A method for analyzing and detecting plutonium oxalate precipitation

Abstract

The present invention provides an analytical detection method for plutonium oxalate precipitation, comprising the following steps: dissolving a plutonium oxalate precipitation sample to obtain a dissolving solution; converting the dissolving solution into a medium to obtain a test solution; and detecting the content of Pu element, the content of U element, and the content of 241 The content of Am element, the content of non-volatile impurity elements, and the radiation energy of γ. The analytical detection method of the plutonium oxalate precipitate of the present invention can judge the quality of the plutonium dioxide powder product in advance according to the plutonium oxalate precipitate, and reliably detect and analyze the product quality and control the quality before using the plutonium oxalate precipitate as a raw material to prepare plutonium dioxide.

Description

Technical Field

[0001] The invention relates to the technical field of spent fuel post-processing, in particular to an analysis and detection method for plutonium oxalate precipitation. Background Art

[0002] In spent fuel reprocessing, plutonium products refer to plutonium dioxide powder. Currently, oxalic acid is used as a precipitant to generate plutonium oxalate precipitate, which is then heated and decomposed to generate plutonium dioxide powder. When plutonium dioxide powder is used in power reactor nuclear fuel, mixed oxide fuel and other fuels, the plutonium content, plutonium isotope content, impurity content, and especially the content of boron equivalent elements should meet certain requirements. Before the generation of plutonium dioxide, the composition of the intermediate product plutonium oxalate precipitate is determined to judge the quality of the product in advance. Therefore, it is of great significance to analyze and detect the plutonium oxalate precipitate.

[0003] In view of this, it is urgent to propose an analytical detection method for plutonium oxalate precipitation in order to carry out quality control of plutonium dioxide.

[0004] In addition, after the precipitation of plutonium oxalate, the oxalate mother liquor still contains plutonium, and the plutonium in the oxalate mother liquor needs to be returned for purification. 4+ It has a strong complexing effect, so potassium permanganate is used to destroy it. The analysis of plutonium oxalate precipitation is also helpful to obtain information such as the impurity content of the oxalate mother liquor. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an analytical detection method for plutonium oxalate precipitation, so as to solve the technical problem that it is difficult to control the quality of plutonium dioxide production in the prior art.

[0006] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0007] A method for analyzing and detecting plutonium oxalate precipitation comprises the following steps:

[0008] (1) dissolving a plutonium oxalate precipitate sample to obtain a dissolving solution;

[0009] (2) performing medium conversion on the dissolved solution obtained in step (1) to obtain a test solution;

[0010] (3) Detecting the content of Pu element, the content of U element, 241 The content of Am element, the content of non-volatile impurity elements, and the radiation energy of γ.

[0011] Preferably, in step (1), an ammonium carbonate solution is used to dissolve the plutonium oxalate precipitate sample.

[0012] In the dissolving solution, the concentration of ammonium carbonate is 100 g / L, and the concentration of plutonium oxalate is 10-20 g / L.

[0013] Preferably, in step (2), a nitric acid solution is used to perform medium conversion on the dissolving solution.

[0014] In the test solution, the concentration of nitric acid is 6 mol / L, and the concentration of plutonium oxalate is 10-20 g / L.

[0015] Preferably, in step (3), the content of the Pu element is detected by the following method:

[0016] The test liquid is connected to a coulometer for electrolysis, and the Pu element in the test liquid is reduced and oxidized on the working electrode by controlling the electrode potential. The content of the Pu element is calculated based on the amount of electricity in the coulometer.

[0017] Preferably, the content of the U element is detected by the following method:

[0018] Under the environment of pH value of 6-7, the liquid to be tested is irradiated with an ultraviolet pulse light source to generate fluorescence, and the fluorescence intensity of the liquid to be tested is measured, and the content of U element is obtained according to the fluorescence intensity.

[0019] Preferably, the 241 The content of Am element is detected by the following method:

[0020] The gamma-ray energy spectrum of the test liquid is measured by a gamma-ray spectrometer, and the gamma-ray energy spectrum obtained and the detection efficiency of the gamma-ray spectrometer are calculated to obtain 241 The content of Am element.

[0021] Preferably, the content of the non-volatile impurity elements is detected by the following method:

[0022] The plutonium and impurity elements in the test solution are separated by a strong alkaline anion resin, and then the content of the impurity elements therein is determined by ICP-AES method.

[0023] Preferably, the gamma radiation energy is detected by the following method:

[0024] The test liquid is subjected to a gamma-ray energy spectrum measurement using a gamma spectrometer, and the gamma radiation energy is obtained according to the peak area in the obtained gamma-ray energy spectrum.

[0025] Preferably, the analytical detection method for plutonium oxalate precipitation further comprises: (4) respectively calculating the content of the U element obtained in step (3), 241 The content of Am element, the content of non-volatile impurity elements, the ratio of γ radiation energy to the content of Pu element, and the equivalent value of each detection value are obtained.

[0026] Preferably, the analytical detection method of plutonium oxalate precipitation is based on the Pu element, U element, 241 The quality of the plutonium oxalate precipitate is determined by the content of Am element, non-volatile impurity elements, and the γ radiation energy.

[0027] Preferably, judging the quality of the plutonium oxalate precipitate comprises:

[0028] When the mass fraction of the Pu element is greater than or equal to 86.0%, the quality is qualified; otherwise, the quality is unqualified; and / or,

[0029] When the equivalent value of the U element is less than 6000 μg / g Pu, the quality is qualified; otherwise, the quality is unqualified; and / or,

[0030] When the equivalent value of the non-volatile impurity element is less than 6000 μg / g Pu, the quality is qualified; otherwise, the quality is unqualified; and / or,

[0031] When the equivalent value of the gamma radiation energy is less than or equal to 10 6 MeV·Bq / g Pu, the quality is qualified; otherwise, the quality is unqualified.

[0032] The above solution of the present invention includes at least the following beneficial effects:

[0033] The method for analyzing and detecting plutonium oxalate precipitation of the present invention comprises the following steps: dissolving a plutonium oxalate precipitation sample to obtain a dissolving solution; converting the dissolving solution into a medium to obtain a test solution; and detecting the content of Pu element, the content of U element, and the content of 241 The content of Am element, the content of non-volatile impurity elements, and the radiation energy of γ. The analytical detection method of the plutonium oxalate precipitate of the present invention can judge the quality of the plutonium dioxide powder product in advance according to the plutonium oxalate precipitate, and reliably detect and analyze the product quality and control the quality before using the plutonium oxalate precipitate as a raw material to prepare plutonium dioxide. DETAILED DESCRIPTION

[0034] In the embodiments of the present invention, if the specific conditions are not specified, the conventional conditions or the conditions recommended by the manufacturer are followed. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially. Raw materials of different manufacturers and models do not affect the implementation of the technical solution of the present invention and the realization of the technical effects.

[0035] The analysis and detection method of plutonium oxalate precipitation in this embodiment comprises the following steps:

[0036] (1) Taking a plutonium oxalate precipitate sample, dissolving the plutonium oxalate precipitate sample with an ammonium carbonate solution to obtain a dissolving solution; in the dissolving solution, the concentration of ammonium carbonate is 100 g / L, and the concentration of plutonium oxalate is 10-20 g / L.

[0037] As a preferred implementation of this embodiment, the plutonium oxalate precipitate sample can be obtained by sampling the plutonium oxalate filter cake at multiple points to ensure the uniformity of the sample. After the sampling is completed, the samples are mixed evenly and then divided into 1 to 3 parallel samples.

[0038] (2) The solution obtained in step (1) is subjected to medium conversion by using a nitric acid solution to obtain a test solution; in the test solution, the concentration of nitric acid is 6 mol / L, and the concentration of plutonium oxalate is 10-20 g / L.

[0039] (3) Detecting the content of Pu element, the content of U element, 241 The content of Am element, the content of non-volatile impurity elements, and the radiation energy of γ.

[0040] As a preferred implementation of this embodiment, the content of the Pu element is detected by the following method: the test liquid is connected to a coulometer for electrolysis, and the Pu element in the test liquid is reduced and oxidized on the working electrode by controlling the electrode potential, and the content of the Pu element is calculated based on the amount of electricity in the coulometer. The content of the Pu element is calculated based on Faraday's law.

[0041] The content of the U element is detected by the following method: under a pH value of 6-7, the test liquid is irradiated with an ultraviolet pulse light source to generate fluorescence, the fluorescence intensity of the test liquid is measured, and the content of the U element is obtained according to the fluorescence intensity.

[0042] In order to reduce the influence on the test result and obtain a more accurate test result, before the test liquid is irradiated with the ultraviolet pulse light source, the test liquid is extracted and separated, and the extracted liquid is irradiated with the ultraviolet pulse light source.

[0043] Said 241 The content of Am element is detected by the following method: the test liquid is measured with a γ-ray energy spectrum using a γ-ray spectrometer, and the obtained γ-ray energy spectrum and the detection efficiency of the γ-ray spectrometer are calculated to obtain 241 The content of Am element.

[0044] Among them, the 241 The content of Am can be calculated by the following method: 237 U and 241The branch intensity ratio of the two nuclides Am at 59.5keV and 208keV, as well as the detection efficiency of the gamma spectrometer, are calculated to obtain 241 The content of Am element.

[0045] It should be noted that 241 Am 241 Pu decays to the point where the value detected in the test liquid is not fixed.

[0046] The content of the non-volatile impurity elements is detected by the following method: the plutonium in the test solution is separated from the impurity elements by a strong alkaline anion resin, and then the content of the impurity elements is determined by ICP-AES method, which is inductively coupled plasma atomic emission spectrometry.

[0047] The gamma radiation energy is detected by the following method: the gamma ray energy spectrum of the test liquid is measured by a gamma spectrometer, and the gamma radiation energy is obtained according to the peak area in the obtained gamma ray energy spectrum.

[0048] (4) Calculate the content of U element obtained in step (3), 241 The content of Am element, the content of non-volatile impurity elements, the ratio of γ radiation energy to the content of Pu element, and the equivalent value of each detection value are obtained.

[0049] In this embodiment, each measurement result is converted and finally expressed in μg / gPu. The detection results of Pu element content and γ radiation energy can be directly used to judge the quality of the plutonium oxalate precipitate; U element content, 241 The results of the determination of the Am element content and the non-volatile impurity element content are divided by the total amount of plutonium, and the final result is plutonium-based μg / gPu.

[0050] According to Pu element, U element, 241 The quality of the plutonium oxalate precipitate is judged by the content of Am element, non-volatile impurity elements, and γ radiation energy, which may specifically include:

[0051] When the mass fraction of the Pu element is greater than or equal to 86.0%, the quality is qualified; otherwise, the quality is unqualified; and / or,

[0052] When the equivalent value of the U element is less than 6000 μg / g Pu, the quality is qualified; otherwise, the quality is unqualified; and / or,

[0053] When the equivalent value of the non-volatile impurity element is less than 6000 μg / g Pu, the quality is qualified; otherwise, the quality is unqualified; and / or,

[0054] When the equivalent value of the gamma radiation energy is less than or equal to 10 6 MeV·Bq / g Pu, the quality is qualified; otherwise, the quality is unqualified.

[0055] It should be noted that the equivalent value of the U element and the 241 The equivalent value of the Am element, the equivalent value of the non-volatile impurity element, and the equivalent value of the γ radiation energy all refer to the equivalent to the mass of Pu.

[0056] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A method for analyzing and detecting plutonium oxalate precipitation, characterized in that: The steps include: (1) dissolving a plutonium oxalate precipitate sample to obtain a dissolving solution; (2) performing medium conversion on the dissolved solution obtained in step (1) to obtain a test solution; (3) Detecting the content of Pu element, the content of U element, 241 The content of Am element, the content of non-volatile impurity elements, and the radiation energy of γ; (4) Calculate the content of U element obtained in step (3), 241 The content of Am element, the content of non-volatile impurity elements, the ratio of γ radiation energy to the content of Pu element, and the equivalent value of each detection value are obtained; According to Pu element, U element, 241 The quality of the plutonium oxalate precipitate is determined by the content of Am element, non-volatile impurity elements, and the γ radiation energy, including: When the mass fraction of the Pu element is greater than or equal to 86.0%, the quality is qualified; otherwise, the quality is unqualified; and / or When the equivalent value of the U element is less than 6000 μg / g Pu, the quality is qualified; otherwise, the quality is unqualified; and / or When the equivalent value of the non-volatile impurity element is less than 6000 μg / g Pu, the quality is qualified; otherwise, the quality is unqualified; and / or When the equivalent value of the gamma radiation energy is less than or equal to 10 6 MeV·Bq / g Pu, the quality is qualified; otherwise, the quality is unqualified.

2. The method for analyzing and detecting plutonium oxalate precipitation according to claim 1, characterized in that: In step (1), the plutonium oxalate precipitate sample is dissolved by using an ammonium carbonate solution; In the dissolving solution, the concentration of ammonium carbonate is 100 g / L, and the concentration of plutonium oxalate is 10-20 g / L.

3. The method for analyzing and detecting plutonium oxalate precipitation according to claim 1, characterized in that: In step (2), a nitric acid solution is used to perform medium conversion on the dissolving solution; In the test solution, the concentration of nitric acid is 6 mol / L, and the concentration of plutonium oxalate is 10-20 g / L.

4. The method for analyzing and detecting plutonium oxalate precipitation according to claim 1, characterized in that: In step (3), the content of the Pu element is detected by the following method: The test liquid is connected to a coulometer for electrolysis, and the Pu element in the test liquid is reduced and oxidized on the working electrode by controlling the electrode potential. The content of the Pu element is calculated based on the amount of electricity in the coulometer.

5. The method for analyzing and detecting plutonium oxalate precipitation according to claim 1, characterized in that: The content of the U element is detected by the following method: Under the environment of pH value of 6-7, the liquid to be tested is irradiated with an ultraviolet pulse light source to generate fluorescence, and the fluorescence intensity of the liquid to be tested is measured, and the content of U element is obtained according to the fluorescence intensity.

6. The method for analyzing and detecting plutonium oxalate precipitation according to claim 1, characterized in that: Said 241 The content of Am element is detected by the following method: The gamma-ray energy spectrum of the test liquid is measured by a gamma-ray spectrometer, and the gamma-ray energy spectrum obtained and the detection efficiency of the gamma-ray spectrometer are calculated to obtain 241 The content of Am element.

7. The method for analyzing and detecting plutonium oxalate precipitation according to claim 1, characterized in that: The content of the non-volatile impurity elements is detected by the following method: The plutonium and impurity elements in the test solution are separated by a strong alkaline anion resin, and then the content of the impurity elements therein is determined by ICP-AES method.

8. The method for analyzing and detecting plutonium oxalate precipitation according to claim 1, characterized in that: The γ radiation energy is detected by the following method: The test liquid is subjected to a gamma-ray energy spectrum measurement using a gamma spectrometer, and the gamma radiation energy is obtained according to the peak area in the obtained gamma-ray energy spectrum.