JP6236380B2 - Control rod drive mechanism - Google Patents

Description

  The present invention relates to a control rod drive mechanism for a boiling water reactor, and more particularly to a hydraulic drive control rod drive mechanism.

  The control rod drive mechanism of the boiling water reactor includes a hydraulic drive type (see, for example, Patent Document 1) and an electric drive type.

  The hydraulic drive type control rod drive mechanism includes a cylinder tube (outer tube), an index tube disposed on the inner peripheral side of the cylinder tube, and a piston tube disposed on the inner peripheral side of the index tube. .

  A control rod is connected to the upper end of the index tube, and a drive piston is formed at the lower end of the index tube. When pressurized water is supplied from the insertion pressurized water supply hole to the lower surface side of the drive piston, the index tube rises and the control rod rises. Further, when pressurized water is supplied from the pressurized pressurized water supply hole to the upper surface side of the drive piston through the inside and outside of the piston tube, the index tube descends and the control rod descends.

  Furthermore, the hydraulically driven control rod drive mechanism is provided on the upper end side of the cylinder tube and is movable in the vertical direction, a collet finger provided on the upper side of the collet piston, and a downward attachment to the collet piston. A collet spring for applying a force and a guide cap are provided.

  The index tube has a plurality of notches that are spaced apart in the length direction. Each notch has a tapered shape on the lower side and a step shape on the upper side. Then, the collet finger and the notch of the index tube engage with each other to regulate the descending of the index tube. That is, the control rod is held at a desired height position.

  In addition, when pressurized water is supplied to the lower surface side of the collet piston via the pressurized water supply passage communicated with the extraction pressurized water supply hole, the collet piston rises against the urging force of the collet spring, and the collet finger To rise. Along with this, the guide cap opens the collet finger so that the notch of the collet finger and the index tube cannot be engaged. Therefore, the lowering of the index tube is not restricted, and the control rod can be pulled out.

Japanese Patent Laid-Open No. 4-50694 (see FIGS. 4 to 9)

  By the way, there is a possibility that foreign matter such as clad that could not be collected by the filter exists in the control rod drive mechanism, and the sealing performance of the collet piston is deteriorated. And the driving force (in other words, differential pressure) which acts on a collet piston falls, and malfunction of a collet piston may arise. For this reason, the notch of the collet finger and the index tube may not be in an unengageable state, and the control rod may not be pulled out. As one of the countermeasures, there is a method of increasing the supply water pressure, but it is desirable that the malfunction of the collet piston can be reduced without increasing the supply water pressure.

  An object of the present invention is to provide a control rod drive mechanism that can reduce the malfunction of the collet piston.

  In order to achieve the above object, the present invention provides a cylinder tube, an index tube disposed on the inner peripheral side of the cylinder tube, connected to a control rod and movable in the vertical direction, and an upper end of the cylinder tube. A collet piston provided on the side and movable in the vertical direction; a collet finger provided on the upper side of the collet piston, and engageable with a notch of the index tube to restrict the lowering of the index tube; A collet spring that applies a downward biasing force to the collet piston, and when the collet piston rises against the biasing force of the collet spring, the notch of the collet finger and the index tube cannot be engaged. Guide key for expanding the collet fingers so that And a backup piston that is provided on the upper end side of the cylinder tube and is movable in the vertical direction separately from the collet piston, and a downward attachment to the backup piston. And a backup spring for applying a force, and the backup piston is configured to assist the raising of the collet piston when the backup piston moves up against the biasing force of the backup spring.

  In the present invention, the operation failure of the collet piston can be reduced by providing a backup spring for assisting the operation of the collet piston. That is, even if the sealing performance of the collet piston deteriorates due to foreign matter or the like and the driving force (in other words, differential pressure) acting on the collet piston decreases, Since the acting driving force (in other words, differential pressure) does not decrease, the backup piston can be operated, and the collet piston can be operated with the assistance of the backup piston.

  According to the present invention, malfunction of the collet piston can be reduced.

It is a longitudinal section showing the whole control rod drive mechanism structure in one embodiment of the present invention. It is a partial expanded longitudinal cross-sectional view showing the principal part structure of the control rod drive mechanism in one Embodiment of this invention. It is a longitudinal cross-sectional view showing the structure of the spacer in one Embodiment of this invention. FIG. 4 is a transverse sectional view taken along section IV-IV in FIG. 3. It is a partial expanded longitudinal cross-sectional view for demonstrating extraction operation | movement when the sealing performance of the collet piston in one Embodiment of this invention deteriorates. It is a partial expanded longitudinal cross-sectional view for demonstrating extraction operation | movement when the sealing performance of the collet piston in one Embodiment of this invention deteriorates. It is a partial expanded longitudinal cross-sectional view for demonstrating extraction operation | movement when the sealing performance of the collet piston in one Embodiment of this invention deteriorates. It is a partial expanded longitudinal cross-sectional view for demonstrating extraction operation | movement when the sealing performance of the collet piston in one Embodiment of this invention deteriorates.

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

  FIG. 1 is a longitudinal sectional view showing the overall structure of the control rod drive mechanism in the present embodiment. FIG. 2 is a partially enlarged longitudinal sectional view showing the main structure of the control rod drive mechanism in the present embodiment. FIG. 3 is a longitudinal sectional view showing the structure of the spacer in the present embodiment, and FIG. 4 is a transverse sectional view taken along section IV-IV in FIG.

  The control rod drive mechanism includes a housing 2 provided integrally with the bottom 1 of the reactor pressure vessel, a block 3 connected to the lower side of the housing 2, and an upper side of the block 3. The cylinder tube 4 accommodated in the cylinder tube 4, the index tube 5 disposed on the inner peripheral side of the cylinder tube 4, and the piston tube 6 disposed on the inner peripheral side of the index tube 5 are provided.

  The block 3 is formed with an insertion pressurized water supply hole 7 and an extraction pressurized water supply hole 8, and pressurized water from a water pressure control unit (not shown) is inserted into the insertion pressurized water supply hole 7 and the extraction pressurized water supply hole 8. One of them is selectively supplied. The cylinder tube 4 has a double cylindrical structure including, for example, an outer cylinder 9 and an inner cylinder 10, and a pressurized water supply passage 11 is formed between the outer cylinder 9 and the inner cylinder 10 (and an outer cylinder portion of a spacer described later). Yes. The pressurized water supply passage 11 communicates with the pressurized pressurized water supply hole 8.

  Although not shown in detail, the water pressure control unit includes a pump for pressurizing water, a flow rate adjusting valve for adjusting the flow rate of pressurized water from the pump, a pressurized water supply hole 7 for inserting pressurized water from the flow rate adjusting valve, and a pull-out port. Two supply direction selection valves for supplying one of the pressurized water supply holes 8 and two discharges for discharging water from the other of the insertion pressurized water supply hole 7 and the extraction pressurized water supply hole 8 A direction selection valve is provided.

  A control rod 12 is connected to the upper end of the index tube 5, and a drive piston 13 is formed at the lower end of the index tube 5. And when pressurized water is supplied to the lower surface side of the drive piston 13 from the pressurized water supply hole 7 for insertion, the index tube 5 rises and the control rod 12 rises. Further, when pressurized water is supplied to the upper surface side of the drive piston 13 through the inside and outside of the piston tube 6 from the extraction pressurized water supply hole 8, the index tube 5 is lowered and the control rod 12 is lowered.

  A spacer 14 is provided on the upper end side of the cylinder tube 4, and a guide cap 16 is provided on the upper side of the spacer 14 via a collet retainer tube 15. A lower portion of the guide cap 16 is formed in a tapered shape.

  The spacer 14 includes an outer cylinder part 17 connected to the outer cylinder 9 of the cylinder tube 4, an inner cylinder part 18 positioned on the inner peripheral side of the outer cylinder part 17, an inner peripheral surface and an inner cylinder of the outer cylinder part 17. It is comprised with the substantially annular piston seating part 19 connected to the lower surface of the part 18. As shown in FIG. A collet cylinder 20 is formed between the inner cylinder 10 of the cylinder tube 4, the inner cylinder portion 18 of the spacer 14, and the piston seating portion 19, and the inner cylinder portion 18, the outer cylinder portion 17, and the piston seating portion 19 of the spacer 14. A backup cylinder 21 is formed between the two. For example, three semicircular cutouts 22 are formed in the piston seating portion 19, and the collet cylinder 20 and the pressurized water supply passage 11 are communicated with each other through the cutouts 22. Further, for example, eight circular holes 23 are formed in the piston seating portion 19, and the backup cylinder 21 and the pressurized water supply path 11 are communicated with each other through these holes 23.

  The lower part of the collet piston 24 is slidably accommodated in the collet cylinder 20, and the lower part of the backup piston 25 is slidably accommodated in the backup cylinder 21. That is, the collet piston 24 and the backup piston 25 are provided so as to be movable in the vertical direction. A collet spring 27 is provided between the collet retainer tube 15 and the plate portion 26 of the collet piston 24, and this collet spring 27 applies a downward biasing force F1 to the collet piston 24. A backup spring 28 is provided between the collet piston 24 and the backup piston 25, and this backup spring 28 applies a downward biasing force F2 (where F2 <F1) to the backup piston 25. A collet finger 29 is provided on the upper side of the collet piston 24.

  The index tube 5 has a plurality of notches (only four notches 30A, 30B, 30C, and 30D are shown for convenience in FIG. 2) formed apart in the length direction. Each notch has a tapered shape on the lower side and a step shape on the upper side. Then, the collet finger 29 and the notch of the index tube 5 are engaged to regulate the lowering of the index tube 5. That is, the control rod 12 is held at a desired height position.

  When pressurized water is supplied to the lower surface side of the collet piston 24 and the lower surface side of the backup piston 25 via the pressurized water supply passage 11, the backup piston 25 normally rises against the urging force of the backup spring 28. The collet piston 24 rises against the urging force of the collet spring 27. At this time, the backup piston 25 abuts on the plate portion 26 of the collet piston 24 to assist the raising of the collet piston 24.

  When the collet finger 29 rises together with the collet piston 24, the guide cap 16 spreads the collet finger 29 outward, so that the collet finger 29 and the notch of the index tube 5 cannot be engaged. Therefore, the lowering of the index tube 5 is not regulated, and the control rod 12 can be pulled out.

  In the present embodiment configured as described above, the operation failure of the collet piston 24 can be reduced by providing the backup piston 25 that assists the operation of the collet piston 24. Specifically, the pulling operation in the case where the sealing performance of the backup piston 25 is not deteriorated although the sealing performance of the collet piston 24 is deteriorated due to foreign matter or the like will be described with reference to FIGS.

  Before starting the operation, for example, as shown in FIG. 5, the collet finger 29 and the notch 30B of the index tube 5 are engaged, and the control rod 12 is held at a predetermined height position. First, as shown in FIG. 6, pressurized water is supplied from the insertion pressurized water supply hole 7 to the lower surface side of the drive piston 13, and the index tube 5 is slightly raised. Thereby, the engagement state of the collet finger 29 and the notch 30B of the index tube 5 is released.

  Then, pressurized water is supplied from the pressurized pressurized water supply hole 8 to the upper surface side of the drive piston 13 through the inside and outside of the piston tube 6, and pressurized water is supplied to the lower surface side of the collet piston 24 and the lower surface side of the backup piston 25 via the pressurized water supply path 11. Supply. At this time, although the sealing performance of the collet piston 24 is deteriorated and the driving force (in other words, differential pressure) acting on the collet piston 24 is reduced, the sealing performance of the backup piston 25 is not deteriorated. The driving force (in other words, differential pressure) acting on the piston 25 is not reduced. Therefore, although the collet piston 24 does not operate alone, the backup piston 25 operates. That is, as shown in FIG. 7, the backup piston 25 rises and the backup piston 25 comes into contact with the plate portion 26 of the collet piston 24.

  Thereafter, as shown in FIG. 8, the backup piston 25 and the collet piston 24 rise together, and the collet finger 29 rises. Along with this, the guide cap 16 expands the collet finger 29 so that the collet finger 29 and the notch of the index tube 5 cannot be engaged. Note that the index tube 5 starts to descend almost simultaneously with the start of the upward movement of the backup piston 25 described above.

Then, after the index tube 5 is lowered, the supply of pressurized water is stopped. Thereby, the collet piston 24 and the backup piston 25 are lowered by the collet spring 27 and the backup spring 28, and the collet finger 29 is lowered. Further, the index tube 5 is lowered by its own weight, and the notch of the index tube 5 and the collet finger 29 are engaged. Thereby, the pulling-out operation of the control rod 12 is completed.

  As described above, even if the sealing performance of the collet piston 24 deteriorates due to foreign matter or the like, the backup piston 25 can be operated if the sealing performance of the backup piston 25 does not deteriorate. The piston 24 can be operated. Accordingly, the collet fingers 29 and the notches of the index tube 5 cannot be engaged, and the control rod 12 can be pulled out.

  In addition, although the sealing performance of the backup piston 25 deteriorates due to foreign matter or the like, the collet piston 24 can be operated even when the sealing performance of the collet piston 24 is not deteriorated. In this embodiment, the sum of the cross-sectional area of the lower surface of the collet piston 24 and the cross-sectional area of the lower surface of the backup piston 25 is made larger than the cross-sectional area of the lower surface of the collet piston 24 when the collet piston 24 is provided alone. ing. Therefore, if the supply water pressure is the same, the driving force acting on the collet piston 24 is increased. Therefore, the malfunction of the collet piston 24 can be reduced also from such a viewpoint.

4 Cylinder tube 5 Index tube
11 Pressurized water supply path 12 Control rod 16 Guide cap 20 Collet cylinder 21 Backup cylinder 24 Collet piston 25 Backup piston 27 Collet spring 28 Backup spring 29 Collet finger 30A, 30B, 30C, 30D Notch

Claims (3)

A cylinder tube;
An index tube that is arranged on the inner peripheral side of the cylinder tube, is connected to the control rod, and is movable in the vertical direction;
A collet piston provided on the upper end side of the cylinder tube and movable in the vertical direction;
A collet finger that is provided on the upper side of the collet piston and engages with a notch of the index tube to restrict the lowering of the index tube;
A collet spring that applies a downward biasing force to the collet piston;
A guide cap for expanding the collet finger so that the collet finger and the notch of the index tube cannot be engaged when the collet piston rises against the urging force of the collet spring; In the control rod drive mechanism provided,
Separately from the collet piston, a backup piston provided on the upper end side of the cylinder tube and movable in the vertical direction;
A backup spring for applying a downward biasing force to the backup piston,
The control rod drive mechanism according to claim 1, wherein the backup piston is configured to assist the raising of the collet piston when it rises against the urging force of the backup spring. The control rod drive mechanism according to claim 1,
A collet cylinder provided on the upper end side of the cylinder tube and slidably storing a lower part of the collet piston;
A backup cylinder that is provided at the upper end side of the cylinder tube and on the outer peripheral side of the collet cylinder, and slidably houses a lower portion of the backup piston;
A control rod drive mechanism comprising: a pressurized water supply passage for supplying pressurized water to the collet cylinder and the backup cylinder. The control rod drive mechanism according to claim 1,
The control rod drive mechanism, wherein the backup spring is provided between the collet piston and the backup piston, and the biasing force thereof is smaller than the biasing force of the collet spring.

Images