Utilization of subcritical neutron multiplication by an electron neutron generator for producing radioisotopes

Abstract

A target irradiation device for producing a radioactive isotope line source is provided. The target irradiation device includes a storage container, a plurality of electron neutron generation insertion parts, and a removable neutron enhancement cartridge. The storage container includes an inner surface, an outer surface, a first end, a second end, a main body part, and a support member. Each of the plurality of electron neutron generator insertion devices is inserted into a plurality of openings in the main body part, and the removable neutron enhancement cartridge is adapted to be disposed inside the storage container. A radioactive isotope production system including the target irradiation device and a method for producing a radioactive isotope source are also provided.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit and priority under 35 U.S.C.§120 to U.S. Patent Application No. 17 / 807,067, entitled "USE OF SUB - CRITICAL NEUTRON MULTIPLICATION DRIVEN BY ELECTRONIC NEUTRON GENERATORS TO PRODUCE RADIOISOTOPES", filed on June 15, 2022, the content of which is hereby incorporated by reference in its entirety.

Background Art

[0002] Much of the development and implementation of new radiation therapies depends on the ready availability of medical radioisotopes. Medical radioisotopes are typically produced by irradiating a parent isotope with a very large number of neutrons. Conventional methods for generating a sufficient number of neutrons to reliably produce medical radioisotopes require an operating nuclear reactor. However, access to an operating nuclear reactor for the production of medical radioisotopes with short half - lives is restricted, so it is a difficult endeavor to reliably and economically produce medical radioisotopes on demand. Alternative sources for generating a large number of neutrons, such as electronic neutron generators, cannot generate a large - scale neutron flux that is effective for the commercial production of medical radioisotopes. There is a need to develop alternative neutron generation systems and methods of operating them to optimize the certainty and economy of medical radioisotope production.

Summary of the Invention

Means for Solving the Problems

[0003] The following summary is provided to facilitate understanding of some of the innovative features specific to the aspects disclosed herein and is not intended to be a complete description. A complete understanding of the various aspects disclosed herein can be obtained by taking the entire specification, claims, and abstract as a whole.

[0004] In various aspects, a target irradiation device for producing a radioisotope source is disclosed. In some aspects, the target irradiation device includes a storage container having an inner surface and an outer surface, a plurality of electron neutron generators (hereinafter referred to as "ENG") insertion devices, and a removable neutron multiplier cartridge. In some aspects, the storage container includes a first end, a plurality of through-holes extending from the outer surface to the inner surface, a second end adapted to be coupled to a transport system for an irradiation target insert, a body portion extending between an upper end and a lower end and having a plurality of openings, each of the plurality of openings being adapted to fit a radiation shielding plug, the body portion, and a support member having a plurality of channels, the channels being aligned with the through-holes of the second end, and a first surface of the support member facing the inner surface of the second end, the support member. In some aspects, each of the plurality of ENG insertion devices of the target irradiation device is inserted into each of the plurality of openings of the body portion. In some aspects, the removable neutron multiplier cartridge is disposed on a second surface of the support member. In some aspects, the neutron multiplier cartridge includes a cell structure and a neutron multiplier assembly. In some aspects, the cell structure includes a plurality of panels configured to form at least one cell volume, and each of the plurality of panels includes an outer metal shell. In some aspects, the neutron multiplier assembly is configured to be removably inserted into at least one cell volume and is adapted to align with one of the plurality of channels of the support member to accommodate an irradiation target insert.

[0005] In various aspects, a radioisotope production system for producing a radioisotope source is disclosed. In some aspects, the radioisotope production system includes a neutron multiplication device, at least one removable neutron multiplication cartridge, and a removable transport system for an irradiation target insert. In some aspects, the neutron multiplication device includes a storage container having an inner surface and an outer surface, and a plurality of electron neutron generator insertion devices. In some aspects, the storage container includes an upper end portion having a removable container lid, a plurality of longitudinally oriented openings extending from the outer surface to the inner surface, a lower end portion adapted to be coupled with the irradiation target insert transport system, and a main body portion extending longitudinally between the upper end portion and the lower end portion and having a plurality of side openings, each of the plurality of side openings being adapted to mate with a radiation shielding plug, the main body portion, and a lower support member disposed on the inner surface above the lower end portion and having a plurality of longitudinally oriented channels, the longitudinally oriented channels being aligned with the longitudinally oriented openings of the lower end portion, the lower support member. In some aspects, each of the electron neutron generator insertion devices is inserted into a respective one of the plurality of side openings of the main body portion. In some aspects, at least one removable neutron multiplication cartridge is adapted to be attached to the lower support member within the storage container of at least one neutron multiplication device. In some aspects, at least one removable neutron multiplication cartridge includes a cell structure having an array of cell volumes, each cell volume being configured to accommodate a neutron multiplication assembly, the neutron multiplication assembly being adapted to align with one of the plurality of longitudinally oriented channels of the lower support member and accommodate an irradiation target insert. In some aspects, the removable transport system for the irradiation target insert is adapted to move the irradiation target through the lower end portion of the storage container.

[0006] In various aspects, a method of producing a radioisotope source is disclosed. In some aspects, the method includes initializing a radioisotope production system and producing a radioisotope source. In some aspects, initializing the radioisotope production system includes submerging a first neutron multiplication cartridge in a spent fuel pool and loading at least one spent fuel assembly into the first neutron multiplication cartridge, where the newly installed first neutron multiplication cartridge has a neutron multiplication factor K eff and loading it, submerging the open radioisotope production system in the spent fuel pool, where the open radioisotope production system includes an array of electron neutron generator insertion devices, submerging it, loading the newly installed first neutron multiplication cartridge into the submerged radioisotope production system, closing the loaded radioisotope production system, and inserting an irradiation target into the closed radioisotope production system. In some aspects, producing the radioisotope source includes supplying power to the array of electron neutron generator insertion devices to irradiate the inserted irradiation target and withdrawing the irradiation target from the closed radioisotope production system to produce a radioisotope source.

[0007] These and other objects, features, and characteristics of the present disclosure, as well as the operating methods and functions of the related elements of the structure, as well as the combinations of parts and the economics of production, will become more apparent by considering the following description and the appended claims with reference to the accompanying drawings. The following description and the claims are part of this specification, and in the drawings, like reference numerals indicate corresponding parts. However, it should be clearly understood that the drawings are for illustrative and explanatory purposes only and are not intended as a definition of the limitations of the aspects disclosed herein.

Brief Description of the Drawings

[0008] The various aspects described in this specification will be best understood in conjunction with the accompanying drawings and the following description, along with their purposes and advantages.

[0009]

Figure 1

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Figure 6

[0015] In the plurality of drawings, corresponding reference numerals indicate corresponding parts. The examples described in this specification illustrate the various aspects of the present disclosure in some form, and such examples should not be construed as limiting the scope of the aspects disclosed herein.

Mode for Carrying Out the Invention

[0016] To provide a holistic understanding of the principles, functions, production, and use of the compositions and methods disclosed herein, specific exemplary aspects of the present disclosure are described. Examples of these aspects are shown in the accompanying drawings. Those skilled in the art will understand that the compositions, articles, and methods specifically described herein and shown in the accompanying drawings are non-limiting exemplary aspects, and the scope of the various examples of the present invention is defined only by the claims. Features illustrated or described with respect to one exemplary aspect can be combined with features of other aspects. Such modifications and variations are within the scope of the present invention.

[0017] Throughout this specification, words such as "various examples", "some examples", "one example", "an example", etc. mean that the specific features, structures, or characteristics described with respect to that example are included in the example. Thus, expressions such as "in various examples", "in some examples", "in one example", "in an example", etc. used throughout this specification do not necessarily all refer to the same example. Furthermore, the specific features, structures, or characteristics may be combined in any suitable manner in one or more examples. Accordingly, the specific features, structures, or characteristics illustrated or described with respect to one example may be combined, in whole or in part, without limitation, with the features, structures, or characteristics of another one or more examples. Such modifications and variations are within the scope of this example.

[0018] In the following description, like reference characters in several figures indicate like or corresponding parts. Also, in the following description, it should be understood that words such as "front", "rear", "left", "right", "above", "below", "upper", "lower", etc. are for convenience and are not to be construed as limiting terms.

[0019] A radioactive isotope is an unstable isotope of an element with excess nuclear energy. Therefore, radioactive isotopes release excess nuclear energy in various decay modes, generally at a decay rate called the half-life. Radioactive isotopes are used in a variety of commercial applications, such as nuclear medicine, food preservation, industrial production, and geological dating. Medical radioactive isotopes are usually short-lived. For example, molybdenum-99 is a medical radioactive isotope with a half-life of about 66 hours. Generally, medical radioactive isotopes are synthetically produced as fission products or induced radioactive isotopes. For example, after nuclear fission occurs in a nuclear reactor containing uranium-235, the remaining fission products and unreacted uranium-235 are removed, and molybdenum-99 is separated from them.

[0020] Alternatively, the short-lived radioactivity of stable isotopes can be induced using a neutron beam source. Whether a neutron source can activate a stable isotope within a certain time depends on the thermal neutron flux of the neutron source and the neutron absorption characteristics of the isotope. For example, commercially available ENG such as ENG using deuterium-tritium fusion can be used for the production of radioactive isotopes, but these ENG usually do not generate a flux effective for producing medical radioactive isotopes on a commercial scale. For example, for the commercial production of medical radioactive isotopes such as molybdenum-99, lutetium-177, and actinium-225, a thermal neutron flux on the order of 10 11 neutrons / cm 2 / s is suitable. However, the neutron flux of ENG using deuterium-tritium fusion is usually on the order of 10 9 neutrons / cm 2 / s. Therefore, for the commercial production of medical radioactive isotopes, a nuclear reactor that can usually provide a neutron flux sufficient for neutron activation is used. For example, when an irradiation target containing the stable isotope of molybdenum-98 is inserted into the fuel assembly of an operating nuclear reactor, molybdenum-98 absorbs a part of the free neutrons generated there, forming an unstable molybdenum-99 radionuclide product, which is then removed from the fuel assembly.

[0021] In the case of a nuclear reactor, when fissile fuel splits into multiple daughter radioactive isotopes, first-generation free neutrons are released. When at least a part of the first-generation neutrons is absorbed by other atomic nuclei, another nuclear fission event and the generation of second-generation neutrons are induced. The neutron multiplication factor K of a specific array among the fissile fuel assemblies eff represents the ratio of the number of neutrons generated by nuclear fission in one neutron generation to the number of neutrons lost by absorption in the previous neutron generation. When initially loading a nuclear reactor fuel assembly into a reactor vessel, the neutron level inside the reactor vessel and its gradual changes are monitored by a neutron source region detector and / or a BF3 neutron detector so that each fuel assembly is placed in the reactor core. Changes due to the addition of fuel assemblies and the arrangement of fuel assemblies within the array are used to confirm the predicted K eff value.

[0022] Due to the discharge burnup during the service life of the fuel assembly, the K ∞ of the fuel assembly gradually decreases to a reactivity level where it becomes unusable. For example, in a fuel assembly with uranium-235 having an initial enrichment of 5%, after a discharge burnup of about 48 GWd / MTU, the value of K ∞ becomes as high as about 0.99. This indicates that the spent fuel assembly can no longer achieve a critical reactivity. A long-term reactor shutdown procedure is initiated, and the spent fuel assembly is removed from the reactor and then stored underwater in a spent fuel pool.

[0023] Using an operating nuclear reactor as a neutron source for medical radioisotope production involves certain complexities regarding operation and safety. Usually, an operating nuclear reactor has a K effIt is controlled to maintain a critical state where it is 1.0, and neutrons are generated by a stable self-sustaining nuclear fission chain reaction even without a neutron flux source. To maintain a stable operating state and, in particular, to avoid a catastrophic runaway of neutron generation when components that affect the reactivity in the reactor are perturbed, it is necessary to precisely control the operating reactor. For example, when the absorption of neutrons by secondary non-fissionable reactor elements including burnable absorbers and control rods is insufficient, K eff will reach a supercritical state where it exceeds 1.0, and the number of neutrons may increase exponentially at an extremely high speed.

[0024] To obtain access rights to an operating reactor for the above-described radioactive isotope production means can be costly and may be difficult to obtain. Furthermore, since there are risks specific to self-sustaining nuclear fission reactions, special safety precautions must be strictly observed to maintain control of the nuclear chain reaction. Although ENG devices are readily available, they cannot provide a neutron flux suitable for reliably producing medical radioactive isotopes on a large scale. Accordingly, various aspects of the present disclosure provide various methods and apparatuses for easily and safely producing medical radioactive isotopes without sacrificing productivity.

[0025] The various methods and apparatuses provided by the present disclosure optimize the technical and economic aspects of the production of medical radioactive isotopes, such as neutron activation of an irradiation target. In some embodiments, this optimization may advantageously include upcycling waste from nuclear energy production to make medical radioactive isotopes more accessible and / or reliably supplied compared to the production of conventional medical radioactive isotopes.

[0026] FIG. 1 shows a schematic diagram of a target irradiation device 100 according to at least one non-limiting aspect of the present disclosure. The target irradiation device 100 includes a storage container 200, a plurality of ENG insertion devices 300, and a removable neutron multiplication cartridge 400. In various examples, the storage container 200 may include an inner surface 202, an outer surface 204, a first end 210, a second end 220, a body portion 230, and a support member 240.

[0027] In various examples, the first end 210 may be configured as the upper end of the storage container 200. The first end 210 of the storage container may be adapted to provide access to the interior of the container. For example, the first end 210 may be removably attached to the body portion 230. In some examples, the first end 210 may be configured as a removable container lid. In a particular example, the first end 210 may be configured to have a seal so as to substantially isolate the interior of the storage container 200. The configuration of the first end 210 enables easy loading and unloading of components into and out of the storage container. For example, when the first end 210 is configured as a removable lid, components can be lifted and easily removed from the top, and then new components can be inserted. This configuration is particularly advantageous in an underwater environment where remote operation of components can be complex, such as in a spent fuel pool.

[0028] In various examples, the second end 220 is the lower end of the storage container 200. The second end 220 may be adapted to facilitate loading and unloading of the irradiation target into and out of the target irradiation device 100. For example, the second end 220 may be configured to include a plurality of through-holes 222 extending from the outer surface to the inner surface. The second end 220 may be adapted to connect to an irradiation target insert transport system. For example, the plurality of through-holes 222 may be configured to receive rabbet guide members. In some examples, the profile of each of the plurality of through-holes 222 is dimensioned to be substantially the same as or slightly larger than a rabbet guide tube.

[0029] In various examples, the body portion 230 may include a plurality of openings 232. Each of the plurality of openings 232 may be adapted to mate with a radiation shielding plug. The plurality of openings 232 may be distributed axially along the length of the body portion. In some examples, the plurality of openings 232 may be limited to be distributed within a portion of the length of the body portion 230. As shown in FIG. 1, the body portion 230 may optionally include a plurality of neutron generator supports 238 disposed on the inner surface of the body portion 230 to provide structural support to the inserted ENG insertion device 300.

[0030] The support member 240 is adapted to facilitate the insertion and removal of the irradiation target to the target irradiation device 100. For example, the support member 240 may include a plurality of channels 242 axially aligned with one of the plurality of through portions 222. In some examples, each of the plurality of channels 242 may be longitudinally oriented. In a particular example, each of the plurality of channels 242 has a cross-sectional shape that is substantially the same as or slightly larger than the cross-sectional shape of the irradiation target insert.

[0031] The support member 240 includes a first surface and a second surface. In various examples, the first surface of the support member 240 faces towards the inner surface of the second end portion 220, and the second surface of the support member 240 faces the first surface. In some examples, the first surface of the support member may face downward, and the second surface of the support member may face upward. The support member may also include at least one flow path 244 in fluid communication with the surrounding region of the support member. In some examples, the second surface may include at least one hole (not shown). In a particular embodiment, at least one flow path 244 is in fluid communication with at least one hole in the second surface.

[0032] In some examples, the storage container 200 may include a fluid inlet 234 and a fluid outlet 236, both of which provide fluid communication between the interior region of the storage container and the exterior region of the storage container. The fluid inlet 234 and the fluid outlet 236 may be adapted to removably couple to a coolant circulation system. In certain examples, the fluid inlet 234 and the fluid outlet 236 may be individual and may include pipe connection flanges. Other types of fluid connections are contemplated in the present disclosure. For example, in some embodiments, the fluid inlet and the fluid outlet may be individual and may include tube stubs, compression couplings, flare couplings, push-in couplings, quick-exchange couplings, straight or tapered threaded pipe couplings, bulkhead couplings, threaded pipe couplings, bayonet couplings, cam and groove couplings, or any other suitable reusable fluid coupling.

[0033] FIG. 2 shows a schematic cross-sectional view of a radial cross-section of a target irradiation device 100 according to at least one non-limiting aspect of the present disclosure. In some examples, the storage container 200 may be configured to have a cylindrical shape or other tubular shape. In a configuration where the storage container 200 has a cylindrical shape, a plurality of openings may be arranged such that ENG insertion devices 300 are provided at various radial positions, as shown in FIG. 2. Other configurations are contemplated in the present disclosure. For example, in some embodiments, the storage container 200 may be configured to have a cubic shape or a rectangular prism shape. In various examples, as shown in FIG. 1, the plurality of side openings 232 may be arranged at various axial positions.

[0034] FIG. 3 shows a perspective view of an ENG insertion device 300 according to at least one non-limiting aspect of the present disclosure. The plurality of ENG insertion devices 300 are each configured to be inserted into the opening 232.

[0035] In various examples, each of the plurality of ENG insertion devices 300 includes an electron neutron generation tube 302, a neutron moderation section 304 disposed within a storage container, a metal sheath (not shown) configured to surround the neutron moderation section 304, a radiation shielding plug section 306, and a power cable 308. In various examples, the electron neutron generation tube 302 may include deuterium, tritium, or a combination thereof. In some examples, the electron neutron generation tube has a length of about 30 inches or less. In some examples, the electron neutron generation tube has a diameter of about 7 inches or less.

[0036] In various examples, the neutron moderation section 304 includes a solid neutron moderation material. In some examples, the neutron moderation section 304 may include high density polyethylene. The thickness of the neutron moderation section may be configured to provide a desired thermal neutron flux output from the ENG insertion device. The metal sheath includes a material that substantially transmits thermal neutrons. In some examples, the metal sheath may comprise a thin layer of aluminum. The radiation shielding plug section 306 may include a material effective to reduce and / or eliminate the intensity of ionizing radiation outside the storage container. In some examples, the radiation shielding plug section 306 may include lead.

[0037] Referring now to FIGS. 1-2, the dimensions and / or shape of the ENG insertion device 300 may be configured such that the ENG insertion device 300 can be removably inserted and / or inserted into the opening 232. In various examples, the dimensions of the radiation shielding plug 306 are configured to be substantially the same as or slightly smaller than the side opening 232. The configuration of the ENG insertion device provides the advantage that the ENG insertion device can be easily repositioned, and the distribution of the neutron beam source can be optimized within the target irradiation device 100. For example, in some embodiments, the main body 230 may have a greater number of openings than the ENG insertion device, and multiple ENG insertion devices can be removed and repositioned until the neutron beam source is distributed as desired. In certain embodiments, the plurality of ENG insertion devices 300 may be arranged such that the neutron beam source is distributed along the fuel effective length of the used fuel assembly inserted into the removable neutron enhancement cartridge 400.

[0038] Referring further to FIGS. 1-2, the removable neutron enhancement cartridge 400 includes a cell structure 410. The cell structure 410 is adapted to be removably inserted into the storage container 200. For example, the dimensions and / or shape of the cell structure may be configured to be easily inserted and / or inserted between the ENG insertion devices 300 within the storage container 200. In various examples, the removable neutron enhancement cartridge 400 is configured to be disposed on the second surface of the support member 240 within the storage container 200 when inserted.

[0039] Referring to FIG. 4, a perspective view of a cell structure 410 according to at least one non-limiting aspect of the present disclosure is shown. The cell structure 410 includes a plurality of panels 420 configured to form one or more cell volumes 430. The dimensions and / or shape of each panel 420 may be configured to provide a desired arrangement and / or spacing of the cell volumes 430. In various examples, the plurality of panels 420 are arranged to form an array of cell volumes 430. In some examples, the plurality of panels 420 are arranged to form an array having a two-dimensional grid configuration as shown in FIG. 4. In an array configuration, the array may be dimensioned to accommodate a number of neutron multiplication assemblies suitable for receiving a neutron beam from a plurality of ENG insertion devices, thereby generating subcritical neutrons suitable for the commercial production of medical radioisotopes. For example, the two-dimensional grid may have individual integer dimensions A and B that form an array of A×B cell volumes 430, and each of A and B may be any integer greater than 1. In one example, the plurality of panels 420 are arranged to form an array of 17×17 cell volumes 430. Other array configurations are contemplated in the present disclosure. For example, in some embodiments, the plurality of panels 420 may be configured to form at least one uniform linear array, hexagonal array, circular array, or three-dimensional grid array.

[0040] Referring now to FIGS. 1-2 and 4, at least one of the one or more cell volumes 430 may be adapted such that a transport system for an irradiation target insert is accessible via a second end 220. For example, the arrangement of the cell volumes may be configured to axially align one cell volume 430 with one of the plurality of penetrations 222. In various examples, when inserting a removable neutron multiplication cartridge 400 into the storage container 200, at least one cell volume 430 may be arranged to be located at the center of one of the plurality of penetrations 222 and / or the channel 242. In some embodiments, the arrangement of the cell volumes is configured such that each of the penetrations 222 is accessible to the axial center of the cell volume.

[0041] The dimensions and / or shape of one or more cell volumes 430 may be configured such that the neutron augmentation assembly 440 can be easily inserted and / or placed into the one or more cell volumes 430. In various examples, the axial length of the one or more cell volumes 430 is configured to be substantially the same as or slightly longer than the axial length of the neutron augmentation assembly 440. In some examples, the axial length of the one or more cell volumes 430 is configured to be substantially the same as or slightly longer than the axial length of the spent fuel assembly. In a particular example, the axial length of at least one of the one or more cell volumes is configured to be about 12 feet. In various examples, the cross-sectional shape of the one or more cell volumes 430 is configured to be substantially the same as or slightly larger than the cross-sectional shape of the neutron augmentation assembly 440. In some examples, the cross-sectional shape of at least one of the one or more cell volumes 430 is configured to be substantially the same as or slightly larger than the cross-sectional shape of the spent fuel assembly. In a particular example, the projected cross-sectional shape of each of the one or more cell volumes 430 may be configured to fit within a square having sides of a length between 5 inches and 9 inches.

[0042] The removable neutron augmentation cartridge 400 may be adapted to couple with a transport system for the cartridge. For example, the cell structure 410 may include a mechanical interface configured to provide a releasable connection with a handling tool. In a particular example, the removable neutron augmentation cartridge 400 may include a coupling member that interlocks with a lifting tool for a spent fuel assembly. In one example, the removable neutron augmentation cartridge 400 includes a coupling member that interlocks with a grapple.

[0043] The configuration of the cell structure 410 can optimize the logistic and safety issues associated with the replacement of the neutron multiplication cartridge. For example, in certain embodiments, the existing equipment of the spent fuel pool in the storage facility can be used to move the cell structure 410 equipped with a coupling member that interlocks with the lifting tool for the spent fuel assembly while remaining safely submerged. Also, a spare cell structure submerged in the spent fuel pool of the storage facility can be loaded with the spent fuel assemblies in that spent fuel pool to store an inventory of pre-loaded and immediately usable neutron multiplication cartridges. Therefore, without losing the inherent safety advantage of performing operations while submerged, the time required between removing the neutron multiplication cartridge 400 from the submerged storage container and inserting the pre-loaded neutron multiplication cartridge into the storage container can be minimized.

[0044] The removable neutron multiplication cartridge 400 is adapted to generate a neutron flux that is proportionally larger than the neutron flux provided by the ENG insertion device 300. For example, at least one neutron multiplication assembly 440 may include a neutron multiplication material configured to provide subcritical multiplication of neutrons. In various examples, at least one neutron multiplication assembly 440 may include spent nuclear fuel. In some examples, at least one neutron multiplication assembly 440 includes a spent fuel assembly having a K ∞ value of less than 1. In a particular example, at least one neutron multiplication assembly 440 includes a spent fuel assembly having a K ∞ value of 0.99 or less.

[0045] The K of the array of fuel assemblies eff can be determined by known methods using the infinite multiplication factor K ∞ of a particular fuel assembly in the array, and the multiplication factor K ∞ represents the upper limit of the neutron multiplication factor of the particular fuel assembly. K effIn the subcritical state where it is less than 1, the subcritical multiplication mechanism multiplies the subcritical multiplication factor M through the fission interaction between the neutron flux source N and the nuclear fission interaction between the neutron source and the array of fissile fuel assemblies, and the fuel assembly neutron flux N A is brought about. TIFF2025522448000002.tif22170

[0046] The configuration of the neutron multiplication cartridge 400 can provide the advantage of operating safety without relying on the complex control of nuclear reactions. For example, K ∞ Since an array of spent fuel assemblies with K less than 1 cannot generate neutrons by a self-sustaining nuclear fission reaction, K ∞ The neutron multiplication cartridge 400 equipped with an array of spent fuel assemblies with K less than 1 stops generating neutrons immediately when the power of the ENG insertion device 300 is turned off.

[0047] When the power of a plurality of ENG insertion devices 300 is turned on, the thermal neutron flux generated by the ENG insertion device interacts with the neutron multiplication material of the inserted neutron multiplication cartridge. For example, about 10 9 neutrons / cm 2 / second order of incident thermal neutron flux interacts with an array of spent fuel assemblies with K ∞ being 0.99 to generate a multiplied neutron flux of about 10 11 neutrons / cm 2 / second order.

[0048] The neutron multiplication assembly 440 may include an axial flow path that terminates at a coolant inlet at a first end and at a coolant outlet at a second end. In various configurations, the first end of the neutron multiplication assembly 440 is disposed to face the support member 240, and the second end of the neutron multiplication assembly is disposed at a position closest to the first end 210. The target irradiation device 100 may be adapted to flow a coolant through the neutron multiplication assembly 440. For example, in some embodiments, the support member 240 may include at least one hole disposed within the boundary of at least one cell volume that houses the neutron multiplication assembly 440 configured to have an axial flow path. Advantageously, this configuration provides fluid communication between the flow path 244 and the coolant outlet at the second end of the neutron multiplication assembly 440. Thus, when a coolant circulation system is connected to a storage container configured to have a fluid inlet 234 and a fluid outlet 236, coolant can be supplied from the fluid inlet 234 to the coolant inlet of the neutron multiplication assembly 440, and the coolant exiting the coolant outlet of the neutron multiplication assembly 440 can be recovered at the fluid outlet 236.

[0049] In certain embodiments, the target irradiation device 100 can provide the advantage of generating a thermal neutron flux sufficient to commercially produce medical radioisotopes without sacrificing availability and / or safety. For example, since the neutron multiplication assembly 440 may be configured as a spent fuel assembly, a removable neutron multiplication cartridge 400 can be remotely loaded within a spent fuel pool that provides easy and / or safe access to the spent fuel assembly away from an operating nuclear reactor, thereby avoiding perturbation of the state of the operating nuclear reactor and the associated risks. Further, in some embodiments, if too much heat is generated within the target irradiation device, an undesirable heat progression state can be mitigated simply by turning off the power of the plurality of ENG insertion devices 300 and / or by introducing coolant into the target irradiation device.

[0050] Referring now to FIGS. 1 - 3, at least one neutron multiplication assembly 440 includes an internal housing 442. The internal housing 442 is adapted to accommodate an irradiation target insert. For example, the dimensions and / or shape of the internal housing 442 may be configured to be substantially the same as or slightly longer than the axial length of the irradiation target insert. In various examples, the axial length of the internal housing 442 is configured to extend from a first axial end of the neutron multiplication assembly 440 to a region within the neutron multiplication assembly. In some examples, the cross-sectional shape of the internal housing 442 is configured to be substantially the same as or slightly larger than the cross-sectional shape of the irradiation target insert. In a particular example, the internal housing 442 is the insertion sleeve of a spent fuel assembly.

[0051] In some examples, when an irradiation target insert is inserted into the internal housing 442, the neutron flux provided by at least one neutron multiplication assembly 440 interacts with the material of the irradiation target insert to produce a medical radioisotope. For example, when the plurality of ENG insertion devices 300 are powered on, an irradiation target insert containing molybdenum 98 disposed within the internal housing 442 may be irradiated with a neutron flux sufficient to produce molybdenum 99.

[0052] The inner housing 442 may be adapted to optimize the movement of the irradiation target insert. For example, one inner housing 442 may be positioned to align with one of the plurality of channels 242. In various examples, at least one inner housing 442 of the inserted removable neutron multiplication cartridge 400 is axially aligned with one of the plurality of channels 242. In some embodiments, the axial alignment of the inner housing 442 with one of the plurality of channels 242 provides an inlet path and / or an outlet path for the irradiation target insert through one of the plurality of through-holes 222 that is axially aligned with the said one of the plurality of channels 242, so that the irradiation target insert can be inserted into and removed from the neutron multiplication cartridge 400 without the need to disassemble the target irradiation device 100, providing the advantage.

[0053] Referring to FIG. 5, a schematic diagram of a panel 420 according to at least one non-limiting aspect of the present disclosure is shown. Each of the panels 420 includes an outer metal shell 422. In various examples, the outer metal shell 422 may include a material that is transmissive to ionizing radiation. In some examples, the outer metal shell 422 may include aluminum.

[0054] Each of the plurality of panels 420 may be adapted to slow down fast neutrons and / or absorb gamma rays in order to provide a thermal neutron flux. For example, the panel may be configured to include a neutron moderation material, a photoneutron source, or a combination thereof. In various examples, the panel 420 may include carbon and / or beryllium. In some examples, the panel 420 may include graphite. In some panel configurations, the outer metal shell 422 may house a filling mixture 424 that includes graphite and beryllium, as shown in FIG. 5. In certain examples, the filling mixture 424 may be sealed.

[0055] Due to the configuration of panel 420, the subcritical multiplication efficiency during the operation of the target irradiation device 100 can be increased. For example, in some examples, panel 420 can convert any incident fast neutrons and / or incident gamma rays from neutron multiplication assembly 440 into an incident thermal neutron beam.

[0056] FIG. 6 shows a schematic view of a radioisotope production system 1000 including a neutron multiplication device 1100, at least one removable neutron multiplication cartridge 1400, and a detachable transport system 1500, according to at least one non-limiting aspect of the present disclosure. The neutron multiplication device 1100 includes a storage container 1200 having an inner surface and an outer surface, and a plurality of electron neutron generator insertion devices 1300. The storage container 1200 is similar in many respects to other storage devices disclosed elsewhere in the present disclosure and will not be repeatedly described here at the same level of detail for the sake of brevity. In various examples, the storage container 1200 includes an upper end, a lower end having a plurality of longitudinally oriented openings extending from the outer surface to the inner surface, and a body portion extending longitudinally between the upper end and the lower end, the body portion having a plurality of side openings, each of the plurality of side openings being adapted to mate with a radiation shielding plug, a body portion, and a lower support member (not shown) disposed on the inner surface above the lower end, the lower support member having a plurality of longitudinally oriented channels, the longitudinally oriented channels being aligned with the longitudinally oriented openings of the lower end, and a lower support member. In some examples, the upper end may include a removable container lid, and the lower end may be adapted to be reversibly coupled to the detachable transport system 1500. In various examples, as shown in FIG. 6, each of the plurality of electron neutron generator insertion devices 1300 is inserted laterally into each of the plurality of side openings of the storage container 1200. The storage container 1200 may optionally include a first fluid port and a second fluid port, both of which are adapted to be removably coupled to a coolant circulation system.

[0057] The radioactive isotope production system 1000 may optionally include a coolant circulation system 1600 removably connected to the first fluid port and the second fluid port of the storage container 1200. The coolant circulation system 1600 is adapted to remove excess heat from the neutron multiplication cartridge 1400 inserted into the storage container 1200. For example, the coolant circulation system may be configured to have a cold side that supplies a boron-based coolant to the first fluid port of the storage container 1200 and a hot side that recovers the coolant from the second fluid port of the storage container 1200. In some examples, when at least one removable neutron multiplication cartridge 1400 is inserted into the storage container 1200, the storage container 1200 is adapted to direct at least a portion of the coolant supplied to the first fluid port to pass through at least one removable neutron multiplication cartridge 1400.

[0058] Referring further to FIG. 6, at least one removable neutron multiplication cartridge 1400 includes a cell structure having an array of cell volumes and may be configured similarly to the neutron multiplication cartridge 400 described above herein. Accordingly, at least one removable neutron multiplication cartridge 1400 may be adapted to be mounted to a lower support member within the storage container 1200 and may accommodate a neutron multiplication assembly and / or an irradiation target insert so as to align with one of a plurality of longitudinally oriented channels of the lower support member. In some embodiments, each cell volume of the neutron multiplication cartridge 1400 may be configured to be in fluid communication with the first fluid port and the second fluid port of the storage container 1200.

[0059] The configuration of the removable neutron multiplier cartridge 1400 can minimize any exchange delay and / or associated safety issues. For example, in some embodiments, spare neutron multiplier cartridges may be individually submerged in the spent fuel pool of a storage facility for spent fuel assemblies, the spent fuel assemblies may be loaded, and an inventory of pre-loaded neutron multiplier cartridges may be stocked. When the irradiation target device is submerged in the spent fuel pool, the storage container that requires replacement of the neutron multiplier cartridge can be quickly unloaded and reloaded, thus minimizing exposure to ionizing radiation from the fuel assemblies during storage. And / or, the accumulation of downtime during replacement can be minimized, and the time available for target irradiation can be obtained. Thus, the configuration of the removable neutron multiplier cartridge 1400 can optimize the safety and logistics of commercial-scale production of medical radioisotopes.

[0060] The detachable transfer system 1500 includes at least one transfer member 1510. In various examples, each of the at least one transfer member 1510 is reversibly coupled to each of a plurality of longitudinally oriented openings of the storage container 1200. The transfer member 1510 may be adapted to guide the irradiation target insert into and / or out of at least one removable neutron multiplication cartridge 1400 when inserting the at least one removable neutron multiplication cartridge 1400 into the storage container 1200. For example, the transfer member 1510 may be a guide tube having a cross-sectional shape slightly larger than the cross-sectional shape of the irradiation target insert. The detachable transfer system 1500 may be configured to pneumatically or mechanically transfer the irradiation target insert. In various examples, the detachable transfer system 1500 is cable-driven. In some examples, the detachable transfer system 1500 may include a cable drive assembly adapted to mechanically couple to a first end of the irradiation target insert. In a particular example, the cable drive assembly is adapted to traverse a path axially aligned with the transfer member 1510.

[0061] When attaching and detaching the transfer system 1500 to the radioisotope production system 1000 submerged in the spent fuel pool, liquid may enter the plurality of longitudinally oriented openings and / or the transfer member 1510. The configuration of the detachable transfer system 1500 can provide the advantage of being able to quickly and reliably recover the irradiated target insert by providing for quick connection and / or disconnection with the storage container 1200 without relying on maintaining a closed gas loop. For example, in a cable drive configuration, the transfer system 1500 can provide the force necessary to overcome obstacles associated with slight misalignment and / or liquid ingress that are difficult to correct with conventional pneumatic systems.

[0062] As described above in this specification, the advantages provided by the configuration of the radioisotope production system 1000 can optimize the technical and economic aspects of medical radioisotope production, such as, for example, accessibility to the high-energy neutron beam source for irradiating the target insert, efficient recovery of the irradiated target, and operational safety.

[0063] As described in this specification, the radioisotope production system 1000 may be incorporated into a production method. For example, a method for producing a radioisotope source may include initializing the radioisotope production system and producing the radioisotope source. The initialization step may include submerging a first neutron multiplication cartridge into the spent fuel pool, loading at least one spent fuel assembly into the first neutron multiplication cartridge, submerging the open radioisotope production system into the spent fuel pool, where the open radioisotope production system includes an array of ENG insertion devices, loading the first neutron multiplication cartridge that has just been loaded into the submerged radioisotope production system, closing the loaded radioisotope production system, and inserting an irradiation target into the closed radioisotope production system. The production step of the method may include supplying power to the array of ENG insertion devices to irradiate the inserted irradiation target, and withdrawing the irradiation target from the closed radioisotope production system to produce a radioisotope source. The method for producing radioisotopes can be adapted to various applications. For example, the method for producing radioisotopes may be adapted to the production of short-lived medical radioisotopes.

[0064] The first neutron multiplication cartridge may have a neutron multiplication factor K eff partially based on the configuration of the loaded first neutron multiplication cartridge. For example, the discharge burnup and final placement of at least one spent fuel assembly are for the desired neutron multiplication factor K effIt may be configured to obtain a loaded first neutron multiplication cartridge having. In some examples, the just-loaded first neutron multiplication cartridge has a neutron multiplication factor K less than 1 eff It may have. In a particular example, the neutron multiplication factor K eff Is a K less than 1 ∞ Rate included. A neutron multiplication cartridge having a K less than 1 ∞ Since it is essentially limited to subcritical neutron multiplication, the radioisotope production system used in the manner described above in this specification may be configured to generate a neutron flux according to the flux provided by the array of ENG insertion devices, thereby avoiding neutron multiplication running out of control during startup and neutrons continuing to be generated after shutdown. Thus, the method of producing a radioisotope source can provide the advantage that the process can be quickly started up and / or stopped without compromising safety by providing a neutron flux limited to subcritical multiplication of the neutron flux generated by the array of ENG insertion devices.

[0065] The method of producing a radioisotope source involves submerging a second neutron multiplication cartridge and loading the second neutron multiplication cartridge to have a K substantially the same as that of the just-loaded first neutron multiplication cartridge effGenerating a freshly loaded second neutron multiplication cartridge, opening a submerged and closed radioactive isotope production system, and exchanging the first neutron multiplication cartridge with the freshly loaded second neutron multiplication cartridge may additionally be included. In some embodiments, these additional steps can minimize the delay that can occur during neutron multiplication cartridge exchange. Further, when it is desired to extend the radioactive isotope production schedule after production has started, a spare neutron multiplication cartridge can be prepared in anticipation of the end of the life of the last cartridge according to the previous schedule. Thus, this method can provide the advantage of optimizing the production schedule by shortening the overall production time and / or flexibly extending the production schedule.

[0066] If the demand for the radioactive isotope source changes during the production of the radioactive isotope source, by using the radioactive isotope production system in the method for producing the radioactive isotope source as described above in this specification, the radioactive isotope source can be produced quickly and reliably without sacrificing production flexibility, thereby avoiding the economic and / or safety problems associated with conventional methods for producing radioactive isotopes.

[0067] Various aspects of the invention according to the present disclosure include, but are not limited to, the aspects listed in the following numbered clauses. 1. A target irradiation device for producing a radioactive isotope source, the target irradiation device comprising A storage container having an inner surface and an outer surface, the storage container comprising A first end, A second end having a plurality of through-holes extending from the outer surface to the inner surface and adapted to be coupled to a transport system for an irradiation target insert, A body portion extending between an upper end and a lower end and having a plurality of openings, each of the plurality of openings being adapted to mate with a radiation shielding plug, the body portion, A support member having a plurality of channels, the channels being aligned with the through portions of the second ends, and the first surface of the support member facing the inner surface of the second ends, the support member, and a storage container comprising the same. A plurality of electron neutron generator insertion devices, each of the electron neutron generator insertion devices being inserted into a plurality of openings respectively, the plurality of electron neutron generator insertion devices. A removable neutron multiplication cartridge disposed on the second surface of the support member, the neutron multiplication cartridge comprising: A cell structure having a plurality of panels, the plurality of panels being configured to form at least one cell volume, and each of the plurality of panels comprising an outer metal shell, the cell structure. A neutron multiplication assembly configured to be removably inserted into at least one cell volume and adapted to accommodate an irradiation target insert so as to be aligned with one of the plurality of channels of the support member, the neutron multiplication cartridge comprising the neutron multiplication assembly, and a target irradiation device. 2. Each of the plurality of electron neutron generator insertion devices comprises: An electron neutron generation tube; A neutron moderation section; A metal sheath configured to surround the neutron moderation section; A radiation shielding plug section; A power cable, the target irradiation device of item 1. 3. The target irradiation device of item 2, wherein the electron neutron generation tube contains deuterium, tritium, or a combination thereof. 4. The target irradiation device according to any one of items 2 to 3, wherein the neutron moderation section contains high density polyethylene. 5. The target irradiation device according to any one of items 2 to 4, wherein the metal sheath contains aluminum. 6. The target irradiation device according to any one of items 2 to 5, wherein the radiation shielding plug section contains lead. 7. The target irradiation device according to any one of items 1 to 6, wherein the outer metal shell of each of the plurality of panels contains a material with low thermal neutron absorptivity. 8. The target irradiation device according to item 7, wherein the material with low thermal neutron absorptivity contains aluminum. 9. The target irradiation device according to any one of items 1 to 7, wherein each of the plurality of panels is filled with a mixture containing a neutron moderating material and a photo-neutron sensitive material. 10. The target irradiation device according to item 9, wherein the neutron moderating material contains carbon. 11. The target irradiation device according to item 9, wherein the photo-neutron sensitive material contains beryllium. 12. The target irradiation device according to any one of items 1 to 11, wherein the neutron multiplication assembly contains a subcritical multiplication material. 13. The target irradiation device according to item 12, wherein the neutron multiplication assembly is a spent fuel assembly. 14. The target irradiation device according to any one of items 1 to 12, wherein the containment vessel has a fluid inlet and a fluid outlet, each neutron multiplication has an axial flow path, and the support member has at least one flow path that is in fluid communication with the axial flow path of each neutron multiplication and the fluid inlet of the containment vessel. 15. A radioisotope production system for producing a radioisotope source, the radioisotope production system comprising: A neutron multiplication device, A containment vessel having an inner surface and an outer surface, An upper end portion having a removable vessel lid, A lower end portion having a plurality of longitudinally oriented openings extending from the outer surface to the inner surface and adapted to be coupled to a transport system for an irradiation target insert, A main body portion extending longitudinally between the upper end portion and the lower end portion and having a plurality of side openings, each of the plurality of side openings being adapted to fit a radiation shielding plug, the main body portion; A lower support member disposed on the inner surface above the lower end portion and having a plurality of longitudinally oriented channels, the longitudinally oriented channels being aligned with the longitudinally oriented openings of the lower end portion, the lower support member; a containment vessel comprising; A plurality of electron neutron generator insertion devices, each of the electron neutron generator insertion devices being inserted laterally into each of the plurality of side openings, the neutron multiplication device comprising the plurality of electron neutron generator insertion devices. At least one removable neutron multiplication cartridge adapted to be attached to a lower support member within a storage container of at least one neutron multiplication device, the at least one removable neutron multiplication cartridge comprising a cell structure having an array of cell volumes, each of the cell volumes being configured to receive a neutron multiplication assembly, the neutron multiplication assembly being adapted to receive an irradiation target insert so as to be aligned with one of a plurality of longitudinally oriented channels of the lower support member, the neutron multiplication cartridge; A radioactive isotope production system comprising a removable irradiation target insert transport system adapted to move an irradiation target through a lower end of the storage container. 16. The radioactive isotope production system of item 15, wherein the transport system comprises a cable drive assembly comprising a cable, and an end of the cable is adapted to removably attach the cable to the irradiation target insert. 17. The storage container includes a first fluid port and a second fluid port, the first fluid port and the second fluid port being adapted to be removably connected to a coolant circulation system, and a plurality of cell volumes being adapted to receive a liquid flow from the first fluid port and flow the liquid flow to the second fluid port. The radioactive isotope production system according to any one of items 15 to 16. 18. A method for producing a radioactive isotope source, comprising: Initializing a radioactive isotope production system; Submerging a first neutron multiplication cartridge in a spent fuel pool; Loading at least one spent fuel assembly into the first neutron multiplication cartridge, the freshly loaded first neutron multiplication cartridge having a neutron multiplication factor K eff Having, loading; Submerging an open radioactive isotope production system comprising an array of electron neutron generator insertion devices in a spent fuel pool; Loading a first neutron multiplication cartridge just loaded into a submerged radioisotope production system, Closing the loaded radioisotope production system, Inserting an irradiation target into the closed radioisotope production system, including initializing the radioisotope production system, Producing a radioisotope source, Supplying power to an array of electron neutron generator insertion devices to irradiate the inserted irradiation target, Withdrawing the irradiated target from the closed radioisotope production system to produce a radioisotope source, including producing a radioisotope source, a method comprising. 19. Neutron multiplication factor K eff Is less than 1, the method for producing a radioisotope source according to item 18. 20. Submerging a second neutron multiplication cartridge, Loading the second neutron multiplication cartridge to produce a just-loaded second neutron multiplication cartridge having substantially the same K eff As the just-loaded first neutron multiplication cartridge, Opening the closed radioisotope production system that is submerged, Replacing the first neutron multiplication cartridge with the just-loaded second neutron multiplication cartridge, the method for producing a radioisotope source according to any one of items 18 to 19.

[0068] In this specification, various features and characteristics have been described to provide an understanding of the structure, production, function, and / or operation of the present invention, including the disclosed methods and systems. It is understood that the various features and characteristics of the present invention described herein can be arbitrarily and appropriately combined regardless of whether such features and characteristics are explicitly described in combination in this specification. The inventors and applicants explicitly intend that such combinations of features and characteristics are included within the scope of the invention described herein. Therefore, the claims can be amended to describe any combination of the features and characteristics explicitly or essentially described in this specification, or the features and characteristics explicitly or essentially incorporated by reference herein. Further, the applicant reserves the right to amend the claims to affirmatively deny any features or characteristics that may exist in the prior art even if those features and characteristics are not explicitly described in this specification. Accordingly, such amendments do not add new matter to the specification or the claims, but are in accordance with the specification, the sufficiency of the specification, and the requirements for additional matter.

[0069] Regarding the appended claims, those skilled in the art will understand that the operations described therein may generally be performed in any order. Also, although various operation flows are shown in order, it should be understood that these various operations may be performed in an order other than the described order or simultaneously. Unless otherwise indicated by the context, examples of such alternative orders include overlapping order, interleaved order, interrupted order, reordered order, incremental order, preparatory order, supplementary order, simultaneous order, reverse order, or other modified orders. Further, words such as "corresponding to," "related to," or other past participle adjectives generally do not intend to exclude such modifications unless otherwise indicated by the context.

[0070] The invention described in this specification may comprise, consist of, or consist essentially of the various features and characteristics described herein. The terms "comprise" (and any form of "comprise" such as "comprised", "comprising"), "have" (and any form of "have" such as "had", "having"), "include" (and any form of "include" such as "included", "including"), and "contain" (and any form of "contain" such as "contained", "containing") are open-ended conjunctive verbs. Thus, a method or system that "comprises", "has", "includes", or "contains" one or more features and / or characteristics has those one or more features and / or characteristics, but is not limited to having only those one or more features and / or characteristics. Similarly, an element of a composition, coating, or process that "comprises", "has", "includes", or "contains" one or more features and / or characteristics has those one or more features and / or characteristics, but is not limited to having only those one or more features and / or characteristics and may have additional features and / or characteristics.

[0071] As used in this specification, including the claims, the singular forms of the grammatical articles “a,” “an,” and “the” are intended to include “at least one” or “one or more,” unless the context clearly dictates otherwise. Thus, in this specification, these articles are used to refer to one or more (i.e., “at least one”) of the grammatical objects of the article. By way of example, “a component” means one or more components, and thus one or more components may be contemplated and one or more components may be employed or used in the practice of the described compositions, coatings, and processes. Nevertheless, it is understood that the use of the phrase “at least one” or “one or more” in some instances and not in others does not result in an interpretation that limits the object of the grammatical articles “a,” “an,” and “the” to only one. Further, the use of singular nouns includes the plural, and the use of plural nouns includes the singular.

[0072] In this specification, unless otherwise indicated, all numerical parameters should be understood to be prefaced and modified by the term “about” in all instances. In this case, the numerical parameters have the variability inherent in the basic measurement techniques used to determine the parameter's value. At a minimum, and not to limit the application of the doctrine of equivalents to the claims, each numerical parameter set forth in this specification should be construed in light of at least the number of reported significant digits and by applying ordinary rounding techniques.

[0073] Every numerical range described herein includes all sub-ranges subsumed within the described range. For example, the range “1 to 10” includes all sub-ranges between (and including) the described minimum value “1” and the described maximum value “10”, i.e., all sub-ranges where the minimum value is 1 or greater and the maximum value is 10 or less. Also, all ranges described herein include the endpoints of the described range. For example, the range “1 to 10” includes the endpoints 1 and 10. The maximum numerical limitations described herein are intended to include all sub-numerical limitations subsumed therein, and the minimum numerical limitations described herein are intended to include all super-numerical limitations subsumed therein. Accordingly, Applicant reserves the right to correct this specification, including the claims, to expressly recite any sub-range subsumed within the explicitly recited ranges. All such ranges are in essence described herein.

[0074] As used herein, especially when used with respect to a layer, the terms “on”, “above”, “onto” and their variations (e.g., “applied on”, “formed on”, “disposed on”, “provided on”, “located on”, etc.) mean being applied, formed, disposed, provided or located on the surface of a substrate, but not necessarily in contact with the surface of the substrate. For example, a layer “applied on” a substrate does not preclude the presence of one or more additional layers of the same or different composition between the applied layer and the substrate. Similarly, a second layer “applied on” a first layer does not preclude the presence of one or more additional layers of the same or different composition between the applied second layer and the applied first layer.

[0075] Having thus described specific examples of the invention for purposes of illustration, it will be apparent to those skilled in the art that numerous modifications to the details of the invention may be made without departing from the invention as set forth in the appended claims.

Claims

1. A target irradiation device for producing a radioisotope source, the target irradiation device comprising: A storage container having an inner surface and an outer surface, A first end and A second end adapted to be coupled to a transport system for an irradiation target insert, the second end having a plurality of through-holes extending from the outer surface to the inner surface; A body portion extending between the upper end and the lower end and having a plurality of openings, each of the plurality of openings being adapted to mate with a radiation shielding plug; A support member having a plurality of channels, the channels being aligned with the through-holes of the second end, the first surface of the support member facing the inner surface of the second end; A plurality of electron neutron generator insertion devices, each of the electron neutron generator insertion devices being inserted into a respective one of the plurality of openings; A removable neutron multiplier cartridge disposed on a second surface of the support member, A cell structure having a plurality of panels, the plurality of panels being configured to form at least one cell volume, each of the plurality of panels having an outer metal shell; A neutron multiplier assembly configured to be removably inserted into the at least one cell volume and adapted to receive an irradiation target insert in alignment with one of the plurality of channels of the support member;

2. Each of the plurality of electron neutron generator insertion devices comprises: An electron neutron generation tube, A neutron moderation section, A metal sheath configured to surround the neutron moderation section, A radiation shielding plug section, and A power cable.

3. The target irradiation device according to claim 2, wherein the electron neutron generation tube contains deuterium, tritium, or a combination thereof.

4. The target irradiation device according to any one of claims 2 to 3, wherein the neutron moderation section contains high density polyethylene.

5. The target irradiation device according to any one of claims 2 to 4, wherein the metal sheath contains aluminum.

6. The target irradiation device according to any one of claims 2 to 5, wherein the radiation shielding plug section contains lead.

7. The target irradiation device according to any one of claims 1 to 6, wherein each of the outer metal shells of the plurality of panels contains a material having low thermal neutron absorptivity.

8. The target irradiation device according to claim 7, wherein the material having low thermal neutron absorptivity contains aluminum.

9. The target irradiation device according to any one of claims 1 to 8, wherein each of the plurality of panels is filled with a mixture containing a neutron moderating material and a photoneutron sensitive material.

10. The target irradiation device according to claim 9, wherein the neutron moderating material contains carbon.

11. The target irradiation device according to any one of claims 9 to 10, wherein the photoneutron sensitive material contains beryllium.

12. The target irradiation device according to any one of claims 1 to 11, wherein the neutron multiplication assembly contains a subcritical multiplication material.

13. The target irradiation device according to claim 12, wherein the neutron multiplication assembly is a spent fuel assembly.

14. The storage container includes a fluid inlet and a fluid outlet, each of the neutron multiplications includes an axial flow path, The target irradiation device according to any one of claims 1 to 13, wherein the support member includes at least one flow path that is in fluid communication with the axial flow path of each of the neutron multiplications and the fluid inlet of the storage container.

15. A radioisotope production system for producing a radioisotope source, the radioisotope production system comprising a neutron multiplication device, a storage container having an inner surface and an outer surface, an upper end portion having a removable container lid, a lower end portion having a plurality of longitudinally oriented openings extending from the outer surface to the inner surface and adapted to be coupled to a removable transport system for an irradiation target insert, a main body portion extending longitudinally between the upper end portion and the lower end portion and having a plurality of side openings, each of the plurality of side openings being adapted to mate with a radiation shielding plug, the main body portion, a lower support member disposed on the inner surface above the lower end portion and having a plurality of longitudinally oriented channels, the longitudinally oriented channels being aligned with the longitudinally oriented openings of the lower end portion, the lower support member, and a storage container comprising. A plurality of electron neutron generator insertion devices, each of the electron neutron generator insertion devices being inserted into a respective one of the plurality of side openings, and a neutron multiplication device comprising the same, At least one removable neutron enhancement cartridge adapted to be attached to the lower support member within the storage container of the at least one neutron multiplication device, A cell structure comprising an array of cell volumes, each of the cell volumes being configured to accommodate a neutron enhancement assembly, the neutron enhancement assembly being adapted to accommodate an irradiation target insert so as to align with one of the plurality of longitudinally oriented channels of the lower support member, and at least one removable neutron enhancement cartridge comprising the cell structure, A radioactive isotope production system comprising a removable transport system for an irradiation target insert, the transport system being adapted to move the irradiation target through the lower end of the storage container.

16. The removable transport system comprises a cable drive assembly comprising a cable, The radioactive isotope production system according to claim 15, wherein an end of the cable is adapted to removably attach the cable to the irradiation target insert.

17. The storage container includes a first fluid port and a second fluid port, The first fluid port and the second fluid port are adapted to be removably connected to a coolant circulation system, The radioactive isotope production system according to any one of claims 15 to 16, wherein the plurality of cell volumes are adapted to receive a liquid flow from the first fluid port and direct the liquid flow to the second fluid port.

18. A method for producing a radioactive isotope source, the production method comprising: Initializing a radioactive isotope production system, Submerging a first neutron enhancement cartridge in a spent fuel pool, Loading at least one spent fuel assembly into the first neutron multiplication cartridge, wherein the just-loaded first neutron multiplication cartridge has a neutron multiplication factor K ｅｆｆ and performing the loading Submerging in the spent fuel pool an open radioactive isotope production system comprising an array of electron neutron generator insertion devices, Loading the first neutron enhancement cartridge, which has just been loaded, into the radioactive isotope production system that has been submerged, Closing the loaded radioactive isotope production system, Initializing a radioisotope production system, including inserting an irradiation target into the radioisotope production system in a closed state; Producing a radioisotope source, comprising: Supplying power to the array of the electron neutron generator insertion device to irradiate the inserted irradiation target; A method for producing a radioisotope source, comprising: producing a radioisotope source, including withdrawing the irradiated target from the radioisotope production system in a closed state to produce the radioisotope source.

19. The neutron multiplication factor K ｅｆｆ The method for producing a radioisotope source according to claim 18, wherein ｅｆｆ is less than 1.

20. Submerging a second neutron multiplication cartridge; Load the second neutron multiplication cartridge to produce a freshly loaded second neutron multiplication cartridge having substantially the same K as the freshly loaded first neutron multiplication cartridge ｅｆｆ as that of the freshly loaded first neutron multiplication cartridge, and Opening the radioisotope production system in a submerged and closed state; The method for producing a radioisotope source according to any one of claims 18 to 19, comprising replacing the first neutron multiplication cartridge with the second neutron multiplication cartridge just loaded.

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