Rapid on-board analysis method and on-board mobile measurement system for radioactive cesium in seawater

Abstract

The present invention relates to a rapid onboard analysis method for radioactive cesium in seawater and an onboard mobile measurement system. Specifically, the present invention comprises: (1) a step of filtering seawater collected from a ship, adding it to a chamber, and adjusting the pH to 1.0 to 2.0; (2) a step of adding stable cesium (Cs) to the pH-adjusted seawater and stirring; (3) a step of adding a cesium adsorption resin to the seawater and stirring to adsorb cesium onto the resin; (4) a step of precipitating the resin on which cesium is adsorbed; and (5) a step of filtering the precipitated resin on which cesium is adsorbed, transferring it to a dish, and drying it. The present invention relates to a method for rapid onboard analysis of radioactive cesium in seawater comprising the step of (6) analyzing radioactive cesium adsorbed on resin using a gamma radionuclide spectrometer, and furthermore, the present invention relates to a mobile onboard measurement system for analyzing radioactive cesium in seawater at the site, comprising a mobile radioactive onboard experimental space isolated from the outside on board and a mobile radioactive onboard measurement unit isolated from the outside on board.

Description

Technology Field

[0001] The present invention relates to a rapid onboard analysis method for radioactive cesium in seawater and an onboard mobile measurement system. Background Technology

[0002] Since the Fukushima nuclear accident, many countries have been focusing on developing methods and systems to analyze underwater radioactive materials while monitoring the inflow of contaminated water into their territories. Radiation detectors are generally based on NaI(Tl) scintillators, and underwater radiation measurement systems are mostly operated by fixing detectors to buoys and harbor breakwater structures.

[0003] As public anxiety intensifies following the recent decision to discharge contaminated water from the Fukushima nuclear power plant, the importance of real-time monitoring of domestic marine environmental contamination is emerging, and there are currently many obstacles to determining the extent of radioactive contamination in seawater. In particular 137 For the analysis of radionuclides including Cs nuclides, it takes a considerable amount of time to collect samples from seawater, move and transport them to a research vessel for analysis, and 137 In the case of Cs radionuclide analysis, there is a problem that it takes a long time, about two months.

[0004] In the case of such conventional technologies, not only are separate facilities and equipment required to move and transport samples of radionuclides to the analysis site, but there are also concerns regarding the leakage of radionuclides; therefore, there is a need to develop a new analysis system that can analyze radionuclides in seawater more quickly and conveniently. Prior art literature

[0005] Republic of Korea Published Patent 10-2023-0021798 The problem to be solved

[0006] Accordingly, the inventors of the present invention completed the invention by developing a rapid analysis method capable of analyzing radioactive cesium in seawater within 24 hours and a mobile field measurement system that can be mounted on a ship.

[0007] Accordingly, the objective of the present invention is to provide a method for rapid onboard analysis of radioactive cesium in seawater, comprising the steps of: (1) filtering seawater collected from a ship, adding it to a chamber, and adjusting the pH to 1.0 to 2.0; (2) adding stable cesium (Cs) to the pH-adjusted seawater and stirring; (3) adding a cesium adsorption resin to the seawater and stirring to adsorb cesium onto the resin; (4) precipitating the resin on which cesium is adsorbed; (5) filtering the precipitated resin on which cesium is adsorbed, transferring it to a dish, and drying it; and (6) analyzing the radioactive cesium adsorbed onto the resin using a gamma radionuclide spectrometer.

[0008] Another objective of the present invention is to provide a mobile onboard measurement system for analyzing radioactive cesium in seawater at the site, comprising a mobile onboard radioactivity experimental space isolated from the outside on board and a mobile onboard radioactivity measurement unit isolated from the outside on board. means of solving the problem

[0009] To achieve the above-mentioned objective of the present invention, the present invention provides a method for rapid onboard analysis of radioactive cesium in seawater, comprising: (1) a step of filtering seawater collected from a ship, adding it to a chamber, and adjusting the pH to 1.0 to 2.0; (2) a step of adding stable cesium (Cs) to the pH-adjusted seawater and stirring; (3) a step of adding a cesium adsorption resin to the seawater and stirring to adsorb cesium onto the resin; (4) a step of precipitating the resin on which cesium is adsorbed; (5) a step of filtering the precipitated resin on which cesium is adsorbed, transferring it to a dish, and drying it; and (6) a step of analyzing the radioactive cesium adsorbed onto the resin using a gamma radionuclide spectrometer.

[0010] In one embodiment of the present invention, after step (6), the method may further include: (7) a step of deriving a result of primary field analysis by applying the cesium recovery rate value obtained by performing the process of (1) to (6) three or more times in a land laboratory in advance to the measured concentration of radioactive cesium; and (8) a step of deriving the concentration of radioactive cesium in the final seawater using the cesium recovery rate value obtained from the supernatant obtained after precipitating the resin on which cesium was adsorbed in step (4).

[0011] In one embodiment of the present invention, in step (2), stable cesium (Cs) is added in an amount of 10 to 20 mg per 100 L of collected seawater, and the stirring may be performed by stirring in both directions for 10 to 20 minutes at a time for 1 to 2 hours.

[0012] In one embodiment of the present invention, the resin for cesium adsorption in step (3) may be a KNiFC-PAN resin in which potassium-nickel hexacyanoferrate II polyacrylonitrile (KNiFC) and polyacrylonitrile (PAN) which is an organic support are combined.

[0013] In one embodiment of the present invention, in step (3), the cesium adsorption resin may be added in an amount of 20 to 30 g per 100 L of collected seawater.

[0014] In one embodiment of the present invention, in step (3), stirring may be performed in both directions for 3 hours at 10-minute intervals.

[0015] In one embodiment of the present invention, the radioactive cesium 137 It could be Cs.

[0016] In one embodiment of the present invention, the method may be performed within 24 hours on a mobile measuring system provided on board.

[0017] In one embodiment of the present invention, the mobile measurement system is composed of a mobile radioactivity onboard experimental space and a mobile radioactivity onboard measurement unit isolated from the outside on board, wherein the experimental space performs a seawater pretreatment process for radioactive cesium analysis, and the onboard measurement unit performs radioactive cesium analysis using a gamma radionuclide spectrometer.

[0018] In addition, the present invention provides a mobile onboard measurement system for analyzing radioactive cesium in seawater at the site, comprising: a mobile radioactivity onboard experimental space isolated from the outside on board; and a mobile radioactivity onboard measurement unit isolated from the outside on board.

[0019] In one embodiment of the present invention, the mobile radioactive shipboard experimental space may be composed of a space for pre-treating seawater collected from a ship, a chamber section for adding collected seawater to adjust the pH and adding resin, and then performing a stirring process; a filtration section for filtering the resin adsorbed with cesium; and a drying section for drying the filtered resin.

[0020] In one embodiment of the present invention, the mobile radioactivity line measurement unit may be composed of: a detection unit equipped with a gamma nuclide spectrometer capable of detecting radioactive cesium; and an analysis unit that analyzes and converts the detected radioactive cesium into data. Effects of the invention

[0021] The onboard mobile measurement system for analyzing radioactive cesium in seawater and the onboard rapid analysis method for radioactive cesium in seawater provided in this invention are characterized by the ability to perform rapid on-site analysis compared to existing methods for monitoring marine radioactive materials; therefore, they have the advantage of enabling the immediate execution of the entire process, from sample collection to verification of analysis results, in areas where marine radioactive contamination is a concern. Brief explanation of the drawing

[0022] Figure 1 is a schematic diagram showing the process of a rapid onboard analysis method for radioactive cesium in seawater according to the present invention. Figure 2 is a photograph showing the process of the onboard rapid analysis method of radioactive cesium in seawater according to the present invention, and the bottom shows the chamber used in the present invention. Figures 3 and 4 show the results of analyzing the recovery rate of radioactive cesium according to the amount of resin added in the onboard rapid analysis method of radioactive cesium in seawater according to the present invention. Figure 5 shows the results of analyzing the radioactive cesium recovery rate according to the stirring method after resin addition in the onboard rapid analysis method of radioactive cesium in seawater according to the present invention. Figure 6 shows the results of analyzing the radioactive cesium recovery rate according to the stirring time after adding resin in the onboard rapid analysis method of radioactive cesium in seawater according to the present invention. FIG. 7 compares and analyzes the recovery rate of radioactive cesium in seawater using a method utilizing a mobile onboard field measurement system according to the present invention and a conventional method of transporting samples to a land-based laboratory for analysis, wherein A in situ represents the concentration of radioactive Cs in seawater calculated from the average Cs recovery rate of this method obtained prior to conducting the investigation at the investigation site, and AR represents the concentration of radioactive Cs calculated by correcting from the Cs recovery rate measured per sample on land. Figure 8 shows the results of comparing the concentrations of radioactive cesium analyzed in seawater at the site and the recovery rate on land using the onboard mobile field measurement system according to the present invention. Figure 9 is a photograph showing the appearance of a mobile onboard field measurement system according to the present invention. FIG. 10 shows a plan view of a measurement room (equipment room) container in a mobile onboard field measurement system according to the present invention. FIG. 11 shows a plan view of a wet lab container in a mobile onboard field measurement system according to the present invention. Specific details for implementing the invention

[0023] The present invention is characterized by providing a rapid onboard analysis method for radioactive cesium in seawater and an onboard mobile measurement system.

[0024] Conventional analysis of radioactive materials in seawater required a significant amount of time—at least two months—to transport collected seawater to a laboratory on land, pre-process the sample, and obtain analysis results, and there were problems requiring separate equipment for transport to the land laboratory.

[0025] Accordingly, the present invention provides a new method to solve these conventional problems, and is characterized by providing a method and a mobile onboard measurement system capable of rapidly analyzing radioactive cesium in seawater at the site, that is, on board.

[0026] The method for rapid onboard analysis of radioactive cesium in seawater provided by the present invention preferably comprises: (1) a step of filtering seawater collected from a ship, adding it to a chamber, and adjusting the pH to 1.0 to 2.0; (2) a step of adding stable cesium (Cs) to the pH-adjusted seawater and stirring; (3) a step of adding a cesium adsorption resin to the seawater and stirring to adsorb cesium onto the resin; (4) a step of precipitating the resin on which cesium is adsorbed; (5) a step of filtering the precipitated resin on which cesium is adsorbed, transferring it to a dish, and drying it; and (6) a step of analyzing the radioactive cesium adsorbed onto the resin using a gamma radionuclide spectrometer.

[0027] Additionally, after step (6) above, the cesium recovery rate obtained by performing the process of (1) to (6) above three or more times in a land laboratory is applied to the measured concentration of radioactive cesium (7) to derive the results of the first field analysis, and then (8) the concentration of radioactive cesium in the final seawater can be derived using the cesium recovery rate obtained from the supernatant obtained after precipitating the resin on which cesium was adsorbed in step (4).

[0028] The method for rapid onboard analysis of radioactive cesium in seawater according to the present invention can be performed on a mobile onboard measuring system provided on board, and the mobile onboard measuring system according to the present invention is configured as a space capable of rapidly analyzing radioactive cesium from seawater collected on board.

[0029] Specifically, the onboard mobile measurement system for analyzing radioactive cesium in seawater at the site consists of a mobile radioactivity onboard experimental space isolated from the outside on board; and a mobile radioactivity onboard measurement unit isolated from the outside on board.

[0030] The above-mentioned mobile radioactivity shipboard experimental space is a space for pre-treating seawater collected from a ship, and is composed of a chamber section that performs a stirring process after adding the collected seawater to adjust the pH and adding resin; a filtration section that filters the resin adsorbed with cesium; and a drying section that dries the filtered resin.

[0031] The above-described mobile radiation line measurement unit comprises: a detection unit equipped with a gamma nuclide spectrometer capable of detecting radioactive cesium; and an analysis unit that analyzes and converts the detected radioactive cesium into data.

[0032] Due to the analysis performed using the aforementioned onboard mobile measurement system equipped on board, the inconvenience of transporting collected seawater to land, the time required for analysis, and the need for separate equipment for transport are eliminated.

[0033] In addition, two gamma detectors capable of detecting radioactive cesium, i.e., gamma radionuclide spectrometers, may be provided. They are positioned in the side space to minimize the influence of the ship's inclination and the imbalance caused by the weight of the equipment (each weighing 2 tons) when used on board. The two gamma detectors (GEM100-ICS-ES; Ortec) have identical performance and serve to measure gamma rays from radionuclides in the sample. The installed gamma detectors have a measurement efficiency (>100%) that is approximately twice that of the widely used gamma detector (GC5019; Canberra), so they not only have excellent performance but also have the convenient advantage of not requiring periodic liquid nitrogen supply through an electric cooling system.

[0034] Meanwhile, the inventors have established optimal analysis conditions for rapidly analyzing radioactive cesium in seawater in a shipboard mobile measuring system according to the present invention, which is equipped on board.

[0035] A specific method for rapid onboard analysis of radioactive cesium in seawater according to the present invention is described as follows.

[0036] First, (1) seawater collected from the ship is filtered, then added to the chamber and the pH is adjusted to 1.0 to 2.0.

[0037] The reason for adjusting the pH to 1.0 to 2.0 as described above is that the influence of biological activity present in seawater can be eliminated by adjusting the pH of the seawater, and the pH is adjusted to 1.0 to 2.0 as described above to suppress the adsorption of unnecessary organic matter on the resin.

[0038] In one embodiment of the present invention, the pH was adjusted to 1.0.

[0039] Once pH adjustment is complete, the next step involves adding stable cesium (stable Cs) to the pH-adjusted seawater and stirring. The addition of stable cesium was used as an internal standard for the chemical recovery rate.

[0040] In addition, the above stable cesium (stable Cs) can be added in an amount of 10 to 20 mg per 100 L of collected seawater, and the stirring is performed by stirring in both directions for 10 to 20 minutes at a time for 1 to 2 hours to achieve equilibrium with the radioactive cesium present in the seawater.

[0041] In one embodiment of the present invention, 10 mg of stable cesium (Cs) was added per 100 L of collected seawater and stirred in both directions for 10 minutes at a time for 1 hour.

[0042] Afterwards, (3) a cesium adsorption resin is added to the seawater and stirred to adsorb cesium onto the resin.

[0043] At this time, the resin used is a KNiFC-PAN resin in which potassium-nickel hexacyanoferrate II (KNiFC) and polyacrylonitrile (PAN), an organic support, are combined.

[0044] In one embodiment of the present invention, an experiment was conducted to determine whether the recovery rate of radioactive cesium is affected by the type of resin. Specifically, the recovery rate of radioactive cesium in seawater was analyzed using the same method with KNiFC-PAN resin and AMP-PAN resin. As a result, it was found that the recovery rate was at least 1.2 times higher when KNiFC-PAN resin was used compared to when AMP-PAN resin was used.

[0045] These results confirmed that the use of KNiFC-PAN resin is desirable for effectively recovering and analyzing radioactive cesium.

[0046] In addition, the above cesium adsorption resin can be added in an amount of 20 to 30 g per 100 L of collected seawater, and preferably in an amount of 25 g.

[0047] In one embodiment of the present invention, in order to determine the most effective optimal resin usage amount, the recovery rate of radioactive cesium was analyzed for different resin usage amounts based on 100L of collected seawater. It was found that when 6.5g of resin was used, the recovery rate was approximately 23.49%, when 19g was used, the recovery rate was 79.45%, and when 30g was used, the recovery rate was 88.04%, whereas when 25g was used, the highest recovery rate of 91.94% was observed.

[0048] Therefore, through these results, it was found that the appropriate amount of resin to use for adsorbing and analyzing radioactive cesium in seawater is 20 to 30 g per 100 L of seawater, and the most optimal amount is 25 g.

[0049] In addition, in the process of adding a cesium adsorption resin to the seawater and stirring to adsorb cesium onto the resin, it is preferable to perform the stirring in both directions for 10 minutes at a time for 3 hours.

[0050] The inventors analyzed the recovery rate of radioactive cesium in seawater by varying the stirring conditions, and compared to the group stirred in one direction for 3 hours, the group stirred in both directions for 3 hours, and the group stirred for 3 hours by air injection, the group stirred in both directions at 10-minute intervals for 3 hours showed the highest radioactive cesium recovery rate (91.94±4.74%).

[0051] Through these results, the inventors were able to determine that the amount of resin used for adsorbing radioactive cesium and the stirring conditions can play an important role in the analysis of radioactive cesium present in seawater, and that the most effective conditions are to use 25g of resin per 100L of seawater and to perform bidirectional stirring at 10-minute intervals for 3 hours.

[0052] Next, when the process of adsorbing cesium onto the resin is completed, (4) the process of precipitating the resin on which cesium has been adsorbed is performed. This allows for the resin and radioactive cesium to co-precipitate, and this precipitation is performed for 1 hour.

[0053] Once the precipitation process is complete, the supernatant can be transferred to another container and used to measure the cesium recovery rate.

[0054] In addition, the resin adsorbed with precipitated cesium is filtered, transferred to a dish, and dried. At this time, the filtration can be performed using filter paper, and in one embodiment of the present invention, filtration was performed using 7 µm filter paper.

[0055] The filtered resin is transferred to a dish and dried, and the drying can be performed by natural drying.

[0056] Once the drying process is complete, a step is performed to analyze the radioactive cesium adsorbed on the resin using a gamma nuclide spectrometer.

[0057] Furthermore, when the above process is completed, (7) the results of on-site analysis on the ship are derived by applying the recovery rate value of the cesium experiment obtained by performing the above (1) to (6) process, which preceded in the land laboratory, three or more times to the measured radioactive cesium concentration. Afterwards, (8) the final corrected radioactive cesium concentration is derived from the actual experimental recovery rate value derived from the samples through step (6) in the land laboratory.

[0058] The radioactive cesium to be analyzed by the method of the present invention is 137 It may be Cs, and this method can be fully performed within 24 hours on a mobile measuring system equipped on board.

[0059] The above-mentioned mobile measurement system consists of a mobile radioactivity onboard experimental space and a mobile radioactivity onboard measurement unit isolated from the outside on board, wherein the experimental space performs a seawater pretreatment process for radioactive cesium analysis, and the onboard measurement unit performs radioactive cesium analysis using a gamma radionuclide spectrometer.

[0060] The method of the present invention has the advantage of significantly reducing the time compared to conventional seawater radioactive material analysis methods. While conventional methods require at least two months, the method of the present invention can complete the analysis within 24 hours, that is, within one day.

[0062] The onboard mobile measurement system for analyzing radioactive cesium in seawater and the onboard rapid analysis method for radioactive cesium in seawater provided by the present invention are characterized by the ability to perform rapid on-site analysis compared to existing methods for monitoring marine radioactive materials; therefore, they have the advantage of enabling the immediate execution of the entire process, from sample collection to verification of analysis results, in areas where marine radioactive contamination is a concern.

[0064] The present invention will be explained in more detail below through examples. These examples are intended to explain the invention more specifically, and the scope of the invention is not limited to these examples.

[0066] <Example 1>

[0067] Establishment of a rapid onboard analysis method for radioactive cesium in seawater

[0068] The inventors of the present invention [distributed] radioactive cesium in seawater ( 137 A new method for rapidly monitoring and analyzing Cs on board was established through the following experiments.

[0070] <1-1> Rapid On-Ship Analysis of Radioactive Cesium in Seawater

[0071] ① Seawater collection and pH adjustment

[0072] First, about 100 liters of seawater were collected on board, filtered, and then the pH was adjusted to approximately 1.0. Specifically, the collected seawater was filtered through a filter, placed in a chamber, and the pH was adjusted to 1.0. This pH adjustment was intended to eliminate the influence of biological activity in the seawater and prevent the adsorption of unnecessary organic matter onto the resin.

[0074] ② Addition of cesium carrier (Cs carrier) and stirring

[0075] When the collection of seawater and pH adjustment were completed as described above, 10 mg of stable cesium (stable Cs) was added to each seawater sample as an internal standard for chemical recovery, and the mixture was stirred in both directions for 10 minutes at a time for 1 hour to achieve equilibrium with radioactive cesium.

[0077] ③ Addition of resin and stirring

[0078] After the process of ② above was completed, a resin (KNiFC-PAN) for adsorbing radioactive cesium was added to the seawater sample (6.5g, 19g, 25g) and stirring was performed. The stirring was carried out by stirring in one direction for 3 hours, stirring in both directions for 3 hours, stirring in both directions for 10 minutes at a time for 3 hours, and stirring with air injection for 3 hours, and the stirring was performed at a speed of 700 rpm. Through this resin addition and stirring, radioactive cesium present in the seawater was adsorbed onto the resin. In addition to the 3-hour stirring time, stirring was also performed for 1 hour, 4 hours, and 5 hours, respectively.

[0079] In addition, the resin (KNiFC-PAN) used in this experiment was a KNiFC-PAN (100 - 600 μm; TRISKEM) resin in which KNiFC (potassium-nickel hexacyanoferrate II) and an organic support, PAN (polyacrilonitrile), were combined.

[0081] ④ Measurement of radioactive cesium after co-precipitation

[0082] After adsorbing radioactive cesium from seawater onto the resin through the above process, the stirred sample was co-precipitated with the adsorbed resin for 1 hour, and the supernatant was collected in 20 ml aliquots. The precipitated resin was collected using filter paper (pore size: 7 μm; diameter: 90 mm; ADVANTEC filter paper), transferred to a petri dish, and air-dried for 1 hour. 137 Cs analysis was performed using the HPGe gamma radionuclide spectrometry system (High Purity Germanium gamma spectrometry; relative efficiency 100%; ORTEC®USA), and reliable results (uncertainty < 10%) were obtained through an analysis time of 8 hours.

[0084] ⑤ Derivation of results for primary on-board radioactive cesium

[0085] After measuring radioactive cesium in seawater through the above process, the chemical recovery rate was derived using the chemical recovery rate (91.94%) obtained from three or more preliminary studies at a land-based laboratory.

[0087] ⑥ Derivation of final radioactive Cs concentration result

[0088] The chemical recovery rate of the sample obtained on board was measured in a land-based laboratory using the following procedure. The aliquoted supernatant was diluted approximately 10,000 times and measured using MC-ICP-MS (multi-collector inductively coupled plasma mass spectrometry). The chemical recovery rate was applied to the results obtained from the gamma radionuclide spectroscopic analysis system on board to derive the final radioactive Cs concentration result.

[0089] The analysis process of radioactive cesium in seawater according to the present invention is shown in the schematic diagram of FIG. 1 and FIG. 2.

[0091] <1-2> Analysis Results

[0092] Analysis of radioactive cesium in seawater was performed using the method of <1-1> above, and the optimal analysis method was established based on the following results.

[0094] <1-2-1> Analysis of Radioactive Cesium Recovery Rate According to Resin Addition Amount

[0095] The inventors analyzed the cesium recovery rate by using different amounts of resin added in the resin addition and stirring process of Example <1-1> as 6.5g, 19g, and 25g, respectively, during the process of analyzing radioactive cesium in seawater.

[0097] As a result, as shown in Figure 3, a higher radioactive cesium recovery rate was confirmed when 25g of resin was used compared to when 6.5g and 19g of resin were used. In addition, the chemical recovery rate of KNiFC-PAN resin showed a recovery rate value approximately 1.2 times higher than that of AMP-PAN resin, confirming that the use of KNiFC-PAN resin is desirable.

[0099] Furthermore, to additionally confirm the optimal amount of KNiFC-PAN and the chemical recovery rate and precision of the field experiment, the inventors performed repeated experiments with resin amounts of 6.5g, 9g, 25g, and 30g (n = 6).

[0100] As a result, as shown in Figure 4, the group using 25 g of resin showed a relatively higher chemical recovery rate (91.94% ± 4.74%) compared to the groups using 6.5 g, 9 g, and 30 g of resin.

[0101] Therefore, through these experiments, the inventors confirmed that using KNiFC-PAN resin in an amount of 25 g per 100 L of seawater is the most optimal condition for recovering and analyzing radioactive cesium in seawater using the method of the present invention.

[0103] <1-2-2> Analysis of Radioactive Cesium Recovery Rates According to Stirring Conditions

[0104] Next, the inventors analyzed the effect of stirring conditions after resin addition on the recovery rate of radioactive cesium. To this end, KNiFC-PAN resin was added in an amount of 25 g per 100 L of seawater, and stirring conditions were performed under the following four conditions: (i) stirring in one direction for 3 hours, (ii) stirring in both directions for 3 hours, (iii) stirring in both directions for 10 minutes at a time for 3 hours, and (iv) stirring with air injection for 3 hours. The recovery rate of radioactive cesium recovered under each stirring condition was analyzed.

[0106] As a result, as shown in Figure 5, the condition of stirring in both directions for 10 minutes at a time for 3 hours showed the highest radioactive cesium recovery rate (91.94 ± 4.74%). When stirring in one direction, the recovery rate was found to be 73.23 ± 1.67%, and when stirring in both directions, the recovery rate was found to be 81.00 ± 1.90%, indicating that stirring in both directions for 10 minutes at a time for 3 hours is a condition that can significantly increase the radioactive cesium recovery rate.

[0108] <1-2-3> Analysis of Radioactive Cesium Recovery Rate According to Stirring Time

[0109] In addition, the inventors also performed an analysis of the radioactive cesium recovery rate according to the stirring time after adding the resin. KNiFC-PAN resin was added at a rate of 25 g per 100 L of seawater, and the cesium recovery rate was analyzed by varying the stirring time to 1 hour, 3 hours, 4 hours, and 5 hours, respectively.

[0111] As a result, as shown in Figure 6, the highest chemical recovery rate (91.94 ± 4.74%) was observed when the stirring time was 3 hours. When stirred for 2 hours, a recovery rate of 73.64 ± 1.55% was observed, and when stirred for 4 hours, which exceeded 3 hours, a recovery rate of 85.36 ± 2.02% was observed, indicating that the condition of stirring for 3 hours is the most effective condition for recovering and analyzing radioactive cesium.

[0113] Through the above results, the inventors confirmed that when analyzing radioactive cesium in seawater on board using the method of the present invention, adding 25g of resin and stirring in both directions for 10 minutes for 3 hours allows for the recovery of radioactive cesium with a high yield, thereby enabling more accurate and rapid analysis of radioactive cesium in seawater.

[0115] <Example 2>

[0116] Comparison of the onboard rapid field analysis method according to the present invention and existing methods

[0117] The inventors verified whether the onboard rapid method for radioactive cesium in seawater according to <Example 1> has superior analytical accuracy compared to the conventional method (a method of collecting seawater, moving it to a land-based laboratory, and then analyzing it).

[0118] To this end, when conducting a field survey in Namhae in October 2022, the recovery rate of radioactive cesium recovered by the conventional method and the recovery rate of radioactive cesium recovered by the method of the present invention were compared based on the results (Figs. 7 and 8).

[0119] As a result, the average values ​​of the field survey of the present invention and the land survey of the conventional method were 1.99 ± 0.40 mBq / kg and 1.90 ± 0.40 mBq / kg, respectively, and it was confirmed that when the rapid analysis method of the present invention was performed in the field, it showed high accuracy of 100.54 ± 4.00% at a 95.4% confidence interval (mean ± 2 × standard deviation). These results showed an average difference of 0.54% when compared with the value calculated by applying the average recovery rate of 91.94% obtained from three identical processes on land prior to the field survey, and showed an error of -3.46 to 4.54% at a 95.4% confidence interval. This confirmed that the present method is a highly accurate rapid analysis method capable of determining the presence of contamination from the concentration of radioactive Cs in seawater obtained while conducting field surveys with an error of less than 5%.

[0121] In addition, the inventors determined that a measurement time of at least 8 hours was required to perform a precise analysis using a gamma detector established based on the cesium concentration in a typical seawater sample (1–2 mBq kg⁻¹), and therefore performed the analysis based on an 8-hour standard. When performing the analysis with an 8-hour measurement time, the cesium concentration in a typical seawater sample (1–2 mBq kg⁻¹) -1 Based on ), the uncertainty was found to be 0.35 ± 0.13 mBq / kg, and when the uncertainty is allowed to be 30%, the MDL (minimum detection limit) was found to be 0.61 mBq / kg.

[0122] Based on the above results, the inventors found that the method of the present invention can identify and analyze the radioactive contamination situation in the sea more accurately, quickly, and preemptively compared to conventional methods performed in land-based laboratories.

[0124] <Example 3>

[0125] Establishment of a shipboard mobile measurement system for on-site analysis of radioactive cesium in seawater

[0126] The inventors have constructed a shipboard mobile measurement system capable of rapidly performing onboard the on-site analysis of radioactive cesium in seawater established in <Example 1>. The appearance of the shipboard mobile on-site measurement system constructed on board is shown in FIG. 9, the floor plan of the measurement room of the on-site measurement system of the present invention is shown in FIG. 10, and the floor plan of the laboratory is shown in FIG. 11.

[0127] The field measurement system (field measurement room container) of the present invention is constructed as a mobile type that can be mounted on a ship and is divided into a field laboratory and a field measurement room isolated from the outside on board. First, seawater collected from the ship is immediately transferred to the field laboratory to perform the resin co-precipitation and drying process, and then radioactive cesium is analyzed using two gamma detectors in the field measurement room. At this time, the two gamma detectors equipped in the field measurement room were placed in the side space to minimize the influence of the ship's inclination and the bias caused by the weight of the equipment (2 tons each) when used on board. The two gamma detectors (model name: GEM100-ICS-ES; Ortec, AMETEK ORTEC) have identical performance and are instruments that measure gamma rays from radionuclides in a sample. They have superior performance, with a measurement efficiency (>100%) approximately twice that of the widely used gamma detector (GC5019; Canberra), and have the advantage of not requiring periodic liquid nitrogen supply through an electric cooling system.

[0129] Those skilled in the art to which the present invention pertains will understand that the present invention may be embodied in modified forms without departing from the essential characteristics of the invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the invention is defined by the claims, not by the foregoing description, and all variations within the scope of equivalents should be interpreted as being included in the invention.

Claims

Claim 1 (1) A step of filtering seawater collected from a ship, adding it to a chamber, and adjusting the pH to 1.0 to 2.0; (2) A step of adding stable cesium (Cs) to the pH-adjusted seawater and stirring; (3) A step of adding a cesium adsorption resin to the seawater and stirring to adsorb cesium onto the resin; (4) A step of precipitating the resin with adsorbed cesium; (5) A step of filtering the precipitated resin with adsorbed cesium, transferring it to a dish, and drying it; A method for rapid onboard analysis of radioactive cesium in seawater, comprising the step of (6) analyzing radioactive cesium adsorbed on a resin using a gamma radionuclide spectrometer, wherein in step (3), the resin for adsorbing cesium is a KNiFC-PAN resin in which potassium-nickel hexacyanoferrate II (KNiFC) and polyacrylonitrile (PAN) as an organic support are combined, and 25g is added per 100L of seawater, and the stirring is performed in both directions for 10 minutes each for 3 hours. Claim 2 A method for rapid onboard analysis of radioactive cesium in seawater according to claim 1, further comprising: (7) a step of deriving a result of primary field analysis by applying the cesium recovery rate value obtained by performing the process of (1) to (6) three or more times in advance at a land laboratory to the measured concentration of radioactive cesium; and (8) a step of deriving the final concentration of radioactive cesium in seawater using the cesium recovery rate value obtained from the supernatant obtained after precipitating the resin on which cesium was adsorbed in step (4). Claim 3 A method for rapid onboard analysis of radioactive cesium in seawater, characterized in that, in step (2) above, stable cesium (Cs) is added in an amount of 10 to 20 mg per 100 L of collected seawater, and the stirring is performed in both directions for 10 to 20 minutes at a time for 1 to 2 hours. Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 In paragraph 1, the radioactive cesium 137 A rapid onboard analysis method for radioactive cesium in seawater, characterized by being Cs. Claim 8 A method for rapid onboard analysis of radioactive cesium in seawater according to claim 1, characterized in that the method is performed within 24 hours on a mobile measuring system provided on board. Claim 9 A method for rapid onboard analysis of radioactive cesium in seawater according to claim 8, wherein the mobile measurement system comprises a mobile radioactive onboard experimental space and a mobile radioactive onboard measurement unit isolated from the outside on board, wherein the experimental space performs a pretreatment process of seawater for radioactive cesium analysis, and the onboard measurement unit performs radioactive cesium analysis using a gamma radionuclide spectrometer. Claim 10 delete Claim 11 delete Claim 12 delete

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