JPH10246790A - Control rod drive - Google Patents

Abstract

(57) [Problem] To provide a control rod drive device capable of suppressing a temporary pressure rise at the end of a scrum operation. A drive water pressure release groove (200) is provided along the vertical direction on an inner wall of a cylinder tube (105) with which the drive piston (108) contacts at a position where the drive piston (108) is excessively inserted. Is released into the reactor through the driving water pressure release groove 200.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a boiling water reactor (B)
The present invention relates to a hydraulic control rod driving device of WR), and aims to suppress a temporary increase in pressure in the control rod driving device and the driving water supply pipe, which is generated particularly at the end stage of the reactor emergency shutdown operation. To a control rod drive.

[0002]

2. Description of the Related Art Generally, in a BWR, a coolant and a core are housed in a reactor pressure vessel, and the core is composed of a plurality of fuel assemblies, control rods and the like. The control rod is driven by a control rod drive (CRD) to adjust the amount of insertion into the core, thereby controlling the core power.

The configuration of a conventional control rod driving device will be described with reference to FIGS. 7 and 8. FIG. FIG.
Shows the longitudinal sectional structure of the control rod drive device according to the prior art,
FIG. 8 is an enlarged cross-sectional view taken along the line AA in FIG.

In FIG. 7, reference numeral 1 partially shows a bottom wall of the reactor pressure vessel, a CRD housing 2 is fixed to the bottom wall 1, a CRD main body 103 is inserted into the CRD housing 2, and a flange is provided. 103a.

The structure of the CRD body 103 will be described in detail. First, an outer tube 104 and a cylinder tube 105 are arranged on the inner peripheral side of the CRD housing 2. An index tube 106 is disposed on the inner peripheral side of the cylinder tube 105, and a piston tube 107 is disposed on the inner peripheral side of the index tube 106.
Is arranged.

The index tube 106 is movable up and down, and has a bayonet coupling 10 at the upper end.
6a is provided, and a CRD after coupling with a control rod (not shown) is provided.
The main body 103 is connected by rotating it by 45 °. A drive piston 108 is provided at the lower end of the index tube 106.

[0007] A plurality of recessed latch grooves 106b are provided in the outer peripheral portion of the index tube 106.
As shown in FIG. 8, a plurality of (three) guide grooves 106c, which are concave portions, are provided on the inner surface in the axial direction. Further, an orifice 106d penetrating inside and outside is provided at the upper part of the index tube 106.

A buffer shaft 109 is connected to an upper portion of the piston tube 107, and the buffer shaft 109
A buffer piston 110 and a buffer spring 111 are arranged on the outer periphery of the device, and a stop piston 112 is attached so as to cover them.

As shown in FIG. 8, three rollers 113 are connected to the upper part of the stop piston 112 in the same direction, and are fitted with the guide grooves 106c of the index tube 106. The lower end of the piston tube 107 is fixed to the flange 103a so that the piston tube 107 does not move in the axial direction and the circumferential direction.

A control rod positioning mechanism 114 is provided above the outer tube 104 and the cylinder tube 105 and between the two tubes. This positioning mechanism 114
Are collet piston 115, collet finger 116
And a return spring 117.
Then, the tip of the collet finger 116 is configured to hold the position of the control rod by fitting into any one of the plurality of latch grooves 106b provided in the index tube 106.

An insertion port 118 is formed in the flange 103a and communicates with the lower surface space of the drive piston 108 to supply driving water from a hydraulic system (not shown) to the lower surface of the drive piston 108.

The flange 103a is provided with a collet piston operating port 119 which communicates with the lower surface of the collet piston 115 through the space between the outer tube 104 and the cylinder tube 105 to supply pressurized water to the lower surface of the collet piston 115. Have been.

Further, a guide cap 120 is provided on the upper end of the outer tube 104, and when the collet piston 115 is pushed up, the collet finger 1
The collet finger 16 is configured to be able to be pushed out so that the tip of the collet finger can be removed from the latch groove 106b of the index tube 106.

Next, the operation of the control rod driving device having the above configuration will be described.

In the control rod driving device having the above structure, when a control rod (not shown) is inserted into the core, driving water is supplied from the insertion port 118 and the drive piston 108 is driven.
And the inner surface of the index tube 106 is pressurized to raise the index tube 106, thereby inserting the control rod into the furnace.

At this time, water between the index tube 106 and the cylinder tube 105 is discharged into the furnace through a gap between the guide cap 120 and the index tube 106. When the control rod is inserted to a predetermined position, the tip of the collet finger 116 fits into the latch groove 106b of the index tube 106, and the insertion position of the control rod is maintained.

When the control rod is pulled out, pressurized water is supplied from the collet piston operation port 119, and the collet piston 115 is pushed up. Then, the collet finger 116 is pushed open by the guide cap 120,
The tip of the collet finger 116 comes off the latch groove 106b of the index tube 106.

As a result, the index tube 106 is lowered by the weight of the control rod and the movable portion such as the index tube 106, and the control rod is pulled out of the core.
The water on the lower surface of the drive piston 108 and the inner surface of the index tube 106 flows out of the insertion port 118 to the outside.

At the time of an emergency shutdown of the reactor (hereinafter referred to as a scram), high-pressure driving water is supplied from the insertion port 118, and the lower surface of the drive piston 108 and the inner surface of the index tube 106 are pressurized. As a result, the control rod is also inserted into the core at a high speed.

When it is not necessary to operate the control rod driving device during normal operation of the nuclear reactor, cooling water is constantly supplied from a hydraulic system (not shown) to the insertion port 118. The gas flows into the reactor through the orifice 106d through the inner surface of the index tube 106.

[0021]

However, the conventional control rod driving device having the above configuration has the following problems.

That is, when the drive piston is decelerated and stopped by the buffer mechanism at the end of the scram operation, the flow path of the high-pressure drive water flowing from the insertion port is instantaneously cut off, so that the control rod drive device containing the drive water is provided. And the pressure in the pipe connected to the insertion port temporarily increases. Therefore, the piping connected to the control rod driving device and the insertion port needs to have a structure that can withstand this temporary high pressure.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a control rod driving device capable of suppressing a temporary pressure rise at the end of a scram operation. .

[0024]

That is, a first aspect of the present invention provides a control rod drive mechanism housing fixed to a bottom wall of a reactor pressure vessel, an outer tube housed in the control rod drive mechanism housing, and A vertically movable index tube having a cylinder tube, a control rod connected to the upper end, a drive piston provided at the lower end, a piston tube housed in the index tube, and the piston A buffer mechanism that is disposed above the tube and decelerates and stops the drive piston that has been rapidly raised during the scrum operation, and a collet finger is engaged with a latch groove provided on an outer peripheral portion of the index tube so that the index tube is moved. A positioning mechanism for locking at a desired height position; In a control rod drive device having an insertion port for flowing drive water into the lower part of the ebu piston and raising the index tube, in the scram operation, the drive piston is raised and decelerated and stopped by the buffer mechanism. When you reach the position,
A drive water release flow path is provided, which allows the drive water flowing below the drive piston to flow into the reactor.

According to a second aspect of the present invention, in the control rod driving device according to the first aspect, the drive piston is raised during a scram operation, and the drive piston is decelerated by the buffer mechanism.
When reaching the over-insertion position to be stopped, the drive water release flow path is formed vertically above the inner peripheral wall of the cylinder tube so as to form a drive water release flow path that passes through the side of the drive piston and extends above the cylinder tube. A driving water release groove is provided along the direction.

According to a third aspect of the present invention, in the control rod driving device according to the first aspect, the drive piston is raised during a scram operation, and the drive piston is decelerated by the buffer mechanism.
A drive water release port is provided in the cylinder tube and the outer tube such that a drive water release passage that penetrates the cylinder tube and the outer tube is formed when reaching the excessive insertion position to be stopped. It is characterized by.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a control rod drive mechanism according to the present invention will be described below with reference to FIGS.

FIG. 1 shows the configuration of a main part of a control rod driving device according to an embodiment of the present invention, and FIG.
FIG. 3 shows an enlarged cross section taken in the direction of arrow A, and FIG. 3 shows a state of returning to the full insertion position after the completion of the scrum operation. FIG. 4 shows a main configuration of a control rod driving device according to another embodiment of the present invention, and FIG. 5 is an enlarged cross-sectional view taken along the line AA in FIG. FIG. 6 shows a state where it returns to the full insertion position after the completion of the scrum operation. In addition, in these FIGS. 1 to 6, FIG.
Parts corresponding to those of the conventional control rod driving device shown in FIG. 8 are denoted by the same reference numerals.

In the control rod driving device shown in FIG. 1, a CRD housing 2 is fixed to a bottom wall 1 of a reactor pressure vessel.
The CRD main body 103 is inserted into the CRD housing 2, and is fixed by the flange 103a shown in FIG. FIG. 1 shows a state immediately after the scram operation of the control rod driving device according to the present embodiment. In this state,
Drive piston 108 is over-inserted. That is, the buffer piston 110 and the buffer spring 11
This shows a state immediately after the drive piston 108 is decelerated and stopped by the buffer mechanism composed of 1 or the like.

In the control rod driving device according to this embodiment, as shown in FIG. 2, the inner wall of the cylinder tube 105 where the drive piston 108 comes into contact with the over-inserted position as shown in FIG. A plurality of driving water pressure release grooves 200 are provided, and the driving water that has pushed up the lower surface of the drive piston 108 is released into the reactor through the driving water pressure release grooves 200. . Therefore, a temporary increase in pressure on the lower surface of the drive piston 108 during scram is suppressed.

When the pressure of the driving water pushing up the lower surface of the drive piston 108 is released and falls, the drive piston 108 descends by its own weight of the index tube 106 and the control rod (not shown), and the collet finger 116 The claw is held at the position shown in FIG. 3 (the control rod full insertion position) by engaging with the latch groove 106b of the index tube 106.

In this state, the position of the inner wall of the cylinder tube 105 with which the drive piston 108 comes into contact is lower than the position where the driving water pressure release groove 200 is provided. In other words, in this state, there is no drive water pressure release groove 200 on the inner wall of the cylinder tube 105 in contact with the drive piston 108, and therefore, the coolant in the furnace does not flow backward to the lower surface side of the drive piston 108. Also, when the control rod is inserted by the scrum, the driving water on the lower surface of the drive piston 108 is not released through the driving water pressure release groove 200 until the drive piston 108 reaches this position, that is, the entire control rod insertion position. So
There is no delay in the control rod insertion time up to the control rod full insertion position.

Next, another embodiment of the present invention shown in FIGS. 4 to 6 will be described.

FIG. 4 shows the end stage of the scram operation of the control rod drive device according to this embodiment, in which the control rod is inserted at the maximum, that is, the drive piston 1 is moved.
Reference numeral 08 indicates a state where the vehicle stops at the vertex.

In the control rod driving device of this embodiment, as shown in FIG. 5, when the drive piston 108 is excessively inserted as described above,
8, a plurality of drive water pressure release ports 210 that form a water passage extending from the inner wall of the cylinder tube 105 to the inner surface of the CRD housing 2 are provided. Therefore, in this state, the drive piston 10
Since the driving water that has pushed up the lower surface of the drive piston 8 is released into the reactor through the driving water pressure release port 210, a temporary increase in pressure on the lower surface of the drive piston 108 is suppressed. In FIG. 5, reference numeral 211 denotes a collet driving water port through which collet driving water for pushing up the collet piston 115 flows.

When the pressure of the driving water pushing up the lower surface of the drive piston 108 is released and falls, the drive piston 108 descends by its own weight of the index tube 106 and the control rod (not shown), and the collet finger 1
16 claws are in the latch groove 10 of the index tube 106.
6b (the control rod full insertion position) is held.

In this state, the drive piston 108
Is located below the drive water pressure release port 210, there is no water passage below the drive piston 108 from the inner wall of the cylinder tube 105 to the inner surface of the CRD housing 2, and the coolant in the furnace is
8 does not flow back to the lower surface side. Also, when the control rod is inserted by the scrum, the drive water on the lower surface of the drive piston 108 is not released until the drive piston 108 reaches this position, that is, the control rod full insertion position. There is no delay in rod insertion.

As described above, in any of the above-described two embodiments, since the pressure increase immediately after the end of the scram operation on the lower surface of the drive piston 108 is suppressed, the pressure considered in design can be reduced. it can. Further, since the load on the buffer mechanism for stopping the drive piston 108 can be reduced, the structure of the buffer mechanism can be simplified, and the manufacturing cost of the control rod driving device can be reduced.

The design pressure of the piping connected to the insertion port 118 shown in FIG. 7 can be similarly reduced. In addition, since the load on the supports is reduced, the support structure can be designed to be compact, and the arrangement space can be rationalized. Therefore, the cost of manufacturing and installing the pipes and supports can be reduced.

[0040]

As described above, according to the control rod driving device of the present invention, it is possible to suppress a temporary pressure rise at the end of the scrum operation.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a control rod driving device according to the present invention.

FIG. 2 is an enlarged cross-sectional view showing a cross-sectional structure taken along the line AA of FIG. 1;

FIG. 3 is a longitudinal sectional view showing a completed state of a scrum of the control rod driving device of FIG. 1;

FIG. 4 is a longitudinal sectional view showing another embodiment of the control rod driving device according to the present invention.

FIG. 5 is an enlarged cross-sectional view showing a cross-sectional structure taken along line AA of FIG. 4;

FIG. 6 is a longitudinal sectional view showing a completed state of a scrum of the control rod driving device of FIG. 4;

FIG. 7 is a longitudinal sectional view of a control rod driving device according to the prior art.

FIG. 8 is an enlarged cross-sectional view showing a cross-sectional structure taken along the line AA of FIG. 7;

[Explanation of symbols]

 1 Bottom wall of reactor pressure vessel 2 CRD housing 103 CRD body 104 Outer tube 105 Cylinder tube 106 Index tube 106 b Latch groove 107 Piston tube 108 Drive Piston 109 buffer shaft 110 buffer piston 111 buffer spring 112 stop piston 113 roller 114 positioning mechanism 115 collet piston 116 collet finger 117 return spring 120 guide Cap 200: Drive water pressure release groove 210: Drive water pressure release port

Claims (3)

[Claims] 1. A control rod drive mechanism housing fixed to a bottom wall of a reactor pressure vessel; an outer tube and a cylinder tube housed in the control rod drive mechanism housing; A control rod is connected to the lower end, and a vertically movable index tube provided with a drive piston at a lower end; a piston tube accommodated in the index tube; and a piston tube disposed above the piston tube, which rises rapidly during a scrum operation. A buffer mechanism for decelerating / stopping the drive piston, a positioning mechanism for engaging a collet finger with a latch groove provided on an outer peripheral portion of the index tube to lock the index tube at a desired height position, Drive water flows into the lower part of the drive piston, An insertion port for raising the index tube, wherein the drive piston is lifted during a scram operation and reaches an over-insertion position where the drive piston is decelerated and stopped by the buffer mechanism. A control rod drive device comprising: a drive water release flow passage that allows the drive water flowing downward to flow into a nuclear reactor. 2. The control rod drive device according to claim 1, wherein the drive piston is raised during a scrum operation, and when the drive piston reaches an over-insertion position where the drive piston is decelerated and stopped, a lateral direction of the drive piston is obtained. A control water release groove provided vertically above the inner peripheral wall of the cylinder tube so as to form a drive water release flow path extending through the cylinder tube and above the cylinder tube. Drive. 3. The control rod driving device according to claim 1, wherein said drive piston is raised during a scram operation, and said cylinder tube and said outer tube are moved when reaching an excessive insertion position where said drive piston is decelerated and stopped by said buffer mechanism. A control rod drive device, wherein a drive water release port is provided in the cylinder tube and the outer tube so that a drive water release flow path passing through the tube is formed.