JPH09101398A - Method and device for treating radioactive waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solidify radioactive wastes stably, obtain the stability of them for a long term, improve the integrity of it and reduce the treatment time and cost by soaking the radioactive wastes in an alkaline solution before the solidifying treatment of them or carrying out a heating pretreatment after the soaking of them. SOLUTION: The concentration of cement-saturated water is regulated by adding an alkaline metal element to it so that the composition will be that of water in cement and in the disposal environment. In this solution, ion exchange resin is soaked beforehand (S1). Moreover, though the heating temperature to accelerate the reaction speed may be determined by the time permitted by the time needed for the ion exchange reaction and treatment processes because much time is taken for the exchange reaction, it is heated over 70 deg.C in order to shorten the treatment time (S2). In a boiling state, especially, 30 minutes are sufficient for the treatment time. Notably, the alkaline metal element has only to be added to the cement-saturated water so that the concentration of the treatment liquid will be 0.4mol/l in the total element concentration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for treating medium to low level solid radioactive waste generated in a radioactive material handling facility such as a nuclear power plant as a cement solidified body, and particularly to radioactive waste. TECHNICAL FIELD The present invention relates to a radioactive waste treatment method and apparatus capable of accommodating materials in a compact manner and easily producing a cement-solidified product excellent in stability and durability over a long period of time.

[0002]

2. Description of the Related Art Since radioactive wastes are generated in radioactive material handling facilities such as nuclear power plants, various treatments are performed for reducing and stabilizing the radioactive wastes.

Among these wastes, combustible wastes such as paper and waste are incinerated in a dedicated incinerator to reduce the volume. Further, as the solidifying method, a cement solidifying method of solidifying incinerated ash with cement and a plastic solidifying method of solidifying with plastic have been put into practical use, and are adopted in some nuclear power plants.

Further, organic ion exchange resins are used for purification of liquid waste generated in radioactive substance handling facilities and purification of water used in the facilities. When the ion exchange capacity of such an ion exchange resin decreases, it is regenerated by a chemical solution and repeatedly used.

However, since the ion exchange capacity deteriorates little by little when it is regenerated, it is finally discarded as a waste. A cement solidification method of solidifying the waste resin as it is and a plastic solidification method of solidifying by mixing with the plastic after being dried have been put into practical use. Also, a method of temporarily storing without making a solidified body has been put into practical use,
This method is a method of drying a waste resin, mixing a small amount of a binder, molding the mixture into pellets, and storing the intermediate storage until final solidification, which is called a pelletization method.

On the other hand, although the above-mentioned solidification method is a technique capable of stabilizing waste, it has the following problems in order to achieve further long-term stability after treatment.

First, regarding incinerated ash, in many cases, in addition to combustible waste, amphoteric metals such as aluminum are contained in the waste to be incinerated. When the incinerated ash is hardened with cement, these amphoteric metals are removed. Reacts with alkaline components in cement, especially calcium hydroxide, to generate hydrogen gas. Since the alkaline component is generated by the hydration reaction of cement,
Hydrogen gas accumulates in the solidified body while the cement sets. Therefore, expansion of the solidified body by the generated hydrogen gas,
Cracks and voids may occur.

When the incineration ash is solidified with plastic, the above reaction does not occur at the time of solidification, but a problem may occur when it is stored in a disposal facility. That is, since the disposal facility is a concrete structure and cement is a basic component, an alkaline component is present in the structural material.
When water enters this disposal facility, the water is in equilibrium with the cement components, enters the solidified plastic, and reacts with the amphoteric metals in the incinerated ash to generate hydrogen gas. The generation of hydrogen gas in the disposal facility may affect the soundness of the disposal facility.

Due to the above problems, as a method for preventing gas generation, a lithium compound is added to the cement material (a typical example is lithium nitrate), and an aluminate is added to the surface of the amphoteric metal in the incinerated ash. A method of forming a lithium film to suppress hydrogen gas generation has been proposed (example:
JP-A-6-102397).

According to this method, it is recognized that the reaction between the alkaline component in the cement and the amphoteric metal in the incinerated ash, especially aluminum, can be prevented by the lithium aluminate film, and the generation of hydrogen gas can be reduced.

However, since the film is formed only on the aluminum surface layer, the aluminum remains without reacting inside the film. Therefore, to ensure that gassing is reduced or eliminated over the long term,
The long-term stability of the coating must be demonstrated.

Further, a method of reacting the amphoteric metal in the incinerated ash before solidifying has been proposed, and a method of immersing the incinerated ash in an alkaline or acidic solution has also been proposed. (Example:
JP-A-2-62200, JP-A-4-287000, etc.). However, this method has a problem that the processing time is extremely long, which is one day or more, and is not suitable for practical use.

On the other hand, the used ion exchange resin has already been solidified at the nuclear power plant. For example, in the case of solidifying the granular ion exchange resin, the solidifying amount of the resin per 200 liter drum can is 25 kg to 30 kg on a dry resin weight basis.

The limitation of the solidification amount of the resin is to avoid the problem that the resin expands when the solidified resin product is disposed and the solidified product is broken. That is, when cement and water are mixed to harden the cement, the water mixed with the cement becomes alkaline because of the alkaline component generated by the hydration reaction. When the ion exchange resin is solidified, the ion exchange resin takes in the alkali component by ion exchange.

The composition of free water in the ion exchange resin tends to be the same as that of water in the cement. Due to these two reactions, the water possessed by the ion exchange resin is released into the cement, and the cement is hardened in a state where the ion exchange resin contracts.

However, when the groundwater enters after the disposal, the groundwater and the ion exchange resin come into contact with each other and the ion exchange resin swells. If the amount of ion exchange resin in the cement is less than this limit value, there is no problem because the strength of the cement is higher than the swelling pressure of the ion exchange resin.

However, when the amount of the ion exchange resin added is more than the limit value, the swelling pressure of the ion exchange resin becomes large, which causes cracks in the solidified body. Therefore, there is a problem that the amount of solidified cement of the ion exchange resin cannot be increased in order to suppress the amount of solidified cement.

In order to solve this problem, a method has been proposed in which the cement itself is strengthened so that it can withstand the swelling pressure of the ion exchange resin. Specifically, when a resin is swollen, a tensile stress is applied to the cement, but a method of putting a substance having a very high tensile strength, such as carbon fiber, into the cement so as to withstand this stress has been proposed (example : JP-A-4-194794). However, since this method disposes a solidified body having a potentially high internal pressure in a state where expansion is suppressed by carbon fiber, it is necessary to ensure its safety for a long time, and a fiber having high tensile strength is generally used. High price can result in expensive waste.

In order to prevent the ion exchange resin from swelling or shrinking, the ion exchange resin may be dipped in an aqueous solution of an alkali metal (eg, JP-A-61-86692) or an alkaline earth such as calcium hydroxide. Immersion in a saturated solution of a hydroxide of a group element (eg, JP-A-63-2612)
No. 00) is also proposed. However, the water quality condition around the ion-exchange resin in the disposed solidified product is a condition in which the soluble component in the hardened cement is dissolved and equilibrated.

Table 1 shows an example of the soluble components of the following hardened cement. As shown in Table 1, in addition to Ca, which is a main component and has a very low solubility, cement contains a small amount of alkali metal elements such as Na, K, and Li that have a very high solubility. .

[0021]

[Table 1]

Therefore, even when the ion-exchange resin is simply pretreated, it is immersed in water having an alkali metal component to cause a reaction, but under the environmental conditions of disposal, an ion-exchange reaction occurs with calcium ions generated from calcium hydroxide. The volume of resin varies.

Further, even if the ion exchange resin is reacted with saturated water of hydroxide of alkaline earth element, the composition of water in the cement solidified body or the composition of water in the disposal environment is not simulated. Specifically, the cement contains alkali metal components as shown in Table 1 above, and the trace elements of these alkali metal components are extremely small, such as in the gaps in the cement or in the disposal facility. It dissolves in the water that fills the voids and exists at relatively high temperatures. Therefore, when a large amount of the ion exchange resin is solidified in one drum, an ion exchange reaction with the ion exchange resin occurs particularly in the long term,
The resin has a problem of swelling and shrinking.

[0024]

In the prior art, when the radioactive waste is solidified with cement, the reaction of the metal components contained in the cement affects the stability and soundness, and the treatment time. However, there are problems such as a long period of time and an increase in cost.

The present invention has been made in view of the above circumstances, and is capable of stably immobilizing radioactive waste and also achieving long-term stability, further improving soundness, shortening the treatment time, and reducing the treatment time. An object of the present invention is to provide a method for treating radioactive waste, which can be cost-effective, and a treatment apparatus for carrying out the method.

[0026]

[Means for Solving the Problems] Among the wastes, incinerated ash contains amphoteric metals such as aluminum and zinc. In the case of aluminum, for example, it reacts with alkali metals in an alkaline atmosphere to generate hydrogen. Is known to do.

[0027]

(Equation 1)

This reaction proceeds faster as the alkalinity is higher, but the reaction time is very slow at room temperature and is 15 μm /
About a day. Further, the particle size of aluminum in the incinerated ash is about 50 μm, and therefore it takes several days at room temperature to completely react.

On the other hand, when this reaction is carried out at a high temperature, the reaction time is shortened, and the aluminum contained in the incinerated ash reacts completely. Li, Na, K, Cs and other alkali metals, Mg, and C react with aluminum and the like.
It is a hydroxide of an alkaline earth metal compound such as a.

It is known that the waste disposal facility is constructed of cement material, and the main component of cement after hardening is calcium hydroxide. Therefore, when the above-mentioned chemicals or hardened products of cement are dissolved or immersed in water to reach an equilibrium state and incineration ash is put into this to heat, the reaction as shown above proceeds and aluminum is stabilized. .

The heating temperature can be determined depending on the reaction of aluminum and the time allowed for the treatment step, but the present inventors have confirmed that heating to 70 ° C. or higher is particularly required for shortening the treatment time. . Particularly, in the boiling state, the treatment time of 30 minutes is sufficient.

It is generally considered that the content of amphoteric metals such as aluminum in the incinerated ash is about 2% of the incinerated ash. Therefore, the amount necessary for the alkaline reaction of the amphoteric metal in the incinerated ash is 0.08 mol or more, when treated with an alkali metal hydroxide, with respect to 100 g of the incinerated ash (containing 2 g of amphoteric metal such as aluminum). With respect to the earth metal hydroxide, if added at a ratio of 0.12 mol or more, the amphoteric metal in the incinerated ash can be treated before being solidified with cement.

Generally, a radioactive substance handling facility is provided with a concentrator for reducing the volume of waste liquid generated in the facility and suppressing the amount of waste generated. As a result of studying the heat treatment of the incineration ash with this concentrator, the present inventors have confirmed that the treatment can be performed without problems. As described above, the present invention, which can be processed by the existing equipment, leads to a reduction in costs related to waste disposal.

Regarding the treatment of the ion exchange resin,
The swelling and shrinkage must be suppressed for a long period of time to stabilize the solidified waste and the treatment facility. For this purpose, it is necessary to prevent the swelling and shrinkage of the ion exchange resin even when it comes into contact with the water in the cement solidified body or the water under the disposal environment, instead of the pretreatment of the ion exchange resin which has been studied conventionally.

Therefore, in the present invention, the alkali metal element is added to the saturated water of cement to adjust the concentration so that the composition of the water in the cement or the water in the disposal environment is adjusted, and the ion exchange resin is dipped in this solution. It is desirable to keep it. In other words, this solution has exactly the same composition as the components in the pretreated ion-exchange resin, even when water in equilibrium with the components of the facility structure flows in during the hydration reaction of cement or after disposal. No expansion or contraction occurs. Moreover, since this exchange reaction takes time, it is effective to heat it in order to increase the reaction rate.

The heating temperature can be determined depending on the time of the ion exchange reaction and the time allowed for the treatment step, but the present inventors have confirmed that heating at 70 ° C. or higher is required to shorten the treatment time. . In particular, in the boiling state, it was found that the treatment time of 30 minutes was sufficient.

The alkali metal element added to the cement-saturated water is such that the concentration of the treatment liquid is 0.4 mol in terms of the total element concentration.
It was confirmed that / L was good. Also, because of the water contained in the ion exchange resin when using this immersion liquid,
Since the concentration of the pretreatment liquid may fluctuate, it was confirmed that it is effective to dehydrate the ion exchange resin so that the water content in the ion exchange resin is constant before the treatment.

Generally, a facility for handling radioactive substances is provided with a concentrator for reducing the volume of waste liquid generated in the facility and suppressing the amount of waste generated. As a result of studying the heat treatment of the incineration ash with this concentrator, the present inventors have confirmed that the treatment can be performed without problems. If a method that can be treated with existing facilities can be implemented in this way, it will lead to a reduction in costs related to waste treatment.

The present invention has been made based on the above findings, and the invention of claim 1 solidifies the powdery, granular or other solid radioactive waste generated in a radioactive material handling facility with cement. In the method of treating radioactive waste,
Before the solidification treatment, the radioactive waste is immersed in an alkaline solution, or a pretreatment of heating is performed after the immersion.

According to the invention of claim 2, in the method for treating radioactive waste according to claim 1, as radioactive waste to be treated, incineration ash obtained by incineration of combustible waste generated at a radioactive material handling facility, Alternatively, the feature is that the ion exchange resin used for fluid purification at the same facility is applied.

According to the invention of claim 3, in the method for treating radioactive waste according to claim 2, when the radioactive waste to be treated is incinerated ash, the incineration is carried out as an alkaline solution for immersion in the incinerated ash. Addition of 0.08 mol or more of alkali metal hydroxide or 0.12 mol or more of alkaline earth metal hydroxide to 2 g of amphoteric metal contained in ash, or contacting water with a hardened cement product It is characterized in that cement components are dissolved and saturated to be used.

According to the invention of claim 4, in the method for treating radioactive waste according to claim 2 or 3, when the radioactive waste to be treated is incinerated ash, the incinerated ash is heated after being immersed in an alkaline solution. The condition is that the heating temperature is 70 ° C. or higher and the heating time is 4 hours or longer, or the immersion liquid is boiled for 30 minutes or longer.

According to a fifth aspect of the present invention, in the method for treating radioactive waste according to the second aspect, the incineration ash or the ion exchange resin, which is the radioactive waste to be treated, is immersed in an alkaline solution and the heat treatment is performed. It is characterized in that it is performed by a waste liquid concentrating device installed in a handling facility.

The invention of claim 6 is the method for treating radioactive waste according to claim 2, wherein when the radioactive waste to be treated is an ion exchange resin, water is brought into contact with the hardened cement product as an alkaline solution. It is characterized in that a solution prepared by mixing an alkali metal hydroxide with a liquid saturated with a soluble component of cement in water is used.

According to the invention of claim 7, in the method of treating radioactive waste according to claim 2, when the radioactive waste to be treated is an ion exchange resin, the ion exchange resin is immersed in an alkaline solution and is not heated. For 12 hours or more, or after the ion exchange resin is immersed in an alkaline solution, the heating condition is a heating temperature of 70 ° C. or more for a heating time of 4 hours or more or the immersion liquid is boiled for 30 minutes or more, and the alkaline solution As a solution in which one or more kinds of alkali metals selected from Li, K, and Na are added to a liquid saturated with the dissolved components of cement, the concentration of the immersion liquid after addition is 0.4 mol / It is characterized in that it is set to be L or more.

According to the eighth aspect of the present invention, in the method for treating radioactive waste according to the second aspect, when the radioactive waste to be treated is an ion exchange resin, water contained in the ion exchange resin is removed. It is characterized in that it is subsequently immersed in an alkaline solution.

The invention according to claim 9 is the method for treating radioactive waste according to any one of claims 1 to 8, wherein as radioactive waste to be treated, in addition to incineration ash or ion exchange resin, used waste is used. A feature is that pelletized waste obtained by drying and solidifying the ion exchange resin is added, and two or more kinds of them are collectively pretreated and solidified with cement.

According to a tenth aspect of the invention, there is provided a dipping tank for dipping radioactive waste containing an alkaline solution, a heating tank for heating the dipping material, and a solidifying device for cement-solidifying the substance after heating. It is characterized by having.

According to the present invention as described above, stable solidification of waste such as incinerated ash and ion exchange resin is performed by reacting the waste with an alkali metal or alkaline earth metal in an alkaline solution. It is possible to enhance the reactivity and shorten the treatment time by heating the material into a product and heating it during the reaction.

[0050]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a flow chart showing an outline of a method for treating radioactive waste. As shown in FIG. 1, in the present invention, as radioactive waste, incineration ash, used ion-exchange resin, and pellet-shaped waste (hereinafter referred to as resin pellets) formed by drying used ion-exchange resin are targeted. One of the wastes is dipped in an alkaline solution and treated for a certain period of time (step S1). Further, heat concentration is performed for the purpose of promoting the effect of the pretreatment and shortening the pretreatment time (step S2).

This pretreatment is carried out in order to solve the problems in fixing the incinerated ash and the used resin with cement as described above. If the facility that handles radioactive waste has an existing concentrator for concentrating radioactive liquid waste, this may be used for pretreatment.

The radioactive waste subjected to the pretreatment is dehydrated (step S3) and then kneaded with cement and kneading water by a kneader (step S4). At this time, kneading in advance (step S
4 ') The pretreated waste may be added to the cement paste and kneaded. This mixture is fixed in a container such as a 200-liter drum, after which it is fixed (step S5).

FIG. 2 is a graph showing the results of measuring the rate of Al corrosion in an alkaline solution in which the pretreatment conditions for incinerated ash were determined by temperature, and FIG. 3 is the pretreatment conditions for the used ion exchange resin by temperature. It is a graph which shows the time-dependent change measurement result of the obtained resin pellet diameter, FIG. 4 is a graph which shows the compression strength time-dependent change of the produced incineration ash fixed body, and FIG.
It is a graph which shows the compressive strength time change of the produced used ion-exchange resin solidified body. Further, Table 2 at the end shows Examples and Comparative Examples.

The pretreatment condition of the incineration ash was selected from the corrosion rate of aluminum in the saturated dissolved water of the cement component. The particle size of aluminum in the incinerated ash is about 50 μm
Therefore, the temperature and time required for 50 μm corrosion are shown in FIG.
It was selected from the results.

The resin was obtained from the rate of change in diameter of saturated cement water of the cement component whose Na temperature was adjusted to 0.4 mol / L shown in FIG. From this result, the temperature and time until the size of the ion exchange resin became constant were selected.

As described above, according to the ion-exchange resin or the resin pellet which has been subjected to the alkali immersion and the heat concentration treatment, a good solidified product is obtained which does not expand in the cement, as shown in the following examples.

Example 1 Incinerated ash was put in a 1N-NaOH solution, pretreated at a temperature of 70 to 90 ° C. for 4 hours and then dehydrated, and blast furnace cement type B: water: incinerated ash = 100: 75:
A kneaded mixture of 30 (parts by weight) was obtained to obtain a solidified product.

No cracks were observed in the solidified body, which was good. As shown in FIG. 4, the strength of the solidified body cured in water is 5.0 MPa after 7 days of age and 9.0 MPa after 28 days of age.
Was obtained, which was well above the disposal standard of 1.5 MPa.

Example 2 About 100 g of incinerated ash Na
The incinerated ash was placed in the solution so that the OH ratio was 0.08 mol, pretreated under boiling conditions for 30 minutes, dehydrated, and then kneaded with cement in the same composition as described above.

The solidified product obtained was good without cracks and the like, and the compressive strength of the solidified product was well above the reference value as shown in FIG.

Example 3 Incinerated ash was put in saturated solution of cement components, pretreated at a temperature of 70 to 90 ° C. for 4 hours, dehydrated, and kneaded with cement in the same composition as described above.

The obtained solidified body was good with no cracks and the like, and as shown in FIG. 4, the compressive strength of the solidified body was well above the reference value.

[Example 4] The incinerated ash was put in a saturated solution of cement components, pretreated for 30 minutes under boiling conditions, dehydrated, and kneaded with cement in the same composition as described above.

The obtained solidified body was good without cracks and the like, and as shown in FIG. 4, the compressive strength of the solidified body was well above the standard value.

Example 5 The incinerated ash was put in 1N-NaOH, pretreated at room temperature (20 ° C.) for 7 days, dehydrated, and then kneaded with cement in the same composition as described above.

The solidified product obtained was good without cracks and the like, and as shown in FIG. 4, the compressive strength of the solidified product was well above the standard value.

Example 6 Incinerated ash was put in saturated dissolved water of cement components, pretreated at room temperature (20 ° C.) for 7 days, dehydrated, and kneaded with cement in the same composition as described above.

The solidified product obtained was good without cracks and the like, and as shown in FIG. 4, the compressive strength of the solidified product was well above the reference value.

Example 7 As a simulated used ion exchange resin, a granular ion exchange resin manufactured by Mitsubishi Kasei Co., Ltd. was used by adjusting the cation: anion = 2: 1 (weight ratio). This ion exchange resin was adjusted to a Na concentration of 0.
It was put into saturated dissolved water of cement component adjusted to 4 mol / L, pretreated at room temperature (20 ° C.) for 12 hours, and then dehydrated.

At this time, the water content of the ion exchange resin is about 6
It was 0 wt%. This was kneaded with a blend of blast furnace cement type B: water: ion exchange resin = 100: 40: 60 (parts by weight) to obtain a solidified body. The solidified product obtained was good without any cracks or the like. As shown in FIG. 5, the strength of the solidified body cured in water was 8.9MP after 7 days of age.
a, a characteristic of 14 MPa was obtained after 28 days of material age, well exceeding the disposal standard of 1.5 MPa.

Example 8 An ion exchange resin having the same specifications as in Example 7 was charged with saturated dissolved water of a cement component whose K concentration was adjusted to 0.4 mol / L using KOH, and the temperature was kept at room temperature (20
It was dehydrated after pretreatment for 12 hours at a temperature of (.degree. C.). This was kneaded with cement in the same composition as above.

The obtained solidified body was good with no cracks and the like, and as shown in FIG. 5, the compressive strength of the solidified body was well above the reference value.

Example 9 An ion exchange resin having the same specifications as described above was placed in saturated solution of cement components, the Li concentration of which was adjusted to 0.4 mol / L with LiOH, at room temperature (20
It was dehydrated after pretreatment for 12 hours at a temperature of (.degree. C.). This was kneaded with cement in the same composition as above.

The solidified product obtained was good without cracks and the like, and as shown in FIG. 5, the compressive strength of the solidified product was well above the standard value.

[Example 10] An ion exchange resin having the same specifications as described above was used to adjust the Na concentration to 0.4 mol / L using NaOH.
Add saturated dissolved water of the cement component adjusted to
It was pretreated at 0 ° C. for 4 hours and then dehydrated. This was kneaded with cement in the same composition as above.

The obtained solidified body was good without cracks and the like, and as shown in FIG. 5, the compressive strength of the solidified body was well above the reference value.

[Example 11] An ion exchange resin having the same specifications as described above was placed in saturated dissolved water of a cement component whose Na concentration was adjusted to 0.4 mol / L, pretreated for 30 minutes under boiling conditions, and then dehydrated. . This was kneaded with cement in the same composition as above.

The solidified product obtained was good without cracks and the like, and as shown in FIG. 5, the compressive strength of the solidified product was well above the reference value.

Example 12 A resin pellet made of an ion exchange resin having the same specifications as described above was used, and the Na concentration was 0.4 m.
Put in saturated water of cement component adjusted to ol / L,
It was pretreated at room temperature (20 ° C.) for 12 hours and then dehydrated. Blast furnace cement type B: water: ion exchange resin =
The mixture was kneaded at a mixing ratio of 100: 40: 64 (parts by weight) to obtain a solidified body.

The solidified product obtained was good without any cracks or the like. As shown in FIG. 5, the strength of the solidified body cured in water is 2.5 MPa after 7 days of age and 4.5 MPa after 28 days of age, which is a disposal standard of 1.5.
It was well above MPa.

[Example 13] A waste obtained by mixing incineration ash having the same specifications as described above and an ion exchange resin in a weight ratio of 1: 1 was used.
It was placed in saturated dissolved water of cement component whose a concentration was adjusted to 0.4 mol / L, pretreated for 30 minutes under boiling conditions, and then dehydrated. Blast furnace cement type B: water: (mixture of incineration ash and ion exchange resin) = 100: 40: 64 (parts by weight)
The mixture was kneaded to obtain a solidified product.

No cracks were observed in the obtained solidified product, which was good. The strength of the solidified body cured in water was 6.5 MPa after 7 days of age and 11.3 MPa after 28 days of age, which was sufficiently higher than the disposal standard of 1.5 MPa.

[Comparative Example 1] The incinerated ash was not pretreated, but was mixed with a blend of blast furnace cement type B: water: incinerated ash = 100: 75: 30 (parts by weight).

In the obtained solidified product, expansion thought to be due to the influence of the generated hydrogen gas was observed throughout and cracks were generated.

Comparative Example 2 Incinerated ash was put in 1N-NaOH, pretreated at room temperature (20 ° C.) for 30 minutes, dehydrated, and kneaded in the same composition as in Comparative Example 1 to obtain a solidified product. It was

As a result, since the pretreatment time was insufficient, the obtained solidified body had cracks due to expansion.

[Comparative Example 3] Incinerated ash was put into saturated solution of cement components, pretreated at room temperature (20 ° C) for 30 minutes, dehydrated, and kneaded in the same composition as above to obtain a solidified product. It was

As a result, since the pretreatment was not sufficient,
The obtained solidified body had cracks due to expansion.

[Comparative Example 4] An ion exchange resin having the same specifications as those in the above-mentioned Example was kneaded without pretreatment in a blend of blast furnace cement type B: water: ion exchange resin = 100: 40: 64 (parts by weight). .

The solidified product thus obtained could not be a solidified product due to cracking which was considered to be caused by the water-expansion of the ion exchange resin.

Comparative Example 5 An ion exchange resin having the same specifications as above was pretreated in water at room temperature (20 ° C.) for 12 hours, then dehydrated, and then cemented with the same composition as in Comparative Example 4 above. .

As a result, in the case of pretreatment with water, water absorption continued from the cement paste after kneading, and cracking occurred in the solidified body due to expansion due to this.

Comparative Example 6 A resin pellet having the same specifications as in Example 12 was pretreated in water at room temperature (20 ° C.) for 12 hours and then dehydrated, and blast furnace cement type B: water: resin pellet = The mixture was kneaded and solidified with a compounding ratio of 100: 40: 66 (parts by weight).

As a result, in the obtained solidified body, as in the case of Comparative Example 5, cracks which are considered to be caused by the water absorption expansion of the ion exchange resin were generated.

[0096]

[Table 2]

[0097]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, incineration ash, used ion-exchange resin, and used ions, which are wastes generated from a radiation handling facility whose stability in cement has been difficult in the past. The pelletized waste of the exchange resin can be stably fixed with cement, and long-term stability at the landfill site can be obtained.

Further, in the present invention, only the pretreatment with an alkaline solution is added to the ordinary cement solidification method, which can be applied to a concentrator for existing radioactive waste liquid etc. Therefore, there are few cost problems.

In addition, the conventional 200 liter drum can 2
It is possible to solidify 50kg or more of the dry base used resin that could only be solidified with cement for 5 to 30kg, and also to cement a plurality of radioactive wastes that could not be performed in the past. Can be solidified.

[Brief description of the drawings]

FIG. 1 is a float chart showing a procedure according to an embodiment of a radioactive waste treatment method according to the present invention.

FIG. 2 is a graph showing the results of measurement of Al corrosion rate in an alkaline solution, in which the pretreatment conditions for incinerated ash were obtained for each temperature.

FIG. 3 is a graph showing the results of measuring the change over time in the diameter of resin pellets, in which the pretreatment conditions for the used ion exchange resin were determined for each temperature.

FIG. 4 is a graph showing the change over time in compressive strength of the produced solidified incinerated ash.

FIG. 5 is a graph showing the change over time in compressive strength of the produced solidified ion-exchange resin.

[Explanation of symbols]

 Steps showing steps S1 to S5

Claims (10)

[Claims] 1. A powdery material generated at a radioactive material handling facility,
In the radioactive waste treatment method of solidifying granular or other solid radioactive waste with cement, before the solidification treatment, the radioactive waste is immersed in an alkaline solution, or a pretreatment of heating after immersion is performed. A method for treating radioactive waste, characterized in that 2. The method for treating radioactive waste according to claim 1, wherein as radioactive waste to be treated, incinerated ash obtained by incineration of combustible waste generated at a radioactive material handling facility, or fluid at the facility. A method for treating radioactive waste, which comprises applying an ion exchange resin used for purification. 3. The method for treating radioactive waste according to claim 2, wherein when the radioactive waste to be treated is incinerated ash, the amphoteric ash contained in the incinerated ash is an alkaline solution for dipping in the incinerated ash. 0.0 for 2 g of metal
8 mol or more of alkali metal hydroxide or 0.12
Treatment of radioactive wastes, characterized by using a product added with mol or more of alkaline earth metal hydroxide or a product obtained by contacting water with a hardened cement product to dissolve the components of the cement and saturating Method. 4. The method for treating radioactive waste according to claim 2 or 3, when the radioactive waste to be treated is incinerated ash, the heating condition after immersing the incinerated ash in an alkaline solution is the heating temperature. A method for treating radioactive waste, characterized in that the heating time is set to 70 ° C. or higher for 4 hours or more, or the immersion liquid is boiled for 30 minutes or more. 5. The method for treating radioactive waste according to claim 2, wherein the incineration ash or the ion exchange resin, which is the radioactive waste to be treated, is immersed in an alkaline solution and the heat treatment is performed at a radioactive substance handling facility. Waste liquid concentrating device, which is a method for treating radioactive waste. 6. The method for treating radioactive waste according to claim 2, wherein when the radioactive waste to be treated is an ion exchange resin, the hardened cement cement is contacted with water as an alkaline solution to remove the cement in water. A method for treating radioactive waste, which comprises using a solution prepared by mixing a solution saturated with a dissolved component with an alkali metal hydroxide. 7. The method for treating radioactive waste according to claim 2, wherein when the radioactive waste to be treated is an ion exchange resin, the ion exchange resin is immersed in an alkaline solution and held for 12 hours or more without heating. Or the heating condition after immersing the ion exchange resin in an alkaline solution is such that the heating temperature is 70 ° C. or higher and the immersion liquid is boiled for 4 hours or longer or 30 minutes or longer, and the cement is dissolved as an alkaline solution. Li, K,
A radioactive waste characterized by using one to which one or more kinds of alkali metals selected from Na are added, and the amount of addition is set so that the concentration of the immersion liquid after addition is 0.4 mol / L or more. How to dispose of things. 8. The method for treating radioactive waste according to claim 2, wherein when the radioactive waste to be treated is an ion exchange resin, water contained in the ion exchange resin is removed, and then the alkaline solution is added. A method for treating radioactive waste, which comprises dipping. 9. The method for treating radioactive waste according to any one of claims 1 to 8, wherein as the radioactive waste to be treated, in addition to incineration ash or ion exchange resin, used ion exchange resin is dried. An apparatus for treating radioactive waste, which comprises adding post-solidified pellet waste, pre-treating two or more of them collectively and solidifying with cement. 10. A dipping tank for dipping radioactive waste containing an alkaline solution, a heating tank for heating the dipping material, and a solidification device for cement-solidifying the substance after heating. Radioactive waste treatment equipment.