Method for measuring < 99 > Tc in post-treatment process feed liquid

Abstract

The invention belongs to the technical field of spent fuel post-treatment, and particularly relates to a method for measuring < 99 > Tc in post-treatment process feed liquid. The method comprises the following steps: acquiring a water-phase sample containing < 99Tc > with preset acidity; carrying out separation treatment on the water-phase sample through TEVA (Tetraethyl Vinyl Acetate) resin; and eluting the < 99 > Tc on the TEVA resin by using an eluent, and measuring the < 99 > Tc obtained by elution to obtain a measurement result. According to the present invention, the 99Tc in the process feed liquid is separated and purified by using the high distribution coefficient of the Tc (VII) on the TEEVA resin in the low acid environment, and the method can be widely used for the separation of the 99Tc in the aqueous phase sample, the organic phase sample and the complex system sample.

Description

Technical Field

[0001] The present invention relates to a spent fuel post-processing technology, and specifically relates to a method for 99 Method for Tc measurement. Background Art

[0002] 99 Tc is 235 One of the main fission products of U is a pure beta emitter in power reactors. In order to understand the operation of the technetium washing column and the direction of technetium in the process, it is necessary to analyze the technetium content in the process materials.

[0003] Currently measured 99 The methods for Tc include liquid scintillator counting method, spectrophotometry, etc. However, since the liquid scintillator counting method and spectrophotometry are not very applicable and have a high detection limit, they cannot meet the detection requirements of samples in post-processing process liquid. Summary of the invention

[0004] The purpose of this application is to provide a method for post-processing process liquid 99 The method of Tc measurement solves the problem that the existing technology cannot meet the detection requirements of samples in the post-processing process liquid.

[0005] Technical solution to achieve the purpose of this application:

[0006] The present application embodiment provides a method for treating a liquid feed in a post-treatment process 99 A method for measuring Tc, the method comprising:

[0007] Get the preset acidity content 99 Aqueous sample of Tc;

[0008] The aqueous phase sample is separated and treated by TEVA resin;

[0009] The TEVA resin was eluted with an eluent. 99 Tc, and the eluted 99 Tc is measured to obtain the measurement result.

[0010] Optionally, the preset acidity is 0.01-1 mol / L.

[0011] Optionally, the method for obtaining the preset acidity contains 99 The aqueous phase sample of Tc specifically includes:

[0012] Obtaining a reduced sample of the reduction system, wherein the reduced sample contains Tc;

[0013] After destroying the reduction system of the reduced sample by using a sodium nitrite solution, hydrogen peroxide is added to oxidize Tc in the reduced sample to Tc(VII) and the acidity is adjusted to obtain the aqueous phase sample.

[0014] Optionally, the concentration of the sodium nitrite solution is 2 mol / L.

[0015] Optionally, the method for obtaining the preset acidity contains 99 The aqueous phase sample of Tc specifically includes:

[0016] obtaining an organic phase sample, wherein the organic phase sample contains Tc;

[0017] The organic phase sample is subjected to a back extraction treatment, and the acidity of the water phase after the back extraction is adjusted to obtain the water phase sample.

[0018] Optionally, the stripping treatment of the organic phase sample specifically includes:

[0019] After adding CCl4 solution and ultrapure water, the mixture was shaken and stripped, and then centrifuged.

[0020] Optionally, the eluent is nitric acid.

[0021] Optionally, the aqueous phase sample is separated and treated by TEVA resin, specifically comprising:

[0022] The aqueous sample was passed through the TEVA resin at a preset flow rate, and the fragmented elements were eluted with nitric acid solution.

[0023] Optionally, the method is performed in a glove box.

[0024] The beneficial technical effects of this application are:

[0025] The present application provides a method for post-processing process liquid 99 The method for measuring Tc comprises: obtaining a predetermined acidity content 99 Tc aqueous phase sample; separating and treating the aqueous phase sample through TEVA resin; eluting the TEVA resin with an eluent 99 Tc, and the eluted 99 The present invention uses the high partition coefficient of Tc(VII) on TEVA resin in a low acid environment to measure the distribution of the process liquid. 99 Tc can be used for separation and purification, and can be widely used in aqueous samples, organic samples and complex system samples. 99 The separation of Tc simplifies the sample pretreatment steps, and the separation efficiency can reach more than 95%, which can achieve trace level 99 Determination of Tc. DETAILED DESCRIPTION

[0026] In order to make those skilled in the art better understand the present application, the technical scheme in the embodiments of the present application will be clearly and completely described below. Obviously, the embodiments described below are only a part of the embodiments of the present application, not all. Based on the embodiments recorded in the present application, all other embodiments obtained by those skilled in the art without paying creative work are within the scope of protection of the present application.

[0027] 99 Tc is 235 One of the main fission products of U, it is a pure beta emitter in power reactors. In order to understand the operation of the technetium washing column and the direction of technetium in the process, it is necessary to analyze the technetium content in the process material. Since the composition of the process liquid is complex and contains a large number of interfering nuclides such as uranium and plutonium, it is difficult to achieve trace and trace levels. 99 The determination of Tc causes great interference. The current determination methods include liquid scintillator counting method, spectrophotometry, etc. Since the liquid scintillator counting method and spectrophotometry are not very applicable and the detection limit of the method is high, they cannot accurately determine the content of Tc in the post-processing process liquid. 99 Tc content.

[0028] In order to solve the problems of the prior art, the present invention provides a method for determining the content of 99 The method of Tc content is to use Tc (VII) to have a higher distribution coefficient on quaternary ammonium salt resin (TEVA resin) in a low acid environment to 99 Tc was separated and purified by using TEVA resin column for different process liquids. 99 Tc is separated, and the sample contains a large amount of MoH + Impurities can be realized in aqueous phase, organic phase, process liquid with different γ activity concentrations and trace levels 99 The determination of Tc effectively improves the speed of analysis and detection, simplifies the analysis operation steps, and has the advantages of low measurement limit, wide application range and good separation effect. This is achieved by testing different pretreatment methods and interference elimination for the above-mentioned different samples, combined with factors such as the sample radioactivity level. 99 Accurate determination of Tc content in samples 99 Tc fast and accurate analysis.

[0029] Based on the above content, in order to clearly and in detail illustrate the above advantages of the present application, the specific implementation methods of the present application are described below.

[0030] The present application provides a method for post-processing process liquid 99 Methods for measuring Tc include:

[0031] Step S101: Obtaining the content of preset acidity 99 Aqueous sample of Tc;

[0032] Step S102: separating the aqueous phase sample by TEVA resin;

[0033] Step S103: Using an eluent to elute the TEVA resin 99 Tc, and the eluted 99 Tc is measured to obtain the measurement result.

[0034] In the present application, the high partition coefficient of Tc(VII) on TEVA resin in a low acid environment is used to 99 Tc is separated and purified, and the radioactivity level of the sample is combined to achieve 99 The present invention has a high degree of separation and purification, a wide range of applications, and a low detection limit, and can be widely used in aqueous samples, organic samples, and complex system samples. 99 The separation of Tc simplifies the sample pretreatment steps, and the separation efficiency can reach more than 95%, which can achieve trace level 99 Determination of Tc.

[0035] In one example, the preset acidity may be 0.01-1 mol / L.

[0036] In the specific implementation, including 99 Different types of process samples can be divided into general aqueous phase samples, reduction system samples and organic phase samples. Different pretreatment steps can be performed for different types of process samples. 99 Tc aqueous sample, sample 99 The valence state of Tc is generally Tc(VII), so there is no need to 99 Adjustment of Tc valence state. After adjusting the sample acidity, take a certain volume of sample and pass it through the TEVA column, use a certain concentration of nitric acid to elute a large amount of uranium and other interfering nuclides in the sample, and then choose a suitable eluent to elute the resin column. 99 Tc, for samples 99 After Tc is separated and purified, a certain volume of eluent is taken and 99 Analysis of Tc content.

[0037] For the reduced sample of the reduction system, in some possible implementations of the present application, step S101 may specifically include:

[0038] Obtaining a reduced sample of the reduction system, wherein the reduced sample contains Tc;

[0039] After destroying the reduction system of the reduced sample by using a sodium nitrite solution, hydrogen peroxide is added to oxidize Tc in the reduced sample to Tc(VII) and the acidity is adjusted to obtain the aqueous phase sample.

[0040] It is understandable that due to the 99 The Tc sample contains a certain concentration of reducing substances such as hydroxylamine and hydrazine nitrate, which makes some of the samples 99 The valence state of Tc is reduced to below VII. 99 Tc has better separation and purification. It is necessary to add a suitable oxidant to oxidize the low-valent Tc to Tc (VII), and then separate and purify it according to the above-mentioned general aqueous phase sample and then measure it.

[0041] In one example, the concentration of the sodium nitrite solution is 2 mol / L.

[0042] For an organic phase sample, in some possible implementations of the present application, step S101 may specifically include:

[0043] obtaining an organic phase sample, wherein the organic phase sample contains Tc;

[0044] The organic phase sample is subjected to a back extraction treatment, and the acidity of the water phase after the back extraction is adjusted to obtain the water phase sample.

[0045] As an example, the stripping treatment of the organic phase sample may specifically include:

[0046] After adding CCl4 solution and ultrapure water, the mixture was shaken and stripped, and then centrifuged.

[0047] It is understandable that, in specific implementation, a certain volume of 99 Place the Tc organic phase sample in an extraction tube, add a certain amount of CCl4 and ultrapure water, shake and centrifuge, discard the lower organic phase, and take the aqueous phase sample after stripping according to the general aqueous phase sample. 99 Tc was separated and purified.

[0048] In a specific implementation, the eluent may be nitric acid.

[0049] In some possible implementations of the embodiments of the present application, the aqueous phase sample is separated and processed by TEVA resin, which may specifically include:

[0050] The aqueous sample was passed through the TEVA resin at a preset flow rate, and the fragmented elements were eluted with nitric acid solution.

[0051] In one example, the method is performed in a glove box, which meets the radiation shielding requirements and can effectively ensure the safety of operators. At the same time, the method has a fast analysis speed and reduces the radiation dose to personnel.

[0052] The following describes in detail a method for treating a liquid in a post-treatment process provided by an embodiment of the present application with reference to a specific example. 99 Method for Tc measurement.

[0053] For general aqueous samples, the present invention provides a method for post-treatment process liquid. 99 The method of measuring Tc may specifically include:

[0054] Since Tc(VII) has a high distribution coefficient on the TEVA resin column in a low acid environment (such as 0.01-1 mol / L), the adsorbed 99 Tc can be analyzed. 99 The Tc aqueous process liquid was adjusted to 0.01mol / L, 0.1mol / L, 0.4mol / L, 0.6mol / L, 0.8mol / L, 1mol / L, 2mol / L and 3mol / L with a small amount of ammonia water, and passed through the TEVA resin column at a flow rate of 0.8-1mL / min. After eluting the fragmented elements with 30mL of nitric acid solution with acidity of 0.001mol / L, 0.01mol / L, 0.05mol / L, 0.1mol / L and 0.25mol / L, 10mL of nitric acid with concentrations of 5mol / L, 6mol / L, 7mol / L, 8mol / L and 9mol / L was used to remove the adsorbed elements on the column. 99 Tc was eluted and measured. The test results are as follows:

[0055] Table 1: Effect of sample acidity on recovery

[0056]

[0057]

[0058] Table 2 Effect of eluent acidity on recovery rate

[0059] Eluent acidity (mol / L) Analysis results (g / L) Recovery rate (%) 0.001 <![CDATA[1.45ⅹ10 -3 ]]> 88.85 0.01 <![CDATA[1.51ⅹ10 -3 ]]> 92.85 0.05 <![CDATA[1.78ⅹ10 -3 ]]> 90.87 0.1 <![CDATA[1.41ⅹ10 -3 ]]> 86.55 0.25 <![CDATA[1.45ⅹ10 -3 ]]> 89.11

[0060] Table 3 Effect of eluent acidity on recovery rate

[0061] Eluent acidity (mol / L) Analysis results (g / L) Recovery rate (%) 5 <![CDATA[8.63ⅹ10 -4 ]]> 47.67 6 <![CDATA[1.30ⅹ10 -3 ]]> 71.79 7 <![CDATA[1.51ⅹ10 -3 ]]> 83.32 8 <![CDATA[1.67ⅹ10 -3 ]]> 92.12 9 <![CDATA[1.66ⅹ10 -3 ]]> 91.58

[0062] In summary, it can be seen that for general aqueous samples, the optimal column acidity of the sample is 0.01 mol / L nitric acid, the optimal eluent acidity is 0.01 mol / L nitric acid, and the optimal eluent acidity is 8 mol / L.

[0063] For the reduction system sample, the present application provides a method for post-treatment process liquid.99 The method of measuring Tc may specifically include:

[0064] First, add 2 mol / L sodium nitrite solution to destroy the reduction system, then add 30% hydrogen peroxide to oxidize low-valent Tc to Tc(VII), and then let it stand for 10 minutes. When no bubbles are generated in the above solution, treat the water phase sample as described above and then measure. The examples are as follows:

[0065] Sample No. Oxidation time (min) Tc concentration (g / L) Recovery rate (%) 1 7 <![CDATA[1.04ⅹ10 -3 ]]> 86.67 2 8 <![CDATA[1.09ⅹ10 -3 ]]> 90.83 3 9 <![CDATA[1.11ⅹ10 -3 ]]> 92.5 4 10 <![CDATA[1.16ⅹ10 -3 ]]> 96.67 5 11 <![CDATA[1.03ⅹ10 -3 ]]> 85.83

[0066] For the reduction system sample, the present application provides a method for post-treatment process liquid. 99 The method of measuring Tc may specifically include:

[0067] Take 1 mL of organic phase sample in an extraction tube, add 3 mL of CCl4 solution and 2 mL of ultrapure water, shake and extract for 8 to 10 minutes, and centrifuge for 3 to 5 minutes. 99 Tc is separated and purified. The examples are as follows:

[0068]

[0069] It should also be noted that a Mo standard solution with a similar Tc content was added to the process sample, and the sample was separated and purified by a TEVA numerical column after being pretreated with a general aqueous sample. 98 MoH + The interference with the measurement and the comparison of the results of the sample that has not passed the column are as follows:

[0070]

[0071] Based on the above analysis, 98 After the Mo sample was pretreated with TEVA resin column, 98 Mo binds to a H + The formed 98 MoH + The interference is almost eliminated. 98 Mo has almost no effect 99 Accurate determination of Tc content.

[0072] The present application is described in detail above in conjunction with the embodiments, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present application. Any content not described in detail in the present application can adopt the existing technology.

Claims

1. A method for post-processing liquid 99 The method for measuring Tc is characterized in that The method comprises: Get the preset acidity content 99 Aqueous sample of Tc; The aqueous phase sample is separated and treated by TEVA resin; The TEVA resin was eluted with an eluent. 99 Tc, and the eluted 99 Tc is measured to obtain the measurement result.

2. The method for post-processing liquid according to claim 1 99 The method for measuring Tc is characterized in that The preset acidity is 0.01-1 mol / L.

3. The method for post-processing liquid according to claim 2 99 The method for measuring Tc is characterized in that The content of the preset acidity is obtained 99 The aqueous phase sample of Tc specifically includes: obtaining a reduced sample of the reduction system, wherein the reduced sample contains Tc; After destroying the reduction system of the reduced sample by using a sodium nitrite solution, hydrogen peroxide is added to oxidize Tc in the reduced sample to Tc(VII) and the acidity is adjusted to obtain the aqueous phase sample.

4. The method for post-processing liquid according to claim 3 99 The method for measuring Tc is characterized in that The concentration of the sodium nitrite solution is 2 mol / L.

5. The method for post-processing liquid according to claim 2 99 The method for measuring Tc is characterized in that The content of the preset acidity is obtained 99 The aqueous phase sample of Tc specifically includes: obtaining an organic phase sample, wherein the organic phase sample contains Tc; The organic phase sample is subjected to a back extraction treatment, and the acidity of the water phase after the back extraction is adjusted to obtain the water phase sample.

6. The method for post-processing liquid according to claim 5 99 The method for measuring Tc is characterized in that The stripping treatment of the organic phase sample specifically comprises: After adding CCl4 solution and ultrapure water, the mixture was shaken and stripped, and then centrifuged.

7. The method for post-processing a liquid according to any one of claims 1 to 6. 99 The method for measuring Tc is characterized in that The eluent is nitric acid.

8. The method for post-processing a liquid according to any one of claims 1 to 6. 99 The method for measuring Tc is characterized in that The aqueous phase sample is separated and processed by TEVA resin, specifically comprising: The aqueous sample was passed through the TEVA resin at a preset flow rate, and the fragmented elements were eluted with nitric acid solution.

9. The method for post-processing a liquid according to any one of claims 1 to 6. 99 The method for measuring Tc is characterized in that The method is performed in a glove box.

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