Airborne radioactive Po-210 purification system and method thereof

Abstract

The invention provides an airborne radioactive Po-210 purification system and method, efficient purification and waste minimization of airborne radioactive Po-210 in covering gas are achieved, the purification system comprises a cooling and depressurization pipeline, an acid solution absorption device and a heating and pressurizing pipeline which are sequentially connected, one end of the cooling and depressurizing pipeline is connected with a covering gas output end of the reactor covering gas system; the other end of the cooling and depressurization pipeline is connected with a gas source input end of the acid solution absorption device, and airborne radioactive Po-210 is dissolved in a strong acid solution; the solution discharge end of the acid solution absorption device is connected with the electrolysis device, and airborne radioactive Po-210 species dissolved in the acid solution are deposited on the surface of a solid material of the electrolysis device; two ends of the heating and pressurizing pipeline are respectively connected with a gas source output end of the acid solution absorption device and a gas input end of the reactor covering gas system; the heating and pressurizing pipeline is also provided with a deacidification and dehumidification assembly, and the purified gas is conveyed back to the reactor covering gas system after being subjected to deacidification, dehumidification, heating and pressurization in sequence.

Description

Technical Field

[0001] The invention relates to the field of nuclear air purification, and in particular to an airborne radioactive Po-210 purification system and method thereof. Background Art

[0002] Liquid lead-bismuth eutectic alloy, referred to as lead-bismuth alloy. It has the characteristics of low melting point (396K) and high boiling point (1943K), and is a good coolant for fast neutron reactors and ADS subcritical systems. When lead-bismuth alloy is used as the coolant for the above two reactors, Bi-209 atoms will produce highly radioactive nuclides Po-210 after being activated by neutrons.

[0003] Studies have shown that polonium-containing species are highly volatile. At the reactor operating temperature, species containing Po-210 will evaporate from the coolant into the cover gas above, thereby accumulating a certain amount of airborne radioactive Po-210 in the cover gas. Under normal operating conditions, the cover gas system has a certain leakage rate, which causes airborne radioactive Po-210 to enter the reactor top containment room and plant, and may eventually enter the personnel work area and environment.

[0004] Po-210 is an extremely toxic radioactive nuclide that releases alpha particles with an energy of up to 5.3 MeV when it decays. In addition, the physical half-life of Po-210 is as long as 138.4 days, and the biological half-life is 30-50 days. Therefore, if Po-210 species enter the human body through inhalation, ingestion, or skin contact, it will cause serious internal radiation. Ultimately, the generation and accumulation of Po-210 greatly increases the difficulty of operation and maintenance of lead-bismuth fast reactors and ADS subcritical systems.

[0005] In order to ensure the safe and stable operation of my country's lead-bismuth reactor and ADS subcritical system and prevent the leakage or emission of airborne radioactive Po-210 into the air, it is very necessary to purify the airborne radioactive Po-210 in the cover gas.

[0006] Patent application number 202210293734.8 is a polonium removal system and method for a lead-bismuth cooled reactor. A serpentine flow channel is arranged between multiple adsorption modules in the polonium removal system. The covering gas flows in the serpentine flow channel and passes through each of the adsorption modules multiple times, so that the polonium aerosol in the covering gas is adsorbed and fixed on the multiple adsorption modules, thereby physically adsorbing and filtering the covering gas mixed with the polonium aerosol.

[0007] However, the physical adsorption method used is reversible, which means that the adsorbed Po-210 can be easily desorbed from the adsorption module and cannot be stably adsorbed for a long time, which is very unfavorable for operators in the later sealed transportation process. At the same time, the adsorption module made of polymer materials such as cellulose and resin has a high covering gas temperature. The covering gas temperature is extremely high. Even if the temperature varies depending on the type of reactor and operating conditions, its temperature is usually between 300 and 600 degrees Celsius, which makes it very easy for Po-210 to desorb. Moreover, in the presence of high-temperature covering gas, the pressure in the adsorption device is much greater than the atmospheric pressure, and it is difficult to achieve vacuum. There are other easily adsorbed species in the covering gas, which makes the surface of the multi-molecular layer adsorption module too crowded, affecting the adsorption efficiency, and requires frequent replacement of the adsorption module, resulting in excessive human contact. Summary of the invention

[0008] The object of the present invention is to provide a system and method for purifying airborne radioactive Po-210, which deposits the airborne radioactive Po-210 in the covering gas onto the surface of the electrolytic solid material through strong acid absorption and electrolytic deposition, thereby ultimately achieving efficient purification of the airborne radioactive Po-210 in the covering gas and minimization of waste.

[0009] Embodiments of the present invention are as follows:

[0010] A purification system for airborne radioactive Po-210, comprising a cooling and depressurizing pipeline, an acid solution absorption device and a heating and pressurizing pipeline connected in sequence, wherein one end of the cooling and depressurizing pipeline is connected to a covering gas output end of a reactor covering gas system; the other end of the cooling and depressurizing pipeline is connected to a gas source input end of the acid solution absorption device, and the airborne radioactive Po-210 reacts with a strong acid solution in the acid solution absorption device and dissolves in the strong acid solution; the solution discharge end of the acid solution absorption device is connected to an electrolysis device, and the airborne radioactive Po-210 dissolved in the acid solution is deposited on a solid material surface of the electrolysis device through the electrolysis device; the two ends of the heating and pressurizing pipeline are respectively connected to the gas source output end of the acid solution absorption device and the gas input end of the reactor covering gas system; a deacidification and dehumidification component is also arranged on the heating and pressurizing pipeline, and the purified gas purified by the acid solution absorption device is transported back to the reactor covering gas system after being deacidified, dehumidified, heated and pressurized in sequence.

[0011] As a preferred technical solution, the above-mentioned cooling and pressure reduction pipeline includes an upstream isolation valve, a circulation pump, a cooling and pressure reduction device and a first Po-210 activity monitoring device which are sequentially connected through pipelines.

[0012] As a preferred technical solution, the hydrogen ion concentration in the above-mentioned acid solution absorption device is ≥1 mol / L.

[0013] As a preferred technical solution, the strong acid solution in the above-mentioned acid solution absorption device includes one of nitric acid solution, sulfuric acid solution, and hydrochloric acid solution, or a mixed solution of multiple acids.

[0014] As a preferred technical solution, the solution temperature of the above-mentioned acid solution absorption device is 60-100°C.

[0015] As a preferred technical solution, the above-mentioned heating and pressurizing pipeline includes a deacidification tank, a dehumidification tank, a second Po-210 activity monitoring device, a downstream isolation valve, and a heating and pressurizing device which are sequentially connected through pipelines.

[0016] As a preferred technical solution, a third Po-210 activity monitoring device is also provided at the solution output end of the electrolysis device.

[0017] As a preferred technical solution, the deposition reaction temperature of the electrolytic device is 0-60°C.

[0018] As a preferred technical solution, the above-mentioned acid solution absorption device also includes an acid solution replenisher connected to the acid solution injection end of the acid solution absorption device.

[0019] A method for purifying airborne radioactive Po-210, comprising:

[0020] The temperature-reducing and pressure-reducing pipeline leads the covering gas of the reactor covering gas system from the covering gas output end, and introduces the covering gas into the acid solution absorption device after temperature-reducing and pressure-reducing, and the Po-210 in the covering gas is absorbed and dissolved into the strong acid solution, and then the dissolved Po-210 in the strong acid solution is further deposited onto the surface of the solid material through the electrolysis device;

[0021] The purified gas after absorption is transported back to the reactor blanket gas system through a heating and pressurizing pipeline after being deacidified, dehumidified, heated, and pressurized in sequence.

[0022] The beneficial effects of the embodiments of the present invention are:

[0023] 1. The airborne radioactive Po-210 purification system of the present invention is provided with a temperature reduction and pressure reduction management system, and the covering gas containing airborne radioactive Po-210 drawn from the reactor covering gas system is subjected to a temperature reduction and pressure reduction treatment. On the one hand, the specific activity of the airborne radioactive Po-210 can be increased, the operability of the subsequent acid solution purification process can be improved, and the safety of the purification process can be ensured; on the other hand, lowering the temperature of the covering gas can avoid the loss of the strong acid solution in the acid solution absorption device due to high temperature, and at the same time can protect the downstream drying device from being corroded by acidic substances;

[0024] 2. The gas after cooling and depressurization is injected into the acid solution absorption device, and the airborne radioactive Po-210 species reacts with the strong acid solution and dissolves in the strong acid solution, thereby completing a purification. The strong acid can be completely ionized in water, accelerating the dissolution of the polonium-containing species, thereby improving the single purification efficiency. The Po-210 species dissolved in the strong acid solution are further deposited on the surface of the solid material by the electrochemical deposition method, ultimately achieving efficient purification of the airborne radioactive Po-210 in the covering gas and minimizing waste.

[0025] 3. The purified gas enters the heating and pressurizing pipeline. Before heating and pressurizing, a deacidification and dehumidification component is designed to reduce acid corrosion to the heating and pressurizing pipeline and ensure that acid gas and water vapor will not enter the reactor; the purified gas is then reheated and pressurized to the gas temperature and pressure of the reactor cover gas system through the heating and pressurizing pipeline to ensure minimal disturbance to the temperature and pressure in the reactor;

[0026] 4. The overall airborne radioactive Po-210 purification system is easy to operate, has mild conditions, produces a small amount of waste, and reduces the frequency of human contact. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 A schematic diagram of an airborne radioactive Po-210 purification system according to a first embodiment of the present invention;

[0029] Figure 2 It is a schematic diagram of a temperature and pressure reduction device according to a first embodiment of the present invention;

[0030] Figure 3 A schematic diagram of an electrolysis device according to a first embodiment of the present invention;

[0031] Figure 4 A schematic diagram of a heating and pressure-boosting device according to a first embodiment of the present invention;

[0032] Figure 5 A schematic diagram of a partial airborne radioactive Po-210 purification system according to a second embodiment of the present invention;

[0033] Figure 6 This is a schematic structural diagram of an acid solution absorption device according to a second embodiment of the present invention.

[0034] Icons: cooling and pressure reduction pipeline 110; upstream isolation valve 111; circulation pump 112; cooling and pressure reduction device 113; heat exchanger 1131; pressure reduction valve 1132; spray absorption tower 1133; first Po-210 activity monitoring device 114; acid solution absorption device 120; electrolysis device 121; electrolysis generator 1211; cathode tank 1212; anode tank 1213; ion exchange membrane 1214; acid solution inlet conduit 1215; cathode electrolytic sheet 1216; acid solution outlet conduit 1217; anode Electrolytic sheet 1218; electrolytic power supply 1219; third Po-210 activity monitoring device 122; acid solution replenisher 123; partition 124; S-shaped flow channel 125; spoiler 126; jacketed coil 127; heating and pressurizing pipeline 130; acid removal tank 131; dehumidification tank 132; second Po-210 activity monitoring device 133; downstream isolation valve 134; heating and pressurizing device 135; dehydrogenation tank 136; gas compressor 1351; electric heater 1352; reactor cover gas system 200. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0038] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete and fully convey the concept of the example embodiments to those skilled in the art.

[0039] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0040] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0041] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0042] First embodiment

[0043] See also Figure 1 In view of the generation of airborne radioactive polonium-210 in lead-bismuth fast reactors and ADS subcritical systems and the health hazards to workers caused by leakage, an embodiment provides an airborne radioactive Po-210 purification system, which includes a cooling and pressure reduction pipeline 110, an acid solution absorption device 120 and a heating and pressurizing pipeline 130 connected in sequence, and can effectively reduce the concentration of airborne radioactive polonium-210 in the above-mentioned reactor cover gas; realize continuous, stable and efficient purification of airborne radioactive polonium-210 in the cover gas, avoid desorption of airborne radioactive polonium-210, and effectively protect the health and safety of workers.

[0044] In this embodiment, one end of the temperature-reducing and pressure-reducing pipeline 110 is connected to the covering gas output end of the reactor covering gas system 200, and the other end is connected to the gas source input end of the acid solution absorption device 120, so as to lead the covering gas carrying airborne radioactive Po-210 out of the reactor covering gas system 200 for temperature-reducing and pressure-reducing treatment and then discharge it into the acid solution absorption device 120, and the airborne radioactive Po-210 reacts with the strong acid solution in the acid solution absorption device 120 and dissolves in the strong acid solution.

[0045] Specifically, the cooling and depressurizing pipeline 110 in this embodiment includes an upstream isolation valve 111, a circulation pump 112, a cooling and depressurizing device 113 and a first Po-210 activity monitoring device 114 connected in sequence through pipelines, which are used to safely lead out the covering gas and perform cooling and depressurizing treatment at the same time. The advantages are: ① The risk factor of the covering gas after the cooling and depressurizing treatment is greatly reduced, ensuring the safety of the purification process and strong operability; ② The covering gas after the cooling and depressurizing treatment can reduce the impact on the acid solution absorption device 120 and the downstream devices, avoiding the solution temperature of the strong acid solution in the acid solution absorption device 120 to increase due to the high temperature and high pressure gas, and the strong acid solution is instantly vaporized, generating a large amount of strong acid vapor, which directly causes the loss of the strong acid solution; at the same time, the strong acid vapor flows into the subsequent heating and pressurizing pipeline 130, increasing the workload of the deacidification and dehumidification component in the heating and pressurizing pipeline 130, and the strong acid vapor is in a small molecule state, which is easy to escape from the deacidification and dehumidification component, causing acid corrosion to the heating and pressurization in the deacidification and dehumidification component.

[0046] Furthermore, the upstream isolation valve 111 is configured to selectively open or close or selectively open and close part of the flow channel for the covering gas to pass through, so as to control the flow, flow speed and flow volume of the covering gas between the airborne radioactive Po-210 purification system and the reactor covering gas system 200.

[0047] The circulation pump 112 is used to transport the covering gas in the reactor covering gas system 200 to the airborne radioactive Po-210 purification system and to transport the adsorbed and purified covering gas back to the reactor covering gas system 200, circulating the gas in the closed airborne radioactive Po-210 purification system.

[0048] See also Figure 2 The temperature and pressure reduction device 113 is implemented by a heat exchanger 1131 and a pressure reducing valve 1132. The high-temperature and high-pressure covering gas contacts the refrigerant for heat exchange, thereby achieving the temperature reduction of the covering gas. The temperature reduction is accompanied by a certain pressure reduction effect. A pressure reducing valve 1132 is also provided, which automatically adjusts the valve opening according to the set outlet pressure through an internal regulating device, thereby stably reducing the high-pressure covering gas to the required pressure value, thereby further achieving pressure reduction processing.

[0049] The cooling temperature of the heat exchanger 1131 can be controlled at 150-200°C, which is about half the temperature of the original covering gas. The cooling is not difficult and can reduce the energy consumption of the heat exchanger 1131. The temperature after passing through the pressure reducing valve 1132 will be further reduced and controlled at about 100-150°C.

[0050] The first Po-210 activity monitoring device 114 is used to detect the polonium content and the activity concentration of Po-210 entering the acid solution absorption device 120. The amount of strong acid solution in the acid solution absorption device 120 is determined according to the monitoring value of the first Po-210 activity monitoring device 114. The activity concentration of Po-210 is calculated as follows: C0 = A1·N0 / N t V,

[0051] , C0 is the activity concentration of Po-210 in aerosol, unit is Bq / m 3 ; A1 is the activity of the added tracer, in Bq; N0 is the net count rate in the region of interest corresponding to the Po-210 peak, in S -1 ; N1 is the net count rate in the region of interest corresponding to the tracer peak, in units of S -1 ; V is the aerosol volume, in m 3 .

[0052] A strong acid solution is provided in the acid solution absorption device 120. When the covering gas enters the acid solution absorption device 120, the airborne radioactive Po-210 species reacts with the strong acid solution and dissolves in the strong acid solution, thereby completing the first purification.

[0053] In this embodiment, the strong acid solution in the acid solution absorption device 120 is in a completely ionized state, and its hydrogen ion concentration is ≥1 mol / L. The strong acid solution in the acid solution absorption device 120 includes one of nitric acid solution, sulfuric acid solution, and hydrochloric acid solution, or a mixed solution of multiple acids, such as a mixed solution of hydrochloric acid and nitric acid, a mixed solution of sulfuric acid and hydrochloric acid, and a mixed solution of nitric acid, sulfuric acid, and hydrochloric acid, preferably nitric acid and hydrochloric acid, and the reaction formula is:

[0054] PbPo+6HNO3→Po(NO3)4+Pb(NO3)2+3H2;

[0055] PbPo+3H2SO4→Po(SO4)2+PbSO4+3H2;

[0056] PbPo+6HCl→PoCl4+PbCl2+3H2.

[0057] The solution temperature of the acid solution absorption device 120 can be 30-100°C, but in order to reduce the energy consumption of the early cooling and pressure reduction device 113, the solution temperature of the acid solution absorption device 120 is preferably 60-100°C, which can not only ensure the reaction absorption efficiency of the airborne radioactive Po-210, but also reduce the overall energy consumption. In addition, the ionization state of the strong acid is not significantly affected under slightly higher temperature conditions, thereby not affecting the use of the strong acid solution.

[0058] The acid solution absorption device 120 further includes an electrolysis device 121 , which is connected to the solution discharge end of the acid solution absorption device 120 , and deposits the airborne radioactive Po-210 dissolved in the acid solution onto the solid material surface of the electrolysis device 121 through the electrolysis device 121 .

[0059] See also Figure 3 The electrolysis device 121 includes an electrolysis generator 1211, an ion exchange membrane 1214 is arranged between the cathode tank 1212 and the anode tank 1213 of the electrolysis generator 1211, the cathode tank 1212 is provided with an acid liquid inlet conduit 1215 and a cathode electrolytic sheet 1216, the anode tank 1213 is provided with an acid liquid outlet conduit 1217 and an anode electrolytic sheet 1218, and the anode electrolytic sheet 1218 and the cathode electrolytic sheet 1216 are connected to an electrolysis power supply 1219.

[0060] The ion exchange membrane 1214 has a three-layer structure, including a rare earth metal filter layer, a glass fiber filter layer and a ceramic base layer, wherein the rare earth metal filter layer is immersed in the surface of the glass fiber filter layer, and the rare earth metal filter layer is formed by plating Pr-type rare earth metal or Pr2O3 on the surface of the glass fiber filter layer.

[0061] A third Po-210 activity monitoring device 122 is also provided on the solution output end of the electrolysis device 121, that is, the acid solution outlet conduit 1217. The third Po-210 activity monitoring device 122 at the tail end of the electrolysis device 121 is used to determine the deposition amount of Po-210 species in the electrolytic solution. When the activity is reduced to an allowable value, the treated acid solution is discharged from the electrolysis device 121. Fresh strong acid solution is filled into the electrolysis device 121 for the next Po-210 electrolytic purification.

[0062] The strong acid solution containing dissolved Po-210 species contains Po 4+ Ions, Pb 2+ Ions, H + ions, etc., after electrolytic deposition Po 4+ +4e - →Po. The environmental parameters of the deposition reaction are similar to those of Po absorption, and the electrolytic reaction can be carried out in a temperature range of 0 to 100°C. In this embodiment, the temperature of the electrolytic deposition solution can be reduced to a lower temperature by cooling, and the optimal temperature range is 0-60°C, which can greatly reduce the corrosion of the inert anode and extend the service life of the inert electrode.

[0063] The electrodes used in the deposition reaction are made of acid-resistant materials: including carbon materials, platinum, stainless steel, etc.

[0064] The acid solution absorption device 120 further includes an acid solution replenisher 123 connected to the acid solution injection end of the acid solution absorption device 120 , and is used to replenish new strong acid solution into the acid solution absorption device 120 and / or the electrolysis device 121 .

[0065] The two ends of the heating and pressurizing pipeline 130 are respectively connected to the gas source output end of the acid solution absorption device 120 and the gas input end of the reactor cover gas system 200; the heating and pressurizing pipeline 130 is also provided with an acid removal and dehumidification component, and the purified gas purified by the acid solution absorption device 120 is successively deacidified, dehumidified, heated, and pressurized before being transported back to the reactor cover gas system 200. In this embodiment, after the acid solution absorption device 120 completes the absorption, the acid and water molecules carried by the cover gas during the pickling process are first removed by the acid removal and dehumidification component to avoid affecting the subsequent heating and pressurizing equipment.

[0066] Specifically, the heating and pressurizing pipeline 130 includes a deacidification tank 131, a dehumidification tank 132, a second Po-210 activity monitoring device 133, a downstream isolation valve 134 and a heating and pressurizing device 135 which are sequentially connected through pipelines.

[0067] The acid removal tank 131 is used to remove the gaseous acid solution droplets contained in the gas at the gas source output end. The dehumidification tank 132 is used to remove the moisture in the gas at the gas source output end. The second Po-210 activity monitoring device 133 is used to detect whether there is still radioactive nuclide polonium-210 in the reflux pipe section. When there is no radioactive nuclide polonium-210, the downstream isolation valve 134 is opened to increase the pressure and heat the treated reflux gas.

[0068] In this embodiment, the first, second and third Po-210 activity monitoring devices may be I CP-MS or I CP-OES or α spectrometers.

[0069] See also Figure 4 In this embodiment, the heating and pressurizing device 135 uses a gas compressor 1351 and an electric heater 1352 connected in sequence. The pressure of the covering gas compressed by the gas compressor 1351 can be increased, and when the pressure reaches a pressure value consistent with the pressure in the reactor, it is heated by the electric heater 1352. In this embodiment, the method of first increasing the pressure and then heating is adopted. While increasing the pressure, the covering gas has a certain temperature increase ability, thereby reducing the energy consumption of the electric heater 1352.

[0070] The treated gas is reheated and pressurized to the original parameters by means of pressurization by gas compressor 1351 and electric heating to ensure the minimum disturbance of temperature and pressure in the reactor. Electric heating can provide a faster heating rate, and the required equipment is small and easy to operate; the gas compressor 1351 has a fast pressurization rate and requires simple equipment, thereby reducing equipment cost investment.

[0071] For an airborne radioactive Po-210 purification system, this embodiment provides an airborne radioactive Po-210 purification method, which includes:

[0072] S1: The temperature reduction and pressure reduction pipeline 110 leads the covering gas of the reactor covering gas system 200 from the covering gas output end, and introduces the covering gas into the acid solution absorption device 120 after temperature reduction and pressure reduction. The temperature reduction and pressure reduction device 113 uses a heat exchanger 1131 and a pressure reduction valve 1132. The heat exchanger 1131 reduces the temperature of the original covering gas to 150°C to 200°C, and then passes through the pressure reduction valve 1132 for temperature reduction and pressure reduction treatment, and further controls the temperature of the covering gas to 100 to 150°C; the covering gas after temperature reduction and pressure reduction passes through the first Po-210 activity monitoring device 114 to detect the polonium content and the activity concentration of Po-210 entering the acid solution absorption device 120, thereby controlling the strong acid solution content and temperature in the acid solution absorption device 120. For example, when the polonium content and the activity concentration of Po-210 are high, new strong acid solution is appropriately added to the acid solution absorption device 120 through the acid solution replenisher 123 to reduce the temperature of the acid solution absorption device 120; when the polonium content is low and the activity concentration of Po-210 is low, the strong acid solution content and temperature of the acid solution absorption device 120 are maintained to reduce energy consumption.

[0073] S2: Po-210 in the covering gas is absorbed and dissolved into the strong acid solution, and then the dissolved Po-210 in the strong acid solution is further deposited onto the surface of the solid material through the electrolysis device 121. The acid solution absorption device 120 is used as the first purification device, and the covering gas at 100-150°C enters the acid solution absorption device 120, and the contact solution can be further cooled to control the solution temperature below 100°C; at the same time, according to the detection result of the first Po-210 activity monitoring device 114, for example: when the polonium content and the activity of Po-210 are high, the cooling mechanism of the acid solution absorption device 120 is started, and the acid solution absorption device 120 is controlled at about 65°C to improve the absorption capacity of the acid solution absorption device 120; when the polonium content and the activity concentration of Po-210 are low, there is no need to start the cooling mechanism.

[0074] The covering gas enters the acid solution absorption device 120 for full contact reaction, and absorbs and dissolves the Po-210 in the covering gas into the strong acid solution. Further, the strong acid solution after dissolving the covering gas is introduced into the electrolysis device, and the Po-210 species dissolved in the acid solution are deposited on the surface of the solid material by electrodeposition, finally achieving efficient purification of the airborne radioactive Po-210 in the covering gas and minimization of waste.

[0075] S3: The purified gas after absorption is successively deacidified, dehumidified, heated and pressurized through the heating and pressurizing pipeline 130 and then transported back to the reactor blanketing gas system 200. The purified gas is discharged from the gas source output end of the acid solution absorption device 120, and the acid solution and the generated hydrogen are first removed by the deacidification tank 131, and then the moisture in the purified gas is removed by the dehumidification tank 132. When the second Po-210 activity monitoring device 133 detects that there is no radioactive nuclide polonium-210, the downstream isolation valve 134 is opened to pressurize and heat the treated purified gas; the purified gas is reheated and pressurized to the blanketing gas parameters in the reactor blanketing gas system 200 to reduce disturbance.

[0076] In summary, the advantages of the airborne radioactive Po-210 purification system and method in this embodiment are:

[0077] 1. The airborne radioactive Po-210 purification system of the present invention is provided with a temperature reduction and pressure reduction management, and the covering gas containing the airborne radioactive Po-210 drawn from the reactor covering gas system 200 is subjected to a temperature reduction and pressure reduction treatment. On the one hand, the specific activity of the airborne radioactive Po-210 can be increased, the operability of the subsequent acid solution purification process can be improved, and the safety of the purification process can be ensured; on the other hand, lowering the temperature of the covering gas can avoid the loss of the strong acid solution in the acid easy absorption device due to high temperature, and at the same time can protect the downstream drying device from being corroded by acidic substances;

[0078] 2. The gas after cooling and depressurization is injected into the acid solution absorption device 120, and the airborne radioactive Po-210 species reacts with the strong acid solution and dissolves in the strong acid solution, thereby completing one purification. The strong acid can be completely ionized in water, accelerating the dissolution of the polonium-containing species, thereby improving the single purification efficiency. The Po-210 species dissolved in the strong acid solution are further deposited on the surface of the solid material by an electrochemical deposition method, ultimately achieving efficient purification of the airborne radioactive Po-210 in the covering gas and minimizing waste.

[0079] 3. The purified gas enters the heating and pressurizing pipeline 130. Before heating and pressurizing, a deacidification and dehumidification component is designed to reduce acid corrosion to the heating and pressurizing pipeline 130. The purified gas is then heated and pressurized again to the gas temperature and pressure of the reactor cover gas system 200 through the heating and pressurizing pipeline 130 to ensure minimal disturbance to the temperature and pressure in the reactor.

[0080] 4. The overall airborne radioactive Po-210 purification system is easy to operate, has mild conditions, produces a small amount of waste, and reduces the frequency of human contact.

[0081] Second embodiment

[0082] This embodiment is further optimized based on the first embodiment. Figure 5 This embodiment provides an airborne radioactive Po-210 purification system, which also includes a cooling and depressurizing pipeline 110, an acid solution absorption device 120 and a heating and pressurizing pipeline 130 connected in sequence, but the cooling and depressurizing pipeline 110, the acid solution absorption device 120 and the heating and pressurizing pipeline 130 are all optimized.

[0083] The cooling and depressurizing pipeline 110 includes an upstream isolation valve 111, a circulation pump 112, a cooling and depressurizing device 113, and a first Po-210 activity monitoring device 114, which are connected in sequence through pipelines. Among them, the cooling and depressurizing device 113 includes a heat exchanger 1131 for cooling, and a spray-type absorption tower 1133. The covering gas after cooling enters the spray-type absorption tower 1133. Since the volume of the spray-type absorption tower 1133 is large, the covering gas after entering the spray-type absorption tower 1133 is depressurized. At the same time, the spray-type absorption tower 1133 sprays water, PbPo+H2O→H2Po+PbO. Since H2Po is an unstable gas, it can be decomposed into H2 and Po, so that Po and PbO in a solution state can be introduced into the electrolysis device for precipitation, and the covering gas carrying H2 enters the acid solution absorption device 120 for the purification process of the main Po-210 species. The advantage is that the amount of strong acid solution used can be reduced, reducing the purification burden of the acid solution absorption device 120, and the spray absorption tower 1133 can assist in cooling and reduce the energy consumption of the heat exchanger 1131.

[0084] The acid solution absorption device 120 is the same as that in the first embodiment, and also includes an electrolysis device 121. The difference is that the electrolysis device 121 can be divided into two groups, one group for electrolyzing the effluent solution of the acid solution absorption device 120, and the other group for electrolyzing the effluent solution of the spray absorption tower 1133, and the purpose is the same, that is, the airborne radioactive Po-210 dissolved in the acid solution / spray recovery liquid is deposited on the solid material surface of the electrolysis device 121 through the electrolysis device 121.

[0085] See also Figure 6 In order to ensure the reaction between the acid solution absorber 120 and the pretreated covering gas, an S-shaped flow channel 125 can be set up by isolating the acid solution absorber 120 through a partition 124. By extending the moving path of the covering gas, the reaction time of the strong acid solution and the covering gas can be increased, and the covering gas temperature can be reduced. The access end of the acid solution replenisher 123 is designed at the tail end of the S-shaped flow channel 125, so that the temperature of the covering gas is still slightly high before entering the S-shaped flow channel 125, and the reaction speed of the airborne radioactive Po-210 with the strong acid is slow, but after entering the middle and rear sections, after a period of time of heat exchange and cooling of the covering gas and the strong acid, the reaction speed of the airborne radioactive Po-210 with the strong acid becomes faster.

[0086] By using the acid solution absorption device 120 in the second embodiment, compared with the acid solution absorption device 120 in the first embodiment, the temperature of the covering gas and the reaction temperature of the strong acid solution can be further reduced, thereby reducing the vaporization of the strong acid solution and avoiding corrosion of downstream equipment; at the same time, the loss of the strong acid solution is reduced.

[0087] Furthermore, a spoiler 126 is provided at a relative position of each partition 124. The spoiler 126 may be a strong acid agitator, or may be provided by reducing the diameter of a pipe or accelerating blades to help the airborne radioactive Po-210 and the strong acid to fully react.

[0088] The outer wall of the acid solution absorption device 120 is provided with a jacket coil 127, and a spiral cooling coil is designed inside the jacket. The output end of the cooling coil is connected to the input end of the heat exchanger 1131, and the input end of the cooling coil is connected to the output end of the heat exchanger 1131, thereby realizing heat exchange and cooling.

[0089] The heating and pressurizing pipeline 130 includes an acid removal tank 131, a moisture removal tank 132, a hydrogen removal tank 136, a second Po-210 activity monitoring device 133, a downstream isolation valve 134 and a heating and pressurizing device 135 which are sequentially connected through pipelines.

[0090] Among them, the acid removal tank 131 adopts a multi-layer filtration method. An alkaline adsorption tank 1311 is arranged at the bottom as the first filter layer. Alkaline substances such as sodium hydroxide are arranged in the alkaline adsorption tank 1311 to constitute the first neutralization reaction layer. The acid gas reacts with the alkaline substance to generate salt and water, thereby removing the acid gas. The second filter layer 1312 is designed with an alumina-loaded deacidifier, which is a mesoporous material with a complex pore structure. After calcination pretreatment at 550°C, the specific surface area decreases and the pore size increases, so that the remaining acid gas can be further absorbed by the deacidifier.

[0091] In the dehydrogenation tank 136 , toluene and hydrogen react under the conditions of Ni or Pt catalyst and heating to generate 1-methylcyclohexane. The purified gas after heating can save energy consumption of the heating and pressure-boosting device 135 .

[0092] Generally, the hydrogen generated during the entire purification process does not need to be removed, and the method in the first embodiment can be used to control the deposition voltage and deposition time to minimize the amount of hydrogen generated. At the same time, there is a small amount of hydrogen in the covering gas, so the hydrogen content does not actually have a big impact on the covering gas.

[0093] However, in this embodiment, since the H2Po generated by the use of the spray absorption tower 1133 is an unstable gas that can be decomposed into H2 and Po, the excess H2 generated may affect the purification system or cover the gas. In this case, a separate hydrogen removal tank 136 in the second embodiment can be used to remove the excess hydrogen.

[0094] With respect to the airborne radioactive Po-210 purification system in the second embodiment, the purification method thereof includes:

[0095] S1: The temperature reduction and pressure reduction pipeline 110 leads the covering gas of the reactor covering gas system 200 from the covering gas output end, and introduces the covering gas into the acid solution absorption device 120 after temperature reduction and pressure reduction. Among them, the temperature reduction and pressure reduction device 113 adopts a heat exchanger 1131 and a spray absorption tower 1133. The heat exchanger 1131 reduces the temperature of the original covering gas to 200°C to 250°C, and then passes through the spray absorption tower 1133 for temperature reduction and pressure reduction treatment, and further controls the temperature of the covering gas to 150 to 200°C; the covering gas after temperature reduction and pressure reduction passes through the first Po-210 activity monitoring device 114 to detect the polonium content and the activity concentration of Po-210 entering the acid solution absorption device 120, thereby controlling the strong acid solution content and temperature in the acid solution absorption device 120. For example, when the polonium content and the activity concentration of Po-210 are high, new strong acid solution is appropriately added to the acid solution absorption device 120 through the acid solution replenisher 123 to reduce the temperature of the acid solution absorption device 120; when the polonium content is low and the activity concentration of Po-210 is low, the strong acid solution content and temperature of the acid solution absorption device 120 are maintained to reduce energy consumption.

[0096] S2: Po-210 in the covering gas is absorbed and dissolved into the strong acid solution, and then the dissolved Po-210 in the strong acid solution is further deposited on the surface of the solid material through the electrolysis device 121. The acid solution absorption device 120 is used as the first purification device, and the covering gas at 150-200°C enters the acid solution absorption device 120, and the contact solution can be further cooled. When the strong acid solution and the covering gas contact in the S flow channel, even if vaporization occurs, it will be eliminated in the rear section of the S flow channel, and the average temperature of the solution is controlled below 100°C; at the same time, according to the detection results of the first Po-210 activity monitoring device 114, for example: when the polonium content and the activity concentration of Po-210 are high, the cooling mechanism of the acid solution absorption device 120 is started, and the acid solution absorption device 120 is controlled at about 65°C to improve the absorption capacity of the acid solution absorption device 120; when the polonium content and the activity concentration of Po-210 are low, there is no need to start the cooling mechanism.

[0097] The covering gas enters the acid solution absorption device 120 for full contact reaction, and absorbs and dissolves the Po-210 in the covering gas into the strong acid solution. Further, the strong acid solution after the covering gas is introduced into the electrolysis device, and the Po-210 species dissolved in the acid solution are deposited on the surface of the solid material by deposition, finally achieving efficient purification of the airborne radioactive Po-210 in the covering gas and minimization of waste.

[0098] S3: The purified gas after absorption is successively deacidified, dehumidified, heated and pressurized through the heating and pressurizing pipeline 130 and then transported back to the reactor blanketing gas system 200. The purified gas is discharged from the gas source output end of the acid solution absorption device 120, and the acid solution is first removed by the deacidification tank 131, and then the moisture in the purified gas is removed by the dehumidification tank 132, and the generated hydrogen is removed by the hydrogen removal tank 136. When the second Po-210 activity monitoring device 133 detects that there is no radioactive nuclide polonium-210, the downstream isolation valve 134 is opened to pressurize and heat the treated purified gas; the purified gas is reheated and pressurized to the blanketing gas parameters in the reactor blanketing gas system 200 to reduce disturbance.

[0099] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An airborne radioactive Po-210 purification system, characterized in that: The purification system comprises: A temperature-reducing and pressure-reducing pipeline, one end of which is connected to a covering gas output end of a reactor covering gas system; The acid solution absorption device, the other end of the temperature reduction and pressure reduction pipeline is connected to the gas source input end of the acid solution absorption device, the airborne radioactive Po-210 reacts with the strong acid solution in the acid solution absorption device and dissolves in the strong acid solution; the solution discharge end of the acid solution absorption device is connected to an electrolysis device, and the airborne radioactive Po-210 species dissolved in the acid solution are deposited on the solid material surface of the electrolysis device through the electrolysis device; A heating and pressurizing pipeline, wherein both ends of the heating and pressurizing pipeline are respectively connected to the gas source output end of the acid solution absorption device and the gas input end of the reactor covering gas system; a deacidification and dehumidification component is also provided on the heating and pressurizing pipeline, and the purified gas purified by the acid solution absorption device is transported back to the reactor covering gas system after being deacidified, dehumidified, heated and pressurized in sequence.

2. The airborne radioactive Po-210 purification system according to claim 1, characterized in that: The temperature-reducing and pressure-reducing pipeline comprises an upstream isolation valve, a circulation pump, a temperature-reducing and pressure-reducing device and a first Po-210 activity monitoring device which are sequentially connected through pipelines.

3. The airborne radioactive Po-210 purification system according to claim 1, characterized in that: The hydrogen ion concentration in the acid solution absorption device is ≥1 mol / L.

4. The airborne radioactive Po-210 purification system according to claim 1, characterized in that: The strong acid solution in the acid solution absorption device includes one of nitric acid solution, sulfuric acid solution and hydrochloric acid solution or a mixed solution of multiple acids.

5. The airborne radioactive Po-210 purification system according to claim 1, characterized in that: The solution temperature of the acid solution absorption device is 60-100°C.

6. The airborne radioactive Po-210 purification system according to claim 1, characterized in that: The heating and pressurizing pipeline includes a deacidification tank, a dehumidification tank, a second Po-210 activity monitoring device, a downstream isolation valve, and a heating and pressurizing device which are sequentially connected through pipelines.

7. The airborne radioactive Po-210 purification system according to claim 1, characterized in that: The solution output end of the electrolysis device is also provided with a third Po-210 activity monitoring device.

8. The airborne radioactive Po-210 purification system according to claim 7, characterized in that: The deposition reaction temperature of the electrolytic device is 0-60°C.

9. The airborne radioactive Po-210 purification system according to claim 1, characterized in that: The acid solution absorption device further comprises an acid solution supplementer connected to the acid solution injection end of the acid solution absorption device.

10. A method for purifying airborne radioactive Po-210, comprising the airborne radioactive Po-210 purification system according to any one of claims 1 to 9, characterized in that: The airborne radioactive Po-210 purification method comprises: The temperature-reducing and pressure-reducing pipeline leads the covering gas of the reactor covering gas system from the covering gas output end, and introduces the covering gas into the acid solution absorption device after temperature-reducing and pressure-reducing, and the Po-210 in the covering gas is absorbed and dissolved into the strong acid solution, and then the Po-210 species dissolved in the strong acid solution are further deposited onto the surface of the solid material through the electrolysis device; The purified gas after absorption is successively deacidified, dehumidified, heated and pressurized through a heating and pressurizing pipeline and then transported back to the reactor covering gas system.

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