Liquid heavy metal cooled microreactor control rod drive mechanism

Abstract

The application discloses a liquid heavy metal cooling micro small reactor control rod drive mechanism which is composed of a motor drive transmission mechanism, an outer cylinder, a supporting cylinder, a rod position measurer, an electromagnetic clutch mechanism, a screw rod connecting rod, a guide pipe and a gas protection system; a speed reducer and a drive motor in the motor drive transmission mechanism are installed upside down at the lower end of a gear transmission box in sequence, a rotating cylinder is coaxially installed in the outer cylinder and is installed at the lower end of the gear transmission box through a connector at the upper end; the rod position measurer is fixedly installed on the outer wall of the outer cylinder; the electromagnetic clutch mechanism is fixedly installed at the lower end of the outer cylinder and the rotating cylinder; the lower end of the screw rod connecting rod is fixedly connected with a control rod, and the upper part is in screw thread cooperation with a ball nut of the electromagnetic clutch mechanism. The single motor and the electromagnetic clutch mechanism are adopted, the liquid heavy metal buoyancy is fully utilized, the spring is assisted, the control rod adjusting and falling rod functions are realized, the height and weight above the top cover are reduced, the metal vapor is avoided from escaping through the gas protection system, the structure is compact, and the safety and reliability are high.

Description

Technical Field

[0001] This invention relates to the field of reactor engineering technology, and more specifically to a control rod drive mechanism for a liquid heavy metal cooled micro-reactor. Background Technology

[0002] Liquid heavy metals (such as lead / lead-bismuth eutectic alloys) possess significant advantages, including low melting points, high boiling points, high heat transfer efficiency, and weak neutron moderation, making them the primary coolant for fast neutron reactors. Lead-based reactors use lead or lead alloys (collectively referred to as lead-based materials) as coolants, offering marked advantages in physical and thermal performance as well as safe operation. Miniature lead-based reactors are currently the main direction of development.

[0003] The reactivity control drive mechanism is a critical safety device in a reactor, responsible for important functions such as reactor startup, power regulation, and safe shutdown. It plays a vital role in ensuring the reactor can shut down and regulate power as required. To guarantee safe reactor operation, reactors employ independent reactivity control systems based on different principles, such as control rods (control drums), chemical compensation, mechanical compensation, and combustible poison control. Among these, the control rod drive mechanism system is the most widely used. Miniature lead-based reactors, due to space, weight, and high-temperature requirements, present new challenges to the control rod drive mechanism. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention provides a control rod drive mechanism for a liquid heavy metal cooled micro reactor, which is characterized by its compact structure, safety and reliability, and adaptability to the high-temperature environment of liquid heavy metal coolant, while significantly reducing the height and weight above the top cover.

[0005] To achieve the above objectives, the present invention proposes the following technical solution:

[0006] A control rod drive mechanism for a liquid heavy metal cooled micro reactor, the drive mechanism comprising a motor drive transmission mechanism, an outer cylinder, a support cylinder, a rod position measuring device, an electromagnetic clutch mechanism, a lead screw connecting rod, a guide tube, and a gas protection system;

[0007] The motor drive transmission mechanism includes a drive motor, a reducer, a gear transmission box, and a rotating drum; the gear transmission box is installed at the top of the outer drum; the reducer and the drive motor are sequentially inverted and installed at the bottom of the gear transmission box, parallel to the outer drum; the rotating drum is coaxially installed inside the outer drum, and its upper end is installed at the bottom of the gear transmission box via a connector;

[0008] The rod position measuring device is fixedly installed on the outer wall of the outer cylinder, with its upper end flush with the connector position;

[0009] The electromagnetic clutch mechanism is fixedly installed at the lower end of the outer cylinder and the rotating cylinder;

[0010] The guide tube is coaxially disposed below the support cylinder, and its lower end is fixedly installed on the lower grid plate;

[0011] The lower end of the lead screw connecting rod is fixedly connected to the control rod and is movably disposed in the rotating drum and guide tube. The upper part is threadedly engaged with the ball nut of the electromagnetic clutch mechanism.

[0012] The gas protection system includes an exhaust port, an inflation port, an upper sealing ring, a middle sealing ring, and a lower sealing ring; the exhaust port is located on the side of the gear transmission box, and the inflation port is located on the outer wall of the support cylinder.

[0013] Furthermore, the electromagnetic clutch mechanism includes an external electromagnet, an internal bracket, a spring, an armature, and a split ball nut; the electromagnet is ring-shaped and installed on the support cylinder step; the bracket is a ring-shaped object with a U-shaped cross section, and its upper end is fixed to the rotating cylinder.

[0014] Furthermore, springs are fixedly installed on both the top and bottom of the inner surface of the bracket, and then an armature and a split ball nut are fixedly installed inward in sequence. The springs, armature and split ball nut form a telescopic module; one telescopic module is evenly arranged circumferentially on the inner surface of the bracket.

[0015] Furthermore, one end of an auxiliary spring is fixedly installed on the upper surface of the bracket, the auxiliary spring is sleeved on the lead screw connecting rod, and the other end of the auxiliary spring is a movable end.

[0016] Furthermore, a clamping cover is fixedly installed on the upper end of the lead screw connecting rod. When the lead screw connecting rod moves downward, the clamping cover contacts and compresses the auxiliary spring.

[0017] Furthermore, the rod position measuring device has a split structure, including a signal cable, a converter, a measuring rod, and a magnetic block; the magnetic block is fixedly installed on the clamping cover and can move up and down together with the lead screw connecting rod.

[0018] Furthermore, a limiting block is provided at the upper end of the rotating drum. When the pressing cover contacts the limiting block, the lead screw reaches the highest position and stops moving upward, and the lower control rod returns to the core position.

[0019] Furthermore, the support cylinder is connected to the upper cover plate via a flange located at its lower part, and a sealing and heat insulation layer is provided inside the support cylinder; the support cylinder is connected to the upper end of the guide tube via 2 to 4 positioning pins circumferentially fixed to its lower end face.

[0020] Furthermore, a ring of drain holes is provided near the upper end of the guide tube. When the lead screw and connecting rod drive the control rod to move upward, the liquid metal in the guide tube is discharged outward through the drain holes.

[0021] Furthermore, a buffer is provided at the lower end of the guide tube to prevent the control rod from falling and impacting the system when there is no coolant; a protruding fixing block is provided on the inner wall of the guide tube; and an elongated groove is provided on the lower part of the lead screw connecting rod to cooperate with the fixing block and restrict the circumferential rotation of the lead screw connecting rod.

[0022] The control rod drive mechanism has a sealed cavity inside. Furthermore, the protective gas filled into the gas protection system is an inert gas with a pressure higher than that of the metal vapor in the reactor, to prevent the metal vapor from escaping into the upper cavity.

[0023] Furthermore, the inert gas is argon.

[0024] The advantages of this invention compared to the prior art are:

[0025] 1) This invention utilizes the buoyancy of liquid heavy metals through a single inverted motor drive mechanism, an electromagnetic armature attraction mechanism, and an electromagnetic clutch mechanism that controls the opening and closing of the nut with a spring. With the assistance of a spring, it realizes the function of controlling the up and down movement of the control rod and the dropping of the rod. The structure is compact, safe and reliable, and effectively reduces the height and weight above the top cover, making it more suitable for use in micro-small reactors.

[0026] 2) The split-type magnetostrictive rod position measurement scheme overcomes the influence of high temperature. Combined with motor stroke detection, it can accurately detect the real-time position of the drive shaft, thus improving the accuracy of the operation of this invention.

[0027] 3) An inert gas protection system is provided to prevent metal vapor from escaping into the control rod drive mechanism cavity, thereby improving the safety of the device of this invention. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0029] Figure 1 A schematic diagram of the overall structure of a control rod drive mechanism for a liquid heavy metal cooled micro-reactor;

[0030] Figure 2 This is a schematic diagram of a control rod drive mechanism for a liquid heavy metal cooled micro-reactor after the control rods have entered the reactor core.

[0031] Figure 3 This is a structural diagram of the electromagnetic clutch mechanism of a control rod drive mechanism for a liquid heavy metal cooled micro-reactor.

[0032] The symbols in the attached figures represent the following: 1. Drive motor; 2. Reducer; 3. Upper sealing ring; 4. Gear transmission box; 5. Air outlet; 6. Connector; 7. Rod position measuring device; 8. Limit block; 9. Electromagnetic clutch mechanism; 10. Outer cylinder; 11. Rotary cylinder; 12. Pressing cover; 13. Auxiliary spring; 14. Lead screw connecting rod; 15. Middle sealing ring; 16. Air inlet; 17. Sealing and heat insulation layer; 18. Support cylinder; 19. Top cover plate; 20. Positioning pin; 21. Guide tube; 22. Drain hole; 23. Fixing block; 24. Control rod; 25. Buffer; 26. Lower grid plate; 27. Lower sealing ring; 701. Signal cable; 702. Converter; 703. Measuring rod; 704. Magnetic block; 901. Electromagnet; 902. Bracket; 903. Spring; 904. Armature; 905. Ball nut. Detailed Implementation

[0033] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are within the scope of protection of the present invention.

[0034] Example 1:

[0035] like Figures 1-2 As shown, the control rod drive mechanism for a liquid heavy metal cooled micro-reactor of the present invention consists of a motor drive transmission mechanism, an outer cylinder 10, a support cylinder 18, a rod position measuring device 7, an electromagnetic clutch mechanism 9, a lead screw connecting rod 14, a guide tube 21, and a gas protection system.

[0036] The motor-driven transmission mechanism includes a drive motor 1, a reducer 2, a gear transmission box 4, and a rotating drum 11. The gear transmission box 4 is installed at the top of the outer cylinder 10. The reducer 2 and the drive motor 1 are sequentially inverted and installed at the lower end of the gear transmission box 4, parallel to the outer cylinder 10. The rotating drum 11 is coaxially installed inside the outer cylinder 10, and its upper end is installed at the lower end of the gear transmission box 4 via a connector 6. The rod position measuring device 7 is fixedly installed on the outer wall of the outer cylinder 10, and its upper end is flush with the position of the connector 6. The electromagnetic clutch mechanism 9 is fixedly installed at the lower ends of the outer cylinder 10 and the rotating drum 11. The guide tube 21 is coaxially arranged below the support cylinder 18, and its lower end is fixedly installed on the lower grid plate 26. The lower end of the lead screw connecting rod 14 is fixedly connected to the control rod 24, and is movably arranged inside the rotating drum 11 and the guide tube 21. Its upper part is threadedly engaged with the ball nut 905 of the electromagnetic clutch mechanism 9.

[0037] The support cylinder 18 is connected to the upper cover plate 19 via a flange located at its lower part. A sealing and heat insulation layer 17 is provided inside the support cylinder 18. Two to four positioning pins 20 are fixedly installed on the lower end face of the support cylinder 18 and connected to the upper end of the guide tube 21.

[0038] A ring of drain holes 22 is provided near the upper end of the guide tube 21. When the lead screw 14 drives the control rod 24 to move upward, the liquid metal in the guide tube 21 is discharged outward through the drain holes 22.

[0039] The guide tube 21 is provided with a buffer 25 at its lower end and a fixed stop 23 protrusion on its inner wall; the lower part of the lead screw 14 is provided with a long strip groove, which cooperates with the fixed stop 23 to restrict the circumferential rotation of the lead screw 14.

[0040] An auxiliary spring 13 is fixedly installed on the upper surface of the electromagnetic clutch mechanism 9. The auxiliary spring 13 is sleeved on the lead screw connecting rod 14, and the other end is a movable end.

[0041] The upper end of the lead screw connecting rod 14 is fixedly installed with a clamping cover 12. When the lead screw connecting rod 14 moves downward, the clamping cover 12 contacts and compresses the auxiliary spring 13.

[0042] A limiting block 8 is provided at the upper end of the inner drum 11. When the pressing cover 12 contacts the limiting block 8, the lead screw connecting rod 14 reaches the highest position and stops moving upward.

[0043] The working principle of this embodiment is as follows:

[0044] Up and down movement steps: The electromagnetic clutch mechanism 9 locks the lead screw connecting rod 14, the motor drives the transmission mechanism to drive the lead screw connecting rod 14 to move up and down, the lead screw connecting rod 14 drives the control rod 24 to move up and down, so that the control rod 24 stops at the predetermined position;

[0045] Control rod descent steps: After the core is loaded, the electromagnetic clutch mechanism 9 locks the lead screw 14, and the motor-driven transmission mechanism drives the lead screw 14 to move downward to the lowest end, and the pressure cover 12 compresses the auxiliary spring 13 to the maximum preload.

[0046] Rapid rod dropping procedure: When the control rod 24 is below the core, the electromagnetic clutch mechanism 9 releases the lead screw connecting rod 14, the auxiliary spring 13 returns to its original state and releases the preload. Under the action of buoyancy and elasticity, the lead screw connecting rod 14 drives the control rod 24 to move rapidly upward to the top, and the control rod 24 is inserted into the core.

[0047] Stop and refueling procedure: The motor drives the transmission mechanism to move the lead screw 14 upward to the top, the control rod 24 is inserted into the core, and the electromagnetic clutch mechanism 9 releases the lead screw 14.

[0048] Example 2:

[0049] like Figure 3 As shown, the electromagnetic clutch mechanism 9 includes an external electromagnet 901, an internal bracket 902, a spring 903, an armature 904, and a split ball nut 905; the electromagnet 901 is ring-shaped and is installed on the steps of the support cylinder 18; the bracket 902 is a ring with a U-shaped cross section, and its upper end is fixed to the rotating cylinder 11.

[0050] Springs 903 are fixedly installed on the inner surface of the bracket 902, and then armature 904 and split ball nut 905 are fixedly installed in sequence. The springs 903, armature 904 and split ball nut 905 form a telescopic module. Two to four telescopic modules are evenly arranged circumferentially on the inner surface of the bracket 902.

[0051] The external electromagnet 901 is a combination of a permanent magnet and an electromagnet. When energized, the electromagnet 901 cancels the magnetic force of the internal permanent magnet and has no attraction to the armature 904. The split ball nut 905 is tightened under the action of the spring 903 to complete the transmission with the lead screw 14. When de-energized, the permanent magnet inside the electromagnet 901 attracts the armature 904, overcomes the spring force, and the split ball nut 905 opens, releasing the lead screw 14 and the control rod 24.

[0052] Example 3:

[0053] like Figures 1-2 As shown, the rod position measuring device 7 has a split structure, including a signal cable 701, a converter 702, a measuring rod 703, and a magnetic block 704. The magnetic block 704 is fixedly installed on the clamping cover 12 and can move up and down together with the lead screw connecting rod 14. The converter 702 converts the position information of the magnetic block 704 obtained by the measuring rod 703 and transmits it out through the signal cable 701.

[0054] Example 4:

[0055] like Figures 1-2 As shown, the gas protection system includes an exhaust port 5, an inflation port 16, an upper sealing ring 3, a middle sealing ring 15, and a lower sealing ring 27. The exhaust port 5 is located on the side of the gear transmission box 4, and the inflation port 16 is located on the outer wall of the support cylinder 18. Through the above-mentioned components, a sealed cavity is formed inside the main body of the control rod drive mechanism. The protective gas filled into the cavity is an inert gas, such as argon, and the gas pressure is higher than the metal vapor pressure inside the reactor, preventing metal vapor from escaping into the upper cavity and protecting the components inside the cavity.

[0056] Although the illustrative specific embodiments of the present invention have been described above to enable those skilled in the art to understand the invention, it should be understood that the invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes will be obvious as long as they are within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of the present invention are protected.

Claims

1. A control rod drive mechanism for a liquid heavy metal cooled micro-reactor, the drive mechanism comprising a motor drive transmission mechanism, an outer cylinder (10), a support cylinder (18), a rod position measuring device (7), an electromagnetic clutch mechanism (9), a lead screw connecting rod (14), a guide tube (21), and a gas protection system, characterized in that: The motor drive transmission mechanism includes a drive motor (1), a reducer (2), a gear transmission box (4), and a rotating drum (11); the gear transmission box (4) is installed at the top of the outer cylinder (10); the reducer (2) and the drive motor (1) are installed invertedly at the lower end of the gear transmission box (4) in sequence, parallel to the outer cylinder (10); the rotating drum (11) is coaxially installed inside the outer cylinder (10), and its upper end is installed at the lower end of the gear transmission box (4) through a connector (6); The rod position measuring device (7) is fixedly installed on the outer wall of the outer cylinder (10), with its upper end flush with the connector (6); The electromagnetic clutch mechanism (9) is fixedly installed at the lower end of the outer cylinder (10) and the rotating cylinder (11); The guide tube (21) is coaxially arranged below the support cylinder (18), and its lower end is fixedly installed on the lower grid plate (26); The lower end of the lead screw connecting rod (14) is fixedly connected to the control rod (24), and is movably disposed in the rotating drum (11) and the guide tube (21). The upper part is threadedly engaged with the ball nut (905) of the electromagnetic clutch mechanism (9). The gas protection system includes an exhaust port (5), an inflation port (16), an upper sealing ring (3), a middle sealing ring (15), and a lower sealing ring (27); the exhaust port (5) is located on the side of the gear transmission box (4), and the inflation port (16) is located on the outer wall of the support cylinder (18); The electromagnetic clutch mechanism (9) includes an external electromagnet (901), an internal bracket (902), a spring (903), an armature (904), and a split ball nut (905); the electromagnet (901) is ring-shaped and installed on the step of the support cylinder (18); the bracket (902) is a ring with a U-shaped cross section, and its upper end is fixed to the rotating cylinder (11); Springs (903) are fixedly installed on both the top and bottom of the inner surface of the bracket (902), and then an armature (904) and a split ball nut (905) are fixedly installed inward in sequence. The springs (903), armatures (904) and split ball nuts (905) form a telescopic module. Two to four telescopic modules are evenly arranged circumferentially on the inner surface of the bracket (902).

2. The control rod drive mechanism for a liquid heavy metal cooled micro-reactor according to any one of claims 1, characterized in that: One end of the auxiliary spring (13) is fixedly installed on the upper surface of the bracket (902). The auxiliary spring (13) is sleeved on the lead screw connecting rod (14). The other end of the auxiliary spring (13) is the movable end.

3. The control rod drive mechanism for a liquid heavy metal cooled micro-reactor according to claim 2, characterized in that: The upper end of the lead screw connecting rod (14) is fixedly installed with a pressure cover (12). When the lead screw connecting rod (14) moves downward, the pressure cover (12) contacts and compresses the auxiliary spring (13).

4. The control rod drive mechanism for a liquid heavy metal cooled micro-reactor according to claim 1, characterized in that: The rod position measuring device (7) is a split structure, including a signal cable (701), a converter (702), a measuring rod (703) and a magnetic block (704); the magnetic block (704) is fixedly installed on the pressure cover (12) and can move up and down together with the lead screw connecting rod (14).

5. The control rod drive mechanism for a liquid heavy metal cooled micro-reactor according to claim 1, characterized in that: A limiting block (8) is provided at the upper end of the inner drum (11). When the pressing cover (12) contacts the limiting block (8), the lead screw connecting rod (14) reaches the highest position and stops moving upward.

6. The control rod drive mechanism for a liquid heavy metal cooled micro-reactor according to claim 1, characterized in that: The support cylinder (18) is connected to the top cover plate (19) through a flange provided in its lower part. A sealing and heat insulation layer (17) is provided inside the support cylinder (18). The support cylinder (18) is connected to the upper end of the guide tube (21) through 2 to 4 positioning pins (20) fixedly installed on its lower end face.

7. A control rod drive mechanism for a liquid heavy metal cooled micro-reactor according to claim 1 or 6, characterized in that: A ring of drain holes (22) is provided near the upper end of the guide tube (21). When the lead screw connecting rod (14) drives the control rod (24) to move upward, the liquid metal in the guide tube (21) is discharged outward through the drain holes (22).

8. The control rod drive mechanism for a liquid heavy metal cooled micro-reactor according to claim 7, characterized in that: A buffer (25) is provided at the lower end of the guide tube (21), and a protruding fixed block (23) is provided on the inner wall of the guide tube (21); a long strip groove is provided on the lower part of the lead screw connecting rod (14), which cooperates with the fixed block (23) to restrict the circumferential rotation of the lead screw connecting rod (14).

9. The control rod drive mechanism for a liquid heavy metal cooled micro-reactor according to claim 1, characterized in that: The protective gas supplied to the gas protection system is an inert gas, and the pressure of the inert gas is higher than the pressure of the metal vapor inside the reactor.

10. The control rod drive mechanism for a liquid heavy metal cooled micro-reactor according to claim 9, characterized in that: The inert gas is argon.

Images