JP2787125B2 - Reactor cutting and removal method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cutting and removing a nuclear reactor which is cut and dismantled using a wire saw in order to disassemble and remove a used nuclear reactor.

[0002]

2. Description of the Related Art A nuclear reactor is generally operated from 30 to
Operating for 40 years is a permanent operation end period. Reactors have residual radioactivity even after the fuel has been removed, and various laws and regulations are in place for safe management and disposal of such reactors.

[0003] Decommissioning measures include shutting down a reactor facility and keeping it under appropriate control, or shutting off the reactor periphery and isolating it from the outside. It is difficult to construct new equipment near the old equipment because the equipment remains in the laying, and in recent years where the environmental conditions for installing the reactor are limited, the old equipment is removed and the new equipment is built at that position It is desired.

[0004] As a means for removing a nuclear reactor, for example, the base of the reactor of the nuclear reactor is continuously vertically moved using core boring.
There has been proposed a method of cutting horizontally, separating the base and the pressure vessel, moving them, and storing them tightly in a large waste storage.

On the other hand, the diameter of the reactor pressure vessel itself after removal of the precursor base of the reactor pressure vessel is 5 mm.
８8 m, height 12 系 18 m, and wall thickness of pressure vessel made of austenitic stainless steel is 150１５０
Since it is about 200 mm, it has been desired to establish a technique for cutting and disassembling such a large-sized pressure vessel so as to be transportable.

As a disassembly technique, a technique has been developed by the applicant of the present invention in which a grout material is press-fitted into a pressure vessel, integrated with each other, and then cut with a wire saw having diamond grains.

[0007]

According to the above technique, when cutting from the outer periphery of the pressure vessel, radioactive equipment,
Since everything can be cut integrally while preventing the base material from scattering, disassembly work can be performed safely and reliably,
In addition, the grout material has attracted attention because it has a feature that the substance having radioactivity inside is isolated and is safe for transportation and disposal.

On the other hand, in the above technique, since the outer periphery of the surface at the time of cutting is metal, the first cutout portion is stabilized.
Further, there is a demand for the development of a technique for reducing abrasion of abrasive grains of a wire saw during cutting of a metal part as a technique for further improving cutting efficiency.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for cutting and removing a nuclear reactor which can stably cut the nuclear reactor with a wire saw and has less wear of abrasive grains of the wire saw.

[0010]

In order to solve the above problems, the present invention fills a reactor with a cement grout material or a synthetic resin material, covers the outer periphery with concrete, and uses a wire saw using diamond beads from the outer periphery. The reactor inside is filled with cement grout material or synthetic resin material, and the outside of the reactor is cut by plasma, and then the inside of the reactor is cut into blocks by a wire saw using diamond beads. It is designed to cut and remove the reactor by carrying it out, so that when cutting the reactor with a wire saw, it can cut stably and reduce the wear of abrasive grains of the wire saw, improving cutting performance It was made.

[0011]

According to the present invention, as described above, when cutting a nuclear reactor, first, a cement grout material or a synthetic resin material having a high fluidity is press-fitted into the nuclear reactor so that internal equipment and the like can be cut. Is filled with a cement grout material or a synthetic resin material up to the detailed space of. Next, after the outer periphery of the reactor is covered with concrete, a wire saw using diamond beads is driven to cut. At this time, since the first cut is made of concrete material, cutting is easily started with a wire saw using beads, and when cutting the reactor body made of stainless steel, the wire saw is cut at the cut of the concrete material cut section. Guided by a stable cutting. If the wire saw cuts hard to cut due to wear of the surface of the bead material that occurs during cutting of the stainless steel reactor, the wire saw cuts the concrete material from the metal part, Works as a grindstone to polish and maintain the cutting performance of stainless steel.

[0012]

An embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a pressure vessel 1 inside a nuclear reactor is supported on a concrete base 2 by a jaw 3 thereof. A cement grout material or a synthetic resin material 4 is press-fitted from between the substrate 2 and the base material 2.

[0013] As the cement grout material, a cement or mortar paste as a base material which is appropriately mixed with an admixture for improving the fluidity for smooth filling is used, and a non-shrinkable material is suitable. .

As the synthetic resin material, various synthetic resins such as polyester resin, polyether resin, polyacrylonitrile resin, polyamide resin, vinyl chloride resin, epoxy resin, melamine resin and polyurethane resin are used. Further, a material such as an inorganic material containing calcium aluminate and calcium silicate as main components can also be used.

An opening 6 is formed in the upper part of the pressure vessel 1, and a similar cement grout material 5 or a synthetic resin material is filled from the opening 6 as well. Further, the outer peripheral concrete portion 9 is formed by framing the upper outer periphery of the pressure vessel 1 and pouring and solidifying a concrete material therein.

As a result, after the cement grout material or the synthetic resin material and the concrete material are solidified, the inside of the pressure vessel 1 and the outer periphery of the pressure vessel 1 and the inside of the concrete base 2 are all cement grout materials or pipes including various equipment such as piping. Integrated and solidified by synthetic resin material. In addition, their outer periphery is covered with a concrete part and a concrete base.

As described above, when the furnace internal structure 7 integrated with the cement grout material or the synthetic resin material and concrete is cut in the horizontal direction, as shown in FIGS. An endless wire saw 12 between a guide pulley 10 and a driving pulley 11 fixed so that the vertical position can be adjusted.
Over. The driving pulley 11 is fixed to a driving device 13 having a driving motor therein, and the driving device 13 is fixed so that its height can be adjusted.

A driving pulley 11 is fixed to the driving device 13 so as to be movable in the direction of the member to be cut, and the tension of the wire saw 12 is kept substantially constant by adjusting the fixing position. The pulling side 14 of the wire saw 12 is hung on the in-furnace structure 7, and the feeding side 15 is hung directly on the guide pulley 10 via the guide rollers 16, 16.

Since the wire saw 12 also integrally cuts a concrete material such as austenitic stainless steel which forms a pressure vessel, beads formed by sintering diamond grains together with powder such as cobalt bronze are connected. Diamond sintered beads or electrodeposited beads are used.

In the present invention, in particular, when using sintered beads when cutting a stainless steel reactor main body, even if the cutting blade surface is flattened and the machinability is deteriorated, the concrete on the outer periphery of the reactor main body is reduced. Since the material is provided, when the wire saw cuts the concrete material through the layer of the concrete material, the corners of the flattened cutting blade surface are shaved off, and an appropriate cutting blade can be formed. As described above, the concrete material on the outer periphery of the reactor body serves as a grindstone for the sintered beads of the wire saw.

When the driving device of the wire saw and the horizontal plane of the cutting section are different, as shown in FIG. 4, a driving device 21 supporting a driving pulley 20 is provided on a traveling carriage 18 on a base surface 17, and a driving pulley 20 is provided. Wire saw 22
Are guided in the cutting horizontal direction by guide pulleys 23 and 24, and the wire saw 22 is arranged so as to be drivable in a horizontal plane by a vertical guide pulley 25 and a horizontal guide pulley 26 fixed to the in-furnace structure 7 and the like.

The traveling carriage 18 moves backward so that the wire saw maintains a predetermined tension in accordance with the cutting situation. By fixing the pulley unit 27 including the vertical guide pulley 25 and the horizontal guide pulley 26 to an arbitrary horizontal plane, an arbitrary horizontal plane can be cut. Further, a wedge may be appropriately driven into the cut groove.

On the other hand, when cutting the furnace internals in the vertical direction, as shown in FIG. 5, a portal frame 30 is movably provided on rails 31 and 32 so as to surround the furnace internals 7. . The wire saw 38 is wound around each pulley of the pulley units 35 and 36 movably provided in the up-and-down direction on the pillar portions 33 and 34 of the gate-shaped frame 30, and the motor 37 drives the wire saw 38 to match the cutting condition. The vertical cutting is performed by lowering the pulley units 35 and 36.

Since the upper portion of the reactor body has a substantially spherical shape, it is extremely difficult to cut out the wire saw on the spherical surface even if an attempt is made to start an arbitrary vertical cross section at the time of vertical cutting. In the present invention, since a concrete material is provided on the outer periphery of the reactor main body, a wire saw is set at an arbitrary vertical cross section, and when cutting is started, the concrete material can be easily cut. As the cutting proceeds and reaches the reactor main body, the kerf of the concrete material becomes a guide groove, and it becomes possible to cut the spherical surface of the reactor main body without slipping.

By the horizontal and vertical cutting as described above, the furnace internal structure 7 is cut into many blocks as shown in FIG. Since these blocks are in a state in which the equipment that emits radioactivity is sealed by concrete and grout, the generation of radioactivity in each block is small, and transport and storage to waste disposal sites by appropriate transport means, Processing is performed. In addition, a new reactor can be built on the site after the removal.

[0026]

[0027]

[0028]

According to the present invention, as described above,
At the start of cutting the structure with the wire saw, the structure is cut from the concrete material, so that the cutting can be easily started and the cut edge is stabilized. After that, when cutting the metal surface of the reactor body, the cutting groove of concrete becomes the guide groove of the wire saw, and the wire saw does not slide along the curved surface of the metal surface and cuts the predetermined position stably Becomes possible.

Even when the surface of the sintered material is worn out and flattened when cutting the metal reactor main body and the machinability is deteriorated, since the concrete material layer is provided around the outer periphery of the metal material, the wire is When the saw cuts through the concrete material layer, the corner of the flattened cut surface is cut and the concrete material plays the role of a grinding stone, so the wire saw can always maintain a stable cutting blade surface, It is possible to maintain stable machinability for a period.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state where a grout material is filled in a furnace internal structure according to an embodiment of the present invention, and an outer periphery is covered with a concrete material.

FIG. 2 is a plan view showing a horizontal cutting state according to the embodiment of the present invention.

FIG. 3 is a front view showing a horizontal cutting state according to the embodiment of the present invention.

FIG. 4 is a side view showing another embodiment of the horizontal cutting of the present invention.

FIG. 5 is a front view showing an embodiment of vertical cutting according to the present invention.

FIG. 6 is a sectional view of a furnace internal structure cut according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressure vessel 2 Concrete base 4 Cement grout material or synthetic resin material 5 Cement grout material or synthetic resin material 7 Furnace internal structure 9 Peripheral concrete part 12 Wire saw 13 Drive device 18 Traveling trolley 22 Wire saw 27 Pulley unit 30 Portal frame 38 wire saw

Claims (1)

(57) [Claims] A reactor characterized in that a cement grout material or a synthetic resin material is filled in the reactor, the outer periphery is covered with concrete, and the outer periphery is cut into blocks by a wire saw using diamond beads and carried out. Cutting and removing method.