JPS5926100A - Method of dismantling reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention provides a method for dismantling a nuclear reactor, more specifically, a method for dismantling a nuclear reactor, and more specifically, a method for dismantling a nuclear reactor, in which a cutting torch is disposed inside the reactor, and the cutting torch is moved by remote control. This article relates to a method for dismantling a nuclear reactor that involves cutting off the attached parts.

BACKGROUND ART In recent years, as the development of nuclear reactors has progressed at power plants, it has become necessary to dismantle reactors whose operating efficiency has deteriorated, and methods of dismantling these reactors are being considered.

By the way, since such nuclear reactors themselves are high-level radioactive waste, workers cannot directly approach or enter the reactor to dismantle it, and must necessarily use remote control. . In practical terms, it is important that this remote-controlled dismantling equipment be lightweight and compact.For this reason, the fuel rods and control rods present in the reactor, as well as the various pipes and pipes located on the inner wall of the reactor, are important for practical purposes. It is conceivable that after accessories such as a pump diffuser are cut and removed, the furnace body is cut using a cutting torch placed inside the furnace.

However, when the cutting torch is disposed within the furnace body in this manner, it is difficult to control the position of the cutting torch because it cannot be visually observed.

As a result of intensive studies in view of the above points, the present inventors have determined that the reactor body has a cylindrical shape and that one of the control rod drive mechanism housing groups provided at the bottom of the reactor body is located at the center of the reactor body. The present invention was developed by paying attention to the fact that

That is, after the fuel and control rods in the reactor are removed, the lower end is supported by the control rod drive mechanism housing that exists at the center of the circle of the control rod drive mechanism housing group remaining at the bottom of the reactor, and the upper part is supported at the center of the reactor. The present invention provides a method for dismantling a nuclear reactor, in which at least an accessory provided on the inner wall of the reactor is cut while moving a cutting torch around a support rod held in the reactor.

An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a sectional view showing a state in which an apparatus for carrying out the method of the present invention is installed in a nuclear reactor.

The reactor A includes a main body 1 consisting of an upper hemisphere and a cylindrical part ta (not shown), a hemisphere formed below the hemisphere, a housing 2 for a control rod drive mechanism in which a plurality of hemispheres bK are installed, A pipe 6 provided on the inner wall of the cylindrical portion a, a buffer plate 4 provided at the boundary between the cylindrical portion a and the hemispherical portion, and accessories such as a jet pump diffuser 5 provided on the buffer plate 4. , a fuel section 6, a control rod 7, etc. arranged inside.

The control rod drive mechanism housing 2a in the control rod drive mechanism housing 2 is arranged at the center of the main body 1, and a plurality of piping 6 and jet pump diffusers 5 are provided along the inner wall of the main body 1. There is.

The apparatus for carrying out the present invention is composed of a rotary girder 8, an extension arm 9, and a swinging arm 11 having a plasma arc torch 10 at its tip.

Specifically, a plurality of rollers 12 are attached to the lower peripheral edge of the rotary girder 8, and a drive device 16 such as a motor is connected to at least one of the rollers 12 inside.

A telescopically formed telescopic rod 9 is suspended from the center of the rotary girder 8, and a vertical drive mechanism 14 for extending and contracting the telescopic rod 9 is provided above the rod.

As shown in FIG. 2, the lower end of the telescoping rod 9 is provided with a support portion 15 having a taper 15a at the bottom, so that when the telescoping rod 9 is lowered, its tip easily enters the control rod drive mechanism housing 2a. It looks like this.

A swinging arm 11 having a Blazuma arc torch 10 at its tip
is constructed such that it can be bent at least in the vertical direction by a link mechanism, and is attached to the telescopic rod 9 by an attachment member 16. The mounting member 16 may be detachable as required, or may be configured to be movable up and down.

If reactor A is to be dismantled with this configuration, first the upper hemisphere, fuel section 6 and control rod section 7 (not shown) are removed by known means, and then the rotary girder 8 is removed.
is placed on the upper edge of the cylindrical part a using a crane or the like. As a result, the upper part of the support rod 9 is held at the center of the main body 1. From this position, the vertical drive mechanism 14 is operated to lower the tip of the telescopic rod 9, and the tapered portion 15a is inserted into the control rod drive mechanism housing 2a and fixed.

Thereafter, the swinging arm 11 is operated to position the plasma arc torch 10 to the location to be cut and start cutting,
When the drive device 16 is driven, the rotary carter 8 rotates, so that the plasma arc torch 10 is moved in an arc in the horizontal direction around the telescopic rod 9. in this case,
The piping 6, buffer plate 4, jet pump diffuser 5, and other accessories provided on the inner wall of the main body 1 are first cut, and the cut pieces are taken out of the furnace by a manipulator (not shown). It is better to cut a.

FIGS. 3 and 4 show another embodiment of the upper holding mechanism for the telescopic rod 9, in which holding arms 26 and bevel gears 22 are provided on at least three sides of the donut-shaped holding member 21, which are extendable and retractable by hydraulic pressure or the like. A hydraulic device 25 having a bevel gear 24 is rotatably attached to the center thereof. According to such a holding mechanism, if the oil pressure source for each holding arm 26 is made the same, the upper part of the telescopic rod 9 can be easily aligned with the center of .

In the case of this O-holding mechanism, it is preferable that the support portion 15 provided at the lower end of the telescoping rod 9 is provided with a ball bearing or the like to ensure smooth rotation.

As described above, according to the present invention, since the telescoping rod 9 is arranged with reference to the control rod drive mechanism housing 2a arranged at the center inside the main body, the alignment is extremely easy, and the swing arm 11 By setting the height of the mounting member 16 to match the height of the cutting location, alignment of the plasma arc torch 10 is quick and easy.

Particularly when cutting an appendage that has an arc that is similar to the main body 1, setting the plasma arc torch 10 at the initial cutting position is very effective as it is only necessary to rotate the telescopic rod 9.

Of course, the present invention is not limited to the above embodiments. The important point of the present invention is the technical concept of aligning the telescopic rod and the main body using the housing for the control rod drive mechanism that remains at the center of the furnace bottom, and controlling the movement of the cutting torch based on this telescopic rod. be. Therefore, it is clear that various changes can be made without departing from this concept.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the state in which an apparatus for carrying out the method of the present invention is installed in a nuclear reactor, Fig. 2 is an enlarged sectional view of section C in Fig. 1, and Figs. FIG. 3 is an illustration of another device for holding the upper part of the telescopic rod for carrying out the method;
The figure is a plan view, and FIG. 4 is a sectional view taken along the line B-Bi in FIG. 3. 1. Φ body, 2.2a.. buffer plate, 5 @ conflict jet pump differential user, 6.. fuel section, 7..
Control rod part, 8... Rotating girder 19... Telescopic rod, 10... Plasma arc torch, 11... Swinging arm, 15... Support part, 2
1. Holding member, 26. Holding arm, A.. Nuclear reactor, a.
- Cylindrical part, b... Hemispherical part. Figure 3 Figure 4 Procedural amendment (method) Mr. Commissioner of the Japan Patent Office '""'"+1251"1, Indication of the case 1980 1/Patent application No. 13557] 82, Name of the invention Method for dismantling a nuclear reactor 3 , the person making the amendment jG1'1...!: Patent applicant 4, agent

Claims (1)

[Claims] After removing the fuel part and the control rod part in the reactor, the lower end of the control rod drive mechanism housing group remaining at the bottom of the reactor is supported by the uncontrolled salary drive mechanism housing in the center, and A method for dismantling a nuclear reactor, characterized in that at least an accessory provided on an inner wall of the reactor is cut while a cutting torch is moved around a support whose upper part is held at the center of the reactor.