Structure for manufacturing radioactive source by recycling retired cobalt source

Abstract

The invention relates to a radioactive source structure manufactured by reusing a retired cobalt source, and belongs to the technical field of radioactive sources. The structure for manufacturing the radioactive source by reusing the retired cobalt source comprises an outer wrapping shell and a plurality of inner wrapping shells, wherein the inner wrapping shells are arranged on the inner side of the outer wrapping shell; the multiple inner jackets are distributed in a circumferential array mode in the circumferential direction of the outer jacket to form M layers of circular ring structures which are sequentially arranged from inside to outside, and M is larger than or equal to 2; the innermost circular ring layer in the multiple inner jackets comprises at least one inner jacket, and the number of the inner jackets of the other circular ring layers is gradually increased layer by layer outwards in the radial direction; the circular ring layer and the outer wrapping shell are coaxial; the inner cladding comprises an inner shell body and a pair of first end plugs, the pair of first end plugs are used for blocking openings in the two ends of the inner shell body, and the inner shell body and the pair of first end plugs define a space used for containing the retired cobalt source; the first end plug of any inner cladding is attached to the first end plug of the adjacent inner cladding. According to the radioactive source structure manufactured by reusing the retired cobalt source provided by the embodiment of the invention, the radiation intensity of each part of the radioactive source can be uniform.

Description

Technical Field

[0001] This application relates to the technical field of radiation sources, and in particular, to a structure for recycling retired cobalt sources to manufacture radiation sources. Background Art

[0002] Cobalt-60 ( 60 Co) is a commonly used external irradiation γ radiation source, which is widely used in the fields of radiation medicine, modification processing of polymer materials, agricultural irradiation mutagenesis breeding, sterilization and disinfection of traditional Chinese medicine and medical devices, food irradiation preservation, etc.

[0003] When the cobalt source reaches the end of its service life or is replaced, it will be retired. The retired cobalt source still has strong radioactivity. It takes a long time and a large storage space to wait for it to lose its activity. This disposal method not only increases the storage pressure of the disposal site and increases the disposal cost for users, but also is not conducive to resource conservation and environmental protection. Recycling and reusing retired cobalt sources can extend the service life of cobalt sources, reduce the disposal volume of final spent radiation sources, and relieve the storage pressure of the disposal site, thereby achieving the purpose of saving resources and protecting the environment.

[0004] The recycled retired cobalt sources can be filled into the cladding and used as new radiation sources. The following problems are found in the process of applying medical retired cobalt sources to industrial or agricultural fields: when the number of cobalt sources is large, they will be arranged randomly in the cladding. The radiation energy of randomly arranged radiation sources may interfere with each other, making it difficult to predict the penetration depth and making the radiation dose of each part of the radiation source to the target uncontrollable; in addition, the random arrangement of cobalt sources may lead to the overlap or dispersion of the energy deposition areas, forming local high-dose (hot spots) or low-dose (cold areas), which will affect the working environment. Summary of the Invention

[0005] The purpose of this application is to provide a structure for recycling retired cobalt sources to manufacture radiation sources in view of the above problems, which can make the radiation intensity of each part of the radiation source uniform and improve the above problems.

[0006] This application is achieved by the following technical solutions:

[0007] The present application provides a structure for recycling a retired cobalt source to manufacture a radioactive source. The structure comprises an outer shell and a plurality of inner shells, wherein the inner shell is arranged on the inner side of the outer shell; the plurality of inner shells are distributed in a circular array along the circumference of the outer shell to form an M-layer circular ring structure arranged in sequence from the inside to the outside, and M≥2 is satisfied; the innermost circular ring layer among the plurality of inner shells comprises at least one inner shell, and the number of inner shells in the remaining circular ring layers increases layer by layer as the radial direction goes outward; the circular ring layer is coaxial with the outer shell; the inner shell comprises an inner shell and a pair of first end plugs, the pair of first end plugs are used to seal the openings at both ends of the inner shell, and the inner shell and the pair of first end plugs enclose a space for placing the retired cobalt source; the first end plug of any inner shell among the plurality of inner shells fits with the first end plug of the adjacent inner shell.

[0008] In the technical solution of the embodiment of the present application, all the inner shells located on the inner side of the outer shell constitute a shell group as a whole. The shell group is composed of M layers of annular layers. The M layers of annular layers are sequentially arranged from the inside to the outside. Under the premise that the radioactivity intensity of each inner shell is similar, multiple inner shells are distributed in a circular array along the circumference of the outer shell to form an M-layer annular structure sequentially arranged from the inside to the outside. The radioactivity intensity of multiple inner shells in each annular layer to various parts of the outer shell is similar, so that the radioactivity intensity of various parts of the outer shell to the outside is uniform, and the adjacent annular layers are fitted together, so that the multiple inner shells contained in the annular layer can be contained in the adjacent annular layer. The inner shell is used to limit the position of the inner shell; the inner shell and a pair of first end plugs enclose a space for placing the retired cobalt source. Since the cobalt source itself has strong radioactivity, the process and time required for operating it should be minimized during recovery and treatment. The structure consists of an inner shell and a pair of first end plugs, and the retired cobalt source can be disassembled and assembled from any end of the inner shell, eliminating the process required to calibrate the front and back of the inner shell; the first end plug of any inner shell among the multiple inner shells contacts the first end plug of the adjacent inner shell, so that the multiple inner shells in the outer shell are limited to each other through the first end plugs that fit each other, thereby keeping the overall structure of the multiple inner shells intact.

[0009] In some embodiments, there is a gap between the inner shells of two adjacent inner shells in the outermost N annular layers, satisfying M>N≥2.

[0010] In the technical solution of the embodiment of the present application, when the γ rays emitted by the decommissioned cobalt source in the inner cladding irradiate the adjacent inner cladding, a series of energy transfer and energy deposition processes may be triggered. Therefore, in order to reduce the electrical effect and thermal effect caused by energy deposition, a gap can be left in the adjacent inner cladding to reduce the rays directly absorbed by the adjacent inner cladding. However, after setting the gap, the number of rays emitted by the outer cladding at the gap will be reduced, that is, the radioactive intensity of the outer cladding at the gap will be reduced. In order to avoid the problem of relatively low local radioactive intensity of the outer cladding caused by setting the gap, the gaps between the inner shells of two adjacent inner claddings in two adjacent circular ring layers in the outermost N circular ring layers are staggered from each other, so that the shielding between the rays of the inner cladding of the adjacent inner circular ring layer at the gap and the outer cladding can be reduced. Thus, the rays emitted by the inner cladding on the inner side are used to fill the ray gap at the gap between the adjacent outer inner claddings, so that the radioactive intensity received by each part of the outer cladding from the cladding group is similar.

[0011] In some embodiments, the inner shells of any two adjacent inner claddings in the outermost J circular ring layers are in contact with each other, satisfying M > J ≥ 1.

[0012] In the technical solution of the embodiment of the present application, the inner shells of any two adjacent inner claddings in the outermost J circular ring layers are in contact with each other, so that the inner claddings in the outermost J circular ring layers can stably shield the rays of the inner claddings located on the inner side. On the one hand, the radioactive intensity of the outermost J circular ring layers on the outer cladding ring is made similar. On the other hand, the shielding effect of the outermost J circular ring layers on the inner circular ring layers is made similar, reducing the probability that the radioactive intensity of the inner claddings on the inner side on the outer cladding fluctuates strongly or weakly due to the possible movement between the inner claddings in the outer circular ring layers and the adjacent inner claddings, resulting in unstable sizes of the gaps between the inner claddings and the adjacent inner claddings, so that the radioactive intensity received by each part of the outer cladding from the cladding group can be kept stable and uniform.

[0013] In some embodiments, the radioactive intensity of the decommissioned cobalt source in the inner cladding in the innermost K circular ring layers is higher than the radioactive intensity of the decommissioned cobalt source in the inner cladding in the outermost circular ring layers, satisfying M > K ≥ 1.

[0014] In the technical solution of the embodiment of the present application, the radioactive intensity of the decommissioned cobalt source in the inner cladding within the innermost K-layer circular ring layer is higher than that of the decommissioned cobalt source in the inner cladding within the outermost circular ring layer. The gamma rays of the decommissioned cobalt source in the inner cladding on the inner side have strong penetration power, forming a superimposed radiation field in the central region of the outer cladding and significantly increasing the central dose. The radioactive intensity of the decommissioned cobalt source in the inner cladding at the edge is relatively low. By the dose-dominant effect of the inner source provided by the present application, the dependence on the intensity of the outer source can be reduced, and the total loading amount (i.e., the number of decommissioned cobalt sources) of the radioactive sources within the outer cladding can be decreased. On the premise of ensuring the overall radioactive intensity, the overall size and weight can be reduced.

[0015] In some embodiments, an absorption layer is provided on the outer surface of the inner cladding within the innermost K-layer circular ring layer.

[0016] In the technical solution of the embodiment of the present application, the radioactive intensity of the decommissioned cobalt source in the inner cladding within the innermost K-layer circular ring layer is higher than that of the decommissioned cobalt source in the inner cladding within the outermost circular ring layer. And an absorption layer is provided on the outer side of the inner cladding with high activity. The absorption layer (such as lead, tungsten alloy or boron-containing composite material) forms a dose gradient attenuation from the inside to the outside by partially absorbing gamma rays; the direct irradiation of the inner cladding with high activity on the inner side will cause over-dose in the central region, and the absorption layer can make the radiation field more uniform through selective shielding.

[0017] In some embodiments, the first end plug includes a first section and a second section. The second section is closer to the decommissioned cobalt source than the first section, and the second section extends into the inner side of the inner shell and fits with the inner wall of the inner shell.

[0018] In the technical solution of the embodiment of the present application, the first end plug includes the first section and the second section, which is convenient for components such as a robotic arm to hold the first section to insert the second section into the inner side of the inner shell, and also enhances the mutual positioning effect between the two through the fit of the second section with the inner wall of the inner shell.

[0019] In some embodiments, in the radial direction of the inner shell, the outer wall surface of the first section exceeds the outer peripheral surface of the inner shell.

[0020] In the technical solution of the embodiment of the present application, in the radial direction of the inner shell, the outer wall surface of the first section exceeds the outer peripheral surface of the inner shell, enabling the inner cladding to contact the adjacent inner shell through the first section, so that there is a gap between the inner shell containing the decommissioned cobalt source and the inner shells of the adjacent inner claddings. This can not only improve the overall structural stability of the cladding group but also prevent excessive energy deposition between the inner shells in direct contact from causing safety accidents such as overheating.

[0021] In some embodiments, the positive projection of the first section in the axial direction of the inner housing is a polygon. The first sections of adjacent inner claddings in any ring layer are attached to each other through flat surfaces, and the first sections in any ring layer are attached to the first sections in adjacent ring layers through flat surfaces.

[0022] In the technical solution of the embodiment of the present application, when the positive projection of the first section in the axial direction of the inner housing is a polygon, the first section of any inner cladding can be attached to the first section of the adjacent inner cladding in the same layer or the first section of the inner cladding in the adjacent layer through a flat surface, thereby restricting the movement and even rotation of the inner cladding and making the structure of the cladding group easier to maintain stability.

[0023] In some embodiments, the thickness dimension of the wall of the inner housing is smaller than the dimension of the first end plug in the axial direction of the inner housing.

[0024] In the technical solution of the embodiment of the present application, the thickness dimension of the wall of the inner housing is smaller than the dimension of the first end plug in the axial direction of the inner housing, so that the rays emitted by the decommissioned cobalt source in the inner housing along the axial direction towards the first end plug can be effectively blocked, so that the rays emitted by the decommissioned cobalt source are mainly concentrated in the radial direction of the inner housing, facilitating the user to control the radiation direction of the radiation source.

[0025] In some embodiments, the outer cladding includes an outer housing and a pair of second end plugs. The pair of second end plugs are used to block the openings at both ends of the outer housing, and the outer housing and the pair of second end plugs enclose a space for placing the inner cladding; in the axial direction of the outer housing, the dimension of the inner cladding is H1, and the interval dimension between the pair of second end plugs is H2, satisfying H2≥H1.

[0026] In the technical solution of the embodiment of the present application, the outer housing and the second end plug are designed separately, reducing the processing difficulty of the outer housing and the second end plug. In the axial direction of the outer housing, the dimension H1 of the inner cladding is less than or equal to the interval dimension H2 between the pair of second end plugs, so that there is enough space inside the outer housing to accommodate multiple inner claddings, avoiding the second end plug applying force to the inner cladding, and avoiding the situation where the inner cladding expands due to heat under the action of rays and is squeezed by the second end plug, resulting in damage to both.

[0027] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts.

[0029] Figure 1 Explosion view of the structure of a radioactive source manufactured by recycling retired cobalt sources provided in some embodiments of the present application;

[0030] Figure 2 Explosion view of the structure of a radioactive source manufactured by recycling retired cobalt sources provided in other embodiments of the present application;

[0031] Figure 3 Explosion view of the structure of a radioactive source manufactured by recycling retired cobalt sources provided in still other embodiments of the present application;

[0032] Figure 4 Partial explosion view of the structure of a radioactive source manufactured by recycling retired cobalt sources when M>2 provided in some embodiments of the present application;

[0033] Figure 5 Bottom view of the structure of a radioactive source manufactured by recycling retired cobalt sources provided in some embodiments of the present application;

[0034] Figure 6 For Figure 5 The cross-sectional view at A-A in

[0035] Icon: 1 - Outer cladding; 10 - Outer housing; 11 - Second end plug; 2 - Inner cladding; 20 - Inner housing; 21 - First end plug; 210 - First section; 211 - Second section; 3 - Retired cobalt source. Detailed implementation manners

[0036] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0037] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification and claims of the present application or the above drawings are used to distinguish different objects and are not used to describe a specific order or primary-secondary relationship.

[0038] References to "embodiments" in this application mean that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0039] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "joined", "attached" shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0040] The term "and / or" in this application is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally represents an "or" relationship between the associated objects before and after.

[0041] The "multiple" mentioned in this application means two or more (including two). Similarly, "multiple groups" means two or more groups (including two groups), and "multiple pieces" means two or more pieces (including two pieces).

[0042] According to some embodiments of this application, optionally, as Figures 1 to 6 shown, this application provides a structure for recycling a retired cobalt source 3 to manufacture a radiation source. The structure for recycling a retired cobalt source 3 to manufacture a radiation source includes an outer shell 1 and multiple inner shells 2. The inner shells 2 are arranged inside the outer shell 1; the multiple inner shells 2 are distributed in a circumferential array along the circumference of the outer shell 1 to form M layers of ring structures arranged in sequence from inside to outside, satisfying M≥2; at least one inner shell 2 is included in the innermost ring layer among the multiple inner shells 2, and the number of inner shells 2 in each of the remaining ring layers increases layer by layer along the radial direction outward; the ring layers are coaxial with the outer shell 1; the inner shell 2 includes an inner housing 20 and a pair of first end plugs 21. The pair of first end plugs 21 are used to block the openings at both ends of the inner housing 20, and a space for placing the retired cobalt source 3 is formed by the inner housing 20 and the pair of first end plugs 21; the first end plug 21 of any one of the multiple inner shells 2 is in contact with the first end plug 21 of the adjacent inner shell 2.

[0043] The innermost ring layer can be composed of one inner shell 2, and the remaining ring layers are all arranged around this ring layer.

[0044] The number of inner shells 2 constituting the annular layer increases gradually from the inside to the outside.

[0045] M can be 2, 3, 4, 5, 6, 7, 8, 9, 10 or more.

[0046] The value range of the spacing dimension between the cladding group and the inner wall of the outer cladding 1 is (2,0].

[0047] The outer shell 1 can be cylindrical, so that when the cladding group is located in the center of the outer shell 1, the distance between each part of the wall of the outer shell 1 and the cladding group is close, so that the radioactivity intensity at each part of the outer peripheral surface of the outer shell 1 is uniform.

[0048] All the inner shells 2 located on the inner side of the outer shell 1 form a shell group as a whole. The shell group is composed of M annular layers. The M annular layers are sequentially arranged from the inside to the outside. Under the premise that the radioactivity intensity of each inner shell 2 is similar, multiple inner shells 2 are distributed in a circular array along the circumference of the outer shell 1 to form an M-layer annular structure sequentially arranged from the inside to the outside. The radioactivity intensity of multiple inner shells 2 in each annular layer to various parts of the outer shell 1 is similar, so that the radioactivity intensity of various parts of the outer shell 1 to the outside is uniform, and the adjacent annular layers are fitted together, so that the multiple inner shells 2 contained in the annular layer can limit the inner shells 2 contained in the adjacent annular layers; in the radial direction of the outer shell 1, the spacing distance between the shell group and the inner wall of the outer shell 1 is smaller than the size of the inner shell 2, so that the inner shell 2 in the outermost annular layer can be limited by the adjacent inner shell 2, even along The radial movement of the outer shell 1 cannot deviate from the circumferential array of the annular layer, so that the shell group can maintain its own structure and the radioactivity intensity of the shell group to each part of the outer shell 1 is similar and stable; the shell and a pair of first end plugs 21 enclose a space for placing the retired cobalt source 3. Since the cobalt source itself has strong radioactivity, the process and time required for operating it should be minimized during recovery and treatment. The structure is an inner shell 20 and a pair of first end plugs 21. The retired cobalt source 3 can be disassembled and assembled from any end of the inner shell 20, eliminating the process required to calibrate the front and back of the inner shell 2; the first end plug 21 of any inner shell 2 among the multiple inner shells 2 contacts the first end plug 21 of the adjacent inner shell 2, so that the multiple inner shells 2 in the outer shell 1 are limited to each other through the first end plugs 21 that fit each other, thereby keeping the overall structure of the multiple inner shells 2 intact.

[0049] According to some embodiments of the present application, optionally, Figure 2 and Figure 4 As shown, there is a gap between the inner shells 20 of two adjacent inner claddings 2 in the outermost N annular layers, satisfying M>N≥2.

[0050] When M = 2, there is only one inner cladding 2 in the innermost ring layer. Then, the gaps between any two adjacent inner claddings 2 in the outermost ring layer can be directly opposite to the outer wall of the inner cladding 2 in the innermost layer.

[0051] The γ-rays emitted by the retired cobalt sources 3 in the inner cladding 2 may trigger a series of energy transfer and energy deposition processes when irradiating the adjacent inner cladding 2. Therefore, in order to reduce the electrical and thermal effects caused by energy deposition, gaps can be left in the adjacent inner claddings 2 to reduce the rays directly absorbed by the adjacent inner claddings 2. However, after setting the gaps, the amount of rays emitted to the outer cladding 1 at the gaps will be reduced, that is, the radioactivity intensity of the outer cladding 1 at the gaps will be reduced. In order to avoid the problem of relatively low local radioactivity intensity of the outer cladding 1 caused by setting the gaps, the gaps between the inner shells 20 of the adjacent two inner claddings 2 in the outermost N ring layers are staggered from each other, so that the shielding between the rays of the inner cladding 2 of the adjacent inner ring layer at the gaps and the outer cladding 1 can be reduced. Thus, the rays emitted by the inner cladding 2 on the inner side are used to fill the ray vacancies at the gaps between the adjacent outer claddings 2, so that the radioactivity intensity received by each part of the outer cladding 1 from the cladding group is similar.

[0052] According to some embodiments of the present application, optionally, as Figures 1 to 4 shown, the inner shells 20 of any two adjacent inner claddings 2 in the outermost J ring layers are in mutual contact, satisfying M > J ≥ 1.

[0053] The inner shells 20 of any two adjacent inner claddings 2 in the outermost J ring layer can be in mutual abutment, so that the effect of limiting the positions of the inner claddings 2 in the same ring layer is enhanced, thereby reducing the risk of the overall structure of the multiple inner claddings 2 falling apart.

[0054] The inner shells 20 of any two adjacent inner claddings 2 in the outermost J ring layers are in mutual contact, so that the inner claddings 2 in the outermost J ring layer can stably shield the rays of the inner claddings 2 located on the inner side. On the one hand, the radioactivity intensity of the outer cladding 1 ring in the outermost J ring layer is made similar, and on the other hand, the shielding effect on the inner ring layer in the outermost J ring layer is made similar, reducing the probability that the radioactivity intensity of the inner cladding 2 on the inner side on the outer cladding 1 fluctuates strongly and weakly due to the possible movement between the inner cladding 2 in the outer ring layer and the adjacent inner cladding 2, resulting in unstable gap sizes between the inner cladding 2 and the adjacent inner cladding 2, so that the radioactivity intensity received by each part of the outer cladding 1 from the cladding group can be kept stable and uniform.

[0055] According to some embodiments of the present application, optionally, the radioactivity intensity of the retired cobalt sources 3 in the inner claddings 2 in the innermost K ring layer is higher than the radioactivity intensity of the retired cobalt sources 3 in the inner claddings 2 in the outermost ring layer, satisfying M > K ≥ 1.

[0056] The radioactivity of the outer cladding 1 and the inner cladding 2 mentioned in this application is the radioactivity of the decommissioned cobalt source 3 filled inside the inner cladding 2.

[0057] The radioactivity of a radioactive source will decrease over time, mainly due to radioactive decay. Radioactive decay refers to the process in which an unstable atomic nucleus spontaneously emits rays and transforms into another more stable atomic nucleus. During this process, the number of atomic nuclei that have not decayed gradually decreases, and the activity of the radionuclide gradually decreases, resulting in a decrease in its radioactivity.

[0058] The radioactivity intensity of the decommissioned cobalt source 3 inside the inner cladding 2 in the innermost K-layer circular ring layer is higher than that of the decommissioned cobalt source 3 inside the inner cladding 2 in the outermost circular ring layer. The gamma rays of the decommissioned cobalt source 3 inside the inner cladding 2 on the inner side have strong penetration, forming a superimposed radiation field in the central area of the outer cladding 1 and significantly increasing the central dose. The radioactivity intensity of the decommissioned cobalt source 3 inside the inner cladding 2 on the edge is relatively low. With the dose-dominant effect of the inner source provided by this application, the dependence on the intensity of the outer source can be reduced, and the total loading amount of the radioactive sources (i.e., the number of decommissioned cobalt sources 3) inside the outer cladding 1 can be reduced. On the premise of ensuring the overall radioactivity intensity, the overall size and weight can be reduced.

[0059] According to some embodiments of this application, optionally, an absorption layer is provided on the outer surface of the inner cladding 2 in the innermost K-layer circular ring layer.

[0060] The material of the absorption layer can be, but is not limited to, lead, tungsten alloy, boron-containing composite material, etc.

[0061] The radioactivity intensity of the decommissioned cobalt source 3 inside the inner cladding 2 in the innermost K-layer circular ring layer is higher than that of the decommissioned cobalt source 3 inside the inner cladding 2 in the outermost circular ring layer. An absorption layer is provided on the outer side of the inner cladding 2 with high activity. The absorption layer (such as lead, tungsten alloy or boron-containing composite material) forms a dose gradient attenuation from the inside to the outside by partially absorbing gamma rays; the direct irradiation of the inner cladding 2 with high activity on the inner side will cause over-dose in the central area, and the absorption layer can make the radiation field more uniform through selective shielding.

[0062] The absorption layer provided on the outer surface of the inner cladding 2 in the innermost K-layer circular ring layer can be detachably connected to the inner cladding 2. When the activity of the outermost inner cladding 2 decreases significantly, the overall radioactivity activity of the outer cladding 1 can be increased by removing the absorption layer.

[0063] According to some embodiments of this application, optionally, such as Figures 1 to 4 and Figure 6As shown, the first end plug 21 includes a first section 210 and a second section 211. The second section 211 is closer to the decommissioned cobalt source 3 than the first section 210. The second section 211 extends into the inner side of the inner housing 20 and fits against the inner wall of the inner housing 20.

[0064] In the axial direction of the inner housing 20, the size of the first end plug 21 can be 18.45 mm, and the size of the second section 211 extending into the inner housing 20 can be taken as 7.45 mm.

[0065] The first end plug 21 includes a first section 210 and a second section 211, which facilitates components such as a robotic arm to hold the first section 210 to insert the second section 211 into the inner side of the inner housing 20, and also enhances the mutual positioning effect between the two by the fitting of the second section 211 against the inner wall of the inner housing 20.

[0066] According to some embodiments of the present application, optionally, as Figures 1 to 4 and Figure 6 shown, in the radial direction of the inner housing 20, the outer wall surface of the first section 210 exceeds the outer peripheral surface of the inner housing 20.

[0067] In the radial direction of the inner housing 20, the size of the first section 210 can be 11 mm, and the size of the second section 211 can be 8.4 mm. The outer diameter of the inner housing 20 can be 9.68 mm.

[0068] Adjacent inner claddings 2 can be limited by the abutment of the outer wall surface of the first section 210 against each other, improving the overall structural stability of the cladding group.

[0069] In the radial direction of the inner housing 20, the outer wall surface of the first section 210 exceeds the outer peripheral surface of the inner housing 20, enabling the inner cladding 2 to contact the adjacent inner housing 2 through the first section 210, so that there is a gap between the inner housing 20 containing the decommissioned cobalt source 3 and the inner housing 20 of the adjacent inner cladding 2, which can not only improve the overall structural stability of the cladding group, but also prevent the inner housing 20 from directly contacting and causing excessive energy deposition between them, leading to safety accidents such as overheating.

[0070] In some embodiments, the first section 210 of the outermost inner cladding 2 can be flush with or not exceed the outer peripheral surface of the inner housing 20, so that the outermost inner cladding 2 can block the rays of the inner claddings 2 inside, avoiding the situation of excessive local radioactivity of the cladding group caused by the inner claddings 2 inside.

[0071] According to some embodiments of the present application, optionally, the orthographic projection of the first section 210 in the axial direction of the inner housing 20 is a polygon. The first sections 210 of adjacent inner claddings 2 in any layer of the ring layer are in flat surface contact, and the first sections 210 in any layer of the ring layer are in flat surface contact with the first sections 210 in the adjacent ring layer.

[0072] The polygon can be a hexagon, heptagon, octagon or more.

[0073] When the positive projection of the first section 210 of the inner housing 20 in the axial direction is a polygon, the first section 210 of any inner casing 2 can be attached to the first section 210 of the adjacent inner casing 2 in the same layer or the first section 210 of the inner casing 2 in the adjacent layer through a flat surface, so as to limit the movement and even rotation of the inner casing 2, making the structure of the casing group easier to maintain stability.

[0074] According to some embodiments of the present application, optionally, as Figure 6 shown, the thickness dimension of the wall of the inner housing 20 is smaller than the dimension of the first end plug 21 in the axial direction of the inner housing 20.

[0075] The wall thickness of the inner housing 20 can be 1.28 mm.

[0076] The thickness dimension of the wall of the inner housing 20 is smaller than the dimension of the first end plug 21 in the axial direction of the inner housing 20, so that the rays emitted by the decommissioned cobalt source 3 in the inner housing 20 along the axial direction towards the first end plug 21 can be more effectively blocked, so that the rays emitted by the decommissioned cobalt source 3 are mainly concentrated in the radial direction of the inner housing 20, facilitating the user to control the radiation direction of the radiation source.

[0077] According to some embodiments of the present application, optionally, as Figures 1 to 4 and Figure 6 shown, the outer casing 1 includes an outer housing 10 and a pair of second end plugs 11. The pair of second end plugs 11 are used to seal the openings at both ends of the outer housing 10. The outer housing 10 and the pair of second end plugs 11 enclose a space for placing the inner casing 2; in the axial direction of the outer housing 10, the dimension of the inner casing 2 is H1, and the interval dimension between the pair of second end plugs 11 is H2, satisfying H2≥H1.

[0078] One of the pair of second end plugs 11 facing upward can be provided with a welding hole.

[0079] The second end plug 11 can be fixedly connected to the outer housing 10 by welding.

[0080] A part of the second end plug 11 can extend into the inner side of the outer housing 10 and contact the inner wall of the outer housing 10, and the outer wall surface of the other part of the second end plug 11 can not exceed the outer peripheral surface of the outer housing 10 or be flush with the outer peripheral surface of the outer housing 10.

[0081] The outer housing 10 and the second end plug 11 are designed separately, reducing the processing difficulty of the outer housing 10 and the second end plug 11.

[0082] In the axial direction of the outer housing 10, the dimension H1 of the inner housing 2 is less than or equal to the interval dimension H2 between a pair of second end plugs 11, so that there is enough space inside the outer housing 10 to accommodate a plurality of inner housings 2, avoiding the second end plugs 11 applying force to the inner housings 2, and avoiding the situation where the inner housings 2 expand due to heat under the action of rays and are squeezed by the second end plugs 11, resulting in damage to both.

[0083] Although the present application has been described with reference to the preferred embodiments, various improvements can be made to it and components therein can be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A structure for manufacturing a radiation source by recycling retired cobalt sources, characterized in that, Comprising: An outer shell; A plurality of inner shells, disposed inside the outer shell; Wherein, the plurality of inner shells are distributed in a circumferential array along the circumference of the outer shell, forming M layers of circular ring structures arranged in sequence from the inside to the outside, satisfying M≥2; Wherein, the innermost circular ring layer of the plurality of inner shells contains at least one of the inner shells, and the number of inner shells in each of the remaining circular ring layers increases layer by layer radially outward, and the circular ring layers are coaxial with the outer shell; The inner shell includes an inner housing and a pair of first end plugs, and the pair of first end plugs are used to block the openings at both ends of the inner housing, and the inner housing and the pair of first end plugs enclose a space for placing the decommissioned cobalt source; The first end plugs of any one of the plurality of inner shells are in contact with the first end plugs of the adjacent inner shells.

2. The structure of a recycled cobalt source for manufacturing a radiation source according to claim 1, wherein The inner housings of any two adjacent inner shells in the outermost J-layer circular ring layers are in contact with each other, satisfying M>J≥1.

3. The structure of a recycled cobalt source for manufacturing a radiation source according to claim 2, characterized in that, The radioactive intensity of the decommissioned cobalt source in the inner shell of the innermost K-layer circular ring layer is higher than that of the decommissioned cobalt source in the inner shell of the outermost circular ring layer, satisfying M>K≥1.

4. The structure of a recycled cobalt source for manufacturing a radiation source according to claim 3, characterized in that, An absorption layer is provided on the outer surface of the inner shell of the innermost K-layer circular ring layer.

5. A structure for manufacturing a radiation source by recycling retired cobalt sources according to claim 1, characterized in that, There is a gap between the inner housings of two adjacent inner shells in the outermost N-layer circular ring layers, satisfying M>N≥2.

6. A structure for manufacturing a radiation source by recycling a decommissioned cobalt source according to claim 1, characterized in that, The first end plug includes a first section and a second section, and the second section is closer to the decommissioned cobalt source than the first section, and the second section extends into the inner side of the inner housing and is in contact with the inner wall of the inner housing.

7. A structure for recycling a retired cobalt source to manufacture a radiation source according to claim 6, characterized in that, In the radial direction of the inner housing, the outer wall surface of the first section exceeds the outer peripheral surface of the inner housing.

8. A structure for manufacturing a radiation source by recycling a retired cobalt source according to claim 6, characterized in that, The positive projection of the first section in the axial direction of the inner housing is a polygon, and the first sections of the adjacent inner shells in any one layer of the circular ring layers are in contact through a flat surface, and the first sections in any one layer of the circular ring layers are in contact with the first sections in the adjacent circular ring layers through a flat surface.

9. A structure for recycling a retired cobalt source to manufacture a radiation source according to claim 6, characterized in that, The thickness dimension of the wall of the inner housing is smaller than the dimension of the first end plug in the axial direction of the inner housing.

10. The structure of a recycled cobalt source for manufacturing a radiation source according to claim 1, characterized in that, The outer shell includes an outer housing and a pair of second end plugs, and the pair of second end plugs are used to block the openings at both ends of the outer housing, and the outer housing and the pair of second end plugs enclose a space for placing the inner shells; In the axial direction of the outer housing, the dimension of the inner shell is H1, and the interval dimension between the pair of second end plugs is H2, satisfying H2≥H1.

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