Decomposable range display method, decomposition method, and decomposable range display system

Abstract

A decomposable range display method displays a decomposable range in a decomposable object having a predetermined structure, the decomposable range display method displaying a decomposable range corresponding to a sampling position of the decomposable object based on measurement information of a radiation dose and a radiation energy at the sampling position and distribution information related to a radioactive distribution in a depth direction corresponding to the sampling position.

Description

Technical Field

[0001] This disclosure relates to a method for displaying decomposable ranges, a decomposition method, and a system for displaying decomposable ranges. Background Technology

[0002] Previously, the device shown in Patent Document 1 was known as a device with a structure that is susceptible to radiation activation. The device shown in Patent Document 1 is a self-shielded cyclotron that generates radiation during operation. Therefore, during disposal, the radiation-activated parts of the device and surrounding components need to be decomposed and disposed of as radioactive contaminants.

[0003] Previous technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2019-160462 Summary of the Invention

[0004] The technical problem to be solved by the invention Here, for the aforementioned self-shielding objects and other decomposition targets, it is necessary to distinguish between activated and non-activated portions. In particular, the activation of these decomposition targets occurs not only on the surface but sometimes also at depth. Therefore, to determine the radioactivity concentration at depth, core boring is required to obtain samples, which are then segmented along the depth direction to measure their radioactivity concentration. Such operations need to be performed on multiple parts of the self-shielding object.

[0005] Therefore, the purpose of this disclosure is to provide a method, method and system for easily displaying decomposable ranges.

[0006] means for solving technical problems An embodiment of this disclosure relates to a method for displaying the decomposable range, which is used to display the decomposable range in a decomposable object having a predetermined structure. The method displays the decomposable range corresponding to a sampling position based on measurement information of radiation dose and radiation energy at a predetermined sampling position of the decomposable object, and distribution information related to the radioactivity distribution in the depth direction corresponding to the sampling position.

[0007] This method for displaying the resolvable range uses measurement information of radiation dose and radiation energy at a predetermined sampling location of the object to be decomposed, along with distribution information related to the radioactivity distribution along the depth direction corresponding to the sampling location, to display the resolvable range corresponding to the sampling location. Thus, by using measurement and distribution information, the resolvable range corresponding to the sampling location can be displayed. In summary, the resolvable range can be easily displayed.

[0008] For sampling locations, a radiation meter can be used to measure radiation dose and radiation energy. Thus, by using a radiation meter, simple measurements can be achieved without destructive operations such as core drilling.

[0009] The object to be decomposed may consist of a radiation source that generates radiation and a shielding body that covers the radiation source using shielding components. Because the shielding body covers the radiation source, its activation extends to the depth direction, but the decomposable range can be easily shown according to this disclosure.

[0010] The radiation source is a target device irradiated by a particle beam from an accelerator, and the shield can be a self-shielding device covering the target device. The activation state of the self-shielding device varies depending on its location, therefore, the self-shielding device needs to be measured at multiple sampling locations. Thus, by employing a non-destructive measurement method, the effect of easily displaying the resolvable range can be more significantly achieved.

[0011] The objects to be decomposed can include, for example, steel plates and concrete.

[0012] The decomposable range display method can further include: a calculation step, which sets up a virtual simulation model of the object to be decomposed and calculates the radioactivity concentration at various locations in the depth direction from the surface in the model; a measurement step, which prepares the physical object to be decomposed, obtains a core sample extending from the sampling location into the depth direction from the physical object, and simultaneously measures the radioactivity concentration of the core sample; and a distribution information acquisition step, which obtains distribution information related to the radioactivity concentration distribution in the depth direction corresponding to the sampling location based on the radioactivity concentration obtained in the calculation step and the radioactivity concentration obtained in the measurement step. In this case, by combining the virtual model and using the physical object, the radioactivity concentration in the depth direction can be accurately and easily determined.

[0013] The decomposition method according to one embodiment of this disclosure can decompose an object to be decomposed based on a decomposable range displayed by the aforementioned decomposable range display method. By performing the decomposition operation according to the range displayed by the aforementioned decomposable range display method, the decomposition operation can be easily performed.

[0014] An embodiment of the present disclosure discloses a decomposable range display system for displaying the decomposable range of a decomposable object having a predetermined structure. The decomposable range display system includes a display unit that displays the decomposable range corresponding to a sampling position based on measurement information of radiation dose and radiation energy at a predetermined sampling position of the decomposable object, and distribution information related to the radioactivity distribution in the depth direction corresponding to the sampling position.

[0015] According to this decomposable range display system, the same effect as the decomposable range display method described above can be achieved.

[0016] Invention Effects According to this disclosure, a method for displaying decomposable range, a decomposition method, and a system for displaying decomposable range can be provided that can easily display the decomposable range. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating a decomposable range display system for implementing the decomposable range display method according to this embodiment.

[0018] Figure 2 This is a top sectional view of the self-shielded accelerator 1.

[0019] Figure 3 This is a front view of the self-shielded accelerator 1, omitting the side wall portion near the front.

[0020] Figure 4 This is a process diagram illustrating the decomposition method.

[0021] Figure 5 This is a process diagram showing the detailed processing content of the method for obtaining distribution information (step S10).

[0022] Figure 6 This is a process diagram showing the detailed processing content of the method for obtaining distribution information (step S10).

[0023] Figure 7 This is a diagram showing the virtual model.

[0024] Figure 8 This is a table showing the experimental conditions.

[0025] Figure 9 This is a table showing the calculated results of the detection efficiency.

[0026] Figure 10 This is a table showing the system weights of steel plates and concrete of various diameters.

[0027] Figure 11 It shows Rw L and Rw total The table shows the calculation results.

[0028] Figure 12 It shows A L A chart of the calculation results.

[0029] Figure 13 This is a table summarizing the analytical results and radioactivity calculation conditions for sampling locations SP1 to SP8.

[0030] Figure 14 This is a table summarizing the analytical results and radioactivity calculation conditions for sampling locations SP1 to SP8.

[0031] Figure 15 This is a table summarizing the analytical results and radioactivity calculation conditions for sampling locations SP1 to SP8.

[0032] Figure 16 This is a chart comparing the radioactive depth distribution calculated based on a virtual model with the depth distribution obtained through physical measurements.

[0033] Figure 17 This is a chart comparing the radioactive depth distribution calculated based on a virtual model with the depth distribution obtained through physical measurements.

[0034] Figure 18 This is a chart comparing the radioactive depth distribution calculated based on a virtual model with the depth distribution obtained through physical measurements.

[0035] Figure 19 This is a chart comparing the radioactive depth distribution calculated based on a virtual model with the depth distribution obtained through physical measurements.

[0036] Figure 20 This is a process diagram that shows the process steps that can be broken down into their constituent parts.

[0037] Figure 21 This is a diagram showing the content displayed on the display unit. Detailed Implementation

[0038] Hereinafter, with reference to the accompanying drawings, the method for displaying the decomposable range according to the embodiments of this disclosure will be described in detail. Furthermore, in the description, the terms "upper" and "lower" are sometimes used, corresponding to the upper and lower directions in the accompanying drawings.

[0039] The decomposable range display method involved in this embodiment is a method for displaying the decomposable range of a decomposable object 50 having a predetermined structure that should be decomposed due to activation. Figure 1 This is a schematic diagram showing a decomposable range display system 100 for implementing the decomposable range display method according to this embodiment.

[0040] The object to be decomposed 50 is a structure that needs to be partially or completely decomposed due to activation. The object to be decomposed 50 may, for example, include a radiation source that generates radiation and a shielding body that covers the radiation source using shielding components. As such an object to be decomposed 50, it can be adopted as... Figure 2 and Figure 3The self-shielded accelerator 1 is shown. In this case, the main radiation source is the target device 10. The shielding body is a self-shielding body 6 covering the target device 10. The object to be decomposed 50 may have a steel plate 17 and concrete 18. However, the object to be decomposed 50 is not limited to the combination of steel plate 17 and concrete 18; for example, it may be only concrete 18 or only steel plate 17. "Heavy concrete" is used as the concrete 18 for the self-shielding body 6. However, "ordinary concrete" can also be used as the concrete 18. Since the cobalt contained in iron in heavy concrete is activated (60Co), it is sufficient to observe its distribution. Furthermore, the inventors of this application have found that cobalt is dominant in heavy concrete. On the other hand, in ordinary concrete, it is sufficient to observe the distribution of activated europium.

[0041] Furthermore, the object to be decomposed 50 is not limited to the self-shielded accelerator 1, but can also be a two-layer shielding wall in the case of a non-self-shielded body but a wall-shielded body. For example, it can be a concrete / iron plate installed under the ceiling. In addition, the object to be decomposed 50 can also be a shielding wall installed in an accelerator without a self-shielded body. Accelerators without self-shielded bodies can be, for example, accelerators for various purposes such as: accelerators for treatment devices that treat cancer by irradiating charged particle beams, accelerators for neutron capture therapy systems that treat cancer using boron neutron capture therapy (BNCT), accelerators for PET, accelerators for RI manufacturing, and accelerators for nuclear experiments. In addition, for example, in the case of a particle beam therapy device, the main radiation source can be a collimator, deflector, damper, etc., installed inside the accelerator to process the beam emitted from the accelerator. Furthermore, the radiation source can be an energy reducer (for attenuating energy), collimator, etc., installed midway along the path of the particle beam emitted from the accelerator until it reaches the irradiation section. When protons strike a de-energizer, scattering occurs, producing neutrons. In the case of BNCT, the radiation source can be a target that emits neutron lines by irradiating a proton beam.

[0042] Here, refer to Figure 2 and Figure 3 The structure of the self-shielded accelerator 1, an example of the decomposition object 50, will be explained. Figure 2 This is a top sectional view of the self-shielded accelerator 1. Figure 3 This is a front view of the self-shielded accelerator 1, omitting the near-anterior sidewall portion.

[0043] like Figure 2 and Figure 3As shown, the self-shielded accelerator 1 includes a target device 10. The self-shielded accelerator 1 functions as an RI manufacturing apparatus for producing radioisotopes (RI). For example, the self-shielded accelerator 1 can be used as a cyclotron for PET scans, and the RI produced by the self-shielded accelerator 1 can be used, for example, for the manufacture of radioisotope labeling compounds (RI compounds), i.e., radiopharmaceuticals (including radiopharmaceuticals). As a radioisotope labeling compound for PET scans (positron emission tomography) in hospitals, etc., there are... 18 F-FDG (fluorodeoxyglucose) 18 F-FLT (fluorothymidine) 18 F-FMISO (fluoromisonidazole) 11 C-Racloprid, etc.

[0044] Figure 2 and Figure 3 The self-shielded accelerator 1 illustrated herein is a so-called self-shielded particle accelerator system, comprising: an accelerator 2 for accelerating charged particles, and a radiation shield, i.e., a self-shielding body 6, for surrounding the accelerator 2 and shielding its radiation. In the internal space S formed by the self-shielding body 6, in addition to the accelerator 2, a target device 10 for producing RI, a vacuum pump 4 for creating a vacuum inside the accelerator 2, and other similar equipment are also arranged in the internal space S. Furthermore, accessories necessary for the operation of the accelerator 2, auxiliary equipment for cooling the target device 10, and other similar equipment are also arranged in the internal space S.

[0045] like Figure 2 and Figure 3 As shown, the target device 10 is used to receive the charged particle beam B irradiated from the accelerator 2 to produce RI, and has a container for raw materials (e.g., target water) formed inside. 18 The target device 10 is a container for water. The target device 10 is covered by target shields 7 and 8 mounted on the accelerator 2. The inner peripheral target shield 8 is made of resin such as polyethylene. The outer peripheral target shield 7 is made of lead, for example.

[0046] The self-shielding body 6 is composed of multiple parts and is formed to cover the accelerator 2 and the target device 10. The self-shielding body 6 is a structure in which the accelerator 2 and the target device 10 are disposed internally, and RI is produced by irradiating the target with a charged particle beam B from the accelerator 2 inside the body. The self-shielding body 6 is a structure used to shield the radiation generated during the production of RI and prevent it from leaking to the outside of the self-shielding body 6.

[0047] like Figure 2As shown, the self-shielding body 6 includes sidewall portions 11 and 12 facing each other in the irradiation direction of the charged particle beam B, and sidewall portions 13 and 14 facing each other in the horizontal direction orthogonal to the irradiation direction of the charged particle beam B. Sidewall portions 11 and 12 are configured to be separate from each other, and sidewall portions 13 and 14 are configured to be separate from each other. One end of sidewall portions 13 and 14 is connected to both ends of sidewall portion 11, and the other end of sidewall portions 13 and 14 is connected to both ends of sidewall portion 12. Thus, the internal space S of the self-shielding body 6 is surrounded without gaps by sidewall portions 11, 12, 13, and 14.

[0048] like Figure 3 As shown, the upper end of the self-shielding body 6 is closed by the upper wall portion 15. That is, the upper wall portion 15 is connected to the upper ends of the side wall portions 11, 12, 13, and 14. The lower ends of the side wall portions 11, 12, 13, and 14 are provided on the floor 16. Thus, the internal space S surrounded by the side wall portions 11, 12, 13, and 14 is closed without gaps in the vertical direction by the upper wall portion 15 and the floor 16.

[0049] like Figure 3 As shown, the self-shielding body 6 has a steel plate 17 and concrete 18. Each wall portion 11, 12, 13, 14, 15 of the self-shielding body 6 has concrete 18 between the steel plate 17 constituting the outer shell and the steel plate 17 constituting the inner shell.

[0050] return Figure 1 The decomposable range display system 100 is a system for displaying the decomposable range of the object to be decomposed 50 that should decompose due to activation. The decomposable range display system 100 can display the decomposable range non-destructively without damaging the object to be decomposed 50 (e.g., removing a core sample). The decomposable range display system 100 can obtain the radioactivity concentration in the depth direction of the object to be decomposed 50 non-destructively. The decomposable range display system 100 includes a measuring unit 20, a processing unit 21, and a display unit 22.

[0051] The measuring unit 20 uses a radiation measuring instrument 23 to measure the radiation dose and radiation energy at predetermined sampling locations on the object 50 to be decomposed. The radiation measuring instrument 23 sends the measurement information to the computing unit 21. For example, a radiation survey meter can be used as such a radiation measuring instrument 23. The radiation measuring instrument 23 is capable of measuring the nuclides (energy) of radiation. For example, the radiation measuring instrument 23 can measure the nuclides of radiation. 54 Mn, 60Co, etc. Furthermore, the radiation measuring instrument 23 can measure the number of nuclides. The radiation measuring instrument 23 performs the measurement by contacting its end face 23a with the surface 50a of the object to be decomposed 50. Therefore, the radiation measuring instrument 23 can measure the radiation dose and radiation energy of the surface 50a of the object to be decomposed 50. A scintillation counter is used as the radiation measuring instrument 23. Furthermore, a semiconductor detector capable of performing gamma-ray energy spectrum measurements can also be used as the radiation measuring instrument 23.

[0052] The nature of the radiation irradiating the target object 50 is determined by the positional relationship between the target device 10 (the internal target) which serves as the radiation source and the self-shielding body 6, as well as the structures existing between them. In the target object 50, the sampling position measured by the measuring unit 20 is related to the distribution of radioactive concentration. This is because the shape of the target object 50 and the position of objects disposed around it during its use (e.g., a target irradiating accelerated particles) affect the neutron energy distribution. In this embodiment, the target device 10 (the target) serving as the radiation source is located on both sides of the accelerator 2. Target shielding bodies 7 and 8 are provided around the target device 10, and the distances from the target device 10 to each of the walls 11, 12, 13, 14, and 15 are different. Therefore, the sampling position is set at each of the walls 11, 12, 13, 14, and 15.

[0053] exist Figure 3 An example of a sampling position is shown. For example, sampling positions SP1 to SP8 can be used as sampling positions. These sampling positions SP1 to SP8 are set according to their positional relationship with the two target devices 10 on both sides, which serve as radiation sources. In addition, sampling positions SP6 to SP8 are set towards the inward side of the paper. Figure 3 The middle section is designed for the inner sidewall of the paper. Additionally, in... Figure 3 Sampling positions are also provided on the sidewalls of the paper surface. For example, sampling positions can be set at locations opposite sampling positions SP6 and SP7. Figure 3 In the diagram, sampling positions SP1 to SP8 are shown as the state of the self-shielding body 6 as observed from the target device 10 (which is a radiation source) (or the accelerator 2, which is highly associated with the target device 10). Therefore, the part of the measurement unit 20 that is measured is the part corresponding to surface 6a when the self-shielding body 6 is observed from sampling position SP1.

[0054] like Figure 1As shown, the display unit 22 is a device for displaying various information to the operator. The display unit 22 can be, for example, a monitor. The display unit 22 can display the decomposable range to the operator after it has been determined. Alternatively, when the calculation unit 21 does not perform the determination process described later, the estimation result of the estimation unit 26 can be displayed on the display unit 22, allowing the operator to determine the decomposable range after viewing the display result. In addition to the display unit 22, a sound output unit such as a speaker can also be provided.

[0055] The content displayed by display unit 22 is not particularly limited. As the decomposable range, it can directly display the radioactivity concentration, or it can display the recommended decomposition range (without directly displaying the radioactivity concentration). Furthermore, the method by which display unit 22 displays the decomposable range is not particularly limited; it can be as follows: Figure 21 The display content EA can display graphics as shown, or it can display a combination of numerical and text information as shown in the display content EB.

[0056] The arithmetic unit 21 is a device that performs various calculations in the decomposable range display system 100. The arithmetic unit 21 may be composed of a computer system or the like. The arithmetic unit 21 includes an estimation unit 26, a decomposable range determination unit 27, a distribution information acquisition unit 28, and a storage unit 29.

[0057] The estimation unit 26 estimates the radioactivity concentration distribution in the depth direction corresponding to the sampling position based on the measurement information obtained by the measurement unit 20, the pre-stored surface radiation dose information corresponding to the sampling position, and the distribution information related to the radioactivity distribution in the depth direction. The depth direction refers to the thickness direction of each wall portion 11, 12, 13, 14, and 15 with the inner surface 6a of the self-shielding body 6 as a reference. For example, at sampling position SP1 (refer to…) Figure 3 The depth direction is defined by taking the inner surface 6a of the sidewall portion 11 as a reference and extending horizontally toward the outer surface 6b. The detailed estimation method performed by the estimation unit 26 will be described later.

[0058] The decomposable range determination unit 27 determines the decomposable range based on the estimation results of the estimation unit 26. Based on the estimation results of the radioactivity concentration distribution from the surface 6a of the self-shielding body 6 to the depth direction, the decomposable range determination unit 27 determines the extent to which activation has proceeded from the surface 6a and determines the range to be decomposed.

[0059] The distribution information acquisition unit 28 acquires distribution information related to the radioactivity distribution in the depth direction corresponding to the sampling location. Before the processing by the estimation unit 26 and the resolvable range determination unit 27, the distribution information acquisition unit 28 acquires the distribution information and stores it in the storage unit 29. Detailed processing procedures of the distribution information acquisition unit 28 will be described later. Alternatively, the distribution information acquisition unit 28 can be provided as a separate device from the computing device 21. In this case, after acquiring the distribution information, the distribution information acquisition unit 28 sends the distribution information to the storage unit 29 of the computing device 21.

[0060] Next, refer to Figure 4 The decomposition method, including the decomposable range display method involved in this embodiment, will be described. Figure 4 This is a process diagram illustrating the decomposition method. For example... Figure 4 As shown, in the decomposition method, firstly, distribution information is acquired (step S10), then the decomposable range display method is executed (step S20), and finally, the object 50 is decomposed based on the displayed decomposable range (step S30). Furthermore, the distribution information acquisition method (step S10) is performed in advance at different work sites before the decomposable range display method (step S20) and the decomposition method (step S30). The distribution information obtained through the distribution information acquisition method is stored in the storage unit 29.

[0061] Figure 5 and Figure 6 This is a process diagram showing the detailed processing content of the method for acquiring distribution information (step S10). The method for acquiring distribution information includes a calculation step S200, a measurement step S300, and a distribution information acquisition step S400. The calculation step S200 is as follows: setting a virtual model (model) for virtual simulation of the object to be decomposed 50, and calculating the radioactivity concentration at each position in the depth direction from the surface in the virtual model. The measurement step S300 is as follows: preparing a physical object to be decomposed 50, acquiring a core sample extending from the sampling position in the depth direction from the physical object, and simultaneously measuring the radioactivity concentration of the core sample. The distribution information acquisition step S400 is as follows: acquiring distribution information related to the radioactivity concentration distribution in the depth direction corresponding to the sampling position based on the radioactivity concentration obtained in the calculation step S200 and the radioactivity concentration obtained in the measurement step S300. The calculation step S200 and the distribution information acquisition step S400 are executed by the distribution information acquisition unit 28.

[0062] Reference Figure 5 and Figures 7-12 The calculation process S200 will be described in detail. For example... Figure 5As shown, firstly, the virtual model 70 is prepared (step S40). In step S40, the virtual model 70 simulating the self-shielding body 6 is prepared, and various radiation source systems are fabricated. For example... Figure 7 As shown, the virtual model 70 cuts the surface 6a of the self-shielding body 6 into a cylindrical shape with a predetermined diameter and thickness. The virtual model 70 includes a steel plate 51 and concrete 52. The steel plate 51 on the surface of the virtual model 70 is measured using a radiation meter 23. A steel plate of predetermined thickness is used as the steel plate 51. The number of concrete layers 52 varies from 2 to 5 depending on the model. Four types of virtual models 70 are prepared, namely "MA", "MB", "MC", and "MD", with arbitrary values ​​for diameter and thickness. Furthermore, the values ​​decrease in the order of "MA", "MB", "MC", and "MD". The number of concrete layers and density of the four types of virtual models 70 can be shown, for example, in... Figure 8 The table shown illustrates this. Steel plate 51 is designated as layer "L0," and concrete layers 52, numbered "L1" to "L5," are sequentially arranged from surface 6a. The radioactivity ratio F / C between steel plate 51 and concrete 52 was determined using three modes: X, Y, and Z. Furthermore, in... Figure 8 In the various columns of the table, you can insert values ​​corresponding to the simulation settings and calculated values; therefore, specific numerical values ​​are omitted here. Figure 8 In the text, you can insert any number within the asterisk (*). For subsequent... Figure 9 The tables shown thereafter are the same. Figure 9 In the future, you can insert any value in "***".

[0063] Next, the detection efficiency for gamma rays of various energies was calculated: η(step S50, Figure 5 Regarding the relative intensity of radioactivity, concrete 52 used an attenuation rate e derived from analysis of another core sample. -0.0125d The obtained values. The results of the detection efficiency calculation can be summarized, for example, as follows: Figure 9 The table shown.

[0064] Next, the overall radioactivity of the system is calculated based on the radioactivity ratio of each layer (step S60). Figure 5 ).exist Figure 8 The overall system value can be inserted into the detection efficiency calculation. The following explains the method of decomposing the above values ​​by layer. Each layer L0 to L5 is assigned to insert... Figure 8 Inherent relative radioactivity: R L Because of R L It is processed based on the concentration per unit weight, therefore, as shown in equation (1), by multiplying by the weight of each layer: w L This gives the proportion of radioactivity in the whole: Rw LTherefore, the overall radioactivity of the system can be expressed as Equation (2). Additionally, the overall weight of the system is calculated (step S70, ...). Figure 5 The weights of the steel plates 51 and concrete 52 systems of various diameters can be summarized as follows: Figure 10 The table shown. Rw L and Rw total The calculation results can be summarized in Figure 11 The table shown.

[0065] [Formula 1]

[0066] Finally, the radioactivity concentration per cps in each layer is calculated (step S80). Figure 5 The radioactive concentration per cps is calculated using equation (3) above. The calculation results for γ-rays at αkeV are then used in... Figure 12 A is shown in the middle. L An example of a graph showing the calculation results. Based on the results of step S80, the saturation region of the radiation source is confirmed (step S90, ...). Figure 5 The error range of the results for each radiation source system is preferably within 10%. If the radiation source system is saturated for the γ-rays reaching the radiation measuring instrument 23, then A L The value should not change.

[0067] Next, refer to Figure 6 and Figures 13-19 The measurement process S300 and the distribution information process S400 are described below. First, a physical model is prepared (step S100). Figure 6 For example, when the self-shielding body 6 of the decomposed object 50 is "HM-12S", the physical model 60 in step S100 (refer to...) Figure 3 The self-shielding body 6 of "HM-12S" was also used. Next, core samples were obtained from the physical model, and the radioactivity concentration in each core sample was measured simultaneously (step S110). Figure 6 Core samples can be obtained from... Figure 3 Sampling locations SP1 to SP8 are shown. At the corresponding sampling locations, a core sample CS is taken from the inner surface 6a to the outer surface 6b of the self-shielding body 6. The radioactivity concentration at each location along the depth direction is measured using a measuring instrument.

[0068] Next, for the locations corresponding to the sampling positions of the core samples obtained from the physical model, the radioactivity concentration in the depth direction in the virtual model is calculated (step S120). Figure 6 Here, sampling positions SP1 to SP8 in the virtual model are used to... Figure 5The same method as the measurement method described herein is used for analysis. The analysis results (cps, statistical error) from sampling locations SP1 to SP8, along with the radioactivity calculation conditions (detection efficiency derived from the system), can be used. 54 Mn and 60 The radioactivity ratio (F / C) of steel plate 51 and concrete 52 of Co is summarized in Figures 13-15 The table shown. Additionally, A is obtained through the above formula (3). L This represents the radioactivity concentration per cps in each layer. By multiplying this value by the experimentally obtained cps values ​​of the αkeV, βkeV, and γkeV peaks, and correcting for half-life and branching ratio, the values ​​for each layer can be derived. 54 Mn and 60 The radioactivity concentration of Co.

[0069] The distribution information acquisition unit 28 acquires distribution information related to the radioactivity distribution in the depth direction corresponding to each sampling location SP1 to SP8 based on the calculation results obtained in step S120 and the measurement information obtained in step S110 (step S400). Figure 6 For example, the radioactive depth distribution obtained in step S120 and the depth distribution calculated in step S110 can be obtained as follows: Figures 16-19 Compare those charts. Also, as... Figure 16 As shown in the chart on the left, chart G1 with larger values ​​indicates... 60 The estimated value of Co, with smaller values ​​represented by graph G2. 54 The estimated value of Mn. Additionally, graphs of the estimated values ​​calculated using the virtual model can also be plotted for other F / C models, but only graphs close to the measurements from the physical model are shown here. For others... Figures 16-19 The charts are the same. Regarding 60 Co, after deriving the radioactive concentrations for βkeV and γkeV using equation (3), the weighted average value was calculated. Figure 14 , Figure 15 It is also recorded in the middle. 54 Mn and 60 (Estimated radioactivity value of Co). For example... Figures 16-19 As shown, the estimated values ​​obtained using the virtual model generally reproduced well the measurements from the physical model. In particular, good consistency was achieved at sampling points with higher radioactivity. In Cores 4 and 5, the construction showed a dose buildup effect, with a depth distribution different from other sampling locations, but the estimated values ​​reproduced the core sample analysis values ​​well. In Cores 3, 5, and 7, the estimated values ​​based on the virtual model were lower than the core sample analysis values, but this is believed to be due to a gap between the self-shielding surface and the detector caused by upward measurements, which prevented reproduction of the measured values. Figure 1This is due to the calculation system. That is, by correcting in the direction of decreasing detection efficiency and increasing the estimated value, the difference from the core sample analysis value can be reduced. In "Core 1" and "Core 8", the estimated value is only... 60 The Co content exceeded the core sample analysis value. This is attributed to the presence of the target nearby during measurement and the activation caused by the target or its surroundings. 60 The effect of Co.

[0070] The above information acquisition unit 28 is able to... Figures 16-19 The charts G1 and G2 (or the revised charts) shown are set as follows: 60 Co、 54 Distribution information at each sampling location SP1 to SP8 in Mn. The distribution information acquisition unit 28 stores the acquired distribution information at each sampling location SP1 to SP8 in association with the surface dose values ​​at each sampling location SP1 to SP8 measured by the radiation measuring instrument 23 in the storage unit 29. In addition, Figures 17-19 The distribution information under partial conditions is shown. The distribution information is obtained and stored in the storage unit by performing the measurement process S300 and the calculation process S200 under more conditions.

[0071] Reference Figure 20 The method for displaying the decomposable range is described in detail below. First, the measuring unit 20 uses the radiation measuring instrument 23 to measure the radiation dose and radiation energy at the sampling position of the self-shielding body 6 of the object to be decomposed 50 (step S140). The radiation dose is information about the magnitude of the radioactive concentration. The radiation energy is information about the radioactive nuclide. The sampling position can be sampling positions SP1 to SP8, but if the storage unit 29 also has data from other sampling positions, measurements can also be performed at other sampling positions.

[0072] The estimation unit 26 estimates the radioactivity concentration distribution in the depth direction corresponding to the sampling location based on the measurement information in step S140, the pre-stored surface radiation dose information corresponding to the sampling location, and the distribution information related to the radioactivity distribution in the depth direction (step S150). The estimation unit 26 obtains the measurement information of the radiation dose and radiation energy of the surface 6a at the sampling location from the measurement unit 20. Furthermore, the estimation unit 26 obtains the distribution information corresponding to the sampling location by comparing the information stored in the storage unit 29 with the sampling location measured by the measurement unit 20. The estimation unit 26 estimates (calculates) the radioactivity concentration distribution in the depth direction at the sampling location using the measurement information from the measurement unit 20 and the distribution information and dose information stored in the storage unit 29. The calculation method of the estimation unit 26 is not particularly limited; for example, "A=Ce" can be used. -0.0125t The equation states that "A: radioactivity concentration," "C: a coefficient determined by surface radiation dose information," and "t: depth from the surface (excluding the thickness of the iron plate)."

[0073] The decomposable range determination unit 27 determines the decomposable range based on the estimation result in step S150 (step S160). The decomposable range determination unit 27 determines the radioactivity concentration in the depth direction of sampling positions SP1 to SP8 and the depth to which activation has proceeded at each sampling position SP1 to SP8. Furthermore, the decomposable range determination unit 27 determines the range (depth) at sampling positions SP1 to SP8 that should be decomposed. For example, the decomposable range determination unit 27 can determine a range larger than the value used as a reference radioactivity concentration as the decomposable range. For locations other than sampling positions SP1 to SP8, the decomposable range determination unit 27 can set the range based on the decomposable range at those sampling positions SP1 to SP8. The display unit 22 displays the decomposable range determined in step S160 (step S180).

[0074] exist Figure 20 After demonstrating the decomposable range, the decomposition operation is carried out. As a decomposition method, for example, chipping can be used to break the wall from the side of surface 6a. However, the decomposition method is not limited to chipping; methods such as cutting can also be used. In the self-shielding enclosure 6, the decomposed portion is disposed of as radioactive waste. Parts presumed to be unactivated are disposed of as general waste. Furthermore, in the case of the self-shielding enclosure 6, the polyethylene and lead shielding components can be removed before measurement. Polyethylene with fewer impurities will have less activation. For lead, after measuring the radiation dose, the portion that should be disposed of as radioactive waste can be placed in a metal container for disposal.

[0075] Next, the effects of the decomposable range method, decomposition method, and decomposable range display system 100 involved in this embodiment will be explained.

[0076] This method for displaying the decomposable range uses measurement information of radiation dose and radiation energy at a predetermined sampling location of the object to be decomposed 50, along with distribution information related to the radioactivity distribution in the depth direction corresponding to the sampling location, to display the decomposable range corresponding to the sampling location. Thus, by using the measurement and distribution information, the decomposable range corresponding to the sampling location can be displayed. This allows for easy determination of the decomposable range.

[0077] The radiation dose and radiation energy at the sampling location can be measured using the radiation measuring instrument 23. Thus, by using the radiation measuring instrument 23, simple measurements can be achieved without destructive operations such as core drilling.

[0078] The object to be decomposed 50 may include a radiation source that generates radiation and a shield that covers the radiation source using a shielding component. Since the shield covers the radiation source, the decomposable range can be easily shown through this disclosure even if activation proceeds to the depth direction.

[0079] The radiation source is a target device 10 irradiated by a particle beam from accelerator 2, and the shield can be a self-shielding body 6 covering the target device. Since the activation state of the self-shielding body 6 varies depending on its location, measurements need to be taken at multiple sampling locations. Therefore, by employing non-destructive measurements, the effect of easily displaying the resolvable range can be more significantly achieved.

[0080] The object to be decomposed 50 may include, for example, steel plate 17 and concrete 18.

[0081] The decomposable range display method may further include: a calculation step, in which a virtual simulation model of the object to be decomposed 50 is set up, and the radioactivity concentration at various locations in the depth direction from the surface in the model is calculated; a measurement step, in which a physical object of the object to be decomposed 50 is prepared, a core sample extending from the sampling position into the depth direction is obtained from the physical object, and the radioactivity concentration of the core sample is measured simultaneously; and a distribution information acquisition step, in which distribution information related to the radioactivity concentration distribution in the depth direction corresponding to the sampling position is obtained based on the radioactivity concentration obtained in the calculation step and the radioactivity concentration obtained in the measurement step. In this case, by combining the virtual model and using the physical object, the radioactivity concentration in the depth direction can be accurately and easily determined.

[0082] The decomposition method described in this embodiment can decompose objects within the decomposable range determined by the aforementioned decomposable range display method. By performing the decomposition operation according to the range determined by the aforementioned decomposable range display method, the decomposition operation can be easily performed.

[0083] The decomposable range display system 100 according to this embodiment is used to display the decomposable range of a decomposable object 50 having a predetermined structure. The decomposable range display system includes a display unit 22, which displays the decomposable range corresponding to a sampling position based on the measurement information of radiation dose and radiation energy at a predetermined sampling position of the decomposable object 50 and the distribution information related to the radioactivity distribution in the depth direction corresponding to the sampling position.

[0084] According to the decomposable range display system 100, the same effect as the decomposable range display method described above can be achieved.

[0085] The above describes one embodiment of the present disclosure, but the present disclosure is not limited to the above embodiment, and modifications can be made without changing the spirit of the technical solutions.

[0086] For example, Figures 4-6 and Figure 20The process shown is only one example. Without departing from the spirit of this disclosure, the content and order may be appropriately changed, and some processes may be omitted.

[0087] Symbol Explanation 2-Accelerator, 6-Self-shielding body, 10-Target device, 20-Measuring unit, 22-Display unit, 23-Radiation measuring instrument, 26-Estimation unit, 27-Decomposable range determination unit, 50-Decomposable object, 100-Decomposable range display system.

Claims

1. A method for displaying decomposable ranges, used to display the decomposable ranges of a decomposable object having a predetermined structure, wherein, The method for displaying the decomposable range displays the decomposable range corresponding to the sampling location based on the measurement information of radiation dose and radiation energy at a predetermined sampling location of the object to be decomposed, as well as the distribution information related to the radioactivity distribution in the depth direction corresponding to the sampling location.

2. The method for displaying a decomposable range according to claim 1, wherein, At the sampling location, a radiation meter is used to measure the radiation dose and radiation energy.

3. The method for displaying decomposable ranges according to claim 1, wherein, The object to be decomposed has the following characteristics: The radiation source that produces radiation, and A shielding body is used to cover the radiation source using shielding components.

4. The method for displaying a decomposable range according to claim 3, wherein, The radiation source is a target device irradiated by a particle beam from an accelerator. The shield is a self-shielding body that covers the target device.

5. The method for displaying a decomposable range according to claim 3, wherein, The objects to be decomposed include steel plates and concrete.

6. The method for displaying a decomposable range according to claim 1, further comprising: The calculation process involves setting up a virtual simulation model of the object to be decomposed, and calculating the radioactivity concentration at various locations in the model along the depth direction from the surface. The measurement process involves preparing the physical object to be decomposed, obtaining a core sample from the physical object extending from the sampling position to the depth direction, and simultaneously measuring the radioactivity concentration of the core sample. and The distribution information acquisition step obtains distribution information related to the radioactivity concentration distribution in the depth direction corresponding to the sampling location, based on the radioactivity concentration obtained in the calculation step and the radioactivity concentration obtained in the measurement step.

7. A decomposition method, wherein the object to be decomposed is decomposed based on the decomposable range displayed by the decomposable range display method according to any one of claims 1 to 5.

8. A decomposable range display system for displaying the decomposable range of a decomposable object having a predetermined structure, wherein, The decomposable range display system includes a display unit that displays the decomposable range corresponding to the sampling location based on the measurement information of radiation dose and radiation energy at a predetermined sampling location of the object to be decomposed, and the distribution information related to the radioactivity distribution in the depth direction corresponding to the sampling location.

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