JPS62121400A - Method of solidifying and processing radioactive waste incinerating ash - 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 OBJECTS OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a method for solidifying radioactive waste incineration ash into a form suitable for final storage and land disposal.

[Prior art] For example, with the operation of nuclear power plants and lighting conditions, combustible [raw solid wastes] with low levels of radioactivity, such as polyethylene, paper rags, yellow cloth, work clothes, etc. or occur. Traditionally, these wastes were compressed and stored in drums, but as the amount of waste generated has increased recently, it has become necessary to incinerate and reduce the volume of these wastes in order to make effective use of drum storage space. It is. The quenched ash, which has low levels of radioactivity, is stored in drums.

Methods for final storage of waste incineration ash until its capacity is reduced to a safe level and further disposal on land include plastic solidification, microwave melting, or solidification by elevated heating. A law has been proposed.

In the plastic solidification method, for example, incineration ash and a solidifying agent (unsaturated polyester resin) are mixed and stirred and placed in a ram can, followed by pouring a hardening agent and stirring with rotation 97.
There is a way to solidify it. This method has the disadvantage that the presence of unburned carbon and moisture in the burnt IJl ash inhibits the hardening of the plastic, so there is a limit to the blending ratio and the degree of volume reduction cannot be increased. This method also poses handling problems, such as taking out the incinerated ash from drums and transporting it, since it is a powder.

The solidification method by melting is a method in which the incinerated ash is heated to a high temperature by applying microwaves or high-frequency induction heating to melt and solidify the ash. Although this method is superior in terms of the degree of volume reduction and the physical properties of the solidified material,
Similarly, handling is difficult and the cost is high.

As other methods, it is necessary to use a solidification treatment method using cement.In the conventional technology, the kneading of incinerated ash and solidifying agent is performed by out-drum mixing, so that the incinerated ash is not scattered when the mixer is driven. , Migi! New problems arise in addition to handling problems, such as the disposal of secondary historical waste such as waste water from the incineration ash (which is also radioactive).Additionally, soluble salts in the incineration ash, lead, zinc, etc. This may cause the solidified cement to become brittle or cause poor setting of the cement.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the problems that have hitherto been associated with the solidification treatment of ash produced by incinerating waste with low levels of oxidation, and to provide a method that is easy to handle and can be incinerated. The object of the present invention is to provide a processing method that can produce a solidified material that is easy to remove at a low cost without worrying about scattering of ash, washing, or processing of wastewater.

Summary of the invention [Means for solving the problem] The method for solidifying radioactive waste incineration ash of the present invention includes injecting cement mortar or paste into a container containing incineration ash of radioactive waste, The contents 1'/J3 are granulated by applying rotation and/or vibration to the container, and once the resulting granules have solidified, cement mortar or paste is injected into the container. Alternatively, the paste is filled airtightly into the gaps of the solidified granules and solidified.

In other words, the treatment method of the present invention includes a first step in which incineration ash is granulated and solidified using cement mortar or paste, and a second step in which the solidified granules are roughly filled with cement mortar or paste and solidified as a whole. The process consists of two steps.

The purpose of the cement mortar or paste injected in the first step is to prevent the incineration ash from scattering, granulate it, and solidify it to a certain level of strength. Depending on the degree of pollution, there is no incineration ash that remains without being granulated, and on the other hand, the free ratio 11 water is appropriately selected within the range that does not occur during actual purchase. Semen 1~ is
Any material can be used, including ordinary boltant cement. It is possible that other hydraulic substances may be used in combination.

The cement 1 to mortar or paste used in the second step can also be prepared using any cement. In order to reduce heat generation and increase the strength of the solidified material, it is necessary to add an appropriate amount of aggregate such as sand. Further, in order to improve fluidity, it is preferable to add a fluidizing agent. As a fluidizing agent, water reducing agents that are added and used in the construction of concrete and mortar in civil engineering or construction work, especially when pouring grout (A), are effective.For optimal usage conditions, follow the instructions for each water reducing agent. ,
It should be easy to decide.

Injecting the cement mortar or paste in the first step is usually done from the top of the container, taking the necessary time to avoid scattering incinerated ash. The injection amount is suitably in the range of 0.6 to 1.6 by volume based on the incinerated ash. If there is not enough space above the container to inject the cement mortar or paste, apply vibrations in advance to lower the surface of the incinerated ash.
It is also effective to inject while giving one more movement.

By rotating and/or vibrating the container after or preferably simultaneously with the injection of the cement mortar or paste 1~, the incineration ash is granulated into homogeneous lumps of about 5 to 100 cubes in diameter. Rotation is 45 degrees with respect to the vertical axis of the container.
~90' tilt (preferably done with a rotational speed of 5
Slow rates on the order of ~30 ppm are suitable.

When applying vibration, use a vibrator with a vibration rating of 3.000 to 7. ○OO
The appropriate amplitude for v, p, m, is 0.5 to 3.0 m.

Of course, it is preferable to use rotation and agitation in combination because granulation is promoted.

Since the granulated ash is brittle and crumbles immediately after it is formed, it is left to stand for at least 24 hours to allow it to solidify to some extent before proceeding to the second step.

Injecting the cement mortar or paste in the second step can be done from the top of the container, or by inserting a pipe toward the bottom of the container, or by preparing a pipe in advance and using it to pour the cement mortar or paste into the bottom of the container. Alternatively, it is also preferable to inject from the inside. Applying vibration to the container is a process that is performed during or subsequent to injection, filling the spaces between the solidified granules with cement mortar or paste, and expelling air bubbles to prevent the formation of cavities. It is advantageous to choose conditions that generate fewer bubbles from the beginning, as this will shorten the time required for vibration and ensure a reliable effect.

To apply vibration, a suitable vibration generating means such as a vibration motor or an air pipe rake is used. In order to dispose of incinerated ash from Okawa, it is necessary to prepare a special shaking table and vibrate the entire container, but if the target is a small amount, vibration can be applied to the bottom or side wall of the container. It is also possible to apply vibration by bringing the means into contact with each other.

Since the vibrations in the second process do not have to worry about the scattering of incinerated ash, a wide range of vibration frequency and amplitude can be selected. Generally, the frequency is 3,000 to 7°000v, p, m,
, the appropriate amplitude is 0.5 to 3.0 mm.

[Action] Cement mortar or paste (1, rotation and (
or) It is mixed with the incineration ash by vibration and forms granules by its action as bangu. As a result,
Incineration ash is easy to handle due to its scattering properties (tentative).

If this granular material is left to stand, it will gain some strength as the cement solidifies, so it is possible to roughly fill the periphery with element mortar or paste under vibration and solidify it into one piece. In this way, a form suitable for final storage and land disposal of tj'i radioactive waste incineration ash is provided.

(Example) ], the volume of simulated incineration ash was 30. Cement 1 to mortar was poured into a 50.11 drum filled with Q in a volume ratio of 1/2 to the incinerated ash.

Cement mortar has the following composition.

“Denka Tascon” Premix 84.7 Juyobesui
15.3
lno (the above premix is from cemen 1 to 36.6
It has a composition by weight of 41.2% sand, 4.5% "Denka Tascon" and 17.7% water. ) Seal the drum, tilt its axis 90' to the vertical, and rotate at a rotation speed of 1 or
, P, M, and C filter for 30 minutes, in each case, granules with combined incineration ash were obtained. The particle size ranged from 10 to 30 m.

2. Into a 50 g drum containing the same simulated incinerated ash with a volume of 300 Å, the same cement mortar as above was poured into a drum with a volume ratio of 2/3 to the incinerated ash, and after sealing, the axis was made vertical. Vibrate using a vibrator at k6,000v
, p-ml, and vibration with an amplitude of 1.0 mm was applied for 30 minutes. Although the particle shape and particle size were more irregular than in 1., similar granules were obtained.

3. The granules from 1 and 2 above were left in the drum at room temperature for 2 days to wait for the granules to solidify.

Then, using a vibrator, the frequency was 6,000 + V, p
, m,, The same cement mortar as above was injected while vibrating with an amplitude of 1.0#.

It was observed that there was no disintegration of the granules and the mortar into Cement 1 filled their interstices well.

4. After pouring, the drum was left at room temperature for one month and then cut to vertically divide the solidified product. Observation of the cross section confirmed that the granules were stably fixed in the cement mortar with good airtightness.

The compressive strength of the solidified body was 150 K5j/cni or more.

Effects of the invention Incineration of radioactive waste according to the solidification treatment method of the present invention]
If the ash is solidified with cement, there will be no handling problems such as scattering of the incinerated ash, and the waste incinerated ash stored in a container such as a drum can can be solidified as is. Since there is no need for an out-drum mixer or an in-drum mixing rotary blade, there is no equipment cost and there are no problems such as processing of sweat water.

In the solidified product obtained, the cement mortar or paste sufficiently fills the gaps between the granules, there are virtually no harmful cavities, and the strength is sufficient for subsequent transportation and storage.

In addition, since cement 1-based solidifying agents are available at low cost,
The cost of solidified material is also low.

In this way, safe storage and disposal of radioactive waste incineration ash is achieved simply and at low cost.

Claims (1)

[Claims] Cement mortar or paste is injected into a container containing radioactive waste incineration ash, the contents are granulated by rotating and/or vibrating the container, and the resulting granules are solidified and reused in cement mortar. Alternatively, a method for solidifying radioactive waste incineration ash characterized by injecting paste and applying vibration to a container to fill the gaps between solidified granules with mortar or paste and solidify it.