JPH0481759B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a mechanism that can be adjusted to an angle that facilitates self-orientation when core components are inserted into the core of a nuclear reactor. Slanted contact surfaces are formed on both the tip of the gripper's gripping claws and the handling head, and an oblique sliding guide mechanism is provided along these contact surfaces to adjust the core configuration by minute changes in the degree of expansion and contraction of the gripping claws. This invention relates to a mechanism for adjusting the insertion angle of core components that allows the elements to rotate while being suspended.

[Prior Art] The case of a liquid sodium cooled fast breeder reactor will be explained below as an example.

For example, as shown in FIG. 8, a fast breeder reactor has a reactor core 12 loaded with a large number of core components such as fuel assemblies in a reactor vessel 10, and low-temperature liquid sodium as a coolant is passed through an inlet pipe 14. It is configured such that it flows in from the reactor core 12, is heated by the reactor core 12, and flows out from the outlet pipe 16. A shielding plug 18 is attached to the upper part of the reactor vessel 10, and a core upper mechanism 20 and a fuel exchanger 22 are attached to the shielding plug 18.

The fuel exchanger 22 is used to transfer, position, extract, insert, etc. the core components within the reactor, and has a gripper 26 that can grip the core components 24, as shown in FIG. Gritspa 26
These include a gripping claw 30 which is pivotally attached by a pin 32 so that the tip can come out and go out from a window 28 formed on the lower side surface, and a claw opening/closing operation for controlling the expansion and contraction of the tip 30a of the gripping claw 30. The gripping claw tip 30a protruding from the window 28 is configured to be able to grip a handling head 36 on the upper part of the core component 24.

Now, the core components 24 such as fuel assemblies are
As shown in Figure 0, they have a hexagonal cross section and are regularly arranged in a triangular lattice in the reactor core. Fuel assemblies that have deteriorated due to reactor operation are removed from the reactor core, and new fuel assemblies are inserted in their place. The replacement work for these core components is performed one by one by remote control using the fuel exchanger 22, and when the coolant is liquid sodium, the operation is performed blindly. The core component is inserted by positioning the new core component above the hexagonal column-shaped hole 25 created by pulling out the deteriorated core component, and suspending and inserting the new core component. At this time, insertion is impossible unless the ridgeline of the core component 24 to be inserted and the ridgeline of the insertion hole 25 match.

Therefore, in order to ensure that the core component 24 is inserted into the hole 25 at the correct angle during insertion, in the prior art, an inclined sliding surface 38 is provided on the outside of the handling head portion 36 of the core component 24, and an entrance nozzle 40 and a wrapper tube are provided. A self-orientation mechanism is incorporated in which a key portion 44 is provided between the key portion 43 and the key portion 43 .

When the core component 24 to be inserted is gripped by the gripper 26 of the refueling machine and transferred above the insertion hole 25 and lowered, the key portion 44 is inserted into the surrounding core component forming the hole 25, as shown in FIG. It interferes with the sliding surface 38 of , and rotates to the right by a deviation angle θ while sliding and descending. This allows the ridgeline of the core component 24 to be inserted to match the ridgeline of the insertion hole 25, allowing the core component 24 to be inserted.

[Problems to be Solved by the Invention] The key part 4 located on the sliding surface 38 of the handling head part 36 and the upper part of the entrance nozzle 40
4, various shapes have been proposed. However, it actually depends on the angle of the core components inserted. Even if the above-mentioned self-orientation mechanism is incorporated, insertion may become impossible. For example, in FIG. 11, this is the case where the insertion deviation angle θ of the core component 24 is around 40 to 50 degrees. The reason why it is easy to insert the core component 24 into the hole 25 is that
When inserted into the tube, the corner portion 45a of the lower pad 45 at the lower end of the wrapper tube 43 (see Fig. 12)
Handling head 3 of the adjacent core component
Test results have shown that this is because it hits the apex of 6.

In the conventional technology, if insertion becomes impossible, there is no other way than to repeatedly try to lift and lower the fuel using a fuel exchanger until it is accidentally inserted. However, this method has the serious drawback that a large number of core components are replaced one by one, which increases the time required for fuel exchange and reduces the operating efficiency of the reactor.

In order to ensure the loading of core components into the core, it is possible to set the angle at the time of receiving taking into consideration all handling from the time of fuel reception to core loading, but this is extremely cumbersome and it is difficult to manage the insertion angle. It is.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to enable the core components to be suspended by the girders of the refueling machine even if the self-orientation mechanism does not work well during the initial insertion operation and insertion is impossible. To provide a mechanism for correcting the insertion angle of a core component, which allows smooth insertion by slightly rotating the core component while lowering it.

[Means for Solving the Problems] The present invention, which can achieve the above-mentioned objects, has devised the shape of the gripping claw tip of the fuel exchanger gripper and the shape of the handling head of the core component,
It was devised so that the insertion angle of the core components could be changed while they were suspended.

In the present invention, the fuel exchanger gripper incorporates a mechanism for finely adjusting the degree of expansion and contraction of the tips of the gripping claws. In other words, instead of a structure that simply controls displacement in two stages, such as protruding from the window or recessing into the window, as in the past, the degree of protrusion (opening degree of the tip of the gripping claw) is controlled while protruding from the window. It is equipped with a mechanism that allows for multi-step or stepless adjustment.

In addition, a chamfered and inclined contact surface is formed on the outer upper edge of the tip of the gripping claw and the lower edge of the inner circumferential ring of the handling head, and these contact surfaces slide and guide both in a diagonal direction with respect to the generatrix direction. A sliding guide mechanism is provided. As this sliding guide mechanism, for example, concavo-convex strips that mesh with each other and are slidable are preferable.

[Function] The function of the fuel exchanger gripper is basically the same as in the conventional case. That is, the tip of the gripping claw is fully opened to grip the handling head, and the core component is transferred and positioned at a predetermined insertion hole in the reactor. Then, lower it down and insert it into the insertion hole.

If the self-orientation mechanism does not work smoothly, close the tips of the gripping claws slightly so that the inclined contact surfaces are in contact with each other, and lift the gripper slightly so that both sliding guide mechanisms engage. In this state, when the tips of the gripping claws are slightly narrowed, the core components rotate slightly while sliding down slightly due to the sliding guide mechanism. While holding the position, lower the core components again and attempt insertion.

Therefore, the insertion angle of the core components changes while they are suspended, so even if the insertion angle is initially impossible, the self-orientation mechanism will be at an angle that makes it easier for the next insertion. It becomes possible to insert core components smoothly and quickly.

[Embodiment] FIG. 1 is a sectional view of a main part showing an embodiment of the present invention. The basic structures of the grippers and core components are almost the same as those of the prior art shown in FIG. 9, so corresponding parts are given the same reference numerals to simplify the explanation. The gripper 26 of the fuel exchanger is provided with windows 28 on both sides of its lower side, and the tips 30a of the gripping claws 30 are configured to be freely retractable from the windows 28. Therefore, although the gripping claws 30 are not shown in FIG.
A claw opening/closing operation rod is inserted between the opening and closing openings, and swings depending on the insertion position, so that the tip 30a emerges and retracts from the window portion 28.

In the present invention, the gripping claw tip 30a does not have a structure in which it can simply be moved in and out in two steps, but has a structure in which the degree of protrusion can be finely adjusted in multiple steps or steplessly while protruding from the window portion 28. This can be easily accomplished by forming an appropriate taper in the outer shape of the claw opening/closing operating rod and in the shape of the contacting inner surface of the gripping claw 30 with which it comes into contact.

As described above, the gripper 26 of the present invention is significantly different from the prior art in the shapes of the gripping claw tips 30a and the inner surface of the handling head 36. Details of the gripper 26 in this embodiment are shown in FIGS. 2A and 2B, and details of the handling head 36 are shown in FIGS. 3A and 3B. A chamfered inclined contact surface is formed on the outer upper edge of the gripping claw tip 30a, and a similar chamfered contact surface is formed on the inner circumferential lower edge of the handling head portion 36. A plurality of uneven stripes 50 are formed on the contact surface of the gripping claw tip 30a in a diagonal direction with respect to the generatrix direction of the contact surface, and also on the contact surface of the handling head section 36 in a diagonal direction with respect to the mother ship direction. A large number of uneven stripes 52 are formed on the surface. The uneven strips 50 of the gripping claw tips 30a and the uneven strips 52 of the handling head 36 are structured to mesh with each other and to be slidable along the direction in which the uneven strips are formed, that is, in a direction inclined to the generatrix direction. .

The operation of the insertion angle correction mechanism constructed in this way is as follows. First, as shown in FIG. 4, the handling head portion 36 is
Suspend the core component 24 by grasping the lower surface of the
Transfer it to above the predetermined insertion hole. Then lower it and try to insert it. At this time, if the self-orientation mechanism does not work properly and insertion becomes impossible, proceed as follows.

The core component 24 to be inserted interferes with the surrounding core components and becomes lifted as shown in FIG. 5, so the gripping claw tips 30a are separated from the handling head 36.

The gripping claws 30 of the gripper 26 are slightly closed and pulled up so that the uneven stripes 50 on the gripping claw tips 30a and the uneven stripes 52 on the handling head section 36 come into contact with each other (see FIGS. 6 and 7), and then hung as is. Raise the key part of the lowered core component by a distance (usually several tens of millimeters) so that it no longer interferes with surrounding core components.

In this state shown in FIG. 6, the gripping claw tip 30
A is gradually contracted and closed as shown by arrow P. Then, the uneven line 50 of the gripping claw tip 30a and the uneven line 5 of the handling head part 36 mesh with each other.
2 and rotates in the direction of arrow R while descending to the handling head 36 as shown by arrow Q. As a result, the insertion angle is corrected compared to the initial insertion state.

The opening degree of the gripping claws 30 is fixed as it is, and the core component 24 is held.

Then, the core component 24 is lowered again and an attempt is made to insert it into the hexagonal hole at the insertion position. Generally, this operation provides a self-orientation mechanism that allows the core to be positioned between surrounding core components.

If the insertion is not possible even after these series of operations, the gripping claw tip 30a and the handling head 3
Since there is a gap between the gripping claws 30 and 6,
Fully open the reactor, re-grasp the core components, and repeat the above steps again. The deviation angle is thereby reduced and certain angles in which self-orientation is not possible are avoided.

Although it varies depending on the configuration of the self-orientation mechanism and the configuration of the uneven strips in the insertion angle correction mechanism, in general, the new core component can be smoothly inserted into the specified insertion hole by performing the above operation once. be able to.

Although the above-described embodiment uses concave and convex strips that engage with each other as the sliding guide mechanism, the present invention is not necessarily limited to such a configuration. It is also possible to have a structure in which one side has a large number of grooves and the other side has a projection (for example, a point-like projection) that fits into the groove, and these are combined.

[Effects of the Invention] As described above, the present invention forms chamfered contact surfaces on the tips of the gripping claws of the gripper and on the inner surface of the handling head, respectively, and provides a diagonal sliding guide mechanism on these contact surfaces. The structure allows the core components to rotate slightly while suspended due to the fine adjustment mechanism for the degree of expansion/contraction at the tip, so even if the self-orientation mechanism does not work properly and the core components cannot be inserted into the designated holes. , the orientation of the core components to be inserted can be corrected and inserted reliably and quickly with an extremely simple operation,
This has the excellent effect of shortening the fuel exchange time and improving the operating rate of the reactor.

In addition, the present invention has an extremely simple configuration, requiring only slight processing on core components and a part of the handling head of a conventional structure. is also applicable.

Furthermore, with the present invention, the insertion angle of the core components can be corrected within the reactor, so there is no need for complicated insertion angle management, such as setting the angle at the time of reception, taking into account all handling from fuel reception to core loading. There are also some effects.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of essential parts showing an embodiment of the insertion angle correction mechanism for core components according to the present invention, and FIG.
2B is a plan view of the gripper, FIG. 2B is a side view thereof, FIG. 3A is a plan view of the handling head, FIG. Fig. 5 is an explanatory drawing showing the initial state where the insertion is impossible, Fig. 6 is an explanatory drawing showing the state when the insertion angle is being corrected. , Fig. 7 is an explanatory diagram showing the engagement state between the gripping claw tip and the handling head, Fig. 8 is an explanatory diagram showing an example of a liquid sodium cooled fast reactor, and Fig. 9 is an explanatory diagram showing a reactor core using a conventional fuel exchanger gripper. An explanatory diagram showing the gripping state of the components, FIG. 10 is an explanatory diagram showing the core components to be inserted and a hexagonal column-shaped hole formed at the insertion position, and FIGS. 11 and 12 are the operation of the self-orientation mechanism. It is an explanatory diagram. DESCRIPTION OF SYMBOLS 10... Reactor vessel, 12... Reactor core part, 22... Fuel exchange machine, 24... Core mechanism element, 26... Gripper, 30... Gripping claw, 30a... Gripping claw tip,
36... Handling head section, 50, 52...
Uneven stripes.

Claims (1)

[Scope of Claims] 1. A refueling machine gripper incorporates a mechanism for finely adjusting the degree of expansion/contraction of the tips of the gripping claws, and a chamfered shape is provided on the outer upper edge of the gripping claw tips and the inner lower edge of the handling head of the core component. 1. A mechanism for adjusting the insertion angle of a reactor core component, characterized in that the contact surfaces are provided with a sliding guide mechanism that guides the contact surfaces in a direction oblique to the generatrix direction of the contact surfaces. 2. Insertion of the core component according to claim 1, wherein the sliding guide mechanism is comprised of a large number of concave and convex strips that are capable of engaging and sliding with each other on both of the contact surfaces and extending diagonally with respect to the generatrix direction of the contact surfaces. Angle correction mechanism.