RI-contaminated water treatment system and method

Abstract

This invention provides a contaminated water purification method that can rapidly process and purify radioactive materials in compliance with laws and regulations, and can be used in a space-saving manner. [Solution] A method for treating RI-contaminated water having a purification step and a storage step, wherein an evaporation step is provided after the storage step, in which the RI-contaminated water is heated and evaporated by a heater heating unit and discharged into the atmosphere.

Description

Technical Field

[0001] The present invention relates to a purification treatment system and method for contaminated water, particularly radioactive contaminated water contaminated by radioactive substances.

Background Art

[0002] In recent years, radioactive substances may be used in medical facilities such as hospitals for examinations or for radiation therapy. In particular, for prostate cancer and the like, radiation therapy is an important option, and radioactive substances are used for its treatment.

[0003] The disposal and treatment of radioactive substances used in radiation therapy require safe management and treatment based on regulations. Therefore, liquid radioactive substances are stored and diluted in the facility and then discarded. On the other hand, solid radioactive substances are entrusted to specialized contractors for disposal, and appropriate disposal is carried out.

[0004] In actual sites, a method of diluting liquid radioactive substances with water and discarding them at a concentration below the standard value defined by regulations is adopted. However, at the sites of medical facilities, the storage tanks, dilution tanks, etc. for disposal are physically limited in size, and for the drainage facilities in hospitals that use radioactive pharmaceuticals, it is essential to install septic tanks, storage tanks, and dilution tanks. For this reason, for installation, a large-scale and extensive space was required, but there was a current situation where it was difficult to secure such a space. In particular, medical facilities that perform the most advanced radioactive examinations and treatments are often located in areas where it is difficult to secure space, such as in the city center, and the problem was serious.

[0005] Also, in such a method using purification equipment, in order to lower the RI concentration in the drainage to the concentration defined by the legal standard, a large amount of dilution water was required depending on the usage situation of radioactive substances.

[0006] Another disposal method involves waiting for the half-life to expire before disposal. However, this decay storage method is not practical for radiopharmaceuticals with relatively long half-lives, and it would limit the total amount of radiopharmaceuticals that can be used throughout the facility.

[0007] Statistics show that the number of cancer patients has been increasing since 1985. Furthermore, according to 2023 statistics, the number of cancer-related deaths exceeded 380,000. Radiation therapy is one of the major treatment methods, alongside chemotherapy, and is applied to many types of cancer; therefore, the amount of radioactive material used in medical institutions is expected to increase significantly. For this reason, a system and method that can rapidly process and purify radioactive materials in compliance with the law is desirable. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2017-170363 [Overview of the project] [Problems that the invention aims to solve]

[0009] Therefore, the present invention aims to provide a contaminated water purification system and method that can rapidly process and purify radioactive materials in compliance with laws and regulations, and that can be used in a space-saving manner. [Means for solving the problem]

[0010] This problem is solved by an RI-contaminated water treatment system having a septic tank and a storage tank, wherein an evaporation tank is provided following the storage tank, and this evaporation tank has a heater heating unit, and the RI-contaminated water is heated and evaporated by the heater heating unit and discharged into the atmosphere.

[0011] In an advanced version of the present invention, the RI-contaminated water evaporated in the evaporation tank can be transferred to a mixing tube and mixed with heated air from a hot dryer connected to the mixing tube.

[0012] Furthermore, a demister is provided, which has the advantage that if liquefied water is generated in the RI-contaminated water mixture mixed with heated air in the mixing tube, the demister removes the water from the RI-contaminated water and discharges it into the atmosphere.

[0013] Furthermore, the problem can also be solved by an RI-contaminated water treatment method having a purification step and a storage step, wherein an evaporation step is provided after the storage step, and in this evaporation step, the RI-contaminated water is heated and evaporated by a heater heating unit and discharged into the atmosphere.

[0014] In an advanced version of this method, the RI-contaminated water evaporated in the evaporation step may be transferred to a mixing tube and mixed with heated air from a hot dryer connected to the mixing tube.

[0015] Furthermore, in the above method, it is advantageous to provide a demister, and if liquefied water is generated in the RI-contaminated water mixture mixed with heated air in the mixing tube, the demister is provided with a step to remove the water from the RI-contaminated water mixture. [Effects of the Invention]

[0016] By using this system and method, RI-contaminated water can be evaporated in an evaporation tank and mixed with the facility's ventilation and air conditioning air, and then discharged to the outside as a gas, without diluting it to meet the concentration standards for wastewater or waiting for the half-life to expire. The discharged gas is required to meet the RI concentration standards for gases, which is monitored by a monitor in this invention. This makes it possible to discharge a larger amount of RI pollutants. [Brief explanation of the drawing]

[0017] [Figure 1] Schematic diagram of the contaminated water purification treatment system according to the present invention [Figure 2] Circuit diagram of the contaminated water purification treatment system according to the present invention [Figure 3] External view of the contaminated water purification treatment system according to the present invention [Figure 4] Diagram representing the prior art

Mode for Carrying Out the Invention

[0018] [Prior Art] For the description of the present invention, first, the prior art will be described using FIG. 4. FIG. 4 is a schematic diagram of a general RI wastewater facility or RI contaminated water treatment method in a medical facility. As shown in FIG. 4, radioactive substances used in hospitals and medical facilities are mainly discharged as RI wastewater (Radioactive Wastewater) from examination rooms, treatment rooms, toilets, and showers. This wastewater is treated sequentially through a drainage purification tank, a storage tank, and a dilution layer / attenuation layer. That is, first, the contaminants in the wastewater are primarily treated in the purification drainage tank, and suspended matter and the like are separated. Thereafter, the supernatant water is transferred from the wastewater purification tank to the storage tank. The storage tank is a tank for temporarily storing and preserving the purified supernatant water. The wastewater is then transferred from here to the dilution tank / attenuation tank. In the dilution tank / attenuation tank, the wastewater transferred from the storage tank is further diluted, and / or the passage of the half-life of the radioactive substance is awaited, and the RI concentration is reduced. Finally, the wastewater that has reached the standard value is discharged into the general sewer.

[0019] Thus, for the treatment of wastewater containing radioactive substances, the installation of a storage tank, a dilution tank, and an attenuation tank is essential. To appropriately arrange these facilities, a large ground contact area is required. Also, to discharge the wastewater into the sewer, it is necessary to lower the RI concentration below the standard value defined by laws and regulations, and for this, it was necessary to reduce the concentration of radioactive substances using a large amount of dilution water.

[0020] [System and Method Outline According to the Present Invention (First Embodiment)] Subsequently, the configuration of the RI contaminated water treatment system according to the present invention will be described based on the schematic diagram shown in FIG. 1. The applicant of the present application has noticed that since it is limited to diluting the RI contaminated water until it meets the concentration standard as drainage or waiting for the passage of the half-life, by evaporating it in an evaporation tank and discharging it as gas / gas together with the building ventilation and air conditioning air, more RI contaminants can be discharged. This is because a margin is created in the discharge amount for the concentration standard of RI contaminants in the gas / discharge gas. Therefore, the RI contaminated water treatment system / RI contaminated water treatment method according to the present invention has a pretreatment section, a main treatment section, and a post-treatment section as shown in FIG. 1, and has a mechanism / step for evaporating and vaporizing the RI contaminated water in the main treatment section. Note that the conventional method of discharging RI wastewater into the sewer can also be implemented in parallel.

[0021] As shown in FIG. 1, the pretreatment section consists of a septic tank, a storage tank, and an activated carbon adsorption device. Similar to the prior art, RI wastewater containing radioactive substances used in hospitals and medical facilities flows into the septic tank. The RI wastewater is mainly discharged from examination rooms, treatment rooms, toilets, and showers, as in the prior art. First-stage treatment is performed in the septic tank.

[0022] After that, the supernatant water from the septic tank is sent to the storage tank. The storage tank is a tank for temporarily storing and preserving the purified supernatant water. The supernatant water stored in the storage tank for a predetermined period is then transferred to the main treatment section. The main treatment section is the core part of the RI contaminated water treatment system according to the present invention, where the evaporation / vaporization of the RI contaminated water is performed. Therefore, As shown in FIG. 1, the main treatment section has an evaporation tank, a mixer tube , and a demister. Furthermore, as can be seen from FIG. 1, a hot dryer can be connected to the main treatment section.

[0023] The evaporator has a heater heating section, as conceptually shown in Figure 1. This heater heating section is configured to heat and evaporate the wastewater. The heater heating section has the capacity to heat the wastewater to approximately 100°C, for example.

[0024] The water vapor evaporated in the evaporator is then sent to the mixing tube. The mixing tube is used to mix the water vapor from the evaporator with heated air from the hot dryer. The evaporated wastewater is cooled and condensed, and / or adjusted (mixed with heated air) by the heated air from the hot dryer to achieve the appropriate temperature and pressure. This adjustment is performed so that the temperature and pressure of the water vapor are located in the upper region of the vapor pressure curve. In the mixing tube, any wastewater that cools and condenses and returns to a liquid state is returned to the evaporator. This liquid flow is represented by dashed arrows in Figure 1.

[0025] The hot dryer connected to this processing unit is a device that sends heated air to the mixing tube of this processing unit. It uses heating to evaporate and remove moisture. dry This is a device. In this invention, the device is configured to heat indoor air and send it to a mixing tube as heated air, for example, at 150°C.

[0026] In the mixing tube, the wastewater vapor is mixed with heated air from the hot dryer and adjusted to a gaseous state as a mixture with air. This mixture is then sent to the demister. The demister is designed to return any moisture generated due to changes in temperature conditions, etc., back to the evaporation tank. This flow from the demister to the evaporation tank is represented by a dashed arrow in Figure 2.

[0027] In the RI-contaminated water treatment system according to the present invention, a post-treatment section is provided following the demister. The post-treatment section is provided with a filter layer, as shown in Figure 1. It is also possible to provide another filter following the filter layer.

[0028] The filter layer can consist of, for example, a pre-filter, an intermediate filter, and a HEPA filter. The pre-filter is a coarser filter designed to remove coarser particles and larger foreign objects. It is installed to capture dust, mist, and debris. This prevents filter clogging and extends the lifespan of the intermediate filter and HEPA filter.

[0029] An intermediate filter is a filter designed to remove medium-sized particles. It is intended to capture minute particles that were not removed by the pre-filter. It is also used to reduce the load on the HEPA filter and extend its lifespan. A relatively higher-performance filter is used compared to the pre-filter.

[0030] HEPA (High Efficiency Particulate Air) filters are designed to remove extremely fine particles. Conform to HEPA standards, they are configured to capture over 99.97% of particles as small as 0.3 μm. They are used when cleanroom-level purification is required and are also suitable for removing non-volatile radioactive particulate matter.

[0031] The filter layer, consisting of a pre-filter, intermediate filter, and HEPA filter, can be a charcoal filter. The charcoal filter, with its large surface area due to the fine pores (porous structure) of activated carbon, can efficiently remove harmful substances, and furthermore, it can adsorb radioactive iodine gas, suppressing its release into the environment.

[0032] The RI-contaminated water, from which water has been removed by the demister, is sent to a post-processing unit equipped with these filter tanks and filters, where foreign matter, harmful substances, radioactive particles, and harmful dust are removed as appropriate before being released into the atmosphere.

[0033] As shown in Figure 1, the post-treatment unit is structured to mix not only the RI-contaminated water vapor mixture from the treatment unit according to the present invention, but also exhaust gas from the RI-using facility / building. In other words, in addition to the post-treatment unit newly installed for the RI-contaminated water treatment system according to the present invention, existing treatment units normally installed in RI-using facilities / buildings are used in conjunction with the post-treatment unit of the system according to the present invention.

[0034] Following the post-treatment section, the RI-contaminated water treatment system according to the present invention is equipped with a monitor. The monitor is used to check whether the exhaust gas that has passed through the post-treatment section is safe to release to the outside, that is, whether the concentration of pollutants contained in the exhaust gas is below the concentration limit.

[0035] [System Circuit Diagram (Second Embodiment)] Next, another embodiment of the RI-contaminated water treatment system according to the present invention will be described based on the circuit diagram shown in Figure 2. Figure 2 is an example of a circuit diagram of the RI-contaminated water treatment system according to the present invention. As with Figure 1, Figure 2 shows the pre-treatment unit and the main treatment unit. In Figure 2, the post-treatment unit is not shown.

[0036] In Figure 2, the pretreatment unit also includes a septic tank and a storage tank, similar to those in Figure 1. Furthermore, a pump can be seen in Figure 2.

[0037] The septic tank is configured to purify the RI-contaminated water it takes inside. As can be seen in Figure 2, this septic tank is equipped with a wastewater inlet, a wastewater level detection unit (level gauge, LG), and a wastewater level alarm (level indicator alarm, LIA). The wastewater level detection unit detects the water level of the wastewater in the septic tank. The wastewater level alarm detects the water level of the wastewater and is configured to issue a predetermined alarm or instruction command when it falls below and / or exceeds a predetermined level. The electrical signals and instructions from the wastewater level detection unit and the wastewater level alarm are configured to be transmitted to the wastewater treatment control panel, which will be described later, via general information and communication technology and electrical technology.

[0038] In Figure 2, it can be seen that a pressure gauge (PG) and a first pump (P) are installed following the septic tank. A motor (M) is attached to the first pump, i.e., the wastewater supply pump. The pressure gauge is configured to measure the pressure of the RI-contaminated water at that location and, if necessary, to transmit a signal to a control unit connected to it, i.e., the wastewater treatment control panel described later.

[0039] In Figure 2, two storage tanks (the first storage tank and the second storage tank) are provided following the pump. These storage tanks are connected in a way that allows switching between serial and parallel connections via the control of multiple valves (solenoid valves, SV). The valves are configured to be controlled as appropriate by a control unit such as a wastewater treatment control panel.

[0040] Each of these storage tanks is equipped with a wastewater level detection unit and a wastewater level alarm. Through these, the level of RI-contaminated water inside each storage tank can be detected at all times. Multiple valves are configured to be independently switched on and off based on signals and instructions from these wastewater detection units and wastewater level alarms, thereby enabling the switching of the aforementioned connection state (serial connection or parallel connection). Furthermore, if the water level of RI-contaminated water stored in all of these storage units drops, a signal is sent to the aforementioned pump, which may increase the amount of water transferred from the septic tank and activated carbon adsorption device.

[0041] Following these storage tanks, Figure 2 shows a second pump, namely the evaporator feed pump. It can be seen that the second pump is also equipped with a motor. The second pump is installed to transfer RI-contaminated water from the storage tanks to the evaporator.

[0042] Figure 2 shows that a pressure gauge (PG) is installed following the second pump. The pressure gauge is configured to detect the pressure of the RI-contaminated water at that location and, if necessary, to transmit a signal to the connected control unit (wastewater treatment control panel), etc.

[0043] In Figure 2, a flow indicator with quantity (FIQ) is installed following the pressure gauge. The flow indicator is configured to measure the flow rate of RI-contaminated water being transferred from the storage tank to the evaporation tank and to control it as needed.

[0044] Next, we will explain the main processing unit shown in Figure 2. The main processing unit in Figure 2, like the main processing unit in Figure 1, has an evaporator, a mixing tube, and a demister. As with Figure 1, Figure 2 also shows a hot dryer connected to the main processing unit. Furthermore, in Figure 2, it can be seen that two water seal tanks are provided.

[0045] As shown in Figure 2, the evaporator has a heater heating section (electric heater, EH). The evaporator is configured so that the RI-contaminated water transferred into the evaporator is heated and evaporated by this heater heating section. In other words, for example, the heater heating section has the capacity to heat the RI-contaminated water to approximately 100°C.

[0046] The evaporator tank is further equipped with a wastewater level detection unit (level gauge, LG) and a wastewater level alarm (level indicator alarm, LIA). The wastewater level detection unit detects the water level of the wastewater in the septic tank. The wastewater level alarm detects the water level of the wastewater and is configured to emit a predetermined alarm or issue a predetermined instruction command when it falls below and / or exceeds a predetermined level.

[0047] Following the evaporator, Figure 2 shows a mixing tube. The mixing tube has the same function and role as in Figure 1. That is, the mixing tube is a tube / component for mixing the water vapor from the RI-contaminated water in the evaporator with the heated air from the hot dryer. It has the function and role of regulating the evaporated RI-contaminated water with the heated air from the hot dryer to prevent it from cooling and condensing, and / or to reach an appropriate temperature and pressure. This regulation is performed so that the temperature and pressure of the water vapor are located in the upper region of the vapor pressure curve.

[0048] In Figure 2, a temperature measuring unit (thermogauge, TG) and a temperature indicator (temperature indicator, TI) are provided in the transfer path from the evaporator to the mixing tube. The system is configured to measure the temperature along the path and, if necessary, transmit a temperature signal to an external control unit.

[0049] In Figure 2, the wastewater, which has been cooled and condensed in the mixing tube and returned to a liquid state, is returned to the evaporation tank via a water seal tank.

[0050] In Figure 2, the hot dryer connected to this processing unit is a device that sends heated air to the mixing tube of this processing unit. Heating is used to evaporate and remove moisture. dry This is the device. You can see that the hot dryer is equipped with a heater heating unit (electric heater, EH) and a motor. As shown in Figure 2, this hot dryer is configured to heat the room air and send it to the mixing tube as heated air, for example, at 150°C.

[0051] In the mixing tube, it is mixed with heated air from the hot dryer and adjusted to a gaseous state. wastewater Next, it is sent to the demister. The demister, also called a mist separator, is a device that removes moisture from the gas, and then the hot dryer... effect It has the function of increasing moisture. The moisture generated in the demister is returned to the evaporation tank via a water seal tank.

[0052] Next, based on Figure 3, the RI-contaminated water treatment system according to the present invention Overview The layout of each piece of equipment and device is shown. Figure 3 shows, from left to right, the activated carbon filter, the first water receiving tank, the second water receiving tank, the wastewater supply pump, the evaporation tank supply pump, the wastewater treatment control panel, and the main processing unit.

[0053] This processing unit can be seen to include an evaporator, mixing tube, demister, and hot dryer. Although not shown, each component unit is connected by appropriate piping and routing as shown in Figure 1 or Figure 2 above.

[0054] The system and method according to the present invention have been described above based on two embodiments. The above description is for illustrative purposes only and does not limit the scope of the rights of the present invention.

Claims

[Claim 1] A method for treating RI-contaminated water, comprising a purification step and a storage step, The RI-contaminated water to be treated is RI wastewater from radioactive materials used in hospitals or medical facilities, specifically RI-contaminated water discharged from laboratories, treatment rooms, toilets, or shower rooms, and includes an evaporation step after the storage step. In this evaporation step, the RI-contaminated water is heated and evaporated by a heater heating unit and discharged into the atmosphere, in a method for treating RI-contaminated water. In the evaporation step, the RI-contaminated water that was evaporated was It is transferred to the mixing tube, The step involves mixing the heated air from a hot dryer connected to a mixing tube with the heated air from the hot dryer. A demister is provided. If liquefied water occurs in the RI-contaminated water mixture that is mixed with heated air in the mixing tube, A method for treating radioisotope (RI) contaminated water, characterized by comprising a step of removing moisture from the RI contaminated water mixture transferred to a demister. 。

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