JPH03181899A - Cement solidification of cinder ash of radioactive waste - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for solidifying radioactive waste incineration ash into cement, and particularly relates to a technique for quickly bringing radioactive waste incineration ash into a solidified state.

"Prior Art" As a method of reducing the volume of radioactive waste generated in nuclear couplant-related facilities, incineration of combustible materials and materials to be thermally decomposed is carried out, and
The incinerated ash produced in this case has concentrated radioactive materials, so one way to prevent the spread of radioactive materials is to fill drums with grout (cement mortar) and cement the incinerated ash with grout (cement mortar). It is planned that the solidified cement will be kept in a confined state through solidification treatment, and that it will be stored for a long period of time in a radioactive waste storage facility to prevent radioactive contamination.

[Problem to be solved by the invention] However, when forming a cement solidified body, radioactive waste incineration ash before solidification and radioactive waste incineration ash in the middle of solidification become radioactive during the cement solidification process. Since radiation is emitted by the phenomenon of material decay, it is necessary to adequately control the radiation dose of workers engaged in cement solidification work to ensure safety. However, it is not possible to transport the container containing the material to be solidified, and the material must be stored for a considerable period of time.

The present invention has been made in view of the above circumstances, and aims to shorten the time required for cement solidification and reduce the amount of radioactive materials accumulated during cement solidification.

"Means for Solving the Problem" In order to achieve the above object, in the present invention, radioactive waste incineration ash is stored in a storage container and solidified with cement. Radioactive waste incineration ash and hydraulic cement such as silica cement or alumina cement are filled and sealed, and the sealed storage container is rotated at high speed to apply centrifugal force to the mixed contents and bring them into a compressed state. In addition, the method for solidifying radioactive waste incineration ash into cement is characterized in that the content is heated by the heat of the hydration reaction of the cement to bring it into a solidified and hardened state.

"Function" When water, radioactive waste incineration ash, and hydraulic cement such as silica cement or alumina cement are stored in a storage container, a coagulation phenomenon occurs due to the so-called hydration of cement and the reaction between cement minerals and water. , followed by a hardening phenomenon.

In this case, if centrifugal force is applied to the mixed contents,
The mixed contents are compressed by centrifugal force. The heat from this compression and the heat from the hydration reaction of the cement promote the hydration reaction of the cement, shortening the solidification time, and causing the hardened cement parts, etc., which have a relatively large specific gravity, to close to the outside of the storage container. It becomes an accumulated state, solidification occurs from the outside, and becomes integrated with the storage container. In this case, by showing a tendency for the rotation of the fluid substance that accumulates in a relatively large amount in the center to be delayed, it is possible to shorten the solidification time by equalizing the temperature in the rotation direction, and to quickly solidify the outside. The purpose is to improve ease of handling.

"Example" Hereinafter, with reference to FIG. 1, an example of the method for solidifying radioactive waste incineration ash into cement according to the present invention will be described.

In the figure, symbol A is a storage container (for example, a drum), l is a turntable, 2 is a heat insulating case, 3 is a rotating shaft, 4 is a rotational drive source such as an electric motor, 5 and 6 are bearings, and 7 is a bolt, etc. It is a fastener.

The incineration ash produced by incinerating radioactive waste is in powder form containing other types of radioactive substances and metal oxides, etc.
Used as fine aggregate during cement solidification.

As shown in Fig. 1, a mixture is prepared by mixing so-called hydraulic cement such as silica cement and alumina cement with incinerated ash and, if necessary, an appropriate amount of fine aggregate such as S f OtSA Is Os and water. Alternatively, water and incineration ash are put and mixed into the storage container A, and cement or the like is also put into the storage container A to roughly knead it and then filled, and then the container is covered and sealed.

Next, the storage container A for incinerated ash, etc. is mounted on the turntable 1, and the heat insulating case 2 is placed on top of it, and the storage container A is fixed to the turntable 1 with the fastener 7, as shown in FIG. The condition shown is as follows.

By operating the rotational drive source 4, the turntable I is rotated at high speed and centrifugal force is applied to the contents of the storage container A.

Inside the storage container A, a so-called hydration effect of cement occurs due to the reaction between the cement mineral and water, causing a setting phenomenon, and a hardening phenomenon subsequently occurs.

In this case, when centrifugal force is applied to the mixed contents of storage container A, a phenomenon occurs in which substances with a relatively higher specific gravity than water or fluids are accumulated on the outside due to the centrifugal force. The substance, ie, most of the mixed contents, is compressed by centrifugal force. It is expected that the heat generated by this compression and the heat generated during the hydration reaction of the cement will accelerate the hydration reaction of the cement and shorten the solidification time. By covering with the heat insulating case 2, heat radiation into the atmosphere is reduced.

In addition, the solidification tank As shown in FIG. 2, it is considered that the particles are accumulated near the outer periphery, and as the solidification tank X becomes solidified, the particles adhere to the inner circumferential surface of the storage container A and become integrated.

In this case, the part with fluidity remaining in the center of storage container A, that is, the fluid phase Y, shows a tendency to rotate later than the solidification tank X based on its fluidity. A convection phenomenon occurs in a portion having a rotation direction, which equalizes the temperature in the rotation direction, and generates heat due to a deviation in the rotation direction. Therefore, the cement hardens quickly.

On the other hand, as shown in Fig. 2, a solidification tank X is gradually formed inside the storage container A, which is integrated with the wall of the storage container A. Even when the center of the interior of storage container A is brought to a solidified state by the hydration reaction of cement, it is difficult to cause uneven solidification or eccentricity, so transport or storage in storage during the solidification process is not recommended. This will improve the ease of handling through remote control.

"Effects of the Invention" As explained above, the method for solidifying radioactive waste incineration ash into cement according to the present invention, when storing incineration ash in a storage container and solidifying it with cement, water, incineration ash, hydraulic cement, etc. Since it is stored in a sealed state and solidified while rotating at high speed and applying centrifugal force, it is caused by heat generation due to compression, heat of hydration reaction of cement, and misalignment of the direction of rotation between the solidification tank and the fluid phase during solidification. By utilizing heat generation or the like, the solidification time can be shortened by quickly leading to a solidification and hardening state.

In addition, since the solidification tank is located outside the fluid phase and becomes integrated with the storage container more quickly, it becomes easier to handle for transportation and storage in a short time, and the radioactive materials for cement solidification are stored. This has effects such as being able to reduce the amount.

[Brief explanation of drawings]

Fig. 1 is a partially sectional front view showing an embodiment of the cement solidification method for radioactive waste incineration ash according to the present invention, and Fig. 2 is a chain line in Fig. 1 showing a state in the middle of cement solidification. It is a line arrow view. A...Storage container (drum 1...Turntable, 2...Insulating case, 3...Rotating shaft, 4...Rotating drive source, 5...bearing, 6...bearing, 7...fastener, X...solidification tank, Y...fluid phase.) ,

Claims (1)

[Claims] A storage container is filled with water, radioactive waste incineration ash, and hydraulic cement such as silica cement or alumina cement and sealed, and the sealed storage container is rotated at high speed to apply centrifugal force to the mixed contents. 1. A method for solidifying radioactive waste incineration ash into cement, the method comprising: applying heat to compress the contents, and heating the contents using the heat of hydration reaction of the cement to bring the contents into a solidified and hardened state.