A method for measuring the plutonium content in a uranium sample

Abstract

The present invention provides a method for measuring the plutonium content in a uranium sample, comprising: performing a deuterium removal treatment on the collected uranium sample to obtain a treated uranium sample; the concentration of uranium in the uranium sample being a preset concentration value; measuring the plutonium content of the treated uranium sample by a preset liquid scintillation spectrometer to obtain the energy value of plutonium in the uranium sample; determining the target concentration value of plutonium in the uranium sample according to the energy value of plutonium and a preset standard solution curve; the preset standard solution curve being determined according to the concentration and energy value of a plutonium standard stock solution. The solution of the present invention solves the problems of long sample analysis time and large irradiation dose received by personnel during the plutonium determination process, and effectively improves the analysis speed.

Description

Technical Field

[0001] The present invention relates to the technical field of spent fuel reprocessing analysis, and particularly to a method for measuring the plutonium content in uranium samples. Background Art

[0002] In the spent fuel reprocessing process in China, the separation, purification and accurate determination of plutonium are of great significance for the quality control and stable operation of the entire technological process. The determination of plutonium is a crucial part of the spent fuel reprocessing analysis technology. Currently, the analytical methods for the plutonium content in the samples of the reprocessing process mainly include TiOA (triisooctylamine) extraction separation, TTA (thiophenoyltrifluoroacetone) extraction separation α counting method or α spectrometry method, and spectrophotometry, etc.

[0003] However, these analytical methods all require complicated pretreatment steps, and have the disadvantages of long sample analysis time and large irradiation dose for personnel. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to provide a method for measuring the plutonium content in uranium samples. The problems of long sample analysis time and large irradiation dose for personnel during the plutonium determination process are solved, and the analysis speed is effectively improved.

[0005] To solve the above technical problem, the technical solution of the present invention is as follows:

[0006] A method for measuring the plutonium content in uranium samples, comprising:

[0007] Performing tritium removal treatment on the collected uranium samples to obtain the treated uranium samples; the concentration of uranium in the uranium samples is a preset concentration value;

[0008] Measuring the plutonium content of the treated uranium samples by a preset liquid scintillation spectrometer to obtain the energy value of plutonium in the uranium samples;

[0009] Determining the target concentration value of plutonium in the uranium samples according to the energy value of plutonium and a preset standard solution curve; the preset standard solution curve is determined according to the concentration and energy value of the plutonium standard stock solution.

[0010] Optionally, performing tritium removal treatment on the collected uranium samples to obtain the treated uranium samples, comprising:

[0011] For the uranium samples in the organic phase, performing tritium removal treatment on the uranium samples by tributyl phosphate to obtain the tritium-removed uranium samples; or

[0012] For the uranium samples in the aqueous phase, performing tritium removal treatment on the uranium samples by nitric acid to obtain the tritium-removed uranium samples.

[0013] Optionally, for the uranium sample in the organic phase, tritium removal treatment is performed on the uranium sample through tributyl phosphate to obtain a tritium-removed uranium sample, including:

[0014] Take tributyl phosphate and add it to the uranium sample in the organic phase;

[0015] Under normal pressure environment, distillation and volume fixation treatment are performed on the uranium sample in the organic phase added with the tributyl phosphate to obtain a tritium-removed uranium sample.

[0016] Optionally, for the uranium sample in the aqueous phase, tritium removal treatment is performed on the uranium sample through nitric acid to obtain a tritium-removed uranium sample, including:

[0017] Take nitric acid and add it to the uranium sample in the aqueous phase;

[0018] Under normal pressure environment, distillation and volume fixation treatment are performed on the uranium sample in the aqueous phase added with the nitric acid to obtain a tritium-removed uranium sample.

[0019] Optionally, the method for measuring the plutonium content in the uranium sample further includes:

[0020] According to the preset detection efficiency curve and the target concentration value of plutonium in the uranium sample, determine the detection efficiency of the uranium sample on the preset liquid scintillation spectrometer, and the preset detection efficiency curve is determined according to the recovery rate of plutonium by the uranium matrix solution.

[0021] Optionally, according to the preset detection efficiency curve and the target concentration value of plutonium in the uranium sample, determining the detection efficiency of the uranium sample on the preset liquid scintillation spectrometer includes:

[0022] Based on the preset detection efficiency curve, determine the standard plutonium concentration value corresponding to the preset uranium concentration value in the uranium sample;

[0023] According to the standard plutonium concentration value and the target concentration value of plutonium in the uranium sample, determine the detection efficiency of the uranium sample on the preset liquid scintillation spectrometer.

[0024] Optionally, the preset detection efficiency curve is obtained through the following process:

[0025] Add a preset amount of plutonium to uranium matrix solutions with multiple different uranium concentrations;

[0026] Measure the recovery rate of the preset amount of plutonium in uranium matrix solutions with different uranium concentrations;

[0027] According to the recovery rate, draw a preset detection efficiency curve.

[0028] Optionally, when measuring the plutonium content of the processed uranium sample by a preset liquid scintillation spectrometer, the discrimination thresholds of the first preset radionuclide α and the second preset radionuclide β of the preset liquid scintillation spectrometer are 130 V to 160 V, the preset energy window is 0 keV to 21 keV, and the preset measurement time is 5 min.

[0029] Optionally, the preset standard solution curve is determined according to the concentration and energy value of the plutonium standard stock solution, and includes:

[0030] Obtain a plutonium standard stock solution with a concentration of 0.1 g / L;

[0031] Based on the plutonium standard stock solution with a concentration of 0.1 g / L, obtain multiple plutonium standard stock solutions with different concentrations;

[0032] Measure the multiple plutonium standard stock solutions with different concentrations by a preset liquid scintillation spectrometer to obtain the energy values corresponding to the plutonium standard stock solutions with different concentrations;

[0033] Draw the preset standard solution curve according to the energy values corresponding to the plutonium standard stock solutions with different concentrations.

[0034] Optionally, obtaining a plutonium standard stock solution with a concentration of 0.1 g / L includes:

[0035] Take 0.011 g of plutonium dioxide standard substance, add a mixed acid composed of nitric acid and hydrogen fluoride in a ratio of 275:2, and dissolve it at a temperature of 170 °C to 200 °C to obtain a dissolved solution;

[0036] Evaporate and cool the dissolved solution to obtain a process solution;

[0037] Make a 100 mL constant volume of the process solution with 1 mol / L nitric acid to obtain a plutonium standard stock solution with a concentration of 0.1 g / L.

[0038] The above solution of the present invention has at least the following beneficial effects:

[0039] By performing deuterium removal treatment on the collected uranium sample, a processed uranium sample is obtained; the concentration of uranium in the uranium sample is a preset concentration value; by measuring the plutonium content of the processed uranium sample by a preset liquid scintillation spectrometer, the energy value of plutonium in the uranium sample is obtained; according to the energy value of plutonium and the preset standard solution curve, the target concentration value of plutonium in the uranium sample is determined; the preset standard solution curve is determined according to the concentration and energy value of the plutonium standard stock solution; the problems of long sample analysis time and large irradiation dose for personnel during the plutonium determination process are solved. By pre-removing deuterium from the uranium sample, the influence of the low-energy β radioactive substance deuterium on the plutonium content measurement can be effectively removed. The plutonium content measurement based on the preset standard solution curve can shorten the measurement time and effectively improve the analysis speed. Brief Description of the Drawings

[0040] Figure 1 It is a schematic flowchart of a method for measuring the plutonium content in a uranium sample according to an embodiment of the present invention. Detailed Description of the Embodiments

[0041] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0042] As Figure 1 shown, an embodiment of the present invention provides a method for measuring the plutonium content in a uranium sample, including:

[0043] Step 11: Perform tritium removal treatment on the collected uranium sample to obtain a treated uranium sample; the concentration of uranium in the uranium sample is a preset concentration value;

[0044] Step 12: Measure the plutonium content of the treated uranium sample by a preset liquid scintillation spectrometer to obtain the energy value of plutonium in the uranium sample;

[0045] Step 13: Determine the target concentration value of plutonium in the uranium sample according to the energy value of plutonium and a preset standard solution curve; the preset standard solution curve is determined according to the concentration and energy value of a plutonium standard stock solution.

[0046] In this embodiment, before measuring the collected uranium sample, tritium removal treatment should be carried out first to remove the influence of low-energy β radioactive substance tritium on the measurement of plutonium content. This tritium removal treatment is preferably carried out by atmospheric distillation. Measure the plutonium content of the treated uranium sample by a preset liquid scintillation spectrometer to obtain the energy value of plutonium in the uranium sample. Then, based on the preset standard solution curve, the target concentration value of plutonium corresponding to the energy value of plutonium in the uranium sample can be determined. The preset standard solution curve mentioned here is determined according to the concentration and energy value of a plutonium standard stock solution. The preset standard solution curve corresponds the concentration of the plutonium standard stock solution and its corresponding energy value. Therefore, in this embodiment, only the energy value of plutonium in the uranium sample needs to be determined to determine the target concentration value of plutonium according to the preset standard solution curve; it not only effectively removes the influence of low-energy β radioactive substance tritium on the measurement of plutonium content, but also shortens the measurement time and effectively improves the analysis speed.

[0047] Here, the preset liquid scintillation spectrometer is described: The preset liquid scintillation spectrometer is specifically a liquid scintillation spectrometer, which is used to measure β radioactive elements in a sample. The plutonium element in this application is a low-energy β emitter 241When measuring a uranium sample for Pu, the uranium sample is added to a scintillation liquid and uniformly mixed with it. When plutonium particles pass through the scintillation liquid, their radiation energy is consumed through the ionization and excitation of solvent molecules. When the solvent molecules return to the ground state after excitation, they release energy to the scintillator. When the solute molecules of the scintillator return from the excited state to the ground state, the excess energy is emitted in the form of photons. These photons with the characteristic wavelength of the solute are then detected by the photocathode, and then the optical signal is converted into an electrical signal and preliminarily amplified. Based on the discrimination of the electrical signal, the energy value of the β-radioactive element in the sample can be determined; using a liquid scintillation spectrometer to measure the plutonium content can effectively lower the measurement lower limit and make the measurement range wider.

[0048] It should be noted that considering factors such as the radioactive level of the uranium sample, the dissolution of substances, the preparation of stock solutions, and the preparation of solutions in the embodiments of the present application all need to be carried out in a glove box with radiation shielding function, which meets the radiation protection requirements and can effectively ensure the safety of personnel. The method for measuring the plutonium content in the uranium sample of the present application improves the analysis speed and reduces the harm of personnel irradiated by radiation.

[0049] In an optional embodiment of the present invention, step 11 includes:

[0050] Step 111, for the uranium sample in the organic phase, perform deuterium-tritium removal treatment on the uranium sample through tributyl phosphate to obtain the uranium sample after deuterium-tritium removal; or

[0051] Step 112, for the uranium sample in the aqueous phase, perform deuterium-tritium removal treatment on the uranium sample through nitric acid to obtain the uranium sample after deuterium-tritium removal.

[0052] In this embodiment, the uranium sample is preferably a high-uranium sample, that is, the concentration of uranium in the uranium sample is a preset concentration value. Since the preset liquid scintillation spectrometer can measure the β-radioactive elements in the uranium sample, the low-energy β-radioactive substance tritium will affect the measurement of the plutonium content in the uranium sample by the preset liquid scintillation spectrometer in the subsequent process. Therefore, it is necessary to perform deuterium-tritium removal treatment on the uranium sample;

[0053] The uranium sample is divided into an organic phase and an aqueous phase according to the state of the substance. For the uranium sample in the organic phase, tributyl phosphate should be used to perform deuterium-tritium removal treatment on it, and for the uranium sample in the aqueous phase, nitric acid should be used to perform deuterium-tritium removal treatment on it.

[0054] In an optional embodiment of the present invention, step 111 includes:

[0055] Step 1111, take tributyl phosphate and add it to the uranium sample in the organic phase;

[0056] Step 1112, perform distillation and volume fixing treatment on the uranium sample in the organic phase added with the tributyl phosphate under normal pressure environment to obtain the uranium sample after deuterium-tritium removal.

[0057] In this embodiment, the uranium sample in the organic phase is placed in a beaker, tributyl phosphate (TBP) is added, and then the uranium sample in the organic phase added with tributyl phosphate is distilled under normal pressure. Specifically, it is evaporated to near dryness on a graphite electric hot plate, and then the bottom of the beaker evaporated to near dryness is rinsed with tributyl phosphate, and all the cleaning liquid is transferred to a volumetric flask for volume fixation to obtain the deuterium - tritium - removed uranium sample.

[0058] In a specific embodiment, for the deuterium - tritium removal treatment of the uranium sample in 0.1 mL to 0.5 mL of the organic phase, it can be placed in a beaker, 5 mL of TBP with a concentration of 30% is added, then the beaker is placed on a graphite electric hot plate and evaporated to near dryness, and then the bottom of the beaker is rinsed with 30% TBP, and finally all the cleaning liquid is transferred to a 10 - mL volumetric flask for volume fixation, thus completing the deuterium - tritium removal of the uranium sample in the organic phase.

[0059] In an alternative embodiment of the present invention, step 112 includes:

[0060] Step 1121, add nitric acid to the uranium sample in the aqueous phase;

[0061] Step 1122, distill and fix the volume of the uranium sample in the aqueous phase added with the nitric acid under normal pressure to obtain the deuterium - tritium - removed uranium sample.

[0062] In this embodiment, the uranium sample in the aqueous phase is placed in a beaker, nitric acid (HNO3) is added, and then the uranium sample in the aqueous phase added with nitric acid is distilled under normal pressure. Specifically, it is evaporated to near dryness on a graphite electric hot plate, and then the bottom of the beaker evaporated to near dryness is rinsed with nitric acid, and all the cleaning liquid is transferred to a volumetric flask for volume fixation to obtain the deuterium - tritium - removed uranium sample.

[0063] In another specific embodiment, for the deuterium - tritium removal treatment of the uranium sample in 0.1 mL to 0.5 mL of the aqueous phase, it can be placed in a beaker, 5 mL of HNO3 with a concentration of 0.1 mol / L to 0.5 mol / L is added, then the beaker is placed on a graphite electric hot plate and evaporated to near dryness, and then the bottom of the beaker is rinsed with 0.1 mol / L to 0.5 mol / L HNO3, and finally all the cleaning liquid is transferred to a 10 - mL volumetric flask for volume fixation, thus completing the deuterium - tritium removal of the uranium sample in the aqueous phase.

[0064] In an alternative embodiment of the present invention, when measuring the plutonium content of the processed uranium sample by a preset liquid scintillation spectrometer, the discrimination thresholds of the first preset radionuclide α and the second preset radionuclide β of the preset liquid scintillation spectrometer are 130 V to 160 V, the preset energy window is 0 keV to 21 keV, and the preset measurement time is 5 min.

[0065] In this embodiment, the instrument parameters of the preset liquid scintillation spectrometer are preset. The discrimination thresholds of the first preset radionuclide α and the second preset radionuclide β are set to 130V to 160V to minimize the miscount rate of the first preset radionuclide α and the second preset radionuclide β. Then, the preset energy window is set to 0keV to 21keV, and the preset measurement time is 5min. In addition, the volume of the scintillation liquid in the preset liquid scintillation spectrometer is set to 10mL. It should be noted that the discrimination threshold, preset energy window, preset measurement time, and scintillation liquid volume of the preset liquid scintillation spectrometer here are all preferred choices and can be adjusted adaptively according to the actual uranium sample. This application is not limited thereto.

[0066] In an alternative embodiment of the present invention, the preset standard solution curve in step 13 is determined according to the concentration and energy value of the plutonium standard stock solution, including:

[0067] Step 13a, obtaining a plutonium standard stock solution with a concentration of 0.1g / L;

[0068] Step 13b, based on the plutonium standard stock solution with a concentration of 0.1g / L, obtaining multiple plutonium standard stock solutions with different concentrations;

[0069] Step 13c, measuring the multiple plutonium standard stock solutions with different concentrations through a preset liquid scintillation spectrometer to obtain the energy values corresponding to the plutonium standard stock solutions with different concentrations;

[0070] Step 13d, drawing the preset standard solution curve according to the energy values corresponding to the plutonium standard stock solutions with different concentrations.

[0071] In this embodiment, by obtaining a plutonium standard stock solution with a concentration of 0.1g / L, and then determining multiple plutonium standard stock solutions with different concentrations based on the 0.1g / L plutonium standard stock solution. For example, when preparing a plutonium standard stock solution of 5×10 -2 g / L, 5.0mL of the 0.1g / L plutonium standard stock solution can be pipetted into a 10mL volumetric flask and made up to the mark with 1mol / L nitric acid solution to obtain a plutonium standard stock solution of 5×10 -2 g / L;

[0072] By measuring the plutonium standard stock solutions with different concentrations through a preset liquid scintillation spectrometer, the energy values corresponding to the plutonium standard stock solutions with different concentrations are obtained. Since these plutonium standard stock solutions with different concentrations are all standard solutions, the corresponding energy values are also standard values. Using the different concentrations of the plutonium standard stock solution as the ordinate and the corresponding energy values as the abscissa, the preset standard solution curve can be drawn. This preset standard solution curve can be used to determine the concentration of plutonium according to the energy value of plutonium in the uranium sample, greatly improving the analysis speed of measuring the plutonium content in the uranium sample and shortening the cumbersome measurement process.

[0073] In addition, since the preset standard solution curve is a reference curve in the subsequent measurement process of the plutonium content in the uranium sample, the data accuracy requirements for the concentration and energy value of each group of plutonium standard stock solutions in the preset standard solution curve are relatively high, and its linear correlation coefficient is not less than a preset value, which is preferably 0.999.

[0074] In an alternative embodiment of the present invention, step 13a includes:

[0075] Step 13a1, take 0.011 g of plutonium dioxide standard substance, add a mixed acid composed of nitric acid and hydrogen fluoride in a ratio of 275:2, and dissolve it under the temperature condition of 170°C to 200°C to obtain a dissolved solution;

[0076] Step 13a2, evaporate and cool the dissolved solution to obtain a process solution;

[0077] Step 13a4, make a constant volume of 100 mL of the process solution with 1 mol / L nitric acid to obtain a plutonium standard stock solution with a concentration of 0.1 g / L.

[0078] In this embodiment, the plutonium standard stock solution with a concentration of 0.1 g / L is prepared from a plutonium dioxide standard substance. Take 0.011 g of the plutonium dioxide standard substance and place it in a beaker, add 4 mL to 8 mL of the mixed acid, which is obtained by adding 11 mol / L nitric acid HNO3 and 0.08 moL / L hydrogen fluoride HF, and dissolve it under the temperature condition of 170°C to 200°C. After complete dissolution, a dark green and residue-free dissolved solution is obtained. Evaporate the dissolved solution to near dryness, and then perform a cooling treatment to obtain a process solution. Make a constant volume of the process solution to 100 mL in a volumetric flask with 1 mol / L nitric acid to obtain a plutonium standard stock solution with a concentration of 0.1 g / L.

[0079] In an alternative embodiment of the present invention, the method for measuring the plutonium content in a uranium sample further includes:

[0080] Step 14, determine the detection efficiency of the uranium sample on a preset liquid scintillation spectrometer according to the preset detection efficiency curve and the target concentration value of plutonium in the uranium sample, and the preset detection efficiency curve is determined according to the recovery rate of plutonium by a uranium matrix solution.

[0081] In this embodiment, in order to exclude the influence of the uranium matrix on the determination of the plutonium content, it is necessary to judge the detection efficiency of the preset liquid scintillation spectrometer. When the detection efficiency is higher than a preset detection efficiency, the target concentration value of plutonium is reliable, and the preset detection efficiency curve is determined according to the recovery rate of plutonium by a uranium matrix solution.

[0082] In an alternative embodiment of the present invention, step 14 includes:

[0083] Step 141: Based on a preset detection efficiency curve, determine the standard plutonium concentration value corresponding to the preset uranium concentration value in the uranium sample.

[0084] Step 142: According to the standard plutonium concentration value and the target plutonium concentration value in the uranium sample, determine the detection efficiency of the uranium sample on a preset liquid scintillation spectrometer.

[0085] In this embodiment, the preset detection efficiency curve is a reference curve with the uranium concentration of the uranium matrix solution as the abscissa and the standard plutonium concentration value as the ordinate. Based on this preset detection efficiency curve, according to the preset uranium concentration value, determine its corresponding standard plutonium concentration value, and then perform a deviation calculation between the standard plutonium concentration value and the target plutonium concentration value in the uranium sample, so as to determine the detection efficiency of the uranium sample on the preset liquid scintillation spectrometer. Compare this detection efficiency with the preset detection efficiency. When this detection efficiency is greater than the preset detection efficiency value, the influence of the uranium matrix on the determination of the plutonium content can be excluded.

[0086] In an optional embodiment of the present invention, the preset detection efficiency curve in Step 14 is obtained through the following process:

[0087] Step 14a: Add a preset amount of plutonium to uranium matrix solutions with multiple different uranium concentrations.

[0088] Step 14b: Measure the recovery rate of the preset amount of plutonium in the uranium matrix solutions with different uranium concentrations.

[0089] Step 14c: Draw a preset detection efficiency curve according to the recovery rate.

[0090] In this embodiment, add a preset amount of plutonium to uranium matrix solutions with multiple different uranium concentrations, measure the recovery rate of plutonium in the uranium matrix solutions with different uranium concentrations, and draw a preset detection efficiency curve with the uranium concentration of the uranium matrix solution as the abscissa and the recovery rate as the ordinate. Here, the recovery rate of plutonium can represent the standard plutonium concentration value under the uranium matrix solution with this uranium concentration.

[0091] In a specific embodiment, take 0.2 mL - 1 mL of a high-uranium sample with a uranium concentration of M in the high-uranium sample. Perform a deuterium-tritium removal treatment on the high-uranium sample to obtain 10 mL of the treated high-uranium sample. Measure the plutonium content of the treated high-uranium sample with a preset liquid scintillation spectrometer with set instrument parameters to obtain the energy value of plutonium. Among them, the instrument parameters of the preset liquid scintillation spectrometer are that the discrimination thresholds for the first preset radionuclide α and the second preset radionuclide β are 130 V to 160 V, the preset energy window is 0 keV to 21 keV, the preset measurement time is 5 min, and the volume of the scintillation liquid is 10 mL. According to the energy value of plutonium and the preset standard solution curve, determine the target plutonium concentration value in the uranium sample.

[0092] Among them, the preset standard solution curve is prepared by first preparing a 1 mol / L nitric acid solution, then weighing 0.011 g (error range ±0.1 mg) of plutonium dioxide standard substance into a beaker, adding 4 mL to 8 mL of mixed acid (11 mol / L nitric acid HNO3 added with 0.08 moL / L hydrogen fluoride HF), dissolving at a temperature of 170 °C to 200 °C. After complete dissolution, a dark green and residue-free solution is obtained. Evaporate this solution to near dryness and cool it, and make up the volume to 100 mL in a volumetric flask with the pre-prepared 1 mol / L nitric acid to obtain a plutonium standard stock solution with a concentration of 0.1 g / L;

[0093] Accurately pipette 5.0 mL of the 0.1 g / L plutonium standard stock solution into a 10 mL volumetric flask, and make up the volume to the scale line with a 1 mol / L nitric acid solution to obtain a plutonium standard stock solution of 5×10 -2 g / L; and so on. According to the method of stepwise dilution, plutonium standard stock solutions with the following concentrations are obtained: 5×10 -2 g / L, 1×10 -2 g / L, 5×10 -3 g / L, 5×10 -4 g / L, 5×10 -5 g / L, 1×10 -5 g / L, 5×10 -6 g / L, 1×10 -6 g / L;

[0094] Respectively pipette 50 μL of the plutonium standard stock solution into a low-potassium glass bottle containing 10 mL of scintillation solution, measure for 10 min with a preset liquid scintillation spectrometer. With the concentration of the plutonium standard stock solution as the abscissa, read the corresponding count of the preset liquid scintillation spectrometer within the energy range of 0 KeV to 21 keV as the energy value corresponding to the plutonium standard stock solution, and then plot the preset standard solution curve;

[0095] The data corresponding to this preset standard solution curve is as follows:

[0096] Serial number 1 2 3 4 5 6 7 8 Standard name Pu1 Pu2 Pu3 Pu4 Pu5 Pu6 Pu7 Pu8 Plutonium concentration (g / L) <![CDATA[5×10 -2 > <![CDATA[1×10 -2 > <![CDATA[5×10 -3 > <![CDATA[5×10 -4 > <![CDATA[5×10 -5 > <![CDATA[1×10 -5 > <![CDATA[5×10 -6 > <![CDATA[1×10 -6 >

[0097] Table 1

[0098] Based on the above 8 concentrations of plutonium standard stock solutions, with the concentration of the plutonium standard stock solution as the abscissa and the energy value corresponding to the plutonium standard stock solution as the ordinate, plot a preset standard solution curve with a linear correlation coefficient not less than 0.999;

[0099] The energy value of plutonium obtained by measuring a high-uranium sample with a preset liquid scintillation spectrometer can be used to find and determine the target concentration value of plutonium in the uranium sample corresponding to a preset standard solution curve. Further, the detection efficiency of the target concentration value of plutonium is judged to exclude the influence of the uranium matrix on the determination of the plutonium content. Specifically, according to the characteristics of the high-uranium sample, a preset amount of plutonium is added to a uranium matrix solution with a known uranium concentration, and the recovery rate of plutonium in uranium matrix solutions with different uranium concentrations is measured, obtaining the data shown in the following table:

[0100] Serial number 1 2 3 4 5 Uranium concentration (g / L) <![CDATA[1.0×10 -4 > <![CDATA[1.0×10 -3 > <![CDATA[1.0×10 -2 > <![CDATA[1.0×10 -1 > 1.0 Plutonium concentration (g / L) <![CDATA[5.0×10 -4 > <![CDATA[5.0×10 -4 > <![CDATA[5.0×10 -4 > <![CDATA[5.0×10 -4 > <![CDATA[5.0×10 -4 >

[0101] Table 2

[0102] According to Table 2, a preset detection efficiency curve of plutonium can be plotted. The preset detection efficiency curve is plotted with the uranium concentration of the uranium matrix solution as the abscissa and the standard plutonium concentration value under the uranium matrix solution as the ordinate;

[0103] According to the uranium concentration in the high-uranium sample, determine the corresponding standard plutonium concentration value in the preset detection efficiency curve, calculate the error between the standard plutonium concentration value and the target concentration value of plutonium, and use the error value as the detection efficiency. When the detection efficiency is above 95%, it indicates that the influence of the uranium matrix on the plutonium determination has been excluded for the target concentration value.

[0104] In the embodiment of the present invention, the collected uranium sample is subjected to tritium removal treatment to obtain a treated uranium sample; the uranium concentration in the uranium sample is a preset concentration value; the plutonium content of the treated uranium sample is measured by a preset liquid scintillation spectrometer to obtain the energy value of plutonium in the uranium sample; according to the energy value of plutonium and a preset standard solution curve, the target concentration value of plutonium in the uranium sample is determined; the preset standard solution curve is determined according to the concentration and energy value of a plutonium standard stock solution; the problems of long sample analysis time and large irradiation dose received by personnel during the plutonium determination process are solved. By pre-removing tritium from the uranium sample, the influence of the low-energy β radioactive substance tritium on the plutonium content measurement can be effectively removed, and the plutonium content measurement based on the preset standard solution curve can shorten the measurement time and effectively improve the analysis speed.

[0105] The above is the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for measuring the plutonium content in a uranium sample, characterized in that, Including: Performing tritium removal treatment on the collected uranium sample to obtain a treated uranium sample; The concentration of uranium in the uranium sample is a preset concentration value; Measuring the plutonium content of the treated uranium sample by a preset liquid scintillation spectrometer to obtain the energy value of plutonium in the uranium sample; Determining the target concentration value of plutonium in the uranium sample according to the energy value of the plutonium and a preset standard solution curve; The preset standard solution curve is determined according to the concentration and energy value of a plutonium standard stock solution.

2. The method for measuring the plutonium content in a uranium sample according to claim 1, characterized in that, Performing tritium removal treatment on the collected uranium sample to obtain a treated uranium sample, including: For the uranium sample in the organic phase, performing tritium removal treatment on the uranium sample with tributyl phosphate to obtain a tritium-removed uranium sample; or For the uranium sample in the aqueous phase, performing tritium removal treatment on the uranium sample with nitric acid to obtain a tritium-removed uranium sample.

3. The method for measuring the plutonium content in a uranium sample according to claim 2, characterized in that, For the uranium sample in the organic phase, performing tritium removal treatment on the uranium sample with tributyl phosphate to obtain a tritium-removed uranium sample, including: Taking tributyl phosphate and adding it to the uranium sample in the organic phase; Performing distillation and volume fixation treatment on the uranium sample in the organic phase added with the tributyl phosphate under an atmospheric pressure environment to obtain a tritium-removed uranium sample.

4. The method for measuring the plutonium content in a uranium sample according to claim 2, characterized in that, For the uranium sample in the aqueous phase, performing tritium removal treatment on the uranium sample with nitric acid to obtain a tritium-removed uranium sample, including: Taking nitric acid and adding it to the uranium sample in the aqueous phase; Performing distillation and volume fixation treatment on the uranium sample in the aqueous phase added with the nitric acid under an atmospheric pressure environment to obtain a tritium-removed uranium sample.

5. The method for measuring the plutonium content in a uranium sample according to claim 1, characterized in that, It also includes: Determining the detection efficiency of the uranium sample on the preset liquid scintillation spectrometer according to a preset detection efficiency curve and the target concentration value of plutonium in the uranium sample; Among them, calculating the error between the standard plutonium concentration value and the target concentration value of plutonium, and taking the error value as the detection efficiency.

6. The method for measuring the plutonium content in a uranium sample according to claim 5, characterized in that, Determining the detection efficiency of the uranium sample on the preset liquid scintillation spectrometer according to a preset detection efficiency curve and the target concentration value of plutonium in the uranium sample, including: Based on the preset detection efficiency curve, determining the standard plutonium concentration value corresponding to the preset concentration value of uranium in the uranium sample; Determining the detection efficiency of the uranium sample on the preset liquid scintillation spectrometer according to the standard plutonium concentration value and the target concentration value of plutonium in the uranium sample.

7. The method for measuring the plutonium content in a uranium sample according to claim 5, characterized in that, The preset detection efficiency curve is obtained through the following process: Adding a preset amount of plutonium to uranium matrix solutions with multiple different uranium concentrations; Measuring the standard plutonium concentration values of the preset amount of plutonium in the uranium matrix solutions with different uranium concentrations; Drawing a preset detection efficiency curve according to the standard plutonium concentration values corresponding to the uranium matrix solutions with different uranium concentrations.

8. The method for measuring the plutonium content in a uranium sample according to claim 1, characterized in that, When measuring the plutonium content of the treated uranium sample by a preset liquid scintillation spectrometer, the discrimination thresholds of the first preset radionuclide α and the second preset radionuclide β of the preset liquid scintillation spectrometer are 130V to 160V, the preset energy window is 0keV to 21keV, and the preset measurement time is 5 min.

9. The method for measuring the plutonium content in a uranium sample according to claim 1, wherein The preset standard solution curve is determined according to the concentration and energy value of a plutonium standard stock solution, including: Obtaining a plutonium standard stock solution with a concentration of 0.1 g / L; Based on the plutonium standard stock solution with a concentration of 0.1 g / L, obtaining multiple plutonium standard stock solutions with different concentrations; Measure the multiple plutonium standard stock solutions with different concentrations by a preset liquid scintillation spectrometer to obtain the energy values corresponding to the plutonium standard stock solutions with different concentrations; Draw the preset standard solution curve according to the energy values corresponding to the plutonium standard stock solutions with different concentrations.

10. The method for measuring the plutonium content in a uranium sample according to claim 9, characterized in that, Obtain a plutonium standard stock solution with a concentration of 0.1 g / L, including: Take 0.011 g of plutonium dioxide standard substance, add a mixed acid composed of nitric acid and hydrogen fluoride in a ratio of 275:2, and dissolve it under the temperature condition of 170°C to 200°C to obtain a dissolution solution; Perform evaporation and cooling treatment on the dissolution solution to obtain a process solution; Make a 100 mL constant volume of the process solution with 1 mol / L nitric acid to obtain a plutonium standard stock solution with a concentration of 0.1 g / L.

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