A method and system for disaster superposition analysis of a nuclear power plant

Abstract

This invention relates to a method and system for disaster overlay analysis in nuclear power plants, comprising the following steps: acquiring standard specifications and experience feedback data of the nuclear power plant; conducting preliminary screening analysis based on the standard specifications, experience feedback data, and screening criteria to obtain a preliminary screening list of disaster overlays; and conducting secondary analysis based on the preliminary screening list of disaster overlays and in conjunction with a list of overlay disaster analysis scopes to obtain a disaster overlay list. This invention, through preliminary screening analysis, obtains a preliminary screening list of disaster overlays, achieving a comprehensive and effective review of possible disaster overlay types and avoiding omissions; simultaneously, through secondary analysis, it achieves a comprehensive and effective review and determination of the disaster overlay types that need to be considered, further ensuring the comprehensiveness and effectiveness of the disaster overlay analysis and avoiding omissions.

Description

Technical Field

[0001] This invention relates to the technical field of disaster analysis in nuclear power plants, and more specifically, to a method and system for superimposed disaster analysis in nuclear power plants. Background Technology

[0002] In the design of nuclear power plants, effective protection is generally provided for individual disasters and corresponding mitigation measures are taken according to the consequences. However, in reality, some disasters may be accompanied by or cause other disasters when they occur. This is called disaster superposition. The consequences of disaster superposition may render the protective measures for individual disasters ineffective, thereby affecting reactor safety.

[0003] Currently, the analysis methods for the superposition of disasters at nuclear power plants mainly refer to the scenarios specified in regulations and standards, such as earthquakes causing fires, fires causing explosions, etc., or are based on the types of disaster superposition caused by experience feedback, such as extreme rainfall causing external water sources. However, existing solutions mainly list the main types of disaster superposition based on regulations, standards, and experience feedback. This approach is not comprehensive enough, which can lead to omissions, and it lacks a systematic analysis process. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method and system for disaster superposition analysis of nuclear power plants.

[0005] The technical solution adopted by this invention to solve its technical problem is: constructing a disaster superposition analysis method for nuclear power plants, including the following steps:

[0006] Obtain standard specifications and experience feedback data from nuclear power plants;

[0007] Based on the aforementioned standards and specifications, the aforementioned experience feedback data, and the screening criteria, a preliminary screening analysis was conducted to obtain a preliminary screening list of disaster superposition.

[0008] Based on the preliminary screening list of disaster superposition and combined with the list of superposition disaster analysis scope, a secondary analysis is performed to obtain the disaster superposition list.

[0009] In the hazard superposition analysis method for nuclear power plants described in this invention, the preliminary screening analysis based on the standard specifications, the experience feedback data, and the screening criteria to obtain a preliminary screening list of hazard superposition includes:

[0010] The analysis is performed based on the aforementioned standards and specifications and the aforementioned experience feedback data, and the results are used to determine whether the disaster combination to be analyzed is a superimposed disaster in the aforementioned standards and specifications or a superimposed disaster in the aforementioned experience feedback data.

[0011] If so, the disaster combination to be analyzed is determined as a reliable superimposed disaster combination;

[0012] If not, then determine whether the disaster combination to be analyzed will theoretically overlap;

[0013] If the disaster combination to be analyzed is theoretically superimposed, then determine whether the disaster combination to be analyzed has been excluded by existing design measures;

[0014] If the disaster combination to be analyzed is not excluded by existing design measures, then determine whether there are management measures to mitigate or eliminate the occurrence of the disaster combination to be analyzed;

[0015] If there are no management measures to mitigate or eliminate the occurrence of the disaster combination to be analyzed, then determine whether the probability of the occurrence of the disaster combination to be analyzed is less than the set probability;

[0016] If the probability of the disaster combination to be analyzed occurring is greater than the set probability, then the combination is determined to be a credible superimposed disaster combination.

[0017] Based on the credible combinations of superimposed disasters and the combinations of superimposed disasters caused by external disasters, a preliminary screening list of the superimposed disasters is formed.

[0018] In the disaster superposition analysis method for nuclear power plants described in this invention, the method further includes:

[0019] Obtain information on all structures within a nuclear power plant;

[0020] Based on the information of each structure, determine whether the sub-item has a system or component that performs a safe shutdown function; the sub-item refers to the structure of the nuclear power plant;

[0021] If so, the current factory building will be identified as a factory building that needs to be considered for superimposed disasters;

[0022] The list of superimposed disaster analysis scopes is formed based on the identified factory buildings that require consideration of superimposed disasters.

[0023] In the hazard superposition analysis method for nuclear power plants described in this invention, the secondary analysis based on the preliminary screening list of hazard superposition and combined with the list of superposition hazard analysis scope to obtain the hazard superposition list includes:

[0024] Based on the preliminary screening list of disaster superpositions, all credible combinations of superposition disasters are obtained;

[0025] Perform the following analysis for each credible combination of superimposed hazards:

[0026] Perform system-level filtering;

[0027] After completing the system-level screening, the list of superimposed disaster analysis scopes is combined with the credible superimposed disaster combinations to be analyzed, and sub-item-level screening is performed.

[0028] After completing the sub-item-level screening, perform specific scenario function analysis;

[0029] Based on the analysis results of each credible superimposed disaster combination and the analysis results of superimposed disaster combinations caused by external disasters, the disaster superposition list is obtained.

[0030] In the disaster superposition analysis method for nuclear power plants described in this invention, the system-level screening includes:

[0031] A method for determining whether the conditions are met; the method for meeting the conditions is: a method that is related to the disaster superposition phenomenon of the credible superposition disaster combination to be analyzed and makes the consequences of the credible superposition disaster combination to be analyzed within an acceptable range;

[0032] If no method satisfies the conditions, then determine whether the credible superimposed disaster combination to be analyzed meets the consideration conditions; the consideration conditions are: the disaster consequences generated by the credible superimposed disaster combination to be analyzed already include any one of the disasters in the credible superimposed disaster combination to be analyzed; or the disaster consequences generated by the credible superimposed disaster combination to be analyzed are less than the disaster consequences generated by any one of the disasters in the credible superimposed disaster combination to be analyzed.

[0033] If the consideration criteria are not met, then sub-item-level filtering will be performed.

[0034] In the nuclear power plant disaster overlay analysis method described in this invention, the step of combining the list of overlay disaster analysis scopes with the credible combinations of overlay disasters to be analyzed, and performing sub-item-level screening, includes:

[0035] All sub-items within the scope of the superimposed disaster analysis are obtained based on the list of superimposed disaster analysis scopes;

[0036] Each sub-item is combined with a credible combination of superimposed disasters to be analyzed, and the following analysis is performed:

[0037] Determine whether the sub-item to be analyzed can withstand any one of the credible superimposed disasters to be analyzed;

[0038] If not, then determine whether the sub-item to be analyzed has a disaster source corresponding to the credible superimposed disaster to be analyzed;

[0039] If there is a disaster source corresponding to the credible superimposed disaster to be analyzed, then determine whether the layout of the sub-item to be analyzed or the system design of the sub-item to be analyzed can prevent the occurrence of the credible superimposed disaster to be analyzed.

[0040] If the occurrence of the credible superimposed disaster to be analyzed cannot be avoided, then determine whether the sub-item to be analyzed has backup measures or mitigation measures;

[0041] If there are no alternative or mitigation measures, then a secondary classification list will be used;

[0042] Based on the aforementioned secondary classification list, specific scenario functional analysis is performed in conjunction with the superimposed disaster combinations caused by external disasters.

[0043] In the disaster superposition analysis method for nuclear power plants described in this invention, the step of performing specific scenario functional analysis based on the secondary classification list and combined with the superposition disaster combination caused by the external disaster includes:

[0044] Based on the preliminary screening list of superimposed disasters, the superimposed disaster combinations caused by the external disasters are obtained;

[0045] Based on the secondary classification list, a functional analysis is performed in conjunction with the superimposed disaster combinations caused by the external disasters.

[0046] Based on the functional analysis results, the impact of superimposed disaster combinations caused by external disasters on safety items is assessed.

[0047] In the disaster superposition analysis method for nuclear power plants described in this invention, the step of judging the impact of superimposed disaster combinations caused by external disasters on safety items based on functional analysis results includes:

[0048] The impact of the superimposed disaster combination caused by the external disaster on the safety item is judged based on the start time of the credible external disaster, the duration of the credible external disaster, and the consequences of the credible external disaster on the loss of external power and / or the loss of the final heat sink.

[0049] If unacceptable, output the corresponding reliable combination of superimposed disasters.

[0050] In the disaster superposition analysis method for nuclear power plants described in this invention, the method further includes:

[0051] Based on the aforementioned list of overlapping disasters, identify credible overlapping disasters that could lead to unacceptable consequences;

[0052] Risk mitigation is carried out for credible superimposed disasters that could lead to unacceptable consequences.

[0053] This invention also provides a disaster superposition analysis system for nuclear power plants, comprising:

[0054] The acquisition unit is used to acquire standard specifications and experience feedback data from nuclear power plants.

[0055] The preliminary screening and analysis unit is used to perform preliminary screening and analysis based on the aforementioned standards and specifications, the aforementioned experience feedback data, and the screening criteria to obtain a preliminary screening list of disaster superposition.

[0056] The secondary screening and analysis unit is used to perform secondary analysis based on the preliminary screening list of disaster superposition and the list of superposition disaster analysis scope to obtain the disaster superposition list.

[0057] The method and system for disaster superposition analysis in nuclear power plants, as described in this invention, have the following beneficial effects: The method includes the following steps: acquiring standard specifications and experience feedback data for nuclear power plants; conducting preliminary screening analysis based on the standard specifications and experience feedback data to obtain a preliminary screening list of disaster superpositions; and conducting secondary analysis based on the preliminary screening list of disaster superpositions and a list of superposition disaster analysis scopes to obtain a disaster superposition list. This invention, through preliminary screening analysis, obtains a preliminary screening list of disaster superpositions, achieving a comprehensive and effective review of possible disaster superposition types and avoiding omissions. Simultaneously, through secondary analysis, it achieves a comprehensive and effective review and determination of the disaster superposition types that need to be considered, further ensuring the comprehensiveness and effectiveness of the disaster superposition analysis and avoiding omissions. Attached Figure Description

[0058] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0059] Figure 1 This is a flowchart illustrating the disaster superposition analysis method for nuclear power plants provided by the present invention;

[0060] Figure 2 This is a flowchart of the preliminary screening and analysis process for disaster superposition provided by the present invention;

[0061] Figure 3 This is a flowchart illustrating the determination of the scope of superimposed disaster analysis provided by the present invention;

[0062] Figure 4 This is a flowchart of the secondary analysis of disaster superposition provided by the present invention;

[0063] Figure 5 This is a detailed screening and analysis flowchart for each credible superimposed disaster combination provided by the present invention. Detailed Implementation

[0064] 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.

[0065] Figure 1The present invention illustrates the specific analysis process of the disaster superposition analysis method for nuclear power plants provided by this invention. This method outlines the analytical framework and process for disaster superposition in nuclear power plants, gradually narrowing down the scope of disaster superposition considerations through qualitative and quantitative judgments. It effectively determines the list of disaster superpositions to be considered, effectively avoiding omissions and ensuring the comprehensiveness of the disaster superposition analysis.

[0066] Specifically, such as Figure 1 As shown, in this embodiment, the disaster superposition analysis method for the nuclear power plant includes the following steps:

[0067] Step S10: Obtain standard specifications and experience feedback data from nuclear power plants.

[0068] Specifically, in this embodiment, the standard specifications and experience feedback data of nuclear power plants can be obtained using any existing method, and this invention does not impose any specific limitations. The standard specifications of nuclear power plants mainly refer to the regulations and standards governing nuclear power plants, which specify the types of disaster superposition, such as earthquakes causing fires, fires causing explosions, etc. Similarly, the experience feedback data also reflects the types of disaster superposition, such as extreme rainfall causing external flooding, etc.

[0069] Step S20: Conduct preliminary screening analysis based on standards, experience feedback data, and screening criteria to obtain a preliminary screening list of disaster superposition.

[0070] Specifically, in this embodiment, since the regulations and standards for nuclear power plants specify the types of disaster superposition, and the experience feedback data also reflects the types of disaster superposition, we can analyze the regulations and standards for nuclear power plants and / or experience feedback data to obtain the corresponding credible combinations of superposition disasters. Then, we can further analyze them through the corresponding rules to finally obtain a preliminary screening list.

[0071] Specifically, in this embodiment, disaster superposition can be divided into the following four categories:

[0072] The first category is the superposition of independent disasters, which refers to the simultaneous occurrence of unrelated disasters. For example, a fire occurs inside a factory building while a natural disaster occurs outside the factory building.

[0073] The second category is the superposition of related disasters, which refers to disasters occurring simultaneously under the same circumstances. For example, in extreme weather conditions, storms and lightning may occur at the same time. The concept of related disasters is mainly applied to natural disasters, as multiple disasters typically occur simultaneously during natural disasters.

[0074] The third category is the superposition of secondary disasters. Secondary disasters refer to the possibility that the occurrence of one disaster may trigger another disaster, i.e., the secondary effect of a disaster. For example, a projectile hitting a water storage tank may cause the tank to rupture, resulting in flooding.

[0075] The fourth category, which also needs to be considered in secondary disasters, is the superposition of external disasters and / or loss of off-site power (LOOP) and loss of ultimate heat sink (LUHS). Specifically, the global effects of an external disaster may lead to LOOP and / or LUHS, while the safety requirements of internal disasters can ensure that these two types of secondary effects will not occur. In some cases, the initial disaster does not directly cause LOOP and / or LUHS, but is caused by secondary disasters. For example, extreme cold air can cause frost and floating ice in water, thereby jeopardizing the operational safety of off-site power facilities and heat sinks, and may lead to LOOP and LUHS.

[0076] It should be noted that among the four types of disasters mentioned above, the superposition of independent disasters is less frequent, as the frequency of a single disaster is generally around 10. -4 The magnitude is so low that the overall superposition frequency will be very low, which can be filtered out. In actual operation, it is also very rare for independent disasters that are not related to each other to occur simultaneously in a certain safe area.

[0077] Specifically, in this embodiment, as follows: Figure 2 As shown, based on standards, feedback data, and screening criteria, a preliminary screening analysis was conducted to obtain a preliminary list of disaster superposition scenarios, including:

[0078] Step S201: Analyze the disaster combination to be analyzed based on the standard specifications and experience feedback data, and determine whether the disaster combination to be analyzed is a superimposed disaster in the standard specifications or a superimposed disaster in the experience feedback data based on the analysis results; if so, proceed to step S206.

[0079] Specifically, in this step, whether it is a disaster superposition type in the standard specifications or comes from experience feedback can be determined by sorting out the provisions on disaster superposition in the relevant design standards and specifications and referring to experience feedback in power plant review or operation. For example, a certain standard specification indicates that the superposition of snow and wind needs to be considered; while in the case of an earthquake, it may cause the non-seismic water system to rupture, thereby causing flooding effect.

[0080] Step S202: If not, determine whether the disaster combination to be analyzed will theoretically overlap.

[0081] Specifically, in this step, the possibility of overlapping disasters can theoretically be ruled out for unrelated or non-secondary disasters. However, it is important to distinguish the possible sequential overlapping relationships among secondary disasters. For example, a fire does not necessarily trigger an earthquake, but an earthquake may trigger a fire. It should be noted that related natural disasters require specific analysis using meteorological knowledge, because not all weather conditions will result in several natural disasters occurring simultaneously. This only happens during extreme weather events, and factors such as season and air pressure need to be considered.

[0082] Step S203: If the disaster combination to be analyzed is theoretically superimposed, then determine whether the disaster combination to be analyzed has been excluded by existing design measures.

[0083] Specifically, this step requires considering whether the existing design has already taken into account or excluded the impact of overlapping disasters. This may include: source elimination, design measures, etc. For example, an earthquake may cause an external explosion, but the site selection stage already considers that the site should be far away from facilities with explosion risks and roads transporting explosive materials.

[0084] Step S204: If the disaster combination to be analyzed has not been excluded by existing design measures, then determine whether there are management measures to mitigate or eliminate the occurrence of the disaster combination to be analyzed.

[0085] Specifically, this step requires considering whether existing power plant management measures can mitigate or eliminate the possibility of a disaster. For example, on-site vehicle transport may cause a collision with a safe building, but existing management measures, such as limiting vehicle speed and controlling the amount of hazardous materials loaded, can eliminate or significantly reduce the probability of secondary disasters.

[0086] Step S205: If there are no management measures to mitigate or eliminate the occurrence of the disaster combination to be analyzed, determine whether the probability of the occurrence of the disaster combination to be analyzed is less than the set probability; if the probability of the occurrence of the disaster combination to be analyzed is greater than the set probability, then proceed to step S206.

[0087] Specifically, this step requires considering whether the probability of a theoretically feasible disaster superposition is very low. If the probability of the initial disaster is already very low, the probability of a secondary disaster is also unlikely to occur, then the probability of such a disaster superposition is very low and can be screened out. Or, the probability of causing serious consequences is low. For example, the probability of a heavy object falling is very low due to design and control measures. Even if it does occur, the probability of secondary effects such as fires and explosions is even lower. If the probability of causing serious consequences is also considered, the overall probability level will be kept at a very low level so that the risk is acceptable.

[0088] Step S206: Determine the disaster combination to be analyzed as a reliable superimposed disaster combination.

[0089] Step S207: Based on credible combinations of superimposed disasters and combinations of superimposed disasters caused by external disasters, a preliminary screening list of disaster superpositions is formed.

[0090] It should be noted that the factors to be considered in steps S202 to S205 are the screening criteria.

[0091] The combination of superimposed disasters caused by external disasters involves analyzing the probability of each external disaster causing a loop and / or LUHS, thus obtaining the combination of superimposed disasters caused by external disasters. The reliability of each external disaster causing a loop and / or LUHS needs to be considered in the credible superimposed scenario, including the start time and duration of the external disaster and its direct impact on the loop and / or LUHS. The impact and consequences on safe items are analyzed, and finally, based on the impact and consequences (e.g., if the impact and consequences exceed acceptable impact and consequences), it is included in the combination of superimposed disasters caused by external disasters.

[0092] In this embodiment, a disaster overlay matrix (i.e., a preliminary screening list, as shown in Table 1) is first established based on the existing internal and external disaster lists to conduct preliminary analysis and determine possible combinations of non-independent disasters and secondary disasters. In Table 1, the horizontal axis represents various forms of internal and external disasters, and the vertical axis represents related or secondary disasters. If the analysis determines that a disaster is not related or is not secondary, an "×" can be marked in Table 1, and the reason for exclusion needs to be recorded. If there is still a possibility of overlay after the analysis and exclusion, a "√" can be marked in the corresponding cell.

[0093] Table 1 Preliminary Screening and Analysis of Disaster Overlap

[0094]

[0095] After filtering according to the above rules, a matrix table of associated and secondary disasters is formed, as shown in Table 1. Table 1 lists the possible disaster superposition types and the disaster superpositions that have been filtered out. It should be noted that during the initial screening and analysis process, some combinations that are difficult to qualitatively exclude at the current design stage may occur. In such cases, it is necessary to make full use of the engineers' experience and judgment and expert meetings for screening. For those cases that are still possible, they should be retained in the superposition list for detailed verification and analysis in the subsequent design stage.

[0096] Step S30: Based on the preliminary screening list of disaster superposition, and combined with the list of superposition disaster analysis scope, a secondary analysis is performed to obtain the disaster superposition list.

[0097] Specifically, in this embodiment, as follows: Figure 3 As shown, the list of overlay disaster analysis scopes can be obtained through the following steps:

[0098] Step S301: Obtain information on all structures within the nuclear power plant.

[0099] Step S302: Determine whether the sub-item has a system or component capable of performing a safe shutdown function based on the information of each structure. The sub-item refers to the structures of the nuclear power plant, i.e., the plant buildings.

[0100] Step S303: If so, then the current factory building is identified as a factory building that needs to be considered for superimposed disasters.

[0101] Step S304: Based on the identified factory buildings that require consideration of superimposed disasters, form a list of superimposed disaster analysis scopes.

[0102] Specifically, in nuclear power plant disaster analysis, the protection objective for both external and internal disasters is to ensure the reactor's safe shutdown capability (reactivity control, residual heat removal, and containment of radioactive materials; items performing these functions are considered safety items). Therefore, protection against superimposed disasters is based on the same objective. According to this objective, the systems, components, and structures responsible for achieving and maintaining a safe shutdown state are within the scope of consideration for superimposed disasters. Systems lacking such items and radioactive containment functions, however, are excluded from this scope. Specific determination methods are as follows... Figure 3 As shown, the first step is to check whether there are any systems or components in the plant structure (referred to as "sub-items") that perform safe shutdown functions (or whether there is radioactivity in the system / component). If either of these is present, the plant structure falls within the scope of the superimposed hazards that need to be considered. Finally, a list of superimposed hazard analysis scopes is obtained based on the judgment results of all sub-items.

[0103] Specifically, in this embodiment, as follows: Figure 4 As shown, based on the initial screening list of disaster overlays and combined with the list of overlay disaster analysis scopes, a secondary analysis was conducted to obtain the disaster overlay list, which includes:

[0104] Step S401: Obtain all credible combinations of superimposed disasters based on the preliminary screening list of disaster superposition; perform the following analysis for each credible combination of superimposed disasters:

[0105] Step S402: Perform system-level filtering.

[0106] The system-level screening process includes: determining whether a method meets the criteria; a method that meets the criteria is one that is related to the disaster superposition phenomenon of the credible superposition disaster combination to be analyzed and makes the consequences of the credible superposition disaster combination to be analyzed within an acceptable range; if no method meets the criteria, then determining whether the credible superposition disaster combination to be analyzed meets the consideration criteria; the consideration criteria are: the disaster consequences generated by the credible superposition disaster combination to be analyzed already include any one of the disasters in the credible superposition disaster combination to be analyzed; or the disaster consequences generated by the credible superposition disaster combination to be analyzed are less than the disaster consequences generated by any one of the disasters in the credible superposition disaster combination to be analyzed; if the consideration criteria are not met, then sub-item-level screening is performed.

[0107] Step S403: After completing the system-level screening, combine the list of superimposed disaster analysis scopes with the credible superimposed disaster combinations to be analyzed, and perform sub-item-level screening.

[0108] The analysis combines the list of superimposed disaster analysis scopes with the credible combinations of superimposed disasters to be analyzed, and performs sub-item-level screening, including: obtaining all sub-items within the scope of superimposed disaster analysis based on the list of superimposed disaster analysis scopes; combining each sub-item with the credible combinations of superimposed disasters to be analyzed, and performing the following analyses: determining whether the sub-item to be analyzed can withstand any one of the credible superimposed disasters to be analyzed; if not, determining whether the sub-item to be analyzed has a disaster source corresponding to the credible superimposed disaster to be analyzed; if a disaster source corresponding to the credible superimposed disaster to be analyzed exists, determining whether the layout or system design of the sub-item to be analyzed can avoid the occurrence of the credible superimposed disaster to be analyzed; if the occurrence of the credible superimposed disaster to be analyzed cannot be avoided, determining whether the sub-item to be analyzed has backup measures or mitigation measures; if there are no backup measures or mitigation measures, a secondary classification list is established; based on the secondary classification list, specific scenario functional analysis is performed in conjunction with the superimposed disaster combinations caused by external disasters.

[0109] The specific scenario functional analysis based on the secondary classification list and combined with the superimposed disaster combinations caused by external disasters includes: obtaining the superimposed disaster combinations caused by external disasters based on the preliminary screening list of disaster superposition; conducting functional analysis based on the secondary classification list and combined with the superimposed disaster combinations caused by external disasters; and judging the impact of the superimposed disaster combinations caused by external disasters on safety items based on the results of the functional analysis.

[0110] In this embodiment, the assessment of the impact of the superimposed disaster combination caused by external disasters on safety items based on the functional analysis results includes: determining whether the impact of the superimposed disaster combination caused by external disasters on safety items is acceptable based on the start time of the credible external disaster, the duration of the credible external disaster, and the consequences of the credible external disaster on the loss of external power and / or the loss of the final heat sink; if it is unacceptable, the corresponding credible superimposed disaster combination is output.

[0111] Step S404: After completing the sub-item-level screening, perform specific scenario function analysis.

[0112] Step S405: Based on the analysis results of each credible superimposed disaster combination and the analysis results of superimposed disaster combinations caused by external disasters, obtain a disaster superposition list.

[0113] Furthermore, in this embodiment, the disaster superposition analysis method for the nuclear power plant also includes: determining credible superposition disasters that will produce unacceptable consequences based on the disaster superposition list; and performing risk elimination on the credible superposition disasters that will produce unacceptable consequences.

[0114] Specifically, when the design reaches the detailed design stage, corresponding protective measures are already in place for individual disasters. Based on this, the credible combinations of superimposed disasters in Table 1 can be screened and analyzed one by one from the following three levels. For example... Figure 5 As shown:

[0115] The first level: system-level screening.

[0116] This level focuses primarily on the characteristics of individual disasters, as these may have already been considered in the protection design for individual disasters.

[0117] First, factors such as the material layout of the system, components, and the plant itself can prevent one of the superimposed disasters from harming safe items. For example, the plant slopes used to mitigate external flooding and the plant drainage system will not be damaged even if struck by lightning, and the plant's wastewater system is made of non-metallic materials and will not be affected by lightning.

[0118] Secondly, the consequences of superimposed disasters are already included in the consideration of individual disasters, and may even be no greater than the consequences of a single disaster. For example, in the case of earthquakes superimposed with other disasters, on the one hand, the impact of induced disasters has already been considered in the earthquake consequence analysis; on the other hand, the consequences induced by earthquakes are global, and the resulting consequences are more severe than the consequences of superimposing a single disaster.

[0119] The second level: sub-item level screening.

[0120] If system-level filtering still cannot eliminate the possibility of overlap, then filtering should be conducted in conjunction with the design and layout characteristics of the sub-items. Figure 3 The analysis of the superimposed disaster scope is performed item by item from the obtained list of sub-items, taking into account the following factors:

[0121] First, can the sub-item itself withstand one of the disasters, thereby decoupling the superimposed disasters? This is typically used for combinations where external disasters induce internal disasters.

[0122] Secondly, it's crucial to determine if any corresponding disaster sources exist within the sub-items. This refers to the source items that could trigger a disaster, such as hydrogen pipelines or hydrogen tanks that might cause an explosion. If none of the superimposed disaster sources exist, or if one of them does not exist, then the superposition will not occur.

[0123] Next, the arrangement of sub-items, or the design of existing systems, can prevent the superposition of events. This mainly applies to disasters with global impact. For example, a sub-item may not have considered the impact of an external explosion, but if the explosion source in the plant area is far from the sub-item from the arrangement, exceeding the minimum safe distance, then even if an external explosion is induced by a tornado, it will not affect the safety of the sub-item.

[0124] Finally, even if existing designs are affected by superimposed disasters, the consequences are acceptable or controllable due to the existence of backup or mitigation measures, such as backup cooling measures or other safety measures that prevent the spread of disaster consequences.

[0125] The third level: Specific scenario function analysis.

[0126] By filtering through the previous two levels, we can determine the credible combinations of superimposed disasters applicable to a certain sub-item, thus forming a table as follows, which is a secondary classification list, specifically defined as Table 2. In Table 2, we indicate whether each credible combination of superimposed disasters in Table 1 is applicable to a specific factory building ("√" indicates applicable, "×" indicates not applicable).

[0127] Table 2. Analysis of Credible Overlay Disasters and Sub-items

[0128]

[0129] For the combinations of [Credible Superimposed Disasters, Sub-items] applicable in Table 2, it is necessary to consider the specific locations of the safety items and disaster sources within the sub-items and determine from a functional analysis perspective whether the superimposed disasters will cause unacceptable consequences to the safety items. Functional analysis includes both qualitative and quantitative methods.

[0130] For the credible external hazards and the superposition of LOOP and / or LUHS in Table 1, the functional analysis method can be directly applied. That is, the start time and duration of the credible external hazard under the credible superposition scenario and its direct impact on LOOP and / or LUHS are considered, and the impact on safety items and the consequences are analyzed.

[0131] The fourth level: eliminating risks.

[0132] After analyzing the first three levels, we can determine which credible superimposed hazards will produce unacceptable consequences (the criterion for determining whether a credible superimposed hazard will produce unacceptable consequences is that the protection objectives for both external and internal hazards are to ensure the reactor's safe shutdown capability (i.e., reactivity control, residual heat removal, and containment of radioactive materials)). We can then take corresponding protective measures in the design to eliminate risks or mitigate consequences. The result of risk elimination will lead to several design changes.

[0133] For example, taking the case of internal flooding caused by an external explosion in Table 1, the nuclear island building houses components required for safe shutdown. However, because the exterior walls of the nuclear island building were designed to withstand the loads of an external explosion, and the openings and penetrations in the exterior walls (including doors) are also required to withstand corresponding explosion loads, the shock wave generated by the explosion cannot be transmitted into the building to cause damage to the internal flooding source. Therefore, this disaster combination can be decoupled and eliminated from the nuclear island building. In this process, it is necessary to focus on checking and confirming the shock wave resistance capabilities of the openings and penetrations in the exterior walls of the building.

[0134] This invention obtains Table 1 through preliminary screening and analysis. Table 1 and the corresponding screening criteria comprehensively and effectively identify possible disaster overlap types, avoiding omissions. Furthermore, a detailed screening analysis is conducted, using detailed screening steps and criteria to comprehensively and effectively determine the disaster overlap types that need to be considered. These criteria are closely integrated with design considerations and recorded in Table 2 to ensure comprehensiveness and avoid omissions. Finally, this invention also eliminates the last remaining risk items, ensuring a closed loop for the entire implementation system.

[0135] This invention also provides a disaster superposition analysis system for nuclear power plants, comprising:

[0136] The acquisition unit is used to acquire standard specifications and experience feedback data from nuclear power plants.

[0137] The preliminary screening and analysis unit is used to conduct preliminary screening and analysis based on standard specifications, experience feedback data, and screening criteria to obtain a preliminary screening list of disaster superposition.

[0138] The secondary screening and analysis unit is used to perform secondary analysis based on the preliminary screening list of disaster superposition and the list of superposition disaster analysis scope to obtain the disaster superposition list.

[0139] Specifically, the specific coordination and operation process between the various units in the disaster superposition analysis system of the nuclear power plant can be referred to the disaster superposition analysis method of the nuclear power plant mentioned above, and will not be repeated here.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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 superimposed hazard analysis of a nuclear power plant, characterized in that, Includes the following steps: Obtain standard specifications and experience feedback data from nuclear power plants; Based on the aforementioned standards and specifications, the aforementioned experience feedback data, and the screening criteria, a preliminary screening analysis was conducted to obtain a preliminary screening list of disaster superposition. Based on the preliminary screening list of disaster superposition and combined with the list of superposition disaster analysis scope, a secondary analysis is performed to obtain the disaster superposition list; The list of superimposed disaster analysis scopes is obtained through the following steps: acquiring information on all structures within the nuclear power plant; determining whether each structure has a system or component capable of performing a safe shutdown function; the sub-item being a structure of the nuclear power plant; if so, identifying the current building as the building requiring consideration of superimposed disasters; and forming the list of superimposed disaster analysis scopes based on the identified buildings requiring consideration of superimposed disasters.

2. The method for disaster superposition analysis of nuclear power plants according to claim 1, characterized in that, The preliminary screening analysis based on the aforementioned standards and specifications, the aforementioned experience feedback data, and the screening criteria, to obtain a preliminary screening list of disaster superposition, includes: The analysis is performed based on the aforementioned standards and specifications and the aforementioned experience feedback data, and the results are used to determine whether the disaster combination to be analyzed is a superimposed disaster in the aforementioned standards and specifications or a superimposed disaster in the aforementioned experience feedback data. If so, the disaster combination to be analyzed is determined as a reliable superimposed disaster combination; If not, then determine whether the disaster combination to be analyzed will theoretically overlap; If the disaster combination to be analyzed is theoretically superimposed, then determine whether the disaster combination to be analyzed has been excluded by existing design measures; If the disaster combination to be analyzed is not excluded by existing design measures, then determine whether there are management measures to mitigate or eliminate the occurrence of the disaster combination to be analyzed; If there are no management measures to mitigate or eliminate the occurrence of the disaster combination to be analyzed, then determine whether the probability of the occurrence of the disaster combination to be analyzed is less than the set probability; If the probability of the disaster combination to be analyzed occurring is greater than the set probability, then the disaster combination to be analyzed is determined as a reliable superimposed disaster combination; Based on the credible combinations of superimposed disasters and the combinations of superimposed disasters caused by external disasters, a preliminary screening list of the superimposed disasters is formed.

3. The method for disaster superposition analysis of nuclear power plants according to claim 1, characterized in that, The preliminary screening list based on the disaster overlay, combined with the list of overlay disaster analysis scopes, is used for secondary analysis to obtain the disaster overlay list, which includes: Based on the preliminary screening list of disaster superpositions, all credible combinations of superposition disasters are obtained; the credible combinations of superposition disasters are those combinations with related or secondary disasters identified in the preliminary screening list. Perform the following analysis for each credible combination of superimposed hazards: Perform system-level screening; the system-level screening includes: determining whether there is a method that meets the conditions; the method that meets the conditions is: a method that is related to the disaster superposition phenomenon of the credible superposition disaster combination to be analyzed and makes the consequences of the credible superposition disaster combination to be analyzed within an acceptable range; if there is no method that meets the conditions, then determine whether the credible superposition disaster combination to be analyzed meets the consideration conditions; the consideration conditions are: the disaster consequences generated by the credible superposition disaster combination to be analyzed already include any one of the disasters in the credible superposition disaster combination to be analyzed; or the disaster consequences generated by the credible superposition disaster combination to be analyzed are less than the disaster consequences generated by any one of the disasters in the credible superposition disaster combination to be analyzed; if the consideration conditions are not met, then perform sub-item-level screening; After completing the system-level screening, the list of superimposed disaster analysis scopes is combined with the credible combinations of superimposed disasters to be analyzed to perform sub-item-level screening. This sub-item-level screening involves: obtaining all sub-items within the superimposed disaster analysis scope based on the list of superimposed disaster analysis scopes; combining each sub-item with the credible combinations of superimposed disasters to be analyzed, and performing the following analysis: determining whether the sub-item to be analyzed can withstand any one of the credible superimposed disasters to be analyzed; if not, determining whether the sub-item to be analyzed... There exists a disaster source corresponding to the credible superimposed disaster to be analyzed; if there is a disaster source corresponding to the credible superimposed disaster to be analyzed, then it is determined whether the layout of the sub-item to be analyzed or the system design of the sub-item to be analyzed can avoid the occurrence of the credible superimposed disaster to be analyzed; if it cannot avoid the occurrence of the credible superimposed disaster to be analyzed, then it is determined whether the sub-item to be analyzed has backup measures or mitigation measures; if there are no backup measures or mitigation measures, then a secondary classification list is generated; based on the secondary classification list, a specific scenario functional analysis is performed in combination with the superimposed disaster combination caused by external disasters; the sub-item is the structure of the nuclear power plant; After completing the sub-item-level screening, perform specific scenario function analysis; The step of performing specific scenario functional analysis based on the secondary classification list and the superimposed disaster combinations caused by the external disasters includes: obtaining the superimposed disaster combinations caused by the external disasters according to the preliminary screening list of disaster superposition; performing functional analysis based on the secondary classification list and the superimposed disaster combinations caused by the external disasters; and judging the impact of the superimposed disaster combinations caused by the external disasters on safety items based on the functional analysis results. Based on the analysis results of each credible superimposed disaster combination and the analysis results of superimposed disaster combinations caused by external disasters, the disaster superposition list is obtained.

4. The method for disaster superposition analysis of nuclear power plants according to claim 3, characterized in that, The assessment of the impact of combined external disasters on safety items based on functional analysis results includes: The impact of the combined effects of external disasters on safety items is determined based on the start time of the credible external disaster, the duration of the credible external disaster, and the consequences of the credible external disaster on the loss of external power and / or the loss of the final heat sink; the credible external disasters are those in the preliminary screening list. If unacceptable, output the corresponding reliable combination of superimposed disasters.

5. The method for disaster superposition analysis of nuclear power plants according to claim 4, characterized in that, The method further includes: Based on the aforementioned list of overlapping disasters, identify credible overlapping disasters that could lead to unacceptable consequences; Risk mitigation is carried out for credible superimposed disasters that could lead to unacceptable consequences.

6. A disaster superposition analysis system for nuclear power plants, characterized in that, include: The acquisition unit is used to acquire standard specifications and experience feedback data from nuclear power plants. The preliminary screening and analysis unit is used to perform preliminary screening and analysis based on the aforementioned standards and specifications, the aforementioned experience feedback data, and the screening criteria to obtain a preliminary screening list of disaster superposition. The secondary screening and analysis unit is used to perform secondary analysis based on the preliminary screening list of disaster superposition and the list of superposition disaster analysis scope to obtain the disaster superposition list; The list of superimposed disaster analysis scopes is obtained through the following steps: acquiring information on all structures within the nuclear power plant; determining whether each structure has a system or component capable of performing a safe shutdown function; the sub-item being a structure of the nuclear power plant; if so, identifying the current building as the building requiring consideration of superimposed disasters; and forming the list of superimposed disaster analysis scopes based on the identified buildings requiring consideration of superimposed disasters.

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