KR102578178B1 - Preventive System of reactor trip in case of one RCP trip in Small Modular Reactor - Google Patents

Abstract

OPR1000 and APR1400, Korea's representative nuclear power plants, are composed of four reactor coolant pumps, as shown in Figure 1, and provide sufficient forced circulation flow to the reactor coolant system to properly remove heat generated from the reactor core during normal operation. It plays a role. However, if one RCP stops due to various failures during normal operation, the remaining three RCPs cannot sufficiently supply the reactor coolant flow rate necessary to properly remove the heat generated in the core. Therefore, if one RCP fails, the power plant protection system safely stops the reactor to prevent damage to the core. Then, the stopped RCP is repaired through prompt maintenance and then returns to normal operation. In relation to this, in the case of nuclear power plants operating in Korea, the technology that allows continued operation without stopping the reactor when one RCP fails during 100% full power operation has not yet been applied. In other words, the failure of any RCP during normal operation is directly related to the shutdown of the reactor. However, in the case of small nuclear reactors, most of them are located in islands or remote areas, so when the reactor is stopped unexpectedly, professional maintenance personnel must be dispatched to the site and necessary parts and equipment must be transported to the site. Therefore, compared to large nuclear power plants, repair of broken RCP and reactor It takes a relatively large amount of time and effort to restart. Therefore, if there is no problem with reactor safety, it is necessary to prevent unplanned reactor shutdown due to the failure of one RCP if possible. Since this is directly related to the operation rate of small nuclear reactors, it will be of great help in improving the operation rate if a method is developed to enable continuous operation of the reactor without stopping even in the event of an unexpected shutdown of one RCP. The present invention proposes a method to prevent the unexpected shutdown of one RCP of a small nuclear reactor from causing unnecessary unexpected shutdown of the reactor.

Description

Reactor stop prevention system when one reactor coolant pump of a small nuclear reactor stops {Preventive System of reactor trip in case of one RCP trip in Small Modular Reactor}

The present disclosure relates to a system that allows the reactor to continue to operate without unnecessary sudden stoppage even when one reactor coolant pump of a small nuclear reactor malfunctions.

OPR1000 and APR1400, Korea's representative nuclear power plants, are composed of four reactor coolant pumps (hereinafter RCP), as shown in Figure 1, and are installed in the reactor coolant system (hereinafter RCS) to properly remove heat generated from the reactor core during normal operation. It serves to provide sufficient forced circulation flow.

However, if one reactor coolant pump stops due to various failures during normal operation, the remaining three reactor coolant pumps cannot sufficiently supply the reactor coolant flow rate necessary to properly remove the heat generated in the core.

Therefore, if one of the four reactor coolant pumps fails, the power plant protection system safely stops the reactor to prevent core damage. Then, the broken RCP is repaired through prompt maintenance and normal operation is restored. In relation to this, in the case of nuclear power plants operating in Korea, the technology that allows continued operation without stopping the reactor when one RCP fails during 100% full power operation has not yet been applied. In other words, failure of any RCP during normal operation is directly related to reactor shutdown.

Currently, in the case of large nuclear power plants such as domestic OPR1000 and APR1400, if even one of the four reactor coolant pumps stops unexpectedly, the power plant protection system is designed to stop the reactor to prevent core damage.

In the case of small nuclear reactors of 300 MW or less, they are generally implemented with 2-4 reactor coolant pumps, so if one of the 2-4 reactor coolant pumps stops unexpectedly, the power plant protection system stops the reactor to prevent damage to the core. Small nuclear reactors are generally located in islands or remote areas and are likely to be comprised of a single power grid, so in such cases, an unexpected shutdown of a nuclear reactor can be a serious power system event that could lead to a blackout from the consumer's perspective.

Therefore, there is an urgent need for measures to prevent unnecessary unplanned shutdowns of small nuclear reactors. Therefore, there is an urgent need to develop technology that will enable small reactors to continue operating without stopping even if one of the two to four reactor coolant pumps in normal operation comes to an unexpected stop.

The nuclear reactor shutdown prevention system according to embodiments of the present disclosure is connected to the first nuclear reactor coolant pump and the second nuclear reactor coolant pump, receives the first axial speed value and the first input voltage of the first nuclear reactor coolant pump, and 1 Receives first flow rate information of the nuclear reactor coolant system, and receives a signal in which the first axial speed value is less than the first reference axial speed value and a signal in which the first input voltage is less than the first reference input voltage value through an AND circuit A stop determination unit that outputs a first output signal by inputting the first output signal and the first flow rate information into an AND circuit to output a second output signal. ; and a switching unit that switches the power of the first nuclear reactor coolant pump to the emergency power when the second output signal is true.

If the second output signal is true, the stop determination unit may transmit an unexpected stop prevention signal to at least one of the control rod speed control unit and the turbine load control unit of the control rod drive device control system.

In response to the sudden stop prevention signal, the control rod drive device control system switches emergency power to the first reactor coolant pump, adjusts the speed of the control rod until the reactor output decreases to a preset first level, and controls the turbine. A control command that rapidly reduces the output to a preset second degree can be transmitted to the turbine control system.

The stop determination unit re-receives the second axial velocity value of the first reactor coolant pump, re-receives second flow rate information of the first reactor coolant series, and receives the second axial velocity value and the second flow rate information. Taking this into consideration, it can be determined whether the first reactor coolant pump is normally stopped.

According to the present disclosure, the switching state of the first and second nuclear reactor coolant pumps, the high-speed insertion state of the control rod, the trip status of the first and second nuclear reactor coolant pumps, the turbine control state, and the primary and secondary energy balance states. It may include a human-machine linkage device that displays.

A computer program according to an embodiment of the present invention may be stored in a medium to execute any one of the methods according to an embodiment of the present invention using a computer.

In addition to this, another method for implementing the present invention, another system, and a computer-readable recording medium for recording a computer program for executing the method are further provided.

Other aspects, features and advantages in addition to those described above will become apparent from the following drawings, claims and detailed description of the invention.

Once a nuclear power plant is shut down, it takes a long time to return to normal operation. Even if the cause of the outage is simple or a replacement part is available at the plant site, it may take several days; in other cases, it may take weeks or even months. Moreover, considering the restart approval process and time of the licensing agency, it takes additional time.

Therefore, in the case of small nuclear reactors located in islands or remote areas, unplanned shutdown of nuclear power plants should be prevented whenever possible, unless it threatens the safety of the nuclear power plant.

Therefore, the present invention can prevent unnecessary unexpected shutdown of the reactor due to the unexpected shutdown of one reactor coolant pump, which can greatly contribute to improving the operation rate of small nuclear reactors and prevent economic losses due to failure to generate power due to unexpected shutdown.

According to embodiments of the present disclosure, even in the event of a failure of one RCP of a small nuclear reactor, the reactor does not stop unnecessarily and maintains thermal equilibrium between the primary and secondary sides at a low output lower than the normal output. You can drive continuously.

1 is a diagram of the reactor coolant system of domestic OPR1000 and APR1400 nuclear power plants related to embodiments of the present disclosure.
Figure 2 is an exemplary diagram of a nuclear reactor coolant system of an ocean floating small nuclear reactor related to embodiments of the present disclosure.
3 and 4 are block diagrams and logic algorithms showing a nuclear reactor shutdown prevention method when one RCP is stopped according to embodiments of the present disclosure.
Figure 5 is a logic algorithm for determining whether one of two RCPs is stopped according to embodiments of the present disclosure.
Figure 6 is a diagram of a human-machine linkage device located in the main control room according to embodiments of the present disclosure.

Hereinafter, the configuration and operation of the present invention will be described in detail with reference to embodiments of the present invention shown in the attached drawings.

Since the present invention can be modified in various ways and can have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. The effects and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various forms.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. When describing with reference to the drawings, identical or corresponding components will be assigned the same reference numerals and redundant description thereof will be omitted. .

In this specification, terms such as “learning” and “learning” are not intended to refer to mental operations such as human educational activities, but are terms that refer to performing machine learning through procedural computing. interpret.

In the following embodiments, terms such as first and second are used not in a limiting sense but for the purpose of distinguishing one component from another component.

In the following examples, singular terms include plural terms unless the context clearly dictates otherwise.

In the following embodiments, terms such as include or have mean that the features or components described in the specification exist, and do not exclude in advance the possibility of adding one or more other features or components.

In the drawings, the sizes of components may be exaggerated or reduced for convenience of explanation. For example, the size and thickness of each component shown in the drawings are shown arbitrarily for convenience of explanation, so the present invention is not necessarily limited to what is shown.

In cases where an embodiment can be implemented differently, a specific process sequence may be performed differently from the described sequence. For example, two processes described in succession may be performed substantially at the same time, or may be performed in an order opposite to that in which they are described.

The nuclear reactor shutdown prevention system according to embodiments of the present disclosure includes an RCS flow sensor 130 that measures the flow rate within the RCS, and a switch unit that switches to emergency power when the RCP is not supplied with normal input power due to a failure of the input power unit. (150), a speed sensor unit (140) for measuring the axial speed of the RCP, a speed measuring unit for measuring the axial speed of the RCP, and a determination unit (110) for determining whether one RCP is stopped, switching to emergency power when the RCP input power is lost. It includes an emergency power transfer signal unit that generates a transfer signal to stop the reactor, and an unplanned stop prevention signal unit that generates a reactor unplanned stop prevention signal when one RCP is stopped.

As shown in FIG. 5, the nuclear reactor shutdown prevention system according to embodiments of the present disclosure includes an RCP operation state determination unit that determines the operation state (normal operation or trip) of each RCP while two RCPs are normally operating.

As shown in Figure 6, it consists of a human-machine linkage device in the main control room to inform the operator of various operation information related to preventing unplanned reactor shutdown when one RCP is stopped.

In addition, the connected system includes a power plant protection system (120) that receives RCS flow information as input and generates emergency power transfer and unexpected stop prevention signals, and a control rod speed control unit (211) and turbine load control unit that receive unexpected stop prevention signals. The control rod drive device control system 210, which controls the primary and secondary output through (212), the reactor output control system 160, which controls the reactor output to reduce the deviation between the reactor output and the turbine output, and the control rod drive device. There is a turbine control system 240 that controls the turbine load through a turbine load control unit.

1 is a diagram of a nuclear reactor coolant system of OPR1000 and APR1400 related to embodiments of the present disclosure.

As shown in Figure 1, the two reactor coolant systems each have four RCPs installed in the cold pipe.

Figure 2 shows the reactor coolant system of the BANDI-60s marine floating small nuclear reactor being developed by Korea Electric Power Engineering Co., Ltd., and one canned motor pump type RCP is installed directly attached to the bottom of two steam generators.

3 and 4 are diagrams conceptually explaining an operation method according to embodiments of the present disclosure.

If the RCP is stopped during normal operation, first determine whether only one RCP or both RCPs are stopped. If both RCPs are stopped, the reactor has no choice but to stop due to the low flow rate of the RCS. And after the reactor is stopped, it is operated according to the established emergency operation procedures.

However, if only one RCP is stopped, that RCP is first switched to the emergency power source. And when the transfer is successful, the control rod drive device control system 210 inserts all control rods at high speed (normally at 3 IPM, but at high speeds at 30 IPM) until the reactor output reaches about 50%. IPM: Inch Per Minute, the speed here is an example. The specific speed can be presented only after the final design is completed). At the same time, the turbine control system 240 performs a turbine setback to reduce the turbine output to 50% of the total output and adjusts the primary and secondary outputs to balance the reactor output and turbine output around 50%. Of course, after such large-scale adjustments, additional fine-tuning is necessary to converge to a more stable state. In the case of nuclear reactor output, fine adjustment is performed through PID control by the nuclear reactor output control system 160 to reduce the deviation between the reactor output and turbine output, and the turbine control system 240 performs functions such as turbine runback and turbine load increase inhibit. It is performed through control commands.

The nuclear reactor is maintained in a stable state at 50% output (i.e., 50% reactor output, 50% turbine output under a single RCP operation situation), and when the conditions for recovery to normal operation are met, the output increases to normal operation (100%). % output).

Figure 5 shows an algorithm for determining whether two RCPs are simultaneously stopped.

The axial speed and outlet flow rate of RCP #1 are compared with the corresponding set value (S120, S121), and if both are below the set value, these two signals are combined with “AND” logic (S130). If it is above the set value, it continues until it is below the set value. Speed and flow rate are monitored.

In the case of RCP #2, it is similarly compared with the set value (S122, S123), and if it is below the set value, it is combined with “AND” logic (S131). If it is above the set value, the speed and flow rate are continuously monitored until it falls below the set value. The operation status of RCP #1 and RCP #2 can be broadly divided into three cases. The first is when both RCP #1 and RCP #2 are operating normally (S162), the second is when only one of RCP #1 and RCP #2 is operating normally (S163) and the other is stopped, and the third and final is when RCP #2 is operating normally (S163). This will be the case when both #1 and RCP #2 stop (S161).

Therefore, in order to determine these three cases, the number of all combinations of result values A, B, and C of “AND Gate3”, “OR Gate 1”, and “XOR Gate1” are LOOKUP Tabled to simultaneously check RCP #1 and RCP #2. “ABC=110” indicating stop, “ABC=000” indicating normal operation of RCP #1 and RCP #2, and “ABC=011” indicating that only one of the two RCPs is operating normally and the other is stopped. It is done (S150). The remaining combinations are meaningless and are therefore ignored.

Figure 6 shows a human-machine linkage device located in the main control room to prevent reactor shutdown when one RCP is stopped. First, the top left shows whether the RCP input power is receiving the input power during normal operation or whether the transfer switch is switched and the input power is supplied from the emergency power source. The bottom left displays the control rod withdrawal/insertion command and speed from the control rod drive device control system. The central indicator indicates the stopped or normal operating status of RCP #1 and RCP #2.

And the upper right intuitively shows how much deviation there is between the reactor and turbine output, and the lower right shows which turbine control command is being executed in the turbine control system.

If one RCP is stopped and the reactor coolant cannot be continuously forcibly circulated using the stored energy of the emergency power source, the method presented in this invention specification will not be effective. In other words, when one RCP is stopped, core damage must be prevented by continuing to operate the RCP with emergency power stopped, even while reducing the output of the reactor and turbine by 50%. Of course, if the output of the reactor and turbine is balanced at 50%, then core damage can be prevented with just one RCP, so there is no longer a need for emergency power to supply power to the stopped RCP.

In the case of small nuclear reactors, most of them are located in islands or remote areas, so when the reactor is stopped unexpectedly, professional maintenance personnel must be dispatched to the site and necessary parts and equipment must be transported to the site. Therefore, compared to large nuclear power plants, repair of broken RCPs and reactor maintenance are required. It takes a relatively large amount of time and effort to restart. Therefore, as suggested in the embodiment of the present disclosure, preventing unnecessary unplanned stoppage of the nuclear reactor and lowering the output to continue supplying power even when one RCP fails contributes to improving the economic efficiency of both the power generation business operator and the recipient. Therefore, it is believed that small reactors using this technology will be advantageous in pioneering the small reactor market by gaining a technological advantage over competing reactors that do not.

The device described above may be implemented with hardware components, software components, and/or a combination of hardware components and software components. For example, devices and components described in embodiments may include, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA), etc. , may be implemented using one or more general-purpose or special-purpose computers, such as a programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. Additionally, a processing device may access, store, manipulate, process, and generate data in response to the execution of software. For ease of understanding, a single processing device may be described as being used; however, those skilled in the art will understand that a processing device includes multiple processing elements and/or multiple types of processing elements. It can be seen that it may include. For example, a processing device may include a plurality of processors or one processor and one controller. Additionally, other processing configurations, such as parallel processors, are possible.

Software may include a computer program, code, instructions, or a combination of one or more of these, which may configure a processing unit to operate as desired, or may be processed independently or collectively. You can command the device. Software and/or data may be used on any type of machine, component, physical device, virtual equipment, computer storage medium or device to be interpreted by or to provide instructions or data to a processing device. , or may be permanently or temporarily embodied in a transmitted signal wave. Software may be distributed over networked computer systems and stored or executed in a distributed manner. Software and data may be stored on one or more computer-readable recording media.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc., singly or in combination. Program instructions recorded on the medium may be specially designed and configured for the embodiment or may be known and available to those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floptical disks. -Includes optical media (magneto-optical media) and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. Examples of program instructions include machine language code, such as that produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

As described above, although the embodiments have been described with limited examples and drawings, various modifications and variations can be made by those skilled in the art from the above description. For example, the described techniques are performed in a different order than the described method, and/or components of the described system, structure, device, circuit, etc. are combined or combined in a different form than the described method, or other components are used. Alternatively, appropriate results may be achieved even if substituted or substituted by an equivalent.

Therefore, other implementations, other embodiments, and equivalents of the claims also fall within the scope of the claims described below.

Claims (5)

It is connected to a first nuclear reactor coolant pump and a second nuclear reactor coolant pump, receives a first axial speed value and a first input voltage of the first nuclear reactor coolant pump, and receives first flow rate information of the first nuclear reactor coolant pump. , inputting a signal in which the first axial speed value is less than the first reference axial speed value and a signal in which the first input voltage is less than the first reference input voltage value into an AND circuit to output a first output signal, a stop determination unit that outputs a second output signal by inputting a signal in which the first output signal and the first flow rate information are less than a first reference flow rate value into an AND circuit; and
When the second output signal is true, a switching unit that switches the power of the first reactor coolant pump to emergency power,
The stop determination unit
When the second output signal is true, a nuclear reactor stoppage prevention signal is transmitted to at least one of the control rod speed control unit and the turbine load control unit of the control rod drive device control system. delete According to paragraph 1,
The control rod driving device control system is
In response to the sudden stop prevention signal, emergency power is transferred to the first reactor coolant pump, the speed of the control rod is adjusted until the reactor output decreases to a preset first level, and the output of the turbine is adjusted to a preset second level. A nuclear reactor shutdown prevention system that transmits control commands to rapidly decelerate to the turbine control system. According to paragraph 1,
The stop determination unit
Receiving the second axial speed value of the first nuclear reactor coolant pump, receiving again the second flow rate information of the first nuclear reactor coolant pump, and considering the second axial speed value and the second flow rate information, 1 A nuclear reactor shutdown prevention system that determines whether the reactor coolant pump has stopped normally. According to paragraph 1,
A human displaying the switching status of the first and second reactor coolant pumps, the high-speed insertion status of the control rod, the trip status of the first and second reactor coolant pumps, the turbine control status, and the primary and secondary side energy balance status - A nuclear reactor shutdown prevention system further comprising a machine-to-machine linkage device.

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