Target irradiation systems for the production of radioisotopes

Abstract

A target irradiation system includes an irradiated target removal system having a body defining a central bore; an elevator received within the central bore; and a docking surface for placing the irradiated target removal system in fluid communication with a vessel penetration of a reactor. A target barrel has a radioisotope target slidably received therein, and the elevator is configured to receive the target barrel. The elevator is lowered into the reactor when irradiating the radioisotope target, and the irradiated target removal system forms a portion of the pressure boundary of the reactor during target irradiation.

Description

[0001] Declaration of priority

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 698,540, filed on July 16, 2018, the disclosure of which is incorporated herein by reference. Technical Field

[0003] The presently disclosed invention relates generally to a system for irradiating a radioisotope target in a nuclear reactor, and more particularly to a system for irradiating a radioisotope target in a heavy water moderated fission type nuclear reactor. Background Art

[0004] Technetium-99m (Tc-99m) is the most commonly used radioisotope in nuclear medicine (e.g., medical diagnostic imaging). Tc-99m (m is in a metastable state) is typically injected into a patient and used with certain equipment to image the patient's internal organs. However, the half-life of Tc-99m is only six (6) hours. Thus, at least in the field of nuclear medicine, a readily available source of Tc-99m is of particular interest and / or need.

[0005] Given the short half-life of Tc-99m, Tc-99m is typically obtained at the location and / or time of need (e.g., in a pharmacy, hospital, etc.) via a Mo-99 / Tc-99m generator. A Mo-99 / Tc-99m generator is a device used to extract a metastable isotope of technetium (i.e., Tc-99m) from a decaying molybdenum-99 (Mo-99) source by passing salt water through the Mo-99 material. Mo-99 is unstable and decays to Tc-99m with a half-life of 66 hours. Mo-99 is typically produced in a high flux nuclear reactor by irradiation of a highly enriched uranium target (93% uranium-235) and shipped to a Mo-99 / Tc-99m generator manufacturing site after subsequent processing steps to reduce the Mo-99 to a usable form, such as titanium-99 molybdate (Ti-Mo99). The Mo-99 / Tc-99m generators are then distributed from these centralized locations to hospitals and pharmacies throughout the country. Due to the short half-life of Mo-99 and the limited number of existing production sites, there is a need to both minimize the time required to reduce the irradiated Mo-99 material to a usable form and to increase the number of sites where the irradiation process can occur.

[0006] Therefore, there remains at least a need for a system and method for producing titanium-99 oxide material suitable for use in Tc-99m generators in a timely manner. Summary of the invention

[0007] One embodiment of the present disclosure provides a target irradiation system for irradiating a radioisotope target in a vessel penetration of a fission reactor, the system comprising an irradiated target removal system having a body defining a central bore; a lifter configured to be selectively received within the central bore; and a docking surface configured to selectively place the irradiated target removal system in fluid communication with the vessel penetration. The target barrel includes a body defining a target bore configured to slidably receive a radioisotope target therein; and a cap configured to be attached to the body of the target barrel to provide a watertight seal for the target bore. The lifter is configured to receive the target barrel therein and to be lowered into the vessel penetration of the reactor when irradiating the radioisotope target. The irradiated target removal system forms a portion of a pressure boundary of the reactor when in fluid communication with the vessel penetration.

[0008] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements.

[0010] Figures 1A to 1C is a partial perspective view of a regulator port docking base according to an embodiment of the present invention;

[0011] Figure 2 yes Figures 1A to 1C A perspective view of a regulator port docking base is shown mounted on a reactive mechanism platform of a nuclear fission reactor;

[0012] FIG. 3A to FIG. 3D is a partial perspective view of an irradiated target removal system according to an embodiment of the present invention;

[0013] Figure 4 is an exploded perspective view of a target barrel according to an embodiment of the present invention;

[0014] Figure 5 is a perspective view of an elevator of an irradiated target removal system with a target barrel mounted thereon.

[0015] Figure 6 Yes Figures 3A to 3D A perspective view of an irradiated target removal system shown in FIG. Figures 1A to 1C The regulator port shown is docked on the base;

[0016] Fig. 7A and 7B is a perspective view of an irradiated material transfer bottle according to an embodiment of the present invention;

[0017] Figure 8 yes Fig. 7A and 7B A cross-sectional view of an irradiated material transfer bottle is shown;

[0018] Fig. 9 is a perspective view of a target exchange module according to an embodiment of the present invention;

[0019] Fig.10 is a perspective view of a heavy water moderated fission reactor including a target irradiation system according to an embodiment of the present invention;

[0020] Fig.11 is a perspective view of an irradiated target removal system mounted on an irradiated material transfer bottle in a loading / unloading area;

[0021] FIG. 12A to FIG. 12C are various views of a heavy water moderated fission reactor and corresponding vessel penetrations;

[0022] Fig.13A and 13B A perspective view and a cross-sectional view, respectively, of an alternative embodiment of a target irradiation system according to the present invention; and

[0023] Fig.14 is a perspective view of yet another alternative embodiment of a target irradiation system according to the present invention.

[0024] Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the invention according to the present disclosure. DETAILED DESCRIPTION

[0025] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the invention are shown. Indeed, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. As used in the specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.

[0026] Referring now to the drawings, a target irradiation system according to the present disclosure includes a regulator port docking base 150 ( Figures 1A to 1C ), the regulator port docking base 150 is in fluid communication with the corresponding nuclear reactor vessel penetration; irradiation target removal system 100 ( Figure 3A), which can be selectively docked with the regulator port docking base 150 so that the irradiation target removal system 100 can be inserted into and extract the irradiation target 145 from the nuclear reactor respectively ( Figure 4 ); at least one target barrel 140 ( Figure 4 ), for containing the radioisotope target 145 during irradiation; and the irradiated material transfer bottle 180 ( Figure 8 ), which includes a target exchange module 190 ( Figure 8 ), for loading and unloading the target barrel 140. Figure 2 The regulator port docking base 150 is preferably mounted to a corresponding heavy water moderated nuclear fission reactor 101 (such as Fig.10 and 12A 12C) so that the regulator port docking base 150 is connected to the unused regulator port 105 of the reactor ( Fig. 12B ) fluid communication. Note, however, that in alternative embodiments, various other types of reactor and vessel penetrations may be utilized during radioisotope target irradiation.

[0027] Reference now Figures 1A to 1C , the regulator port docking base 150 includes an outer body portion 152 that defines a central cavity in which an inner body portion 163 is disposed. The outer body 152 includes a plurality of support legs 156 extending radially outward therefrom, each support leg 156 including an outrigger 162 with a socket 158 ​​and a corresponding lag bolt 160 disposed at a lower end thereof. Each socket 158 ​​is configured to be received in a corresponding mounting aperture of the reactor reactivity mechanism platform 103 ( Figure 2 ), and lag bolts 160 are used to semi-permanently secure the regulator port docking base 150 to the reactive mechanism platform. Preferably, the outer body 152 is formed of depleted uranium to provide radiation shielding.

[0028] The inner body portion 163 of the regulator port docking base 150 includes a central hole 164 that is in fluid communication with the interior of the reactor vessel 113 through a corresponding regulator port; a mounting flange 166 that is configured to be fixed to the corresponding regulator port; and a gate valve 172 disposed at the upper end of the inner body portion 163. The gate valve 172 includes a gate 175 ( Figure 1C ) and provides a docking surface 176 so that the irradiated target removal system 100 ( Figure 3A) can be selectively secured to the regulator port docking base 150, as discussed in more detail below. A gate valve 172 provides a seal so that the regulator port docking base 150 forms part of the reactor pressure boundary when the gate valve is closed. A maintenance control valve 168 is also provided to isolate the pressure boundary if maintenance is required on the gate valve 172. In addition, a force isolation bellows 170 is provided to reduce contact forces between the irradiated target removal system 100 and the regulator docking base 150 during docking, as described in more detail below.

[0029] Reference now Figures 3A to 3D , the irradiated target removal system 100 includes a body 102 defining an elongated central hole 104, a lifter 112 selectively receivable in the central hole 104, a winch 106 connected to the lifter 112 by a cable 110 passing through a pulley 108; and a gate valve 132 disposed on the bottom of the irradiated target removal system 100. Figure 3B As best shown, the riser 112 includes a pair of opposed risers 116 having a plurality of support platforms 122 extending therebetween. Figure 3A As shown, each support platform is configured to slidably receive a corresponding target barrel 140 thereon. An elongated protrusion 118 is provided on the inner surface of the two risers 116 and is configured to engage with each target barrel 140 ( Figure 4 ) to help hold the target barrel in a desired position on the elevator 112. The connection point 114 is provided at the top end of the elevator 112 and is configured to be crimped to the bottom end of the cable 110. The elevator 112 includes a V-shaped bottom surface 124 to facilitate the elevator 112 to be positioned between the target exchange module 190 ( Fig. 9 ) for loading and unloading of the target barrel 140, as discussed in more detail below. The apexes of the V-shaped bottom surface 124 each correspond to an elongated groove 120 formed on the outer surface of each riser 116, which is also discussed in more detail below.

[0030] The irradiated target removal system 100 also includes a damped lifting assembly 126 disposed at its upper end. The damped lifting assembly 126 includes a shackle 128 to facilitate lifting by the reactor crane 107 ( Fig.10 ), and is configured to reduce the contact force between the irradiated target removal system 100 and the regulator port docking base 150 during the docking process. Preferably, a cleaning / drying box 130 is provided to remove the moderator water from the interior of the irradiated target removal system 100 after the irradiation process is completed. The drying process is performed before closing the gate valve 132 and then disconnecting the docked irradiated target removal system 100 from the regulator port docking base 150. Similar to the gate valve of the regulator port docking base 150, the gate valve 132 includes a gate ( Figure 1CThe remotely operated motor 134 is not shown in the figure, and its bottom surface is a docking surface 136 for mating with the docking surface 176 of the regulator port docking base 150, such as Figure 6 shown.

[0031] Reference now Figure 4 , the target barrel 140 includes a substantially cylindrical body portion 142 including a pair of opposing parallel side walls 143. A plurality of target holes 144 are defined by the target barrel 140, each target hole 144 being parallel to a longitudinal center axis of the target barrel 140 and configured to slidably receive a corresponding radioisotope target 145 therein. A sealing cap 146 may be connected to an end of the target barrel 140 from which the target hole 144 extends, such that the interior of the target barrel 140 remains free of fluid during irradiation. A first pair of recesses 148 and a second pair of recesses 149 are formed on opposing sides of each side wall 143 and are configured to be opened and closed by the target exchange module 190 ( Fig. 9 ) is selectively engaged with a corresponding gripper pin of the riser, as discussed in more detail below. Likewise, each side wall 143 includes an elongated recess 147 that is configured to selectively receive a corresponding elongated protrusion 118 ( Figure 3B ) to help keep each target barrel 140 on the elevator 112, such as Figure 5 shown.

[0032] Reference now Fig. 7A , 7B 8, the irradiated material transfer bottle 180 includes a main body 182 defining a central hole 184, a target exchange module 190 disposed in the central hole 184, and an in-station transfer tool 186 mounted to the top of the main body 182. Figure 7B As shown, during loading and unloading operations, the irradiated target removal system 100 is docked with the in-station transfer tool 186. The in-station transfer tool 186 provides the necessary pneumatic / electrical connections to facilitate the loading and unloading of the target cartridge 140, and its upper surface forms a docking surface 188 that is configured to mate with the docking surface 136 of the irradiated target removal system 100. Once the irradiated target removal system 100 is securely docked with the irradiated material transfer bottle 180, the gate valve 132 of the irradiated target removal system 100 is opened and the elevator 112 is lowered into the central bore 184 so that the target cartridge 140 can be loaded and / or unloaded by the target exchange module 190. Note that as Fig. 7A and 7B As shown, the irradiated material transfer bottle 180 is arranged on the top of the bracket 185, which facilitates the forklift 111 to move the irradiated material transfer bottle 180 ( Fig.10 and 11 ) in the loading area 109 of the reactor facility.

[0033] Reference now Fig. 9 , the target exchange module 190 includes a frame 192 that defines a central passage 197 and first and second storage locations 199a and 199b, respectively, disposed on opposite sides of the central passage 197. The central passage 197 is configured to allow the elevator 112 of the irradiated target removal system 100 to pass through the target exchange module 190 so that a desired target barrel 140 of the elevator is aligned with a pair of gripper slides 194 of the target exchange module 190.

[0034] like Fig. 9 As shown, each gripper slide 194 includes a first pair of gripper pins 196 and a second pair of gripper pins 198, wherein each pair of gripper pins is configured to selectively engage a corresponding pair of recesses 148 and 149 of the target barrel. The interaction between the gripper pins and the gripper recesses allows the gripper slide 194 to move the target barrel 140 onto and off the elevator 112. In addition, the gripper pins 196 and 198 can remain engaged with the corresponding recesses 148 and 149 of the target barrel during movement of the irradiated material transfer bottle 180 to help stabilize them. Each gripper slide 194 includes a plunger 191 for lateral movement of the slide along a pair of linear bearings 193.

[0035] Still refer to Fig. 9 , the target exchange module 190 includes a pair of rotation guide pins 195 that are opposite to each other and disposed adjacent to the central passage 197. Each rotation guide pin 195 extends radially inwardly into the central passage 197 and is configured to engage with the outer periphery of the V-shaped bottom surface 124 of the elevator 112 when the elevator is lowered into the central passage 197 of the target exchange module 190. When the elevator 112 is lowered into the central passage 197, each rotation guide pin 195 contacts a corresponding portion of the V-shaped bottom surface 124. If the rotation guide pins 195 are aligned with the apex 125 of the V-shaped bottom surface 124, each rotation guide pin 195 will slidably enter a corresponding one of the elongated grooves 120, each of which originates from the bottom surface and the corresponding apex 125 of the elevator 112. In this way, the elevator will pass through the target exchange module 190 without rotation. However, if the rotation guide pin 195 contacts the V-shaped bottom surface 124 anywhere other than the apex 125, the lifter 112 will be caused to rotate as the periphery of the bottom surface passes along the rotation guide pin 195. When the rotation guide pin 195 reaches the apex 125, the rotation will stop and the rotation guide pin 195 will slidably pass through the corresponding elongated groove until the lifter 112 reaches the desired position.

[0036] Reference now Fig.13A and 13B, showing an alternative embodiment of a target irradiation system according to the present disclosure. The main difference between the alternative embodiment and the previously discussed embodiment is that the regulator port docking base 250 includes a winch 256 and a pulley 258 for raising and lowering the elevator. Similar to the previously discussed embodiments, after the irradiated target removal system 200 is docked to the regulator port docking base 250, the gate valves 232 and 272 are opened and the elevator 212 can be lowered into the regulator port docking base 250, which is aligned with the corresponding regulator port 105 ( Fig. 12B and 12C ) fluid communication. However, unlike the previous embodiments, once inside the regulator port docking base 250, the elevator 212 is transferred to the capstan 256 and pulley 258 for further descent into the regulator port. After the elevator 212 is transferred to the capstan 256, the gate valves 232 and 272 are closed so that the irradiated target removal system 200 no longer forms part of the pressure boundary of the reactor. In this way, the irradiated target removal system 200 can be undocked from the regulator port docking base 250 and removed for the duration of the irradiation process. Note that Fig.13A and 13B The target irradiation system shown also differs from previous embodiments in that the irradiation target removal system 200 includes an on-board target exchange module 290 for loading and unloading the target barrel 140 .

[0037] like Fig.14 As shown, another embodiment of the target irradiation system includes an irradiated target removal system 300 that is supported by the bridge 113 as the target is irradiated when positioned on the regulator port docking base 150 and the reactive mechanism platform 103. The support provided by the bridge 113 reduces the weight supported by the regulator port docking base and also limits the number of moves required by the crane 107 on the reactive mechanism deck to properly position the irradiated target removal system 300.

[0038] Without departing from the spirit and scope of the present invention, those of ordinary skill in the art may make these and other modifications and variations to the present invention, the spirit and scope of the present invention being more particularly set forth in the appended claims. In addition, it should be understood that the various aspects of the various embodiments may be interchangeable in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is merely exemplary and is not intended to limit the present invention to as further described in the appended claims. Therefore, the spirit and scope of the appended claims should not be limited to the exemplary description of the versions contained herein.

Claims

1. A target irradiation system for irradiating a radioisotope target in a vessel penetration of a fission reactor, comprising: An irradiated target removal system comprising: a body defining a central bore; an elevator configured to be selectively received within the central bore, the elevator further comprising at least one support platform and a pair of opposed risers extending upwardly therefrom; and a docking surface configured to selectively position the irradiated target removal system in fluid communication with the vessel penetration; and A target barrel includes a body defining a target aperture configured to slidably receive a radioisotope target therein; and a cap configured to be attached to the body of the target barrel to provide a watertight seal for the target aperture, wherein the target barrel is slidably received between the pair of risers and disposed on a support platform, wherein the elevator is configured to receive a target barrel thereon, the elevator being lowered into a vessel penetration of a reactor when irradiating a radioisotope target, and an irradiated target removal system forming part of a pressure boundary of the reactor when in fluid communication with the vessel penetration, and wherein the elevator is movable from a first upper position in which the elevator is disposed within a central bore of a body of the irradiated target removal system to a second lower position in which the elevator is disposed below the body of the irradiated target removal system.

2. The target irradiation system according to claim 1, wherein: The fission reactor is a heavy water moderated fission reactor and the vessel penetration is a regulator port.

3. The target irradiation system according to claim 1, wherein: The irradiated target removal system also includes a winch and pulley assembly connected to the elevator by a cable.

4. The target irradiation system according to claim 1, wherein: The irradiated target removal system further includes a gate valve disposed at a bottom end of the body, and a bottom surface of the gate valve defines a docking surface of the irradiated target removal system.

5. The target irradiation system according to claim 1, wherein: The at least one support platform further includes a first support platform and a second support platform, and the pair of opposing risers connects the first support platform and the second support platform.

6. The target irradiation system of claim 1 , further comprising a regulator port docking base, the regulator port docking base comprising a body defining a central bore in fluid communication with the vessel feedthrough; and a docking surface configured to be selectively secured to a docking surface of an irradiated target removal system, wherein The regulator port docking base forms part of the pressure boundary of the reactor.

7. The target irradiation system according to claim 6, wherein: The regulator port docking base further includes a gate valve disposed at a top end of a body of the regulator port docking base, and a top end of the gate valve defines a docking surface of the regulator port docking base.

8. The target irradiation system according to claim 7, wherein: The regulator port docking base also includes a mounting flange attached to the container feedthrough.

9. A target irradiation system for irradiating a radioisotope target in a vessel penetration of a fission reactor, comprising: An irradiated target removal system includes a body defining a central aperture; a lifter configured to be selectively received within the central bore; and a docking surface configured to selectively position an irradiated target removal system in fluid communication with a vessel penetration, wherein the elevator is configured to move the radioisotope target into and out of an interior volume of the fission reactor, wherein the interior volume is subject to reactor operating pressure; and a gate valve movable between a first position in which the central bore is in fluid communication with the interior volume of the fission reactor and a second position in which the central bore is isolated from the interior volume of the fission reactor; wherein the elevator is configured to receive a radioisotope target thereon, the elevator being lowered into a vessel penetration of the reactor when irradiating the radioisotope target, and the irradiated target removal system forming part of a pressure boundary of the reactor when in fluid communication with the vessel penetration, and wherein the elevator is movable via a gate valve in a first position from a first upper position, wherein the elevator is disposed within a central bore of the irradiated target removal system and outside an interior volume of the fission reactor, to a second lower position, wherein the elevator is disposed within the interior volume of the fission reactor and is subject to reactor operating pressure.

10. The target irradiation system of claim 9, further comprising a regulator port docking base, the regulator port docking base comprising a body defining a central bore in fluid communication with the vessel feedthrough; and a docking surface configured to be selectively secured to a docking surface of an irradiated target removal system, wherein The regulator port docking base forms part of the pressure boundary of the reactor.

11. The target irradiation system according to claim 10, wherein: The regulator port docking base further includes a gate valve disposed at a top end of a body of the regulator port docking base, and a top end of the gate valve defines a docking surface of the regulator port docking base.

12. The target irradiation system of claim 11, further comprising: a target barrel including a body defining a target aperture configured to slidably receive a radioisotope target therein; and a cap configured to be attached to the body of the target barrel to provide a watertight seal for the target aperture.

13. The target irradiation system according to claim 12, wherein: The elevator further includes at least one support platform and a pair of opposed risers extending upwardly therefrom, wherein the target barrel is slidably received between the pair of opposed risers and disposed on the support platform.

14. The target irradiation system according to claim 13, wherein: The at least one support platform further includes a first support platform and a second support platform, and a pair of opposing risers connects the first support platform and the second support platform.

15. The target irradiation system according to claim 13, wherein: The irradiated target removal system also includes a winch and pulley assembly connected to the elevator by a cable.

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