Method and system for producing isotopes

Abstract

A system and method for producing radioisotopes, such as molybdenum-99. The system includes a first accelerator, a second accelerator, a first beamline, and a target. Using a pair of accelerators, the beamlines preferably fire in opposite directions toward the target, thereby irradiating the target from both sides. The system may further include a target cooling system utilizing gaseous helium, a modular local target shield consisting of a box of either metal shot with liquid coolant or steel with concrete, and a hot cell for loading and unloading the target disk.

Description

[Background technology]

[0001] [Citation of Related Applications] This application claims benefit of the filing dates of U.S. Provisional Patent Application No. 63 / 066,897, entitled "Method and System for Producing Molybdenum-99," filed August 18, 2020, and U.S. Provisional Patent Application No. 63 / 086,488, entitled "Method and System for Producing Molybdenum-99," filed October 1, 2020, both of which are incorporated by reference in their entireties.

[0002] Radioisotopes (in the fields of medicine and life science, "radioisotopes" are often called "radioisotopes" and "isotopes" are often called "isotopes," so in this specification, the latter terms will be used) are widely used in medicine and life science. The usefulness and commercial value of radioisotopes are determined in part based on their specific radioactivity, and a high specific activity means that they have widespread utility and are of great value.

[0003] Artificial isotopes are typically produced by electron beam, ion beam, and nuclear reactor methods. Electron beams are generally used to produce short-lived isotopes near the site of use. Ion beams and nuclear reactors are generally used to produce longer-lived isotopes in central facilities.

[0004] Many isotopes can be readily produced by all three techniques, including isotopes made by either neutron enrichment or depletion of a naturally occurring target isotope.

[0005] Ion beam processing has been the method of choice for neutron reduction due to its relatively high energy efficiency. However, ion beam processing suffers from its high initial cost, complex operation, and limited ability to scale to mass production rates. In addition, the relatively large mass of ions makes it extremely difficult to generate high current density beams. Furthermore, the deposition distance of ion energy is extremely short, thus resulting in intense local target heating, and sharply focused beams inevitably destroy the target. These factors limit the average specific activity achievable with ion beams and limit the production volume and quality.

[0006] The stopping distance of an electron beam is significantly longer than that of an ion beam. However, an electron beam can only form radioisotopes if it can generate photons in or near the target. Furthermore, to generate the photon intensity necessary to produce a high specific activity of the radioisotope, a high electron beam power density is required, which typically imposes an unacceptably high heat load on the target material, resulting in target melting. This again limits production volume and production quality.

[0007] Fission reactors compete with beam sources for the production of isotopes through the neutron absorption process and play a unique role in producing isotopes that are separated from the fission products. Fission reactors are currently the method of choice for neutron augmentation because of their ability to produce large quantities of product.

[0008] Molybdenum-99 (Mo-99 or aMO) is an important medical isotope used to produce technetium-99m (Tc-99m), which is used in approximately 80 percent of medical imaging procedures in the United States, or approximately 50,000 procedures per day.

[0009] Today, the majority of Mo-99 feedstock used in industry is produced in nuclear fission reactors. Molybdenum-98 (Mo-98), the naturally occurring molybdenum (nMO) isotope with the highest natural abundance and most commercial application, is bombarded with neutrons using neutron capture to produce Mo-99. NorthStar Medical Radioisotopes, LLC, the first U.S. supplier to receive FDA approval for Mo-99 production since the 1980s, is currently producing Mo-99 using neutron capture in partnership with the University of Missouri Research Reactor.

[0010] However, there are many drawbacks to using nuclear reactors to produce medical isotopes. Nuclear reactors are extremely expensive, costly to operate, and subject to extremely strict siting and operational constraints under federal regulations. Therefore, there continues to be a need for an inexpensive means of producing Mo-99 without the need for a nuclear reactor.

[0011] Alternatively, the production of Mo-99 using neutron emission methods was investigated by Lidsky et al. at the Massachusetts Institute of Technology in the 1990s. U.S. Patent No. 5,784,423 (Lidsky, entitled "Method of Producing Molybdenum-99") discloses a method for producing Mo-99 using a single electron accelerator, and is incorporated herein by reference in its entirety. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] U.S. Patent No. 5,784,423 Summary of the Invention [Problem to be solved by the invention]

[0013] While the method described in the Lidsky patent eliminates reliance on nuclear reactors for the production of Mo-99, it still has drawbacks for several reasons. For example, reliance on a single accelerator results in interruptions in production during maintenance downtime. Additionally, backflow radiation generated by the electron beam can cause severe damage to equipment located within the accelerator target area. These technical challenges make commercial production of Mo-99 using electron accelerators unlikely. Therefore, there is a continuing need to increase the production rate of Mo-99 while minimizing backflow radiation.

[0014] There is also a need for uninterrupted production of synthetic Mo-99 and other medically useful radioisotopes in the event that accelerators need to be shut down for maintenance. [Means for solving the problem]

[0015] The present disclosure generally relates to a method and system for producing product isotopes from a target isotope by irradiating the target isotope from opposite sides using a pair of electron accelerators. Illustratively, a Mo-100 target is irradiated with high-energy electrons, which generates high-energy x-rays from the opposite direction, maximizing the yield of the product isotope Mo-99 while minimizing backflow radiation.

[0016] In an exemplary embodiment, a system for producing radioisotopes can include a first electron accelerator configured to engage a first beamline and a second electron accelerator configured to engage a second beamline. The system can further include a target assembly configured to accommodate a target isotope to be converted into a product isotope, with the first beamline engaging the target assembly from a first direction and the second beamline engaging the target assembly from a second direction. More specifically, the target isotope can be molybdenum-100 and the product isotope can be molybdenum-99. The system can further include a hot cell coupled to the target assembly and a target cooling system configured to engage the target assembly. In particular, the target assembly can be trifurcated to engage a first cooling pipe at a proximal end and a second cooling pipe at a distal end.

[0017] In another exemplary embodiment, a method for producing a radioisotope may include fabricating a first beamline from a first electron accelerator, fabricating a second beamline from a second electron accelerator, converging the first and second beamlines onto a target assembly, irradiating the target assembly with the first and second beamlines, and converting the target isotope to a product isotope in response to irradiation of the target assembly by the first and second beamlines. More specifically, the target isotope may be molybdenum-100 and the product isotope may be molybdenum-99. In particular, the first beamline may be converging on the target assembly from a first direction and the second beamline may be converging on the target assembly from a second direction opposite the first direction.

[0018] In yet another exemplary embodiment, a system for producing molybdenum-99 can include a first electron accelerator configured to engage a first beamline, a second electron accelerator configured to engage a second beamline, and a target assembly configured to house a target holder carrying molybdenum 100 to be converted to molybdenum-99. The first beamline can engage the target assembly from a first direction, and the second beamline can engage the target assembly from a second direction opposite the first direction. Additionally, a target cooling system can be configured to provide gaseous helium to the target assembly, and a hot cell can be configured to engage the target assembly for loading and unloading the target holder. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view of a system for producing an isotope, such as Mo-99, in accordance with an exemplary embodiment of the present invention. [Figure 2] FIG. 1 is a block diagram of a beamline according to an example embodiment. [Figure 3] FIG. 1 illustrates a simplified process of delivering an electron beam to a target in accordance with an example embodiment. [Figure 4A-1] FIG. 4A-2 is a diagram illustrating a network architecture of a control system according to an example embodiment, and is an integral continuation of FIG. 4A-2. [Figure 4A-2] FIG. 4A-1 illustrates a network architecture of a control system according to an example embodiment, and is a unified continuation of FIG. 4A-1. [Figure 4B] FIG. 2 is an example control diagram for an accelerator control subsystem according to an example embodiment. [Figure 4C] FIG. 4B illustrates control parameters that can be monitored and controlled by the control system of FIG. 4A. [Figure 5A] FIG. 1 is a perspective view of a target assembly with a trifurcated region shown in dashed lines in accordance with an example embodiment. [Figure 5B]FIG. 1 is a perspective view of a target assembly with a trifurcated region shown in dashed lines in accordance with an example embodiment. [Figure 6] FIG. 5C is an enlarged perspective view of the trifurcated region of the target assembly of FIGS. 5A and 5B. [Figure 7A] FIG. 1 is an exploded view of a target holder according to an example embodiment. [Figure 7B] FIG. 7B is a perspective view of the target holder of FIG. 7A. [Figure 8] FIG. 1 is a modeled graph showing the relationship between Mo-99 production per electron of approximately 40 megaelectron volts (MeV) and disk number in a conceptual target. [Figure 9] 5C is a cross-sectional view of the trifurcated region of the target assembly of FIGS. 5A and 5B. FIG. [Figure 10] 5C is another cross-sectional view of the trifurcated region of the target assembly of FIGS. 5A and 5B. FIG. [Figure 11] 1 is a schematic diagram of an overall cooling system according to an example embodiment; [Figure 12] FIG. 1 is a perspective view of an insertion tool according to an exemplary embodiment. [Figure 13] FIG. 13 is another perspective view of the insertion tool of FIG. 12. [Figure 14] FIG. 1 is a perspective view of a hot cell according to an example embodiment. [Figure 15] FIG. 15 is another perspective view of the hot cell of FIG. 14. [Figure 16] FIG. 1 is a perspective view of a target unloader according to an example embodiment. [Figure 17A] FIG. 1 is a perspective view of a local target shield according to an example embodiment. [Figure 17B] FIG. 17B is a cross-sectional view of the local target shield of FIG. 17A showing alternative locations for the coolant inlet and outlet. [Figure 17C] FIG. 17B is an exploded view of the local target shield of FIG. 17A. [Figure 18] FIG. 1 is a cross-sectional view of a shield block container according to an example embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] Before describing the embodiments of the disclosed subject matter of the present invention in detail, it should be understood that the application of the present invention is not limited to the details of the specific arrangements shown, as the present invention may be practiced in other embodiments. Illustrative embodiments are described in the referenced figures of the drawings. The embodiments and figures disclosed herein should be considered as illustrative rather than limiting of the present invention. Furthermore, the terminology used herein is for the purpose of description and not limitation.

[0021] While the present invention may be embodied in a wide variety of forms, specific embodiments have been shown and described in detail with the understanding that this disclosure is an example of the principles of the invention. It is not intended that the invention be limited to the specific illustrated embodiments. The features of the invention disclosed herein in the text, drawings, and claims may be significant to the operation of the invention both individually and in any combination required with respect to its various embodiments. Features of one embodiment may be used in other embodiments of the invention.

[0022] Additionally, while the methods and systems described herein generally relate to the production of product isotopes (e.g., Mo-99) using target isotopes (e.g., Mo-100), it should be understood that other radioisotopes, including, but not limited to, Cu-67 using a Zn-68 target, Sc-47 using a Ti-48 target, Ac-225 using a Ra-226 target, or Re-186 using an Os-187 target, can also be produced using the methods and systems described herein. Thus, the description of an embodiment using molybdenum is not meant to preclude other isotopes. It should be understood that the systems and methods described herein are an improvement over all known systems by offering many advantages, including the ability to produce radioisotopes uninterrupted even when one of the accelerators is shut down for maintenance.

[0023] It is noteworthy that the use of artificially enriched concentrations of the target isotope can increase the yield of the desired product isotope. For example, amounts of Mo-100 ranging from the naturally abundant amount (about 9.7%) to about 95% Mo-100 can be used as the target. When 95% Mo-100 is used, the yield of Mo-99 increases by about 10-fold. Thus, when many stable isotopes exist (e.g., half-lives longer than 100 years with less than 1% loss), it is preferable to utilize a target isotope enriched for the desired target isotope.

[0024] Conventionally, neutron reduction processes for producing isotopes, particularly radioisotopes, involve firing a linear electron accelerator (linac) at a target along a common axis. However, conventional methods result in low yields of the desired isotope and also produce harmful backflow radiation to equipment located along the beamline. Thus, to maximize production efficiency and avoid backflow radiation, according to an exemplary embodiment, an enriched target is irradiated from both sides, i.e., from opposite directions, using a pair of electron accelerators.

[0025] Referring to FIG. 1 , an exemplary system 100 for producing isotopes, particularly Mo-99, is shown. Specifically, the system 100 for producing isotopes may include a first accelerator 110 and a second accelerator 120, which are coupled to a first beamline 130 and a second beamline 140, respectively. The first beamline 130 and the second beamline 140 may converge from opposite directions onto a target holder 150. The target holder 150 may be a device where a target isotope (e.g., enriched Mo-100) is held for irradiation. The target holder 150 may further be coupled to a target cooling system 160 (also referred to as a process cooling system) and a hot cell 170.

[0026] The first accelerator 110 and the second accelerator 120, along with the first beamline 130 and the second beamline 140, may be shielded within an accelerator vault 180. In an exemplary embodiment, the accelerator vault 180 may be further divided into a first radiation zone 182 that houses the first accelerator 110 and a first portion of the first beamline 130, a second radiation zone 184 that houses the second accelerator 120 and a first portion of the second beamline 140, and a third radiation zone 186 that houses the target holder 150 along with a second portion of the first beamline 130 and a second portion of the second beamline 140. The separate radiation zones allow maintenance to be performed on one component of the system 100 while the remaining components remain operational. For example, a technician can service the first accelerator 110 in the first radiation zone 182 without affecting the operation of the second accelerator 120 located in the second radiation zone 184.

[0027] The area proximal to the target holder 150 may be further shielded by a local target shield 190. One or more water skids (not shown) may be provided for cooling the first beamline 130 and / or the second beamline 140. Each water skid may include a valve and a pump mounted on a common carrier. Given that the water skids may be radioactive, the system 100 may further include one or more shielded water skid chambers 188 used to house the water skids.

[0028] In an exemplary embodiment, accelerator vault 180, along with interior walls used to form radiation zones 182, 184, 186 and waterskid chamber 188, may be constructed of high-density (HD) concrete blocks supplied by Veritas Medical Solutions of Harlesville, Pennsylvania, USA. HD concrete is better per unit volume than regular-density concrete at blocking gamma rays, which are the primary source of prompt radiation generated during the process. Specifically, prompt radiation refers to radiation emitted instantaneously during accelerator operation, as opposed to residual or induced radiation generated by active components within the vault or beamline. Other materials, such as steel or lead, can also be used for accelerator vaults, but these materials are more expensive and are not as effective as HD concrete at stopping prompt neutrons generated during the process.

[0029] The first accelerator 110 and the second accelerator 120 are used to generate accelerated electrons to irradiate the Mo-100 held in the target holder 150. In the illustrated embodiment, the first accelerator 110 and the second accelerator 120 are electron accelerators capable of providing an average power of 125 kW with 40 MeV electrons. In another embodiment, the first accelerator 110 and the second accelerator 120 are capable of generating at least 20 MeV electrons. However, as can be appreciated, the first accelerator 110 and the second accelerator 120 can provide a power output of less than 125 kW and can reliably generate energies less than 40 MeV depending on the manufacturing level and the particular embodiment.

[0030] In an exemplary embodiment, a target isotope (e.g., Mo-100) can serve as both the bremsstrahlung converter and the target material, where gamma rays produced by collisions of the electron beam with the target isotope then interact with the target isotope to produce a product isotope (e.g., Mo-99) through a gamma-n reaction, thus eliminating the need for a conventional bremsstrahlung converter.

[0031] According to an exemplary embodiment, a pair of RHODOTRON® electron beam (E-beam) accelerators manufactured by IBA Industrial of Louvain-la-Neuve, Belgium, can be used as the first accelerator 110 or the second accelerator 120. Unlike conventional linear accelerators (linacs), RHODOTRON® E-beam accelerators are continuous-wave electron beam accelerators that combine high power and high energy. The high power and high energy characteristics of RHODOTRON® E-beam accelerators help improve the production efficiency of Mo-99, which was previously unachievable using linacs. Furthermore, RHODOTRON® E-beam accelerators are more compact in size, thereby allowing a dual accelerator setup to occupy less space (measured in square feet) at an isotope production facility.

[0032] To irradiate the target holder 150 from opposite directions, dedicated beamlines (shown in FIG. 2 ) can be used to bend each electron beam at an angle toward the target holder 150. In the illustrated embodiment, the beamlines 130 and 140 bend the electron beams by 90° toward the target holder 150. The present invention is not limited to 90° and can include other angles that result in the beamlines irradiating the target from different directions or angles. As a result, the target holder 150 is not positioned on a common axis with one of the accelerators 110 or 120. Instead, in the illustrated embodiment, the first accelerator 110 and the second accelerator 120 are offset from the target holder 150, as shown in FIG. 1 .

[0033] In operation, the first beamline 130 and the second beamline 140 may receive electron beams from the first accelerator 110 and the second accelerator 120, respectively. The first beamline 130 and the second beamline 140 may then bend their respective electron beams to strike the target holder 150 from both sides to avoid back-flow radiation. After bending, the first beamline 130 and the second beamline 140 may align their respective electron beam spots with desired spots on the target holder 150 and analyze the energy of their respective electron beams or pass their respective electron beams straight through to an on-call beam analyzer and dump.

[0034] As can be appreciated, the system 100 may include other variations, such as the addition or omission of certain components, and such variations are still within the spirit of the present invention.

[0035] FIG. 2 is a block diagram of a beamline subsystem 200 that can be used as the first beamline 130 or the second beamline 140. The beamline subsystem 200 can include first beam optics 210 that receive an electron beam from an accelerator (which can be either the first accelerator 110 or the second accelerator 120 described above). The first beam optics 210 can be used to correct or steer the electron beam received from the accelerator. The first beam optics 210 can be coupled to a first diagnostic component 220 that can be used to analyze the current or position of the electron beam. The first diagnostic component 220 can be further coupled to second beam optics 230 that is used to focus the electron beam. The second beam optics 230 can be coupled to third beam optics 240 for further correction or steering of the electron beam. The third beam optics 240 can then be coupled to fourth beam optics 250, which includes an achromatic bending system. In an exemplary embodiment, to facilitate bending of the electron beam, an achromatic bending system may be used to bend the electron beam using a pair of 270° magnets.

[0036] From the fourth beam optics 250, the electron beam can travel along one of three paths. If the electron beam meets predetermined manufacturing standards, it can be bent by the fourth beam optics 250 toward the second diagnostic component 260, which can further analyze the electron beam current or position. The second diagnostic component 260 can be coupled to the fifth beam optics 270 for correction and steering, which can be further coupled to the sixth beam optics 280 for focusing. The sixth beam optics 280 can be coupled to the third diagnostic component 290 for one final current and position analysis of the electron beam before delivering the electron beam to the target (e.g., Mo-100 housed within the target holder 150 described above).

[0037] Alternatively, if the electron beam does not meet predetermined manufacturing standards, the fourth beam optics 250 may route the electron beam to a fourth diagnostic component 292 and then to a beam dump or beam stop. Finally, if the electron beam is not to be used for manufacturing, the fourth beam optics 250 may route the electron beam to a fifth diagnostic component 294, such as a spectrometer, for further analysis.

[0038] In the illustrated embodiment, the electron beam may enter and exit the fourth beam optics 250 at substantially the same plane. That is, the achromatic bending system of the fourth beam optics 250 does not affect the vertical elevation angle of the electron beam. However, in other embodiments, the electron beam may exit the fourth beam optics 250 at a different plane than the plane at which the electron beam enters the fourth beam optics 250.

[0039] As can be appreciated, the beamline subsystem 200 may include other variations, such as the addition or omission of certain components, and such variations are still within the spirit of the present invention.

[0040] 3 illustrates a simplified process 300 for delivering an electron beam to a target (which may be held in target holder 150 of FIG. 1) according to an example embodiment. In step 310, the electron beam is generated by an accelerator (e.g., accelerators 110, 120 of FIG. 1). According to an example embodiment, the electron beam may be generated using a RHODOTRON® E-beam accelerator providing 125 kW average power at 40 MeV electrons.

[0041] In step 320, the electron beam can be analyzed (e.g., by the first diagnostic component 220 of FIG. 2 ) to determine whether the energy meets the predetermined manufacturing criteria. In step 330, the electron beam can take one of three paths and can be bent accordingly. If the electron beam meets the predetermined manufacturing criteria, in step 340, the electron beam can be bent, preferably 90°, toward the target (e.g., by the fourth beam optics 250 of FIG. 2 ) and aligned to the desired beam spot at the target, and then delivered to the target in step 350. Alternatively, if the electron beam is not being used for manufacturing, it can be analyzed in step 360 by passing it through a spectrometer (e.g., the fifth diagnostic component 294 of FIG. 2 ). If the electron beam does not meet the predetermined manufacturing criteria in step 320, the beam line can be passed to a waiting beam analyzer (e.g., the fourth diagnostic component 292 of FIG. 2 ) and then to a beam dump or beam stop in step 370.

[0042] As can be appreciated, the process 300 may include other variations, such as the addition or omission of certain steps, and such variations are still within the spirit of the present invention.

[0043] 4A, 4B, and 4C illustrate a network 400 that may be used to monitor and control, for example, the beamlines described above, according to an example embodiment. Referring to FIG. 4A, the network 400 may include an enterprise network 410 and a process control network 420 separated by a firewall 430.

[0044] Enterprise network 410 may include physical machines 411 and virtual machines 415, which form an enterprise intranet. In an exemplary embodiment, physical machine 411 may include a quality control system 412 and an enterprise resource planning system 413. Additionally, virtual machines may include a system for configuration 416, a system for troubleshooting and data analysis 417, and a system for historian trending 418. Enterprise network 410 may further include a building management system 414 (BMS) that may be configured to control various aspects of the plant building. As an example, building management system 414 may be configured to control BMS devices, water, air, water filtration, uninterruptible power supply (UPS), chillers, coolers, heating, ventilation, and air conditioning (HVAC), and other systems within the plant building.

[0045] The process control network 420 may include several control subsystems for controlling various aspects of a system for radioisotope production (e.g., system 100 of FIG. 1). In an exemplary embodiment, the process control network 420 may include an accelerator control subsystem 421, a cooler control subsystem 422, a target control subsystem 423, a radiation drain control subsystem 424, a vault door control subsystem 425, and various servers 426. Each control subsystem 421, 422, 423, 424, or 425 may include one or more human-machine interfaces (HMIs), personal computers (PCs), switches, programmable logic controllers (PLCs), and / or network couplers. Each control subsystem 421, 422, 423, 424, or 425 may be further connected to an industrial Ethernet layer 440, which is further connected to each input / output (IO) of the system that each subsystem intends to control. In the exemplary embodiment, the industrial Ethernet layer 440 may be PROFINET, although other suitable network protocols may also be used. The servers 426 may include a system platform server and a historian server.

[0046] Using the accelerator control subsystem 440 as an example, the accelerator control subsystem 440 may include components located in a control room of a manufacturing facility (plant). For example, the accelerator control subsystem 440 may include a control room switch that connects the accelerator control subsystem 440 to the process control network 420. Furthermore, the control room switch may be connected to a human machine interface and a PC in the control room, allowing an operator to control and monitor the accelerator. The control room switch may also be connected to one or more PLCs.

[0047] In an exemplary embodiment, one PLC may correspond to one accelerator. For example, a first PLC may be provided for the first accelerator system 450 (which may include the first accelerator 110 and the first beamline 130), a second PLC may be provided for the second accelerator system 460 (which may include the second accelerator 120 and the second beamline 140), and a third PLC may be provided for the safety system 470. The safety system 470 may include many devices that are strictly necessary for radioisotope production but are nevertheless important to the health and safety of the operators. By way of example, the safety system 470 may include doors, search buttons, warning lights, emergency stop devices, etc.

[0048] Each PLC may be connected to its corresponding industrial Ethernet layer 440, which may further be in communication with the input / output (I / O) of the underlying components. For example, a first PLC may be connected to an industrial Ethernet layer 440, which may be connected to the I / O for a first accelerator system 450. Similarly, a second PLC may be connected to an industrial Ethernet layer 440, which may be connected to the I / O for a second accelerator system 460, and a third PLC may be connected to an industrial Ethernet layer 440, which may be connected to the I / O for a safety system 470. Depending on the embodiment, one or more network couplers (such as PN / PN couplers) may be provided to connect several industrial Ethernet layers 440 together. In one embodiment, a PN / PN coupler may be provided to connect the industrial Ethernet layer 440 for the first accelerator system 450 to the industrial Ethernet layer 440 for the second accelerator system 460. In an exemplary embodiment, the I / O for the safety system 450 may be further connected to the I / O for the first accelerator system 450 and the I / O for the second accelerator system 460.

[0049] 4A, there are many ways to configure a control subsystem, and the example configurations provided herein are for illustrative purposes only. For example, the PLC or industrial Ethernet layer 440 may be omitted from the control subsystem shown in vault door control subsystem 425. It should be understood that other example configurations of control subsystems are also within the scope of the present invention.

[0050] 4B shows an example control diagram 490 of an accelerator control subsystem according to one embodiment. When an accelerator (either the first accelerator 110 or the second accelerator 120) generates an electron beam on the target holder 150, an image (or images) of such beam on the target can be captured by a camera system. The camera system includes cameras and lenses that capture light resulting from the interaction of the electron beam with the target window in both the visible and infrared (IR) spectrum to actively control the accelerator and beamline.

[0051] The camera system can then feed data into an input for a control system (e.g., accelerator control subsystem 421). The data can then be analyzed by a set of logic circuits (which can be implemented by one of the PLCs or other computers or processors acting as diagnostic components). The control system, in conjunction with the accelerator, can analyze whether the temperature of the electron beam is within tolerance or on target. Based on such a determination, the control system can issue commands to the accelerator accordingly to adjust the beam current (signal strength) or turn off the electron beam. For example, an IR camera with a view of the target window can be used to shut down the accelerator if a high temperature is detected, prior to damage to the target window. The control system, in conjunction with the beamline, can analyze whether the size (signal shape) or position of the electron beam is within tolerance or on target, and can issue commands to the beamline to adjust accordingly.

[0052] Furthermore, in addition to monitoring parameters related to the electron beam, additional sensors may be further deployed to monitor other attributes of the beamlines (e.g., the vacuum level within each beamline). Thus, the control system may be further configured such that when a sensor detects a breach in a beamline indicated by a change in the vacuum level within that beamline, the control system can automatically shut down the corresponding accelerator and close the corresponding valve, thereby isolating the area with the vacuum leak from the rest of the plant.

[0053] Additionally, a combined control system can be provided that integrates the individual control systems of each accelerator 110, 120, each beamline 130, 140, target cooling system 160, hot cell 170, and other components of the system for producing radioisotopes. For example, the combined control system can be used to time the generation of beam pulses by the first and second accelerators 110, 120 so that the beam pulses arrive at the target holder 150 out of phase, as shown in FIG. 4C, which can help limit the temperature seen at the target and can help ensure stability of the wide electrical grid.

[0054] Furthermore, the control system may notify the operator by a visual indication, such as a warning signal on a display or a flashing light in the control room. Alternatively or additionally, the control system may be configured to notify the operator by short message service (SMS), email, telephone call, instant message (IM), or other suitable means.

[0055] The status of the sensors in the control system can be monitored remotely. For example, the control system may be configured to transmit the status of the sensors over a remote network, such as the Internet or an intranet, to a location where an operator has access to the remote network even if the person or machine is not physically present at the facility where the monitored beamline is located, thus achieving remote troubleshooting and remote monitoring capabilities.

[0056] 5A shows a trifurcated region 600 of the target assembly 500 that allows the target holder 150 to be irradiated from opposite directions. The target assembly 500 may be housed within a vacuum pipe 560. The vacuum pipe 560 may have a first beamline connection point 510 on a first side that engages the first beamline 130 and a second beamline connection point 515 (not shown in FIG. 5A ) on the opposite side that engages the second beamline 140. The target assembly 500 may include a target housing 610 that has a first target window 520, a target handling access 530, a first cooling pipe 540, and a second cooling pipe 550. It will be appreciated that while FIG. 5A is created from a perspective looking toward the first target window 520 and the first beamline connection point 510, the target assembly 500 may further include a second target window 525 (not shown in FIG. 5A) opposite the first target window 520 in substantially the same manner.

[0057] The first target window 520 and the second target window 525 may separate the interior of the target assembly 500, which may be connected to the target cooling system 160 through the first cooling pipe 540 and the second cooling pipe 550, from the exterior of the target assembly 500, which is housed within a vacuum pipe 560, which is connected to the first beamline 130 and the second beamline 140 through the first beamline connection point 510 and the second beamline connection point 515, respectively. In an exemplary embodiment, the first target window 520 and / or the second target window 525 may have a concave shape in which the curvature is directed inward toward the target disk as described in U.S. Patent Application No. 15 / 526,699 (U.S. Pregrant Publication No. 2017 / 0337997), entitled "Apparatus for Preparing Medical Radioisotopes," which is incorporated by reference in its entirety.

[0058] 5A as an example, the first beamline 130 and the second beamline 140 can carry electron beams toward the target holder 150 (held within the target assembly 500) from opposite directions, represented by the Z axis. Meanwhile, the target holder 150 can be cooled from the Y axis by a first end 542 of a first cooling pipe 540 and a first end 552 of a second cooling pipe 550. Finally, the target holder 150 can be moved in and out from the X axis via the target handling access 530. In one embodiment, the first cooling pipe 540 can serve as a coolant inlet and the second cooling pipe 550 can serve as a coolant outlet, or vice versa.

[0059] Figure 5B is another perspective view of the target assembly 500, which is relatively scaled down compared to Figure 5A. The three-prong 600 shown in Figure 5A is shown in dashed lines in Figure 5B. As shown in Figure 5B, the second end 544 of the first cooling pipe 540, the second end 554 of the second cooling pipe 550, and the target handling access 530 can extend from the vacuum pipe 560 into the hot cell 170 (see Figures 14 and 15). From there, the first cooling pipe 540 and the second cooling pipe 550 can be further connected to the target cooling system 160, as shown in Figure 1, and the target handling access 530 can be further connected to the insertion tool 1200, as shown in Figure 12.

[0060] FIG. 6 is another enlarged perspective view of the three-pronged region 600 of the target assembly 500. The three-pronged region 600 includes a target housing 610 with an opening. In the illustrated embodiment, the target housing 610 can be substantially T-shaped. In an alternative embodiment, the target housing can be substantially M-shaped. The target housing can have a first opening 612 configured to engage with the target handling access 530 (not shown in FIG. 6). The target holder 150 can be inserted into the target housing 610 through the target handling access 530 and the first opening 612. The first cooling pipe 540 can engage with the target housing 610 at the second opening 614, and the second cooling pipe 550 can engage with the target housing 610 at the third opening 616, thereby creating a substantially three-pronged shape. When the target handling access 530, the first cooling pipe 540, and the second cooling pipe 550 engage the target housing 610, the trifurcated region can be substantially airtight, thereby preventing coolant from leaking into the vacuum pipe 560. The target housing 610 can further include a first target window 520 and a second target window 525 on the opposite side from the first target window 520, thereby allowing the target housing 610 to receive the electron beam from the beamline in opposite directions.

[0061] 7A and 7B illustrate a target holder 150 according to an example embodiment. The target holder 150 may have a first bundling component 710 at a first end and a second bundling component 720 at a second end opposite the first end. A plurality of spacers 730 may be provided between the first bundling component 710 and the second bundling component 720 to sandwich at least one target disk 740 in a stacked configuration. In other words, each target disk 740 may be sandwiched between two spacers 730.

[0062] The first binding component 710 and the second binding component 720 may each have one or more corresponding openings 712 through which a fastener 714 may be inserted. The fastener 714 may be a rod, bolt, screw, or other suitable fastener. In one embodiment, the fastener 714 may have multiple portions that may be joined together to form the fastener 714.

[0063] Each spacer can include an upper bracket 731 and a lower bracket 733, which can have one or more first openings 732 corresponding to the openings 712 in the first binding component 710 or the second binding component 720. Because the first openings 732 in the spacer 730 correspond to the openings 712 in the binding component 710 or 720, fasteners 714 can fasten the binding component 710, 720 and the spacer 730 together with the target disk 740 positioned between the spacers 730, thus forming the target holder 150. In the exemplary embodiment shown in Figures 7A and 7B, four openings 712 can be provided at the four corners of the first binding component 710 and the second binding component 720, respectively, and four fasteners 714 can be provided at the four corners.

[0064] Each spacer 730 may further include a second opening 734 between the upper bracket 731 and the lower bracket 733, corresponding to the shape of the target disk 740. For example, if the target disk 740 is circular, the second opening 734 may also be circular. However, the dimensions of the second opening 734 may be slightly smaller than the target disk 740, so that the target disk 740 may be held between the two spacers 730 with a substantial portion of the target disk 740 exposed through the second opening 734 of each of the two spacers 730. Furthermore, one or more cooling channels 736 may be provided in the spacers 730. In an exemplary embodiment, the cooling channels 736 may be in the form of slit-like openings. Furthermore, assuming that the target disks 740 are stacked between the spacers 730, the gap between the portions of the two spacers 730 that do not overlap with the target disk 740 may functionally serve as an additional cooling channel.

[0065] Additionally, one or more manipulation apertures 738 may also be provided on the spacers 730 (e.g., on the lower bracket 733) to allow the configured target holder 150 to be manipulated via external manipulation means (e.g., a mechanical or robotic arm). By way of example, in one embodiment, a mechanical arm or air-driven actuator (e.g., actuator 1610 in FIG. 16) may be inserted into the manipulation apertures 738 to increase the space between each spacer 730, thereby loosening the fasteners 714 and allowing the target disks 740 to fall out of the target holder 150. Of course, the manipulation apertures 738 may also be used for other purposes, such as to move the target holder 150.

[0066] The target disks 740 may be made of enriched Mo-100 or another isotope. In an exemplary embodiment, the target holder 150 can hold approximately 80 to approximately 90 Mo-100 target disks 740. In an exemplary embodiment, the Mo-100 target disks 740 may be circular in shape, approximately 0.3 to approximately 0.7 mm thick, and approximately 25 to approximately 30 mm in diameter, for a total of approximately 26.0 grams (g) of Mo-100. By way of example, an exemplary target holder 150 can hold 86 enriched Mo-100 target disks 740, each 29 mm in diameter and 0.5 mm thick. However, more or fewer target disks 740 may be used to produce Mo-99. FIG. 8 is a graph illustrating the modeled yield of Mo-99 per electron at approximately 40 MeV versus the number of disks in a conceptual target.

[0067] Using the beam intensity and conceptual target parameters shown in Figure 8, if this production rate were maintained for seven days (164 hours) of irradiation, and four hours were required to remove the activated target and insert a new one, it would result in approximately 2100 curies (Ci) of Mo-99. If the same process were maintained for seven consecutive one-day (20-hour) irradiations, it would result in approximately 3300 Ci over the course of a week, whereas if the same process were maintained for two consecutive three-and-a-half-day (80-hour) irradiations, it would result in approximately 2800 Ci over the course of a week.

[0068] Mo-100 comprises about 9.8 percent of the naturally abundant molybdenum. Preferred Mo-100 targets contain about 90 to about 99 percent Mo-100. Typically used targets contain about 95 percent Mo-100.

[0069] 9 and 10 are additional cross-sectional views of the trifurcated region 600. First, referring to FIG. 9 , which shows the trifurcated region 600 from one side (along the Y-axis in FIG. 5A ) after the target holder 150 has been inserted, the target disk 740 held in place by the target holder 150 can be aligned with beamlines coming from both directions. Additionally, a first cooling pipe 540 located above the target holder 150 and a second cooling pipe 550 located below the target holder 150 bring coolant from the target cooling system 160 to the target holder 150 for cooling. In one embodiment, the first cooling pipe 540 can serve as a coolant inlet and the second cooling pipe 550 can serve as a coolant outlet, or vice versa. In between, a target handling access 530 is provided, which can include a target insertion channel 532 into which the target holder 150 can be inserted using an insertion carriage 910. Additionally, an insertion rail 534 may be provided within the insertion channel 532, allowing the insertion carriage 910 to move within the insertion channel 532. As shown in FIG. 9, the three-pronged region 600 may be housed within a vacuum pipe 560.

[0070] FIG. 10 is another cross-sectional view of the trifurcated region 600 as viewed from above (along the Z-axis in FIG. 5A ). As shown more clearly in FIG. 10 , after insertion, the target holder 150 is positioned between the first beam line 130 and the second beam line 140, which extend from opposite directions, thereby irradiating the target disk 740 in the target holder from both directions. As shown in FIG. 10 , the first beam line 130 can engage with a vacuum pipe 560 at a first beam line connection point 510. The first beam line 130 can be positioned such that the electron beam passes through the first target window 520 to irradiate the target disk 740 held in the target holder 150 from a first side. Similarly, the second beamline 140 may engage a vacuum pipe 560 at a second beamline connection point 515 opposite the first beamline connection point 510, the second beamline being positioned such that the electron beam passes through a second target window 525 and irradiates a target disk 740 held in a target holder 150 from a second side opposite the first side, thereby irradiating the target disk 740 from both sides. One or more cooling channels 536 may be provided within the target handling access 530 to allow some coolant from the target cooling system 160 to flow into the insertion channel 532 to cool the insertion carriage 910. The cooling channels 536 may be purposefully designed to control the flow rate of coolant entering the insertion channel 532 and to ensure sufficient coolant flow through the target holder 150. In an exemplary embodiment, the cooling channels 536 may be conical in shape.

[0071] The insertion carriage 910 may include one or more clips 912 that can be used to retain the target holder 150 in the target insertion channel 532. According to an exemplary embodiment, as shown in FIG. 10 , a retention mechanism 533 may be provided in the target insertion channel 532. The retention mechanism 533 may include a recess that can mate with a protrusion on the clip 912. Thus, when the insertion carriage 910 is inserted into the target assembly 500, the protrusion on the clip 912 mates with the recess on the retention mechanism 533, thereby holding the target holder 150 in place. Additionally, the insertion carriage 910 may include several removable sections. For example, the clip 912 may be located on a first section 911 of the insertion carriage 910. Once the clip 912 is engaged with the retention mechanism 533, the remaining sections of the insertion carriage 910 may be retracted before irradiation begins. Additionally, a spring mechanism 914 may be coupled to a first end of the clip 912 to lock the clip 912 in place with the retaining mechanism 533. One or more segment spacers 920 may be used to space the segments of the insertion carriage 910 apart from one another. The first segment 911 of the insertion carriage 910 may further include one or more engagement mechanisms 913 positioned to engage the target holder 150.

[0072] Additionally, a ramp 917 may be provided at the second section 916 of the insertion carriage 910. The second section 916 may be attachable to and detachable from the first section 911. The ramp 917 may engage a second end of the clip 912 opposite the first end, thereby providing a leverage force to disengage the clip 912 from the retention mechanism 533. The insertion carriage 910 may also include a third section 918 that is detachable from and attachable to the second section 916. The third section 918 may have an attachment mechanism 919 that attaches the third section 918 to the second section 916. The attachment mechanism 919 may include, for example, a spring or hydraulic device for holding the third section 918 in place with the second section 916.

[0073] FIG. 11 is a schematic diagram of an overall cooling system 1100 according to an example embodiment. The overall cooling system may include a target cooling system 160. Cooling the target holder 150 may be a complex task due to the high amount of power input into the target holder 150 by the electron beam and the high amount of radiation generated during this process. In an example embodiment, gaseous helium may be used to cool the target holder 150. Helium does not react with Mo, even at high temperatures. Additionally, helium has a very small cross section for interacting with the prompt radiation generated by the accelerator, and thus does not generate significant amounts of activated species. However, other coolants, such as nitrogen or hydrogen, may also be used. In an alternative embodiment, a liquid coolant may be used to cool the target holder 150.

[0074] The target cooling system 160 can transfer heat from the target holder 150 to the chiller system by direct heat exchange, as shown in Figure 11. In an exemplary embodiment, a helium blower can be used, which flows high-pressure (approximately 300 psia) helium at a high mass flow rate (greater than 350 g / s) through the system to ensure proper cooling of the target holder 150.

[0075] In addition to the blower and heat exchanger, the target cooling system 160 may include additional sections including a heat exchanger, a filtration system, a monitoring system, and a purification system to remove the heat added by the blower to ensure contaminant-free operation.

[0076] Within target cooling system 160, helium gas or other coolant can travel from the blower and other subsystems through pipes in both the inner walls of accelerator vault 180 and local target shield 190 to target holder 150 held within target assembly 500. In other words, target cooling system 160 can ultimately be connected through various pipes and mechanisms to first cooling pipe 540 and second cooling pipe 550 to cool target holder 150.

[0077] The overall cooling system 1100 may further include an accelerator cooling system 1110 and a target shielding and beamline cooling system 1120. In an exemplary embodiment, the accelerator cooling system 1110 and the target shielding and beamline cooling system 1120 may utilize liquid cooling in combination with various skids. As described above, the skids may be maintained in one or more water skid chambers 188 of FIG. 1. In-house chilled water 1140 may be used to power the various cooling systems as shown in FIG. 11.

[0078] 12 and 13 show several perspective views of an insertion / removal tool 1200 according to an example embodiment. The insertion tool 1200 can be used to push or pull the insertion carriage 910 along the insertion rail 534, thereby inserting or removing the target holder 150 into or from the target housing 610. The insertion tool 1200 can include a motor 1210 (e.g., an electric stepper motor) coupled to a push-pull chain 1220 to push or pull the insertion carriage 910. The insertion tool 1200 can also include a linear position transducer 1230 and a pusher trolley 1240. During insertion or removal, the insertion carriage 910 can be coupled to the pusher trolley 1240, thereby pushing or pulling the insertion carriage 910. As shown in FIG. 12 , the insertion carriage 910 can also include one or more rail couplers 930 that secure the insertion carriage 910 on the insertion rail 534.

[0079] 13, in operation, motor 1210 can push insertion carriage 910, with target holder 150 engaged, through target handling access 530 and into triangular region 600 of target assembly 500 prior to irradiation. Once clip 912 on first section 911 of insertion carriage 910 engages retention mechanism 533 on insertion channel 532, as shown in FIG. 10, this secures target holder 150 in a state ready for irradiation. The remaining sections of insertion carriage 910 can then be disengaged from first section 911 and withdrawn by motor 1210.

[0080] The radioactive plug 1310 can then be inserted through the insertion carriage 910 into the insertion channel 532. The radioactive plug can be coupled into segments. In some embodiments, multiple radioactive plugs 1310 can be paired together as a segment, or multiple segments can be connected together.

[0081] Once the radioactive plug 1310 is inserted into the insertion channel 532, the insertion carriage 910 can once again be retracted by the motor 1210. A portion of the insertion rail 534 can then be disengaged, thereby creating a sufficient gap for the channel door 1320 to seal the insertion channel 530. In an exemplary embodiment, the channel door 1320 can withstand and seal a pressurized insertion channel 530 filled with helium, for example, up to 300 psi.

[0082] After conversion and opening the channel door 1320, the disengagement portion of the insertion rail 534 can be re-engaged. The motor 1210 can once again engage the insertion carriage 910 to extract the radioactive plug 1310. The insertion carriage 910 can then remove the target holder 150 holding the converted Mo-99 from the three-way area 600.

[0083] After irradiation, the original Mo-100 that made up the target disk 740 held by the target holder 150 is partially converted to Mo-99 and is radioactive. The irradiated target disk 740 can be removed from the tri-furcation region 600 and placed into the hot cell 170 by the insertion tool 1200.

[0084] FIG. 14 is a perspective view of a hot cell 170 according to an example embodiment. FIG. 15 further illustrates a cross section of the hot cell of FIG. 14. As shown in FIGS. 14 and 15, the insertion tool 1200 can be housed within the hot cell 170. In the example embodiment, the hot cell 170 can include a hot cell shield 1410 that acts as a radiation shield to prevent radiation from escaping the hot cell 170. The hot cell 170 can also include a manipulator 1420 coupled to a mechanical arm 1430. An operator can use the manipulator 1420 to control the mechanical arm 1430 to perform various operations, such as engaging the target holder 150 with the insertion carriage 910, placing the radioactive plug 1310 on the insertion rail 534, and other operations as needed. The mechanical arm 1430 may further engage a target unloader 1600, as shown in FIG. 7B and described above, which is designed to engage the operating aperture 738 to loosen the target holder 150, thereby allowing the target disk 740 to fall out of the target holder. A monitoring system 1440 may be provided to allow an operator to monitor various conditions within the hot cell 170. An observation window 1450 may also be provided in the hot cell 170 to allow the operator to view into the hot cell 170. Alternatively, the mechanical arm 1430 may be electronically and remotely controlled by a remote operator. One or more trapdoors 1460 may also be provided in the hot cell 170 to allow loading and unloading of the target holder 150. Additionally, the hot cell 170 may include a storage compartment 1470 that can be used to store used target holders 150. Additionally, a crane system 1480 may be used to allow for precise movement of different components within the hot cell 170 .

[0085] 16 is a perspective view of a target unloader 1600 according to an example embodiment. The target unloader 1600 may include an actuator 1610 configured to individually separate or break apart the stack of target holders 150. The actuator 1610 may be air-driven in an example embodiment. A canister 1620 may be provided to hold the transmuted Mo-99-containing target disks 740. In an example embodiment, the canister 1620 may eventually be removed from the hot cell 170 so that the transmuted product isotope (e.g., Mo-99) can be recovered from the hot cell 170.

[0086] The irradiation process generates a large amount of radiation that is not input into the process. This radiation must be contained, which is the role of shielding. As mentioned above, accelerator vault 180 can be provided to shield the surrounding environment from the radiation emitted by system 100. Additionally, local shielding, such as local target shield 190, can be placed around trifurcated region 600 to reduce the total amount of concrete required for the vault.

[0087] 17A, 17B, and 17C illustrate a local target shield 190 according to an example embodiment. The local target shield 190 may include a jacket 1710. The jacket 1710 may house a portion of the first beamline 130 and a portion of the second beamline 140, as well as the vacuum pipe 560. Referring specifically to FIG. 17C, a first section 1712 of the jacket 1710 may be designed to house a portion of the vacuum pipe 560, a second section 1714 of the jacket 1710 may be designed to house a portion of the first beamline 130, and a third section 1716 of the jacket 1710 may be designed to house a portion of the second beamline 140.

[0088] In an exemplary embodiment, the jacket 1710 may be liquid-cooled. Specifically, the jacket 1710 may be filled with a mixture of water and steel balls and cooled by flowing water, although it should be understood that other liquids, such as an ethylene glycol-water mixture, may also be used in the jacket 1710. The jacket 1710 may be a component of the target shield-beamline cooling system 1120 (see FIG. 11). An inlet 1718 and an outlet 1719 may be provided in the jacket 1710 to facilitate the flow of coolant through the jacket 1710, and FIGS. 17A and 17B show two exemplary locations where the inlet 1718 and outlet 1719 may be provided in the jacket 1710.

[0089] The local target shield 190 may further include a plurality of shielding block containers 1720 surrounding the jacket 1710. The shielding block containers 1720 may be modular such that one or more shielding block containers 1720 can be installed or removed from the local target shield 190 to facilitate facility maintenance.

[0090] 18, a shielding block vessel 1720 can include one or more dividers 1810 that divide the interior space of the block vessel 1720 into one or more interior chambers 1820. The interior chambers 1820 can be connected to one another by one or more passageways, or the interior chambers 1820 can be isolated from one another.

[0091] In an exemplary embodiment, some or all of the interior chamber 1820 can be filled with a mixture of radiation-absorbing metal shot 1830 (e.g., steel balls) and liquid coolant 1840 (e.g., water). An inlet 1850 and an outlet 1860 can be provided in the shielding block vessel 1720 to facilitate the flow of the liquid coolant 1840. In some embodiments, ports can be provided that function as both an inlet and / or an outlet. The combination of the metal shot 1830 and the liquid coolant 1840 can form an effective shield for both gamma and neutron radiation. In an alternative embodiment, the interior chamber 1820 can be filled with a mixture of carbon steel and concrete, which is also an effective shield for both gamma and neutron radiation. It should be understood that other materials can also be used for shielding purposes.

[0092] The local target shield 190 may include shielding block containers 1720 filled with various shielding materials. By way of example, in an exemplary embodiment, the shielding block containers 1720 located near the target holder 150 may be filled with metal shot 1830 and liquid coolant 1840, while the shielding block containers 1720 located farther from the target holder 150 may be filled with carbon steel and concrete. In such an exemplary embodiment, the shielding block containers 1720 filled with metal shot 1830 and liquid coolant 1840 may form an inner layer, and the shielding block containers 1720 filled with carbon steel and concrete may form an outer layer of shielding within the local target shield 190. Specifically, by filling the shielding block container 1720 with liquid coolant 1840, which is positioned closer to the target than the shielding block container 1720 filled with concrete, the liquid coolant 1840 in a flowing state can remove heat that has accumulated within the shielding block container 1720 due to radiation.

[0093] In the illustrated embodiment, the metal shot 1830 may be steel balls approximately ½ inch (1.27 cm) in diameter. While FIG. 18 shows only one internal chamber 1820 filled with metal shot 1830, it should be understood that other internal chambers 1820 may also contain metal shot 1830.

[0094] In certain embodiments, the shielding block container 1720 can be made of various materials, such as regular concrete, steel, HD concrete, or other radiation blocking (absorbing) materials. In yet other embodiments, the shielding block container 1720 can be made of solid concrete or steel blocks.

[0095] Specific embodiments of a method and system for producing molybdenum-99 in accordance with the present invention have been described for the purpose of illustrating how the invention can be made and used. It is to be understood that other variations and modifications of the present invention and its different aspects will be apparent to those skilled in the art, and the present invention is not limited to the specific embodiments described. Features described in one embodiment may be embodied in other embodiments. The present disclosure should be understood to include the present invention and any and all modifications, variations, or equivalents that fall within the spirit and scope of the underlying basic principles disclosed and claimed herein.

Claims

1. 1. A system for producing radioisotopes, comprising: a first radiation zone containing a first electron accelerator configured to engage a first beam line, the first beam line configured to receive a first electron beam from the first electron accelerator, the first radiation zone extending along a first axis; a second radiation zone containing a second electron accelerator configured to engage a second beam line, the second beam line configured to receive a second electron beam from the second electron accelerator extending along a second axis; and a third radiation zone containing a target assembly containing a target isotope to be converted into a product isotope; the first beamline includes a first beamline subsystem that bends the first electron beam at a first angle to engage the target assembly from a first direction; the second beamline includes a second beamline subsystem that bends the second electron beam at a second angle to engage the target assembly from a second direction opposite the first direction.

2. The system of claim 1 , wherein the first electron accelerator and the second electron accelerator are continuous wave electron beam accelerators.

3. The system of claim 1 , wherein the first electron accelerator and the second electron accelerator are configured to provide an average power output of 125 kW at 40 MeV electrons.

4. a hot cell configured to engage the target assembly; The system of claim 1 , further comprising: a target cooling system configured to engage the target assembly.

5. the target assembly further includes a target housing having a first opening, a second opening, and a third opening; the target housing engages the first cooling pipe at the second opening; the target housing engages a second cooling pipe at the third opening; The system of claim 4 , wherein the first opening, the first cooling pipe, and the second cooling pipe form a trifurcated shape.

6. the target cooling system is configured to engage the target assembly via the first cooling pipe and the second cooling pipe; The system of claim 5 , wherein the first cooling pipe serves as a coolant inlet and the second cooling pipe serves as a coolant outlet.

7. The system of claim 1, wherein the first beamline subsystem is a first achromatic bending system and the second beamline subsystem is a second achromatic bending system.

8. The system described in claim 7, wherein each of the first achromatic bending system and the second achromatic bending system includes a pair of 270° magnets.

9. The system of claim 1, wherein each of the first angle and the second angle is 90 degrees.

10. The system of claim 1, wherein the target assembly is housed within a vacuum pipe.

11. The system described in claim 10, wherein the vacuum pipe includes a first beamline connection point that engages with the first beamline and a second beamline connection point that engages with the second beamline.

12. The system of claim 10, wherein the vacuum pipe is housed within a jacket that cools the vacuum pipe.

13. The system of claim 12, wherein the jacket is liquid cooled.

14. The system of claim 6, wherein the coolant is a gaseous coolant.

15. The system of claim 14, wherein the gaseous coolant is helium.

16. The system of claim 6, wherein the coolant is a liquid coolant.

17. The method of claim 17, wherein the target isotope is molybdenum-100 and the product isotope is molybdenum-99, or the target isotope is Zn-68 and the product isotope is Cu-67; or the target isotope is Ti-48 and the product isotope is Sc-47; or the target isotope is Ra-226 and the product isotope is Ac-225, or 2. The system of claim 1, wherein the target isotope is Os-187 and the product isotope is Re-186.

18. The system of claim 5, further comprising a target holder for containing the target isotope, the target holder engaging the target housing through the first opening.

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