An online replacement device for irradiation targets in a swimming pool-type reactor

Abstract

The present application discloses an online replacement device for in-core irradiation targets in a swimming pool-type reactor, which is used to solve the problem of existing reactors requiring shutdown for in-core target replacement. The online replacement device provided by the present application inserts or removes the target through the irradiation channel via a target hoisting connecting rod and a target driving mechanism. During the withdrawal of the old target, the compensating target floats up due to the buoyancy of the coolant and eventually remains in the irradiation channel due to the action of a petal-shaped stopper. During the insertion of the new target, the compensating target is pushed out of the irradiation channel by the new target. After the stopper retracts, the compensating target can be withdrawn from the core in the same manner as the old target and then replaced. During the entire target replacement process, the overall reactivity and moderation ratio of the core are not significantly disturbed, so there is no need to shut down and restart the core to replace the target. This shortens the target replacement time period, improves irradiation efficiency, reduces the complexity of the target replacement operation, and improves operational safety.

Description

Technical Field

[0001] The present application relates to the technical field of reactor isotope production equipment, and in particular to a device for online replacement of irradiation targets in a swimming pool-type reactor. Background Art

[0002] Neutron irradiation of targets within the reactor's irradiation tunnel is the primary method for producing neutron-rich isotopes. Many important medical isotopes, such as Mo-99 and I-131, are neutron-rich isotopes, and their primary production method is neutron irradiation of targets within the reactor's irradiation tunnel.

[0003] After a certain period of irradiation within the reactor, the targets need to be removed and transferred to a dedicated hot cell for post-processing, such as target dissolution and isotope separation. Simultaneously, new, unirradiated targets are placed into the core irradiation channel for the next round of irradiation production. Due to reactivity perturbations and other considerations, most research reactors require a shutdown when handling large targets. This not only prolongs the target replacement cycle and reduces production efficiency, but also introduces unnecessary complexity to reactor maintenance, increasing the likelihood of safety incidents.

[0004] Therefore, it is urgent to propose a technical solution that can realize target replacement without stopping the reactor, so as to shorten the target replacement cycle as much as possible and reduce the operating costs and safety risks during reactor operation. Summary of the Invention

[0005] The present application provides an online replacement device for irradiation targets in a swimming pool-type reactor, which is used to solve the problem in the prior art that the reactor needs to be shut down to replace targets during the irradiation process, resulting in low production efficiency and increased safety accident rate.

[0006] In order to achieve the above objectives, this application provides the following technical solutions:

[0007] The present application provides an online replacement device for an in-core irradiation target of a swimming pool type reactor, comprising a reactor pool containing a reactor, the reactor pool being filled with a coolant, a reactor operating bridge being provided at the top edge of the reactor pool, a target driving mechanism being provided on the reactor operating bridge, the target driving mechanism being connected to a target hoisting connecting rod, and the target hoisting connecting rod being detachably connected to one end of an irradiation target;

[0008] A compensation target is arranged directly below the irradiation channel in the reactor stack, and the compensation target is filled with helium. A petal-shaped stopper and an action knob for controlling the action of the petal-shaped stopper are provided on the compensation target, and the action knob is detachably connected to one end of the target hoisting connecting rod; when the target to be replaced in the irradiation channel is driven out of the irradiation channel by the target hoisting connecting rod, the compensation target enters the irradiation channel under the buoyancy of the coolant, and is fixed to the irradiation channel by the petal-shaped stopper.

[0009] The above technical solution further has the following features: the power output end of the target driving mechanism is connected to one end of the target hoisting connecting rod; the other end of the target hoisting connecting rod is detachably connected to a new target; the new target is located directly above the irradiation channel; the new target is driven by the target hoisting connecting rod to vertically downwardly enter the irradiation channel; when the new target is inserted into the irradiation channel, the compensating target located in the irradiation channel is pushed out of the irradiation channel by the new target.

[0010] Furthermore, the shape and size of the compensation target are respectively the same as the shape and size of the target to be replaced.

[0011] Furthermore, the compensation target has an outer shell, in which a first cavity and a second cavity adjacent to each other are formed, a transmission track is vertically arranged in the first cavity along the direction of its central axis, and an internal thread is formed on the inner wall of the transmission track.

[0012] Furthermore, a fuel filling area is formed in the first cavity, and the fuel filling area is an annular area arranged in a circle along the radial direction of the first cavity.

[0013] Furthermore, a helium filling area is formed between the inner wall of the first cavity and the outer wall of the transmission track.

[0014] Furthermore, the action knob is installed at the end of the transmission track away from the second cavity, and the action knob includes a drive connection end and a connecting column. The outer wall of the connecting column is provided with an external thread that is adapted to engage with the inner wall of the transmission track, and the drive connection end is adapted to be connected to the end of the target lifting connecting rod.

[0015] Furthermore, the second cavity forms the installation position of the petal-shaped limiter; the petal-shaped limiter includes a transmission rod, a head arranged at one end of the transmission rod, a wedge-shaped slider slidably connected to the head, and an elastic member for connecting the wedge-shaped slider to the inner wall of the second cavity.

[0016] Furthermore, the plug is arranged in the second cavity, the other end of the transmission rod is installed in the transmission track, and the end of the transmission rod is connected to the connecting column.

[0017] Furthermore, the end of the plug facing away from the transmission rod forms a cone, and the central axis of the cone coincides with the central axis of the transmission rod.

[0018] Furthermore, the plurality of wedge-shaped sliding blocks are evenly distributed radially around the central axis of the cone.

[0019] Furthermore, the wedge-shaped slider has a first sliding part and a second sliding part, the first sliding part is vertically arranged along the central axis of the transmission rod, and the second sliding rod is horizontally arranged along the radial direction of the transmission rod. The first sliding part is connected to the inner wall of the second cavity through a spring; the second sliding part is slidably connected to the end of the compensation target.

[0020] Furthermore, a strip-shaped protrusion is formed on the surface where the second sliding portion connects with the end of the compensation target, and the end of the compensation target is provided with a sliding groove adapted to the strip-shaped protrusion, and the length extension line of the strip-shaped protrusion is perpendicular to and intersects with the central axis of the transmission rod.

[0021] Furthermore, when the compensation target enters the irradiation channel under the buoyancy of the coolant, the target hoisting connecting rod is connected to the action knob on the compensation target, and the target driving mechanism rotates the target hoisting connecting rod clockwise, so that the transmission rod moves vertically downward under the drive of the action knob, and then pushes the multiple wedge-shaped sliders open through the head, and the second sliding part of the wedge-shaped slider slides along the radial direction of the outer shell of the compensation target and abuts against the irradiation channel.

[0022] Furthermore, the outer shell of the compensation target is an aluminum shell.

[0023] Furthermore, the fuel filled in the fuel filling area is U-235.

[0024] Furthermore, the average density of the compensation target is less than the density of the coolant.

[0025] Furthermore, the petal-shaped limiter is provided at one end of the compensation target facing the bottom of the reactor pool, and the action knob is provided at the other end of the compensation target.

[0026] Furthermore, the reactor in the reactor pool is a swimming pool-type reactor with an open core.

[0027] Compared with the existing technology, this application has the following beneficial effects:

[0028] The present application provides an online replacement device for irradiation targets in a swimming pool-type reactor, comprising a reactor pool with a reactor accommodated therein, the reactor pool being filled with coolant, a reactor operating bridge being provided at the top edge of the reactor pool, a target driving mechanism and a target hoisting connecting rod being provided on the reactor operating bridge, the target hoisting connecting rod being detachably connected to one end of the irradiation target; a compensation target being provided directly below an irradiation channel in the reactor, the compensation target being filled with helium, a petal-shaped stopper and an action knob for controlling the action of the petal-shaped stopper being provided on the compensation target, the action knob being detachably connected to one end of the target hoisting connecting rod; when the target to be replaced in the irradiation channel is driven out of the irradiation channel by the target hoisting connecting rod, the compensation target enters the irradiation channel under the buoyancy of the coolant, and is fixed to the irradiation channel by the petal-shaped stopper. The swimming pool-type reactor in-core irradiation target online replacement device provided by the present application inserts the target into the irradiation channel in the reactor core from above the reactor core by a target hoisting connecting rod and a target driving mechanism. The irradiation channel is provided with a compensating target with a petal-shaped stopper. During the insertion of the new target, the compensating target is pushed out of the irradiation channel from top to bottom by the new target. During the withdrawal of the old target (i.e., the target to be replaced), the compensating target floats up with the help of the buoyancy of the coolant and eventually stays in the irradiation channel due to the action of the petal-shaped stopper. The petal-shaped stopper on the compensating target can be reset and retracted by adjusting the action knob above. After the stopper is retracted, the compensating target can be withdrawn from the core in the same manner as the old target and then replaced. During the entire target replacement process, the overall reactivity and moderation ratio of the core are not significantly disturbed, so there is no need to shut down and restart the reactor to replace the target. This shortens the target replacement time cycle, improves irradiation efficiency, reduces the complexity of the target replacement operation, and improves operational safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing the present application; for example, based on the technical concepts and exemplary drawings disclosed in this application, those skilled in the art are able to easily make routine adjustments or further optimizations to the addition / reduction / attribution division, specific shapes, positional relationships, connection methods, and dimensional ratios of certain units (components).

[0030] Figure 1This is a schematic structural diagram of an online replacement device for in-core irradiation targets in a swimming pool-type reactor provided by the present application in one embodiment, in an application state. The diagram shows the state where the target to be replaced is pulled out of the irradiation channel and the compensation target enters the irradiation channel under the buoyancy of the coolant;

[0031] Figure 2 This is a schematic diagram showing the state in which the target is fixed in the irradiation channel by the bottom petal-shaped stopper after entering the irradiation channel;

[0032] Figure 3 This is a schematic structural diagram of the online replacement device for in-core irradiation targets of a swimming pool-type reactor provided by the present application in another application state, in one embodiment. This diagram shows the state where a new target is used to eject the compensation target in the irradiation channel;

[0033] Figure 4 This is a schematic structural diagram of a compensation target provided by the present application in a side-section state in one embodiment;

[0034] Figure 5 This is a schematic diagram of the bottom-up structure of the limiter in the compensation target provided by the present application in an embodiment in an open state.

[0035] Description of reference numerals:

[0036] 1. Reactor pool; 2. Coolant; 3. Reactor core; 4. Target to be replaced; 5. Target hoisting rod; 6. Reactor operating bridge; 7. Target drive mechanism; 8. Compensating target; 9. Petal-shaped limiter; 10. Helium filling area; 11. Fuel filling area; 12. Drive rod; 13. Spring; 14. Action knob; 15. Thread; 16. Drive track; 17. Head; 18. Wedge-shaped slider; 19. Outer shell; 20. New target. DETAILED DESCRIPTION

[0037] The present application will be further described below in detail through specific embodiments in conjunction with the accompanying drawings.

[0038] In the description of this application: unless otherwise specified, the meaning of "plurality" is two or more. The terms "first", "second", "third", etc. in this application are intended to distinguish the objects referred to and do not have any special meaning in terms of technical connotation (for example, they should not be understood as emphasizing the importance or order, etc.). Expressions such as "including", "comprising", "having", etc. also mean "not limited to" (certain units, components, materials, steps, etc.).

[0039] Terms such as "upper," "lower," "left," "right," and "center" used in this application are generally intended to facilitate intuitive understanding when compared with the accompanying drawings and are not intended to be absolute limitations on positional relationships in actual products. Changes to these relative positional relationships are considered within the scope of this application without departing from the technical concepts disclosed herein.

[0040] In order to solve the problems existing in the prior art, the present application proposes a solution for online replacement of irradiated targets in a swimming pool reactor. The aforementioned replacement refers to the process of replacing irradiated targets with unirradiated targets.

[0041] In order to realize the above-mentioned online replacement scheme, the present application provides an online replacement device for irradiation targets in a swimming pool-type reactor. The replacement device can replace targets without stopping the reactor, thereby shortening the target replacement cycle and improving the isotope production efficiency, while avoiding the additional operating costs and safety risks caused by frequent shutdown and restart of the reactor.

[0042] The online replacement device provided in this application is applicable to a swimming pool-type reactor with an open core. The specific structure and working principle of the online replacement device are described in detail below with reference to the accompanying drawings.

[0043] like Figure 1 As shown, the swimming pool-type reactor in-core irradiation target online replacement device provided by the present application includes: a reactor pool 1 with a reactor accommodated therein, the reactor pool 1 is filled with coolant 2, a reactor operating bridge 6 is provided at the top edge of the reactor pool 1, a target driving mechanism 7 is provided on the reactor operating bridge 6, the target driving mechanism 7 is connected to the target hoisting connecting rod 5, and the target hoisting connecting rod 5 is detachably connected to one end of the irradiation target; a compensation target 8 is provided directly below the irradiation channel in the reactor, the compensation target 8 is filled with helium, a petal-shaped stopper 9 and an action knob 14 for controlling the action of the petal-shaped stopper are provided on the compensation target 8, and the action knob 14 is detachably connected to one end of the target hoisting connecting rod 5; when the target 4 to be replaced in the irradiation channel is driven out of the irradiation channel by the target hoisting connecting rod 5, the compensation target 8 enters the irradiation channel under the buoyancy of the coolant 2 and is fixed to the irradiation channel by the petal-shaped stopper 9. The power output end of the target driving mechanism 7 is connected to one end of the target hoisting connecting rod 5, and the other end of the target hoisting connecting rod 5 is detachably connected to a new target 20. The new target 20 is located directly above the irradiation channel. Driven by the target hoisting connecting rod 5, the new target 20 enters the irradiation channel vertically downward; when the new target 20 is inserted into the irradiation channel, the compensating target 8 located in the irradiation channel is pushed out of the irradiation channel by the new target 20.

[0044] like Figure 1As mentioned above, this figure shows the state where the target to be replaced is pulled out from the irradiation channel and the compensation target 8 enters the irradiation channel under the buoyancy of the coolant 2. Figure 2 After the compensation target 8 enters the irradiation channel, it is fixed in place by the petal-shaped stopper 9 at the bottom. When the new irradiation target is not inserted into the irradiation channel, the compensation target 8 occupies the internal space of the irradiation channel, so that the moderator inventory and reactivity value introduced into the channel are consistent with those when the standard irradiation target is inserted. Figure 3 When the new target 20 is inserted into the irradiation channel, its lower end contacts the upper end of the compensation target 8, pushing the compensation target 8 out of the reactor core 3. Throughout this process, the overall reactivity and moderation ratio of the core are not significantly disturbed, so there is no need to shut down the reactor in advance for target insertion.

[0045] See also Figure 3 The new target 20 enters and exits the irradiation tunnel from above the reactor core 3. The entry and exit of the new target 20 is driven by the target drive mechanism 7 installed on the reactor operating bridge 6, and the driving force is transmitted through the target hoisting connecting rod 5 connecting the target and the drive mechanism.

[0046] The inventors designed a compensation target based on the standard irradiation target. Figure 4 As shown, the outer shell of compensation target 8 is an aluminum cladding, with a central portion forming a nuclear fuel filling area 11 containing an appropriate amount of low-enriched uranium. The space between outer cladding 19 and fuel filling area 11 is filled with helium, forming a helium filling area 10, which primarily serves to conduct heat and reduce the overall density of compensation target 8.

[0047] The external dimensions of the compensation target 8 provided in this application are completely consistent with those of the irradiation target, and the loading amount of U-235 filled in the fuel filling area 11 needs to be accurately calculated so that the overall reactivity value of the compensation target 8 is equal to that of the standard irradiation target.

[0048] Because the majority of the space within the compensation target 8 is filled with helium, its average density is less than that of the coolant. When replacing the irradiation target, as the target 4 to be replaced is lifted out of the irradiation channel, the compensation target 8 floats upward due to buoyancy and, as the target 4 to be replaced is lifted, gradually reoccupies the space within the irradiation channel. A flap-shaped stopper 9 is provided at the lower end of the compensation target 8. Once the compensation target 8 is placed into the reactor core 3, the actuation knob 14 at its top is rotated clockwise to open the wedge-shaped slider 18 of the flap-shaped stopper 9.

[0049] The working principle of the flap stopper is as follows: Figure 4The upper half of the petal-shaped limiter's transmission rod 12 engages with a transmission track 16 (an internal hole formed in the compensating target, allowing the transmission rod to reciprocate) via a thread 15. Clockwise rotation of the action knob 14 forces the transmission rod 12 downward. A conical plug 17 is provided at the bottom of the transmission rod 12. During its downward movement, the plug 17 pushes away a wedge-shaped slider 18 in sliding contact with the plug 17, thereby driving the limiter to radially expand. The target drive mechanism 7 can drive the target hoisting connecting rod 5 to complete the rotation of the action knob 14. The end of the target hoisting connecting rod 5 connected to the action knob 14 can be provided with a chuck or other structural component that can achieve clamping and releasing actions.

[0050] Once the target 4 to be replaced has been completely removed from the irradiation channel, the compensating target 8 is secured within the channel by the petal-shaped stoppers 9 and cannot rise further. During the entire target replacement process, the core's overall reactivity and moderation ratio remain unchanged, eliminating the need to shut down and restart the reactor for target replacement. This shortens the target replacement cycle, improves irradiation efficiency, reduces the complexity of the target replacement operation, and enhances operational safety.

[0051] It should be noted that since the compensating target 8 contains fissile material, it will be consumed over time in the core neutron field and therefore needs to be replaced after a period of use. To replace the compensating target 8, it is necessary to first rotate the actuating knob 14 of the petal-shaped stopper 9 counterclockwise to move the transmission rod 12 upward. The wedge-shaped slider 18, under the action of the spring 13, returns to the interior of the outer shell 19 of the compensating target 8. After this, the compensating target 8 can be removed from the core by the target hoisting connecting rod 5.

[0052] In summary, the online replacement device for in-core irradiation targets of a swimming pool-type reactor provided by the present application inserts the target from above the reactor core into the irradiation channel inside the core by means of a target hoisting connecting rod and a target driving mechanism. A compensating target with a petal-shaped limiter is provided in the irradiation channel. The geometric dimensions and reactivity value of the compensating target are exactly the same as those of the standard irradiation target. During the insertion of the new target, the compensating target is pushed out of the irradiation channel from top to bottom by the new target. During the extraction of the old target (i.e., the target to be replaced), the compensating target floats up with the help of the buoyancy of the coolant, and finally stays in the irradiation channel due to the action of the petal-shaped limiter. The petal-shaped limiter on the compensating target can be reset and retracted by adjusting the action knob above. After the limiter is retracted, the compensating target can be extracted from the core in the same way as the old target, and then replaced.

[0053] The online replacement device provided in the present application is equipped with a compensating target that can follow the target into and out of the core, and the reactivity value and size of the compensating target are completely consistent with those of the standard irradiation target. Therefore, regardless of whether the target is inside or outside the reactor, the overall reactivity, moderation ratio and core temperature distribution of the reactor remain basically unchanged, and the reactor can maintain normal steady-state operation without the need to perform shutdown and restart operations specifically for target replacement.

[0054] If the compensating target's flotation mechanism or limiter mechanism fails, the compensating rod will sink to the bottom of the pool or float out of the core. In either case, the core reactivity will decrease, forming a negative reactivity feedback loop to ensure core safety.

[0055] The technical features of the above embodiments can be combined arbitrarily (as long as there is no contradiction in the combination of these technical features). In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described; these embodiments that are not explicitly written should also be considered to be within the scope of this specification.

[0056] The present application has been described in a relatively specific and detailed manner through general explanations and specific embodiments. It should be understood that, based on the technical concept of the present application, several conventional adjustments or further innovations may be made to these specific embodiments; however, as long as they do not depart from the technical concept of the present application, the technical solutions obtained by such conventional adjustments or further innovations also fall within the scope of protection of the claims of the present application.

Claims

1. An online replacement device for irradiation targets in a swimming pool type reactor, characterized in that: The reactor comprises a reactor pool containing a reactor, the reactor pool being filled with coolant, a reactor operating bridge being provided at the top edge of the reactor pool, a target driving mechanism being provided on the reactor operating bridge, the target driving mechanism being connected to a target hoisting connecting rod, and the target hoisting connecting rod being detachably connected to one end of an irradiation target; A compensating target is provided directly below the irradiation channel in the reactor, the compensating target being filled with helium and provided with a petal-shaped stopper and an action knob for controlling the movement of the petal-shaped stopper, the action knob being detachably connected to one end of a target hoisting connecting rod; when the target to be replaced in the irradiation channel is driven out of the irradiation channel by the target hoisting connecting rod, the compensating target enters the irradiation channel under the buoyancy of the coolant and is fixed to the irradiation channel by the petal-shaped stopper; The power output end of the target driving mechanism is connected to one end of the target hoisting connecting rod, and the other end of the target hoisting connecting rod is detachably connected to a new target. The new target is located directly above the irradiation channel. Driven by the target hoisting connecting rod, the new target enters the irradiation channel vertically downward; when the new target is inserted into the irradiation channel, the compensating target located in the irradiation channel is pushed out of the irradiation channel by the new target.

2. The online replacement device for in-core irradiation targets of a swimming pool type reactor according to claim 1, characterized in that: The shape and size of the compensation target are respectively the same as those of the target to be replaced; The compensation target has an outer shell, wherein a first cavity and a second cavity adjacent to each other are formed in the outer shell, a transmission track is vertically provided in the first cavity along the direction of the central axis thereof, and an internal thread is formed on the inner wall of the transmission track; A fuel filling area is formed in the first cavity, and the fuel filling area is an annular area arranged along the radial direction of the first cavity; A helium filling area is formed between the inner wall of the first cavity and the outer wall of the transmission track.

3. The online replacement device for in-core irradiation targets of a swimming pool type reactor according to claim 2, characterized in that: The action knob is installed at the end of the transmission track away from the second cavity, and the action knob includes a driving connection end and a connecting column. The outer wall of the connecting column is provided with an external thread that is adapted to engage with the inner wall of the transmission track, and the driving connection end is adapted to be connected to the end of the target lifting connecting rod.

4. The online replacement device for in-core irradiation targets of a swimming pool type reactor according to claim 3, characterized in that: The second cavity forms a mounting position for the petal-shaped stopper; the petal-shaped stopper includes a transmission rod, a head provided at one end of the transmission rod, a wedge-shaped slider slidably connected to the head, and an elastic member for connecting the wedge-shaped slider to the inner wall of the second cavity; The plug is arranged in the second cavity, the other end of the transmission rod is installed in the transmission track, and the end of the transmission rod is connected to the connecting column.

5. The online replacement device for in-core irradiation targets of a swimming pool type reactor according to claim 4, characterized in that: The end of the mandrel facing away from the transmission rod forms a cone, and the central axis of the cone coincides with the central axis of the transmission rod; The plurality of wedge-shaped sliders are evenly distributed radially around the central axis of the cone; The wedge-shaped slider has a first sliding part and a second sliding part. The first sliding part is vertically arranged along the central axis of the transmission rod, and the second sliding rod is horizontally arranged along the radial direction of the transmission rod. The first sliding part is connected to the inner wall of the second cavity through a spring; the second sliding part is slidably connected to the end of the compensation target.

6. The online replacement device for in-core irradiation targets of a swimming pool type reactor according to claim 5, characterized in that: A strip-shaped protrusion is formed on the surface where the second sliding portion connects with the end of the compensation target. The end of the compensation target is provided with a sliding groove adapted to the strip-shaped protrusion. The length extension line of the strip-shaped protrusion is perpendicular to and intersects with the central axis of the transmission rod.

7. The online replacement device for in-core irradiation targets of a swimming pool type reactor according to claim 5, characterized in that: When the compensation target enters the irradiation channel under the buoyancy of the coolant, the target hoisting connecting rod is connected to the action knob on the compensation target. The target driving mechanism rotates the target hoisting connecting rod clockwise, so that the transmission rod moves vertically downward under the drive of the action knob, and then pushes the multiple wedge-shaped sliders apart through the head. The second sliding part of the wedge-shaped slider slides along the radial direction of the outer shell of the compensation target and abuts against the irradiation channel.

8. The online replacement device for in-core irradiation targets of a swimming pool type reactor according to claim 2, characterized in that: The outer shell of the compensation target is an aluminum shell. The fuel filled in the fuel filling area is U-235; The average density of the compensation target is less than the density of the coolant; The petal-shaped stopper is provided at one end of the compensation target facing the bottom of the reactor pool, and the action knob is provided at the other end of the compensation target.

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