Pressurized water reactor irradiation cobalt target structure and use method thereof

Abstract

The invention discloses a pressurized water reactor irradiation cobalt target structure and a using method thereof.The pressurized water reactor irradiation cobalt target structure comprises a pressing piece, a plurality of flow choking stoppers detachably connected with the pressing piece and a plurality of cobalt rod assemblies detachably connected with the pressing piece, and each cobalt rod assembly comprises a cladding pipe, a plurality of cobalt sheets and a positioning piece; the cobalt sheets are packaged in the cladding tube and are arranged at intervals in the axial direction of the cladding tube, the central axes of the cobalt sheets are perpendicular to the central axis of the cladding tube, and the positioning part is packaged in the cladding tube, detachably connected with the cladding tube and used for positioning the cobalt sheets. According to the pressurized water reactor irradiation cobalt target structure, the loading activity of produced cobalt-60 is improved, meanwhile, components of the cobalt rod assembly are detachable, the cladding pipe and the lower end plug can be repeatedly used, and generation of radioactive waste can be greatly reduced. And a positioning piece is arranged for fixing the cobalt sheet, so that the situation that the cobalt sheet moves and vibrates in the cladding pipe due to the fact that the cobalt rod assembly is scoured by water flow in the pressurized water reactor is prevented.

Description

Technical Field

[0001] The invention relates to the field of reactor neutron irradiation production, and in particular to a pressurized water reactor irradiation cobalt target structure and a use method thereof. Background Art

[0002] Radioactive cobalt-60 is generally produced by irradiation in heavy water reactors, boiling water reactors and research reactors. Due to the neutron spectrum characteristics of pressurized water reactors and the long refueling cycle (generally 18 months), the specific activity of cobalt-60 produced in pressurized water reactors is not high, which has certain application limitations and will reduce the effective full-power operation days of pressurized water reactors, reducing the economic efficiency of power generation in power plants. In addition, in the process of isotope production, irradiation targets will produce radioactive waste, and the treatment of radioactive waste will also reduce the economic efficiency of cobalt-60 production. Therefore, in the production of cobalt-60 by irradiation in pressurized water reactors, it is necessary to consider controlling the impact on the effective full-power operation days of pressurized water reactors and optimizing the structure of cobalt-60 irradiation targets to reduce the amount of radioactive waste generated, so as to improve the economic efficiency of cobalt-60 production. The currently designed pressurized water reactor irradiation targets use resistance plug assemblies, which are non-replaceable structures. The irradiation target core is cobalt particles, which have a complex structure and high production cost. The loading activity does not meet the requirements of industrial irradiation sources, which is not conducive to the subsequent packaging of radioactive sources. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a pressurized water reactor irradiation cobalt target structure and a use method thereof.

[0004] The technical solution adopted by the present invention to solve the technical problem is: constructing a pressurized water reactor irradiation cobalt target structure, which includes a pressing piece, a plurality of choke rods detachably connected to the pressing piece, and a plurality of cobalt rod assemblies detachably connected to the pressing piece;

[0005] The cobalt rod assembly comprises a cladding tube, a plurality of cobalt sheets and a positioning piece;

[0006] A plurality of the cobalt sheets are encapsulated in the cladding tube, and the plurality of the cobalt sheets are arranged separately along the axial direction of the cladding tube, and the central axis of the cobalt sheet is arranged perpendicular to the central axis of the cladding tube;

[0007] The positioning member is encapsulated in the cladding tube and is detachably connected to the cladding tube, and is used for positioning the plurality of cobalt sheets.

[0008] In some embodiments, the interval between adjacent cobalt sheets is no less than 5 mm.

[0009] In some embodiments, the cobalt sheet has a thickness of 0.5 mm to 1.5 mm.

[0010] In some embodiments, a nickel-plated layer is provided on the surface of the cobalt sheet.

[0011] In some embodiments, the cobalt rod assembly further includes an upper end plug connected to the upper end of the cladding tube and a lower end plug connected to the lower end of the cladding tube.

[0012] In some embodiments, the positioning member includes two zirconium sheets, the two zirconium sheets are connected by pressure resistance welding, and the two zirconium sheets are used together to fix and clamp the cobalt sheet.

[0013] In some embodiments, the cobalt rod assembly further includes a helium filling component, which is encapsulated in the cladding tube and is used to fill the cladding tube with helium.

[0014] In this embodiment, a method for using a pressurized water reactor irradiated cobalt target structure is also constructed, which is based on the pressurized water reactor irradiated cobalt target structure and includes the steps of:

[0015] After the irradiation of the PWR irradiated cobalt target structure is completed in the PWR, the irradiated cobalt rod assembly is disassembled in the spent fuel storage pool;

[0016] The disassembled cobalt rod assembly is transported to a hot chamber by a shielded transport container, the cobalt rod assembly is disassembled, and the irradiated cobalt sheets are taken out;

[0017] Packaging the new cobalt rod assembly in a hot chamber;

[0018] Transporting the new cobalt rod assembly to the spent fuel storage pool via the shielded transport container, and assembling the pressing piece and the new cobalt rod assembly in the spent fuel storage pool;

[0019] The new PWR irradiation cobalt target structure is transported to the PWR for irradiation.

[0020] In some embodiments, packaging the new cobalt rod assembly in a hot chamber comprises:

[0021] trimming the used cladding tube;

[0022] loading the cobalt sheet which has not been irradiated;

[0023] Replacing the unirradiated upper end plug and girth-welding the upper end plug to the cladding tube;

[0024] Install the used lower end plug;

[0025] The cladding tube is filled with helium, and after the helium filling is completed, the hole plugging welding is performed.

[0026] In some embodiments, after the packaging of the new cobalt rod assembly in the hot chamber is completed, the threads of the upper end plug are broken in the spent pool.

[0027] The implementation of the present invention has the following beneficial effects: the pressurized water reactor irradiation cobalt target structure is provided with a cobalt sheet, and the central axis of the cobalt sheet is arranged perpendicularly to the central axis of the cladding tube, which has a higher specific activity than the irradiation using cobalt particles or cobalt columns in the past, and improves the loading activity of the produced cobalt-60. At the same time, the components of the cobalt rod assembly are detachable, and the cladding tube and the lower end plug are reusable, which can greatly reduce the generation of radioactive waste. A positioning member is provided for fixing the cobalt sheet to prevent the cobalt sheet from moving and vibrating in the cladding tube due to the scouring of the cobalt rod assembly by water flow in the pressurized water reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solution of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work. In the drawings:

[0029] Figure 1 is a schematic diagram of the overall structure of a pressurized water reactor irradiation cobalt target structure in some embodiments of the present invention;

[0030] Figure 2 is a front cross-sectional view of the structure of a cobalt rod assembly in some embodiments of the present invention;

[0031] Figure 3 1 is a top cross-sectional view of the structure of the cobalt rod assembly in some embodiments of the present invention. DETAILED DESCRIPTION

[0032] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings, are constructed and operated in a specific direction, and are only for the convenience of describing the present technical solution, rather than indicating that the device or element referred to must have a specific direction, and therefore cannot be understood as a limitation to the present invention.

[0033] It should also be noted that, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected", "fixed", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intermediate elements. The terms "first", "second", "third", etc. are only for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", "third", etc. can explicitly or implicitly include one or more of the features. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0034] See also Figures 1 to 3 , is a pressurized water reactor irradiated cobalt target structure in some embodiments of the present invention, which is used to produce cobalt-60, and the pressurized water reactor irradiated cobalt target structure includes a pressing member 1, a plurality of choke rods 2 detachably connected to the pressing member 1, and a plurality of cobalt rod assemblies 3 detachably connected to the pressing member 1. The cobalt rod assembly 3 includes a cladding tube 31, a plurality of cobalt sheets 33, and a positioning member 34. The plurality of cobalt sheets 33 are encapsulated in the cladding tube 31, and the plurality of cobalt sheets 33 are separated and arranged along the axial direction of the cladding tube 31, and the central axis of the cobalt sheet 33 is arranged perpendicular to the central axis of the cladding tube 31. The positioning member 34 is encapsulated in the cladding tube 31 and detachably connected to the cladding tube 31, and is used to position the plurality of cobalt sheets 33.

[0035] The cobalt sheet 33 is initially made of cobalt-59, which absorbs neutrons during the operation of the pressurized water reactor to generate a cobalt-60 radioactive source with a certain specific activity. The central axis of the cobalt sheet 33 is perpendicular to the central axis of the cladding tube 31. The cobalt sheet 33 has a higher specific activity than the irradiation with cobalt particles or cobalt columns in the past, which improves the loading activity of the produced cobalt-60. The cobalt sheet 33 is in the shape of a round sheet.

[0036] The positioning member 34 is specifically used to fix the cobalt sheet 33 , which can be inserted into the cladding tube 31 to prevent the cobalt sheet 33 from moving and vibrating in the cladding tube 31 due to the scouring of the cobalt rod assembly 3 by water flow in the PWR.

[0037] In addition, the cobalt rod assembly 3 further comprises a helium filling member 32 , which is encapsulated in the cladding tube 31 and used to fill the cladding tube 31 with helium. Filling the cladding tube 31 with helium can prevent the cobalt sheet 33 from being oxidized and overheated.

[0038] Furthermore, the interval between adjacent cobalt sheets 33 is not less than 5 mm, so as to ensure that the space between the cobalt sheets 33 can fully absorb neutrons and ensure the loading activity of the produced cobalt-60.

[0039] The thickness of the cobalt sheet 33 is 0.5 mm to 1.5 mm, one for ease of packaging, and the other for ensuring effective utilization of cobalt-59.

[0040] A nickel-plated layer is provided on the surface of the cobalt sheet 33, and the nickel-plated layer can play an anti-oxidation and anti-pollution role, and is of great significance in the subsequent packaging and use of cobalt-60.

[0041] like Figure 2 As shown, the cobalt rod assembly 3 further includes an upper end plug 35 connected to the upper end of the cladding tube 31 and a lower end plug 36 connected to the lower end of the cladding tube 31 , and the upper end plug 35 and the lower end plug 36 are used together to seal the cladding tube 31 .

[0042] like Figure 3 As shown, the positioning member 34 includes two zirconium sheets 341, which are connected by pressure resistance welding, and the two zirconium sheets 341 are used together to fix and clamp the cobalt sheet 33. It can be understood that the cobalt sheet 33 is fixed by using a zirconium sheet 341 with a small neutron absorption cross section to cover and support, and the zirconium sheet 341 can be rolled into an arc shape. The two zirconium sheets 341 clamp the cobalt sheet 33 together to prevent the cobalt sheet 33 from moving and vibrating in the cladding tube 31.

[0043] In this embodiment, a method for using a pressurized water reactor irradiated cobalt target structure is also constructed, which is based on the above pressurized water reactor irradiated cobalt target structure and includes the steps of:

[0044] After the irradiation of the pressurized water reactor irradiated cobalt target structure in the pressurized water reactor is completed, the irradiated cobalt rod assembly 3 is disassembled in the spent fuel storage pool; the disassembled cobalt rod assembly 3 is transported to the hot chamber through a shielded transport container, the cobalt rod assembly 3 is disassembled, and the irradiated cobalt sheet 33 is taken out; the new cobalt rod assembly 3 is packaged in the hot chamber; the new cobalt rod assembly 3 is transported to the spent fuel storage pool through a shielded transport container, and the pressing piece 1 and the new cobalt rod assembly 3 are assembled in the spent fuel storage pool; the new pressurized water reactor irradiated cobalt target structure is transported to the pressurized water reactor for irradiation.

[0045] Furthermore, the packaging of the new cobalt rod assembly 3 in the hot chamber includes: trimming the used cladding tube 31; loading the unirradiated cobalt sheet 33; replacing the unirradiated upper end plug 35, and performing girth welding between the upper end plug 35 and the cladding tube 31; loading the used lower end plug 36; filling the cladding tube 31 with helium, and performing plugging welding after the helium filling is completed. It can be understood that after the old cobalt rod assembly 3 is disassembled, the cladding tube 31 and the lower end plug 36 can be reused, which can greatly reduce the generation of radioactive waste.

[0046] After the packaging of the new cobalt rod assembly 3 is completed in the hot chamber, the thread of the upper end plug 35 is broken in the spent pool to prevent the nut from loosening.

[0047] In summary, the pressurized water reactor irradiation cobalt target structure and its use method have the following beneficial effects: the pressurized water reactor irradiation cobalt target structure is provided with a cobalt sheet 33, and the central axis of the cobalt sheet 33 is arranged perpendicularly to the central axis of the cladding tube 31, which has a higher specific activity than the irradiation using cobalt particles or cobalt columns in the past, and improves the loading activity of the produced cobalt-60. At the same time, the components of the cobalt rod assembly 3 are detachable, and the cladding tube 31 and the lower end plug 36 are reusable, which can greatly reduce the generation of radioactive waste. A positioning member 34 is provided for fixing the cobalt sheet 33 to prevent the cobalt sheet 33 from moving and vibrating in the cladding tube 31 due to the scouring of the cobalt rod assembly 3 by water flow in the pressurized water reactor.

[0048] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the scope covered by the claims of the present invention.

Claims

1. A pressurized water reactor irradiation cobalt target structure, characterized in that: It comprises a pressing piece (1), a plurality of flow blocking rods (2) detachably connected to the pressing piece (1), and a plurality of cobalt rod assemblies (3) detachably connected to the pressing piece (1); The cobalt rod assembly (3) comprises a cladding tube (31), a plurality of cobalt sheets (33) and a positioning member (34); A plurality of the cobalt sheets (33) are encapsulated in the cladding tube (31), the plurality of the cobalt sheets (33) are arranged separately along the axial direction of the cladding tube (31), and the central axis of the cobalt sheet (33) is arranged perpendicular to the central axis of the cladding tube (31); The positioning member (34) is encapsulated in the cladding tube (31) and is detachably connected to the cladding tube (31), and is used to position a plurality of the cobalt sheets (33).

2. The pressurized water reactor irradiation cobalt target structure according to claim 1, characterized in that: The interval between adjacent cobalt sheets (33) is not less than 5 mm.

3. The pressurized water reactor irradiation cobalt target structure according to claim 1, characterized in that: The thickness of the cobalt sheet (33) is 0.5 mm to 1.5 mm.

4. The pressurized water reactor irradiation cobalt target structure according to claim 1, characterized in that: A nickel plating layer is provided on the surface of the cobalt sheet (33).

5. The pressurized water reactor irradiation cobalt target structure according to claim 1, characterized in that: The cobalt rod assembly (3) further comprises an upper end plug (35) connected to the upper end of the cladding tube (31) and a lower end plug (36) connected to the lower end of the cladding tube (31).

6. The pressurized water reactor irradiation cobalt target structure according to claim 1, characterized in that: The positioning member (34) comprises two zirconium sheets (341), the two zirconium sheets (341) are connected by pressure resistance welding, and the two zirconium sheets (341) are used together to fix and clamp the cobalt sheet (33).

7. The pressurized water reactor irradiation cobalt target structure according to claim 1, characterized in that: The cobalt rod assembly (3) further comprises a helium filling component (32), wherein the helium filling component (32) is encapsulated in the cladding tube (31) and is used to fill the cladding tube (31) with helium.

8. A method for using a pressurized water reactor irradiated cobalt target structure, based on the pressurized water reactor irradiated cobalt target structure according to any one of claims 1 to 7, characterized in that: Includes steps: After the irradiation of the pressurized water reactor irradiated cobalt target structure in the pressurized water reactor is completed, the irradiated cobalt rod assembly (3) is disassembled in the spent fuel storage pool; The disassembled cobalt rod assembly (3) is transported to a hot chamber via a shielded transport container, the cobalt rod assembly (3) is disassembled, and the irradiated cobalt sheets (33) are taken out; Packaging the new cobalt rod assembly (3) in a hot chamber; transporting the new cobalt rod assembly (3) to a spent fuel storage pool via the shielded transport container, and assembling the pressing piece (1) and the new cobalt rod assembly (3) in the spent fuel storage pool; The new PWR irradiation cobalt target structure is transported to the PWR for irradiation.

9. The method for using the pressurized water reactor irradiation cobalt target structure according to claim 8, characterized in that: The packaging of the new cobalt rod assembly (3) in the hot chamber comprises: trimming the used cladding tube (31); Loading the cobalt sheet (33) which has not been irradiated; replacing the unirradiated upper end plug (35), and girth-welding the upper end plug (35) and the cladding tube (31); Insert the used lower end plug (36); The cladding tube (31) is filled with helium, and after the filling with helium is completed, the hole plugging welding is performed.

10. The method for using the pressurized water reactor irradiation cobalt target structure according to claim 8, characterized in that: After the packaging of the new cobalt rod assembly (3) is completed in the hot chamber, the threads of the upper end plug (35) are broken in the spent tank.

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