JPH0868895A - Solidification method and device for radioactive waste - Google Patents

Abstract

PURPOSE: To provide a solidification method for radioactive waste capable of forming uniform solid without lowering the nuclide adsorption capability of cement as a solidifier. CONSTITUTION: According to the content of amorphous silica measured in advance, an operator sets a target supply amount of silica fly ash and cement material to a supply amount setter of a mixing controller 100 so that the weight ratio of the amorphous silica to portland cement becomes 1/9 to 2/3 and so according to it, a cement supply mechanism 62 and silica supply mechanism 60 throw the cement material and fly ash controlled at the supply amount controller in a mixer 10. Then, a predetermined amount of sand, cellulose ether, mixing water are thrown from an aggregate tank 3, a separation prevention tank 4 and a mixing water tank 5 into the mixer 10 and mixed. After mixing, the prepared mixed paste is injected in a solidification vessel filled with miscellaneous waste by opening an exhaust gate 13.

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 radioactive waste generated from nuclear facilities such as power plants and reprocessing plants, and more particularly to solidifying radioactive waste by using cement-based solidifying material. The present invention relates to a method for solidifying radioactive waste and an apparatus for solidifying radioactive waste.

[0002]

2. Description of the Related Art Generally, a nuclear facility such as a nuclear power plant produces radioactive waste such as chemical waste liquid, solid waste, used ion-exchange resin and incineration ash. These wastes are appropriately volume-reduced and then solidified in a steel solidification container using solidifying materials such as cement and plastic.
It is buried and stored in a storage facility constructed underground. Among the solidifying materials used at this time, especially the cement-based solidifying material is inexpensive because the raw material is an ore that is naturally calculated, and it is easy to handle because it can be solidified simply by kneading with water, and it is an inorganic substance. Since it has an advantage of being excellent in long-term durability, it is often used as a typical solidifying material for radioactive waste.

The solidification method of radioactive waste using this cement-based solidifying material is roughly classified into the following two types. (1) Injection solidification method In this solidification method, radioactive waste is filled in a solidification container in advance, and a mixed paste of solidifying material and kneading water is injected into the solidification container to solidify. -A solidification method suitable for solidifying relatively large-sized waste such as heat-insulating materials, scaffolding materials, valve bodies, and other miscellaneous solid waste, and compression-molded products thereof. (2) Kneading and solidifying method In this solidifying method, the solidifying material, the kneading water, and the radioactive waste are uniformly kneaded with a dedicated kneader to prepare a mixed paste,
This mixed paste is poured into a solidifying container and solidified. In this case, the radioactive waste is limited to those having relatively good compatibility with cement, such as chemical waste liquid, dry powder (salts) of chemical waste liquid, and incineration ash.

In the solidification treatment of radioactive waste using the above-mentioned cement-based solidifying material, it is essential to suppress an increase in the internal temperature of the solidified body due to the heat generated by hardening of the cement. This exotherm is caused by the fact that the cement hydration reaction is an exothermic reaction, and in particular, a large-scale cement hardening process is performed by filling the inside of a 200-liter drum with metal waste having a relatively low specific heat. It appears prominently when creating the body. This heat generation has the following adverse effects, for example. That is, if the temperature of the central portion of the solidified body rises excessively and a temperature distribution is formed inside the solidified body, cracks may occur due to thermal strain. In general, when amphoteric metals such as aluminum are present in metal waste, hydrogen is generated by reacting with the alkali component in the cement, but this rate of hydrogen generation accelerates as the temperature inside the solidified body rises. Since the bubbles of hydrogen gas are generated during curing of the solidified cement, the strength of the solidified body may decrease. Therefore, in the solidification of radioactive solid waste into cement, it is desirable to alleviate the hardening heat of the cement and reduce the rise in internal temperature of the solidified body. Based on this point of view, there are, for example, the following known techniques for alleviating the heat generated by hardening of cement.

A unit for reducing the amount of unit cement This known technique is to add aggregates such as sand, gravel and artificial aggregates to a mixed paste as described in "Characteristics of concrete" (written by Neville) p36. By reducing the unit amount of cement by means of the above, the amount of heat generated when the mixed paste in the solidification container is cured is reduced.

Using low-heat-generating cement This known technique is disclosed in "Characteristics of concrete" (Neville) p36, for example, as a low-heat-generating component of 2 calcium silicate (2CaO.SiO2 solid solution). By using a low exothermic cement having a large ratio of (commonly known as belite), the amount of heat generated when the mixed paste in the solidifying container is cured is reduced.

This known technique uses latent heat, for example, as described in Japanese Patent Application Laid-Open No. 1-158400, in which kneading water is added in an ice state to remove the latent heat to lower the internal temperature of the solidified body. Is.

[0008]

Generally, in the solidification treatment method using cement, the mixed paste is required to have a certain degree of fluidity.
In particular, in the injection solidification method of (1), it is required that the mixed paste has a large fluidity so that the mixed paste can spread throughout the gaps of the waste filled in the solidification container. From this point of view, the following problems exist when applying the above-mentioned known techniques (1) to the injection solidification method (1) to suppress heat generation. That is, in the known art, cement and aggregate are easily separated, the fluidity of the mixed paste is insufficient,
On the other hand, when the amount of kneading water is increased to increase the fluidity of the mixed paste, breathing water is generated and the solidified product becomes non-uniform. Further, there is a problem in that the uniformity of the paste is deteriorated due to the catching of the aggregate in the narrowed portion, and internal voids remain in the solidified body. Further, in the known art, in order to secure the fluidity of the mixed paste, an increase in the amount of kneading water or β
-It is necessary to use a water-reducing agent such as a naphthalene type, and as in the above case, breathing water is generated and the solidified product tends to become non-uniform, which is a problem. Furthermore, in the known art, it is difficult to obtain a cement paste having a fluidity of a degree necessary for injection solidification, and breathing water is generated in the same manner as above when ice is increased to increase the fluidity of the mixed paste. There was a problem that the solidified body became uneven. That is, when heat generation is suppressed by applying the above-mentioned known techniques in the injection solidification method of (1), breathing water is generated in the mixed paste, and nonuniformity of the solidified body due to solid-liquid separation occurs. Therefore, as a known technique for solving this, for example, the following has been proposed.

[0009] Japanese Patent Laid-Open No. 63-228099 discloses a known technique in which a fine aggregate such as sand and blast furnace slag, and coarse aggregate such as artificial aggregate and natural aggregate are added to a mixed paste in a solidifying container. The amount of heat generated by hardening of cement is reduced, and the viscosity of the mixed paste is adjusted by adding a water-retaining material (separation preventive material) of cellulose, vinyl, or acrylic so that the breathing water before the mixed paste solidifies. To prevent the occurrence of solid state separation and solid-liquid separation.

On the other hand, in the kneading and solidifying method of (2), it is necessary to reduce heat generation. In this case, by applying the above-mentioned known technique, a cement paste having a fluidity of a degree necessary for kneading and hardening is obtained. Obtainable. However, in the kneading method of (2), the powdery radioactive waste contained in the mixed paste has a relatively low specific gravity,
Since it tends to float upward in the mixed paste, radioactive waste concentrates upward and the solidified body tends to become non-uniform. Therefore, by adding the separation preventing material as described in the above-mentioned known technique to the mixed paste, the viscosity of the mixed paste is increased to suppress this floating, and it is possible to maintain good uniformity in the mixed paste. it can.

As described above, in both the injection solidification method (1) and the kneading and solidification method (2), the separation preventing agent is added to the mixed paste to ensure good uniformity of the mixed paste. There is. However, the addition of such a separation preventing material causes the following new problems. That is, the separation preventing material according to the known technique is a water-soluble organic substance used for underwater non-separable concrete, and when applied to the solidification of radioactive waste, it is soluble in radioactive nuclides (Co-60, Ni-63, etc.) belonging to transition metals. There is a problem that it is easy to form a water-soluble complex and lowers the nuclide adsorption performance of cement, which is a solidifying material, that is, the distribution coefficient.

An object of the present invention is to provide a radioactive waste solidification method and a radioactive waste solidification apparatus capable of producing a uniform solidified product without deteriorating the nuclide adsorption performance of cement as a solidifying material. That is.

[0013]

In order to achieve the above object, according to the first concept of the present invention, a cement having a Portland cement component, an inorganic aggregate, kneading water, and a viscosity modifier are added. In the method of solidifying radioactive waste by solidifying the radioactive waste with the cement-based solidifying material contained, as the inorganic aggregate, amorphous silica having a weight ratio to the Portland cement component of 1/9 or more and 2/3 or less There is provided a method for solidifying radioactive waste, which comprises using a material containing components.

Preferably, in the method for solidifying radioactive waste, there is provided a method for solidifying radioactive waste, wherein the radioactive waste is radioactive miscellaneous solid waste.

In order to achieve the above object, according to the second concept of the present invention, a radioactive waste is a cement-based solidifying material containing cement having a Portland cement component, kneading water, and a viscosity modifier. In the method for solidifying radioactive waste, the cement is used in a weight ratio to the Portland cement component of 1/9 or more 2 /
There is provided a method for solidifying radioactive waste, which comprises using an amorphous silica component containing 3 or less.

[0016] Preferably, in the method for solidifying radioactive waste, the radioactive waste has at least one of an incinerated ash, an incinerated ash compact, and a concentrated chemical waste liquid compact. A method for solidifying radioactive waste is provided.

Also preferably, in the method for solidifying radioactive waste, the amorphous silica component has a weight ratio to the Portland cement component of 3/17 or more and 7/1.
There is provided a method for solidifying radioactive waste, which is characterized by being 3 or less.

More preferably, in the method for solidifying radioactive waste, the amorphous silica component is contained in the blast furnace slag contained in the cement, and the blast furnace slag is in a weight ratio to the Portland cement component. Is 3/7 or more and 7/3 or less, and a method for solidifying radioactive waste is provided.

Further preferably, in the method for solidifying radioactive waste, the amorphous silica component is contained in the blast furnace slag contained in the cement, and the blast furnace slag has a weight ratio to the Portland cement component. Is 2/3 or more and 3/2 or less, and a method for solidifying radioactive waste is provided.

More preferably, in the method for solidifying radioactive waste, the amorphous silica component is contained in silica fume contained in at least one of the cement and the inorganic aggregate. Has a weight ratio of 1 to the Portland cement component.
/ 9 or more and 3/7 or less, The solidification method of radioactive waste is provided.

Further preferably, in the method for solidifying radioactive waste, the amorphous silica component is contained in fly ash contained in at least one of the cement and the inorganic aggregate. Is
The weight ratio to the Portland cement component is 3/1
A method for solidifying radioactive waste is provided, which is 7 or more and 1 or less.

More preferably, in the method for solidifying radioactive waste, there is provided a method for solidifying radioactive waste, wherein the viscosity modifier is a water-soluble organic substance.

Further preferably, in the method for solidifying radioactive waste, there is provided a method for solidifying radioactive waste, characterized in that the water-soluble organic matter contains at least one of cellulose ethers and polyacrylamides. It

More preferably, in the method for solidifying radioactive waste, the Portland cement component is 2
There is provided a method for solidifying radioactive waste, which comprises 30% by weight or more of calcium silicate.

Further preferably, in the method for solidifying radioactive waste, there is provided a method for solidifying radioactive waste, wherein the cement, the inorganic aggregate and the viscosity modifier are premixed in advance.

More preferably, in the method for solidifying radioactive waste, the inorganic aggregate is a non-reactive inorganic aggregate made of a substance having non-reactivity to the Portland cement component. A method of solidifying an article is provided.

Further preferably, in the method for solidifying radioactive waste, the non-reactive inorganic aggregate includes at least one of sand, gravel, and artificial lightweight aggregate. A solidification method is provided.

In order to further achieve the above object, according to the third concept of the present invention, a radioactive substance for solidifying radioactive waste with a cement-based solidifying material containing cement, kneading water, and a viscosity modifier. In the method for solidifying waste, there is provided a method for solidifying radioactive waste, which comprises using an inorganic substance as the viscosity modifier.

Preferably, in the method for solidifying radioactive waste, the cement-based solidifying material further comprises an inorganic aggregate, and the radioactive waste is miscellaneous solid waste. A solidification method is provided.

Further preferably, in the method for solidifying radioactive waste, the radioactive waste is at least one of an incinerated ash, an incinerated ash compact, and a concentrated chemical waste liquid compact.
There is provided a method for solidifying radioactive waste, comprising:

More preferably, in the method for solidifying radioactive waste, the inorganic substance has at least one of bentonite, montmorillonite, clinobutilolite, and acid clay, and solidification of radioactive waste. A method is provided.

In order to achieve the above object, according to a fourth concept of the present invention, cement storing means for storing cement having a Portland cement component, inorganic aggregate, kneading water, and viscosity modifier, respectively. An aggregate storing means, a kneading water storing means, and a viscosity adjusting agent storing means; and a kneader for kneading the cement, the inorganic aggregate, the kneading water, and the viscosity adjusting agent introduced from these storing means to form a mixed paste. Provided between the cement storage means, the aggregate storage means, the kneading water storage means, and the viscosity adjusting agent storage means, and the kneading machine, and each of the cement, the inorganic aggregate, the kneading water, and the viscosity adjusting agent. Cement supplying means, aggregate supplying means, kneading water supplying means, and viscosity adjusting agent supplying means having a function of quantitatively supplying from the storage means to the kneading machine; mixing mixed by the kneading machine A solidification device for injecting the mixed paste into a radioactive miscellaneous solid waste previously arranged in the solidification container, and solidifying the solid waste into a solidification container. A silica storage means for storing a substance containing silica, and a function of being provided between the silica storage means and the kneader, and having a function of quantitatively supplying the substance containing the amorphous silica to the kneader. A silica supply means, a supply amount setting means capable of setting the supply amount of the substance containing the amorphous silica and cement to the kneader, and the cement supply means according to the supply amount set by the setting means, and A solidification device for radioactive waste, comprising: a supply amount control means for controlling an operation of the silica supply means.

According to a fifth concept of the present invention, in order to achieve the above object, a radioactive substance having at least one of an incineration ash, an incineration ash compact, and a concentrated chemical waste liquid compact. Waste, cement having a Portland cement component, kneading water, and a waste storing means for storing a viscosity adjusting agent, a cement storing means, a kneading water storing means,
And a viscosity adjusting agent storage means; at least a kneading machine for kneading radioactive waste, cement, kneading water, and a viscosity adjusting agent introduced from these storage means into a mixed paste; the waste storage means, cement storage Means, kneading water storage means, and viscosity adjusting agent storage means and the kneading machine, respectively, the waste, cement, kneading water, and viscosity adjusting agent from each storage means to the kneading machine A waste supply means having a function of supplying, a cement supply means, a kneading water supply means, and a viscosity adjusting agent supply means; and an injection means for injecting the mixed paste kneaded by the kneader into a solidification container, In a device for solidifying radioactive waste for solidifying the radioactive waste, a silica storing means for storing a substance containing amorphous silica, the silica storing means, and the silica storing means. To the kneading machine for the substance containing the amorphous silica, and a means for supplying the substance containing the amorphous silica to the kneading machine in a fixed amount, and a function of feeding the substance and the cement containing the amorphous silica. And a supply amount control unit for controlling the operations of the cement supply unit and the silica supply unit according to the supply amount set by the setting unit. A solidification device for radioactive waste is provided.

Preferably, in the apparatus for solidifying radioactive waste, at least one of blast furnace slag, silica fume, and fly ash is stored in the silica storage means, and the setting means corresponds to this. There is provided a solidification device for radioactive waste, which is a means capable of setting the amounts of blast furnace slag, silica fume, and fly ash supplied to the kneader.

Further preferably, in the apparatus for solidifying radioactive waste, the first vibrating means provided in the pouring means for vibrating the mixed paste injected into the solidification container and the solidification container are vibrated. There is provided a solidification device for radioactive waste, further comprising at least one of second adding means for adding.

More preferably, in the apparatus for solidifying radioactive waste, a viscosity monitor means for measuring the viscosity of the mixed paste in the kneader, and at least the cement supply means according to the viscosity measured by the viscosity monitor means, The viscosity of the mixed paste is adjusted to 5 by controlling the operations of the kneading water supply means, the viscosity adjusting agent supply means, and the silica supply means.
There is provided a solidification device for radioactive waste, further comprising a viscosity control means for adjusting the viscosity to 000 cp or less.

Further preferably, in the apparatus for solidifying radioactive waste, the viscosity control means is means for adjusting the viscosity of the mixed paste to 1000 cp or more and 3000 cp or less. Provided.

More preferably, in the apparatus for solidifying radioactive waste, the kneading machine has a stirring blade for stirring the mixed paste in the kneading machine, and the viscosity monitoring means is
Radioactive waste characterized in that it is a means for measuring the load current of an electric motor that drives the stirring blade, and detecting the viscosity of the mixed paste based on the correlation between the load current and the viscosity that is measured and stored in advance. A solidification device is provided.

Further preferably, in the apparatus for solidifying radioactive waste, the kneading machine has a stirring blade for stirring the mixed paste in the kneading machine, and the viscosity monitoring means measures the torque of the stirring blade, A solidification device for radioactive waste is provided, which is a means for detecting the viscosity of the mixed paste based on the correlation between torque and viscosity that has been measured and stored in advance.

More preferably, in the apparatus for solidifying radioactive waste, the cement supplying means, the aggregate supplying means, the viscosity adjusting agent supplying means and the silica supplying means are provided between the kneader and the cement supplying means. From the aggregate, the inorganic aggregate from the aggregate supply means, the viscosity modifier from the viscosity modifier supply means, and the substance containing amorphous silica from the silica supply means are mixed and mixed in a powder state. It further comprises a premixer for forming powder and a mixed powder supply means having a function of quantitatively supplying the mixed powder from the premixer to the kneader, and the kneader comprises the mixed powder supply There is provided a device for solidifying radioactive waste, which is a means for kneading the mixed powder supplied from the means and the kneading water supplied from the kneading water supplying means.

Further preferably, in the apparatus for solidifying radioactive waste, it is provided between the waste supply means, the cement supply means, the viscosity modifier supply means, the silica supply means and the kneader, and at least the waste. The radioactive waste from the material supply means, the cement from the cement supply means, the viscosity modifier from the viscosity modifier supply means, and the substance containing amorphous silica from the silica supply means are mixed in a powder state. And a mixed powder supply means having a function of quantitatively supplying the mixed powder from the premixer to the kneading machine, and the kneading machine,
There is provided a device for solidifying radioactive waste, which is a means for kneading the mixed powder supplied from the mixed powder supply means and the kneading water supplied from the kneading water supply means.

More preferably, in the apparatus for solidifying radioactive waste, there is provided the apparatus for solidifying radioactive waste, wherein the premixer is installed outside a radiation controlled area.

Further preferably, in the apparatus for solidifying radioactive waste, at least one of the kneading water tank and the kneading water supply means is provided with a cooling means for cooling the kneading water. A solidification device is provided.

More preferably, in the apparatus for solidifying radioactive waste, the viscosity adjusting agent supplying means is a means for supplying the viscosity adjusting agent from the viscosity adjusting agent supplying means to the kneading water storing means, and the kneading is performed. The water storage means includes a stirring blade that stirs the mixture of the viscosity modifier and the kneading water supplied by the viscosity modifier supply means, and the kneading water supply means stores the mixture in the kneading water reservoir. A solidification device for radioactive waste is provided, which is a means for supplying the kneader to the kneader.

[0045]

In the method for solidifying radioactive waste according to the first concept of the present invention configured as described above, radioactive waste, for example, miscellaneous solid radioactive waste, is mixed with an inorganic aggregate and a viscosity modifier such as cellulose ether. By solidifying with a cement-based solidifying material containing a water-soluble organic substance such as polyacrylamides and polyacrylamides, it is possible to suppress the curing heat of the solidified body with the inorganic aggregate and reduce the internal temperature, and also the viscosity modifier. In this way, it is possible to suppress the sedimentation and separation of cement particles and aggregates, and the setting of cement is completed before the separation, so that a uniform solidified body can be created. Therefore, solid-liquid separation can be suppressed and the generation of breathing water can be reduced. Further, the fluidity of the mixed paste can be improved and the voids inside the solidified body can be reduced. Furthermore, since the inorganic aggregate contains an amorphous silica component having a weight ratio of cement to Portland cement component of 1/9 or more and 2/3 or less, the amorphous silica reacts with alkali in the cement. Then, the properties of the cement can be changed, and the nuclide adsorption performance of the cement which has been lowered by the addition of the viscosity modifier can be recovered. Further, at this time, by reducing the internal temperature with the inorganic aggregate, the corrosion rate of the metal having temperature dependence is reduced, so that the corrosion of the metal contained in the waste can be reduced, and a viscosity modifier is added. As a result, the ion diffusion rate decreases and the reaction between the metal and the cement is suppressed, so that the corrosion can be further reduced.

In the method for solidifying radioactive waste according to the second concept of the present invention, radioactive waste such as incineration ash
By solidifying the molded body / concentrated chemical waste liquid molded body with a cement-based solidifying material containing a viscosity modifier, it is possible to suppress low-density incinerated ash and the like from floating and separating from the mixed paste, and to separate by floating. Since the setting of cement is completed before it is destroyed, a uniform solidified body can be created. Therefore, solid-liquid separation can be suppressed and the generation of breathing water can be reduced. Further, the fluidity of the mixed paste can be improved and the voids inside the solidified body can be reduced. Further, since the cement contains an amorphous silica component having a weight ratio to the Portland cement component of 1/9 or more and 2/3 or less, the amorphous silica reacts with alkali in the cement to improve the properties of the cement. It is possible to restore the nuclide adsorption performance of the cement that has been changed and decreased by the addition of the viscosity modifier. Further, at this time, the addition of the viscosity modifier lowers the ion diffusion rate and suppresses the reaction between the metal contained in the waste and the cement, so that the metal corrosion can be reduced.

The weight ratio of the amorphous silica component to the Portland cement component is 3/17 or more and 7/13 or less, so that the nuclide adsorption performance of the cement can be remarkably improved, and the viscosity modifier is Even better nuclide adsorption performance can be obtained as compared with the case of not adding.

Further, by using Portland cement containing 30% by weight or more of 2 calcium silicate, so-called moderate heat Portland cement, the curing rate of the solidified product is slowed down, so that the maximum temperature reached in the heat of curing is increased. Can be lower.

Further, since the cement, the inorganic aggregate containing amorphous silica, and the viscosity modifier are premixed in advance, they are stored in one storage means by one supply means. The number of means and supply means can be reduced, the space of the entire solidification apparatus can be minimized, and the cost can be reduced.

Furthermore, since the inorganic aggregate is a non-reactive inorganic aggregate made of a substance having non-reactivity with respect to the components of Portland cement, such as sand, gravel, and artificial lightweight aggregate, heat generation with Portland cement occurs. The reaction does not impede the effect of reducing the heat build up by the inorganic aggregate.

Further, in the method for solidifying radioactive waste according to the third concept of the present invention, a viscosity adjusting agent for inorganic substances, for example, bentonite, montmorillonite, clinobuchilorite, or natural clay mineral such as acid clay is used. This can prevent the nuclide adsorption performance of the cement from being lowered as in the case of using the organic viscosity modifier. Therefore, it is not necessary to add amorphous silica to recover the nuclide adsorption performance. Also, the cation exchange action of the natural clay mineral can improve the adsorption performance for cation nuclides such as Cs and Sr.

Further, in the radioactive waste solidifying apparatus of the fourth concept of the present invention, cement storage means, aggregate storage means, kneading water storage means, viscosity adjusting agent storage means, silica storage means, cement and inorganic material are used. Aggregate, kneading water, viscosity modifier,
Amorphous silica-containing substances such as blast furnace slag, silica fume, fly ash, etc. are stored, and are supplied from cement storage means, aggregate supply means, kneading water supply means, viscosity adjusting agent supply means, silica supply means. Derived cement, inorganic aggregate, kneading water, viscosity modifier, amorphous silica-containing substance is quantitatively supplied to the kneader, and these are kneaded with the kneader to form a mixed paste, which is then poured into a solidification container by a pouring means. The mixed paste is injected, and radioactive miscellaneous solid waste, such as miscellaneous solid waste, which has been previously placed in the solidification container is injected and solidified. At this time, in accordance with the amorphous silica content in the amorphous silica-containing substance measured in advance and the Portland cement component content in the cement, the operator, by the supply amount setting means, with the amorphous silica-containing substance The amount of cement supplied to the kneading machine is set, and the operations of the cement supply unit and the silica supply unit are controlled by the supply amount control unit according to the set supply amount. As a result, the amorphous silica can be kneaded in an arbitrary ratio with respect to the Portland component contained in the cement.

Further, in the radioactive waste solidifying apparatus of the fifth concept of the present invention, radioactive waste is contained in the waste storage means, cement storage means, kneading water storage means, viscosity adjusting agent storage means, silica storage means. For example, incinerated ash, incinerated ash compact
Molded material of concentrated chemical waste liquid, cement, kneading water, viscosity modifier, amorphous silica-containing substance is stored, waste supply means,
A cement supply means, a kneading water supply means, a viscosity adjusting agent supplying means, and a silica supplying means, and the waste, cement, kneading water, viscosity adjusting agent, and amorphous silica-containing substance introduced from these storage means to the kneader. A fixed amount is supplied, and these are kneaded by a kneader to form a mixed paste, and the mixed paste is injected into a solidification container by an injection means to knead and solidify the radioactive waste. At this time, in accordance with the amorphous silica content in the amorphous silica-containing substance measured in advance and the Portland cement component content in the cement, the operator, by the supply amount setting means, with the amorphous silica-containing substance The amount of cement supplied to the kneading machine is set, and the operations of the cement supply unit and the silica supply unit are controlled by the supply amount control unit according to the set supply amount. As a result, the amorphous silica can be kneaded in an arbitrary ratio with respect to the Portland component contained in the cement.

Further, the first mixing means provided in the injecting means vibrates the mixed paste injected into the solidification container, or the second exciting means vibrates the solidification container to mix the paste. External stress is applied to the paste, the cement skeleton that is being formed is temporarily divided and softened, and the apparent viscosity of the mixed paste is reduced. Further, since the bubbles inside the solidified body are swung to facilitate the escape to the outside, the deviation of the voids inside the solidified body can be promoted and the internal porosity can be lowered.

Further, the viscosity of the mixed paste in the kneading machine is measured by the viscosity monitoring means, and the viscosity controlling means selects one of the cement supplying means, the kneading water supplying means, the viscosity adjusting agent supplying means and the silica supplying means according to the measured viscosity. By controlling the operation and adjusting the viscosity of the mixed paste to 5000 cp or less, it is possible to reduce the viscosity of the mixed paste to such an extent that injection solidification is possible.

Further, by adjusting the viscosity of the mixed paste to 1000 cp or more and 3000 cp or less by the viscosity control means, the fluidity is improved and the mixed paste is allowed to penetrate into the miscellaneous solid waste having constrictions such as metal pipes. In addition, the injection time can be shortened. Further, it is possible to suppress the aggregate separation and improve the uniformity.

In addition, cement supply means, aggregate supply means,
A premixer provided between the kneading machine and the viscosity adjusting agent supplying means and the silica supplying means, the cement from the cement supplying means, the inorganic aggregate from the aggregate supplying means, the viscosity adjustment from the viscosity adjusting agent supplying means Agent, the amorphous silica-containing substance from the silica supply means is mixed in a powder state to form a mixed powder, and the mixed powder supply means quantitatively supplies the mixed powder from the premixer to the kneader. The mixed powder is supplied from the mixed powder supply means to the kneading machine through one line, and the space for arranging the lines is small, and after the mixing, the control for adjusting these components is not performed. Therefore, it becomes possible to draw a long line from the mixed powder supply means to the kneader,
By using this pipeline as the boundary line of the radiation control area, the storage means, the supply means, the premixer, etc. on the upstream side of this pipeline can be arranged outside the radiation control area, and the maintainability of these is improved. Further, since the number of members to be arranged in the radiation controlled area is reduced, the space in the radiation controlled area can be reduced and the amount of radioactive waste can be reduced. Furthermore, since the amorphous silica-containing substance, cement, inorganic aggregate, and viscosity modifier are uniformly mixed before mixing with kneading water, the kneading time in the kneader can be shortened, and the solidification treatment speed can be increased. Can be increased. This is also
The same applies to the case of kneading and solidification without an aggregate supplying means.

Furthermore, the initial temperature of the mixed paste can be lowered by cooling the kneading water with the cooling means provided in the kneading water tank or the kneading water supply means. Therefore, it is effective, for example, when it is desired to reduce the amount of aggregate.

Further, while the viscosity adjusting agent is supplied from the viscosity adjusting agent supplying means to the kneading water storing means by the viscosity adjusting agent supplying means, the mixture of the viscosity adjusting agent and the kneading water is stirred by the stirring blade of the kneading water storing means. This makes it possible to finely adjust the viscosity of the kneading water, which is particularly suitable for preparing a mixed paste having a large water-cement ratio. Further, since the viscosity of the kneading water has increased from the initial stage of kneading, it is possible to prevent sedimentation of the inorganic aggregate in the kneader and clogging of the injection means.

[0060]

Embodiments of the present invention will be described below with reference to FIGS. A first embodiment of the present invention will be described with reference to FIGS. This embodiment is an embodiment of a method for solidifying radioactive waste and a solidifying apparatus for carrying out the method. FIG. 1 shows the overall configuration of a solidification apparatus for carrying out the method for solidifying radioactive waste according to this embodiment. In FIG. 1, the solidification device 10
00 is a fly ash containing 55% by weight of amorphous silica, a cement member in which 100% of the component is Portland cement, sand as an inorganic aggregate, and a function of adjusting viscosity to prevent solid-liquid separation. Cellulose ether as an organic separation inhibitor, and a silica storage tank 50 in which kneading water is stored, a cement storage tank 2, an aggregate storage tank 3, a separation prevention agent storage tank 4, a mixing water storage tank 5, and these storage tanks are introduced. A kneading machine 10 for kneading a cement member, sand, cellulose ether, and kneading water into a mixed paste, and a silica storage tank 5
0 ・ Cement storage tank 2 ・ Aggregate storage tank 3 ・ Separation prevention agent storage tank 4 ・
A silica supply mechanism 60, a cement supply mechanism 62, an aggregate supply mechanism 63, an anti-separation agent supply mechanism 64, and an electromagnetic valve 6 which are respectively provided between the kneading water storage tank 5 and the kneading machine 10.
And the mixture paste kneaded by the kneading machine 10 into a solidifying container 1
The discharge gate 13 for injecting into the inside, the compounding control device 100 for controlling the operations of the silica supply mechanism 60 and the cement supply mechanism 62, and the viscosity control device 70 for monitoring the viscosity of the mixed paste and controlling the viscosity are provided.

The solidification container 1 is a steel container having a size (for example, a capacity of 200 liters) that can be injected and solidified on an actual scale, and has a non-combustible miscellaneous solid waste such as metal pipes generated from a nuclear power plant inside. The product or its compression molded product is pre-filled. Further, below the solidification container 1, a shaker 12 that applies vibration to the solidification container 1 is provided.

Silica supply mechanism 60, cement supply mechanism 6
2, the aggregate supply mechanism 63, the separation preventing agent supply mechanism 64, and the kneading water supply mechanism 65 are constituted by a fixed quantity feeder or a fixed quantity hopper. Each of these supply mechanisms includes a silica storage tank 50, a cement storage tank 2, an aggregate storage tank 3, an antiseparation agent storage tank 4, a first opening / closing valve capable of opening and closing the bottom of the kneading water storage tank 5, and a kneading machine 10 from each supply mechanism. It has a second opening / closing valve capable of opening and closing a pipe line communicating with, and has a function of quantitatively supplying fly ash, cement member, sand, cellulose ether, and kneading water to the kneading machine 10.

The cellulose ether stored in the separation preventing agent storage tank 4 corresponds to, for example, alkyl cellulose such as methyl cellulose or carboxyalkyl cellulose such as hydroxyethyl cellulose.

In the kneading machine 10, the fly ash, the cement member, the sand, the cellulose ether, and the kneading water, which are fed into the kneading machine 10, are stirred, and a stirring blade 9 for uniformly mixing them into a mixed paste is provided. A motor 8 for rotating the stirring blade 9 (for example, at a rotation speed of about 100 rpm for about 3 minutes) is provided. The load current of the motor 8 is measured by the ammeter 7.

The discharge gate 13 is provided with a shaker 11 for vibrating the mixed paste injected into the solidification container 1.

The compounding control device 100 has a supply amount setting unit (not shown) capable of setting the supply amounts of fly ash and cement members to the kneading machine 10, and a target supply amount set by this supply amount setting unit. Accordingly, the cement supply mechanism 62 and the silica supply mechanism 60 are provided with a supply amount control unit (not shown). As a result, the operator sets the mixing ratio of the fly ash and the cement member according to the content of the amorphous silica in the fly ash and the content of Portland cement in the cement member, which is measured in advance, and sets the supply amount. When inputting to the section, the supply amount control section correspondingly receives the input from the cement supply mechanism 62 and the silica supply mechanism
Controls 0 operation. FIG. 2 shows a flowchart showing the control contents of this supply amount control unit.

In FIG. 2, first, in S100,
The target supply amount of fly ash and the target supply amount of the cement member set by the supply amount setting unit are input. Then S20
0, the second opening / closing valve of the cement supply mechanism 62 is closed to stop the supply of the cement member to the kneading machine 10, and the first opening / closing valve is opened to introduce the cement member from the cement storage tank 2. Then, in S300, it is determined whether the weight of the introduced cement member is less than the target supply amount, and if it is less than the target supply amount, the process returns to S200 and the cement member is continuously introduced. If it exceeds the target supply amount, S400
Then, the first opening / closing valve of the cement supply mechanism 62 is closed to stop the introduction of the cement member from the cement storage tank 2, and the second opening / closing valve is opened to supply the cement member to the kneading machine 10. After that, the process proceeds to S500, the second opening / closing valve of the silica supply mechanism 60 is closed to stop the supply of fly ash to the kneader 10, the first opening / closing valve is opened, and the fly ash is introduced from the silica storage tank 50. Then, in S600, it is determined whether the weight of the introduced fly ash is less than the target supply amount, and if it is less than the target supply amount, the process returns to S500 and the fly ash is continuously introduced. When the supply amount exceeds the target supply amount, the process proceeds to S700, and the silica supply mechanism 60
Of the kneading machine 1 by closing the first opening / closing valve of the
The fly ash is supplied to 0, and this flow ends.

Returning to FIG. 1, the load current value measured by the ammeter 7 is input to the viscosity control device 70. Then, the viscosity of the mixed paste is converted from the input load current value according to the calibration curve of the load current value-mixed paste viscosity that is input and stored in advance in the viscosity control device 70.
Then, based on this calculated viscosity, the silica supply mechanism 6
0, the cement supply mechanism 62, the aggregate supply mechanism 63, the separation preventing agent supply mechanism 64, and the electromagnetic valve 6 are controlled to control the viscosity of the mixed paste. At this time, as described above, since the supply amount of fly ash by the silica supply mechanism 60 and the supply amount of the cement member by the cement supply mechanism 62 are previously determined in the compounding control device 100, other supply amount is based on this supply amount. An aggregate supply mechanism 63 which is a supply mechanism,
The viscosity of the mixed paste is controlled by adjusting the supply amount of the sand / cellulose ether / kneading water by the separation preventing agent supply mechanism 64 and the electromagnetic valve 6 and, in some cases, finely adjusting the silica supply mechanism 60 and the cement supply mechanism 62. To do. This makes it possible to create a paste having an arbitrary property. Also, as a guideline for viscosity control of the mixed paste at this time,
The paste viscosity is 5000 cp to enable injection and solidification
It is necessary to keep below, but further 1000-300
It is desirable to control to 0 cp. As a result, the fluidity can be improved and the mixed paste can be infiltrated into the miscellaneous solid waste having narrowed portions such as metal pipes, and the injection time can be shortened. Further, it is possible to suppress the aggregate separation and improve the uniformity.

Next, the procedure of the solidification method of this embodiment, which is carried out using the solidification apparatus 1000 having the above-mentioned structure, will be described below. First, in this example, for example, radioactive miscellaneous solid waste is filled at 50% by volume, the target supply amount of fly ash is 15 kg per batch, and the target supply amount of cement members is 25 kg per batch. Is set in the supply amount setting unit of the blending control device 100.
At this time, the content of amorphous silica in the fly ash and the content of Portland cement in the cement member have been measured in advance, for example, 55 in each of the examples.
%, 100% results in a final weight ratio of amorphous silica to Portland cement of 0.33. Then, according to these two target supply amounts, the cement supply mechanism 62 and the silica supply mechanism 60 are controlled by the supply amount control unit of the blending control device 100, and this amount of cement member and fly ash is thrown into the kneading machine 10. To be done.

Thereafter, a predetermined amount of sand, cellulose ether, and kneading water for one batch are introduced into the kneading machine 10 from the aggregate storage tank 3, the separation preventing agent storage tank 4, and the kneading water storage tank 5, respectively, and all of them are kneaded. It is kneaded in the machine 10. It should be noted that the separation preventive agent (cellulose ether in this example) is better kneaded as a whole when it is added to the kneading machine 10 after the kneading of other components is completed. At this time, as described above, the viscosity control device 70 causes the silica supply mechanism 60,
The operations of the cement supply mechanism 62, the aggregate supply mechanism 63, the separation preventing agent supply mechanism 64, and the electromagnetic valve 6 are feedback-controlled, and the amount of the mixed paste fed into the kneading machine 10 is controlled. It FIG. 3 shows an example of the amount of one batch of the cement member, fly ash, sand, cellulose ether, and kneading water added to the kneading machine 1 at this time. After the kneading in the kneading machine 10 is completed, the discharge gate 13 is opened and the prepared mixed paste is poured into the solidification container 1 filled with miscellaneous solid waste. At the time of this injection, the exciter 11 of the discharge gate 13 and the exciter 12 below the solidification container 1 are operated. As a result, external stress (shearing force) is applied to the mixed paste, and the cement skeleton that is being generated is temporarily divided and softened (thixotropic), so that the apparent viscosity of the paste is temporarily reduced and the paste flow And the injection property can be improved and the paste injection time can be shortened. Further, since the bubbles inside the solidified body are swung to facilitate the escape to the outside, the deviation of the voids inside the solidified body can be promoted and the internal porosity can be reduced.

The solidified container 1 in which the injection is completed is transferred by the conveyor and enters the next batch. The transferred solidification container 1 is
It is left standing and cured to become a solidified body 14.

The operation of this embodiment will be described below.
The method for solidifying radioactive waste according to the present embodiment is (1) adding inorganic aggregate to reduce hardening heat of cement, and (2) adding segregation preventive agent to fluidity and uniformity of mixed paste. And (3) adding a silica-containing substance (fly ash) to improve the nuclide adsorption performance of cement. Hereinafter, this will be described with reference to FIGS.

(1) Reduction of Curing Heat Generation by Inorganic Aggregate The inventors of the present application first conducted the following experiment in order to examine the curing heat reducing effect of the inorganic aggregate. That is, a heat insulating material was wrapped around a solidification container of 2 liter scale, mixed pastes of various compositions were injected into the solidified container, and a thermocouple inserted in the central portion was used to change the temperature of the central part of the solidified body by this mixed paste. Was measured. The composition of the paste used is shown in FIG. 4 as a weight ratio with the cement member + the inorganic aggregate as 100%.

In FIG. 4, ordinary Portland cement was used as the cement member, and blast furnace slag and 6 were used as the inorganic aggregates.
No. silica sand was used. Further, a β-naphthalene-based high-performance water reducing agent was added as a water reducing agent for improving the kneading property. And the amount of inorganic aggregate (blast furnace slag + silica sand) is different as shown in Figure 3
Experiments were conducted on the composition of two cases.

The experimental results are shown in FIG. 5, in case 1, the amount of inorganic aggregate (silica sand + blast furnace slag) is 50.
%, The center temperature rose to nearly 90 ° C., and cracks due to thermal strain were observed in the solidified body. In case 2, the amount of inorganic aggregate is 60% and the amount of Portland cement is 40%.
As a result of diluting the solution with water, the maximum temperature dropped to 80 ° C. However, fine cracks still occurred in the solidified body. Case 3
Then, as a result of increasing the amount of inorganic aggregate to 75% and diluting the amount of Portland cement to 255, the maximum temperature is 60 ° C.
And cracks in the solidified body could be almost completely suppressed.

From FIG. 5, it was found that by mixing the aggregate with the cement member, it is possible to suppress the heat of curing of the solidified body and reduce the internal temperature without limiting the type of cement.

(2) Improvement of uniformity by anti-separation agent As shown in case 3 above, the addition of an appropriate amount of aggregate can sufficiently reduce the heat of curing. However, in this case 3, it was found that the uniformity of the solidified body was poor and breathing water was generated due to solid-liquid separation, and the temperature distribution was generated inside the solidified body because the sand and cement were not uniformly dispersed. . In order to eliminate such problems and improve the uniformity of the solidified product, a separation inhibitor having a function of adjusting the viscosity of the mixed paste (for example, cellulose ethers / polyethers commonly used in water-insoluble concrete) Water-soluble organic substances such as acrylamides are effective. This principle will be described in detail below.

It is generally known that the sedimentation velocity of particles in a medium follows the Stokes' equation. _{^{V = gD 2 (ρ 2 -ρ}} 1) / 18μ where, V: sedimentation velocity of the particles, g: gravitational acceleration, D: particle diameter, [rho _1: density of the medium, [rho _2: Density of the particles, mu: medium Therefore, when the above formula is considered for the mixed paste, if the separation inhibitor can be added to increase the viscosity μ of the kneading water by 100 times, the sedimentation speed V of the particles (cement / aggregate) in the mixed paste can be increased. Since it can be set to 1/100, sedimentation of cement particles or aggregate can be suppressed for a certain period of time until the setting and hardening of cement is started. As a result, the solidified body produced has higher uniformity and improved soundness. This action also has the effect of suppressing the generation of breathing water (supernatant water) after the mixed paste is poured into the solidifying container. When breathing water is generated in the waste solidified product, there is a risk that the solidified product is spilled during the transportation of the solidified product and spreads the pollution. However, such a phenomenon can be avoided by adding the separation preventing agent.

Based on the above principle, the inventors of the present application conducted an experiment for confirming the uniformity improving effect of the separation preventing agent. The experiment was performed in the same manner as in (1). The composition of the paste at that time (shown in the same weight ratio as in FIG. 4) is shown in FIG.
Case 4 is shown in FIG. The composition is almost the same as the cases 1 to 3 shown in FIG. 4, but the difference from the cases 1 to 3 is that alkyl cellulose is added as a separation preventing agent.

The experimental results are shown in FIG. FIG. 7 corresponds to FIG. 5 described above, and also shows Case 3 for comparison for comparison. 7, in case 4, no breathing water was generated and no separation of sand and cement was observed due to the addition of alkylcellulose as a separation inhibitor. Then, the maximum temperature dropped to over 50 ° C., and cracks due to thermal strain of the solidified body were completely suppressed.

As shown in FIG. 7, by mixing the aggregate and the separation preventing agent into the cement member, the curing heat generation is prevented and
It was found that a uniform solidified body can be created.

In the above cases 1 to 4, Co
In order to secure the -60 distribution coefficient (described later), 50% by weight of blast furnace slag powder as an aggregate is added, and in any case, the distribution coefficient of Co-60 is lower than that of cement alone (up to 3000). It showed a high value. This action will be described in detail in (3).

(3) Improvement of Nuclide Adsorption Performance by Amorphous Silica-Containing Substance As shown in Case 4 above, a uniform solidified body can be prepared by adding an appropriate amount of the separation preventing agent. However,
When water-soluble organic substances such as the above-mentioned cellulose ethers and polyacrylamides are used as separation inhibitors, radionuclides belonging to transition metals (Co-60, Ni-63, etc.)
It was found from an experiment by the inventors of the present application that the adsorption performance (partition coefficient) of cement with respect to water may decrease. This is shown in FIG. FIG. 8 shows Co-6 in the cement-solidified body by the mixed paste containing the separation preventing agent.
It shows the change with time of the distribution coefficient for 0. In addition, in this experiment, heating was performed at 80 ° C. to accelerate the reaction. The horizontal axis in Fig. 2 indicates the number of days after immersion of the mixed paste, and the vertical axis indicates when the mixed paste was injected (0 days elapsed).
The relative value of the distribution coefficient when the value in 1 is taken as 1. As shown in the figure, the distribution coefficient tended to decrease sharply immediately after the injection, and about one day after immersion, the distribution coefficient was about 0.
It is reduced by a factor of 1. It is speculated that the cause of this decrease is that the organic component dissolved in water and the transition metal element form a complex to become water-soluble. After the immersion was reduced to about 0.1 in one day, the value remained almost unchanged until 20 days later.

In order to solve the above problems and prevent the reduction of the distribution coefficient of the solidified body, the inventors of the present application have studied and found that a certain amount of amorphous silica should be added to the mixed paste. I understood. This will be described with reference to FIG. The inventors of the present application conducted the following experiment in order to examine the effect of improving the distribution coefficient by the amorphous silica. That is, taking blast furnace slag as an example of a substance containing amorphous silica, when the solidified body is formed by blast furnace cement consisting of this blast furnace slag and Portland cement, the content rate of blast furnace slag in the blast furnace cement (% by weight) Is varied from 0% to 90%, and the distribution coefficient value is measured after one or more days of immersion in which the value of the distribution coefficient stabilizes.

In FIG. 9, the horizontal axis represents the content of blast furnace slag, the vertical axis represents the distribution coefficient of cement to Co-60, and the separation inhibitor (cellulose ether type water-soluble organic substance) is not added. This is a relative value when the distribution coefficient is 1 (that is, 0.1 when added). In FIG. 9, when the blast furnace slag content in the blast furnace cement is increased from 0%, the amorphous silica contained in the blast furnace slag reacts with the alkali in the cement and Co
Since we change the cement into a form that can take in -60,
The Co-60 partition coefficient gradually increases. The distribution coefficient becomes 1 when the blast furnace slag content is about 30%, that is, the distribution coefficient can be recovered to the same level as when the separation preventing agent is not added. When the content of blast furnace slag is further increased, the content reaches about 50% and reaches a peak (about 3.4). However, if the blast furnace slag content exceeds 50%, the alkali component in the cement becomes insufficient, so the distribution coefficient decreases with increasing content, and the distribution coefficient becomes 1 again at a content of about 70%. The distribution coefficient sharply decreases with an increase and becomes about 0.08 at a content rate of 90%.

According to FIG. 9, the blast furnace slag content is 30% to 7%.
It was found that a distribution coefficient equal to or higher than that in the case where the separation preventing agent is not added can be secured in the range of 0%, and particularly, the distribution coefficient is remarkably improved in the range of 40% to 60%.
Content of amorphous silica in blast furnace slag is 40% to 50%
In consideration of that, the blast furnace slag content rate is 30
The ranges of% -70% and 40% -60% are respectively 10 in terms of the content of amorphous silica in the blast furnace cement.
.About.40% and 15 to 30%, and when expressed by the weight ratio of the amorphous silica to the Portland cement component, it becomes 1/9 to 2/3 and 3/17 to 7/13. Here, as described above, the components of the mixed paste of the method for solidifying radioactive waste according to the present embodiment are the cement member made of Portland cement stored in the cement storage tank 2 and the sand stored in the aggregate storage tank 3. , Kneading water storage tank 5
The kneading water stored in the storage tank, the cellulose ether stored in the separation preventing agent storage tank 4, and the fly ash containing amorphous silica stored in the silica storage tank 50 are provided. That is, by incorporating sand as the inorganic aggregate, it is possible to suppress the effect heat generation of the solidified body and reduce the internal temperature. In addition, since cellulose ether is blended as a separation preventing agent, separation and blockage of the aggregate can be prevented, a uniform solidified body can be prepared, and generation of breathing water can be reduced. In addition, the fluidity of the mixed paste can be improved and voids inside the solidified body can be reduced. Therefore, the reliability of the solidified body can be improved. Further, fly ash is blended as a substance containing amorphous silica, and the weight ratio of this amorphous silica to the Portland component is 0.33, which is greater than 3/17 and 7
When it is smaller than / 13, it is possible to obtain a larger partition coefficient than when cellulose ether is not added, that is, a high nuclide adsorption performance can be obtained.

By the way, in the method for solidifying radioactive waste according to the present embodiment, in addition to (1) reduction of curing heat generation (2) uniformization of mixed paste (3) each action of improving nuclide adsorption performance, (4) metal There is also an action of reducing the corrosion of wastes, that is, an action of reducing alkali corrosion of metal wastes due to the interaction with cement. This is shown in Figure 1.
0 and FIG. 11 will be described in detail below.

(4) Corrosion reduction of metal wastes Corrosion reduction by increasing viscosity Generally, the corrosion rate of metals depends on the diffusion rate of ions in water, and this diffusion rate of ions should be regarded as hard spheres. Therefore, it is inversely proportional to the viscosity of water. That is, when the separation preventing agent is added to the mixed paste, the viscosity of the kneading water increases and the diffusion rate of ions decreases, so that the corrosion rate of metal can be reduced.

Corrosion Reduction Based on Temperature Dependence Generally, the corrosion rate of metals shows a remarkable temperature dependence. FIG. 10 shows the temperature dependence of the generation rate of hydrogen generated in the alkali corrosion of aluminum, which is the most typical example of alkali corrosion. In FIG. 10, the horizontal axis indicates the temperature T [° C.].
And the reciprocal of temperature (1000 / T [1 / K]) and the hydrogen generation rate V [milliliter / cm ² · h] on the vertical axis. As shown in the figure, the higher the temperature is, the higher the hydrogen generation rate V tends to be. For example, T = 8.
Hydrogen generation rate at 0 ° C V ≈ 42 [milliliter / c
m ² · h] is the hydrogen generation rate V≈1 when T = 20 ° C.
It is a value nearly 30 times that of 5 [milliliter / cm ² · h]. Therefore, the hydrogen generation rate can also be reduced by adding the aggregate to the mixed paste and lowering the internal temperature of the mixed paste according to the principle described in (1). That is, metal corrosion can be reduced.

The inventors of the present application conducted the following experiments in order to confirm the effect of reducing metal corrosion as described above. This experiment was performed in the same manner as in (1) and (2), that is, by wrapping a heat insulating material around a solidification container of 2 liter scale, and using the cement paste (cases of various compositions) used in (1) and (2). 1 to Case 4 (see FIGS. 4 and 6) were injected into a solidification container to solidify a metal test piece of an aluminum sash. Then, at this time, the cumulative value of the hydrogen generation amount was measured until the hardening of the cement due to the corrosion of the test piece was completed. The results of this experiment are shown in FIG.

In FIG. 11, cases 2 to 4 and case 1
Comparing with the above, first, in Case 2, the hydrogen generation amount is reduced by the principle described above in response to the decrease in the solidified body internal temperature due to the supply of aggregate (see FIG. 5), and in Case 3 further. It can be seen that the hydrogen generation amount is further reduced because the internal temperature of the solidified body is lowered. In case 4, the temperature inside the solidified body is further lowered (see FIG. 7).
In addition to the above), the hydrogen generation amount is also reduced by the addition of the separation preventing agent alkyl cellulose, and as a result, the hydrogen generation amount is decreased by an order of magnitude more than in the cases 2 and 3. You can see that
Further, in the solidified bodies of Cases 1 to 3, many escape holes for hydrogen generated were observed in the upper portion of the solidified body, but in Case 4, it did not occur.

From FIG. 11, it was found that metal corrosion can be reduced by adding the aggregate to the cement member, and further addition of the separation preventing agent can further improve the corrosion reducing effect.

In the method for solidifying radioactive waste according to the present embodiment, the sand stored in the aggregate storage tank 3 and the cellulose ether stored in the separation preventing agent storage tank 4 are contained in the mixed paste, It is possible to suppress the reaction between the metal waste contained in the radioactive miscellaneous solid waste in the solidification container 1 and the cement and to reduce the corrosion rate of the metal.

The second embodiment of the present invention will be described with reference to FIG. The present example is an example of a solidifying device in which each component other than the kneading water of the mixed paste is mixed in a powder state before being introduced into the kneader. FIG. 12 shows the entire configuration of the radioactive waste solidifying apparatus according to the present embodiment. The same members as those in the first embodiment are designated by the same reference numerals. In FIG.
The main difference between the solidifying device 2000 of this embodiment and the solidifying device 1000 of the first embodiment is that the silica supplying mechanism 60, the cement supplying mechanism 62, the aggregate supplying mechanism 63, the separation preventing agent supplying mechanism 64, and the kneading machine 10. And a cement supply mechanism 62, which is provided between the silica supply mechanism 60 and the fly ash.
Pre-mixer 15 for mixing Portland cement from No. 5, sand from aggregate supplying mechanism 63, and cellulose ether from separation preventing agent supplying mechanism 64 in a powder state to form a mixed powder.
And a mixed powder supply mechanism 75 having a function of quantitatively supplying this mixed powder from the premixer 15 to the kneading machine 10. The kneading machine 10 is supplied from the mixed powder supply mechanism 75. That is, the mixed powder and the kneading water supplied from the kneading water storage tank 5 through the electromagnetic valve 6 are kneaded. Other configurations are almost the same as those of the radioactive waste solidifying apparatus 1000 of the first embodiment.

According to this embodiment, in addition to the effects of the first embodiment, there are the following effects. That is, in the first embodiment shown in FIG. 1, the silica supply mechanism 60, the cement supply mechanism 62, the aggregate supply mechanism 63, the separation preventing agent supply mechanism 64, and the electromagnetic valve 6 are kneaded by independent pipelines. It is guided to the machine 10 and the problem of space for arranging these many pipelines, and the amount of fly ash, Portland cement, sand, and cellulose ether stored in each of them are adjusted to be compounded to the kneader 10. From the viewpoint of controllability and responsiveness in the case where the device 100 and the viscosity adjusting device 70 are individually controlled, these conduits could not be laid long. Therefore, it is necessary to arrange all the members shown in Fig. 1 including these storage tanks, piping, and supply mechanism in the radiation controlled area, and after using for a certain period of time, all these members must be treated as radioactive waste. I had to do it. However, in the solidifying device 2000 of this embodiment, fly ash, Portland cement, sand, and cellulose ether are once mixed in the premixer 15. That is, since the mixed powder supply mechanism 75 supplies the mixed powder to the kneading machine 10 through one pipe 76, the space for arranging the pipes can be reduced, and the components can be adjusted after the mixing. It is not performed, and the problem of quality of controllability / responsiveness does not occur. Therefore, it is possible to extend the pipe line 76 from the mixed powder supply mechanism 75 to the kneading machine 10 for a long time. Therefore, as shown in the drawing, the pipe line 76 serves as a boundary line of the radiation control area and is located upstream of the pipe line 76. The storage tank, supply mechanism, premixer 15 and the like can be arranged outside the radiation control area, and the maintainability of these can be improved. Further, since the number of members to be arranged in the radiation controlled area is reduced, the space in the radiation controlled area can be reduced and the amount of radioactive waste can be reduced.

Further, since the fly ash, the cement member, the sand and the cellulose ether are uniformly mixed before being mixed with the kneading water, the kneading time in the kneading machine 10 can be shortened and the solidification treatment speed can be increased. Can also be obtained.

In the above embodiment, the components of the mixed paste, such as fly ash, Portland cement, sand and cellulose ether, were mixed in the premixer 15, but these were mixed from the beginning. There is also a configuration in which it is stored in one storage tank. This modification is shown in FIG.
3 will be described. In FIG. 13, the solidifying device 2100 of this modification is different from the solidifying device 2000 of the second embodiment in that the silica storage tank 50, the cement storage tank 2, the aggregate storage tank 3,
One premix material storage tank 17 is provided instead of each of the separation adjusting agent storage tanks 4, and the premixed material in which fly ash, Portland cement, sand, and cellulose ether are already mixed is stored in advance as the premix material. These are mixed by the premix material supply mechanism 77 whose supply amount is controlled by the viscosity adjusting device 70.
This is the point at which 0 is supplied. Further, the boundary line of the radiation control area is provided in the pipe line 78 from the premix material supply mechanism 77 to the kneading machine 10, and the premix material storage tank 17 and the premix material supply mechanism 77 are outside the radiation control area. Will be installed in. The other points are almost the same as those of the solidification apparatus 2000 of the second embodiment.

According to this modification, as in the solidifying apparatuses 1000 and 2000 of the first and second embodiments, the supply amount / mixing ratio of fly ash / Portland cement / sand / cellulose ether and the viscosity of the mixed paste are finely adjusted. Although it cannot be controlled, the number of storage tanks and supply mechanisms can be reduced, and the premixer can be eliminated, so that the entire space of the solidification apparatus 2100 can be minimized and the cost can be reduced. Therefore, it is effective when the ratio of each component of the mixed paste is fixed in advance.

A third embodiment of the present invention will be described with reference to FIG. In this example, the separation preventing agent was introduced into the kneading water storage tank,
It is an example of the solidification device which mixes the separation preventing agent and the kneading water in advance in the kneading water storage tank. FIG. 14 shows the overall structure of the radioactive waste solidifying apparatus according to this embodiment. The same members as those in the first and second embodiments are designated by the same reference numerals. 14
In this regard, the main difference between the solidification device 3000 of this embodiment and the solidification device 1000 of the first embodiment is that the separation inhibitor supply mechanism 64 is connected to the kneading water storage tank 5 and the cellulose ether in the separation inhibitor storage tank 4 is connected. To the kneading water storage tank 5, the kneading water storage tank 5 is provided with a stirring blade 22 for stirring the mixture of cellulose ether and the kneading water, and the mixture in the kneading water storage tank 5 is passed through the electromagnetic valve 6. Kneading machine 1
0 to be kneaded with other components of the mixed paste.

Further, the kneading water storage tank 5 is provided with an electric motor 21 for driving the stirring blade 22, the load current of the electric motor 21 is measured by the ammeter 20, and the measured value is input to the viscosity control device 70. . The viscosity control device 70 stores in advance a load current value-viscosity calibration curve of the kneading water / cellulose ether mixture, which is used to convert the viscosity of the mixture. At this time, a torque meter for directly detecting the torque of the stirring blade 22 is provided, the torque value is input into the viscosity control device 70, and the torque-mixture viscosity calibration curve stored in the viscosity control device 70 is used to calculate the mixture The viscosity may be converted.
The other structure is the same as that of the second embodiment.

In the solidification operation in the above constitution, first, the separation preventing agent supply mechanism 64 is added to the kneading water storage tank 5 filled with water.
Then, the cellulose ether is added by, and the mixture is stirred by the stirring blade 22 to dissolve the cellulose ether. At this time, the viscosity in the kneading water storage tank 5 is detected by the viscosity controller 70 based on the load current value from the ammeter 20, and the separation preventing agent supply mechanism 64 is controlled so that the viscosity of the kneading water becomes a predetermined value. The supply amount of cellulose ether is adjusted. After the viscosity of the kneading water is adjusted in this manner, the kneading water is quantitatively supplied to the kneading machine 10 via the electromagnetic valve 6. The subsequent steps are the same as those in the first embodiment.

According to this embodiment, in addition to the effect obtained in the first embodiment, the viscosity of the kneading water can be finely adjusted, which is particularly suitable for preparing a mixed paste having a large water-cement ratio. . In addition, since the viscosity of the kneading water has increased from the initial stage of kneading, it has the effect of preventing sand settling in the kneading machine 10 and blockage of the discharge gate 13.

In the first to third embodiments described above, the fly ash, which is a substance containing amorphous silica, is stored in the silica storage tank 50. However, since fly ash also serves as an aggregate, The composition may be stored in the aggregate storage tank 3 together with the component of the inorganic aggregate. In this case, the silica storage tank 50 and the silica supply mechanism 60 can be omitted, and the operation of the aggregate supply mechanism 63 is controlled by the compounding control device 100 to adjust the supply amount of fly ash. The same applies when other amorphous silica-containing substances, blast furnace slag, silica fume, etc. are stored in the silica storage tank (described later).

Further, in the above-mentioned first to third embodiments,
The cement member was made of 100% Portland cement, but the present invention is not limited to this, and it is sufficient if it has a Portland component. When this cement member is fly ash cement containing fly ash beforehand, blast furnace cement containing blast furnace slag, or silica cement containing silica fume, fly ash, which is an amorphous silica-containing substance, blast furnace slag. , Silica fume is stored in the cement storage tank 2, and the silica storage tank 5
0 and the silica supply mechanism 60 can be omitted. In this case, only the operation of the cement supply mechanism 62 is controlled by the blending controller 100 to adjust the supply amount of fly ash or the like.

Furthermore, in the above-mentioned first to third examples, finally, the amorphous silica is finally made amorphous according to the content ratio of the amorphous silica in the fly ash and the content ratio of the Portland cement in the cement which are measured in advance. The operator himself sets the target supply amount of fly ash so that the weight ratio of silica and Portland cement becomes a predetermined value (for example, between 1/9 and 2/3, or between 3/17 and 7/13). And the target supply amount of cement are calculated, and the calculated value is used as the mixing control device 100.
However, the present invention is not limited to this, and the composition control device 100 may perform the calculation by this operator. That is, in this case, for example, the final target weight ratio of amorphous silica and Portland cement is 1 /
When the operator sets and inputs between 9 and 2/3 or between 3/17 and 7/13, the operator also inputs the content of amorphous silica in fly ash and the content of Portland cement in cement. A target supply amount of fly ash and cement that achieves the set target weight ratio is calculated, and the supply amount control unit controls the operations of the cement supply mechanism 62 and the silica supply mechanism 60 based on this.

Further, in the above-mentioned first to third embodiments,
Fly ash was used as the amorphous silica-containing substance stored in the silica storage tank 50. At this time, the weight ratio of the amorphous silica to the Portland cement component was 1/9 to 2
The conditions of / 3 and 3/17 to 7/13 are 3/17 to 1 and 1/4 to 2/3 in terms of the weight ratio of fly ash to the Portland cement component. The amorphous silica-containing substance is not limited to fly ash, but may be blast furnace slag, silica fume, or the like. In this case, the conditions of the weight ratio of the amorphous silica to the Portland cement component of 1/9 to 2/3 and 3/17 to 7/13 are converted into the weight ratio of the blast furnace slag / silica fume to the Portland cement component, In blast furnace slag, it becomes 3/7 to 7/3 and 2/3 to 3/2, and in silica fume, it becomes 1/9 to 3/7 and 3/17 to 1/3.
This is arranged and shown in FIG.

Further, in the above-mentioned first to third embodiments, sand is used as the inorganic aggregate stored in the aggregate storage tank 3, but the present invention is not limited to this, and does not cause an exothermic reaction with Portland cement (that is, A non-reactive inorganic aggregate (which has no reactivity with Portland cement) is sufficient, and for example, gravel / artificial lightweight aggregate can also be used.

Further, in the above-mentioned first to third embodiments,
As the separation preventing agent, an alkyl cellulose such as methyl cellulose, a carboxyalkyl cellulose such as hydroxyethyl cellulose, that is, a cellulose ether is used. Can be used, and the same effect can be obtained in this case as well. The separation preventing agent is preferably a powdery one, but can also be used as a liquid. However, in the case of a liquid separation inhibitor,
Since the separation preventing agent itself has a considerably high viscosity, a structure capable of pressurizing and injecting into the separation preventing agent supply mechanism 64 is required.

Further, in the above first to third embodiments, in order to supplement the deterioration of the cement adsorption performance due to the organic ether separation inhibitor cellulose ether, as described in (3), the amorphous silica is contained. Although the substances were added at a predetermined ratio, the use of an inorganic separation preventing agent does not cause such a decrease in adsorption performance, so that the amorphous silica-containing substance is not always necessary. In this case, natural clay minerals having good water absorption (water retention) such as bentonite, montmorillonite, clinobuchilorite, and acid clay are stored in the separation preventing agent storage tank 4 as the inorganic separation preventing agent, and the separation preventing agent is supplied. It is introduced into the kneading machine 10 by the mechanism 64. Further, since the amorphous silica-containing substance is unnecessary, the silica storage tank 50, the silica supply mechanism 60, and the compounding control device 100 can be omitted, and the supply amount of each component is controlled only by the viscosity control device 70. . Also in this case, the same effect as that of the above-mentioned embodiment is obtained. In addition, the cation exchange action of natural clay minerals also has the secondary effect of improving the distribution coefficient of cation nuclides such as Cs and Sr.

Fourth Embodiment of the Present Invention FIGS. 16 and 17
Will be described. This example is an example of a solidifying device for kneading and solidifying a molded body of a radioactive chemical waste liquid. FIG. 16 shows the overall configuration of the radioactive waste solidifying apparatus according to the present embodiment.
The same members as those in the first to third embodiments are designated by the same reference numerals. In FIG. 16, the solidifying device 4000 of the present embodiment is different from the solidifying device 1000 of the first embodiment mainly in that the silica storage tank 50, the silica supply mechanism 60, the aggregate storage tank 3, the aggregate supply mechanism 63, and the compounding. The controller 100 is omitted, and a waste storage tank 80 in which a molded body of a concentrated chemical waste liquid containing sodium borate as a main component (for example, a sodium borate molded body generated from a PWR plant) and the molded body are transferred to the kneading machine 10. The point is that a waste supply mechanism 90 for supplying is provided. The waste supply mechanism 90 is similar in configuration to the other supply mechanisms and has a fixed-quantity supply function.
0 controls the amount of the molded body supplied to the kneading machine 10. Further, unlike the solidifying device 1000 of the first embodiment, 100% quick-hardening Portland cement is used for the cement member in the cement storage tank 2, and the inorganic separation inhibitor is used as the separation prevention agent in the separation prevention agent storage tank 4. Acid clay (Shilton A, manufactured by Mizusawa Chemical Co., Ltd.) was used. Further, the β-naphthalene-based high-performance water reducing agent stored in the water reducing agent storage tank (not shown) is supplied to the kneading machine 10 by the water reducing agent supply mechanism. The other structure is almost the same as that of the first embodiment.

With the above structure, in the kneading machine 10,
The concentrated chemical waste liquid molded body from the waste storage tank 80, the quick-hardening Portland cement from the cement storage tank 2, the acid clay from the separation inhibitor storage tank 4, and the kneading water from the kneading water storage tank 5 are kneaded to form a mixed paste. Is created and the discharge gate 1
3 is poured into the solidification container 1 and solidified. FIG. 17 shows the weight ratio of each component of this mixed paste (when the rapid-setting Portland cement is 100%). Note that FIG.
Shows the weight ratio of the mixed paste of the comparative example which was cured by removing the acid clay in order to confirm the effect of this example.

In the comparative example, as a result of visually observing the solidification state in the solidification container 1 after injecting the mixed paste, the concentrated chemical waste liquid which is a radioactive waste despite the fact that the rapid hardening Portland cement was used as the cement member. The molded body of No. 1 floated, and the layer containing only cement and the layer containing the molded body were completely separated. Furthermore, it was found that the cement in the part in contact with the waste liquid molded body was not completely solidified. This is because sodium borate, which is the main component of the molded body, reacts with calcium in the cement to form calcium borate, which inhibits the hydration reaction of the cement.

On the other hand, in the present example in which the acid clay as the separation preventing agent was added, the viscosity of the kneading water increased and the concentration of the concentrated paste was changed from the mixed paste of low density according to the principle described in (2) of the first example. Floating separation of the waste liquid molded body is suppressed, and the setting of cement is completed before the floating separation occurs, so that a uniform solidified body can be obtained. In addition, since the viscosity of the kneading water is increased in this way, the diffusion coefficient of ions in water is reduced by the principle described in (4) of the first embodiment, thereby reducing the dissolution rate of the molded body. Therefore, the inhibition of the hardening reaction of cement due to the elution of borate ions can be suppressed. That is, the interaction between waste and cement can be reduced, and the soundness of the solidified body can be improved. And, at this time, since the acid clay which is an inorganic type is used as the separation preventing agent, the decrease of the Co-60 distribution coefficient as in the case of using the organic separation preventing agent does not occur, and the nuclide adsorption performance of the cement is deteriorated. Never.

In the above embodiment, the case where the molded body of the concentrated chemical waste liquid containing sodium borate as the main component is solidified as the radioactive waste has been described. Molded body (for example,
The same effect can be obtained when cementing the sodium sulfate molded body). At this time, as an interaction reaction between the cement and the waste liquid molded body, sodium sulfate and cement may react to form an ethrin guide and the solidified body may expand and deteriorate, but such an event can be avoided. It will be possible. Further, at this time, this effect can be further ensured by using, as the cement, a sulfate resistant cement which is not easily deteriorated by sulfuric acid.

In addition, although the inorganic separation preventing agent is used as the separation preventing agent in the above-mentioned embodiments, the present invention is not limited to this, and the organic separation preventing agent is used and the first to third separation separating agents are used.
The silica storage tank 50 and the silica supply mechanism 6 are the same as those in the above embodiment.
0 and the compounding control device 100 may be provided to supply an appropriate amount of the amorphous silica-containing substance (fly ash or the like) to the kneading machine 10. Also in this case, the same effect is obtained.

A fifth embodiment of the present invention will be described with reference to FIGS. This example is an example of a solidifying device for kneading and solidifying radioactive incineration ash. FIG. 18 shows the overall configuration of the radioactive waste solidifying apparatus according to the present embodiment. The same members as those in the first to fourth embodiments are designated by the same reference numerals. FIG.
In the above, the main difference of the solidification apparatus 5000 of the present embodiment from the fourth embodiment is that the radioactive waste incineration ash (or its compact) generated from the nuclear power plant is stored in the waste storage tank 80. In the cement storage tank 2, blast furnace cement having a blast furnace slag content of 70% by weight (that is, the weight ratio of blast furnace slag to Portland component is 7/3, and the weight ratio of amorphous silica to Portland component is 2/3). ) Is stored. The other structure is almost the same as that of the fourth embodiment.

Next, the operation of this embodiment will be described. Generally, when the incinerated ash is solidified with cement, there are problems that the ash absorbs kneading water and the kneading property is deteriorated, and that the fine metal powder in the ash is corroded by alkali to generate hydrogen. Conventionally,
In order to improve the former, the water-cement ratio was set to a considerably large value (0.5 or more), which unavoidably caused breathing water. Therefore, as described in the first embodiment (2), generation of breathing water can be prevented by adding a separation preventing agent to improve the uniformity of the mixed paste. Also in the latter case, the generation of hydrogen can be reduced by increasing the viscosity with the separation preventing agent, as described in the first embodiment (4).

From the above viewpoints, the inventors of the present application conducted the following solidification experiment as a simulation experiment in order to confirm the breathing water generation prevention effect and the hydrogen generation reduction effect by the separation preventing agent. And the results shown in FIG. 20 were obtained. That is, FIG. 19 shows furnace bottom ash generated from an incinerator for municipal solid waste as simulated incineration ash, blast furnace cement in which the weight ratio of blast furnace slag to Portland component is 7/3 as cement member, and carboxycellulose ether as separation inhibitor. The liquid surface of the mixed paste prepared by pouring is mixed into a beaker to be solidified, and the change over time in the thickness of the breathing water layer is measured. On the other hand, FIG.
Is the one in which the same mixed paste was sealed in another container having a sampling pipe attached to the gas phase part, and the amount of hydrogen generated was measured by water replacement. The composition of the components of the mixed paste used in these experiments is shown in FIG. At this time, as a comparative experimental example, the measurement was performed also in the case where carboxycellulose ether was not added.

First, the experimental results shown in FIG. 19 will be described. In FIG. 19, the horizontal axis represents the elapsed time after injection, and the vertical axis represents the thickness of the breathing water tank with respect to the total thickness of the mixed paste. In the comparative experimental example in which the separation inhibitor carboxyl ether was not added, the breathing water was gradually generated after about 2 hours and increased with time, and finally the amount reached close to 4%.
On the other hand, in the present experimental example in which the separation preventing agent was added, 30
No generation of breathing water was observed even after a lapse of time. Further, in the comparative experiment example, when the bleeding water was removed, a layer of incinerated ash was formed on the surface over a depth of several cm, that is, it was found that incinerated ash having a fine particle size and light weight floated and was released from the paste. However, in this experimental example, there was no such separation of ash, and a uniform solidified body was prepared.

Next, FIG. 20 will be described. FIG.
Shows the cumulative amount of hydrogen generated until the cement paste hardens in the present experimental example and comparative example. As shown in the figure, the amount of hydrogen generated in this experimental example is about 1/10 of that in the comparative experimental example, and it can be seen that addition of carboxycellulose ether, which is a separation inhibitor, also exerts an effect of suppressing hydrogen generation. In the solidified body of the comparative experimental example, voids and cracks were generated due to the generated hydrogen, and strength reduction was observed, but in the solidified body of the present experimental example, no abnormality was observed in appearance and the strength did not change. Such an anti-separation agent is disclosed in Japanese Patent Application No. 4-
When used in combination with the corrosion inhibitor described in 249937, higher effects can be produced.

From FIGS. 19 and 20, it was found that, in the kneading and solidification of the incineration ash, by adding the separation preventing agent to the mixed paste, the effect of improving the uniformity of the solidified body and reducing the metal corrosion can be obtained. .

In the method for solidifying radioactive waste according to this embodiment, the incinerated ash (or its molded body) stored in the waste storage tank 80 and the cement member (blast furnace cement) stored in the cement storage tank 2 are used. The carboxyl cellulose ether stored in the separation preventing agent storage tank 4 and the kneading water stored in the kneading water storage tank 5 are kneaded in the kneading machine 10 to form a mixed paste. That is, by incorporating carboxyl cellulose ether as the separation preventing agent, a uniform solidified product can be prepared and the generation of breathing water can be reduced. Further, blast furnace slag, which is a substance containing amorphous silica, is mixed in the cement member, and the weight ratio of the amorphous silica to the Portland component is 2/3, which is greater than 1/9 and 2
When it is smaller than / 3, a larger partition coefficient, that is, a higher nuclide adsorption performance can be obtained as compared with the case where no carboxyl cellulose ether is added. Further, it is possible to suppress the reaction between the metal waste contained in the incineration ash and the cement and to reduce the corrosion rate of the metal.

In the fourth and fifth embodiments, radioactive waste, cement material, separation preventing agent and kneading water are mixed in the kneading machine 10 and then injected into the solidification container 1.
It was a so-called kneading and solidification method, but the present invention is not limited to this, and it is an injection and solidification method in which radioactive waste is previously placed in the solidification container 1 and the mixed paste is injected as in the first to third embodiments. May be. At this time, the first to third
The aggregate storage tank 3 may be provided and the aggregate may be added to the mixed paste as in the above embodiment. Also in this case, the same effect is obtained.

In the fourth and fifth embodiments, each component was introduced directly from each storage tank to the kneader 10.
As in the second embodiment shown in FIG. 12, a pre-mixer may be provided to pre-mix other than the kneading water.
It may be premixed and supplied as in the modification shown in FIG. Also in this case, the same effect is obtained.

Further, in the first to fifth embodiments, no means for cooling the kneading water is provided, but at least one of the kneading water storage tank 5 and the electromagnetic valve 6 has a cooling mechanism for cooling the kneading water. There is also a configuration to provide, in this case,
Since the initial temperature of the mixed paste can be lowered,
For example, it is effective when it is desired to reduce the aggregate.

Further, in the above-mentioned first to fifth embodiments,
The main component of the solidifying material was cement, but it is not limited to this, and for example, a configuration using mortar, concrete or the like is also conceivable.

Further, in the above-mentioned first to fifth embodiments, the vibrating machine 1 is attached to the solidification container 1 and the discharge gate 13, respectively.
2 and the vibration exciter 11 are provided, but either one may be used,
Also in this case, the same effect is obtained.

Further, in the above-mentioned first to fifth embodiments,
The load current value of the motor 9 for driving the stirring blade 9 was detected by the ammeter 7, and the viscosity of the mixed paste was converted by the calibration curve of the load current value-mixed paste viscosity stored in the viscosity control device 70. However, a torque meter for directly detecting the torque of the stirring blade 9 is provided, the torque value is input into the viscosity control device 70, and the torque-mixing paste viscosity calibration curve stored in the viscosity control device 70 is used for mixing. The viscosity of the paste may be converted. Also in this case, the same effect is obtained.

Further, in the above-mentioned first to third and fifth embodiments, further detailed components of Portland cement are not particularly limited, but those containing 30% by weight or more of dicalcium silicate (moderate). There is also a configuration using hot Portland cement). In this case, since the curing speed of the solidified body becomes slow, there is an effect that it is possible to further lower the maximum attainable temperature (see FIGS. 5 and 7) in the heat of curing.

[0130]

EFFECTS OF THE INVENTION According to the present invention, the internal heat can be reduced by suppressing the hardening heat of the solidified body with the inorganic aggregate, and the cement particles and the aggregate can be separated by the viscosity modifier. As a result, the setting of cement is completed before it is separated, and a uniform solidified body can be created. Therefore,
It is possible to suppress solid-liquid separation, reduce generation of breathing water, improve fluidity of the mixed paste, and reduce voids inside the solidified body. The reliability of the solidified body can be improved. further,
Since the inorganic aggregate contains the amorphous silica component in which the weight ratio of the cement to the Portland cement component is 1/9 or more and 2/3 or less, it is possible to improve the nuclide adsorption performance of the cement which has been lowered by the addition of the viscosity modifier. Can be recovered. Further, at this time, since the internal temperature is reduced by the inorganic aggregate, the corrosion of the metal contained in the waste can be reduced, and since the viscosity modifier is added, the corrosion can be further reduced.

Further, according to the present invention, it is possible to prevent the low-density incinerated ash and the like from being floated and separated from the mixed paste, and the setting of the cement is completed before the cement is floated and separated, so that a uniform solidified body is produced. can do. Therefore, solid-liquid separation can be suppressed, the generation of breathing water can be reduced, the fluidity of the mixed paste can be improved, and the voids inside the solidified body can be reduced. Therefore, the reliability of the solidified body can be improved. The weight ratio of cement to Portland cement component is 1 /
Since it contains the amorphous silica component of 9 or more and 2/3 or less, it is possible to recover the nuclide adsorption performance of the cement which has been lowered by the addition of the viscosity modifier. At this time, since a viscosity modifier is added, metal corrosion can be reduced.

Further, according to the present invention, since a viscosity adjusting agent for inorganic substances, for example, natural clay minerals such as bentonite, montmorillonite, clinobuchilorite, or acid clay is used, it is not possible to recover the nuclide adsorption performance. There is no need to add crystalline silica. Also, the cation exchange action of the natural clay mineral can improve the adsorption performance for cation nuclides such as Cs and Sr.

Further, according to the present invention, the operator sets the supply amount setting means in accordance with the amorphous silica content in the amorphous silica-containing substance and the Portland cement component content in the cement which are measured in advance. The amount of supply of the amorphous silica-containing substance and cement to the kneader is set, and the operations of the cement supply means and the silica supply means are controlled by the supply amount control means according to the set supply amount, so that the port included in the cement is controlled. Amorphous silica can be kneaded in an arbitrary ratio with respect to the land component.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an overall configuration of a solidification apparatus for carrying out a method for solidifying radioactive waste according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a control content in a supply amount control unit.

FIG. 3 is a diagram showing an example of an input amount of one batch into a kneading machine of cement member, fly ash, sand, cellulose ether, and kneading water.

FIG. 4 is a diagram showing a composition of a mixed paste used in an experiment for studying reduction of heat generation by hardening due to an inorganic aggregate.

FIG. 5 is a diagram showing a result of an experiment for examining reduction of heat generation by hardening by an inorganic aggregate.

FIG. 6 is a diagram showing a composition of a mixed paste used in an experiment for confirming the uniformity improving effect of the separation preventing agent.

FIG. 7 is a diagram showing a result of an experiment for confirming the uniformity improving effect of the separation preventing agent.

FIG. 8 is a view showing a change with time of a distribution coefficient with respect to Co-60 in a cement-solidified body with a mixed paste containing a separation preventing agent.

FIG. 9 is a diagram showing the results of an experiment for confirming the partition coefficient improving effect of amorphous silica.

FIG. 10 is a diagram showing the temperature dependence of the generation rate of hydrogen generated in the alkali corrosion of aluminum.

FIG. 11 is a diagram showing a result of an experiment for confirming a metal corrosion reducing effect of the aggregate and the separation preventing agent.

FIG. 12 is a conceptual diagram showing the overall configuration of a solidification apparatus for carrying out the method for solidifying radioactive waste according to the second embodiment of the present invention.

FIG. 13 is a conceptual diagram showing an overall configuration of a solidification apparatus for carrying out a method for solidifying radioactive waste according to a modification of the second embodiment of the present invention.

FIG. 14 is a conceptual diagram showing the overall configuration of a solidification apparatus for carrying out the method for solidifying radioactive waste according to the third embodiment of the present invention.

FIG. 15 is a diagram showing values when the weight ratio condition of amorphous silica is converted into the weight ratio of fly ash / blast furnace slag / silica fume.

FIG. 16 is a conceptual diagram showing the overall configuration of a solidification apparatus for carrying out the method for solidifying radioactive waste according to the fourth embodiment of the present invention.

FIG. 17 is a diagram showing a composition of a mixed paste.

FIG. 18 is a conceptual diagram showing the overall configuration of a solidification apparatus for carrying out the method for solidifying radioactive waste according to the fifth embodiment of the present invention.

FIG. 19 is a diagram showing a result of an experiment for confirming an effect of preventing the generation of breathing water by the separation preventing agent.

FIG. 20 is a diagram showing the results of an experiment for confirming the hydrogen generation reducing effect of the separation preventing agent.

FIG. 21 is a diagram showing a composition of a mixed paste.

[Explanation of symbols]

 1 Solidification container 2 Cement storage tank 3 Aggregate storage tank 4 Separation inhibitor storage tank 5 Kneading water storage tank 6 Electromagnetic valve 7 Ammeter 8 Electric motor 9 Stirrer blade 10 Kneader 11 Vibrator 12 Exciter 13 Discharge gate 14 Solidified body 15 Premix Machine 17 Premix material storage tank 20 Ammeter 21 Electric motor 22 Stirring blade 50 Silica storage tank 60 Silica supply mechanism 62 Cement supply mechanism 63 Aggregate supply mechanism 64 Viscosity adjusting agent supply mechanism 70 Viscosity control device 75 Mixed powder supply mechanism 77 Premix material Supply mechanism 80 Waste storage tank 90 Waste supply mechanism 100 Mixing control device 1000 Solidifying device 2000 Solidifying device 2100 Solidifying device 3000 Solidifying device 4000 Solidifying device 5000 Solidifying device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshi Komori 7-2-1, Omika-cho, Hitachi-shi, Ibaraki Hitachi Energy Co., Ltd. Energy Research Institute (72) Kenji Noshita 7-chome, Omika-cho, Hitachi-shi, Ibaraki 2-1 Incorporated company Hitachi Ltd. Energy Research Laboratory (72) Inventor Tatsuo Izumida 3-1-1 1-1 Saiwaicho, Hitachi City, Ibaraki Hitachi Ltd. Hitachi Factory

Claims (32)

[Claims] 1. A method of solidifying radioactive waste by solidifying radioactive waste with a cement-based solidifying material containing a cement having a Portland cement component, an inorganic aggregate, kneading water, and a viscosity modifier, A method for solidifying radioactive waste, wherein an inorganic aggregate containing an amorphous silica component having a weight ratio to the Portland cement component of 1/9 or more and 2/3 or less is used. 2. The method of solidifying radioactive waste according to claim 1, wherein the radioactive waste is radioactive miscellaneous solid waste. 3. A method for solidifying radioactive waste, which comprises solidifying a radioactive waste with a cement-based solidifying material containing a cement having a Portland cement component, kneading water, and a viscosity adjusting agent, wherein the Portland cement is used as the cement. A method for solidifying radioactive waste, comprising using an amorphous silica component having a weight ratio to the component of 1/9 or more and 2/3 or less. 4. The method for solidifying radioactive waste according to claim 3, wherein the radioactive waste has at least one of an incineration ash, an incineration ash compact, and a concentrated chemical waste liquid compact. A method for solidifying radioactive waste, which is characterized by the following. 5. The method for solidifying radioactive waste according to claim 1 or 3, wherein the amorphous silica component has a weight ratio of 3/17 or more to the Portland cement component.
A method for solidifying radioactive waste, which is 13 or less. 6. The method for solidifying radioactive waste according to claim 1, wherein the amorphous silica component is contained in blast furnace slag contained in the cement, and the blast furnace slag is the Portland cement. A method for solidifying radioactive waste, characterized in that the weight ratio to the components is 3/7 or more and 7/3 or less. 7. The method of solidifying radioactive waste according to claim 1, wherein the amorphous silica component is contained in blast furnace slag contained in the cement, and the blast furnace slag is the Portland cement. A method for solidifying radioactive waste, characterized in that the weight ratio to the components is 2/3 or more and 3/2 or less. 8. The method of solidifying radioactive waste according to claim 1, wherein the amorphous silica component is contained in silica fume contained in at least one of the cement and the inorganic aggregate. This silica fume has a weight ratio of 1 to the Portland cement component.
/ 9 or more and 3/7 or less, The solidification method of radioactive waste characterized by the above-mentioned. 9. The method for solidifying radioactive waste according to claim 1, wherein the amorphous silica component is contained in fly ash contained in at least one of the cement and the inorganic aggregate. , This fly ash has a weight ratio of 3 to the Portland cement component.
/ 17 or more and 1 or less, The solidification method of radioactive waste characterized by the above-mentioned. 10. The method of solidifying radioactive waste according to claim 1 or 3, wherein the viscosity modifier is a water-soluble organic substance. 11. The method of solidifying radioactive waste according to claim 1 or 3, wherein the water-soluble organic matter contains at least one of cellulose ethers and polyacrylamides. Method. 12. The method of solidifying radioactive waste according to claim 1, wherein the Portland cement component is
A method for solidifying radioactive waste, which comprises 30% by weight or more of 2 calcium silicate. 13. The method for solidifying radioactive waste according to claim 1, wherein the cement, the inorganic aggregate and the viscosity modifier are
A method for solidifying radioactive waste, which is premixed in advance. 14. The method for solidifying radioactive waste according to claim 1, wherein the inorganic aggregate is a non-reactive inorganic aggregate made of a substance having non-reactivity with respect to the Portland cement component. Method for solidifying radioactive waste. 15. The radioactive waste solidifying method according to claim 14, wherein the non-reactive inorganic aggregate includes at least one of sand, gravel, and artificial lightweight aggregate. How to solidify things. 16. A method for solidifying radioactive waste, which comprises solidifying a radioactive waste with a cement-based solidifying material containing cement, kneading water, and a viscosity adjusting agent, wherein an inorganic substance is used as the viscosity adjusting agent. A method for solidifying radioactive waste, which is characterized by the following. 17. The method for solidifying radioactive waste according to claim 16, wherein the cement-based solidifying material further comprises an inorganic aggregate, and the radioactive waste is miscellaneous solid waste. Waste solidification method. 18. The method for solidifying radioactive waste according to claim 16, wherein the radioactive waste is at least one of incineration ash, incineration ash compact, and concentrated chemical waste liquid compact.
A method for solidifying radioactive waste, comprising: 19. The method of solidifying radioactive waste according to claim 16, wherein the inorganic substance comprises at least one of bentonite, montmorillonite, clinobutilolite, and acid clay. Solidification method. 20. A cement storage means, an aggregate storage means, a kneading water storage means, and a viscosity adjusting agent storage means for respectively storing cement having a Portland cement component, inorganic aggregate, kneading water, and a viscosity adjusting agent; And a kneader for kneading the cement, the inorganic aggregate, the kneading water, and the viscosity modifier, which are led from these storage means, into a mixed paste; the cement storage means, the aggregate storage means, the kneading water storage means, and the viscosity. Cement supply provided respectively between the modifier storage means and the kneader, and having a function of quantitatively supplying the cement, the inorganic aggregate, the kneading water, and the viscosity modifier from the respective storage means to the kneader. Means, aggregate supplying means, kneading water supplying means, and viscosity adjusting agent supplying means; and injection means for injecting the mixed paste kneaded by the kneading machine into a solidification container, wherein the solidification In a radioactive waste solidification device for injecting the mixed paste into a radioactive miscellaneous solid waste previously placed in a container for solidification treatment, silica storage means for storing a substance containing amorphous silica, and this silica A silica supply means provided between the storage means and the kneader, which has a function of quantitatively supplying the substance containing the amorphous silica to the kneader, and the substance containing the amorphous silica, and A supply amount setting means capable of setting a supply amount of cement to the kneading machine; and a supply amount control means for controlling the operations of the cement supplying means and the silica supplying means according to the supply amount set by the setting means. A device for solidifying radioactive waste, which is characterized in that 21. A radioactive waste having at least one of incinerated ash, a molded body of incinerated ash, and a molded body of concentrated chemical waste liquid, cement having a Portland cement component, kneading water, and a viscosity modifier. A waste storage means, a cement storage means, a kneading water storage means, and a viscosity adjusting agent storage means, which are respectively stored; kneading at least radioactive waste, cement, kneading water, and a viscosity adjusting agent introduced from these storage means And a kneading machine for forming a mixed paste; the waste storage means, the cement storage means, the kneading water storage means, and the viscosity adjusting agent storage means and the kneading machine, respectively. Waste material supplying means, cement supplying means, kneading water supplying means, and viscous material having a function of quantitatively supplying water and a viscosity adjusting agent from the respective storage means to the kneading machine. In the apparatus for solidifying radioactive waste, which comprises: a degree adjusting agent supplying means; and an injecting means for injecting the mixed paste kneaded by the kneader into a solidification container A silica storage means for storing a substance containing silica, and a function provided between the silica storage means and the kneader to quantitatively supply the substance containing the amorphous silica to the kneader. And a silica supply means, a supply quantity setting means capable of setting a supply quantity of the substance containing the amorphous silica and cement to the kneader, and the cement supply means according to the supply quantity set by the setting means, A solidification device for radioactive waste, comprising: a supply amount control means for controlling the operation of the silica supply means. 22. The apparatus for solidifying radioactive waste according to claim 20 or 21, wherein at least one of blast furnace slag, silica fume, and fly ash is stored in the silica storage means. The solidification device for radioactive waste, wherein the setting means is means capable of setting the amounts of blast furnace slag, silica fume, and fly ash supplied to the kneader. 23. The apparatus for solidifying radioactive waste according to claim 20 or 21, wherein vibration is applied to the mixed paste which is provided in the injection means and is injected into the solidification container.
And at least one of second vibrating means for vibrating the solidification container. 24. The apparatus for solidifying radioactive waste according to claim 20 or 21, wherein at least the viscosity monitor means for measuring the viscosity of the mixed paste in the kneader and the viscosity measured by the viscosity monitor means are used. Radioactive waste, further comprising a viscosity supply means for controlling the operations of the cement supply means, the kneading water supply means, the viscosity adjusting agent supply means, and the silica supply means, and adjusting the viscosity of the mixed paste to 5000 cp or less. A solidification device for things. 25. The radioactive waste solidifying device according to claim 23, wherein the viscosity control means is a means for adjusting the viscosity of the mixed paste to 1000 cp or more and 3000 cp or less. apparatus. 26. The apparatus for solidifying radioactive waste according to claim 23, wherein the kneader has a stirring blade for stirring the mixed paste in the kneader, and the viscosity monitoring means drives an electric motor for driving the stirring blade. Is a means for measuring the load current of the mixed paste and detecting the viscosity of the mixed paste based on the correlation between the load current and the viscosity which is measured and stored in advance. 27. The apparatus for solidifying radioactive waste according to claim 23, wherein the kneading machine has a stirring blade for stirring the mixed paste in the kneading machine, and the viscosity monitoring means measures the torque of the stirring blade. A solidification device for radioactive waste, comprising means for detecting the viscosity of the mixed paste based on the correlation between torque and viscosity that has been measured and stored in advance. 28. The apparatus for solidifying radioactive waste according to claim 20, wherein the cement supply means, the aggregate supply means,
Provided between the viscosity adjusting agent supplying means and silica supplying means and the kneader, the cement from the cement supplying means, the inorganic aggregate from the aggregate supplying means, the viscosity adjusting agent from the viscosity adjusting agent supplying means , And a premixer for mixing the substance containing the amorphous silica from the silica supply means in a powder state to form a mixed powder, and a function for quantitatively supplying the mixed powder from the premixer to the kneader Further comprising a mixed powder supply means, wherein the kneader is a means for kneading the mixed powder supplied from the mixed powder supply means and the kneading water supplied from the kneading water supply means. A solidification device for radioactive waste, characterized by being. 29. The apparatus for solidifying radioactive waste according to claim 21, which is provided between the waste supply means, the cement supply means, the viscosity modifier supply means, the silica supply means and the kneader, and at least: The radioactive waste from the waste supply means, the cement from the cement supply means, the viscosity modifier from the viscosity modifier supply means, and the substance containing amorphous silica from the silica supply means in a powder state A premixer to be mixed powder with a mixed powder, and further has a mixed powder supply means having a function of quantitatively supplying the mixed powder from the premixer to the kneader, and the kneader,
A solidification device for radioactive waste, comprising means for kneading the mixed powder supplied from the mixed powder supply means and the kneading water supplied from the kneading water supply means. 30. The apparatus for solidifying radioactive waste according to claim 20, wherein the premixer is installed outside a radiation controlled area. 31. The apparatus for solidifying radioactive waste according to claim 20 or 21, wherein at least one of the kneading water tank and the kneading water supply means is provided with a cooling means for cooling the kneading water. Equipment for solidifying radioactive waste. 32. The apparatus for solidifying radioactive waste according to claim 20 or 21, wherein the viscosity adjusting agent supplying means is means for supplying the viscosity adjusting agent from the viscosity adjusting agent storing means to the kneading water storing means. Yes, the kneading water storage means is provided with a stirring blade for stirring the mixture of the viscosity adjusting agent and the kneading water supplied by the viscosity adjusting agent supply means, the kneading water supply means, the kneading water supply means A solidification device for radioactive waste, which is a means for supplying the kneading water from the kneading water storage means to the kneading machine.