阅读说明：本技术 产生放射性同位素的靶辐照系统 (Target irradiation system for producing radioisotopes ) 是由 T.G.昂德沃特 M.A.阿尔博伊诺 B.D.费希尔 A.朗 于 2019-08-23 设计创作，主要内容包括：一种用于对裂变反应堆的容器贯穿结构中的放射性同位素靶进行辐照的靶辐照系统,该系统包括：靶输送组件,该靶输送组件包括限定中心孔的主体、可滑动地接收在主体的中心孔内的篮、以及通过线缆连接至所述篮的绞盘,所述靶输送组件附着到反应堆的容器贯穿结构上；以及与靶输送组件流体连通的靶通道,其中所述篮配置为经由靶通道在其中接收放射性同位素靶,并且在辐照放射性同位素靶时,所述篮被降到反应堆的容器贯穿结构中,所述靶输送系统在与反应堆流体连通时形成反应堆的压力边界的一部分。(A target irradiation system for irradiating a radioisotope target in a vessel penetration structure of a fission reactor, the system comprising: a target transport assembly comprising a body defining a central bore, a basket slidably received within the central bore of the body, and a winch connected to the basket by a cable, the target transport assembly being attached to a vessel penetration structure of a reactor; and a target passage in fluid communication with the target delivery assembly, wherein the basket is configured to receive the radioisotope target therein via the target passage and upon irradiation of the radioisotope target, the basket is lowered into a vessel penetration structure of the reactor, the target delivery system forming a portion of a pressure boundary of the reactor when in fluid communication with the reactor.)

1. A target irradiation system for irradiating a radioisotope target in a vessel penetration structure of a fission reactor, comprising:

a target transport assembly including a body defining a central bore, a basket slidably received within the central bore of the body, and a winch connected to the basket by a cable, the target transport assembly being secured to a vessel penetration structure of a reactor; and

a target channel in fluid communication with the target delivery assembly,

wherein the basket is configured to receive a radioisotope target therein via a target passage and upon irradiation of the radioisotope target, the basket is lowered into a vessel penetration structure of a reactor, the target delivery system forming a portion of a pressure boundary of the reactor when in fluid communication with the reactor.

2. The target irradiation system of claim 1, wherein the fission reactor is a heavy water moderating fission reactor and the vessel penetration structure is a regulator port.

3. The target irradiation system of claim 2, wherein the radioisotope target is comprised of native molybdenum.

4. The target irradiation system of claim 1, wherein the target transport assembly is attached to the container through structure such that a portion of the body of the target transport assembly extends down into the container through structure.

5. The target irradiation system of claim 4, wherein the container penetration structure is an absorber port of a regulator.

6. The target irradiation system of claim 1, wherein the basket further comprises a cylindrical sidewall including a plurality of apertures such that a moderator fluid of a fission reactor can enter the basket when the basket is in the fission reactor.

7. The target irradiation system of claim 1, further comprising a substantially cylindrical target compartment in which the radioisotope target is disposed, wherein the target compartment includes a pair of annular side projections extending radially outward therefrom.

8. The target irradiation system of claim 1, wherein one of the pair of annular side projections is disposed at each end of the target capsule.

9. The target irradiation system of claim 1, further comprising:

a pneumatic pressure source; and

a pneumatic inlet in fluid communication with the central bore of the body of the target delivery assembly to apply pneumatic pressure to the radioisotope target.

10. The target irradiation system of claim 9, wherein the pneumatic inlet is disposed below a lowermost radioisotope target within the central bore of the target transport assembly.

11. A target irradiation system for irradiating a radioisotope target in a vessel penetration structure of a fission reactor, comprising:

a target delivery assembly including an outer tube and an inner tube disposed within the outer tube, thereby forming an annular space between the outer tube and the inner tube;

at least one flow channel extending between the bottom end of the outer tube and the bottom end of the inner tube; and

a lift piston slidably disposed in the inner tube, the lift piston including a one-way check valve that permits downward flow and prevents upward flow.

12. The target irradiation system of claim 11, wherein the inner tube further comprises an upper portion, a lower portion, and a constricted portion disposed between the upper and lower portions, the constricted portion defining an aperture having an inner diameter smaller than an outer diameter of the lift piston, thereby preventing passage of the lift piston from the lower portion to the upper portion of the inner tube.

13. The target irradiation system of claim 11, further comprising a central tube disposed within an upper portion of the inner tube, thereby defining an annular space between the central tube and the inner tube.

14. The target irradiation system of claim 13, further comprising at least one flow orifice defined in the bottom end of the central tube adjacent the constriction.

15. The target irradiation system of claim 11, further comprising a damper element disposed inside and at the bottom of the inner tube.

16. The target irradiation system of claim 11, wherein the fission reactor is a heavy water moderating fission reactor and the vessel penetration structure is a regulator port.

17. The target irradiation system of claim 11, wherein the target transport assembly is attached to the container through structure such that a portion of the body of the target transport assembly extends down into the container through structure.

18. The target irradiation system of claim 17, wherein the container penetration structure is an absorber port of a regulator.

19. The target irradiation system of claim 11, further comprising a substantially cylindrical target compartment in which the radioisotope target is disposed, wherein the target compartment includes a pair of annular side projections extending radially outward therefrom.

20. The target irradiation system of claim 11, further comprising:

a hydraulic source; and

a hydraulic inlet in fluid communication with the annular space of the target delivery assembly for applying hydraulic pressure to the radioisotope target through the at least one flow passage.

Technical Field

The presently disclosed invention relates generally to a system for irradiating radioisotope targets in nuclear reactors, and more particularly, to a system for irradiating radioisotope targets in heavy water moderated fission nuclear reactors.

Background

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

Given the short half-life of Tc-99m, Tc-99m is typically obtained by a Mo-99/Tc-99m generator at the desired location and/or time (e.g., in a pharmacy, hospital, etc.). The Mo-99/Tc-99m generator is a device for extracting a metastable isotope of technetium (i.e., Tc-99m) from a decaying molybdenum-99 (Mo-99) source by flowing brine through the molybdenum-99 material. Mo-99 is unstable and decays to Tc-99m over a 66 hour half-life. Mo-99 is typically produced in high throughput nuclear reactors by irradiation with highly concentrated uranium targets (93% uranium-235) and, after subsequent processing steps, is transported to Mo-99/Tc-99m generator manufacturing plants to reduce Mo-99 to a usable form, such as titanium molybdate-99 (Ti-Mo 99). Mo-99/Tc-99m generators are then distributed from these centralized locations to hospitals and drug stores across the country. Because Mo-99 has a short half-life and the number of existing production sites is limited, it is desirable to 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.

Thus, there remains at least a need for a system and process for timely production of titanium-99 molybdate material suitable for use in Tc-99m generators.

Disclosure of Invention

One embodiment of the present disclosure provides a target irradiation system for irradiating radioisotope targets in a vessel penetration structure of a fission reactor, the system comprising: a target transport assembly comprising a body defining a central bore, a basket slidably received within the central bore of the body, and a winch connected to the basket by a cable, the target transport assembly being attached to a vessel penetration structure of a reactor; and a target passage in fluid communication with the target delivery assembly, wherein the basket is configured to receive the radioisotope target therein via the target passage and upon irradiation of the radioisotope target, the basket is lowered into a vessel penetration structure of the reactor, the target delivery system forming a portion of a pressure boundary of the reactor when in fluid communication with the reactor.

Another embodiment of the present disclosure provides a target irradiation system for irradiating a radioisotope target in a vessel penetration structure of a fission reactor, the system comprising: a target delivery assembly comprising an outer tube and an inner tube disposed therein, thereby forming an annular space between the outer tube and the inner tube; at least one flow channel extending between the bottom end of the outer tube and the bottom end of the inner tube; and a lift piston slidably disposed within the inner tube, the lift piston including a one-way check valve that flows downward and prevents upward flow.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and together with the description, serve to explain the principles of the invention.

Drawings

The present inventions now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, this 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.

FIG. 1 is a perspective view of a target irradiation system installed on a CANDU (deuterium-uranium canada) reactor of one embodiment of the present disclosure;

FIGS. 2A and 2B are perspective and cross-sectional views, respectively, of a target capsule of the target irradiation system shown in FIG. 1;

FIG. 3 includes a cross-sectional view of a hydraulic target well of the target irradiation system shown in FIG. 1;

FIGS. 4A and 4B are cross-sectional views of portions of the hydraulic target well shown in FIG. 3;

FIGS. 5A and 5B are perspective and cross-sectional views, respectively, of a lift piston of the hydraulic target well shown in FIG. 3;

FIGS. 6A and 6B are cross-sectional views of the hydraulic target well shown in FIG. 3;

FIGS. 7A, 7B, and 7C are perspective views of an air lock station of the target irradiation system shown in FIG. 1;

FIGS. 8A and 8B are schematic diagrams of piping near a hydraulic target well and a gas lock station, respectively;

FIG. 9 is a cross-sectional view of the shielded container loader of the target irradiation system shown in FIG. 1;

FIG. 10 is a perspective view of a target capsule of the target irradiation system shown in FIG. 1;

FIG. 11 is an alternative embodiment of the target irradiation system of the present invention;

FIG. 12 is an alternative embodiment of the target irradiation system of the present invention;

FIGS. 13A and 13B are perspective views of a target basket of the target irradiation system shown in FIGS. 11 and 12;

FIGS. 14A and 14B are perspective views of the target irradiation system shown in FIG. 11;

FIG. 15 is a top view of the target irradiation system of FIG. 11 installed on the reactive mechanical deck of a CANDU reactor;

FIG. 16 is a perspective view of a mechanical cable drive assembly of the target irradiation system shown in FIGS. 11 and 12;

FIG. 17 is a perspective view of a seeding drawer and a corresponding series of target compartments;

FIG. 18 is a schematic view of the piping system of the target irradiation system shown in FIGS. 11 and 12;

FIG. 19 is a cross-sectional view of an alternative embodiment of the target irradiation system of the present invention;

FIG. 20 is a cross-sectional view of a main body portion of the target irradiation system shown in FIG. 19;

FIG. 21 is a top view of the target irradiation system of FIG. 19 installed on the reactive mechanical deck of a CANDU reactor; and

FIG. 22 is a side view of the target irradiation system of FIG. 19 installed on the reactive mechanical deck of a CANDU reactor.

Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the disclosure.

Detailed Description

The present inventions now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, this 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 this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.

The target irradiation system of the present invention includes elements to be exposed to a reactor neutron flux within the core of a reactor, preferably a CANDU (deuterouranium canada) reactor, and elements to be attached to a CANDU reactor civil structure outside the reactor core. The system also includes a target capsule 12 (fig. 2A and 2B) designed to interface with other system components. The various components cooperate to form a system, and fig. 1 shows the system installed on a CANDU reactor.

As shown, the in-core target irradiation system includes a hydraulic target well 14 (fig. 4A and 4B), a lift piston 16 (fig. 5A and 5B), a separation device 18 (fig. 3), and a levitation (dwell) station 20 (fig. 3, 6A, and 6B). These components are designed to support the target capsule 12 when the target capsule 12 is in neutron flux.

As part of the system to be inserted into the CANDU core, a hydraulic target well (fig. 3) composed of zircaloy-3 and stainless steel is inserted vertically into an existing through-structure on the reactivity management platform (RMD)22 (fig. 1) of the reactor. The existing pass-through configuration currently intended for installation of the system is to disable the regulated absorber (AA) port. However, the system is not limited to installation in this location, and may be installed in other through-structures that meet installation specifications.

As shown in fig. 2A and 2B, the target capsule 12 is a vehicle that, when in the core of the reactor, isolates the material from the environmental media (e.g., hydraulic transport media) in an inert environment designed to eliminate corrosion-related degradation. The target capsule 12 is preferably constructed of 5 th commercial grade titanium (consisting of titanium-aluminum-vanadium (Ti-6 AI-4V)) with welded end caps 13. The target chamber 12 is shaped to maximize flow through the delivery conduit 23. Fig. 2A and 2B show the design of a target capsule in which there is a target material consisting of native molybdenum 11. To ensure that the target capsule 12 is safe prior to use in the reactor 15 (fig. 1), and to maintain its integrity, a comprehensive leak test and verification process is preferably performed during manufacture. The closed design of the end cap 13 incorporates a margin (e.g., side projections 17) for end forces that the capsule may experience to ensure that the weld joint does not degrade or fail due to impact or force during delivery. The tabs, end portions and body portions are preferably designed so that they do not become stretched or jammed by the pressure experienced during operation of the system.

Referring to fig. 3, the target well 14 is a guide and housing for the target capsule 12 from the RMD 22 down into the calandria container 19 (fig. 1). The target capsule 12 would be placed at the bottom of this well for a defined period of time to be exposed to the neutron flux of the CANDU reactor. During operation, the target capsule 12 is conveyed up the well to the RMD 22 using hydraulic flow. The propellant medium considered for this design is independently supplied heavy water (D2O) because this propellant minimizes health and safety risks associated with neutron flux exposure to the CANDU reactor and further minimizes impact on reactor operation. This system is not limited to the use of heavy water as a propellant. By adjusting the operating set point, it is possible to allow the use of other propellant media to achieve the same hydraulic flow.

As can best be seen in fig. 4A and 4B, the target well 14 is comprised of an inner tube 24 and an outer tube 26, the inner tube 24 and the outer tube 26 having a lift piston 16 (fig. 5A and 5B) and a force limiting device 25 (located in the inner tube 24), respectively, to limit any damage to other reactor systems caused by positive acceleration of the target capsule 12 beyond operating speed. Fig. 4A, 4B, 6A, and 6B illustrate detailed components of the target well 14 and illustrate flow paths, as discussed in more detail below.

During forced cooling, the heavy water flow will flow down the annular space 28 formed between the outer tube 26 and the inner tube 24 and then turn up from the bottom of the inner tube 24 into the inner tube 24, as shown in fig. 6A and 6B. This flow path creates the flow rate required to lift the cluster of targets 12 by utilizing the inner tube 24 and the lift piston 16.

As shown in fig. 5A and 5B, the lift piston 16 includes a central check valve 32 that allows one-way flow. This feature supports the lifting of the target in clusters (fig. 6A and 6B) while still taking into account the potential need to pass heavy water through the target capsule (fig. 4A and 4B) to dissipate the heat generated by the irradiation of the target material within the target capsule 12, as shown in fig. 4A and 4B. Similarly, this feature allows the target capsule 12 to fall to the bottom of the well under the force of gravity by passively allowing heavy water to drain through the check valve 32. The target capsule 12 placed in the reactor and exposed to CANDU reactor flux can have significant radiation hazards caused by short half-life (1-2 hours) isotopes and medium half-life (4-6 hours) isotopes. Because this poses a significant hazard to the CANDU reactor station, the target well 14 is designed with a suspension (hold-down) station 20 (fig. 3, 6A and 6B).

As shown in fig. 3, 6A and 6B, the docking station 20 is located outside the calandria vessel 19, but below the RMD 22, in the concrete shield 29 (fig. 1) of the CANDU reactor. The location of this feature is important to its function because being outside the flux region of the CANDU reactor provides the ability to stop strings of target capsules 12 and allow short half-life isotope decay. This stopping feature enables safe and economical target removal while eliminating some of the radiation hazards associated with the target material and target capsule. This feature can be customized to have different durations of the blocking period, as this depends on the material of the encapsulation and the duration of the radiation being applied.

It is contemplated that the control system for this feature will preferably include a material-based operational set point that accounts for the delay time required for safe removal. This feature may be implemented to reduce the shielding required, thereby reducing the weight load on the RMD 22, thereby contributing to the outer core portion of the system. This is desirable because the RMD 22 has design limitations associated with maximum weight loading and is a seismic sensitive area.

As can best be seen in fig. 6A and 6B, the docking station 20 is configured as a constriction of the inner well pipe 24 in which the lift pistons 16 nest to form a seal, thereby reducing the flow on the target 12 and returning them to a blocking position on the nested lift pistons 16. A side channel 34 is provided above the nesting point between the inner tube 24 and the central tube 23 arranged in the inner tube 24 to allow the injection of fresh (non-irradiated) heavy water, thereby reducing the irradiation risk of irradiated heavy water. After a defined dwell time, the flow rate is increased, allowing the series of target capsules 12 to be delivered to the singulator 18 (fig. 3). During this stage of operation, the elevator piston 16 remains nested in the inner tube constriction 35, as shown in fig. 6B.

As shown in FIG. 3, another feature of the present system is the singulator 18, which singulator 18 is an automated device attached to the top of a target well on the RMD 22. The singulator 18 alternately constrains the target capsule 12 using solenoid valves 37 that effect simple movements and releases the target capsule 12 out of the core of the system. The electromagnet provides the force without penetrating the heavy water pipe and the sealed sleeve contains the activation rod 37a of the solenoid valve 35. This feature also acts as a barrier in the event that the target capsule 12 is incorrectly injected into the target well 14. At this point, the target capsule 12 may be stopped before entering the reactor and becoming an operational or safety hazard for the CANDU station. Furthermore, in the event that the system is prematurely activated resulting in premature removal of the target capsule 12, this will serve as a barrier to again protect the CANDU station personnel and systems from injury, exposure, or damage.

With continued reference to fig. 3, another feature of the present system is a fast acting pneumatic isolation valve 38. The isolation valve 38 is in place to isolate the core and outside of the core of the system from each other in the event of a containment breach or the need to isolate any part of the system (i.e., for maintenance).

Referring to fig. 1, the core external portion of the system is comprised of a number of different components, including a hydraulic delivery system 40, a pneumatic delivery system 42, a barrier container loading station 44, and a station-in-transit airlock 46 (fig. 7A-7C). Each of the components of the core outer portion are interconnected and interfaced with each other to accomplish their intended action.

The hydraulic delivery system 40 is a closed loop hydraulic system that delivers the target capsule 12 into and out of the reactor at variable flow rates. The hydraulic system interacts with the pneumatic system 42 through an air lock (fig. 7A to 7C). The air lock uses pneumatic or hydraulic media to purge the internal cavity 43 to move the target 12 between the two systems while ensuring that the media do not contaminate each other. This is important to minimize the risk that may occur when two propellant media are mixed.

The supply part of the system consists of a propellant tank, a circulation pump and a filtering device (not shown). The supply portion provides a flow of propellant to the target well 14. Propellant is pumped to the target well 14 using a series of control valves 41 and shut-off valves 43, respectively. These valves allow the direction of flow to be manipulated depending on the particular operation being performed. Flow into and out of the target well 14 is accomplished using two primary propellant lines. One line is used to flow the target capsule between the target airlock (in this system) and the target well.

The control valve 41 and shut-off valve 43 are located at the target airlock, outside of the RMD 22 (shown in fig. 1), in an accessible area of the CANDU control station. Fluid flow to the dampers 46 and wells 14 is distributed by a manifold also located at a location outside the platform. A shut-off valve 43 is also located at the top of each well on the RMD 22. The system uses full port ball valves in the target capsule travel line because these valves maintain a constant inner diameter to allow passage of the target capsule.

Referring to fig. 8A and 8B, the system is rated as core level 2, 3, or 6, depending on the location within the system. Generally, all containment boundary piping, tubing or components are rated at level 2. The pipes, tubing and components constituting the target capsule travel line were rated in 3 stages. And, the supply pipe and the parts are rated at 6. In addition, the system will have a section with a seismic rating of Design Base Event (DBE) -A.

As shown in fig. 7A-7C, the airlock staging station 46 is used to remove/introduce the target capsule 12 from/into the hydraulic or pneumatic transport system, submerging it (fig. 7A) or drying it (fig. 7B) before releasing them into the hydraulic or pneumatic transport system. The air lock intermediate station 46 consists of two main shut-off valves 43 and a clearance cavity 43a located between them, at which clearance cavity 43a the target capsule 12 can be isolated from the rest of the system.

The function of the system is to enable the target capsule 12 to be reached in a wet state from the hydraulic system 40 or in a dry state from the pneumatic system 42. The system may perform one or both of the functions of passing fluid through the internal cavity 43a to wet the target chamber 12 for entry into the hydraulic system 40, or purging and drying the target chamber 12 for entry into the pneumatic system 42. The specific operation depends on the operation (injection or harvesting) performed by the system.

Drying of the target capsule (fig. 7B) involves first isolating the target capsule 12 in the interstitial cavity 43 a. While in cavity 43a, the hydraulic propellant is vented and a purge of the cavity occurs. The chamber is then dried with hot air to remove any residual moisture that may contain hazardous materials such as tritium before releasing the target capsule into the pneumatic system. This feature eliminates the possibility of mixing of the two propellants and eliminates the risk to workers and operator stations when there is an airborne hazard in the humid air left in the cavity before being released into the pneumatic system. When the interstitial cavity 43a is sufficiently dry, a humidity sensor located in the exhaust line of the airlock midway station 46 is used to signal.

The immersion of the new target capsule 12 utilizes a similar process. First, the target capsule 12 is isolated in the interstitial cavity 43. Then, the hydraulic propellant is introduced into the cavity 43a, and the exhaust valve 50 (fig. 7B) is opened, so that the air in the cavity 43a is exhausted after being replaced with the hydraulic propellant. Finally, the target is released into the hydraulic system 40 and the wet well 14 when it is submerged by the hydraulic propellant.

The pneumatic system 42 is a connection system connecting the intermediate station air lock 46 and the shield container loader 44. The system consists of the following elements: a compressor assembly with an inlet filter, an aftercooler, and a dehumidifier; a "wet" receiver located downstream of the compressor assembly and upstream of the air dryer assembly; an air dryer assembly with an inlet coalescing filter and an outlet filter; a "dry" receiver located downstream of the dryer assembly; a regulator valve downstream of the "dry" receiver for control and system pressure; a heating element located downstream of the pressure reducing valve; and control valves in multiple positions for controlling the direction and speed of flow.

During operation of the pneumatic system 42, the compressor fills the receiver with ambient air until a high pressure point on the receiver pressure switch is reached, at which time the compressor is turned off. As the system draws air from the receiver, the pressure in the receiver may decrease until the low pressure switch set point is triggered, causing the compressor to begin operating again. If a high pressure switch on the receiver fails, a pressure relief valve vents excess air to the CANDU station vapor recovery system through the hydraulic propellant tank.

The compressed air from the receiver is sent through a desiccant type air dryer to a second drying receiver where the dried air is accumulated for the target compartment drying operation. After the target compartment drying operation is complete, air from the system is directed to the intermediate station to deliver the target compartment to the shield container loading station 44.

As shown in fig. 9, the shield container loading station 44 uses the carriage 54 to place the transport shield container 58. The carriage 54, mounted to the linear drive system 56, transports the shielded containers 58 into a shielded cabinet 60 (fig. 1, interior of the shielded container loader), the shielded cabinet 60 not being shown in fig. 9 for ease of viewing the interior components. The shield door 68 is closed to prevent the release of radioactive particles or any emission of radiation. In a first position within the shield container loader, the shield plug 61 of the shield container is removed using a pneumatic cylinder to lower the energized magnet 63 onto the shield plug 61 of the shield container 58. Then, the shield container 58 with the shield plug removed is advanced to the next position, and the pod cartridge 59 (fig. 10) is lifted from the shield container.

The pod 59 is lifted using a vertical linear device with a locking hollow shaft. The shaft is first lowered to a predetermined height within the central bore and then rotated through a calculated number of degrees and hooked over the cross pin of the cassette 59. At this point, the shaft is raised, presenting the cartridge to the pneumatic system 57 for loading the cartridge 59. The cartridge 59 is indexed into position to ensure alignment with the pneumatic system.

With the cartridge 59 in place, the target capsule is released to this position by free fall, as shown in figure 10. The bottom of the receiving position on the box 59 is provided with a landing pad made of a high-strength material, which absorbs shocks so that the target capsule is not damaged. The cartridge 59 is then indexed to the next position and the operation is repeated. When the cassette 59 is filled, it is returned to the shield container 58, and the unloading process is performed in reverse. The shielded container 58 is moved to the desired transport area using the crane 52 (fig. 1).

As shown in fig. 11 and 12, an alternative embodiment of the target irradiation delivery system 70 of the present disclosure includes a mechanical cable drive assembly 72 (fig. 16) to raise and lower the target compartment 12 (fig. 2A and 2B) directly into the moderator, thereby eliminating the need for the hydraulic system disclosed in the first embodiment (fig. 1-10). After being lifted and blown, the target capsule 12 is pneumatically transported to the shield container loader 44.

Referring additionally to fig. 13A and 13B, the target capsule 12 is held and lowered into the core within a basket 74, which basket 74 also serves as the starting point for the pneumatic conveying operation. The basket 74 is formed such that it may be held in the center by the cable 76 of the cable drive assembly 72 while providing a pneumatic exit path 78 for the target capsule as it is ejected to the pneumatic conduit system 42 via the side-bent partial tube. Basket 74 is pulled into target delivery system 70 of body 71 mounted on top of the existing regulator port. The cable drive assembly 72 includes a winch 75 (FIG. 16) mounted on top of the target transport system 70 of the main body 71, thereby forming a portion of the containment boundary of the reactor similar to existing reactive mechanism drive arrangements.

As can best be seen in fig. 15, when the target capsule 12 is irradiated, an operational containment boundary is established by the first of the two ball valves 80a and 80B (fig. 14A and 14B) located near the RMD 22 and the two solenoid valves 82a and 82B that isolate the helium and air systems. The redundant valves provide a secondary containment boundary in the event of a failure of the primary containment valve or a button activation command. Basket 74 and cable 76 extend into the reactor through a maintenance valve and lower containment valve 84, both of which are open for insertion of the target. During harvest and seed operations, an operating containment environment is established by the lower containment valve 84 below the target delivery system 70 as the target basket is lifted into the target delivery system 70.

The lower containment valve 84 and the first upper containment ball valve 80a act as dampers and neither valve is open at any time. If the lower containment valve (or the rest of the system) requires maintenance, a maintenance valve (not shown) located below the lower containment valve acts as a service valve to isolate the system from the containment. The locations of the existing AA ports preferred for target irradiation are advantageous because they not only provide the highest flux access into the core, but also are only 18 "(best seen in fig. 15) from the peripheral portion of the RMD 22, where there is no drive.

The target basket 74 (fig. 13 and 13B) is lifted out of the core at the desired speed and held at one location in the cask region for a dwell period of up to one hour to attenuate activity prior to transport. It is expected that the target capsule 12 and basket 74 will be relatively dry after the dwell period has elapsed due to the drippings/waste heat remaining in the target capsule 12.

After the dwell period is over, the target basket 74 is lifted and received into the body 71 of the target transport system 70. Helical groove 77 (fig. 12 and 20) aligns target outlet 78 in basket 74 with pneumatic tubing 42 as basket 74 enters the mechanism. Helium is then injected into the system to flush the MCG back into the AA port, expelling air-borne impurities (e.g., Ar41) into the containment.

After purging the target delivery system 70 with helium, the lower containment valve 84 at the bottom of the target delivery system 70 is closed and the system is pressure tested using helium to ensure the integrity of the seal. After the pressure test was successfully completed, the lower air purge solenoid valve was opened, and the upper exhaust solenoid valve was opened, air was blown from the pneumatic system to blow out helium gas to the contaminated exhaust portion. This purge exhausts the helium gas and dries the target capsule 12 as needed. Moisture monitoring of the exhausted air is performed to ensure that the target is dry before exiting the target transport mechanism.

After the drying sequence is successfully completed, the upper containment valve 80a is opened and the lower vent solenoid valve is closed. The target pods 12 are then blown as a whole through the flight tube as a series of target pods and either directly to the shielded container loading station 44 (fig. 1) or one at a time using a singulation mechanism.

Referring now to fig. 1 and 17, the operator places a new target capsule 12 into the pneumatic tube system 42. It is recommended to provide a seed drawer 86 or notch on each target pod line to minimize the complexity of target loading. When loading of a new series of target capsules 12 is complete, pneumatic pressure is applied to the piping and the series of target capsules are blown directly into the basket 74. Means to slow or stop the string of target compartments 12 are preferably incorporated at the bottom of the basket 74 to limit impact fatigue of the basket 74 and cables 76 during seeding.

After all of the target compartments 12 are in the basket 74, the upper containment valve 80a is closed, the lower vent valve and the upper helium valve are opened, and the chamber is purged of air and replaced with helium. After purging the air, the lower vent valve was closed and the chamber was pressurized with helium for leak testing. The upper helium valve was closed and the pressure decay monitored. This test ensures the integrity of all containment valves. The lower containment valve 84 is then opened and the basket 74 and target capsule 12 are lowered into the calandria 19 (FIG. 1) to begin the next irradiation cycle.

Referring now to fig. 19-22, another alternate embodiment of a target irradiation delivery system 90 of the present disclosure is shown. This third embodiment is substantially the same as the previously discussed second embodiment 70 (shown in fig. 11-18), except that the overall height of this embodiment 90 above the RMD 22 is less than the overall height of the second embodiment 70. This height difference is best seen in fig. 19 and 22 (this embodiment 90) as compared to fig. 11 and 14 (the second embodiment 70), and is achieved by extending the body 91 of this embodiment down into the AA port rather than extending it up from the AA port. Reducing the height of the target delivery system 90 is preferred because it can reduce the likelihood of excessive shock during a potential seismic event. Also, reducing the height may reduce the chance of the target delivery system 90 being accidentally contacted by personnel or equipment moving around the RMD 22 (e.g., during maintenance). Since the other elements of the second embodiment 70 and the third embodiment 90 are almost the same, they will not be described again.

These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. Additionally, it should be understood that features of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so defined, except as set forth in the following claims. Therefore, the spirit and scope of the appended claims should not be limited to the description of the versions contained herein.