A multi-layer source grid based complex radiation field inversion system and method

Abstract

The present application relates to the technical field of complex radiation field inversion, and particularly relates to a complex radiation field inversion system and method based on a multi-layer source grid, wherein a multi-layer source grid division subsystem is used to perform multi-layer discrete approximation on a complex source term with a known position and shape to be inverted, a detector partition arrangement subsystem is used to set detectors for a radioactive source, all coarse grid volume sources and all fine grid volume sources respectively in different manners for detection, a source term inversion subsystem is used to perform inversion on source intensity distribution of the complex source term according to the radioactive source, all coarse grid volume sources, all fine grid volume sources and first, second and third measurement values, and a radiation field calculation subsystem is used to calculate the radiation field distribution of the inverted complex source term. The technical problem that the complex source cannot be inverted in the traditional inversion is overcome, and the radiation field under the complex source distribution can be quickly and accurately inverted.

Description

Technical Field

[0001] This invention relates to the field of complex radiation field inversion technology, and in particular to a complex radiation field inversion system and method based on a multi-layer source grid. Background Technology

[0002] In the shielding design of nuclear power plants, there are numerous and complex pieces of equipment, and the dose field distribution within the plant is equally complex and variable. To conduct precise, comprehensive, and accurate radiation protection design for nuclear power plants, detailed calculations of the dose field distribution within the plant are necessary.

[0003] During the maintenance and decommissioning of nuclear facilities, dose assessment of work plans is a crucial means of achieving on-site dose reduction. Establishing the radiation field of the work area can be achieved in advance through software simulations of the work process, providing dose information and optimizing the work plan to further effectively reduce the radiation dose to workers. Therefore, conducting research on rapid radiation field calculations can provide advanced and more operational technical support for optimizing radiation protection, significantly improving the safety level of on-site radiation protection at nuclear facilities. Inversion methods are an important means of rapid radiation field calculation.

[0004] The inversion method retrieves the true source term distribution within the reactor by analyzing readings from external detectors. It then calculates the contribution function of the source terms to the spatial dose value of the radiation field through transport calculations. Multiplying the source term distribution by the contribution function yields the radiation field distribution. Source term information is the input and a prerequisite for the calculation. Traditional inversion methods treat in-reactor radioactive sources as uniformly distributed volume or point sources. However, in reality, the reactor's internal components are complex, resulting in a complex and non-uniform distribution of radioactive sources. The source terms are activated using the reactor core coolant. 16 Taking N as an example, the coolant flow rate in a pressurized water reactor is relatively fast. 16 The nitrogen source term is relatively uniformly distributed in the main coolant system, while the design flow rate is lower in high-temperature reactors. 16 The distribution of nitrogen (N) in different regions of the main coolant system exhibits significant non-uniformity, with activity differences reaching up to two orders of magnitude. In this situation, current source term inversion methods, which treat the source term as a uniform distribution before inversion, introduce substantial errors, failing to provide accurate and reliable radiation field distribution data. This is particularly true at locations close to the source term, where the deviation from the true value is significant and cannot be ignored.

[0005] Therefore, it is necessary to develop a radiation field inversion method that can obtain a true negative non-uniformly distributed radiation source and construct a reliable radiation field distribution. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a complex radiation field inversion system and method based on a multi-layer source grid.

[0007] The technical solution of the complex radiation field inversion system based on multi-layer source grid of the present invention is as follows:

[0008] The multi-layer source grid partitioning subsystem is used to: perform multi-layer discrete approximation on the complex source terms with known positions and shapes to be inverted, to obtain a radioactive source, and multiple coarse grid volume sources obtained by partitioning the radioactive source, and multiple fine grid volume sources obtained by partitioning each coarse grid volume source, wherein the source intensity is uniformly distributed in the radioactive source, each coarse grid volume source and each fine grid volume source.

[0009] The detector partitioning subsystem is used to: set detectors for the radiation source, all coarse-grid sources and all fine-grid sources in different ways, so as to detect and obtain the first measurement value corresponding to the radiation source, the second measurement value corresponding to all coarse-grid sources and the third measurement value corresponding to all fine-grid sources.

[0010] The source term inversion subsystem is used to: invert the source intensity distribution of the complex source term based on the radioactive source, all coarse-grid volume sources, all fine-grid volume sources, and the first measurement value, the second measurement value, and the third measurement value;

[0011] The radiation field calculation subsystem is used to calculate the radiation field distribution of the inverted complex source terms.

[0012] The beneficial effects of the complex radiation field inversion system based on a multi-layer source grid of the present invention are as follows:

[0013] It overcomes the technical challenge of traditional inversion methods that cannot invert complex sources, and can quickly and accurately invert radiation fields under complex source distributions, which has important scientific research and engineering application value.

[0014] The technical solution of the complex radiation field inversion method based on multi-layer source grid of the present invention is as follows:

[0015] Multi-level discrete approximation is performed on the complex source term with known location and shape to be inverted to obtain a radioactive source, multiple coarse grid volume sources obtained by dividing the radioactive source, and multiple fine grid volume sources obtained by dividing each coarse grid volume source, wherein the source intensity is uniformly distributed in the radioactive source, each coarse grid source and each fine grid volume source.

[0016] Detectors are set up for the radioactive source, all coarse-grid sources, and all fine-grid sources in different ways to detect and obtain the first measurement value corresponding to the radioactive source, the second measurement value corresponding to all coarse-grid sources, and the third measurement value corresponding to all fine-grid sources.

[0017] Based on the radioactive source, all coarse-grid sources, all fine-grid sources, and the first, second, and third measurements, the source intensity distribution of the complex source term is inverted;

[0018] Calculate the radiation field distribution of the complex source term after inversion.

[0019] The beneficial effects of the complex radiation field inversion method based on multi-layer source grids of the present invention are as follows:

[0020] It overcomes the technical challenge of traditional inversion methods that cannot invert complex sources, and can quickly and accurately invert radiation fields under complex source distributions, which has important scientific research and engineering application value. Attached Figure Description

[0021] Figure 1 This is one of the flowcharts of a complex radiation field inversion system based on a multi-layer source grid according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of a complex radiation field inversion method based on a multi-layer source grid according to an embodiment of the present invention. Detailed Implementation

[0023] like Figure 1 As shown, an embodiment of the present invention provides a complex radiation field inversion system 200 based on a multi-layer source grid, which includes a multi-layer source grid partitioning subsystem 210, a detector partitioning subsystem 220, a source term inversion subsystem 230, and a radiation field calculation subsystem 240.

[0024] The multi-layer source grid partitioning subsystem 210 is used to: perform multi-layer discrete approximation on a complex source term with known location and shape to be inverted, to obtain a radioactive source, and multiple coarse grid volume sources obtained by partitioning the radioactive source, and multiple fine grid volume sources obtained by partitioning each coarse grid volume source, wherein the source intensity is uniformly distributed in each coarse grid volume source and each fine grid volume source.

[0025] The multi-layer source mesh generation subsystem 210 is specifically used for:

[0026] Define a radioactive source with the same shape and uniform source intensity at the location of the complex source term, and ensure that the total source intensity of the radioactive source is equal to the total source intensity of the complex source term. Specifically:

[0027] For the complex source term S with known location and shape to be inverted in In complex source item S in Location definition and complex source term S in Radioactive sources with the same shape and uniform intensity distribution Furthermore, radioactive sources Total source strength With the complex source term S to be inverted in The total source strength is equal;

[0028] The radioactive source is divided into multiple coarse-grid volume sources, with the source intensity uniformly distributed within each coarse-grid volume source. The sum of the source intensities of all coarse-grid volume sources is equal to the total source intensity of the complex source term. Specifically:

[0029] radioactive source Divide into N coarse-grid volume sources, based on the complex source term S in The complexity is such that N ranges from 2 to 10, and the source strength within each coarse grid source is uniformly distributed. The nth coarse grid source... The source strength is Furthermore, the sum of the source strengths of all coarse-grid volume sources and the complex source term S in The total source intensity is equal because the radioactive source Total source strength With the complex source term S to be inverted in If the total source strengths are equal, then it can be expressed as:

[0030] Each coarse-grid source is divided into multiple fine-grid sources. The source intensity within each fine-grid source is uniformly distributed. The sum of the source intensities of all fine-grid sources is equal to the total source intensity of the complex source term. Furthermore, the total source intensity of any coarse-grid source is equal to the total source intensity of all fine-grid sources derived from that coarse-grid source. Specifically:

[0031] radioactive source Divide into M fine-mesh volume sources. Specifically, each coarse-mesh volume source is further divided into M fine-mesh volume sources, based on the complex source term S. in The complexity is determined by the value of M, which ranges from 4 to 50. The source intensity within each fine-mesh volume source is uniformly distributed, and the distribution of all fine-mesh volume sources can characterize the complex source term S. in Non-uniform distribution of source strength within the m-th fine mesh volume source The source strength is m = 1, 2, ..., M, the sum of the source strengths of all fine mesh volumes and the complex source term S in The total source strength is equal, and the sum of the source strengths of fine mesh sources belonging to the same coarse mesh source is equal to the source strength of that coarse mesh.

[0032] The detector partitioning subsystem 220 is used to: set up detectors for the radiation source, all coarse grid sources and all fine grid sources in different ways, so as to detect and obtain the first measurement value corresponding to the radiation source, the second measurement value corresponding to all coarse grid sources and the third measurement value corresponding to all fine grid sources;

[0033] The detector zoning subsystem 220 is used for:

[0034] A first detector is deployed at a location within a first preset distance from the radiation source to obtain a first measurement value corresponding to the radiation source. In other words, the first detector is deployed at any location greater than the first preset distance from the radiation source, designated as a first preset distance. Specifically:

[0035] For radioactive sources A detector is deployed at a location relatively far from the source, with a preset distance >1m. This location is within a certain distance of the radiation source. Relatively distant, complex source term S in The non-uniform distribution has little impact on the detector, i.e., the first detector, which is sensitive to complex source terms S. in The response can be equivalent to the detector, i.e., the first detector, responding to the radioactive source. The response.

[0036] Multiple second detectors are deployed at a second preset distance from all coarse-grid volume sources in Zone 2, so that the second measurement values ​​corresponding to all coarse-grid volume sources can be obtained through detection by all second detectors. Specifically:

[0037] For a coarse-grid source, N2 detectors are deployed, i.e., the second detector is located in the second zone, which is far away from the coarse-grid source. The second preset distance is >0.5m. In other words, the distance between each coarse-grid source and the second zone location must be greater than 0.5m.

[0038] According to the complex source term S in The complexity of the distribution, N2, ranges from N / 4 to N / 2. The arrangement of the detectors, i.e., the second detector, satisfies the following conditions:

[0039] 1) The detectors in the second zone are sensitive to different coarse-grid volume sources;

[0040] 2) Compared to Zone 1, Zone 2 is closer to the radiation source. Relatively close;

[0041] 3) The location of the second detector in the second region is relatively far from the coarse-grid volume source. The second detector detects the complex source term S. in The response can be equivalent to the response of the second detector to the coarse-grid source;

[0042] The arrangement of the second detectors will be explained using an example of four second detectors:

[0043] Using the centroid of the set of all coarse mesh sources as the center, and the plane perpendicular to the normal direction of the set of all coarse mesh sources as the reference plane, and with the second preset distance as the radius, a circle is established. A second detector is arranged every 360° / 4 on the circle, that is, a second detector is arranged every 90° on the circle.

[0044] It should be noted that the second detector is distributed around the set of all coarse-grid volume sources in a dispersed manner as much as possible, and this can be adjusted according to the actual situation.

[0045] Multiple third detectors are deployed at three locations within a third preset distance from all fine-grid volume sources. The third detectors are used to obtain the third measurement values ​​corresponding to all fine-grid volume sources. Specifically:

[0046] For a fine-grid volume source, N3 detectors are deployed, with the third detector located in the third region, which is relatively far from the fine-grid volume source. The third preset distance is <0.5m. In other words, the distance between each coarse-grid volume source and the third region location must be less than 0.5m. According to the complex source term S... in The complexity of the distribution, N3, ranges from M / 4 to M / 2. The detector, i.e., the third detector, is arranged to satisfy the following conditions:

[0047] 1) The detectors in the three regions, namely the third detectors in the three regions, are sensitive to different fine-mesh volume sources;

[0048] 2) Compared to the locations in Zones 1 and 2, the location in Zone 3 is closer to the radiation source. More recently, the third detector studied the complex source term S. in The response can be equivalent to the response of the third detector to the fine mesh source.

[0049] The arrangement of the third detectors will be explained using an example of eight third detectors:

[0050] Using the centroid of the set of all fine mesh sources as the center, and the plane perpendicular to the normal direction of the set of all fine mesh sources as the reference plane, and with a third preset distance as the radius, a circle is established. A second detector is arranged every 360° / 8 on the circle, that is, a third detector is arranged every 45° on the circle.

[0051] It should be noted that the distribution of the third detector around the set of all fine-grid volume sources in a dispersed manner can be adjusted according to the actual situation.

[0052] Measurements were performed using the first detector in zone one, the second detector in zone two, and the third detector in zone three, respectively, to obtain the radioactive source. The corresponding first measurement value The second measurement value corresponding to all coarse mesh volume sources And the third measurement value corresponding to all fine mesh volume sources. in, This represents the measurement values ​​from the first and second detectors. This represents the measurement value of the second detector, ... This represents the measurement value of the N2nd second detector; This represents the measurement value of the first third detector. This represents the measurement values ​​from the second and third detectors, ... This represents the measurement value of the N3rd third detector;

[0053] The source term inversion subsystem 230 is used to invert the source intensity distribution of complex source terms based on the radioactive source, all coarse grid volume sources, all fine grid volume sources, and the first, second, and third measurements.

[0054] The complex source term inversion subsystem 230 is specifically used for:

[0055] Establish a full-space particle transport model;

[0056] Based on the full-space particle transport model, a radioactive source with unit source intensity is set at the radioactive source, and a detector reaction rate count is set at the first detector. The reaction rate at the first detector is obtained through transport calculations, and the reaction rate is determined as the first response function. Specifically:

[0057] Based on the full-space particle transport model, in the radioactive source A radioactive source of unit source strength is set up at the location, and a detector reactivity count is set up at the first detector. The reactivity at the first detector is obtained through transport calculation. That is, the first detector in Zone 1 is used to detect the radioactive source. response function That is, the first response function is

[0058] Based on the full-space particle transport model, a radioactive source with unit source intensity is set at each coarse-grid volume source, and a detector reactivity count is set at each second detector. The reactivity at each second detector is obtained through transport calculations, and a second response function is obtained based on the reactivity at each second detector. Specifically:

[0059] Based on the full-space particle transport model, N independent transport calculations were performed. Unit-intensity radioactive sources were set at N coarse-grid volume sources, and detector reactivity counts were set at N² second detector locations. The reactivity at each second detector under the influence of the N coarse-grid volume sources was obtained through transport calculations.

[0060] The reaction rate at the first and second detectors The reaction rate at the second detector is ...the reaction rate at the N2nd second detector is Will The response function at the first and second detectors Will The response function at the second detector Will The response function at the N2nd second detector The second response function is obtained as follows: Based on the full-space particle transport model, a radioactive source with unit source intensity is set at each fine-grid volume source, and a detector reactivity count is set at each third detector. The reactivity at each third detector is obtained through transport calculations, and the third response function is obtained based on the reactivity at each third detector. Specifically:

[0061] Based on the full-space particle transport model, M independent transport calculations were performed. Unit-intensity radioactive sources were set up at M fine-grid sources, and detector reactivity counts were set up at N3 third detector locations. The reactivity at each second detector under the influence of M coarse-grid sources was obtained through transport calculations. The reactivity at the first third detector was... The reaction rate at the second and third detectors ...the reaction rate at the N3rd third detector is Will The response function at the first third detector Will The response function at the second and third detectors ……,Will The response function at the N3rd third detector The third response function is obtained as follows:

[0062] Based on the first measurement value and the first response function, the total source intensity of the radioactive source is calculated. Based on the second measurement value and the second response function, the source intensity of each coarse-grid volume source is calculated. Based on the third measurement value and the third response function, the source intensity of each fine-grid volume source is calculated, thereby achieving the inversion of the source intensity distribution of complex source terms. Specifically:

[0063] 1) Inversion of radioactive sources Total source strength:

[0064] Based on the first measurement value of Zone 1 First response function of zone 1 With Zong Yuanqiang Relationship equations: based on Solving this equation yields the radioactive source. Total source strength The specific value;

[0065] 2) Coarse-grid volume source inversion:

[0066] According to the second measurement value in Zone 2 The second response function of zone two The equation relating the source strength to the coarse mesh volume is as follows:

[0067]

[0068] The source strength of the nth coarse mesh volume source is obtained by solving the problem. The specific value is obtained, and thus the specific value of the source strength of each coarse grid source is obtained.

[0069] 3) Fine-mesh volume source inversion:

[0070] Based on the third measurement value of the three zones The third response function of the three zones The equation relating the source strength to the fine mesh volume is as follows:

[0071]

[0072] The source strength of the m-th fine-mesh volume source is obtained by solving the problem. The specific value is obtained, and thus the specific value of the source strength of each fine mesh volume source is obtained;

[0073] The radiation field calculation subsystem 240 is used to calculate the radiation field distribution of the inverted complex source term. Specifically:

[0074] Based on the full-space particle transport model, M independent transport calculations were performed. Unit-intensity radioactive sources were set up at M fine-grid sources, and the dose rate across the entire radiation field was counted. The dose rate at the m-th fine-grid source was calculated, and this dose rate represents the response function f of the full-space dose rate to the fine-grid source. m (r);

[0075] In actual radiation field monitoring, the dose rate X(r) of the entire space is related to the radiation source. f m The relationship between (r) is as follows: f1(r) represents the dose rate under the first fine-grid volume source, which is the response function of the total dose rate of the radiation field to the fine-grid volume source. This is based on the specific source strength of each fine-grid volume source and the partially solved response function f1(r)...f m (r), construct the equation above, which is... Solving the equation yields the specific value of the dose rate X(r) across the entire radiation field, which is the radiation field distribution of the complex source term after inversion.

[0076] This invention addresses the problem of pre-existing radiation field inversion methods that assume a uniform distribution of radioactive sources, making it impossible to invert complex, non-uniformly distributed radioactive sources and obtain the true radiation field distribution. This invention proposes a radiation field inversion method based on a partitioned detector layout and a multi-layered source grid, enabling rapid and accurate inversion of radiation fields with complex source distributions. This overcomes the technical challenge of traditional inversion methods being unable to invert complex sources, and thus possesses significant scientific research and engineering application value. It belongs to the field of radiation detection technology.

[0077] like Figure 2 As shown in the figure, an embodiment of the present invention provides a method for inverting complex radiation fields based on multi-layer source grids, comprising the following steps:

[0078] S1. Perform multi-level discrete approximation on the complex source term with known location and shape to be inverted to obtain the radioactive source, and multiple coarse grid sources obtained by dividing the radioactive source, and multiple fine grid sources obtained by dividing each coarse grid source, wherein the source intensity is uniformly distributed in the radioactive source, each coarse grid source and each fine grid source.

[0079] S2. Detectors are set up for the radioactive source, all coarse grid sources and all fine grid sources in different ways to detect the first measurement value corresponding to the radioactive source, the second measurement value corresponding to all coarse grid sources and the third measurement value corresponding to all fine grid sources.

[0080] S3. Based on the radioactive source, all coarse-grid volume sources, all fine-grid volume sources, and the first, second, and third measurements, the source intensity distribution of the complex source term is inverted;

[0081] S4. Calculate the radiation field distribution of the complex source terms after inversion.

[0082] Optionally, in the above technical solution, S1, the process of performing multi-level discrete approximation on the complex source term with known location and shape to be inverted includes:

[0083] S10. Define a uniformly distributed radioactive source with the same shape as the complex source term at the location of the complex source term, and the total source intensity of the radioactive source is equal to the total source intensity of the complex source term.

[0084] S11. Divide the radioactive source into multiple coarse grid sources. The source intensity in each coarse grid source is uniformly distributed. The sum of the source intensities of all coarse grid sources is equal to the total source intensity of the complex source term.

[0085] S12. Divide each coarse grid source into multiple fine grid sources. The source intensity in each fine grid source is uniformly distributed. The sum of the source intensities of all fine grid sources is equal to the total source intensity of the complex source term. Furthermore, the total source intensity of any coarse grid source is equal to the total source intensity of all fine grid sources divided from that coarse grid source.

[0086] Optionally, in the above technical solution, the process of setting the detector in S2 includes:

[0087] S20. At a location in Zone 1, at a first preset distance from the radiation source, a first detector is set up to detect and obtain the first measurement value corresponding to the radiation source.

[0088] S21. At the second zone position, which is a second preset distance from all coarse grid volume sources, multiple second detectors are arranged so that the second measurement values ​​corresponding to all coarse grid volume sources can be obtained by detecting all the second detectors.

[0089] S22. At the three-zone location at a third preset distance from all fine-grid volume sources, multiple third detectors are arranged to obtain the third measurement value corresponding to all fine-grid volume sources through all third detectors.

[0090] Optionally, in the above technical solution, the process of inverting the source strength distribution of complex source terms in S3 includes:

[0091] S30. Establish a full-space particle transport model;

[0092] S31. Based on the full-space particle transport model, a radioactive source with a unit source strength is set at the radioactive source, and a detector reaction rate count is set at the first detector. The reaction rate at the first detector is obtained through transport calculation, and the reaction rate is determined as the first response function.

[0093] S32. Based on the full-space particle transport model, a radioactive source with a unit source intensity is set at each coarse grid volume source, and a detector reaction rate count is set at each second detector. The reaction rate at each second detector is obtained through transport calculation, and the second response function is obtained based on the reaction rate at each second detector.

[0094] S33. Based on the full-space particle transport model, a radioactive source with a unit source intensity is set at each fine grid volume source, and a detector reaction rate count is set at each third detector. The reaction rate at each third detector is obtained through transport calculation, and the third response function is obtained based on the reaction rate at each third detector.

[0095] S34. Based on the first measurement value and the first response function, the total source intensity of the radioactive source is calculated. Based on the second measurement value and the second response function, the source intensity of each coarse grid volume source is calculated. Based on the third measurement value and the third response function, the source intensity of each fine grid volume source is calculated, so as to realize the inversion of the source intensity distribution of complex source terms.

[0096] In the above embodiments, although the steps are numbered S1, S2, etc., they are only specific embodiments given in this application. Those skilled in the art can adjust the execution order of S1, S2, etc. according to the actual situation, which is also within the protection scope of this invention. It can be understood that in some embodiments, some or all of the above embodiments may be included.

[0097] The implementation of each step in the above-described method for inverting complex radiation fields based on multi-layer source grids of the present invention can be referred to the embodiments of the complex radiation field inversion system 200 based on multi-layer source grids described above, and will not be repeated here.

[0098] An electronic device according to an embodiment of the present invention includes a memory, a processor, and a program stored in the memory and running on the processor. When the processor executes the program, it implements the steps of a complex radiation field inversion method based on a multi-layer source grid according to any of the above embodiments.

[0099] The electronic device can be a computer, mobile phone, etc., and the corresponding program is computer software or mobile APP, etc. The parameters and steps of the above-mentioned electronic device of the present invention can be referred to the parameters and steps in the embodiment of the steps of the complex radiation field inversion method based on multi-layer source grid in the above text, and will not be repeated here.

[0100] Those skilled in the art will know that this invention can be implemented as a system, method, or computer program product.

[0101] Therefore, this disclosure can be implemented in the following forms: it can be entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software, generally referred to herein as a "circuit," "module," or "system." Furthermore, in some embodiments, the invention can also be implemented as a computer program product in one or more computer-readable media, the computer-readable medium containing computer-readable program code.

[0102] Any combination of one or more computer-readable media may be used. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in connection with an instruction execution system, apparatus, or device.

[0103] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A complex radiation field inversion system based on a multi-layer source grid, characterized in that, It includes a multi-layer source grid partitioning subsystem, a detector partitioning subsystem, a source term inversion subsystem, and a radiation field calculation subsystem; The multi-layer source grid partitioning subsystem is used to: perform multi-layer discrete approximation on the complex source terms with known positions and shapes to be inverted, to obtain a radioactive source, and multiple coarse grid volume sources obtained by partitioning the radioactive source, and multiple fine grid volume sources obtained by partitioning each coarse grid volume source, wherein the source intensity is uniformly distributed in the radioactive source, each coarse grid volume source and each fine grid volume source. The detector partitioning subsystem is used to: set detectors for the radiation source, all coarse-grid sources and all fine-grid sources in different ways, so as to detect and obtain the first measurement value corresponding to the radiation source, the second measurement value corresponding to all coarse-grid sources and the third measurement value corresponding to all fine-grid sources. The source term inversion subsystem is used to: invert the source intensity distribution of the complex source term based on the radioactive source, all coarse-grid volume sources, all fine-grid volume sources, and the first measurement value, the second measurement value, and the third measurement value; The radiation field calculation subsystem is used to: calculate the radiation field distribution of the inverted complex source terms; The multi-layer source mesh partitioning subsystem is specifically used for: At the location of the complex source term, a uniformly distributed radioactive source with the same shape as the complex source term is defined, and the total source intensity of the radioactive source is equal to the total source intensity of the complex source term; The radioactive source is divided into multiple coarse grid sources, and the source intensity within each coarse grid source is uniformly distributed. The sum of the source intensities of all coarse grid sources is equal to the total source intensity of the complex source term. Each coarse grid source is divided into multiple fine grid sources. The source intensity within each fine grid source is uniformly distributed. The sum of the source intensities of all fine grid sources is equal to the total source intensity of the complex source term. Furthermore, the total source intensity of any coarse grid source is equal to the total source intensity of all fine grid sources divided from that coarse grid source. The detector partitioning subsystem is used for: A first detector is deployed at a location in a zone at a first preset distance from the radiation source, so as to obtain a first measurement value corresponding to the radiation source by detecting the first detector; In the second zone, at a second preset distance from all coarse grid volume sources, multiple second detectors are arranged to obtain the second measurement values ​​corresponding to all coarse grid volume sources through all second detectors. Multiple third detectors are deployed at three locations at a third preset distance from all fine-grid volume sources, so that the third measurement value corresponding to all fine-grid volume sources can be obtained by detecting all the third detectors.

2. The complex radiation field inversion system based on a multi-layer source grid according to claim 1, characterized in that, The complex source term inversion subsystem is specifically used for: Establish a full-space particle transport model; Based on the full-space particle transport model, a radioactive source with a unit source strength is set at the radioactive source, and a detector reaction rate count is set at the first detector. The reaction rate at the first detector is obtained through transport calculation, and the reaction rate is determined as the first response function. Based on the full-space particle transport model, a radioactive source with a unit source intensity is set at each coarse grid source, and a detector reaction rate count is set at each second detector. The reaction rate at each second detector is obtained through transport calculation, and the second response function is obtained based on the reaction rate at each second detector. Based on the full-space particle transport model, a radioactive source with a unit source intensity is set at each fine grid volume source, and a detector reaction rate count is set at each third detector. The reaction rate at each third detector is obtained through transport calculation, and the third response function is obtained based on the reaction rate at each third detector. The total source intensity of the radioactive source is calculated based on the first measured value and the first response function. The source intensity of each coarse-grid volume source is calculated based on the second measured value and the second response function. The source intensity of each fine-grid volume source is calculated based on the third measured value and the third response function, so as to realize the inversion of the source intensity distribution of the complex source term.

3. A method for inverting complex radiation fields based on multi-layer source grids, characterized in that, include: Multi-level discrete approximation is performed on the complex source term with known location and shape to be inverted to obtain a radioactive source, multiple coarse grid volume sources obtained by dividing the radioactive source, and multiple fine grid volume sources obtained by dividing each coarse grid volume source, wherein the source intensity is uniformly distributed in the radioactive source, each coarse grid source and each fine grid source. Detectors are set up for the radioactive source, all coarse-grid sources, and all fine-grid sources in different ways to detect and obtain the first measurement value corresponding to the radioactive source, the second measurement value corresponding to all coarse-grid sources, and the third measurement value corresponding to all fine-grid sources. Based on the radioactive source, all coarse-grid sources, all fine-grid sources, and the first, second, and third measurements, the source intensity distribution of the complex source term is inverted; Calculate the radiation field distribution of the complex source term after inversion; The process of performing multi-level discrete approximations on complex source terms with known locations and shapes to be inverted includes: At the location of the complex source term, a uniformly distributed radioactive source with the same shape as the complex source term is defined, and the total source intensity of the radioactive source is equal to the total source intensity of the complex source term; The radioactive source is divided into multiple coarse grid sources, and the source intensity within each coarse grid source is uniformly distributed. The sum of the source intensities of all coarse grid sources is equal to the total source intensity of the complex source term. Each coarse grid source is divided into multiple fine grid sources. The source intensity within each fine grid source is uniformly distributed. The sum of the source intensities of all fine grid sources is equal to the total source intensity of the complex source term. Furthermore, the total source intensity of any coarse grid source is equal to the total source intensity of all fine grid sources divided from that coarse grid source. The process of setting up the detector includes: A first detector is deployed at a location in a zone at a first preset distance from the radiation source, so as to obtain a first measurement value corresponding to the radiation source by detecting the first detector; In the second zone, at a second preset distance from all coarse grid volume sources, multiple second detectors are arranged to obtain the second measurement values ​​corresponding to all coarse grid volume sources through all second detectors. Multiple third detectors are deployed at three locations at a third preset distance from all fine-grid volume sources, so that the third measurement value corresponding to all fine-grid volume sources can be obtained by detecting all the third detectors.

4. The complex radiation field inversion method based on a multi-layer source grid according to claim 3, characterized in that, The process of inverting the source strength distribution of the complex source term includes: Establish a full-space particle transport model; Based on the full-space particle transport model, a radioactive source with a unit source strength is set at the radioactive source, and a detector reaction rate count is set at the first detector. The reaction rate at the first detector is obtained through transport calculation, and the reaction rate is determined as the first response function. Based on the full-space particle transport model, a radioactive source with a unit source intensity is set at each coarse grid source, and a detector reaction rate count is set at each second detector. The reaction rate at each second detector is obtained through transport calculation, and the second response function is obtained based on the reaction rate at each second detector. Based on the full-space particle transport model, a radioactive source with a unit source intensity is set at each fine grid volume source, and a detector reaction rate count is set at each third detector. The reaction rate at each third detector is obtained through transport calculation, and the third response function is obtained based on the reaction rate at each third detector. The total source intensity of the radioactive source is calculated based on the first measured value and the first response function. The source intensity of each coarse-grid volume source is calculated based on the second measured value and the second response function. The source intensity of each fine-grid volume source is calculated based on the third measured value and the third response function, so as to realize the inversion of the source intensity distribution of the complex source term.

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