JPH02242196A - Inner filter attachment structure of control rod drive mechanism - Google Patents

Abstract

PURPOSE:To make an attaching work of an inner filter more easier by forming a protrusively engaging part at a stopper piston and a chamferred part at a base end part of the protrusively engaging part, and also by forming an engaging hole which engages loosely the protrusively engaging part, at a lower part of the inner filter. CONSTITUTION:A protrusively engaging part 25 of a stop piston 17 can be inserted only into an opening 46 formed on a side surface of a lower most member 41 of an inner filter 40 and by an attaching/detaching groove 42 and an insertion groove 44. When attaching the inner filter 40, an attaching work can be completed only by fitting the attaching/detaching groove 42 to the chamferred part 27 of the stop piston 17, by fitting the insertion groove 44 to the chamferred part 25 of the stop pin 17, by fitting the insertion groove 44 to the protrusively engaging part 25 of the stop piston 17 and by inserting to a predetermined direction A. After completion of the attaching work, an engaging groove 43 of the inner filter 40 and the chamferred part 27 of the stop piston 17 engages and fits one another and therewith the inner filter 40 becomes unfailingly to be in a locked condition against the stop piston 17.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an inner filter mounting structure for a control rod drive am (hereinafter abbreviated as CRD) in a boiling water nuclear reactor.

(Prior Art) A conventional CRD of a boiling water nuclear reactor and a mounting structure of an inner filter in an index tube fixed to the CRD are shown in FIGS. 5 to 12. That is, reference numeral 1 in FIG. 5 indicates a part of the lower mirror part of the reactor pressure vessel, and the CRD housing 2 is installed passing through the lower mirror part 1. A CRD 3 is housed within this CRD housing 2. This CRD 3 has a hollow index tube 4, and a coupling spud 5 is attached to the upper end of this index tube 4.

Further, a control rod guide tube 6 is connected to the upper end of the CRD housing 2, and υJt[
The I rod 7 is accommodated. A socket 8 is provided at the lower end of the control rod 7. Coupling spud 5 provided at the upper end of index tube 4 of the above CRD 3
are engaged with the sockets 8 of the control rods 7, and as the index tube 4 is driven up and down by water pressure, the control rods 7 move within the control rod guide tubes 6 and are inserted into or withdrawn from the reactor core. is configured to be done.

The connection structure between the control rod 7 and the index tube 4 is constructed as shown in FIGS. 6 and 7. That is, the socket 8 has a cylindrical shape, and an engaging portion 10 having an enlarged inner diameter is formed on its inner surface. Further, the coupling spud 5 has a cylindrical shape, and an engaging portion 11 with an enlarged outer diameter is formed at the upper end thereof, and a plurality of cuts 12 are formed in the axial direction as shown in FIG. , is configured to be able to elastically contract and expand the diameter. Further, a lock plug 13 is provided at the center of the socket 8. The locking plug 13 has an outer diameter such that it fits into the inner surface of the coupling spud 5 when the coupling spud 5 is expanded, and is biased downwardly by springs 14 and 15.

When this coupling spud 5 is to be engaged with the socket 8 of the control rod 7, the index tube 4 is raised. Then, the upper end of coupling spud 5 is a socket!・The diameter is reduced when it hits the inner peripheral edge of the lower end of lock plug 1.
3 and enters into this socket 8. The engaging part 11 of the coupling spud 5 is the engaging part 1 of the socket 8.
0, the diameter of the coupling spud 5 expands due to elastic force, and the engagement portion 1 of the coupling spud 5 expands.
1 engages with the engaging portion 10 of the socket 8, and the locking plug 13 is fitted into the coupling spud 5 by the elastic force of the spring 14, 15, making the coupling spud 5 unable to contract in diameter and completely Engagement is made.

Further, an uncoupling rod 16 is provided at the center of the coupling spud 5 so as to be slidable up and down.

Furthermore, a stopper piston 17 is slidably provided within the index tube 4. To disengage the coupling spud 5 from the socket 8 of the control rod 7, push up the stop piston 17, push up the uncoupling rod 16, and use the uncoupling rod 16 to spring the lock plug 13. The lock plug 13 is lifted up against the biasing horns 14 and 15, and the lock plug 13 is pulled out from inside the coupling spud 5. Thereafter, the coupling spud 5 is removed from the socket 8 by lowering the index tube 4.

By the way, since such a CRD 3 is installed at the bottom of the reactor pressure vessel, foreign matter such as crud in the reactor water tends to accumulate, and this foreign matter can penetrate into the cut 1 of the coupling spud 5.
2 and into the index tube 4 through the communication hole 18 formed in the coupling spud 5, and there is a risk of damaging the seal ring 19 of the stop piston 17.

For this reason, an inner filter 20 is provided at the upper end of the stop piston 17. This inner filter 2
0 is configured to trap foreign matter that has entered the index tube 4 and prevent damage to the seal ring 19 in the stop piston 17.

The inner filter 20 may be damaged by the stop piston 17 due to improper attachment to the stop piston 17 or foreign matter getting caught in the stop piston 17.
The stop piston 17 is attached with a certain amount of play so that the movement of the stop piston 17 is not restricted. The conventional mounting structure of this inner filter 20 will be explained in detail using FIGS. 8 to 12.

As shown in FIG. 8, the inner filter 20 includes a cylindrical filter body 21, an annular upper end member 22 attached to the upper end of the filter body 21, and a lower end of the filter body 21 that is opened and attached. and a lower end member 23.

A seal ring 24 is provided on the outer periphery of the upper end member 22,
Liquid tightness is maintained between the outer circumference of the upper end member 22 and the inner circumference of the index tube 4. Therefore, all foreign matter that has entered the index tube 4 flows into the inner filter 20 and is captured. Further, the outer diameter of the lower end member 23 is smaller than the inner diameter of the index tube 4, and the inner filter 20 has a predetermined play with respect to the index tube 4.

On the other hand, a cylindrical engaging protrusion 25 as shown in FIG. 9 is protruded from the center of the upper end of the stop piston 17. As shown in FIG. A pair of parallel chamfers 27 are formed at the base end of the engaging protrusion 25, and a locking step 28 is formed at the upper end of the chamfer 27. Further, an engagement hole 29 is formed in the lower end member 23 of the inner filter 20,
The engagement protrusion 25 is loosely fitted into the engagement hole 29. Further, a circular spring accommodating portion 3 is provided at the bottom of this engagement hole 29.
0 is formed, and a locking spring 31 is accommodated in this spring accommodating portion 30. This locking spring 31
As shown in Figure 0, it has a C-shape, and locking legs 32 parallel to each other are formed at both ends thereof. These locking legs 3
2 elastically abuts against the chamfered portion 27 of the engagement protrusion 25 to lock the locking step portion 28, thereby preventing the inner filter 20 from being removed (locked state).

In addition, an abutting protrusion 3 is provided at the center of the inner surface of the lower end member 23.
3 is formed, and when the stop piston 17 rises, the upper surface of this contact protrusion 33 becomes an uncoupled ring 1.
6 and pushes up this uncoupling rod, raising the locking plug 13 and releasing the engagement between the coupling spud 5 and the socket 8.

By the way, the inner filter 20 is connected to the stop piston 17.
When attaching the stop piston 17 to the engagement hole 29 of the lower end member 23, the engagement protrusion 25 of the stop piston 17 is inserted into the engagement hole 29 of the lower end member 23 and pressed, and the engagement legs 32 of the engagement spring 31 are expanded and engaged. It engages with the stepped portion 28 . Also, when removing this inner filter 20 from the stop piston 17,
As shown in FIGS. 11 and 12, the inner filter 2
0 by 90' to make the locking leg 32 ride on the circumferential surface of the engagement protrusion 25. In this way, the locking step 28 of the lower end member 32 and the locking leg 32 are disengaged (unlocked state), so the inner filter 20 can be pulled out and removed (FIG. 11 is shown for convenience of explanation). (This shows the case where the stop piston 17 is rotated by 90 degrees.) (Problem to be Solved by the Invention) The inner filter 20 is inserted in the state shown in FIG. 10 at the time of assembly, and is locked if properly installed. 1st
If it is installed in the state shown in Figure 2, it will not be able to be locked (unlocked state).

Therefore, during assembly work, the installed state is always checked manually. That is, when comparing FIG. 10 and FIG. 12, in FIG. 12, the locking spring 32 sandwiches the engagement protrusion 25 through elastic deformation, so the rotational torque of the inner filter 20 is larger than that in FIG. 10. Therefore, it is necessary to manually detect the magnitude of rotational torque to confirm whether or not the device is properly installed.

However, this confirmation work is difficult for workers with little experience, and it is conceivable that the parts may be assembled without being locked. For example, it is conceivable that the rotation starts from the unlocked state shown in FIG. 12 and is turned too much, passing through the state shown in FIG. 10 (locked state), or that it is turned insufficiently. Also,
The assembly is not necessarily in the locked state shown in FIG. 10, nor is the phase shifted by 90° as shown in FIG. 12. In other words, when installed, the inner filter 20 is located between the phase shown in Fig. 10 and the position shown in Fig. 12, and there is no fixed number of rotations to set it in the locked state shown in Fig. 10. It is not.

Therefore, if the CRD 3 operates in the unlocked state, the inner filter 20 may come off.

Further, even if the inner filter 20 is properly attached, if the inner filter 20 should rotate 90' while the CRD 3 is in operation, the inner filter 20 may come off the stop piston 17.

Furthermore, if we talk about the inner filter removal work,
As mentioned earlier, the inner filter 20 can be removed when it is in the unlocked state shown in Figure 12, but there is no way to check this state, and as with the installation work, the work relies on the sensation of the hands. Work efficiency is poor.

This invention was made in consideration of the above circumstances,
It is an object of the present invention to provide an inner filter mounting structure for a control rod drive mechanism that can improve work efficiency by making filter mounting and removal work of an inner filter easy and reliable, and can prevent accidental detachment of the inner filter during operation of a CRT. shall be.

[Structure of the invention]

(Means for Solving the Problems) This invention provides an inner filter and a stopper piston arranged in an index tube of a υ11iO rod drive mechanism, and the inner filter is attached to the inner filter of a control rod drive mechanism attached to the stopper piston. In the filter mounting structure, an engaging protrusion is formed on the stopper piston, a chamfer is formed at the base end of the engaging protrusion, and the engaging protrusion is formed on the lower part of the inner filter. mFI! An engagement hole is formed therein, and an attachment/removal groove and an engagement groove that engage and fit into the chamfered portion are continuously formed at the entrance of the engagement hole. be.

(Function) Therefore, according to the inner filter mounting structure of the control rod drive mechanism according to the present invention, when mounting and removing the inner filter, the mounting and removing groove of the inner filter is engaged with the chamfered portion of the stopper piston, This mounting/dismounting groove serves as a guide during mounting/dismounting. Mounting/dismounting work cannot be performed without engaging the mounting/dismounting groove with the listening part. As a result, by intervening the work of engaging the chamfered part of the stopper piston with the inner filter installation/removal groove, the conventional manual and unreliable confirmation work is no longer necessary, and the inner filter installation/removal work is completed. can be done easily and reliably to improve work efficiency.

Furthermore, when the inner filter is installed on the stopper piston, the retaining groove that is continuous with the inner filter's installation/removal groove engages and fits with the listening part of the stopper piston. This prevents the inner filter from rotating inadvertently during CRT operation.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a sectional view of an inner filter and the like showing a first embodiment of an inner filter mounting structure for a control rod drive mechanism according to the present invention. In this first embodiment, the same parts as those in the conventional example are given the same reference numerals and the explanation will be omitted.

An engagement hole 29 is formed in the lower end member 41 of the inner filter 40, and attachment/removal grooves 42 are formed at the entrances of the two engagement holes.

As shown in FIG. 2, the attachment/detachment groove 42 extends in the radial direction from an arbitrary location on the side circumference of the lower end member 41.

An engagement groove 43 is formed below the engagement hole 29 in the lower end member 41 and is continuous with the attachment/removal groove 42 . The groove widths of these attachment/removal grooves 42 and engagement grooves 43 are
7 distance and road distance are set.

The attachment/removal groove 42 engages with the chamfered portion 27 of the stopper piston 17 when the inner filter 40 is attached to or removed from the stopper piston 17, and functions as a guide. Further, the engagement groove 43 is provided so that the inner filter 40 does not rotate relative to the stopper piston 17 by engaging and fitting into the listening portion 27 when the inner filter 40 is completely installed.

Furthermore, an insertion groove 44 is formed in the lower end member 41 in parallel to the attachment/removal groove 42 . This insertion groove 44 is connected to the engagement hole 29
It has a diameter of , and a groove width of 2, and is provided continuously in the engagement hole 29 . The inner filter 40 is moved to the stopper piston 17.
When attaching or removing, the engagement protrusion 25 passes through the insertion groove 44 and reaches the engagement hole 29.

Since the engagement groove 43 and the insertion groove 44 have different widths, an engagement step 45 is formed at the boundary between them.

This engagement step portion 45 is engaged with the locking step portion 28 of the engagement protrusion 25 to prevent the inner filter 40 and the stopper piston 17 from separating in the vertical direction.

Next, the action will be explained.

The engagement protrusion 25 of the stop piston 17 is connected to the mounting/removal groove 4.
2 and the insertion groove 44 are the lower end member 4 of the inner filter 40.
It can only be inserted through the opening 46 formed in the side surface of 1. When installing the inner filter 40, the installation/removal groove 42
The installation is completed by simply fitting into the chamfered portion 27 of the stop piston 17, fitting the insertion groove 44 into the engaging protrusion 25 of the stop piston 17, and inserting it in a certain direction Δ (FIG. 2). After the installation is completed, the engagement groove 43 of the inner filter 40 and the chamfered portion 27 of the stop piston 17 are locked and fitted together, so the inner filter 40 is attached to the stop piston 1.
7, it will inevitably be in a locked state.

In addition, when removing the inner filter 40, the inner filter 40 is moved in the opposite direction B (FIG. 2) from the direction at the time of insertion.
Inner by pulling out 0.

Remove filter 40 from stop piston 17.

Therefore, even an inexperienced worker can easily attach and detach the inner filter 40 to the stop piston 17, and there is no need to manually check the locked state depending on experience. As a result, the work of attaching and removing the inner filter 40 becomes easy and reliable, and work efficiency can be improved.

During operation of the CRT, the inner filter 40 and the stop piston 1 are moved in the direction in which the inner filter 40 is removed.
A force may act between 7.

Such events include scram and insert operations.

In either case, a force that pulls the inner filter 40 upward relative to the stop piston 17 acts. Among these, the most severe is when a scram occurs, and it is conceivable that a rotating force acts on the inner filter 40 in addition to the pulling force during the scram.

However, when the inner filter 40 is pulled upward, the locking step 45 of the inner filter 40 fits into the locking step 28 of the stop piston 17, as shown in FIG. Further, when a rotating force is applied, the engagement groove 43 of the inner filter 40 is inserted into the stop piston 17.
It fits into the chamfered portion 27 of. As a result, even if a scram or the like occurs during operation of the CRT, accidental rotation and detachment of the inner filter 40 can be prevented.

FIG. 3 is a sectional view of an inner filter, etc., showing a second embodiment of the inner filter mounting structure of the control rod drive mechanism according to the present invention. In this second embodiment, the same parts as those in the conventional example are given the same reference numerals and the explanation will be omitted.

In the lower end member 51 of the inner filter 50 of this second embodiment, an engagement hole 29 and a stopper insertion portion 52 are formed. This stopper insertion portion 52 is provided perpendicularly to the axis of the engagement hole 29. A substantially disk-shaped stopper 53 shown in FIG.
is placed.

This stopper 53 is attached to the lower end member 51 with a screw 54. An engagement groove 55 that engages and fits into the chamfered portion 52 of the stop piston 17 is formed at the tip of the stopper 53 .

When attaching the inner filter 50 to the stop piston 17, the engagement protrusion 25 is loosely fitted into the engagement hole 29 of the inner filter 50, and the stopper 53 is inserted into the stopper insertion portion 52. At this time, the inner filter 50 is rotated to fit the chamfered portion 27 into the engagement groove 55. Therefore, the engagement groove 55 serves as a guide when the inner filter 50 is attached, and functions as an attachment/removal groove. Therefore, in this case as well, by attaching the stopper 53 to the lower end member 51, the locked state of the inner filter 50 can be confirmed, and the attachment and detachment work of the inner filter 50 can be easily and reliably performed, thereby improving the work efficiency.

Furthermore, after the installation of the inner filter 50 is completed, the engagement groove 55 of the stopper 53 is connected to the chamfered portion 27 of the stopper piston 17.
Since the stopper 53 is fitted into the stopper piston 17, rotation of the stopper 53 with respect to the stopper piston 17 can be prevented, and the inner filter can be prevented from accidentally coming off when the CRT is operated.

〔Effect of the invention〕

As described above, according to the inner filter mounting structure for a control rod drive mechanism according to the present invention, an engagement protrusion is formed on the stopper piston, and a chamfer is formed at the base end of the engagement protrusion. At the same time, an engagement hole into which the above-mentioned engagement protrusion is loosely fitted is formed in the lower part of the inner filter, and a mounting/removal groove into which the above-mentioned chamfered part engages and fits is formed at the entrance of the engagement hole. Since the engagement grooves are formed continuously, it is possible to easily and reliably attach and detach the inner filter, improve work efficiency, and prevent the inner filter from accidentally coming off when the CRT is operated.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an inner filter etc. showing a first embodiment of the inner filter mounting structure with a control rod drive structure according to the present invention, FIG. 2 is a cross-sectional view taken along the If-X line in FIG. Fig. 3 is a sectional view showing an inner filter etc. to which the second embodiment of the present invention is applied, Fig. 4 is a sectional view taken along line IV-IV in Fig. 3, and Fig. 5 is a conventional anti-crime rod! 6 is a sectional view of the main part of FIG. 5, FIG. 7 is a sectional view taken along the line ■-■ of FIG. 6, and FIG. 8 is a sectional view of the inner filter, etc. of FIG. 6. An enlarged sectional view, FIG. 9 is a partial perspective view of the stop piston in FIG. 8, and FIG. 10 is a cross-sectional view of the stop piston in FIG.
11 is a sectional view taken along the X-ray, FIG. 11 is a sectional view showing the unlocked state of the inner filter, and FIG. 12 is a sectional view corresponding to FIG.
FIG. 2 is a cross-sectional view taken along the cutting-scoring line in FIG. 1; 3...! 11 Obokoke vJ mechanism (CRT), 4...
Index tube, 17... Stop screws 1 to 25... Engaging protrusion, 27... Chamfered portion, 29...
Engagement hole, 40... Inner filter, 42... Attachment/removal groove, 43... Engagement groove, 44... Insertion groove. Applicant's agent Hisashi Hatano-a1 Figure 159''l No. i. Figure 12 Procedural amendment (voluntary) April 25, 1989

Claims (1)

[Claims] In an inner filter mounting structure for a control rod drive mechanism in which an inner filter and a stopper piston are disposed in an index tube of a control rod drive mechanism, and the inner filter is attached to the stopper piston, the stopper piston has an engaging protrusion. A chamfer is formed at the base end of the engagement protrusion, and an engagement hole into which the engagement protrusion is loosely fitted is formed in the lower part of the inner filter. An inner filter mounting structure for a control rod drive mechanism, characterized in that an attachment/removal groove and an engagement groove that engage and fit into the chamfered portion are continuously formed in the inlet portion.