CN219936685U

CN219936685U - Control rod driving device

Info

Publication number: CN219936685U
Application number: CN202320973124.2U
Authority: CN
Inventors: 崔军; 李爽; 易奎铭; 韩万富
Original assignee: China General Nuclear Power Corp; China Nuclear Power Technology Research Institute Co Ltd; CGN Power Co Ltd
Current assignee: China General Nuclear Power Corp; China Nuclear Power Technology Research Institute Co Ltd; CGN Power Co Ltd
Priority date: 2023-04-18
Filing date: 2023-04-18
Publication date: 2023-10-31
Anticipated expiration: 2033-04-18

Abstract

The utility model discloses a control rod driving device, which is used for driving a control rod to do lifting motion in a pressure vessel, and comprises: the driving assembly is fixedly connected above the top cover of the pressure container; the transmission assembly penetrates through the top cover and the supporting plate of the pressure container and comprises a first transmission piece, a second transmission piece and a third transmission piece which are sleeved in sequence from outside to inside; a first thread pair is arranged between the first transmission piece and the second transmission piece; a second thread pair is arranged between the second transmission piece and the third transmission piece; the tail end of the third transmission piece is fixedly connected with the control rod, the first transmission piece is connected with the driving assembly and is driven by the driving assembly to rotate, and the second transmission piece is driven by the first thread pair to do lifting motion; the second transmission piece drives the third transmission piece and the control rod to do lifting motion through the second thread pair. According to the utility model, through the combined design of the sleeve and the screw nut, the height of the control rod driving device is reduced, and the overall size of the reactor system is effectively reduced.

Description

Control rod driving device

Technical Field

The utility model relates to the technical field of nuclear power, in particular to a control rod driving device.

Background

With the great increase in the diversity of energy utilization, the reactor tends to be miniaturized more than a large commercial pressurized water reactor so as to cater for a wider application space, and therefore the height of the reactor must be reduced so as to meet the miniaturization requirement of the nuclear reactor. The reactor height is primarily determined by the control rod drive line height, which is typically about 4 times the core height on a core height basis (without regard to top shielding), whereas the control rod drive line includes control rod drive mechanisms and core control rods, wherein the control rod drive mechanisms are typically 2 times the core height. Therefore, the height dimension of the control rod driving mechanism is directly related to the height of the whole reactor, and the height dimension of the control rod driving mechanism becomes a key technology for restricting the miniaturization of the reactor.

The control rod driving mechanism is key equipment in the nuclear reactor, and can complete the functions of starting, power adjustment, power maintenance, normal reactor stopping and nuclear accident stopping of the reactor according to instructions of a reactor control and protection system. At present, control rod driving mechanisms are divided into a plurality of types such as a gear rack type, a screw nut type, a chain wheel and chain type, a magnetic lifting type, a hydraulic driving type and the like according to a power principle, and the control rod driving mechanisms widely applied to small-sized reactors internationally mainly comprise two types: gear rack type screw nut type screw driver. However, in both driving modes, the driving rod (screw rod/rack) is required to pass through the top cover of the reactor pressure vessel during lifting, and the passing-through height is generally 2 times of the height of the reactor core, so that the height of the control rod driving mechanism is relatively high, the stroke is relatively long, and a certain space is required above the top of the reactor to facilitate the insertion and the lifting of the control rod in the process of controlling the reactivity of the reactor, which is not beneficial to reducing the overall height of the reactor system.

Disclosure of Invention

The utility model aims to provide a control rod driving device.

The technical scheme adopted for solving the technical problems is as follows: constructing a control rod driving device for driving the control rod to do lifting motion in the pressure vessel; the pressure container comprises a container main body, a top cover arranged at the upper end of the container main body, a supporting plate arranged in the container main body and a guide cylinder for guiding the movement of the control rod; the control rod driving apparatus includes:

the driving assembly is fixedly connected above the top cover of the pressure container;

the transmission assembly is rotatably arranged on the top cover and the supporting plate of the pressure container in a penetrating manner and comprises a first transmission piece, a second transmission piece and a third transmission piece which are sleeved in sequence from outside to inside;

a first thread pair is arranged between the first transmission piece and the second transmission piece; a second thread pair is arranged between the second transmission piece and the third transmission piece;

the tail end of the third transmission piece is fixedly connected with the control rod; the first transmission piece is connected with the driving assembly and is driven by the driving assembly to rotate, and the first thread pair drives the second transmission piece to do lifting motion; and the second transmission piece drives the third transmission piece and the control rod to do lifting motion through the second thread pair.

Preferably, an elastic piece is arranged at one end of the first transmission piece, which is close to the driving assembly, and the elastic piece is connected with the second transmission piece;

the elastic member is compressed when the second transmission member is lifted, and the second transmission member is lifted to the highest point and can be kept relatively stationary with the first transmission member when the elastic member is compressed to the shortest.

Preferably, the second transmission member includes a first threaded section and a first light pipe section, the first threaded section is closer to the driving assembly than the first light pipe section, the first threaded pair includes a first internal thread and a first external thread which are meshed with each other, the first internal thread is disposed on the inner side of the first transmission member, the first external thread is disposed on the outer surface of the first threaded section, and the outer diameter of the first light pipe section is smaller than the outer diameter of the first threaded section;

the one end that first driving medium kept away from drive assembly is equipped with first screw thread limiter, first screw thread limiter is followed first driving medium with space between the second driving medium extends the second driving medium descends to on first screw thread section with first screw thread limiter and butt time, first screw thread limiter can restrict the second driving medium is to keeping away from drive assembly's direction removes.

Preferably, the third transmission member comprises a second threaded section and a second light pipe section, the second threaded section is closer to the driving assembly than the second light pipe section, the second threaded pair comprises a second internal thread and a second external thread which are meshed with each other, the second internal thread is arranged on the inner side of the second transmission member, the second external thread is arranged on the outer surface of the second threaded section, and the outer diameter of the second light pipe section is smaller than the outer diameter of the second threaded section;

the one end that the second driving medium kept away from drive assembly is equipped with the second screw thread limiter, the second screw thread limiter is followed the second driving medium with space between the third driving medium extends, when the third driving medium descends to it the second screw thread section with second screw thread limiter and butt on, the second screw thread limiter can restrict the third driving medium is to keeping away from drive assembly's direction removes.

Preferably, the driving assembly comprises a shielding motor and a coupler, the coupler can rotate under the driving of the shielding motor, and the first transmission piece is connected with the coupler through a key slot in a connecting mode.

Preferably, the coupling is a friction disc electromagnetic clutch, a dog electromagnetic clutch or a rigid coupling.

Preferably, a brake is arranged at the top of the shielding motor, the brake brakes the shielding motor when the shielding motor is electrified, and the brake stops braking the shielding motor when the shielding motor is powered off.

Preferably, a rotary encoder is provided on top of the brake, which rotary encoder can measure and adjust the rotational speed of the brake.

Preferably, the drive assembly further comprises a coupling housing, a first bearing housing, a top cover flange, and two first bearings; the top cover flange is arranged on the top cover of the pressure container; the first bearing seats are arranged above the top cover flange, and the two first bearings are fixed between the first bearing seats and the first transmission piece at intervals; the coupler is sleeved on the coupler shell and is fixed between the shielding motor and the first bearing seat.

Preferably, the control rod driving apparatus further includes a second bearing seat disposed on the support plate of the pressure vessel, and two second bearing seats spaced-apart between the second bearing seat and the first transmission member.

The implementation of the utility model has the following beneficial effects: through the combined design of the sleeve and the screw nut, the first transmission piece is sleeved with the second transmission piece and then sleeved with the third transmission piece, under the condition that the driving assembly drives the first transmission piece to rotate, the second transmission piece can be driven to do lifting motion through the first thread pair between the first transmission piece and the second transmission piece, and the third transmission piece and a control rod connected with the third transmission piece are driven to do lifting motion through the second thread pair between the second transmission piece and the third transmission piece, so that the height of a control rod driving wire is fundamentally reduced, the height of the control rod driving mechanism is reduced to 1/2 times of the height of a reactor core, the height of a control rod driving wire assembly is reduced to 2.5 times of the height of the reactor core from 4 times of the height of the reactor core, the height dimension of the control rod driving wire assembly is obviously reduced, and the original reactor height is reduced by about 37.5%, and the purposes of reducing the height of the reactor core and the size are achieved.

Drawings

In order to more clearly illustrate the technical solution of the present utility model, the following description will be given with reference to the accompanying drawings and examples, it being understood that the following drawings only illustrate some examples of the present utility model and should not be construed as limiting the scope, and that other related drawings can be obtained from these drawings by those skilled in the art without the inventive effort. In the accompanying drawings:

FIG. 1 is a schematic diagram of a control rod drive apparatus in accordance with some embodiments of the present utility model;

FIG. 2 is a schematic view of a partial enlarged structure at A in some embodiments of the utility model;

FIG. 3 is a schematic view of a partially enlarged structure at B in some embodiments of the utility model;

fig. 4 is a schematic view of the control rod 13 and the guide cylinder 23 in a section C-C according to some embodiments of the present utility model.

Detailed Description

For a clearer understanding of technical features, objects and effects of the present utility model, a detailed description of embodiments of the present utility model will be made with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "rear", "upper", "lower", "left", "right", "longitudinal", "transverse", "vertical", "horizontal", "top", "bottom", "inner", "outer", "head", "tail", etc. are configured and operated in specific directions based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present utility model, and do not indicate that the apparatus or element to be referred to must have specific directions, and thus should not be construed as limiting the present utility model.

It should also be noted that unless explicitly stated or limited otherwise, terms such as "mounted," "connected," "secured," "disposed," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. When an element is referred to as being "on" or "under" another element, it can be "directly" or "indirectly" on the other element or one or more intervening elements may also be present. The terms "first," "second," "third," and the like are used merely for convenience in describing the present utility model and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, whereby features defining "first," "second," "third," etc. may explicitly or implicitly include one or more such features. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present utility model. It will be apparent, however, to one skilled in the art that the present utility model may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present utility model with unnecessary detail.

Fig. 1 shows a control rod driving apparatus 1 according to some embodiments of the present utility model for driving a control rod 3 to move up and down in a pressure vessel 2, the pressure vessel 2 including a vessel body, a top cover 21 provided at an upper end of the vessel body, a support plate 22 provided in the vessel body, and a guide cylinder 23 for guiding movement of the control rod 3, the control rod driving apparatus 1 including a driving assembly 11 and a transmission assembly 12. The driving assembly 11 is fixedly connected above the top cover 21 of the pressure container 2 and is used for connecting and driving the transmission assembly 12 to rotate. The transmission assembly 12 is rotatably arranged through the top cover 21 and the supporting plate 22 of the pressure container 2 and is used for driving the control rod 3 to do lifting motion.

The transmission assembly 12 comprises a first transmission member 121, a second transmission member 122 and a third transmission member 123 which are sleeved in sequence from outside to inside. The first transmission member 121 has a hollow cylindrical structure, the second transmission member 122 has a hollow cylindrical structure, and the third transmission member 123 has a solid round bar structure. A first thread pair is arranged between the first transmission piece 121 and the second transmission piece 122; a second thread pair is arranged between the second transmission member 122 and the third transmission member 123; the tail end of the third transmission member 123 is fixedly connected with the control rod 3. The first transmission part 121 is connected with the driving assembly 11 and is driven by the driving assembly 11 to rotate, the second transmission part 122 is driven by the first screw pair to do lifting motion, and the second transmission part 122 drives the third transmission part 123 and the control rod 3 to do lifting motion through the second screw pair. Preferably, the end of the third transmission member 123 is fixedly connected to the control rod 3 by means of a screw. In some embodiments, the first and second transmission members 121 and 122 are sleeve screws and the third transmission member 123 is a screw.

As shown in fig. 2, in some embodiments, an elastic member 124 is disposed at an end of the first transmission member 121 near the driving assembly 11, where one end of the elastic member 124 is welded to the top end of the first transmission member 121, and the other end is connected to the second transmission member 122. The elastic member 124 is compressed when the second transmission member 122 is lifted, and the second transmission member 122 is lifted to the highest point and can be kept relatively stationary with the first transmission member 121 when the elastic member 124 is compressed to the shortest. Specifically, when the driving assembly 11 drives the first transmission member 121 to rotate in the first direction, the second transmission member 122 can be driven by the first screw pair to perform an ascending motion, that is, the second transmission member 122 moves in a direction approaching to the driving assembly 11, and the second transmission member 122 continuously compresses the elastic member 124 during the ascending process. When the elastic member 124 is compressed to the minimum, it means that the elastic member 124 cannot be compressed any more at this time, that is, it means that the second transmission member 122 cannot rise any more, that is, it means that the second transmission member 122 rises to the highest point at this time. After the second transmission member 122 rises to the highest point, when the driving assembly 11 continues to drive the first transmission member 121 to rotate in the first direction, the second transmission member 122 is still relative to the first transmission member 121 because the second transmission member 122 cannot rise relative to the first transmission member, i.e. the second transmission member 122 rotates synchronously along with the first transmission member 121, and then drives the third transmission member 123 to rise through the second screw pair.

In some embodiments, the second transmission member 122 includes a first threaded section and a first light pipe section, the first threaded section is closer to the driving assembly 11 than the first light pipe section, the first threaded pair includes a first internal thread and a first external thread meshed with each other, the first internal thread is disposed inside the first transmission member 121, the first external thread is disposed on an outer surface of the first threaded section, and an outer diameter of the first light pipe section is smaller than an outer diameter of the first threaded section. That is, only a portion of the outer surface of the second transmission member 122 is threaded, the outer surface of the second transmission member is threaded to form a first threaded section, and the outer surface of the second transmission member is not threaded to form a first light pipe section. As shown in fig. 3, an end of the first transmission member 121 remote from the driving assembly 11 is welded to the first thread limiter 125, and the first thread limiter 125 extends along a space between the first transmission member 121 and the second transmission member 122. When the first threaded section of the second transmission member 122 descends thereon and the first threaded limiter 125 are abutted, the first threaded limiter 125 can limit the second transmission member 122 to move away from the driving assembly 11. Specifically, during the descent of the second transmission member 122, the first light pipe segment can smoothly pass through the first thread limiter 125, and when the first thread segment on which the second transmission member 122 descends abuts against the top of the first thread limiter 125, the first thread limiter 125 can limit the second transmission member 122 to continue to descend, that is, indicate that the second transmission member 122 has descended to the lowest point in the first transmission member 121 at this time. Preferably, in some embodiments, the first threaded limiter 125 is annular, with sides through which the first light pipe section can pass, and a top for abutting the first threaded section.

In some embodiments, the third transmission member 123 includes a second threaded section and a second light pipe section, the second threaded section is closer to the driving assembly 11 than the second light pipe section, the second threaded pair includes a second internal thread and a second external thread that are engaged with each other, the second internal thread is disposed inside the second transmission member 123, the second external thread is disposed on an outer surface of the second threaded section, and an outer diameter of the second light pipe section is smaller than an outer diameter of the second threaded section. That is, only a portion of the outer surface of the second transmission member 122 is threaded, the outer surface of the second transmission member is threaded to form a second threaded section, and the outer surface of the second transmission member is not threaded to form a second light pipe section. As shown in fig. 3, an end of the second transmission member 122 remote from the driving assembly 11 is welded to a second thread limiter 126, and the second thread limiter 126 extends along a space between the second transmission member 122 and the third transmission member 123. When the second threaded section of the third transmission member 123 is lowered onto the second threaded section and the second threaded limiter 126 are abutted against each other, the second threaded limiter 126 can limit the movement of the third transmission member 123 in a direction away from the driving assembly 11. Specifically, during the descent of the third transmission member 123, the second light pipe segment can smoothly pass through the second thread limiter 126, and when the second thread segment on which the third transmission member 123 descends abuts against the top of the second thread limiter 126, the second thread limiter 126 can limit the third transmission member 123 to continue to descend, that is, indicate that the third transmission member 123 has descended to the lowest point in the second transmission member 122 at this time. Preferably, in some embodiments, the second threaded stop 126 is annular, with sides through which the second light pipe section can pass, and a top for abutting the second threaded section.

In some embodiments, the driving assembly 11 includes a shielding motor 113 and a coupling 114, the coupling 114 can be driven by the shielding motor 113 to rotate, and the first transmission member 121 is connected to the coupling 114 through a key slot. Preferably, the coupling 114 is a friction disk electromagnetic clutch, a dog electromagnetic clutch, or a rigid coupling.

In some embodiments, a brake 112 is provided on top of the shield motor 113, the brake 112 braking the shield motor 113 when energized, and the brake 112 stopping braking the shield motor 113 when de-energized. The top of the brake 112 is provided with a rotary encoder 111, and the rotary encoder 111 is in communication connection with the brake 112 and is used for measuring the rotating speed of the brake 112 and realizing quick speed regulation of the brake 112.

In some embodiments, the drive assembly 11 further includes a coupling housing 115, a first bearing mount 116, a top cover flange 117, and two first bearings 118. A top cover flange 117 is provided on the top cover 21 of the pressure vessel 2 for carrying the weight of the control rod drive lines and for positioning the control rod drive. The first bearing seat 116 is disposed above the top cover flange 117, and two first bearings 118 are fixed between the first bearing seat 116 and the first transmission member 121 at intervals, for fixing the first transmission member 121 and axially positioning and radially positioning the first transmission member 121. The coupling housing 115 is used to fit the coupling 114 and is fixed between the canned motor 113 and the first bearing housing 116.

As shown in fig. 3, in some embodiments, the control rod driving apparatus 1 further includes a second bearing 13 and two second bearings 131, where the second bearing 13 is disposed on the support plate 22 of the pressure vessel 2, and the two second bearings 131 are fixed between the second bearing 13 and the second transmission member 122 at intervals, for fixing the first transmission member 121 and axially positioning and radially positioning the first transmission member 121.

As shown in fig. 4, the control rod 3 is provided with a recess 31, and the guide cylinder 23 is provided with a protrusion 231 fitted to the recess 31, so that the guide cylinder 23 restricts the rotational movement of the control rod 3 and can only be lifted and lowered in the height direction of the guide cylinder 23 when the control rod 3 is in the guide cylinder 23. It will be appreciated that the guide cylinder 23 may also be provided with a recess, and the control rod 3 may be provided with a protrusion that fits into the recess.

The working principle of the utility model is as follows:

when the control rod driving apparatus 1 makes a descending motion, a total of 3 stages are experienced, as follows:

(1) the shielding motor 113 drives the first transmission member 121 to perform synchronous rotation motion in the second direction, and at this time, the second transmission member 122 is connected with the first transmission member 121 through the first thread pair and is not stressed, so that the second transmission member 122 also follows the first transmission member 121 to perform synchronous rotation motion in the second direction; the third transmission member 123 is fixedly connected with the control rod 3 through a screw, and the control rod 3 cannot rotate under the limitation of the control rod guide cylinder 23, so that the third transmission member 123 cannot synchronously rotate together, and the third transmission member 123 is connected with the second transmission member 122 through a second screw pair, and at this time, the third transmission member 123 can vertically descend during the rotation of the shielding motor 113.

(2) When the third transmission member 123 descends to the second threaded section on the third transmission member 123 and the second threaded limiter 126 welded at the lower end of the second transmission member 122 are in contact with each other, the second threaded limiter 126 forces the third transmission member 123 to stop descending, at this time, the third transmission member 123 descends to the lowest point, and the second transmission member 122 and the third transmission member 123 become in relative fixed connection with friction resistance.

(3) When the second transmission member 122 and the third transmission member 123 are in a relatively fixed connection with frictional resistance, the second transmission member 122 cannot perform synchronous rotational movement along with the first transmission member 121 as with the third transmission member 123. The second transmission member 122 is connected to the first transmission member 121 through the first screw pair, and at this time, the second transmission member 122 will vertically descend immediately during the rotation of the shielding motor 113 until the first screw section on the second transmission member abuts against the top of the first screw limiter 125 welded to the lower end of the first transmission member 121, and the first screw limiter 125 forces the second transmission member 122 to stop descending.

When the control rod driving apparatus 1 makes a rising motion, a total of 3 stages are experienced, as follows:

(1) at this point the control rod 3 is at its lowest point. When the shielding motor 113 drives the first transmission member 121 to perform synchronous rotation motion in the first direction, the second transmission member 122 and the third transmission member 123 are still in relatively fixed connection with friction resistance, the second transmission member 122 cannot follow the first transmission member 121 to perform synchronous rotation motion like the control rod 3, and the second transmission member 122 is connected with the first transmission member 121 through the first screw pair, so that the second transmission member 122 performs vertical lifting motion during rotation motion of the shielding motor 113.

(2) During the second transmission member 122 is lifted, the second transmission member 122 continuously compresses the elastic member 124, and when the elastic member 124 is compressed to the limit, the second transmission member 122 is limited to be lifted continuously, and the second transmission member 122 is lifted to the highest point.

(3) After the second transmission member 122 rises to the highest point, the shielding motor 113 continues to drive the first transmission member 121 to perform synchronous rotation in the first direction, and at this time, the second transmission member 122 cannot continue to perform the rising motion, and will follow the first transmission member 121 to perform synchronous rotation in the first direction under the connection of the first screw pair. The third transmission member 123 is connected to the second transmission member 122 through the second screw pair, and at this time, the third transmission member 122 will vertically move up to the highest point during the rotation of the shielding motor 113.

The second direction is opposite to the first direction, for example, the first direction is clockwise, and the second direction is counterclockwise; alternatively, the first direction may be counterclockwise and the second direction may be clockwise, without limitation.

The utility model adopts a sleeve type screw nut type structure to divide the driving rod of the control rod driving mechanism into three parts, the first driving part is sleeved with the second driving part and then sleeved with the third driving part, under the condition that the driving assembly drives the first driving part to rotate, the first screw thread pair between the first driving part and the second driving part can drive the second driving part to do lifting motion, and the second screw thread pair between the second driving part and the third driving part can drive the third driving part and the control rod connected with the third driving part to do lifting motion, thereby fundamentally reducing the height of the control rod driving line, reducing the height of the control rod driving mechanism to 1/2 times of the height of the reactor core, obviously reducing the height dimension of the control rod driving line assembly from 4 times of the height of the reactor core to 2.5 times of the height of the reactor core, reducing the height of the original reactor by about 37.5 percent, enabling the arrangement of the reactor core to be more beneficial to the miniaturization development, and realizing the purposes of reducing the height of the nuclear reactor and reducing the volume.

It is to be understood that the above examples only represent preferred embodiments of the present utility model, which are described in more detail and are not to be construed as limiting the scope of the utility model; it should be noted that, for a person skilled in the art, the above technical features can be freely combined, and several variations and modifications can be made without departing from the scope of the utility model; therefore, all changes and modifications that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A control rod driving device for driving a control rod (3) to do lifting movement in a pressure vessel (2); the pressure container (2) comprises a container main body, a top cover (21) arranged at the upper end of the container main body, a supporting plate (22) arranged in the container main body, and a guide cylinder (23) for guiding the movement of the control rod (3); the control rod driving device is characterized by comprising:

the driving assembly (11) is fixedly connected above the top cover (21) of the pressure container (2);

the transmission assembly (12) is rotatably arranged on the top cover (21) and the supporting plate (22) of the pressure container (2) in a penetrating manner, and the transmission assembly (12) comprises a first transmission member (121), a second transmission member (122) and a third transmission member (123) which are sleeved in sequence from outside to inside;

a first thread pair is arranged between the first transmission piece (121) and the second transmission piece (122); a second thread pair is arranged between the second transmission piece (122) and the third transmission piece (123);

the tail end of the third transmission piece (123) is fixedly connected with the control rod (3); the first transmission piece (121) is connected with the driving assembly (11) and is driven by the driving assembly (11) to rotate, and the first thread pair drives the second transmission piece (122) to do lifting motion; and the second transmission piece (122) drives the third transmission piece (123) and the control rod (3) to do lifting movement through the second thread pair.

2. The control rod driving apparatus according to claim 1, wherein an elastic member (124) is provided at an end of the first transmission member (121) adjacent to the driving assembly (11), and the elastic member (124) is connected to the second transmission member (122);

the elastic member (124) is compressed when the second transmission member (122) is lifted, and the second transmission member (122) is lifted to the highest point and can be kept relatively stationary with the first transmission member (121) when the elastic member (124) is compressed to the shortest.

3. The control rod driving apparatus as defined in claim 1, wherein said second transmission member (122) comprises a first threaded section and a first light pipe section, said first threaded section being closer to said driving assembly (11) than said first light pipe section, said first threaded pair comprising a first internal thread and a first external thread that are intermeshed, said first internal thread being disposed inside said first transmission member, said first external thread being disposed on an outer surface of said first threaded section, said first light pipe section having an outer diameter that is smaller than said first threaded section outer diameter;

one end that drive assembly (11) was kept away from to first driving medium (121) is equipped with first screw thread limiter (125), first screw thread limiter (125) are followed first driving medium (121) with space between second driving medium (122) extends second driving medium (122) descend to on first screw thread section with first screw thread limiter (125) and butt time, first screw thread limiter (125) can restrict second driving medium (122) are kept away from the direction removal of drive assembly (11).

4. The control rod driving apparatus as defined in claim 1, wherein a third transmission member (123) includes a second threaded section and a second light pipe section, the second threaded section being closer to the driving assembly (11) than the second light pipe section, the second threaded pair including a second internal thread and a second external thread that are engaged with each other, the second internal thread being provided inside the second transmission member, the second external thread being provided on an outer surface of the second threaded section, the second light pipe section having an outer diameter smaller than the second threaded section;

one end that second driving medium (122) kept away from drive assembly (11) is equipped with second screw thread limiter (126), second screw thread limiter (126) are followed second driving medium (122) with space between third driving medium (123) extends third driving medium (123) descend to on second screw thread section with second screw thread limiter (126) and butt time, second screw thread limiter (126) can restrict third driving medium (123) are kept away from drive assembly (11) direction removal.

5. Control rod driving device according to claim 1, characterized in that the driving assembly (11) comprises a shielding motor (113) and a coupling (114), the coupling (114) can rotate under the drive of the shielding motor (113), and the first transmission piece (121) is connected with the coupling (114) through a key slot connection mode.

6. Control rod driving arrangement according to claim 5, characterized in that the coupling (114) is a friction disc electromagnetic clutch, a dog electromagnetic clutch or a rigid coupling.

7. The control rod driving apparatus according to claim 5, wherein a brake (112) is provided on top of the shield motor (113), the brake (112) braking the shield motor (113) when energized, the brake (112) stopping braking the shield motor (113) when de-energized.

8. Control rod driving apparatus according to claim 7, characterized in that the brake (112) is provided with a rotary encoder (111) on top, which rotary encoder (111) can measure and adjust the rotational speed of the brake (112).

9. The control rod drive of claim 5, wherein the drive assembly (11) further comprises a coupling housing (115), a first bearing seat (116), a top cover flange (117) and two first bearings (118); the top cover flange (117) is arranged on a top cover (21) of the pressure container (2); the first bearing seat (116) is arranged above the top cover flange (117), and two first bearings (118) are fixed between the first bearing seat (116) and the first transmission piece (121) at intervals; the coupler housing (115) is sleeved with the coupler (114) and is fixed between the shielding motor (113) and the first bearing seat (116).

10. Control rod driving apparatus according to claim 1, characterized in that the control rod driving apparatus further comprises a second bearing housing (13) and two second bearings (131), the second bearing housing (13) being arranged on a support plate (22) of the pressure vessel (2), the two second bearings (131) being fixed at a distance between the second bearing housing (13) and the first transmission member (121).