Visual neutron reference radiation generating device

Abstract

The visual neutron reference radiation generating device comprises a neutron source tank and a radioactive isotope neutron source, a source storage cabin is arranged in the center of the neutron source tank, a source guiding opening and a source rising air inlet are oppositely formed in the upper portion and the lower portion of the source storage cabin, and the source guiding opening is communicated with an irradiation cabin on the outer side of the neutron source tank through a source guiding pipe; the rising source air inlet is connected with a rising source air pipe, the irradiation cabin is provided with a falling source air inlet, and the falling source air inlet is connected with a falling source air pipe; the inner diameters of the source rising gas pipe and the source falling gas pipe are smaller than the size of the radioactive isotope neutron source; the neutron source tank is made of transparent crosslinked polyethylene or organic glass, light water or a boric acid solution is arranged in the neutron source tank, a water injection port and an exhaust port are formed in the upper part of the neutron source tank, and an emptying port is formed in the lower part of the neutron source tank. The device is visualized, the economic cost can be effectively reduced while the shielding effect is guaranteed, the maintainability of the device is improved, and the calibration and verification service of instruments and meters for radiation protection can be efficiently provided for clients.

Description

Technical Field

[0001] The invention belongs to the technical field of ionizing radiation metrology and verification, and in particular relates to a visual neutron reference radiation generating device. Background Art

[0002] With the comprehensive upgrade of the public's understanding of ionizing radiation, the demand for ionizing radiation measurement and verification is no longer limited to a few fields such as scientific research, education, and radiation health. More and more scientific and technological innovation companies are investing in this field.

[0003] According to ISO / FDIS8529.1-2021 "Reference neutron radiations fields-Part 1: Characteristics and methods of production", the principle of the commonly used neutron reference radiation generation device is based on the application of radioisotope neutron sources. The device generally consists of three parts: a neutron source tank, a neutron source transmission device (rabbit) and a radioisotope neutron source; americium beryllium neutron source is usually used, and californium neutron source is occasionally used.

[0004] The neutron source tank is mainly made of materials such as boron-containing polyethylene, lead, and stainless steel, while the neutron source transmission device is made of stainless steel pipes or aluminum pipes. The material and processing costs are expensive; and the finished product is invisible, which is mainly reflected in the invisible in-place diagnosis of the conversion of the radioactive source from the storage state to the irradiation state (the process of lifting the source). When such an accident occurs, that is, the in-place diagnosis signal is not triggered, it may be a fault of the in-place diagnosis system itself, or it may be a real source jam accident; for source jam accidents, this invisible device is difficult to determine the specific source jam location, which brings considerable difficulty to the handling of the accident. Experienced engineers are required to troubleshoot the fault on site, report it to the operating unit and after-sales maintenance team according to the specific situation, and arrange professional technicians to deal with it on site. During this period, the equipment may be unavailable for a long time, which in turn affects the calibration and verification services of radiation protection instruments and meters provided by the operating unit to its customers. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a visualized neutron reference radiation generating device. The device of the present invention is visualized, which can effectively reduce economic costs while ensuring the shielding effect, improve the maintainability of the device, and can efficiently provide customers with calibration and verification services for radiation protection instruments.

[0006] The technical solution of the present invention is achieved in this way: A visualized neutron reference radiation generating device comprises a neutron source tank and a radioactive isotope neutron source, wherein the center of the neutron source tank is provided with a source storage cabin for storing the radioactive isotope neutron source, a source guide port and a source raising air inlet are arranged oppositely above and below the source storage cabin, the source guide port is communicated with an irradiation cabin outside the neutron source tank through a source guide pipe, the source raising air inlet is connected with a source raising air pipe for introducing compressed air so as to facilitate blowing the radioactive isotope neutron source in the source storage cabin into the irradiation cabin, the irradiation cabin is provided with a source lowering air inlet, the source lowering air inlet is connected with a source lowering air pipe for introducing compressed air so as to blow the radioactive isotope neutron source in the irradiation cabin into the source storage cabin; the inner diameters of the source raising air pipe and the source lowering air pipe are smaller than the size of the radioactive isotope neutron source.

[0007] The source guide tube is made of a transparent cross-linked polyethylene hose; the neutron source tank is made of transparent cross-linked polyethylene or organic glass, and light water or boric acid solution is arranged in the neutron source tank. A water inlet and an exhaust port are arranged at the top of the neutron source tank, and an emptying port is arranged at the bottom.

[0008] Furthermore, a boric acid solution is provided in the neutron source tank, and a plurality of partitions are provided in the neutron source tank. All the partitions are vertically arranged and evenly distributed along the circumference of the central axis of the neutron source tank, thereby dividing the neutron source tank into a plurality of compartments. A connecting port is provided on each partition, thereby connecting two adjacent compartments; and an auxiliary heating device is provided in one of the compartments for heating the boric acid solution, so that the boric acid solution forms thermal convection in the neutron source tank.

[0009] Furthermore, an impeller is provided at the communication port to facilitate the impeller to rotate under the action of thermal convection to stir the boric acid solution.

[0010] Furthermore, the impeller is connected to a driving motor to drive the impeller to rotate.

[0011] Furthermore, it also includes a camera, which is arranged on the outside of the neutron source tank and is used to obtain the position data of the radioactive isotope neutron source in real time.

[0012] Furthermore, the neutron source tank has a spherical, cylindrical, hexagonal or rectangular shape.

[0013] Furthermore, the radioisotope neutron source is 241 Am-Be, 241 Am-B, 210 Po-Be, 226 Ra-Be or 252 Cf.

[0014] Furthermore, the source storage cabin has a plurality of compartments, and correspondingly, a radioactive isotope neutron source is arranged in each compartment.

[0015] Furthermore, a 45° inclined tee is provided near the irradiation chamber, two interfaces of which are respectively connected to the irradiation chamber and the source guide tube, and the other interface is used to install a radioactive isotope neutron source, and a plug is provided on the interface to seal the interface.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The neutron source tank of the present invention is made of transparent cross-linked polyethylene or organic glass, and the source guide tube as a neutron source delivery pipeline is made of a transparent cross-linked polyethylene hose. Light water or boric acid solution is injected into the neutron source tank, which can make the neutron source tank transparent and visible while achieving neutron shielding; the source guide tube can allow the neutron source to freely reciprocate inside it under the action of compressed gas, and can achieve neutron source state conversion while also having visibility. Operators can quickly determine the reason why the in-place diagnostic signal is not triggered through the video monitoring system, independently handle the source jamming accident, shorten the equipment unavailability time, and ensure that the calibration and verification services of neutron measuring instruments are provided to customers.

[0017] 2. The present invention adopts light water or boric acid solution as the main shielding material, which can not only reduce the economic cost, but also solve the shielding problem caused by the installation joints of the neutron source tank and the neutron source transmission sleeve which were assembled by the boron-containing polyethylene plate in the past, thereby improving the shielding effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 -Schematic diagram of the structure of the present invention.

[0019] Figure 2 - Assembly comparison diagram of the prior art and the present invention.

[0020] Among them: 1-neutron source tank; 2-source storage cabin; 3-source guide pipe; 4-source rising gas pipe; 5-irradiation cabin; 6-source descending gas pipe; 7-auxiliary heating equipment; 8-camera; 9-radioactive isotope neutron source; 10-water injection port; 11-exhaust port; 12-emptying port. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0022] See also Figure 1A visualized neutron reference radiation generating device comprises a neutron source tank 1 and a radioactive isotope neutron source 9, wherein the center of the neutron source tank 1 is provided with a source storage cabin 2 for storing the radioactive isotope neutron source 9, and source guide ports and source ascending air inlets are arranged above and below the source storage cabin 2, respectively. The source guide ports are communicated with an irradiation cabin 5 outside the neutron source tank 1 through a source guide pipe 3, and the source ascending air inlet is connected with a source ascending air pipe 4 for introducing compressed air to facilitate blowing the radioactive isotope neutron source 9 in the source storage cabin 2 into the irradiation cabin 5, and the irradiation cabin 5 is provided with a source descending air inlet, and the source descending air inlet is connected with a source descending air pipe 6 for introducing compressed air to blow the radioactive isotope neutron source 9 in the irradiation cabin 5 into the source storage cabin 2; the inner diameters of the source ascending air pipe 4 and the source descending air pipe 6 are smaller than the size of the radioactive isotope neutron source 9.

[0023] The source guide tube 3 is made of a transparent cross-linked polyethylene hose; the neutron source tank 1 is made of a transparent cross-linked polyethylene or organic glass, and light water or boric acid solution is arranged in the neutron source tank 1. The upper part of the neutron source tank 1 is provided with a water injection port 10 and an exhaust port 11, and the lower part is provided with an emptying port 12. The water injection port is used to inject light water or boric acid solution into the neutron source tank, and the emptying port is used to discharge the light water or boric acid solution in the neutron source tank when the light water or boric acid solution does not meet the shielding requirements.

[0024] In specific applications, the radioisotope neutron source is 241 Am-Be, 241 Am-B, 210 Po-Be, 226 Ra-Be or 252 Cf. Light water or boric acid solution is injected into the neutron source tank to shield the neutron source and its accompanying gamma rays. 241 Am-Be neutron source, light water transmission coefficient B = e -0.11t , where t is the thickness of the water layer; the addition of boric acid solution is mainly to absorb thermal neutrons through the (n,γ) reaction, further reducing the thickness of the water layer. At the same time, the water shielding layer also needs to shield two groups of γ rays, one of which is 9 Be(α,n) 12m The other group is the 4.4 MeV gamma rays released by the (n,γ) reaction. 241 The gamma rays produced by the decay of Am can generally be shielded by a lead sheet wrapped around the outer layer of the neutron source. The radiation shielding scheme of the neutron source tank can ultimately be designed through a Monte Carlo program combined with the actual activity of the neutron source.

[0025] Here, the neutron source tank is made of transparent cross-linked polyethylene or plexiglass, and light water or boric acid solution is injected inside. This can make the neutron source tank transparent and visible while achieving neutron shielding. The source guide tube, as a neutron source delivery pipeline, is made of a transparent cross-linked polyethylene hose. Under the action of compressed gas, the neutron source can freely reciprocate inside it, achieving neutron source state conversion while also having visibility. The operator can observe the position of the neutron source. When the diagnostic signal is not triggered after the neutron source state conversion (source lifting and lowering process) is completed, that is, when a source jam accident occurs, the specific source jam location can be easily determined, reducing the difficulty of accident handling.

[0026] At the same time, light water or boric acid solution is used instead of traditional boron-containing polyethylene, and the operator can achieve cost reduction and efficiency improvement in equipment manufacturing, installation, commissioning, operation, maintenance and many other aspects. The source guide tube is a hose. When a source jam occurs, the source guide tube can be shaken from a distance with tools such as long-handled tweezers to quickly handle the jam, greatly reducing the consequences of the accident, avoiding unnecessary radiation exposure of workers caused by secondary accidents, and ensuring the radiation safety of workers.

[0027] During specific implementation, a boric acid solution is provided in the neutron source tank 1, and a plurality of partitions are provided in the neutron source tank. All the partitions are vertically arranged and evenly distributed along the circumference of the central axis of the neutron source tank 1, thereby dividing the neutron source tank into a plurality of compartments. A connecting port is provided on each partition, thereby connecting two adjacent compartments; and an auxiliary heating device 7 is provided in one of the compartments for heating the boric acid solution, so that the boric acid solution forms thermal convection in the neutron source tank 1.

[0028] In this way, an auxiliary heating device is arranged in a compartment of the neutron source tank, which can heat the boric acid solution, so that the boric acid solution forms thermal convection in the neutron source tank, and realizes the natural circulation of the boric acid solution in the neutron tank, so as to ensure that the temperature is higher than the saturation temperature of the boric acid solution, avoid boric acid crystallization, ensure the uniformity of the concentration of the boric acid solution, and ensure the neutron shielding effect.

[0029] In a specific implementation, an impeller is provided at the communication port, so as to facilitate the impeller to rotate under the action of thermal convection to stir the boric acid solution. The boric acid solution is further stirred to improve the concentration uniformity of the boric acid solution. In a specific implementation, the impeller is connected to a drive motor to drive the impeller to rotate. When the thermal convection drive is insufficient, the drive motor can be turned on to control the impeller to rotate, so as to realize the forced circulation of the boric acid solution between the compartments in the neutron source tank.

[0030] In the specific implementation, it also includes a camera 8, which is arranged on the outside of the neutron source tank 1 and is used to obtain the position data of the radioisotope neutron source 9 in real time. In this way, the camera can monitor the position of the neutron source in real time during the process of lifting the neutron source. When a source jam accident occurs, the source jam position can be quickly located, and the operator can quickly and independently determine the reason why the signal is not triggered without notifying the after-sales maintenance team. In the event of a source jam accident, the operator can also independently determine the source jam position through the video content, and quickly complete the accident handling through remote or on-site guidance of the after-sales maintenance team, without delaying the operating unit to provide its customers with calibration and verification services for neutron measuring instruments, thereby efficiently providing customers with calibration and verification services for radiation protection instruments.

[0031] In a specific implementation, the shape of the neutron source tank 1 includes but is not limited to a sphere, a cylinder, a hexagonal prism or a cuboid.

[0032] In specific implementation, the source storage cabin 2 has several cabins, and correspondingly, each cabin is provided with a radioisotope neutron source 9. In specific application, it can be set to a single cabin, double cabin, three cabins or four cabins structure according to needs.

[0033] In specific implementation, the source guide tube, the source ascending air inlet tube and the source descending air inlet tube are all bent, and the bending radius of the source guide tube is large, so that the inner wall of the source guide tube is smoother and the probability of the neutron source getting stuck when the source guide tube is transmitted is reduced.

[0034] Compared with the neutron source tank using boron-containing polyethylene sheet as the main shielding material (its cross section and profile diagram are shown in the figure), Figure 2 a and Figure 2 b) is made of several boron-containing polyethylene plates staggered together, and a sleeve is prefabricated in the neutron source tank for the source tube to pass through. There are assembly gaps between the boron-containing polyethylene plates, and neutron radiation will scatter through the sleeve. Figure 2 c) There are no assembly gaps, and the source guide tube here is in a smoothly curved state inside the neutron source tank. When the neutron source is stored in the source storage cabin, neutrons will not be ejected out of the neutron source tank in a straight line through the source guide tube, but will be ejected out of the neutron source tank by scattering or passing through the light water boric acid solution, thereby effectively reducing radiation.

[0035] In specific implementation, a 45° inclined tee is provided near the irradiation chamber 5, and two interfaces of the inclined tee are respectively connected to the irradiation chamber 5 and the source guide tube 3, and the other interface is used to install the radioactive isotope neutron source 9, and a plug is provided at the interface to close the interface.

[0036] Finally, it should be noted that the above embodiments of the present invention are only examples for illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes and modifications can be made based on the above description. It is impossible to list all implementation methods here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A visual neutron reference radiation generating device, comprising a neutron source tank and a radioisotope neutron source, characterized in that: The center of the neutron source tank is provided with a storage source cabin for storing radioactive isotope neutron sources, and source guide ports and source ascending air inlets are arranged above and below the storage source cabin, respectively. The source guide ports are connected to the irradiation cabin outside the neutron source tank through a source guide pipe, and the source ascending air inlet is connected to a source ascending air pipe for introducing compressed air, so as to facilitate blowing the radioactive isotope neutron source in the storage source cabin into the irradiation cabin. The irradiation cabin is provided with a source descending air inlet, and the source descending air inlet is connected to the source descending air pipe for introducing compressed air, so as to blow the radioactive isotope neutron source in the irradiation cabin into the storage source cabin; the inner diameters of the source ascending air pipe and the source descending air pipe are smaller than the size of the radioactive isotope neutron source; The source guide tube is made of a transparent cross-linked polyethylene hose; the neutron source tank is made of transparent cross-linked polyethylene or organic glass, and light water or boric acid solution is arranged in the neutron source tank. A water inlet and an exhaust port are arranged at the top of the neutron source tank, and an emptying port is arranged at the bottom.

2. A visual neutron reference radiation generating device according to claim 1, characterized in that: A boric acid solution is arranged in the neutron source tank. A plurality of partitions are arranged in the neutron source tank. All the partitions are arranged vertically and evenly distributed along the circumference of the central axis of the neutron source tank, so as to divide the neutron source tank into a plurality of compartments. A connecting port is arranged on each partition, so as to connect two adjacent compartments. An auxiliary heating device is arranged in one of the compartments for heating the boric acid solution, so that the boric acid solution forms thermal convection in the neutron source tank.

3. A visual neutron reference radiation generating device according to claim 2, characterized in that: An impeller is arranged at the connecting port, so as to promote the impeller to rotate under the action of thermal convection to stir the boric acid solution.

4. A visual neutron reference radiation generating device according to claim 3, characterized in that: The impeller is connected to a driving motor to drive the impeller to rotate.

5. A visual neutron reference radiation generating device according to any one of claims 1 to 4, characterized in that: It also includes a camera, which is arranged on the outside of the neutron source tank and is used to obtain the position data of the radioactive isotope neutron source in real time.

6. The visual neutron reference radiation generating device according to claim 1, characterized in that: The neutron source tank has a spherical shape, a cylindrical shape, a hexagonal prism or a rectangular parallelepiped shape.

7. The visual neutron reference radiation generating device according to claim 1, characterized in that: The radioisotope neutron source is 241 Am-Be, 241 Am-B, 210 Po-Be, 226 Ra-Be or 252 Cf.

8. A visual neutron reference radiation generating device according to claim 1 or 7, characterized in that: The source storage cabin has a plurality of compartments, and correspondingly, a radioactive isotope neutron source is arranged in each compartment.

9. The visual neutron reference radiation generating device according to claim 1, characterized in that: A 45° inclined tee is provided near the irradiation cabin, and two interfaces of the inclined tee are respectively connected to the irradiation cabin and the source guide tube, and the other interface is used to install the radioactive isotope neutron source, and a plug is provided on the interface to close the interface.

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