A reinforced sodium leakage early warning system and method for a sodium-cooled fast reactor primary circuit

Abstract

The present application relates to the technical field of nuclear reactor safety monitoring, and particularly relates to an enhanced sodium leakage early warning system and method for a sodium-cooled fast reactor primary loop, which comprises a shielding wall and an externally mounted machine case, the externally mounted machine case is fixed outside the shielding wall of a sodium process room and is used for integrated installation of internal components of the system; a sampling transmission mechanism penetrates through the shielding wall and enters the inside of the sodium process room, is used for collecting aerosol samples and connecting the externally mounted machine case to build a circulating gas path; and a negative pressure concentration unit is arranged inside the externally mounted machine case and is used for enrichment treatment of the collected aerosol samples. The negative pressure concentration unit forms a negative pressure three-dimensional rotating turbulent flow field, can efficiently enrich the micro-nano sodium aerosol generated in the initial stage of sodium leakage, improves the aggregation concentration of the trace sodium aerosol, improves the lower limit of the system detection, realizes the ultra-early warning of sodium leakage, and solves the problems of the existing technology, such as response lag and difficulty in early warning of trace leakage.

Description

Technical Field

[0001] This invention relates to the field of nuclear reactor safety monitoring technology, specifically to an enhanced sodium leakage early warning system and method for the primary loop of a sodium-cooled fast reactor. Background Technology

[0002] Sodium-cooled fast reactors (SNFRs) have been listed as a key preferred reactor type for fourth-generation nuclear energy systems due to their significant advantages in nuclear fuel breeding and transmutation of long-lived nuclear waste. Liquid metallic sodium, with its excellent thermal conductivity and neutronic properties, is commonly used as the cooling medium in the primary loop of SNFRs. However, liquid metallic sodium is extremely chemically reactive and easily oxidizes and burns upon contact with air. Damage to pipes, sodium containers, or other equipment can lead to sodium leaks and fires, seriously threatening the safe operation of the reactor. The sodium process room in the primary loop of SNFRs is constantly exposed to high temperatures and radiation, and contains numerous sodium transport and storage devices, making sodium leaks a significant hazard. Therefore, achieving ultra-early, highly sensitive, and large-area online monitoring of sodium leaks is a crucial technology for ensuring the safe and stable operation of SNFRs.

[0003] Currently, sodium leakage monitoring in the primary loop of sodium-cooled fast reactors mainly employs two technical approaches, both of which have significant shortcomings, specifically: The first type is the contact-type short-circuit sodium leak detector. This type of device utilizes the conductive properties of metallic sodium to trigger an alarm by causing a short circuit in the bimetallic wires through the dripping of liquid sodium. It can only achieve single-point or small-area monitoring and cannot cover large-area process spaces. When the leaking sodium liquid does not directly contact the detection electrode, it will miss the detection and cannot achieve early warning.

[0004] The second category is sodium aerosol optical detection technology, such as the sodium aerosol detection system in open air disclosed in prior art document CN218766496U. This system uses a high-repetition-rate, high-voltage nanosecond pulse spark discharge method to achieve sodium aerosol ionization excitation in an open space, and collects spectral signals with a time synchronization unit. It eliminates the need for carrier gases such as argon, reducing system power consumption and equipment complexity. However, this approach directly detects open air without enriching and concentrating trace amounts of sodium aerosol. It is insufficiently responsive to low-concentration, micro-nano-scale sodium aerosols generated in the early stages of a leak, exhibiting a high detection limit and limited sensitivity, making it difficult to meet the ultra-early warning requirements for sodium leaks in the primary loop of a sodium-cooled fast reactor. Furthermore, the system employs an open sampling and exhaust structure, failing to form a closed-loop gas path, resulting in direct gas emission, which is unsuitable for sodium process room environments with strict requirements for radioactivity and airtightness.

[0005] In addition, existing sodium aerosol detection devices generally suffer from problems such as low integration, inconvenient installation and layout, and insufficient radiation resistance and high temperature resistance. They cannot adapt to the complex operating conditions of high temperature, radiation, and confinement in the primary loop of sodium-cooled fast reactors. The detection response speed is slow and the early warning is delayed, making it difficult to conduct timely, reliable, and continuous online monitoring of trace sodium leaks.

[0006] Therefore, the industry urgently needs an enhanced sodium leakage early warning system that is highly integrated, has aerosol enrichment capabilities, low detection limits, fast response speed, and can form a circulating gas path within radioactive process rooms to compensate for the shortcomings of existing technologies. Summary of the Invention

[0007] The purpose of this invention is to provide an enhanced sodium leakage early warning system and method for the primary loop of a sodium-cooled fast reactor in order to solve the above-mentioned problems. By setting up a negative pressure enrichment unit to form a negative pressure three-dimensional rotating turbulent flow field, it is possible to efficiently enrich the micro-nano-scale sodium aerosols generated in the early stage of sodium leakage, improve the aggregation concentration of trace sodium aerosols, raise the detection limit of the system, realize ultra-early warning of sodium leakage, and solve the problems of delayed response and difficulty in early warning of trace leakage in the prior art. See the following description for details.

[0008] To achieve the above objectives, the present invention provides the following technical solution: This invention provides an enhanced sodium leakage early warning system for the primary loop of a sodium-cooled fast reactor, comprising: The shielding wall and the external mounting chassis are fixed to the outside of the shielding wall in the sodium process room and are used to integrate and install internal components of the system. The sampling and transmission mechanism penetrates the shielded wall and enters the sodium process room. It is used to collect aerosol samples and connect to an external mounting chassis to build a circulating gas path. The negative pressure concentration unit, located inside the external mounting chassis, is used to enrich the collected aerosol samples. The spectral detection unit is located inside the external mounting chassis and connected in parallel to the negative pressure concentration unit. It is used to detect sodium leakage in the enriched sample and output an early warning signal. The sampling and transmission mechanism's acquisition end is connected to the spectral detection unit through the negative pressure concentration unit, and the spectral detection unit and the negative pressure concentration unit are connected through the output end of the sampling and transmission mechanism and return to the sodium process room, forming a continuous circulation monitoring gas path. In operation, the sampling and transmission mechanism collects aerosols in the sodium process room and sends them to the negative pressure concentration unit for enrichment. The enriched sample enters the spectral detection unit for detection. The detected gas is then returned to the sodium process room via the sampling and transmission mechanism, achieving continuous online early warning.

[0009] As a preferred option, the external mounting chassis is equipped with power input terminals and analog output terminals, which are used for system power supply and early warning signal output, respectively.

[0010] As a preferred embodiment, the sampling and transmission mechanism includes two through-wall pipes: an inlet pipe and a outlet pipe. The through-wall pipes are sealed and pass through the shielding wall to extend into the sodium process room, with the ends forming a sampling probe and a reflux outlet, respectively.

[0011] Preferably, the negative pressure concentration unit includes a cyclone device, a flow meter and a fan connected in sequence, and the cyclone device is provided with an inlet for receiving the sample in the sample inlet tube.

[0012] Preferably, the fan is provided with a heat dissipation vent and a sample discharge port. The heat dissipation vent penetrates the outer wall of the external mounting chassis, and the sample discharge port is connected to the sample discharge pipe of the sampling and transmission mechanism.

[0013] Preferably, the cyclone device includes a swirl cone section and an overflow port and a concentration hopper connected to the upper and lower ports of the swirl cone section. The sample inlet is connected to the outside of the swirl cone section to form a negative pressure three-dimensional rotating turbulent flow field, which is used to enrich micro- and nano-sized sodium aerosols and collect dust. Specifically, it collects dust from the gas sample to prevent dust from entering the spectrometer and affecting the instrument's operation.

[0014] Preferably, the spectral detection unit is a microwave plasma spectral detection unit, used to perform sodium element characteristic spectral detection on the enriched sample.

[0015] This invention also provides an enhanced sodium leakage early warning method for the primary loop of a sodium-cooled fast reactor, comprising the following steps: S1. Collect aerosol samples from the sodium process room using a sampling and transmission mechanism; S2. The collected aerosol samples are sent to the negative pressure concentration unit for enrichment. S3. The enriched sample is sent to the spectral detection unit for sodium leakage detection. The spectral detection results are used to determine whether sodium leakage has occurred and an early warning signal is output. S4. The gas that has been tested is returned to the sodium process room to form a cycle monitoring.

[0016] As a preferred method, sodium aerosol enrichment is achieved in S2 through a negative pressure three-dimensional rotating turbulent flow field, and detection in S3 is performed using microwave plasma spectroscopy.

[0017] The beneficial effects are as follows: 1. By setting up a negative pressure concentration unit to form a negative pressure three-dimensional rotating turbulent flow field, the present invention can efficiently enrich the micro-nano-scale sodium aerosols generated in the early stage of sodium leakage. Compared with the open air direct detection method used in the prior art, it greatly improves the aggregation concentration of trace sodium aerosols, raises the detection limit of the system, realizes ultra-early warning of sodium leakage, and solves the problem of delayed response and difficulty in early warning of trace leakage in the prior art.

[0018] 2. A closed-loop gas path is formed by the combination of the sample inlet pipe and the sample outlet pipe. The gas after detection flows back to the sodium process room through the sample outlet pipe, without being emitted to the external environment and without damaging the gas environment inside the chamber. It is fully compatible with the special operating conditions of the primary loop of the sodium-cooled fast reactor with radioactive confinement. It overcomes the defect that open detection systems cannot be used in the closed space of the nuclear island and improves the safety and environmental adaptability of the system.

[0019] 3. This invention uses a microwave plasma spectral detection unit to perform sodium element characteristic spectral detection on the enriched sample. The detection process is simple and the signal response is rapid, which can shorten the overall detection response time. It can quickly output an early warning signal after a leak occurs, avoiding the expansion of the leak and causing safety accidents such as fire and equipment damage due to delayed early warning.

[0020] 4. The layout adopts an external mounting chassis combined with through-wall sampling. The core components such as the negative pressure concentration unit and the spectral detection unit are integrated and installed in the external chassis outside the shielded wall. Only the sampling and transmission mechanism extends into the high temperature and high radiation sodium process room, which significantly reduces the impact of high temperature and radiation on the core electronic components and improves the system's operational stability and service life.

[0021] 5. The system features a full-area gas path sampling and monitoring mode, which can cover a large monitoring area within the sodium process room. It no longer relies on liquid sodium directly contacting the electrodes to trigger an alarm, fundamentally solving the problem that traditional distributed short-circuit detectors can only achieve single-point or small-area monitoring and are prone to missed detections. This improves the completeness and reliability of sodium leak monitoring.

[0022] 6. The system of this invention has a highly integrated overall structure. It can complete the entire process of sampling, enrichment and detection by relying on the cyclone device, fan and spectral detection unit. The system has low power consumption, simple structure and easy installation and deployment. It can achieve long-term continuous automated operation and reduce on-site operation and maintenance costs and difficulties. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a three-dimensional structural schematic diagram of the present invention; Figure 2 This is a schematic diagram of the internal structure of the external mounting chassis of the present invention; Figure 3 This is a front view structural diagram of the cyclone device of the present invention; Figure 4 This is a three-dimensional structural schematic diagram of the cyclone device of the present invention; Figure 5 This is a rear view structural diagram of the cyclone device of the present invention; Figure 6 This is a graph showing the change in sodium aerosol detection concentration over time for Group 1 of this invention; Figure 7This is a graph showing the change in sodium aerosol detection concentration over time for Group 2 of this invention; Figure 8 This is a graph showing the change in sodium aerosol detection concentration over time for Group 3 of this invention; Figure 9 This is a graph showing the change in sodium aerosol detection concentration over time for Group 4 of this invention.

[0025] The annotations in the attached figures are explained as follows: 1. Shielding wall; 2. External mounting chassis; 201. Power input terminal; 202. Analog output terminal; 3. Sampling and transmission mechanism; 301. Sample inlet tube; 302. Sample outlet tube; 4. Spectroscopic detection unit; 5. Negative pressure concentration unit; 501. Cyclone device; 501a. Sample inlet; 501b. Cyclone cone section; 501c. Concentrator hopper; 501d. Overflow port; 502. Flow meter; 503. Fan; 503a. Fan heat dissipation port; 503b. Sample outlet. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0027] It should be noted that all directional and positional terms used in this invention, such as "up," "down," "left," "right," "front," "back," "vertical," "horizontal," "inner," "outer," "top," "lower," "lateral," "longitudinal," and "center," are only used to explain the relative positional relationships and connections between components in a specific state (as shown in the accompanying drawings). They are merely for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0028] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0030] See Figures 1-9 As shown, the present invention provides an enhanced sodium leakage early warning system for the primary loop of a sodium-cooled fast reactor, comprising: The shielding wall 1 and the external mounting box 2 are fixed outside the shielding wall 1 in the sodium process room. The external mounting box 2 is used to integrate and install the internal components of the system, thereby isolating the core electrical components from the high temperature and high radiation environment of the process room and improving the system stability and service life. The sampling and transmission mechanism 3 penetrates the shielded wall 1 and enters the sodium process room. It is used to collect aerosol samples and connect to the external mounting box 2 to build a circulating gas path. This is used to achieve uninterrupted extraction of aerosols throughout the sodium process room and avoid the problem of missed detection by traditional contact detectors. The negative pressure concentration unit 5 is located inside the external mounting chassis 2 and is used to enrich the collected aerosol samples, thereby efficiently aggregating trace amounts and low concentrations of micro-nano-scale sodium aerosols, significantly improving detection sensitivity and response speed. The spectral detection unit 4 is located inside the external mounting chassis 2 and connected in parallel to the negative pressure concentration unit 5. It is used to detect sodium leakage in the enriched sample and output an early warning signal. Then, the detection signal is output to the reactor control system through a standard interface to realize alarm and interlock protection. The sampling and transmission mechanism 3 is connected to the spectral detection unit 4 through the negative pressure concentration unit 5, and the spectral detection unit 4 and the negative pressure concentration unit 5 are connected through the output end of the sampling and transmission mechanism 3 and return to the sodium process room to form a continuous circulation monitoring gas path, so as not to release gas to the outside world, not to damage the closed process room environment, and to meet the requirements for safe use of the nuclear island. In operation, the sampling and transmission mechanism 3 collects aerosols in the sodium process room and sends them to the negative pressure concentration unit 5 for enrichment. The enriched sample enters the spectral detection unit 4 for detection. The detected gas is returned to the sodium process room via the sampling and transmission mechanism 3, realizing continuous online early warning.

[0031] As an optional implementation, the external mounting chassis 2 is equipped with a power input terminal 201 and an analog output terminal 202, which are used for system power supply and early warning signal output, respectively. Specifically, with this configuration, through standardized electrical interface design, it can be directly connected to the field monitoring system without additional conversion, thereby improving system compatibility and deployment efficiency. The sampling and transmission mechanism 3 includes two through-wall pipes: an inlet pipe 301 and an outlet pipe 302. The through-wall pipes pass through the shielding wall 1 in a sealed manner and extend into the sodium process room to ensure reliable communication between the gas path inside and outside the process room and to maintain the airtightness of the shielding wall 1. The ends of the pipes form a sampling probe and a return outlet, respectively, thereby ensuring that the sampling probe can capture aerosols over a wide range. The return outlet smoothly sends the detected gas back to the process room. With this configuration, full-process room coverage monitoring can be achieved, and the circuit is sealed and leak-free. The negative pressure concentration unit 5 includes a cyclone device 501, a flow meter 502, and a fan 503 connected in sequence. The cyclone device 501 is provided with an inlet 501a for receiving the sample in the sample inlet tube 301. The flow meter 502 is used to monitor the gas flow in real time to ensure that the sampling and concentration process is stable and controllable. The fan 503 is used to generate negative pressure, thereby providing power for the entire circulating gas path and realizing continuous and stable sample extraction and delivery. With this setting, the gas path state can be precisely controlled to ensure enrichment effect and detection repeatability. The fan 503 is equipped with a fan heat dissipation port 503a and a sample discharge port 503b. The heat dissipation port penetrates the outer wall of the external mounting box 2, and the sample discharge port 503b is connected to the sample discharge pipe 302 of the sampling and transmission mechanism 3, so as to dissipate the working heat of the fan 503 in a timely manner and avoid heat accumulation inside the box. This setting helps to extend the continuous working life of the fan 503, while ensuring the smooth closed-loop air passage. The cyclone device 501 includes a swirl cone section 501b and an overflow port 501d and a concentration hopper 501c connected to the upper and lower ports of the swirl cone section 501b. The overflow port 501d is used to discharge the concentrated and separated gas, and the concentration hopper 501c is used to collect the enriched high-concentration sodium aerosol particles to prevent particle backflow and improve enrichment efficiency. The sample inlet 501a is connected to the outside of the swirl cone section 501b to form a negative pressure three-dimensional rotating turbulent flow field, thereby enabling the aerosol to be rapidly separated and enriched under the action of centrifugal force. It is used to enrich micro- and nano-sized sodium aerosols to raise the detection limit by 1 to 3 orders of magnitude and achieve ultra-early warning. It is also used for dust collection, specifically by collecting dust in the gas sample to prevent dust from entering the spectrometer and affecting the instrument's operation. In addition, the external connection of the concentration hopper 501c is an outwardly extending detection return interface and detection exit interface, and the detection return interface is located above the detection exit interface. This setting facilitates the formation of a stable internal flow field and pressure balance, allowing high-concentration samples to be output smoothly and avoiding air blockage or backflow. Both the sample return interface and the sample output interface are connected to an external spectrometer used as a detection device. By connecting the interface on the spectrometer, a closed sampling and gas return loop is formed. In this way, the internal pressure of the detection system can be stabilized, the sample can be continuously transported, and the accuracy of the detection data can be improved.

[0032] The spectral detection unit 4 is a microwave plasma spectral detection unit. This configuration is used to perform sodium element characteristic spectral detection on the enriched sample, thereby quickly identifying sodium characteristic spectral lines and shortening the response time.

[0033] An enhanced sodium leakage early warning method for the primary circuit of a sodium-cooled fast reactor includes the following steps: S1. Aerosol samples are collected from the sodium process room through the sampling and transmission mechanism 3. Specifically, the sampling tube 301 continuously extracts the air and sodium aerosol mixture in the process room under the negative pressure of the fan 503 to achieve sampling without dead angles in the whole area. S2. The collected aerosol samples are sent to the negative pressure concentration unit 5 for enrichment. Specifically, the samples are processed by the cyclone device 501 to form a negative pressure three-dimensional rotating turbulent flow field, and the micro-nano sodium aerosols are efficiently enriched and concentrated, greatly increasing the concentration of the analyte. S3. The enriched sample is sent to the spectral detection unit 4 for sodium leakage detection. The spectral detection results determine whether sodium leakage has occurred and output an early warning signal. With this setting, the characteristic spectrum of sodium element is excited by microwave plasma to achieve accurate identification of trace leakage. The signal is stable and has strong anti-interference ability. S4. The gas that has been tested is returned to the sodium process room to form a cycle monitoring. In this way, the gas is not discharged from the sodium process room, which helps to protect the environment and meets the stringent requirements of nuclear industry for airtightness, safety and environmental protection.

[0034] In S2, sodium aerosol enrichment is achieved through a negative pressure three-dimensional rotating turbulent field. In S3, microwave plasma spectroscopy is used for detection, thus ensuring that the monitoring system has both high sensitivity and fast response capability, meeting the requirements of ultra-early, high-reliability, and continuous online early warning of sodium leakage in the primary loop of the sodium-cooled fast reactor.

[0035] By setting up a negative pressure concentration unit 5 to form a negative pressure three-dimensional rotating turbulent flow field, it is possible to efficiently enrich the micro-nano-scale sodium aerosols generated in the early stage of sodium leakage. Compared with the open air direct detection method used in the existing technology, it significantly improves the aggregation concentration of trace sodium aerosols, raises the detection limit of the system, realizes ultra-early warning of sodium leakage, and solves the problem of delayed response and difficulty in early warning of trace leakage in the existing technology.

[0036] The system uses an inlet pipe 301 and an outlet pipe 302 to form a closed-loop gas path. The gas detected is returned to the sodium process room through the outlet pipe 302 without being emitted to the external environment or disrupting the gas environment inside the room. This system is fully compatible with the special operating conditions of the sodium-cooled fast reactor, which is closed in the primary loop and has radioactive confinement. It overcomes the shortcomings of open detection systems that cannot be used in the closed space of the nuclear island, and improves the system's safety and environmental adaptability.

[0037] This invention uses a microwave plasma spectral detection unit 4 to perform sodium element characteristic spectral detection on the enriched sample. The detection process is simple and the signal response is rapid, which can shorten the overall detection response time. It can quickly output an early warning signal after a leak occurs, avoiding the expansion of the leak and the occurrence of safety accidents such as fire and equipment damage due to delayed early warning.

[0038] By adopting an external mounting chassis 2 and a layout that combines through-wall sampling, core components such as the negative pressure concentration unit 5 and the spectral detection unit 4 are integrated and installed in the external chassis outside the shielded wall 1. Only the sampling and transmission mechanism 3 extends into the high-temperature and high-irradiation sodium process room, which significantly reduces the impact of high temperature and irradiation on the core electronic components and improves the system's operational stability and service life.

[0039] The system employs a full-area gas path sampling and monitoring method, which can cover a large monitoring area within the sodium process room. It no longer relies on liquid sodium directly contacting the electrodes to trigger an alarm, fundamentally solving the problem that traditional distributed short-circuit detectors can only achieve single-point or small-area monitoring and are prone to missed detections. This improves the completeness and reliability of sodium leak monitoring.

[0040] The system of this invention has a highly integrated overall structure. It can complete the entire process of sampling, enrichment and detection by relying on the cyclone device 501, the fan 503 and the spectral detection unit 4. The system has low power consumption, simple structure and is easy to install and deploy. It can achieve long-term continuous automated operation and reduce on-site operation and maintenance costs and difficulties.

[0041] To verify the technical effectiveness of the short-circuit flow-controlled negative pressure cyclone aerosol concentrator of this invention, four sets of comparative experiments were conducted using the device of this invention and conventional unenhanced spectral detection under the same detection environment, same gas source concentration, same sampling flow rate, and same negative pressure dynamic conditions. The experimental object was micro-nano-scale sodium aerosol generated by a simulated leak in a sodium-cooled fast reactor. The experimental system included an aerosol generating device, a sampling pipeline, the concentrator of this invention, a conventional negative pressure cyclone separator, a microwave plasma spectral detection unit, and a data acquisition system.

[0042] I. Experimental Conditions Experimental medium: sodium-cooled fast reactor simulating leaked sodium aerosol Sampling flow rate: kept constant throughout. System power: negative pressure drive, fan load is the same. Detection target: 0.1-1μm micro / nano sodium aerosol Environmental conditions: Temperature, humidity, and ventilation conditions should be kept consistent with those of the reactor process. Comparison objects: Experimental group: Short-circuit flow controlled negative pressure cyclone aerosol concentration device of the present invention Control group: Traditional negative pressure cyclones without annular microchannels, short-circuit flow suppression cavities, or short-circuit flow control structures. II. Comparative experimental data are as follows

[0043] III. Explanation of Experimental Results Group 1 (see Figure 6 Under high-concentration leakage conditions, the device of this invention can quickly trigger an alarm in 102.5 seconds, with a peak concentration as high as 15994.1 ppb, and can continuously and stably detect for 10 minutes; conventional spectral detection has no concentration signal and no alarm throughout the entire process.

[0044] Group 2 (see Figure 7 Under medium-concentration leakage conditions, the device of this invention can alarm in 600 seconds, with a peak concentration of 2128.7 ppb, and can continuously detect for up to 85 minutes; conventional spectral detection still has no response.

[0045] Group 3 (see Figure 8 Under low-concentration leakage conditions, the device of this invention can still detect leaks stably for 2580s, achieving early warning of trace leaks; conventional spectral detection cannot capture low-concentration aerosols at all, and there is no detection data.

[0046] Group 4 (see Figure 9 Under optimal response conditions, the device of this invention has a response time of 72.5s, which can achieve ultra-early warning of sodium leakage; conventional spectral detection still has no response.

[0047] IV. Experimental Conclusions This invention solves the short-circuit escape problem of traditional hydrocyclones by using a short-circuit flow suppression cavity and an annular microchannel structure, achieving a capture efficiency of ≥95% for micro- and nano-sized sodium aerosols and a concentration factor of ≥1000 times.

[0048] Under high, medium, and low concentration leakage simulations, the device of this invention can output detection signals quickly, stably, and accurately, while conventional spectral detection has no response, no alarm, and no detection data throughout the entire process. Therefore, this invention can realize ultra-early, highly sensitive, and blind-zone-free online monitoring of trace sodium leakage in sodium-cooled fast reactors, meeting the safety early warning requirements of the nuclear industry.

[0049] This invention solves the short-circuit escape problem by setting a coaxial annular microchannel in the straight section of the hydrocyclone and dividing the internal flow field into an outer swirling cavity and a central short-circuit flow suppression cavity. The vertical direct exhaust flow destroys the quasi-rigid central vortex core of the traditional hydrocyclone, blocking the path of fine particles to escape directly along the overflow pipe. This forces the escaped particles to return to the swirling cavity to participate in centrifugal separation again. The escape rate of micro and nano particles can be reduced from more than 10% to less than 2%, thus solving the short-circuit escape problem.

[0050] As a physical separation structure, the annular microchannel forcibly separates the outer swirling flow field from the central straight flow field, avoiding the mixing and disturbance of the two airflows. This makes the swirling flow field more stable and the pressure fluctuation smaller. It can maintain stable separation efficiency under negative pressure drive, flow fluctuation and long-term continuous operation conditions, without clogging or attenuation, and is suitable for the long-term online monitoring requirements of nuclear industry sites.

[0051] Using negative pressure as the separation power, the blower is placed at the outlet end of the overflow pipe, so that the gas containing aerosols is first separated and concentrated by cyclone separation, and then the clean gas comes into contact with the blower. This changes the harm of direct contact between the blower and unseparated aerosols in the traditional positive pressure sampling, avoids the wear, corrosion and adhesion of sodium aerosol particles to the blower blades and cavity, eliminates the safety hazards of particle accumulation, blockage, heat generation and even combustion and explosion, and improves the safety of on-site operation in the nuclear industry.

[0052] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An enhanced sodium leakage early warning system for the primary loop of a sodium-cooled fast reactor, characterized in that, include: The shielding wall (1) and the external mounting box (2) are fixed outside the shielding wall (1) of the sodium process room and are used to integrate the internal components of the installation system. The sampling and transmission mechanism (3) penetrates the shielded wall (1) and enters the sodium process room to collect aerosol samples and connect to the external mounting box (2) to construct a circulating gas path; The negative pressure concentration unit (5) is located inside the external mounting box (2) and is used to enrich the collected aerosol samples. The spectral detection unit (4) is located inside the external mounting chassis (2) and connected in parallel to the negative pressure concentration unit (5) for detecting sodium leakage in the enriched sample and outputting an early warning signal. The sampling and transmission mechanism (3) is connected to the spectral detection unit (4) through the negative pressure concentration unit (5), and the spectral detection unit (4) and the negative pressure concentration unit (5) are connected through the output end of the sampling and transmission mechanism (3) and returned to the sodium process room to form a continuous circulation monitoring gas path. In operation, the sampling and transmission mechanism (3) collects aerosols in the sodium process room and sends them to the negative pressure concentration unit (5) for enrichment. The enriched sample enters the spectral detection unit (4) for detection. The detected gas is returned to the sodium process room via the sampling and transmission mechanism (3) to achieve continuous online early warning.

2. The enhanced sodium leakage early warning system for the primary loop of a sodium-cooled fast reactor according to claim 1, characterized in that, The external mounting chassis (2) is equipped with a power input terminal (201) and an analog output terminal (202), which are used for system power supply and early warning signal output, respectively.

3. The enhanced sodium leakage early warning system for the primary loop of a sodium-cooled fast reactor according to claim 1, characterized in that, The sampling and transmission mechanism (3) includes two through-wall pipes: a sample inlet pipe (301) and a sample outlet pipe (302). The through-wall pipes are sealed and pass through the shielding wall (1) and extend into the sodium process room. The ends of the pipes form a sampling probe and a reflux outlet, respectively.

4. The enhanced sodium leakage early warning system for the primary loop of a sodium-cooled fast reactor according to claim 3, characterized in that, The negative pressure concentration unit (5) includes a cyclone device (501), a flow meter (502) and a fan (503) connected in sequence. The cyclone device (501) is provided with an inlet (501a) for receiving the sample in the sample inlet tube (301).

5. The enhanced sodium leakage early warning system for the primary loop of a sodium-cooled fast reactor according to claim 4, characterized in that, The fan (503) is provided with a fan heat dissipation port (503a) and a sample discharge port (503b). The heat dissipation port penetrates the outer wall of the external mounting box (2), and the sample discharge port (503b) is connected to the sample discharge pipe (302) of the sampling and transmission mechanism (3).

6. The enhanced sodium leakage early warning system for the primary loop of a sodium-cooled fast reactor according to claim 5, characterized in that, The cyclone device (501) includes a swirl cone section (501b) and an overflow port (501d) and a concentration hopper (501c) connected to the upper and lower ports of the swirl cone section (501b). The sample inlet (501a) is connected to the outside of the swirl cone section (501b) to form a negative pressure three-dimensional rotating turbulent field for enriching micro- and nano-sized sodium aerosols.

7. The enhanced sodium leakage early warning system for the primary loop of a sodium-cooled fast reactor according to claim 1, characterized in that, The spectral detection unit (4) is a microwave plasma spectral detection unit, used to perform sodium element characteristic spectral detection on the enriched sample.

8. A method for enhanced sodium leakage early warning in the primary circuit of a sodium-cooled fast reactor, characterized in that, Includes the following steps: S1. Collect aerosol samples from the sodium process room through the sampling and transmission mechanism (3); S2. The collected aerosol samples are sent to the negative pressure concentration unit (5) for enrichment. S3. The enriched sample is sent to the spectral detection unit (4) for sodium leakage detection. The spectral detection results are used to determine whether sodium leakage has occurred and output an early warning signal. S4. The gas that has been tested is returned to the sodium process room to form a cycle monitoring.

9. The enhanced sodium leakage early warning method for the primary circuit of a sodium-cooled fast reactor according to claim 8, characterized in that, In S2, sodium aerosol enrichment is achieved through a negative pressure three-dimensional rotating turbulent flow field, while in S3, detection is performed using microwave plasma spectroscopy.

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