An extended operation method for a power supply system

Abstract

The present invention discloses an extended operation method for a power supply system. The power supply system includes: a thermoelectric conversion device installed in the residual heat removal pipeline of the reactor core for generating electricity by utilizing the residual heat of the reactor core; a power management device connected to the thermoelectric conversion device for managing the electricity generated by the thermoelectric conversion device; and a storage battery connected to the power management device or a charging power source for supplying power to loads. The power supply system is provided with a thermoelectric conversion device, and realizes self-power supply for the storage battery based on the waste heat emission of the nuclear power plant itself, which can greatly improve the power supply capacity of the storage battery and ensure the safe operation of the nuclear power plant; the extended operation method can reasonably plan the electricity load in each stage, and when used in conjunction with the foregoing power supply system, can effectively extend the service life of the storage battery.

Description

Technical Field

[0001] The present invention belongs to the field of power supply, and particularly relates to an extended operation method for a power supply system. Background Art

[0002] A complete loss of power is an extreme condition that may occur in a nuclear power plant. The nuclear accident that occurred at the Fukushima nuclear power plant in Japan shows that extreme external disasters and equipment failure problems may lead to a complete loss of power in the nuclear power plant and the loss of all heat sinks, ultimately resulting in a serious accident of core damage, bringing catastrophic consequences to people's lives and the environment. Therefore, the design and operation of nuclear power plants should strive to ensure nuclear safety under extreme conditions such as a complete loss of power. To ensure nuclear safety under extreme conditions such as a complete loss of power, the fundamental problem is the power supply problem, and the power supply for safety equipment required to mitigate the consequences of accidents under accidents should be ensured. Usually, emergency diesel generator sets are set up in nuclear power plants as emergency power supplies when the normal power supply is lost, and backup diesel generator sets, dedicated battery packs, and mobile diesel generator sets are used as backup power supplies for dealing with a complete loss of power.

[0003] However, the above-mentioned diesel generator sets generate electricity by converting the chemical energy of fuel into heat energy through internal combustion engine technology and doing work through rotating machinery. There are the following deficiencies in terms of actual operation and maintenance availability: 1) The system operation reliability is relatively low: Due to the complex system structure and many factors affecting system availability, it may be affected by external disasters, component failures, etc., and problems such as inability to start and inability to carry load may occur, thus affecting power supply reliability and further affecting the safety of nuclear power plants; 2) The response ability is insufficient: Since the start-up of diesel generator sets requires certain procedures and steps, after receiving the start-up command, it usually takes a certain amount of time to normally output electricity and gradually carry load, posing challenges and pressures to the safety design of nuclear power plants. 3) The system for maintaining the normal operation of diesel generator sets is huge, with a complex structure, troublesome maintenance and high costs; 4) The fuel stored in the plant area is limited, and the fuel cost is high.

[0004] In fact, the Fukushima nuclear accident has shown that when the external power supply is lost due to external disasters such as tsunamis, the accompanying failure of diesel generator sets is very likely to occur. Under the condition of a complete power outage of the whole plant, after the diesel generator sets fail, only the battery pack power supply can be used to maintain the power supply of a few loads in the nuclear power plant, including the instrument control system, so that the operating personnel can continuously monitor and control the reactor state. However, the capacity of the battery pack is limited. Generally, in design, it only has the ability to supply power continuously for a limited time (typically 2 hours). Even if some nuclear power plants have expanded the battery capacity by equipping high-energy battery packs and other forms, it can only extend the power supply duration limitedly. The exhaustion of the battery is still inevitable. After the battery is exhausted, the entire nuclear power plant will lose all AC and DC power supplies, and the means of monitoring and controlling the nuclear power plant will be completely lost, and serious accident consequences will inevitably occur, posing a great threat to people, society and the environment. Summary of the Invention

[0005] In order to overcome the above technical defects, the present invention provides a power supply system and an extended operation method, which can supply power to the battery without relying on an external power supply.

[0006] The present invention is realized through the following solutions:

[0007] A power supply system, comprising:

[0008] A thermoelectric conversion device, installed on the residual heat removal pipeline of the reactor core, for generating electricity by using the residual heat of the reactor core;

[0009] A power management device, connected to the thermoelectric conversion device, for managing the power generated by the thermoelectric conversion device;

[0010] A battery, connected to the power management device or a charging power supply, for supplying power to a load.

[0011] As a further improvement of the present invention, the present invention further includes: a static transfer switch, and the power management device and the charging power supply are connected to the battery through the static transfer switch.

[0012] As a further improvement of the present invention, the thermoelectric conversion device includes: a heat dissipation component, a thermoelectric conversion component and a heat collection component;

[0013] The heat collection component is sleeved on the outer surface of the residual heat removal pipeline, the thermoelectric conversion component is closely arranged against the heat collection component, and the heat dissipation component is located on the other side of the thermoelectric conversion component away from the heat collection component.

[0014] As a further improvement of the present invention, the thermoelectric conversion component includes: a plurality of thermoelectric conversion materials; a plurality of the thermoelectric conversion materials are connected in series and then in parallel to form the thermoelectric conversion component.

[0015] As a further improvement of the present invention, the power management device includes:

[0016] A boost unit, connected to the thermoelectric conversion device, for boosting the electric energy.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: A thermoelectric conversion device is provided, and self-power supply for the storage battery is realized based on the waste heat emission of the power station itself, which can greatly improve the power supply capacity of the storage battery and ensure the safe operation of the nuclear power station.

[0018] In addition, the present invention also provides an extended operation method, which is applied to the above power system and includes the steps of:

[0019] For a power plant where an accident occurs, divide the accident into several stages according to the development of the accident;

[0020] In different stages, determine the functions that the power plant needs to retain;

[0021] Determine the retained load according to the functions that need to be retained;

[0022] Determine the load shedding method according to the determined retained load.

[0023] As a further improvement of the present invention, the functions that need to be retained include: functions required to control the unit state under the current accident state, functions required to monitor the unit state under the current accident state, monitoring of system operation state parameters, monitoring of parameters related to nuclear accident emergency, monitoring of parameters required to monitor the power supply state, functions required to restore power supply, and functions related to the residence in the main control room.

[0024] As a further improvement of the present invention, the step of determining the retained load according to the functions that need to be retained includes:

[0025] For the load that can realize the functions that need to be retained, it is regarded as the retained load.

[0026] As a further improvement of the present invention, if a function that needs to be retained has been completed in the previous stage, then in this stage, the function that needs to be retained is a non-essential function; or if a function that needs to be retained has an alternative function that needs to be retained, then the function that needs to be retained is a non-essential function.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows: Divide the accident into several stages according to the development of the accident, reasonably plan the power consumption load in each stage, and cooperate with the aforementioned power system for use, which can effectively extend the use of the storage battery, avoid the depletion of the electric energy of the storage battery, thereby ensuring long-term monitoring of the reactor after the accident, and avoiding or delaying the core melting of the unit and large-scale radioactive release.

[0028] In addition, the present invention also provides a control system, which includes a processor and a memory. At least one instruction, at least one program, a code set or an instruction set is stored in the memory, and the at least one instruction, at least one program, the code set or the instruction set is loaded and executed by the processor to implement the above-mentioned extended operation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The following further describes in detail the specific embodiments of the present invention with reference to the drawings, wherein:

[0030] Figure 1 is a schematic structural diagram of the power supply system described in Embodiment 1;

[0031] Figure 2 is a schematic diagram of the installation position of the thermoelectric conversion device described in Embodiment 1;

[0032] Figure 3 is another schematic structural diagram of the power supply system described in Embodiment 1;

[0033] Figure 4 is a cross-sectional view of the thermoelectric conversion device described in Embodiment 1;

[0034] Figure 5 is a schematic connection diagram of the boost unit and the thermoelectric conversion material block described in Embodiment 1;

[0035] Figure 6 is a flowchart of the extended operation method described in Embodiment 2;

[0036] Figure 7 is a schematic diagram of the accident stage division described in Embodiment 2;

[0037] Figure 8 is a schematic diagram of parameter display in Embodiment 2;

[0038] Figure 9 is a flowchart of the extended operation method of a typical pressurized water reactor nuclear power plant described in Embodiment 2;

[0039] Figure 10 is a schematic diagram of the stage division of a typical pressurized water reactor nuclear power plant described in Embodiment 2.

[0040] Marking description: 1. Thermoelectric conversion device; 11. Heat dissipation component; 12. Thermoelectric conversion component; 121. Thermoelectric conversion material; 13. Heat collection component; 2. Power management device; 21. Boost unit; 3. Storage battery; 4. Static transfer switch; 5. Control system; 100. Core residual heat discharge pipeline; 200. AC charging power supply; 300. Load; 400. First position; 500. Second position. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0042] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of the present invention, the serial numbers of each step are only used to distinguish between steps, and do not represent that each step needs to be strictly executed in the order of the serial numbers.

[0043] Embodiment 1

[0044] This embodiment provides a power supply system. This embodiment is described with a nuclear power plant as the application scenario. As Figure 1 shown, it includes: a thermoelectric conversion device 1, a power management device 2, and a storage battery 3; the thermoelectric conversion device 1 is installed on the residual heat removal pipeline 100 of the reactor core and is used to generate electricity by using the residual heat of the reactor core; the power management device 2 is connected to the thermoelectric conversion device 1 and is used to manage the electricity generated by the thermoelectric conversion device 1; the storage battery 3 is connected to the power management device 2 or a charging power supply and is used to supply power to the load 300 of the nuclear power plant.

[0045] As Figure 2 shown, it is one of the installation methods of the thermoelectric conversion device 1 in this embodiment. The first position 400 is on the exhaust steam pipeline downstream of the atmospheric relief valve (i.e., the silencer position). Considering that the steam discharge is an open path, the installed thermoelectric conversion device 1 does not affect the original steam discharging to the atmosphere function. In particular, the thermoelectric conversion device 1 can also be integrated with the silencer and can be used as a silencer at the same time to eliminate the sharp noise of the steam discharging to the atmosphere.

[0046] The second position 500 is the steam pipeline of the passive residual heat removal system of the containment. The thermoelectric conversion device 1 is arranged around the steam pipeline to achieve thermoelectric conversion. Considering that the thermoelectric conversion device 1 itself is equipped with a heat dissipation device to achieve a higher thermoelectric conversion efficiency, from the perspective of discharging the heat in the containment, it is beneficial to discharge the heat in the containment after arranging the thermoelectric conversion device 1.

[0047] In order to minimize the impact on the existing systems and equipment, this embodiment further includes: a static transfer switch 4. The power management device 2 and the charging power supply are connected to the storage battery 3 through the static transfer switch 4. The existing AC charging power supply 200 of the storage battery 3 and the charging circuit of the thermoelectric conversion device 1 in this embodiment are connected to the storage battery 3 circuit in the form of a static transfer switch 4. The static transfer switch 4 can automatically switch to the charging circuit of the thermoelectric conversion device 1 when the AC charging power supply 200 is lost. As Figure 3 shown.

[0048] Figure 4 This is one of the structures of the thermoelectric conversion device 1. The thermoelectric conversion device 1 includes a heat dissipation component 11, a thermoelectric conversion component 12, and a heat collection component 13. Among them, the heat collection component 13 is sleeved on the outer surface of the waste heat discharge pipeline. The thermoelectric conversion component 12 is disposed closely against the heat collection component 13. The heat dissipation component 11 is located on the other side of the thermoelectric conversion component 12 away from the heat collection component 13. When the thermoelectric power generation sheet is working, a temperature difference is generated between the hot end in contact with the heat collection component 13 and the cold end in contact with the heat dissipation component 11. Based on this temperature difference, the thermoelectric power generation sheet realizes power generation.

[0049] The thermoelectric conversion device 1 is designed based on the static thermoelectric conversion material 121. The present invention preferably uses bismuth telluride material. Other optional static thermoelectric conversion materials 121 include arsenic telluride, lead telluride, etc.

[0050] The batteries 3 in pressurized water reactor nuclear power plants are mostly of 48V DC or 110V DC standard voltages. In order to meet the charging requirements of the batteries 3, it is necessary to manage the electric energy output by the thermoelectric conversion device 1 to achieve the floating charge of the batteries 3 while improving the efficiency of the entire device. The output voltage of a single thermoelectric conversion material 121 is limited (generally below 5V). In order to increase the output voltage of the thermoelectric conversion device 1, in this embodiment, several thermoelectric conversion materials 121 are connected in series. At the same time, in order to improve the efficiency of the entire device, the serially connected thermoelectric conversion materials 121 are connected in parallel to form the thermoelectric conversion component 12 to reduce the internal resistance, thereby increasing the output power and the thermoelectric conversion efficiency.

[0051] Taking the 48V DC battery 3 as an example, assuming that the output voltage of a single thermoelectric conversion material 121 is between 2 and 3V DC (the output voltage is determined by the temperature difference between the inner and outer end faces of the thermoelectric conversion material 121 and is related to factors such as the decay heat power of the reactor core and the ambient temperature, so it is not a fixed value), then six thermoelectric conversion materials 121 can be considered to be connected in series, as Figure 5 shown, so as to reach an output voltage of 12 to 18V DC; at the same time, in order to achieve the required electric power output, the serially connected thermoelectric conversion materials 121 are connected in parallel.

[0052] As Figure 4 shown, the heat collection component 13 is made of a metal material with good thermal conductivity. The inner end face of the heat collection component 13 is designed in an arc shape to closely fit the outer wall of the steam pipeline (waste heat discharge pipeline), so as to achieve the purpose of effectively conducting the heat in the steam pipeline to the inner end face of the thermoelectric conversion material 121. For the convenience of installation, the heat collection component 13 can adopt a modular split design. For example, Figure 4The heat collection component 13 shown can be divided into six parts according to the arrangement of 121 pieces of thermoelectric conversion materials. The heat collection component 13 also serves as a fixing component. The power generation module composed of the thermoelectric conversion materials 121 and the heat dissipation component 11 is closely attached to and fixed on the heat collection component 13, and the gap between the two can be filled with thermal conductive glue.

[0053] Estimation of power generation: Taking a typical 100 MW-class nuclear power plant as an example, assuming the rated thermal power of the reactor core is 2895 MW, the decay heat power after its accidental shutdown is estimated. The remaining decay heat power is about 17158.7 kW one day after shutdown, and about 7923.6 kW ten days after shutdown. Calculated conservatively at a thermoelectric conversion efficiency of 0.1%, the electric power output by this thermoelectric conversion device 1 is about 17 kW one day after shutdown and about 7.9 kW ten days after shutdown. Considering that the loads carried by the battery 3 are mostly for instrument control systems, solenoid valves, etc., with relatively small loads of 300, and also considering that as the accident progresses, the equipment no longer required for accident handling will be gradually cut off according to the extended operation method of the battery 3, the load 300 required for accident handling will become smaller and smaller. Therefore, although the decay heat power of the reactor core gradually decreases with the increase of the shutdown time, the electric power output by this thermoelectric conversion device 1 can meet the requirement of floating charging the battery 3.

[0054] As Figure 5 shown, the power management device 2 includes: a boost unit 21, connected to the thermoelectric conversion device 1, for boosting the electric energy to achieve a voltage output that meets the charging requirements.

[0055] In this embodiment, it is considered to arrange the thermoelectric conversion device 1 at a suitable position in the decay heat discharge path of the reactor core under the condition of full-field power failure. Without affecting the function of residual heat discharge, power is generated using static thermoelectric conversion technology. The electric energy generated by the thermoelectric conversion device 1 reaches the stable voltage required for charging the battery 3 after passing through the power management device 2, and the floating charging of the battery 3 is achieved through a static transfer switch.

[0056] In summary, this embodiment has the following technical effects:

[0057] 1) Generate electricity using the residual heat of the reactor core without additional fuel, thus eliminating the fire load brought by fuel storage, without the need for a large and complex fire protection design, and having good safety;

[0058] 2) Adopt static thermoelectric conversion technology. While simplifying the structure, since there are no rotating parts, no lubrication is required, no or only a very small amount of auxiliary support system is needed, and it can work within a large temperature range, with high power supply reliability;

[0059] 3) Fast power supply response: The static thermoelectric power supply can generate electricity when there is residual heat discharge (with a temperature difference), without a complex program loading process;

[0060] 4) Low investment and obvious benefits: The thermoelectric conversion device does not involve any modifications to the original process system. On the premise of a relatively small increase in the total cost, a new power supply system is realized, providing a reliable power supply for the nuclear power plant, which can greatly improve the safety of the nuclear power plant.

[0061] Embodiment 2

[0062] This embodiment provides an extended operation method, which is applied to the power supply system of Embodiment 1. For the loads downstream of the battery, an extended operation method for the battery is formulated, and reasonable planning is carried out according to the extended operation method of the battery. By dividing the full-field power failure condition into different stages according to the development trend of the accident transient, from the perspectives of accident monitoring, control and mitigation, the power consumption load of each stage is reasonably planned, so as to extend the service time of the battery, avoid the situation of battery exhaustion, ensure long-term stable and continuous monitoring of the reactor state, and avoid or delay the core melting of the unit and large-scale radioactive release.

[0063] This embodiment is described in detail taking a nuclear power plant as an example, as Figure 6 shown, the extended operation method includes the steps:

[0064] S1. For the nuclear power plant where an accident occurs, the accident is divided into several stages according to the accident development.

[0065] The purpose of the extended operation method of the battery is to effectively manage the battery load in combination with the accident development process, gradually cut off the loads that are no longer needed for subsequent accident handling according to the accident development process, so as to minimize the consumption of the battery and extend the service life of the battery. Combining with the power supply system of Embodiment 1, it is possible to realize the full-process monitoring of the unit from the occurrence of a full-field power failure until the unit deteriorates into a severe accident. As Figure 7 shown, first, the accident stage is divided into: the first stage, the second stage and the third stage in combination with the development process of the full-field power failure accident.

[0066] The first stage: The 30 minutes after the occurrence of the full-field power failure accident is regarded as the first stage. Within the first stage, the unit's automatic action response is completed, including the automatic action of the reactor protection system to shut down the reactor, the turbine trip, etc. At the same time, the 30 minutes also takes into account the time required for the operator to comprehensively diagnose the unit state and confirm the occurrence of the full-field power failure accident. After 30 minutes, it is assumed that the operator starts to perform manual intervention operations.

[0067] The second stage: The interval from 30 minutes after the total power outage to the beginning of the degradation of the core cooling state is regarded as the second stage. At the beginning of this stage, the primary pressure boundary barrier is intact, the core decay heat is discharged by the atmospheric release valve, and the water charge of the steam generator is guaranteed by the auxiliary feedwater pump; then, as the sealing performance of the passive shutdown seal is lost, the primary pressure boundary barrier is no longer intact, and as the primary coolant is continuously discharged from the shaft seal into the containment, the primary water charge continues to deteriorate, and the environment in the containment also continues to deteriorate. Until the core cooling state is degraded (for example, the saturation of the primary coolant and the water level of the pressure vessel is lower than the bottom of the hot pipe section as the criterion for the degradation of the core cooling state), the hot pipe section is no longer a pure liquid phase, the natural circulation of the loop is interrupted, and the heat conduction capacity of the steam generator can no longer be guaranteed.

[0068] The third stage: The period after the core cooling state is degraded is regarded as the third stage. After the core cooling state is degraded (e.g., the saturation of the primary coolant and the water level of the pressure vessel is lower than the bottom of the heat pipe section as the criterion for the degradation of the core cooling state), the loop coolant is in a two-phase state, the natural circulation is interrupted, and the core decay heat discharge transitions from being dominated by the steam generator to being dominated by the shaft seal breach. During this period, due to the continuous release of mass and energy from the primary coolant into the containment through the shaft seal breach, the environment of the containment continues to deteriorate, and the passive cooling system of the containment needs to be put into operation to ensure the integrity of the containment barrier and prevent the release of radioactive substances outside the containment.

[0069] S2. Determine the functions that need to be retained in the nuclear power plant at different stages. The functions that need to be retained include:

[0070] Functions required to control the unit status under the current accident state: including control of the atmospheric release valve (controlling the cooling rate by adjusting the valve opening), control of the injection box isolation valve (closing the isolation valve when necessary to avoid nitrogen injection into the primary circuit), control of the steam-driven feedwater pump (adjusting the steam generator feedwater flow), control of the passive containment cooling system pipeline valve (non-passive containment cooling system put into operation), etc.

[0071] Functions required to monitor the status of the unit under the current accident state: typically including monitoring of unit status functional parameters (such as pressure vessel water level, core outlet coolant subcooling, steam generator water charge, containment temperature and pressure, containment dose rate), etc.

[0072] Monitoring of system operating status parameters (such as steam-driven water supply pump flow): including atmospheric relief valve opening, steam-driven water supply pump flow, etc.

[0073] Parameter monitoring involved in nuclear accident emergency response: including radioactive monitoring of gaseous and liquid effluent emissions from the plant area.

[0074] Parameter monitoring required for monitoring the power supply status: including battery voltage, switchboard fault alarm, battery room temperature, etc.

[0075] Functions required for restoring power supply: including status monitoring of power supply switches, operation control of power supply switches, etc.

[0076] Functions related to occupancy in the main control room: including emergency lighting in the main control room, etc.

[0077] It should be noted that if a function to be retained has been completed in the previous stage, then in this stage, the function to be retained is considered a non-essential function. For example, for the operation control of the power supply switch, if it can be achieved through on-site operation, then the operation control function of the power supply switch is not considered necessary. Or if a function to be retained has an alternative function to be retained, then the function to be retained is a non-essential function. For example, after automatic reactor shutdown and turbine shutdown are successful, the functions of automatic reactor shutdown and turbine shutdown are no longer required in subsequent stages.

[0078] S3. Determine the retained load according to the functions to be retained. The principle for load retention is that the retained load should be able to achieve the aforementioned required functions. That is, the power supply to all equipment and components involved in achieving the aforementioned functions cannot be cut off. For example Figure 8 As shown, in order to ensure the monitoring of the core outlet temperature in the main control room, the power supply to the instruments, DCS signal acquisition cabinets, and DCS signal processing cabinets cannot be cut off. Considering that this parameter is displayed on the mimic panel and digitally in the main control room, the power supply to the digital information system cabinet can be cut off, and only the mimic panel display is retained.

[0079] S4. Determine the load cut-off method according to the determined retained load. The load cut-off method can be selected according to the actual situation by disconnecting the downstream outlet switch of the battery (mainly for equipment directly powered by the battery, such as solenoid valves), or the switch in the downstream power distribution cabinet of the battery (mainly for equipment with secondary power distribution cabinets, such as disconnecting the corresponding switch in the DCS power distribution cabinet to cut off the power supply to the corresponding DCS signal acquisition and processing cabinets) to cut off the power supply to equipment other than the retained load.

[0080] For some specific loads, the cut-off timing is closely related to the accident handling process. For example, after the accumulator injection is completed, the operator needs to manually close the accumulator isolation valve to prevent nitrogen from being injected into the primary circuit. After the operator manually closes the accumulator isolation valve, the power supply to the accumulator isolation valve can be cut off.

[0081] Next, the present embodiment will be further explained in combination with the specific implementation process as follows:

[0082] Such as Figure 9 And Figure 10As shown in the figure, in a typical pressurized water reactor nuclear power plant, the full power loss condition is divided into three stages according to the accident development process. Then, the functional requirements, the equipment involved, and the loads to be retained in each accident stage are screened and determined, as shown in Table 1.

[0083] When the accident is in the first stage, in the first stage, any load of the battery is not considered to be disconnected. This is because the battery is generally designed to operate at full load for 2 hours, and the duration of the first stage is 30 minutes. 30 minutes will not cause a large consumption of the battery capacity while ensuring that all automatic actions are completed; moreover, in the first stage, the operator is busy making a comprehensive and accurate diagnosis of the unit status. It is not realistic to perform the operation of cutting off part of the battery load during this period. Therefore, the battery provides power for all loads in the first stage, that is, the cutting off of the battery load is not considered, so as to ensure the complete automatic response of the unit and the comprehensive and correct diagnosis of the unit status by the operator.

[0084] When the accident is in the second stage, after the automatic actions are completed, the equipment involved in the relevant automatic action functions is no longer needed, and the power supply to these equipment can be cut off; except for the retained loads listed in the table, other battery loads can be cut off planned (including non-safety-class DCS cabinets, control power loads of non-safety-class DCS equipment, non-safety-class instruments, non-safety-class solenoid valves, etc.). At the same time, in the second stage, if the containment isolation is performed, the power supply of the containment isolation valve on the containment penetration pipeline can be cut off. After the accumulator tank is emptied, the operator closes the accumulator tank isolation valve, and the power supply of the valve can be cut off after the valve is closed.

[0085] At the same time, in the first stage and the early stage of the second stage, the steam generator dominates the removal of the decay heat of the reactor core. Since the atmospheric relief valve exhaust pipeline discharges saturated steam to the atmosphere, there is an obvious temperature difference between the atmospheric relief valve exhaust pipeline and the environment. The thermoelectric conversion device arranged there is automatically put into operation. Due to the loss of AC power, the changeover switch switches to the line where the thermoelectric conversion device is located. The electric energy generated by the thermoelectric conversion device provides charging power for the battery after passing through the power management module.

[0086] In the third stage, the unit is in the transition stage to the severe accident stage. The goal of this stage is to monitor the operation status of the passive containment cooling system and ensure the integrity of the containment barrier. Therefore, except for the loads to be retained listed in the table, other loads (including the loads related to the heat removal of the steam generator in the second stage) can be cut off.

[0087] Meanwhile, in the later stage of the second phase, when it is monitored that the environment inside the containment deteriorates to a certain extent (for example, when the pressure inside the containment increases due to the continuous mass-energy release of the primary coolant through the shaft seal break, and the pressure exceeds 0.24 MPa, it is considered that the environment inside the containment deteriorates), the operator will put into operation the passive residual heat removal system of the containment. The high-temperature steam inside the containment flows in the pipeline of the passive residual heat removal system, generating a significant temperature difference with the external environment. The thermoelectric conversion device arranged there will be automatically put into operation. Due to the loss of AC power, the switch is switched to the circuit where the thermoelectric conversion device is located. The electric energy generated by the thermoelectric conversion device provides a charging power supply for the battery after passing through the power management module.

[0088]

[0089]

[0090]

[0091] In this embodiment, by dividing the accident into several stages according to the accident development and reasonably planning the power consumption load of each stage, from the perspectives of accident monitoring, control, and mitigation, the power consumption load of each stage is reasonably planned, thereby extending the service time of the battery, avoiding the depletion of the battery, ensuring the long-term monitoring of the reactor after the accident, avoiding or delaying the core melting of the unit and large-scale radioactive release, and cooperating with the power supply system of Embodiment 1, it can ensure that the battery power will never be depleted under the condition of a complete power outage of the whole plant, and further ensure the continuous monitoring and control of the reactor state during the entire accident development process, comprehensively improving the self-sustaining ability of the nuclear power plant under the condition of a complete power outage of the whole plant.

[0092] Embodiment 3

[0093] This embodiment provides a control system, which includes a processor and a memory. At least one instruction, at least one program, a code set, or an instruction set is stored in the memory, and the at least one instruction, at least one program, the code set, or the instruction set is loaded and executed by the processor to implement the extended operation method as in Embodiment 2

[0094] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An extended operation method for a power supply system, characterized in that, Applied to a power supply system, the power supply system includes: A thermoelectric conversion device installed in the residual heat removal pipeline of the reactor core for generating electricity by using the residual heat of the reactor core; A power management device connected to the thermoelectric conversion device for managing the electricity generated by the thermoelectric conversion device; A storage battery connected to the power management device or a charging power supply for supplying power to loads; The extended operation method includes the steps of: For a power plant in an accident, divide the accident into a first stage, a second stage, and a third stage according to the development of the accident; Regard the 30 minutes after the occurrence of a station blackout accident as the first stage. In the first stage, do not disconnect any load of the storage battery; Regard the interval from 30 minutes after the occurrence of a station blackout accident to the start of the degradation of the reactor core cooling state as the second stage, and cut off the automatic reactor shutdown, turbine trip, main steam isolation, main feed water isolation, other I&C systems, and other storage battery loads; Regard the time period after the degradation of the reactor core cooling state as the third stage, and cut off the control of the safety injection tank isolation valve, the control of the atmospheric relief valve, the control of the motor-driven feed water pump, the containment isolation, the monitoring of the pressure vessel water level, the monitoring of the primary loop pressure, the monitoring of the steam generator water inventory, and the monitoring of the steam generator pressure; The functions that need to be retained include: the functions required to control the unit state under the current accident state, the functions required to monitor the unit state under the current accident state, the monitoring of system operation state parameters, the monitoring of parameters related to nuclear accident emergency, the monitoring of parameters required to monitor the power supply state, the functions required for restoring power supply, and the functions related to the occupancy of the main control room; The functions required to control the unit state under the current accident state: include the control of the atmospheric relief valve, the control of the safety injection tank isolation valve, the control of the motor-driven feed water pump, and the control of the valves in the passive containment cooling system pipeline; The functions required to monitor the unit state under the current accident state: include the monitoring of the functional parameters of the unit state; The monitoring of system operation state parameters: includes the opening of the atmospheric relief valve and the flow rate of the motor-driven feed water pump; The monitoring of parameters related to nuclear accident emergency: includes the monitoring of the radioactivity of gaseous and liquid effluent emissions in the plant area; The monitoring of parameters required to monitor the power supply state: includes the storage battery voltage, the distribution panel fault alarm, and the temperature of the storage battery room; The functions required for restoring power supply: includes the state monitoring of the power supply switch and the operation control of the power supply switch; The functions related to the occupancy of the main control room: includes the emergency lighting in the main control room; If a function that needs to be retained has been completed in the previous stage, then in this stage, the function that needs to be retained is a non-essential function; or if a function that needs to be retained has an alternative function that can replace it, then the function that needs to be retained is a non-essential function; The steps for determining the retained loads according to the functions that need to be retained include: For the loads that can realize the functions that need to be retained, regard them as the retained loads; The principle of load retention is: the retained loads complete the realization of the functions required above, that is, the power supply of all equipment and components involved in realizing the above functions cannot be cut off; Determine the load shedding method according to the determined retained load. The load shedding method is selected according to the actual situation by disconnecting the outgoing line switch downstream of the battery or the switch in the distribution cabinet downstream of the battery to cut off the power supply of the equipment other than the retained load. For some specific loads, the cut-off timing is closely related to the accident handling process. After the injection of the safety injection tank is completed, the operator manually closes the isolation valve of the safety injection tank to avoid nitrogen injection into the primary loop. After the operator manually closes the isolation valve of the safety injection tank, the power supply of the isolation valve of the safety injection tank is cut off.

2. The extended operation method according to claim 1, wherein The power supply system further includes: a static transfer switch, and the power management device and the charging power supply are connected to the battery through the static transfer switch.

3. The extended operation method according to claim 1, characterized in that The thermoelectric conversion device includes: a heat dissipation component, a thermoelectric conversion component, and a heat collection component; The heat collection component is sleeved on the outer surface of the residual heat removal pipeline, the thermoelectric conversion component is disposed closely against the heat collection component, and the heat dissipation component is located on the other side of the thermoelectric conversion component away from the heat collection component.

4. The extended operation method according to claim 3, characterized in that The thermoelectric conversion component includes: a plurality of thermoelectric conversion materials; a plurality of the thermoelectric conversion materials are connected in series and then in parallel to form the thermoelectric conversion component.

5. The extended operation method according to claim 1, characterized in that, The power management device includes: A boost unit, connected to the thermoelectric conversion device, for boosting the electric energy.

6. A control system, characterized in that, The control system includes a processor and a memory. At least one instruction, at least one program, a code set or an instruction set is stored in the memory. The at least one instruction, at least one program, the code set or the instruction set is loaded and executed by the processor to implement the stretching operation method according to any one of claims 1 to 5.

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