JP2987671B2 - Solidification of non-combustible waste - 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 solidifying non-combustible waste using a centrifugal casting method.

[0002]

2. Description of the Related Art For example, wastes used in a nuclear power plant and generated therefrom are roughly divided into the following two parts.

[0003] Of these, filters that are combustible waste,
Ion exchange resin, plastic, wood, waste, clothing,
After incineration and volume reduction, paper and the like are stored and managed in a drum together with void fillers 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 materials, are stored and managed in a drum together with void fillers such as cement, asphalt and resin. I have.

[0005]

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

[0006] Non-combustible waste stored and managed in a drum together with void fillers such as cement, asphalt, resin, etc., are not uniformly contaminated by heavy metals and radioactive substances. There is a possibility that a highly contaminated portion may come to the outer peripheral portion of the drum, and there is a possibility that harmful substances leak due to corrosion of the drum by rainwater or the like or an increase in radioactive exposure.

[0007] Further, the use of the void filler reduces the storage efficiency, which increases the number of drums, increases the load in transportation, and requires more storage space.

[0008] It is an object of the present invention to solve the above-mentioned problems in the treatment of non-combustible waste and to provide a method for safely storing in a reduced volume form.

[0009]

Means for Solving the Problems To solve the above problems, the present invention provides (1) a method for treating non-combustible waste consisting of a plurality of N, which contains different concentrations of heavy metals and radioactive substances, In advance, the concentrations of heavy metals and radioactive substances in the plurality of non-combustible wastes are roughly measured, and after melting the plurality of N non-combustible wastes in a plurality of melting furnaces, the lowest incombustible The molten metal component in the waste melt is cast into a centrifugal casting facility, and after a certain period of time, a cylindrical part is formed.The rotation of the mold is stopped or reduced to a speed close to the stop. A first shielding body having a bottom portion formed therein is formed. Next, the first shielding body is provided with a metal component melt in the melt of the non-combustible waste having the second lowest concentration, and Cast into a centrifugal casting facility with a shield and pass a certain time After the formation of the cylindrical portion, the rotation of the mold is stopped or reduced to a rotation close to the stop, and a second shield formed by forming a bottom portion with a non-solidified metal component melt is formed. By laminating and forming a shield composed of N layers, finally, the non-metal component melt in the melt of the plurality of noncombustible wastes is charged into the shield composed of the N layers. Solidification method for non-combustible waste,

(2) In a method for treating a plurality of N non-combustible wastes having different concentrations of heavy metals and radioactive substances contained therein, the concentrations of the heavy metals and radioactive substances in the plurality of non-combustible wastes may be roughly determined in advance. Measured, after melting the lowest concentration of non-combustible waste in a melting furnace, casting the metal component melt in the melt into a centrifugal casting facility, allowing a certain time to elapse and forming a cylindrical portion, then mold The rotation of the metal is stopped or reduced to a rotation close to the stop, a first shield is formed by forming a bottom portion with the unsolidified metal component melt, and the non-metal component melt in the melt is separated into another container. After melting in the melting furnace, then, the second shield of the non-combustible waste having the second lowest concentration in the first shield is melted in the melting furnace. Casting the metal component melt into a centrifugal casting facility having a 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,
A second shield formed by forming a bottom with the unsolidified metal component melt is formed, and the non-metal component melt in the melt is transferred to the another container, and thereafter, by the same method, A shield formed of N layers is formed by lamination, and finally, the non-metal component melt in the melt of the plurality of non-combustible wastes transferred to the another container is placed in the shield formed of the N layers. A method for solidifying non-combustible waste.

[0011]

In the present application, assuming that the number of shields to be provided is N, the nonmetallic component waste in which heavy metals and radioactive substances are introduced into the shield N having the maximum concentration is removed from the shield 1. This is performed by the thickness up to the shield N.

The shielding of heavy metals and radioactive substances contained in the shield N-1 is performed by the thickness from the shield 1 to the shield N-2. Hereinafter, the shielding of the shielding body 2 is sequentially performed by the thickness of the shielding body 1.

As described above, by selecting the concentration of the heavy metal or radioactive substance constituting the shield from the outer shield to the inner shield, the concentration is selected so as to increase sequentially.
Finally, it is possible to prevent harmful substances from leaking at 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, or an induction furnace. Is separated into

One is a metal component portion having a low concentration of heavy metals and radioactive substances, mainly iron.

The other one is a non-metal component portion centering 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 portion, and the concentration of the metal component portion is extremely low.

Here, in the treatment of a plurality of non-combustible wastes including heavy metals and radioactive substances, wet chemical component analysis,
Approximate amounts of heavy metals and radioactive substances contained in the plurality of non-combustible wastes are measured by instrumental component analysis, GM tubes, and the like.

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

One is that a plurality of noncombustible wastes to be treated are separately melted in the same number of melting furnaces, respectively.
The first melt having the lowest harmful substance among the melts is used and poured into a rotating mold of a centrifugal casting facility by using a metal component portion therein.

At this time, due to the centrifugal force and the specific gravity difference, a metal component portion is present in the cylindrical mold wall portion, and a harmful non-metal component portion contained in the metal component portion in a minute amount in the cylindrical mold wall portion. Is formed.

After that, when the mold is stopped or almost stopped, the unsolidified metal component and non-metal component fall and concentrate on the bottom of the mold, and the bottom is formed on the cylindrical body, and the shield 1 is formed. Is made.

Next, the second melt having the second lowest harmful substance among the above melts is used and poured into a rotating mold of a centrifugal casting facility by using a metal component portion therein.

As a result, similarly to the above, a metal component portion is formed on the side wall portion of the shield 1 and a harmful non-metal component portion contained in a trace amount in the metal component portion injected into the mold is formed inside the side wall portion. Thereafter, when the mold is stopped or turned to a state close to the stop, the unsolidified metal component and non-metal component fall down and concentrate on the bottom of the mold, and the bottom is formed on the cylindrical shape to form the shield 2. .

Thereafter, the operation is sequentially performed to form the shield N.

Thereafter, after the shield N is solidified, the exposed non-metallic components of the plurality of melts to be processed are injected into the shield.

The condition that the rotation of the mold is almost stopped is as follows.
So that G _NO represented by the following equation is 20 or less,
The rotation speed may be set.

When G _NO exceeds 20, unsolidified, especially metal component portions at the bottom are scattered to the cylindrical portion due to centrifugal force.
It is not preferable because unevenness occurs in the thickness of the bottom portion, and the shielding effect is reduced because the metal component portion and the non-metal component portion are mixed in the bottom portion.

[0029]

(Equation 1)

N: number of rotations of the mold G _NO : centrifugal force expressed as a multiple of gravity D: inner diameter of the mold

Next, the second method will be described.

That is, a plurality of non-combustible wastes to be processed are melted sequentially in one melting furnace to form a plurality of laminated shields N.

That is, the shield 1 is manufactured in the same manner as described above using the melt of the first non-combustible waste, which is the lowest in harmful substances, which is substantially measured by the method described above.

Next, after transferring the remaining non-metal component portion of the melt of the first non-combustible waste to another container, the second lowest non-combustible waste of harmful substances is then transferred. Is melted in the same melting furnace as described above, and the melt is used to form a shield 2 in the same manner as described above.

Similarly, the remaining nonmetallic component portion of the second incombustible waste melt is transferred to the another container, and thereafter, a plurality of laminated shields N are formed while being sequentially melted.

[0036]

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

Reference numerals 1 and 2 denote shields 1 and 2, and reference numeral 3 denotes a nonmetallic component portion generated from a plurality of wastes by the present production.

In order to confirm the operation and effect of the present invention, two non-combustible wastes having different concentrations are used.
In the method shown in Table 1, a container of T ₁ = 200 mm was made of a conventional cement material as a comparative example, and 3.4 × 10 ⁴ Bq / g of radioactive waste was put into the container. Manufactured.

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

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

In the present embodiment, the lid 5 is made of a cast iron casting material having a thickness of 100 mm. However, the present invention is not limited to this. If there is, the same operation and effect as the present application are exerted.

In addition, no void filler such as a conventional resin is required, and the conventional bulk density of 1 to 2 g / cm ³ is reduced to ⁵ to 6 g / cm ^3.
The storage efficiency, transportation and storage have become much easier.

[0043]

[Table 1]

[0044]

According to the present invention, non-combustible waste containing radioactive harmful substances can be stored safely with a high storage efficiency, a reduced load on transportation, a small number of storage places, and no exposure.

[Brief description of the drawings]

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shield 2 Shield 3 Nonmetallic component 4 Drum can 5 Lid

Claims (2)

(57) [Claims] 1. A method for treating a plurality of N non-combustible wastes having different concentrations of heavy metals and radioactive substances contained therein, wherein the concentrations of the heavy metals and radioactive substances in the plurality of non-combustible wastes are roughly measured in advance. Then, after melting the plurality of N non-combustible wastes in a plurality of melting furnaces, a metal component melt in the melt of the non-combustible waste having the lowest concentration is cast into a centrifugal casting facility, and the melted non-combustible waste is centrifugally cast. After the passage and the formation of the cylindrical portion, the rotation of the mold is stopped or reduced to a rotation close to the stop, and a first shield formed by forming a bottom portion with an unsolidified metal component melt is formed. The metal component melt in the melt of the non-combustible waste having the second lowest concentration is cast into the first shield into the centrifugal casting facility having the first shield, and a certain time passes to form a cylindrical portion. After that, stop the rotation of the mold or To form a second shield formed by forming a bottom portion with a non-solidified metal component melt, and thereafter, by a similar method, stacking and forming a N-layer shield, and finally, the N-layer Wherein the non-metal component melt in the melt of the plurality of non-combustible wastes is charged into a shield made of a non-combustible waste. 2. In a method for treating a plurality of N non-combustible wastes having different concentrations of heavy metals and radioactive substances contained therein, the concentrations of the heavy metals and radioactive substances in the plurality of non-combustible wastes are roughly measured in advance. Then, after melting the non-combustible waste having the lowest concentration 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, a cylindrical portion is formed. Stop the rotation or drop it to a rotation close to the stop, create a first shield formed by forming a bottom with the unsolidified metal component melt, and transfer the non-metal component melt in the melt to another container. After transferring, after melting in the melting furnace,
Next, after melting the non-combustible waste having the second lowest concentration 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, allowing a certain time to elapse and forming a cylindrical portion, and then stopping or lowering the rotation of the mold to a rotation close to the stop, and forming a bottom portion with an unsolidified metal component melt. After the body is made and the non-metal component melt in the melt is transferred to the another container, thereafter, in the same manner, an N-layer shielding body is laminated and formed, and finally, the N-layer shield is formed. A method for solidifying non-combustible waste, wherein a non-metal component melt in the plurality of non-combustible waste melts transferred to the another container is charged into the shield.