JPS6245516B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gripping tool for measuring tubes in a nuclear reactor, and particularly to a gripping tool for a nuclear reactor that is suitable for gripping a measuring tube that has been left out of the grid without being pulled out by a pulling tool. Concerning gripping tools for measuring tubes.

Generally, in a boiling water reactor (BWR), a neutron measurement tube is usually installed in the reactor core.
These neutron measurement tubes must be replaced from time to time, and for this reason underwater tools called handling tools are used.

This handling tool includes a special handling tool for pulling out old pipes, and an insertion guide and handling tool for inserting new pipes. The system is driven by an overhead winch, a jib crane, etc.

In this case, the neutron measurement tube that has come off the grid due to a mistake in pulling out the old tube may remain upright and cannot be pulled up, and it is not easy to use the extraction tool again because the measurement tube will wobble. This neutron measurement tube is free between the upper grid and the core support plate unless the head is pushed into the lower edge of the grid, and the lower part from the core support plate is inserted into the guide tube and housing, and the core support plate is inserted into the guide tube and housing. It is about 4 to 5 meters above the plate and about 9 meters below the core support plate, so it is difficult to grasp the measurement tube that is outside the grid.

Conventionally, for measurement tubes that were left unattended from the grid without being pulled out using a puller, a special gripping device called RHT was used to suspend them using an auxiliary winch, pressurized them with a water pressure pump to hold the measurement tubes, and then depressurized them to remove the It is gripped by a spring.

Although this method is reliable, it takes more than half a day to prepare, the schedule changes, and there is a risk that the master schedule may have to be changed at times.

The present invention was devised to solve such conventional problems, and its purpose is to remove a neutron measurement tube that has been left out of the grid without being pulled out with a puller without any preparation. To provide a gripping tool for a measurement tube of a nuclear reactor that can be surely gripped.

In the present invention, a tool is attached to the tip of a flexible rope, and the weight of the tool is used to latch and extract the neutron measuring tube from the head.

The present invention will be described below based on an illustrated embodiment. FIG. 1 is a cross-sectional view showing one embodiment of the gripping device according to the present invention, in which reference numeral 1 is tied to the tip of a polyvinyl chloride rope (not shown) suspended from a lifting platform. This is a hanging ring, and a gripping tool 3 is fixed to this hanging ring 1 via a guide rod 2.

As shown in FIGS. 1 and 3, the tool 3 is generally cube-shaped and includes an inverted L-shaped main body 4 and a presser 5 disposed inside the L-shaped main body 4. As shown in FIGS.

At the center of the lower surface of the main body 4, as shown in FIG. A cutout hole 6 is provided which is made up of a continuous truncated conical part 6c, and the upper end of the truncated conical part 6c is configured to be a completely blind hole as shown in FIG. And the cylindrical part 6b
is formed to have a slightly larger diameter than the head 7a of the measuring tube 7,
Further, the upper end of the truncated conical portion 6c is formed to have a slightly larger diameter approximating the diameter of the head 7a of the measuring tube 7, as shown in FIG.

On the other hand, the presser tool 5 is provided with a tapered arcuate groove 8 that faces the notch hole 6 and tapers upward, as shown in FIG. It is positioned slightly below the head 7a of the measuring tube 7 inserted into the notch hole 6. The presser 5 passes through holes 9, 9 arranged horizontally in the presser 5, and its tip ends at the main body 4.
It is configured to be horizontally movable using two mounting bolts 10, 10 screwed into the holder as a guide.

Each of the mounting bolts 10 is shown in FIGS. 1 and 3.
As shown in the figure, springs 11 are provided around the respective peripheries, and the pressers 5 are biased toward the main body 4 by the springs 11. This presser 5 has a pulling claw 12 as shown in FIGS. 1 and 3.
is provided in a protruding manner so that the presser 5 can be moved in the direction of being pulled away from the main body 4 against the biasing force of the spring 11.

At the four corners of the lower surface of the tool 3 constructed in this way, countersunks 13 are provided, respectively, as shown in FIG.

In addition, in FIGS. 3 and 4, reference numeral 14 is a lattice, and the space of the lattice 14 is about four times as large as the lower surface of the tool 3.

Next, the operation of the present invention will be explained.

The tool 3 is lowered into the water by tying a rope from the lifting platform to a rope or chain block. Then, since the tool 3 has a required weight and the lower surface of the tool 3 is about 1/4 of the grid space of the grid 14, it can be moved freely within the grid 14 after fuel has been taken.

At this time, the head 7 of the measuring tube 7 that could not be pulled up completely
A is raised approximately 20 mm above the lower edge of the grid 14 and is floating in the square space of the grid 14.

When the tool 3 is lowered onto this head 7a, the head 7a
The presser 5 in contact with the spring 11 slides against the biasing force of the spring 11, and after passing the head 7a, the presser 5 slides against the biasing force of the spring 11.
to press the head 7a at a slightly lower position. Thereby, the measurement tube 7 is locked to the tool 3, and will not come off even if the measurement tube 7 is shaken.

After the measurement tube 7 is locked, the tool 3 is pulled up.

Note that the slide stroke of the special extractor is predetermined, so in some cases it may be possible to catch the measuring tube 7 under the grid 14 and compress it to remove it from the grid 14, but it may be necessary to pull it in further. There are some things I can't do. In this case, without worrying about the original performance of the special extractor, push it down to create momentum and release it. Then, the measurement tube 7 will come out between the grids 14, and can be grabbed using the tool 3.

As explained above, according to this embodiment, the following effects are achieved.

(1) Since mistakes in replacement work are covered, the accuracy of work completion is high.

(2) Since this work is carried out suddenly, there is no need to repurpose the auxiliary winch on the platform that lowers the special extraction tool, and there is no need to use other winches. Therefore, continuous drawing operations can be performed without interruption.

(3) Even if the removal tool used for replacement work cannot be removed, it is relatively easy to remove it from the grid, so it can be used in conjunction with the removal tool.

Note that the present invention is not limited to the above-mentioned embodiments, and for example, the notch hole 6 and the tapered arc groove 8
Changes in the shape of the etc. are included within the technical scope of the present invention.

The present invention has been described above based on the preferred embodiments, but according to the present invention, a measurement tube left out of the grid can be reliably grabbed without any preparation.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing an embodiment of the present invention;
Figure 2 is a cross-sectional view of Figure 1, and Figure 3 is a cross-sectional view of Figure 1.
4 is a plan view of the figure, and FIG. 4 is a sectional view taken along the line -- in FIG. 3... Tool, 4... Main body, 5... Holder, 6... Notch hole, 6a... Tapered part, 6d... Cylindrical part, 6c... Fractured conical part, 7... Measuring tube, 7a... Head, 8... Tapered circular arc Groove, 14...grid.

Claims (1)

[Claims] 1. A main body having a rope hanging part on the upper part, an upwardly tapered guide hole for the head of the reactor measurement tube, and a surface perpendicular to the axis of the guide hole at the upper end. and a holding tool that is attached so as to be movable in the lateral direction with respect to the guide hole so that the upper end thereof is located below at a predetermined distance from the innermost end of the guide hole. tube grip.