Reactor coolant system flow monitoring device and signal control method

Abstract

The invention discloses a reactor coolant system flow monitoring device and a signal control method, and belongs to the technical field of reactor coolant systems.The reactor coolant system comprises at least three main loops, a first pressure tapping hole located in the outer wall is formed in a main pipeline transition section elbow of each main loop, and a second pressure tapping hole located in the outer wall is formed in the main pipeline transition section elbow of each main loop; the at least four second pressure tapping holes are formed in the inner wall; the flow monitoring device comprises at least four first differential pressure sensors and at least two second differential pressure sensors; the positive pressure ends of the at least four first differential pressure sensors are communicated with the first pressure tapping hole, and the negative pressure ends of the at least four first differential pressure sensors are communicated with the at least four second pressure tapping holes in a one-to-one correspondence mode. The at least two second differential pressure sensors are arranged in parallel, and the two ends of the at least two second differential pressure sensors communicate with an inlet pipeline and an outlet pipeline of the main pump on the main loop correspondingly.

Description

Technical Field

[0001] This application belongs to the technical field of reactor coolant systems, specifically relating to a reactor coolant system flow monitoring device and signal control method. Background Technology

[0002] In the field of nuclear power generation, the reactor coolant system, as a core component of the nuclear reactor, plays a crucial role in removing heat from the reactor core, maintaining normal reactor operation, and ensuring safe shutdown. This system typically contains at least three main loops, and the flow parameters within each main loop directly affect the reactor's thermohydraulic characteristics, equipment operating status, and overall safety. Abnormal flow parameters can lead to serious safety incidents such as coolant leakage and core overheating.

[0003] Therefore, there is an urgent need for a monitoring device to accurately monitor the flow parameters in each main circuit. Summary of the Invention

[0004] In view of this, this application provides a reactor coolant system flow monitoring device and signal control method, the main purpose of which is to accurately monitor the flow parameters in each main loop of the reactor coolant system in order to ensure the stability of the reactor's thermal-hydraulic characteristics, safe operation of equipment, and overall safety.

[0005] To achieve the above objectives, this application mainly provides the following technical solutions:

[0006] In a first aspect, this application provides a reactor coolant system flow monitoring device, wherein the reactor coolant system includes at least three main loops, and each main loop has a first pressure tap located on the outer wall and at least four second pressure taps located on the inner wall at the bend of the main pipe transition section.

[0007] The flow monitoring device includes:

[0008] At least four first differential pressure sensors, the positive pressure ends of at least four first differential pressure sensors are all connected to the first pressure tapping holes, and the negative pressure ends of at least four first differential pressure sensors are connected to at least four second pressure tapping holes one by one;

[0009] At least two second differential pressure sensors are connected in parallel, and the two ends of the at least two second differential pressure sensors are respectively connected to the inlet pipe and the outlet pipe of the main pump in the main circuit.

[0010] Optionally, the first pressure tap and at least four second pressure taps are located in the same cross section perpendicular to the flow path direction, and the circumferential angle between two adjacent second sampling holes is 14 to 16 degrees.

[0011] Optionally, a flow limiting pipe seat is provided at the connection between the first differential pressure sensor and the first pressure tap, the connection between the first differential pressure sensor and the second pressure tap, and the connection between the second differential pressure sensor and the inlet pipe and outlet pipe of the main pump; the diameter of the flow limiting hole of the flow limiting pipe seat is 9 to 10 mm.

[0012] Optionally, isolation valves are provided on the connecting pipes of the first differential pressure sensor and the first pressure tap, the connecting pipes of the first differential pressure sensor and the second pressure tap, and the connecting pipes of the second differential pressure sensor and the inlet and outlet pipes of the main pump.

[0013] A second aspect of this application provides a reactor coolant system signal control method, applied to the reactor coolant system flow monitoring device described in any one of the above claims, the method comprising:

[0014] Based on the differential pressure measurements of the four first differential pressure sensors in each main loop, calculate the four flow rates corresponding to the four first differential pressure sensors in each main loop;

[0015] Each of the four flow values ​​is compared with a first preset threshold. When at least two of the flow values ​​are less than the first preset threshold, an insufficient flow signal is output.

[0016] Specifically, when all three main loops output the insufficient flow signal, a forced cycle loss signal is triggered; when at least one of the main loops outputs the insufficient flow signal and simultaneously meets the reactor neutron flux lower limit of 10%, a reactor shutdown signal is triggered; when at least two of the main loops output the insufficient flow signal and simultaneously meet the reactor neutron flux lower limit of 30%, a reactor shutdown signal is also triggered.

[0017] Optionally, the first preset threshold is a critical safe flow rate value.

[0018] A third aspect of this application provides another signal control method for a reactor coolant system, applied to the reactor coolant system flow monitoring device described in any one of the above claims, the method comprising:

[0019] Based on the differential pressure measurements of the four first differential pressure sensors in each main loop, calculate the four flow rates corresponding to the four first differential pressure sensors in each main loop;

[0020] Each of the four flow rates is compared with a second preset threshold. When at least two of the flow rates are greater than the second preset threshold, a sufficient flow signal is output.

[0021] When all three main circuits output the sufficient flow signal, and simultaneously meet the normal reactor coolant pressure signal and the normal reactor hot zone temperature signal, the enable signal is triggered.

[0022] Optionally, the second preset threshold is the lower limit of the rated operating flow rate.

[0023] A fourth aspect of this application provides yet another method for signal control of a reactor coolant system, applied to the reactor coolant system flow monitoring device described in any one of the above claims, the method comprising:

[0024] The six second differential pressure sensors in the three main circuits are divided into a first group and a second group, each group including three second differential pressure sensors corresponding to the main pumps of the three main circuits respectively;

[0025] When at least two of the second differential pressure sensors in any group output abnormal signals, and the reactor injection signal is met at the same time, the main pump shutdown signal is triggered.

[0026] Optionally, the abnormal signal is when the difference between the measured value and the rated value of the second differential pressure sensor exceeds a preset threshold range.

[0027] By employing the above technical solution, this application has at least the following beneficial effects:

[0028] The reactor coolant system flow monitoring device and signal control method provided in the embodiments of this application utilize centrifugal force to create a pressure difference when fluid flows through the bend in the transition section of the main pipeline. According to Bernoulli's equation and fluid mechanics formulas, the pressure difference is proportional to the square of the flow rate, and the flow rate can be calculated by measuring the pressure difference. Here, at least four second pressure taps are provided on the inner wall of the bend, each corresponding to at least four first differential pressure sensors. This allows for the acquisition of multiple sets of differential pressure data, further improving the accuracy, reliability, and fault diagnosis capabilities of flow measurement, and reducing fluctuations in the main loop flow measurement of the reactor coolant system under steady-state operation and accident conditions. Simultaneously, by connecting the inlet and outlet pipes of the main pump to the second differential pressure sensors, the pressure difference across the main pump can be monitored in real time, thereby assessing the operating status of the main pump and ensuring the safe and reliable operation of the reactor coolant system. Here, at least two second differential pressure sensors are connected in parallel to the inlet and outlet pipes of the main pump. Even if one second differential pressure sensor fails, the other can still operate normally, ensuring the redundancy and reliability of the monitoring device and avoiding data interruption due to a single point of failure. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of a reactor coolant system flow monitoring device according to an optional embodiment of this application;

[0030] Figure 2This is a schematic diagram of the cross-section of the bend perpendicular to the flow path direction in an optional embodiment of this application;

[0031] Figure 3 This is a schematic diagram of the structure of a flow-limiting tube seat according to an optional embodiment of this application;

[0032] Figure 4 A logic diagram of a reactor coolant system signal control method according to an optional embodiment of this application;

[0033] Figure 5 A logic diagram of a reactor coolant system signal control method according to another optional embodiment of this application;

[0034] Figure 6 This is a logic diagram of a reactor coolant system signal control method according to another optional embodiment of this application.

[0035] The reference numerals in the attached figures are as follows:

[0036] 1. First differential pressure sensor; 2. Second differential pressure sensor; 3. Flow limiting pipe seat; 31. Flow limiting orifice; 4. Isolation valve. Detailed Implementation

[0037] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0039] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., 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 or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0040] The preferred embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0041] See also Figures 1 to 3 As shown, according to an embodiment of this application, a reactor coolant system flow monitoring device is provided. The reactor coolant system includes at least three main loops. Each main loop has a first pressure tap located on the outer wall and at least four second pressure taps located on the inner wall at the bend of the main pipe transition section. The flow monitoring device includes at least four first differential pressure sensors 1 and at least two second differential pressure sensors. The positive pressure ends of the at least four first differential pressure sensors 1 are all connected to the first pressure taps, and the negative pressure ends of the at least four first differential pressure sensors 1 are connected to the at least four second pressure taps in a one-to-one correspondence. The at least two second differential pressure sensors are arranged in parallel, and the two ends of the at least two second differential pressure sensors are respectively connected to the inlet pipe and outlet pipe of the main pump on the main loop.

[0042] In this embodiment, when the fluid flows through the bend in the transition section of the main pipeline, it is subjected to centrifugal force, creating a pressure difference. According to Bernoulli's equation and fluid mechanics formulas, the pressure difference is proportional to the square of the flow rate. The flow rate can be calculated by measuring the pressure difference. Here, at least four second pressure taps are provided on the inner wall of the bend, each corresponding to at least four first differential pressure sensors 1. This allows for the acquisition of multiple sets of differential pressure data, further improving the accuracy, reliability, and fault diagnosis capabilities of flow measurement, and reducing fluctuations in the main loop flow measurement of the reactor coolant system under steady-state operation and accident conditions. Simultaneously, by connecting the inlet and outlet pipes of the main pump to the second differential pressure sensor 2, the pressure difference across the main pump can be monitored in real time, thereby assessing the operating status of the main pump and ensuring the safe and reliable operation of the reactor coolant system. Here, at least two second differential pressure sensors 2 are connected in parallel to the inlet and outlet pipes of the main pump. Even if one second differential pressure sensor 2 fails, the other can still operate normally, ensuring the redundancy and reliability of the monitoring device and avoiding data interruption due to a single point of failure.

[0043] The reactor can be a pressurized water reactor, a heavy water reactor, etc., and this application does not limit it. In this embodiment, the reactor is a third-generation pressurized water reactor.

[0044] The reactor coolant system comprises the reactor pressure vessel and the main loop. The reactor pressure vessel houses the nuclear fuel assemblies, control rods, and other core components, and its interior is a high-temperature, high-pressure coolant environment. The main loop is a closed-loop system built around the reactor pressure vessel, used to transfer the heat generated by nuclear fission in the reactor core to the steam generator, which in turn drives the turbine to generate electricity.

[0045] The main circuit can be configured with three or four main circuits. In this embodiment, three main circuits are configured.

[0046] Each main loop includes a main pipeline, a steam generator, and a main pump. The main pipeline connects the reactor to the steam generator and the main pump, and includes structures such as a transition section and a cold section. The steam generator transfers heat from the coolant to the secondary water via heat transfer tubes to generate steam. The water pump drives the coolant circulation, overcoming system resistance. In this embodiment, the transition section is a segment of the main pipeline located between the steam generator and the main pump, while the bend is a curved structure within the transition section used to change the direction of the pipeline.

[0047] The first pressure tap is located on the outer wall of the bend in the transition section of the main pipeline and is connected to the positive pressure end of the first differential pressure sensor 1. When fluid flows through the bend, the pressure value borne by the outer wall due to centrifugal force is one of the key parameters of the differential pressure measured by the first differential pressure sensor 1. It can be understood that the outer wall of the bend is the pipe wall on the side of the bend away from the center of the bend.

[0048] The second pressure tap is located on the inner wall of the bend in the transition section of the main pipeline and is connected to the negative pressure end of the first differential pressure sensor 1. When fluid flows through the bend, the inner wall also experiences pressure due to fluid inertia and streamline contraction. This pressure value is another key parameter of the differential pressure measured by the first differential pressure sensor 1. It can be understood that the inner wall of the bend is the pipe wall on the side closer to the center of the bend.

[0049] Here, one first pressure tap is provided, and four second pressure taps and four first differential pressure sensors 1 are provided. The positive pressure ends of the four first differential pressure sensors 1 are all connected to the first pressure tap, and the negative pressure ends of the four first differential pressure sensors 1 are respectively connected to the corresponding second pressure taps to obtain multiple sets of differential pressure data.

[0050] The inlet and outlet pipes of the main pump are connected to the two ends of the second differential pressure sensor 2, which is used to measure the pressure difference between the inlet and outlet of the main pump in real time. It is understood that, according to Bernoulli's equation, the pressure difference across the main pump is directly related to the pump's head and flow rate. The pressure difference can be used to determine whether the main pump is operating normally, such as whether there are faults like cavitation or impeller wear.

[0051] Here, two second differential pressure sensors 2 are set up and connected in parallel to back each other up. If one of them fails, the other can still continue to monitor, avoiding the interruption of the main pump operation status monitoring due to a single point failure of the second differential pressure sensor 2, which meets the redundancy requirements of the nuclear safety system.

[0052] In some possible implementations disclosed in this application, see [link to relevant documentation]. Figure 1 and Figure 2 As shown, the first pressure tap and at least four second pressure taps are located in the same cross section perpendicular to the flow path direction, and the circumferential angle between two adjacent second sampling holes is 14 to 16 degrees.

[0053] In this embodiment, the first pressure tap and at least four second pressure taps are located in the same cross section perpendicular to the flow path in the bend, which can ensure that the data collected by each first differential pressure sensor 1 corresponds to the flow state of the fluid at the same position, avoid the pressure data asynchrony caused by position deviation, and make the differential pressure measurement value more accurately reflect the real fluid dynamic characteristics at the bend.

[0054] The circumferential angle between two adjacent second sampling holes can be 14 degrees, 15 degrees, 16 degrees, etc., and this application does not limit this. In this embodiment, the circumferential angle between two adjacent second sampling holes is preferably 15 degrees. When the circumferential angle is 15 degrees, the pressure dispersion of each second sampling hole is minimized, the data fluctuation range can be controlled within ±0.5%, and the pressure values ​​tend to be consistent. At this angle, the comprehensiveness of the pressure sampling of the inner wall of the bend can be guaranteed, and the influence of fluid disturbance on the differential pressure data can be effectively reduced, thereby improving the accuracy of flow calculation and the reliability of system monitoring.

[0055] In some possible implementations disclosed in this application, see [link to relevant documentation]. Figure 2 and Figure 3 As shown, flow limiting pipe seats are provided at the connection points of the first differential pressure sensor 1 and the first pressure tap, the connection points of the first differential pressure sensor 1 and the second pressure tap, and the connection points of the second differential pressure sensor and the inlet and outlet pipes of the main pump; the diameter of the flow limiting orifice of the flow limiting pipe seat is 9 to 10 mm.

[0056] In this embodiment, by mechanically limiting the flow rate, the fluid flow at the connection point can be controlled to avoid pressure fluctuations during reactor operation. At the same time, it directly limits the maximum leakage flow rate when the connecting pipe ruptures, which significantly reduces the load on downstream pipes or components and can correspondingly lower their safety rating.

[0057] The diameter of the flow-limiting orifice 31 of the flow-limiting tube seat 3 can be 9 mm, 9.5 mm, 10 mm, etc., and this application does not limit it. In this embodiment, the diameter of the flow-limiting orifice 31 of the flow-limiting tube seat 3 is preferably 9.5 mm.

[0058] In some possible implementations disclosed in this application, see [link to relevant documentation]. Figure 1 As shown, isolation valves are installed on the connecting pipes of the first differential pressure sensor 1 and the first pressure tap, the connecting pipes of the first differential pressure sensor 1 and the second pressure tap, and the connecting pipes of the second differential pressure sensor and the inlet and outlet pipes of the main pump.

[0059] In this embodiment, by setting an isolation valve 4, the fluid connection between the sensor and the main pipeline can be cut off without affecting the normal operation of the main circuit, so that maintenance personnel can safely inspect, calibrate or replace the first differential pressure sensor 1, the second differential pressure sensor 2 or the connecting pipeline, avoiding the risk of high temperature and high pressure coolant leakage.

[0060] The isolation valve 4 can be a ball valve, a gate valve, a globe valve, etc., and this application does not limit it.

[0061] Furthermore, to fully illustrate the specific implementation process of this embodiment, a reactor coolant system signal control method is provided, see [link to relevant documentation]. Figure 4 As shown, the method includes:

[0062] Based on the differential pressure measurement values ​​of the four first differential pressure sensors 1 in each main loop, calculate the four flow values ​​corresponding to the four first differential pressure sensors 1 in each main loop;

[0063] The four flow values ​​are compared with the first preset threshold respectively. When at least two flow values ​​are less than the first preset threshold, an insufficient flow signal is output.

[0064] Specifically, when all three main loops output insufficient flow signals, a forced cycle loss signal is triggered; when at least one main loop outputs insufficient flow signals and simultaneously meets the reactor neutron flux lower limit of 10%, a reactor shutdown signal is triggered; when at least two main loops output insufficient flow signals and simultaneously meet the reactor neutron flux lower limit of 30%, a reactor shutdown signal is also triggered.

[0065] In this embodiment, multiple sets of differential pressure data are acquired by multiple first differential pressure sensors 1 in each main loop. Fluid differential pressure at bends can be measured from different points. Through comprehensive calculation of multiple data points, the impact of errors from a single sensor on flow measurement results is reduced, thus more accurately reflecting the actual flow situation of the main loop and providing a reliable data foundation for subsequent signal judgment and safety control. Four flow values ​​are compared with a first preset threshold. When at least two flow values ​​are less than the first preset threshold, a flow insufficiency signal is output. This judgment method does not rely solely on a single flow data point but uses mutual verification from multiple data points, avoiding misjudgments caused by single sensor failure or instantaneous fluid disturbances. It can more reliably identify the true flow insufficiency situation, improve the ability to identify flow anomalies, and ensure timely issuance of warning signals when flow anomalies occur. Specifically, when all three main loops output flow insufficiency signals, a forced loop loss signal is triggered. Simultaneous insufficient flow in all three main loops is a serious situation, potentially indicating a near-complete loss of the reactor coolant system's forced circulation function. Triggering this signal in such cases promptly alerts personnel to take emergency measures, preventing excessively high reactor core temperatures and potential safety accidents due to insufficient coolant circulation. A reactor shutdown signal is triggered when at least one main loop outputs an insufficient flow signal, simultaneously meeting the reactor neutron flux minimum of 10%. The 10% neutron flux minimum signal indicates a low reactor power level; in this situation, even insufficient flow in only one main loop can impact stable reactor operation. Triggering the shutdown signal allows for timely reactor shutdown, preventing further escalation of potential safety risks. A reactor shutdown signal is triggered when at least two main loops output insufficient flow signals, simultaneously meeting the reactor neutron flux minimum of 30%. In cases where two main loops exhibit insufficient flow and the neutron flux is at the 30% minimum, it indicates significant problems with both the reactor's cooling system and power status. Triggering the shutdown signal in this situation is a necessary safety precaution to ensure reactor safety.

[0066] Here, through the aforementioned multiple safety protection logics, this method constructs a relatively complete safety protection system. Under different combinations of abnormal main loop flow conditions and reactor neutron flux states, corresponding signal triggering and shutdown measures are taken. This allows for timely and correct responses based on the severity of the actual situation, effectively reducing the probability of reactor safety accidents, enhancing the safety and reliability of the entire reactor coolant system, and ensuring the safe and stable operation of the reactor.

[0067] In the above embodiments, the first preset threshold is a critical safe flow rate value. When the flow rate is lower than this threshold, it indicates that the flow rate is severely insufficient or the main pump has failed, requiring the activation of the natural circulation cooling or emergency cooling system.

[0068] Furthermore, as a refinement and extension of the specific implementation of the above embodiments, and to fully illustrate the specific implementation process of this embodiment, another reactor coolant system signal control method is provided, see [link to relevant documentation]. Figure 5 As shown, the method includes:

[0069] Based on the differential pressure measurement values ​​of the four first differential pressure sensors 1 in each main loop, calculate the four flow values ​​corresponding to the four first differential pressure sensors 1 in each main loop;

[0070] The four flow values ​​are compared with the second preset threshold respectively. When at least two flow values ​​are greater than the second preset threshold, a sufficient flow signal is output.

[0071] When all three main circuits output sufficient flow signals, and simultaneously meet the normal reactor coolant pressure signal and the normal reactor hot zone temperature signal, the enable signal is triggered.

[0072] In this embodiment, four flow rates are calculated based on the pressure differences measured by the four first differential pressure sensors 1 in each main loop. Cross-validation using multi-point data avoids misjudgments caused by a single sensor failure. Sufficient flow is only determined when at least two flow rates exceed a second preset threshold; this majority voting mechanism further improves monitoring reliability. Even fluctuations in individual sensor data will not trigger erroneous signals. Specifically, triggering the permission signal requires not only sufficient flow in all three main loops but also normal reactor coolant pressure and normal hot zone temperature signals simultaneously. This multi-parameter linkage mechanism avoids system malfunctions caused by misjudgments of a single parameter. For example, if only the flow is sufficient but the pressure is abnormal, such as a coolant leak, the system will not trigger the permission signal, preventing potential safety risks. If the flow and pressure are normal but the hot zone temperature is abnormal, such as localized core overheating, the permission signal can be blocked by the temperature signal, providing timely warning.

[0073] Here, the operation of nuclear reactors must meet the principle of multiple barriers. This method uses multi-parameter coupling judgment to incorporate key parameters such as flow rate, pressure, and temperature into a unified control framework, which meets the requirements of nuclear safety systems for diversity and independence and reduces the probability of accidents caused by the failure of a single parameter.

[0074] Specifically, when the system is in an unsafe state, such as insufficient pressure or abnormal temperature, even if the flow rate is sufficient, the permission signal will not be triggered. This ensures that the reactor only enters the permission state when all key parameters meet the safety thresholds, such as starting the main pump or increasing power, to avoid the overall risk being masked by normal local parameters.

[0075] The permission signal serves as a prerequisite for operations such as reactor startup, power regulation, or system switching. For example, during the unit startup phase, power increase is only permitted when coolant flow, pressure, and temperature are all normal, thus ensuring the safety of the entire startup process.

[0076] In the above embodiment, the second preset threshold is the lower limit of the rated operating flow rate. When the flow rate is higher than this threshold, it indicates that the flow rate is within a safe and controllable range, allowing related operations such as power boosting to be performed, thus avoiding risks caused by misoperation when the flow rate is insufficient.

[0077] Furthermore, as a refinement and extension of the specific implementation of the above embodiments, and to fully illustrate the specific implementation process of this embodiment, another reactor coolant system signal control method is provided, see [link to relevant documentation]. Figure 6 As shown, the method includes:

[0078] The six second differential pressure sensors 2 in the three main circuits are divided into a first group and a second group, each group including three second differential pressure sensors 2 corresponding to the main pumps of the three main circuits respectively;

[0079] When at least two of the second differential pressure sensors 2 in any group output abnormal signals, and the reactor injection signal is met at the same time, the main pump shutdown signal is triggered.

[0080] In this embodiment, the six second differential pressure sensors 2 are divided into two groups, each group corresponding to the main pump second differential pressure sensors 2 of the three main circuits. By using a judgment logic that detects at least two abnormal sensors within a group, false alarms caused by a single sensor failure are avoided. For example, if a sensor in a group outputs an abnormal signal due to a hardware failure, while other sensors are normal, a shutdown signal will not be triggered, effectively reducing the probability of erroneous operation. The main pump shutdown signal is only triggered when the abnormal signal from the second differential pressure sensor 2 and the reactor safety injection signal are simultaneously satisfied. The reactor safety injection signal is used to characterize emergency situations such as severe loss of coolant in the reactor. In this case, combined with the abnormality of the second differential pressure sensor 2, it can be determined that the main pump may no longer be able to maintain normal coolant circulation, such as pump failure or pipe blockage. Shutting down the main pump can prevent the abnormal operation of the main pump from exacerbating system risks, such as damage from idling or insufficient flow leading to core overheating. If only the second differential pressure sensor 2 is abnormal without a reactor safety injection signal, such as an occasional sensor failure during normal operation, the system will not trigger a shutdown, ensuring continuous and stable operation of the reactor under non-emergency conditions and improving system availability.

[0081] Here, the two sets of second differential pressure sensors 2 form independent monitoring channels. Even if one set of sensors or related circuits fails, the other set can still operate normally, ensuring the continuity of monitoring functions. For example, when the first set of sensors fails completely due to a cable fault, the second set can still determine the main pump status through its own logic, maintaining the system's safety monitoring capability. This logic design follows the principle of safety priority. When either set of monitoring meets abnormal conditions and is accompanied by a safety injection signal, it can quickly cut off the main pump power, preventing the escalation of an accident caused by the superposition of coolant system failure and reactor emergency conditions, which conforms to the defense-in-depth principle in nuclear safety design.

[0082] In the above embodiment, the abnormal signal is when the difference between the measured value and the rated value of the second differential pressure sensor 2 exceeds the preset threshold range.

[0083] The preset threshold range is used to quantify the abnormal boundary in order to balance fault sensitivity and operational stability and prevent the main pump from shutting down due to parameter fluctuations.

[0084] Abnormal pressure differentials may indicate malfunctions such as main pump cavitation, impeller wear, or inlet blockage. For example, when the measured pressure differential drops suddenly and is accompanied by an increase in vibration, mechanical damage to the pump body should be investigated first; if the pressure differential fluctuates frequently, there may be a problem of excessive gas content in the coolant.

[0085] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of a preferred embodiment, and the apparatus or process shown in the drawings is not necessarily necessary for implementing this application. Any variations that can be conceived by those skilled in the art should fall within the protection scope of this application.

Claims

1. A reactor coolant system flow monitoring device, wherein the reactor coolant system comprises at least three main loops, characterized in that, Each of the main circuits has a first pressure tapping hole on the outer wall and at least four second pressure tapping holes on the inner wall at the bend of the main pipe transition section. The flow monitoring device includes: At least four first differential pressure sensors, the positive pressure ends of at least four first differential pressure sensors are all connected to the first pressure tapping holes, and the negative pressure ends of at least four first differential pressure sensors are connected to at least four second pressure tapping holes one by one; At least two second differential pressure sensors are connected in parallel, and the two ends of the at least two second differential pressure sensors are respectively connected to the inlet pipe and the outlet pipe of the main pump in the main circuit.

2. The reactor coolant system flow monitoring device according to claim 1, characterized in that, The first pressure tap and at least four second pressure taps are located in the same cross section perpendicular to the flow path direction, and the circumferential angle between two adjacent second sampling holes is 14 to 16 degrees.

3. The reactor coolant system flow monitoring device according to claim 1, characterized in that, A flow limiting pipe seat is provided at the connection between the first differential pressure sensor and the first pressure tap, the connection between the first differential pressure sensor and the second pressure tap, and the connection between the second differential pressure sensor and the inlet pipe and outlet pipe of the main pump; the diameter of the flow limiting hole of the flow limiting pipe seat is 9 to 10 mm.

4. The reactor coolant system flow monitoring device according to claim 1, characterized in that, Isolation valves are installed on the connecting pipes of the first differential pressure sensor and the first pressure tap, the connecting pipes of the first differential pressure sensor and the second pressure tap, and the connecting pipes of the second differential pressure sensor and the inlet and outlet pipes of the main pump.

5. A signal control method for a reactor coolant system, characterized in that, The method, applied to the reactor coolant system flow monitoring device as described in any one of claims 1-4, comprises: Based on the differential pressure measurements of the four first differential pressure sensors in each main loop, calculate the four flow rates corresponding to the four first differential pressure sensors in each main loop; Each of the four flow values ​​is compared with a first preset threshold. When at least two of the flow values ​​are less than the first preset threshold, an insufficient flow signal is output. Specifically, when all three main loops output the insufficient flow signal, a forced cycle loss signal is triggered; when at least one of the main loops outputs the insufficient flow signal and simultaneously meets the reactor neutron flux lower limit of 10%, a reactor shutdown signal is triggered; when at least two of the main loops output the insufficient flow signal and simultaneously meet the reactor neutron flux lower limit of 30%, a reactor shutdown signal is also triggered.

6. The reactor coolant system signal control method according to claim 5, characterized in that, The first preset threshold is the critical safe flow rate value.

7. A signal control method for a reactor coolant system, characterized in that, The method, applied to the reactor coolant system flow monitoring device as described in any one of claims 1-4, comprises: Based on the differential pressure measurements of the four first differential pressure sensors in each main loop, calculate the four flow rates corresponding to the four first differential pressure sensors in each main loop; Each of the four flow rates is compared with a second preset threshold. When at least two of the flow rates are greater than the second preset threshold, a sufficient flow signal is output. When all three main circuits output the sufficient flow signal, and simultaneously meet the normal reactor coolant pressure signal and the normal reactor hot zone temperature signal, the enable signal is triggered.

8. The reactor coolant system signal control method according to claim 7, characterized in that, The second preset threshold is the lower limit of the rated operating flow rate.

9. A signal control method for a reactor coolant system, characterized in that, The method, applied to the reactor coolant system flow monitoring device as described in any one of claims 1-4, comprises: The six second differential pressure sensors in the three main circuits are divided into a first group and a second group, each group including three second differential pressure sensors corresponding to the main pumps of the three main circuits respectively; When at least two of the second differential pressure sensors in any group output abnormal signals, and the reactor injection signal is met at the same time, the main pump shutdown signal is triggered.

10. The reactor coolant system signal control method according to claim 9, characterized in that, The abnormal signal is when the difference between the measured value and the rated value of the second differential pressure sensor exceeds a preset threshold range.

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