JPS6241277Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a moving coil type nuclear reactor control rod drive device, particularly to an improvement of its snubber cylinder.

[Conventional technology]

FIG. 5 shows a longitudinal sectional view of a conventional moving coil type nuclear reactor control rod drive device. In the figure, the pressure pipe 1 is connected to the reactor vessel (not shown) at the top, and the drive shaft 2 inserted into the pressure pipe 1 is connected to the control rod (not shown) at the top, and the full power is output at the top end position. , respectively provide a shutdown of the furnace at the lower end position. In this reactor control rod drive device, the control rods are located above the reactor core (during normal operation), and the drive mechanism, which will be described later, is located below the reactor core. That is, by operating the drive mechanism 2 below the core, the upper control rods are moved in and out of the core. The electromagnetic plunger 3 is for vertically moving the drive shaft 2 inserted into the pressure tube 1, and the movable coil 4 disposed around the outer periphery of the pressure tube 1 is composed of an electromagnetic coil and its feeding mechanism. When this electromagnetic coil is excited, the plunger 3 and the movable coil 4 are magnetically coupled through the wall surface of the pressure tube 1. When the movable coil 4 is moved up and down in this state, the plunger 3 is moved accordingly. That is, the control rod is driven. The coil hold cover 5 is provided for earthquake resistance and suppresses displacement of the movable coil 4 and the plunger 3 in the lateral direction.

Further, the snubber piston 6 projects from the lower end of the plunger 3, and its tip can enter into the upper hollow of the snubber cylinder 7. (The figure shows a state in which the piston 6 has completely penetrated into the hollow part of the upper part of the cylinder 7.) This snubber cylinder 7 is inserted inside the lower end side of the pressure pipe 1, and its lower end is connected to the lower end of the coil hold cover 5. It is connected and held by a cylinder support member 8 attached to the cylinder. The inside of the snubber cylinder 7 is partitioned into upper and lower parts by a partition wall 9, and a plurality of upper and lower flow holes 10 and 11 are provided at predetermined positions in the upper and lower parts, respectively.
is open, and an annular recess 12 connecting the upper and lower communication holes 10 and 11 is formed on the outer peripheral surface. That is, the upper and lower hollow portions of the snubber cylinder 7 are connected by a flow path consisting of a flow hole 10, an annular recess 12, and a flow hole 11. Further, an on-off valve 13 is installed below the snubber cylinder 7, which is used to close the snubber cylinder 7 during disassembly and replacement work.

The above structure constitutes the so-called pressure boundary of the nuclear reactor, and is disposed and supported by the reactor vessel or an immovable structural part connected thereto.

The inside of these fixed parts is filled with a primary coolant, and the drive shaft 2, plunger 3, snubber piston 6, etc. are integrated therein and interlocked in the axial direction. During normal operation, the moving coil 4 outside the pressure pipe is excited, and the plunger 3 follows and moves by the magnetic coupling force of the moving coil 4. On the other hand, during a scram (in the event of an emergency shutdown of the reactor), the moving coil 4 is energized. The excitation is cut off and the magnetic coupling force is eliminated, and the integrated snubber piston 6, plunger 3, drive shaft 2, and control rod rapidly fall under their own weight, that is, the control rod is inserted into the reactor core. The reactor is shut down.
In the event of a fall, first of all, when the snubber piston 6 is above the snubber cylinder 7, the primary coolant under the plunger 3 is released upward through the gap between the plunger 3 and the pressure pipe 1, and the arrow As shown in FIG.
and escapes downward through the annular recess 12. In this way, the primary coolant that interferes with free fall is discharged. Next, when the lower end of the snubber piston 6 enters the snubber cylinder 7, passes through the position of the circulation hole 10, and approaches the partition wall 9, that is, when it approaches the stop position, there is a gap between the lower end of the snubber piston 6 and the partition wall 9. The primary coolant trapped in the snubber piston 6 creates pressure for a damping action or snubber.
As a result, the impact of the fall of the drive shaft 2 is buffered and the drive shaft 2 stops.

[Problem that the invention attempts to solve]

In the conventional moving coil reactor control rod drive device as described above, the snubber cylinder 7 is inserted into the inner surface of the lower end of the upper pressure pipe 1, and the snubber cylinder 7 and the pressure pipe 1 are not connected. do not have. If the connection is made by welding as shown in Fig. 6a (a partially enlarged view of the welded part is shown in Fig. 6b), when replacing the snubber cylinder 7 due to roughness of the inner surface, etc. There is a disadvantage that the pressure tube 1 that is in use must be disposed of as well, which is uneconomical.

Therefore, the weight of the snubber cylinder 7 is supported by the coil hold cover 5. Therefore, if it is necessary to disassemble the coil hold cover 5 to remove it from the drive device, for example, if the movable coil 4 inside the coil hold cover 5 is to be replaced due to a failure, etc., before removing the coil hold cover 5, It is necessary to close the on-off valve 13 at the bottom of the cylinder 7 and then support the weight of the snubber cylinder 7 with some kind of support means. Therefore, the removal work of the coil hold cover 5 is complicated and takes a long time, and the worker's exposure to radiation increases.

This idea was made in order to solve these problems, and to provide a moving coil type nuclear reactor control rod drive device that can be easily disassembled in a short time and that allows economical replacement of the snubber cylinder. With the goal.

[Means for solving the problem] The moving coil type nuclear reactor control rod drive device according to this invention has a Snatsuba cylinder outer cylinder welded to a pressure pipe, and a Snatsuba cylinder that is detachably attached to the outer cylinder. The above-mentioned problem is solved by comprising a snubber cylinder body that is inserted and fitted by means.

[Effect]

In this invention, the Snatsuba cylinder is composed of a Snatsuba cylinder outer cylinder welded to a pressure pipe and a Snatsuba cylinder main body that is inserted into this outer cylinder by a removable attachment means. The weight of the cylinder is supported by the pressure tube, and the snubber cylinder body can be replaced without discarding the pressure tube.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1a shows an example in which the snubber cylinder is composed of a snubber cylinder outer cylinder welded to a pressure pipe, and a snubber cylinder main body that is inserted into the outer cylinder by a detachable attachment means, and the snubber cylinder is connected to the pressure pipe. Only the Snatsuba cylinder is shown.

In the figure, the snubber cylinder 70 is composed of a detachable snubber cylinder main body 7a and a snubber cylinder outer cylinder 7b. 1 is welded to the lower end. (Welded part 15
is shown in FIG. 1b, a partially enlarged view. ) On the other hand, a threaded portion 16b is formed on the inner periphery of the lower end of the outer cylinder 7b as a detachable attachment means.

Similarly, a threaded portion 16a is screwed into the threaded portion 16b at a predetermined position on the lower end side circumferential surface of the cylinder body 7a.
is engraved. The inner peripheral surface on the upper end side of the cylinder body 7a following this threaded portion 16a is the cylinder outer cylinder 7b.
It is formed so that it can be inserted into the inner peripheral surface.

Therefore, the weight of the snubber cylinder 70 is borne by the pressure pipe 1.

Further, the structure of the snubber function such as the primary coolant circulation hole is similar to the structure of the snubber cylinder of the moving coil type nuclear reactor control rod drive device of the prior art, and the snubber cylinder main body 7a is A partition wall 9a and communication holes 10a, 11a are provided corresponding to the partition wall 9 and communication holes 10, 11 of the snubber cylinder 7 shown in FIG. However, the annular recess 12 of the snubber cylinder 7 of the prior art
In the present invention, the annular recess 12 is provided in the cylinder outer tube 7b.
b, but its effect is the same as that of the conventional one.

FIG. 2 shows another embodiment of the present invention in a vertical sectional view of the main part. Figures 3a and 3b are schematic perspective views thereof, with Figure 3a showing the cylinder body and Figure 3b showing the cylinder outer cylinder.

This uses a bayonet joint as a detachable attachment means, and an engagement pin 17 is provided protrudingly at a predetermined position on the circumferential surface of the cylinder body 7c, and an approximately inverted L-shape is provided at a predetermined position on the lower end side of the cylinder outer cylinder 7d. A shaped guide groove 18 is provided, and the engagement pin 17 is inserted into the guide groove 1.
8 and is connected to the engaging portion 18p at the tip of the guide groove 18. Therefore, the structure is such that the cylinder main body 7c does not come off from the cylinder outer cylinder 7d even with some vibration.

Note that although FIG. 2 and FIG. 3b show a notch 14 provided on the upper end circumferential surface of the cylinder outer cylinder 7d so as to open from the annular recess 12b to the upper end, such a cutout may be made as necessary. Providing the cutout portion 14 has the effect that the primary coolant can be removed more quickly during scramming, and the scramming time can be further shortened.
In this case, after the snubber operation is completed, the primary coolant flows through the notch 14 and the annular recess 12d, which has the effect of preventing minute dust from accumulating in the annular recess 12b and the lower hollow part of the cylinder body 7a. be.

The longitudinal sectional view of the main part shown in Figure 4 is shown in Figures 2 and 3.
This makes the attachment of the cylinder outer cylinder and the cylinder body as shown in Figures a and b more stable, and the flange 19 provided at a predetermined position on the lower end circumferential surface of the cylinder body 7e and the lower end surface of the cylinder outer cylinder 7f. An elastic body 20 made of rubber or the like is interposed therebetween so that a pressing force is constantly applied to the elastic body 20 to reliably hold the snubber cylinder body 7e in the cylinder outer cylinder 7f.

[Effect of idea]

As explained above, this invention consists of a snubber cylinder of a moving coil type nuclear reactor control rod drive device, a snubber cylinder outer cylinder welded to the lower end of a pressure tube, and a detachable attachment means to this snubber cylinder outer cylinder. Since the weight of the Snatsuba cylinder is supported by the pressure pipe by inserting and fitting the Snatsuba cylinder body into the Snatsuba cylinder body, when removing the coil hold cover for coil replacement etc. This eliminates the need for supporting the weight of the cylinder, making the work easier and faster. This reduction in work time also has the effect of reducing the risk of radiation exposure to workers associated with the work.

Furthermore, even though the Snatsuba cylinder outer cylinder is welded to the pressure pipe, the Snatsuba cylinder body is removable, so during maintenance, only the Snatsuba cylinder body can be replaced without discarding the pressure pipe. There is also an economic effect.

[Brief explanation of the drawing]

Figures 1a and b are longitudinal sectional views of essential parts showing one embodiment of this invention, Figure 2 are longitudinal sectional views of essential parts showing another embodiment, and Figures 3a and b are the cylinder body and cylinder of Fig. 2. FIG. 4 is a schematic vertical cross-sectional view showing another embodiment; FIG. 5 is a vertical cross-sectional view showing a conventional moving coil reactor control rod drive device; FIG. 6 a, b The figure is a vertical cross-sectional view of a main part of a conventional moving coil type nuclear reactor control rod drive device. In the figure, 1 is a pressure pipe, 2 is a drive shaft, 3 is an electromagnetic plunger, 4 is a moving coil, 5 is a coil hold cover, 6 is a snubber piston, 70 is a snubber cylinder, 7a, 7c, and 7e are snubber cylinders The main body, 7b, 7d, 7f are the snubber cylinder outer cylinder, 8 is the snubber cylinder support member, 13 is the on-off valve, 14 is the notch, 16a, 16b is the threaded part,
17 is an engagement pin, 18 is a guide groove, 19 is a flange, and 20 is an elastic body. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A pressure pipe connected to the reactor core and containing primary coolant, a drive shaft inserted into this pressure pipe connected to the reactor control rod above, and this drive shaft. an electromagnetic plunger as a driving mechanism; a snubber piston hanging down from the lower end of the electromagnetic plunger; a snubber cylinder inserted into the lower part of the pressure pipe so that the snubber piston enters; an on-off valve connected to the lower part of the pressure pipe, a cylinder support member that extends around the outer periphery of the lower end of the pressure pipe and engages and supports the snubber cylinder, and a magnetic coupling via the electromagnetic plunger and the pressure pipe. a movable coil consisting of a vertically movable electromagnetic coil wound around the outer periphery of the pressure pipe and a feeding mechanism therefor; a coil hold cover surrounding the movable coil and the pressure pipe via the cylinder support member; A moving coil reactor control rod drive device comprising: a tubular snubber cylinder outer cylinder that is inserted into the lower part of the pressure pipe and welded; A moving coil type nuclear reactor control rod drive device comprising a snubber cylinder body that is inserted into the body by a flexible attachment means. (2) The movable device according to claim 1, wherein the removable attachment means includes threaded portions formed on the snubber cylinder body and the snubber cylinder outer cylinder. Coil type reactor control rod drive device. (3) The moving coil type according to claim 1, wherein the detachable attachment means includes a bayonet joint that connects the snubber cylinder body and the snubber cylinder outer cylinder. Reactor control rod drive system. (4) The removable attachment means includes a flange portion provided on the lower outer periphery of the snubber cylinder body, and an elastic body interposed between the flange portion and the lower end of the snubber cylinder outer cylinder. Claim 1 for utility model registration characterized by including
The moving coil type nuclear reactor control rod drive device described in 2.