JP2583263B2 - Highly radioactive solid waste cutting equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to underwater plasma cutting technology, and more particularly to a cutting device suitable for cutting highly radioactive solid waste.

[Conventional technology]

As a cutting technique used in a conventional high radioactive solid waste cutting apparatus, for example, as described in Japanese Patent Application No. 58-60814, a "consumable electrode type arc cutting method" (Patent No. 1154604) The application of is known.

The above-mentioned known cutting technique is an improvement of the consumable electrode type arc cutting method using a solid wire or the like as an electrode. A water jet nozzle is provided outside a contact tip of a wire electrode, and high pressure water is jetted from the nozzle to arc heat. This is a cutting method in which a material to be cut (hereinafter, referred to as a base material) melted by blowing is blown off.

However, in the above-described known cutting method, a potential difference is provided between the base material and the wire that is an electrode, and an arc is generated between the two. Therefore, the base material must be a conductor.

However, some highly radioactive solid waste to be cut by this cutting device has a ceramic-like non-conductive oxide film formed on the surface of the base material as it is used in a nuclear reactor facility. There is a problem that it is not stable. In addition, the quality of water in the pool that stores highly radioactive solid waste is required to be close to that of pure water. However, in the case of this cutting method, since the electrode wire is melted together with the base material, dross (molten metal particles) ) May occur in large quantities and contaminate the pool water, so that a large-scale water purification device is required.

On the other hand, the plasma cutting method is a technique for generating an arc similarly, but is a non-transfer type plasma (also called a plasma jet) that generates an arc without giving a potential difference to a base material, or a thick-walled plasma. There are transfer-type plasma cutting methods and the like that can also be applied to a base material, and these non-transfer-type plasma cutting methods and transfer-type plasma cutting methods are relatively easy to apply to underwater cutting.

[Problems to be solved by the invention]

However, the plasma arc is generated by supplying an operating gas such as an argon gas to the arc generated between the electrodes, ejecting the gas as a plasma gas flow, melting the base material, and further blowing off the base material.

Therefore, when plasma cutting is used for highly radioactive solid waste that needs to be cut in water, the plasma gas flow is suppressed in ejection energy by water pressure, the ability to remove molten base material is reduced, and dross is reduced. There is a drawback that phenomena such as adhesion and fusion again behind the cut portion occur.

The present invention has been made in view of the above circumstances, and provides a high-radioactive solid waste cutting apparatus capable of performing high-quality cutting without dross generated by cutting being attached to a cut-off object. The purpose is to:

[Means for solving the problem]

The above object is achieved by forcibly removing generated dross or promoting the ability to remove a molten base material.

In the present invention, the latter method of promoting the exclusion ability is adopted, and a nozzle capable of jetting water to the fusing portion of the base material by the plasma arc is provided.

As a technique of disposing a nozzle in a plasma cutting machine, a plasma cutting apparatus described in Japanese Utility Model Application Laid-Open No. 62-109862 has been proposed.

However, the above-described technique is intended to reduce adhered dross in plasma cutting in the air and to facilitate collection of fine particles in the generated fumes.
The present invention ejects liquid water, as compared to ejecting a gas or a liquid that easily vaporizes from an arranged nozzle, and has a completely different technical idea.

In addition, when the above-mentioned known technique (Japanese Utility Model Application Laid-Open No. 62-109862) is applied to underwater cutting, the gas injected from the nozzle rises as bubbles while being affected by the water pressure, so that the molten base material is excluded. There is also a problem that no improvement can be expected.

That is, in the present invention, a highly radioactive solid waste cutting device that moves a plasma torch along a cut object made of highly radioactive solid waste placed in a water tank and cuts the cut object by a plasma arc. A plasma torch that generates a plasma arc while moving along the cutting part of the object in the water tank, and is mounted at a position opposite to the direction of movement of the plasma torch with respect to the plasma torch, and cuts the object to be cut. At the time, the front end portion sprayed high-pressure water toward the fusing portion of the object, and was supported so as to be able to move forward and backward toward the fusing portion of the object and to be rotatable along the moving direction of the plasma torch. Nozzle, having means for supplying high-pressure water to the nozzle, means for supplying the high-pressure water,
A valve for adjusting the pressure and flow rate of high-pressure water to be supplied to the nozzle is provided.

[Action]

During the cutting operation, the workpiece is melted by the plasma arc from the plasma torch. At this time, the jet pressure of the plasma gas flow is suppressed by the water pressure, and the molten dross may adhere to the workpiece.

However, in the present invention, when jet water is jetted from the rear of the plasma torch by the nozzle, the jet water from the nozzle is jetted toward the fusing portion of the object to be cut. The dross immediately after the dross is likely to adhere to the object to be cut can be scattered, so that the dross immediately after the melting can be efficiently removed, and a high-quality cut can be obtained.

Moreover, even if the conditions such as the thickness of the object to be cut and the cutting speed change, by adjusting the position of the nozzle tip with respect to the object to be cut, and by adjusting the pressure and flow rate of the high-pressure water to be supplied to the nozzle, It is possible to deal with it freely, and it is possible to cut highly radioactive solid wastes of various shapes into non-defective products. Also, with respect to an increase in external pressure due to an increase in cutting water depth, by increasing the injection water pressure as described above, an efficient dross and molten base material rejection effect can be obtained.

〔Example〕

 FIG. 1 is an explanatory diagram showing a first embodiment.

A state in which a material 2 to be cut (hereinafter, referred to as a base material 2) such as a highly radioactive solid waste is cut by an underwater plasma torch (hereinafter, referred to as a torch 1) that cuts below the surface of a water tank (or a storage pool) 4 Is shown. An arc generated between the torch 1 and the base material 2 is ejected as a plasma arc 3 by ejecting an inert gas such as an argon gas supplied as an operating gas. As a result, the base material 2 is melted by the thermal energy of the plasma arc 3, and the melted base material is separated from the base material 2 as dross 5. Here, a nozzle 6 capable of jetting water
(Hereinafter referred to as jet water nozzle 6) is mounted near the torch 1. That is, the jet water nozzle 6 is attached to a position near the torch 1 in a direction opposite to the traveling direction A of the cutting operation of the torch 1 so that the jet water 7 can be jetted to the fusing portion of the base material 2. The tip is inclined. At the time of cutting, jet water 7 is supplied to the nozzle 6 behind the torch 1.
By spraying the dross 5 from the melted portion of the base material 2, the detachment (or elimination) of the dross 5 is promoted, and a high quality cut shape is obtained.

FIG. 2 is a sectional view showing a second embodiment. This second
In this embodiment, as an application example of the first embodiment, a jet water nozzle 6 is incorporated in the torch 1 integrally. The jet water nozzle 6a is incorporated in the outer periphery of the torch 1 ', and jets the jet water 7 supplied from the jet water supply device 20 to the base material 2.

According to the experiments performed by the present inventors, the jet direction of the jet water 7 does not cause disturbance or the like of the plasma arc 3 when jetted from behind the torch 1 with respect to the cutting direction A. It has been confirmed that the dross 5 immediately after melting can be scattered as it tries to adhere to the base material 2, and that the dross 5 immediately after melting can be efficiently removed. Further, the jetting position, distance, jet water pressure, and flow rate of the jet water 7 to the base material 2 are appropriately set according to the thickness of the base material 2 to be cut, the capability of the generated plasma arc 3 and the cutting speed. We confirm that it is necessary. In carrying out the method of the present invention, appropriate values of these parameters can be easily obtained experimentally.

FIG. 3 is an explanatory view showing a third embodiment. In this embodiment, the jetting position of the jet water 7 can be adjusted by swinging and expanding and contracting the jet water nozzle, and the pressure and flow rate of the jet water 7 can be adjusted.

The distal end of a jet water nozzle 6 'disposed on the torch 1 "via a holder 8 is provided with a telescopic nozzle 6b which can expand and contract in the direction of a reciprocating arrow C. The telescopic nozzle 6b is a rotary joint 9 The jet water 7 is supplied from a jet water supply device 20 and is adjusted to an appropriate value by a pressure control valve 21 and a flow control valve 22. .

According to the present embodiment (FIG. 3), even if conditions such as the thickness of the base material to be cut and the cutting speed are changed, it is possible to freely adjust and cope with one apparatus system, and various shapes can be obtained. Highly radioactive solid waste can be cut into good products. Such a problem can be easily dealt with by increasing the injection water pressure, even when the external pressure increases with an increase in the cutting water depth.

〔The invention's effect〕

According to the present invention, at the time of cutting, jet water from the nozzle is jetted from behind the plasma torch toward the fusing portion of the object to be cut, without significantly reducing the plasma arc injection energy, and dross immediately after melting is reduced. Since it is configured to surely disperse what is going to adhere to the object to be cut, dross immediately after melting can be efficiently removed, and high-quality cutting can be obtained. Even if conditions such as the thickness of the welded material and the cutting speed change, the position of the nozzle tip is adjusted with respect to the workpiece, and the pressure and flow rate of the high-pressure water to be supplied to the nozzle are adjusted. It is possible to easily cope with it, and it is possible to cut high-radioactive solid wastes of various shapes into non-defective products, thereby improving cutting performance.

In the experiments of the present inventors, as a performance comparison between the use and non-use of the present invention under a certain cutting condition, for example, when comparing the cutting speed, it is 2-3 times higher than the non-use when used. It has been confirmed that the same or higher cutting quality can be obtained even at a cutting speed of.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention and is an explanatory view showing a basic configuration in which a jet water nozzle is arranged near a torch. FIG. 2 shows a second embodiment of the present invention, and is a cross-sectional view showing a structure in which a jet water nozzle is integrated with a torch 1. FIG. 3 shows a third embodiment of the present invention, and is a cross-sectional view showing a structure capable of adjusting the jetting position, pressure, and flow rate of jet water. 1 ... torch, 2 ... base material, 5 ... dross, 6 ... jet water nozzle, 6b ... telescopic nozzle, 7 ... jet water,
20: a jet water supply device, 9: a rotary joint, 21: a pressure regulating valve, 22: a flow regulating valve.

Claims (1)

(57) [Claims] 1. A highly radioactive solid waste cutting apparatus for moving a plasma torch along an object of high radioactive solid waste installed in a water tank and cutting the object by a plasma arc, A plasma torch that generates a plasma arc while moving along the cutting part of the object in the water tank, and is attached to the plasma torch at a position opposite to a moving direction of the plasma torch, and when cutting the object, A nozzle whose tip end injects high-pressure water toward the fusing portion of the object to be cut, and which is supported so as to be able to advance and retreat toward the fusing portion of the object and to be rotatable along the moving direction of the plasma torch, Means for supplying high-pressure water to the nozzle, wherein the means for supplying high-pressure water includes a valve for adjusting the pressure and flow rate of the high-pressure water to be supplied to the nozzle. Things cutting device.