KR20220052488A - Method for manufacturing sollidification form using radioactive waste concrete based on usage of cement solidification agent - Google Patents

Abstract

According to an embodiment of the present invention, a radioactive waste concrete solidified body manufacturing method based on the amount of a used cement solidified material comprises the following steps of: inferring a content of a hardened cement body with respect to fine powder of waste concrete; and determining the amount of a used cement solidified material based on the inferred content of the hardened cement body.

Description

Method for manufacturing radioactive waste concrete solidified body based on cement solidification amount usage

The present invention relates to a method for manufacturing a waste radioactive concrete solidified body, and more particularly, to a method for manufacturing a solidified body targeting radioactive waste concrete, to determine the appropriate amount of cement solidified material according to the component content of the waste concrete .

During the operation and decommissioning of nuclear power plants, various types and types of radioactive waste are generated. At this time, radioactive concrete waste accounts for more than 70% of the generated waste.

However, there is no developed technology for the treatment of such radioactive concrete waste.

On the other hand, there are various methods for treating radioactive waste, but solidification refers to a treatment method of physically fixing and chemically stabilizing the waste in a solid structure by mixing the radioactive waste with a material that fixes the radioactive waste in a solid form. Such solidification treatment includes a cement-based method, a lime-based method, a thermosetting polymer method, a film-forming method, a self-cement method, and a vitrification method. For example, the solidification treatment includes a technique through high-temperature calcination vitrification of 1000 degrees or more, a method using a solidifying material composition based on a polymer or paraffin, or a solidifying material composition including alumina cement.

As such, the largest proportion of waste generated during dismantling of nuclear power plants is the concrete material used in nuclear power plant facilities. In this case, a very large social cost is incurred in securing a storage facility for storing these solidified materials.

In addition, there is a problem in that the maintenance and management efficiency of radioactive waste is significantly reduced when solidified substances having different degrees of radioactivity are stored in the same space.

In the case of low- and medium-level radioactive concrete waste generated during the dismantling of nuclear power plants, radioactivity is concentrated in the cement hardening body, and radioactivity hardly proceeds in the aggregate area. In addition, the proportion of hardened cement based on the total volume of concrete is around 30%, which is relatively small.

Therefore, if aggregates are separated from a large amount of low- and medium-level radioactive concrete waste generated during decommissioning of a nuclear power plant, the amount of low-intermediate level radioactive waste can be reduced by more than 50%.

If the aggregate separated from the low-intermediate level waste concrete is removed from the cement hardening body (paste) attached to the surface, the degree of radioactive contamination is greatly reduced depending on the level of removal of the paste. has advantages.

Through this process, it is possible to greatly reduce the amount of waste generated from the low and medium level waste concrete generated in the process of dismantling nuclear power plants. It can be said that it is the most essential technology for a nuclear power country.

However, in order to separate aggregates that have not undergone radiation from the waste concrete generated during the decommissioning process of nuclear power plants, the hardened cement adhering to the surface of the aggregates must be separated by various methods. At this time, since the attached hardened cement must be separated as much as possible in order for the aggregate to have a contamination level below a certain level, a significant amount of aggregate is inevitably separated from the hardened cement.

Therefore, the waste remaining after the final separation of aggregates from the low and medium level waste concrete inevitably contains a significant amount of fine and coarse aggregate particles along with the hardened cement, and thus the content of hardened cement in the waste may change significantly.

Existing research presented as a method for recycling of low- and medium-level radioactive concrete suggests that it is possible to secure the strength to satisfy the conditions for receiving solidified bodies if the radioactive waste concrete from which aggregates are separated is pulverized into fine powder and then calcined at a certain temperature. However, the results of these studies can vary greatly depending on the content of hardened cement included in the final waste, and when the content of hardened cement is below a certain level, the compressive strength suggested in the conditions for receiving the solidified body cannot be satisfied.

In order to solve this problem, it is necessary to verify the content of the cement hardened body contained in the waste obtained from the radioactive waste concrete and to manufacture the solidified body based on this.

As a related prior art, there is Republic of Korea Patent Publication No. 10-1641281 (title of invention: solidifying composition for solidifying radioactive waste containing alumina cement and solidifying method of radioactive waste using the same, registration date: July 14, 2016).

An object of the present invention is to reduce the amount of cement solidified material used while satisfying the compressive strength suggested in the solidified material acceptance condition in a solidified material manufacturing method for radioactive waste concrete. To provide a method for manufacturing a solid concrete body.

The above object is, according to the present invention, inferring the content of hardened cement with respect to the fine powder of waste concrete, and determining the amount of cement hardening material to be used based on the inferred content of the hardened cement. It is achieved by a method for manufacturing a solidified waste concrete based on radiation.

Preferably, the step of inferring the content of the hardened cement body is the analysis of the content of calcium oxide with respect to the fine powder of waste concrete, and the content of the hardened cement in the waste concrete based on the result of analyzing the content of calcium oxide. It may include an inference step.

Preferably, analyzing the content of calcium oxide may include analyzing the content of calcium oxide using a fluorescence X-ray diffraction analyzer.

Preferably, the determining of the amount of the cement hardening material used includes increasing the amount of the cement hardening material used if the analogous content of the hardened cement body is less than a preset reference value, and if the analogous content of the hardened cement body is equal to or greater than a preset standard value It may include reducing the amount of the cement hardening material used.

The present invention infers the content of hardened cement included in the waste obtained from radioactive waste concrete and determines the amount of cement solidified based on this, which is suggested in the solidified body acceptance conditions in manufacturing the radioactive waste concrete solidified body. It is possible to reduce the amount of cement solidifying material used while satisfying the compressive strength.

In addition, the present invention can maximize the efficiency in the treatment of radioactive waste concrete by securing the performance stability and homogeneous quality of the radioactive waste concrete solidified body.

1 is an overall flowchart illustrating a method for manufacturing a radioactive waste concrete solidified body according to an embodiment of the present invention.
2 is a flowchart illustrating a process of inferring the content of hardened cement according to an embodiment of the present invention.
3 is a flowchart illustrating a process for determining the amount of cement hardening material used according to an embodiment of the present invention.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings illustrating preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, the present invention will be described in detail by describing preferred embodiments of the present invention with reference to the accompanying drawings. However, in describing the present invention, descriptions of known functions or configurations will be omitted in order to clarify the gist of the present invention.

Concrete is the most common construction material manufactured with cement, fine aggregate, and coarse aggregate as main raw materials, and these raw materials have the characteristic that the content of components can be distinguished chemically. In the case of fine aggregate, the main component is silicon dioxide (SiO2), and the coarse aggregate has the characteristics of silicon dioxide (SiO2) and aluminum oxide (Al2O3). In comparison, cement has a characteristic that contains calcium oxide (CaO), silicon dioxide (SiO2), and aluminum oxide (Al2O3) as main components, and contains a large amount of calcium oxide, which is hardly contained in fine and coarse aggregates. Therefore, if the content of calcium oxide contained in the final waste can be calculated, the content of hardened cement can be inferred.

If the content of hardened cement included in the waste concrete is inferred from the chemical compositional characteristics of the concrete material, and the standard is set to produce the solidified body, the performance stability and homogeneous quality of the radioactive waste concrete solidified body are secured. It is possible to maximize the efficiency in the treatment of concrete.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is an overall flowchart illustrating a method for manufacturing a radioactive waste concrete solidified body according to an embodiment of the present invention.

The method described here is only one embodiment of the present invention, and in addition, various steps may be added as follows if necessary, and since the following steps may also be performed by changing the order, the present invention is described below It is not limited to each step and its order to be described.

Referring to FIG. 1 , in step 110 , the content of hardened cement may be inferred with respect to the fine powder of waste concrete.

This will be described in detail with further reference to FIG. 2 as follows. For reference, FIG. 2 is a flowchart illustrating a process of inferring the content of hardened cement according to an embodiment of the present invention.

That is, in step 210, it is possible to prepare (provide) the waste concrete fine powder.

Thereafter, in step 220, the content of calcium oxide may be analyzed using a fluorescence X-ray diffraction analyzer with respect to the fine powder of waste concrete.

Thereafter, in step 230, the content of the hardened cement in the waste concrete may be inferred based on the result of analyzing the content of the calcium oxide.

As described above, in one embodiment of the present invention, in order to infer the content of hardened cement in the waste concrete, for fine particles of 0.30 mm or less from which aggregates are separated from the waste concrete, the content analysis of calcium oxide can be precisely and simply performed. The fluorescence X-ray diffractometer (XRF) may be used.

The hardened cement in the waste concrete was pulverized to 0.30 mm or less, and the fine aggregates were mixed in each ratio and analyzed by the fluorescence X-ray diffraction analyzer, and the values are summarized in Table 1 below.

In one embodiment of the present invention, it is characterized in that the content of the hardened cement included in the fine powder of waste concrete is inferred based on Table 1 above. After the waste concrete from which the aggregate is separated is pulverized to a size of 0.30 mm or less, the content of calcium oxide is analyzed with the fluorescence X-ray diffraction analyzer to infer the content of hardened cement in the waste concrete.

Here, pulverizing the fine powder of waste concrete from which the aggregate is separated to a size of 0.30 mm or less facilitates the analysis of the calcium oxide content using a fluorescence X-ray diffraction analyzer, and suppresses material separation and bleeding during the production of a solidified body. At the same time, it is to secure stable strength.

Referring back to FIG. 1 , in step 120 , the amount of cement hardening material used may be determined based on the analogous content of the hardened cement body.

For example, when the content of calcium oxide in the fine powder of waste concrete is 24% or less, the use ratio of the waste concrete and the solidifying material is 87:13, and the amount of the cement solidifying material can be determined based on the use ratio.

In addition, when the content of calcium oxide in the waste concrete fine powder is 24% or more, the use ratio of the waste concrete and the solidifying material is 90:10, and the amount of the cement solidifying material can be determined based on the use ratio.

This will be described in detail with further reference to FIG. 3 as follows. For reference, FIG. 3 is a flowchart illustrating a process of determining the amount of cement hardening material used according to an embodiment of the present invention.

That is, in step 310, the inferred content of the hardened cement may be compared with a preset reference value.

As a result of the comparison, if the inferred content of the hardening cement is less than a preset reference value (in the "Yes" direction of 320), in step 330, the amount of the cement hardening material may be increased.

On the other hand, as a result of the comparison, if the inferred content of the hardened cement body is equal to or greater than a preset reference value (in the "No" direction of 320), the amount of the cement hardening material may be reduced in step 340.

Here, the cement solidifying material may include high powder cement (powder degree 4,800 to 6,000 cm 2 / g), fine powder blast furnace crushed slag fine powder (powder degree 5,500 to 7,000 cm 2 / g), and powder-type high-performance water reducing agent.

In addition, the cement solidifying material may further include a powdery thickener (HPMC, 0.1 to 1.5% by weight of the mixed water).

The characteristics of the composition of the cement solidifying material will be described as follows.

The hardened cement included in the waste concrete contains a large amount of calcium hydroxide (Ca(OH)2), so the pozzolan reaction of the concrete mixture such as fly ash and fine powder of granulated blast furnace slag (or latent hydraulic reaction).

In consideration of this, a large amount of crushed blast furnace slag processed into high powder was included in the cement-based solidifying material to improve initial workability and to contribute to strength enhancement. In addition, cement was also processed into a high powder so that the hydration reaction could proceed while filling between the fine powder particles of waste concrete.

In addition, by including a powdery high-performance water reducing agent, the workability of the mixture for manufacturing a solid was improved, and at the same time, the mixing quantity was reduced to have the effect of increasing the utilization rate of concrete waste in the same volume.

Example

Referring to Tables 2 and 3 below, Examples in which the present invention is applied to the waste concrete fine powder and Comparative Examples to which the present invention is not applied are exemplified. In the comparative example, a conventional technique of partially recovering the reactivity of cement components by calcining waste concrete fine powder at 600° C. for 90 minutes is applied.

In the case of the comparative example, in the mixture (Comparative Example 1) in which the hardened cement content in the waste concrete was 40% or less (Comparative Example 1), the compressive strength at 28 days of age did not satisfy the standard. However, in the formulation (Comparative Example 2) in which the cured body content was 50% or more, the compressive strength at 28 days of age satisfies the standard.

Examples 1 to 4 to which the present invention is applied were not significantly affected by the cement hardening body content of the waste concrete, and it was found that the compressive strength at 28 days of age satisfies the standard.

In addition, Examples 1 to 4 were confirmed to exhibit superior strength compared to Comparative Examples 1 and 2, and it was confirmed that it was advantageous for the manufacture of a solidified body using the low and medium level radioactive waste concrete generated during the dismantling of a nuclear power plant. .

The present invention is not limited to the above-described embodiments, and it is apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the present invention. Accordingly, it should be said that such modifications or variations are included in the claims of the present invention.

Claims (4)

inferring the content of hardened cement with respect to the fine powder of waste concrete; and
Determining the amount of cement hardening material to be used based on the analogous content of the cement hardening body; radioactive waste concrete solidified body manufacturing method based on the amount of cement hardening material used, comprising: a.
The method of claim 1,
The step of inferring the content of the cement hardened body
analyzing the content of calcium oxide with respect to the fine powder of waste concrete; and
Inferring the content of the hardened cement in the waste concrete based on the result of analyzing the content of the calcium oxide;
3. The method of claim 2,
The step of analyzing the content of calcium oxide is
A method for producing a radioactive waste concrete solidified body based on the amount of cement solidified material used, comprising the step of analyzing the calcium oxide content using a fluorescence X-ray diffraction analyzer.
The method of claim 1,
The step of determining the amount of the cement solidifying material used is
increasing the amount of the cement hardening material used if the inferred content of the cement hardening body is less than a preset reference value; and
When the analogous content of the hardened cement body is equal to or greater than a preset reference value, reducing the amount of the cement hardening material used;

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