KR100426952B1 - Glass Formulation for Combustible Radioactive Wastes Using Triangular Coordinate - Google Patents

Abstract

The present invention relates to a method for producing a glass solid of combustible radioactive waste using three-phase coordinates. When the combustible medium and low level radioactive waste generated in a nuclear power plant is decomposed, an ash component is mixed with a molten glass additive to form an amorphous glass solid. In manufacturing, by mixing the radioactive waste and the glass additive in a glass melting furnace to produce a glass solid having excellent properties of leaching resistance and viscosity at the time of melting.

More specifically, the glass solids of 52 different compositions were prepared by simulating radioactive waste and glass additives, and a database was prepared by measuring the viscosity and the total mass loss of the melt. As shown in FIG. 1, SiO ₂ + Al ₂ O ₃ , The optimum composition area consisting of alkali + B ₂ O ₃ and other components is displayed in three-phase coordinates, and the composition of the final glass solidified according to the increase in the content of each waste type as shown in FIG. The integrity of the final glass solid is determined on the basis of.

The glass solid composition shown on the three-phase diagram of the present invention may be mixed in a form of 30 to 50% in the form of ash with respect to a representative glass, or about 30 to 40% in the form of a waste boric acid dried matter and the form of the ash. Even if mixed to a degree, it can be melted in a melting furnace at 1,100 ~ 1,200 ℃ under an air atmosphere to produce an excellent glass solid.

Description

Glass formulation for combustible radioactive wastes using triangular coordinates

The present invention provides a method for selecting the optimum composition of glass as a method for producing a glass solid of a combustible medium-low level radioactive waste generated in a nuclear power plant. More specifically, the low-level radioactive waste from the nuclear power plant pyrolyzes flammable wastes such as waste ion exchange resins (waste I, waste resin II), scum and boric acid waste liquid on molten glass to remove organic matter as exhaust gas. In glass-solidifying the trace-containing inorganic material, the composition of the final glass solids is changed depending on the composition of the glass frit as well as the type of waste and the ash content thereof.

Conventionally, the glass solids have been produced by separately developing the composition of the glass additive in consideration of the composition of the waste, but there is a disadvantage in that a large cost is required for the production of the glass additive. However, in the present invention, before the actual glass solids are prepared, the candidate composition of the glass additive is selected, and the ashes of the grater, the waste resin, and the boric acid dry matter are predicted according to the mixing ratio of the final glass, and the final glass having excellent properties. It is to enable the design of a glass additive composition that can produce a solid composition.

Prior art related to the present invention is a method of making a glass solid by using a fly ash and a boric acid-containing radioactive waste as a base material of borosilicate glass (Korean Patent Publication No. 97-051470), a method of manufacturing a glass solid of a high level waste using a fly ash (Korea Patent Published 97-003288), glass fire for waste solidification and glass for waste solidification (Japanese Patent Laid-Open No. 98-167754) and U.S. Patent No. 5,840,638 for radioactive, hazardous materials and mixed waste liquid immobilization. This is different things.

The present invention is to prepare a glass solid body which is easy to discharge by mixing the oxidizing material of the radioactive waste and the glass additive in the glass melting furnace and excellent leaching resistance and low enough viscosity during melting. To this end, a mixture of inorganic oxides and carbonates is mixed / melted to establish a database of composition regions having excellent properties.

In order to present the mixing ratio and content of ash for each waste by using glass, which is easy to purchase, it is a component that raises the viscosity for a wide range of composition (SiO ₂ + Al ₂ O ₃ ) and lowers the viscosity. Three-phase diagrams were constructed by classifying the components (alkali + B ₂ O ₃ ) and the main components (CaO + Ti ₂ O +…) in the waste. The three-phase chart provides the determination of the mixing ratio between wastes and the mixing ratio of waste and common glass to produce solids with good properties.

FIG. 1 shows an optimum composition of glass solids containing Si, Al, B, and alkali elements (Na, K, Li, etc.) as main components.

Figure 2 shows the change in the composition (predicted value) of the final solidified body according to the type and content of the waste (increased by 5%) with the basic glass as a basic raw material and its embodiment.

<Description of the code | symbol about the principal part of drawing>

10: excellent solidified composition range of less than 5 g / m ² total mass loss

12: excellent solidified composition area with viscosity at melting point of 100 poise or less

14: glass solid composition composition which satisfies the conditions 10 and 12 at the same time

20: general glass 22: boric acid waste liquid

24: Waste Ion Exchange Resin 26: Waste Ion Exchange Resin II

28: representative catch 30: glass compositions with an increase of 5% in waste content

32: Composition in which the glass solid produced using ordinary glass has a viscosity within 100 poise and a total mass loss of less than 5 g / m ^2.

34: Composition which does not satisfy the above conditions among glass solid bodies prepared using ordinary glass

Conventional radioactive waste treatment method is the mixing ratio (composition) of the glass to vitrify the waste using a glass additive or a method for producing the glass, the present invention is focused on the type of waste by focusing on the common glass that is easy to purchase a certain composition The increase in log ash is indicated in a specific three-phase diagram to preliminarily select minimum and maximum values for each waste or mixed waste for the appropriate compositional area.

The optimum composition region of Figure 1 was determined in the same manner as in the following examples by investigating the viscosity and leaching rate of the glass solids of 52 different compositions. The leaching rate and viscosity (Table 1) represented by the total mass loss according to the 52 glass solid compositions were summarized.

As shown in FIG. 1, when the optimum composition region is determined, the final glass solid composition according to the ash content constituting the representative composition for each type of waste may be displayed on the three-phase chart, starting with a candidate glass additive composition (eg, general glass) as shown in FIG. 2. In order to design the ash content for each type of waste according to the glass additive composition to have an optimal composition in the target region (vector) of FIG.

In the above, the final glass solids are basically a shortage component necessary for an excellent glass in consideration of the inorganic oxide (TiO ₂ + CaO + B ₂ O ₃ + ∑R ₂ O + ..) constituting the ash of the waste. In addition, the final glass should be made so that the composition area of the final glass solid having the best characteristics (viscosity, leaching rate) should be determined first. This process is the database shown in Table 1, which has nothing to do with the composition of ordinary glass or waste.

Therefore, the superior composition region shown in Table 1 is limited to FIG. 1 and is not related to the vector described in FIG. 2 and applies the concept of the vector only in relation to the mixing ratio of waste and glass additives.

The database described above is about 30 to 60% of silicon and aluminum oxide (SiO ₂ + Al ₂ O ₃ ) and about 7 to 35% of boron and alkali oxide (B ₂ O ₃ + ∑R ₂ O) by weight. The composition region 14 of the excellent glass solid shown on the three-phase coordinate of the three-component system composed of about 10 to 50% of other oxides (TiO ₂ + CaO +...) Is shown. In addition, the composition of the final glass solid mixed with the glass additive and the ash ash is located in the region 14 by determining the appropriate content of the waste to be mixed and melted into the general glass which is a specific glass additive. This explains the process of checking.

Therefore, in order to pass the quality of the final product, the amount of raw material A (e.g. general glass) and raw material B (e.g. ash content of waste) should be added to each embodiment in order to make glass solids at various mixing ratios. Was determined by measuring. In practice, however, glass solids can be produced and predicted in three-phase plots without measurement / judgement. (Delete content after this)

Table 1. Leaching rate and viscosity according to the composition of glass solids

# SiO ₂ + Al ₂ O ₃ (% by weight) B ₂ O ₃ + ΣR ₂ O ^* (% by weight) Other oxides (% by weight) Total mass loss (g / m ² ) Viscosity One 72.4 27.2 0.4 1.35 500 2 52.2 30.3 17.5 3.77 20 3 45.1 35.3 29.6 11.1 30 4 43.9 48.7 17.4 11.0 5 5 39.7 50.7 9.6 38.61 2 6 59.3 40.4 0.3 61.18 10 7 65.8 27.2 7.0 1.81 100 8 57.3 30.3 12.4 1.97 70 9 37.6 37.1 25.3 7.22 2 10 37.6 25.3 37.1 2.43 2 11 41.4 22.9 35.7 2.83 5 12 32.9 31.6 35.5 4.34 2 13 48.5 13.8 37.7 2.05 5 14 50.2 14.4 35.4 2.94 5 15 38.8 25.0 36.2 2.36 10 16 43.3 19.4 37.3 1.25 5 17 34.8 25.0 40.2 2.23 5 18 61.8 35.6 3.6 4.17 50 19 48.2 25.0 26.8 1.99 10 20 46.0 23.2 30.8 1.56 10 21 43.7 21.5 35.8 2.35 10 22 41.5 19.7 38.8 1.92 10 23 39.2 17.9 42.9 1.68 10 24 52.5 44.9 2.6 24.23 10 25 49.5 48.0 2.5 43.26 10 26 43.3 54.2 2.5 128.2 10 27 47.5 23.3 29.2 2.88 5 28 45.5 21.6 32.9 2.71 5 29 43.4 19.8 36.8 2.54 5 30 44.1 21.5 34.4 2.56 5 31 48.6 21.8 29.6 2.06 5 32 48.3 20.8 31.9 2.35 5 33 46.6 19.0 34.4 2.37 5 34 45.1 17.3 37.6 2.23 5 35 52.5 40.8 6.7 23.6 5 36 37.1 49.4 13.5 262.3 5

* Alkali Oxides (Li, K, Na, etc.)

Table 1. Measurement of Leaching Rate and Viscosity According to Composition of Glass Solids (Continued)

# SiO ₂ + Al ₂ O ₃ (% by weight) B ₂ O ₃ + ΣR ₂ O ^* (% by weight) Other oxides (% by weight) Total mass loss (g / m ² ) Viscosity 37 66.6 26.2 7.2 0.01 100 38 69.8 20.0 10.2 0.34 100 39 56.2 26.3 17.5 2.12 30 40 52.5 20.1 27.4 0.59 30 41 48.8 13.9 37.3 0.77 50 42 61.2 26.3 12.5 0.86 100 43 60.8 20.0 19.2 0.98 100 44 49.5 31.4 19.1 1.41 10 45 52.6 32.1 15.3 2.18 10 46 52.6 32.1 15.3 2.31 10 47 67.6 25.6 6.8 1.26 300 48 63.1 30.5 6.4 2.86 300 49 54.1 40.4 5.5 5.47 100 50 45.1 50.4 4.5 214.2 30 51 58.6 35.0 6.4 5.07 100 52 58.6 35.5 5.9 3.37 100

* Alkali Oxides (Li, K, Na, etc.)

<Example>

Low-level radioactive waste boric acid dry matter and scum and waste resin I and scum mixed waste are about 10-50g in the form of simulated oxide after pyrolysis, and glass (SiO ₂ 73%, Al ₂ O ₃ 1%) , Na ₂ O 14%, MgO 4%, CaO 8%) was vitrified in the platinum crucible at various compounding ratios using about 50 ~ 90g, the leaching rate of the glass solid was measured using a simple PCT method. (See Tables 2 and 3) Here, the surface area (S) of the glass powder and the volume (V) of the leachate are determined so that the glass solids have an S / V value of 1/50 based on 1 to 2 mm crushed glass. . Thus prepared samples are stored for 7 days in a 70 ℃ oven. Thereafter, after drying the glass powder, the total mass loss was measured to determine the leaching rate of the glass solid.

Table 2. Comparison of Leaching Rates of Glass Solids Containing Crushed and Boric Acid Wastes

Boric acid waste solution 0% Boric Acid Waste 10% Boric acid waste 20% Boric acid waste 30% 0% NA 4.0 31.8 8.1 10% 5.2 4.8 3.1 2.8 20% 4.5 NA NA NA 30% 4.7 NA NA NA 40% of handwriting 5.6 NA NA NA 50% of handwriting 3.9 NA NA NA

* NA: No experimental data. Total mass loss for 7 days at 70 ℃ (g / m ² )

Table 3. Comparison of leaching rate of glass solids containing ash of waste ion exchange resin

Waste resin I0% Waste resin I10% Waste Resin I20% Waste Resin I30% 0% NA 4.7 7.9 14.7

* NA: No experimental data. Total mass loss for 7 days at 70 ℃ (g / m ² )

The glass solids are melted by mixing inorganic oxides, carbonates and glass additives (general glass), which simulate the waste resin, boric acid waste dry matter, or ash component of the collectible, and the temperature of the molten glass is higher than 1,200 ° C. After keeping it at a high temperature and melting it, it is immediately followed by tilting the crucible and the temperature at that time is maintained at 1,150 ± 30 ° C. The viscosity was predicted by the correlation curve between discharge time and standard viscosity. (See Table 4 and Table 5)

Table 4. Viscosity Comparison of Molten Glass Containing Catch and Waste Boric Acid Dry Matter

Boric acid waste solution 0% Boric Acid Waste 10% Boric acid waste 20% Boric acid waste 30% 0% NA H H G 10% H H G G 20% H NA NA NA 30% G NA NA NA 40% of handwriting G NA NA NA 50% of handwriting G NA NA NA

* NA: No experimental data. G: 100 poise or less, H: 100 poise or more

Table 5. Viscosity Comparison of Molten Glass Containing Ash Component of Waste Ion Exchange Resin

Waste resin I0% Waste resin I10% Waste Resin I20% Waste Resin I30% 0% NA H G G

* NA: No experimental data. G: 100 poise or less, H: 100 poise or more

A glass that can reach within a glass composition region having excellent glass properties by predicting the composition change of the glass solid body in accordance with increasing the content of the ash of the waste resin or catch body or the dry matter of the boric acid waste in a glass additive such as known glass. May contribute to the selection of additives.

Claims (5)

In the method for producing a glass solid using a combustible radioactive waste, [SiO ₂ + Al ₂ O ₃ ], [B ₂ O ₃ + R ₂ O], displaying a glass solid having a melt viscosity of 100 poise or less and a total mass loss of less than 5 g / m ^{2 as} a composition region of the superior glass solid on a three-phase coordinate consisting of other oxides; And Using the three-phase coordinates characterized in that the composition of the final glass solids according to the increase in the amount of waste by type added to the selected glass additives is selected and the composition contained in the composition region of the excellent glass solids is selected to produce the glass solids. Method for producing glass solids of flammable radioactive waste. However, in the above, R ₂ O represents an alkali oxide. delete delete delete delete