WO2024025067A1 - Decontamination system and decontamination method using gas hydrate - Google Patents

Abstract

The present invention relates to a decontamination system and a decontamination method using gas hydrate that can be applied to an ultra-mega ship to store and decontaminate large quantities of radioactive water, the system comprising: a contaminated water supply module supplying contaminated water filled in a first cargo tank and containing hypersaline and high-concentration radioactive materials; a gas hydrate forming module that forms gas hydrate by injecting gas into the contaminated water supplied from the contaminated water supply module; a solid-liquid separation module that forms the gas hydrate formed by means of the gas hydrate forming module into a pellet shape and separates same from radioactive materials; a washing module that washes the pellets; a dissociation module that separates water molecules and gas from the pellets washed by the washing module; and a radioactive material storage module that stores the radioactive materials separated in the solid-liquid separation module. This configuration can dramatically reduce the cost and time of manufacturing a decontamination plant.

Description

Decontamination system and method using gas hydrate

The present invention relates to a decontamination system and decontamination method using gas hydrate, which is portable and capable of storing and decontaminating large quantities of radioactive contaminated water. In particular, the gas hydrate is converted into water and gas at a constant temperature and pressure. It relates to a decontamination system and decontamination method using gas hydrate that can store and decontaminate large quantities of radioactive contaminated water by artificially constructing the physical phenomenon in which contaminants in water are naturally discharged when created and applying it to very large ships.

In general, clathrate hydrate is a crystalline compound that physically captures and traps guest molecules without chemical bonding in a three-dimensional lattice structure formed by host molecules through hydrogen bonding. says If the host molecule is a water molecule and the guest molecule is a low-molecular gas molecule such as methane, ethane, propane, or carbon dioxide, it is called a gas hydrate.

Currently, more than 100 types of gas molecules are known to form hydrates, and methane (CH ₄ ) combines with water molecules (H ₂ O) at 4°C and about 30 atmospheres to form gas hydrates, and HFC-based gases are used. It is possible to form gas hydrate even at a much lower pressure (approximately 2 to 3 atmospheres at 4°C).

Various methods and devices have been developed to artificially produce these gas hydrates, and since they have properties that can be applied to various industrial fields, much research has been conducted recently. Research is largely being conducted on securing fluid fluidity, recovery as an energy resource, climate change response technology, gas transportation and storage, and safety related to each of these fields. For example, technologies for gas transportation and storage on large ships are also being developed.

Meanwhile, there is a need to increase public safety in response to the occurrence of serious nuclear accidents in nuclear power plant areas and the discharge of marine polluted water. Northeast Asia is a globally concentrated area of the nuclear industry, and is required to respond to disasters caused by serious nuclear accidents such as the Fukushima nuclear accident in Japan. Anxiety about this is increasing. The accident at Japan's Fukushima nuclear power plant that occurred in March 2011 has not been resolved to this day, and the radioactive contaminated water generated from the accident nuclear power plant is due to the complexity and performance limitations of the Japanese government's radioactive contaminated water treatment method, the Multinuclide Removal System (ALPS). Due to this problem, radioactive contaminated water is about to be discharged into the sea.

The method of treating radioactive contaminated water using a multi-nuclide removal facility involves complex treatment processes such as precipitation/adsorption/membrane separation, requires removal of each nuclide through multiple processes, and generates secondary waste during the treatment of radioactive contaminated water. There are problems such as rapidly increasing time and costs, so it is necessary to come up with fundamental and groundbreaking technological alternatives to solve these problems.

An example of a technology to solve this problem is disclosed in Patent Documents 1 to 3 below.

For example, Patent Document 1 (Japanese Patent Application Publication No. 2013-92415, published on May 16, 2013) discloses that water contaminated with radioactive substances and one or two or more types of gas that can form gas hydrates are mixed at a temperature higher than the freezing point of the water. A process of obtaining a gas hydrate suspended in the water by contacting the gas hydrate under temperature and conditions to form a gas hydrate, and a process of washing radioactive substances and other impurities adhering to the outer wall of the gas hydrate with washing water while substantially maintaining the gas hydrate state. , In this order, it includes the process of separating the washing water and gas hydrate while maintaining the gas hydrate state, and the process of turning the gas hydrate into water and gas with radioactive substances removed or reduced by applying a higher temperature or lower pressure than the gas hydrate state. A method for removing or reducing radioactive materials from water contaminated with radioactive materials is disclosed.

In addition, Patent Document 2 (Korean Patent Publication No. 10-2237252, registered on April 1, 2021) discloses that liquefied gas stored in a liquefied gas storage tank is regasified to generate regasified gas, and evaporation gas generated from the liquefied gas storage tank is disclosed. And a regasification device including a re-condenser for re-condensing the liquefied gas, and a desalination device for desalinating sea water, wherein the desalination device generates gas hydrate from the sea water through guest gas and cold heat supplied from the sea water. It includes a hydrate device and a dissociation device that receives and dissociates the gas hydrate from the hydrate device, and supplies the guest gas remaining in the hydrate device or the gas dissociated from the dissociation device to the re-condenser or the liquefied gas storage tank. A gas regasification system is disclosed.

On the other hand, Patent Document 3 (Korean Patent Publication No. 10-1978880, registered on May 9, 2019) discloses a ship body, a liquefaction system for receiving a feed gas containing an acidic gas from the outside of the ship body and liquefying or hydrating the acidic gas; A hydration unit, a storage tank for receiving and storing the liquefied or hydrated product from the liquefaction and hydration unit, and a pretreatment process provided upstream of the liquefaction and hydration unit to remove impurities other than acid gas from the feed gas. Disclosed is an acid gas treatment vessel containing a part.

Patent Document 1 as described above discloses a technology for removing or reducing radioactive materials from water contaminated with radioactive materials and simultaneously reducing the amount of concentrated radioactive material content, but the radiation is continuously applied to the contaminated water. There was a problem that radioactive materials could not be removed or reduced.

In addition, Patent Document 2 discloses a hydrate device that generates seawater into gas hydrate through cold heat supplied from seawater in an LNG carrier, and a dissociation device that receives the gas hydrate from the hydrate device and dissociates it, and the patent document 3 discloses the configuration of a liquefaction and hydration unit that liquefies or hydrates an acidic gas provided in the hull, but Patent Documents 2 and 3 do not disclose a technology for decontamination of contaminated water containing radionuclides. .

The purpose of the present invention is to solve the problems described above, and to decontaminate radioactive contaminated water using ultra-large ships such as Very Large Crude Oil Carriers (VLCCs), which are scheduled to be decommissioned due to international oversupply. To provide a decontamination system and method using gas hydrate that can dramatically reduce production costs and time.

Another object of the present invention is to provide a decontamination system and method using gas hydrate that can be installed on a very large ship to enable sea movement and to effectively respond to international crisis situations such as responding to future nuclear power plant accidents.

Another object of the present invention is to provide a decontamination system and method using gas hydrate that can simultaneously remove polynuclear radioactive contaminated water and can be applied even under high-concentration salt seawater conditions.

Another object of the present invention is to provide a decontamination system and method using gas hydrate that can dramatically reduce the amount of secondary waste generated by utilizing a crystallization method.

Another object of the present invention is to provide a decontamination system and method using gas hydrate that are easy to operate and maintain by developing each process for decontamination in a modular form and installing it on a very large ship.

In order to achieve the above object, the decontamination system using gas hydrate according to the present invention can be operated at sea and is installed in a very large ship equipped with a plurality of compartmentalized cargo tanks and a pump that can fill each cargo tank with contaminated water. A system for mass storage and decontamination of contaminated water from a radioactive leak using a gas hydrate, a contaminated water supply module that is stored in a first cargo tank and supplies contaminated water containing high salt and high concentration of radioactive materials, and the contaminated water supply module A gas hydrate formation module that injects gas into supplied contaminated water to form gas hydrate, a solid-liquid separation module that separates the gas hydrate formed by the gas hydrate formation module into pellets from radioactive materials, and a washing unit that cleans the pellets. It is characterized in that it includes a module, a dissociation module that separates water molecules and gases from the pellet washed by the washing module, and a radioactive material storage module that stores the radioactive material separated in the solid-liquid separation module.

In addition, in the decontamination system using gas hydrate according to the present invention, a gas injection and recovery module for injecting gas into the gas hydrate formation module and recovering the gas from the dissociation module, and measuring the concentration of water molecules dissociated from the dissociation module It is characterized in that it further includes a discharge module for discharging water to the sea.

In addition, in the decontamination system using gas hydrate according to the present invention, the gas hydrate formation module and the dissociation module are respectively provided in the second cargo tank and the third cargo tank adjacent to each other, and the gas hydrate formation module, solid-liquid separation module, and washing module and the operation of the dissociation module is characterized in that it is executed continuously.

In addition, in the decontamination system using gas hydrate according to the present invention, the gas hydrate formation module, solid-liquid separation module, washing module, and dissociation module are each provided in plural numbers in the second cargo tank and the third cargo tank.

Additionally, in the decontamination system using gas hydrate according to the present invention, the gas is HFC134a.

In addition, in the decontamination system using gas hydrate according to the present invention, the gas hydrate formation module and dissociation module remove cesium (Cs ⁺ ), strontium (Sr ²⁺ ), and cobalt (Co ²⁺ ) from contaminated water containing the radioactive material. , It is characterized by simultaneously removing foreign substances in addition to pure water containing iodine (I ^- ).

In addition, in the decontamination system using gas hydrate according to the present invention, the second cargo tank provided with the gas hydrate formation module is maintained at a constant temperature and pressure, and the third cargo tank provided with the dissociation module is maintained at room temperature and pressure. It is characterized by

In addition, in the decontamination system using gas hydrate according to the present invention, the pellets formed in the solid-liquid separation module are transported to the dissociation module by a screw conveyor.

In addition, in the decontamination system using gas hydrate according to the present invention, the washing module is provided with three or more fine spray nozzles, and the washing water used in the washing module is pure water formed by the dissociation module or discharge module. do.

In addition, the decontamination system using gas hydrate according to the present invention further includes a heat exchanger module that exchanges temperature between gas hydrate formation in the gas hydrate formation module and dissociation in the dissociation module.

In addition, in the decontamination system using gas hydrate according to the present invention, the first cargo tank is provided with a larger capacity than the second cargo tank and the third cargo tank, and tritium contained in the contaminated water is stored in the first cargo tank. It is characterized by being removed.

In addition, in order to achieve the above object, the decontamination method using gas hydrate according to the present invention is a method of storing and decontaminating large quantities of contaminated water from radioactive leaks, including (a) a plurality of cargo tanks that can be operated at sea and are partitioned, and each Step (b) storing contaminated water containing high salt and high concentration radioactive materials in a first cargo tank, which is a buffer tank, by a pump provided in the pump room in a very large ship that can fill the cargo tank with contaminated water, (b) the above step ( (a) supplying the contaminated water stored in step (b) to the gas hydrate formation module of the second cargo tank, (c) supplying HFC134a gas to the gas hydrate formation module, (d) to the contaminated water supplied in step (b). For example, forming a gas hydrate in the gas hydrate formation module using the HFC134a gas supplied in step (c), (e) pelletizing the gas hydrate formed in step (d) to separate radioactive materials and foreign substances. Step (f) comprising the step of dissociating the pellets formed in step (e) in a third cargo tank adjacent to the second cargo tank.

In addition, in the decontamination method using gas hydrate according to the present invention, (g) measuring the radioactivity concentration of the pure water dissociated in step (f), and if the radioactivity concentration is within the allowable range, discharging it into the sea is further added. It is characterized by including.

In addition, in the decontamination method using gas hydrate according to the present invention, steps (a) to (f) are performed continuously.

As described above, according to the decontamination system and decontamination method using gas hydrate according to the present invention, each component for recycling very large ships scheduled to be decommissioned and decontamination of contaminated water from radioactive leaks is installed in a module form in a plurality of cargo tanks. Since it is prepared and installed on a very large ship, the cost and time for manufacturing a radioactive contaminated water decontamination plant are reduced, and operation and maintenance are easy.

In addition, according to the decontamination system and decontamination method using gas hydrate according to the present invention, a radioactive contaminated water decontamination plant is installed on a very large ship scheduled to be decommissioned, so the advantage of the ship is that it is portable and can respond quickly to radioactive leakage accidents. obtained.

In addition, according to the decontamination system and method using gas hydrate according to the present invention, it can be applied even in high-concentration salt seawater conditions, and the effect of dramatically reducing the amount of secondary waste generated for treating radioactive contaminated water is obtained.

1 is an explanatory diagram of the gas hydrate structure produced by the present invention;

Figure 2 is a schematic structural diagram of a very large ship applied to the present invention;

Figure 3 is a schematic configuration diagram of a decontamination system using gas hydrate according to the present invention;

Figure 4 is a diagram showing an example of the configuration of a decontamination system using the gas hydrate shown in Figure 3;

Figure 5 is a photograph of HFC134a hydrate formation for treatment of seawater and radioactive contaminated water according to the present invention;

Figure 6 is a graph showing the results of a removal rate experiment (simultaneous removal rate) of seawater and radioactive contaminated water according to the present invention;

Figure 7 is a flowchart illustrating the process of decontamination of contaminated water from a radioactive leak accident according to the present invention.

The above and other objects and new features of the present invention will become more clear by the description of this specification and the accompanying drawings.

As used herein, the term “module,” “unit,” or “unit” performs at least one function or operation and may be implemented as hardware or software consisting of a mechanical or electrical or electronic configuration, or as a combination of hardware and software. In addition, a plurality of “modules” or a plurality of “units” may be integrated into at least one module and implemented with at least one processor, except for “modules” or “units” that need to be implemented with specific hardware.

Meanwhile, the term "very large ship" used herein refers to a ship such as a Very Large Crude Oil Carrier (VLCC) or Ultra Large Crude Oil Carrier (ULCC), which is a very large crude oil carrier, and is used at sea. Medium-sized or larger ships equipped with multiple navigable, compartmentalized cargo tanks and pumps to fill them also fall into this category. “Decontamination” means removing contamination by radioactive elements such as cesium (Cs ⁺ ), strontium (Sr ²⁺ ), cobalt (Co ²⁺ ), iodine (I ^- ), etc.

The present invention solves the disadvantages of existing radioactive contaminated water treatment technologies such as evaporation, membrane separation, and ion exchange, which require large and complex equipment and low decontamination performance, and treats secondary radioactive waste generated from filters and ion exchange resins. Gas hydrate technology is applied to prevent adverse effects caused by . In other words, the “Gas Hydrate” produced by the present invention is a state in which gas molecules (HFC134a) and water molecules (pure water) are physically combined, as shown in Figure 1, and gas molecules are present in the water lattice. This is the structure where is stored. 1 is an explanatory diagram of the gas hydrate structure produced by the present invention.

Therefore, the present invention provides a technology that can be applied even under conditions of simultaneous removal of radioactive polynuclear contaminated water and high-concentration salt seawater, and can dramatically reduce the amount of secondary waste generated by utilizing a determination method without pretreatment.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

The structure of a very large ship applied to the present invention will be described with reference to FIG. 2.

Figure 2 is a schematic structural diagram of a very large ship applied to the present invention.

As shown in FIG. 2, the ultra-large ship applied to the present invention is capable of operating at sea and has a separation tower (10), an engine room (20), a pump room (30), a cargo deck line (40), and a plurality of partitioned Very Large Crude Oil Carrier (VLCC) equipped with cargo tanks (51~59), screw conveyor (60), contaminated water supply pipe line (70), gas recovery pipe line (80), and discharge pipe line (90). ) or ULCC (Ultra Large Crude Oil Carrier) may be applied.

That is, for example, a gas hydrate decontamination plant can be built for a very large crude oil carrier that is scheduled to be decommissioned and converted into a mobile VLCC gas hydrate decontamination plant. As a very large ship, VLCC is the name for an oil tanker weighing more than 150,000 tons, and ULCC is used as a name for an oil tanker weighing more than 400,000 tons.

The separation tower 10 is provided with the function of removing all moisture that may contaminate the ship's oil storage facility, the engine room 20 is provided to control the engine and each module related to the ship's operation, and the pump room 30 ) is used to fill or empty each carco tank (51 to 59) through the pump and cargo deck line (40), contaminated water supply pipe line (70), gas recovery pipe line (80), and discharge pipe line (90). It is prepared.

The cargo tanks 51 to 59 are divided into multiple compartments to prevent fluctuations in the liquid level during the operation of the ship. For example, liquefied natural gas (LNG) liquefied at ultra-low temperature in an LNG carrier ) as a structure for storing and storing LNG. Since LNG has a vapor pressure higher than atmospheric pressure and a boiling temperature of approximately -163°C, it must be formed of a material that can withstand ultra-low temperatures in order to safely store and store such LNG. there is. That is, the cargo tank is made of, for example, aluminum steel, stainless steel, 35% nickel steel, etc., is resistant to other thermal stresses and heat shrinkage, and is formed with an insulating structure that can prevent heat intrusion.

For example, as shown in FIG. 2, the cargo tanks 51 to 59 in the decontamination system using gas hydrate according to the present invention are used to store contaminated water containing high salt and high concentration of radioactive materials due to a radioactive leak accident. A first cargo tank 51 used as a buffer tank for the gas hydrate, a second cargo tank 52 and a fifth cargo tank 55 for forming gas hydrate, and a third cargo tank 55 for separating water molecules and gas and storing water molecules. It may be provided with a cargo tank 53, a fourth cargo tank 54, and a sixth cargo tank 56 for storing radioactive materials. Meanwhile, in the above description, the structure of six cargo tanks is shown for convenience, but this is limited. As shown in FIG. 2, the cargo tank may be provided in a structure of seven or more. In other words, it is possible to provide the function of storing contaminated water and operating a decontamination system by operating additional cargo tanks (57 to 59). In addition, the first cargo tank 51 may be partitioned into a larger capacity than other cargo tanks in order to have the function of storing a large amount of radioactive contaminated water for a long time. For example, substances with a relatively short radioactivity half-life, such as tritium, are not removed not only in the gas hydrate process but also in various processes such as evaporation, membrane separation, and ion exchange, so the radiation dose of the corresponding nuclide must be reduced over a long period of storage time. This is to reduce it naturally during the period. Meanwhile, the above-described first to sixth cargo tanks are shown separately for convenience of explanation, and each of the first to sixth cargo tanks may be provided as two or more cargo tanks.

Next, a system for decontamination of contaminated water from a radioactive leak accident according to the present invention in a very large ship as shown in FIG. 2 will be described with reference to FIGS. 3 and 4.

Figure 3 is a schematic configuration diagram of a decontamination system using a gas hydrate according to the present invention, and Figure 4 is a diagram showing an example of the configuration of a decontamination system using a gas hydrate shown in Figure 3, as shown in Figure 4. Contaminated water treatment can be maximized by performing parallel and sequential treatment of contaminated water by repeating the module configuration n times in the remaining space of each cargo tank.

As shown in FIGS. 2 to 4, the decontamination system using gas hydrate according to the present invention uses gas hydrate in a very large ship capable of operating at sea and equipped with a plurality of compartmentalized cargo tanks 51 to 59. A system for storing and decontaminating large quantities of contaminated water from radioactive leaks, including a contaminated water supply module (100) that supplies contaminated water containing highly salty and highly concentrated radioactive materials caused by radioactive leaks, and supplied from the contaminated water supply module (100). A gas hydrate formation module 200 that injects gas into contaminated water to form gas hydrate, and a solid-liquid separation module 300 that forms the gas hydrate formed by the gas hydrate formation module 200 into a pellet shape and separates it from radioactive materials. ), a washing module 400 for washing the pellets, a dissociation module 500 for separating water molecules and gases for the pellets washed by the washing module 400, and radioactive substances separated in the solid-liquid separation module 300. A radioactive material storage module 600 that stores the material, a discharge module 700 that measures the concentration of the water molecules dissociated in the dissociation module 500 and discharges them to the sea, injects gas into the gas hydrate formation module and dissociates the water molecules. It may include a gas injection and recovery module 800 that recovers the gas from the module, and a heat exchanger module 900 that exchanges temperature between the gas hydrate formation and dissociation. Additionally, each of the modules 100 to 900 described above may include a control module that controls each operation and condition.

For example, the contaminated water supply module 100 supplies radioactive contaminated water (1.25 million tons) stored following the accident at the Fukushima nuclear power plant in Japan, which occurred in March 2011, to a very large ship, as shown in Figures 2 and 3. It is a module that is stored in the first cargo tank 51 and supplies radioactive leakage contaminated water stored in the first cargo tank 51 to the second cargo tank 52 and the fifth cargo tank 55. The supply of radioactive contaminated water by the contaminated water supply module 100 as described above is executed by a control module provided in the engine room 20, and the supply of contaminated water is performed in the pump room 30, as indicated by the arrow in FIG. 2. , It can be executed through the cargo deck line 40, the contaminated water supply pipe line 70 provided at the bottom of the ship, etc. Additionally, ball valves or check valves can be applied before and after each pipeline or on the flow path.

In other words, the contaminated water supply module 100 according to the present invention does not build a new pipeline to supply contaminated water, but is equipped with an engine room 20, a pressurized pump, a vacuum pump, etc. provided on a very large crude oil carrier scheduled to be dismantled. The pressure and water level of each cargo tank (51 to 59) can be individually adjusted by utilizing the pump room (30) and the contaminated water supply pipe line (70). Therefore, the manufacturing cost and time of the decontamination system using gas hydrate according to the present invention can be dramatically reduced.

The gas hydrate formation module 200 may be provided in the second cargo tank 52 and the fifth cargo tank 55 as shown in FIG. 2, and the second cargo tank 52 and the fifth cargo tank ( 55) can maintain 4℃ and 3bar for hydrate formation by contact with low-temperature seawater. As shown in FIGS. 3 and 4, the gas hydrate formation module 200 injects and recovers gas that can form hydrates in radioactive contaminated water supplied from the contaminated water supply module 100. It is injected from the module 800 to separate contaminants and hydrates and extract only the hydrates (pure water).

The gas hydrate forming module 200 includes a contaminated water supply unit connected to the contaminated water supply module 100, a gas supply unit connected to the gas recovery pipeline 80 of the gas injection and recovery module 800, and a reaction unit for forming gas hydrate. , a venturi valve that allows the contaminated water and gas to be mixed smoothly and supplied to the reaction unit, a discharge unit that can discharge the fluid existing in the reaction unit to the outside, a discharge unit that discharges the final product, gas hydrate, when it is generated, It may include a cooling unit capable of supplying cooling water to a portion of the conduit connected to the reaction unit that requires temperature maintenance. In addition, the reaction unit may be provided with a cylinder to transport the gas hydrate, which is the final product, a stirring device to stir the reaction water in the reaction unit, and a heater to prevent components such as sensors in the reaction unit from freezing. .

In this gas hydrate formation module 200, approximately 85% of cesium (Cs ⁺ ), strontium (Sr ²⁺ ), cobalt (Co), and iodine (I ^- ), and about 60 radionuclides are extracted without a pretreatment process using the gas hydrate determination method. Species and foreign substances can be removed at the same time. That is, the gas hydrate formation module 200, which treats radioactive contaminated water contained in seawater, injects a gas (HFC134a) capable of forming hydrate into radioactive waste liquid to form hydrate from which contaminants are excluded without any pretreatment. Since only double hydrate (pure water) can be extracted by simultaneous operation of the solid-liquid separation module 300 and the washing module 400, cesium (Cs ⁺ ), strontium (Sr ²⁺ ), and cobalt (Co ²⁺ ) , Even though iodine (I-) and other radioactive 4 nuclides (1000ppm) are included in general seawater (35,000ppm), as shown in Figures 5 and 6, it can be confirmed that more than 85% are simultaneously removed in 30 minutes. I was able to. Meanwhile, when performing secondary treatment, it was confirmed that 99% of all nuclides were removed.

Figure 5 shows a photograph of HFC134a hydrate formation for treating seawater and radioactively contaminated water according to the present invention. The experimental conditions in Figure 5 were 1.8 bar and 4°C. Figure 6 shows the results of a removal rate experiment (simultaneous removal rate) of seawater and radioactive contaminated water according to the present invention. As can be seen in Figure 6, it was considered that all foreign substances, including radionuclides, were removed simultaneously (simultaneously) by the gas hydrate formation/dissociation method according to the present invention, and no secondary waste was generated.

The solid-liquid separation module 300 is a pelletizer in the form of a screw conveyor that can dehydrate the gas hydrate slurry discharged from the discharge port of the gas hydrate forming module 200 and transfer it to the dissociation module 500, and has a rotational movement. This allows slurry compression, dehydration, and transportation to proceed simultaneously. The solid-liquid separation module 300 is installed on the partition wall between the second cargo tank 52 and the third cargo tank 53 and between the fourth cargo tank 54 and the fifth cargo tank 55 as shown in FIG. By installing it, only clean gas hydrate that excludes contaminants can be passed on to the next cargo tank. A cleaning module 400 may be provided within the solid-liquid separation module 300 to clean radioactive contaminants attached to the surface of the pellets during gas hydrate dehydration and transport. Meanwhile, gas hydrate is transferred from the gas hydrate formation module 200 and the solid-liquid separation module 300 to the third cargo tank 53 and the fourth cargo tank 54, and radioactive materials and foreign substances not included in the gas hydrate are It continues to concentrate or precipitate in the second cargo tank 52 and the fifth cargo tank 55. At this time, the viscosity is very high, making it impossible to form gas hydrate, and if the radioactive content is also higher than the standard value, pipes and valves at the bottom of the ship By operation, the radioactive material is transferred to the storage module 600 in the sixth cargo tank 56 for storing the radioactive material as shown in FIG. 2.

The above-described gas hydrate formation module 200 and solid-liquid separation module 300 may be prepared according to the gas hydrate continuous manufacturing device disclosed in Korean Patent Publication No. 10-1044770 (2011.06.21) invented and registered by the present inventor. .

The cleaning module 400 may be provided in the screw conveyor 60 to wash radioactive contaminants attached to the surface of the pellets in the process of transferring the pellets formed by the solid-liquid separation module 400 to the dissociation module 500. , pure water formed by the dissociation module 500 or the discharge module 700 can be used as the washing water. In addition, as shown in FIG. 4, the cleaning module 400 is equipped with three or more stages of fine mist spray nozzles and circulates the clean water stored in the dissociation module 700 to individually adjust the spray amount of each nozzle to improve the cleaning effect. can be maximized.

The dissociation module 500 may be provided with a device such as a heater to maintain room temperature and pressure, and as shown in FIG. 2, it is provided between the second cargo tank 52 and the fifth cargo tank 55. It may be provided in the third cargo tank 53 and the fourth cargo tank 54, respectively, and may be connected to the solid-liquid separation module 300 by a screw conveyor 60, respectively. The third cargo tank 53 and the fourth cargo tank 54 are maintained at room temperature and pressure, unlike the second cargo tank 52 and the fifth cargo tank 54, and are supplied through the screw conveyor 60. The gas hydrate in the pellet is dissociated and separated into dissociation water (pure water) and dissociation gas.

The dissociated water separated by the dissociation module 500 is filled in the third cargo tank 53 and the fourth cargo tank 54, and the separated gas is recovered by the gas injection and recovery module 800, as shown in FIG. 2 As indicated by the arrow, the gas is supplied to the hydrate formation module 200.

Unlike the first to fifth cargo tanks described above, the radioactive material storage module 600 is separately manufactured and provided to prevent leakage of radioactive materials, and is provided by the gas hydrate formation module 200 and the solid-liquid separation module 300. Separated and concentrated radioactive materials such as cesium (Cs ⁺ ), strontium (Sr ²⁺ ), cobalt (Co ²⁺ ), and iodine (I ^- ) can be stored.

The discharge module 700 is provided in the third cargo tank 53 and the fourth cargo tank 54, and is equipped with a measuring instrument capable of measuring the radioactivity concentration of the dissociated water separated by the dissociation module 500. And, if the measured radioactivity concentration is within the allowable range, the dissociated water filled in the third cargo tank 53 and the fourth cargo tank 54 is discharged into the sea. Meanwhile, if the measured radioactivity concentration exceeds the allowable range, dissociated water may be supplied to the contaminated water supply module 100 to form secondary gas hydrate.

The gas injection and recovery module 800 supplies HFC134a to the reaction unit of the gas hydrate formation module 200 and is provided to recover the gas generated in the third cargo tank 53 and the fourth cargo tank 54. . In addition, in the above description, HFC134a was used as the gas, but it is not limited to this, and any gas that can separate radioactive materials from contaminated water using gas hydrate can be used.

As described above, the formation of gas hydrate using HFC134a gas involves an exothermic process, and the dissociation involves an endothermic process. Since the enthalpy of this phase transition process is 477 kj/kg-water, which is a fairly large value, a heat exchanger module 900 as shown in FIGS. 3 and 4 is provided to exchange the temperature between gas hydrate formation and dissociation to achieve economic efficiency. can be improved.

Next, the process of decontaminating radioactive contaminated water using the decontamination system described above will be described with reference to FIG. 7.

Figure 7 is a flow chart to explain the process of decontamination of contaminated water from a radioactive leak accident according to the present invention.

The decontamination method using gas hydrate according to the present invention is a method of decontamination of radioactive leakage contaminated water using gas hydrate in a very large ship capable of operating at sea and equipped with a plurality of compartmentalized cargo tanks, Figures 2 and 7 As shown, contaminated water containing high salt and high concentration of radioactive materials due to a radioactive leak is stored in the first cargo tank 51, which is a buffer tank, by a pump provided in the pump room 30 (S10).

The contaminated water stored in the first cargo tank 51 is provided in the second cargo tank 52 and the fifth cargo tank 55, which can maintain 4°C and 3 bar along the pipeline under the control of the control module. It is supplied to the venturi valve of the gas hydrate formation module 200 through the supply module 100 (S20). Meanwhile, the gas injection and recovery module 800 supplies HFC134a gas to the venturi valve of the gas hydrate formation module 200 (S30).

Accordingly, gas hydrate is formed in the reaction unit of the gas hydrate forming module 200 (S40), and the generated gas hydrate is supplied to the solid-liquid separation module 300 through the discharge unit.

The pelletizer of the solid-liquid separation module 300 pelletizes the gas hydrate discharged from the discharge unit, and the gas hydrate forming module 200 and the solid-liquid separation module 300 pelletize radioactive substances and foreign substances not contained in the gas hydrate. The gas hydrate, which is concentrated in the second cargo tank 52 and the fifth cargo tank 55 and excludes contaminants, is transferred to the third cargo tank 53 and the fourth cargo tank 54 (S50). Foreign substances including cesium (Cs ⁺ ), strontium (Sr ²⁺ ), cobalt (Co ²⁺ ), iodine (I ^- ), etc., which are radioactive materials precipitated in step S50, are transferred to the radioactive material storage module 600 and stored. It can be.

The gas hydrate pellets formed in the solid-liquid separation module 300 are transferred from the second cargo tank 52 and the fifth cargo tank 55 to the third cargo tank 53, respectively, by the screw conveyor 60 as shown in FIG. 2. ) and is transferred to the fourth cargo tank 54, and can be washed with pure water formed in the dissociation module 500 by the washing module 400 to wash radioactive contaminants attached to the surface of the pellet during the transfer process ( S60).

The gas hydrate of the pellets transferred to the third cargo tank 53 and the fourth cargo tank 54 by the screw conveyor 60 is separated into dissociated water and dissociated gas by the dissociation module 500 (S70) , the dissociated water is charged in the second cargo tank 52 and the fifth cargo tank 55, and the dissociated gas is passed through the gas recovery pipeline 80 by the gas injection and recovery module 800 into the second cargo tank ( 52) and is circulated and recovered to the fifth cargo tank 55 (S70).

The radioactivity concentration of the dissociated water in the third cargo tank 53 and the fourth cargo tank 54 is measured by a radioactivity measurement device provided in the discharge module 700 (S80), and as a result of the measurement, the radioactivity concentration is within the allowable range. In this case (S90), it is released into the sea (S100). Meanwhile, if the radioactivity concentration exceeds the allowable range in step S90, the process proceeds to step S20 and secondary processing is performed through the above-described processes S30 to S90. When performing secondary treatment, 99% of all nuclides can be removed.

As mentioned above, radioactive contaminated water is decontaminated using very large ships such as very large crude oil carriers (VLCCs), which are scheduled to be decommissioned due to international oversupply, thereby dramatically reducing the cost and time of manufacturing plants for decontamination. , nuclides from radioactive leakage contaminated water can be removed.

Although the invention made by the present inventor has been described in detail according to the above-mentioned embodiments, the present invention is not limited to the above-described embodiments and can of course be changed in various ways without departing from the gist of the invention.

By using the decontamination system and decontamination method using gas hydrate according to the present invention, the manufacturing cost and time of a decontamination plant can be dramatically reduced.

Claims (14)

1. A system that stores and decontaminates large quantities of contaminated water from radioactive leaks using gas hydrates within a very large ship that can operate at sea and is equipped with multiple compartmented cargo tanks and a pump that can fill each cargo tank with contaminated water. As,

   A contaminated water supply module that is stored in the first cargo tank and supplies contaminated water containing high salt and high concentration radioactive materials;

   A gas hydrate forming module that forms gas hydrate by injecting gas into the contaminated water supplied from the contaminated water supply module;

   A solid-liquid separation module that forms the gas hydrate formed by the gas hydrate forming module into a pellet shape and separates it from radioactive materials,

   A washing module for washing the pellets,

   a dissociation module that separates water molecules and gas from the pellets washed by the washing module;

   A decontamination system using gas hydrate, comprising a radioactive material storage module for storing radioactive material separated in the solid-liquid separation module.
2. In paragraph 1:

   a gas injection and recovery module for injecting gas into the gas hydrate formation module and recovering the gas from the dissociation module;

   A decontamination system using gas hydrate, characterized in that it further comprises a discharge module that measures the concentration of water molecules dissociated in the dissociation module and then discharges them to the sea.
3. In paragraph 2,

   The gas hydrate formation module and the dissociation module are respectively provided in a second cargo tank and a third cargo tank adjacent to each other,

   A decontamination system using gas hydrate, characterized in that the operations of the gas hydrate formation module, solid-liquid separation module, washing module, and dissociation module are performed continuously.
4. In paragraph 3,

   A decontamination system using gas hydrate, characterized in that a plurality of the gas hydrate forming module, solid-liquid separation module, washing module, and dissociation module are provided in a plurality of each of the second cargo tank and the third cargo tank.
5. In paragraph 3,

   A decontamination system using gas hydrate, characterized in that the gas is HFC134a.
6. In paragraph 3,

   In the gas hydrate formation module and dissociation module, foreign substances in addition to pure water including cesium (Cs ⁺ ), strontium (Sr ²⁺ ), cobalt (Co ²⁺ ), and iodine (I ^- ) are removed from the contaminated water containing the radioactive material. A decontamination system using gas hydrate, characterized in that it is simultaneously removed.
7. In paragraph 3,

   The second cargo tank equipped with the gas hydrate formation module is maintained at a constant temperature and pressure,

   A decontamination system using gas hydrate, characterized in that the third cargo tank equipped with the dissociation module is maintained at room temperature and pressure.
8. In paragraph 3,

   A decontamination system using gas hydrate, characterized in that the pellets formed in the solid-liquid separation module are transferred to the dissociation module by a screw conveyor.
9. In paragraph 8:

   The cleaning module is provided with three or more fine spray nozzles,

   A decontamination system using gas hydrate, characterized in that the washing water used in the washing module is pure water formed by the dissociation module or discharge module.
10. In paragraph 3,

    A decontamination system using gas hydrates, further comprising a heat exchanger module that exchanges temperature between gas hydrate formation in the gas hydrate formation module and dissociation in the dissociation module.
11. In paragraph 3,

    The first cargo tank is provided with a larger capacity than the second cargo tank and the third cargo tank, and tritium contained in the contaminated water is removed from the first cargo tank. A decontamination system using gas hydrate.
12. A method of storing and decontaminating large quantities of contaminated water from a radioactive leak using gas hydrate in a very large ship that can operate at sea and is equipped with a number of compartmentalized cargo tanks and a pump that can fill each cargo tank with contaminated water. As,

    (a) Contaminated water containing high salt and high concentration of radioactive substances is buffered by a pump provided in the pump room in a very large ship that can operate at sea and can fill multiple compartmented cargo tanks and each cargo tank with contaminated water. Storing in a first cargo tank, which is a tank,

    (b) supplying the contaminated water stored in step (a) to the gas hydrate formation module of the second cargo tank,

    (c) supplying HFC134a gas to the gas hydrate formation module,

    (d) forming a gas hydrate in the gas hydrate forming module using the HFC134a gas supplied in step (c) for the contaminated water supplied in step (b),

    (e) pelletizing the gas hydrate formed in step (d) to separate radioactive materials and foreign substances,

    (f) A decontamination method using gas hydrate, comprising the step of dissociating the pellets formed in step (e) in a third cargo tank adjacent to the second cargo tank.
13. In paragraph 12:

    (g) A decontamination method using gas hydrate, further comprising measuring the radioactivity concentration of the pure water dissociated in step (f), and discharging it into the sea if the radioactivity concentration is within the allowable range.
14. In paragraph 12:

    A decontamination method using gas hydrate, characterized in that steps (a) to (f) are performed continuously.

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