Method for rapidly determining radiation field before and after reactor item cutting

Abstract

The embodiment of the invention relates to the technical field of computer-aided simulation, in particular to a method for rapidly determining a radiation field before and after reactor item cutting, and the method comprises the following steps: S1, obtaining geometric parameters and physical attribute parameters of a reactor; s2, determining a digital model of the reactor according to the geometric parameters and the physical attribute parameters of the reactor; s3, determining a radiation source of the reactor according to the digital model; and S4, determining a radiation field in the reactor according to the radiation source. According to the method provided by the embodiment of the invention, the radiation field in the reactor is determined according to the digital model of the reactor, and a worker does not need to enter the high-radiation reactor, so that the worker can be prevented from being influenced by radiation.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of computer-aided simulation technology, and in particular to a method for quickly determining the radiation field before and after cutting of a reactor item. Background Art

[0002] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0003] After a reactor is decommissioned, it needs to be dismantled. Before and during dismantling, the radiation field dose inside the reactor needs to be determined, and the dismantling plan and related protective measures need to be determined based on the radiation field dose. Summary of the invention

[0004] A brief overview of the present application is provided below in order to provide a basic understanding of certain aspects of the present application. It should be understood that this overview is not an exhaustive overview of the present application. It is not intended to identify the key or important parts of the present application, nor is it intended to limit the scope of the present application. Its purpose is merely to present certain concepts in a simplified form as a prelude to a more detailed description discussed later.

[0005] An embodiment of the present application provides a method for quickly determining the radiation field before and after a reactor item is cut, comprising the following steps S1 to S4: S1: obtaining geometric parameters and physical property parameters of the reactor; S2: determining a digital model of the reactor based on the geometric parameters and physical property parameters of the reactor; S3: determining the radiation source of the reactor based on the digital model; S4: determining the radiation field inside the reactor based on the radiation source.

[0006] The method provided in the embodiment of the present application determines the radiation field inside the reactor based on the digital model of the reactor, does not require workers to enter the interior of the high-radiation reactor, and can prevent workers from being affected by radiation. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] In order to further illustrate the above and other advantages and features of the present application, the specific embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. The accompanying drawings together with the following detailed description are included in this specification and form a part of this specification. Elements with the same function and structure are represented by the same reference numerals. It should be understood that these drawings only describe typical examples of the present application and should not be regarded as limiting the scope of the present application.

[0008] Figure 1 is a flow chart of a method for quickly determining the radiation field before and after the cutting of a reactor item according to an embodiment of the present application;

[0009] Figure 2ais a schematic diagram of a radiation source and a radiation field for visual rendering according to an embodiment of the present application;

[0010] Figure 2b yes Figure 2a Schematic diagram of the radiation source and radiation field after the cover is removed;

[0011] Figure 2c yes Figure 2b Schematic diagram of the radiation source and radiation field after adjusting the rendering parameters;

[0012] Figure 2d yes Figure 2c Schematic diagram of the radiation field generated after the radiation source in is cut;

[0013] Figure 2e yes Figure 2d Schematic diagram of the radiation field generated after the radiation source in moves.

[0014] It should be noted that the drawings are not necessarily drawn to scale, but are merely shown in a schematic manner that does not affect the reader's understanding.

[0015] Description of reference numerals: 100, radiation source; 110, first radiation source; 120, remaining radiation sources; 200, radiation field. DETAILED DESCRIPTION

[0016] Exemplary embodiments of the present application will be described below in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features of the actual implementation are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the process of developing any such actual implementation in order to achieve the developer's specific goals, such as meeting those constraints related to the system and business, and these constraints may vary from implementation to implementation. In addition, it should be understood that although the development work may be very complex and time-consuming, it is only a routine task for those skilled in the art who benefit from the content of this application.

[0017] It is also necessary to explain here that, in order to avoid obscuring the present application due to unnecessary details, only the device structure and / or processing steps closely related to the scheme according to the present application are shown in the accompanying drawings, while other details that are not very relevant to the present application are omitted.

[0018] The disclosure below provides a plurality of different embodiments or examples to implement the present application. In order to simplify the disclosure of the present application, the parts and methods of specific examples are described below. Of course, they are merely examples, and the purpose is not to limit the present application. In the description of the embodiments of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically limited.

[0019] When it is necessary to determine the radiation field inside the reactor, it is difficult to directly measure the radiation field inside the reactor because the radiation dose inside the reactor is very large and has a strong impact on the human body and machinery. It is necessary to use other methods to determine the radiation field inside the reactor.

[0020] See also Figure 1 , an embodiment of the present application provides a method for quickly determining the radiation field before and after the cutting of a reactor item, comprising the following steps S1 to S4:

[0021] S1: Obtain the geometric parameters and physical property parameters of the reactor.

[0022] S2: Determine the digital model of the reactor based on the geometric parameters and physical property parameters of the reactor.

[0023] S3: Determine the radiation source of the reactor based on the digital model.

[0024] S4: Determine the radiation field inside the reactor based on the radiation source.

[0025] The method provided in the embodiment of the present application determines the radiation field inside the reactor based on the digital model of the reactor, does not require workers to enter the interior of the high-radiation reactor, and can prevent workers from being affected by radiation.

[0026] In some embodiments, step S4 also includes the following steps: determining that the radiation source is a point radiation source; determining a spherical surface of arbitrary radius with the radiation source as the center; determining the number of photons emitted by the radiation source that pass through the spherical surface; and determining the radiation field inside the reactor based on the number of photons.

[0027] The radiation from a point radiation source is isotropic, so the radiation intensity of the point radiation source at different distances from itself can be determined by establishing a spherical surface, thereby determining the radiation field inside the reactor.

[0028] In some embodiments, the method further includes: determining the number of gamma photons emitted by the point radiation source; determining the radius of the spherical surface; and determining the number of photons passing through the spherical surface based on the position, radius and number of gamma photons of the point radiation source.

[0029] Since the number of gamma photons emitted by a point radiation source per unit time is certain, once the number of gamma photons is determined, the number of photons passing through a unit area of ​​the sphere per unit time can be determined based on the radius of the sphere.

[0030] In some embodiments, the position, radius, and number of gamma photons of the point radiation source, as well as the number of photons passing through the spherical surface satisfy the following expressions:

[0031]

[0032] In the formula, Φ is the number of photons passing through the spherical surface, S0 is the number of γ photons, r is the position of the point radiation source, (r p -r) is the radius of the sphere.

[0033] Through the above expression, the number of photons passing through the spherical surface can be accurately determined.

[0034] In some embodiments, in step S43, the influence of the shielding material of the reactor and the environment of the reactor on the radiation emitted by the point radiation source is determined, and the number of photons is corrected according to the influence.

[0035] There are shielding materials in the reactor. The gamma photons emitted by the point radiation source will produce a certain degree of attenuation when passing through the shielding material. In addition, factors such as the material of the radiation source, the energy of the gamma photons, and the optical distance will also affect the number of gamma photons emitted by the point radiation source. Therefore, when calculating the radiation field inside the reactor, it is necessary to consider the influence of these factors to make the determined radiation field closer to the actual situation.

[0036] In some embodiments, the corrected number of photons, the effect of the shielding material, and the effect of the environment meet the following relationship:

[0037]

[0038] In the formula, Φ′ is the corrected photon number, B is the impact of the environment on the photon number, and μt is the impact of the reactor shielding material on the photon number.

[0039] Through the above expression, a radiation field closer to the actual situation can be obtained. Furthermore, when there are multiple shielding materials or environmental factors that affect the radiation field, these factors can be summed up before being substituted into the above expression. The summed expression is as follows:

[0040] μt=Σμ i t i , B=B mix (B1, ..., B n ),

[0041] Among them, when calculating the impact of the environment on the number of photons, the numerical values ​​in the database can be used for calculation according to parameters such as material type, γ source characteristics, and optical distance.

[0042] In some embodiments, step S4 also includes the following steps: determining whether the radiation source is a surface radiation source or a body radiation source; discretizing the surface radiation source or the body radiation source to obtain multiple point radiation sources; determining a spherical surface of arbitrary radius with multiple point radiation sources as the center; determining the number of photons emitted by the radiation source passing through the spherical surface; determining the radiation field inside the reactor based on the number of photons; determining the relationship between the number of photons and one of the air kerma, ambient dose equivalent, personal dose equivalent and effective dose under different irradiation modes; based on the relationship, determining the superposition of the radiation fields inside the reactor for multiple point radiation sources, and determining the radiation field of the surface radiation source or the body radiation source based on the superposition of the radiation fields.

[0043] When the radiation source is a surface radiation source or a body radiation source, on the one hand, the center of the sphere cannot be directly determined, and on the other hand, since the shape of the radiation source itself is not uniformly distributed in all directions, the radiation of the radiation source is no longer isotropic. Based on the above reasons, the surface radiation source or body radiation source can be discretized to obtain multiple point radiation sources, and the radiation field of the surface radiation source or body radiation source can be determined by superimposing the radiation fields of the point radiation sources.

[0044] In some embodiments, when discretizing a surface radiation source or a volume radiation source, if the radiation source is of a regular shape, the discretization is performed by using a coordinate discretization method; if the radiation source is of an irregular shape, the discretization is performed by using a Monte Carlo sampling method.

[0045] In some embodiments, the radiation value of some points inside the reactor can be determined first, for example, by actual measurement, and the actual activity of the radiation source can be determined based on the determined radiation value, and the determined radiation field can be corrected based on the actual activity of the radiation source.

[0046] The determined digital model of the reactor cannot be exactly the same as the actual reactor, and the errors therein will affect the radiation field determined, and the errors cannot be eliminated by the aforementioned methods. Using the radiation values ​​of some points to determine the actual activity of the radiation source can overcome the influence of the above errors and make the determined radiation field closer to the actual situation.

[0047] In some embodiments, step S1 includes the following steps: setting a plurality of reference devices inside and outside the reactor, and establishing a coordinate system about the reactor according to the positions of the reference devices; setting a plurality of scanning points inside the reactor, recording the coordinates of the scanning points, and scanning the reactor at the scanning points, converting the scanned photos into point cloud data, and obtaining the geometric parameters and physical property parameters of the reactor according to the point cloud data.

[0048] In some embodiments, step S2 includes the following steps: importing point cloud data into modeling software, using modeling software to remove content that is not related to the reactor in the point cloud data, splicing and coloring the processed point cloud data according to the position of a reference device, and converting the spliced ​​and colored point cloud data into a digital model of the reactor.

[0049] The radiation field determined by the above method is a plurality of sets of values ​​about the coordinates. In order to make the radiation field of the reactor more intuitive, especially in the process of cutting and moving the radiation source, it can be clearly seen that the radiation field changes with the radiation source, in some embodiments, the corresponding relationship between the intensity and color of the radiation field can be determined, and the determined radiation field is visualized and rendered according to the relationship, and the visualized radiation field is superimposed on the digital model of the reactor.

[0050] See also Figure 2a to Figure 2e , which shows the changes in the radiation field during the process of cutting and moving the radiation source in one embodiment. The radiation source is a tank loaded with radioactive materials. The tank is 200 cm high, 80 cm in outer radius, 3 cm thick, and made of stainless steel. A uniform surface source is set on the inner wall, and the total activity is 2E+9Bq. Figure 2a The radiation source 100 and its radiation field 200 are shown, wherein the darker the color, the stronger the radiation field 200. Since the cover on the radiation source 100 has a shielding effect, the radiation field 200 generated by it is relatively weak. Figure 2b In the embodiment, the cover is removed, and the shielding effect of the shielding material on the radiation source 100 is reduced, so Figure 2b The radiation field 200 generated above the radiation source 100 in Figure 2a The radiation field in 200.

[0051] Furthermore, in the process of visually rendering the radiation field 200 , by adjusting the rendering parameters, the color of the same radiation field 200 can be changed, thereby making the visual effect of the radiation field 200 more obvious. Figure 2c Shows the adjustment Figure 2b The radiation field 200 after the rendering parameters in Figure 2b The radiation field 200 in is exactly the same, but its visual effect is more obvious. Figure 2d FIG. 1 shows the first radiation source 110 and the remaining radiation source 120 obtained after cutting the body radiation source 100. It can be seen that after the first radiation source 110 is lifted upward, the intensity of the radiation field 200 below the remaining radiation source 120 is greater than Figure 2c Middle and lower. Figure 2e FIG. 2 shows the radiation field 200 after the first radiation source 110 is horizontally moved for a certain distance. It can be seen that the radiation field 200 also moves to a certain extent along the direction of the first radiation source 110. Figure 2a to Figure 2e It is shown that the method provided in the embodiment of the present application can accurately and intuitively determine and represent the changes in the radiation field 200 during the process of cutting and moving the radiation source 100.

[0052] The method of the present application is described below with reference to specific embodiments.

[0053] A plurality of reference devices are set up inside and outside the reactor, and a coordinate system of the reactor is established according to the positions of the reference devices. A plurality of scanning points are set up inside the reactor, and the coordinates of the scanning points are recorded. The reactor is scanned at the scanning points, and the scanned photos are converted into point cloud data. The geometric parameters and physical property parameters of the reactor are obtained according to the point cloud data.

[0054] The point cloud data is imported into the modeling software, and the modeling software is used to remove the content that is not related to the reactor in the point cloud data. The processed point cloud data is spliced ​​and colored according to the position of the reference device, and the spliced ​​and colored point cloud data is converted into a digital model of the reactor. According to the digital model, the radiation source of the reactor is determined.

[0055] When the radiation source is determined to be a point radiation source, determine a spherical surface of arbitrary radius with the radiation source as the center; determine the number of gamma photons emitted by the point radiation source; determine the radius of the spherical surface, and determine the number of photons emitted by the radiation source that pass through the spherical surface based on the position, radius and number of gamma photons of the point radiation source; determine the influence of the shielding material of the reactor and the environment of the reactor on the radiation emitted by the point radiation source, and correct the number of photons based on the influence; and determine the radiation field inside the reactor based on the number of photons.

[0056] When it is determined that the radiation source is a surface radiation source or a body radiation source, the surface radiation source or the body radiation source is discretized to obtain multiple point radiation sources, wherein if the radiation source is of a regular shape, the discretization is performed by using a coordinate discretization method, and if the radiation source is of an irregular shape, the discretization is performed by using a Monte Carlo sampling method; a spherical surface of arbitrary radius with multiple point radiation sources as the sphere center is determined; the number of photons of radiation emitted by the radiation source passing through the spherical surface is determined; based on the number of photons, the radiation field inside the reactor is determined; the relationship between the number of photons and one of the air kerma, ambient dose equivalent, personal dose equivalent and effective dose under different irradiation modes is determined; based on the relationship, the radiation field superposition inside the reactor is determined for multiple point radiation sources, and based on the superposition of the radiation fields, the radiation field of the surface radiation source or the body radiation source is determined.

[0057] After determining the radiation field of the radiation source, the radiation values ​​of some points inside the reactor are measured and determined, and the actual activity of the radiation source is determined based on the determined radiation value, and the determined radiation field is corrected based on the actual activity of the radiation source. The corresponding relationship between the intensity and color of the corrected radiation field is determined, and the determined radiation field is visualized and rendered based on the relationship, and the visualized radiation field is superimposed on the digital model of the reactor.

[0058] Regarding the embodiments of the present application, it should also be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other to obtain new embodiments.

[0059] The above are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. The protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for quickly determining the radiation field before and after cutting of a reactor item, characterized in that: The following steps are involved: S1: Obtaining geometric parameters and physical property parameters of the reactor; S2: Determine a digital model of the reactor according to geometric parameters and physical property parameters of the reactor; S3: Determine the radiation source of the reactor according to the digital model; S4: Determine the radiation field inside the reactor according to the radiation source.

2. The method according to claim 1, characterized in that In step S4, the following steps are also included: Determining that the radiation source is a point radiation source; Determine a spherical surface with an arbitrary radius and with the radiation source as the center; Determining the number of photons emitted by the radiation source that pass through the spherical surface; The radiation field inside the reactor is determined according to the photon number.

3. The method according to claim 2, characterized in that Determining the number of gamma photons emitted by the point radiation source; determining the radius of the spherical surface; The number of photons passing through the spherical surface is determined according to the position of the point radiation source, the radius and the number of gamma photons.

4. The method according to claim 3, characterized in that The position of the point radiation source, the radius and the number of gamma photons, and the number of photons passing through the spherical surface satisfy the following expression: Where, Φ is the number of photons passing through the spherical surface, S0 is the number of γ photons, r is the position of the point radiation source, (r p -r) is the radius of the sphere.

5. The method according to claim 4, characterized in that In step S43, determining the effect of the shielding material of the reactor and the environment of the reactor on the radiation emitted by the point radiation source, The photon number is corrected according to the influence.

6. The method according to claim 5, characterized in that The corrected number of photons, the influence of the shielding material, and the influence of the environment conform to the following relationship: In the formula, Φ ′ is the corrected photon number, B is the influence of the environment on the photon number, and μt is the influence of the shielding material of the reactor on the photon number.

7. The method according to claim 2, characterized in that: In step S4, the following steps are also included: determining that the radiation source is a surface radiation source or a body radiation source; discretizing the surface radiation source or the volume radiation source to obtain a plurality of point radiation sources; Determine a spherical surface with any radius and with the multiple point radiation sources as the sphere center; Determining the number of photons emitted by the radiation source that pass through the spherical surface; determining a radiation field inside the reactor according to the number of photons; Determining the relationship between the number of photons and one of air kerma, ambient dose equivalent, personal dose equivalent and effective dose under different irradiation modes; According to the relationship, determining the radiation field superposition inside the reactor for the multiple point radiation sources, The radiation field of the surface radiation source or the body radiation source is determined according to the superposition of the radiation fields.

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