Method for evaluating the exposure of in-containment robots to nuclear radiation

Abstract

The application relates to the technical field of nuclear radiation, and provides a method for evaluating nuclear radiation of a robot in a containment, which comprises the following steps: dividing a space in the containment into multiple volume elements, and obtaining total concentrations of various radionuclides in each volume element; calculating a first nuclear radiation dose of each volume element to the robot based on the volume of each volume element, the distance between each volume element and the robot, and the total concentrations of various radionuclides in each volume element; and summing up multiple first nuclear radiation doses to obtain a total nuclear radiation dose of the robot at a current position. The method for evaluating the nuclear radiation of the robot in the containment can calculate the total nuclear radiation dose of the robot at the current position, and can evaluate whether the robot can normally work in a high-radiation environment after an accident according to the relationship between the total nuclear radiation dose and a preset value. The evaluation method is simple, feasible and high in accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear radiation, in particular to a method for evaluating nuclear radiation received by a robot in a containment vessel. BACKGROUND

[0002] Nuclear safety has always been a topic of concern. Once a nuclear accident occurs in a nuclear power plant, radioactive substances originally contained in a closed container and a loop may leak into the containment vessel. As the accident progresses, radioactive substances may spread to the external environment, affecting the safety of the environment and the public. In order to reasonably dispose of the accident, a robot is needed to detect the accident environment. Therefore, it is necessary to reasonably evaluate the radiation dose received by the robot in the radiation field to ensure that the robot can work normally in the high radiation field environment after the accident.

[0003] Currently, when evaluating the radiation dose received by the robot in the radiation field, a test method is usually used. However, the test method is time-consuming and laborious, and the test conditions are difficult to achieve the actual accident conditions. At the same time, radioactive tests pose a great risk. Therefore, it is crucial to provide a new method for evaluating the nuclear radiation received by a robot. SUMMARY

[0004] The present application provides a method for evaluating the nuclear radiation received by a robot in a containment vessel, which solves the defects of time-consuming and high risk in evaluating the nuclear radiation of the robot by using the test method in the prior art.

[0005] The present application provides a method for evaluating the nuclear radiation received by a robot in a containment vessel, which includes: dividing the space in the containment vessel into a plurality of cells, obtaining the total concentration of various radionuclides in each cell; based on the volume of each cell, the distance between each cell and the robot, and the total concentration of various radionuclides in each cell, calculating the first nuclear radiation dose of each cell to the robot; summing a plurality of the first nuclear radiation dose to obtain the total nuclear radiation dose received by the robot at the current position.

[0006] According to the method for evaluating the nuclear radiation received by a robot in a containment vessel provided by the present application, the step of dividing the space in the containment vessel into a plurality of cells includes: dividing the space in the containment vessel into a plurality of cells according to the axial length of the containment vessel, the radius of the containment vessel and the azimuth angle of the three dimensions.

[0007] The method for evaluating the nuclear radiation received by the robot in the containment vessel according to the present application, the step of calculating the first nuclear radiation dose of each volume element to the robot based on the volume of each volume element, the distance between each volume element and the robot, and the total concentration of various radioactive nuclides in each volume element comprises: taking the center of the bottom surface of the containment vessel as the circle point, taking the axial length, radius and azimuth angle of the containment vessel as the coordinates to establish a cylindrical coordinate system; obtaining the first coordinates of the contour of each volume element in the cylindrical coordinate system, and calculating the volume of each volume element based on the first coordinates.

[0008] The method for evaluating the nuclear radiation received by the robot in the containment vessel according to the present application, the step of calculating the first nuclear radiation dose of each volume element to the robot based on the volume of each volume element, the distance between each volume element and the robot, and the total concentration of various radioactive nuclides in each volume element further comprises: calculating the second coordinates of the center point of each volume element based on the first coordinates; obtaining the third coordinates of the robot at the current position; and calculating the distance between the robot and each volume element based on the second coordinates and the third coordinates.

[0009] The method for evaluating the nuclear radiation received by the robot in the containment vessel according to the present application, the step of calculating the first nuclear radiation dose of each volume element to the robot based on the volume of each volume element, the distance between each volume element and the robot, and the total concentration of various radioactive nuclides in each volume element further comprises: obtaining the concentration of various radioactive nuclides in each volume element; calculating the second nuclear radiation dose of each radioactive nuclide to the robot based on the concentration, the volume of each volume element, and the distance between each volume element and the robot; and summing up the second nuclear radiation doses to obtain the first nuclear radiation dose of each volume element to the robot.

[0010] The method for evaluating the nuclear radiation received by the robot in the containment vessel according to the present application further comprises: obtaining the working time length of the robot at the current position; and calculating the first nuclear radiation dose of each volume element to the robot based on the working time length, the volume of each volume element, the distance between each volume element and the robot, and the total concentration of radioactive nuclides in each volume element.

[0011] The method for evaluating the nuclear radiation received by the robot in the containment vessel according to the present application, the step of obtaining the total concentration of various radioactive nuclides in each volume element comprises: obtaining the concentration data of various radioactive nuclides in each volume element over time.

[0012] The method for evaluating the nuclear radiation received by the robot in the containment vessel according to the present application further comprises: selecting a nuclear accident working condition that needs to be evaluated to obtain the radioactive source term leaked into the containment vessel before calculating the first nuclear radiation dose.

[0013] The evaluation method for the nuclear radiation received by the in-containment robot according to the present application further comprises: evaluating the condition of the nuclear radiation received by the robot based on the relationship between the total nuclear radiation dose and a preset value.

[0014] The evaluation method for the nuclear radiation received by the in-containment robot according to the present application further comprises: determining that the robot cannot work normally when the total nuclear radiation dose is greater than or equal to the preset value; and determining that the robot can work normally when the total nuclear radiation dose is less than the preset value.

[0015] The evaluation method for the nuclear radiation received by the in-containment robot according to the present application can calculate the total nuclear radiation dose received by the robot at the current position, and evaluate whether the robot can work normally in the high-radiation environment after an accident according to the relationship between the total nuclear radiation dose and a preset value, which is simple, feasible and has high accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0017] Figure 1 is a flow chart of the evaluation method for the nuclear radiation received by the in-containment robot according to the present application.

[0018] Figure 2 is a division diagram of a body element.

[0019] Reference signs:

[0020] 1, body element. DETAILED DESCRIPTION

[0021] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0022] The evaluation method for the nuclear radiation received by the in-containment robot according to the present application will be described below with reference to Figure 1 and Figure 2

[0023] As Figure 1 ​As shown, in an embodiment of the present invention, the method for assessing nuclear irradiation of a robot inside a containment vessel includes the following steps:

[0024] Step 100: Divide the space inside the containment into multiple volumes 1 and obtain the total concentration of various radionuclides in each volume 1; Step 200: Calculate the first nuclear radiation dose of each volume 1 to the robot based on the volume of each volume 1, the distance between each volume 1 and the robot, and the total concentration of radionuclides in each volume 1; Step 300: Sum the multiple first nuclear radiation doses to obtain the total nuclear radiation dose received by the robot at the current position.

[0025] Specifically, after a nuclear accident, radioactive nuclides leak from the reactor loop into the containment vessel. In this embodiment, the radioactive nuclides include: rare gases such as Kr and Xe; alkali metals such as Cs; and halogens such as I and Br. The concentration of radioactive nuclides varies at different locations within the containment vessel, resulting in different radiation doses received by the robot depending on its position. In this embodiment, the space within the containment vessel is divided into multiple volume elements 1. There are various ways to divide volume elements 1, such as dividing the space into multiple cylinders with different radii, or dividing the space into multiple volume elements 1 according to three dimensions: the axial length of the containment vessel, the radius of the containment vessel, and the azimuth angle. The total concentration of various radioactive nuclides within each volume element 1 is obtained. Based on each volume element 1, the distance between each volume element 1 and the robot, and the total concentration of radioactive nuclides within each volume element 1, the first radiation dose of each volume element 1 on the robot is calculated. Summing the first radiation doses of each volume element 1 yields the total radiation dose received by the robot at its current position. If the total nuclear radiation dose is greater than or equal to the preset value, it indicates that the robot cannot work normally in the current nuclear radiation environment; if the total nuclear radiation dose is less than the preset value, it indicates that the robot can work normally in the current nuclear radiation environment.

[0026] The method for assessing nuclear radiation exposure of a robot inside a containment vessel provided in this invention can calculate the total nuclear radiation dose received by the robot at its current location. Based on the relationship between the total nuclear radiation dose and a preset value, the method can assess whether the robot can work normally in a high-radiation environment after an accident. The assessment method is simple, feasible, and highly accurate.

[0027] like Figure 2 As shown, in an embodiment of the present invention, the step of dividing the space inside the containment into multiple volume elements 1 includes: dividing the space inside the containment into multiple volume elements 1 according to three dimensions: the axial length of the containment, the radius of the containment, and the azimuth angle.

[0028] Specifically, the containment is approximated as a cylinder, a cylindrical coordinate system is established with the center of the bottom circle of the cylinder as the coordinate origin, the axial length of the cylinder, the radius of the cylinder and the azimuth angle as the coordinates, as shown in Figure 2 , is the axial direction of the cylinder, is the radial direction of the cylinder, is the azimuth angle, and the coordinates of any point on the cylinder are represented as (x, r, θ). , , The space in the containment is divided into a plurality of volume elements 1 according to the three dimensions of the axial length of the cylinder , the radial length of the cylinder and the azimuth angle The more the volume elements 1 are divided, the higher the calculation accuracy is.

[0029] The calculation formula of the second nuclear radiation dose received by the robot at any position in the containment is: (Formula 1)

[0030] Wherein: is the second radiation dose received by the robot caused by the radiation of various radioactive nuclides in the containment, Gy; is the duration of radioactive irradiation received by the robot in the containment, s; is the concentration of radioactive nuclide i in the volume element j, Bq / m3; is the air kerma rate constant corresponding to the specific gas environment in the containment, (Gy / s)·(Bq / m2)-1; is the volume of the volume element j in the containment, m3; is the distance from the volume element j to the position of the robot, m. In the above formula, is a constant value, and the numerical value is related to the mass and energy of the radiation released by the radioactive nuclide, and the gas density and composition in the space.

[0031] According to the above formula, the second nuclear radiation dose of one kind of radioactive nuclide of the robot at any position in the containment can be calculated, the second nuclear radiation dose of various radioactive nuclides is accumulated to obtain the first nuclear radiation dose of each first volume element 1 to the robot, and the sum of a plurality of first nuclear radiation doses is obtained to obtain the total nuclear radiation dose. When the total nuclear radiation dose is greater than or equal to a preset value, it indicates that the robot cannot work normally in the containment.

[0032] In the embodiment of the present application, the calculation method of the volume of each volume element 1 is: obtaining each first coordinate of the outline of the volume element 1 in the cylindrical coordinate system, and calculating the volume of the volume element 1 based on the first coordinate.

[0033] Specifically, it is assumed that the volume element 1 is in the first quadrant of the cylindrical coordinate system, and the first coordinate of the outline of the volume element 1 in the cylindrical coordinate system is (x1, r1, θ1), (x2, r2, θ2), (x3, r3, θ3) and (x4, r4, θ4). The first coordinate of the direction is , The range of the volume element 1 in the direction is Correspondingly, the range of the volume element 1 in the direction can be determined as The azimuth angle range is The volume of the volume element can be expressed as .

[0034] The distance of each volume element 1 to the position of the robot in the containment vessel is calculated as follows:

[0035] The second coordinate of the center point of the volume element j is expressed as wherein , , The third coordinate of the robot at the current position is assumed to be At this time, the distance of the volume element j to the position of the robot in the containment vessel is expressed as:

[0036] According to formula 1, the total nuclear radiation dose received by the robot at a certain position in the containment vessel is related to the working time length of the robot in the containment vessel. The longer the working time length is, the greater the total nuclear radiation dose received is.

[0037] Specifically, the work of the robot in the containment vessel is not limited to a certain position. In the entire working time length, the robot may need to work at multiple positions. Therefore, after the position of the robot changes, the total nuclear radiation dose received by the robot at the current position can be calculated according to formula 1 according to the above method.

[0038] According to the above method, the total nuclear radiation dose of the robot at each position can be calculated according to the working time length of the robot at each position in actual work. The total nuclear radiation dose at each position is accumulated, and then the working time length of the robot in the containment vessel under the current accident condition can be obtained, so as to better evaluate and guide the work of the robot in the high radiation environment.

[0039] In an embodiment of the present application, the in formula 1 can be a fixed value, that is, in the case that the concentration of various radioactive nuclides in the containment vessel no longer changes, the robot is placed in the containment vessel to calculate the nuclear radiation dose received by the robot.

[0040] In another embodiment of the present application, the ​​​​​The robot can also be placed in the containment vessel when the nuclear accident occurs and the radionuclides start to leak into the containment vessel, at which time the concentration of the radionuclides in the containment vessel increases with time. In this embodiment, the concentration data of the radionuclides in each voxel 1 over time can be obtained when the total concentration of the radionuclides in each voxel is obtained. For example, when the radionuclides do not leak, the robot is located in the containment vessel, and when the radionuclides start to leak into the containment vessel, the robot starts to work. At this time, the working time of the robot is equal to the time length of the diffusion of the radionuclides into the containment vessel, and the concentration of the radionuclides in each voxel 1 at this time can be obtained according to the time length.

[0041] In the embodiments of the present application, the evaluation method further comprises: before calculating the first nuclear irradiation dose, selecting a nuclear accident working condition that needs to be evaluated, and obtaining the radioactive source term that leaks into the containment vessel.

[0042] Specifically, based on the nuclear accident source term analysis and evaluation program, the nuclear accident working condition that needs to be evaluated is selected according to the design parameters of a specific reactor type, and the radioactive source term that leaks from the reactor loop into the containment vessel after the nuclear accident occurs is calculated.

[0043] The evaluation method for the nuclear irradiation of the robot in the containment vessel provided in the embodiments of the present application can quickly and efficiently calculate the irradiation dose of the robot in the radiation field and evaluate whether the robot can normally work in the high radiation environment after the accident. At the same time, the radiation field distribution results caused by different nuclear accidents can be simulated, and the nuclear irradiation dose of the robot at any position in the containment vessel can be calculated, so that the work of the robot under different working conditions can be evaluated, and the adaptability is stronger.

[0044] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for evaluating the exposure of a containment-in-machine robot to nuclear radiation, characterized in that, The method comprises the following steps: dividing the space in the containment vessel into a plurality of cells, and obtaining the total concentration of various radionuclides in each cell; calculating the first nuclear radiation dose of each cell to the robot based on the volume of each cell, the distance between each cell and the robot, and the total concentration of various radionuclides in each cell; summing up a plurality of the first nuclear radiation doses to obtain the total nuclear radiation dose received by the robot at the current position; the step of calculating the first nuclear radiation dose of each cell to the robot based on the volume of each cell, the distance between each cell and the robot, and the total concentration of various radionuclides in each cell further comprises: obtaining the concentration of various radionuclides in each cell; calculating the second nuclear radiation dose of each radionuclide to the robot based on the concentration, the volume of each cell, and the distance between each cell and the robot; summing up a plurality of the second nuclear radiation doses to obtain the first nuclear radiation dose of each cell to the robot.

2. The method of claim 1, wherein, The step of dividing the space in the containment vessel into a plurality of cells comprises: dividing the space in the containment vessel into a plurality of cells according to the axial length, radius, and azimuth angle of the containment vessel.

3. The method of claim 1, wherein the method further comprises: The step of calculating the first nuclear radiation dose of each cell to the robot based on the volume of each cell, the distance between each cell and the robot, and the total concentration of various radionuclides in each cell comprises: establishing a cylindrical coordinate system with the center of the bottom surface of the containment vessel as the origin, and with the axial length, radius, and azimuth angle of the containment vessel as the coordinates; obtaining the first coordinates of the profile of each cell in the cylindrical coordinate system, and calculating the volume of each cell based on the first coordinates.

4. The method of claim 3, wherein the method further comprises: The step of calculating the first nuclear radiation dose of each cell to the robot based on the volume of each cell, the distance between each cell and the robot, and the total concentration of various radionuclides in each cell further comprises: calculating the second coordinates of the center point of each cell based on the first coordinates; obtaining the third coordinates of the robot at the current position; calculating the distance between the robot and each cell based on the second coordinates and the third coordinates.

5. The method of claim 1, wherein, The method further comprises: obtaining the working time of the robot at the current position; calculating the first nuclear radiation dose of each cell to the robot based on the working time, the volume of each cell, the distance between each cell and the robot, and the total concentration of radionuclides in each cell.

6. The method of evaluating the exposure of a containment-in-plant robot to nuclear radiation according to claim 1, wherein, The step of obtaining the total concentration of various radionuclides in each cell comprises: obtaining the concentration data of various radionuclides in each cell over time.

7. The method of claim 1, wherein the method further comprises: The evaluation method further comprises: before calculating the first nuclear radiation dose, selecting a nuclear accident working condition that needs to be evaluated, and obtaining the radioactive source term leaked into the containment vessel.

8. The method of claim 1, wherein, The evaluation method further comprises: evaluating the condition of the robot subjected to nuclear radiation based on the relationship between the total nuclear radiation dose and a preset value.

9. The method of evaluating the exposure of a containment-in-plant robot to nuclear radiation according to claim 8, wherein, The evaluation method further comprises: when the total nuclear radiation dose is greater than or equal to the preset value, determining that the robot cannot work normally. When the total nuclear radiation dose is less than the preset value, it is determined that the robot can work normally.

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