A method for preparing a transuranium nuclide glass solidified body

Abstract

The present invention relates to a method for preparing a transuranium nuclide glass solid body. The method for preparing a transuranium nuclide glass solid body of the present invention comprises the following steps: 1) mixing granite powder and boron oxide powder and calcining to obtain granite glass powder; 2) uniformly mixing cerium oxide and neodymium oxide to obtain cerium-neodymium oxide; 3) mixing the cerium-neodymium oxide with the granite glass powder as a base material, adding transuranium nuclides, adding a mixing medium and mixing uniformly, and then pressing and molding to obtain a molded body; 4) calcining the molded body at 1200°C-1400°C for 1-3 hours under an inert atmosphere to obtain a transuranium nuclide glass solid body. The preparation method of the present invention utilizes cerium-neodymium oxide in conjunction with granite glass powder to solidify transuranium nuclides under relatively mild conditions, thereby solving the problem of adhesion between the crucible and the solid body during solidification and sintering, and obtaining a transuranium nuclide glass solid body with good chemical stability.

Description

Technical Field

[0001] The invention relates to a method for preparing a transuranium nuclide glass solidification body, belonging to the technical field of nuclear waste industrial treatment and application. Background Art

[0002] High-level waste (HLW), one of the most difficult forms of existing nuclear waste, primarily exists in the form of liquid waste (wastewater). While its volume accounts for less than 1% of the total nuclear waste generated by the nuclear fuel cycle, its radioactivity exceeds 99% of the total radioactivity from the nuclear fuel cycle. Due to its complex and highly volatile composition, HLW imposes stringent requirements on the adaptability (multi-nuclides and components), tolerance (high solid solubility), and stability (mechanical, thermal, and irradiation stability) of its solidification matrix.

[0003] To address high-level radioactive liquid waste, the international community has proposed the technical approaches of "Partitioning and Transmutation (P&T)" and "Partitioning and Conditioning (P&C)," which have become hot topics of international research. P&T involves separating transuranic elements and long-lived fission products (such as Tc-99) from high-level radioactive liquid waste, and then converting them into short-lived or stable nuclides through transmutation. P&C, on the other hand, involves separating actinides and highly radioactive, high-heat-releasing elements such as Sr-90 and Cs-137 through separation methods, even when transmutation is not yet possible. This allows the high-level liquid waste to be converted into low-toxic, intermediate- and low-level radioactive waste. The separated highly radioactive elements are then conditioned separately to reduce the amount of waste requiring deep geological disposal.

[0004] Solidification is a crucial step in ensuring the safe use of nuclear energy. High-level radioactive waste contains highly radioactive nuclides, such as neptunium, plutonium, americium, and technetium. These nuclides are highly toxic and have long half-lives. If leaked, they would have long-term impacts on the environment and human health.

[0005] The effective treatment of high-level radioactive waste is the key to the sustainable development of nuclear energy. Through solidification treatment, the impact of nuclear waste on the environment can be reduced, the public's acceptance of nuclear energy utilization can be improved, and support can be provided for the long-term development of nuclear energy. Summary of the Invention

[0006] Problems to be solved by the invention

[0007] The purpose of the present invention is to solve the problem of solidification of transuranic nuclides after separation of high-level radioactive liquid waste in the prior art, provide a method for preparing transuranic nuclide glass solidification bodies, and provide a more feasible solidification method for permanent disposal of transuranic nuclide waste.

[0008] Solutions for solving problems

[0009] The present invention provides a method for preparing a transuranium nuclide glass solidified body, comprising the following steps:

[0010] 1) Mixing granite powder and boron oxide powder and calcining them to obtain granite glass powder;

[0011] 2) Evenly mixing cerium oxide and neodymium oxide to obtain cerium-neodymium oxide;

[0012] 3) Mixing the cerium-neodymium oxide and the granite glass powder as a base material, adding transuranic nuclides, adding a mixing medium, mixing evenly, and then pressing to obtain a molded body;

[0013] 4) calcining the formed body at 1200° C.-1400° C. for 1-3 hours under an inert atmosphere to obtain a transuranic nuclide glass solidified body.

[0014] According to the preparation method of the present invention, wherein, in step 1), the mass ratio of the granite powder to the boron oxide powder is granite powder:boron oxide powder=(70-90):(10-30).

[0015] According to the preparation method of the present invention, in step 1), the calcination is carried out at 900-1100° C. for 1-3 hours, preferably at 1000° C. for 2 hours.

[0016] According to the preparation method of the present invention, in step 1), the particle size of the granite glass powder is below 200 meshes.

[0017] According to the preparation method of the present invention, in step 2), based on the total mass of cerium oxide and neodymium oxide, the content of cerium oxide is 30-70 wt%, and the content of neodymium oxide is 30-70 wt%.

[0018] According to the preparation method of the present invention, in step 3), based on the total mass of cerium-neodymium oxide and granite glass powder, the content of cerium-neodymium oxide is 10-30 wt%, and the content of granite glass powder is 70-90 wt%.

[0019] According to the preparation method of the present invention, wherein, in step 3), the transuranic nuclide is one or more of Am, Np, and Pu.

[0020] According to the preparation method of the present invention, in step 3), the mixed medium is ethanol, and after mixing evenly, the mixture is pressed at 8-10 MPa for 5-10 minutes to perform compression molding.

[0021] According to the preparation method of the present invention, in step 4), the temperature is raised to 1200°C-1400°C at a heating rate of 5-10°C / min, preferably to 1300°C at a heating rate of 5°C / min, and calcined for 2 hours.

[0022] According to the preparation method of the present invention, the total dose per 1g of the transuranium nuclide glass solidified body is 10 6 -10 7 Bq.

[0023] Effects of the Invention

[0024] The method for preparing a transuranium nuclide glass solid body provided by the present invention utilizes cerium-neodymium oxide in conjunction with granite glass powder to solidify transuranium nuclide radioactive materials under relatively mild conditions, thereby solving the problem of adhesion between the crucible and the solid body during solidification and sintering, obtaining a transuranium nuclide glass solid body with good chemical stability, and laying a foundation for the research and development of the solidification of transuranium nuclides separated from high-level liquid waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 XRD diffraction test pattern of the transuranium nuclide glass solid body-I prepared in Example 1. DETAILED DESCRIPTION

[0026] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The word "exemplary" is used herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior or preferred over other embodiments.

[0027] In addition, numerous specific details are provided in the following detailed description to better illustrate the present invention. Those skilled in the art will appreciate that the present invention can be practiced without certain specific details. In other instances, methods, means, equipment, and steps well known to those skilled in the art are not described in detail in order to highlight the main points of the present invention.

[0028] Unless otherwise stated, the units used in this specification are international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0029] In this specification, the use of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

[0030] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "embodiments," etc., mean that the specific elements (e.g., features, structures, properties, and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

[0031] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

[0032] In this specification, "room temperature" or "normal temperature" means "10-40°C".

[0033] The present invention provides a method for preparing a transuranium nuclide glass solidified body, comprising the following steps:

[0034] 1) Mixing granite powder and boron oxide powder and calcining them to obtain granite glass powder;

[0035] 2) uniformly mixing cerium oxide and neodymium oxide to obtain a cerium-neodymium mixed oxide;

[0036] 3) Using the cerium-neodymium oxide as an inducing agent and the granite glass powder as a base material, adding transuranic nuclides, adding a mixed medium, mixing evenly, and then pressing and molding to obtain a molded body;

[0037] 4) calcining the formed body at 1200° C.-1400° C. for 1-3 hours under an inert atmosphere to obtain a transuranic nuclide glass solidified body.

[0038] The granite glass powder of the present invention has a wide tolerance for different elements and can achieve atomic-scale solidification of nuclides. The obtained transuranium nuclide glass solidification body has excellent chemical and mechanical stability, can resist external impact and vibration, has good radiation resistance, and is suitable for the solidification of high-level radioactive waste.

[0039] Since Ce is tetravalent, similar to radioactive Np / Pu nuclides; and Nd is trivalent, similar to radioactive Am nuclides; CeO2 and Nd2O3 can be well contained in granite glass. According to the principle of isomorphous substitution, CeO2 and Nd2O3 are used to induce radioactive Np / Pu / Am nuclides to solidify in granite glass.

[0040] According to the preparation method of the present invention, in step 1), the mass ratio of the granite powder to the boron oxide powder is granite powder:boron oxide powder=(70-90):(10-30), preferably 80:20.

[0041] According to the preparation method of the present invention, in step 1), the calcination is carried out at 900-1100° C. for 1-3 hours, preferably at 1000° C. for 2 hours.

[0042] According to the preparation method of the present invention, in step 1), the particle size of the granite glass powder is below 200 mesh.

[0043] According to the preparation method of the present invention, in step 2), the cerium oxide content is 30-70 wt%, and the neodymium oxide content is 30-70 wt%, based on the total weight of the cerium oxide and neodymium oxide. Using cerium oxide and neodymium oxide within these content ranges solves the problem of solidifying transuranic nuclides of varying contents.

[0044] According to the preparation method of the present invention, in step 3), based on the total mass of cerium-neodymium oxide and granite glass powder, the content of cerium-neodymium oxide is 10-30wt%, and the content of granite glass powder is 70-90wt%. This content range is conducive to the mixed materials forming a glass solid body.

[0045] According to the preparation method of the present invention, wherein, in step 3), the transuranic nuclide is one or more of Am, Np, and Pu.

[0046] According to the preparation method of the present invention, in step 3), the mixed medium is ethanol. After mixing evenly, the mixture is pressed at 8-10 MPa for 5-10 minutes, preferably at 8 MPa for 10 minutes.

[0047] According to the preparation method of the present invention, in step 4), the temperature is raised to 1200°C-1400°C and calcined at a heating rate of 5-10°C / min, preferably raised to 1300°C at a heating rate of 5°C / min.

[0048] Example

[0049] Preparation Example 1

[0050] 80 wt% of granite powder and 20 wt% of boron oxide powder were mixed evenly, and then calcined at 1000° C. for 2 hours. After cooling, the mixture was ball-milled and sieved to obtain granite glass powder with a size less than 200 mesh.

[0051] Example 1

[0052] Based on the total mass of cerium oxide and neodymium oxide, 30 wt% of cerium oxide and 70 wt% of neodymium oxide are uniformly mixed to obtain a cerium-neodymium mixed oxide;

[0053] Take 0.2 g of dry cerium neodymium oxide and 0.8 g of granite glass powder; add 1×10 6 Bq transuranic nuclides Am / Np / Pu, where Am accounts for 90wt%, Np and Pu each account for 5wt%, add 1.5ml of anhydrous ethanol and mix well;

[0054] Then, the pressure was maintained at 8 MPa for 10 minutes and pressed to obtain a molded body; the molded body was placed in a graphite crucible, and then placed in a quartz tube furnace. Under an inert atmosphere, the temperature was raised to 1300° C. at a rate of 5° C. / min, kept at this temperature for 2 hours, and naturally cooled to room temperature to obtain a transuranic nuclide glass solid body, which was recorded as transuranic nuclide glass solid body-I. During the calcination process, the exhaust gas was absorbed with 0.5 mol / L nitric acid.

[0055] Example 2

[0056] Based on the total mass of cerium oxide and neodymium oxide, 50 wt% of cerium oxide and 50 wt% of neodymium oxide are uniformly mixed to obtain cerium neodymium oxide;

[0057] Take 0.1 g of dry cerium neodymium oxide and 0.9 g of granite glass powder; add 1×10 6 Bq transuranic nuclides Am / Np / Pu, where Am accounts for 90wt%, Np and Pu each account for 5wt%, add 1.5ml of anhydrous ethanol and mix well;

[0058] Then, the pressure was maintained at 9 MPa for 8 minutes to obtain a molded body; the molded body was placed in a graphite crucible, and then placed in a quartz tube furnace. Under an inert atmosphere, the temperature was increased to 1200° C. at a rate of 10° C. / min, and the temperature was maintained for 3 hours. The body was naturally cooled to room temperature to obtain a transuranium nuclide glass solid body, which was recorded as a transuranium nuclide glass solid body transuranium nuclide glass solid body-II. During the calcination process, the tail gas was absorbed with 0.5 mol / L nitric acid.

[0059] Example 3

[0060] Based on the total mass of cerium oxide and neodymium oxide, 70 wt% of cerium oxide and 30 wt% of neodymium oxide are uniformly mixed to obtain a cerium-neodymium mixed oxide;

[0061] Take 0.2 g of dry cerium neodymium oxide and 0.8 g of granite glass powder; add 1×10 6 Bq transuranic nuclides Am / Np / Pu, where Am accounts for 90wt%, Np and Pu each account for 5wt%, add 1.5ml of anhydrous ethanol and mix well;

[0062] Then, the molded body was pressed under 10 MPa for 5 minutes, and the molded body was placed in a graphite crucible, and then placed in a quartz tube furnace. Under an inert atmosphere, the temperature was raised to 1400°C at a rate of 5°C / min, kept for 1 hour, and naturally cooled to room temperature to obtain a transuranium nuclide glass solid body, which was recorded as transuranium nuclide glass solid body-III. During the calcination process, the exhaust gas was absorbed with 0.5 mol / L nitric acid.

[0063] Comparative Example 1

[0064] Take 0.2g of dry cerium oxide and 0.8g of granite glass powder; add transuranic nuclides Am / Np / Pu, where Am accounts for 90wt%, Np and Pu each account for 5wt%;

[0065] Then, the pressure was maintained at 8 MPa for 10 minutes and pressed to obtain a molded body; the molded body was placed in a graphite crucible, and then placed in a quartz tube furnace. Under an inert atmosphere, the temperature was raised to 1300°C at a rate of 5°C / min, kept for 2 hours, and naturally cooled to room temperature to obtain a transuranium nuclide glass solid body, which was recorded as transuranium nuclide glass solid body-IV. During the calcination process, the exhaust gas was absorbed with 0.5 mol / L nitric acid.

[0066] Comparative Example 2

[0067] Take 0.2g of dry neodymium oxide and 0.8g of granite glass powder; add transuranic nuclides Am / Np / Pu, where Am accounts for 90wt%, Np and Pu each account for 5wt%;

[0068] Then, the pressure was maintained at 8 MPa for 10 minutes and pressed to obtain a molded body; the molded body was placed in a graphite crucible, and then placed in a quartz tube furnace. Under an inert atmosphere, the temperature was raised to 1300°C at a rate of 5°C / min, kept for 2 hours, and naturally cooled to room temperature to obtain a transuranium nuclide glass solid body, which was recorded as transuranium nuclide glass solid body-IV. During the calcination process, the exhaust gas was absorbed with 0.5 mol / L nitric acid.

[0069] XRD test

[0070] The crystal structure of the solidified body was tested using a Japanese Rigaku model miniflex600, using CuKa rays (wavelength ), the step size is 0.02°, and the test range is 2theta 10°-70°.

[0071] Depend on Figure 1 It can be seen that the material structure of the transuranium nuclide glass solid body-I is a typical amorphous crystal structure.

[0072] Chemical stability test

[0073] According to the US ASTM C1220-2017 standard, "Standard Test Method for Static Leaching of Monolithic Waste Bodies for Radioactive Waste Treatment," a specimen of known geometric surface area (S) is immersed in a leaching container containing a known volume (V) of leaching agent. The sealed container is placed in a thermostat and maintained at a set temperature for a specified time. After the specified time, the container is removed from the thermostat, cooled to room temperature, and then opened. Leaching is then conducted at 90°C for 14 days to assess chemical stability. The normalized leaching rate of transuranic nuclides is shown in the table below. The quartz tube is then cleaned three times with 0.5 mol / L nitric acid, a tail gas absorption solution. The cleaning solution test results are shown in the table below.

[0074] Normalized leaching rate of transuranic nuclides Cleaning fluid test Example 1 <![CDATA[2.45×10 -4 g / m 2 .d]]> Non-radioactive transuranic nuclides Example 2 <![CDATA[3.85×10 -4 g / m 2 .d]]> Non-radioactive transuranic nuclides Example 3 <![CDATA[3.11×10 -4 g / m 2 .d]]> Non-radioactive transuranic nuclides Comparative Example 1 <![CDATA[2.68×10 -2 g / m 2 .d]]> Non-radioactive transuranic nuclides Comparative Example 2 <![CDATA[4.89×10 -3 g / m 2 .d]]> Non-radioactive transuranic nuclides

[0075] It should be noted that, although the technical solutions of the present invention are described with specific examples, those skilled in the art will appreciate that the present invention should not be limited thereto.

[0076] While various embodiments of the present invention have been described above, the above descriptions are intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing a transuranium nuclide glass solidified body, characterized in that: The steps include: 1) Mixing granite powder and boron oxide powder and calcining them to obtain granite glass powder; 2) Evenly mixing cerium oxide and neodymium oxide to obtain cerium-neodymium oxide; 3) Mixing the cerium-neodymium oxide and the granite glass powder as a base material, adding transuranic nuclides, adding a mixing medium, mixing evenly, and then pressing to obtain a molded body; 4) calcining the formed body at 1200° C.-1400° C. for 1-3 hours under an inert atmosphere to obtain a transuranic nuclide glass solidified body.

2. The preparation method according to claim 1, wherein In step 1), the mass ratio of the granite powder to the boron oxide powder is granite powder:boron oxide powder=(70-90):(10-30).

3. The preparation method according to claim 1 or 2, wherein In step 1), calcination is performed at 900-1100° C. for 1-3 hours.

4. The preparation method according to claim 1 or 2, wherein In step 1), the particle size of the granite glass powder is below 200 meshes.

5. The preparation method according to claim 1 or 2, wherein In step 2), based on the total mass of cerium oxide and neodymium oxide, the content of cerium oxide is 30-70 wt%, and the content of neodymium oxide is 30-70 wt%.

6. The preparation method according to claim 1 or 2, wherein In step 3), based on the total weight of the cerium-neodymium oxide and the granite glass powder, the content of the cerium-neodymium oxide is 10-30 wt %, and the content of the granite glass powder is 70-90 wt %.

7. The preparation method according to claim 1 or 2, wherein In step 3), the transuranic nuclides are one or more of Am, Np, and Pu.

8. The preparation method according to claim 1 or 2, wherein In step 3), the mixed medium is ethanol, and after being mixed evenly, the mixture is pressed at 8-10 MPa for 5-10 minutes to perform compression molding.

9. The preparation method according to claim 1 or 2, wherein In step 4), the temperature is raised to 1200° C.-1400° C. at a heating rate of 5-10° C. / min and calcined.

10. The preparation method according to claim 1 or 2, wherein Calculated by radiation dose, the total dose per 1g of the transuranium nuclide glass solidified body is 10 6 -10 7 Bq.

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