Evaluation Method for Solidification Treatment of Radioactive Waste and Feasibility Evaluation Method for Substitute Nuclides

Abstract

The present invention relates to a method for evaluating the solidification treatment of radioactive waste and a method for evaluating the feasibility of alternative nuclides. The method for evaluating the feasibility of alternative nuclides includes: obtaining at least one actinide nuclide in the solidification treatment of radioactive waste; preparing a single crystal of trivalent coordination salt of the actinide nuclide in a simulated coordination environment for the solidification treatment of radioactive waste; preparing a single crystal of trivalent coordination salt of the lanthanide nuclide in the same simulated coordination environment; comparing the crystal structures of the single crystals of trivalent coordination salts of the actinide nuclide and the lanthanide nuclide; and obtaining the evaluation result of the feasibility evaluation according to the comparison result. By preparing single crystals of trivalent coordination salts of actinide and lanthanide nuclides under the same conditions, comparing the crystal structures of the single crystals, and based on the comparison result, it can be determined whether the lanthanide nuclide can replace the actinide nuclide for use in the research on the evaluation of the solidification treatment of radioactive waste.

Description

Technical Field

[0001] The present invention relates to the technical field of solidification treatment of radionuclides, and particularly relates to a method for evaluating the solidification treatment of radioactive waste and a method for evaluating the feasibility of alternative nuclides. Background Art

[0002] The solidification treatment of radioactive waste is a treatment technology that converts radioactive waste into a stable solid by means of a solidification matrix, fixing the radionuclides, and transforming liquid or solid waste into a monolithic solidification body with performance indicators meeting the disposal requirements. The purpose of the solidification treatment is to form an object suitable for handling, transportation, and temporary storage, with performance meeting the disposal requirements. The solidification product is called a solidification body. The solidification body should have as good chemical stability (especially a low leaching rate), mechanical stability, thermal stability, and radiation stability as possible. The solidification method should have a high waste loading capacity, good compatibility between the solidification matrix and the waste components, and a simple process with low treatment costs. According to the different solidification matrices, the solidification treatment can be divided into cement solidification, asphalt solidification, polymer solidification, glass solidification, artificial rock solidification, and so on.

[0003] Due to the characteristics of strong radiolysis, strong radioactivity, and high chemical and radiological toxicity of actinides and minor actinides, for safety considerations, when studying the solidification treatment of radionuclides, lanthanides with properties similar to those of actinides and minor actinides are usually used as substitutes to simulate and study the solidification treatment of actinides and minor actinides. However, the differences in the physical and chemical properties of radionuclides and their alternative nuclides will lead to significant deviations during the solidification process. Summary of the Invention

[0004] Based on this, it is necessary to provide a method for evaluating the feasibility of alternative nuclides in the solidification treatment of radioactive waste that can judge the feasibility of alternative nuclides to guide the research on the solidification treatment of radionuclides.

[0005] One aspect of the present invention provides a method for evaluating the feasibility of alternative nuclides in the solidification treatment of radioactive waste, including the following steps:

[0006] Obtain at least one actinide nuclide in the solidification treatment of the radioactive waste;

[0007] Prepare a single crystal of trivalent coordination salt of the actinide nuclide in the simulated coordination environment of the solidification treatment of the radioactive waste;

[0008] Prepare a single crystal of trivalent coordination salt of the lanthanide nuclide in the same simulated coordination environment;

[0009] Compare the crystal structures of the single crystal of trivalent coordination salt of the actinide nuclide and the single crystal of trivalent coordination salt of the lanthanide nuclide to obtain a comparison result;

[0010] According to the comparison result, the evaluation result of the feasibility evaluation is obtained.

[0011] In some embodiments, the ligand source in the simulated coordination environment includes at least one of phosphate, silicate, and borate.

[0012] In some embodiments, the raw materials for preparing the trivalent coordination salt single crystal of the actinide nuclide further include an actinide nuclide source, the actinide nuclide source is selected from soluble trivalent salts of actinide nuclides, and the reaction temperature between the actinide nuclide source and the ligand source is 150°C to 200°C.

[0013] In some embodiments, the raw materials for preparing the trivalent coordination salt single crystal of the lanthanide nuclide further include a lanthanide nuclide source, the lanthanide nuclide source is selected from soluble trivalent salts of lanthanide nuclides, and the reaction temperature between the lanthanide nuclide source and the ligand source is 150°C to 200°C.

[0014] In some embodiments, both the trivalent coordination salt single crystal of the actinide nuclide and the trivalent coordination salt single crystal of the lanthanide nuclide are phosphate single crystals, and the ligands in the trivalent coordination salt single crystal of the actinide nuclide and the trivalent coordination salt single crystal of the lanthanide nuclide are each independently selected from one of organic phosphonic acid ligands and inorganic phosphoric acid ligands.

[0015] In some embodiments, the ligand sources of both the trivalent coordination salt single crystal of the actinide nuclide and the trivalent coordination salt single crystal of the lanthanide nuclide are methylenediphosphonic acid;

[0016] The trivalent coordination salt single crystal of the actinide nuclide is prepared by a hydrothermal reaction of methylenediphosphonic acid and the trivalent chloride of the actinide nuclide at 150°C to 200°C;

[0017] The trivalent coordination salt single crystal of the lanthanide nuclide is prepared by a hydrothermal reaction of methylenediphosphonic acid and the trivalent chloride of the lanthanide nuclide at 150°C to 200°C.

[0018] In some embodiments, both the trivalent coordination salt single crystal of the actinide nuclide and the trivalent coordination salt single crystal of the lanthanide nuclide are silicate single crystals, and the ligand sources of the trivalent coordination salt single crystal of the actinide nuclide and the trivalent coordination salt single crystal of the lanthanide nuclide are selected from one of organic silicic acid ligands and inorganic silicic acid ligands.

[0019] In some embodiments, both the trivalent coordination salt single crystal of the actinide nuclide and the trivalent coordination salt single crystal of the lanthanide nuclide are borate single crystals, and the ligand sources of the trivalent coordination salt single crystal of the actinide nuclide and the trivalent coordination salt single crystal of the lanthanide nuclide are selected from one of organic boric acid ligands and inorganic boric acid ligands.

[0020] In some of these embodiments, in the step of comparing the crystal structures of the trivalent coordination salt single crystals of the actinide nuclides and the trivalent coordination salt single crystals of the lanthanide nuclides, it includes:

[0021] Comparing whether the crystal forms of the trivalent coordination salt single crystals of the lanthanide nuclides and the trivalent coordination salt single crystals of the actinide nuclides are the same;

[0022] In the step of obtaining the evaluation result of the feasibility evaluation according to the comparison result, it includes:

[0023] If the crystal forms of the trivalent coordination salt single crystals of the lanthanide nuclides and the trivalent coordination salt single crystals of the actinide nuclides are the same, then the lanthanide nuclides can be used as alternative nuclides in the solidification treatment of the radioactive waste;

[0024] If the crystal forms of the trivalent coordination salt single crystals of the lanthanide nuclides and the trivalent coordination salt single crystals of the actinide nuclides are different, then the lanthanide nuclides are not selected as alternative nuclides in the solidification treatment of the radioactive waste.

[0025] In some of these embodiments, in the step of comparing the crystal structures of the trivalent coordination salt single crystals of the actinide nuclides and the trivalent coordination salt single crystals of the lanthanide nuclides, it further includes: comparing the ionic radius sizes of the trivalent ions of the lanthanide nuclides and the trivalent ions of the actinide nuclides;

[0026] In the step of obtaining the evaluation result of the feasibility evaluation according to the comparison result, it further includes:

[0027] If the crystal forms of the trivalent coordination salt single crystals of the lanthanide nuclides and the trivalent coordination salt single crystals of the actinide nuclides are the same, and the ionic radii of the trivalent ions of the lanthanide nuclides and the trivalent ions of the actinide nuclides are the closest, then the lanthanide nuclides are selected as alternative nuclides in the solidification treatment of the radioactive waste.

[0028] On the other hand, the present invention further provides a method for evaluating the solidification treatment of radioactive waste, including the following steps:

[0029] Adopting the above-mentioned method for evaluating the feasibility of alternative nuclides in the solidification treatment of radioactive waste to obtain the alternative lanthanide nuclides corresponding to at least one actinide nuclide in the radioactive waste;

[0030] Using the alternative lanthanide nuclides to replace the actinide nuclides in the radioactive waste to prepare a solidified body;

[0031] Obtaining the evaluation result of the stability of the solidified body.

[0032] In some of these embodiments, the actinide nuclides in the radioactive waste are at least one of plutonium and americium; the alternative lanthanide nuclides are selected from at least one of neodymium and samarium.

[0033] The above-mentioned feasibility evaluation method for alternative nuclides in radioactive waste solidification treatment prepares single crystals of trivalent coordination salts of actinide nuclides and lanthanide nuclides in the same simulated coordination environment, compares the crystal structures of the single crystals of trivalent coordination salts of actinide nuclides and the single crystals of trivalent coordination salts of lanthanide nuclides to obtain a comparison result, and based on the comparison result, it can be determined whether the alternative nuclide can replace the actinide nuclide for use in the research of radioactive waste solidification treatment evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the crystal structure of R[CH2(PO3H 0.5 )2](R = La~Sm; Pu) prepared in an embodiment of the present invention;

[0035] Figure 2 Schematic diagram of the crystal structure of NaRE[CH2(PO3)2](RE = La~Dy; Am) prepared in an embodiment of the present invention;

[0036] Figure 3 Schematic diagram of the crystal structure of NaQ[CH2(PO3H 0.5 )2]·(H2O)(Q = Yb, Lu) prepared in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0039] In the traditional research on radioactive nuclide solidification treatment, for safety considerations, lanthanide elements with structures and properties relatively close to those of radioactive nuclides are usually used as alternative nuclides for solidification treatment research. However, due to the differences in the basic physical and chemical properties between radioactive nuclides and their alternative nuclides, significant differences will occur in the types, contents, and stabilities of nuclide solidified bodies in the solidification treatment. However, there is still a lack of research on methods for judging the feasibility of alternative nuclides replacing radioactive nuclides.

[0040] An embodiment of the present invention provides a method for evaluating the feasibility of substituting nuclides in the solidification treatment of radioactive waste, including the following steps S110 to S150.

[0041] Step S110: Obtain at least one actinide nuclide in the solidification treatment of radioactive waste.

[0042] Step S120: Prepare single crystals of trivalent coordination salts of actinide nuclides in a simulated coordination environment for the solidification treatment of radioactive waste.

[0043] Step S130: Prepare single crystals of trivalent coordination salts of lanthanide nuclides in the same simulated coordination environment.

[0044] Step S140: Compare the crystal structures of the single crystals of trivalent coordination salts of actinide nuclides and the single crystals of trivalent coordination salts of lanthanide nuclides to obtain a comparison result.

[0045] Step S150: Obtain the evaluation result of the feasibility evaluation according to the comparison result.

[0046] In the above method for evaluating the feasibility of substituting nuclides in the solidification treatment of radioactive waste, by preparing single crystals of trivalent coordination salts of actinide nuclides and lanthanide nuclides in the same simulated coordination environment, comparing the crystal structures of the single crystals of trivalent coordination salts of actinide nuclides and the single crystals of trivalent coordination salts of lanthanide nuclides to obtain a comparison result, and according to the comparison result, it can be determined whether the substituting nuclide can replace the actinide nuclide for use in the research of the evaluation of the solidification treatment of radioactive waste.

[0047] In some of these embodiments, the ligand source in the simulated coordination environment of step S120 includes at least one of phosphate, silicate, and borate. Specifically, according to the different solidified bodies in the solidification treatment of radioactive waste, the preparation raw materials in the simulated coordination environment are different. The solidified body can be selected from one of glass and ceramic.

[0048] In some of these embodiments, the raw materials for preparing the single crystals of trivalent coordination salts of actinide nuclides further include an actinide nuclide source, and the actinide nuclide source is selected from soluble trivalent salts of actinide nuclides. The reaction temperature between the actinide nuclide source and the ligand source is 150°C to 200°C.

[0049] Specifically, the actinide nuclide can be selected from at least one of plutonium (Pu) and americium (Am). The soluble trivalent salt of the actinide nuclide can be selected from one of the trivalent nitrates of the actinide nuclide and the trivalent chlorides of the actinide nuclide.

[0050] In some of these embodiments, the raw materials for preparing the single crystals of trivalent coordination salts of lanthanide nuclides further include a lanthanide nuclide source, and the lanthanide nuclide source is selected from soluble trivalent salts of lanthanide nuclides. The reaction temperature between the lanthanide nuclide source and the ligand source is 150°C to 200°C.

[0051] Specifically, the lanthanide nuclides can be selected from at least one of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), ytterbium (Yb), and lutetium (Lu). The soluble trivalent salts of lanthanide nuclides can be selected from one of the trivalent nitrates of lanthanide nuclides and the trivalent chlorides of lanthanide nuclides.

[0052] In some of these embodiments, both the trivalent coordination salt single crystals of actinide nuclides and the trivalent coordination salt single crystals of lanthanide nuclides are phosphate single crystals, and the ligands in the trivalent coordination salt single crystals of actinide nuclides and the trivalent coordination salt single crystals of lanthanide nuclides are each independently selected from one of organic phosphonic acid ligands and inorganic phosphoric acid ligands.

[0053] Specifically, the organic phosphonic acid ligand can be selected from one of methylenediphosphonic acid, 1,2-benzenediphosphonic acid, 1,4-butanediphosphonic acid, hydroxyethylidenediphosphonic acid, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, o-xylenediphosphonic acid, 2,5-dihydroxy-1,4-benzenediphosphonic acid, biphenyl-4,4-diphosphonic acid, 2,2-bipyridine-4,4-bisphosphonic acid, benzene-1,3,5-triyltris(phosphonic acid), adamantane tetraphosphate, and tetraphenylphosphonium silane. The inorganic phosphoric acid ligand can be selected from one of dihydrogen phosphates, hydrogen phosphates, orthophosphates, pyrophosphates, and metaphosphates.

[0054] In some of these embodiments, the ligand sources of both the trivalent coordination salt single crystals of actinide nuclides and the trivalent coordination salt single crystals of lanthanide nuclides are methylenediphosphonic acid.

[0055] The trivalent coordination salt single crystals of actinide nuclides are prepared by hydrothermal reaction of methylenediphosphonic acid with the trivalent chlorides of actinide nuclides at 150°C to 200°C.

[0056] The trivalent coordination salt single crystals of lanthanide nuclides are prepared by hydrothermal reaction of methylenediphosphonic acid with the trivalent chlorides of lanthanide nuclides at 150°C to 200°C.

[0057] In some of these embodiments, the trivalent coordination salt single crystals of actinide nuclides and the trivalent coordination salt single crystals of lanthanide nuclides are silicate single crystals, and the ligand sources of the trivalent coordination salt single crystals of actinide nuclides and the trivalent coordination salt single crystals of lanthanide nuclides are selected from one of organic silicate ligands and inorganic silicate ligands.

[0058] Specifically, the organic silicate ligand can be selected from one of silanol, silanetriol, trimethoxysilane, phenyltriethoxysilane, ethyl silicate, sodium methyl silicate, sodium vinyl silicate, sodium aminopropyl silicate, and sodium polyether organodisilicate. The inorganic silicate ligand can be selected from one of silicon dioxide, sodium silicate, potassium silicate, sodium metasilicate, sodium aluminosilicate, and magnesium aluminosilicate.

[0059] In some of these embodiments, the trivalent coordination salt single crystals of actinide nuclides and the trivalent coordination salt single crystals of lanthanide nuclides are borate single crystals, and the ligand source of the trivalent coordination salt single crystals of actinide nuclides and the trivalent coordination salt single crystals of lanthanide nuclides is selected from one of organic boric acid ligands and inorganic boric acid ligands.

[0060] Specifically, the organic boric acid ligand can be selected from methylboronic acid, phenylboronic acid, 1,4-benzenediboronic acid, 4,4-biphenyldiboronic acid, 2,2-bipyridine-4,4-diboronic acid, 2,6-naphthalenediylbisboronic acid, and bisthiophenediboronic acid. The inorganic boric acid ligand can be selected from one of boron trioxide, borate, tetraborate, perborate, and metaborate.

[0061] In some of these embodiments, in step S130, if single crystals of lanthanide nuclides are not formed, the lanthanide nuclides are not used as substitute nuclides in the solidification treatment of radioactive waste.

[0062] In some of these embodiments, in step S140, it includes:

[0063] Step S141: Comparing whether the crystal forms of the trivalent coordination salt single crystals of lanthanide nuclides and the trivalent coordination single crystals of actinide nuclides are the same.

[0064] Before step S141, it also includes the steps of measuring and analyzing the crystal structures of the trivalent coordination salt single crystals of lanthanide nuclides and the trivalent coordination salt single crystals of actinide nuclides.

[0065] In some of these embodiments, the trivalent coordination salt single crystals of lanthanide nuclides and the trivalent coordination salt single crystals of actinide nuclides respectively measure the diffraction intensity data of the single crystals through an X-ray diffractometer.

[0066] In some of these embodiments, the SHELXTL program is used to analyze the diffraction intensity data of the single crystals. Further, the steps of using the SHELXTL program to analyze the diffraction intensity data of the single crystals include initial solution and refinement.

[0067] In step S150, it includes:

[0068] If the crystal forms of the trivalent coordination salt single crystals of lanthanide nuclides and the trivalent coordination salt single crystals of actinide nuclides are the same, the lanthanide nuclides can be used as substitute nuclides in the solidification treatment of radioactive waste;

[0069] If the crystal forms of the trivalent coordination salt single crystals of lanthanide nuclides and the trivalent coordination salt single crystals of actinide nuclides are different, the lanthanide nuclides are not selected as substitute nuclides in the solidification treatment of radioactive waste.

[0070] In some of these embodiments, in step S140, it also includes:

[0071] Step S142: Compare the ionic radii of trivalent ions of lanthanide nuclides and trivalent ions of actinide nuclides.

[0072] In step S150, it further includes:

[0073] If the crystal forms of the trivalent coordination salt single crystals of lanthanide nuclides and the trivalent coordination salt single crystals of actinide nuclides are the same, and the ionic radii of the trivalent ions of lanthanide nuclides and the trivalent ions of actinide nuclides are the closest, then select the lanthanide nuclide as the alternative nuclide in the solidification treatment of radioactive waste.

[0074] Optionally, in step S140, it further includes:

[0075] Step S143: Perform density functional theory (DFT) calculations on the trivalent coordination salt single crystals of lanthanide nuclides and the trivalent coordination salt single crystals of actinide nuclides, and compare the coordination abilities of different nuclides.

[0076] In step S150, it further includes:

[0077] According to the electron distribution of the trivalent ions of lanthanide nuclides and the trivalent ions of actinide nuclides, a lanthanide nuclide closer to the actinide nuclide can be further selected as the alternative nuclide in the solidification treatment of radioactive waste.

[0078] In some embodiments, the preparation method of the trivalent coordination phosphate single crystals of actinide nuclides and lanthanide nuclides includes the following steps:

[0079] Prepare the trivalent coordination phosphate single crystal of actinide nuclide: Mix the trivalent chloride of actinide nuclide with deionized water, methylenediphosphonic acid and NaOH aqueous solution, and heat for reaction; cool the reaction solution to room temperature and wash with cold water to obtain crystals.

[0080] Specifically, the heating reaction is carried out in a muffle furnace. The temperature of the heating reaction is 150°C to 200°C. The heating time is 2 days to 5 days. Optionally, the heating temperature is 150°C, 160°C, 170°C, 180°C, 190°C or 200°C. The heating reaction time is 2 days, 3 days, 4 days or 5 days.

[0081] In some embodiments, the step of cooling the reaction solution to room temperature is carried out under anhydrous and anaerobic conditions. Specifically, the step of cooling the reaction solution to room temperature can be carried out in a glove box.

[0082] In some embodiments, the concentration of NaOH in the NaOH aqueous solution is 1 mol / L.

[0083] Prepare the trivalent coordination phosphate single crystal of lanthanide nuclide:

[0084] Mix the trivalent chloride of lanthanide nuclide, methylenediphosphonic acid, deionized water and crystallization additive, and heat for reaction; cool the reaction solution to room temperature, wash it, and obtain crystals.

[0085] In some of these embodiments, the crystallization additive is selected from one of an aqueous NaOH solution and NaNO3.

[0086] In some of these embodiments, a muffle furnace is used for the heating reaction. Specifically, the temperature of the heating reaction is 150°C to 200°C. The time of the heating reaction is 2 days to 5 days. Optionally, the temperature of the heating reaction is 150°C, 160°C, 170°C, 180°C, 190°C or 200°C. The time of the heating reaction is 2 days, 3 days, 4 days or 5 days.

[0087] In some of these embodiments, the concentration of NaOH in the aqueous NaOH solution is 1 mol / L.

[0088] In some of these embodiments, a muffle furnace is used for the heating reaction. Specifically, the temperature of the heating reaction is 150°C to 200°C. The time of the heating reaction is 2 days to 5 days. Optionally, the temperature of the heating reaction is 150°C, 160°C, 170°C, 180°C, 190°C or 200°C. The time of the heating reaction is 2 days, 3 days, 4 days or 5 days.

[0089] Another embodiment of the present invention also provides a method for evaluating the solidification treatment of radioactive waste, including the following steps S210 to S230.

[0090] Step S210: Use the above-mentioned feasibility evaluation method for alternative nuclides in the solidification treatment of radioactive waste to obtain at least one alternative lanthanide nuclide corresponding to the actinide nuclide in the radioactive waste.

[0091] Step S220: Use the alternative lanthanide nuclide to replace the actinide nuclide in the radioactive waste to prepare a solidified body.

[0092] Step S230: Obtain the stability evaluation result of the solidified body.

[0093] Specifically, in step S230, obtaining the stability evaluation result of the solidified body includes: measuring the chemical stability, thermal stability, mechanical stability and anti-irradiation stability of the solidified body.

[0094] In the above-mentioned method for evaluating the solidification treatment of radioactive waste, selecting a suitable lanthanide nuclide as an alternative nuclide for the actinide element in the radioactive waste, preparing a solidified body and studying its stability is beneficial to preparing a radioactive waste solidified body with high stability.

[0095] In some of these embodiments, the solidified body is selected from one of glass and ceramic.

[0096] In some of these embodiments, the actinides in the radioactive waste are at least one of plutonium (Pu) and americium (Am); the alternative lanthanides are selected from at least one of neodymium (Nd) and samarium (Sm).

[0097] The following further illustrates the method for judging the feasibility of alternative nuclides of the present invention through specific examples.

[0098] Example 1:

[0099] In this example, trivalent coordination phosphate single crystals of actinides and lanthanides are prepared to simulate the coordination environment during vitrification, which specifically includes the following steps:

[0100] (1) Preparation of Pu trivalent coordination phosphate crystal: Place 5 mg of anhydrous PuCl3 in the inner lining of a polytetrafluoroethylene reaction kettle. Add 150 μL of deionized water, 3 mg of methylenediphosphonic acid, and 50 μL of 1 mol / L NaOH aqueous solution into the reaction kettle respectively. Then seal the inner lining of the reaction kettle in a high-pressure stainless steel reaction kettle sleeve and place it in a muffle furnace at 180 °C for heating for 3 days, and then cool it to room temperature in a glove box. The generated product is washed with cold water to remove the excess methylenediphosphonic acid, and purple-blue needle-like crystals are obtained.

[0101] (2) Preparation of Am trivalent coordination phosphate crystal: In a polytetrafluoroethylene reaction kettle, dissolve 5 mg of AmO2 in 200 μL of 5 mol / L HCl solution. After the reaction is complete, heat it to 120 °C until the solvent completely evaporates to obtain yellow anhydrous AmCl3. Then add 150 μL of deionized water, 3 mg of methylenediphosphonic acid, and 50 μL of 1 mol / L NaOH aqueous solution into the reaction kettle respectively. Then seal the inner lining of the reaction kettle in a high-pressure stainless steel reaction kettle sleeve and place it in a muffle furnace at 180 °C for heating for 4 days, and then cool it to room temperature in a glove box. The generated product is washed with cold water to remove the excess methylenediphosphonic acid, and yellow crystals are obtained.

[0102] (3.1) Preparation of La trivalent coordination phosphate crystal: Place 60 mg of anhydrous LaCl3, 30 mg of methylenediphosphonic acid, 1 mL of deionized water, and 800 μL of 1 mol / L NaOH aqueous solution in the inner lining of a polytetrafluoroethylene reaction kettle. Then seal the inner lining of the reaction kettle in a high-pressure stainless steel reaction kettle sleeve and place it in a muffle furnace at 180 °C for heating for 2 days, and then cool the reaction system to room temperature within one day. The generated product is first washed with boiling water to remove the excess methylenediphosphonic acid, and then washed with ethanol to obtain crystals.

[0103] (3.2) Preparation of Ce(III) coordinated phosphate crystals: 50 mg of anhydrous CeCl3, 30 mg of methylenediphosphonic acid, 1 mL of deionized water, and 800 μL of 1 mol / L NaOH aqueous solution were placed in the inner lining of a polytetrafluoroethylene reaction kettle. Subsequently, the inner lining of the reaction kettle was sealed in a high-pressure stainless steel reaction kettle jacket and placed in a muffle furnace for heating at 180 °C for 2 days, and then the reaction system was cooled to room temperature within one day. The resulting product was first washed with boiling water to remove the excess methylenediphosphonic acid, and then washed with ethanol to obtain the crystals.

[0104] (3.3) Preparation of Pr(III) coordinated phosphate crystals: 50 mg of anhydrous PrCl3, 30 mg of methylenediphosphonic acid, 2 mL of deionized water, and 100 mg of NaNO3 were placed in the inner lining of a polytetrafluoroethylene reaction kettle. Subsequently, the inner lining of the reaction kettle was sealed in a high-pressure stainless steel reaction kettle jacket and placed in a muffle furnace for heating at 180 °C for 3 days, and then the reaction system was cooled to room temperature within one day. The resulting product was first washed with boiling water to remove the excess methylenediphosphonic acid, and then washed with ethanol to obtain the crystals.

[0105] (3.4) Preparation of Nd(III) coordinated phosphate crystals: 50 mg of anhydrous NdCl3, 30 mg of methylenediphosphonic acid, 1.5 mL of deionized water, and 500 μL of 1 mol / L NaOH aqueous solution were placed in the inner lining of a polytetrafluoroethylene reaction kettle. Subsequently, the inner lining of the reaction kettle was sealed in a high-pressure stainless steel reaction kettle jacket and placed in a muffle furnace for heating at 180 °C for 2 days, and then the reaction system was cooled to room temperature within one day. The resulting product was first washed with boiling water to remove the excess methylenediphosphonic acid, and then washed with ethanol to obtain the crystals.

[0106] (3.5) Preparation of Sm(III) coordinated phosphate crystals: 30 mg of anhydrous SmCl3, 20 mg of methylenediphosphonic acid, 0.8 mL of deionized water, and 300 μL of 1 mol / L NaOH aqueous solution were placed in the inner lining of a polytetrafluoroethylene reaction kettle. Subsequently, the inner lining of the reaction kettle was sealed in a high-pressure stainless steel reaction kettle jacket and placed in a muffle furnace for heating at 180 °C for 2 days, and then the reaction system was cooled to room temperature within one day. The resulting product was first washed with boiling water to remove the excess methylenediphosphonic acid, and then washed with ethanol to obtain the crystals.

[0107] (3.6) Preparation of Eu(III) coordinated phosphate crystal: 50 mg of anhydrous EuCl3, 30 mg of methylenediphosphonic acid, 1.5 mL of deionized water and 500 μL of 1 mol / L NaOH aqueous solution were placed in the inner lining of a polytetrafluoroethylene reaction kettle. Subsequently, the inner lining of the reaction kettle was sealed in a high-pressure stainless steel reaction kettle jacket and placed in a muffle furnace for heating reaction at 180 °C for 2 days, and then the reaction system was cooled to room temperature within one day. The generated product was first washed with boiling water to remove the excess methylenediphosphonic acid, and then washed with ethanol to obtain the crystal.

[0108] (3.7) Preparation of Gd(III) coordinated phosphate crystal: 50 mg of anhydrous GdCl3, 30 mg of methylenediphosphonic acid, 2 mL of deionized water and 100 mg of NaNO3 were placed in the inner lining of a polytetrafluoroethylene reaction kettle. Subsequently, the inner lining of the reaction kettle was sealed in a high-pressure stainless steel reaction kettle jacket and placed in a muffle furnace for heating reaction at 180 °C for 5 days, and then the reaction system was cooled to room temperature within one day. The generated product was first washed with boiling water to remove the excess methylenediphosphonic acid, and then washed with ethanol to obtain the crystal.

[0109] (3.8) Preparation of Tb(III) coordinated phosphate crystal: 50 mg of anhydrous TbCl3, 30 mg of methylenediphosphonic acid, 2 mL of deionized water and 100 mg of NaNO3 were placed in the inner lining of a polytetrafluoroethylene reaction kettle. Subsequently, the inner lining of the reaction kettle was sealed in a high-pressure stainless steel reaction kettle jacket and placed in a muffle furnace for heating reaction at 180 °C for 5 days, and then the reaction system was cooled to room temperature within one day. The generated product was first washed with boiling water to remove the excess methylenediphosphonic acid, and then washed with ethanol to obtain the crystal.

[0110] (3.9) Preparation of Dy(III) coordinated phosphate crystal: 100 mg of anhydrous DyCl3, 30 mg of methylenediphosphonic acid, 2 mL of deionized water and 80 mg of NaNO3 were placed in the inner lining of a polytetrafluoroethylene reaction kettle. Subsequently, the inner lining of the reaction kettle was sealed in a high-pressure stainless steel reaction kettle jacket and placed in a muffle furnace for heating reaction at 180 °C for 5 days, and then the reaction system was cooled to room temperature within one day. The generated product was first washed with boiling water to remove the excess methylenediphosphonic acid, and then washed with ethanol to obtain the crystal.

[0111] (3.10) Preparation of Yb(III) coordinated phosphate crystal: 50 mg of anhydrous YbCl3, 30 mg of methylenediphosphonic acid, 2 mL of deionized water and 120 mg of NaNO3 were placed in the inner lining of a polytetrafluoroethylene reaction kettle. Subsequently, the inner lining of the reaction kettle was sealed in a high-pressure stainless steel reaction kettle jacket and placed in a muffle furnace for heating reaction at 180 °C for 5 days, and then the reaction system was cooled to room temperature within one day. The generated product was first washed with boiling water to remove the excess methylenediphosphonic acid, and then washed with ethanol to obtain the crystal.

[0112] (3.11) Preparation of Lu(III) coordinated phosphate crystals: Place 60 mg of anhydrous LuCl3, 30 mg of methylenediphosphonic acid, 2 mL of deionized water, and 80 mg of NaNO3 in the inner lining of a polytetrafluoroethylene reaction kettle. Subsequently, seal the inner lining of the reaction kettle in a high-pressure stainless steel reaction kettle sleeve and place it in a muffle furnace for heating at 180 °C for 5 days, and then cool the reaction system to room temperature within one day. The resulting product is first washed with boiling water to remove excess methylenediphosphonic acid, and then washed with ethanol to obtain crystals.

[0113] (4) Use an XRD diffractometer to measure the diffraction intensity data of the crystals prepared in steps (1) to (3) respectively.

[0114] (5) Use the SHELXTL program to analyze the diffraction intensity data in step (4) to obtain the crystal structures of the crystals prepared in steps (1) to (3).

[0115] (6) Compare the crystal structures analyzed in step (4) to obtain the comparison results.

[0116] Refer to Figures 1 to 3 , which are the schematic diagrams of the crystal structures of the crystals prepared in steps (1) to (3) respectively. Figure 1 is the schematic diagram of the crystal structure of R[CH2(PO3H 0.5 )2] (R = La - Sm; Pu). Figure 2 is the schematic diagram of the crystal structure of NaRE[CH2(PO3)2] (RE = La - Dy; Am). Figure 3 is the schematic diagram of the crystal structure of NaQ[CH2(PO3H 0.5 )2]·(H2O) (Q = Yb, Lu).

[0117] Figure 1 In the crystal structure of R[CH2(PO3H 0.5 )2] (R = La - Sm; Pu) shown, the metal centers are connected into chains by bonding with edge-sharing oxygen to form a polyhedral coordination structure, and further connected by methylenediphosphonic acid ligands to form a three-dimensional framework structure. Among them, the two PO3 groups in the methylenediphosphonic acid ligand are respectively connected to two metal centers, and the O1 in the PO3 group bridges with the metal center; O2 is μ3-O, which is connected to two adjacent metal centers respectively, connecting the coordination polyhedra into chains; O3 is further connected to another metal center to form a structure similar to a layer. The layer structures are connected by the -CH2- unit in the methylenediphosphonic acid ligand to form a three-dimensional framework structure.

[0118] Figure 2The crystal structure of NaRE[CH2(PO3)2] (RE = La - Dy; Am) shown is also a three - dimensional framework structure. The basic unit of this kind of structure is a metal dimer. These dimers are connected by methylene diphosphate ligands and expand in all three directions to form a three - dimensional framework. Among them, the PO3 unit in the methylene diphosphate ligand chelates one metal center through two oxygen atoms and bridges the second metal center through a μ3 - O. The third oxygen atom of this PO3 unit binds to the adjacent metal center of the dimer. The other PO3 unit does not chelate the metal center but connects three metal centers from different dimers. There are Na + ions in this structural framework to maintain charge balance. Therefore, all oxygen atoms in the methylene diphosphate ligand are completely deprotonated.

[0119] Figure 3 The crystal structure of NaQ[CH2(PO3H 0.5 )2]·(H2O) (Q = Yb, Lu) shown is another kind of three - dimensional framework structure, where the metal polyhedron is an isolated monomer. Different from the Figure 1 、 Figure 2 crystal structure with an eight - coordinated metal center, the metal centers in this structure are all six - coordinated. All six oxygen atoms come from the methylene diphosphate ligand. Two of them come from two PO3 units of the same methylene diphosphate ligand unit, which chelate the metal center in this way. The other four all come from adjacent methylene diphosphate ligand units, which bind to the metal center and expand the structure into a three - dimensional framework. The cavity size in this structure type is larger than that of the Figure 2 crystal structure. There are Na + cations and disordered water molecules in the cavity.

[0120] From the Figures 1 to 3 crystal structure, it can be seen that the lanthanide elements from La to Dy have a phosphate crystal structure close to that of Pu and Am. Specifically, the crystal forms of the phosphates of the lanthanide elements from La to Dy are the same as those of Pu and Am. Therefore, it is judged that La - Dy can be selected as alternative nuclides for actinide elements. However, from the crystal structures of Yb and Lu, it can be seen that they have a coordination structure different from that of Pu and Am. Therefore, they are not suitable as alternative nuclides for Pu and Am. Further, according to the trivalent ion radii of La - Dy, the trivalent lanthanide ions Sm 3+ 、Nd 3+ are selected as alternative nuclides for the trivalent actinide ions Pu 3+ 、Am 3+ .

[0121] The technical features of the above-described embodiments may be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as falling within the scope described in this specification.

[0122] The above-described embodiments merely represent several implementation manners of the present invention and are convenient for understanding the technical solutions of the present invention specifically and in detail. However, it should not be construed as a limitation on the protection scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention. It should be understood that the technical solutions obtained by those skilled in the art based on the technical solutions provided by the present invention through logical analysis, reasoning or limited experiments are all within the protection scope of the appended claims of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the content of the appended claims, and the specification and the drawings can be used to interpret the content of the claims.

Claims

1. A feasibility assessment method for alternative nuclides in the solidification treatment of radioactive waste, characterized in that, It includes the following steps: Obtain at least one actinide nuclide in the solidification treatment of the radioactive waste, where the actinide nuclide is at least one of plutonium and americium; Prepare a single crystal of trivalent coordination salt of the actinide nuclide in the simulated coordination environment of the solidification treatment of the radioactive waste; Prepare a single crystal of trivalent coordination salt of the lanthanide nuclide in the same simulated coordination environment, where the lanthanide nuclide is selected from at least one of lanthanum La, cerium Ce, praseodymium Pr, neodymium Nd, samarium Sm, europium Eu, gadolinium Gd, terbium Tb, and dysprosium Dy; The ligand sources of the single crystal of trivalent coordination salt of the actinide nuclide and the single crystal of trivalent coordination salt of the lanthanide nuclide are both methylene diphosphonic acid; Compare the crystal structures of the single crystal of trivalent coordination salt of the actinide nuclide and the single crystal of trivalent coordination salt of the lanthanide nuclide to obtain a comparison result; Obtain the evaluation result of the feasibility assessment according to the comparison result.

2. The feasibility evaluation method for substituting nuclides in the solidification treatment of radioactive waste according to claim 1, wherein The raw materials for preparing the single crystal of trivalent coordination salt of the actinide nuclide further include an actinide nuclide source, where the actinide nuclide source is selected from soluble trivalent salts of actinide nuclides, and the reaction temperature between the actinide nuclide source and the ligand source is 150°C to 200°C; And / or, the raw materials for preparing the single crystal of trivalent coordination salt of the lanthanide nuclide further include a lanthanide nuclide source, where the lanthanide nuclide source is selected from soluble trivalent salts of lanthanide nuclides, and the reaction temperature between the lanthanide nuclide source and the ligand source is 150°C to 200°C.

3. The feasibility evaluation method for substituting nuclides in the solidification treatment of radioactive waste according to claim 1, wherein The single crystal of trivalent coordination salt of the actinide nuclide is prepared by hydrothermal reaction of methylene diphosphonic acid with trivalent chloride of the actinide nuclide at 150°C to 200°C; the single crystal of trivalent coordination salt of the lanthanide nuclide is prepared by hydrothermal reaction of methylene diphosphonic acid with trivalent chloride of the lanthanide nuclide at 150°C to 200°C.

4. The feasibility evaluation method for substituting radionuclides in the solidification treatment of radioactive waste according to claim 1, wherein In the step of comparing the crystal structures of the single crystal of trivalent coordination salt of the actinide nuclide and the single crystal of trivalent coordination salt of the lanthanide nuclide, it includes: Compare whether the crystal forms of the single crystal of trivalent coordination salt of the lanthanide nuclide and the single crystal of trivalent coordination salt of the actinide nuclide are the same; In the step of obtaining the evaluation result of the feasibility assessment according to the comparison result, it includes: If the crystal forms of the single crystal of trivalent coordination salt of the lanthanide nuclide and the single crystal of trivalent coordination salt of the actinide nuclide are the same, then the lanthanide nuclide can be used as an alternative nuclide in the solidification treatment of the radioactive waste; If the crystal forms of the single crystal of trivalent coordination salt of the lanthanide nuclide and the single crystal of trivalent coordination salt of the actinide nuclide are different, then the lanthanide nuclide is not selected as an alternative nuclide in the solidification treatment of the radioactive waste.

5. The feasibility evaluation method for substituting nuclides in the solidification treatment of radioactive waste according to claim 4, wherein In the step of comparing the crystal structures of the single crystal of trivalent coordination salt of the actinide nuclide and the single crystal of trivalent coordination salt of the lanthanide nuclide, it further includes: comparing the ionic radius sizes of the trivalent ions of the lanthanide nuclide and the trivalent ions of the actinide nuclide; In the step of obtaining the evaluation result of the feasibility assessment according to the comparison result, it further includes: If the crystal forms of the single crystal of trivalent coordination salt of the lanthanide nuclide and the single crystal of trivalent coordination salt of the actinide nuclide are the same, and the ionic radius of the trivalent ion of the lanthanide nuclide is the closest to that of the trivalent ion of the actinide nuclide, then the lanthanide nuclide is selected as an alternative nuclide in the solidification treatment of the radioactive waste.

6. An evaluation method for solidification treatment of radioactive waste, characterized in that, It includes the following steps: Using the feasibility evaluation method for alternative nuclides in the solidification treatment of radioactive waste according to any one of claims 1 to 5, at least one alternative lanthanide nuclide corresponding to the actinide nuclide in the radioactive waste is obtained; Using the alternative lanthanide nuclide to replace the actinide nuclide in the radioactive waste to prepare a solidified body; Obtaining the stability evaluation result of the solidified body.

7. The radioactive waste solidification treatment evaluation method according to claim 6, wherein The alternative lanthanide nuclide is selected from at least one of neodymium and samarium.

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