JP2868833B2 - Control rod drive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control rod driving device for a nuclear reactor.

[Conventional technology]

Conventional control rod drive for fast breeder reactor
1 As described in No. 46, 1983, 6, p. 63-71, a stroke motor, a ball screw as a mechanism for converting rotational movement into vertical movement, a control rod latch, a drive shaft latch mechanism, and a cut off during scram. A magnet link mechanism for rapid insertion of control rods, and a drive shaft lock mechanism for pulling out and preventing the drive shaft from dropping when refueling or the like are arranged in series. It was a long object with a drive unit located at about 5m in length.
In addition, since it is a long object, the structure has a seismic support in the vicinity of the center of the drive unit in order to increase the seismic strength from the surface on the seismic resistance.

FIG. 2 is an example of a known example of a control rod driving device. FIG. 2 (2) is a diagram leading to FIG. 1 (1). The control rod driving device of this known example includes a stroke motor 4 disposed on an upper portion of a driving unit housing 17 containing a control rod driving device and the like.
The control rod 22 is moved up and down by the ball screw 23 and the ball screw nut 24. Scrum demagnetizes the hold magnet 25, releases the magnet ring mechanism 26,
The control rod 22 and the drive shaft 19 are integrally formed by gas acceleration and gravity drop.

The main functions of this known control rod driving device will be described below.

First, the vertical drive as a normal drive is performed by converting the rotation of the stroke motor 4 into a linear motion by a ball screw 23 and a ball screw nut 24, and transmitting the linear motion to the hold magnet 25 via the load cell 15. The armature 27 attracted to the hold magnet 25 is connected to a magnet link mechanism 26, a control rod drive shaft 19, and a latch shaft 20.
It moves up and down as one. Holding at the fixed position and stopping at the time of power failure are performed by the stroke electromagnetic brake 28.

Second, the scrum demagnetizes the hold magnet 25, disconnects the armature 27, releases the connecting magnet link mechanism 25, and accelerates the control rod 22 and the control rod drive shaft 19 integrally by gas pressure and gravity. Performed by

Third, at the time of refueling, the control rod is separated from the control rod drive device by the following operation. When the control rod 22 is in the full insertion position, the latch motor 9 is operated, and the latch shaft 20 is inserted from the normal position to the control rod separation position.
21 is delatched. In this state, the stroke motor 4 is operated to pull out the control rod drive shaft 19 from the lower limit position to the fuel exchange lower limit position. Next, the latch motor 9 is operated from the control rod separating position to the drive shaft lock position, and the control rod drive shaft 19 is mechanically locked by the drive shaft lock mechanism 12. The control rod is held in the latched and delatched states by an electromagnetic brake directly connected to the latch motor.

Fourth, an operation of separating the drive unit housing 17 containing the control rod drive device and the like from the upper guide tube 18 is also performed. This operation consists of a mechanism housing 17 and an upper guide tube 18 for maintenance of the drive mechanism.
Operate only when it is necessary to disconnect the Upper guide tube 18
Is separated by overrunning the stroke motor 4 at the lower limit of the stroke, and releasing the ball latch between the upper guide tube 18 and the drive shaft 19 and the latch shaft 20 in the guide tube 18 by the movement of the spring.

Fifth, it has a sealing function. Welding bellows 29 are used for the stroke part and the latch shaft drive part, and shut off the atmosphere in the furnace and outside air while absorbing the relative movement between the drive shaft 19 and the upper guide tube 18 and the latch shaft 20 and the drive shaft 19, respectively. I do.

[Problems to be solved by the invention]

As described above, according to the conventional example, since the stroke motor, the mechanism for converting rotational movement into vertical movement, the control rod latch, the drive shaft latch mechanism, and the like are arranged in series, the drive unit length becomes about 5 m. However, the need for seismic support and the accompanying need for a large space above the reactor have left factors for cost increase.

An object of the present invention is to satisfy all of the functions of the above-described conventional control rod drive device, to shorten and simplify the structure thereof, and to further improve the reliability of the control rod drive device itself. An object of the present invention is to reduce the length of the reactor, eliminate the need for seismic support parts in the upper part of the reactor core, streamline the upper structure of the reactor, and reduce the cost of the plant as a whole.

[Means for solving the problem]

In order to achieve the above object, a control rod driving device according to the present invention has a configuration described in each claim.

[Action]

A stroke motor and a mechanism for converting the rotation of the stroke motor, which includes a ball screw with a spline for a stroke, a spline nut for a stroke, and a ball screw nut for a stroke, into a vertical movement of a ball screw with a spline for a stroke are arranged in parallel. In addition to the above, the rotation of the latch motor, which includes a latch motor, a latch spline ball screw, a latch spline nut, and a latch ball screw nut, is performed by a latch spline ball screw (an upper portion of the latch shaft). ) And a mechanism that converts the movement into vertical movement are arranged in parallel,
The overall height of the control rod drive is shortened, so that seismic support is not required.

Further, the space above the reactor core can be made smaller than before, which can contribute to the downsizing of the entire reactor structure. Furthermore,
With the above, it is possible to contribute to cost reduction of the entire reactor structure.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to FIG.

In this embodiment, a stroke operation mechanism 30 including a stroke motor 4 having a hollow rotor is installed below a drive unit housing 17 disposed on the upper surface of a rotary plug in a nuclear reactor.
The stroke ball screw nut 2 integral with the hollow rotor is rotated by the stroke motor 4, and the ball screw 1 with the spline for stroke, which is screwed with this, is driven up and down.

The ball screw 1 with a stroke acting spline is tubular and penetrates through the motor 4 and engages with a spline nut for stroke disposed inside the motor 4 for stroke to prevent rotation thereof. It is supported in the state where it was done. At the upper end of the ball screw 1 with a spline for stroke which is driven up and down without rotating, a scram mechanism 11 for performing a scram operation for holding the control rod drive shaft 19 releasably and a drive shaft lock mechanism 12 are provided.
Is provided.

The scrum mechanism 11 has the same structure as that of the above-described conventional example in that the armature 27 is attracted to the hold magnet 25 so that the control rod drive shaft 19 is always held through the magnet link mechanism 26. The control rod drive shaft 19 extends through the inside of the ball screw 1 with the spline for stroke to the lower drive shaft separating mechanism 13.

Further, the latch operation mechanism 16 includes a latch motor 9 mounted and installed on the upper part of the scrum mechanism 11 and generating a stroke necessary for disconnecting the control rod, disconnecting the drive shaft, and locking the drive shaft. That is, the latch motor 9
Is mounted on the scrum mechanism 11 via a support with a load cell 15. The ball screw 6 with a spline for latch penetrating through the inside of the latch motor 9 is connected to a latch shaft 20 extending into the control rod drive shaft 19.

The mechanism for generating the vertical movement of the latch shaft 20 with respect to the control rod drive shaft 19 is the same as that for the stroke described above. This is made possible by moving up and down without rotating. In order to prevent the rotation of the ball screw 6 with the latch spline, the latch spline nut 8 is arranged in the same arrangement as that for the stroke described above, and the latch motor 9 is rotated.
It is installed in.

The vertical movement of the ball screw 1 with a spline for stroke caused by the rotation of the hollow rotor of the stroke motor 4 causes the latch operation mechanism 16 and the scrum mechanism
Since all the mechanisms 11 move up and down, power is supplied from the outside to the latch operation mechanism 16 and the scrum mechanism 11 by the spring cable 14.

During maintenance, the drive shaft separating mechanism 13 is actuated by the latch operation mechanism 16 to drive the drive unit housing 17 to the upper guide tube portion 18.
And can be separated. The grip for detachably connecting the control rod 22 to the lower end of the control rod drive shaft 19 has a structure in which the finger 21 is operated by the movement of the latch shaft 20, which is the same as the conventional structure.

As described above, in the present embodiment, the stroke motor 4 and its rotation → vertical motion conversion mechanism are arranged in parallel, so that the drive unit can be significantly shortened. In this embodiment, the stroke motor 4 and the stroke operation rotation → vertical motion conversion mechanism are arranged in parallel, so that the entire control rod driving device can be shortened. The motor 9 for rotation and the rotation-to-up / down movement conversion mechanism for latch operation are similarly arranged in parallel, thereby achieving a double shortening.

In the following, it will be described that the present embodiment enables the same operation motor as that of the above-described conventional control rod driving device.

First, in the case of vertical drive as a normal drive, the rotation of the stroke motor 4 is transmitted from the stroke ball screw nut 2 to the stroke spline ball screw 1 via the stroke spline nut 3 as described above. , The scrum mechanism via the latch operation mechanism 16
Tell 11 Scrum mechanism 11 composed of hold magnet 25, armature 27 and magnet link mechanism 26
During normal operation, by energizing the magnet 25, the link mechanism 26 is closed, and the up / down drive of the latch operation mechanism 16 is transmitted to the control rod drive shaft 19 and the latch shaft 20 as they are. The holding at the fixed position and the stop at the time of the power failure are performed by the stroke electromagnetic brake 5.

Second, the scrum is a magnet in the scrum mechanism 11
This is performed by demagnetizing the link 25, releasing the link mechanism 26, and dropping the control rod drive shaft 19 and the control rod 22 located below the shaft integrally.

Third, at the time of refueling, the latch motor 9 is operated to push down the latch shaft 20 relatively with respect to the control rod drive shaft 19 to close the finger 21 and to separate the control rod 22 from the drive shaft 19. Thereafter, the stroke motor 4 is operated while the control rod 22 remains, and the latch operation mechanism 16 is pulled up. After the control rod 22 and the control rod drive shaft 19 are completely separated from each other, this time, the latch motor 9 is operated upward to cause the drive shaft lock mechanism 12 to act on the armature 27, and the control rod drive shaft 19
To prevent falling. The latching, delatching of the control rod 22 and the holding of the drive shaft locked state are performed by the latching electromagnetic brake 10 directly connected to the latching motor 9.

Fourth, the drive unit housing 17 is separated from the upper guide tube unit 18 by:
Similar to the conventional structure, the operation is performed by pushing down the latch shaft 20 further below the control rod separation position and releasing the ball latch of the drive shaft separation mechanism 13. In addition, the seal structure can be performed by a bellows or a seal as in the conventional structure.

In addition, the acceleration during scram is performed by using the same driving mechanism as in Fig. 2 and applying pressure to the bellows back pressure or housing back pressure, a method using a spring, a method using an acceleration cylinder as in the past, and using only its own weight without acceleration. A combination with various methods such as a method of dropping can be adopted.

In the conventional example, the drive unit length of the control rod drive device is: drive unit length = stroke motor unit + stroke unit + latch motor unit + latch stroke unit + drive shaft lock unit + acceleration cylinder unit. In the embodiment, the driving unit length =
It becomes a stroke part + a latch mechanism part, and the length can be reduced to about 1/2 or less. Further, as the length is shortened, the rigidity of the driving unit is increased, so that the conventionally provided earthquake-resistant support is not required, and the upper structure of the reactor can be simplified.

FIG. 3 shows another embodiment of the present invention. In this embodiment,
In the driving device for the control rod according to the above-described embodiment, while removing the latch motor from the latch operation mechanism,
The latching ball screw nut is disposed at the upper end of the latch operation mechanism, and the latching ball screw nut is rotated via a jig which can be attached to and detached from the latching operation mechanism, thereby moving the latching spline ball screw up and down. It is characterized by having been made to let
As described above, by moving the latch operation mechanism up and down by using a jig instead of the latch motor, the function required for the control rod drive device is not impaired at all, and the length can be further reduced.

At the time of refueling or maintenance, the latch ball screw nut 7 is rotated using a jig that can be rotated from the latch mechanism access hole 31, and the same operation as the embodiment of FIG. 1 is performed. Other operations can be performed in exactly the same manner as in the embodiment of FIG.

According to the present embodiment, it is possible to further reduce the number of components because the length is reduced and a latch motor is not required.

〔The invention's effect〕

According to the present invention, since the control rod drive device drive unit can be significantly shortened, the rigidity of the drive unit increases, seismic support is not required, and the reactor upper structure can be rationalized.
This has the effect of reducing the cost of the entire reactor structure.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a conventional example, and FIG. 3 is a longitudinal sectional view of another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Ball screw with spline for stroke 2 ... Ball screw nut for stroke 3 ... Spline nut for stroke 4 ... Motor for stroke 5 ... Electromagnetic brake for stroke 6 ... Ball screw with spline for latch 7 ... Latch Ball screw nut for latch 8 Spline nut for latch 9 Motor for latch 10 Electromagnetic brake for latch 11 Scrum mechanism 12 Drive shaft locking mechanism 13 Drive shaft separating mechanism 14 Spring Cable 15 Load cell 16 Latching mechanism 17 Drive housing 18 Upper guide tube 19 Control rod drive shaft 20 Latch shaft 21 Fingers 22 Control rod 23 Ball screw, 24 Ball screw nut 25 Hold magnet, 26 Magnet link mechanism 27 Armature electromagnetic brake 29 ...... bellows for 28 ...... stroke, holes for 30 ...... stroke motion mechanism 31 ...... latching mechanism Access

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masayoshi Sasaki 2-9-1, Aise-cho, Hitachi City, Ibaraki Prefecture Inside Hitachi Capital Engineering Co., Ltd. (56) References JP-A-61-178694 (JP, A) 62-217188 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G21C 7/14

Claims (2)

(57) [Claims] 1. A stroke motor having a hollow rotor installed on the upper surface of a rotary plug of a nuclear reactor, and a tubular ball screw with a spline for a stroke penetrating through the rotor of the stroke motor so as to be movable up and down relative to the rotor. ,
The ball screw with a spline for stroke is spline-engaged, and the spline nut for stroke for preventing rotation of the ball screw and the ball screw with a spline for stroke are screwed together. A stroke operation mechanism including a stroke ball screw nut for causing a stroke, a hollow control rod drive shaft penetrating the stroke splined ball screw so as to be able to move up and down relative thereto, and the control rod drive A latch shaft that is inserted into the shaft so as to be movable up and down relative thereto, and that enables the control rod drive shaft and the control rod to be disengaged from the latch; and an upper end portion of the ball screw with a spline for stroke. A scrum mechanism supported and releasably holding the control rod drive shaft; A latch motor having a hollow rotor mounted and installed on an upper part of a scrum mechanism, and a latch spline penetrating through the rotor of the latch motor so as to be movable up and down relative thereto and forming an upper portion of the latch shaft. A spline nut with a latch, a spline engagement with the latch spline ball screw, a latch spline nut for preventing the rotation thereof, and a screw engagement with the latch spline ball screw, which are rotated by the latch motor. A latch operation mechanism including a latch ball screw nut for moving the same relatively up and down with respect to the control rod drive shaft. 2. The control rod driving device according to claim 1, wherein said latch motor is removed from said latch operation mechanism, and said latch ball screw nut is disposed at an upper end of said latch operation mechanism. A control rod drive device characterized in that the latch ball screw nut is rotated via a jig which can be attached to and detached from the latch ball screw nut, thereby moving the latch spline-equipped ball screw up and down.