Nuclear reactor reactivity control cylinder and control method

Abstract

The present invention discloses a reactivity control cylinder and a control method for a nuclear reactor, belonging to the technical field of nuclear reactor reactivity control. The reactivity control cylinder for the nuclear reactor includes a first fixed reflector disposed around the core and a plurality of cylinders. The core has a longitudinal central axis. The plurality of cylinders are coaxially sleeved between the core and the first fixed reflector in sequence from inside to outside with the longitudinal central axis as the center. A rotary driver is connected to each cylinder, and the same number of absorber layers are uniformly spaced along the circumference of each cylinder. The reactivity control cylinder and the control method of the present invention can ensure that the absorption / reflection effect is uniform for the fuel consumption in all radial directions in the reactor core during long-term operation. At the same time, without increasing the total mass and volume of the absorber layer, and on the premise of maintaining neutron economy or utilization rate, the purpose of increasing the controllable reactivity range of the cylinder is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear reactor reactivity control, and particularly relates to a nuclear reactor reactivity control cylinder and a control method. Background Art

[0002] For a compact small ground nuclear reactor, some existing control technologies can adjust the neutron absorption rate and reflectivity by changing the relative position of the absorber and the reflector, and then regulate the reactivity. For example, in a control drum, crescent-shaped or arc-shaped neutron absorption materials are arranged on the side of the circular control drum, and the control drum is arranged in the reflector layer outside the reactor core. When the neutron absorption material in the control drum is rotated away from the reactor core, the absorption efficiency is reduced; when the control drum is rotated to make the neutron absorption material close to the reactor core, the absorption efficiency is improved. However, it cannot ensure that during the long-term operation of the nuclear reactor, the absorption / reflection effects related to control are uniform for the fuel consumption in all directions in the reactor core; at the same time, under the existing technology, it is difficult to expand the controllable reactivity range while keeping the total mass volume of the absorption material unchanged. Summary of the Invention

[0003] The purpose of the present invention is to overcome the problems in the prior art, and provide a nuclear reactor reactivity control cylinder and a control method that can ensure that the absorption / reflection effects are uniform for the fuel consumption in all radial directions in the reactor core during long-term operation. At the same time, the purpose of increasing the controllable reactivity range of the cylinder without increasing the total mass volume of the absorption layer and while maintaining the neutron economy or utilization rate is achieved.

[0004] The nuclear reactor reactivity control cylinder provided by the present invention includes a first fixed reflector arranged around the reactor core. The reactor core has a longitudinal central axis, and further includes:

[0005] A plurality of cylinders are coaxially sleeved between the reactor core and the first fixed reflector in sequence from inside to outside with the longitudinal central axis as the center. Absorption layers are evenly spaced along the circumferences of the respective cylinders, and the number of absorption layers on each cylinder is the same. The absorption layers on different cylinders can overlap radially along the cylinders, and when the positions of all the absorption layers are misaligned, they can at least jointly occupy an angular range of 360° with the longitudinal central axis as the center;

[0006] A rotary drive is connected to each of the cylinders to drive each cylinder to rotate around the longitudinal central axis through the rotary drive.

[0007] Preferably, the sum of the angular ranges occupied by the absorption layers on any one cylinder with the longitudinal central axis as the center is 360° / N, and the number of the cylinders is greater than N.

[0008] Preferably, the innermost cylinder is in close contact with the reactor core, and adjacent cylinders are in close contact with each other.

[0009] Preferably, an annular groove is provided on the inner wall of the cylinder body. The annular groove is arranged centered on the longitudinal central axis. Ball bearings are annularly and arrayedly provided on the outer wall of the cylinder body. The positions of the ball bearings on the inner cylinder body correspond to the positions of the annular grooves on the adjacent outer cylinder body, so that the ball bearings roll in the corresponding annular grooves.

[0010] Preferably, the core is sequentially divided into multiple sections along the longitudinal central axis. Multiple cylinder bodies are coaxially sleeved between each section of the core and the first fixed reflector layer from inside to outside in sequence. Each cylinder body is respectively connected to a rotation drive.

[0011] Preferably, the rotation drives correspond to the cylinder bodies one by one. Each rotation drive includes:

[0012] A fixed gear coaxially and fixedly connected to one end of the corresponding cylinder body;

[0013] A transmission gear meshing with the fixed gear;

[0014] A drive part connected to the transmission gear through a clutch device. The clutch device is used to connect or disconnect the drive part from the transmission gear. When the drive part is connected to the transmission gear, the drive part is used to drive the transmission gear to rotate;

[0015] An elastic resetting part connected to the transmission gear to prevent the transmission gear from leaving the initial position.

[0016] Preferably, the rotation drives correspond to the cylinder bodies one by one. Each rotation drive includes:

[0017] A fixed gear coaxially and fixedly connected to one end of the corresponding cylinder body;

[0018] A transmission rack meshing with the fixed gear;

[0019] A drive part connected to the transmission rack through a clutch device. The clutch device is used to connect or disconnect the drive part from the transmission rack. When the drive part is connected to the transmission rack, the drive part is used to drive the transmission rack to translate;

[0020] An elastic resetting part connected to the transmission rack to prevent the transmission rack from leaving the initial position.

[0021] Preferably, the fixed gears are all sector gears, and the sector gears on each cylinder body are arranged circumferentially in a staggered manner.

[0022] The control method of any one of the above nuclear reactor reactivity control cylinders includes driving each cylinder body to rotate synchronously and in the same direction through a rotation drive when the angular range jointly occupied by the positions of each absorption layer is less than 360°.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The novel cylinder disclosed herein can ensure uniform fuel consumption in all radial directions in the reactor core due to absorption / reflection effects during long-term operation by rotating all cylinders. By ensuring that the inner absorption layer and the outer absorption layer completely overlap in the radial direction, the cylinder's neutron absorption effect can be minimized and its neutron reflection effect can be maximized, at which point the core reactivity is maximized. To achieve uniform absorption at this point, all cylinders can be synchronously rotated by an angle at regular time intervals to achieve uniform radial neutron absorption on a time-averaged basis. By allowing each absorption layer to alternately occupy an angle range of 0° to 360°, i.e., by fully expanding the absorption layer to cover the core, the core's neutron absorption effect can be maximized, its neutron reflection effect can be minimized, and its core reactivity can be minimized, thereby achieving uniform absorption of core neutrons.

[0025] The difference in core reactivity when the cylinders are fully overlapped and fully deployed is the range of the controllable reactivity of the cylinders. In actual use, the cylinders can be deployed to a range between fully overlapped and fully deployed, that is, the reactivity they control is between the maximum and minimum values. Specifically, the total amount of absorption layers in each cylinder remains unchanged. By increasing the number of cylinder layers, the absorption layers are subdivided into more parts, such as from Figures 1 to 2 The third level is upgraded to Figures 3 to 4 The six layers can compress the area facing the core to a smaller size when the absorption layers in each cylinder are fully overlapped, thereby further reducing the neutron absorption amount and increasing the difference in the amount of neutrons absorbed from full expansion to full overlap, thereby expanding the control range of reactivity, thereby achieving the purpose of improving the controllable reactivity range of the cylinder without increasing the total mass volume of the absorption layer and while maintaining neutron economy (utilization rate). BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the structure of the three-layer cylinder of the present invention in which the absorption layers are completely overlapped;

[0027] Figure 2 This is a schematic diagram of the structure of the three-layer cylinder of the present invention in which the absorption layers are completely staggered;

[0028] Figure 3 This is a schematic diagram of the structure of the six-layer cylinder of the present invention in which the absorption layers are completely overlapped;

[0029] Figure 4 This is a schematic diagram of the structure of the six-layer cylinder of the present invention in which the absorption layers are completely staggered;

[0030] Figure 5 Schematic diagram of the cross-sectional structure of the core of the present invention divided along the axial direction;

[0031] Figure 6Schematic diagram of the axial power distribution of the reactor of the present invention;

[0032] Figure 7 Schematic diagram for comparing the reactivity control ranges under the three-layer and six-layer cylinders of the present invention;

[0033] Figure 8 Axonometric structure diagram of the cylinder of the present invention;

[0034] Figure 9 Longitudinal sectional structure diagram of the cylinder of the present invention;

[0035] Figure 10 Top view structure diagram of the cylinder of the present invention;

[0036] Figure 11 Structure diagram of the connection between the cylinder and the transmission gear of the present invention;

[0037] Figure 12 Structure diagram of the spring winding device of the present invention;

[0038] Figure 13 Structure diagram of the connection between the three-layer cylinder and the transmission gear of the present invention;

[0039] Figure 14 Structure diagram of the connection between the cylinder and the fixed gear with missing teeth of the present invention;

[0040] Figure 15 Structure diagram of the connection between the transmission rack and the fixed gear with missing teeth of the present invention.

[0041] Explanation of reference numerals:

[0042] 1. Core, 2. First fixed reflector, 3. Cylinder, 31. Absorbing layer, 32. Annular groove, 33. Ball, 41. Fixed gear, 42. Transmission gear, 421. Rotating main shaft, 43. Transmission rack, 431. Slide bar, 432. Linear spring, 451. Spring winding box, 452. Inner shaft of spring winding box, 453. Spring winding, 46. Electric gripper, 47. Friction clutch mechanism, 5. Second fixed reflector, 6. Rotatable reflector. Detailed implementation manners

[0043] The following will describe in detail the specific implementation manners of the present invention in conjunction with the attached Figures 1 to 15 , but it should be understood that the protection scope of the present invention is not limited by the specific implementation manners. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0044] The nuclear reactor reactivity control tube and control method provided by the present invention include a first fixed reflective layer 2 and a plurality of cylinders 3 arranged on the periphery of the core 1. The core 1 has a longitudinal central axis. Each cylinder 3 is coaxially sleeved between the core 1 and the first fixed reflective layer 2 from the inside to the outside with the longitudinal central axis as the center, and the gap between the innermost cylinder 3 and the core 1 is filled by the second fixed reflective layer 5. The cylinders 3 are all connected to a rotary drive to drive each cylinder 3 to rotate around the longitudinal central axis through the rotary drive. Each cylinder 3 is evenly spaced along its own circumference and has the same number of The absorption layer 31, each absorption layer 31 on different cylinders 3 can overlap along the radial direction of the cylinder 3, and when the positions of each absorption layer 31 are staggered, they can at least jointly occupy an angle range of 360° centered on the longitudinal central axis. By adopting the above technical solution, each cylinder 3 can be rotated by a rotary driver so that each absorption layer 31 on each cylinder 3 overlaps or staggers along the radial direction of the cylinder 3, so as to change the angle range jointly occupied by each absorption layer 31 on each cylinder 3 centered on the longitudinal central axis, thereby changing the size of the exposed surface area of the core 1, thereby controlling the reactivity of the core 1.

[0045] Specifically, the number of cylinders 3 layers is selected based on the required reactivity adjustment range of the core 1 while maintaining the mass and volume of the absorption layer unchanged. Thus, the absorption layers 31 are evenly spaced on each layer of the cylinders 3, so that when fully deployed, they can completely cover the core at 360°. When completely overlapping along the radial direction of the cylinders 3, they can also cover the core at close to 0°. Compared with one layer blocking another, the present invention highlights the effect of extreme folding, that is, by overlapping more layers, the area of the absorption layer 31 facing the core 1 is continuously reduced, thereby reducing neutron absorption, thereby achieving the purpose of increasing the controllable reactivity range of the cylinder without increasing the total mass and volume of the absorption layer 31, while maintaining the economic utilization rate of neutrons.

[0046] More specifically, when the three layers of absorption layers 31 completely overlap in the radial direction, 2 / 3 of the surface area of the core 1 is exposed. If the number of layers of the cylinder 3 is increased, and the absorption layers 31 and the reflective material are evenly distributed in each layer to achieve the functions of complete overlap and complete coverage, more core 1 area can be exposed. For example, 6 layers can expose 5 / 6 of the core 1 area, and 8 layers can expose 7 / 8. In this way, the reactivity of the core can be adjusted within a wider range, because the exposed core 1 area in the present invention is larger and can be adjusted as needed, that is, by increasing or decreasing the number of layers, the range of reactivity can be increased or decreased. Under the same loading of the absorption layer 31 and the same thickness of the cylinder 3 and axial length, the range of controllable reactivity is greatly expanded, from the absorption layer being completely staggered and completely covering the core 1, to the absorption layer completely overlapping and only 1 / 3, 1 / 30, 1 / 60... of the area covering the core 1, which can ultimately effectively improve the economic efficiency of the reactor. Specifically, it can be compared Figure 4 Exposed 2 / 3 area andFigure 7 Expose an area of 5 / 6.

[0047] In one embodiment of the present invention, the sum of the angular ranges occupied by the absorption layers 31 on any cylinder 3 centered on the longitudinal central axis is 360° / N, and the number of cylinders 3 can be equal to N. As Figure 1 and Figure 2 shown, the object of the present invention can be achieved. However, after the number of layers of the cylinder 3 increases, the outermost layer is getting farther and farther away from the innermost layer, which will cause the absorption layers 31 of these two layers to be non-adjacent and generate an increasingly large gap, resulting in leakage. Therefore, more preferably, in order to effectively suppress the effect of gap leakage, the number of cylinders 3 is greater than N. As Figure 4 shown, outside the original last layer, add another layer. The absorption material in this layer is completely staggered and adjacent to the penultimate layer, but completely coincides with the innermost first layer. In this way, it can, but if the gap effect is greater, another layer can be added outside, continuing to be completely staggered and adjacent to the penultimate layer, but completely coinciding with the second innermost layer, in order to effectively suppress the gap effect, and so on, until the gap effect can be ignored. And for these additional layers that offset the gap effect, since their absorption layers 31 respectively correspond to the existing internal absorption layers 31, when rotating and contracting to complete coincidence, it will still contract to the effect when there are no additional layers, that is, the exposed area remains the same, thus ensuring the range of controlling reactivity.

[0048] As a preferred solution, the cylinder 3 located in the innermost layer is in close contact with the reactor core 1, and adjacent cylinders 3 are in close contact with each other, so that there is enough space outside the reactor core 1 to arrange more reflecting materials and shielding materials to prevent neutrons from leaking into the environment.

[0049] As a preferred solution, an annular groove 32 is coaxially provided on the inner wall of the cylinder 3, and balls 33 are annularly arrayed on the outer wall of the cylinder 3. The positions of the balls 33 on the inner cylinder 3 correspond to the positions of the annular grooves 32 on the adjacent outer cylinder 3, so that the balls 33 roll in the corresponding annular grooves 32. In this way, when the adjacent cylinders 3 rotate relative to each other, the resistance of the rotation of the cylinder 3 can be reduced.

[0050] Since the existing reactivity control means can only achieve uniform control of axial reactivity, such as a control drum, or one-way introduction of axial reactivity control ability, such as axially partially inserted control rods, and cannot achieve segmented and precise control of axial reactivity. Therefore, as a preferred solution, the reactor core 1 is sequentially divided into multiple segments along the longitudinal central axis. Between each segment of the reactor core 1 and the first fixed reflector layer 2, multiple cylinders 3 are coaxially sleeved from the inside to the outside in sequence, and each cylinder 3 is respectively connected to a rotation driver;

[0051] Specifically, the core 1 is divided into a first section, a second section, and a third section along the longitudinal center axis. A three-layer cylinder 3 and a three-layer rotatable reflective layer 6 are concentrically arranged from the inside to the outside between the first section and the first fixed reflective layer 2. Another three-layer cylinder 3 is concentrically arranged from the inside to the outside between the second section and the third section and the first fixed reflective layer 2. The three-layer cylinder 3 arranged outside the second section is fixedly connected to the three-layer rotatable reflective layer 6 arranged outside the first section in a one-to-one correspondence. The rotation drive includes a first rotation drive, a second rotation drive, and a third rotation drive. The first rotation drive is used to drive the three-layer cylinder 3 arranged outside the first section to rotate around the longitudinal center axis. The second rotation drive is used to drive the three-layer rotatable reflective layer 6 arranged outside the first section to rotate around the longitudinal center axis. The third rotation drive is used to drive the three-layer cylinder 3 arranged outside the third section to rotate.

[0052] Specifically, the core 1 can be divided into M sections, which are greater than three, such as four or five sections, along the longitudinal center axis, to achieve more precise axial layering control. A rotatable reflective layer 6 is provided in the first section or the Mth section, which is connected to each cylinder 3 located in the second section to the M-1th section in a one-to-one correspondence. In this way, the corresponding cylinders 3 in the second section to the M-1th section can be driven to rotate by rotating the rotatable reflective layer 6 in the first section or the Mth section.

[0053] like Figure 6 The different axial power distributions of the reactor reflect the different axial strength distributions of the fission reaction and the axial distribution of the neutron flux. Since the axial power peak / neutron flux distribution in some core 1 designs will move significantly during operation, the above-mentioned technical solution can be used to configure the cylinders 3 located in different sections to be expanded or overlapped according to the different axial neutron flux distributions through axial segmented control, thereby realizing segmented control of the reactor reactivity in the axial direction and providing different neutron absorption capabilities along the axial direction, thereby achieving precise reactivity control and improving neutron economy while ensuring the controllability of the reactor.

[0054] As a preferred embodiment, the rotary drivers correspond one-to-one with the cylinders 3. Each rotary driver includes a fixed gear 41, a transmission gear 42, a driving part, a clutch device and an elastic reset member. The driving part is a motor (not shown in the drawings). The fixed gear 41 is coaxially and fixedly connected to one end of the corresponding cylinder 3. When the reactor core 1 is sequentially segmented along the longitudinal central axis, the fixed gear 41 can be connected to one end of the corresponding rotatable reflector 6. The transmission gear 42 meshes with the fixed gear 41. The motor is electrically connected to a power source and is fixedly arranged on the main structure of the test bench (not shown in the drawings). The transmission gear 42 is coaxially and fixedly connected to a rotating main shaft 421. The clutch device is a friction clutch mechanism 47. The input end of the friction clutch mechanism 47 is connected to the output shaft of the motor, and the output end is connected to the top end of the rotating main shaft 421. The elastic reset member is a spring winding device. The bottom end of the rotating main shaft 421 is connected to a spring winding mechanism. The spring winding mechanism includes a spring winding box 451, a spring winding box inner shaft 452 and a spring 453. The spring winding box 451 is fixedly arranged on the main structure of the test bench. The spring winding box inner shaft 452 is rotatably connected to the center of the spring winding box 451. The spring winding box inner shaft 452 is also fixedly connected to the rotating main shaft 421 through a pin key. The spring 453 is sleeved outside the spring winding box inner shaft 452, and both ends are respectively connected to the spring winding box inner shaft 452 and the inner wall of the spring winding box 451 to prevent the transmission gear 42 or the transmission rack 43 from leaving the initial position. With the above technical solution, when the friction clutch mechanism 47 is energized and tightened, the power from its input end can be transmitted to the rotating main shaft 421 through the output end. Then, the motor drives the transmission gear 42, drives the fixed gear 41 and the corresponding cylinder 3 to rotate, and deforms the spring 453. When the friction clutch mechanism 47 is de-energized and released, the power at its input end can no longer be transmitted to the rotating main shaft 421, and the spring 453 can recover its deformation and drive the cylinder 3 to rotate in the reverse direction until it returns to the initial position. Specifically, the initial position is the state where all the cylinders 3 are sequentially unfolded and the absorber layers 31 do not overlap each other, that is, the fully unfolded state. At this time, the neutron absorption ability of the cylinder 3 is the strongest. Therefore, when power is cut off or there is an accidental power outage, in a passive manner, that is, when the rotary driver loses power (such as losing electricity), the present invention can rely on the inherent characteristics of the components (i.e., the elastic reset member) in the rotary driver to reset the cylinder 3 to the initial position (i.e., the fully unfolded state), realizing the maximum neutron absorption ability for the reactor core 1 to ensure the safety of the reactor core 1.

[0055] In another embodiment, the transmission gear 42 can be replaced by a transmission rack 43, which is meshed with the corresponding fixed gear 41. The transmission rack 43 is slidably connected to the main structure of the test bench. One end of the transmission rack 43 is fixedly connected to a slide bar 431 in the longitudinal direction. The elastic reset member is a linear spring 432, which is sleeved on the slide bar 431. The two ends of the linear spring 432 are respectively connected to the slide bar 431 and the main structure of the test bench. The driving part is also a motor (not shown in the drawings), and a screw slider mechanism (not shown in the drawings) is connected to the output shaft of the motor to drive the slider of the screw slider mechanism to move by the rotation of the motor output shaft. The guide rod of the structure is parallel to the sliding direction of the transmission rack 43 on the main structure of the test bench. The clutch device is an electric clamper 46. The fixed part of the electric clamper 46 is fixedly connected to the slider. The clamping part of the electric clamper 46 is clamped on the slide bar 431. When the electric clamper 46 is powered on, the clamping part of the electric clamper 46 is clamped on the slide bar 431. The movement of the slider can drive the slide bar 431 and the transmission rack 43 to translate, causing the linear spring 432 to deform and drive the fixed gear 41 to rotate. When the electric clamper 46 is powered off, the clamping part of the electric clamper 46 releases the slide bar 431, the linear spring 432 recovers its deformation, and drives the cylinder 3 to rotate in the opposite direction until it returns to its initial position.

[0056] Specifically, the position of the fixed gear 41 located relatively on the inner side is higher than that of the fixed gear 41 located on the outer side, so that the transmission gear 42 or the transmission rack 43 is meshed with the fixed gear 41 .

[0057] In order to achieve the engagement of each fixed gear 41 with the corresponding transmission rack 43 or transmission gear 42, if a complete gear is used, it is necessary to arrange each fixed gear 41 in a stepped manner, with the fixed gear 41 located in the inner layer being higher and the fixed gear 41 located in the outer layer being lower, but this will increase the axial length of the present invention. For this reason, as a preferred embodiment, the present invention arranges that the fixed gears 41 are all fan-shaped gears, and the fan-shaped gears on each cylinder 3 are staggered along the circumferential direction. In this way, the fixed gears 41 can be located at the same height, and the transmission gear 42 or transmission rack 43 can be engaged with the fixed gear 41, thereby reducing the axial length of the present invention.

[0058] Any of the above-mentioned control methods for a nuclear reactor reactivity control cylinder comprises: when the angle range jointly occupied by the positions of the absorption layers 31 on the cylinder 3 is less than 360°, driving the cylinders 3 to rotate synchronously in the same direction by a rotary driver;

[0059] With the above technical solution, by rotating the cylinder 3 simultaneously, it is possible to ensure that the fuel consumption in all radial directions in the reactor core 1 is uniform during long-term operation due to the absorption or reflection effect. By making the inner absorption layer 31 and the outer absorption layer 31 completely overlap radially, the neutron absorption effect of the cylinder 3 can be minimized and the neutron reflection effect can be maximized. At this time, the reactivity of the core 1 is the highest. If a uniform absorption effect is to be achieved at this time, all cylinders 3 can be rotated synchronously by an angle at a certain time interval to achieve a uniform radial neutron absorption effect in terms of time averaging.

[0060] In the description of the present invention, it should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variation thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the element.

[0061] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0062] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A reactivity control cylinder for a nuclear reactor, comprising a first fixed reflector (2) disposed around the core (1), the core (1) having a longitudinal central axis, characterized in that, Further included are: A plurality of cylinders (3), centered on the longitudinal central axis, are coaxially sleeved between the reactor core (1) and the first fixed reflector (2) in sequence from inside to outside. Absorbing layers (31) are uniformly spaced along the circumference of each cylinder (3), and the number of absorbing layers (31) on each cylinder (3) is the same. The absorbing layers (31) on different cylinders (3) can overlap along the radial direction of the cylinder (3), and when the positions of all the absorbing layers (31) are misaligned, they can at least jointly occupy an angular range of 360° centered on the longitudinal central axis; A rotary drive, connected to each of the cylinders (3), for driving each cylinder (3) to rotate around the longitudinal central axis through the rotary drive; The reactor core (1) is sequentially divided into multiple segments along the longitudinal central axis. Between each segment of the reactor core (1) and the first fixed reflector (2), a plurality of the cylinders (3) are coaxially sleeved in sequence from inside to outside, and each cylinder (3) is respectively connected to a rotary drive.

2. The reactivity control cylinder of the nuclear reactor according to claim 1, wherein The sum of the angular ranges occupied by the absorbing layers (31) on any one cylinder (3) centered on the longitudinal central axis is 360° / N, and the number of the cylinders (3) is greater than N.

3. The reactivity control cylinder of the nuclear reactor according to claim 1, characterized in that, The cylinder (3) located in the innermost layer is in close contact with the reactor core (1), and adjacent cylinders (3) are in close contact with each other.

4. The reactivity control cylinder of the nuclear reactor according to claim 1, characterized in that, An annular groove (32) is provided on the inner wall of the cylinder (3), and the annular groove (32) is centered on the longitudinal central axis. Ball bearings (33) are annularly arrayed on the outer wall of the cylinder (3). The positions of the ball bearings (33) on the inner cylinder (3) correspond to the positions of the annular grooves (32) on the adjacent outer cylinder (3), so that the ball bearings (33) roll in the corresponding annular grooves (32).

5. The reactivity control cylinder of the nuclear reactor according to claim 1, characterized in that The rotary drives correspond to the cylinders (3) one by one, and each rotary drive includes: A fixed gear (41), coaxially and fixedly connected to one end of the corresponding cylinder (3); A transmission gear (42), meshing with the fixed gear (41); A driving part, connected to the transmission gear (42) through a clutch device, and the clutch device is used to connect or disconnect the driving part from the transmission gear (42). When the driving part is connected to the transmission gear (42), the driving part is used to drive the transmission gear (42) to rotate; An elastic resetting member, connected to the transmission gear (42), to prevent the transmission gear (42) from leaving the initial position.

6. The reactivity control cylinder of a nuclear reactor according to claim 1, characterized in that, The rotary drives correspond to the cylinders (3) one by one, and each rotary drive includes: A fixed gear (41), coaxially and fixedly connected to one end of the corresponding cylinder (3); A transmission rack (43), meshing with the fixed gear (41); A driving part, connected to the transmission rack (43) through a clutch device, and the clutch device is used to connect or disconnect the driving part from the transmission rack (43). When the driving part is connected to the transmission rack (43), the driving part is used to drive the transmission rack (43) to translate; An elastic resetting member, connected to the transmission rack (43), to prevent the transmission rack (43) from leaving the initial position.

7. The reactivity control cylinder of the nuclear reactor according to claim 5 or 6, characterized in that, The fixed gears (41) are all sector gears, and the sector gears on each cylinder (3) are circumferentially misaligned.

8. The control method of the reactivity control cylinder of the nuclear reactor according to any one of claims 1 to 7, characterized in that, When the angular range commonly occupied by the positions of the absorption layers (31) on the cylinder body (3) is less than 360°, the cylinder bodies (3) are driven to rotate synchronously and in the same direction by a rotation driver.

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