JPS5827474B2 - control rod drive mechanism - Google Patents

Description

Detailed Description of the Invention The present invention relates to a boiling water reactor control rod drive device (hereinafter referred to as CR).
D), and particularly relates to a CRD with an improved connection to a control rod (hereinafter referred to as CR).

In a boiling water reactor, a fuel assembly 2 is placed inside a pressure vessel 1 as shown in FIG. Controls the reactor.

The CRD is inserted and attached from the bottom into the CRD housing 4 attached to the bottom of the pressure vessel 1, and is connected to the CR at the top of the hollow piston of the CRD to drive the CR for the above purpose.

The driving types include a shim operation for adjusting and maintaining the reactor output at a predetermined state, and a scram operation for making an emergency shutdown of the reactor.

In a conventional CRD, the insertion and withdrawal operation of the CR is performed by vertically driving a hollow piston using water pressure.

In other words, the CR is inserted by supplying water under pressure from the import port and using the force applied to the lower and upper inner surfaces of the hollow piston, and the extraction is performed by supplying water under pressure from the out port, and after releasing the latch, water is removed from the import port, and the CR is removed. This is done by the weight of the hollow piston.

Furthermore, when the CHD is installed or removed, the CR and the hollow piston are separated and connected by operating an uncoupling piston using a connecting member located at the upper part of the hollow piston.

In the CRD having the above structure, in order to improve its driving performance, the upper part of the hollow piston is sufficiently sealed and the CRD is reliably sealed.
A connecting member that can separate and connect the R and the hollow piston is required.

In consideration of the above points, an object of the present invention is to improve the driving performance of a CRD by sufficiently sealing the upper part of a hollow piston, and to obtain a connecting member for a CHD that is highly reliable in terms of connection and separation functions with the CR. be.

The present invention will be described in detail below with reference to the drawings of one embodiment.

First, the structure of the entire CRD (see FIG. 2) will be explained.

The CRDT section has a flange 23 with eight bolt holes for attaching the CRD to the CRD housing 4.

The flange 23 has a ring shape with a hole in the center, and is provided with one inlet 25 and one outport 26.

An outer tube 18 and a cylinder tube 19 are concentrically welded to the inner surface of the flange 23.

A piston tube 16 is disposed in the CRD center shaft, and the lower part thereof is fitted into the inner surface of the flange 23 and fixed with a nut 24.

A sealing material 14 is provided on the fitting surfaces of the piston tube 16 and the inner surface of the flange 23.

The diameter of the upper part of the piston tube 16 is increased in steps, and a disc spring 17 is attached to the lower part thereof.

The piston tube 16 has a hollow shape, and a position indicating device is installed inside the piston tube 16.

Between the hollow piston 16 and the cylinder tube 19,
A hollow piston 13 is fitted and can freely move up and down.

A gap is provided between the outer circumferential surface of the piston tube 16 and the inner surface of the hollow piston 13 to allow water to flow freely, and a seal is provided at the bottom of the hollow piston 13 to seal between the outer circumferential surface and the cylinder tube 19. It is equipped with material 15.

The outer surface of the hollow piston 13 is provided with circumferential notches at regular intervals over its entire length, and the notches are provided with a collet piston 20 fitted to the cylinder tube 19 and the outer tube 18. The collet fingers of the book interlock.

A connecting member with CR5 is attached to the upper part of the hollow piston.

Next, details of the connecting member will be explained.

As shown in FIG. 3, the connecting member includes a piston tube 15, a spud 10, a cylinder 30, a cap 31, and an uncoupling rod 11.

As shown in FIG. 2, the piston tube 16 is connected to the CR
D, the upper end is located at the lower part of the ano coupling rod 11, the lower part passes through the flange 23,
A sealing material 14 is attached to maintain the pressure within the pressure vessel 1.

The piston tube 16 is normally fixed, but C
Only when R5 and the hollow piston 13 are to be separated, the nut 24 is removed and the piston can be moved up and down a predetermined distance.

The spud 10 has a cylindrical shape and is attached to the top of the hollow piston 13 by a screw cut into the outer surface of the lower part of the spud 10.

The upper part of the spud 10 has six tongue shapes, each of which has a spring force and can be displaced in the radial direction.

A female thread is cut on the lower inner surface of the spud 10, and a cylinder 30 is attached thereto.

The cylinder 30 has a cylindrical shape with a stepped inner surface.

A labyrinth is formed on the upper inner surface with a smaller diameter, and a lower inner surface with a larger diameter is a uniform cylindrical surface.

Two types of flow passages 32 and 33 are formed in the cylinder 30. The flow passage 32 penetrates to the upper part of the inner peripheral surface, which has a larger diameter than the outer circular surface of the cylinder 30, and the flow passage 33 extends inside the cylinder wall. The lower part of the flow passage 33 extends parallel to the axis of the cylinder 30 and communicates with the inside of the cylinder 30 by a groove.

The lower outer peripheral surface of the cylinder 30 is threaded,
Cap 31 is attached.

The cap 31 serves as a lower lid of the cylinder 30, and a labyrinth is formed on the inner diameter surface of the bottom.

The uncoupling rod 11 has a rod shape with a piston part having a labyrinth formed on the outer periphery, and the piston part is enclosed in the cylinder 30 and the cap 31 and can slide up and down on the inner surface of the cylinder. The rod-shaped portion can slide up and down on the upper and lower labyrinth surfaces.

The outer surface of the uncoupling rod 11 is subjected to surface hardening treatment to prevent galling.

In addition, all screw joints of the connecting member are banded or
It is rolled up by spot welding.

Next, the function and operation of the device described above will be explained.

First, the entire CRD will be explained. The operation of CRD is as follows:
Normal insertion and withdrawal operations (shim operations) and emergency insertion operations (
Scrum behavior).

A normal insertion operation is performed by supplying water from the import 25 at a pressure slightly higher than the furnace pressure.

At this time, the upper part of the hollow piston 13 is sufficiently sealed by the connecting member, and the sealing material 15 also seals between the outer peripheral surface of the lower part of the hollow piston 13 and the cylinder tube 19, so that the inside of the hollow piston 13 is The pressure is higher than that of the cylinder, and this force causes the hollow piston 13 to be inserted upward.

By stopping the water supply after inserting the hollow piston 13 to a predetermined position, the collet finger 21 engages the notch on the outer surface of the hollow piston, supports the hollow piston 13, and performs positioning.

At the time of emergency insertion, water is supplied from the import 25 at a pressure sufficiently higher than the furnace pressure, and the insertion is performed using the same principle as above.

At this time, the piston insertion speed becomes a very large value,
At the end of the stroke, the piston tube 16 is gradually decelerated and stopped by the disc spring 17 above it.

To perform the pulling operation, first supply pressurized water from the import 25, insert the hollow piston 13 a little, and then press the collet finger 21.
After that, pressurized water is supplied from the out port 26, the collet piston 20 is pushed up, the collet finger 21 is pushed outward by the guide cap 22, and with the latch free, the water is removed from the import 25. Then, the hollow piston 13 is pulled downward by its own weight.

When the hollow piston 13 is pulled out to a predetermined position, if water removal from the import 25 and pressurized water supply from the out port 26 are stopped, the collet finger 21 returns to its original position.
Positioning takes place once in a cutout in the hollow piston.

Next, the combined operation of CRD and CR5 is shown in Figures 2 and 4.
This will be explained with reference to the figures.

When the CHD and CR5 are separated, the hollow piston 13
is at the lowest position, and the upper connecting member is at a position farther from the lower CR5.

From this state, when water is supplied under pressure from the import 25 and the hollow piston 13 is gradually inserted, the six tongue-shaped portions at the top of the connecting member reach the bottom of the CR5 and then move toward the center along the inner surface. By bending in the direction, it is fully inserted into the CR5 lower part.

At this time, the lock plug 12 is once lifted by the tongue-like part of the connecting member bent toward the center, but the tongue-like part is
Upper lock plug 1 when fully inserted into the lower part of R5
2. The spring 40 causes the connector member 10 to fit into the tongue-shaped portion.

Thus, unless the lock plug 12 is lifted by the uncoupling rod 11, the lock plug 12
fits within the tongue of the connecting member.

Therefore, since the tongue portion is prevented from bending toward the center, the connecting member does not come off from the lower part of the CR5, and the connection between the hollow piston 13 and the CR5 is securely maintained.

(See FIG. 4a) Next, the operation of separating CHD and CR5 will be explained.

At the time of separating CRD and CR5, the lower part of CR5 is
The hollow piston 13 is pulled out until it comes into contact with the lower taper part of the guide tube 3 and is sealed against reactor water.

In this state, by pushing up the piston tube 16 a predetermined distance, the uncoupling rod 11 is pushed up, and the lock plug 12 in the connecting member is removed upward.

Next, when water is removed from the import 25, the hollow piston 13
Due to its own weight, a downward force is applied to the connecting member, and the tongue-shaped portion at the top of the connecting member bends toward the center, causing the hollow piston 1
3 and CR5 are separated.

(See Figure 4) Next, the action and operation of the connecting member when driving the control rod will be explained.

Among the shim operations, the insertion operation is performed by supplying water from the import 25 at a pressure slightly higher than the furnace pressure and applying force to the lower surface and upper inner surface of the hollow piston 13.

The scram operation is performed by injecting high pressure water from the import 25 and applying force to the lower and upper inner surfaces of the hollow piston.

During any of the above operations, the inside of the hollow piston 19 is always under higher pressure than the outside.

In this state, the force applied to the uncoupling rod 11 is designed so that it is always directed downward as explained below.

In other words, the uncoupling rod 11 and the cylinder 30
and the cap 31 are sealed by a labyrinth, so the downward force is the force of the spring 40, the force obtained by multiplying the cross-sectional area of the small diameter part of the uncoupling rod 11 by the pressure inside the pressure vessel, and the force applied downward. The force obtained by subtracting the cross-sectional area of the small diameter part from the cross-sectional area of the large diameter part of the uncoupling rod 11 multiplied by the pressure applied from the port 25 and the weight of the uncoupling rod 11 is added,
The force applied upward is applied to the uncoupling rod 11.
It is calculated by multiplying the area of the small diameter part by the pressure applied from the port 25.

The area of each of the above parts is determined so that the downward force is greater than the upward force, and the uncoupling rod 11 is pressed downward.

Therefore, during scram operation and normal insertion operation,
The uncoupling rod 11 is always held at the lowermost end, and the connection between CRD and CR5 is maintained.

Further, during the above operation, pressure needs to be accumulated in the hollow piston 13, but the connecting member is sufficiently sealed due to the sealing effect of the labyrinth, and its function is fulfilled.

During normal pulling operation, the inside of the hollow piston 13 is in a slightly lower pressure state than the outside, but since the force applied to the uncoupling piston 11 is always in the downward direction, CR5
The connection between the hollow piston 13 and the hollow piston 13 is maintained.

As explained above, the CRD connecting member according to the present invention is
In any operating mode of the RD, connection with the control rods is reliably maintained, and operations for connection and separation can be easily performed.

Furthermore, since the upper end of the hollow piston is sufficiently sealed, the performance of the CRD can be improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the installed state of a CRD in a boiling water reactor, FIG. 2 is a vertical cross-sectional view of a CRD according to an embodiment of the present invention, and FIG. 3 is a detailed cross-sectional view of the connecting portion of FIG. 2. , FIG. 4 shows the connected state of the connecting parts, where a is a diagram of the connected state and b is a diagram of the open state. 4...CRD housing, 21...Collet finger 23...Flange, 25...
...Import, 26...Out port, 30...Cylinder 31...Cap, 32...-Flow path, 33...-・Flow path.

Claims (1)

[Claims] 1. A hollow piston that moves up and down by hydraulic pressure in a housing installed at the bottom of the pressure vessel, and a plurality of injection ports that supply liquid that applies pressure to the up and down movement of this hollow piston.
A control rod drive mechanism comprising a flange fixed to the lower part of the housing and a latch mechanism that prevents the hollow piston from driving, the control rod drive mechanism including a cylinder member installed inside the upper end of the hollow piston, and a rod that moves up and down within the cylinder. A control rod drive mechanism comprising a member and a sealing mechanism installed between the rod member and the cylinder member.