A method for preparing a radioactive strontium cesium glass ceramic solidification body

Abstract

The application relates to a preparation method of a radioactive strontium cesium glass ceramic solidification body, which comprises the following steps: 1) uniformly mixing cesium garnet, granite, radioactive strontium and radioactive cesium in a solvent to obtain a mixture; 2) pressing and forming the mixture to obtain a solidification body precursor; and 3) sintering the solidification body precursor to obtain the radioactive strontium cesium glass ceramic solidification body. The preparation method can solve the problems of cesium fixation, volatilization and loss, and the obtained radioactive strontium cesium glass ceramic solidification body can be applied to the preparation of a cesium source core, improves the reuse of nuclear waste, and can also be used for permanent disposal of strontium and cesium.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of a radioactive strontium cesium glass ceramic solidification body, and belongs to the technical field of nuclear waste industrial treatment and application. BACKGROUND

[0002] High level waste (HLW) is one of the most difficult forms of existing nuclear waste to handle, which mainly exists in the form of waste liquid (waste water). Although the volume of high level waste is less than 1% of the volume of nuclear waste generated by nuclear fuel cycle, the radioactivity contained therein exceeds 99% of the total radioactivity of the nuclear fuel cycle. Due to the characteristics of complex composition and large fluctuation of high level waste, more stringent requirements are put forward for the adaptability (multiple elements, multiple components), containment (high solid solubility) and stability (mechanical, thermal and irradiation stability) of the solidification matrix.

[0003] For high level waste, there are generally two solidification methods of glass and ceramic; the ceramic solidification body has high chemical stability, good thermal stability, high mechanical strength and strong radiation resistance, but its preparation cost is high and the process is complex; while the glass solidification body has simple solidification process, easy remote control operation and wide containment, but the thermal stability and chemical durability are inferior to the ceramic solidification body.

[0004] For radioactive elements in high level waste, such as cesium and strontium, the existing ceramic solidification method is to add rocks, alkali manganese ore, etc. through grinding and pressing forming, which generally needs to be calcined at 1100-1500℃ in air; cesium belongs to group 1A and is difficult to fix, and generally exists in the form of cesium garnet in nature; however, cesium is easy to volatilize above 1000℃, causing nuclide leakage, therefore, a method is urgently needed to reduce the volatilization of cesium and obtain a more stable solidification body of cesium and strontium radioactive elements. SUMMARY

[0005] Problem to be solved by the invention

[0006] In order to solve the problems existing in the prior art, the present application provides a preparation method of a radioactive strontium cesium glass ceramic solidification body, which can solve the problems of fixation and volatilization of cesium, and the obtained radioactive strontium cesium glass ceramic solidification body can be applied to the preparation of cesium source cores, improving the reuse of nuclear waste, and can also be used for permanent disposal of strontium and cesium.

[0007] Solution for solving the problem

[0008] The present application provides a preparation method of a radioactive strontium cesium glass ceramic solidification body, comprising the following steps:

[0009] 1) mixing cesium garnet, granite, radioactive strontium and radioactive cesium uniformly in a solvent to obtain a mixture;

[0010] 2) molding the mixture to obtain a cured body precursor;

[0011] 3) sintering the cured body precursor to obtain a radioactive strontium cesium glass ceramic cured body.

[0012] According to the preparation method, in step 1), the mass ratio of the cesium garnet and the granite is cesium garnet: granite = 1-2: 8-9.

[0013] According to the preparation method, the solvent in step 1) is ethanol.

[0014] According to the preparation method, in step 2), the pressure of the molding is 8-10 MPa, and the pressure holding time is 5-10 minutes.

[0015] According to the preparation method, in step 3), the sintering temperature is 1000-1200℃, and the holding time is 1-2 hours.

[0016] According to the preparation method, in step 3), the sintering is carried out in an inert atmosphere.

[0017] According to the preparation method, in step 3), the heating rate of the sintering is 5-10℃ / min.

[0018] Effects of the invention

[0019] The preparation method of the radioactive strontium cesium glass ceramic cured body solves the problem of volatilization of radioactive cesium under high temperature conditions, and at the same time, the obtained radioactive strontium cesium glass ceramic cured body has good chemical stability, which lays a foundation for solving the solidification problem of radioactive strontium and cesium separated from high-level liquid waste. 137 Cs, 90 Sr. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The XRD diffraction test chart of the cured body-I prepared in Example 1. DETAILED DESCRIPTION

[0021] Various exemplary embodiments, features, and aspects of the present application will be explained hereinafter in detail. The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations.

[0022] In addition, for a better understanding of the present application, a large number of specific details are given in the following detailed description. It will be appreciated by those skilled in the art that the application can be practiced without certain specific details. In other instances, well-known methods, apparatuses, equipment and procedures have not been described in detail so as not to obscure the application's teachings.

[0023] Unless otherwise specified, the units used in the present specification are international standard units, and the numerical values and numerical value ranges appearing in the present application should be understood as including systematic errors that are inevitable in industrial production.

[0024] In the present specification, the meaning of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

[0025] In the present specification, the phrases "some embodiments", "other embodiments", "exemplary embodiments", etc. mean that the particular element (e.g., feature, structure, property, and / or characteristic) being described is included in at least one embodiment described herein, and can or can not be present in other embodiments. In addition, it should be understood that the described elements can be combined in any suitable manner in various embodiments.

[0026] In the present specification, the numerical value range expressed by "numerical value A to numerical value B" means a range including the end point numerical values A and B.

[0027] In the present specification, the meaning of "room temperature", "normal temperature" is "10-40℃".

[0028] The present application provides a preparation method of a radioactive strontium cesium glass ceramic solidification body, comprising the following steps:

[0029] 1) uniformly mixing cesium garnet, granite, radioactive strontium and radioactive cesium in a solvent to obtain a mixture;

[0030] 2) pressing the mixture to form a solidification body precursor;

[0031] 3) sintering the solidification body precursor to obtain a radioactive strontium cesium glass ceramic solidification body.

[0032] Cesium garnet is due to its inherent spatial pore structure, and cesium and strontium are both alkali metals, which can be synergistically solidified, and granite is one of the most stable natural rocks, and the main components are aluminum oxide and silicon oxide; the combination of the two forms a glass-ceramic phase structure.

[0033] The glass-ceramic phase structure of the present application combines the excellent thermal stability and chemical stability of the ceramic phase, and the high inclusion of the glass phase.

[0034] According to the preparation method of the present application, in step 1), the mass ratio of the cesium feldspar and the granite is cesium feldspar: granite = 1-2: 8-9.

[0035] According to the preparation method of the present application, the solvent in step 1) is ethanol.

[0036] According to the preparation method of the present application, in step 2), the pressure for the press forming is 8-10 MPa, and the pressure maintaining time is 5-10 minutes, preferably, the pressure is 8 MPa, and the pressure maintaining time is 10 minutes.

[0037] According to the preparation method of the present application, in step 3), the sintering temperature is 1000-1200℃, and the heat preservation time is 1-2 hours.

[0038] According to the preparation method of the present application, in step 3), the sintering is carried out in an inert atmosphere.

[0039] According to the preparation method of the present application, in step 3), the heating rate for the sintering is 5-10℃ / min, preferably 5℃ / min.

[0040] Examples

[0041] Preparation Example 1

[0042] 5 liters of simulated strontium cesium high-level waste liquid was prepared according to the content of Table 1, and then was evaporated to dryness, and was dried at 100℃ for 6 hours to obtain simulated strontium cesium nitrate solid.

[0043] Table 1 Simulated strontium cesium high-level waste liquid (wherein the anion is NO3 - )

[0044] Elements Simulated feed solution mg / L Ba 2+ ]] 379 Cs + ]] 449 Fe 3+ ]] 0.19 Mo 6+ ]] 27 Na + ]] 11.4 Pd 2+ ]] 0.606 Rb 2+ ]] 69 Sr 2+ ]]> 142 HNO3 0.3 mol / L

[0045] Preparation Example 2

[0046] Aluminum-silicon molecular sieve (the molecular sieve is sodium type silicate aluminate produced by Tianjin Nanhua Catalyst Co., Ltd., and the molar ratio of SiO2 / Al2O3 in the molecular sieve is 5.2:1) and simulated strontium cesium nitrate solid were mixed according to a mass ratio of 70:30, and were heated to 700℃ at a heating rate of 5℃ / min under air atmosphere, and were heat preserved for 1 hour, and were naturally cooled to room temperature to obtain cesium feldspar.

[0047] Example 1

[0048] 0.1 gram of dried cesium feldspar obtained in Preparation Example 2 and 0.9 gram of granite were weighed; 1×10 6 Bq of Cs and 2×10 6 Bq of Sr were added, 1.5 ml of anhydrous ethanol was added, and the mixture was uniformly mixed to obtain a mixture;

[0049] The mixture was molded into a cured body precursor under 8 MPa for 10 minutes;

[0050] The cured body precursor was placed into a graphite crucible and then into a quartz tube furnace, and was heated to 1200℃ at a rate of 5℃ / min under an inert atmosphere, and was kept for 1 hour, and was naturally cooled to room temperature to obtain a radioactive strontium cesium glass ceramic cured body, which was recorded as cured body-1. The tail gas during calcination was absorbed by 0.5 mol / L nitric acid, and then the quartz tube was washed with 0.5 mol / L nitric acid for 3 times to obtain a final absorption liquid, which was recorded as absorption liquid-I.

[0051] Example 2

[0052] 0.2 grams of the dried cesium garnet obtained in Preparation Example 2 and 0.8 grams of granite were weighed, 1×10 6 Bq of Cs and 2×10 6 Bq of Sr were added, 1.5 ml of anhydrous ethanol was added, and the mixture was uniformly mixed to obtain a mixture;

[0053] The mixture was molded into a cured body precursor under 10 MPa for 5 minutes;

[0054] The cured body precursor was placed into a graphite crucible and then into a quartz tube furnace, and was heated to 1000℃ at a rate of 10℃ / min under an inert atmosphere, and was kept for 2 hours, and was naturally cooled to room temperature to obtain a radioactive strontium cesium glass ceramic cured body, which was recorded as cured body-Ⅱ. The tail gas during calcination was absorbed by 0.5 mol / L nitric acid, and then the quartz tube was washed with 0.5 mol / L nitric acid for 3 times to obtain a final absorption liquid, which was recorded as absorption liquid-Ⅱ.

[0055] Example 3

[0056] 0.15 grams of the dried cesium garnet obtained in Preparation Example 2 and 0.85 grams of granite were weighed, 1×10 6 Bq of Cs and 2×10 6 Bq of Sr were added, 1.5 ml of anhydrous ethanol was added, and the mixture was uniformly mixed to obtain a mixture;

[0057] The mixture was molded into a cured body precursor under 8 MPa for 10 minutes;

[0058] The solidification body precursor was placed in a graphite crucible, and then placed in a quartz tube furnace, and then heated to 1100℃ at a rate of 8℃ / min under an inert atmosphere, and kept for 2 hours, and then naturally cooled to room temperature to obtain a radioactive strontium cesium glass ceramic solidification body, denoted as solidification body-III. During the calcination process, the tail gas was absorbed by 0.5 mol / L nitric acid, and then the quartz tube was washed with 0.5 mol / L nitric acid for 3 times, and then the final absorption liquid was obtained, denoted as absorption liquid-III.

[0059] XRD test

[0060] The crystal structure of the solidification body was tested by using a Japanese Rigaku miniflex600, and the test used CuKa rays (wavelength of ), step size of 0.02°, and test range of 2theta of 10°-80°. Figure 1 The crystal structure diagram of Example 1 is shown in FIG. 1. Figure 1 As can be seen from the figure, the solidification body-I has a glass amorphous phase structure, and also has sharp diffraction peaks of crystals, and the material structure of the solidification body-I is a glass-ceramic structure.

[0061] Chemical stability test

[0062] According to the American ASTM C1220-2017 standard, the standard name is "Standard Test Method for Static Leaching of Monolithic Waste Forms for the Treatment of Radioactive Waste", and the method summary is as follows: the sample with a known geometric surface area (S) is soaked in a leaching container containing a known volume (V) of leaching agent, the container is sealed and placed in a thermostat, and kept static at a set temperature for a specified time. After reaching the specified time, the container is taken out of the thermostat, cooled to room temperature, opened, sampled, acidified, and tested for radioactivity; the present patent is leached at 90℃ for 14 days to investigate the chemical stability, and the normalized leaching rates of strontium and cesium are shown in the following table, and the test results of the volatilization rates of strontium and cesium in absorption liquid-I, absorption liquid-II, and absorption liquid-III are shown in the following table.

[0063] Normalized leaching rate of strontium Normalized leaching rate of cesium Volatilization rate of strontium Volatilization rate of cesium Example 1 6.036 x 10 -4 g / m 2 .d]]> 5.271 x 10 -4 g / m 2 .d]]> 0.05％ 0.25％ Example 2 7.216 x 10 -4 g / m 2 .d]]> 5.316 x 10 -4 g / m 2 .d]]> 0.05％ 0.24％ Example 3 8.418 x 10 -4 g / m 2 .d]]> 3.905 x 10 -4 g / m 2 d]]> 0.05％ 0.25％

[0064] It should be noted that although the technical solutions of the present application are described with specific examples, those skilled in the art can understand that the present application should not be limited thereto.

[0065] Having described various embodiments of the application, it is to be understood that the above description is meant not to limit and not to encompass all of the possible embodiments covered by the claims. Many modifications and variations of this application can be apparent to those of ordinary skill in the art without departing from the spirit and scope of the described embodiments. It is intended that the scope of the application should only be limited by the appended claims.

Claims

1. A method for producing a radioactive strontium cesium glass-ceramic solidification body, characterized by, The method comprises the following steps: 1) mixing cesium beryllium, granite, radioactive strontium and radioactive cesium uniformly in a solvent to obtain a mixture, the mass ratio of the cesium beryllium and the granite being 1-2:8-9; 2) pressing the mixture to obtain a solidified body precursor, the pressure of the pressing being 8-10 MPa, and the pressure maintaining time being 5-10 minutes; 3) sintering the solidified body precursor to obtain a radioactive strontium cesium glass ceramic solidified body, the sintering temperature being 1000-1200 ℃, and the holding time being 1-2 hours.

2. The production method according to claim 1, characterized by, The solvent in step 1) is ethanol.

3. The production method according to claim 1 or 2, characterized by, In step 3), the sintering is carried out in an inert atmosphere.

4. The production method according to claim 1 or 2, characterized by, In step 3), the heating rate of the sintering is 5-10 ℃ / min.

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