Reactor control rod drive mechanism

Abstract

The application provides a reactor control rod drive mechanism, which comprises a winding drum assembly, a drive module, a ball screw and a positioning shaft. The winding drum assembly is provided with a winding drum, a traction rope is wound on the winding drum, and the traction rope is connected with a control rod; the drive module is connected with the winding drum assembly and drives the winding drum to rotate; the ball screw penetrates through the winding drum horizontally, and the winding drum rotates around the ball screw; the ball screw is provided with a nut, the nut is fixed on the winding drum and rotates with the winding drum, and the nut is in threaded cooperation with the ball screw; the positioning shaft is coaxial with the ball screw; the winding drum is provided with a positioning groove, the positioning groove is spiral and surrounds the rotating shaft of the winding drum, and the traction rope is arranged in the positioning groove. The above-mentioned reactor control rod drive mechanism is arranged horizontally, thereby reducing the required vertical installation space; the winding drum is matched with the ball screw, so that the rotating speed of the winding drum is adjustable and the movement of the control rod is stable; the buffer and the buffer assembly are pure mechanical structures, the falling of the control rod is buffered, and the drive mechanism is suitable for a high-temperature environment.

Description

TECHNICAL FIELD

[0001] The present application relates to a reactor control rod drive mechanism. BACKGROUND

[0002] With the rapid increase of energy demand in China, the energy gap is expanding, clean, safe and efficient advanced nuclear energy is an effective solution to China's energy problem, and vigorously developing nuclear energy is an important direction for future energy structure adjustment and optimization in China. The reactor is a device that enables the controlled continuation of atomic nuclear fission reactions. The control rod drive mechanism is an important safety device of the reactor, mainly composed of a drive mechanism and a control rod, which realizes the start, power regulation, power compensation and shutdown of the reactor under normal conditions by manipulating the position of the control rod in the core under normal conditions. In the reactor accident condition, the control rod drive mechanism is powered off, and the control rod is inserted into the core by gravity within a specified time to achieve emergency shutdown of the reactor.

[0003] The CEFR sodium-cooled fast reactor and the early pressurized water reactor use a screw-nut pair as the control rod drive mechanism, the AVR ball bed high temperature gas cooled experimental reactor in Germany uses a gear and rack drive form, and the AP1000 uses magnetic lifting. The characteristics of these three drive mechanisms are high control precision, but they are not suitable for high temperature environment, and the processing, manufacturing and assembly are difficult, require a large vertical installation space, and cannot realize speed adjustment. At the same time, the control rod has a large impact during the drop, and most of them use liquid buffer, which is not suitable for high temperature and gaseous conditions.

[0004] In recent years, small modular reactors have become a research hotspot in the field of nuclear reactors due to their compact design, high inherent safety and flexible application scenarios, and are considered to be used to meet the energy supply of some special fields. Traditional drive mechanisms are mostly steel transmission, which requires a large installation space, and cannot provide a reusable buffer device in a high-temperature gaseous environment. In view of the problem of limited installation space and the use of high-temperature environment, the traditional drive mechanism is not suitable, so it is necessary to propose a new type of control rod drive mechanism. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the defects of the prior art reactor control rod drive mechanism, such as large vertical space occupation, non-adjustable speed, poor buffer effect when the control rod drops, and unsuitable for high temperature environment, and to provide a reactor control rod drive mechanism, which has the advantages of less vertical space occupation, adjustable speed, smooth control rod movement, reduced control rod drop impact, and suitable for high temperature environment.

[0006] The present application solves the above technical problems by the following technical solutions:

[0007] The application provides a reactor control rod drive mechanism, characterized in that the drive mechanism comprises:

[0008] A winding drum assembly is provided with a traction rope wound thereon, the traction rope being connected with a control rod; the winding drum assembly is provided with a winding drum;

[0009] A drive module is connected with the winding drum assembly and drives the winding drum to rotate;

[0010] A ball screw is horizontally arranged through the winding drum, the winding drum rotates around the ball screw; a nut is arranged on the ball screw, the nut is fixed on the winding drum; the nut rotates with the winding drum, and the nut is threadedly connected with the ball screw;

[0011] A positioning shaft is coaxial with the ball screw and connected with the ball screw;

[0012] The winding drum is provided with a positioning groove, the positioning groove is spiral-shaped and surrounds the rotation axis of the winding drum, and the traction rope is arranged in the positioning groove.

[0013] In the technical scheme, the drive module drives the winding drum to rotate, so that the traction rope moves with the winding drum, drives the control rod to ascend and descend, and the speed of the control rod can be adjusted by controlling the rotation speed of the winding drum; when the nut rotates on the ball screw, the winding drum moves horizontally along the axis direction of the ball screw, cooperates with the spiral-shaped positioning groove, so that the traction rope is always kept vertical, prevents the traction rope from winding, and keeps the control rod always in a stable state.

[0014] Preferably, the winding drum assembly further comprises a first rotating wheel, a second rotating wheel and guide columns; the drive module is connected with the first rotating wheel; one end of the guide column is connected with the first rotating wheel, and the other end of the guide column extends into the winding drum and is connected with the second rotating wheel; the first rotating wheel and the second rotating wheel are coaxial with the winding drum.

[0015] In the technical scheme, the first rotating wheel drives the second rotating wheel and the winding drum to rotate through the guide column, the guide column is fixed between the first rotating wheel and the second rotating wheel, so that the guide column cannot move relatively in the horizontal direction, and the rotation is stably transmitted.

[0016] Preferably, the number of the guide columns is three, and the guide columns are uniformly distributed in the circumferential direction of the winding drum.

[0017] In the technical scheme, the plurality of guide columns are uniformly distributed on the winding drum, so that the rotation is uniformly transmitted to the winding drum and drives the winding drum to rotate stably.

[0018] Preferably, a bearing is arranged at the position where the winding drum is connected with the guide column.

[0019] The bearing is arranged to reduce friction when the winding drum moves, so that the horizontal movement of the winding drum is smooth and smooth.

[0020] Preferably, the driving module comprises a transmission assembly and a power assembly; the transmission assembly is coaxial with and connected to the winding drum; and the power assembly is connected to the transmission assembly.

[0021] In the technical solution, the transmission assembly drives the winding drum to rotate and is in the same horizontal plane as the winding drum, thereby saving installation space in the vertical direction.

[0022] Preferably, the transmission assembly is an electromagnetic clutch, which comprises a stator and left and right rotors; the left rotor is connected to the power assembly; and the right rotor is connected to the winding drum assembly.

[0023] When the electromagnetic clutch is powered on, the left rotor is connected to the right rotor; and when the electromagnetic clutch is powered off, the left rotor is disconnected from the right rotor.

[0024] In the technical solution, the electromagnetic clutch connects the power assembly and the winding drum assembly; when the electromagnetic clutch is powered off, the control rod falls due to gravity, thereby achieving emergency rod dropping.

[0025] Preferably, the winding drum assembly further comprises a buffer assembly, which is arranged on the ball screw; the buffer assembly is located at one end of the ball screw pointed by the horizontal movement of the nut when the control rod is in emergency rod dropping; and the ball screw penetrates through the buffer assembly.

[0026] The side of the buffer assembly facing the nut is provided with a contact surface; when the control rod is in emergency rod dropping, the nut abuts against the contact surface.

[0027] The ball screw is provided with a stepped surface; the diameter of the ball screw at the end of the stepped surface away from the buffer assembly is greater than the diameter of the ball screw at the end close to the buffer assembly; when the buffer assembly does not abut against the nut, the buffer assembly contacts the stepped surface and exerts a force on the ball screw in a direction away from the buffer assembly.

[0028] In the technical solution, when the control rod is in emergency rod dropping, the nut contacts the buffer assembly; the buffer assembly exerts a force on the nut in a direction opposite to the movement direction, buffers the impact force of the winding drum, and avoids damage to the winding drum.

[0029] Preferably, the inside of the buffer assembly is sequentially provided with an end cover, a spring, a thrust bearing and a retainer ring in the horizontal direction; one end of the spring is abutted on the end cover, and the other end is abutted on the thrust bearing; the thrust bearing is located between the retainer ring and the spring, and the lower ring of the thrust bearing is installed in the inner hole of the retainer ring; the retainer ring is located at the end of the buffer assembly close to the nut and extends out of the buffer assembly.

[0030] In the technical solution, when the control rod is in emergency drop, the retainer ring contacts the nut, so that the spring is compressed, thereby playing a buffering role on the winding drum; the thrust bearing separates the retainer ring from the spring and drives the retainer ring to rotate with the nut, thereby avoiding the frictional locking between the nut and the retainer ring.

[0031] Preferably, the end surface of the winding drum is provided with a compression sleeve connected with the winding drum; the compression sleeve is internally provided with an elastic element and a small ball, one end of the elastic element is connected with the small ball, and the other end is connected with the compression sleeve; the buffer assembly is provided with a stop groove, and when the winding drum moves to the horizontal limit position in emergency drop, the small ball falls into the stop groove.

[0032] In the technical solution, when the winding drum moves to the limit position in emergency drop, the small ball cooperates with the stop groove to cause a certain resistance to the winding drum, thereby avoiding the damage of the winding drum caused by the sharp rebound of the buffer assembly.

[0033] Preferably, the driving mechanism further comprises a compression roller assembly located above the side of the winding drum, and the compression roller assembly comprises a compression roller in contact with the traction rope.

[0034] In the technical solution, the compression roller contacts the traction rope and presses the traction rope on the winding drum, thereby avoiding the winding and accumulation of the traction rope.

[0035] Preferably, the number of the compression rollers is two, and the two compression rollers are parallel to the ball screw and are respectively pressed on the two sides of the winding drum.

[0036] In the technical solution, the two parallel compression rollers ensure that the traction rope is always in contact with the winding drum when the winding drum moves, and at the same time, ensure that the traction rope does not come out of the positioning groove.

[0037] Preferably, the driving mechanism further comprises a guide assembly located between the winding drum and the control rod, and the traction rope passes through the guide assembly; the guide assembly comprises a first guide wheel, a second guide wheel and a limiting column; the installation position of the first guide wheel is higher than that of the second guide wheel; the first guide wheel and the second guide wheel are provided with guide grooves, and the traction rope moves in the guide grooves; the limiting column is located above the second guide wheel and in contact with the traction rope.

[0038] In the technical solution, the traction rope passes through the guide assembly, so that the traction rope is always kept vertical and taut between the winding drum and the control rod, avoiding deviation of the traction rope movement.

[0039] Preferably, the driving mechanism further comprises a rod position measuring assembly connected with the winding drum assembly; the measuring assembly comprises a phase angle measuring device fixed on a support and connected with the winding drum assembly through a gear pair linkage and rotates with the winding drum.

[0040] In the technical solution, the rotation angle of the winding drum can be calculated according to the rotation angle of the phase angle measuring device when it rotates with the winding drum, and the movement of the winding drum can be measured by outputting the measured phase angle change.

[0041] Preferably, the driving mechanism further comprises a support cylinder located below the winding drum, the support cylinder is hollow, and the traction rope vertically extends into the support cylinder and moves up and down in the support cylinder to drive the control rod to ascend and descend in the support cylinder.

[0042] In the technical solution, the support cylinder limits the movement direction of the traction rope and the control rod, so that they can only move up and down in the vertical direction.

[0043] Preferably, a buffer is arranged in the support cylinder and fixed at the bottom of the support cylinder.

[0044] In the technical solution, the control rod contacts the buffer when it falls in an emergency, thereby buffering the impact caused by the emergency falling of the control rod.

[0045] Preferably, the driving mechanism further comprises a one-way flywheel assembly connected with the winding drum and rotating with the winding drum.

[0046] In the technical solution, most of the kinetic energy of the winding drum when it falls in an emergency is transferred to the one-way flywheel assembly, and when the winding drum is reset, the kinetic energy transferred to the one-way flywheel assembly is consumed, greatly reducing the kinetic energy obtained by the winding drum and avoiding the sharp rise of the control rod.

[0047] On the basis of conforming to the common sense in the art, the above-mentioned preferred conditions can be combined arbitrarily, that is, the preferred examples of the present application are obtained.

[0048] The positive progress effect of the present application is that:

[0049] The above-mentioned reactor control rod driving mechanism, through the horizontal arrangement of the driving module and the winding drum, occupies less vertical installation space; through the cooperation of the winding drum and the ball screw, the rotation speed of the winding drum is adjustable and the movement of the control rod is stable; through the setting of the buffer and the buffer assembly of pure mechanical structure, the impact of the falling control rod is reduced, and the driving mechanism is suitable for high temperature environment. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 Structure diagram of the reactor control rod drive mechanism of the embodiment of the present application.

[0051] Figure 2 Exploded view of the reactor control rod drive mechanism of the embodiment of the present application.

[0052] Figure 3 Partial sectional view of the reactor control rod drive mechanism of the embodiment of the present application.

[0053] Figure 4 Structure diagram of the drive module of the drive mechanism shown in the figure. Figure 3 Sectional view of the transmission assembly of the drive mechanism shown in the figure.

[0054] Figure 5 Structure diagram of the winding drum assembly of the drive mechanism shown in the figure. Figure 3 Sectional view of the winding drum assembly of the drive mechanism shown in the figure.

[0055] Figure 6 Structure diagram of the pressure roller assembly of the drive mechanism shown in the figure. Figure 3 Structure diagram of the guide assembly of the drive mechanism shown in the figure.

[0056] Figure 7 Structure diagram of the measurement assembly of the drive mechanism shown in the figure. Figure 3 Structure diagram of the measurement assembly of the drive mechanism shown in the figure.

[0057] Figure 8 Structure diagram of the measurement assembly of the drive mechanism shown in the figure. Figure 3 Structure diagram of the measurement assembly of the drive mechanism shown in the figure.

[0058] BRIEF DESCRIPTION OF DRAWINGS

[0059] Drive module 1, power assembly 11, transmission assembly 12, left rotor 121, right rotor 122, stator 123;

[0060] Winding drum assembly 2, winding drum 21, positioning groove 211, first rotating wheel 22, second rotating wheel 23, guide column 24, ball screw 25, stepped surface 251, nut 26, positioning shaft 27, buffer assembly 28, end cover 281, spring 282, thrust bearing 283, stop ring 284, stop groove 285, contact surface 286, compression sleeve 29, elastic element 291, ball 292;

[0061] Pressure roller assembly 3, pressure roller 31;

[0062] Guide assembly 4, first guide wheel 41, second guide wheel 42, limiting column 43, guide groove 44;

[0063] Measurement assembly 5, phase angle measurement device 51;

[0064] Supporting cylinder 6, buffer 61;

[0065] One-way flywheel assembly 7;

[0066] Towing rope 8;

[0067] Control rod 9. DETAILED DESCRIPTION

[0068] The application will be further described by way of examples without thereby limiting the application to the examples described.

[0069] As Figures 1 to 3 The embodiment of the reactor control rod drive mechanism of the application is shown. The reactor control rod drive mechanism comprises a drive module 1, a winding drum assembly 2, a ball screw 25 and a positioning shaft 27; the winding drum assembly 2 is wound with a towing rope 8 connected with a control rod 9; the winding drum assembly 2 is provided with a winding drum 21; the drive module 1 is connected with the winding drum assembly 2 and drives the winding drum 21 to rotate; the ball screw 25 horizontally penetrates the winding drum 21, and the winding drum 21 rotates around the ball screw 25; the ball screw 25 is provided with a nut 26 fixed on the winding drum 21; the nut 26 rotates with the winding drum 21, and the nut 26 is threadedly connected with the ball screw 25; the positioning shaft 27 is coaxial with the ball screw 25 and connected with the ball screw 25; the winding drum 21 is provided with a positioning groove 211 which is helical and surrounds the rotation axis of the winding drum 21, and the towing rope 8 is arranged in the positioning groove 211. The drive module 1 drives the winding drum 21 to rotate, so that the towing rope 8 moves with the winding drum 21, drives the control rod 9 to ascend and descend, and the speed of the control rod 9 can be adjusted by controlling the rotation speed of the winding drum 21; the nut 26 drives the winding drum 21 to move horizontally along the axis of the ball screw 25 when the nut 26 rotates on the ball screw 25, cooperates with the positioning groove 211, so that the towing rope 8 always keeps vertical, prevents the towing rope 8 from winding, and keeps the control rod 9 always in a stable state.

[0070] The winding drum assembly 2 further comprises a first rotating wheel 22, a second rotating wheel 23 and a guide column 24; the drive module 1 is connected with the first rotating wheel 22; one end of the guide column 24 is connected with the first rotating wheel 22, and the other end extends into the winding drum 21 and is connected with the second rotating wheel 23; the first rotating wheel 22 and the second rotating wheel 23 are coaxial with the winding drum 21. The first rotating wheel 22 drives the second rotating wheel 23 and the winding drum 21 to rotate through the guide column 24; the guide column 24 is fixed between the first rotating wheel 22 and the second rotating wheel 23, so that the guide column 24 cannot move relatively in the horizontal direction, and the rotation is stably transmitted.

[0071] The number of the guide columns 24 is three, and they are uniformly distributed on the circumference of the winding drum 21, so that the rotation is uniformly transmitted to the winding drum 21 and drives the winding drum 21 to rotate stably.

[0072] The inner part of the winding drum 21 is provided with a bearing at the joint with the guide column 24, so that the friction of the movement of the winding drum 21 is reduced, and the horizontal movement of the winding drum 21 is smooth and stable.

[0073] The driving module 1 comprises a transmission assembly 12 and a power assembly 11; the transmission assembly 12 is coaxial with and connected to the winding drum 21; the power assembly 11 is connected to the transmission assembly 12. The transmission assembly 12 drives the rotation of the winding drum 21, and is in the same horizontal plane as the winding drum 21, thereby saving the installation space in the vertical direction.

[0074] As shown in Figure 4 , the transmission assembly 12 is an electromagnetic clutch, which comprises a stator 123 and left and right rotors 121 and 122; the left rotor 121 is connected to the power assembly 11, and the right rotor 122 is connected to the winding drum assembly 2; when the electromagnetic clutch is powered on, the left rotor 121 is connected to the right rotor 122; when the electromagnetic clutch is powered off, the left rotor 121 is disconnected from the right rotor 122. The electromagnetic clutch connects the power assembly 11 and the winding drum assembly 2, and when the electromagnetic clutch is powered off, the control rod 9 falls due to gravity, thereby realizing the emergency rod drop.

[0075] As shown in Figure 5 , the winding drum assembly 2 further comprises a buffer assembly 28, which is arranged on the ball screw 25; the buffer assembly 28 is located at one end of the ball screw 25 to which the horizontal movement of the nut 26 points when the control rod 9 is in the emergency rod drop, and the ball screw 25 penetrates the buffer assembly 28; the side of the buffer assembly 28 facing the nut 26 is provided with a contact surface 286, and the nut 26 abuts against the contact surface 286 when the control rod 9 is in the emergency rod drop; the ball screw 25 is provided with a stepped surface 251, and the diameter of the ball screw 25 at the end of the stepped surface 251 away from the buffer assembly 28 is greater than that at the end close to the buffer assembly 28; when the buffer assembly 28 is not in abutment with the nut 26, it is in contact with the stepped surface 251 and exerts a force on the ball screw 25 in the direction away from the buffer assembly 28. When the control rod 9 is in the emergency rod drop, the nut 26 contacts the buffer assembly 28, the buffer assembly 28 exerts a force on the nut 26 in the opposite direction of the movement, thereby buffering the impact force of the winding drum 21 and avoiding damage to the winding drum 21.

[0076] The inside of the buffer assembly 28 is sequentially provided with an end cover 281, a spring 282, a thrust bearing 283 and a check ring 284 in the horizontal direction; one end of the spring 282 abuts against the end cover 281, and the other end abuts against the thrust bearing 283; the thrust bearing 283 is located between the check ring 284 and the spring 282, and the lower ring of the thrust bearing 283 is mounted in the inner hole of the check ring 284; the check ring 284 is located at one end of the buffer assembly 28 close to the nut 26 and extends out of the buffer assembly 28. When the control rod 9 falls in emergency, the check ring 284 contacts the nut 26, so that the spring 282 is compressed, thereby playing a buffering role on the winding drum 21; the thrust bearing 283 separates the check ring 284 from the spring 282 and drives the check ring 284 to rotate with the nut 26, avoiding the frictional locking between the nut 26 and the check ring 284.

[0077] The end surface of the winding drum 21 is provided with a compression sleeve 29 connected with the winding drum 21; the compression sleeve 29 is internally provided with an elastic element 291 and a small ball 292, one end of the elastic element 291 is connected with the small ball 292, and the other end is connected with the compression sleeve 29; the buffer assembly 28 is provided with a stop groove 285, and when the winding drum 21 moves to the horizontal limit position in emergency, the small ball 292 falls into the stop groove 285. When the winding drum 21 moves to the limit position in emergency, the small ball 292 cooperates with the stop groove 285 to cause a certain resistance to the winding drum 21, avoiding the damage of the winding drum 21 caused by the sharp rebound of the buffer assembly 28 pushing the winding drum 21.

[0078] As shown in Figure 6 , the driving mechanism further comprises a compression roller assembly 3 located above the side of the winding drum 21, and the compression roller assembly 3 comprises a compression roller 31 in contact with the traction rope 8. The compression roller 31 contacts the traction rope 8 and presses the traction rope 8 on the winding drum 21, avoiding the winding and accumulation of the traction rope 8.

[0079] The number of compression rollers 31 is two, and the two compression rollers 31 are parallel to the ball screw 25 and are respectively pressed on the two sides of the winding drum 21. The two parallel compression rollers 31 ensure that the traction rope 8 always contacts the winding drum 21 when the winding drum 21 moves, and at the same time ensure that the traction rope 8 will not come out of the positioning groove 211.

[0080] As shown in Figure 7As shown, the drive mechanism also includes a guide assembly 4, located between the drum 21 and the control rod 9, through which the traction rope 8 passes. The guide assembly 4 includes a first guide wheel 41, a second guide wheel 42, and a limiting post 43. The first guide wheel 41 is installed higher than the second guide wheel 42. Guide grooves 44 are formed on the first guide wheel 41 and the second guide wheel 42, and the traction rope 8 moves within the guide grooves 44. The limiting post 43 is located above the second guide wheel 42 and contacts the traction rope 8 to prevent the traction rope 8 from coming out of the guide grooves 44. The traction rope 8 passes through the guide assembly 4, ensuring that the traction rope 8 remains vertically taut between the drum 21 and the control rod 9, preventing deviation in the movement of the traction rope 8.

[0081] like Figure 8 As shown, the drive mechanism also includes a rod position measuring component 5, which is connected to the drum assembly 2. The rod position measuring component 5 includes a phase angle measuring device 51, which is fixed on the support 52 and rotates together with the drum 21. By setting the transmission ratio, the rotation angle of the drum 21 can be calculated based on the rotation angle of the phase angle measuring device 51 as it rotates with the drum 21. The motion status of the drum 21 can be measured by outputting the measured phase angle change.

[0082] The drive mechanism also includes a support cylinder 6, which is located below the drum 21. The support cylinder 6 is hollow, and the traction rope 8 extends vertically into the support cylinder 6 and moves up and down within it, driving the control rod 9 to move up and down inside the support cylinder 6. The support cylinder 6 restricts the direction of movement of the traction rope 8 and the control rod 9, allowing them to move up and down only in a vertical direction.

[0083] A buffer 61 is installed inside the support cylinder 6 and is fixed to the bottom of the support cylinder 6. When the control rod 9 drops in an emergency, it comes into contact with the buffer 61, thereby buffering the impact of the emergency drop.

[0084] The drive mechanism also includes a one-way flywheel assembly 7, which is connected to the drum 21 and rotates with the drum 21. Most of the kinetic energy of the drum 21 during emergency drop is transferred to the one-way flywheel assembly 7, while when the drum 21 returns to its original position, the kinetic energy transferred to the one-way flywheel assembly 7 is consumed, greatly reducing the kinetic energy obtained by the drum 21 and preventing the control rod 9 from rising sharply.

[0085] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A reactor control rod drive mechanism characterized by, The drive mechanism comprises: a winding drum assembly, a traction rope being wound on the winding drum assembly, the traction rope being connected with a control rod; the winding drum assembly is provided with a winding drum; a drive module, the drive module being connected with the winding drum assembly and driving the winding drum to rotate; a ball screw, the ball screw being horizontally penetrated through the winding drum, the winding drum rotating around the ball screw; the ball screw is provided with a nut, the nut being fixed on the winding drum; the nut rotates with the winding drum, the nut and the ball screw being connected through thread cooperation; a positioning shaft, the positioning shaft being connected with the ball screw and coaxial with the ball screw; the winding drum is provided with a positioning groove, the positioning groove being spiral and surrounding the rotation axis of the winding drum, the traction rope being arranged in the positioning groove; the winding drum assembly further comprises a buffer assembly, the buffer assembly being arranged on the ball screw, the buffer assembly being located at the end of the ball screw pointed by the horizontal movement of the nut when the control rod is in emergency drop; the ball screw penetrates through the buffer assembly; the side of the buffer assembly facing the nut is provided with a contact surface, the nut being abutted with the contact surface when the control rod is in emergency drop; the ball screw is provided with a stepped surface, the diameter of the ball screw at the end of the stepped surface away from the buffer assembly being greater than the diameter of the ball screw at the end close to the buffer assembly; the buffer assembly is in contact with the stepped surface when the buffer assembly is not abutted with the nut, and the buffer assembly applies a force to the ball screw in the direction away from the buffer assembly.

2. The reactor control rod drive mechanism of Claim 1, wherein, the winding drum assembly further comprises a first rotating wheel, a second rotating wheel and a guide column; the drive module is connected with the first rotating wheel; one end of the guide column is connected with the first rotating wheel, and the other end of the guide column extends into the winding drum and is connected with the second rotating wheel; the first rotating wheel and the second rotating wheel are coaxial with the winding drum.

3. The reactor control rod drive mechanism of claim 2, wherein, the number of the guide columns is three, and the guide columns are uniformly distributed on the circumference of the winding drum.

4. The reactor control rod drive mechanism of Claim 2, wherein, the inside of the winding drum is provided with a bearing at the position where the guide column is connected.

5. The reactor control rod drive mechanism of any one of claims 1 to 4, wherein the drive module comprises a transmission assembly and a power assembly; the transmission assembly is coaxial with and connected with the winding drum; the power assembly is connected with the transmission assembly.

6. The reactor control rod drive mechanism of claim 5, wherein, the transmission assembly is an electromagnetic clutch, the electromagnetic clutch comprising a stator and a left rotor and a right rotor, the left rotor being connected with the power assembly, and the right rotor being connected with the winding drum assembly; when the electromagnetic clutch is powered, the left rotor is connected with the right rotor; when the electromagnetic clutch is powered off, the left rotor is disconnected with the right rotor.

7. The reactor control rod drive mechanism of Claim 1 wherein, the inside of the buffer assembly is sequentially provided with an end cover, a spring, a thrust bearing and a retainer in the horizontal direction; one end of the spring is abutted on the end cover, and the other end of the spring is abutted on the thrust bearing; the thrust bearing is located between the retainer and the spring, and the lower ring of the thrust bearing is installed in the inner hole of the retainer; the retainer is located at the end of the buffer assembly close to the nut and extends out of the buffer assembly.

8. The reactor control rod drive mechanism of Claim 1 wherein, The end surface of the winding drum is provided with a pressing sleeve connected with the winding drum; the pressing sleeve is internally provided with an elastic element and a ball, one end of the elastic element is connected with the ball, and the other end is connected with the pressing sleeve; a stop groove is formed in the buffer assembly, and when the winding drum moves to the horizontal limit position in the emergency rod dropping, the ball falls into the stop groove.

9. The reactor control rod drive mechanism of Claim 1 wherein, The driving mechanism further comprises a pressing roller assembly located above the side of the winding drum, and the pressing roller assembly comprises a pressing roller in contact with the traction rope.

10. The reactor control rod drive mechanism of Claim 9, wherein, The number of the pressing rollers is two, and the two pressing rollers are parallel to the ball screw and are respectively pressed on the two sides of the winding drum.

11. The reactor control rod drive mechanism of Claim 1 wherein, The driving mechanism further comprises a guide assembly located between the winding drum and the control rod, and the traction rope passes through the guide assembly; the guide assembly comprises a first guide wheel, a second guide wheel and a limiting column; the installation position of the first guide wheel is higher than that of the second guide wheel; the first guide wheel and the second guide wheel are provided with guide grooves, and the traction rope moves in the guide grooves; the limiting column is located above the second guide wheel and in contact with the traction rope.

12. The reactor control rod drive mechanism of Claim 1 wherein, The driving mechanism further comprises a rod position measuring assembly connected with the winding drum assembly; the rod position measuring assembly comprises a phase angle measuring device fixed on a support and engaged with the winding drum assembly through a gear pair to rotate with the winding drum.

13. The reactor control rod drive mechanism of Claim 1 wherein, The driving mechanism further comprises a support cylinder located below the winding drum, and the support cylinder is hollow; the traction rope vertically extends into the support cylinder and moves up and down in the support cylinder to drive the control rod to rise and fall in the support cylinder.

14. The reactor control rod drive mechanism of claim 13, wherein, The support cylinder is internally provided with a buffer fixed on the bottom of the support cylinder.

15. The reactor control rod drive mechanism of Claim 1 wherein, The driving mechanism further comprises a one-way flywheel assembly connected with the winding drum and rotating with the winding drum.

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