Method for restraining variable valence metal precipitation problem in power stack high-level liquid waste glass curing process and application

Abstract

The invention provides a method for inhibiting a variable valence metal precipitation problem in a power stack high-level radioactive waste liquid glass curing process and application. The method comprises the following steps: S1, obtaining an oxide component of high-level radioactive glass; s2, according to a formula # imgabs0 #, predicting the numerical value of the theoretical oxidation-reduction property of the high-level glass; s3, according to the numerical value of the theoretical oxidation-reduction property in the step S2, the oxide components are adjusted, so that the numerical value of the theoretical oxidation-reduction property is 0.2-1.2; wherein R is the numerical value of the theoretical oxidation-reduction property, and A is the sum of the coefficient of each oxide component and the product of the molar ratio of oxygen atoms in the oxide components to the total oxygen in the high-level glass. According to the method, by controlling the oxidation-reduction property of the glass, the problem of metal precipitation caused by the oxidation-reduction reaction of variable-valence metal elements in the high-level liquid waste glass curing process is avoided, and safe and stable operation of a glass curing smelting furnace is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of radioactive waste solidification treatment, and particularly to a method and application for suppressing the precipitation of variable-valence metals during the vitrification process of high-level radioactive waste liquid from power reactors. Background Art

[0002] As a widely accepted and most widely used method for treating high-level radioactive waste liquid worldwide at present, vitrification is to calcine and melt high-level radioactive waste liquid and glass additives at high temperature, and fix radionuclides within the glass network structure at the atomic scale to achieve the purpose of preventing the migration of nuclides to the external environment. To achieve the effective utilization of nuclear fuel resources, nuclear energy tends to develop towards high-burnup reactor types. However, at the same time, the high-level radioactive waste liquid generated from spent fuel reprocessing contains higher contents of waste components such as fission products, mainly including transuranic elements and transition metal elements generated by fission. Due to the complex composition of high-level radioactive waste liquid and the high content of variable-valence elements in the liquid composition, the high-temperature vitrification melting process involves extremely complex physical and chemical reactions, resulting in the process of transforming high-level radioactive waste liquid into a glass state being regarded as a "black box" process, so that new problems and challenges often occur in the vitrification process.

[0003] Among them, metal precipitation and deposition are one of the key challenges faced in the vitrification process of high-level radioactive waste liquid. In addition to platinum group metal elements being easily precipitated and deposited due to their extremely low solubility in the glass melt, other variable-valence metal elements in high-level radioactive waste liquid, such as silver, iron, chromium, nickel, antimony, etc., may undergo complex redox reactions in the melt when the oxidation-reduction balance is disrupted during the melting process of high-level radioactive glass, which will also lead to metal precipitation problems. The metals precipitated during the long-term operation of the furnace will settle and deposit at the bottom of the furnace, which will have a destructive effect on refractory materials and alloy electrode materials, affecting the furnace life at least and causing operating accidents at worst. Summary of the Invention

[0004] In view of this, the present invention provides a method and application for suppressing the precipitation of variable-valence metals during the vitrification process of high-level radioactive waste liquid from power reactors. This method controls the oxidation-reduction property of the glass to avoid metal precipitation problems caused by the redox reactions of variable-valence metal elements during the vitrification process of high-level radioactive waste liquid, and ensures the safe and stable operation of the glass vitrification furnace.

[0005] The technical solution of the present invention is realized as follows: In the first aspect, the present invention provides a method for suppressing the precipitation of variable-valence metals during the vitrification process of high-level radioactive waste liquid from power reactors, including the following steps: S1. Obtain the oxide components of high-level radioactive glass; S2. According to the formula , predict the numerical value of the theoretical oxidation-reduction property of the high-level radioactive glass; S3. Adjust the oxide components according to the theoretical oxidation-reduction value in step S2 to make the theoretical oxidation-reduction value 0.2 to 1.2; wherein, R is the theoretical oxidation-reduction value, A is the sum of the products of the coefficients of each oxide component and the molar ratio of oxygen atoms in the oxide component to the total oxygen in the high-level radioactive waste glass.

[0006] Based on the above technical solutions, further, the theoretical oxidation-reduction value in step S3 is 0.2 to 0.9.

[0007] Based on the above technical solutions, further, the theoretical oxidation-reduction value in step S3 is 0.2 to 0.5.

[0008] The theoretical oxidation-reduction value is represented by R When this ratio is less than 0.2, it indicates that the glass melt has strong oxidizing property, and at the same time, the proportion of glass network modifiers is small, and a homogeneous glass body cannot be melted within the specified temperature range. When this ratio is greater than 1.2, it indicates that the glass melt has strong reducing property, and the variable-valence metals in the glass melt are more likely to be reduced to low-valence states, thus causing metal precipitation problems. When this ratio is between 0.2 and 1.2, the glass has moderate oxidation-reduction property and good melting performance.

[0009] Based on the above technical solutions, further, the coefficient of SiO2 is 0.48, the coefficient of B2O3 is 0.43, the coefficient of Na2O is 1.15, the coefficient of Li2O is 1.00, the coefficient of Al2O3 is 0.61, the coefficient of CaO is 1.0, the coefficient of ZnO is 0.95, the coefficient of V2O5 is 1.04, the coefficient of BaO is 1.15, and the coefficient of MgO is 0.78.

[0010] The corresponding coefficient values of each oxide are shown in Table 1, and Table 1 shows the corresponding coefficient values of SiO2, B2O3, Na2O, Li2O, etc.

[0011] Table 1 Corresponding coefficient values of each oxide

[0012] Based on the above technical solutions, even further, the oxide components of the high-level radioactive waste glass include multiple of SiO2, B2O3, Al2O3, CaO, MgO, BaO, Li2O, Na2O, ZnO, V2O5, MoO3, ZrO2, Nd2O3, La2O3, CeO2, Y2O3, Fe2O3, Cr2O3, NiO, MnO2, TeO2, SnO2, BaO, SrO, Cs2O, Rb2O, and K2O.

[0013] On the basis of the above technical solutions, further, the preparation method of the high-level radioactive waste glass is as follows: The borosilicate glass raw materials are fully mixed, heated and melted, and then naturally cooled to obtain the base glass. The base glass is fully mixed with the high-level radioactive waste, heated and melted, and then naturally cooled to obtain the high-level radioactive waste glass.

[0014] On the basis of the above technical solutions, further, the temperature of the heating and melting is 1100-1300 °C, and the time is 1-24 h.

[0015] On the basis of the above technical solutions, further, the oxide components of the base glass include multiple ones among SiO2, B2O3, Na2O, Li2O, Al2O3, CaO, V2O5, BaO, and MgO.

[0016] In the second aspect, the present invention provides an application of the method for suppressing the precipitation of variable-valence metals during the vitrification process of high-level radioactive waste liquid from a power reactor in the formulation design of high-level radioactive waste glass.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The method provided by the present invention for suppressing the precipitation of variable-valence metals during the vitrification process of high-level radioactive waste liquid from a power reactor can effectively inhibit the reduction of variable-valence metal ions, thereby realizing the efficient vitrification of high-level radioactive waste liquid while avoiding the precipitation of variable-valence metals in the high-level radioactive waste glass, maintaining good process performance and solidified body performance, and having good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 It is the XRD pattern of the uniform high-level radioactive waste glass solidified body prepared in Examples 1-3 of the present invention; Figure 2 It is the micrograph of the precipitation of variable-valence metals in the high-level radioactive waste glass solidified body prepared in Comparative Example 1 of the present invention; Figure 3 It is the XRD pattern of the precipitation of variable-valence metals in the high-level radioactive waste glass solidified body prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0021] Example 1 Example 1 provides a method for suppressing the precipitation of variable-valence metals during the vitrification of high-level radioactive waste in a power reactor, and a simulated high-level radioactive glass solid is prepared.

[0022] It includes the following oxides by mass percentage: 46.0% SiO2, 14.0% B2O3, 12.0% Na2O, 2.0% Li2O, 5.0% Al2O3, 4.0% CaO, 1.0% BaO, 2.0% ZrO2, 2.5% La2O3, 1.5% CeO2, 2.5% MoO3, 0.5% Cr2O3, 1.0% Fe2O3, 0.6% NiO, 0.4% MnO2, 0.4% SrO, 0.4% Y2O3, 0.5% TeO2, 1.2% Cs2O, 2.5% Nd2O 3。

[0023] The steps include: 1) Calculate the basic glass composition, weigh the borosilicate glass raw materials and mix them evenly, heat and melt them in a muffle furnace at 1200 °C for 1 h, and after the glass melt is naturally cooled in air, it is broken to obtain borosilicate basic glass with a particle size of about 2 mm. Mix the basic glass particles with the dry matter of the simulated high-level radioactive waste of the power reactor according to the calculated ratio, heat and melt them in a muffle furnace at 1150 °C for 2 h, and after the glass melt is naturally cooled in air, about 100 g of simulated high-level radioactive glass solid is obtained.

[0024] The theoretical oxidation-reduction potential of the simulated high-level radioactive glass is calculated to be about 0.3 through the theoretical oxidation-reduction potential calculation formula. The theoretical oxidation-reduction potential of this simulated high-level radioactive glass is within the required range of the present invention.

[0025] As Figure 1 shown, the uniformity of the molten simulated high-level radioactive glass is good and no metal precipitates. It shows that by controlling the oxidation-reduction potential of the high-level radioactive glass, the effect of suppressing the precipitation of metals in the high-level radioactive glass can be achieved.

[0026] Example 2 This embodiment provides a method for suppressing the precipitation of variable-valence metals during the vitrification of high-level radioactive waste from power reactors, and a simulated high-level radioactive glass solidified body is prepared. The specific operation is the same as that in Embodiment 1, except that the following components are adjusted while keeping the contents of the remaining components unchanged. By mass percentage of oxides, it is 42% SiO2, 17.5% B2O3, 8.5% Na2O, 2.5% Li2O, 7.5% Al2O3, and 5.0% CaO.

[0027] The theoretical oxidation-reduction potential of the simulated high-level radioactive glass is calculated to be approximately 0.2 through the theoretical oxidation-reduction potential calculation formula, and the theoretical oxidation-reduction potential of this simulated high-level radioactive glass is within the required range of the present invention.

[0028] As Figure 1 shown, the uniformity of the molten simulated high-level radioactive glass is good and no metal precipitates. It shows that controlling the oxidation-reduction potential of the high-level radioactive glass can achieve the effect of suppressing the precipitation of metals in the high-level radioactive glass.

[0029] Embodiment 3 This embodiment provides a method for suppressing the precipitation of variable-valence metals during the vitrification of high-level radioactive waste from power reactors, and a simulated high-level radioactive glass solidified body is prepared. The specific operation is the same as that in Embodiment 1, except that the following components are adjusted while keeping the contents of the remaining components unchanged. By mass percentage of oxides, it is 43.0% SiO2, 14.5% B2O3, 10.5% Na2O, 2.5% Li2O, 7.5% Al2O3, and 5.0% CaO.

[0030] The theoretical oxidation-reduction potential of the simulated high-level radioactive glass is calculated to be approximately 0.4 through the theoretical oxidation-reduction potential calculation formula, and the theoretical oxidation-reduction potential of this simulated high-level radioactive glass is within the required range of the present invention.

[0031] As Figure 1 shown, the uniformity of the molten simulated high-level radioactive glass is good and no metal precipitates. It shows that controlling the oxidation-reduction potential of the high-level radioactive glass can achieve the effect of suppressing the precipitation of metals in the high-level radioactive glass.

[0032] Embodiment 4 This embodiment provides a method for suppressing the precipitation of variable-valence metals during the vitrification of high-level radioactive waste from power reactors, and a simulated high-level radioactive glass solidified body is prepared. The specific operation is the same as that in Embodiment 1, except that the following components are adjusted while keeping the contents of the remaining components unchanged. By mass percentage of oxides, it is 45.0% SiO2, 14.0% B2O3, 13.0% Na2O, 3.0% Li2O, 3.0% Al2O3, and 5.0% CaO.

[0033] The theoretical oxidation-reduction potential of the simulated high-level radioactive waste glass was calculated using the theoretical oxidation-reduction potential calculation formula to be approximately 0.9, and the theoretical oxidation-reduction potential of this simulated high-level radioactive waste glass is within the required range of the present invention.

[0034] The uniformity of the molten simulated high-level radioactive waste glass is good, and no metal is precipitated. This indicates that controlling the oxidation-reduction potential of the high-level radioactive waste glass can inhibit the precipitation of metals in the high-level radioactive waste glass.

[0035] Example 5 This example provides a method for suppressing the precipitation of variable-valence metals during the vitrification of high-level radioactive waste from power reactors, and a simulated high-level radioactive waste glass solidified body is prepared. The specific operation is the same as that in Example 1, except that the following components are adjusted while keeping the contents of the remaining components unchanged. In terms of mass percentage of oxides, it is 44.5% SiO2, 14.0% B2O3, 13.0% Na2O, 3.5% Li2O, 3.5% Al2O3, 4.0% CaO, and 0.5% V2O5.

[0036] The theoretical oxidation-reduction potential of the simulated high-level radioactive waste glass was calculated using the theoretical oxidation-reduction potential calculation formula to be approximately 1.2, and the theoretical oxidation-reduction potential of this simulated high-level radioactive waste glass is within the required range of the present invention.

[0037] The uniformity of the molten simulated high-level radioactive waste glass is good, and no metal is precipitated. This indicates that controlling the oxidation-reduction potential of the high-level radioactive waste glass can inhibit the precipitation of variable-valence metals in the high-level radioactive waste glass.

[0038] Comparative Example 1 This comparative example provides a method for suppressing the precipitation of variable-valence metals during the vitrification of high-level radioactive waste from power reactors, and a simulated high-level radioactive waste glass solidified body is prepared. The specific operation is the same as that in Example 1, except that the following components are adjusted while keeping the contents of the remaining components unchanged. In terms of mass percentage of oxides, it is 46.0% SiO2, 12.5% B2O3, 12.5% Na2O, 3.0% Li2O, 2.0% Al2O3, 6.0% CaO, 0.5% MgO, and 0.5% V2O5.

[0039] The theoretical oxidation-reduction potential of the simulated high-level radioactive waste glass was calculated using the theoretical oxidation-reduction potential calculation formula to be approximately 1.5. The reducing property of this simulated high-level radioactive waste glass exceeds the required range of the present invention.

[0040] As Figure 2 and Figure 3 shown, metal precipitation appears at the bottom of the crucible after the simulated high-level radioactive waste glass is melted.

[0041] Comparative Example 2 This comparative example provides a method for suppressing the precipitation problem of variable-valence metals during the vitrification of high-level radioactive waste in a power reactor, and a simulated high-level radioactive glass solidified body is prepared. The specific operation is the same as that in Example 1, except that the following components are adjusted while keeping the contents of the remaining components unchanged. The components are 38.0% SiO2, 20.0% B2O3, 12.0% Na2O, 8.0% Al2O3, and 5.0% CaO in terms of mass percentage of oxides.

[0042] The theoretical oxidation-reduction potential of the simulated high-level radioactive glass is calculated to be approximately 0.1 through the theoretical oxidation-reduction potential calculation formula. The oxidizing property of this simulated high-level radioactive glass exceeds the requirement range of the present invention, and it cannot be melted into a homogeneous glass.

[0043] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for suppressing the precipitation problem of variable-valence metals during the vitrification process of high-level radioactive waste from power reactors, characterized in that, It includes the following steps: S1. Obtain the oxide components of the high-level radioactive waste glass; S2. According to the formula , predict the numerical value of the theoretical oxidation-reduction property of the high-level radioactive waste glass; S3. According to the value of the theoretical oxidation-reduction property in step S2, adjust the oxide components to make the value of the theoretical oxidation-reduction property be 0.2 - 1.2; Among them, R is the value of the theoretical redox property, A is the sum of the products of the coefficients of each oxide component and the molar ratio of oxygen atoms in the oxide component to the total oxygen in the high-level radioactive glass.

2. The method for suppressing the precipitation problem of variable-valence metals during the vitrification of high-level radioactive waste in a power reactor as claimed in claim 1, wherein, In step S3, the value of the theoretical oxidation-reduction property is 0.2 - 0.

9.

3. The method for suppressing the precipitation problem of variable-valence metals during the vitrification of high-level radioactive waste in a power reactor as claimed in claim 1, wherein, In step S3, the value of the theoretical oxidation-reduction property is 0.2 - 0.

5.

4. The method for suppressing the precipitation problem of variable-valence metals during the vitrification of high-level liquid waste from power reactors according to claim 1, wherein The coefficient of SiO2 is 0.48, the coefficient of B2O3 is 0.43, the coefficient of Na2O is 1.15, the coefficient of Li2O is 1.00, the coefficient of Al2O3 is 0.61, the coefficient of CaO is 1.0, the coefficient of ZnO is 0.95, the coefficient of V2O5 is 1.04, the coefficient of BaO is 1.15, and the coefficient of MgO is 0.

78.

5. The method for suppressing the precipitation problem of variable-valence metals during the vitrification of high-level liquid waste from power reactors as claimed in claim 1, characterized in that, The oxide components of the high-level radioactive waste glass include multiple of SiO2, B2O3, Al2O3, CaO, MgO, BaO, Li2O, Na2O, ZnO, V2O5, MoO3, ZrO2, Nd2O3, La2O3, CeO2, Y2O3, Fe2O3, Cr2O3, NiO, MnO2, TeO2, SnO2, BaO, SrO, Cs2O, Rb2O, and K2O.

6. The method for suppressing the precipitation problem of variable-valence metals during the vitrification of high-level radioactive waste in a power reactor as claimed in claim 1, wherein, The preparation method of the high-level radioactive waste glass is as follows: fully mix the borosilicate glass raw materials, heat and melt them, and naturally cool to obtain the base glass, then fully mix the base glass with the high-level radioactive waste, heat and melt them, and obtain the high-level radioactive waste glass after natural cooling.

7. The method for suppressing the precipitation problem of variable-valence metals during the vitrification of high-level radioactive waste in a power reactor as described in claim 1, wherein The temperature of the heating and melting is 1100 - 1300 °C, and the time is 1 - 24 h.

8. The application of the method according to any one of claims 1 - 7 in the formulation design of high-level radioactive waste glass.

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