Method for determining control rod drop time

Abstract

Embodiments of the present application relate to the technical field of nuclear reactor design, and more specifically, to a method for determining control rod drop time, which is applied to a fast neutron reactor and includes the following steps: obtaining a shutdown signal from the fast neutron reactor and determining the time corresponding to the shutdown signal as a first time; obtaining a drive signal from a drive device, and determining the time corresponding to the drive signal as a second time when the drive signal indicates that a drive parameter of the drive device is lower than a preset parameter threshold; obtaining a rod position measurement signal from a control rod, and determining the time corresponding to the rod position measurement signal as a third time when the rod position measurement signal indicates that the control rod has reached a rod position corresponding to a shutdown depth requirement; and determining the control rod drop time based on the first time, the second time, and the third time. The method provided in the embodiments of the present application determines the control rod drop time based on the obtained first time, the second time, and the third time, without requiring the participation of an operator or operating personnel, and has high measurement efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of nuclear reactor design, and in particular to a method for determining a control rod drop time. Background Art

[0002] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0003] A nuclear reactor is a device that utilizes nuclear energy and includes various regulatory systems to maintain safe operation. If an abnormality is detected that a regulatory system cannot handle, an emergency shutdown can be triggered by deactivating power to the control rod drive units.

[0004] After triggering a scram, the control rod drive mechanism (CRD) is designed to insert the control rods into the reactor core as quickly as possible within the specified timeframe, ensuring that the negative reactivity introduced by the control rods meets the required shutdown depth to ensure reactor safety. However, current methods for determining control rod drop timing are suboptimal, hindering operators from accurately and conveniently determining a rod drop time that matches the operational specifications. Summary of the Invention

[0005] A brief overview of the present application is provided below to provide a basic understanding of certain aspects of the present application. It should be understood that this overview is not an exhaustive overview of the present application. It is not intended to identify key or important portions of the present application, nor is it intended to limit the scope of the present application. Its purpose is simply to present certain concepts in a simplified form as a prelude to the more detailed description that will be discussed later.

[0006] An embodiment of the present application provides a method for determining a control rod drop time, which is applied to a fast neutron reactor. The fast neutron reactor includes a driving device for driving the control rods, comprising the following steps:

[0007] S1, obtaining a shutdown signal of a fast neutron reactor and determining a time corresponding to the shutdown signal as a first time;

[0008] S2. Acquire a driving signal from the driving device, and when the driving signal indicates that a driving parameter of the driving device is lower than a preset parameter threshold, determine a moment corresponding to the driving signal as a second moment;

[0009] S3. Obtaining a rod position measurement signal of a control rod. When the rod position measurement signal indicates that the control rod has reached a rod position that satisfies a trip depth requirement, determining a time corresponding to the rod position measurement signal as a third time.

[0010] S4. Determine a control rod drop time based on the first moment, the second moment, and the third moment.

[0011] The method provided in the embodiments of the present application can determine the control rod drop time based on a first moment corresponding to a shutdown signal, a second moment corresponding to when a driving parameter of a driving device falls below a preset parameter threshold, and a third moment corresponding to when a control rod reaches a rod position corresponding to a shutdown depth requirement. This method does not require the involvement of operators or operating personnel, can ensure the efficiency of rod drop time measurement, and is also conducive to improving the degree of automation in measuring rod drop time.

[0012] These and other advantages of the present application will become more apparent through the following detailed description of the preferred embodiments of the present application in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] To further illustrate the above and other advantages and features of the present application, the following detailed description of specific embodiments of the present application is provided in conjunction with the accompanying drawings. The accompanying drawings, together with the detailed description below, are incorporated into and form a part of this specification. Elements with the same function and structure are denoted by the same reference numerals. It should be understood that these drawings depict only typical examples of the present application and should not be construed as limiting the scope of the present application.

[0014] Figure 1 is a flow chart of a method for determining a control rod drop time according to an embodiment of the present application;

[0015] Figure 2 It is a curve showing the changes of various signals over time obtained by the measuring device according to the embodiment of the present application.

[0016] It should be noted that the drawings are not necessarily drawn to scale, but are merely shown in a schematic manner that does not affect the reader's understanding. DETAILED DESCRIPTION

[0017] Exemplary embodiments of the present application will be described below with reference to the accompanying drawings. For the sake of clarity and conciseness, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the process of developing any such actual implementation in order to achieve the developer's specific goals, such as meeting those constraints related to the system and business, and these constraints may vary depending on the implementation. In addition, it should be understood that although the development work may be very complex and time-consuming, it is a routine task for those skilled in the art who benefit from the content of this application.

[0018] It is also necessary to explain here that, in order to avoid obscuring the present application due to unnecessary details, the accompanying drawings only show the device structure and / or processing steps that are closely related to the solution according to the present application, while other details that are not closely related to the present application are omitted.

[0019] It should be noted that, unless otherwise defined, the technical or scientific terms used in this application should have the common meanings understood by persons having ordinary skills in the field to which this application belongs.

[0020] In the description of the embodiments of the present application, “multiple” means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0021] The inventors of this application discovered that because the structure of the control rod drive system for a fast neutron reactor differs significantly from that of control rod drive systems for other types of reactors (e.g., pressurized water reactors), it is not possible to measure the rod drop time using methods known in the related art. For example, the rod drop time is determined by measuring and processing the induced voltage of the rod position measurement coil of the control rod drive system. Furthermore, the rod drop time measurement methods known in the related art require the participation of operators and operational personnel in calculations, resulting in low measurement efficiency and accuracy.

[0022] In response to the above technical problems, an embodiment of the present application provides a method for determining the time of control rod drop, which is applied to a fast neutron reactor. A fast neutron reactor may include a driving device for driving the control rod. Figure 1 As shown, the method may include the following steps S1 to S4.

[0023] S1. Acquire a shutdown signal of a fast neutron reactor and determine a time corresponding to the shutdown signal as a first time.

[0024] S2. Acquire a driving signal from the driving device. When the driving signal indicates that a driving parameter of the driving device is lower than a preset parameter threshold, determine a moment corresponding to the driving signal as a second moment.

[0025] S3. Obtain a rod position measurement signal of the control rod. When the rod position measurement signal indicates that the control rod has reached a rod position corresponding to a trip depth requirement, determine a time corresponding to the rod position measurement signal as a third time.

[0026] S4. Determine a control rod drop time based on the first moment, the second moment, and the third moment.

[0027] The method provided in the embodiments of the present application can determine the control rod drop time based on a first moment corresponding to a shutdown signal, a second moment corresponding to when a driving parameter of a driving device falls below a preset parameter threshold, and a third moment corresponding to when a control rod reaches a rod position corresponding to a shutdown depth requirement. This method does not require the involvement of operators or operating personnel, can ensure the efficiency of rod drop time measurement, and is also conducive to improving the degree of automation in measuring rod drop time.

[0028] In some embodiments, a fast neutron reactor may include a reactor protection system, a rod control, and a rod position indication system. The reactor protection system may include a shutdown circuit breaker. The shutdown circuit breaker may be used to disconnect the power supply to the control rod drive mechanism, thereby achieving a safe shutdown of the fast neutron reactor. The rod control and rod position indication system may include a control rod drive mechanism and a measuring device. The control rod drive mechanism may be used to control the drive mechanism, thereby raising, lowering, and holding the control rods. The measuring device may be used to obtain control rod position signals, including but not limited to the drive signal and rod position measurement signal in the embodiments of this application.

[0029] In some embodiments, in step S1, a trip signal from a trip circuit breaker can be introduced into a measuring device via hard wiring, so that the measuring device can acquire the trip signal. The trip signal can be a trip signal from the trip circuit breaker. When the measuring device acquires the trip signal, the moment the trip signal is acquired can be recorded as a first moment t0.

[0030] In some embodiments, in step S2, the drive signal of the drive device can be introduced into the measuring device via hard wiring, so that the measuring device can obtain the drive signal. When the drive signal indicates that the drive parameter of the drive device is lower than a preset parameter threshold, the measuring device can determine the time corresponding to the current drive signal as the second time t1. The preset parameter threshold can be set based on experience.

[0031] In some embodiments, the fast neutron reactor may further include a rod position measurement device for measuring the position of control rods. When a rod position measurement signal indicates that the control rods have reached a rod position that satisfies a shutdown depth requirement, the measurement device may determine the time corresponding to the current rod position measurement signal as a third time t2.

[0032] In some embodiments, the rod position measurement device may include an angle sensor. The angle sensor is used to detect the continuous operating position of the control rod and convert the linear motion of the control rod drive assembly into an angle signal via a transmission device. In step S3, the angle signal can be used as the rod position measurement signal.

[0033] In some embodiments, the rod position measurement device may include an inductive sensor. The inductive sensor is used to detect the discrete operating positions of the control rod to obtain a control rod position signal. In step S3, the position signal can be used as the rod position measurement signal.

[0034] In the embodiment of the present application, the first moment, the second moment, and the third moment are measured by a measuring device, and the control rod drop time is then determined, which can improve the measurement accuracy of the control rod drop time.

[0035] In some embodiments, after step S4, the method provided by the embodiments of the present application may further include: determining a rod drop curve for the control rod based on the shutdown signal and the first moment obtained in step S1, the drive signal and the second moment obtained in step S2, the rod position measurement signal and the third moment obtained in step S3, and the rod drop time determined in step S4.

[0036] In some embodiments, as Figure 2 As shown, the method provided in the embodiment of the present application can also be used to obtain a control rod drop curve, that is, a curve of multiple signals changing with time. This curve can assist in troubleshooting problems when the rod drop time requirement is not met during subsequent operation.

[0037] In some embodiments, step S4 may include: S41, determining a driving delay time of the driving device based on the first moment and the second moment; S42, determining a falling time of the control rod based on the second moment and the third moment; S43, determining a rod dropping time based on the driving delay time and the falling time.

[0038] The method provided in the embodiments of the present application can determine the control rod drop time based on the drive delay time and the drop time. This not only reduces the error in the determined rod drop time but also eliminates the need for operators and operating personnel to perform manual calculations, thereby further improving the efficiency of determining the control rod drop time.

[0039] In some embodiments, in step S41 , the driving delay time T1 of the driving device may be determined by calculating the difference between the first time t0 and the second time t1 , ie, T1 = t1 − t0 .

[0040] In some embodiments, in step S42, the falling time T2 of the control rod can be determined by calculating the difference between the second time t1 and the third time t2, that is, T2 = t2 - t1.

[0041] In some embodiments, in step S43, the rod drop time T can be determined by calculating the sum of the driving delay time T1 and the drop time T2. 总 , that is, T 总 =T1+T2.

[0042] In this embodiment, by separately determining the drive delay time T1 of the drive mechanism and the control rod drop time T2, it is possible to determine whether each time period meets the corresponding indicator requirements, thereby ensuring the accuracy of the rod drop time determined based on the drive delay time T1 and the drop time T2. For example, the drive delay time T1 of the drive mechanism satisfies T1 < 100ms; for devices whose drive mechanism includes an electromagnetic clutch, the control rod drop time T2 satisfies T2 < 1.4s; and for devices whose drive mechanism includes a motor, the control rod drop time T2 satisfies T2 < 5.9s.

[0043] In some embodiments, the driving device may include a motor, and step S2 may include: S21, obtaining a current signal of the motor; S22, converting the current signal into a first standard signal, wherein the driving signal may include the first standard signal; S23, when the first standard signal indicates that the current of the motor is lower than a preset current threshold, determining the moment corresponding to the first standard signal as the second moment, wherein the preset parameter threshold includes a preset current threshold.

[0044] The method provided in the embodiments of the present application converts the current signal of the motor into a first standard signal, and then when the first standard signal indicates that the current of the motor is lower than a preset current threshold, determines the moment corresponding to the first standard signal as the second moment. This can ensure higher reliability while ensuring a faster current signal transmission speed, which is beneficial to ensuring the reliability of the rod drop time finally obtained.

[0045] In some embodiments, the motor of the drive device can be controlled by current closure. The drive device can include a current sensor for detecting the current of the motor winding to obtain a current signal. Exemplarily, the current sensor can be a Hall effect sensor.

[0046] In some embodiments, the output of the current sensor is a voltage signal proportional to its driving current. Converting this voltage signal to a first standard signal can make the signal more resistant to interference and facilitate long-distance signal transmission. For example, the first standard signal can be a standard current signal of 4-20mA.

[0047] In some embodiments, the preset current threshold may be the current magnitude corresponding to when the motor can maintain the torque not lower than the load requirement value. That is, the second moment t1 is the moment when the motor current drops to the corresponding holding torque lower than the load requirement value.

[0048] In some embodiments, a current signal corresponding to the current flowing through the motor can be introduced into a measuring device to obtain the current signal, which is more efficient and accurate.

[0049] In some embodiments, the driving device may include an electromagnetic driving component, and step S2 may include: S24, obtaining an electromagnetic driving signal of the electromagnetic driving component; S25, converting the electromagnetic driving signal into a second standard signal, wherein the driving signal may include a second standard signal; S26, when the second standard signal indicates that the electromagnetic driving parameter of the electromagnetic driving component is lower than a preset parameter threshold, determining the moment corresponding to the second standard signal as the third moment.

[0050] The method provided in the embodiments of the present application converts the electromagnetic drive signal of the electromagnetic drive component into a second standard signal, and then determines the third moment when the second standard signal indicates that the electromagnetic drive parameter of the electromagnetic drive component is lower than the preset parameter threshold. This can ensure a faster electromagnetic drive signal transmission speed while having higher reliability, which is beneficial to ensuring the reliability of the rod drop time finally obtained.

[0051] In some embodiments, the electromagnetic drive member may be an electromagnetic clutch.

[0052] In some embodiments, the preset parameter threshold may be a parameter value corresponding to when the electromagnetic clutch can maintain the torque not less than the load requirement value. In other words, the third moment t2 is the moment when the operating parameter of the electromagnetic clutch drops to a corresponding holding torque less than the load requirement value.

[0053] In some embodiments, the electromagnetic driving signal may include a voltage signal. Step S24 may include: measuring the voltage across the electromagnetic driving component to obtain the voltage signal of the electromagnetic driving component, which is highly efficient and accurate.

[0054] In some embodiments, the working mode of the electromagnetic clutch may include a constant current working mode and a constant pressure working mode. When the electromagnetic clutch is in the constant pressure working mode, the electromagnetic driving signal may include a voltage signal.

[0055] In some embodiments, the voltage across the electromagnetic driving component can be calculated based on the design of the electromagnetic driving component and the driving circuit of the driving device to obtain the voltage signal of the electromagnetic driving component.

[0056] In some embodiments, when the electromagnetic clutch is in the constant current working mode, the electromagnetic driving signal may include a current signal of the electromagnetic driving member, and the current signal may correspond to the loop current when the electromagnetic clutch is in the constant current working mode.

[0057] In some embodiments, measuring the voltage across the electromagnetic driver may include: connecting a resistor of a predetermined resistance in parallel across the electromagnetic driver; measuring the current flowing through the resistor to obtain a resistor current; and determining the voltage signal of the electromagnetic driver based on the resistor current and the predetermined resistance, with high calculation accuracy and efficiency.

[0058] In some embodiments, before step S1, the method provided in the embodiments of the present application may further include: lifting one / more compensating rod / adjusting rod driving devices or one / more safety rod driving devices to any position of the stroke, manually triggering the shutdown rod drop, so as to subsequently measure the control rod drop time. This method can be used to regularly measure the control rod drop time, which is beneficial to ensuring the safety of fast neutron reactors.

[0059] In some embodiments, after step S4, the method provided by the embodiments of the present application may further include: outputting an alarm signal when the rod drop time is greater than a rod drop time threshold.

[0060] The embodiments of the present application can timely alert operators and operating personnel by outputting alarm signals, which is beneficial to ensuring the safe operation of the fast neutron reactor.

[0061] In some embodiments, a fast neutron reactor may have multiple shutdown devices. The methods provided in the embodiments of this application can be used to determine the control rod drop timing for each shutdown device. For ease of description and understanding, the following embodiments utilize an example of a fast neutron reactor having two shutdown devices, where the first shutdown device's drive device includes a motor, and the second shutdown device's drive device includes an electromagnetic clutch.

[0062] Example 1

[0063] When the fast neutron reactor is in normal operation and the protection parameter exceeds the limit and triggers a protective shutdown, the first moment t0 when the shutdown circuit breaker is opened can be automatically collected and recorded, and the second moment t1 when the current of the motor drops to the corresponding holding torque lower than the load demand value and the fourth moment t2 when the excitation current of the electromagnetic clutch of the control rod drive device drops to the corresponding holding torque lower than the load demand value can be calculated. 1' , the third time t2 when the continuous rod positions of the control rod drive device of the first shutdown device descend to the position corresponding to the shutdown depth, and the fifth time t5 when the continuous rod positions of the control rod drive device of the second shutdown device descend to the position corresponding to the shutdown depth. 2' The control rod drop time of the first shutdown device can be determined based on the first time t0, the second time t1, and the third time t2. The control rod drop time of the second shutdown device can be determined based on the first time t0, the fourth time t1, and the fifth time t2.

[0064] Example 2

[0065] When a fast neutron reactor is in cold shutdown condition, a periodic test of measuring the control rod drop time is required.

[0066] For the first shutdown device, one or more compensating rod / regulating rod drive devices are raised to any position within their travel range, and the shutdown rod drop is manually triggered. The first moment t0 when the shutdown circuit breaker opens, the second moment t1 when the motor current drops to a corresponding holding torque lower than the load requirement, and the third moment t2 when the continuous rod positions of the control rod drive device drop to a position corresponding to the shutdown depth can then be automatically recorded. The control rod drop time of the first shutdown device is tested one by one or in groups to obtain a rod drop curve.

[0067] For the second set of shutdown device, one or more safety rod driving devices can be lifted to any position of the travel, and the shutdown rod drop can be manually triggered to automatically record the sixth moment t when the shutdown circuit breaker is opened. 0' Calculate the seventh moment t when the excitation current of the electromagnetic clutch of the control rod drive device drops to the corresponding holding torque lower than the load demand value 1' The eighth moment t when the continuous rod position of the control rod drive device drops to the specified value 2' , complete the control rod drop time test of the second set of shutdown device one by one / in groups, and obtain the rod drop curve.

[0068] In some embodiments, the rod drop time determination method provided in the embodiments of the present application can be used to automatically measure the rod drop time of the control rod drive device of a fast neutron reactor, and the measurement accuracy can be less than 0.01s. When the rod drop time of the first set of shutdown devices and the second set of shutdown devices exceeds the corresponding rod drop time threshold, an alarm signal will be given.

[0069] Regarding the embodiments of the present application, it should also be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other to obtain new embodiments.

[0070] The above description is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. The protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for determining control rod drop time, applied to a fast neutron reactor, wherein the fast neutron reactor includes a drive device for driving the control rods, characterized in that: The following steps are involved: S1. Acquire a shutdown signal of the fast neutron reactor and determine a time corresponding to the shutdown signal as a first time; S2. Acquire a driving signal from the driving device, and when the driving signal indicates that a driving parameter of the driving device is lower than a preset parameter threshold, determine a moment corresponding to the driving signal as a second moment; S3. Acquire a rod position measurement signal of the control rod, and when the rod position measurement signal indicates that the control rod has reached a rod position corresponding to a trip depth requirement, determine a time corresponding to the rod position measurement signal as a third time; S4. Determining a control rod drop time according to the first moment, the second moment, and the third moment; The driving device includes a motor, and the step S2 includes: S21, obtaining a current signal of the motor; S22. Convert the current signal into a first standard signal, wherein the drive signal includes the first standard signal; S23. When the first standard signal indicates that the current of the motor is lower than a preset current threshold, determine the moment corresponding to the first standard signal as the second moment, wherein the preset parameter threshold includes the preset current threshold; The driving device includes an electromagnetic driving member, and the step S2 includes: S24, obtaining an electromagnetic driving signal of the electromagnetic driving component; S25, converting the electromagnetic driving signal into a second standard signal, wherein the driving signal includes the second standard signal; S26. When the second standard signal indicates that the electromagnetic driving parameter of the electromagnetic driving component is lower than the preset parameter threshold, determine the moment corresponding to the second standard signal as the third moment.

2. The method according to claim 1, characterized in that The driving device includes an electromagnetic driving member, and the step S2 includes: S24, obtaining an electromagnetic driving signal of the electromagnetic driving component; S25, converting the electromagnetic driving signal into a second standard signal, wherein the driving signal includes the second standard signal; S26. When the second standard signal indicates that the electromagnetic driving parameter of the electromagnetic driving component is lower than the preset parameter threshold, determine the moment corresponding to the second standard signal as the third moment.

3. The method according to claim 2, characterized in that The electromagnetic drive signal includes a voltage signal, and the step S24 includes: The voltage across the electromagnetic driving component is measured to obtain a voltage signal of the electromagnetic driving component.

4. The method according to claim 3, characterized in that The measuring of the voltage across the electromagnetic driving component includes: Connecting resistors of predetermined resistance in parallel at both ends of the electromagnetic driving member; measuring the current flowing through the resistor to obtain the resistance current; A voltage signal of the electromagnetic driving component is determined according to the resistance current and the predetermined resistance value.

5. The method according to any one of claims 1 to 4, characterized in that Before the step S1, the method further includes: Lift one or more compensation rod / adjustment rod drive devices or one or more safety rod drive devices to any position in the travel range and manually trigger the stack stop and rod drop.

6. The method according to any one of claims 1 to 4, characterized in that After the step S4, the method further includes: When the rod-drop time is greater than the rod-drop time threshold, an alarm signal is output.

7. The method according to any one of claims 1 to 4, characterized in that After the step S4, the method further includes: A rod drop curve for the control rod is determined based on the shutdown signal and the first time obtained in step S1, the drive signal and the second time obtained in step S2, the rod position measurement signal and the third time obtained in step S3, and the rod drop time determined in step S4.

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