Apparatus for demolishing a reactor shield wall

Details Apparatus for demolishing a reactor shield wall Apparatus for demolishing a reactor shield wall

1987-06-25

1989-03-21

Kyle, Deborah L.

Turning

Lathe

Portable

82169, 82 82, 83178, 83923, 376260, 299 70, E04G 2308, G21F 928

Patent

active

048133132

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to an apparatus for demolishing a reactor shield wall, or the like.


BACKGROUND ART

The inner surface layer of a shield wall of a reactor which has long been in operation is generally radioactively contaminated. In the process of demolishing such a wall in connection with the removal of such a reactor, it is a usual practice to employ a remotely operable demolishing apparatus.
A prior-art demolishing apparatus of this type is disclosed in Japanese Published Unexamined Patent Application No. 59-27297.
This prior-art apparatus has a pillar extending from above the top of the reactor toward the bottom thereof and cutting devices mounted up and down movably on the pillar for cutting the reactor shield wall. Each cutting device is retractably laterally extensible, that is, extensible toward and retractable from the shield wall, and is swingable around the pillar. In this known demolishing apparatus, the cutting device has a complex gear mechanism incorporated in it for allowing such up-and-down and swinging movement of the cutting device.
Now, demolishing work for removal of a reactor is generally carried out over a long period of time, and meanwhile, the demolishing apparatus must be subject to periodic maintenance and inspection. In view of this, therefore, it is desirable that a driving portion of the apparatus should be positioned at the top of the reactor so as to permit easy access thereto for inspection and to minimize the possibility of being exposed to radioactive contamination.
From this standpoint, the construction of the known demolishing apparatus has a drawback in that the drive mechanism, i.e., the gear mechanism for the cutting device, is incorporated in the cutting device itself. Accordingly, it is an object of the invention to provide an apparatus for demolishing a reactor shield wall wherein a mechanism for driving cutting devices may be mounted on the top of the reactor. More specifically, the object of the invention is to provide a shield wall demolishing apparatus such that a drive mechanism for swinging cutting devices may be allowed to remain located on the top of the reactor.


DISCLOSURE OF THE INVENTION

This object is accomplished in accordance with the invention in that the pillar is swingable so as to allow swinging movement of the cutting devices as described above. More particularly, the pillar is swingably supported by an upper support device which is provided with a drive device for actuating the pillar to swing.
According to this arrangement, the drive device is driven to actuate the pillar to swing, so that each cutting device is allowed to be positioned at any desired position on and about the pillar.
According to this arrangement, at least the drive device for actuating swing motion of the pillar is mounted on the top of the reactor and this permits easy maintenance and inspection and eliminates the possibility of exposure to radioactive contamination.


BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
FIG. 1 is a sectional front view showing a reactor shield-wall demolishing apparatus according to a first embodiment of the invention;
FIG. 2 is a sectional view showing a lower support device set on the bottom of the reactor for supporting a pillar;
FIG. 3 is a sectional view of a cutting device;
FIG. 4 is a partial sectional view of another cutting device;
FIG. 5 is a front view in section showing an upper portion of the pillar;
FIG. 6 is a sectional view showing a cut mode of a surface layer of a shield wall;
FIG. 7 is a sectional view in front elevation showing a reactor shield-wall demolishing apparatus according to a second embodiment of the invention;
FIG. 8 is a plan view showing a lower support device in FIG. 7;
FIG. 9 is a section taken on line IX--IX in FIG. 8;
FIGS.

REFERENCES:
patent: 3370888 (1968-02-01), Skendrovic
patent: 4594774 (1986-06-01), Barker et al.
patent: 4664873 (1987-05-01), Hendrich et al.
Supplementary European Search Report.

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