Method for salt inclusion crystal screening and property characterization and application thereof

Abstract

The invention discloses a method for salt inclusion crystal screening and property characterization and application thereof, and belongs to the field of spent fuel aftertreatment. The method comprises the following steps: (1) recombining host skeleton salt inclusion substances with different configurations, host skeletons, guest salts and cations between the skeletons to form a new salt inclusion substance crystal structure; (2) carrying out structure optimization on the material; (3) static self-consistent calculation is carried out on all the optimized new salt inclusion crystal structures, the lowest system energy of each new salt inclusion crystal structure is found, the formation energy of the salt inclusion is calculated, and the new salt inclusion crystal structure with the lowest formation energy in different configurations is the most stable new salt inclusion crystal structure; and (4) performing non-self-consistent calculation according to the screening structure to obtain the electronic structure property of the salt inclusion. By means of the method, the salt inclusion can be screened, the radionuclide combining capacity of the salt inclusion can be predicted through thermodynamic calculation, the development period of the salt inclusion material used for solidifying cesium is shortened, and the research and development efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of spent fuel reprocessing, and particularly relates to a method for screening and characterizing salt-inclusion crystals and application thereof. BACKGROUND

[0002] Salt-inclusion is a new type of solidified material that can be customized at the molecular or lattice level, which is composed of a host framework and a guest salt, and has the ability to stably fix specific radionuclides in the matrix. Meanwhile, the molten salt method is the most likely method to realize the synthesis of new crystals, and the main component of the radioactive waste salt produced by molten salt electrolysis refining is LiCl-KCl eutectic salt, which is one of the typical cosolvent systems in the synthesis of crystals by the molten salt method. Therefore, by taking advantage of the characteristics of salt-inclusion in fixing radionuclides, the radioactive cesium present in the waste salt after electrolytic refining can be treated.

[0003] After the spent fuel is cut into pieces and added to the molten salt electrolysis cell, a non-radioactive fluxing agent is added to the molten salt electrolysis cell to supplement the molten salt medium, and by taking advantage of the difference in formation energy, the radioactive Cs + is replaced by non-radioactive guest salt cations such as Na + , K + , Rb + . By crystallization, radioactive cesium is fixed in salt-inclusion, and finally the salt-inclusion precipitate is separated to remove radioactive cesium. The advantage of this method is that it does not bring impurities into the molten salt system, and when used together with ordinary precipitation methods, it can have a better effect on purifying waste salt. Because after removing lanthanide elements produced during electrolytic refining by using ordinary precipitation methods such as phosphate precipitation, carbonate precipitation and oxide precipitation, the alkali metals in the molten salt have not been properly disposed of, and the residual radioactive cesium will have a great impact on the molten salt system. This method can complement the precipitation method to achieve the purpose of purifying waste salt.

[0004] Many salt-inclusions reported so far are accidentally grown in the process of exploring the synthesis of ordinary oxides. Expanding their types can synthesize salt-inclusion crystals that have good fixing ability for target nuclides, and this process of finding may require a large number of experiments, consume more resources, and have certain blindness. SUMMARY

[0005] The purpose of the present application is to provide a method for screening and characterizing salt-inclusion crystals, which optimizes the crystal structure by first-principle calculation, screens salt-inclusions that are easier to synthesize, and preliminarily obtains salt-inclusions with stable configurations and calculates their electronic structure properties.

[0006] The present application provides a method for screening and characterizing salt-inclusion crystals, comprising:

[0007] Step 1: Obtain salt inclusions of the same or different main body skeleton of different configurations, combine the most numerous cations and anions existing in the salt ion group of the salt inclusion with the main body skeleton to form new salt inclusion crystal structures;

[0008] Step 2: Structure optimization is performed on all new salt inclusion crystal structures until convergence;

[0009] Step 3: Static self-consistent calculation is performed on all new salt inclusion crystal structures after structure optimization to find the system lowest energy of each new salt inclusion crystal structure, obtain wave function information and electron density information; the formation energy of each new salt inclusion crystal structure is calculated according to the system lowest energy, and the most stable new salt inclusion crystal structure in different configurations is screened according to the formation energy;

[0010] Step 4: According to the screened structure, add parameters of non-self-consistent calculation, change KPOINTS or select wave function and charge density as initial values for non-self-consistent calculation, obtain the electronic structure properties of the salt inclusion, and judge the action mode of different elements orbitals in the salt inclusion main body skeleton and guest salt.

[0011] Further, the main body skeleton salt inclusion includes one or more of a silicon-based skeleton, a germanium-based skeleton, and a gallium-based skeleton.

[0012] Further, the most numerous cation Na + , K + , Rb + , Cs + exists in the salt ion group of the salt inclusion; the most numerous anion F - , Cl - exists in the salt ion group of the salt inclusion; and the cation Na + , K + , Rb + , Cs + exists between the skeletons.

[0013] Further, in step 2, the structure optimization of the new salt inclusion crystal structure is specifically: for the exploration of electron-ion interaction, the projection augmented wave method is used, the PBE functional is used as the exchange-correlation function to process the exchange correlation between electrons, the plane wave cutoff energy is 520 eV, and the convergence thresholds of system energy and force are 10 -5 eV and 10 -4 The structure optimization is performed by VASP software.

[0014] Further, in step 3, the formation energy of the salt inclusion is:

[0015]

[0016] wherein H f ∈1∈2...∈n H is the enthalpy of the salt inclusion; H ∈i H is the enthalpy of each component element in the salt inclusion; x i n is the number of elements.

[0017] Further, in step 3, the screening condition is that the new salt inclusion crystal structure containing cesium in different configurations has the minimum formation energy as the target salt inclusion material.

[0018] Further, in step 4, the electronic structure properties of the salt inclusion include energy band, energy band gap value, state density, partial wave state density, electron localization function, and Bader charge.

[0019] The application also provides a method for screening and characterizing salt inclusion crystals, which is applied to the treatment of radioactive cesium in spent fuel. First, the most stable salt inclusion crystal structure containing cesium in different configurations and the electronic structure properties of the salt inclusion containing cesium are obtained. Then, after the spent fuel containing radioactive cesium is cut into pieces and added to a molten salt electrolysis cell, a non-radioactive fluxing agent is added to the molten salt electrolysis cell to supplement the molten salt medium. By using the difference in formation energy, the radioactive Cs + is replaced by the non-radioactive guest salt cation; finally, the radioactive cesium is fixed in the salt inclusion by crystallization, and the salt inclusion precipitate is separated to remove the radioactive cesium. The molten salt electrolysis cell includes a salt inclusion capable of forming a stable crystal structure with Cs + .

[0020] Further, it specifically includes:

[0021] Step 1: Obtain salt inclusions with the same or different host frameworks in different configurations. The most common anion in the salt ion group of the salt inclusion and the most common cation or the cation existing between the frameworks in the salt ion group of the salt inclusion are combined with the host framework to form new salt inclusion crystal structures. +

[0022] Step 2: Perform structural optimization on all new salt inclusion crystal structures containing cesium until convergence.

[0023] Step 3: Perform static self-consistent calculation on all new salt inclusion crystal structures containing cesium after structural optimization to find the system lowest energy of each new salt inclusion crystal structure containing cesium and obtain wave function information and electron density information. Calculate the formation energy of the salt inclusion containing cesium according to the system lowest energy of each new salt inclusion crystal structure containing cesium, and select the most stable new salt inclusion crystal structure containing cesium in different configurations according to the formation energy.

[0024] ​Step 4: According to the screening structure, add the parameters of non-self-consistent calculation, change KPOINTS or select the wave function and charge density as the initial value for non-self-consistent calculation, and obtain the electronic structure properties of the salt-inclusion.

[0025] The beneficial effects of the present application are:

[0026] (1) The present application uses first-principle calculation to calculate the thermodynamic properties of salt-inclusion to judge the stability of salt-inclusion, and screens stable and easy-to-synthesize salt-inclusion.

[0027] (2) The present application calculates the electronic structure properties of the material, and through analyzing the changes of the electronic structure such as band structure, electronic state density, and charge distribution, the various physical and chemical properties of the material under different conditions can be explained.

[0028] (3) The present application can screen salt-inclusion and predict its ability to bind radionuclide through thermodynamic calculation, and select salt-inclusion with specific performance, which helps to deeply understand the internal relationship between the microstructure and macro performance of the material; applying the method to the screening and characterization of salt-inclusion for solidifying cesium can shorten the development cycle of salt-inclusion material for solidifying cesium, find stable salt-inclusion for solidifying cesium, use the stability of different crystal structures to quickly fix radioactive cesium in salt-inclusion, and finally separate the salt-inclusion precipitate to remove radioactive cesium, thereby improving the research and development efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a flowchart of the method for screening and characterizing salt-inclusion crystals of the present application;

[0030] Figure 2 is a schematic diagram of the crystal structure of the salt-inclusion [A6Ag2B2][(UO2)3(Ge2O7)2] and the change of the channel structure in the embodiment of the present application;

[0031] Figure 3 is a schematic diagram of the crystal structure of the salt-inclusion [CA6B][(UO2)3(Ge2O7)2] and the change of the channel structure in the embodiment of the present application;

[0032] Figure 4 is a schematic diagram of the crystal structure of the salt-inclusion [A2A'6Cl2][(UO2)3(Ge2O7)2] and the change of the channel structure in the embodiment of the present application;

[0033] Figure 5 is a comparison chart of the formation energies of three different germanium-based salt-inclusions in the embodiment of the present application;

[0034] Figure 6 is a comparison chart of the formation energies of different alkali cations of the guest salt of the germanium-based salt-inclusion in the embodiment of the present application;

[0035] Figure 7 is a comparison chart of different halogen anion formation energies of three different germanium-based clathrate guest salt in embodiments of the present application;

[0036] Figure 8 is a comparison chart of different halogen anion formation energies of three different germanium-based clathrate guest salt in embodiments of the present application; + is a comparison chart of different halogen anion formation energies of three different germanium-based clathrate guest salt in embodiments of the present application;

[0037] Figure 9 is a comparison chart of different halogen anion formation energies of three different germanium-based clathrate guest salt in embodiments of the present application;

[0038] Figure 10 is a comparison chart of different halogen anion formation energies of three different germanium-based clathrate guest salt in embodiments of the present application;

[0039] Figure 11 is a comparison chart of different halogen anion formation energies of three different germanium-based clathrate guest salt in embodiments of the present application;

[0040] Figure 12 is a comparison chart of different halogen anion formation energies of three different germanium-based clathrate guest salt in embodiments of the present application;

[0041] Figure 13 is a comparison chart of different halogen anion formation energies of three different germanium-based clathrate guest salt in embodiments of the present application;

[0042] Figure 14 is a comparison chart of different halogen anion formation energies of three different germanium-based clathrate guest salt in embodiments of the present application;

[0043] Figure 15is the three-dimensional electron localization function density plot of [CA6F][(UO2)3(Ge2O7)2] (A = Na, K, Rb, Cs) in the embodiment of the present application, and the crystal structure plot after the crystal structure is optimized;

[0044] Figure 16 is the two-dimensional section plot of the electron localization function of [CA6F][(UO2)3(Ge2O7)2] (A = Na, K, Rb, Cs) in the embodiment of the present application;

[0045] Figure 17 is the three-dimensional electron localization function density plot of [A2A'6F2][(UO2)3(Ge2O7)2] (A = A' = Na, K, Rb, Cs) in the embodiment of the present application, and the crystal structure plot after the crystal structure is optimized;

[0046] Figure 18 is the two-dimensional section plot of the electron localization function of [A2A'6F2][(UO2)3(Ge2O7)2] (A = A' = Na, K, Rb, Cs) in the embodiment of the present application;

[0047] Figure 19 is the Bader charge (e) analysis plot of [A6Ag2F2][(UO2)3(Ge2O7)2] in the embodiment of the present application;

[0048] Figure 20 is the Bader charge (e) analysis plot of [CA6F][(UO2)3(Ge2O7)2] in the embodiment of the present application;

[0049] Figure 21 is the Bader charge (e) analysis plot of [A2A'6F2][(UO2)3(Ge2O7)2] in the embodiment of the present application. DETAILED DESCRIPTION

[0050] The present application will be further described below in conjunction with the accompanying drawings and embodiments.

[0051] It should be noted that the following detailed description is illustrative only, and is intended to provide further description in order to provide a further understanding of the exemplary embodiments according to the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0052] It is also important to note that the terms used herein are not intended to limit the particular embodiments according to the present application to the preferred embodiments described. Rather, at least some embodiments according to the present application can be practiced with the exact structure as shown and described. In addition, unless otherwise specified, "a" or "an" shall mean "one or more", and the use of "or" shall include "and / or", particularly cleary in reference to the use of "or" in reference to claims. Furthermore, to the extent that the terms "includes", "including", "has", "have", "has", "including", "includes" and / or "containing", or variants thereof are used in either the detailed description and / or the claims, such terms are intended to be inclusive in a manner similar to the term "comprising" as an open transition such that no properties, elements or limitations are required, unless otherwise expressly stated.

[0053] The technical means, creative features, purposes and effects of the present application are easy to understand, and the present application is further described below in conjunction with specific embodiments.

[0054] The application discloses a method for salt-inclusion crystal screening and property characterization, based on first-principle calculation, comprising the following steps:

[0055] Step S1: Use the MaterialsProject crystal database to obtain different configurations of the same or different host skeletons of salt-inclusions that have been synthesized in the experiment, take the obtained salt-inclusions as the original structure, and convert the structure data file obtained from the database into the input file of VASP through VESTA software; the salt-inclusion host skeleton is selected from one or more of a silicon-based skeleton, a germanium-based skeleton and a gallium-based skeleton.

[0056] Step S2: according to the most common cation Na + , K + , Rb + , Cs + in the salt ion group of the salt-inclusion, the most common anion F - , Cl - in the salt ion group of the salt-inclusion, and the cation Na + , K + , Rb + , Cs + existing between the skeletons, the cation and the host skeleton are combined to form a new salt-inclusion crystal structure, and the input file of the initial structure VASP is modified to obtain the input file of the new salt-inclusion VASP;

[0057] Step S3: use the VASP software to perform structure optimization calculation on all salt-inclusion crystal structures until convergence, obtain the output file CONTCAR, read the output file to obtain the crystal structure data of the salt-inclusion after structure optimization, including the unit cell parameters, bond length and bond angle;

[0058] Step S4: on the basis of structure optimization, read the output file CONTCAR of structure optimization and modify the input file INCAR of structure optimization, perform static self-consistent calculation on all salt-inclusion crystal structures, adjust the electrons of the system, find the lowest energy of the system and obtain the wave function information and electron density information of the system, obtain the output file OUTCAR, read the output file to obtain the energy of the salt-inclusion, calculate the formation energy of the system according to the energy of the system, and screen out the salt-inclusion materials that are relatively stable in theory;

[0059] Step S5: According to the screening results, read the output file CONTCAR after structure optimization, change the input file INCAR, add the parameters of non-self-consistent calculation, change KPOINTS or select wave function and charge density as initial value for non-self-consistent calculation, and obtain the electronic structure properties of the salt inclusion.

[0060] In the above step S3, the structure optimization calculation is based on the VASP simulation software package of the plane wave method density functional theory; wherein, in the process of calculation, for the exploration of the interaction between electrons and ions, the projected augmented wave (PAW) method is used, the PBE functional is used as the exchange-correlation function to process the exchange correlation between electrons, the plane wave cutoff energy is set to 520 eV, and the energy and force convergence thresholds are 10 -5 eV and 10 -4

[0061] In the above step S3, the structure of the salt inclusion is visualized by VESTA software, the output file CONTCAR after structure optimization is read, and the structure parameters are obtained.

[0062] In the above step S4, the calculation formula of the salt inclusion formation energy is:

[0063]

[0064] Wherein, H f ∈1∈2...∈n is the enthalpy value of the salt inclusion; H ∈i is the enthalpy value of each component element in the salt inclusion; x i is the stoichiometric number of the element; n is the number of elements.

[0065] In the above step S5, the electronic structure of the salt inclusion is calculated, including energy band, energy band gap value, state density, partial wave state density, electronic local function, Bader charge, etc., to judge the action mode of different element orbits in the main skeleton of the salt inclusion and the guest salt.

[0066] Example 1

[0067] A method for screening and characterizing salt inclusion crystals, comprising:

[0068] Step 1: Obtain three different configurations of germanium-based salt inclusions as original structures from the crystal database, including [Cs6Ag2Cl2][(UO2)3(Ge2O7)2] (P21 / n), [KK6Cl][(UO2)3(Ge2O7)2] (Pnnm) and [NaK6Cl][(UO2)3(Ge2O7)2] (Pnnm), [Na2Cs6Cl2][(UO2)3(Ge2O7)2] (P21 / c), export in CIF format, and then convert the CIF format file to.vasp file using VESTA software.

[0069] Step 2: According to the most common cations Na + , K + , Rb + , Cs + in the salt inclusion salt ion group, the most common anions F - , Cl - in the salt inclusion salt ion group, and the cations Na + , K + , Rb + , Cs + between the frameworks are combined with the germanium-based framework to form new salt inclusion crystal structures. By replacing the guest salt alkali metal ions, halogen ions and single alkali metal ions between the layers of the above initial salt inclusions, a total of 72 germanium-based salt inclusion crystal structures are obtained, as shown in Table 1. Modify the input file of VASP to obtain the input file of the new salt inclusion VASP. Rb + and F - come from non-radioactive cosolvents containing Rb + and F - .

[0070] Table 1: Germanium-based salt inclusion crystal structures

[0071]

[0072] Step 3: Use VASP software to perform structure optimization calculation on all salt inclusion crystal structures. For the exploration of electron-ion interaction, use the projected augmented wave (PAW) method, use the PBE functional as the exchange-correlation function to handle the exchange-correlation interaction between electrons, and set the plane wave cutoff energy to 520 eV. The energy and force convergence thresholds are 10 -5 eV and 10 -4

[0073] Read the output file to obtain the crystal structure data of the salt inclusion after structure optimization, and analyze Cs +The influence of the three types of salt inclusion channel structures after entering the salt inclusion channel by ion exchange.

[0074] Judging the salt inclusion guest salt cation Na + , K + , Rb + is replaced by Cs + , the salt inclusion channel of three different types changes, finds the rule, and the results are shown in Figures 2-4 .

[0075] Step 4: On the basis of structure optimization, static self-consistent calculation is carried out to find the lowest energy of the system and obtain the wave function information and electron density information of the system. According to the energy of the system, the formation energy of the system is calculated, and the salt inclusion material which is relatively stable in theory is screened out. According to the wave function information and electron density information of the system, the salt inclusion chemical bond type and electron cloud distribution are obtained.

[0076] The calculation formula of the salt inclusion formation energy is as follows:

[0077]

[0078] Among them, H f ∈1∈2...∈n is the enthalpy value of the salt inclusion; H ∈i is the enthalpy value of each component element in the salt inclusion; x i is the stoichiometric number of the element.

[0079] The screening is carried out under the condition of the lowest formation energy, and the screening results are shown in Figures 5-8 .

[0080] Step 5: According to the screening results, read the output file CONTCAR after structure optimization, change the input file INCAR, add the non-self-consistent calculation parameters, change KPOINTS or select the wave function and charge density as the initial value for non-self-consistent calculation, and obtain the electronic structure properties of the cesium-containing salt inclusion.

[0081] When calculating the energy band, a high-point path file needs to be provided. On the basis of static self-consistency, the parameters for energy band calculation are added in the INCAR file. The energy band image is shown in Figure 9 .

[0082] When calculating the state density, on the basis of static self-consistency, the parameters for state density calculation are added in the INCAR file. Read the electronic wave function WAVECAR and CHGCAR for calculation. After the calculation is completed, the output file is processed, the vaspkit software is called, and the 111, 113 and 115 commands in the 11 Density-of-States command are selected to obtain the total state density and partial wave state density respectively. The state density image is shown in Figures 10-12 .

[0083] When calculating the electron localization function, the parameters for calculating the electron localization function are added in the INCAR file on the basis of static self-consistency, the output file ELFCAR is read by VESTA, the value of the appropriate isosurface is set, the three-dimensional density map of the salt-inclusion electron localization function is obtained, and the two-dimensional section of the salt-inclusion electron localization function is obtained by sectioning, and the results are shown in Figures 13-18 .

[0084] When calculating the Bader charge, the VASP program is used to reconstruct three different total electron densities, core density, atomic valence density (overlapping atomic charge density, self-consistent valence density, and write them into AECCAR0, AECCAR1 and AECCAR2 files. Processing these three charge files can calculate the amount of charge accumulated and consumed by each atom. The results are shown in Figures 19-21 .

[0085] The energy band structure, electron state density, electron localization function and Bader charge of the salt-inclusion are combined to understand the mechanism of the salt-inclusion fixing the radionuclide cesium, and the existence form of the chemical bond between the host framework and the guest salt in the salt-inclusion and the interaction between the host framework and the guest salt are analyzed.

[0086] In summary, from specific cases, 72 germanium-based salt-inclusion crystals of three configurations were calculated. After the guest salt cations Na + , K + , Rb + of the salt-inclusion were replaced by Cs + , the changes in the channel shape of the salt-inclusions of the three configurations were similar, but also different. Screening the salt-inclusions, it was found that in the three salt-inclusions [A6Ag2B2][(UO2)3(Ge2O7)2], [CA6B][(UO2)3(Ge2O7)2], [A2A'6B2][(UO2)3(Ge2O7)2] (A=A';C=Na, K, Rb, Cs; B=F, Cl) of different configurations, the thermodynamically stable salt-inclusion in each configuration was [Cs6Ag2F2][(UO2)3(Ge2O7)2], [NaCs6F][(UO2)3(Ge2O7)2], [Cs2Cs'6F2][(UO2)3(Ge2O7)2]. The energy band structure, electron state density, electron localization function and Bader charge of the three germanium salt-inclusions for fixing Cs showed that the covalent oxide framework wrapped the guest salt combined by ionic bonds through electrostatic interaction; the Bader charge calculation showed that the charge transfer between atoms in the three salt-inclusions for fixing Cs was different.

[0087] The above merely describes preferred embodiments of the present application, but the disclosure is not limited to the specific details of the technical solutions described above, and various simple modifications and equivalent transformations of the technical solutions of the disclosure can be made within the technical concept of the disclosure, and these simple modifications and equivalent transformations all belong to the protection scope of the disclosure.

Claims

1. A method for salt inclusion crystal screening and property characterization, characterized by, The application relates to a method for screening a salt-inclusion crystal structure of a host framework, comprising the following steps: step 1: obtaining a salt-inclusion crystal structure of the same or different host framework in different configurations, combining the most numerous anions and cations existing in the salt-inclusion salt ion group with the host framework to form a new salt-inclusion crystal structure; step 2: performing structural optimization on all the new salt-inclusion crystal structures until convergence; step 3: performing static self-consistent calculation on all the new salt-inclusion crystal structures after structural optimization, finding the system lowest energy of each new salt-inclusion crystal structure, obtaining wave function information and electron density information, calculating the formation energy of each new salt-inclusion crystal structure according to the system lowest energy, and screening the most stable new salt-inclusion crystal structure in different configurations according to the formation energy; and step 4: adding the parameters of non-self-consistent calculation, changing KPOINTS or selecting the wave function and charge density as initial values to perform non-self-consistent calculation, obtaining the electronic structure properties of the salt-inclusion, and judging the action mode of different element orbits in the host framework salt-inclusion and the guest salt. The host framework salt-inclusion comprises one or more of a silicon-based framework, a germanium-based framework and a gallium-based framework. In step 3, the formation energy of the salt-inclusion is as follows: In step 3, the screening condition is that the formation energy of the new salt-inclusion crystal structure containing cesium in different configurations is the smallest. In step 4, the electronic structure properties of the salt-inclusion include energy band, energy band gap value, state density, partial wave state density, electron localization function and Bader charge.

2. The method for salt inclusion crystal screening and property characterization according to claim 1, characterized in that, Specifically, the application further relates to a method for screening a cesium-containing salt-inclusion crystal structure of a host framework, comprising the following steps: step 1: obtaining a cesium-containing salt-inclusion crystal structure of the same or different host framework in different configurations, combining the most numerous anions and cations existing in the salt-inclusion salt ion group with the host framework to form a new cesium-containing salt-inclusion crystal structure; step 2: performing structural optimization on all the new cesium-containing salt-inclusion crystal structures until convergence; step 3: performing static self-consistent calculation on all the new cesium-containing salt-inclusion crystal structures after structural optimization, finding the system lowest energy of each new cesium-containing salt-inclusion crystal structure, obtaining wave function information and electron density information, calculating the formation energy of the cesium-containing salt-inclusion according to the system lowest energy, and screening the most stable new cesium-containing salt-inclusion crystal structure in different configurations according to the formation energy; and step 4: adding the parameters of non-self-consistent calculation, changing KPOINTS or selecting the wave function and charge density as initial values to perform non-self-consistent calculation, obtaining the electronic structure properties of the cesium-containing salt-inclusion.

3. The method for salt inclusion crystal screening and property characterization according to claim 1, characterized in that, Na + , K + , Rb + , Cs + ; the most numerous anions in the salt-occluding salt ion group F - , Cl - ; the most numerous cations between the frameworks Na + , K + , Rb + , Cs + .

4. The method for salt inclusion crystal screening and property characterization according to claim 1, wherein, In step 2, the structure optimization of the new salt clathrate structure is as follows: for the exploration of the electronic-ion interaction, the projected augmented wave method is used, the PBE functional is used as the exchange-correlation function to deal with the exchange correlation between electrons, the plane wave cutoff energy is 520 eV, and the convergence thresholds of the system energy and force are 10 -5 eV and The structure optimization of the structure is calculated by using the VASP software.

5. The method for salt inclusion crystal screening and property characterization according to claim 1, wherein, In step 3, the formation energy of the salt-inclusion is as follows: where H f ∈1∈2...∈n is the enthalpy of the salt package; H ∈i is the enthalpy of each component element in the salt package; x i is the stoichiometric number of the element; n is the number of elements.

6. The method for salt inclusion crystal screening and property characterization according to claim 1, wherein, In step 3, the screening condition is that the formation energy of the new salt-inclusion crystal structure containing cesium in different configurations is the smallest.

7. The method for salt inclusion crystal screening and property characterization according to claim 1, wherein, In step 4, the electronic structure properties of the salt-inclusion include energy band, energy band gap value, state density, partial wave state density, electron localization function and Bader charge.

8. Use of a method according to any one of claims 1 to 7 for the screening and property characterization of salt clathrate crystals, characterized in that, Application in the treatment of radioactive cesium in spent fuel; first obtain the most stable crystal structure of the cesium-containing salt clathrate in different configurations and the electronic structure properties of the cesium-containing salt clathrate; then after adding the spent fuel containing radioactive cesium into the molten salt electrolytic cell, non-radioactive fluxing agent is added into the molten salt electrolytic cell to supplement the molten salt medium, and radioactive Cs + is replaced by non-radioactive guest salt cations; finally, radioactive cesium is fixed in the salt clathrate by crystallization, and the salt clathrate precipitate is separated to remove radioactive cesium; the molten salt electrolytic cell comprises a salt clathrate capable of forming a stable crystal structure with Cs + .

9. The use according to claim 8 for the method of salt inclusion crystal screening and its property characterization, characterized in that, ​ Step 1: Obtain the salt inclusion of the same or different host skeleton of different configurations, and combine the most numerous anions existing in the salt inclusion salt ion group with the host skeleton to form a new salt inclusion crystal structure. + The most numerous cations existing in the alternative salt inclusion salt ion group or the cations existing between the skeletons are combined with the host skeleton to form a new salt inclusion crystal structure. ​ ​ ​

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