A method and application for suppressing the precipitation of variable valence metals during vitrification of high-level radioactive waste in power reactors

Abstract

The present invention proposes a method and application for suppressing the precipitation of variable-valence metals during the glass solidification process of high-level radioactive waste liquid in power reactors. The method comprises the following steps: S1, obtaining the oxide components of the high-level radioactive waste glass; S2, predicting the theoretical redox value of the high-level radioactive waste glass according to the formula #imgabs0#; S3, adjusting the oxide components according to the theoretical redox value obtained in step S2, so that the theoretical redox value is 0.2-1.2; wherein, R is the theoretical redox value, A The coefficient is the sum of the coefficients of each oxide component and the molar ratio of oxygen atoms in that oxide component to the total oxygen in the high-level radioactive glass. This method controls the redox properties of the glass to avoid metal precipitation caused by redox reactions of variable-valence metal elements during the vitrification of high-level radioactive waste, thereby ensuring safe and stable operation of the vitrification furnace.

Description

Technical Field

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

[0002] Vitrification, the most widely accepted and widely used method for treating high-level radioactive liquid waste worldwide, involves calcining and melting high-level liquid waste with glass additives at high temperatures. This process fixes the radioactive nuclides within a glass network at the atomic scale, thereby preventing their migration into the external environment. To effectively utilize nuclear fuel resources, nuclear energy is trending toward high-burnup reactors. However, at the same time, the high-level liquid waste produced by spent fuel reprocessing contains elevated levels of waste components such as fission products, primarily transuranic elements and transition metals produced by fission. Due to the complex composition of high-level liquid waste and the high concentration of variable-valence elements in its composition, the high-temperature vitrification and melting process involves extremely complex physical and chemical reactions. Consequently, the transition of high-level liquid waste to the glassy state has long been considered a "black box" process, frequently encountering new problems and challenges during the vitrification process.

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

[0004] In view of this, the present invention proposes a method and application for suppressing the problem of variable-valence metal precipitation during the glass solidification process of high-level radioactive waste in power reactors. The method avoids the problem of metal precipitation caused by the redox reaction of variable-valence metal elements during the glass solidification process of high-level radioactive waste by controlling the redox properties of the glass, thereby ensuring the safe and stable operation of the glass solidification furnace.

[0005] The technical solution of the present invention is achieved as follows:

[0006] In a 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 in power reactors, comprising the following steps:

[0007] S1. Obtaining oxide components of high-energy glass;

[0008] S2, according to the formula , predicting the theoretical redox value of the high-energy glass;

[0009] S3, adjusting the oxide component according to the value of the theoretical redox property in step S2 so that the theoretical redox property is 0.2 to 1.2;

[0010] in, R is the theoretical redox value, A It is the sum of the coefficients of each oxide component and the product of the molar ratio of oxygen atoms in the oxide component to the total oxygen in the high-energy glass.

[0011] On the basis of the above technical solution, further, the value of the theoretical redox property in step S3 is 0.2-0.9.

[0012] On the basis of the above technical solution, further, the value of the theoretical redox property in step S3 is 0.2-0.5.

[0013] The theoretical redox value is R When the ratio is less than 0.2, the glass melt is highly oxidizing and the proportion of glass network modifiers is small, making it impossible to melt into a homogeneous glass within the limited temperature range. When the ratio is greater than 1.2, the glass melt is highly reducing and the variable valence metals in the glass melt are more easily reduced to a low valence state, causing metal precipitation problems. When the ratio is between 0.2 and 1.2, the glass has moderate redox properties and good melting properties.

[0014] On the basis of the above technical solution, 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.

[0015] The coefficient values corresponding to each oxide are shown in Table 1, which shows the coefficient values corresponding to SiO2, B2O3, Na2O, Li2O, etc.

[0016] Table 1 Coefficient values corresponding to various oxides

[0017]

[0018] On the basis of the above technical solution, further, the oxide components of the high-energy glass include multiple ones 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.

[0019] On the basis of the above technical solution, further, the preparation method of the high-level radioactive glass is as follows: borosilicate glass raw materials are fully mixed, heated and melted, and naturally cooled to obtain base glass; the base glass is fully mixed with high-level radioactive waste, heated and melted, and naturally cooled to obtain the high-level radioactive glass.

[0020] On the basis of the above technical solution, further, the heating and melting temperature is 1100-1300° C., and the time is 1-24 h.

[0021] On the basis of the above technical solution, further, the oxide components of the base glass include multiple ones of SiO2, B2O3, Na2O, Li2O, Al2O3, CaO, V2O5, BaO and MgO.

[0022] In a second aspect, the present invention provides the application of the above-mentioned method for suppressing the precipitation of variable-valence metals during the glass solidification process of high-level radioactive waste liquid in power reactors in the formulation design of high-level radioactive glass.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The method provided by the present invention for suppressing the problem of variable-valence metal precipitation during the solidification process of high-level radioactive waste liquid in power reactors can effectively suppress the reduction of variable-valence metal ions, thereby achieving efficient solidification of high-level radioactive waste liquid while avoiding the precipitation of variable-valence metals in high-level radioactive glass, maintaining good process performance and solidified body performance, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 The XRD patterns of the uniform high-energy glass solids obtained in Examples 1 to 3 of the present invention are as follows;

[0027] Figure 2 This is a micrograph of the valence-varied metal precipitated in the high-energy glass solidified body obtained in Comparative Example 1 of the present invention;

[0028] Figure 3 The XRD pattern of the variable valence metal precipitated in the high-energy glass solid body prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] Example 1

[0031] Example 1 provides a method for suppressing the precipitation of variable-valence metals during the glass solidification process of high-level radioactive waste liquid in power reactors, and produces a simulated high-level radioactive glass solidification body.

[0032] The oxide composition includes the following percentages by mass: 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。

[0033] The steps include: 1) calculating the basic glass composition, weighing borosilicate glass raw materials and mixing them uniformly, heating and melting them in a muffle furnace at 1200°C for 1 hour, and naturally cooling the glass liquid in air and then crushing it to obtain borosilicate basic glass with a particle size of approximately 2 mm;

[0034] The basic glass particles were mixed with dried simulated high-level radioactive waste from a power reactor according to a calculated ratio, heated and melted in a muffle furnace at 1150° C. for 2 h, and the glass liquid was naturally cooled in air to obtain about 100 g of a simulated high-level radioactive glass solid.

[0035] The theoretical redox property of the simulated high-energy-density glass is calculated to be approximately 0.3 using the theoretical redox property calculation formula, which is within the required range of the present invention.

[0036] like Figure 1As shown in the figure, the simulated HFA glass after melting has good homogeneity and no metal precipitation. This indicates that controlling the redox properties of HFA glass can inhibit the precipitation of metal in HFA glass.

[0037] Example 2

[0038] This embodiment provides a method for suppressing the precipitation of variable-valence metals during the vitrification process of high-level radioactive waste from power reactors. A simulated high-level radioactive glass solidification body is prepared. The specific operation is the same as that of Example 1, except that the following components are adjusted while keeping the contents of the other components unchanged: 42% SiO2, 17.5% B2O3, 8.5% Na2O, 2.5% Li2O, 7.5% Al2O3, and 5.0% CaO, calculated by mass percentage of oxides.

[0039] The theoretical redox property of the simulated high-radiation glass is calculated to be about 0.2 by using a theoretical redox property calculation formula. This theoretical redox property of the simulated high-radiation glass is within the required range of the present invention.

[0040] like Figure 1 As shown in the figure, the simulated HFA glass after melting has good homogeneity and no metal precipitation. This indicates that controlling the redox properties of HFA glass can inhibit the precipitation of metal in HFA glass.

[0041] Example 3

[0042] This embodiment provides a method for suppressing the precipitation of variable-valence metals during the vitrification process of high-level radioactive waste from power reactors. A simulated high-level radioactive glass solidification body is prepared. The specific operation is the same as that of Example 1, except that the following components are adjusted while keeping the contents of the other components unchanged: 43.0% SiO2, 14.5% B2O3, 10.5% Na2O, 2.5% Li2O, 7.5% Al2O3, and 5.0% CaO, calculated by mass percentage of oxides.

[0043] The theoretical redox property of the simulated high-radiation glass is calculated to be about 0.4 by using a theoretical redox property calculation formula. This theoretical redox property of the simulated high-radiation glass is within the required range of the present invention.

[0044] like Figure 1 As shown in the figure, the simulated HFA glass after melting has good homogeneity and no metal precipitation. This indicates that controlling the redox properties of HFA glass can inhibit the precipitation of metal in HFA glass.

[0045] Example 4

[0046] This embodiment provides a method for suppressing the precipitation of variable-valence metals during the vitrification process of high-level radioactive waste from power reactors. A simulated high-level radioactive glass solidification body is prepared. The specific operation is the same as that of Example 1, except that the following components are adjusted while keeping the contents of the other components unchanged: 45.0% SiO2, 14.0% B2O3, 13.0% Na2O, 3.0% Li2O, 3.0% Al2O3, and 5.0% CaO, calculated by mass percentage of oxides.

[0047] The theoretical redox property of the simulated high-radiation glass is calculated to be about 0.9 by using a theoretical redox property calculation formula. This theoretical redox property of the simulated high-radiation glass is within the required range of the present invention.

[0048] The simulated HFA glass after melting has good homogeneity and no metal precipitation. This shows that controlling the redox properties of HFA glass can inhibit the precipitation of metal in HFA glass.

[0049] Example 5

[0050] This embodiment provides a method for suppressing the precipitation of variable-valence metals during the vitrification process of high-level radioactive waste from power reactors. A simulated high-level radioactive glass solidification body is prepared. The specific operation is the same as that of Example 1, except that the following components are adjusted while keeping the contents of the other components unchanged: 44.5% SiO2, 14.0% B2O3, 13.0% Na2O, 3.5% Li2O, 3.5% Al2O3, 4.0% CaO, and 0.5% V2O5, calculated as oxide mass percentage.

[0051] The theoretical redox property of the simulated high-radiation glass is calculated to be approximately 1.2 using a theoretical redox property calculation formula. This theoretical redox property of the simulated high-radiation glass is within the required range of the present invention.

[0052] The simulated HFA glass after melting has good homogeneity and no metal precipitation. This indicates that the precipitation of variable-valence metals in HFA glass can be suppressed by controlling the redox properties of HFA glass.

[0053] Comparative Example 1

[0054] This comparative example provides a method for suppressing the precipitation of variable-valence metals during the vitrification process of high-level radioactive waste from power reactors. A simulated high-level radioactive glass solidification body is prepared. The specific operation is the same as that of Example 1, except that the following components are adjusted while keeping the contents of the other components unchanged: 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, calculated as oxide mass percentage.

[0055] The theoretical redox property of the simulated high-energy-density glass was calculated to be about 1.5 using the theoretical redox property calculation formula. The redox property of the simulated high-energy-density glass exceeds the required range of the present invention.

[0056] like Figure 2 and Figure 3 As shown in Figure 1, metal precipitation appears at the bottom of the crucible after simulating high-pressure glass melting.

[0057] Comparative Example 2

[0058] This comparative example provides a method for suppressing the precipitation of variable-valence metals during the vitrification process of high-level radioactive waste from power reactors. A simulated high-level radioactive glass solidification body is prepared. The specific operation is the same as that of Example 1, except that the following components are adjusted while keeping the contents of the other components unchanged: 38.0% SiO2, 20.0% B2O3, 12.0% Na2O, 8.0% Al2O3, and 5.0% CaO, calculated by mass percentage of oxides.

[0059] Theoretical redox property of the simulated high-energy-density glass was calculated to be about 0.1 by using the theoretical redox property calculation formula. The redox property of the simulated high-energy-density glass exceeded the required range of the present invention and could not be melted into homogeneous glass.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for suppressing the precipitation of variable valence metals during the vitrification process of high-level radioactive waste in power reactors, characterized in that: The following steps are involved: S1. Obtaining oxide components of high-energy glass; S2, according to the formula , predicting the theoretical redox value of the high-energy glass; S3, adjusting the oxide component according to the value of the theoretical redox property in step S2 so that the value of the theoretical redox property is 0.2-1.2; in, R is the theoretical redox value, A It is the sum of the coefficients of each oxide component and the product of the molar ratio of oxygen atoms in the oxide component to the total oxygen in the high-energy glass.

2. The method for suppressing the precipitation of variable valence metals during the vitrification process of high-level radioactive waste in power reactors according to claim 1, characterized in that: The theoretical redox value in step S3 is 0.2-0.

9.

3. The method for suppressing the precipitation of variable valence metals during the vitrification process of high-level radioactive waste in power reactors according to claim 1, characterized in that: The value of the theoretical redox property in step S3 is 0.2-0.

5.

4. The method for suppressing the precipitation of variable valence metals during the vitrification process of high-level radioactive waste in power reactors according to claim 1, characterized in that: 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 of variable valence metals during the vitrification process of high-level radioactive waste in power reactors according to claim 1, characterized in that: The oxide components of the high-energy glass include multiple ones 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 of variable valence metals during the vitrification process of high-level radioactive waste in power reactors according to claim 1, characterized in that: The preparation method of the high-radioactive glass comprises: fully mixing borosilicate glass raw materials, heating and melting, and naturally cooling to obtain base glass; and fully mixing the base glass with high-radioactive waste, heating and melting, and naturally cooling to obtain the high-radioactive glass.

7. The method for suppressing the precipitation of variable valence metals during the vitrification process of high-level radioactive waste in power reactors according to claim 6, characterized in that: The heating and melting temperature is 1100-1300° C., and the time is 1-24 h.

8. Use of the method according to any one of claims 1 to 7 in the formulation design of high-energy-density glass.

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