A method and system for identification of a nuclear power plant fire leading operational event

Abstract

This invention relates to a method and system for identifying operational events caused by fires in nuclear power plants. The method includes acquiring fire information from the nuclear power plant; determining whether a fire has been confirmed based on the fire information; if so, determining whether the fire falls under an accident operation condition; if it falls under an accident operation condition, managing the fire based on an accident operation condition management model; if it does not fall under an accident operation condition, identifying the operational events caused by the fire based on the damage to safety items caused by the fire. This invention manages fires according to accident operation conditions for situations requiring accident operation, based on the different consequences of the fire. For situations that do not lead to accident operation conditions, it reviews the safety items damaged by the fire and assesses their impact on safety functions, identifies inoperable safety functions, and records corresponding operational events. This achieves the goal of comprehensively identifying operational events caused by fires, providing an important basis for effective and accurate management of nuclear power plant fires and ensuring the operational safety of nuclear power plants.

Description

Technical Field

[0001] This invention relates to the technical field of nuclear power plant operation safety, and more specifically, to a method and system for identifying operational events caused by nuclear power plant fires. Background Technology

[0002] Fire is one of the external hazards that nuclear power plants must consider. Nuclear power plant fire safety design generally takes a comprehensive approach, encompassing fire prevention, detection, and suppression. It not only aims to reduce the likelihood of fires but also to ensure a rapid response to fire incidents, mitigating the impact on the units. Nuclear power plants typically separate redundant equipment performing the same safety function by dividing the area into fire compartments, supplemented by fire doors, smoke exhaust valves, and other fire-fighting facilities to limit the consequences of a fire in one area and prevent its spread to adjacent fire compartments. Regarding the impact of fire on the safe operation of the units, considering the numerous and complex pieces of equipment in nuclear power units and the continuous and spreading nature of fires, the impact of fire on safe operation is highly uncertain. Relying solely on the operator's skill level to judge the consequences of a fire could lead to inappropriate operational decisions, posing a threat to the safe operation of the units. Therefore, it is necessary to develop a systematic method for identifying fire-induced operational events in order to comprehensively and effectively identify such events, help operators quickly assess the impact of fire on unit operation, provide decision-making basis for operators to control unit operation, and help operators take timely and reasonable intervention measures to bring the unit to a safe state.

[0003] Based on the above requirements, existing technologies have proposed relevant methods. Among them, the document "A Method for Guiding a Nuclear Power Plant to a Safe State in the Event of a Fire" discloses a method for guiding a nuclear power plant to a safe state in the event of a fire. This method sorts out the existing operation and accident procedures of the nuclear power plant to extract key information for unit status judgment and procedure guidance for each fire-protected space; sorts out the unusable functions, equipment and information caused by the fire to determine whether the fire has caused unacceptable consequences. If the fire will cause unacceptable consequences, in addition to basic fire fighting and rescue operations, the operator performs specific operations to ensure the safety of the unit. The series of action requirements for guiding the unit to a safe state in the event of a fire formed by the present invention make the operator's operation of the unit in the event of a fire have a basis. This technical solution requires sorting out the missing unit unusable functions, status judgment and procedure guidance information caused by the fire in the fire compartment to guide the operator's subsequent control of the unit status operation. This solution has the following shortcomings: (1) This technical solution only considers the situation where the fire needs to enter the accident procedure and controls the unit with the help of the accident procedure. For fires with relatively minor consequences, they often do not need to be included in the scope of accident operation and can be managed in accordance with the technical specifications and technical requirements manual. This technical solution does not distinguish between such cases. (2) This technical solution only provides guidance for operators to control the unit with the help of accident procedures after a fire, but it fails to clearly show the operators the consequences of the fire and cannot help operators fully grasp the status of the unit.

[0004] In addition, the document "Intelligent Technology Specification Method and System for Nuclear Power Plants" discloses an intelligent technology specification method and system for nuclear power plants. The method includes: obtaining the predetermined operating signals and equipment status of the nuclear power plant through the nuclear power plant KNS system; judging the operating condition of the nuclear power plant based on the equipment status; judging whether a predetermined event is triggered based on the operating signals, operating conditions and preset thresholds; when it is judged that a predetermined event is triggered, activating the predetermined event and triggering the corresponding handling measures and supervision requirements, and simultaneously starting a timer to remind the operator to complete the handling measures required by the specification within the specified time. This invention can intuitively reflect the safety indicators of the nuclear power plant, which is conducive to the operator to quickly handle events, thereby improving the safety of the nuclear power plant, improving the economic efficiency and availability of the unit, and has high market economic value. The technical solution has the following shortcomings: (1) The technical solution mainly judges whether a predetermined event is triggered based on preset thresholds. It judges whether the corresponding function is lost by monitoring whether specific physical parameters such as flow rate and temperature exceed the corresponding thresholds. It should be noted that the thresholds cannot fully reflect the operability of all functions. Especially considering the complexity of the consequences of a fire, a fire may damage cables, instruments, instrumentation cabinets or process equipment itself, it is unrealistic to judge the operability of a function based solely on a threshold. (2) This technical solution only considers the situation where the system has not entered accident operation. For a nuclear power plant fire, considering that a fire may damage the optical cables of the instrumentation system and the instrumentation cabinets, the large-scale unavailability will lead to difficulties in data transmission, and this technical solution is no longer applicable in the event of a fire. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method and system for identifying operational events caused by fires in nuclear power plants, in order to address the deficiencies of the prior art.

[0006] The technical solution adopted by this invention to solve its technical problem is: to construct a method for identifying operational events caused by a nuclear power plant fire, comprising the following steps:

[0007] Obtain information on fires at nuclear power plants;

[0008] Determine whether a fire is confirmed based on the fire information provided.

[0009] If so, determine whether the fire falls under the category of an accidental operating condition;

[0010] If the operation is in an accident-prone condition, the fire will be managed based on the accident-prone condition management model.

[0011] If it does not fall under the accident operation condition, the fire-induced operation event is identified based on the damage to safety items caused by the fire.

[0012] In the method for identifying operational events caused by nuclear power plant fires according to the present invention, determining whether a fire belongs to an accidental operating condition includes:

[0013] Determine whether the fire directly caused the accident.

[0014] If so, the fire is determined to be an accidental operating condition;

[0015] If not, determine whether the fire caused the automatic shutdown of the reactor.

[0016] If the fire leads to automatic shutdown, it is determined to be an accidental operating condition.

[0017] If the fire does not lead to an automatic shutdown, determine whether the fire has caused the loss of the nuclear steam supply system required for normal operation.

[0018] If the fire causes the nuclear steam supply system to lose its function, it is determined to be an accidental operating condition.

[0019] If the fire did not cause the nuclear steam supply system to lose its function, then determine whether the fire caused the loss of function of an important support system.

[0020] If the fire results in the loss of important support system functions, the determination of whether the fire constitutes an accidental operating condition will be made based on feedback from the operating experience of similar units.

[0021] In the method for identifying operational events caused by nuclear power plant fires according to the present invention, the fire management based on the accident operation condition management mode includes:

[0022] Define the interface for fire and accident procedures, and manage fires based on the interface for fire and accident procedures.

[0023] In the method for identifying operational events caused by nuclear power plant fires according to the present invention, the interface between the fire and the accident procedure includes: confirming the fire before entering the accident procedure and confirming the fire during the execution of the accident procedure.

[0024] The interface for determining fire and accident procedures, and the management of fires based on the interface for fire and accident procedures, include:

[0025] If the interface between the fire and accident procedures is to confirm the fire before entering the accident procedures, then the following steps are performed:

[0026] Obtain the initial status parameters of the unit;

[0027] Determine whether the unit's status parameters have degraded based on the initial status parameters;

[0028] If so, the fire should be handled based on the accident conditions.

[0029] If not, the fire will be handled based on the fault condition.

[0030] In the method for identifying operational events caused by nuclear power plant fires according to the present invention, the fire handling based on accident conditions includes:

[0031] Accident handling sequence processing based on accident conditions;

[0032] Fire monitoring is performed after the incident handling sequence is completed;

[0033] Determine whether there is a loss of support function monitoring and / or nuclear steam supply system function monitoring based on fire monitoring information;

[0034] If so, then the unit status should be re-diagnosed;

[0035] Determine whether the unit's status parameters have been downgraded based on the re-diagnosis results;

[0036] If downgraded, it will enter the accident procedure handling sequence;

[0037] If no downgrade is performed, the process returns to the steps of the accident handling sequence based on the accident condition.

[0038] In the method for identifying operational events caused by nuclear power plant fires according to the present invention, the fire handling based on fault conditions includes:

[0039] Accident handling sequence processing based on fault conditions;

[0040] Fire monitoring is performed after the incident handling sequence is completed;

[0041] Determine whether the monitoring function supporting the nuclear steam supply system has been lost based on fire monitoring information;

[0042] If so, then the unit status should be re-diagnosed;

[0043] Determine whether the unit's status parameters have been downgraded based on the re-diagnosis results;

[0044] If downgraded, it will enter the accident procedure handling sequence;

[0045] If no downgrade is performed, return to the step of obtaining the initial state parameters of the unit.

[0046] In the method for identifying operational events caused by nuclear power plant fires according to the present invention, the step of determining the interface between the fire and accident procedures, and managing the fire based on the interface between the fire and accident procedures, further includes:

[0047] If the interface between the fire and accident procedures is that a fire is confirmed during the execution of the accident procedures, then the following steps are performed:

[0048] Perform fire monitoring;

[0049] Determine whether the system has nuclear steam supply system monitoring capabilities based on fire monitoring information;

[0050] If so, the unit status will be re-diagnosed based on the fire monitoring information.

[0051] Determine whether the unit's status parameters have been downgraded based on the re-diagnosis results;

[0052] If downgraded, it will enter the accident procedure handling sequence;

[0053] If no downgrade occurs, the procedure returns to the steps of the accident handling sequence based on the accident condition in the accident condition; or, if no downgrade occurs, the procedure returns to the steps of obtaining the initial state parameters of the unit in the fault condition.

[0054] In the method for identifying operational events caused by nuclear power plant fires according to the present invention, the identification of operational events caused by fires based on damage to safety items due to fires includes:

[0055] Retrieve damaged security items;

[0056] Assess the impact on safety functions based on the damaged safety items;

[0057] Based on the impact of the security function, determine whether the security function is inoperable;

[0058] If it can be run, return to the step of retrieving the damaged security item;

[0059] If it is not operable, obtain the current operating mode of the unit and determine whether the safety function that is not operable is required to be operable under the current operating mode;

[0060] If so, then the running events of the aforementioned non-operable security functions will be logged;

[0061] If not, return to the step of retrieving the damaged security item.

[0062] In the method for identifying operational events caused by a nuclear power plant fire according to the present invention, the step of recording operational events for the non-operable safety functions includes:

[0063] Based on the non-operable security function, obtain the operating event corresponding to the non-operable security function;

[0064] Obtain and record the measures and completion time corresponding to each of the aforementioned running events.

[0065] The present invention also provides a system for identifying operational events caused by fires in nuclear power plants, comprising:

[0066] The acquisition unit is used to acquire fire information from nuclear power plants.

[0067] The fire confirmation unit is used to determine whether a fire is confirmed based on the fire information.

[0068] The judgment unit is used to determine whether a fire falls under an accidental operating condition when a fire is confirmed to have occurred.

[0069] The accident operation management unit is used to manage fires based on the accident operation condition management mode when the fire is in an accident operation condition.

[0070] The identification unit is used to identify fire-related operational events based on the damage to safety items caused by the fire, even if the fire is not considered an accidental operating condition.

[0071] The method and system for identifying operational events caused by nuclear power plant fires according to the present invention have the following beneficial effects: They include: acquiring fire information of the nuclear power plant; determining whether a fire has been confirmed based on the fire information; if so, determining whether the fire falls under an accident operation condition; if it falls under an accident operation condition, managing the fire based on an accident operation condition management mode; if it does not fall under an accident operation condition, identifying operational events caused by the fire based on the damage to safety items caused by the fire. The present invention manages fires according to accident operation conditions for situations requiring accident operation, based on the different consequences of the fire. For situations that do not lead to accident operation conditions, it reviews the safety items damaged by the fire and assesses their impact on safety functions, identifies inoperable safety functions, and records corresponding operational events, thereby achieving the goal of comprehensively identifying operational events caused by fires. This provides an important basis for the effective and accurate management of nuclear power plant fires and ensures the operational safety of nuclear power plants. Attached Figure Description

[0072] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0073] Figure 1 This is a flowchart illustrating the method for identifying operational events caused by nuclear power plant fires, provided in an embodiment of the present invention.

[0074] Figure 2 This is a flowchart illustrating the process for determining whether an operating condition falls under an accident, as provided in an embodiment of the present invention.

[0075] Figure 3 This is a flowchart of the processing of the fire and accident procedure interface of the present invention;

[0076] Figure 4 This is a schematic diagram of the structure of the nuclear power plant fire-induced operational event identification system provided in an embodiment of the present invention. Detailed Implementation

[0077] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0078] Based on the different consequences of a fire, this invention first identifies whether a fire should be included in the accident operation condition. For situations requiring accident operation, it achieves effective management of the fire under the accident operation condition through an interface between fire and accident procedures. For situations that do not lead to the accident operation condition, it sorts out the safety items damaged by the fire, assesses the impact on safety functions, identifies non-operable safety functions, and records the corresponding operational events. This achieves the goal of comprehensively identifying operational events caused by fire, providing an important basis for the effective and accurate management of fires in nuclear power plants, thereby ensuring the operational safety of nuclear power plants.

[0079] Specifically, such as Figure 1 As shown, in a preferred embodiment, the method for identifying operational events caused by a nuclear power plant fire includes the following steps:

[0080] Step S101: Obtain fire information from the nuclear power plant.

[0081] Specifically, in this embodiment of the invention, fire information at nuclear power plants can be obtained in various ways. For example, the methods of acquisition may include, but are not limited to: fire alarm signals issued by fire detection systems, eyewitness confirmation information from on-site inspection personnel, and on-site camera monitoring systems.

[0082] Step S102: Determine whether a fire is confirmed based on the fire information.

[0083] Optionally, in this embodiment of the invention, when a fire occurs, it is only considered a fire if the fire cannot be controlled; if the fire can be effectively controlled and the fire source is detected in time, the fire is not considered a fire. Generally, nuclear power plants conduct fire confirmation during fire response. Nuclear power plant fire response typically implements a multi-level intervention principle. For example, taking a nuclear power plant as an example, after a fire is discovered, the main control room operator immediately initiates a level-two fire intervention. If the level-two intervention confirms that the fire cannot be extinguished by existing means, the fire is determined to be a fire. Further, if the fire is not determined to be a fire, the site is inspected for fire damage, and step S105 is executed after the inspection is completed.

[0084] Step S103: If yes, determine whether the fire belongs to an accidental operating condition.

[0085] Specifically, the degree of impact of the fire on the unit's operation determines whether it falls under an accidental operating condition. If the unit's operating condition caused by the fire is relatively complex and cannot be managed using normal operating procedures within the normal operating range, or if there are significant difficulties in managing it within the normal operating range, and it is necessary to manage it using accident procedures, then the fire should be included in the accidental operating condition and managed using accident procedures.

[0086] In a preferred embodiment, such as Figure 2 As shown, the following methods can be used to determine whether a fire in a fire compartment constitutes an accident condition and to ascertain whether it is covered by accident procedures.

[0087] Specifically, determining whether a fire constitutes an accidental operating condition includes: determining whether the fire directly caused an accidental operating condition; if so, the fire is considered an accidental operating condition; if not, determining whether the fire caused an automatic shutdown; if so, the fire is considered an accidental operating condition; if not, determining whether the fire caused the loss of functionality of the nuclear steam supply system required for normal operation; if so, the fire is considered an accidental operating condition; if not, determining whether the fire caused the loss of functionality of important support systems; if so, the determination of whether the fire constitutes an accidental operating condition is based on feedback from the operating experience of similar units.

[0088] Among these, fire directly causing an accidental operating condition: If a fire directly causes an accidental operating condition, then the fire in that fire compartment needs to be included in the scope of accidental operation and covered by the accident procedures. For example, a fire directly damaging the valve body of the pressure regulator safety valve causes the pressure regulator safety valve to open erroneously, resulting in a pressure regulator safety valve jamming accident; a fire directly damaging the atmospheric release valve causes an accident similar to a small rupture in the main steam pipeline, etc.

[0089] Automatic reactor shutdown due to fire: If a fire in a fire compartment causes the reactor to shut down automatically, it means that the conditions for entering accident operation have been triggered and must be covered by accident procedures. For example, if a fire causes the pressurizer pressure regulation function to fail, the "low pressurizer pressure" or "high pressurizer pressure" signal will trigger an automatic reactor shutdown.

[0090] Fires that cause loss of nuclear steam supply system functions (NSSS functions) required for normal operation: NSSS functions required for normal operation are those required during normal unit shutdown, such as normal borosilicate and normal spraying functions. If these NSSS functions are lost, the unit will not be able to shut down normally and will need to be controlled by accident procedures. Therefore, fires in this situation also need to be covered by accident procedures.

[0091] Fire causing loss of critical support system functionality: If some critical support system functions are lost, it will indirectly lead to the inoperability of a large number of safety functions. In this situation, maintaining the normal operation of the unit is inappropriate. If a fire causes the loss of critical support system functionality, such as the loss of power to the medium-voltage emergency AC bus, then the fire in that fire compartment needs to be covered by the accident procedures.

[0092] Feedback from similar unit operating experiences necessitates consideration of accident scenarios: Feedback from the operating experiences of some similar units can serve as a basis for determining whether a fire should be covered by the accident procedures. For example, if a pressurized water reactor unit is found during normal operation to have significant difficulties in controlling the pressurizer water level due to the loss of the charging line, making it difficult to smoothly shut down the unit, then similarly, if a fire in a fire compartment results in the loss of the charging line, then the fire in that fire compartment can be covered by the accident procedures.

[0093] Step S104: If it is an accident operation condition, then manage the fire based on the accident operation condition management mode.

[0094] Specifically, for fires in fire compartments that need to be included in the accident operation condition management, the consequences of the fire will be managed with the help of accident procedures.

[0095] The fire management based on the accident operation condition management mode includes: determining the interface between the fire and the accident procedure, and managing the fire based on the interface between the fire and the accident procedure. Optionally, in this embodiment of the invention, the interface between the fire and the accident procedure includes: confirming the fire before entering the accident procedure and confirming the fire during the execution of the accident procedure.

[0096] In some embodiments, determining the interface of the fire and accident procedures and managing the fire based on the interface of the fire and accident procedures includes: if the interface of the fire and accident procedures is to confirm the fire before entering the accident procedures, then the following steps are performed: obtaining the initial status parameters of the unit; determining whether the status parameters of the unit are downgraded based on the initial status parameters; if yes, then handling the fire based on the accident condition; if no, then handling the fire based on the fault condition.

[0097] The fire handling based on accident conditions includes: processing the accident handling sequence based on the accident conditions; after the accident handling sequence is completed, performing fire monitoring; determining whether there is a loss of support function monitoring and / or nuclear steam supply system function monitoring based on the fire monitoring information; if so, re-diagnosing the unit status; determining whether the unit's status parameters have degraded based on the re-diagnosis results; if degraded, proceeding to the accident procedure handling sequence; if not degraded, returning to the steps of the accident handling sequence based on accident conditions. The fire handling based on fault conditions includes: processing the accident handling sequence based on the fault conditions; after the accident handling sequence is completed, performing fire monitoring; determining whether there is a loss of support function monitoring and / or nuclear steam supply system function monitoring based on the fire monitoring information; if so, performing re-diagnosis of the unit status; determining whether the unit's status parameters have degraded based on the re-diagnosis results; if degraded, proceeding to the accident procedure handling sequence; if not degraded, returning to the steps of obtaining the unit's initial status parameters.

[0098] Furthermore, determining the interface for fire and accident procedures, and managing fires based on this interface, also includes: if the interface for fire and accident procedures is that a fire is confirmed during the execution of accident procedures, then the following steps are performed: performing fire monitoring; determining whether nuclear steam supply system function monitoring is available based on the fire monitoring information; if so, re-diagnosing the unit status based on the fire monitoring information; determining whether the unit's status parameters have degraded based on the re-diagnosis results; if degraded, entering the accident procedure processing sequence; if not degraded, returning to the steps of the accident processing sequence based on the accident condition in the accident operating condition; or, if not degraded, returning to the steps of obtaining the unit's initial status parameters in the fault operating condition.

[0099] In a preferred embodiment, such as Figure 3 As shown, if the fire and accident procedure interface is as follows: before entering the accident procedure, if a fire is confirmed, the initial status parameters of the unit are first diagnosed. If the status parameters of the unit degrade, it indicates that a nuclear accident threatening reactor safety has occurred, and the accident handling sequence of AC condition (accident condition) is used. If the status parameters do not degrade, it indicates that the unit's safety level has not been severely degraded, and the accident handling sequence of IC condition (fault condition) is used. After the accident handling sequence is completed, fire monitoring continues, and based on the fire monitoring information obtained, the loss of support functions and NSSS functions are monitored to detect possible superimposed faults. Then, the unit status is re-diagnosed, and redirection is performed based on the re-diagnosed status results, i.e., as shown in the diagram. Figure 3 As shown.

[0100] If the fire and accident procedure interface is configured such that: during the execution of the accident procedure, if a fire is confirmed, fire monitoring is performed directly, and the bypass loses its supporting monitoring function; NSSS function monitoring is then performed directly, followed by a re-diagnosis of the unit's status, and redirection is performed based on the re-diagnosis results. Figure 3 As shown.

[0101] Optionally, in this embodiment of the invention, the fire and accident procedure interface is defined as follows:

[0102] A. If a fire is confirmed before entering the accident procedure, the fire shall be a condition for entering the accident procedure, and the accident procedure shall be entered after the fire is confirmed.

[0103] B. If a fire is confirmed during the execution of accident procedures, the fire shall be monitored by the fire monitoring department.

[0104] Once a fire is confirmed, the specific procedures will vary depending on the actual situation of the unit, as detailed below:

[0105] (1) If the fire is confirmed before entering the accident procedure, when performing the initial diagnosis of the unit status, it is necessary to consider the information required for performing the accident procedure affected by the fire, so as to guide the operator to select reliable information for unit status diagnosis. The information required for performing the accident procedure is the instrument parameter information used in the execution of the accident procedure, such as status function parameter information (such as pressure vessel water level, core outlet temperature, etc.).

[0106] (2) If a fire is confirmed within the IC operating range, in addition to considering the information required to execute the accident procedures affected by the fire, the necessary actions to limit the impact of the fire on the unit operation should also be considered, such as switching the affected functions to the standby column (e.g., if the fire causes the cooling water system of the equipment in column A to fail, it needs to be switched to the cooling water system of the equipment in column B), disconnecting the power supply of some important equipment to limit the consequences of the fire, etc.

[0107] (3) If a fire is confirmed within the AC condition, only the information required to implement the accident procedure affected by the fire should be considered. This is because, within the AC condition, ensuring core safety is the top priority. Keeping the affected process systems running instead of actively shutting them down is not advantageous for core safety, although it is disadvantageous from the perspective of equipment protection.

[0108] (4) If a fire is confirmed, the monitoring section that loses its support function will be bypassed during the execution of the accident procedures. This is because a fire may cause a large number of false alarm signals, such as falsely triggering some switchboard power failure alarms. If the operator mistakenly believes that the support function has been lost based on these false alarm signals, it may lead to the inappropriate shutdown of certain safety functions, which is detrimental to the safe operation of the unit. For example, the operator may mistakenly shut down the pumps, fans, heaters, etc. downstream of the switchboard due to a false switchboard power failure alarm, which will result in the loss of the corresponding NSSS function.

[0109] The information required for implementing accident procedures affected by the fire, and the necessary operations to limit the impact of the fire on unit operation, can preferably be presented in the form of a fire operation order. The fire operation order can be presented in various existing formats, and this invention does not limit the specific form.

[0110] Step S105: If it does not belong to the accident operation condition, then identify the operation event caused by the fire based on the damage to safety items caused by the fire.

[0111] Specifically, identifying fire-related operational events based on fire damage to safety items includes: acquiring damaged safety items; assessing the impact of damaged safety items on safety functions; determining whether a safety function is inoperable based on the impact on safety functions; if operable, returning to the step of acquiring damaged safety items; if inoperable, acquiring the unit's current operating mode and determining whether inoperable safety functions are required to operate under the current operating mode; if yes, recording operational events for inoperable safety functions; if no, returning to the step of acquiring damaged safety items.

[0112] The process of recording operational events for non-operable security functions includes: obtaining operational events corresponding to non-operable security functions; and obtaining and recording the measures and completion time corresponding to each operational event.

[0113] Specifically, by acquiring damaged safety items, a classification of these items can be achieved, and this classification provides a basis for assessing the impact of a fire on safety functions. Damaged safety items can be categorized based on the behavioral characteristics of equipment under fire conditions. Details are as follows:

[0114] Purely mechanical equipment: This includes containers, pipes, manual valves, electric valves, ventilation ducts, etc. These devices are generally kept in their pre-fire condition during a fire.

[0115] Mechanical and electrical equipment: This mainly includes electrically driven mechanical equipment such as fans and pumps. In the event of a fire, this type of equipment will generally experience performance degradation or cease operation entirely.

[0116] Electrical equipment includes cables, distribution panels, transformers, control cabinets, and electrical cabinets. These types of equipment often cause power outages in the event of a fire.

[0117] It should be noted that damaged safety items include not only equipment directly damaged by the fire, but also equipment indirectly caused to shut down. In particular, if the short-circuit current of a cable damaged by the fire exceeds the overcurrent protection threshold of the distribution panel itself, the tripping of the distribution panel will cause all downstream loads to be affected, and these downstream loads will also be taken into account.

[0118] The impact of damaged safety items on safety functions is assessed as follows: The realization of a safety function requires the coordination of process equipment such as pumps and valves, as well as corresponding control logic. If a fire affects one or more of these devices, the fire will affect that safety function. Table 1 illustrates this using the high-pressure safety injection function and the residual heat removal system of a nuclear power plant as examples.

[0119]

[0120]

[0121] Table 1

[0122] For the identified damaged safety items, it is generally impossible to determine whether the corresponding safety functions can still perform their intended functions. In the event of a fire, the operability of safety functions can be assessed based on their operational status, evaluating the impact of the fire on those functions. Specifically:

[0123] If the safety function is in operation, the performance of the safety function is determined based on the safety items damaged by the fire. For example, if the high-pressure safety injection is in operation, and the fire directly causes damage to the waste heat discharge pump, it may lead to a decrease in the pump's output, resulting in a decrease in the flow rate of the waste heat discharge system and making it unable to perform its intended safety function. In this case, the safety function is considered to be inoperable.

[0124] If the safety function is not operational, its operational capability is determined by the visible damage caused by the fire to the safety system equipment or the structure containing the equipment. For example, if the high-pressure safety injection pump was not operational during operation and the fire occurred directly in the area where the high-pressure safety injection pump is located, then the safety function can be considered inoperable.

[0125] If the safety function is determined to be operational, proceed to the analysis of the impact of the next damaged safety item on the safety function. If the safety function is determined to be inoperable, record the operational events in accordance with the technical specifications and technical requirements manual.

[0126] For each safety function, its operability is not required in all operating modes. As an example, the table below shows the applicable operating modes for high-pressure injection and waste heat removal systems. The purpose of operating mode determination is to provide input for determining whether the current operating mode requires the operation of that safety function.

[0127] Security features Operating mode High pressure injection 1、2、3、4 Waste heat removal system 4、5、6

[0128] Table 2 Applicable Operating Modes for High-Pressure Injection and Waste Heat Removal Systems

[0129] The determination of the operating mode is based on physical parameters such as core reactivity, unit thermal power, and average reactor coolant temperature. Table 3 shows the typical methods for classifying the operating modes of nuclear power plants.

[0130]

[0131] Table 3 Typical Classification of Nuclear Power Plant Operation Modes

[0132] If the current operating mode requires the security function to be operational, the operating restrictions for the security function will be defined in the technical specifications or technical requirements manual. If one or more security functions are not operational, the event corresponding to the operating restriction will be triggered.

[0133] In the operational constraints, the number of non-operable safety functions corresponds to different events. Here, the events are recorded according to the number of non-operable safety functions. As an example, Table 4 shows some of the events defined in the operational constraints of a typical safety function (emergency borosilicate).

[0134]

[0135] Table 4. Events corresponding to the inability of security functions to operate.

[0136] The operational constraints specify the required actions and completion times for each event, which are recorded here. The required actions define the actions that need to be taken to ensure unit safety is not degraded in response to a safety function inoperability event, and the completion time is the total time allowed to complete one of the required actions.

[0137] refer to Figure 4 The present invention provides a system for identifying operational events caused by fires in nuclear power plants. This system can identify operational events caused by fires based on the method for identifying operational events caused by fires disclosed in the embodiments of the present invention.

[0138] Specifically, such as Figure 4 As shown, the identification system for operational events caused by a fire at the nuclear power plant includes:

[0139] Acquisition unit 401 is used to acquire fire information from nuclear power plants.

[0140] Fire confirmation unit 402 is used to determine whether a fire is confirmed based on fire information.

[0141] The judgment unit 403 is used to determine whether the fire belongs to the accident operation condition when a fire is confirmed to have occurred.

[0142] The accident operation management unit 404 is used to manage the fire based on the accident operation condition management mode when the fire is in an accident operation condition.

[0143] The identification unit 405 is used to identify the operating event caused by the fire based on the damage to safety items caused by the fire if the fire is not an accident operating condition.

[0144] This invention discloses a method and system for identifying operational events caused by fires in nuclear power plants. Based on the different consequences of the fire, it first identifies whether the fire should be included in the accident operation condition. For situations requiring accident operation, it achieves effective fire management under accident operation conditions by defining the interface and execution method between the fire and accident procedures. For situations that do not lead to accident operation conditions, it reviews the safety items damaged by the fire, assesses the impact on safety functions, identifies inoperable safety functions, and records the corresponding operational events. This achieves the goal of comprehensively identifying operational events caused by fires, providing an important basis for effective and accurate management of nuclear power plant fires, thereby ensuring the operational safety of nuclear power plants.

[0145] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0146] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0147] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0148] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They do not limit the scope of protection of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for identifying operational events caused by a fire in a nuclear power plant, characterized in that, Includes the following steps: S101. Obtain fire information from nuclear power plants; S102. Determine whether a fire is confirmed based on the fire information; S103. If so, determine whether the fire falls under an accident-related operating condition, specifically including: Determine whether the fire directly caused the accident. If so, the fire is determined to be an accidental operating condition; If not, determine whether the fire caused the automatic shutdown of the reactor. If the fire leads to automatic shutdown, it is determined to be an accidental operating condition. If the fire does not lead to an automatic shutdown, determine whether the fire has caused the loss of the nuclear steam supply system required for normal operation. If the fire causes the nuclear steam supply system to lose its function, it is determined to be an accidental operating condition. If the fire did not cause the nuclear steam supply system to lose its function, then determine whether the fire caused the loss of function of an important support system. If the fire results in the loss of important support system functions, the judgment on whether the fire constitutes an accidental operating condition will be made based on feedback from the operating experience of similar units. S104. If the operation is under an accident-prone condition, the fire shall be managed based on the accident-prone condition management mode. S105. If the operating condition is not an accident-related condition, the fire-related operational event is identified based on the damage to safety items caused by the fire, specifically including: Retrieve damaged security items; Assess the impact on safety functions based on the damaged safety items; Based on the impact of the security function, determine whether the security function is inoperable; If it can be run, return to the step of retrieving the damaged security item; If it is not operable, obtain the current operating mode of the unit and determine whether the safety function that is not operable is required to be operable under the current operating mode; If so, then the running events of the aforementioned non-operable security functions will be logged; If not, return to the step of retrieving the damaged security item.

2. The method for identifying operational events caused by nuclear power plant fires according to claim 1, characterized in that, The fire management based on the accident operation condition management mode includes: Define the interface for fire and accident procedures, and manage fires based on the interface for fire and accident procedures.

3. The method for identifying operational events caused by nuclear power plant fires according to claim 2, characterized in that, The interfaces for the fire and accident procedures include: confirming a fire before entering the accident procedures and confirming a fire during the execution of the accident procedures; The interface for determining fire and accident procedures, and the management of fires based on the interface for fire and accident procedures, include: If the interface between the fire and accident procedures is to confirm the fire before entering the accident procedures, then the following steps are performed: Obtain the initial status parameters of the unit; Determine whether the unit's status parameters have degraded based on the initial status parameters; If so, the fire should be handled based on the accident conditions. If not, the fire will be handled based on the fault condition.

4. The method for identifying operational events caused by nuclear power plant fires according to claim 3, characterized in that, The fire handling based on accident conditions includes: Accident handling sequence processing based on accident conditions; Fire monitoring is performed after the incident handling sequence is completed; Determine whether there is a loss of support function monitoring and / or nuclear steam supply system function monitoring based on fire monitoring information; If so, then the unit status should be re-diagnosed; Determine whether the unit's status parameters have been downgraded based on the re-diagnosis results; If downgraded, it will enter the accident procedure handling sequence; If no downgrade is performed, the process returns to the steps of the accident handling sequence based on the accident condition.

5. The method for identifying operational events caused by nuclear power plant fires according to claim 3, characterized in that, The fire handling based on fault conditions includes: Accident handling sequence processing based on fault conditions; Fire monitoring is performed after the incident handling sequence is completed; Determine whether the monitoring function supporting the nuclear steam supply system has been lost based on fire monitoring information; If so, then the unit status should be re-diagnosed; Determine whether the unit's status parameters have been downgraded based on the re-diagnosis results; If downgraded, it will enter the accident procedure handling sequence; If no downgrade is performed, return to the step of obtaining the initial state parameters of the unit.

6. The method for identifying operational events caused by nuclear power plant fires according to claim 5, characterized in that, The interface for determining fire and accident procedures, and the management of fires based on the interface for fire and accident procedures, further include: If the interface between the fire and accident procedures is that a fire is confirmed during the execution of the accident procedures, then the following steps are performed: Perform fire monitoring; Determine whether the system has nuclear steam supply system monitoring capabilities based on fire monitoring information; If so, the unit status will be re-diagnosed based on the fire monitoring information. Determine whether the unit's status parameters have been downgraded based on the re-diagnosis results; If downgraded, it will enter the accident procedure handling sequence; If no downgrade occurs, the procedure returns to the steps of the accident handling sequence based on the accident condition in the accident condition; or, if no downgrade occurs, the procedure returns to the steps of obtaining the initial state parameters of the unit in the fault condition.

7. The method for identifying operational events caused by nuclear power plant fires according to claim 1, characterized in that, The logging of operational events for the non-operable security function includes: Based on the non-operable security function, obtain the operating event corresponding to the non-operable security function; Obtain and record the measures and completion time corresponding to each running event.

8. A system for identifying operational events caused by a fire in a nuclear power plant, characterized in that, include: The acquisition unit is used to acquire fire information from nuclear power plants. The fire confirmation unit is used to determine whether a fire is confirmed based on the fire information. The judgment unit is used to determine whether a fire constitutes an accidental operating condition when a fire is confirmed to have occurred. Specifically, it includes: Determine whether the fire directly caused the accident. If so, the fire is determined to be an accidental operating condition; If not, determine whether the fire caused the automatic shutdown of the reactor. If the fire leads to automatic shutdown, it is determined to be an accidental operating condition. If the fire does not lead to an automatic shutdown, determine whether the fire has caused the loss of the nuclear steam supply system required for normal operation. If the fire causes the nuclear steam supply system to lose its function, it is determined to be an accidental operating condition. If the fire did not cause the nuclear steam supply system to lose its function, then determine whether the fire caused the loss of function of an important support system. If the fire results in the loss of important support system functions, the judgment on whether the fire constitutes an accidental operating condition will be made based on feedback from the operating experience of similar units. The accident operation management unit is used to manage fires based on the accident operation condition management mode when the fire is in an accident operation condition. The identification unit is used to identify fire-related operational events based on the damage caused by the fire to safety items, when the fire is not considered an accidental operating condition. Specifically, this includes: Retrieve damaged security items; Assess the impact on safety functions based on the damaged safety items; Based on the impact of the security function, determine whether the security function is inoperable; If it can be run, return to the step of retrieving the damaged security item; If it is not operable, obtain the current operating mode of the unit and determine whether the safety function that is not operable is required to be operable under the current operating mode; If so, then the running events of the aforementioned non-operable security functions will be logged; If not, return to the step of retrieving the damaged security item.

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