic irradiation target heat release rate, and ensures the accuracy of the calculation results of the isotopic irradiation target heat release rate, providing a data basis for subsequent temperature analysis of the irradiation target. Therefore, the method is conducive to the irradiation production of isotopes in the pebble bed high temperature gas cooled reactor, and helps to improve the safety of the isotopic irradiation production process in the pebble bed high temperature gas cooled reactor.

[0089] In order to realize the above-mentioned embodiments, the present application further provides a system for calculating the heat release rate of the isotopic irradiation target of the pebble bed high temperature gas cooled reactor, Figure 10 A structural schematic diagram of a system for calculating the heat release rate of the isotopic irradiation target of the pebble bed high temperature gas cooled reactor according to the present application is shown in Figure 10 The system comprises a first construction module 100, a second construction module 200, a first calculation module 300 and a second calculation module 400.

[0090] The first construction module 100 is configured to construct a reactor model of the pebble bed type high temperature gas cooled reactor to be calculated by a pebble bed type high temperature gas cooled reactor special design application, and calculate the nuclear fuel composition distribution of the reactor core based on the reactor model.

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

[0092] The first calculation module 300 is configured to calculate a plurality of energy deposition heat release rates of the isotope irradiation target of the pebble bed type high temperature gas cooled reactor by the target Monte Carlo model, and calculate a plurality of decay heat release rates of the irradiation generated isotope by using the related calculation results of the Monte Carlo (MC) application program.

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

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

[0095] Optionally, in an embodiment of the present application, the second construction module 200 is specifically configured 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 by a script program.

[0096] Optionally, in an embodiment of the present application, the second construction module 200 is further configured to sample the geometric coordinates of the coated fuel particles in a single spherical fuel element in the reactor core by the Monte Carlo (MC) application program, establish a fuel element model conforming to the probability distribution of the coated fuel particles, and arrange the pebble bed in the reactor core at a preset filling rate, sample the geometric coordinates of the spherical fuel elements in the pebble bed by the Monte Carlo (MC) application program, and establish the core MC model containing the isotope target.

[0097] Optionally, in an embodiment of the present application, the first calculation module 300 is specifically configured to: determine a change equation of the number of nuclei of the isotope target for producing any isotope and the isotope over time respectively; determine a nuclear density function of the isotope and the isotope target with respect to time according to the corresponding change equation of the number of nuclei over time; construct a nuclear density balance equation based on the decay rate of the isotope being equal to the generation rate; and calculate the decay heat release rate of the isotope by combining the relevant calculation results of the Monte Carlo (MC) application program, the nuclear density function and the nuclear density balance equation.

[0098] Optionally, in an embodiment of the present application, the first calculation module 300 is specifically configured to: substitute the thermal neutron flux, the equilibrium concentration and the nuclear density function into the nuclear density balance equation to calculate a time value at which the nuclear density balance is reached; calculate the nuclear density and the decay rate of the isotope at the time value, and calculate the decay heat release rate of the isotope based on the calculated nuclear density and the decay rate of the isotope at the time value.

[0099] It should be noted that the above description of the embodiment of the method for calculating the heat release rate of the isotope irradiation target of the pebble bed type high temperature gas cooled reactor is also applicable to the system of the embodiment, which will not be described here.

[0100] In summary, the system for calculating the heat release rate of the isotope irradiation target of the pebble bed type high temperature gas cooled reactor according to the embodiments of the present application comprehensively considers the double non-uniformity and the non-stop refueling characteristics of the pebble bed type high temperature gas cooled reactor, accurately calculates various types of heat generated by the isotope target during irradiation in view of the characteristics of the pebble bed type high temperature gas cooled reactor, and significantly reduces the error in the calculation results. The system clearly defines 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, thereby providing a data basis for subsequent temperature analysis of the irradiation target.

[0101] In order to implement the above-mentioned embodiments, the present application further provides a non-transitory computer-readable storage medium having a computer program stored thereon, wherein the computer program is executed by a processor to implement the method for calculating the heat release rate of the isotope irradiation target of the pebble bed type high temperature gas cooled reactor according to any one of the above-mentioned embodiments of the first aspect.

[0102] In the description of the application, reference to "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" means that a particular feature, structure, material, or characteristic being described is included in at least one embodiment or example of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment or example. Furthermore, the described specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples. Moreover, the usage of the terms "first", "second" or "third" does not limit the quantity or order of the specific features, structures, materials or characteristics, but rather the term "first", "second" or "third" can be used to distinguish different features, structures, materials or characteristics, which can be combined in any suitable manner. Furthermore, the singular forms "a", "an" and "the" include plural references unless the context clearly dictates otherwise.

[0103] Furthermore, the terms "first", "second", or the like, merely denote different instances of a similar feature, structure, material or characteristic, without necessarily implying any relative importance or any particular order. Thus, a feature defined with "first" or "second" can implicitly or explicitly include at least one of the features. The meaning of "a", "an" and "the" includes plural references unless the context clearly dictates otherwise.

[0104] Any process or method descriptions or blocks in flow charts or otherwise described herein represent embodiments which can be managed as one or more modules, segments, or portions of code which include one or more steps for implementing specific logic functions or steps, and the terms in the description are used for causing or carrying out or upgrading of an action between other hardware under their control. The description of processes and methods of operations should be considered as merely illustrative of the principles of the application.

[0105] The logic and / or steps represented in the flowcharts and / or described herein, for example, can be considered as a sequence of executable instructions stored in a computer readable medium, which can be executed by an instruction execution system, apparatus or device, such as a computer-based system, a processor-based system, or other system that can fetch the instructions from the instruction execution system, apparatus or device and execute the instructions, or a combination thereof. For the purposes of this specification, a "computer readable medium" can be any apparatus that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus or device. The computer readable medium can specifically be, but is not limited to, the following: an electronic connection (electronic apparatus) having one or more wires, a portable computer diskette (magnetic apparatus), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, and a portable compact disk read-only memory (CDROM). In addition, the computer readable medium can even be paper or other suitable medium upon which the program can be printed, because the program can be electronically obtained, for example, by optically scanning the paper or other medium, then

[0106] It should be understood that portions of the application can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. As such, if implemented in hardware, and in another embodiment, any of the following technologies, known in the art, or a combination thereof, can be used: discrete logic circuitry having logic gates for implementing logic functions on data signals, application specific integrated circuits having appropriate combinational logic gates, programmable gate arrays (PGA), field programmable gate arrays (FPGA), and the like.

[0107] Those of ordinary skill in the art can understand that all or part of the steps carried out by the above-mentioned embodiment methods can be completed by programs instructing relevant hardware, and the programs can be stored in a computer readable storage medium. When the programs are executed, they include one of the steps of the method embodiments or a combination thereof.

[0108] In addition, each of the functional units in the various embodiments of the present application can be integrated in one processing module, or each of the units can be physically present separately, or two or more units can be integrated in one module. The integrated module can be implemented in the form of hardware or in the form of a software functional module. When the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer readable storage medium.

[0109] The storage medium mentioned above can 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 should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A method for calculating the heat release rate of an isotope irradiation target in a pebble bed high temperature gas cooled reactor, characterized in that, The method comprises the following steps: constructing a reactor model of the pebble bed type high temperature gas cooled reactor to be calculated through a pebble bed type high temperature gas cooled reactor special design application, and calculating a nuclear fuel composition distribution of a core based on the reactor model; performing twice non-uniform arrangement on a fuel distribution of the core of the pebble bed type high temperature gas cooled reactor through a Monte Carlo (MC) application program, constructing a core MC model, and transferring the nuclear fuel composition distribution of the core into the core MC model to obtain a target Monte Carlo model for isotope irradiation production; calculating a plurality of energy deposition heat release rates of isotope irradiation targets of the pebble bed type high temperature gas cooled reactor through the target Monte Carlo model, and calculating a plurality of decay heat release rates of irradiation generated isotopes by using relevant calculation results of the Monte Carlo MC application program; adding the plurality of energy deposition heat release rates and the plurality of decay heat release rates to obtain a heat release rate of the isotope irradiation targets of the pebble bed type high temperature gas cooled reactor.

2. The method of claim 1, wherein, The reactor model comprises a VSOP calculation model, and the calculation of the nuclear fuel composition distribution of the core based on the reactor model comprises: dividing the core of the pebble bed type high temperature gas cooled reactor into a plurality of units based on the VSOP calculation model, wherein the plurality of units comprise different reflector layers and channels of the core; inputting material composition information of each unit into the VSOP calculation model, and calculating the nuclear fuel composition distribution of the core through an operation program of the VSOP calculation model.

3. The method of claim 2, wherein, The fuel composition distribution of the core comprises nuclear fuel composition information of each batch in different regions, and the transferring of the nuclear fuel composition distribution of the core into the core MC model comprises: matching coordinates of the core MC model and the VSOP calculation model to correspond to fuel element model architectures of different regions; mapping, through a script program, the nuclear fuel composition information of each batch in each region calculated by the VSOP calculation model into the core MC model.

4. The method of claim 1, wherein, The twice non-uniform arrangement on the fuel distribution of the core of the pebble bed type high temperature gas cooled reactor comprises: sampling, through the Monte Carlo MC application program, geometric coordinates of coated fuel particles in a single spherical fuel element in the core to establish a fuel element model conforming to a probability distribution of the coated fuel particles; arranging a pebble bed in the core at a preset filling rate, sampling, through the Monte Carlo MC application program, geometric coordinates of spherical fuel elements in the pebble bed to establish the core MC model containing isotope targets.

5. The method of claim 1, wherein, The calculation of the plurality of decay heat release rates of irradiation generated isotopes comprises: respectively determining a change equation of a number of original nuclei of any isotope and an isotope target producing the any isotope over time; determining a nuclear density function of the any isotope and the isotope target with respect to time according to the corresponding change equation of the number of original nuclei over time; constructing a nuclear density balance equation based on the fact that a decay rate of the any isotope is equal to a generation rate; and In combination with the relevant calculation results of the Monte Carlo (MC) application program, the nuclear density function and the nuclear density balance equation, the decay heat release rate of any isotope is calculated.

6. The method of claim 5, wherein, The determination of the nuclear density function of the any isotope and the isotope target with respect to time comprises: The nuclear density of the any isotope and the isotope target at an initial time is determined, and the nuclear density of the any isotope and the isotope target at the initial time is substituted into the corresponding change equation respectively to solve the nuclear density function of the any isotope and the isotope target.

7. The method of claim 5, wherein, The relevant calculation results of the Monte Carlo (MC) application program comprise a thermal neutron flux and a balance concentration corresponding to the thermal neutron flux, and the calculation of the decay heat release rate of the any isotope comprises: The thermal neutron flux, the balance concentration and the nuclear density function are substituted into the nuclear density balance equation to calculate a time value at which the nuclear density reaches a balance; The nuclear density and the decay rate of the any isotope at the time value are calculated, and the decay heat release rate of the any isotope is calculated based on the calculated nuclear density and the decay rate at the time value.

8. A system for calculating the heat release rate of an isotope irradiation target in a pebble bed high temperature gas cooled reactor, characterized in that, The method comprises the following modules: A first construction module is configured to construct a reactor model of a high-temperature gas-cooled reactor (HTGR) to be calculated by using a special design application of the HTGR, and calculate a nuclear fuel composition distribution of a core of the HTGR based on the reactor model; A second construction module is configured to perform two times of non-uniform arrangement on a fuel distribution of the core of the HTGR by using a Monte Carlo (MC) application program, to construct a core MC model, and transfer the nuclear fuel composition distribution of the core into the core MC model to obtain a target MC model for isotope irradiation production; A first calculation module is configured to calculate a plurality of energy deposition heat release rates of an isotope irradiation target of the HTGR by using the target MC model, and calculate a plurality of decay heat release rates of the irradiation generated isotope by using relevant calculation results of the MC application program; A second calculation module is configured to add the plurality of energy deposition heat release rates and the plurality of decay heat release rates to obtain an isotope irradiation target heat release rate of the HTGR.

9. The system of claim 8, wherein, The reactor model comprises a VSOP calculation model, and the first construction module is specifically configured to: divide the core of the HTGR into a plurality of units based on the VSOP calculation model, wherein the plurality of units comprise different reflector layers and channels of the core; input material composition information of each unit into the VSOP calculation model, and calculate the nuclear fuel composition distribution of the core by using an operation program of the VSOP calculation model.

10. A non-transitory computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by a processor to implement the method for calculating the isotope irradiation target heat release rate of the HTGR according to any one of claims 1-7.

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