Design method for improving power of nuclear power plant
By identifying and utilizing the key margin for power enhancement in the first reactor project, formulating and evaluating the total parameter scheme for power enhancement of nuclear power plants, the problem of insufficient utilization of design margin in nuclear power plants is solved, and the effect of power improvement and economic improvement of nuclear power plants is achieved.
Patent Information
- Application Number
- CN202510203382.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-24
- Publication Date
- 2025-06-03
AI Technical Summary
In nuclear power plants, the design margin of the first reactor project was not fully utilized in the subsequent unit power increase, resulting in potential economic and safety balance problems.
By sorting out and identifying the key margin for power improvement in the first stack project, including equipment performance margin and evaluation and analysis margin, and on the premise of ensuring safety, a total power improvement parameter plan is formulated to optimize the unit's rated output.
It has achieved the improvement of the power of the nuclear power plant on the basis of ensuring safety, thereby improving the economy of subsequent units and achieving the best balance between safety and economy.
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Figure CN120087066A_ABST
Abstract
Description
Technical Field
[0001] This application mainly relates to the field of nuclear power technology, and particularly relates to a design method for power increase of a nuclear power plant Background Art
[0002] During the R & D process of nuclear power models, in order to cope with various potential uncertainties in the processes of the first reactor project design, test, commissioning and operation, etc., and to ensure the smooth implementation of the first reactor project and reduce project risks, a relatively large margin is often reserved in the design. With the implementation, advancement and commissioning operation of the first reactor project, the model technology has been fully tested and verified in the project. Based on the practical experience of the first reactor project, subsequent units can consider releasing the design margin of the first reactor project to carry out power increase of the nuclear power plant on the premise of ensuring safety. Summary of the Invention
[0003] The technical problem to be solved by this application is to provide a design method for power increase of a nuclear power plant to solve the problems raised in the above background art.
[0004] To achieve the above object, this application provides a design method for power increase of a nuclear power plant. This method is applicable to the optimized design of subsequent units after the first reactor project, and includes the following steps: S1, based on the design parameters of the first reactor project, combined with the data accumulated in each stage of the first reactor project test, commissioning and operation, sort out and identify the key margins for power increase of the first reactor project as the basis for power increase; S2, based on the key margins for power increase of the first reactor project, on the premise of ensuring safety, with the optimization goal of increasing the rated output of the unit, draw up a general parameter plan for power increase; S3, evaluate the general parameter plan for power increase, and demonstrate the feasibility of the general parameter plan for power increase for the subsequent unit project design.
[0005] In some embodiments of this application, the key margins for power increase of the first reactor project include equipment performance margins and evaluation and analysis margins. These margins are mainly to ensure the smooth implementation of the project to cope with various uncertainties in each link of the project during the first reactor project. Through the specific data obtained from equipment R & D tests, commissioning tests and unit operation stages, these key margins can be comprehensively sorted out and identified as the main basis for power increase.
[0006] In some embodiments of the present application, based on the key margin for power increase in the first reactor project, and on the premise of ensuring safety, with the optimization goal of increasing the rated output of the unit, the formulation of the overall parameter scheme for power increase is carried out, which further includes: redefining the equipment performance according to the equipment performance margin; selecting the variable key parameters for power increase in the overall parameter scheme for power increase to form a search scheme set; using the margin of the evaluation and analysis category, carrying out the stuck condition analysis for the search schemes in the search scheme set, judging whether the search scheme meets the acceptance criteria of the stuck condition analysis, and if so, classifying it into the candidate scheme set; for the candidate schemes in the candidate scheme set, preferably selecting the one with a higher unit output as the formulated overall parameter scheme for power increase.
[0007] In some embodiments of the present application, the equipment performance margin includes the flow resistance margin of the primary loop equipment, the performance margin of the reactor coolant pump, and the thermal performance margin of the steam generator.
[0008] In some embodiments of the present application, the variable key parameters for power increase include the reactor power, the primary loop operating pressure, and the average temperature of the primary loop.
[0009] In some embodiments of the present application, formulating the overall parameter scheme for power increase according to the candidate scheme set further includes: calculating the interface parameters of the primary and secondary loops for each scheme in the candidate scheme set; estimating the rated output of the steam turbine generator set according to the interface parameters of the primary and secondary loops.
[0010] In some embodiments of the present application, in step S3, an impact assessment is carried out on the overall parameter scheme for power increase to demonstrate whether the overall parameter scheme for power increase can be enveloped by the original design, or there are no subversive restrictive factors and it is feasible in engineering, including carrying out impact assessments on the core design, event / accident analysis, radiation shielding analysis, probabilistic safety analysis, equipment design, process system design, and instrument control system design.
[0011] In some embodiments of the present application, the assessment of the core design includes, according to the reactor power increase situation, redesigning the core loading and control rod layout schemes, and carrying out impact assessments on the core thermal-hydraulic analysis and fuel design, etc.
[0012] In some embodiments of the present application, the impact assessment of the event / accident analysis includes carrying out power increase impact assessments on the transient and accident analyses included in the safety analysis report and other conditions required by the power plant license, and carrying out post-accident radioactive consequence and containment performance analyses; at the same time, carrying out impact assessments such as design transient analysis, environmental condition analysis for equipment qualification, fire safety shutdown analysis, spent fuel pool criticality / cooling analysis, and internal flooding analysis of the power plant.
[0013] In some embodiments of the present application, the impact assessment of radiation shielding analysis includes the assessment of neutron fluence in the pressure vessel, the assessment of core source term analysis, the assessment of coolant source term analysis, the assessment of effluent discharge source term analysis, the assessment of post-accident radioactive source term analysis, the shielding analysis during normal operation, and the assessment of cumulative dose of personnel actions after an accident.
[0014] In some embodiments of the present application, the impact assessment of probabilistic safety analysis includes the analysis and assessment of the core damage frequency of the unit and the frequency of large-scale early radioactive release.
[0015] In some embodiments of the present application, the impact assessment of equipment design analysis includes conducting impact analysis on the structural integrity of the main equipment in a nuclear power plant, and the assessment contents include stress, cumulative fatigue factor, pressure change, temperature change, flow change, the break position of high-energy pipelines, and dynamic effects, etc. The integrity analysis of the reactor pressure vessel should also include upper platform energy, pressurized thermal shock, irradiation surveillance tube replacement plan, pressure / temperature limit curve, and low-temperature overpressure protection, etc.
[0016] Compared with the prior art, the present application is applicable to the optimized design of subsequent units after the first-unit project. By making full use of the design margin of the first-unit project, power improvement of the nuclear power plant is carried out on the basis of ensuring safety, thereby further improving the economy of subsequent units and achieving the best balance between safety and economy in the model design. Brief Description of the Drawings
[0017] Including the drawings is to provide a further understanding of the present application. They are incorporated and constitute a part of the present application. The drawings show the embodiments of the present application and, together with this specification, serve to explain the principles of the present application. In the drawings:
[0018] Figure 1 It is a schematic flow chart of a design method for power improvement in an embodiment of the present application. Detailed Embodiments
[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some examples or embodiments of the present application. For those of ordinary skill in the art, without creative efforts, the present application can also be applied to other similar scenarios based on these drawings. Unless obvious from the language context or otherwise stated, the same reference numerals in the figures represent the same structure or operation.
[0020] As shown in this application and the claims, unless the context clearly indicates otherwise, words such as "a", "an", "one", and / or "the" are not specifically singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of the clearly identified steps and elements, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.
[0021] This application refers to Figure 1 A power improvement method 10 (hereinafter referred to as "improvement method 10") is proposed, which is applicable to the optimization design of subsequent units after the first-unit project, and mainly includes steps S1 to S3. Flowcharts are used in this application to illustrate the operations performed by the system according to the embodiments of this application. It should be understood that the previous or subsequent operations do not necessarily need to be executed precisely in order. At the same time, other operations may be added to these processes, or one or more steps may be removed from these processes.
[0022] Specifically, referring to Figure 1 As shown, step S1 of the improvement method 10 is to, based on the design parameters of the first-unit project, combine the data accumulated in each stage of the design, test, commissioning, and operation of the first-unit project, sort out and identify the key margins for power improvement in the first-unit project, as the basis for power improvement. Among them, the key margins for power improvement in the first-unit project include equipment performance margins and evaluation and analysis margins; step S2 is to, based on the key margins for power improvement in the first-unit project, and on the premise of ensuring safety, take the optimization goal of increasing the rated output of the unit, and draw up a general parameter plan for power improvement; step S3 is to evaluate the general parameter plan for power improvement and demonstrate the feasibility of the general parameter plan for power improvement for the subsequent unit project design.
[0023] Now the steps S1 to S3 will be specifically described. First, step S1 of obtaining the key margins for power improvement can be achieved by, on the basis of the original design parameters and characteristics of the first-unit project, combining the experience and data accumulated in each stage of the design, test, commissioning, and operation of the first-unit project, comprehensively sorting out and identifying the key margins available for power improvement in the nuclear power plant for power improvement, and using this as the main basis for power improvement.
[0024] Furthermore, the key margins related to power improvement include equipment performance margins and evaluation and analysis margins. Among them, the equipment performance margin refers to the additional margin considered in equipment design to ensure meeting performance requirements, and the evaluation and analysis margin refers to the additional margin left above the analysis limit in evaluation and analysis.
[0025] Specifically, in the first-unit project, to ensure the performance requirements of nuclear power plants or systems, a relatively large design margin is considered in equipment design. Based on the specific data obtained from equipment R & D tests, commissioning tests, and the unit operation stage, a re-evaluation of the performance of key equipment is carried out to identify the equipment performance margin of these equipment in terms of performance. In this embodiment, the equipment performance margin includes the flow resistance margin of the primary loop equipment, the performance margin of the reactor coolant pump, and the thermal performance margin of the steam generator. In other embodiments of the present application, the equipment performance margin is not limited to the several margins listed above, and the present application does not limit this.
[0026] Furthermore, the flow resistance of the primary loop equipment directly affects the primary loop flow rate. The main equipment in the primary loop includes the reactor pressure vessel, the reactor core, the steam generator, and the main pipeline, etc. Since most of the first-unit models use newly developed equipment, there is often a large uncertainty in estimating the flow resistance of the primary loop equipment. Therefore, a more conservative resistance value is adopted in the design of the first-unit project. In actual application projects, through equipment tests and on-site commissioning operation data analysis, a more accurate flow resistance value of the primary loop equipment can be obtained. The improvement method 10 refers to this flow resistance value to correct the original resistance estimation model, thereby releasing the flow resistance margin of the primary loop equipment, increasing the primary loop flow rate, and providing conditions for power improvement.
[0027] On the other hand, the reactor coolant pump is used to circulate the primary loop working medium. Increasing the flow rate of the reactor coolant pump can extract more heat from the reactor core, which is beneficial to the improvement of the reactor power. To ensure that the primary loop of the first-unit project reaches the expected rated flow rate, a certain margin is generally reserved in the design performance of the reactor coolant pump. Through equipment tests and on-site commissioning operation data analysis, the actual performance of the reactor coolant pump can be obtained. The improvement method 10 can release a certain reactor coolant pump performance margin according to the actual performance of the reactor coolant pump, which can further increase the output power of the reactor coolant pump and increase the primary loop flow rate.
[0028] Furthermore, the steam generator transfers the heat of the primary loop to the secondary loop and heats the main feed water to saturated steam. To ensure that the main steam parameters (pressure, temperature, humidity, etc.) of the first-unit project meet the requirements, a remaining margin is generally reserved in the design of the thermal performance of the steam generator in the first-unit project. The improvement method 10 can review and confirm the thermal performance of the steam generator through equipment tests and on-site commissioning operation data analysis, obtain the actual thermal performance of the steam generator, and release a part of the steam generator thermal performance margin according to the obtained actual thermal performance of the steam generator, thereby increasing the rated parameters of the steam at the outlet of the steam generator (such as the main steam pressure), optimizing the design parameters of the interface between the primary and secondary loops, and improving the efficiency of the steam turbine generator set.
[0029] During the R & D process of the first reactor, design iterations need to be continuously carried out. To ensure that the final design of the nuclear power plant can pass the evaluation and analysis, sufficient margins may be considered in the evaluation and analysis to avoid risks such as the failure of the evaluation and analysis caused by design changes as much as possible. For example, very conservative analysis assumptions are adopted, and a large margin is reserved between the analysis calculation value and the acceptance criterion value. The margins obtained from the evaluation and analysis can be utilized in the subsequent power uprating of the unit to further increase the power of the nuclear reactor. The evaluation and analysis margins include, for example, the margin from the departure from nucleate boiling ratio limit, the margin from the peak temperature limit of the accident cladding, and the margin from the peak pressure / temperature of the accident containment.
[0030] On the other hand, step S2 is to formulate a general parameter scheme for power uprating according to the key margins for power uprating, which may specifically include the following steps:
[0031] First, the equipment performance can be redefined according to the key margins for power uprating. For example, according to the on-site commissioning and operation conditions of the first reactor project, the design resistance of the primary loop can be corrected; the performance margin of the reactor coolant pump can be appropriately released to increase the rated flow rate of the primary loop; the thermal performance margin of the steam generator can be appropriately released, and the rated parameters of the steam at the outlet of the steam generator can be adjusted.
[0032] Secondly, select the variable key parameters for power uprating to form a search scheme set. The key parameters are expressed as: reactor power X 1 , primary loop operating pressure X 2 , primary loop average temperature X 3 … the Nth parameter X n . Define the value ranges of these parameters according to engineering experience, and select the key parameter values at intervals. Let the value set of parameter X 1 be (x 11 , x 12 , …, x 1a ), the value set of parameter X 2 be X 2 = (x 21 , x 22 , …, x 2b ), the value set of parameter X 3 be X 3 = (x 31 , x 32 , …, x 3c ), …, the value set of parameter X n be X n = (x n1 , x n2 , …, x nm ). Arrange and combine the key parameters to form a search scheme set.
[0033] After that, using the evaluation and analysis type margin, the stuck operating condition analysis is carried out for each scheme in the search scheme set to determine whether it meets the acceptance criteria of the stuck operating condition analysis. If it meets, the scheme is included in the candidate scheme set. The identification and determination of the stuck operating condition mainly consider the magnitudes of various margins in the actual first-of-a-kind project, and at the same time, judgment is made in combination with engineering experience. The following are some examples of identifying potential stuck operating conditions. For example, in the original analysis of the steam generator tube rupture accident (SGTR), the overflow margin of the steam generator is small, so the steam generator tube rupture accident is taken as one of the stuck operating conditions; in the original analysis of the loss of reactor coolant accident (LOCA), the margin between the peak containment pressure and the design limit is small, so the LOCA accident is included in the stuck operating condition for analysis.
[0034] According to the candidate scheme set, formulate the overall power increase parameter scheme. This step includes calculating the primary and secondary loop interface parameters of each scheme in the candidate scheme set; estimating the rated output of the steam turbine generator set based on the primary and secondary loop interface parameters; and selecting the candidate scheme with a high rated output of the steam turbine generator set as the formulated overall parameter scheme.
[0035] In this embodiment, step S3 includes evaluating whether the overall power increase parameter scheme can be enveloped by the original design, or there are no subversive restrictive factors and it is feasible in engineering, mainly including impact assessment on core design, event / accident analysis, radiation shielding analysis, probabilistic safety analysis, equipment design, process system design, and instrument control system design. In other embodiments of the present application, step S3 is not limited to evaluating the above types, and the present application does not make any restrictions on this.
[0036] Specifically, the evaluation of the core design includes, according to the reactor power increase situation, re-designing the core loading and control rod layout scheme, and carrying out impact assessment on core thermal-hydraulic analysis and fuel design, etc.
[0037] Furthermore, the impact assessment of event / accident analysis includes carrying out power increase impact assessment on the transients and accident analysis included in the safety analysis report and other operating conditions required by the power plant license, such as anticipated operational occurrences, design basis accidents, design extension conditions, and carrying out post-accident radioactive consequence and containment performance analysis; at the same time, carrying out impact assessment on design transients, environmental conditions analysis for equipment qualification, fire safety shutdown analysis, spent fuel pool criticality / cooling analysis, and internal flooding analysis of the power plant, etc.
[0038] In addition, the impact assessment of radiation shielding analysis includes pressure vessel neutron fluence assessment, core source term analysis assessment, coolant source term analysis assessment, effluent discharge source term analysis assessment, post-accident radioactive source term analysis assessment, normal operation shielding analysis, and post-accident cumulative dose analysis assessment for personnel actions. In other embodiments of the present application, step S3 is not limited to evaluating the above types, and the present application does not make any restrictions on this.
[0039] On the other hand, the impact assessment of probabilistic safety analysis includes the analysis and assessment of the core damage frequency of the unit and the frequency of large-scale early radioactive release. The focus should be on the situations where the successful path or the time window for human intervention changes after the reactor power is increased.
[0040] The impact assessment of equipment design analysis includes the impact analysis of the structural integrity of the main equipment in the nuclear power plant, such as the reactor pressure vessel, in-core components, control rod drive mechanisms, main pipelines, steam generators, reactor coolant pumps, pressurizers, surge pipes, safety-class pipelines, safety-class valves, etc. The integrity analysis of the reactor pressure vessel includes upper platen energy, pressurized thermal shock, replacement plan for irradiation surveillance tubes, pressure / temperature limit curves, and low-temperature overpressure protection, etc. The assessment content of other equipment includes stress, cumulative fatigue factor, pressure change, temperature change, flow change, break position of high-energy pipelines, and dynamic effects, etc.
[0041] Furthermore, the impact assessment of process system design includes the impact analysis of nuclear island process systems and conventional island process systems. Among them, the nuclear island process systems include the reactor coolant system, steam generator system, normal residual heat removal system, chemical and volume control system, steam generator blowdown system, auxiliary feedwater system, primary loop sampling system, containment isolation system, emergency core cooling system, emergency containment cooling system, hydrogen control system, refueling and reshuffling system, equipment cooling water system, plant service water system, HVAC system, radioactive waste treatment system, etc. The conventional island process systems include the main steam system, moisture separator reheater system, condensate system, circulating water system, main feedwater system, main steam turbine system, etc.
[0042] Finally, the impact assessment of the I&C system design includes the impact analysis of the control system, safety and protection system in the nuclear power plant, including reactor power control, pressurizer pressure control, pressurizer level control, steam generator feedwater control, power reduction control, etc. At the same time, the analysis of the set values of the reactor trip protection system and the trigger set values of the engineered safety feature systems should also be carried out.
[0043] This application is applicable to the optimization design of subsequent units after the first unit project. By making full use of the design margin of the first unit project, a search scheme set is formed through the permutation and combination of key parameters, and the total parameter scheme for power increase is formulated with the analysis of stuck conditions combined with the unit output estimation as the criterion. Then, the evaluation and analysis are carried out for the formulated total parameter scheme to demonstrate the feasibility of the scheme. Based on ensuring safety, the power of the nuclear power plant is increased, thereby further improving the economy of subsequent units and achieving the best balance between safety and economy in the model design.
[0044] The basic concepts have been described above. Obviously, for those skilled in the art, the above application disclosure is only an example and does not constitute a limitation to this application. Although not explicitly stated here, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are proposed in this application, so such modifications, improvements, and corrections still fall within the spirit and scope of the exemplary embodiments of this application.
[0045] Meanwhile, this application uses specific terms to describe the embodiments of this application. Such as "one embodiment", "an embodiment", and / or "some embodiments" mean a certain feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that the "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more at different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application can be appropriately combined. Similarly, it should be noted that, in order to simplify the expression of this application disclosure and thus help the understanding of one or more application embodiments, in the previous description of the embodiments of this application, sometimes multiple features are merged into one embodiment, drawing, or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than those mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiments disclosed above.
[0046] In some embodiments, numbers are used to describe the components and the quantity of attributes. It should be understood that such numbers used for the description of embodiments are, in some examples, modified by the modifiers "about", "approximate", or "substantially". Unless otherwise stated, "about", "approximate", or "substantially" indicate that the said numbers allow a variation of ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, and such approximate values may change according to the characteristics required by individual embodiments. In some embodiments, the numerical parameters should consider the specified significant digits and adopt the method of retaining the general number of digits. Although the numerical ranges and parameters used to confirm the breadth of the scope in some embodiments of this application are approximate values, in specific embodiments, the setting of such numerical values is as precise as possible within the feasible range.
[0047] Although this application has been described with reference to the current specific embodiments, those of ordinary skill in the art should recognize that the above embodiments are only used to illustrate this application, and various equivalent changes or substitutions can be made without departing from the spirit of this application. Therefore, as long as the changes and variations of the above embodiments are within the scope of the spirit of this application, they will fall within the scope of the claims of this application.
Claims
1. A design method for power upgrade of a nuclear power plant, which is applicable to the optimization design of subsequent units after the first reactor project, and is characterized by: The steps include: S1, based on the design parameters of the first reactor project and combined with the data accumulated in the test, commissioning and operation stages of the first reactor project, sort out and identify the key margins for power increase of the first reactor project as the basis for power increase; S2: Based on the key margin of power increase for the first reactor project, and on the premise of ensuring safety, with increasing the rated output of the unit as the optimization goal, formulate a total power increase parameter plan; S3, evaluate the overall power increase parameter scheme, demonstrate the feasibility of the overall power increase parameter scheme, and use it for the subsequent unit engineering design.
2. The design method according to claim 1, characterized in that: The key margins for increasing the power of the first reactor project include equipment performance margin and evaluation and analysis margin.
3. The design method according to claim 2, characterized in that: Based on the key margin of power increase for the first reactor project, and with the optimization goal of increasing the rated output of the unit under the premise of ensuring safety, the proposed total power increase parameter plan further includes: redefine device performance according to the device performance margin; Selecting power boost variable key parameters in the power boost total parameter scheme to form a search scheme set; Conduct a stuck condition analysis on each solution in the search solution set to determine whether it meets the stuck condition analysis acceptance criteria. If so, include it in the candidate solution set. The power boost total parameter scheme is formulated according to the candidate scheme set.
4. The design method according to claim 3, characterized in that: Formulating the power boost total parameter scheme according to the candidate scheme set further includes: Calculate the primary and secondary loop interface parameters of each candidate solution; Estimating the rated output of the steam turbine generator set of each candidate solution according to the primary and secondary circuit interface parameters; The candidate solution with a higher rated output of the steam turbine generator set is selected as the overall parameter solution for the power increase.
5. The design method according to claim 2, characterized in that: The equipment performance margin includes a primary circuit equipment flow resistance margin, a reactor coolant pump performance margin, and a steam generator thermal performance margin.
6. The design method according to claim 3, characterized in that: The power-boosting variable key parameters include reactor power, primary circuit operating pressure, and primary circuit average temperature.
7. The design method according to claim 1, characterized in that: In step S3, the overall power enhancement parameter scheme is evaluated to demonstrate the feasibility of the overall power enhancement parameter scheme, including analysis and evaluation of core design, event / accident analysis, radiation shielding analysis, probabilistic safety analysis, equipment design, process system design and instrumentation and control system design.
8. The design method according to claim 7, characterized in that: The core loading and control rod arrangement schemes were redesigned, and the core thermal-hydraulic analysis and fuel design were analyzed and evaluated.
9. The design method according to claim 7, characterized in that: The impact assessment on radiation shielding analysis includes pressure vessel neutron injection assessment, core source term analysis assessment, coolant source term analysis assessment, effluent emission source term analysis assessment, post-accident radioactive source term analysis assessment, normal operation shielding analysis and post-accident personnel action cumulative dose analysis assessment.
10. The design method according to claim 7, characterized in that: The impact assessment of the instrumentation and control system design includes analysis and assessment of reactor power control, pressurizer pressure control, pressurizer level control, steam generator feed water control, power reduction control, shutdown protection system setting values, and dedicated safety facility system triggering setting values.