Decision-making method and device, design system and method for nuclear power plant system optimization

Abstract

The present invention provides a decision-making method and apparatus for nuclear power plant system optimization, as well as a design system and method for a nuclear power plant system. The decision-making method includes: obtaining the cost generated by a design optimization item to obtain Δcost; obtaining the core damage frequency (CDF) and the large radioactive release frequency (LRF) reduced by the design optimization item to obtain ΔCDF and ΔLRF; calculating the value of #imgabs0# and comparing the value of #imgabs1# with a first and second preset balance index, respectively; and deciding whether to implement the design optimization item based on the comparison results. This decision-making method can be applied to the design stage of a new reactor type and can simultaneously meet the safety and economic requirements of a nuclear power plant.

Description

Technical Field

[0001] The present invention relates to the field of nuclear power technology, and in particular to a decision-making method and device for nuclear power plant system optimization, and a design system and method for nuclear power plant systems. Background Art

[0002] The market competitiveness of nuclear power technology depends largely on its safety and economics. System design is a core component of the research and development of new reactor types. Currently, the industry's mainstream design approach is still based on deterministic thinking, employing qualitative methods or principles such as traditional defense-in-depth, single failures, redundancy, and diversity. During the design and decision-making process, the resulting design often relies on the designer's own experience and subjective judgment, making it difficult to ensure a balance between safety and economics. This can lead to safety weaknesses and economic losses.

[0003] Currently, risk-guided decision-making methods based on probabilistic safety analysis have been widely used in nuclear power system design. However, these decision-making methods only focus on safety and cannot meet the urgent need to achieve a balance between safety and economy when developing new nuclear power reactor types. As a result, the designed nuclear power plants suffer from wasteful construction and operating costs, resulting in economic losses. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art and provide a decision-making method and device for nuclear power plant system optimization, as well as a design system and method for nuclear power plant systems, which can be applied to the design stage of new reactor types and can simultaneously meet the safety and economic balance requirements of nuclear power plants.

[0005] In a first aspect, an embodiment of the present invention provides a decision-making method for nuclear power plant system optimization, comprising: obtaining a cost generated by a design optimization item to obtain a Δcost; obtaining a core damage frequency (CDF) and a large release frequency (LRF) reduced by the design optimization item to obtain a ΔCDF and a ΔLRF; and calculating , and The value of is compared with a preset first balance index and a preset second balance index respectively; and a decision is made based on the comparison result whether to implement the design optimization item.

[0006] Preferably, determining whether to implement the design optimization item according to the comparison result specifically includes: if is less than a preset first balance indicator, and / or If the value is less than a preset second balance index, a decision is made to implement the design optimization item.

[0007] Preferably, in the Before comparing the value of with the preset first balance index and the preset second balance index respectively, the decision-making method for optimizing the nuclear power plant system further includes: calculating the preset first balance index and the preset second balance index, specifically according to the following formula:

[0008]

[0009]

[0010] Among them, L CDF 、L LRF Satisfies the following formula:

[0011] ΔCost<-ΔE CDF =-L CDF ×ΔCDF×n

[0012] ΔCost<-ΔE LRF =-L LRF ×ΔLRF×n

[0013] Where -ΔE CDF The difference in economic losses caused by the core damage accident avoided by the design optimization item, -ΔE LRF is the difference in economic losses caused by a large number of radioactive release accidents avoided by the design optimization item, n is the design life of the nuclear power plant, L=PD+WD+D1+D2+D3, D3=T p ×W e ×P,L is the total loss of the accident, L CDF is the total accident loss caused by the core damage accident, L LRF is the total loss caused by a large-scale radioactive release accident, PD is the public dose caused by the accident, WD is the worker dose caused by the accident, D1 is the off-site property loss caused by the accident, D2 is the cleaning, decontamination and decommissioning costs caused by the accident, D3 is the power generation loss caused by the accident, and T p is the expected shutdown time of the nuclear power plant caused by the accident, W e is the electric power of the nuclear power plant, and P is the benchmark electricity price per kilowatt-hour.

[0014] Preferably, before deciding whether to implement the design optimization item based on the comparison result, the decision-making method for nuclear power plant system optimization also includes: judging whether the design optimization item meets the safety performance index; after the judgment result is that the design optimization item meets the safety performance index, further deciding whether to implement the design optimization item based on the comparison result.

[0015] Preferably, the judgment of whether the design optimization item meets the safety performance index specifically includes: judging whether the design optimization item complies with the requirements of nuclear safety regulations and standards; judging whether the design optimization item meets the requirements of defense in depth; judging whether the design optimization item maintains the required safety margin; judging whether the design optimization item meets the risk index; the judgment result is that the design optimization item meets the safety performance index, specifically: the design optimization item complies with the requirements of nuclear safety regulations and standards, and, the design optimization item meets the requirements of defense in depth, and, the design optimization item maintains the required safety margin, and, the design optimization item meets the risk index.

[0016] In a second aspect, an embodiment of the present invention also provides a design method for a nuclear power plant system, comprising: determining an overall design scheme for the nuclear power plant; obtaining design optimization items in the overall design scheme; making decisions on the design optimization items according to the decision-making method for optimizing the nuclear power plant system described in the first aspect, and after deciding to implement the design optimization items, incorporating the design optimization items into the overall design scheme.

[0017] Preferably, the overall design scheme of the nuclear power plant is determined, specifically including: determining the basic design features and key parameters of the nuclear power plant, the basic design features and key parameters including the type and capacity of the nuclear power plant; obtaining risk indicators based on the basic design features and key parameters of the nuclear power plant, the risk indicators including CDF t 、LRF t According to CDF t and LRF t , determine the safety-related system schemes of the nuclear power plant; determine other system schemes to obtain the overall design scheme; among which the overall design scheme includes the safety-related system schemes and other system schemes.

[0018] Preferably, the CDF t and LRF t , determine the safety-related system solutions for the nuclear power plant, specifically including: obtaining all initiating events / groups and their corresponding frequencies; for each initiating event / group, determining the corresponding conditional core damage probability (CCDP) index value and conditional radioactive release probability (CLRP) index value for each initiating event / group according to the following formula:

[0019]

[0020]

[0021] Among them, IE i Refers to the i-th initiating event / group, F(IE i ) refers to the frequency corresponding to the i-th initiating event / group, i = 1, 2, ..., n, CCDP (IE i) is the CCDP index value corresponding to the i-th initiating event / group, CLRP(IE i ) is the CLRP index value corresponding to the i-th initiating event / group. For each initiating event / group, the required safety function and the corresponding mitigation system of the safety function are determined; for each initiating event / group, the failure data of the determined safety function and the corresponding mitigation system of the safety function are input into the probabilistic safety analysis PSA model to obtain the CCDP actual value and CLRP actual value corresponding to each initiating event / group; the CCDP actual value and CLRP actual value corresponding to each initiating event / group are compared with the determined CCDP index value and the determined CLRP index value respectively; when the comparison result is that the CCDP actual value is less than the CCDP index value, and the CLRP actual value is less than the CLRP index value, it is determined that the safety-related system plan of the nuclear power plant meets the requirements; if not, it is determined that the safety-related system plan of the nuclear power plant needs to be modified until it meets the requirements.

[0022] Preferably, the obtaining of design optimization items in the overall design solution specifically includes: identifying the design optimization items in the overall design solution based on the PSA model.

[0023] In a third aspect, an embodiment of the present invention further provides a decision-making device for nuclear power plant system optimization, comprising a first acquisition module, a second acquisition module, a calculation module and a decision-making module.

[0024] The first acquisition module is used to obtain the cost generated by the design optimization item to obtain Δcost. The second acquisition module is used to obtain the core damage frequency CDF reduced by the design optimization item and the large radioactive release frequency LRF reduced by the design optimization item to obtain ΔCDF and ΔLRF. The calculation module is connected to the first acquisition module and the second acquisition module respectively to calculate , and The value of is compared with the preset first balance index and the second balance index respectively to obtain a comparison result. The decision module is connected to the calculation module and is used to decide whether to implement the design optimization item according to the comparison result of the calculation module.

[0025] In a fourth aspect, embodiments of the present invention further provide a nuclear power plant system design system, comprising a determining device, an acquiring device, and a decision-making device for nuclear power plant system optimization as described in claim 10. The determining device is configured to determine an overall design scheme for the nuclear power plant; the acquiring device is configured to acquire design optimization items from the overall design scheme; and the decision-making device for nuclear power plant system optimization is connected to the determining device and the acquiring device, respectively, and is configured to make a decision on the design optimization items of the acquiring device. After deciding to implement the design optimization items, the decision-making device incorporates the design optimization items into the overall design scheme of the determining device.

[0026] In the decision-making method and device for nuclear power plant system optimization, and the design system and method for nuclear power plant system of the present invention, the first balance index and the second balance index of the balance between design safety and economy are used to determine the balance between the design safety and economy, and then the design optimization item is The comparison with the first balance index and the second balance index is used to decide whether to implement the design optimization item so that the designed system can meet the balance between safety and economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a four-quadrant diagram of safety index (CDF) and economic index;

[0028] Figure 2 It is a four-quadrant diagram of safety index (LRF) and economic index;

[0029] Figure 3 A flowchart of a decision-making method for nuclear power plant system optimization according to embodiment 1 of the present invention;

[0030] Figure 4 A schematic diagram of a decision basis for nuclear power plant system optimization according to Example 1 of the present invention;

[0031] Figure 5 This is a flow chart of a design method for a nuclear power plant system according to embodiment 3 of the present invention;

[0032] Figure 6 This is a structural schematic diagram of a design device for a nuclear power plant system according to Example 4 of the present invention. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0034] The basic principle of the decision-making method for nuclear power plant system optimization of the present invention is to simultaneously introduce quantitative indicators of both safety and economic efficiency during the research, development, and design of new nuclear power plant reactor types for decision-making. Specifically, the quantitative indicators of safety include the core damage frequency (CDF) and the large radioactive release frequency (LRF). The generally accepted quantitative indicator of economic efficiency is the cost per kilowatt. However, based on the determination of the capacity of the new reactor type, a more direct evaluation indicator can be converted into the nuclear power construction cost. Considering that different design schemes will affect the subsequent operating costs of the nuclear power plant after completion, the present invention combines the construction cost and operating cost of the nuclear power plant, collectively referred to as the broad "cost" as a quantitative indicator of economic efficiency.

[0035] For example, the research and development and design of new reactor types focus on the comparison of various options, so the difference comparison of various indicators is the key. Figure 1As shown in the figure, the safety index is the CDF difference (i.e. ΔCDF), and the economic index is the cost difference (i.e. Δcost). When a design optimization item (or a design solution relative to the baseline solution) falls into Figure 1 If it falls into the I quadrant, it means that the design optimization item will lead to a decrease in safety and an increase in cost, which is obviously unacceptable. If it falls into the III quadrant, it means that safety is improved and cost is reduced, which is acceptable. If it falls into the II and IV quadrants, it can only be considered acceptable when the safety benefits are greater than the economic losses, or when the economic benefits are greater than the safety losses. In other words, if Figure 1 It shows that the solution below the slash is acceptable, that is, the relevant indicators of the design optimization items should satisfy the following formula:

[0036]

[0037] Similarly, if Figure 2 As shown in Figure 2, the same four-quadrant diagram is also used for the LRF difference (i.e., ΔLRF) and cost difference (i.e., Δcost) of the design optimization items. Figure 1 Similarly, a design optimization item is unacceptable if it falls into quadrant I, but acceptable if it falls into quadrant III. If it falls into quadrant II or IV, then Figure 2 The solution below the middle slash is acceptable, that is, the relevant indicators of the design optimization items should satisfy the following formula:

[0038]

[0039] The calculation methods of the first balance index and the second balance index are described in detail in Example 1.

[0040] Example 1:

[0041] like Figure 3 As shown, this embodiment provides a decision-making method for nuclear power plant system optimization, which is applicable to the design stage of a new reactor type or the improved design during the power plant operation stage. The decision-making method includes:

[0042] Step 101: Obtain the cost generated by the design optimization item to obtain Δ cost.

[0043] In this embodiment, the design optimization item can be understood as a design solution, an improved solution, an optimized solution, etc. relative to the baseline solution. ΔCost refers to the increased construction cost and operating cost required to implement the design optimization item.

[0044] Step 102 : Obtain the core damage frequency CDF and the large radioactive release frequency LRF reduced by the design optimization item to obtain ΔCDF and ΔLRF.

[0045] In this embodiment, since implementing the design optimization item will reduce the CDF and / or reduce the LRF, the ΔCDF and ΔLRF corresponding to the implementation of the design optimization item are obtained.

[0046] Step 103, calculate , and The values are compared with the preset first balance index and the second balance index respectively.

[0047] In this embodiment, based on the basic principle of the present invention, the first balance index and the second balance index comprehensively consider the balance between the safety index and the economic index, so the corresponding design optimization item is implemented. The value of is compared with the preset first balance index and the preset second balance index respectively to provide a basis for deciding whether to implement the design optimization item.

[0048] Step 104: decide whether to implement the design optimization item based on the comparison result.

[0049] In this embodiment, when the comparison result satisfies the requirement of balancing safety and economic indicators, the design optimization item is decided to be implemented. This avoids the decision being dependent on the designer's own experience and subjective judgment, which could result in safety weaknesses or economic losses. It should be noted that steps 101 and 102 of this embodiment can be reversed in order.

[0050] Optionally, step 104: deciding whether to implement the design optimization item according to the comparison result, specifically including: if is less than a preset first balance indicator, and / or If the value is less than a preset second balance index, a decision is made to implement the design optimization item.

[0051] In this embodiment, if any of the following three situations exists, the decision to implement the design optimization item is made: is less than the preset first balance indicator, or, is less than the preset second balance indicator, or, Less than the preset first balance indicator and Less than the preset second balance indicator.

[0052] Optionally, Before comparing the value of with the preset first balance index and the preset second balance index respectively, the decision-making method for optimizing the nuclear power plant system further includes: calculating the preset first balance index and the preset second balance index, specifically according to the following formula:

[0053]

[0054]

[0055] Among them, L CDF 、L LRF Satisfies the following formula:

[0056] ΔCost<-ΔE CDF =-L CDF ×ΔCDF×n

[0057] ΔCost<-ΔE LRF =-L LRF ×ΔLRF×n

[0058] Where -ΔE CDF The difference in economic losses caused by the core damage accident avoided by the design optimization item, -ΔE LRF is the difference in economic losses caused by a large number of radioactive release accidents avoided by the design optimization item, n is the design life of the nuclear power plant, L=PD+WD+D1+D2+D3, D3=T p ×W e ×P,L is the total loss of the accident, L CDF is the total accident loss caused by the core damage accident, L LRF is the total loss caused by a large-scale radioactive release accident, PD is the public dose caused by the accident, WD is the worker dose caused by the accident, D1 is the off-site property loss caused by the accident, D2 is the cleaning, decontamination and decommissioning costs caused by the accident, D3 is the power generation loss caused by the accident, and T p is the expected shutdown time of the nuclear power plant caused by the accident, W e is the electric power of the nuclear power plant, and P is the benchmark electricity price per kilowatt-hour.

[0059] In this embodiment, the values of the first balance index and the second balance index are calculated using a million-kilowatt nuclear power unit as an example. The method of this embodiment can be used to calculate the values of the first balance index and the second balance index of nuclear power units of other capacities. Specifically, an accident loss calculation model is given, which satisfies L=PD+WD+D1+D2+D3, D3=T p ×W e ×P, where the unit of PD, WD, D2, and D3 is yuan, and T p The unit is "hours". Based on the economic loss data of three serious nuclear accidents in history, the above economic loss estimates are given for a million-kilowatt nuclear power plant. See Table 1 for details (the data in Table 1 will vary for different nuclear power plants). Taking my country's million-kilowatt nuclear power plant as an example, the power generation loss caused by a core damage accident is calculated as follows:

[0060]

[0061] In the above formula, the typical design life of newly built nuclear power plants is 60 years, and the typical unit availability factor is 0.9. The current domestic benchmark electricity price is 0.43 yuan / kWh. Based on this, the power generation loss D3 due to a core damage accident is calculated to be 1.0E+11 yuan. In the event of a large-scale radioactive release, not only will the affected unit be unable to generate electricity, but severe contamination in the plant area will also cause other units at the same site to cease operation. For example, after the Fukushima accident, the intact units at the same site were permanently shut down. Therefore, assuming six units per site, the power generation loss D3 due to a large-scale radioactive release accident is 6.0E+11 yuan.

[0062] Table 1 Accident loss parameters (corresponding to million-kilowatt nuclear power plants)

[0063]

[0064] After constructing the PSA model and calculating the CDF and LRF values of a specific million-kilowatt nuclear power plant, the following formula is used to estimate the difference in accident losses caused by different design schemes:

[0065] ΔE CDF =L CDF ×ΔCDF×60

[0066] ΔE LRF =L LRF ×ΔLRF×60

[0067] Based on the principle of "investment < avoided economic losses", it meets the following requirements:

[0068] ΔCost < ΔE CDF

[0069] ΔCost < ΔE LRF

[0070] Thus we get:

[0071]

[0072]

[0073] That is, the preset first balance index is -8.7E-14, and the preset second balance index is -7.4E-15.

[0074] Optionally, before deciding whether to implement the design optimization item based on the comparison result, the decision-making method for nuclear power plant system optimization also includes: judging whether the design optimization item meets the safety performance index; after the judgment result is that the design optimization item meets the safety performance index, further deciding whether to implement the design optimization item based on the comparison result.

[0075] Optionally, determining whether the design optimization item meets the safety performance index specifically includes: determining whether the design optimization item complies with the requirements of nuclear safety regulations and standards; determining whether the design optimization item meets the defense-in-depth requirements; determining whether the design optimization item maintains the required safety margin; and determining whether the design optimization item meets the risk index.

[0076] In this embodiment, during the design phase of a new reactor or during the improved design during the operation phase of a power plant, the particularity of nuclear safety must be considered, that is, the design of a nuclear power plant must first comply with the nuclear safety laws and regulations and related rules and regulations issued by the national nuclear safety regulatory authorities, and at the same time, must meet the overall probabilistic safety goals. Figure 4 When making decisions on design optimization items based on the decision-making basis of the nuclear power plant system optimization shown in the figure, the design optimization items implemented in the decision-making process can effectively achieve a balance between safety and economy while ensuring safety. Figure 4 The decision bases for nuclear power plant system optimization shown include:

[0077] 1. The design optimization items should be evaluated to see whether they will lead to non-compliance with existing nuclear safety regulations and standards, for example, whether they will affect the single fault criterion set out in the "Regulations on Safety of Nuclear Power Plant Design (HAF102-2016)";

[0078] 2. Design optimizations should be evaluated for consistency with the defense-in-depth principle. The fundamental purpose is to ensure that the defense-in-depth principle is maintained. However, design optimizations should not be rejected solely based on their impact on existing defense-in-depth implementation methods. Specific requirements include:

[0079] (1) A reasonable balance can be achieved between preventing core damage, containment failure, and mitigating the consequences;

[0080] (2) not overly rely on human intervention and take measures to prevent human error;

[0081] (3) The design of the system in terms of redundancy, independence and diversity is commensurate with the accident risks (frequency and consequences) it addresses, and fully considers the uncertainty of risk analysis;

[0082] (4) Measures have been taken to address potential common cause failures, but if the design introduces new common cause failure mechanisms, an assessment is required.

[0083] 3. The design optimization items should be evaluated to see whether they can meet the principle of maintaining sufficient safety margin. Sufficient safety margin means:

[0084] (1) Comply with regulations, standards, or other alternative provisions approved for use by other safety regulatory authorities;

[0085] (2) The acceptance criteria for the relevant accident analysis in the safety analysis report can still be met, or there is still sufficient margin after considering the analysis and data uncertainties.

[0086] 4. The impact of design optimization items on unit risk indicators should be evaluated. Acceptable risk indicators mean:

[0087] (1) The total CDF is less than 1E-5 / reactor-year;

[0088] (2) The total LRF is less than 1E-6 / reactor-year.

[0089] Among them: The above CDF values and LRF values are the requirements of China's nuclear safety regulatory authorities. If the new reactor type is expected to be used in a specific country, it should be re-determined in accordance with the nuclear safety regulations of the corresponding country.

[0090] 5. Only when the design optimization items of nuclear power plants meet the requirements of Principles 1 to 4 can the “cost-benefit balance” principle be considered, i.e., a comprehensive decision-making evaluation of the safety and economic efficiency of the design optimization items can be conducted. For example, according to the design optimization items of this embodiment, and / or, design optimization To achieve the best balance.

[0091] 6. Continuous tracking and iteration of safety and economic analysis is to ensure that any problems that may arise in the subsequent specific design and construction process can be resolved in a timely manner, and the safety and economic decision-making evaluation results can be updated in a timely manner.

[0092] The decision-making method for nuclear power plant system optimization in this embodiment introduces both safety and economic indicators to rationally design the first balance indicator and the second balance indicator, and assigns the design optimization items to the corresponding The first and second balance indicators are compared respectively, and a decision is made on whether to implement the design optimization item based on the comparison results, so that the design optimization item finally implemented can meet the balance requirements of safety and economy, provide an objective decision-making basis for the system design and decision-making of the nuclear power plant, and avoid the problem that the design optimization items implemented based on manual experience judgment are not safe enough or cause economic waste.

[0093] Example 2:

[0094] This embodiment provides a design method for a nuclear power plant system, including steps 201 to 203:

[0095] Step 201: Determine the overall design plan of the nuclear power plant.

[0096] Step 202: Obtain design optimization items in the overall design solution.

[0097] Step 203: making a decision on the design optimization item according to the decision-making method for nuclear power plant system optimization described in Example 1. After deciding to implement the design optimization item, the design optimization item is incorporated into the overall design solution.

[0098] Optionally, step 201: determining an overall design plan for a nuclear power plant, specifically includes:

[0099] Step 2011: determine the basic design features and key parameters of the nuclear power plant, which include the type and capacity of the nuclear power plant.

[0100] Step 2022: Obtain risk indicators based on the basic design features and key parameters of the nuclear power plant. The risk indicators include CDF t 、LRF t .

[0101] Step 2023, according to CDF t and LRF t , determine the safety-related system schemes of the nuclear power plant; determine other system schemes to obtain the overall design scheme, where the overall design scheme includes the safety-related system schemes and other system schemes.

[0102] Optionally, step 2023: according to CDF t and LRF t , determine the safety-related system plan of the nuclear power plant, including steps 21 to 26:

[0103] Step 21: Obtain all originating events / groups and their corresponding frequencies.

[0104] Step 22: For each initiating event / group, determine the corresponding conditional core damage probability (CCDP) and conditional radioactive release probability (CLRP) values for each initiating event / group according to the following formula:

[0105]

[0106]

[0107] Among them, IE i Refers to the i-th initiating event / group, F(IE i ) refers to the frequency corresponding to the i-th initiating event / group, i = 1, 2, ..., n, CCDP (IE i ) is the CCDP index value corresponding to the i-th initiating event / group, CLRP(IE i ) is the CLRP index value of the conditional radioactive release probability corresponding to the i-th initiating event / group.

[0108] Step 23: For each initiating event / group, determine the required safety function and the corresponding mitigation system of the safety function.

[0109] Step 24: For each initiating event / group, the failure data of the determined safety function and the corresponding mitigation system of the safety function are input into the probabilistic safety analysis PSA model to obtain the actual CCDP value and CLRP value corresponding to each initiating event / group.

[0110] Step 25: Compare the CCDP actual value and CLRP actual value corresponding to each initiating event / group with the determined CCDP index value and the determined CLRP index value respectively.

[0111] In step 26, when the comparison result shows that the CCDP actual value is less than the CCDP index value and the CLRP actual value is less than the CLRP index value, it is determined that the safety-related system plan of the nuclear power plant meets the requirements. If not, it is determined that the safety-related system plan of the nuclear power plant needs to be modified until it meets the requirements.

[0112] Optionally, step 202: obtaining design optimization items in the overall design solution specifically includes: identifying the design optimization items in the overall design solution based on the PSA model.

[0113] Example 3:

[0114] like Figure 5 As shown, this embodiment provides a risk-based design method for a nuclear power plant system, which is applied to the design of a new reactor type. The design method includes the following steps:

[0115] Step 1: Determine the basic design features and key parameters of the nuclear power plant.

[0116] For the development of new reactor types, it is necessary to determine their basic design features and key parameters, mainly including:

[0117] 1. Nuclear power plant type and capacity, such as pressurized water reactor or other reactor type, and rated core output power.

[0118] 2. The main characteristics and key parameters of the nuclear steam supply system, such as single-unit layout or the presence of shared parts for multiple units, two-loop, three-loop, or four-loop system, and the design pressures of the primary and secondary loops.

[0119] Step 2: Obtain risk guidance evaluation indicators. Risk guidance evaluation indicators include: CDF t , CDF t ,△CDF / △cost,△LRF / △cost, among which, CDF t 、CDF t It is also a risk indicator that the national nuclear safety regulatory authorities pay attention to.

[0120] Step 3: Determine the safety-related system plan for the nuclear power plant, including steps 3.1 to 3.4.

[0121] Step 3.1: Obtain a list of all initiating events / groups and their frequencies. Specifically, the design objective of the safety-related system plan for a nuclear power plant is to respond to various hypothetical accidents (i.e., initiating events) while meeting established risk indicators. This can be expressed as:

[0122]

[0123]

[0124] Therefore, this step requires determining a list of initiating events / groups and their frequencies. For pressurized water reactor units, a general list of internal initiating events / groups and their frequencies is available, as detailed in Table 2. As R&D and design progress, this list should be updated based on the unit's design characteristics and expanded to include external events (typically, internal fire, internal flooding, and earthquakes). Methods for analyzing the frequency of initiating events include statistical analysis and fault tree analysis.

[0125] Table 2 List of common initiating events / groups for pressurized water reactors and their frequencies

[0126]

[0127] Step 3.2: For each IE group, determine the CCDP index value and CLRP index value corresponding to each IE group.

[0128] Since all the initiating events / groups and their corresponding frequencies have been obtained in step 3.1, and the risk indicator CDF t and LRF t The value of is fixed, so in this step, the CCDP and CLRP values can be determined for all IE groups. Based on the examples of a large number of completed PWR PSA projects, while retaining appropriate margins (for example, a margin of 1.0 or 15%), Tables 3 and 4 provide sample tables for determining CCDP and CLRP values, respectively. The following should be noted:

[0129] (1) During the R&D phase and early design phase of a new nuclear power reactor, the system design has not yet been fully completed, especially the layout information cannot be determined. Therefore, the risk of external events is difficult to determine at this stage. Tables 3 and 4 provide the indicator requirements for internal events.

[0130] (2) Based on the experience of a large number of previous PSA projects, internal fire, internal flooding, and earthquake are the main contributors to the risk of external events. Among them, the risk of internal fire is usually slightly lower than that of internal events, while the risk of internal flooding is much lower than that of internal events. The earthquake risk is closely related to the plant site. In extremely harsh plant sites, it may be much higher than that of internal events. Under normal circumstances, it is equivalent to the risk of internal events. Based on this experience, the overall risk can be divided into five equal parts, corresponding to internal events, internal fire, internal flooding, earthquake, and retention margin. According to regulatory requirements, the CDF should be below 1E-5. If it is divided into five parts, the CDF of internal events should be below 2E-6. The result given by the sample table shown in Table 3 is 2.1E-6, which basically meets the division result of the five-equal division principle.

[0131] Table 3 Sample table for determining CCDP indicators for pressurized water reactors

[0132]

[0133] Table 4 Sample table for determining CLRP index of pressurized water reactor

[0134]

[0135]

[0136] Step 3.3: For each initiating event / group, determine the required safety functions and the corresponding mitigation systems for the safety functions.

[0137] In this step, the safety functions of the nuclear power plant are first determined, and then the corresponding mitigation systems are determined based on them. For example, the safety functions of a typical pressurized water reactor nuclear power plant are summarized in Table 5.

[0138] Table 5 Safety functions considered in PSA of typical PWR nuclear power units

[0139]

[0140]

[0141] Taking the main coolant system large break initiating event as an example, an analysis example for determining the safety functions and mitigation systems required for this initiating event is shown in Table 6.

[0142] Table 6 Safety functions and mitigation systems required for a major break initiating event in the primary coolant system

[0143]

[0144]

[0145] Step 3.4: For each initiating event / group, input the failure data of the determined safety function and the corresponding mitigation system of the safety function into the probabilistic safety analysis (PSA) model to obtain the actual CCDP value and CLRP value corresponding to each initiating event / group. Compare the actual CCDP value and CLRP value corresponding to each initiating event / group with the determined CCDP index value and the determined CLRP index value, respectively, to determine whether the CCDP and CLRP meet the requirements.

[0146] This embodiment proposes a method using an event tree tool to evaluate whether CCDP and CLRP meet requirements. As shown in Table 7, the failure probability of a typical system column level is given, which covers the common system configurations of current nuclear power plants.

[0147] Table 7 System level one failure probability

[0148]

[0149] Taking the main coolant system's major breach as an example, we constructed an event tree model based on current industry practices. By inputting the failure data of the mitigation systems associated with its safety functions into the constructed event tree model and considering common cause failures between system columns (common cause failure parameters can be referenced in industry-standard reliability databases), we can calculate the corresponding CCDP and CLRP actual values. This can be done manually by analysts; for complex models, it is recommended to develop appropriate calculation software. Alternatively, mature commercial software, such as RiskSpecturm PSA, can be used.

[0150] Table 4 shows that for a major breach in the main coolant system, the requirements are CCDP < 1.5E-2 and CLRP < 1.5E-3. If the initial design capacity of the main mitigation and support systems for this event is 100% × 2, the calculated actual CCDP values are 6.02E-3 and CLRP values are 1.46E-3. This result indicates that the current design meets the requirements, but the actual CLRP value is very close to the required limit (CLRP index value). In this case, additional systems may be considered to prevent containment failure.

[0151] Step 4: Determine other system solutions.

[0152] Other systems are mainly those not related to safety, such as conventional island systems and nuclear island auxiliary systems. They have little to do with safety functions and mitigation systems, and can be designed using traditional methods without the need to introduce risk guidance.

[0153] Step 5: Determine the overall design plan.

[0154] Based on the third and fourth steps, the overall design plan of the new reactor type has been basically completed. On this basis, the overall design plan should be finally confirmed from the two aspects of safety and economy. Some design optimization items may be identified. After confirming the rationality of the design optimization items, the design optimization items should be incorporated into the overall design plan to improve the overall design plan.

[0155] Step 5.1: Conduct safety analysis on the overall design scheme. In this step, the safety performance of the overall design scheme is mainly evaluated. For details, please refer to Example 1. Figure 4 The following four decision criteria are evaluated:

[0156] (1) Compliance with relevant nuclear safety regulations.

[0157] (2) Compliance with defense-in-depth requirements.

[0158] (3)Safety margin.

[0159] (4) Risk indicators.

[0160] It should be noted that to complete the conformity demonstration of risk indicators in task (4), a probabilistic safety analysis (PSA) model must be constructed. The PSA standards currently published in China are applicable to the model development in the design and operation stages of nuclear power plants, and are not fully applicable to the development of new reactor types. This is especially true in the early stages of development, when detailed design information (such as equipment layout information, specific equipment models, signal implementation methods, system auxiliary functions, other branch pipeline information, accident handling procedures, etc.) is not available. In this case, the PSA model that can be constructed is relatively simple. As shown in Table 8, the example provides the basic requirements and corresponding processing methods for the PSA model in the new reactor type development stage, based on which a high-accuracy PSA model suitable for the new reactor type development stage can be constructed.

[0161] Table 8 Basic requirements and corresponding treatment methods for PSA models in the new reactor type R&D stage

[0162]

[0163]

[0164] Step 5.2: Obtain the corresponding cost of the overall design scheme. Specifically, the levelized discounted cost calculation method recommended by the International Atomic Energy Agency (IAEA) can be used to obtain the corresponding cost data of the overall design scheme.

[0165] Step 5.3: Identify whether there are design optimization items in terms of safety and economy.

[0166] During steps 5.1 and 5.2, some safety weaknesses and options for further improving economic efficiency can be identified. In this step, corresponding models are developed to evaluate the safety and economic performance of the identified design options. Table 9 provides a sample evaluation table for a specific optimization solution (design optimization item).

[0167] Table 9 Sample evaluation table for a specific optimization solution

[0168]

[0169]

[0170] Step 6: Carry out specific engineering design and construction (continuous tracking and iterative safety and economic analysis). After completing steps 1 to 5, the overall design plan of the new reactor type has been determined, and specific engineering design and construction work will be carried out subsequently. During this period, the safety and economic models should be continuously iterated according to the development of engineering design and construction progress. It is usually required to upgrade the early probabilistic safety analysis model twice. The model upgrade work is synchronized with the submission of the preliminary safety analysis report and the final safety analysis report. At this stage, some design changes will be proposed at any time according to different problems encountered during the design and construction process. The evaluation method for this is the same as step 5.3

[0171] The design method of the nuclear power plant system provided in this embodiment proposes a risk guidance methodology system that integrates safety and economic indicators, and applies it to the research and development and design of new nuclear power reactor types. It can effectively solve the problem of balancing the economy and safety of the overall design scheme, which is the most concerned issue in the research and development of new nuclear power reactor types.

[0172] Example 4:

[0173] like Figure 6 As shown, this embodiment provides a decision-making device for nuclear power plant system optimization, including a first acquisition module 41 , a second acquisition module 42 , a calculation module 43 and a decision-making module 44 .

[0174] The first acquisition module 41 is used to acquire the cost generated by the design optimization item to obtain a Δ cost.

[0175] The second acquisition module 42 is configured to acquire the core damage frequency CDF and the large radioactive release frequency LRF reduced by the design optimization item, so as to obtain ΔCDF and ΔLRF.

[0176] The calculation module 43 is connected to the first acquisition module 41 and the second acquisition module 42 respectively, and is used to calculate , and The values are compared with the preset first balance index and the second balance index respectively to obtain comparison results.

[0177] The decision module 44 is connected to the calculation module 43 and is used to decide whether to implement the design optimization item according to the comparison result of the calculation module.

[0178] In addition, the decision-making device for nuclear power plant system optimization also includes other modules or other units, which are used to implement the decision-making method for nuclear power plant system optimization described in Example 1.

[0179] Example 5:

[0180] This embodiment provides a design system for a nuclear power plant system, including a determination device, an acquisition device, and a decision-making device for optimizing the nuclear power plant system as described in Example 4.

[0181] Determination device, used to determine the overall design plan of the nuclear power plant.

[0182] The acquisition device is used to obtain the design optimization items in the overall design solution.

[0183] The decision-making device for nuclear power plant system optimization is connected to the determination device and the acquisition device respectively, and is used to make decisions on the design optimization items of the acquisition device. After deciding to implement the design optimization items, the design optimization items are incorporated into the overall design plan of the determination device.

[0184] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A decision-making method for nuclear power plant system optimization, characterized in that: include: Obtain the cost generated by the design optimization item to obtain the Δ cost; Obtaining the core damage frequency CDF reduced by the design optimization item and the large radioactive release frequency LRF reduced by the design optimization item to obtain ΔCDF and ΔLRF; calculate , and The value of is compared with a preset first balance index and a preset second balance index respectively; Decide whether to implement the design optimization item based on the comparison result, Among them, the first balance Second balance n is the design life of the nuclear power plant, L CDF is the total accident loss caused by the core damage accident, L LRF The total amount of accidental losses caused by large-scale radioactive release accidents.

2. The decision-making method for nuclear power plant system optimization according to claim 1, characterized in that: The determining whether to implement the design optimization item according to the comparison result specifically includes: like is less than a preset first balance indicator, and / or If the value is less than a preset second balance index, a decision is made to implement the design optimization item.

3. The decision-making method for nuclear power plant system optimization according to claim 1, characterized in that: L CDF 、L LRF Satisfies the following formula: ΔCost<-ΔE CDF =-L CDF ×ΔCDF×n ΔCost<-ΔE LRF =-L LRF ×ΔLRF×n Where -ΔE CDF The difference in economic losses caused by the core damage accident avoided by the design optimization item, -ΔE LRF The difference in economic losses caused by the large number of radioactive release accidents avoided by the design optimization item, L = PD + WD + D1 + D2 + D3, D3 = T p ×W e ×P, L is the total loss caused by the accident, PD is the public dose caused by the accident, WD is the worker dose caused by the accident, D1 is the off-site property loss caused by the accident, D2 is the cleaning, decontamination and decommissioning costs caused by the accident, D3 is the power generation loss caused by the accident, T p is the expected shutdown time of the nuclear power plant caused by the accident, W e is the electric power of the nuclear power plant, and P is the benchmark electricity price per kilowatt-hour.

4. The decision-making method for nuclear power plant system optimization according to claim 1, characterized in that: Before deciding whether to implement the design optimization item according to the comparison result, the method further includes: Determining whether the design optimization item meets the safety performance index; After the judgment result shows that the design optimization item meets the safety performance index, a decision is further made based on the comparison result whether to implement the design optimization item.

5. The decision-making method for nuclear power plant system optimization according to claim 4, characterized in that: Determining whether the design optimization item meets the safety performance index specifically includes: Determine whether the design optimization items comply with nuclear safety regulations and standards; Determine whether the design optimization item meets the defense-in-depth requirements; Determining whether the design optimization item maintains a required safety margin; Determining whether the design optimization item meets the risk index; The judgment result is that the design optimization item meets the safety performance indicators, specifically: the design optimization item complies with the requirements of nuclear safety regulations and standards, and, the design optimization item meets the defense in depth requirements, and, the design optimization item maintains the required safety margin, and, the design optimization item meets the risk indicators.

6. A design method for a nuclear power plant system, characterized in that: include: Determine the overall design of the nuclear power plant; Obtain design optimization items in the overall design solution; According to the decision-making method for nuclear power plant system optimization according to any one of claims 1 to 5, a decision is made on the design optimization item, and after the decision to implement the design optimization item is made, the design optimization item is incorporated into the overall design scheme.

7. The design method of a nuclear power plant system according to claim 6, characterized in that: The determination of the overall design plan of the nuclear power plant specifically includes: Determine the design characteristics and parameters of the nuclear power plant, including the type and capacity of the nuclear power plant; According to the design characteristics and parameters of the nuclear power plant, risk indicators are obtained, including the core damage frequency risk index CDF t , Large Radioactive Release Frequency Risk Index LRF t ; According to CDF t and LRF t , determine the safety system plan of the nuclear power plant and obtain the overall design plan.

8. The design method of a nuclear power plant system according to claim 7, characterized in that: According to CDF t and LRF t , determine the safety system plan for the nuclear power plant, including: Get all originating events / groups and their corresponding frequencies; For each initiating event / group, the corresponding conditional core damage probability (CCDP) and conditional radioactive release probability (CLRP) values are determined according to the following formula: Among them, IE i Refers to the i-th initiating event / group, F(IE i ) refers to the frequency corresponding to the i-th initiating event / group, i = 1, 2, ..., m, CCDP (IE i ) is the CCDP index value corresponding to the i-th initiating event / group, CLRP(IE i ) is the CLRP index value of the conditional radioactive release probability corresponding to the i-th initiating event / group, For each initiating event / group, determine the required safety functions and the corresponding mitigation systems of the safety functions; For each initiating event / group, the failure data of the determined safety function and the corresponding mitigation system of the safety function are input into the probabilistic safety analysis PSA model to obtain the actual CCDP value and CLRP value corresponding to each initiating event / group; Comparing the CCDP actual value and CLRP actual value corresponding to each initiating event / group with the determined CCDP index value and the determined CLRP index value respectively; When the comparison result is that the CCDP actual value is less than the CCDP index value, and the CLRP actual value is less than the CLRP index value, it is determined that the safety system plan of the nuclear power plant meets the requirements. If not, it is determined that the safety system plan of the nuclear power plant needs to be modified until it meets the requirements.

9. The design method of a nuclear power plant system according to claim 8, characterized in that: The obtaining of design optimization items in the overall design solution specifically includes: Identify design optimization items in the overall design solution based on the PSA model.

10. A decision-making device for nuclear power plant system optimization, characterized in that: It includes a first acquisition module, a second acquisition module, a calculation module and a decision module, The first acquisition module is used to obtain the cost generated by the design optimization item to obtain Δ cost, The second acquisition module is used to obtain the core damage frequency CDF reduced by the design optimization item and the large radioactive release frequency LRF reduced by the design optimization item to obtain ΔCDF and ΔLRF, The calculation module is connected to the first acquisition module and the second acquisition module respectively, and is used to calculate , and The value of is compared with the preset first balance index and the second balance index respectively to obtain a comparison result. A decision module, connected to the calculation module, is used to decide whether to implement the design optimization item based on the comparison result of the calculation module, Among them, the first balance Second balance n is the design life of the nuclear power plant, L CDF is the total accident loss caused by the core damage accident, L LRF The total amount of accidental losses caused by large-scale radioactive release accidents.

11. A design system for a nuclear power plant system, characterized in that: The method comprises a determining device, an acquiring device, and a decision-making device for optimizing a nuclear power plant system as claimed in claim 10, Determination device, used to determine the overall design of the nuclear power plant, An acquisition device for acquiring design optimization items in the overall design solution, The decision-making device for nuclear power plant system optimization is connected to the determination device and the acquisition device respectively, and is used to make decisions on the design optimization items of the acquisition device. After deciding to implement the design optimization items, the design optimization items are incorporated into the overall design plan of the determination device.

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