Accident mitigation responding method in case of design extension condition accident

Abstract

An accident mitigation responding method for an accident mitigation apparatus in case of a design extension condition accident of a nuclear power plant, according to an aspect of the present invention, is a strategy for coping with station blackout caused by a natural disaster exceeding a design standard. In order to secure accessibility of a mobile power generation facility moving along a moving path on land to the nuclear power plant, a helicopter or a transportation drone is preliminarily used to transport a large capacity electric storage device and connect same to a 125 VDC safe busbar connecting apparatus provided on a roof of a reactor auxiliary building, thereby supplying essential power.

Description

Accident mitigation response method in case of design expansion condition accident

[0001] The present invention relates to a technology for mitigating accidents in case of design extension condition accidents in nuclear power plants, and more specifically, to a technology for mitigating a nuclear power plant complete loss of power accident among design extension condition accident mitigation strategies by utilizing off-site resources.

[0002] Nuclear power plants generate electricity by utilizing the thermal energy released by nuclear fission. Nuclear power plants utilize the energy released during nuclear fission to generate large amounts of electricity. Nuclear power plants generate enormous amounts of energy using only small amounts of uranium or plutonium, offering the advantages of relatively low fuel costs and minimizing greenhouse gas emissions. However, nuclear power plants always carry the risk of disaster. Furthermore, if a disaster occurs, the consequences can be devastating and long-lasting. Therefore, the operation and management of nuclear power plants require methods to minimize these drawbacks and a robust system to manage and monitor these risks.

[0003] The status of a nuclear power plant is broadly divided into operating conditions and accident conditions. Accident conditions are divided into design basis accidents (DBA) and design extension conditions (DEC). Design basis accidents are accidents that are not expected to occur during the life of a nuclear power plant but must be considered when designing reactor facilities to comply with the design basis. In other words, they serve as the design basis for the power plant's systems, equipment, and structures. These accidents include increased heat removal by secondary systems and reduced reactor coolant flow rates. Design extension conditions (DEC) are accidents that exceed the design basis conditions and include severe accidents that cause serious core damage and multiple failure accidents. Multiple failure accidents include anticipated transients without scram, station blackouts (SBO), and loss of total feedwater.

[0004] Strategies are in place to predict potential accidents at nuclear power plants and mitigate their impacts should they occur. Existing design extension condition (DEC) accident mitigation strategies include using 1 MW mobile generators and 3.2 MW mobile generators to supply essential power in the event of a complete loss of power (SBO) accident. These mobile generators may not be able to arrive within the timeframe required for power supply due to reduced accessibility to the power plant caused by natural disasters such as earthquakes or tsunamis, preventing them from reaching the plant within the timeframe required by the plant's storage battery capacity.

[0005] The purpose of the present invention is to provide an accident mitigation strategy that enables transport of large-capacity batteries without being affected by road conditions in the event of a complete loss of power (SBO) accident at a nuclear power plant.

[0006] According to one aspect of the present invention, a method for mitigating an accident in response to a design extension condition (DEC) accident of a nuclear power plant includes the steps of detecting a station black out (SBO) accident among the design extension condition (DEC) accidents, the step of requesting the movement of a mobile power generation facility for supplying AC power, which is on standby in an integrated storage facility or a mobile facility storage facility, to a nuclear power plant, the step of requesting preparation for the transport of a large-capacity electric storage device stored in the integrated storage facility or the mobile facility storage facility, the step of instructing a helicopter or a transport drone to transport the large-capacity electric storage device to the rooftop of a reactor auxiliary building, and the step of requesting the connection of the large-capacity electric storage device transported to the rooftop of the reactor auxiliary building to a 125 VDC safety bus terminal.

[0007] At this time, a 125 VDC safety bus terminal is installed on the roof of the reactor auxiliary building.

[0008] When a large-capacity electric storage device is transported by helicopter, a large-capacity electric storage device having a capacity of 15,000 Ah or more can be used.

[0009] An accident mitigation response method for a design extended condition (DEC) accident of a nuclear power plant according to an additional aspect of the present invention may further include a step of calculating the required power supply time from the usage of a large-capacity electrical storage device connected to a 125 VDC safety bus terminal, and a step of additionally requesting transportation of a large-capacity electrical storage device stored in an integrated storage facility or a mobile facility storage facility if the calculated required power supply time is less than the arrival time of the mobile power generation facility at the nuclear power plant.

[0010] According to another aspect of the present invention, a method for mitigating an accident in response to a design extended condition (DEC) accident of a nuclear power plant may further include a step of requesting a return of a helicopter or a transport drone when the mobile power generation facility supplies essential power through a 125 VDC safety bus before the helicopter or transport drone transports a large-capacity electrical storage device to the roof of a nuclear reactor auxiliary building.

[0011] According to the present invention, an accident mitigation strategy can be provided that enables transport of large-capacity batteries without being affected by road conditions in the event of a complete loss of power (SBO) at a nuclear power plant.

[0012] Figure 1 is a procedure diagram of an accident mitigation response method in case of a design expansion condition accident according to one aspect of the present invention.

[0013] FIG. 2 is a flowchart of an accident mitigation response method in the event of a design expansion condition accident including an additional transportation request of a large-capacity electric storage device according to an additional aspect of the present invention.

[0014] FIG. 3 is a flowchart of an accident mitigation response method in the event of a design extension condition accident including a return request during transportation of a large-capacity electric storage device according to an additional aspect of the present invention.

[0015] The aforementioned and additional aspects are concretized through embodiments described with reference to the attached drawings. It is understood that various combinations of components of each embodiment are possible within the embodiment, unless otherwise stated or inconsistent with each other. Each block of the block diagram may in some cases represent a physical component, but in other cases may be a logical representation of a portion of the function of a single physical component or a function spanning multiple physical components. Sometimes, the entity of a block or a portion thereof may be a set of program instructions. These blocks may be implemented in whole or in part by hardware, software, or a combination thereof.

[0016]

[0017] An accident mitigation response method for a design extension condition (DEC) accident of a nuclear power plant according to one aspect of the present invention is a method performed in an accident mitigation device, and includes a step of detecting a nuclear power plant complete loss of power accident, a step of requesting movement of a mobile power generation facility, a step of requesting preparation for transport of a large-capacity electric storage device, a step of instructing transport of a large-capacity electric storage device, and a step of requesting connection of a large-capacity electric storage device as an accident mitigation strategy for a design extension condition (DEC) accident.

[0018] An incident mitigation device is a computing device that includes one or more processors and memory that stores program instructions executable by the processors. In addition to hardware, the device includes software concepts to implement response measures according to an incident mitigation strategy. The incident mitigation device may be a computer device that, in addition to the processor and memory, further includes a GPU (Graphics Processor Unit), storage device, network device, display, input device, etc. The processor is a processor that executes program instructions, and the memory is connected to the processor and stores program instructions executable by the processor, data to be used by the processor for calculations, and data processed by the processor.

[0019] The accident mitigation device is installed in at least one of the main control room, computer room, and emergency technical support room, and is connected to the main control room so that it can receive information on the status of the nuclear power plant from the main control room.

[0020] In order to apply the accident mitigation response method of the present invention, a 125 VDC safety bus terminal must be installed on the roof of the reactor auxiliary building.

[0021] A complete loss of power at a nuclear power plant is defined as an accident in which not only the power from the power plant is lost but also the emergency alternating current power from the emergency diesel generator is lost.

[0022] The Station Blackout (SBO) accident detection step analyzes information about the nuclear power plant status received by the accident mitigation device (S1000) to detect a Station Blackout (SBO) accident among design extended condition (DEC) accidents. Since the accident mitigation device may not normally receive this information due to a nuclear power plant accident, an operator can input the occurrence of a Station Blackout (SBO) accident through an interface such as a console connected to the accident mitigation device. The accident mitigation device can detect this input and detect the Station Blackout (SBO).

[0023] The mobile power generation facility relocation request step is the step where the mobile power generation facility, which has been on standby in the integrated storage facility or mobile equipment storage facility, requests the nuclear power plant to relocate the mobile power generation facility to the integrated storage facility or mobile equipment storage facility to supply AC power while the accident mitigation device detects a complete loss of nuclear power and supplies power to the reactor control and protection system connected to the 125 VDC safety bus through the existing installed storage battery (typically for 4 to 8 hours) (S1010). This request may be made by sending a message to the system managing the integrated storage facility or mobile equipment storage facility. However, this is not limited to this, and any method may be used without restriction as long as the manager managing the integrated storage facility or mobile equipment storage facility can recognize the request.

[0024] The mobile power generation facility can be a 1 MW mobile generator or a 3.2 MW mobile generator.

[0025] The 1 MW mobile generator will power critical loads to ensure plant safety within eight hours of a complete AC power failure and will also power equipment required to maintain the natural circulation of the reactor coolant to prevent core damage. The 1 MW mobile generator will supply 4.16 kV / 3-phase / 60 Hz power. Additionally, the 1 MW mobile generator can utilize fuel from the emergency diesel generator or receive fuel from the fuel oil transfer and storage facility to continuously power critical loads.

[0026] The 3.2 MW mobile generator will power critical loads for plant safety within 72 hours of a complete AC power loss and will also power equipment required to maintain the natural circulation of the reactor coolant to prevent core damage. The 3.2 MW mobile generator will supply 4.16 kV / 3-phase / 60 Hz power. Additionally, the 3.2 MW mobile generator can utilize fuel from the emergency diesel generator or receive fuel from the fuel oil transfer and storage facility to continuously power critical loads.

[0027] Mobile power generation facilities are transported along a route from an integrated storage facility or mobile facility storage facility in an isolated area. Therefore, they may not arrive at the nuclear power plant in a timely manner due to debris from typhoons, strong winds, tornadoes, or other factors exceeding design standards, or road damage caused by earthquakes or tsunamis. To address these situations, it is necessary to transport large-capacity energy storage systems via routes other than land.

[0028] The request for transport preparation for a large-capacity electric storage device is the step where the accident mitigation device requests transport preparation for a large-capacity electric storage device stored in an integrated storage facility or mobile equipment storage facility (S1020). This request can also be made by sending a message to the system managing the integrated storage facility or mobile equipment storage facility. However, this is not limited to this, and any method can be used without restriction as long as the manager managing the integrated storage facility or mobile equipment storage facility can recognize the request. Upon recognizing the request, the manager of the integrated storage facility or mobile equipment storage facility prepares for air transport of the large-capacity electric storage device. In other words, the manager loads the large-capacity electric storage device onto a helicopter or transport drone.

[0029] The large-capacity electric storage device transport instruction step is where the accident mitigation device instructs a helicopter or transport drone to transport the large-capacity electric storage device to the rooftop of the reactor auxiliary building (S1030). The helicopter or transport drone transports the large-capacity electric storage device through the air, ensuring it is not affected by obstacles on the ground route, such as those caused by natural disasters. Preferably, the helicopter or transport drone is an unmanned helicopter or drone capable of autonomous flight, but this is not a limitation.

[0030] When transporting large-capacity electric storage devices by helicopter, the devices can have a capacity of 15,000 Ah or more. Since large-capacity electric storage devices weigh approximately 120 kg per 1,000 Ah of capacity, assuming a helicopter transport weight of 2 tons, batteries with a capacity of 15,000 Ah can be transported.

[0031] In the case of a nuclear power plant of the OPR1000 type, essential power supply is possible for 4 hours with a capacity of 2800 Ah, so if a capacity of 15000 Ah is used, essential power supply is possible for approximately 20 hours.

[0032] The step of requesting connection of a large-capacity electrical storage device is the step where the accident mitigation device requests connection of a large-capacity electrical storage device transported to the roof of a reactor auxiliary building, such as the main control room, computer room, or emergency technical support room, to a 125 VDC safety bus terminal (S1040).

[0033] According to an aspect of the invention, a 125 VDC safety bus terminal installed on the roof of a nuclear reactor auxiliary building can be directly connected to a large-capacity electrical storage device by a landing of a transport drone, and at this time, the large-capacity electrical storage device connection request step is a step in which an accident mitigation device transmits a control signal to control the supply of power from the large-capacity electrical storage device to the 125 VDC safety bus terminal.

[0034] An accident mitigation response method for responding to a design extended condition (DEC) accident of a nuclear power plant according to an additional aspect of the present invention may further include a step of calculating the supply availability time and a step of requesting additional transportation.

[0035] The purpose of transporting large-capacity electricity storage devices via helicopters or transport drones is to extend the time it takes for mobile power generation facilities to reach nuclear power plants when obstacles or other problems along the land route make it difficult for the facilities to reach the nuclear power plant. However, the time that can be extended with large-capacity electricity storage devices is also limited, so additional transportation may be necessary depending on the situation.

[0036] The power supply availability calculation step (S1050) involves the accident mitigation device calculating the required power supply availability time based on the current usage of the large-capacity power storage device connected to the 125 VDC safety bus terminal. The accident mitigation device can estimate the time available for supplying the required power based on the current remaining capacity of the large-capacity power storage device.

[0037] The additional transport request step is the step where, if the calculated essential power supply availability time of the accident mitigation device is shorter than the arrival time of the mobile power generation facility at the nuclear power plant, additional transport of the large-capacity electric storage device stored in the integrated storage facility or mobile facility storage facility is requested (S1060). This request can also be made by sending a message to the system managing the integrated storage facility or mobile facility storage facility. However, this is not limited to this, and any method can be used without restriction as long as the manager managing the integrated storage facility or mobile facility storage facility can recognize the request. Upon recognizing the request, the manager of the integrated storage facility or mobile facility storage facility prepares for air transport of the large-capacity electric storage device. That is, the manager loads the large-capacity electric storage device onto a helicopter or transport drone and transports the large-capacity electric storage device to the rooftop of the reactor auxiliary building via the helicopter or transport drone.

[0038] According to another aspect of the present invention, a method for mitigating an accident in response to a design extended condition (DEC) accident of a nuclear power plant may further include a step (S1070) of requesting a return of a helicopter or a transport drone when the mobile power generation facility supplies essential power through a 125 VDC safety bus before the helicopter or transport drone transports a large-capacity electrical storage device to the rooftop of a nuclear reactor auxiliary building.

[0039] Transport of large-capacity electric storage devices via helicopters or transport drones is to prepare for problems such as obstacles on the land route, but if the land route is free of problems or allows for quick response, and the mobile power generation facility can approach the nuclear power plant in a timely manner, the helicopter or transport drone transporting the large-capacity electric storage device can be returned as needed.

[0040]

[0041] While the present invention has been described above with reference to the accompanying drawings and examples, it is not limited thereto and should be construed to encompass various modifications that would be readily apparent to those skilled in the art. The scope of the patent claims is intended to encompass such modifications.

Claims

1. In the accident mitigation response method in response to the design extended condition (DEC) accident of a nuclear power plant, Steps to detect a Station Black Out (SBO) accident during the Design Extended Conditions (DEC) accident; A step for requesting the movement of a mobile power generation facility for supplying AC power, which is on standby in an integrated storage facility or mobile facility storage facility, to a nuclear power plant; A step for requesting preparation for transport of large-capacity electrical storage devices stored in an integrated storage facility or mobile storage facility; A step of instructing a helicopter or transport drone to transport a large-capacity electric storage device to the roof of a nuclear reactor auxiliary building; and A step of requesting connection of a large-capacity electrical storage device transported to the roof of a reactor auxiliary building to a 125 VDC safety bus terminal; Including, but not limited to, An accident mitigation response method of an accident mitigation device in the event of an accident under design extension conditions of a nuclear power plant, characterized in that a 125 VDC safety bus terminal is installed on the roof of the above reactor auxiliary building.

2. In paragraph 1, A method for mitigating accidents in the event of an accident mitigation device in a design expansion condition of a nuclear power plant, in which a large-capacity electric storage device is transported by helicopter and the large-capacity electric storage device has a capacity of 15,000 Ah or more.

3. In paragraph 1, Step for calculating the required power supply time from the usage of a large capacity power storage device connected to a 125 VDC safety bus terminal; A step of additionally requesting transportation of a large-capacity electric storage device stored in an integrated storage facility or a mobile facility storage facility, if the calculated required power supply availability time is less than the arrival time of the mobile power generation facility at the nuclear power plant; An accident mitigation response method of an accident mitigation device in the event of an accident under the design extension conditions of a nuclear power plant, which further includes.

4. In paragraph 1, A step of requesting a return of the helicopter or transport drone when the mobile power generation facility supplies essential power through a 125 VDC safety bus before the helicopter or transport drone transports the large-capacity electrical storage device to the roof of the reactor auxiliary building; An accident mitigation response method of an accident mitigation device in the event of an accident under the design extension conditions of a nuclear power plant, which further includes.

5. In paragraph 1, The above mobile power generation facility is a 1 MW mobile power generation vehicle or a 3.2 MW mobile power generation vehicle. Accident mitigation response method of accident mitigation device in case of design expansion condition accident of nuclear power plant.

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