Method and system for detecting activity concentration of tritium in radioactive sludge

Abstract

The invention provides a method and a system for detecting tritium activity concentration in radioactive sludge, and relates to the technical field of spent fuel post-treatment analysis, and the method comprises the following steps: obtaining a tritium-containing sludge sample and background water; the method comprises the following steps: leaching a tritium-containing sludge sample by utilizing background water to obtain a leached sample solution; performing atmospheric distillation on the leached sample solution to obtain a to-be-detected sample solution, and mixing the to-be-detected sample solution with a scintillation solution to obtain a sample mixed solution; mixing the background water with the scintillation liquid to obtain a background mixed liquid; mixing the standard solution with the scintillation solution to obtain a standard mixed solution; obtaining a first counting rate of tritium in the sample mixed solution, a second counting rate of tritium in the background mixed solution and a third counting rate of tritium in the standard mixed solution; and determining the activity concentration of tritium in the sludge sample according to the first counting rate, the second counting rate and the third counting rate. The accuracy and repeatability of the detection result of the activity concentration of tritium in radioactive sludge can be ensured, and the detection efficiency of tritium in a sample is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of spent fuel reprocessing analysis, and particularly to a method and system for detecting the tritium activity concentration in radioactive sludge. Background Art

[0002] Tritium is an important radionuclide discharged by nuclear facilities into the environment. As a low-energy β-radionuclide, tritium has a relatively small external irradiation effect on the human body, but it can cause internal irradiation damage to the human body. Nuclear facilities use the natural evaporation pond technology to treat very low-level radioactive waste liquid, and the water in the evaporation pond is naturally evaporated by the energy of solar radiation to achieve the concentration treatment of the waste liquid. The bottom sludge in the natural evaporation pond is formed through various processes, including the settlement of suspended solids under the action of gravity, the decomposition of organic matter under the action of microorganisms, and the settlement of minerals under specific conditions. During the formation process of the bottom sludge, tritium in the tritium-containing wastewater is distributed in the radioactive sludge sample through the diffusion and penetration processes of water. Tritium mainly exists in the form of combined tritium, i.e., "tritiated water (HTO)", in the water mixed with sediment in the sludge. When tritiated water enters the human body, it will pose a threat to human health. Therefore, studying the distribution of tritiated water in the bottom sludge of natural evaporation ponds in nuclear facilities is crucial for studying the harm of tritium to humans and the further disposal of radioactive waste. The determination of tritium is often carried out using a liquid scintillation spectrometer. The measurement of tritium content in sludge generally requires pretreatment through a vacuum heating desorption device to collect the water in the sample. This pretreatment method requires special equipment, which is expensive, and it is time-consuming and laborious for personnel to handle, resulting in low detection efficiency. Summary of the Invention

[0003] The present invention provides a method and system for detecting the tritium activity concentration in radioactive sludge to solve the problems in the prior art that the determination of tritium requires special equipment, which is expensive, and it is time-consuming and laborious for personnel to handle, resulting in low detection efficiency.

[0004] To solve the above technical problems, the technical solution of the present invention is as follows:

[0005] A method for detecting the tritium activity concentration in radioactive sludge includes:

[0006] Obtaining a sludge sample containing tritium and background water;

[0007] Leaching the sludge sample containing tritium with the background water to obtain a leaching sample solution;

[0008] Obtaining a sample solution to be measured by subjecting the leaching sample solution to atmospheric distillation;

[0009] Mixing the sample solution to be measured with a scintillation solution to obtain a sample mixture; mixing the background water with the scintillation solution to obtain a background mixture; mixing a standard solution with the scintillation solution to obtain a standard mixture;

[0010] Obtain the first counting rate of tritium in the sample mixture, the second counting rate of tritium in the background mixture, and the third counting rate of tritium in the standard mixture;

[0011] Determine the activity concentration of tritium in the sludge sample according to the first counting rate, the second counting rate, and the third counting rate.

[0012] Optionally, obtaining background water includes:

[0013] Perform atmospheric distillation on the target water multiple times;

[0014] Collect the distillate from the last atmospheric distillation to obtain background water.

[0015] Optionally, leaching the sludge sample containing tritium with background water to obtain a leaching sample solution, including:

[0016] Weigh the sludge sample containing tritium to a constant weight and take samples to obtain laboratory samples;

[0017] Leach the laboratory samples with background water at least twice to obtain a leaching sample solution.

[0018] Optionally, leaching the laboratory samples with background water at least twice to obtain a leaching sample solution, including:

[0019] Leach the laboratory samples to obtain a primary leaching solution;

[0020] Filter the primary leaching solution by suction filtration to obtain a first filtrate and a filter residue;

[0021] Add the background water to the filter residue for leaching to obtain a secondary leaching solution;

[0022] Filter the secondary leaching solution by suction filtration to obtain a second filtrate;

[0023] Obtain the leaching sample solution according to the first filtrate and the second filtrate.

[0024] Optionally, obtaining the test sample solution by atmospheric distillation of the leaching sample solution, including:

[0025] Adjust the pH value of the leaching sample solution to neutral or weakly alkaline and make up the volume with the background water;

[0026] Place the volume-adjusted leaching sample solution into a distillation device equipped with potassium permanganate for atmospheric distillation to obtain the test sample solution.

[0027] Optionally, the standard solution is obtained through the following process:

[0028] Obtain a preset volume of the original standard solution containing tritium;

[0029] Dilute the original standard solution with the background water to obtain a standard solution, and the activity concentration of tritium in the standard solution is a preset value.

[0030] Optionally, obtaining the first counting rate of tritium in the sample mixture, the second counting rate of tritium in the background mixture, and the third counting rate of tritium in the standard mixture includes:

[0031] Detect the tritium in the sample mixture using a liquid scintillation spectrometer to obtain the first counting rate;

[0032] Detect the tritium in the background mixture using a liquid scintillation spectrometer to obtain the second counting rate;

[0033] Detect the tritium in the standard mixture using a liquid scintillation spectrometer to obtain the third counting rate.

[0034] Optionally, determining the activity concentration of tritium in the sludge sample according to the first counting rate, the second counting rate, and the third counting rate includes:

[0035]

[0036] Where C is the tritium activity concentration in the sludge sample, N c is the first counting rate, N0 is the second counting rate, A is the tritium activity concentration of the standard solution, V is the volume after the pH value of the leaching sample solution is adjusted to neutral or weakly alkaline and fixed volume with background water, N s is the third counting rate, V1 is the sampling volume of the sample solution to be measured, and m is the weighed amount of the sludge sample.

[0037] Optionally, the method for detecting the tritium activity concentration in radioactive sludge further includes:

[0038] Dry the sand and soil and then add the standard solution and mix evenly to obtain a simulated sample;

[0039] Use the Karl Fischer coulometric method to detect the uniformity of the water content distribution in the simulated sample, and at the same time calculate the water content in the simulated sample to obtain the theoretical value of the added amount of the standard solution;

[0040] Obtain the recovery rate through the theoretical value of the added amount of the standard solution and the tritium activity concentration in the simulated sample. The present invention also provides a detection system for the tritium activity concentration in radioactive sludge, including:

[0041] A background water preparation device for obtaining the prepared background water;

[0042] A sample mixture preparation device for leaching a sludge sample containing tritium with background water to obtain a leaching sample solution; obtaining a sample solution to be measured by subjecting the leaching sample solution to atmospheric distillation; mixing the sample solution to be measured with a scintillation solution to obtain a sample mixture;

[0043] A liquid scintillation spectrometer for obtaining a first counting rate of tritium in a sample mixture, a second counting rate of tritium in the background mixture, and a second counting rate of tritium in a standard mixture;

[0044] An upper computer for determining the activity concentration of tritium in a sludge sample according to the first counting rate, the second counting rate, and the third counting rate.

[0045] The above solution of the present invention has at least the following beneficial effects:

[0046] The above solution of the present invention includes: obtaining a sludge sample containing tritium and background water; leaching the sludge sample containing tritium with the background water to obtain a leached sample solution; subjecting the leached sample solution to atmospheric distillation to obtain a sample solution to be measured, mixing the sample solution to be measured with a scintillation solution to obtain a sample mixture, mixing the background water with the scintillation solution to obtain a background mixture, and mixing a standard solution with the scintillation solution to obtain a standard mixture; obtaining a first counting rate of tritium in the sample mixture, a second counting rate of tritium in the background mixture, and a third counting rate of tritium in the standard mixture; and determining the activity concentration of tritium in the sludge sample according to the first counting rate, the second counting rate, and the third counting rate. The solution of the present invention effectively dissolves and extracts tritium in radioactive sludge by using background water, can ensure the accuracy and repeatability of the detection result of the tritium activity concentration in radioactive sludge, reduces the occurrence of interference factors, realizes the accurate and rapid detection of the tritium concentration in a sample, and improves the detection efficiency of tritium in the sample. Description of the Drawings

[0047] Figure 1 is a flowchart of a method for detecting the activity concentration of tritium in radioactive sludge provided by an embodiment of the present invention;

[0048] Figure 2 is a process flowchart of a method for detecting the activity concentration of tritium in radioactive sludge provided by an embodiment of the present invention. Detailed Embodiments

[0049] Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to the drawings. Although the exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention 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 invention can be more thoroughly understood and the scope of the present invention can be fully conveyed to those skilled in the art.

[0050] As Figure 1 shown, an embodiment of the present invention provides a method for detecting the activity concentration of tritium in radioactive sludge, including:

[0051] Step 11, obtaining a sludge sample containing tritium and background water;

[0052] Step 12: Leach the sludge sample containing tritium with the background water to obtain a leaching sample solution.

[0053] Step 13: Obtain a sample solution to be measured by performing atmospheric distillation on the leaching sample solution.

[0054] Step 14: Mix the sample solution to be measured with a scintillation solution to obtain a sample mixture; mix the background water with the scintillation solution to obtain a background mixture; mix a standard solution with the scintillation solution to obtain a standard mixture.

[0055] Step 15: Obtain a first counting rate of tritium in the sample mixture, a second counting rate of tritium in the background mixture, and a third counting rate of tritium in the standard mixture.

[0056] Step 16: Determine the activity concentration of tritium in the sludge sample according to the first counting rate, the second counting rate, and the third counting rate.

[0057] In this embodiment, first, prepare the background water. Take 100 mL of deep well water or glacier water with less exchange with the outside world (the tritium counting rate is as low as possible) for atmospheric distillation, collect all the distillates, measure the tritium counting rate with a liquid scintillation spectrometer, distill the remaining distillates again, take the distillates for measurement, repeat the distillation operation three times and measure the tritium counting rate each time, and collect the distillates of the last time as the background water.

[0058] After leaching the obtained sludge sample containing tritium with the background water and performing atmospheric distillation, mix it with the scintillation solution to obtain a sample mixture, mix the background water with the scintillation solution to obtain a background mixture; mix a standard solution with the scintillation solution to obtain a standard mixture. Then, use a liquid scintillation spectrometer to measure the sample mixture to obtain a first counting rate; then, calculate the activity concentration of tritium in the sludge sample according to the first counting rate of tritium in the sample mixture, the second counting rate of tritium in the background mixture, and the third counting rate of tritium in the standard mixture.

[0059] The detection method for the tritium activity concentration in the radioactive sludge of this embodiment can effectively dissolve and extract tritium in the radioactive sludge by using the background water, ensure the accuracy and repeatability of the detection results of the tritium activity concentration in the radioactive sludge, reduce the occurrence of interference factors, achieve the accurate and rapid detection of the tritium concentration in the sample, and improve the detection efficiency of tritium in the sample.

[0060] In an alternative embodiment of the present invention, step 12 may include:

[0061] Step 121: Weigh and sample the sludge sample containing tritium to obtain a laboratory sample.

[0062] Step 122: Use the background water to extract the laboratory sample twice to obtain an extracted sample solution.

[0063] In this embodiment, the background water is used to extract the sludge sample containing tritium to obtain an extracted sample solution, which specifically includes the following steps:

[0064] Step a: Place the radioactive sludge sample in a transparent airtight glass bottle and keep it refrigerated at 20°C - 25°C in a refrigerator to reduce the loss of volatile substances.

[0065] Step b: Place the sludge sample in a thermostatic and humidostatic chamber for constant weight (temperature: 20°C - 25°C, humidity: 30% - 60%). After constant weight for 3 hours, take samples to control the water evaporation rate and achieve standardization and repeatability of constant weight determination.

[0066] Step c: Use the Karl Fischer coulometric method to detect the uniformity of the water content distribution in the sample after constant weight.

[0067] Step d: Take the sample after constant weight in a stable environment without ventilation. Take 80 g of the sample on a clean tray, preliminarily mix the sample, and use the quartering method to take samples. Accurately weigh 10 g of the sample.

[0068] Step e: Weigh 10 g of the sample into a sealed transparent container, and add 40 mL of background water to the container. Place the sealed transparent container containing the sample in an ultrasonic cleaner for ultrasonic operation for 10 minutes. Increase the dispersion by high-frequency vibration, accelerate the extraction process, and improve the extraction efficiency. After the ultrasonic operation, place the sample on a heating magnetic stirrer for extraction, stir at 70°C - 80°C for 1.5 h - 2 h to accelerate the diffusion process of tritiated water, maintain sufficient contact between the solid and liquid phases, make the extraction more complete, and have a higher yield. After heating, cool to room temperature for later use.

[0069] Step f: Take the soaked sample for suction filtration. Use a 0.45 μm polyethersulfone filter membrane for suction filtration operation during suction filtration, collect the filtrate in a ground glass bottle for later use. Scrape the sludge sample on the filter membrane and collect it into a sealed transparent container. Rinse the residual sludge on the filter membrane with 5 mL of background water, and incorporate the rinsing solution into the sealed transparent container.

[0070] Step g: Add 40 mL of background water to the sealed transparent container containing the filter residue, repeat Step e for secondary extraction, and collect the filtrate for later use by repeating Step f for the extraction solution. Discard the filter residue. Combine the two filtrates to obtain the extracted sample solution.

[0071] In an alternative embodiment of the present invention, Step 13 may include:

[0072] Step 131: Adjust the pH value of the extracted sample solution to neutral or weakly alkaline and make up the volume with the background water.

[0073] Step 132: Place the volume-fixed leaching sample solution into a distillation device containing potassium permanganate and perform atmospheric distillation to obtain the sample solution to be measured.

[0074] In this embodiment, use a pH test paper to measure the pH of the leaching sample solution, adjust the solution pH to neutral or weakly alkaline, transfer it to a 100 mL volumetric flask, and fix the volume with background water; transfer the volume-fixed leaching sample solution to a round-bottom flask, add 0.5 g of potassium permanganate, cover it with a ground glass stopper, install a snake-shaped condenser and start atmospheric distillation; start collecting from the appearance of the first drop of distillate, discard the first 40 mL of distillate, and collect all subsequent distillate in a ground glass bottle to obtain the sample solution to be measured.

[0075] In an alternative embodiment of the present invention, the standard solution is obtained through the following process:

[0076] Obtain a preset volume of the original standard solution containing tritium;

[0077] Dilute the original standard solution with the background water to obtain a standard solution, and the activity concentration of tritium in the standard solution is a preset value.

[0078] In this embodiment, before dilution of the original standard solution, the activity concentration of tritium in the solution is known, and then the original standard solution is diluted with the background water sample to dilute the activity concentration of tritium in the original standard solution to the preset value, thereby obtaining the standard solution.

[0079] In step 14, mix the sample solution to be measured with the scintillation liquid to obtain a sample mixture; specifically, take 2 mL of the distillate (sample solution to be measured) and mix it evenly with 15 mL of the scintillation liquid, and let it stand in the dark.

[0080] In an alternative embodiment of the present invention, step 15 may include:

[0081] Step 151: Detect tritium in the sample mixture using a liquid scintillation spectrometer to obtain the first counting rate N C ;

[0082] Step 152: Detect tritium in the background mixture using a liquid scintillation spectrometer to obtain the second counting rate N0;

[0083] Step 153: Detect tritium in the standard mixture using a liquid scintillation spectrometer to obtain the third counting rate N S .

[0084] In this embodiment, add 15 mL of the scintillation liquid to 2 mL of the background water and mix evenly, let it stand in the dark for 2.5 h after mixing to obtain the mixed background mixture (blank sample);

[0085] Take 2 mL of the standard solution, add 15 mL of the scintillation liquid and mix well. After mixing, let it stand in the dark for 2.5 h to obtain the mixed standard mixture (standard sample).

[0086] Place the standing sample to be measured, the background mixture and the standard mixture in a liquid scintillation spectrometer for measurement to obtain the first counting rate N of tritium in the sample mixture C , the second counting rate N0 of tritium in the background mixture, and the third counting rate N of tritium in the standard mixture S . The tritium result in the sludge sample is calculated by the relative measurement method.

[0087] In this embodiment, the measurement time of the liquid scintillation spectrometer can be set to 30 min and the number of measurements is 2 times.

[0088] In an alternative embodiment of the present invention, in step 16, through the formula:

[0089] Calculate the activity concentration of tritium in the sludge sample.

[0090] Where C is the activity concentration of tritium in the sludge sample, N c is the first counting rate, N0 is the second counting rate, A is the activity concentration of tritium in the standard solution, V is the volume after the pH value of the leached sample solution is adjusted to neutral or weakly alkaline and fixed volume with background water, N s is the third counting rate, V1 is the sampling volume of the sample to be measured, and m is the weighed amount of the sludge sample.

[0091] In an alternative embodiment of the present invention, the method for detecting the activity concentration of tritium in radioactive sludge further includes step 17:

[0092] Dry the sandy soil and then add the standard solution and mix well to obtain a simulated sample;

[0093] Use the Karl Fischer coulomb method to detect the homogeneity of the water content distribution in the simulated sample, and at the same time calculate the water content in the simulated sample to obtain the theoretical value of the added amount of the standard solution;

[0094] Obtain the recovery rate through the theoretical value of the added amount of the standard solution and the activity concentration of tritium in the simulated sample.

[0095] In this embodiment, prepare a simulated sample (tritium-containing soil sample) to determine the recovery rate of the method for detecting the activity concentration of tritium in radioactive sludge:

[0096] Step 171, take 200 g of sandy soil, dry it and then add 50 mL of the diluted standard solution, and stir well to obtain a simulated sample;

[0097] Step 172: Using the Karl Fischer coulometric method, take three samples of 0.1 g each to detect the uniformity of the water content distribution in the simulated sample, and at the same time obtain the water content in the simulated sample, that is, obtain the theoretical value c1 of the tritium activity concentration in the simulated sample.

[0098] Step 173: Detect the tritium activity concentration in the simulated sample through Steps 11 - 16 to obtain the measured value c2 of the tritium activity concentration in the sample.

[0099] Step 174: By comparing the theoretical value c1 and the measured value c2 of the tritium activity concentration in the simulated sample, the recovery rate of the detection method for the tritium activity concentration in the above radioactive sludge can be obtained.

[0100] In the above embodiments of the present invention, the tritium in the tritium - containing wastewater is distributed in the radioactive sludge sample due to the diffusion and penetration of water. For the analysis of the tritium activity concentration in the radioactive sludge, the tritium in the tritium water is dissolved with the background water and desorbed into the background water. Therefore, by selecting the pretreatment process of soaking the radioactive sludge sample with the background water, all the tritium in the sludge can be accurately and efficiently transferred and replaced. After collecting the replaced solution and performing atmospheric distillation, and then measuring it with a liquid scintillation spectrometer, the tritium content in the sludge sample can be obtained, that is, the detection of the tritium activity concentration in the radioactive sludge is realized.

[0101] In the above embodiments of the present invention, using the background water to effectively dissolve and extract the tritium in the radioactive sludge can ensure the accuracy and repeatability of the detection results of the tritium activity concentration in the radioactive sludge, reduce the occurrence of interference factors, realize the accurate and rapid detection of the tritium concentration in the sample, improve the detection efficiency of tritium in the sample, and this treatment method is simple, fast, and low - cost. By controlling the leaching conditions, the accuracy and repeatability of the detection results of the tritium activity concentration in the radioactive sludge can be ensured. It can not only detect the tritium activity concentration in the radioactive sludge, but also be applicable to other types of sludge samples, having wide applicability.

[0102] The embodiments of the present invention also provide a detection system for the tritium activity concentration in radioactive sludge, including:

[0103] A background water preparation device for obtaining and preparing background water;

[0104] A sample mixture preparation device for leaching a sludge sample containing tritium with background water to obtain a leached sample solution; obtaining a sample solution to be measured by subjecting the leached sample solution to atmospheric distillation; and mixing the sample solution to be measured with a liquid scintillation solution to obtain a sample mixture.

[0105] A liquid scintillation spectrometer for obtaining the first counting rate of tritium in the sample mixture, the second counting rate of tritium in the background mixture, and the second counting rate of tritium in the standard mixture.

[0106] The host computer is used to determine the activity concentration of tritium in the sludge sample according to the first counting rate, the second counting rate, and the third counting rate.

[0107] In an optional embodiment of the present invention, when the sample mixture preparation device uses background water to leach the sludge sample containing tritium to obtain the leached sample solution, specifically, it is used to weigh the sludge sample containing tritium to a constant weight, take samples to obtain laboratory samples; use background water to leach the laboratory samples twice to obtain the leached sample solution.

[0108] In the above embodiment, the system includes four main parts: a background water preparation device, a sample mixture preparation device, a liquid scintillation spectrometer, and a host computer. The background water preparation device is used to prepare background water. Deep well water or glacier water with less exchange with the outside world is subjected to atmospheric distillation, and all distillates are collected. The tritium counting rate is measured by a liquid scintillation spectrometer. The remaining distillate is distilled again, and the distillate is taken for measurement. The distillation operation is repeated three times and the tritium counting rate is measured each time. The distillate collected last is the background water. The background water is used to reduce background interference and serve as a blank control for subsequent sample processing and background value deduction.

[0109] The sample mixture preparation device is used to leach the sludge sample containing tritium with background water to obtain the leached sample solution; obtain the sample solution to be measured by atmospheric distillation of the leached sample solution; mix the sample solution to be measured with the scintillation solution to obtain the sample mixture; mix the background water with the scintillation solution to obtain the background mixture (blank sample); mix the standard solution with the scintillation solution to obtain the standard mixture (standard sample).

[0110] The liquid scintillation spectrometer is used to measure the β-radioactivity counting rate of tritium in the sample;

[0111] The host computer is a data processing system that calculates the activity concentration of tritium in the sludge based on the data of the liquid scintillation spectrometer, through the formula: Calculate the activity concentration of tritium in the sludge sample.

[0112] It should be noted that all the implementation methods in the above method are applicable to the embodiments of this system and can achieve the same technical effects.

[0113] As Figure 2 shown, in specific implementation, the system realizes the detection process of the tritium activity concentration in the radioactive sludge sample through the pretreatment of leaching with background water. It includes:

[0114] (1) Preparation of background water: Take 100 mL of deep well water or glacier water with less exchange with the outside world (the tritium counting rate is as low as possible) for atmospheric distillation, collect all distillates, measure the tritium counting rate by a liquid scintillation spectrometer, distill the remaining distillate again, take the distillate for measurement, repeat the distillation operation three times and measure the tritium counting rate each time, and collect the distillate collected last as the background water.

[0115] (2) Sample pretreatment:

[0116] a. Sample preservation: The received radioactive sludge samples are placed in transparent airtight glass bottles and stored refrigerated at 20°C - 25°C in a refrigerator to reduce the loss of volatile substances.

[0117] b. Sample constant weight: The sludge samples are placed in a thermostatic and humidistatic chamber for constant weight determination (temperature: 20°C - 25°C, humidity: 30% - 60%). After constant weight for 3 h, sampling is carried out to control the water evaporation rate and achieve standardization and repeatability of constant weight determination.

[0118] c. The homogeneity of the water content distribution in the samples after constant weight is detected by the Karl Fischer coulometric method.

[0119] d. Sample sampling: Take the samples after constant weight in a stable environment without ventilation. Take 80 g of the sample on a clean tray, preliminarily mix the sample, and sample by the quartering method. Accurately weigh 10 g of the sample.

[0120] (3) Preparation of samples to be measured:

[0121] a. Sample extraction: Weigh 10 g of the sample into a closed transparent container and add 40 mL of background water to the container. Place the closed transparent container containing the sample in an ultrasonic cleaner for ultrasonic operation for 10 min. Increase the dispersion by high-frequency vibration, accelerate the extraction process, and improve the extraction efficiency. After ultrasonic treatment, place the sample on a heating magnetic stirrer for extraction, stir at 70°C - 80°C for 1.5 h - 2 h to accelerate the diffusion process of tritiated water, maintain sufficient contact between the solid and liquid phases, make the extraction more complete, and have a higher yield. After heating, cool to room temperature for use.

[0122] b. Collection of extraction solution: Take the soaked sample for suction filtration. During suction filtration, use a 0.45 μm polyethersulfone filter membrane for suction filtration operation, collect the filtrate in a ground glass bottle for use. Scrape the sludge sample on the filter membrane and collect it into a closed transparent container. Rinse the residual sludge on the filter membrane with 5 mL of background water, and incorporate the rinsing solution into the closed transparent container.

[0123] c. Secondary extraction and collection of extraction solution: Add 40 mL of background water to the closed transparent container containing the filter residue, repeat operation a for secondary extraction, and repeat operation b for the extraction solution to collect the filtrate for use, and discard the filter residue. Combine the two filtrates for use.

[0124] d. Adjust the pH of the extraction solution: Measure the pH of the leaching solution with pH test paper, adjust the pH of the solution to neutral or weakly alkaline, then transfer it to a 100 mL volumetric flask and make up the volume with background water.

[0125] e. Distillation of the sample to be tested: The leachate after constant volume was transferred to a round-bottom flask, 0.5 g of potassium permanganate was added, the ground glass stopper was covered, the serpentine condenser was installed and atmospheric distillation was started; the first drop of distillate was collected, the first 40 mL of distillate was discarded, and all subsequent distillates were collected in a ground glass bottle;

[0126] f. Take 2mL of distillate and mix with 15mL of scintillation fluid as the test solution, mix well and let stand in the dark for 2.5h before use;

[0127] (4) Place blank samples and standard samples in a liquid scintillation spectrometer for measurement and record the measurement results;

[0128] (5) After standing still, the sample to be tested is placed in a liquid scintillation spectrometer for measurement, and the measurement results are recorded. The tritium result in the sludge sample is calculated by the relative measurement method;

[0129] (6) The calculation formula for tritium activity concentration in sludge samples is as follows:

[0130]

[0131] Where C is the tritium activity concentration in the sludge sample, N c is the first counting rate, N0 is the second counting rate, A is the tritium activity concentration of the standard solution, V is the volume of the leached sample solution after the pH value is adjusted to neutral or weakly alkaline and the volume is constant with background water, N s is the third counting rate, V1 is the sampling volume of the sample liquid to be tested, and m is the weighing weight of the sludge sample.

[0132] (7) Determination of the recovery rate of the tritium activity concentration detection method using simulated samples:

[0133] a. Take 200g of sand and dry it, add 50mL of the diluted standard solution, stir well and obtain a simulated sample;

[0134] b. Using the Karl Fischer Coulometry method, 0.1 g of water was sampled three times to test the uniformity of the water content distribution in the simulated sample. The water content in the simulated sample was obtained at the same time, and the theoretical value of tritium activity concentration c1 in the simulated sample was obtained;

[0135] c. Detecting the tritium activity concentration in the simulated sample by steps 11-16 to obtain a measured value c2 of the tritium activity concentration in the sample;

[0136] d. The recovery rate of this method can be obtained by comparing the theoretical value c1 of the tritium activity concentration in the simulated sample with the measured value c2.

[0137] For the analysis of the tritium activity concentration in radioactive sludge by the system of the present invention, the tritium in the tritiated water is dissolved with background water and desorbed into the background water. Therefore, by selecting the pretreatment process of soaking the radioactive sludge sample with background water, all the tritium in the sludge can be accurately and efficiently transferred and replaced. After collecting the replaced solution and performing atmospheric distillation, and then measuring it with a liquid scintillation spectrometer, the tritium content in the sludge sample can be obtained, that is, the detection of the tritium activity concentration in the radioactive sludge is realized.

[0138] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle described in the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for detecting the tritium activity concentration in radioactive sludge, characterized in that, Comprising: Obtaining a sludge sample containing tritium and background water; Leaching the sludge sample containing tritium with the background water to obtain a leached sample solution; Obtaining a sample solution to be measured by subjecting the leached sample solution to atmospheric distillation; Mixing the sample solution to be measured with a scintillation solution to obtain a sample mixture; Mixing the background water with a scintillation solution to obtain a background mixture; Mixing a standard solution with a scintillation solution to obtain a standard mixture; Obtaining a first counting rate of tritium in the sample mixture, a second counting rate of tritium in the background mixture, and a third counting rate of tritium in the standard mixture; Determining the activity concentration of tritium in the sludge sample according to the first counting rate, the second counting rate, and the third counting rate.

2. The detection method of the tritium activity concentration in radioactive sludge according to claim 1, wherein, Obtaining background water, comprising: Performing atmospheric distillation on the target water multiple times; Collecting the distillate of the last atmospheric distillation to obtain background water.

3. The detection method of tritium activity concentration in radioactive sludge according to claim 1, characterized in that, Leaching the sludge sample containing tritium with the background water to obtain a leached sample solution, comprising: Performing constant weighing and sampling on the sludge sample containing tritium to obtain a laboratory sample; Leaching the laboratory sample with the background water at least twice to obtain a leached sample solution.

4. The method for detecting the tritium activity concentration in radioactive sludge according to claim 3, characterized in that, Leaching the laboratory sample with the background water at least twice to obtain a leached sample solution, comprising: Leaching the laboratory sample to obtain a primary leaching solution; Performing suction filtration on the primary leaching solution to obtain a first filtrate and a filter residue; Adding the background water to the filter residue for leaching to obtain a secondary leaching solution; Performing suction filtration on the secondary leaching solution to obtain a second filtrate; Obtaining a leached sample solution according to the first filtrate and the second filtrate.

5. The detection method of the tritium activity concentration in radioactive sludge according to claim 1, wherein, Obtaining a sample solution to be measured by subjecting the leached sample solution to atmospheric distillation, comprising: Adjusting the pH value of the leached sample solution to neutral or weakly alkaline and making up the volume with the background water; Placing the leached sample solution with adjusted volume into a distillation device containing potassium permanganate for atmospheric distillation to obtain a sample solution to be measured.

6. The detection method of the tritium activity concentration in radioactive sludge according to claim 1, characterized in that The standard solution is obtained through the following process: Obtaining a preset volume of a primary standard solution containing tritium; Diluting the primary standard solution with the background water to obtain a standard solution, and the activity concentration of tritium in the standard solution is a preset value.

7. The detection method for the tritium activity concentration in radioactive sludge according to claim 1, wherein Obtaining a first counting rate of tritium in the sample mixture, a second counting rate of tritium in the background mixture, and a third counting rate of tritium in the standard mixture, comprising: Detecting tritium in the sample mixture with a liquid scintillation spectrometer to obtain a first counting rate; Detecting tritium in the background mixture with a liquid scintillation spectrometer to obtain a second counting rate; Detecting tritium in the standard mixture with a liquid scintillation spectrometer to obtain a third counting rate.

8. The detection method of the tritium activity concentration in radioactive sludge according to claim 1, characterized in that, Determining the activity concentration of tritium in the sludge sample according to the first counting rate, the second counting rate, and the third counting rate, comprising: Where C is the tritium activity concentration in the sludge sample, N c is the first counting rate, N0 is the second counting rate, A is the tritium activity concentration of the standard solution, V is the volume after the pH value of the leached sample solution is adjusted to neutral or weakly alkaline and fixed volume with background water, N s is the third counting rate, V1 is the sampling volume of the sample solution to be measured, and m is the weighed amount of the sludge sample.

9. The detection method for the tritium activity concentration in radioactive sludge according to claim 1, characterized in that Further comprising: Drying the sand and soil and adding the standard solution thereto and mixing evenly to obtain a simulated sample; Detecting the homogeneity of the water content distribution in the simulated sample by the Karl Fischer coulometric method, and simultaneously calculating the water content in the simulated sample to obtain a theoretical value of the added amount of the standard solution; Obtaining a recovery rate through the theoretical value of the added amount of the standard solution and the activity concentration of tritium in the simulated sample.

10. A detection system for the tritium activity concentration in radioactive sludge, characterized in that, Comprising: A background water preparation device for obtaining and preparing background water; A sample mixture preparation device is used to leach a sludge sample containing tritium with background water to obtain a leached sample solution; The leached sample solution is obtained by atmospheric distillation to get a sample solution to be measured; the sample to be measured is mixed with a scintillation solution to obtain a sample mixture; A liquid scintillation spectrometer is used to obtain a first counting rate of tritium in the sample mixture, a second counting rate of tritium in the background mixture, and a second counting rate of tritium in the standard mixture; A host computer is used to determine the activity concentration of tritium in the sludge sample according to the first counting rate, the second counting rate, and the third counting rate.

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