JP2022164323A - Radioactive waste liquid treatment method - Google Patents

Abstract

To provide a radioactive waste liquid treatment method capable of suppressing an increase in the generated amount of used adsorbent.SOLUTION: The radioactive waste liquid treatment method includes: a first adsorption step in which used adsorbent is made by allowing the adsorbent to adsorb the components to be removed contained in first water to be treated; a density range setting step to set a coexisting component concentration range in a range higher than the coexisting component concentration of the first water to be treated; a determination step to determine whether the coexisting component concentration of second water to be treated is within the coexisting component concentration range; and a second adsorption step in which the used adsorbent is allowed to adsorb the components to be removed contained in the second water to be treated whose coexisting component concentration is within the coexisting component concentration range.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a radioactive waste liquid treatment method, and more particularly to a radioactive waste liquid treatment method for removing radioactive substances from waste liquid containing radioactive substances, groundwater, seawater, rainwater, and the like.

Radioactive liquid waste generated from nuclear facilities contains various radionuclides such as cesium and strontium. As one method for removing the radionuclides, for example, there is a method of passing radioactive waste liquid to be treated (hereinafter referred to as "water to be treated") through an adsorbent capable of adsorbing and removing radionuclides. The used adsorbent generated in this adsorption treatment is stable but becomes radioactive waste, and therefore it is desired to reduce the amount of used adsorbent generated.

The water to be treated includes salt derived from seawater, groundwater, etc. In addition, freshwater from rivers, groundwater, water in contact with concrete used in buildings, and the like are included. Therefore, in addition to the radioactive substances to be removed, coexisting components that affect the adsorption performance of the adsorbent are present in the water to be treated. For example, coexisting components such as sodium ions and calcium ions are known to interfere with the adsorption of radionuclides by the adsorbent and reduce the adsorption performance. Under such conditions where sufficient adsorption performance cannot be obtained, the adsorption removal life of the adsorbent is shortened, and there is concern about an increase in the amount of adsorbent used and the amount of used adsorbent including radioactive waste.
In addition, as a method of reducing the amount of used adsorbent generated, a method of reusing the used adsorbent generated by treating the water to be treated for treatment of another water to be treated has been proposed (for example, See Patent Document 1).

JP 2020-153699 A

However, in the method of reusing the used adsorbent for treatment of another water to be treated, some of the adsorption sites of the used adsorbent already adsorb substances, so compared to a new adsorbent, The amount of substances that can be adsorbed is small. Therefore, the used adsorbent has a shorter adsorption removal life than the new adsorbent. As a result, the amount of used adsorbent used increases, and the amount of radioactive waste generated increases.

In order to solve the above-mentioned problems, the present invention provides a radioactive waste liquid treatment method capable of suppressing an increase in the amount of used adsorbent generated.

The radioactive waste liquid treatment method of the present invention comprises a first adsorption step of adsorbing a component to be removed contained in the first water to be treated to an adsorbent to prepare a used adsorbent, and a coexisting component concentration of the first water to be treated and a concentration range setting step of setting the coexisting component concentration range to a range as high as possible. Furthermore, a determination step of determining whether the coexisting component concentration of the second treatment target water is within the coexisting component concentration range; and a second adsorption step of adsorbing onto the spent adsorbent.

ADVANTAGE OF THE INVENTION According to this invention, the radioactive waste-liquid processing method which can suppress the increase in the generation amount of a used adsorbent can be provided.
Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

It is a flowchart showing a radioactive waste liquid treatment method. 1 is a schematic configuration diagram of a radioactive waste liquid treatment system used in a radioactive waste liquid treatment method; FIG. 4 is a graph showing the effect of coexisting component concentration on the life of new and used materials. This is a model of adsorption to an adsorbent in water to be treated with low concentrations of components to be removed and coexisting components. This is a model of adsorption to an adsorbent in water to be treated with high concentrations of components to be removed and coexisting components. FIG. 2 is a schematic configuration diagram of a radioactive waste liquid treatment system related to a radioactive waste liquid treatment method of a second embodiment; FIG. 4 is a diagram showing the relationship between the concentration ratio of components to be removed in the water to be treated and the life of the adsorbent. It is a figure which shows the relationship between the dilution ratio of the water to be treated, and the treatment amount ratio.

Hereinafter, embodiments and examples according to the present invention will be described with reference to sentences and drawings. However, the structures, materials, and other specific configurations shown in the following description are not limited to the embodiments and examples taken up here, and can be appropriately combined and improved within the scope of not changing the gist. It is possible. Elements that are not directly related to the present invention are omitted from the drawing.

<First embodiment of radioactive waste liquid treatment method>
A first embodiment of a method for treating radioactive waste liquid containing radioactive substances according to the present embodiment will be described.
FIG. 1 shows a flow chart representing the radioactive waste liquid treatment method according to the present embodiment. 2 shows a schematic configuration of a radioactive waste liquid treatment system used in the radioactive waste liquid treatment method of FIG. In the radioactive waste liquid treatment method of the present embodiment, the first treatment target water, which is a radioactive waste liquid containing the removal target component and the coexisting component, is processed to remove the removal target component using an adsorbent. Furthermore, using the used adsorbent used in the radioactive waste liquid treatment of the first target water, a treatment to remove the components to be removed from the second target water, which is a radioactive waste liquid containing the components to be removed and the coexisting components, is performed. conduct. In addition, in the following description, when it is not necessary to distinguish between the first water to be treated and the second water to be treated, they are simply referred to as water to be treated.

[Overview of radioactive waste liquid treatment method]
As shown in FIG. 1, the radioactive waste liquid treatment method first treats the first treatment target water using an adsorbent, adsorbs the components to be removed contained in the first treatment target water to the adsorbent, and adsorbs the used adsorption A material is prepared (step S1). Next, the component concentration range is set to a range higher than the component concentration of the first water to be treated (step S2). Next, it is determined whether or not the component concentration of the second water to be treated is within the set component concentration range (step S3).

If the component concentration of the second target water is not within the component concentration range (NO in step S3), the component concentration of the second target water is adjusted within the component concentration range (step S4). After adjusting the second water to be treated in step S4, the process returns to step S3 to measure the concentrations of the removal target component and the coexisting component in the second water to be treated and determine whether they are within the set concentration range.
If the component concentration of the second treatment target water is within the component concentration range (YES in step S3), the second treatment target water is treated using the adsorbent, and the removal target component contained in the second treatment target water has been used. It is made to adsorb to the adsorbent (step S5).
In this embodiment, the concentration may be ion concentration, weight concentration, volume concentration, or molar concentration.

[Overview of radioactive waste liquid treatment system]
The radioactive liquid waste treatment system shown in FIG. 2 also includes a first radioactive liquid waste treatment facility 1 and a second radioactive liquid waste treatment facility 2 .
The first radioactive liquid waste treatment facility 1 includes a first adjustment facility 10 in which the first water to be treated before treatment is adjusted, and a first treatment facility 12 to treat components to be removed from the first water to be treated. . A first adsorbent container 13 containing an adsorbent is provided in the first treatment facility 12 . Furthermore, the first radioactive liquid waste treatment facility 1 includes a first storage container 15 in which the first treated water generated by the treatment of the first target water in the first treatment facility 12 is stored.
The first adjusting equipment 10 and the first adsorbent container 13 of the first treatment equipment 12 are connected to the first liquid transfer equipment 11 for transferring the first water to be treated from the first adjusting equipment 10 to the first adsorbent container 13. connected by Also, the first adsorbent container 13 and the first storage container 15 are connected by a first water supply facility 14 that transfers the first treated water. In this way, the first radioactive liquid waste treatment facility 1 has a water flow system that allows the first water to be treated to pass through the first adjustment facility 10, the first treatment facility 12, and the first storage container 15, respectively. It is

The second radioactive liquid waste treatment facility 2 includes a second adjustment facility 20 in which the second water to be treated before treatment is adjusted, and a second treatment facility 22 to treat the components to be removed from the second water to be treated. . A second adsorbent container 23 containing an adsorbent is provided in the second treatment facility 22 . Furthermore, the second radioactive liquid waste treatment facility 2 includes a second storage container 25 that stores the second treated water generated by treating the second water to be treated in the second treatment facility 22 .
The second adjusting equipment 20 and the second adsorbent container 23 of the second treatment equipment 22 are the second liquid transfer equipment 21 for transferring the second water to be treated from the second adjusting equipment 20 to the second adsorbent container 23 connected by Also, the second adsorbent container 23 and the second storage container 25 are connected by a second water supply facility 24 for transferring the second treated water. In this way, the second radioactive liquid waste treatment facility 2 has a water flow system that allows the second water to be treated to pass through the second adjustment facility 20, the second treatment facility 22, and the second storage container 25, respectively. It is

The radioactive waste liquid treatment system shown in FIG. 2 also includes transfer equipment 3 for transferring the used adsorbent from the first adsorbent container 13 to the second adsorbent container 23 . That is, the radioactive waste liquid treatment system can transfer the used adsorbent generated in the first adsorbent container 13 by the treatment of the first target water to the second adsorbent container 23 through the transfer facility 3 . Thereby, the used adsorbent can be reused for the treatment of the second water to be treated.

Although FIG. 2 shows a configuration in which one first adsorbent container 13 and one second adsorbent container 23 are provided in the first treatment equipment 12 and the second treatment equipment 22, the first treatment equipment 12 And the number of adsorbent containers provided in the second treatment equipment 22 is not particularly limited, and a plurality may be provided.
In addition, the first liquid transfer equipment 11, the first water transfer equipment 14, the second liquid transfer equipment 21, the second water transfer equipment 24, and the transfer equipment 3 are provided with pumps and pump control units (not shown). By controlling the driving of the pump by , it is possible to transfer the waste liquid and the adsorbent.

The first adsorbent container 13 is filled with an adsorbent capable of adsorbing the components to be removed and the coexisting components contained in the first water to be treated. Therefore, by passing the first water to be treated from the first adjustment equipment 10 to the first adsorbent container 13, the components to be removed can be adsorbed and removed by the adsorbent.
The second adsorbent container 23 is filled with the used adsorbent used in the first adsorbent container 13 . Depending on the concentration of the coexisting components in the second water to be treated, the used adsorbent can adsorb the components to be removed and the coexisting components contained therein. If the concentration of the coexisting component in the second water to be treated is equal to or higher than a predetermined value, the second water to be treated is passed from the second adjustment equipment 20 to the second adsorbent container 23, thereby removing the component to be removed to the adsorbent. It can be removed by adsorption.
It should be noted that the removal of the components to be removed here means lowering the concentration of the components to be removed contained in the water to be treated to a certain value.

[Details of radioactive liquid waste treatment]
Next, details of an embodiment of radioactive waste liquid treatment to which the radioactive waste liquid treatment method shown in FIG. 1 and the radioactive waste liquid treatment system shown in FIG. 2 are applied will be described. In the following description, along with the flowchart of the processing method shown in FIG. 1, the reference numerals for the configuration shown in FIG. 2 are used as appropriate.

(Step S1)
First, in the flowchart of the radioactive waste liquid treatment shown in FIG. 1, in step S1, the first water to be treated is treated with an adsorbent.
In the first radioactive waste liquid treatment facility 1 of FIG. 2, the first water to be treated is sent from the first adjustment facility 10 through the first liquid transfer facility 11 to the first adsorbent container 13 of the first treatment facility 12 . The first water to be treated sent to the first adsorbent container 13 contacts the adsorbent contained in the first adsorbent container 13 . Thereby, the component to be removed contained in the first water to be treated is adsorbed by the adsorbent. In addition, coexisting components contained in the first water to be treated are also adsorbed by the adsorbent. As a result, the components to be removed and the coexisting components are removed from the first water to be treated.
Further, by the adsorption treatment of the first water to be treated, the adsorbent adsorbs the components to be removed and the coexisting components to become the used adsorbent. The first water to be treated from which the components to be removed and the coexisting components have been removed is sent to the first storage container 15 for the first treated water through the first water supply facility 14 .

Components to be removed contained in the water to be treated include, for example, radioactive substances such as strontium, cesium, cobalt, iodine, antimony, ruthenium, technetium, uranium, plutonium, americium, curium, and neptunium.

In addition, coexisting components are substances that coexist in the first water to be treated and the second water to be treated together with the above-mentioned components to be removed, such as sodium, potassium, magnesium, calcium, barium, chlorine, bromine, sulfuric acid, and Carbonic acid etc. are mentioned.
Moreover, the first water to be treated and the second water to be treated may contain the same element as the component to be removed and the coexisting component. In this case, the element is a radioactive isotope as a component to be removed and a stable isotope as a coexisting component. For example, radioactive isotopes of strontium and cesium are included in the aforementioned components to be removed, and stable isotopes of strontium and cesium are included in the coexisting components. In this way, the coexisting components include stable isotopes of the same elements as those listed as the components to be removed.

Examples of adsorbents include inorganic and organic adsorbents such as silicotitanate compounds, titanate compounds, zeolites, ferrocyanate compounds, metal organic framework (MOF) compounds, and ion exchange resins. . In the treatment of radioactive liquid waste, an appropriate adsorbent is selected and used according to the component to be removed. For example, when the component to be removed is strontium, it is preferable to use an adsorbent such as a silicotitanate compound that selectively adsorbs strontium.

(Step S2)
After the first target water treatment step S1 in FIG. 1, the concentration range for reusing the used adsorbent is set in step S2. In step S2, based on the component concentrations of the first water to be treated treated in step S1, the concentration range for reusing the used adsorbent is set.

The concentration range set in step S2 is based on the coexisting component concentration of the first water to be treated, and sets the concentration range of the coexisting component concentration of the second water to be treated when the used adsorbent is reused.
In addition, the concentration range of the coexisting component is set, and the concentration range of the component to be removed when the used adsorbent is reused is set based on the concentration of the component to be removed in the first water to be treated, which is treated in step S1 described above. May be set.
In the present embodiment, when there is no need to distinguish between coexisting component concentrations and removal target component concentrations, they are simply referred to as component concentrations. For example, when either the coexisting component concentration or the removal target component concentration may be used, or when both the coexisting component concentration and the removal target component concentration are used, the component concentration is simply indicated.

The concentrations of the components to be removed and the coexisting components in the first water to be treated are obtained by analyzing the first water to be treated before the first water to be treated is transported to the first radioactive waste liquid treatment facility 1 in FIG. good too. Alternatively, after the first water to be treated is transported to the first radioactive liquid waste treatment facility 1, for example, the first water to be treated stored in the first adjustment facility 10 may be sampled and analyzed.

The concentration ranges of the coexisting components and the components to be removed when reusing the used adsorbent are set as follows.
The concentration range of the coexisting component when reusing the used adsorbent is set to a range higher than the concentration of the coexisting component in the first water to be treated. Further, the concentration range of the components to be removed when the used adsorbent is reused is set to a range higher than the concentration of the components to be removed in the first water to be treated. As a result, the used adsorbent can further adsorb the components to be removed of the second water to be treated by utilizing the adsorption sites that do not adsorb the components to be removed.

The reason for setting the density range as described above will be described with reference to FIG.
FIG. 3 is an example of a graph (double logarithmic graph) showing the effect of coexisting component concentration on the service life of a new adsorbent (hereinafter also referred to as a new material) and a used adsorbent (hereinafter also referred to as a used material). be. The vertical axis is the life of the adsorbent, and the horizontal axis is the concentration of coexisting components contained in the water to be treated. In the graph shown in FIG. 3, the substance to be removed contained in the water to be treated is strontium (Sr), the coexisting component is sodium (Na), and the adsorbent is silicic acid. It is an evaluation of the adsorbent life when it is changed.
In addition, in FIG. 3, the graph when the adsorbent when treating the first water to be treated is a new material is shown by a broken line, and the graph when the adsorbent when treating the second water to be treated is a used material is indicated by a solid line.

In FIG. 3, both the life of the adsorbent and the concentration of the coexisting component are shown as relative values where the life of the new material is 1 when the concentration of the coexisting component is 1 in the first water to be treated. Therefore, when operating under conditions where the coexisting component concentration of the second water to be treated is equal to the coexisting component concentration of the first water to be treated, the coexisting component concentration (horizontal axis) of the graph for the used wood is 1.
As shown in area A of FIG. 3, when the coexisting component concentration (horizontal axis) is close to 1, that is, when the coexisting component concentrations of the first water to be treated and the second water to be treated are about the same, the used The life of the material is about 60% of that of new material. As described above, when the coexisting component concentrations of the first water to be treated and the second water to be treated are about the same, the life of the used material is obviously shorter than that of the new material.

On the other hand, as shown in region B of FIG. 3, the higher the concentration of the coexisting component, the smaller the difference in the life of the adsorbent between the new material and the used material. When the concentration of coexisting components in the water to be treated is low, the adsorption reaction between the adsorbent and the water to be treated is determined by the chemical equilibrium. This is because the chemical equilibrium is predominantly determined by the component ratio in the water to be treated. Therefore, the concentration range of the coexisting components in the second water to be treated when the used adsorbent is reused is set to a range higher than the concentration of the coexisting components in the first water to be treated. Preferably, the concentration range of the coexisting component in the second water to be treated when the used adsorbent is reused is set to twice or more the concentration of the coexisting component in the first water to be treated. As a result, the life of the used adsorbent can be extended, and an increase in radioactive waste due to the used adsorbent can be suppressed.

Also, as shown in region C of FIG. 3, when the concentration of the coexisting component is too high, for example, when the concentration of the coexisting component is 100 times the concentration of the coexisting component in the first water to be treated, the life of the adsorbent is greatly reduced to 1/100 or less. As a result, a practical adsorbent life cannot be secured. Further, as shown in region C of FIG. 3, the negative slope of the graph increases when the coexisting component concentration is about 100 times higher, and there is a tendency that the ratio of the decrease in life with respect to the increase in the coexisting component concentration increases. . Therefore, it is preferable to set the upper limit of the concentration range of the coexisting component when reusing the used adsorbent to be 100 times or less the concentration of the coexisting component in the first water to be treated.

In setting the coexisting component concentration range, the concentration range may be set for each type of coexisting component. In this case, the coexisting component concentration range for each type is preferably set to a range that is higher than the coexisting component concentration for each type of the first water to be treated and is 100 times or less than the coexisting component concentration of the first water to be treated. For example, when sodium is included as a coexisting component, it is preferable to set the sodium concentration to 25,000 ppm or less as the coexisting component concentration range. Moreover, when calcium is included as a coexisting component, it is preferable to set the calcium concentration to 100 ppm or less as the coexisting component concentration range. Furthermore, when chlorine is included as a coexisting component, it is preferable to set the chlorine concentration to 45,000 ppm or less as the coexisting component concentration range.

(adsorption model)
The reason why the performance of recycled used materials approaches that of new materials by increasing the concentration of coexisting components will be explained. FIG. 4 shows an adsorption model of water to be treated (low-concentration water) having low concentrations of components to be removed and coexisting components. In addition, FIG. 5 shows an adsorption model of water to be treated (high-concentration water) having high concentrations of components to be removed and coexisting components.

In addition, in the adsorption model described below, it is assumed that the reuse of the used material is to treat the second water to be treated, which has a higher concentration of the components to be removed than the first water to be treated. Furthermore, the water to be treated has a concentration of coexisting components sufficiently higher than the concentration of components to be removed.
As shown in FIG. 4, in the case of the new material 30, neither the component to be removed nor the coexisting component is adsorbed on the adsorption sites 31 of the new material 30 before the water to be treated is introduced. By bringing the water to be treated into contact with the new material 30 , the components to be removed and the coexisting components are adsorbed on the adsorption sites 31 and become adsorbed substances on the adsorption sites 31 . At this time, the adsorption in the treatment of low-concentration water is determined by the chemical equilibrium of the adsorption reaction between the component to be removed, the coexisting component, and the water to be treated. Therefore, the removal target component and the coexisting component are adsorbed on the adsorption site 31 at a predetermined ratio based on the chemical equilibrium between the removal target component concentration, the coexisting component concentration, and the adsorbent. The component to be removed and the coexisting component that have not been adsorbed are discharged to the subsequent processing equipment or storage container.

Also, in the treatment of low-concentration water using the used material 40 as shown in FIG. exists on the adsorption site 41 . In the low-concentration water, as in the case of the new material 30, the components to be removed and the coexisting components in the water to be treated are adsorbed at the adsorption sites 41 at a predetermined rate due to chemical equilibrium with the adsorbent. For example, some of the coexisting components on the adsorption sites 41 replace the components to be removed in the water to be treated according to chemical equilibrium, and the components to be removed are newly adsorbed. In addition, the removal target component and the coexisting component are newly adsorbed on the adsorption sites 41 that do not adsorb the adsorbent. The coexisting components that have detached from the adsorption site 41 are discharged to subsequent processing equipment or storage containers in the same manner as the components to be removed and the coexisting components that have not been adsorbed.

However, in the case of the used material 40, the components to be removed already exist on the adsorption sites 41, and the components to be removed on the adsorption sites 41 inhibit the adsorption of new components to be removed. For this reason, the adsorption amount is lower than that of the new material 30, and the amount of the component to be removed that is discharged to the subsequent processing equipment or storage container tends to increase. As a result, the life of the used material 40 is about 60% of that of the new material 30 as shown in area A of FIG.

In addition, as shown in FIG. 5, in the treatment of high-concentration water using the new material 30, as in the case of low-concentration water described above, the adsorption reactions between the components to be removed, the coexisting components, and the water to be treated are in chemical equilibrium. determined by However, since the concentrations of the components to be removed and the coexisting components in the water to be treated are high, the adsorption reaction between the components to be removed and the coexisting components and the adsorbent is strongly affected by the concentrations of the components to be removed and the coexisting components in the water to be treated. Therefore, in the treatment of high-concentration water shown in FIG. 5, the component to be removed in the water to be treated is adsorbed on the adsorption site 31 depending on the concentration of the component to be removed in the water to be treated, compared to the treatment of low-concentration water shown in FIG. The ratio of components to be removed increases.

Further, in the treatment of high-concentration water using the used material 40, as shown in FIG. However, in the treatment of high-concentration water, due to an increase in the concentration of coexisting components in the water to be treated, the ratio of the coexisting components in the water to be treated and the components to be removed that contribute to the chemical equilibrium of the adsorption reaction is lower than the ratio of the components on the adsorption sites 41. more than Therefore, as the component concentration of the water to be treated increases, the amount of some of the coexisting components on the adsorption sites 41 that are replaced with the components to be removed in the water to be treated increases, and the components to be removed are newly added to the adsorption sites 41. easier to be adsorbed. As a result, as shown in area B of FIG. life difference becomes smaller.
Therefore, when the used material 40 is reused, the concentration range of the coexisting components in the second water to be treated should be high, and should be set to a range higher than the concentration of the coexisting components in the first water to be treated. Furthermore, it is preferable to set it in a high concentration range of 2 times or more.

Moreover, it is preferable that the concentration of the coexisting component and the concentration of the component to be removed in the second water to be treated are higher than the concentration of the component to be removed in the first water to be treated. As described above, when the coexisting component concentration is high, the chemical equilibrium of the adsorption reaction depends on the component concentration of the water to be treated. A new material 30 can be approached. Furthermore, by increasing the concentration of the component to be removed, the adsorption ratio of the component to be removed to the coexisting component at the adsorption site 41 can be increased. Therefore, the removal target component concentration of the second water to be treated is made higher than the removal target component concentration of the first water to be treated, so that the adsorption performance of the used material 40 for the removal target component can be enhanced.
Preferably, when the used material 40 is reused, the concentration range of the components to be removed in the second water to be treated is set to be twice or more the concentration of the components to be removed in the first water to be treated.

More preferably, in the second water to be treated, the total concentration of the coexisting components and the components to be removed is higher than the total concentration of the coexisting components and the components to be removed in the first water to be treated. Due to the high total concentration of the coexisting component and the component to be removed, the ability of the used material 40 to adsorb the component to be removed can be further enhanced for the same reason as described above.
Preferably, when the used material 40 is reused, the concentration range of the total of the coexisting components of the second treatment target water and the removal target components is the total concentration range of the coexisting components of the first treatment target water and the removal target components. Set to 2 times or more.

The upper limit of the concentration range of the component to be removed from the second water to be treated when the used material 40 is reused is not particularly limited. For example, the upper limit of the concentration range of the components to be removed can be set to 10000 times or less, preferably 1000 times or less than the concentration of the components to be removed in the first water to be treated, as a feasible range for the operation of radioactive waste liquid treatment. .
In addition, the concentration of the component to be removed in the first water to be treated and the second water to be treated is preferably lower than the concentration of the coexisting component, and the concentration of the component to be removed is preferably sufficiently low, about 1/100 of the concentration of the coexisting component. .

(Step S3)
After the density range setting step S2 in FIG. 1, density determination processing is performed in step S3. In the concentration determination process, the coexisting component concentration range set in step S2 described above is compared with the concentration of the coexisting component in the second water to be treated. Then, it is determined whether or not the concentration of the coexisting component in the second water to be treated is within the set concentration range of the coexisting component.
When it is determined that the concentration of the coexisting component in the second water to be treated is within the coexisting component concentration range (YES in step S3), the process proceeds to step S5. Further, when it is determined that the concentration of the coexisting component in the second water to be treated is outside the coexisting component concentration range (NO in step S3), the process proceeds to step S4.

Further, when the removal target component concentration range is set in step S2, in addition to the comparison determination of the coexisting component concentrations, the set concentration range of the removal target component and the concentration of the removal target component of the second water to be treated are compared. do. Then, it is determined whether or not the concentration of the component to be removed in the second water to be treated is within the set concentration range of the component to be removed.
In this case, if both the coexisting component concentration and the removal target component concentration of the second treatment target water are determined to be within the set coexisting component concentration range and removal target component concentration range (YES in step S3), step S5 proceed to If either one of the coexisting component concentration and the removal target component concentration of the second water to be treated is determined to be outside the set concentration range (NO in step S3), the process proceeds to step S4.

Furthermore, when the total concentration range of the coexisting component and the removal target component is set in step S2, along with the comparison determination of the coexisting component concentration and the removal target component, the set total concentration range and the second treatment target water The total concentration of the coexisting component and the component to be removed is compared.
In this case, if the coexisting component concentration, the removal target component concentration, and the total concentration of these in the second treatment target water are determined to be within the set removal target component concentration range, coexisting component concentration range, and total concentration range ( YES in step S3), the process proceeds to step S5. Further, when it is determined that the concentration of any one or more of the second water to be treated is out of the set concentration range (NO in step S3), the process proceeds to step S4.

The concentrations of the components to be removed and the coexisting components in the second water to be treated are obtained by analyzing the second water to be treated before the second water to be treated is transported to the second radioactive waste liquid treatment facility 2 shown in FIG. may In addition, the concentrations of the components to be removed and the coexisting components in the second water to be treated are, after the second water to be treated is transported to the second radioactive waste liquid treatment equipment 2, It may be obtained by sampling and analyzing the water to be treated.

(Step S4)
In step S4, the second water to be treated is adjusted so that the coexisting component concentration and the removal target component concentration of the second water to be treated fall within the set concentration range. In the adjustment of the second water to be treated, the water quality can be adjusted by diluting the water by mixing with water or adjusting the concentration by adding a reagent. As the water to be mixed with the second water to be treated, for example, rainwater, groundwater, and seawater can be used. Further, it is also possible to perform an adjustment of concentrating the second treatment target water by performing a treatment such as evaporation or membrane separation.

After adjusting the second water to be treated in step S4, the process returns to step S3 to measure the concentrations of the removal target component and the coexisting component in the second water to be treated and determine whether they are within the set concentration range.
If it is determined that the adjusted second water to be treated is within the set concentration range (YES in step S3), the process proceeds to step S5. Further, when it is determined that the second treatment target water after adjustment is outside the set concentration range (NO in step S3), the second process is performed in step S4 until it is determined that it is within the concentration range in step S3. Repeat the adjustment process for the target water.

(Step S5)
In step S5, the second water to be treated within the set concentration range is brought into contact with the used adsorbent, and the components to be removed contained in the second water to be treated are adsorbed on the used adsorbent.

The used adsorbent prepared in step S1 described above is transferred from the first adsorbent container 13 of the first radioactive liquid waste treatment facility 1 shown in FIG. Transferred to container 23 .
Then, in the second radioactive liquid waste treatment facility 2 , the second water to be treated is sent from the second adjustment facility 20 through the second liquid transfer facility 21 to the second adsorbent container 23 of the second treatment facility 22 . The second water to be treated sent to the second adsorbent container 23 contacts the used adsorbent stored in the second adsorbent container 23 . Thereby, the component to be removed in the second water to be treated is adsorbed and removed by the used adsorbent. Furthermore, the used adsorbent becomes a secondary used adsorbent by adsorbing the component to be removed. The second water to be treated from which the components to be removed have been removed is sent to the second storage container 25 through the second water supply equipment 24 .

The secondary used adsorbent generated in the treatment of the second water to be treated described above may be radioactive waste, and may be transferred to another water treatment facility to treat the water to be treated that contains higher concentrations of components to be removed. may be reused for the processing of

According to the above-described method for treating radioactive waste liquid, when the used adsorbent is reused to treat the radioactive waste liquid, the deterioration of the adsorption performance of the components to be removed of the used adsorbent is suppressed. A decrease in life can be suppressed. Therefore, in the treatment of radioactive liquid waste, it is possible to reduce operating costs and reduce the amount of radioactive waste generated.

<Second embodiment of radioactive waste liquid treatment method>
Next, a second embodiment of the radioactive waste liquid treatment method will be described. In addition, in the following description of the second embodiment, detailed description of the same processing and configuration as those of the first embodiment will be omitted.

The radioactive liquid waste treatment method of the second embodiment differs from the radioactive liquid waste treatment method of the above-described first embodiment in the method of adjusting the second water to be treated in step S4. In the radioactive waste liquid treatment method of the second embodiment, in the adjustment process of the second water to be treated in step S4, the third water to be treated, which is the radioactive waste liquid containing the component to be removed and the coexisting component, is added to the second water to be treated. Mix water. Thereby, the component concentration of the second water to be treated is adjusted so as to be within the set concentration range. For this reason, the same processing and configuration as those of the above-described first embodiment can be applied to the processing and configuration other than the adjustment of the second water to be treated.

FIG. 6 shows a schematic configuration of a radioactive waste liquid treatment system related to the radioactive waste liquid treatment method of the second embodiment. In addition to the radioactive waste liquid treatment system shown in FIG. 2, the radioactive waste liquid treatment system shown in FIG. and a third adjustment container 221 in which the Further, a first adjustment vessel 201 for mixing the second water to be treated with the third water to be treated and adjusting the component concentration of the second water to be treated is provided in the second adjustment equipment 20 . The second adjustment vessel 211 and the first adjustment vessel 201 are connected by the third liquid transfer equipment 212 , and the second water to be treated is sent to the first adjustment vessel 201 by the third liquid transfer equipment 212 . Also, the third adjustment vessel 221 and the first adjustment vessel 201 are connected by a fourth liquid transfer facility 222 , and the third treatment target water is sent to the first adjustment vessel 201 by the fourth liquid transfer facility 222 .

For example, in the radioactive waste liquid treatment system, the concentrations of the components to be removed and the coexisting components in the second water to be treated in the second adjustment vessel 211 are measured, and the concentration determination process of step S3 described above is performed. Then, when it is determined that the component concentration of the second water to be treated is outside the set concentration range (NO in step S3), the second water to be treated is sent from the second adjustment vessel 211 to the first adjustment vessel 201, The third water to be treated is sent from the third adjusting container 221 to the first adjusting container 201 . As a result, the second water to be treated is mixed with the third water to be treated in the first adjustment vessel 201 to adjust the component concentration of the second water to be treated (step S4).

Then, after the adjustment processing of the second water to be treated in step S4, the process returns to step S3 to measure the component concentration of the adjusted second water to be treated in the first adjustment container 201, and determine whether it is within the set concentration range. judge. If it is determined that the adjusted second water to be treated is within the set concentration range (YES in step S3), the process proceeds to step S5. Further, when it is determined that the adjusted second water to be treated is outside the set concentration range (NO in step S3), the mixing process is repeated until it is determined to be within the concentration range in step S3.

It should be noted that the radioactive liquid waste used as the third water to be treated need not be limited to one type. For example, prepare multiple radioactive waste liquids to be mixed with the second water to be treated as the third water to be treated, and select the type of radioactive waste liquid to be mixed with the second water to be treated as needed. can be mixed and used as the third water to be treated.

In the radioactive liquid waste treatment method according to the present embodiment, the second water to be treated is mixed with the third water to be treated containing the components to be removed. Therefore, compared to the adjustment method of mixing rainwater, groundwater, or seawater with the second treatment target water, the concentrations of the components to be removed and the coexisting components can be adjusted without increasing the total amount of radioactive waste liquid. Therefore, compared with the first embodiment described above, the second treatment target water can be treated with less used adsorbent, and the amount of radioactive waste generated can be reduced.

<Third embodiment of radioactive waste liquid treatment method>
Next, a third embodiment of the radioactive waste liquid treatment method will be described. In addition, in the following description of the third embodiment, detailed description of the same processing and configuration as those of the first and second embodiments will be omitted.

In the radioactive waste liquid treatment method of the third embodiment, in setting the concentration range in step S2 of the radioactive waste liquid treatment methods of the first and second embodiments, the concentration ratio of the component to be removed to the coexisting component in the water to be treated is Set the range of [(component to be removed/coexisting component) ratio]. Further, in step S4, the second water to be treated is adjusted so that the concentration ratio range of the components to be removed is within the range. Therefore, the same processing and configuration as in the above-described first embodiment can be applied to the setting of the concentration range described above and the processing and configuration other than the adjustment of the second water to be treated.

In the radioactive waste liquid treatment method of the third embodiment, first, in setting the concentration range in step S2, similarly to the above-described first and second embodiments, the range higher than the coexisting component concentration of the first target water Set the coexisting component concentration range to . Furthermore, as the setting of the concentration range in step S2, the concentration ratio range of the removal target component is set to a range larger than the concentration ratio of the removal target component to the concentration of the coexisting component in the first water to be treated. At this time, along with the coexisting component concentration and the concentration ratio range of the removal target component, the removal target component concentration range and the total concentration range of the coexisting component and the removal target component may be set.

Next, in step S3, the coexisting component concentration range and the concentration ratio range of the removal target component set in step S2 are compared with the coexisting component concentration and the concentration ratio of the removal target component of the second water to be treated. At this time, in addition to the coexisting component concentration and the concentration ratio range of the components to be removed, if the concentration range of the components to be removed and the total concentration range of the coexisting components and the components to be removed are set, these Concentration may be compared and determined.
Then, when it is determined that all the component concentrations of the second water to be treated are within the set range (YES in step S3), the process proceeds to step S5. If it is determined that the component concentration of the second water to be treated is out of any set range (NO in step S3), the process proceeds to step S4.

Then, in step S4, the coexisting component concentration of the second water to be treated and the concentration ratio of the removal target component to the coexisting component are adjusted. Specifically, the concentration of the coexisting component is higher than that of the second treatment target water, and furthermore, by mixing a diluted solution (for example, the third treatment target water) with a high concentration ratio of the removal target component, the second treatment target water Increase the concentration ratio of coexisting components in water and components to be removed.

(Concentration ratio of components to be removed)
The reason for increasing the concentration ratio of the components to be removed in the water to be treated in the third embodiment will be described.
FIG. 7 shows a graph of the relationship between the concentration ratio of the components to be removed in the water to be treated [(component to be removed/coexisting component) ratio] and the lifetime of the adsorbent. In FIG. 7, the vertical axis indicates the life of the used adsorbent, and the horizontal axis indicates the (removal target component/coexisting component) ratio of the water to be treated.
As shown in the graph of FIG. 7, the higher the (component to be removed/coexisting component) ratio, the longer the life of the spent adsorbent. It is considered that this is because the ratio of coexisting components that inhibit the adsorption of the components to be removed in the water to be treated decreases, so that the components to be removed are more likely to be adsorbed by the adsorbent.

Next, FIG. 8 shows a graph of the relationship between the dilution ratio of the water to be treated and the treatment amount ratio. In FIG. 8, the horizontal axis indicates the dilution rate (magnification) of the adjusted water to be treated, and the vertical axis indicates the magnification of the amount (treatment amount) of the component to be removed adsorbed by the adsorbent when treating the adjusted water to be treated. is shown.
Also, in FIG. 8, the dashed line is a graph when it is assumed that the dilution ratio and the throughput magnification change in a one-to-one ratio. For example, the graph indicated by the dashed line is a graph assuming that the processing amount magnification is 5 times when the dilution rate is 5 times, and the processing amount magnification is 10 times when the dilution rate is 10 times. The water to be treated is diluted with the third water to be treated so that the (component to be removed/coexisting component) ratio becomes high. Therefore, the dashed straight line also corresponds to the relationship with the (component to be removed/coexisting component) ratio that increases in proportion to the dilution rate.

Furthermore, FIG. 8 shows experimental results of the amount of the component to be removed (treatment amount) adsorbed by the adsorbent by actually adjusting the (component to be removed/coexisting component) ratio of the water to be treated. In FIG. 8, the experimental results and the dashed line graph match with the water to be treated in which the dilution ratio is 1, that is, the (component to be removed/coexisting component) ratio is not adjusted.

On the other hand, in the experimental results of the water to be treated, in which the dilution rate was doubled, that is, the ratio of (components to be removed/coexisting components) was adjusted to be doubled, the processing amount of the adsorbent was about 3 times as indicated by the dashed line in the graph. became. In addition, in the experimental result of the water to be treated with the dilution rate adjusted to 4 times, the processing amount magnification of the adsorbent was about 7.5 times as indicated by the dashed line in the graph. Furthermore, in the experimental result of the water to be treated in which the dilution rate was adjusted to 8 times, the processing amount magnification of the adsorbent was about 16.5 times as indicated by the dashed line in the graph.

In this way, by increasing the ratio (components to be removed/coexisting components) in the water to be treated, the components to be removed that are adsorbed by the adsorbent are more than the ratio of the components to be removed that increase in the water to be treated by adjusting the concentration ratio. increase the multiplier. Therefore, by setting the concentration ratio of the components to be removed in the second treatment target water to a range higher than that in the first treatment target water and treating the second treatment target water within this range with the used adsorbent, efficient In addition, the components to be removed can be removed from the water to be treated.

In the radioactive waste liquid treatment method according to the present embodiment, as described above, the range of the concentration ratio of the component to be removed to the coexisting component is set, and the second water to be treated is adjusted so that the concentration ratio falls within this range. As a result, compared to the above-described first and second embodiments, the second treatment target water can be treated with less used adsorbent, and the amount of radioactive waste generated can be reduced.

Although the present invention has been described above, the present invention is not limited to the above-described embodiments, and various changes are possible without departing from the gist of the present invention.
For example, radioactive waste liquid treatment can be implemented by combining each element of the first embodiment, the second embodiment, and the third embodiment.

1 first radioactive liquid waste treatment equipment, 2 second radioactive liquid waste treatment equipment, 3 transfer equipment, 10 first adjustment equipment, 11 first liquid transfer equipment, 12 first treatment equipment, 13 first adsorbent container, 14 first water supply Equipment, 15 first storage container, 20 second adjustment equipment, 21 second liquid transfer equipment, 22 second treatment equipment, 23 second adsorbent container, 24 second water supply equipment, 25 second storage container, 30 new material, 31, 41 adsorption site, 40 used material, 201 first adjustment vessel, 211 second adjustment vessel, 212 third liquid transfer equipment, 221 third adjustment vessel, 222 fourth liquid transfer equipment

Claims (14)

a first adsorption step of adsorbing the component to be removed contained in the first water to be treated to the adsorbent to prepare the used adsorbent;
a concentration range setting step of setting a coexisting component concentration range to a range higher than the coexisting component concentration of the first water to be treated;
a determination step of determining whether the coexisting component concentration of the second water to be treated is within the coexisting component concentration range;
a second adsorption step of causing the used adsorbent to adsorb the component to be removed contained in the second water to be treated whose concentration of the coexisting component is within the concentration range of the coexisting component. A concentration adjustment step of adjusting the concentration of the coexisting component in the second water to be treated to fall within the concentration range of the coexisting component when the concentration of the coexisting component in the second water to be treated is not within the concentration range of the coexisting component. Item 1. The radioactive waste liquid treatment method according to item 1. In the concentration range setting step, setting the removal target component concentration range to a range higher than the removal target component concentration of the first water to be treated,
In the determination step, determining whether the concentration of the component to be removed in the second water to be treated is within the concentration range of the component to be removed;
In the second adsorption step, the concentration of the coexisting component is within the concentration range of the coexisting component, and the concentration of the component to be removed is within the concentration range of the component to be removed. The radioactive waste liquid treatment method according to claim 1 or 2, wherein the used adsorbent is adsorbed. Concentration adjustment for adjusting the concentration of the component to be removed in the second water to be treated to fall within the concentration range of the component to be removed when the concentration of the component to be removed in the second water to be treated is not within the concentration range of the component to be removed 4. The radioactive liquid waste treatment method according to claim 3, comprising a step. 2. The radioactive waste liquid treatment method according to claim 1, wherein the components to be removed include at least one of strontium, cesium, cobalt, iodine, antimony, ruthenium, technetium, uranium, plutonium, americium, curium, and neptunium. 6. The radioactive liquid waste treatment method according to claim 5, wherein at least one of sodium, potassium, magnesium, calcium, barium, chlorine, bromine, sulfuric acid, and carbonic acid is included as the coexisting component. When the same element is included as the component to be removed and the coexisting component, the component to be removed includes a radioactive isotope of the element, and the coexisting component includes a stable isotope of the element. Radioactive waste liquid treatment method. In the concentration range setting step, setting the concentration ratio range of the components to be removed so as to be greater than the concentration ratio of the components to be removed with respect to the concentration of the coexisting components in the first water to be treated;
In the determination step, determining whether the concentration ratio of the component to be removed with respect to the concentration of the coexisting component in the second water to be treated is within the concentration ratio range;
3. The step of adsorbing onto the used adsorbent causes the used adsorbent to adsorb the component to be removed contained in the second water to be treated whose concentration ratio of the component to be removed is within the concentration ratio range. 1. The radioactive waste liquid treatment method according to 1. Concentration adjustment for adjusting the concentration of the removal target component in the second treatment target water to fall within the coexisting component concentration range when the concentration ratio of the removal target component in the second treatment target water is not within the concentration ratio range. The radioactive waste liquid treatment method according to claim 8, comprising a step. 10. The radioactivity according to claim 2, 4, or 9, wherein in the concentration adjustment step, the concentration is adjusted by mixing the second water to be treated with a third water to be treated containing a component to be removed and a coexisting component. Waste liquid treatment method. The radioactive waste liquid treatment method according to claim 1, wherein the second water to be treated contains sodium as the coexisting component, and the concentration of sodium in the second water to be treated in the second adsorption step is 25,000 ppm or less. The radioactive liquid waste treatment method according to claim 1, wherein said second water to be treated contains calcium as said coexisting component, and in said second adsorption step, the concentration of calcium in said second water to be treated is 100 ppm or less. The radioactive waste liquid treatment method according to claim 1, wherein the second water to be treated contains chlorine as the coexisting component, and the concentration of chlorine in the second water to be treated in the second adsorption step is 45,000 ppm or less. 2. The radioactive liquid waste according to claim 1, wherein at least one of a silicotitanate compound, a titanate compound, a zeolite, a ferrocyanate compound, a metal organic framework (MOF) compound, and an ion exchange resin is used as the adsorbent. Processing method.

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