WO2023140562A1 - Apparatus and method for separating radioactive strontium from seawater using cation exchange resin - Google Patents

Abstract

The present invention relates to an apparatus and a method for separating radioactive strontium (SR-90) from seawater using a cation exchange resin, the invention comprising: a first transfer unit for transferring a resin activation solution, a seawater sample, a washing solution and a strontium eluate; a first solution selection unit; a second transfer unit; a column unit in which a prescribed amount of a cation exchange resin is pre-filled and to which the solution transferred from the second transfer unit is injected; a second solution selection unit for selecting a waste liquid or a strontium recovery solution; a pump unit for transferring the solution; and a control unit for controlling the first and second solution selection units and the pump unit, wherein the control unit may control the first and second solution selection units and the pump unit to sequentially inject the resin activation solution, the seawater sample and the washing solution into the column unit in order to discharge the waste liquid, and to inject the strontium eluate into the column unit in order to discharge the strontium recovery solution from the column unit.

Description

Apparatus and method for separating radioactive strontium from seawater using cation exchange resin

The present invention relates to an apparatus for separating radioactive strontium from seawater, and more particularly, to an apparatus and method for separating radioactive strontium (Sr-90) from seawater using a cation exchange resin.

In general, Sr-90 in seawater is present in extremely small amounts, and most of these Sr-90 have been introduced into the environment by nuclear experiments in the past 50-60 years, and since the amount of Sr-90 in seawater is very low, it is a trace amount of artificial radionuclide that is detected only through precise radioactivity analysis using a large amount of seawater.

Since Sr-90 is generated during the operation of a nuclear reactor, has a long physical half-life, and has a high radiation risk, operators of nuclear power facilities as well as related regulatory agencies are investigating Sr-90 in environmental samples around facilities, and among these environmental samples, seawater is one of the important targets of investigation.

In addition, as concerns about pollution to the sea have increased since the Fukushima nuclear power plant accident in Japan, Sr-90 analysis in seawater in the waters around Korea is being periodically performed.

Since Sr-90 is a nuclide that emits beta rays and has a very low concentration, concentration through chemical separation and pure separation are required for detection.

As the most common method, the separation method using the difference in solubility of Ca nitrate and Sr nitrate according to the nitric acid content is used in many laboratories, but this method is very dangerous because it uses a large amount of fuming nitric acid (95%) with a high nitric acid concentration.

In addition, a preliminary process of reducing the volume of a large amount of seawater through carbonate or oxalate precipitation is required before using fuming nitric acid.

In addition, as a column separation method using Sr-Spec resin, which has specificity for Sr, this resin uses a method that can easily separate Sr from Ca, but in the case of samples with high Ca and Sr content, the chemical recovery rate is significantly lowered. Since the price of the resin is too expensive, it is difficult to apply when a large amount of seawater is used.

In addition, a solvent extraction method using HDEHP (di-(2-ethylhexyl) hydrogen phosphoric acid) and Heptane may be used, but this method is also not suitable for processing a large amount of samples such as seawater.

In addition, Registered Patent Publication No. 10-1656475 suggests a method for separating Sr by a method for recovering strontium contained in seawater, but this is a method of recovering Sr in the form of cyclic strontium crystals after removing Ca and Mg, which are +divalent cations present in large amounts in seawater, through hydroxide precipitation. No. 9-001347 is a high-purity recovery method for strontium in seawater. In a method similar to No. 10-1656475, initial Ca and Mg are removed by hydroxyl precipitation and oxalate precipitation, and then Sr is separated using an ion exchange resin. Specific detailed conditions for the Sr separation method using an ion exchange resin are not presented, the separation process is complicated, and no technology for using the device in the column separation process is presented.

In addition, Publication No. 10-2016-0007228 discloses a method for manufacturing 4A-Ba composite zeolite for treatment of radioactive Sr contaminated water and a method for treating contaminated water using the same, and Patent Publication No. 10-2020-0080181 discloses an Sr ion adsorbent using layered vanadosilicate and a method for removing Sr ions using the same, and Laid-Open Patent Publication No. 10-2020-0080 No. 181 discloses a separation method for the quantification of regulatory nuclides Tc-99, Sr-90, Fe-55, Nb-94 and Ni-59 (Ni-63) contained in layered radioactive waste, but these methods have limitations in application to seawater as a separation method for high-concentration radioactive waste and seawater and other solution compositions and conditions.

Therefore, in the future, it is required to develop a technology for separating radioactive strontium (Sr-90) from seawater that can be automated to safely and quickly separate Sr-90 and increase the efficiency of the separation.

A technical problem to be achieved by an embodiment of the present invention is to provide an apparatus and method for separating radioactive strontium from seawater that can be automated to safely and quickly separate radioactive strontium (Sr-90) from seawater and increase the efficiency of the separation by obtaining a recovered strontium solution by injecting a strontium elution solution into the column portion after completion of sequentially injecting a resin activating liquid, a seawater sample, and a washing liquid into a column portion containing a cation exchange resin.

The technical problems to be achieved in the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below.

In order to solve the above technical problems, an apparatus for separating radioactive strontium in seawater according to an embodiment of the present invention includes a first transfer unit that transfers a resin activating liquid, a seawater sample, a washing liquid, and a strontium eluting liquid separately contained in a plurality of solution containers; A second transfer unit for transferring the solution selected from the second transfer unit, a column unit containing a predetermined amount of cation exchange resin in advance and injecting the solution transferred from the second transfer unit, a second solution selector connected to the column unit and selecting waste liquid or strontium recovery liquid, a third transfer unit connected to the second solution selector to transfer the waste liquid or strontium recovery liquid to a recovery container, a pump unit connected to the second transfer unit and transferring the solution, and a control unit for controlling the first and second solution selectors and the pump unit. The controller may control the first and second solution selectors and the pump to sequentially inject the resin activating liquid, the seawater sample, and the washing liquid into the column part and discharge the waste liquid from the column part, and when the resin activating liquid, the seawater sample, and the washing liquid are sequentially injected into the column part, the first and second solution selecting parts and the pump part may inject the strontium eluate into the column part and discharge the recovered strontium liquid from the column part.

In an alternative embodiment of the apparatus for separating radioactive strontium from seawater, the present invention may further include a solution container including a first solution container containing the resin activating solution, a second solution container containing the seawater sample, a third solution container containing the washing solution, and a fourth solution container containing the strontium eluate.

In an alternative embodiment of the apparatus for separating radioactive strontium in seawater, the resin activating solution may include 0.2M HCl, the washing solution may include a washing solution in which 2M ammonium acetate (NH ₄ CH ₃ CO ₂ ) and methanol are mixed in a ratio of 1:1, and the strontium eluate may include 2M ammonium acetate (NH ₄ CH ₃ CO ₂ ).

In an alternative embodiment of the device for separating radioactive strontium from seawater, the first transfer unit includes: a first suction tubing inserted in the first solution container to transfer the resin activating liquid to the first solution selector; a second suction tubing inserted in the second solution container to transfer the seawater sample to the first solution selector; a third suction tubing inserted in the third solution container to transfer the washing liquid to the first solution selector; and a strontium eluate inserted in the fourth solution container. It may include a fourth suction tubing for transferring to the first solution selector.

In an alternative embodiment of the apparatus for separating radioactive strontium from seawater, the present invention further includes a first sensor unit for sensing the flow of the solution flowing in the first transfer unit, and a second sensor unit for detecting the level of the solution contained in the column unit, wherein the control unit determines whether the transfer of the solution contained in the solution container is completed based on the sensing signal received from the first sensor unit, controls the first and second solution selection units and the pump unit, and controls the first and second solution selection units and the pump unit based on the sensing signal received from the second sensor unit. The pump unit may be controlled by determining the level of the solution contained in the unit.

In an alternative embodiment of the device for separating radioactive strontium from seawater, the first sensor unit may include a first photoelectric sensor disposed around the suction tubing of the first transfer unit to primarily sense the flow of the solution, and a second photoelectric sensor disposed around the intake tubing of the first transfer unit to be spaced apart from the first photoelectric sensor by a predetermined distance to secondarily sense the flow of the first-detected solution.

In an alternative embodiment of the apparatus for separating radioactive strontium from seawater, the second sensor unit may include a water level sensor inserted at an upper end of the column unit to detect a level of a solution injected into the column unit.

In an alternative embodiment of the apparatus for separating radioactive strontium from seawater, the control unit controls the first solution selector to select the resin activating liquid when a user input requesting separation of strontium is received, controls the second solution selector to select the waste liquid of the column unit at the same time, controls the pump unit to transfer and injects the selected resin activating liquid into the column unit, and controls the first solution selector to select the seawater sample when the injection of the resin activating liquid is completed; control the pump unit to transfer and inject the seawater sample, control the first solution selector to select the washing liquid when the injection of the seawater sample is completed, control the pump unit to transfer and inject the selected washing liquid to the column unit, and control the first solution selector to select the strontium elution solution and simultaneously control the second solution selector to select the strontium recovery solution of the column unit, and transfer and inject the selected strontium elution solution into the column unit. When the pump unit is controlled and the injection of the strontium eluate is completed, separation and recovery of strontium may be completed.

In an alternative embodiment of the apparatus for separating radioactive strontium from seawater, the control unit may fill the suction tubing of the first transfer unit up to the front end of the first solution selection unit with the resin activating liquid, the seawater sample, the cleaning liquid, and the strontium eluate contained in the plurality of solution containers before receiving a user input requesting separation of strontium.

On the other hand, a method for separating radioactive strontium from seawater according to an embodiment of the present invention is a method for separating radioactive strontium from seawater of a radioactive strontium separation device including a control unit for controlling first and second solution selection units and a pump unit. (b) the control unit controls the first solution selector to select the seawater sample when the injection of the resin activating liquid is completed, and controls the pump unit to transport and inject the selected seawater sample into the column unit, (c) the control unit controls the first solution selector to select the washing liquid when the injection of the seawater sample is completed, and controls the pump unit to transfer and inject the selected washing liquid into the column unit, (d) The control unit may control the first solution selector to select the strontium eluate when the injection of the washing solution is completed, simultaneously control the second solution selector to select the strontium recovery solution of the column unit, and control the pump unit to transport and inject the selected strontium eluate into the column unit, and (e) the control unit to complete separation and recovery of strontium when the injection of the strontium eluate is completed.

Effects of the device and method for separating radioactive strontium from seawater according to the present invention are as follows.

In the present invention, after injection of the resin activating liquid, seawater sample, and washing liquid sequentially into the column unit containing the cation exchange resin, the strontium elution solution is injected into the column unit to obtain a recovered strontium solution, thereby enabling automation to safely and quickly separate radioactive strontium (Sr-90) from seawater and increase the efficiency of the separation.

That is, the present invention, by directly injecting seawater into a column to separate Sr without chemical pretreatment, can ensure the rapidity and safety of chemical separation, and by injecting a certain amount of separation solution at a constant rate, the accuracy and reproducibility of Sr separation are improved. It is expected to contribute to the improvement of analytical ability and quality of domestic nuclear operators and marine research-related laboratories that analyze Sr-90 in seawater.

In addition, the present invention has the advantage of significantly improving the safety of analysts and laboratories and reducing the generation of acid waste by using a safe reagent instead of the existing toxic fuming nitric acid.

In addition, according to the present invention, without computer-based programming, all separation processes proceed in order without the intervention of an analyst by manipulating the automatic separation operation button on the control panel according to the designed operation sequence, and even the final Sr separation solution is recovered, so that user convenience can be promoted, and even first-time users can use it easily.

In addition, in the present invention, since the physical safety of the cation exchange resin is high and the chemical reactivity to the separation solutions is low, it can be used repeatedly by using a regeneration process based on an ion exchange method, so there is no need to use a large amount of resin, thereby reducing economic costs.

In addition, the present invention is expected to be widely used in other radionuclide separations using a similar separation method by automating the element separation process using a column and a separation solution.

A further scope of the applicability of the present invention will become apparent from the detailed description that follows. However, since various changes and modifications within the spirit and scope of the present invention can be clearly understood by those skilled in the art, it should be understood that the detailed description and specific examples such as preferred embodiments of the present invention are given as examples only.

1 is a block diagram illustrating an apparatus for separating radioactive strontium from seawater according to an embodiment of the present invention.

2 is a schematic diagram illustrating an apparatus for separating radioactive strontium from seawater according to an embodiment of the present invention.

3 is a flowchart illustrating a method for separating radioactive strontium from seawater according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

The suffixes "module" and "unit" for components used in the following description are simply given in consideration of the ease of writing the present specification, and the "module" and "unit" may be used interchangeably.

Furthermore, embodiments of the present invention will be described in detail below with reference to the accompanying drawings and the contents described in the accompanying drawings, but the present invention is not limited or limited by the embodiments.

The terminology used in this specification has been selected as a general term that is currently widely used as much as possible while considering the function in the present invention, but it may vary according to the intention or custom of a person skilled in the art or the emergence of new technology. In addition, in a specific case, there is also a term arbitrarily selected by the applicant, and in this case, the meaning will be described in the description of the invention. Therefore, it should be clarified that the terms used in this specification should be interpreted based on the actual meaning of the term and the overall content of this specification, rather than simply the name of the term.

1 is a block configuration diagram for explaining an apparatus for separating radioactive strontium in seawater according to an embodiment of the present invention, and FIG. 2 is a schematic diagram for explaining an apparatus for separating radioactive strontium in seawater according to an embodiment of the present invention.

As shown in FIGS. 1 and 2, the present invention is connected to the first transfer unit 100 for transferring the resin activating liquid 62, the seawater sample 64, the washing liquid 66, and the strontium eluate 68 separately contained in a plurality of solution containers. A first solution selector 200 for selecting any one of the solutions, a second transfer unit 300 connected to the first solution selector 200 and transporting the solution selected from the first solution selector 200, a column unit 400 containing a predetermined amount of cation exchange resin 410 in advance and injecting a solution transferred from the second transfer unit 300, and a waste liquid 32 or strontium recovery liquid 3 connected to the column unit 400 The second solution selector 500 for selecting 4), the third transfer unit 600 connected to the second solution selector 500 to transfer the waste liquid 32 or the strontium recovery liquid 34 to the recovery container, the pump unit 700 connected to the second transfer unit 300 to transport the solution, and the control unit 800 to control the first and second solution selectors 200 and 500 and the pump unit 700. can include

In addition, the present invention may further include a solution container 90 including a first solution container 92 containing the resin activating liquid 62, a second solution container 94 containing the seawater sample 64, a third solution container 96 containing the cleaning solution 66, and a fourth solution container 98 containing the strontium eluate 68.

For example, the resin activating solution 62 may include about 0.2M HCl, the washing solution 66 may include a washing solution in which about 2M ammonium acetate (NH ₄ CH ₃ CO ₂ ) and methanol are mixed in a ratio of 1:1, and the strontium eluent 68 may include about 2M ammonium acetate (NH ₄ CH ₃ CO ₂ ), which is only an example and is not limited thereto. does not

In addition, the first transfer unit 100 includes a first suction tubing 110 inserted into the first solution container 92 to transfer the resin activation liquid 62 to the first solution selector 200, a second suction tubing 120 inserted into the second solution container 94 to transfer the seawater sample 64 to the first solution selector 200, and a washing liquid 66 inserted into the third solution container 96 to the first solution selector It may include a third suction tubing 130 that transfers to 200, and a fourth suction tubing 140 that is inserted into the fourth solution container 98 and transfers the strontium eluate 68 to the first solution selector 200.

Here, ends of the first to fourth suction tubings 110 , 120 , 130 , and 140 may be placed in contact with the bottoms of the first to fourth solution containers 92 , 94 , 96 , and 98 .

In addition, the first, third, and fourth suction tubings 110, 130, and 140 may be fixed by fixing nuts 50 disposed above the first, third, and fourth solution containers 92, 96, and 98, and the second suction tubing 120 may be fixed by a guide tube support 40 disposed above the second solution container 94.

And, the present invention, the first sensor unit 910 for detecting the flow of the solution flowing in the first transfer unit 100, and the second sensor unit 920 for detecting the water level of the solution contained in the column unit 400 It may further include.

For example, the first sensor unit 910 may include a first photoelectric sensor 912 disposed around the suction tubing of the first transfer unit 100 to firstly sense the flow of the solution, and a second photoelectric sensor 914 disposed around the suction tubing of the first transfer unit 100 to be spaced apart from the first photoelectric sensor 912 by a predetermined distance to secondarily sense the firstly sensed flow of the solution. only, but not limited thereto.

In the present invention, the reason for disposing the first sensor unit 910 is to determine whether the transfer of the solution contained in the solution container is complete.

That is, the control unit 800 of the present invention can control the first solution selection unit 200 by determining whether or not the transfer of the solution contained in the solution container is completed based on the sensing signal received from the first sensor unit 910.

For example, if the sensing signal of the first photoelectric sensor 912 is a signal of primarily detecting the flow of the solution and the sensing signal of the second photoelectric sensor 914 is a signal of secondary sensing of the flow of the solution, the control unit 800 may determine that the transfer of the solution contained in the solution container has not been completed and maintain the first solution selector 200 that has selected the current solution as it is, and the sensing signal of the first photoelectric sensor 912 primarily senses the flow of air. signal, and when the signal sensed by the second photoelectric sensor 914 is a signal obtained by secondarily detecting air flow, the first solution selector 200 may be controlled to select another solution by determining that the transfer of the solution contained in the solution container is complete.

As another example, if the sensing signal of the first photoelectric sensor 912 is a signal of primarily detecting the flow of the solution and the sensing signal of the second photoelectric sensor 914 is a signal of secondary sensing of the flow of air, the control unit 800 may determine that the transfer of the solution contained in the solution container is incomplete and maintain the first solution selector 200 that has selected the current solution as it is, and the sensing signal of the first photoelectric sensor 912 primarily senses the flow of air If it is a signal and the sensing signal of the second photoelectric sensor 914 is a signal that secondarily senses the flow of the solution, it is determined that the transfer of the solution contained in the solution container is incomplete, and the first solution selector 200 that currently selects the solution can be maintained.

In addition, the second sensor unit 920 may include a water level sensor inserted into the upper end of the column unit 400 to detect the level of the solution injected into the column unit 400, which is only one embodiment, but is not limited thereto.

Here, the water level sensor may be positioned higher than the surface height of the cation exchange resin 410 contained in the column unit 400.

In the present invention, the reason for arranging the second sensor unit 920 is to determine the level of the solution injected into the column unit 400 and prevent the risk of an excessive increase in the solution in the column unit 400 due to the abnormal operation of the automatic separator.

That is, the control unit 800 may control the pump unit 700 by determining the water level of the solution contained in the column unit 400 based on the sensing signal received from the second sensor unit 920 .

For example, the control unit 800 may control the pump unit 700 to stop operation of the pump unit 700 when the sensing signal of the water level sensor is a signal that increases above a certain level of the solution injected into the column unit 400.

Next, the second transport unit 300 may include an elastic tubing for transporting the solution selected from the first solution selector 200 .

In addition, the pump unit 700 may transfer the solution in one direction at a predetermined speed using pressure generated by compressing the elastic tubing of the second transfer unit 300 while the roller of the pump rotates.

In addition, the third transfer unit 600 may include a waste transfer unit 610 that is connected to the second solution selector 500 and transfers the waste liquid 32 to the waste liquid container 42, and a recovery liquid transfer unit 620 that is connected to the second solution selector 500 and transfers the recovered strontium liquid 34 to the recovery container 44.

Next, the control unit 800 controls the first and second solution selection units 200 and 500 and the pump unit 700 to discharge the waste liquid 32 from the column unit 400 by sequentially injecting the resin activating liquid 62, the seawater sample 64, and the washing liquid 66 into the column unit 400, and the resin activating liquid 62, the seawater sample 64, and the washing liquid 66 are sequentially supplied to the column unit ( 400), the first and second solution selection units 200 and 500 and the pump unit 700 can be controlled to inject the strontium eluate 68 into the column unit 400 and discharge the strontium recovery liquid 34 from the column unit 400.

For example, the control unit 800 includes a main power circuit breaker 810 that turns on/off the power supply, a pump speed controller 820 that controls the operation of the pump unit 700 and the solution transfer speed, a first operation controller 830 that controls the solution selection operation of the first solution selector 200, a second operation controller 840 that controls the solution selection operation of the second solution selector 500, and an overall operation for automatic separation of strontium. It may include an automatic separation operation button 850 for turning on/off, which is only one embodiment, but is not limited thereto.

Here, the controller 800 controls the first solution selector 200 to select the resin activating liquid 62 when a user input requesting separation of strontium is received, and simultaneously controls the second solution selector 500 to select the waste liquid 32 of the column part 400, and controls the pump part 700 to transfer and inject the selected resin activating liquid 62 into the column part 400, and injection of the resin activating liquid 62 is completed. When the seawater sample 64 is selected, the first solution selector 200 is controlled to select the seawater sample 64, and the pump unit 700 is controlled so that the selected seawater sample 64 is transported and injected into the column unit 400. When the injection of the seawater sample 64 is completed, the first solution selector 200 is controlled to select the washing liquid 66, and the pump unit 700 is controlled so that the selected washing liquid 66 is transferred and injected into the column unit 400, When the injection of the cleaning solution is completed, the first solution selector 200 is controlled to select the strontium eluate 68, and the second solution selector 500 is controlled to select the strontium recovery solution 34 of the column unit 400. Separation and recovery of strontium may be completed by controlling the operation of the pump unit 700 .

At this time, the control unit 800, when checking whether the injection of any one of the resin activating liquid 62, the seawater sample 64, the cleaning liquid 66, and the strontium eluate 68 has been completed, can confirm whether the injection of the solution has been completed based on the first sensing signal for firstly sensing the flow of the solution and the second sensing signal for secondarily sensing the firstly sensed flow of the solution.

For example, if the first and second sensing signals are both signals for detecting the flow of air, the controller 800 may determine that the injection of the solution is completed, and if both the first and second sensing signals are signals for detecting the flow of the solution, the controller 800 may determine that the injection of the solution is incomplete.

In addition, the control unit 800 may control the pump unit 700 to stop operation of the pump unit 700 based on a sensing signal that detects the level of the solution injected into the column unit 400 when transferring and injecting any one of the resin activating liquid 62, the seawater sample 64, the washing liquid 66, and the strontium eluate 68 into the column unit 400.

For example, when the solution injected into the column unit 400 increases above a certain level, the water level sensor of the column unit 400 recognizes this and generates a sensing signal for this, and the control unit 800 can control the pump unit 700 to stop the operation of the pump unit 700 based on this.

In addition, before receiving a user input requesting separation of strontium, the control unit 800 may fill the resin activating liquid 62, the seawater sample 64, the cleaning liquid 66, and the strontium eluting liquid 68 separately contained in a plurality of solution containers into the suction tubing of the first transfer unit 100 up to the front end of the first solution selection unit 200.

For example, the control unit 800 controls the first solution selector 200 and the pump unit 700 to fill the first suction tubing 110 of the first transfer unit 100 inserted into the first solution container 92 and connected to the first solution selector 200 with the resin activating liquid 62, inserted into the second solution container 94 and connected to the first solution selector 200, the first transfer unit 100 The seawater sample 64 is filled in the second suction tubing 120 of the third solution container 96 and the washing liquid 66 is filled in the third suction tubing 130 of the first transfer unit 100 connected to the first solution selector 200, and the fourth suction tubing 140 of the first transfer unit 100 is inserted into the fourth solution container 98 and connected to the first solution selector 200. A strontium eluate (68) may be charged.

In addition, the control unit 800 may regenerate the cation exchange resin by injecting a cation removal solution into the column unit 400 when the separation and recovery of strontium is completed.

Here, the cation removal solution may include about 2M HCl, which is only an example, but is not limited thereto.

As such, the configuration of the present invention relates to a method for separating strontium (Sr) from seawater based on a cation exchange resin and an automated separation method for Sr from seawater using the same.

In the present invention, a solution container capable of containing seawater sample, resin activation solution, washing solution, Sr-eluate solution, waste solution, and Sr-recovery solution is prepared, and the solution container including these solution containers is placed at the lower end of the automatic separation device 80.

In addition, the automatic separation device 80 of the present invention includes a Teflon tubing connecting the injection solution to the final recovery container, a tubing pump for transporting the solution, a seawater sample suction tubing guide tube support and a nut for fixing the separation solution suction tubing, a primary solution selection valve for switching the injection solution flow path, a secondary solution selection valve for switching the final recovery solution flow path, a cation exchange resin and an acrylic column containing it, and an optical sensor for detecting the flow of the injection solution It consists of a front sensor, a water level sensor that detects the height of the solution in the column part, a main power breaker for the separation device, a pump operation and pump speed controller, a first solution selection valve passage control, a second solution selection valve passage adjustment, and a control panel that includes the entire process operation function, so that radioactive strontium (Sr-90) can be automatically separated from a large amount of seawater sample.

For the analysis of Sr-90, a radionuclide in seawater, a method of chemically separating stable Sr in seawater and measuring the separated radioactive Sr together with stable Sr with a radioactivity meter can be used.

To this end, in the present invention, as a method of separating Sr from seawater, a cation exchange resin (Dowex 50W-8X, 100-150 mesh) was used, and this method is a method of selectively separating only Sr using a washing and elution solution after adsorbing cations including Sr present in seawater to the resin.

In the present invention, the core of the separation technology is to remove Ca, which is present in a large amount in seawater, is difficult to separate due to similar chemical behavior to Sr, and causes interference in measuring Sr recovery rate and measuring radioactivity.

In the present invention, in order to adsorb cations in seawater, activation of the resin is required. For this purpose, 4 L of about 0.2M hydrochloric acid was injected into the cation exchange resin to convert the reactive group of the resin to H ⁺ type so that cations could be adsorbed.

In addition, the amount of cation resin used was 1.7 L (based on hydrated resin), which is sufficient for Ca separation and Sr recovery, considering the amount of seawater sample (40 L) and the adsorption capacity of the cation resin.

The sample injection rate was determined to be about 30 ml per minute with a balance of inflow and outflow considering the resin capacity (internal diameter: 9 cm, height: 26 cm) and the particle diameter of the resin particles (100 to 150 mesh) in the column. Based on this, it took about 21 hours to inject about 40 L of seawater.

When seawater is injected, a significant part of Mg ²⁺ having a low atomic number among the negative ion elements and +1 charged cations and alkaline earth metal elements is not adsorbed to the resin and is removed.

The main purpose of the washing solution injection after sample injection was to remove Ca, and a 1:1 mixture of about 2M ammonium acetate (NH ₄ CH ₃ CO ₂ ) and methanol was used. In this process, some adsorbed Mg and most of Ca are removed.

As the injection amount of the cleaning solution increases, the Ca removal rate approaches 100%, but the Sr loss gradually increases. Therefore, it is necessary to select an appropriate amount of cleaning solution that can remove Ca as much as possible and minimize Sr loss.

About 95% or more of Ca was removed from 3.1 L of the washing solution, and the loss of Sr was within about 10%.

For final Sr recovery, 2M ammonium acetate (NH ₄ CH ₃ CO ₂ ) was used.

Here, hydrochloric acid or other saline solutions including ammonium can be used as an eluent for Sr, but since elution using strong acid recovers all cations, an additional separation process for Sr is required and a large amount of strong acid must be treated.

In addition, 2M ammonium acetate (NH ₄ CH ₃ CO ₂ ) has a similar washing solution and solution composition compared to other salts, and has the advantage of high selectivity for Sr elution, and the optimal elution amount is about 4.8 L in the resin standard used (internal diameter: 9 cm, height: 26 cm).

In the present invention, the technical core is to accurately inject the injection amount of the separation solution as well as the seawater sample into the resin. Prior to starting the entire separation process, the separation solution (activation, Ca removal, Sr recovery) used for separation of the seawater sample and Sr was accurately measured and injected into each solution box as an automatic separation preparation step.

To prepare the column part, the hydrated cation exchange resin was filled in a circular acrylic column (outer diameter, inner diameter, height (cm): 10 × 9 × 40) to a height of about 26 cm, and then the upper lid was fastened.

In the preparation step of the separation device, after turning on the main power, select the second solution selection valve, that is, the flow path of the second solution selection unit 500 as the first (waste liquid) flow path, and then select the first solution selection valve, that is, the first solution selecting unit 200, as the first flow path (activation solution), operate the tubing pump, and when the solution is injected up to the first solution selection valve, change the flow path to No. 2 to select the seawater sample, and then select the third flow path to prepare the washing liquid, Finally, select flow path 4 to inject the Sr-eluent to the selection valve, and return the flow path to flow path 1 to complete all preparations.

Next, automatic separation proceeds with pressing the automatic separation operation button on the control panel. Starting with the resin activating solution, along with the operation of the tubing pump, seawater sample, cleaning solution, and final strontium elution solution (Sr-elution solution) are sequentially injected along with the flow path change of the first solution selection valve.

At this time, the control for each solution injection is carried out by the first solution selection valve, i.e., the first solution selection unit 200 and the flow rate sensors (first and second photoelectric sensors) installed between the plurality of solution containers detect the inflow of air after all the solutions are injected, and send this signal to the first solution selection valve to switch to the next solution.

The suction tubing that sucks each solution uses a screw tubing clamp coupled to the lid of the solution container, so that the end of the suction tubing is fixedly positioned on the bottom of the container so that all the solutions in the container are injected while the pump is running. In the case of seawater samples, as a large container with a deep depth is used, a tubing guide pipe is installed on the upper wall of the container so that the long suction tubing can be stably adhered to the bottom of the container when injected.

In addition, in the present invention, in order to recover the Sr-eluate, when the final Sr-eluate is injected and the flow path of the first solution selection valve is switched to No. 4, the flow path of the second solution selection valve is switched to No. 2 at the same time.

At this time, the first and second photoelectric sensors used in this case are arranged in series so that a switching signal is transmitted to the valve only when a signal is received from two at the same time in order to prevent malfunction due to one momentary air bubble, thereby improving the safety of operation. In the case of the solution connector (first to fourth suction tubing), it can also be applied to some translucent Teflon tubing, so it can be applied to all tubing of various sizes and materials.

In addition, according to the present invention, as a large amount of resin is used and the structure of the resin is changed due to a change in the chemical composition of the injection solution, a difference in inflow and discharge may occur in some solutions due to a change in the pore size between resins. As a result, since pressure in the column part 400 and solution leakage may occur due to this, a water level sensor capable of measuring the height of the solution is installed at the top of the column part 400 to prevent this, when the solution increases above a certain level, It is an automatic separation device including the safety of the separation system that operates automatically by stopping the operation of the tubing pump.

Here, the tubing pump, that is, the pump unit 700, is a speed-adjustable pump capable of supplying up to about 50 mL per minute. As the principle of transporting the solution in one direction using pressure created by compressing the elastic tubing while the rollers of the pump rotate, the elastic tubing for the pump is applicable to about 2M hydrochloric acid and about 50% methanol solutions by using tubing that can also be used for acid solutions and organic solvents.

The control unit of the present invention is fixed to the panel and consists of a main power circuit breaker, a tubing pump operation and speed controller, a primary solution selector (first solution selector) selection, a secondary solution selector (second solution selector) selection, and an automatic separation operation button. Since the pump operates only when the solution in the tubing is filled during initial solution injection, a process of injecting each solution into the tubing using the control unit before the start of automatic separation is required, and this can be easily operated from the control unit. .

Since the cation exchange resin used in the present invention has very high physical and chemical safety under strong acid and organic solvent conditions, it can be regenerated and activated by removing some of the cations remaining in the resin with about 2M hydrochloric acid after Sr separation is completed, so that it can be used repeatedly as long as the recovery rate for Sr does not decrease.

As described above, in the present invention, after injection of the resin activating liquid, the seawater sample, and the washing liquid into the column unit containing the cation exchange resin is completed, the strontium eluate is injected into the column unit to obtain the recovered strontium solution, thereby enabling automation to safely and quickly separate radioactive strontium (Sr-90) from seawater and increase the efficiency of the separation.

3 is a flowchart illustrating a method for separating radioactive strontium from seawater according to an embodiment of the present invention.

As shown in FIG. 3, in the present invention, the resin activating liquid, the seawater sample, the cleaning liquid, and the strontium eluate, which are separately contained in a plurality of solution containers, can be filled into the suction tubing connected between the solution container and the first solution selector, respectively (S10).

Subsequently, the present invention may check whether a user input requesting separation of strontium is received (S20).

Next, in the present invention, when a user input requesting separation of strontium is received, the first solution selector is controlled to select the resin activating liquid, and the second solution selector is controlled to select the waste liquid of the column unit at the same time, and the pump unit is controlled to transfer and inject the selected resin activating liquid into the column unit (S30).

And, in the present invention, it is possible to check whether injection of the resin activating liquid has been completed (S40).

Here, in the present invention, based on the first sensing signal for primarily detecting the flow of the resin activating liquid in the suction tubing and the second sensing signal for secondarily detecting the first detected flow of the resin activating liquid, whether or not injection of the resin activating liquid is completed can be confirmed.

Subsequently, in the present invention, when the injection of the resin activating liquid is completed, the first solution selection unit may be controlled to select a seawater sample, and the pump unit may be controlled to transport and inject the selected seawater sample into the column unit (S50).

Next, the present invention can check whether the injection of the seawater sample has been completed (S60).

Here, in the present invention, based on the first sensing signal for firstly detecting the flow of the seawater sample in the suction tubing and the second sensing signal for secondarily sensing the flow of the firstly sensed seawater sample, whether or not the seawater sample is injected can be confirmed.

In the present invention, when the injection of the seawater sample is completed, the first solution selector may be controlled to select the washing solution, and the pump may be controlled to transport and inject the selected washing solution into the column unit (S70).

Subsequently, the present invention may check whether the injection of the washing solution is completed (S80).

Here, according to the present invention, it is possible to determine whether or not the injection of the washing liquid is completed based on a first sensing signal for primarily detecting the flow of the washing liquid in the suction tubing and a second sensing signal for secondarily detecting the primarily detected flow of the washing liquid.

Next, in the present invention, when the injection of the cleaning solution is completed, the first solution selector is controlled to select the strontium elution solution, and the second solution selector is controlled to select the strontium recovery solution of the column unit at the same time, and the pump unit is controlled to transfer and inject the selected strontium elution solution into the column unit (S90).

And, in the present invention, it is possible to check whether the injection of the strontium elution solution is completed (S100).

Here, in the present invention, based on the first sensing signal for primarily detecting the flow of the strontium eluate in the suction tubing and the second sensing signal for secondarily sensing the flow of the strontium eluate that has been primarily sensed, it is possible to check whether the injection of the strontium eluate has been completed.

Next, in the present invention, when the injection of the strontium eluate is completed, the strontium separation and recovery process can be completed (S110).

Accordingly, in the present invention, the separation of Sr-90 from a 40L seawater sample is performed automatically in the automatic separation step through the initial sample, separation solution, column preparation step, and automatic separation device operability check step, and Sr separation is completed. An example for this is as follows.

1st process (sample, separation solution and column part preparation step)

After filtering the collected seawater using a 5C filter paper to remove residues, 40L is placed in a Teflon-coated stainless sample box, and then 80mL of strong hydrochloric acid is added to adjust the solution composition to 0.2M hydrochloric acid.

In addition, 0.2M HCl-5L of the activation solution used in the column separation process, washing solution (2M ammonium acetate (NH ₄ CH ₃ CO ₂ ) and methanol mixture (1:1))-3.1L, and Sr-eluent-4.8L were filled into each solution box, and hydrated cation exchange resin (Dowex 50W-8X, 100-150 mesh) was placed in a large acrylic column part (outer diameter, inner diameter, Height (cm): 10 × 9 × 40) after filling to a height of 26 cm, connect the upper part of the column part.

Next, after fixing the injection solution (activation solution, sample, washing solution, Sr-eluent solution) by adjusting the depth so that the bottom of the suction tubing is located at the bottom of the container, it is connected to a Teflon solution tubing (1/8 "), and these solution tubings are precisely positioned between the two photoelectric sensors.

2nd process (operability check step)

After preparing the resin and injection solution required for column separation through the first process, turn on the main power on the control panel, and then use the manual operation button on the control panel to operate the pump and set the solution injection speed to 30 ml/min.

3rd process (automatic separation step)

After confirming the operability in the second process, the flow path of the 1st solution selection valve is changed sequentially with the pump operation, filling the activating solution, sample, washing solution, and elution solution up to the front of the 1st solution selection valve, and then operating the automatic separation action button.

In the automatic separation process, along with the operation of the tubing pump, an activation solution (0.2M HCl - 5L) is injected along flow path 1 at a rate of 30 ml/min for about 170 minutes, and the chemical form at the end of the reactor of the cation exchange resin is converted to H ⁺ form, and the composition is changed so that cations can be adsorbed.

When all the solutions in the activating liquid container are injected, the air continuously travels through the tube to the photoelectric sensor (PES-1), sends the detected signal to the primary solution selection valve, and switches the connection path of the valve to No. 2.

Accordingly, seawater sample injection starts and it takes about 21 hours to inject all 40L.

Through this process, a large amount of anions, +1 valent cations, and a significant amount of Mg ²⁺ in seawater are added to the resin. It is removed without being adsorbed.

After all the seawater in the sample container is injected, the first solution selection valve flow path is switched to number 3 in the same manner as in the previous step, and a 1:1 mixed solution of 2M ammonium acetate (NH ₄ CH ₃ CO ₂ ) and methanol (CH ₃ OH) is injected. In this process, some Mg ²⁺ and most of Ca ²⁺ adsorbed during the sample injection process are removed.

After 3.1 L of washing liquid is injected for about 100 minutes, the first solution selection valve flow path is switched to No. 4, and upon receiving this signal, the second solution selection valve is switched to No. 2 flow path, and the injection and recovery of 4.8 L of 2M ammonium acetate (NH ₄ CH ₃ CO ₂ ) begins.

The recovery and separation of Sr from the recovered eluate requires additional work through carbonate precipitation and nitrate precipitation, but most of the chemical separation of large-capacity seawater is completed through this automated process.

4th process (resin regeneration step)

After the Sr separation is completed in the column part through the third process (automatic separation step), about 4 L of 2M hydrochloric acid solution is manually injected into the used resin to remove some of the cation elements remaining in the cation exchange resin. The next process can be started with a regeneration process used for the next sample separation.

As described above, the present invention can safely and quickly separate radioactive strontium (Sr-90) from seawater and increase the efficiency of the separation by injecting the strontium eluate into the column portion to obtain a recovered strontium solution after the resin activating solution, the seawater sample, and the cleaning solution are sequentially injected into the column portion containing the cation exchange resin.

The features, structures, effects, etc. described in the present inventions above are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, the features, structures, and effects illustrated in each embodiment can be combined or modified with respect to other embodiments by those skilled in the art in the field to which the embodiments belong. Therefore, contents related to these combinations and variations should be construed as being included in the scope of the present invention.

In addition, although the embodiments have been described above, these are only examples and do not limit the present invention, and those skilled in the art to which the present invention belongs will be able to know that various modifications and applications not exemplified above are possible without departing from the essential characteristics of the present embodiment. For example, each component specifically shown in the embodiment can be modified and implemented. And differences related to these modifications and applications should be construed as being included in the scope of the present invention as defined in the appended claims.

The present invention has industrial applicability in that it is possible to safely and quickly separate radioactive strontium (Sr-90) from seawater and to increase the efficiency of the separation by obtaining a recovered strontium solution by injecting a strontium elution solution into the column portion after completion of sequentially injecting the resin activating solution, the seawater sample, and the washing solution into the column portion containing the cation exchange resin.

Claims (10)

1. A first transfer unit for transporting the resin activating liquid, the seawater sample, the washing liquid, and the strontium eluate, which are separately contained in a plurality of solution containers;

   a first solution selection unit that is connected to the first transfer unit and selects one of the resin activating liquid, the seawater sample, the cleaning liquid, and the strontium eluate;

   a second transfer unit connected to the first solution selector and transporting the solution selected from the first solution selector;

   a column unit containing a predetermined amount of cation exchange resin in advance and injecting the solution transferred from the second transfer unit;

   a second solution selection unit connected to the column unit to select waste liquid or strontium recovery liquid;

   a third transfer unit connected to the second solution selection unit and transporting the waste liquid or the strontium recovery liquid to a recovery container;

   a pump unit that is connected to the second transfer unit and transfers the solution; and,

   A control unit for controlling the first and second solution selectors and the pump unit;

   The control unit,

   The first and second solution selection portions and pumps are controlled to inject the waste solution from the column unit sequentially injecting the resin activation solution, seawater sample, and the washing liquid, and when the resin activation solution, seawater sample, and the washing liquid are injected into the column portion sequentially, the strone lithium dissolution liquid is injected into the column unit. Thus, the first and second solution selection portion and the pump part are controlled to discharge the strontium recovery solution from the column unit, characterized in that the radioactive strontium -separated device.
2. According to claim 1,

   a first solution container containing the resin activating solution;

   A second solution container containing the seawater sample;

   a third solution container containing the washing solution; and,

   The apparatus for separating radioactive strontium in seawater, characterized in that it further comprises a solution container unit including a fourth solution container containing the strontium elution solution.
3. According to claim 2,

   The resin activating solution,

   0.2M HCl,

   The washing liquid is

   It includes a washing solution in which 2M ammonium acetate (NH ₄ CH ₃ CO ₂ ) and methanol are mixed in a 1:1 ratio,

   The strontium eluate,

   An apparatus for separating radioactive strontium in seawater, comprising 2M ammonium acetate (NH ₄ CH ₃ CO ₂ ).
4. According to claim 2,

   The first transfer part,

   a first suction tubing inserted into the first solution container and transporting the resin activating liquid to the first solution selector;

   a second suction tubing inserted into the second solution container and transporting the seawater sample to the first solution selector;

   a third suction tubing that is inserted into the third solution container and transfers the cleaning solution to the first solution selector; and,

   and a fourth suction tubing inserted into the fourth solution container to transport the strontium eluate to the first solution selector.
5. According to claim 1,

   a first sensor unit sensing a flow of the solution flowing in the first transfer unit; and,

   Further comprising a second sensor unit for detecting the level of the solution contained in the column unit,

   The control unit,

   Controlling the first and second solution selection units and the pump unit by determining whether the transfer of the solution contained in the solution container is completed based on the sensing signal received from the first sensor unit;

   Radioactive strontium separation device in seawater, characterized in that for controlling the pump unit by determining the level of the solution contained in the column unit based on the sensing signal received from the second sensor unit.
6. According to claim 5,

   The first sensor unit,

   a first photoelectric sensor disposed around the suction tubing of the first transfer unit to primarily sense the flow of the solution; and,

   A device for separating radioactive strontium in seawater, characterized in that it comprises a second photoelectric sensor disposed around the suction tubing of the first transfer unit to be spaced apart from the first photoelectric sensor by a predetermined distance and secondarily detecting the flow of the firstly sensed solution.
7. According to claim 5,

   The second sensor unit,

   Radioactive strontium separation device in seawater, characterized in that it comprises a water level sensor inserted at the top of the column unit to detect the level of the solution injected into the column unit.
8. According to claim 1,

   The control unit,

   When a user input requesting separation of strontium is received, the first solution selector controls the first solution selector to select the resin activating liquid and the second solution selector controls the second solution selector to select the waste liquid of the column part at the same time, controls the pump part to transfer and injects the selected resin activating liquid into the column part, controls the first solution selector to select the seawater sample when the injection of the resin activating liquid is completed, controls the pump part to transfer and injects the selected seawater sample into the column part, and controls the pump unit to transfer and inject the selected seawater sample into the column part. The first solution selector controls the first solution selector to select the washing solution, controls the pump unit to transfer and injects the selected wash solution into the column unit, controls the first solution selector to select the strontium eluate when the injection of the wash solution is completed, and simultaneously controls the second solution selector to select the strontium recovery solution of the column unit, controls the pump unit to transfer and injects the selected strontium eluate into the column unit, and controls the pump unit to transfer and inject the selected strontium eluate into the column unit. An apparatus for separating radioactive strontium in seawater, characterized in that it completes separation and recovery of rontium.
9. According to claim 8,

   The control unit,

   Prior to receiving a user input requesting separation of strontium, the resin activating solution, the seawater sample, the cleaning solution, and the strontium eluate contained in the plurality of solution containers are filled into the suction tubing of the first transfer unit up to the front end of the first solution selection unit. Radioactive strontium separation device in seawater, characterized in that.
10. A method for separating radioactive strontium from seawater in an apparatus for separating radioactive strontium from seawater, including a control unit for controlling first and second solution selectors and a pump unit,

    (a) when the control unit receives a user input requesting separation of strontium, controlling the first solution selector to select the resin activating liquid and simultaneously controlling the second solution selector to select the waste liquid of the column unit, and controlling the pump unit to transfer and inject the selected resin activating liquid into the column unit;

    (b) controlling, by the control unit, the first solution selection unit to select the seawater sample when the injection of the resin activating liquid is completed, and controlling the pump unit to transport and inject the selected seawater sample into the column unit;

    (c) controlling, by the controller, the first solution selection unit to select the washing liquid when the injection of the seawater sample is completed, and controlling the pump unit to transport and inject the selected washing liquid into the column unit;

    (d) when the injection of the cleaning solution is completed, the controller controls the first solution selector to select the strontium eluted solution and at the same time controls the second solution selector to select the strontium recovery solution of the column unit, and controls the pump unit to transfer and inject the selected strontium eluted solution into the column unit; and

    (e) the controller completes the separation and recovery of strontium when the injection of the strontium eluate is completed.

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