JPH0735898A - Solidifying method for incombustible waste - Google Patents

Abstract

PURPOSE:To provide a solidifying method for incombustible waste in which a plurality of incombustible radioactive wastes are fused, the bottom part is formed sequentially of unsolidified metallic components in the order of concentration to create a shield layer, and throwing the residual nonmetallic components into the finally formed multilayer shield layer. CONSTITUTION:A plurality of incombstible wastes to be treated are fused individually and a fused waste having lowest concentration of radioactive substance is poured into a rotary mold in a centrifugal casting facility thus forming metallic components on the wall of the mold and harmful metallic components on the inside thereof. Upon stopping the rotation, unsolidified components concentrate on the bottom of the mold to provide a bottom thus forming a shield layer. Subsequently, a second shield layer is formed by similar process using a fused waste having second lowest concentration of radioactive substance. The process is repeated sequentially to form an N layer shield. After solidification, residual nonmetallic components in the plurality of fused wastes are injected into the multilayer shield. This method enhances the containing effect of incombustible waste including radioactive substance and allows storage thereof in safety.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for solidifying noncombustible waste by applying a centrifugal casting method.

[0002]

2. Description of the Related Art For example, the waste generated from a nuclear power plant is roughly divided into the following two parts.

Of these, a filter which is a combustible waste,
Ion exchange resin, plastic, wood, waste cloth, clothing,
After incineration and volume reduction, paper and other materials are stored and managed in drums together with void fillings such as cement, asphalt, and resin.

On the other hand, pipes, steel plates, concrete, copper wires, etc., which are non-combustible wastes and contain heavy metals and radioactive substances, are stored and managed in drums together with void fillings such as cement, asphalt, and resin. There is.

[0005]

However, in the treatment of non-combustible waste containing heavy metals and radioactive substances, the above treatment methods have the following problems.

Non-combustible waste that is stored and managed together with void fillings such as cement, asphalt, and resin in a drum can has a non-uniform amount of heavy metal and radioactive substances, and therefore is relatively non-uniform in the above treatment method. There is a possibility that highly contaminated parts will come to the outer peripheral part of the drum, and there is a possibility that harmful substances may leak out due to corrosion of the drum due to rainwater or the like, or radiation exposure may increase.

Further, since the void filling material is used, the storage efficiency is low, so that the number of drums is increased, the transportation load is increased, and the storage space is required.

It is an object of the present invention to solve the above-mentioned problems in the processing of non-combustible waste and to provide a method of safely storing it in a reduced volume.

[0009]

In order to solve the above-mentioned problems, the present invention provides (1) a method for treating a non-combustible waste consisting of a plurality of N containing different concentrations of heavy metals and radioactive substances, The concentrations of heavy metals and radioactive substances in the plurality of non-combustible wastes are roughly measured in advance, and the plurality of N non-combustible wastes are melted in a plurality of melting furnaces, and then the lowest non-combustibility of the concentration is obtained. The metal component melt in the melt of waste is cast into a centrifugal casting facility, and after a certain period of time has formed a cylindrical part, the rotation of the mold is stopped or dropped to a speed close to the stop, and the unsolidified metal component melt To form a bottom portion of the first shielding body, and then to the first shielding body, the metal component melt in the melt of non-combustible waste having the second lowest concentration, Casting into a centrifugal casting facility with a shield 1 and passing a certain time After forming the cylindrical portion, the rotation of the mold is stopped or reduced to a rotation close to the stop, and a second shield is formed by forming the bottom portion with the unsolidified metal component melt. Thereafter, the same method is used. According to the above method, a shield composed of N layers is laminated, and finally, a non-metallic component melt in the melt of the plurality of non-combustible wastes is charged into the shield composed of the N layers. Solidification method of non-combustible waste,

(2) In the method for treating noncombustible waste consisting of a plurality of N containing different concentrations of heavy metals and radioactive substances, the concentration of heavy metals and radioactive substances in the plurality of noncombustible wastes can be roughly estimated in advance. After measuring, the non-combustible waste with the lowest concentration is melted in a melting furnace, the molten metal component in the melt is cast into a centrifugal casting facility, and after a certain period of time to form a cylindrical portion, a mold is formed. Of the non-metal component melt in the melt is formed in another container. After melting in the melting furnace, the first shield is then melted in the melting furnace with the second lowest concentration of non-combustible waste, and then in the melt. Casting the metal component melt into the centrifugal casting facility having the first shield, After forming the cylindrical portion is elapsed constant time,
Stop the rotation of the mold, or drop it to a rotation close to the stop,
After making a second shield having a bottom formed of an unsolidified metal component melt and transferring the non-metal component melt in the melt to the another container, thereafter, by the same method, A shield composed of N layers is laminated and finally, in the shield composed of the N layers, a non-metallic component melt in a melt of a plurality of noncombustible wastes transferred to the another container is placed. A method for solidifying non-combustible waste, which is characterized in that it is input.

[0011]

In the present application, assuming that the number of the shields to be arranged is N, the non-metallic component waste in which the heavy metal or the radioactive substance has been injected into the shield N having the maximum concentration is removed from the shield 1. It is performed by the wall thickness up to the shield N.

The heavy metal and the radioactive substance contained in the shield N-1 are shielded by the wall thickness from the shield 1 to the shield N-2. Hereinafter, the shield 2 is shielded sequentially by the thickness of the shield 1.

By thus selecting the concentration of the heavy metal or the radioactive substance forming the shield from the outer shield to the inner shield, the concentration is gradually increased,
Finally, it is possible to prevent the leakage of harmful substances with the concentration of the substantial shield 1.

Further, in the present invention, non-combustible waste containing harmful substances such as heavy metals and radioactive substances is melted in a melting furnace such as a gas furnace, an arc furnace, an induction furnace, etc. Is separated into

One is a metal component portion having a low concentration of heavy metals such as iron and radioactive materials,

The other one is a non-metal component part centered on the oxide.

At this time, heavy metals such as zinc, cadmium, cesium and strontium and radioactive substances are concentrated in the non-metal component part, and the concentration of the metal component part becomes extremely low.

Here, in the treatment of a plurality of noncombustible wastes containing heavy metals and radioactive substances, wet chemical composition analysis,
The approximate amounts of heavy metals and radioactive substances contained in the plurality of noncombustible wastes are measured by instrumental component analysis, GM tube, and the like.

Next, the manufacturing method of the shield will be described. There are two ways to do this.

One is to melt a plurality of non-combustible wastes for the above treatment separately in the same number of melting furnaces,
Of the melts, the first melt containing the lowest harmful substances is used and the metal component portion therein is used to inject it into the rotating mold of the centrifugal casting facility.

At this time, due to the centrifugal force and the difference in specific gravity, a metal component part is contained in the cylindrical mold wall part, and a trace amount of harmful non-metal component part is contained inside the metal component part injected into the mold. Form.

Thereafter, when the mold is stopped in rotation or brought into a state close to the stop, the unsolidified metal component parts and non-metal component parts are descended and concentrated on the bottom part of the mold, the bottom part is formed on the cylindrical object, and the shield 1 is formed. Is created.

Next, a second melt, which is the second lowest harmful substance in the melt, is used to inject the metal component portion therein into a rotating mold of a centrifugal casting facility.

As a result, similar to the above, a metallic component portion is formed on the side wall portion of the shield 1 and a harmful non-metallic component portion, which is contained in a small amount in the metallic component portion injected into the mold, is formed inside thereof. After that, when the mold is stopped or brought into a state close to the stop, unsolidified metal component parts and non-metal component parts are concentrated down to the mold bottom, and the bottom is formed on the cylindrical object to form the shield 2. .

After that, the shield N is manufactured by sequentially performing the steps.

After solidification of the shield N, the scraped non-metallic component portion of the plurality of melts intended for the treatment is then injected into the shield.

The state in which the rotation of the mold is almost stopped means that
As G _NO represented by the following formula is 20 or less,
The number of rotations should be set.

When G _NO exceeds 20, centrifugal force causes scattering of unsolidified, particularly metal component portions at the bottom into the cylindrical portion, resulting in
The thickness of the bottom portion is unevenly formed, and the metal component portion and the non-metal component portion of the bottom portion are mixed, which reduces the shielding effect, which is not preferable.

[0029]

[Equation 1]

N: Rotational speed of the mold G _NO : Centrifugal force expressed as a multiple of gravity D: Inner diameter of the mold

The second method will be described below.

That is, a plurality of non-combustible wastes for the above treatment are successively melted in one melting furnace to form a plurality of laminated shields N.

That is, the shield 1 is prepared by the same method as described above, using the melt of the first non-combustible waste containing the lowest harmful substance, which is substantially measured by the method described above.

Next, after the remaining non-metallic component part of the melt of the first non-combustible waste is transferred to another container, the second non-combustible waste having the second lowest level of harmful substances. Is melted in the same melting furnace as described above and the melt is used to form the shield 2 by the same method as described above.

Similarly, the remaining non-metal component portion of the melt of the second non-combustible waste is transferred to the separate container, and thereafter, the plurality of laminated shields N are formed while sequentially melting.

[0036]

EXAMPLE FIG. 1 shows a cross section of a container for non-combustible waste according to the present invention. Reference numeral 4 denotes a drum, which stores, transports and stores the container made by the method of the present invention.

Reference numerals 1 and 2 denote shields 1 and 2, 3 denotes a non-metal component portion generated from a plurality of wastes by the present production, and 5 denotes a lid.

In order to confirm the action and effect of the present application, claim 2 of the present application using two non-combustible wastes actually having different concentrations
The container shown in Table 1 or a conventional cement material as a comparative example was used to prepare a container with T ₁ = 200 mm and a radioactive waste of 3.4 × 10 ⁴ Bq / g was put inside. Manufactured.

After production, the dose equivalent rate was measured on the side surface 1 m of the container.

As can be seen from Table 1, according to the method of the present invention, in any of Examples 1 to 3, the exposure dose was significantly reduced from 16 μSv / h of the comparative example to 0.15 to 0.42 Bq / g. However, it is an extremely safe value.

In this embodiment, the lid 5 is made of cast iron and has a thickness of 100 mm. However, the present invention is not limited to this, and for example, like the shield 1, the lid 5 has a lower concentration. If it exists, the same operation and effect as the present application can be obtained.

Further, the conventional void filler such as resin is not required at all, and the conventional bulk density of 1 to 2 g / cm ³ is 5 to 6 g / cm ^3.
The storage efficiency, transportation and storage are greatly simplified.

[0043]

[Table 1]

[0044]

Industrial Applicability The non-combustible waste containing radioactive harmful substances can be efficiently stored, the load on transportation is reduced, the storage space is small, and there is no exposure to radiation, so that it can be safely stored.

[Brief description of drawings]

FIG. 1 is a sectional view of a container according to the method of the present application.

[Explanation of symbols]

 1 Shield 2 Shield 3 Non-metal component 4 Drum 5 Lid

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G21F 9/30 551 A 9117-2G B09B 3/00 ZAB B22D 13/02 9266-4E

Claims (2)

[Claims] 1. A method for treating noncombustible waste consisting of a plurality of N containing different concentrations of heavy metals and radioactive substances, in which the concentration of heavy metals and radioactive substances in the plurality of noncombustible wastes is roughly measured in advance. Then, after melting the N non-combustible wastes in a plurality of melting furnaces, the metal component melt in the melt of the non-combustible waste having the lowest concentration is cast into a centrifugal casting facility for a certain period of time. After the passage of the cylindrical portion, the rotation of the mold is stopped, or the rotation is stopped until the rotation is almost stopped, and the first shield is formed by forming the bottom portion with the unsolidified metal component melt. The metal component melt in the melt of the non-combustible waste having the second lowest concentration is cast into the first shield in the centrifugal casting facility having the first shield, and a cylindrical portion is formed after a certain time has elapsed. After that, stop the rotation of the mold or turn it near the stop. To form a second shield having a bottom formed of an unsolidified molten metal component, and thereafter, a shield made of N layers is formed in a laminated manner by the same method, and finally the N layer is formed. A solidification method for non-combustible wastes, characterized in that the non-metallic component melts in the melts of the plurality of non-combustible wastes are charged into a shield made of. 2. A method for treating noncombustible waste consisting of a plurality of N containing different concentrations of heavy metals and radioactive substances, in which the concentration of heavy metals and radioactive substances in the plurality of noncombustible wastes is roughly measured in advance. Then, after melting the non-combustible waste with the lowest concentration in a melting furnace, the metal component melt in the melt is cast into a centrifugal casting facility, and after a certain period of time to form a cylindrical portion, The rotation is stopped or dropped to a speed close to the stop, and a first shield is formed by forming a bottom with an unsolidified metal component melt, and the non-metal component melt in the melt is put in another container. After transferring, after melting in the melting furnace,
Next, after melting the second lowest concentration non-combustible waste in the first shield in the melting furnace, the metal component melt in the melt is provided with the first shield. A second shield formed by casting into a centrifugal casting facility, forming a cylindrical part after a certain period of time, and then stopping the rotation of the mold or dropping it to a speed close to the stop, and forming the bottom with unmelted metal component melt After forming a body and transferring the non-metallic component melt in the melt to the another container, thereafter, a shield made of N layers is laminated by the same method, and finally, the shield made of the N layers is formed. A method for solidifying non-combustible waste, characterized in that a non-metallic component melt in a melt of a plurality of non-combustible waste transferred to another container is charged into a shield.