JPH09325197A - Control rod clamping mechanism for nuclear reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deformation or damage of a control rod or control rod driver when a coupling spud is rotated in the state that the spud is incompletely inserted into a coupling socket. SOLUTION: A coupling socket 7A provided at the lower end of a control rod has four socket protrusions 10 circumferentially provided at an equal interval on the lower inner periphery of its insertion hole 72. A coupling spud 8A is insertional into and drawable from the hole 72 of the socket 7A, and has four spud protrusions 20 provided corresponding to the protrusions 10. The protrusion 20 is formed with an oblique surface 22 inclined down in the rotating direction R in the entire surface of the spud 8A in the direction R side at the time of clamping. The protrusion 10 is formed with an oblique surface 12 inclined in the same direction as the surface 22 of the protrusion 20 in the entire surface at the opposite side to the direction R side of the spud 8A at the time of clamping.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called bayonet coupling for fastening a control rod and a control rod driving device for vertically driving the control rod in a boiling water reactor (BWR). Type control rod fastening mechanism.

[0002]

2. Description of the Related Art FIG. 10 shows a main part of a boiling water reactor (BWR) to which a conventional control rod fastening mechanism is applied. In FIG. 10, a control rod 1 including a neutron absorber,
A control rod drive device 2 located below the control rod 1 is shown. Further, in FIG. 10, reference numeral 3 indicates a reactor pressure vessel (RPV), reference numeral 4 indicates a core support plate, reference numeral 5
The fuel assembly is shown by. Since the control rod 1 has a nuclear and mechanical life, it is assumed that the control rod 1 will be replaced several times during the operation period of the nuclear reactor. To be done.

For this reason, the control rod 1 and the control rod drive device 2 shown in FIG. 10 are detachably fastened by a so-called bayonet coupling type control rod fastening mechanism 6. The control rod fastening mechanism 6 is a combination of a coupling socket 7 provided at the lower end of the control rod 1 and a coupling spud 8 provided at the upper portion of the control rod driving device 2.

As shown in FIG. 11, the coupling socket 7 is a main body 70 provided at the lower end of the control rod 1.
And an insertion hole 72 opening at the bottom of the main body 70,
On the inner peripheral surface of the lower portion of the insertion hole 72, there are four socket convex portions 100 provided at equal intervals in the circumferential direction.
On the other hand, the coupling spud 8 can be inserted into and removed from the insertion hole 72 of the coupling socket 7, and four spuds provided on the outer peripheral surface of the upper end portion corresponding to the socket protrusion 100. It has a convex portion 110. The socket protrusion 100 has an upper surface 104 that is substantially horizontal with respect to the circumferential direction of the insertion hole 72.
10 has a bottom surface 114 corresponding to the top surface 104 of the socket protrusion 100.

The coupling spud 8 has a substantially cylindrical shape as a whole, and four spuds 82 extending downward from the upper end of the coupling spud 8 allow the spud projections 1 to be formed.
It is divided into four leaf spring bodies 84 corresponding to 10.
Inside the coupling spud 8, a substantially cylindrical compression rod 86 extending coaxially with the coupling spud 8 is provided.

Next, referring to FIGS. 12 and 13, the control rod 1
The operation of fastening the control rod drive device 2 with the control rod drive device 2 will be described. First, as shown in FIGS. 12 (a) and 12 (b), the upper end of the coupling spud 8 is replaced with the spud convex portion 110.
Are inserted into the insertion holes 72 of the coupling socket 7 so that the holes pass between the socket protrusions 100. Then, after the bottom surface 114 of the spud convex portion 110 reaches above the upper surface 104 of the socket convex portion 100 (see the chain double-dashed line in FIG. 13A), as shown in FIGS. By rotating the coupling spud 8 in the direction of arrow R at an angle of about 45 degrees around its axis, the spud convex portion 110 is formed.
The bottom surface 114 of the socket is opposed to the top surface 104 of the socket protrusion 100 (see the solid line in FIG. 13A).

Here, in the socket convex portion 100, a surface opposite to the rotation direction R side of the coupling spud 8 at the time of fastening is a vertical surface 102, and the spud convex portion 11 is formed.
In 0, the surface on the rotation direction R side is a vertical surface 112 (see FIG. 13).

[0008]

The conventional control rod fastening mechanism described above has the following problems. That is, as shown in FIG. 13B, the spud protrusion 110
When the coupling spud 8 is rotated in an incompletely inserted state such that the bottom surface 114 of the socket does not reach the upper surface 104 of the socket convex portion 100, the vertical surface 102 of the socket convex portion 100 becomes a vertical surface of the spud convex portion 110. The vertical surfaces 102, 112 directly receive the rotational force of the coupling spud 8, and the vertical surface 102, 112 abuts on it.

Therefore, the rotational force of the coupling spud 8 acts as a torsional stress on the control rod 1 and the control rod drive device 2 via the coupling socket 7 and the coupling spud 8, and the control rod 1 and The control rod drive device 2 may be deformed or damaged. In particular, the leaf spring body 84 of the coupling spud 8 is easily deformed by such twisting.

The present invention has been made in consideration of such a point, and even when the coupling spud is rotated with respect to the coupling socket in an incompletely inserted state, the control rod and the control rod drive device are provided. It is an object of the present invention to provide a control rod fastening mechanism for a nuclear reactor that can prevent deformation and damage of the reactor.

[0011]

A first means is a control rod fastening mechanism for fastening a control rod of a nuclear reactor and a control rod driving device located below the control rod, wherein A cup having a main body provided at the lower end, an insertion hole opening at the bottom of the main body, and a plurality of socket protrusions provided at intervals in the circumferential direction on the lower inner peripheral surface of the insertion hole. A ring socket and an upper portion of the control rod driving device are provided so that the ring socket can be inserted into and removed from the insertion hole of the coupling socket, and the outer peripheral surface of the upper end portion of the socket corresponds to the plurality of socket protrusions. A coupling spud having a plurality of spud protrusions provided, the socket protrusion has an upper surface substantially horizontal to the circumferential direction of the insertion hole, the spud protrusion, the socket protrusion Bottom corresponding to the top of the part When the control rod and the control rod drive device are fastened, the upper end of the coupling spud is inserted into the coupling socket such that the spud protrusion passes between the socket protrusions. The bottom surface of the spud convex portion and the bottom surface of the spud convex portion are rotated by rotating the coupling spud around its axis after the bottom surface of the spud convex portion reaches above the upper surface of the socket convex portion. The upper surface of the socket projection is opposed to the spud projection, and the entire surface of the spud projection on the rotation direction side of the coupling spud at the time of fastening is a slanted surface inclined with respect to the rotation direction. , The socket protrusion is
It is characterized in that the entire surface of the coupling spud on the side opposite to the rotation direction side at the time of fastening is a slope inclined in the same direction as the slope of the spud convex portion.

According to the first means, when the control rod and the control rod driving device are fastened together, the coupling spud is incompletely inserted when the bottom surface of the spud projection does not reach the height of the top surface of the socket projection. When is rotated, the sloped surface of the spud convex portion abuts the sloped surface of the socket convex portion, and the spud convex portion slides on the sloped surface of the socket convex portion. By this, at the contact surface between the spud convex portion and the socket convex portion, a part of the rotational force of the coupling spud is released in the direction of each slope, and the stress acting on the coupling socket and the coupling spud, and these Through this, the stress acting on the control rod and the control rod drive device can be reduced.

The second means is the same as the first means,
The sloped surface of the spud convex portion is characterized by being inclined upward with respect to the rotation direction of the coupling spud at the time of fastening.

According to the second means, the slope of the spud protrusion is inclined upward with respect to the rotating direction of the coupling spud at the time of fastening, and the slope of the socket protrusion is in the same direction as the slope of the spud protrusion. Since the bottom surface of the spud protrusion does not reach the height of the top surface of the socket protrusion when the coupling spud is rotated, the slope of the spud protrusion becomes the slope of the socket protrusion. The abutment is brought into contact with the spud, and the spud is slid upward on the inclined surface of the socket, in the direction of rotation of the coupling spud. By this,
As the coupling spud rotates, raise the coupling spud in the insertion hole of the coupling socket until the bottom surface of the spud protrusion reaches the top surface of the socket protrusion, and then the bottom surface of the spud protrusion and the socket. The upper surface of the convex portion can be opposed.

A third means is characterized in that, in the above-mentioned first or second means, a concave portion for receiving the bottom surface side of the spud convex portion is formed on the upper surface side of the socket convex portion.

According to the third means, in the first or second means, the control rod driving device lowers the coupling spud while the control rod and the control rod driving device are fastened. When pulling out, the bottom side of the spud protrusion is received in the recess on the top side of the opposing socket protrusion, preventing the gap between the bottom of the spud protrusion and the top side of the socket protrusion, and ensuring stability. The control rod can be pulled out.

In a fourth means, in any one of the first to third means, the coupling spud has a substantially cylindrical shape as a whole, and a plurality of slits extending downward from an upper end portion of the coupling spud project each spud. The slits are divided into a plurality of leaf spring bodies corresponding to the portions, and the plurality of slits are characterized in that the width at the upper portion thereof is narrower than the width at the other portions.

According to the fourth means, in any one of the first to third means, the coupling spud is in an incompletely inserted state in which the bottom surface of the spud convex portion does not reach the height of the upper surface of the socket convex portion. When the is rotated, the force acting on the spud convex portion tends to deform the leaf spring body in the circumferential direction of the coupling spud, but the slits of the coupling spud have different widths at the upper part. Since it is narrower than the width at the part of, the upper part of the slit is closed when the leaf spring body is slightly deformed, the slit side surfaces of the upper part of the leaf spring body come into contact with each other, and the leaf spring bodies are circumferentially separated from each other. Support each other. As a result, excessive deformation of the leaf spring body in the circumferential direction of the coupling spud can be prevented.

A fifth means is any one of the first to third means, wherein the coupling spud has a substantially cylindrical shape as a whole, and a plurality of slits extending downward from the upper end portion of the coupling spud make each spud convex. It is divided into a plurality of leaf springs corresponding to the section, inside the coupling spud, a substantially cylindrical compression rod extending coaxially with the coupling spud is provided, and on the side surface of the compression rod, the coupling spud is formed. A rib-shaped stopper extending along each slit of the pad is provided.

According to the fifth means, in any one of the first to third means, the coupling spud is in an incompletely inserted state in which the bottom surface of the spud convex portion does not reach the height of the upper surface of the socket convex portion. When the is rotated, the force acting on the spud convex portion tries to deform the leaf spring body in the circumferential direction of the coupling spud, but along the side surface of the compression rod along each slit of the coupling spud. Since the rib-shaped stopper that extends is provided, when the leaf spring body is slightly deformed, the slit side surface of the leaf spring body contacts the stopper, and the leaf spring body is supported in the circumferential direction by the corresponding stopper. . By this,
Excessive deformation of the leaf spring body in the circumferential direction of the coupling spud can be prevented.

[0021]

Next, an embodiment of the present invention will be described with reference to the drawings. In addition, in the embodiment of the present invention shown in FIGS. 1 to 9, the same components as those of the conventional example shown in FIGS.
Description will be made with reference to FIGS. 10 and 12 as necessary.

First Embodiment FIG. 1 and FIG. 2 are views showing a first embodiment of the present invention. FIG. 1 shows a boiling water reactor (B
In WR), a bayonet coupling type control rod fastening mechanism 6A for fastening the control rod 1 and the control rod drive device 2 located below the control rod 1 is shown. The control rod fastening mechanism 6A includes a coupling socket 7A provided at a lower end portion of the control rod 1 and a rod driving device 2.
Is combined with a coupling spud 8 provided on the upper part of the.

As shown in FIG. 1, the coupling socket 7A includes a main body 70 having a substantially cylindrical shape, and the main body 7
Insertion hole 72 opening at the bottom of 0, and this insertion hole 72
Has four socket convex portions 10 provided at equal intervals in the circumferential direction on the lower inner peripheral surface of the. On the other hand, the coupling spud 8A can be inserted into and removed from the insertion hole 72 of the coupling socket 7A, and four spuds provided on the outer peripheral surface of the upper end portion of the coupling spud 8A corresponding to the socket protrusions 10. It has a convex portion 20.

As shown in FIGS. 1 and 2, the socket protrusion 10 has an upper surface 14 which is substantially horizontal with respect to the circumferential direction of the insertion hole 72, and the spud protrusion 20 is the socket protrusion 1.
It has a bottom surface 24 corresponding to the top surface 14 of zero. Also,
The spud convex portion 20 is the coupling spud 8 at the time of fastening.
The entire surface of A on the side of the rotation direction (see arrow R in FIG. 1) forms an inclined surface 22 that is inclined downward with respect to this rotation direction R. On the other hand, in the socket protrusion 10, the entire surface on the side opposite to the rotation direction R side of the coupling spud 8A at the time of fastening is in the same direction as the slope 22 of the spud protrusion 20 (rotation direction R).
It has a slope 12 that inclines downward.

Further, as shown in FIG. 1, the coupling spud 8A has a substantially cylindrical shape as a whole, and
By the four slits 82 extending downward from the upper end portion, the four leaf spring bodies 84 corresponding to the respective spud convex portions 20 are provided.
It is divided into two parts, which are designed to absorb the impact of scrum. Inside the coupling spud 8A, a substantially cylindrical compression rod 86 extending coaxially with the coupling spud 8A is provided.

Here, when the control rod 1 and the control rod driving device 2 shown in FIG.
As in the case of the conventional example shown in FIG. 2, first, the upper end portion of the coupling spud 8A is replaced by the spud convex portion 20 in the socket convex portion 1.
It is inserted into the insertion hole 72 of the coupling socket 7A so as to pass between 0s. Then, after the bottom surface 24 of the spud convex portion 20 reaches a level higher than the height of the upper surface 14 of the socket convex portion 10, by rotating the coupling spud 8A in the R direction around its axis at an angle of about 45 degrees, The bottom surface 24 of the spud projection 20 and the top surface 1 of the socket projection 10
4 and 4 are opposed to each other.

Next, the operation of this embodiment having such a configuration will be described with reference to FIG. According to the present embodiment, when the control rod 1 and the control rod drive device 2 are fastened together, the bottom surface 24 of the spud convex portion 20 does not reach the height of the upper surface 14 of the socket convex portion 10 (Fig. 2).
When the coupling spud 8A is rotated by the two-dot chain line in (a), the slope 22 of the spud convex portion 20 abuts the slope 12 of the socket convex portion 10 (see the solid line in FIG. 2A), and the socket The slope of the protrusion 10 is 12 and the spud protrusion 20 is
Slides relatively upward on the slope 22 (see FIG. 2B).

As a result, at the contact surfaces 12 and 22 between the spud convex portion 20 and the socket convex portion 10, a part of the rotational force of the coupling spud 8A is applied to the inclined surfaces 12 and 2, respectively.
It is possible to reduce the stress that is released in two directions and that acts on the coupling socket 7A and the coupling spud 8A, and the stress that acts on the control rod 1 and the control rod drive device 2 via these.

In this case, since the socket convex portion 10 is pushed upward, the coupling socket 7A is separated upward from the coupling spud 8A (see FIG. 2).
(See (b)), but the control rod 1 and the control rod drive device 2 are not fastened, but this state is detected by the control rod drive device attaching / detaching machine (not shown) (coupling check).
Then, the fastening work is redone.

Second Embodiment FIGS. 3 and 4 are views showing a second embodiment of the present invention. A control rod fastening mechanism 6B of the present embodiment shown in FIG. 3 includes a coupling socket 7A having the socket protrusion 10 of the control rod fastening mechanism 6A of the first embodiment and a coupling spud 8A having a spud protrusion 20. Instead of
Coupling socket 7B having socket protrusion 30
And a coupling spud 8 having a spud convex portion 40
B is provided, and other configurations are similar to those of the control rod fastening mechanism 6A of the first embodiment shown in FIG.

As shown in FIGS. 3 and 4, the socket convex portion 30 has an upper surface 34 that is substantially horizontal to the circumferential direction of the insertion hole 72, and the spud convex portion 40 is the socket convex portion 3.
It has a bottom surface 44 corresponding to the top surface 34 of zero. Also,
The spud convex portion 40 is the coupling spud 8 at the time of fastening.
The entire surface of B on the side of the turning direction (see arrow R in FIG. 3) forms an inclined surface 42 that is inclined upward with respect to the turning direction R. On the other hand, in the socket convex portion 30, the entire surface on the side opposite to the rotating direction R side of the coupling spud 8B at the time of fastening is in the same direction as the inclined surface 42 of the spud convex portion 40 (rotating direction R).
The slope 32 is inclined upward (to the upper side).

Next, the operation of this embodiment having such a configuration will be described with reference to FIG. According to this embodiment, the slope of the spud convex portion 40 is inclined upward with respect to the rotation direction of the coupling spud 8B at the time of fastening, and the slope of the socket convex portion 30 is in the same direction as the slope of the spud convex portion 40. Since it is inclined, the coupling spud 8B is rotated in an incompletely inserted state in which the bottom surface of the spud convex portion 40 does not reach the height of the upper surface 34 of the socket convex portion 30 (see the chain double-dashed line in FIG. 4A). Then, the sloped surface 42 of the spud convex portion 40 contacts the sloped surface 32 of the socket convex portion 30 (see FIG.
(See the solid line in (a)), the spud protrusion 40 slides upward on the slope 32 of the socket protrusion 30 in the rotational direction R of the coupling spud 8B (see FIG. 4B).

As a result, the coupling spud 8
With the rotation of B, the spud convex portion 40 is raised until the bottom surface 44 thereof reaches the height of the upper surface 34 of the socket convex portion 30 (see FIG. 4B), and then the bottom surface 44 of the spud convex portion 40. And the upper surface 34 of the socket protrusion 30 can be opposed to each other (see FIG. 4C). Therefore, even when the coupling spud 8B is rotated in the incompletely inserted state, the control rod 1 and the control rod drive device 2 can be fastened.

Third Embodiment FIGS. 5 to 7 are views showing a third embodiment of the present invention. A control rod fastening mechanism 6C of the present embodiment shown in FIG. 5 is a coupling socket 7A having the socket protrusion 10 of the control rod fastening mechanism 6A of the second embodiment and a coupling spud 8A having a spud protrusion 20. Instead of
Coupling socket 7C having socket protrusion 50
And a coupling spud 8 having a spud convex portion 60
The control rod fastening mechanism 6A is the same as the control rod fastening mechanism 6A of the first embodiment shown in FIG.

Further, the socket convex portion 50 of the present embodiment shown in FIGS. 5 to 7 is provided with a concave portion 54 on the upper surface side corresponding to the upper surface 34 of the socket convex portion 30 of the second embodiment. Then, unlike the socket protrusion 30 of the second embodiment, the other configurations are the same as those of the socket protrusion 30 of the second embodiment shown in FIGS. 3 and 4. The concave portion 54 of the socket convex portion 50 is formed by being sandwiched by the divergent projections 56 and 57 provided at both ends in the circumferential direction of the insertion hole 72.

Further, the spud convex portion 60 of this embodiment shown in FIGS. 5 to 7 has a shape in which the bottom surface 44 of the spud convex portion 40 of the second embodiment corresponds to the concave portion 54 of the socket convex portion 50. Different from the spud convex portion 40 of the second embodiment in that the bottom surface 64 is changed, other configurations are the same as the spud convex portion 40 of the second embodiment shown in FIGS. 3 and 4.

Next, the operation of this embodiment having such a configuration will be described with reference to FIGS. 6 and 7. According to the present embodiment, the coupling spud 8C in the incompletely inserted state (see the chain double-dashed line in FIG. 6A) in which the bottom surface 64 of the spud protrusion 60 does not reach the height of the protrusion 56 of the socket protrusion 50. When is rotated, the sloped surface 42 of the spud convex portion & 0 comes into contact with the sloped surface 32 of the socket convex portion 50 (see FIG. 6).
(See the solid line in (a)), the spud protrusion 60 slides upward on the slope 32 of the socket protrusion 50 in the rotational direction R of the coupling spud 8C (see FIG. 6B).

As a result, the coupling spud 8
With the rotation of C, the spud projection 60 is raised until the bottom surface 64 thereof reaches the height of the projection 56 of the socket projection 50 (see FIG. 6B), and then the bottom surface of the spud projection 60. 64 and the concave portion 54 on the upper surface side of the socket convex portion 50 can be opposed to each other (see FIG. 6C). For this reason,
Even when the coupling spud 8C is rotated in the incompletely inserted state, the control rod 1 and the control rod drive device 2 can be fastened.

Further, in the state where the bottom surface 64 of the spud convex portion 60 and the concave portion 54 on the upper surface side of the socket convex portion 50 face each other as described above, the control rod driving device 2 lowers the coupling spud 8C (FIG. 7). 7 (a), when the control rod 1 is pulled out, the bottom surface 64 side of the spud convex portion 60 faces the opposite socket convex portion 5 as shown in FIG. 7A.
Since it is received in the concave portion 54 on the upper surface side of 0, the deviation between the bottom surface 64 side of the spud convex portion 60 and the upper surface side of the socket convex portion 50 can be prevented, and stable extraction of the control rod 1 can be performed.

Further, as shown in FIG. 7B, the bottom surface 64 of the spud convex portion 60 and the concave portion 54 on the upper surface side of the socket convex portion 50 are slightly deviated from the rotating direction of the coupling spud 8C. Even when the control rod 1 is pulled out from the state, the bottom surface 64 side of the spud convex portion 60 is guided into the concave portion 54 by the diverging projections 56 and 57, and the above deviation is surely corrected. The control rod 1 can be pulled out.

In the control rod fastening mechanisms 6A to 6C of the first to third embodiments described above, the socket protrusions 10, 30, 50 and the spud protrusions 20, respectively.
It is preferable to apply a surface treatment (for example, a solid lubricating film such as MoS ₂ or graphite) for reducing friction to at least the portions of the inclined surfaces 12 to 42 of 40 and 60. By performing such surface treatment, when the coupling spuds 8A to 8C are rotated in the incompletely inserted state, the frictional force acting between the inclined surfaces 12 to 42 is reduced, whereby the control rod 1 The force acting on the control rod drive device 2 can be reduced, and the fastening operation by the coupling sockets 7A to 7C and the coupling spuds 8A to 8C can be facilitated.

Fourth Embodiment FIG. 8 is a diagram showing a fourth embodiment of the present invention. The control rod fastening mechanism of the present embodiment shown in FIG. 8 is provided with a coupling spud 8D instead of the coupling spud 8A of the control rod fastening mechanism 6A of the first embodiment described above, and other configurations are This is the same as the control rod fastening mechanism 6A of the first embodiment shown in FIG. Further, as shown in FIG. 8, the coupling spud 8D of the present embodiment is divided into four leaf spring bodies 84a corresponding to the respective spud convex portions 20 by the four slits 83 extending downward from the upper end portion. Different from the coupling spud 8A of the first embodiment in that the width of the upper portion 83a of the plurality of slits 83 corresponding to the spud convex portion 20 is narrower than the width of the other portion 83b, other configurations are the same as those in FIG. The coupling spud 8A of the first embodiment shown in FIG.

Next, the operation of this embodiment having such a configuration will be described. According to the present embodiment, when the coupling spud 8D is rotated in the incompletely inserted state in which the bottom surface 24 of the spud convex portion 20 does not reach the height of the upper surface 14 of the socket convex portion 10 (see FIG. 2), Although a force acting on the spud protrusion 20 (a reaction force from the socket protrusion 10 or the like) tends to deform the leaf spring body 84a in the circumferential direction of the coupling spud 8D, the plurality of slits 83 of the coupling spud 8D. Since the width of the upper portion 83a is narrower than the width of the other portion 83b, the upper portion 83a of the slit 83 is closed when the leaf spring body 84a is slightly deformed, and the slit of the leaf spring body 84a on the slit upper portion 83a side. The surfaces come into contact with each other, and the leaf spring bodies 84a support each other in the circumferential direction. By this,
It is possible to prevent excessive deformation of the leaf spring body 84a that exceeds the elastic limit of the coupling spud 8D in the circumferential direction.

Fifth Embodiment FIG. 9 is a diagram showing a fifth embodiment of the present invention. In the control rod fastening mechanism of the present embodiment shown in FIG. 9, a rib-shaped stopper 88 extending along the inside of each slit 82 of the coupling spud 8A is provided on the side surface of the compression rod 86 of the first embodiment. The control rod fastening mechanism 6A differs from the control rod fastening mechanism 6A of the first embodiment in other respects, and other configurations are similar to those of the control rod fastening mechanism 6A of the first embodiment shown in FIG.

Next, the operation of this embodiment having such a configuration will be described. According to this embodiment, when the coupling spud 8A is rotated in the incompletely inserted state in which the bottom surface 24 of the spud convex portion 20 does not reach the height of the upper surface 14 of the socket convex portion 10 (see FIG. 2), Although a force acting on the spud protrusion 20 (a reaction force from the socket protrusion 10 or the like) tends to deform the leaf spring body 84 in the circumferential direction of the coupling spud 8A, the coupling spud is formed on the side surface of the compression rod 86. Since the rib-shaped stopper 88 extending along each slit 82 of the pad 8A is provided, when the leaf spring body 84 is slightly deformed,
The surface of the leaf spring body 84 on the slit 82 side contacts the stopper 88, and each leaf spring body 84 is circumferentially supported by the corresponding stopper 88. As a result, it is possible to prevent excessive deformation of the leaf spring body 84 that exceeds the elastic limit of the coupling spud 8A in the circumferential direction.

In the fourth and fifth embodiments described above, the control rod fastening mechanism 6A of the first embodiment shown in FIG. 1 is described as a basic configuration, but the present invention is not limited to this. It may be based on the structure of the control rod fastening mechanisms 6B and 6C of the second or third embodiment shown in FIG. 3 or 5.

[0047]

According to the first aspect of the present invention, when the control rod and the control rod driving device are fastened together, the bottom surface of the spud convex portion does not reach the height of the upper surface of the socket convex portion and is incompletely inserted. When the coupling spud is rotated, the slant surface of the spud convex portion contacts the slant surface of the socket convex portion, and the spud convex portion slides on the slant surface of the socket convex portion. As a result, at the contact surface between the spud protrusion and the socket protrusion,
Relieving a part of the rotational force of the coupling spud in the direction of the respective slopes to reduce the stress acting on the coupling socket and the coupling spud and the stress acting on the control rod and the control rod drive device via these. You can Therefore, even when the coupling spud is rotated with respect to the coupling socket in an incompletely inserted state, the control rod and the control rod drive device can be prevented from being deformed or damaged.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a main part of a first embodiment of a control rod fastening mechanism for a nuclear reactor according to the present invention.

FIG. 2 is a schematic view showing a relationship between a socket protrusion and a spud protrusion of the control rod fastening mechanism shown in FIG.

FIG. 3 is a partially cutaway perspective view showing a main part of a second embodiment of a control rod fastening mechanism for a nuclear reactor according to the present invention.

FIG. 4 is a schematic diagram showing the relationship between a socket protrusion and a spud protrusion of the control rod fastening mechanism shown in FIG.

FIG. 5 is a partially cutaway perspective view showing an essential part of a third embodiment of a control rod fastening mechanism for a nuclear reactor according to the present invention.

FIG. 6 is a schematic view showing a relationship between a socket convex portion and a spud convex portion when the control rod fastening mechanism shown in FIG. 5 is fastened.

FIG. 7 is a schematic diagram showing a relational action between a socket convex portion and a spud convex portion when the control rod is pulled out of the control rod fastening mechanism shown in FIG.

8A is a plan view showing a coupling spud side of a control rod fastening mechanism for a nuclear reactor according to a fourth embodiment of the present invention, and FIG. 8B is a perspective view of the same.

FIG. 9A is a plan view showing a coupling spud side of a control rod fastening mechanism for a nuclear reactor according to a fifth embodiment of the present invention, and FIG. 9B is a perspective view of the same.

FIG. 10 is a vertical cross-sectional view illustrating a main part of a nuclear reactor to which a conventional control rod fastening mechanism is applied.

FIG. 11 is a partially cutaway perspective view showing an example of a conventional control rod fastening mechanism.

12 is a partially cutaway perspective view showing a fastening operation of the control rod fastening mechanism shown in FIG.

13 (a) is a schematic view showing the relationship between the spud convex portion and the socket convex portion of the control rod fastening mechanism shown in FIG. 11 in a normal fastening state, and FIG. The schematic diagram shown at the time of complete insertion.

[Explanation of symbols]

 1 control rod 2 control rod drive device 6,6A-6C control rod fastening mechanism 7,7A-7C coupling socket 8,8A-8D coupling spud 10,30,50,100 socket convex part 12,32 socket convex part Sloped surface 14, 34, 104 Upper surface of socket convex portion 20, 40, 60, 110 Spud convex portion 22, 42 Sloped surface of spud convex portion 24, 44, 64, 114 Bottom surface of spud convex portion 54 Recessed portion 70 Coupling socket main body 72 Insertion Hole 74 Hole for insertion hole 82,83 Slit 83a Upper part of slit 83b Other part of slit 84,84a Leaf spring body 86 Compression rod 88 Stopper

Claims (5)

[Claims] 1. A control rod fastening mechanism for fastening a control rod of a nuclear reactor and a control rod driving device located below the control rod, comprising a main body provided at a lower end of the control rod, A coupling socket having an insertion hole opening at the bottom of the main body, and a plurality of socket convex portions provided at intervals in the circumferential direction on the lower inner peripheral surface of the insertion hole, and the control rod drive device. It is provided on the upper part and can be inserted into and removed from the insertion hole of the coupling socket, and has a plurality of spud protrusions provided on the outer peripheral surface of the upper end portion corresponding to the plurality of socket protrusions. A coupling spud, wherein the socket protrusion has an upper surface that is substantially horizontal with respect to the circumferential direction of the insertion hole, and the spud protrusion has a bottom surface that corresponds to the upper surface of the socket protrusion. The control rod and the When fastening with a rod driving device, the upper end of the coupling spud is inserted into the insertion hole of the coupling socket such that the spud convex portion passes between the socket convex portions, After the bottom surface of the spud projection reaches above the top surface of the socket projection,
By rotating the coupling spud about its axis, the bottom surface of the spud protrusion and the upper surface of the socket protrusion are opposed to each other, and the spud protrusion is the coupling spud at the time of fastening. The entire surface of the pad on the rotation direction side forms an inclined surface that is inclined with respect to the rotation direction, and the socket convex portion is the entire surface on the side opposite to the rotation direction side of the coupling spud at the time of fastening. Is a slope inclined in the same direction as the slope of the spud convex portion, a control rod fastening mechanism for a nuclear reactor. 2. The control rod fastening mechanism for a nuclear reactor according to claim 1, wherein the sloped surface of the spud projection is inclined upward with respect to the rotational direction of the coupling spud at the time of fastening. . 3. A control rod fastening mechanism for a nuclear reactor according to claim 1, wherein a recess for receiving a bottom surface side of the spud projection is formed on an upper surface side of the socket projection. . 4. The coupling spud has a substantially cylindrical shape as a whole, and is divided into a plurality of leaf spring bodies corresponding to the respective spud protrusions by a plurality of slits extending downward from the upper end thereof. The control rod fastening mechanism for a nuclear reactor according to any one of claims 1 to 3, wherein the plurality of slits have a width at an upper portion thereof narrower than a width at another portion. 5. The coupling spud has a substantially cylindrical shape as a whole, and is divided into a plurality of leaf spring bodies corresponding to the respective spud protrusions by a plurality of slits extending downward from the upper end thereof. A substantially cylindrical compression rod extending coaxially with the coupling spud is provided inside the coupling spud, and a rib-shaped stopper extending along each slit of the coupling spud is provided on a side surface of the compression rod. 4. The method according to claim 1, wherein
A control rod fastening mechanism for a nuclear reactor according to any one of 1.