Nuclear island system seawater high temperature influence analysis method and medium

Abstract

The invention discloses a nuclear island system seawater high temperature influence analysis method and a medium, and the method comprises the following steps: S1, obtaining the historical data of the inlet seawater temperature of a heat exchanger during the operation of a nuclear island system, inputting the inlet seawater temperature historical data into a seawater temperature prediction model, and calculating to obtain a new seawater design temperature and a new seawater maximum temperature; and S2, inputting the new seawater design temperature and the new seawater maximum temperature into the analysis model to obtain a model analysis result, and comprehensively evaluating based on the model analysis result to obtain a seawater high temperature influence analysis result. The new seawater design temperature and the new seawater maximum temperature are input into the analysis model, the seawater high temperature influence is analyzed, the nuclear island system is prevented from influencing heat brought out due to the rising of the inlet seawater temperature, and safe and stable operation of the nuclear island system is ensured.

Description

Technical Field

[0001] This invention relates to the field of nuclear power operation technology, and in particular to a method and medium for analyzing the effects of high temperature on seawater in nuclear island systems. Background Technology

[0002] Global temperatures are rising significantly, and ocean surface temperatures are also on a continuous upward trend. In recent years, seawater temperatures at nuclear power plants have increased markedly compared to the original design phase. As the final cold source for removing heat from the reactor core, seawater temperature changes impact the safety and operation of the units. Rising seawater temperatures lead to increased temperatures in various power plant buildings, deteriorating the operating environment of high-temperature-sensitive electromechanical equipment in the nuclear island system. This increases the likelihood of equipment malfunctions in the nuclear island system, posing a threat to the safe and stable operation of the nuclear power units. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method and medium for analyzing the effects of high temperature on seawater in a nuclear island system, addressing at least one deficiency in the related technologies mentioned in the background section.

[0004] The technical solution adopted by this invention to solve its technical problem is: to construct a method for analyzing the impact of high temperature on seawater in a nuclear island system, the method comprising the following steps: S1: Obtain historical data of the inlet seawater temperature of the heat exchanger during the operation of the nuclear island system, and input the historical data of the inlet seawater temperature into the seawater temperature prediction model to calculate the new seawater design temperature and the new seawater maximum temperature; S2: Input the design temperature and maximum temperature of the new seawater into the analysis model to obtain the model analysis results, and then comprehensively evaluate the impact of high temperature on seawater based on the model analysis results to obtain the analysis results of the impact of high temperature on seawater.

[0005] In some embodiments, the heat exchanger is a heat exchanger for an important plant water system.

[0006] In some embodiments, the method further includes, before step S2: obtaining the equipment parameters and operating parameters of the nuclear island system; The method for establishing the analysis model includes: establishing the analysis model based on equipment parameters and operating parameters using a preset method.

[0007] In some embodiments, the analysis model includes: a heat transfer coefficient verification model; Step S2 includes: obtaining the heat transfer efficiency under different operating conditions based on the design temperature of the new seawater, and inputting the heat transfer efficiency under different operating conditions into the heat transfer coefficient verification model to obtain the heat exchanger margin calculation results.

[0008] In some embodiments, the method for obtaining the heat transfer efficiency under different operating conditions is as follows: The system acquires operational data of the nuclear island system under different operating conditions, and establishes thermal-hydraulic models under different operating conditions based on the operational data. The design temperature of the new seawater is input into the thermal-hydraulic models under different operating conditions to obtain the heat transfer efficiency under different operating conditions.

[0009] In some embodiments, the analysis model further includes: a normal power operation condition model; Step S2 further includes: obtaining the downstream outlet temperature of the cooling water side under normal power operation conditions based on the new seawater design temperature, and inputting the downstream outlet temperature of the cooling water side into the normal power operation condition model to obtain the downstream margin calculation result of the equipment cooling water side.

[0010] In some embodiments, the analysis model further includes: a waste heat removal system shutdown condition model; Step S2 further includes: based on the design temperature input of the new seawater to the shutdown condition model of the waste heat removal system, obtaining the cooling time of the first loop to the preset temperature under different operating conditions.

[0011] In some embodiments, the analysis model further includes: an accident condition model; Step S2 further includes: inputting the highest temperature of the new seawater into the accident condition model to obtain the accident analysis results.

[0012] In some embodiments, step S2, the comprehensive evaluation based on model analysis results includes: comprehensively evaluating the heat exchanger margin calculation results, the downstream margin calculation results on the equipment cooling water side, the seawater cooling time under different waste heat discharge system influence conditions, and the accident analysis results.

[0013] The present invention also constructs a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the method for analyzing the effects of high-temperature seawater on nuclear island systems as described in any of the above embodiments.

[0014] By implementing this invention, the following beneficial effects are achieved: This invention first acquires historical data on the inlet seawater temperature of the heat exchangers in the important plant water system during the operation of the nuclear island system. Based on this historical data, it inputs the seawater temperature prediction model to calculate the new seawater design temperature and the new seawater maximum temperature. Then, it inputs the new seawater design temperature and the new seawater maximum temperature into the analysis model to obtain the model analysis results. Based on the model analysis results, it comprehensively evaluates and obtains the seawater high temperature impact analysis results. By inputting the calculated new seawater temperature into the analysis model, the impact of seawater high temperature is analyzed to prevent the nuclear island system from being affected by heat loss due to rising seawater temperature, thus ensuring the safe and stable operation of the nuclear island system. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 A flowchart of one embodiment of the method for analyzing the effects of high-temperature seawater on nuclear island systems according to the present invention is shown; Figure 2 The flowchart illustrates an embodiment of the analysis method for analyzing the impact of high-temperature seawater on nuclear island systems according to the present invention, showing the input analysis model for the design temperature and maximum temperature of new seawater. Detailed Implementation

[0016] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0017] It should be noted that the flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0018] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0019] like Figure 1 As shown, this invention constructs a method for analyzing the impact of high-temperature seawater on nuclear island systems. This method includes the following steps: S1: Obtain historical data of the inlet seawater temperature of the heat exchanger during the operation of the nuclear island system, and input the historical data of the inlet seawater temperature into the seawater temperature prediction model to calculate the new seawater design temperature and the new seawater maximum temperature; S2: Input the design temperature and maximum temperature of the new seawater into the analysis model to obtain the model analysis results, and then comprehensively evaluate the impact of high temperature on seawater based on the model analysis results to obtain the analysis results of the impact of high temperature on seawater.

[0020] This invention acquires historical data on the inlet seawater temperature of the heat exchangers in the nuclear island system. For example, if the nuclear island system has been operating for ten years, then historical data on the inlet seawater temperature of all heat exchangers over those ten years are acquired. The new seawater design temperature is the historical average of the annual average seawater temperature in the plant site area, selected from a ranking of the annual average seawater temperatures after the nuclear power plant has been operating for a long time. For example, the historical average of the seventh highest daily average seawater temperature in each year. The new seawater maximum temperature refers to the highest seawater temperature in the plant site area after the nuclear power plant has been operating for a long time; for example, the highest seawater temperature reached after ten years of operation is the new seawater maximum temperature. This invention uses historical data on the inlet seawater temperature of the heat exchangers as input to an analysis model to calculate the new seawater design temperature and the new seawater maximum temperature, analyzes the impact on the nuclear island system, prevents the nuclear island system from being affected by rising seawater temperatures, thus ensuring the safe and stable operation of the nuclear island system.

[0021] The purpose of seawater temperature prediction models is to calculate the design temperature and maximum temperature of new seawater. Seawater temperature prediction models include statistical models, such as Günbel analysis or Pearson type III frequency curve analysis, and can also use three-dimensional hydrodynamic methods for nuclear power plant sea areas.

[0022] In some embodiments, the heat exchanger is a heat exchanger for an important plant water system.

[0023] The critical plant water system is the SEC system. The inlet seawater temperature of the SEC system heat exchanger directly affects the heat exchanger's heat exchange capacity. Moreover, the seawater here is turbided by the SEC pump, so there is no need to consider the temperature difference between the surface, middle and bottom layers of the seawater, nor the impact of the thermal backflow of the nuclear island system of the nuclear power plant.

[0024] The SEC / RRI heat exchanger is a heat exchange device that transfers heat from the closed RRI loop of the nuclear island system to the open SEC seawater loop, thereby discharging the heat load of the nuclear island system to the sea. The SEC / RRI heat exchanger includes: SEC side (important plant water system): open circulation, where filtered seawater enters the heat exchanger, carrying away RRI heat and discharging it back to the sea, serving as a cold source; and RRI side (equipment cooling water system): closed demineralized water circulation, which carries heat from various equipment in the nuclear island system (main pumps, heat exchangers, chillers, etc.) to the SEC / RRI heat exchanger, serving as a heat source.

[0025] In some embodiments, the method further includes obtaining the equipment parameters and operating parameters of the nuclear island system before step S2; The methods for establishing the analysis model include: establishing the analysis model based on equipment parameters and operating parameters through preset methods; the preset methods include at least one or more of the following: Günbel analysis, Pearson frequency curve analysis, and three-dimensional fluid dynamics methods.

[0026] The equipment parameters are the design baselines for the nuclear island system equipment in a nuclear power plant, while the operating parameters are the operating limitations of the nuclear island system. These mainly include the design temperature of the seawater, the maximum seawater temperature, the RRI supply water temperature of the equipment cooling water system, the power operating design values, the seasons with high seawater temperatures, the nuclear island system affected by seawater temperature, the functions of the nuclear island system equipment, equipment composition, safety classification, parameters, monitoring instruments, and temperature alarm values ​​(T). limit Operating conditions, heat transfer coefficient Ks of SEC / RRI heat exchanger limit wait.

[0027] like Figure 2 As shown, in some embodiments, the analysis model includes: a heat transfer coefficient verification model; Step S2 includes: obtaining the heat transfer efficiency under different operating conditions based on the design temperature of the new seawater, and inputting the heat transfer efficiency under different operating conditions into the heat transfer coefficient verification model to obtain the heat exchanger margin calculation results.

[0028] In some embodiments, the method for obtaining heat transfer efficiency under different operating conditions is as follows: The system acquires operational data of the nuclear island system under different operating conditions, and establishes thermal-hydraulic models under different operating conditions based on the operational data. The design temperature of the new seawater is input into the thermal-hydraulic models under different operating conditions to obtain the heat transfer efficiency under different operating conditions.

[0029] The different operating conditions include at least five conditions: startup condition, normal operation condition, cold shutdown condition (4-20 hours after shutdown), cold shutdown condition (20 hours after shutdown), and subcritical shutdown condition. Thermal-hydraulic models of the SEC / RRI heat exchanger are established for each of the five conditions. Based on the new seawater design temperature obtained above, the heat transfer coefficient Ks for each of the five conditions is calculated using these thermal-hydraulic models. new Its unit is MW / ℃.

[0030] The heat transfer coefficient verification model is a heat transfer coefficient verification model for SEC / RRI heat exchangers, which verifies the heat transfer coefficient Ks under five operating conditions. new Inputting the data into the heat transfer coefficient verification model yields the margin for the SEC / RRI heat exchanger. The calculation method for the heat transfer coefficient verification model is (Ks...). limit -Ks new ) / Ks limit *100%, Ks limit The heat transfer coefficient of the SEC / RRI heat exchanger is defined under the design baseline of the nuclear island system equipment in a nuclear power plant. When the margin of the SEC / RRI heat exchanger under a certain operating condition is less than 15%, the SEC / RRI heat exchanger is in a weak point and needs to be optimized.

[0031] In some embodiments, the analysis model further includes: a normal power operating condition model; The normal power operating condition model is a thermo-hydraulic model for all downstream users of the RRI cooling water system under normal power operating conditions. The thermo-hydraulic models of all downstream equipment under the RRI cooling water system are analyzed under normal power operating conditions. The design temperature of the new seawater is input into the thermo-hydraulic models of all downstream equipment under the RRI cooling water system under normal power operating conditions, and the outlet temperature T on the hot side of each downstream equipment is calculated. hot_new The outlet temperature of the downstream equipment of the RRI cooling water system is input into the normal power operating condition model to obtain the margin of the downstream equipment of the RRI cooling water system; the calculation method of the normal power operating condition model is: (T limit -T hot_new ) / T limit *100%, T limi The temperature alarm value for the nuclear island system equipment is such that when the margin of the downstream equipment of the equipment cooling water system RRI is less than the preset threshold, for example, less than 5%, the nuclear island system equipment is in a weak link under normal power operation conditions, and the downstream equipment of the equipment cooling water system RRI needs to be optimized and improved.

[0032] In some embodiments, the analysis model further includes: a waste heat removal system shutdown condition model; Step S2 also includes: based on the design temperature input of the new seawater to the shutdown condition model of the waste heat removal system, obtaining the cooling time of the first loop to the preset temperature under different operating conditions.

[0033] The shutdown operation is used for shutdown cooling and consists of two phases. In the first phase, the reactor coolant system (RCP) is cooled by steam venting from the secondary side of the steam generator. The cooling sequence is: core -> steam venting -> RCP -> steam generator -> atmospheric vent valve. In the second phase, when the temperature and pressure of the RCP decrease to 177°C and 28 bar abs respectively, the residual heat removal system (RRA) is activated to continue cooling the RCP. The cooling sequence is: core -> steam venting -> RRA -> RRI -> SEC (Secure and Renewable Energy System) -> ocean. Reactor residual heat and primary loop sensible heat are transferred to the RRI via the RRA heat exchanger, and then transferred to the SEC via the RRI heat exchanger. Finally, the heat is carried away by seawater. The theoretical basis of the residual heat removal system shutdown condition model is the heat balance equation, which includes the heat transfer process from the steam exhaust cooling reactor coolant system RCP to the residual heat removal system RRA, the heat transfer process of the residual heat removal system RRA heat exchanger, the heat transfer process of the equipment cooling water system RRI heat exchanger, and the heat transfer process from the important plant water system SEC to seawater.

[0034] The analysis of the operating conditions of the waste heat removal system (RRA) includes: dual-pump operation, single-pump operation, and complete failure of the RRA. The cooling time (t) for the first loop to cool down to the preset temperature (e.g., 90°C) under each operating condition is calculated using the design temperature of the new seawater. cold If the cooling time t is used to reduce the temperature to 90℃ under each operating condition, then... cold If the time exceeds 36 hours, the waste heat removal system (RRA) is considered a weak link, and the RRA equipment needs to be optimized and improved.

[0035] In some embodiments, the analysis model further includes: an accident condition model; Step S2 also includes: inputting the highest temperature of the new seawater into the accident condition model to obtain the accident analysis results.

[0036] The design baseline accident condition analysis model of nuclear island system equipment in nuclear power plants is reviewed, such as loss of coolant accident. The highest temperature of fresh seawater is input to calculate the analysis results of each accident. The analysis results of each accident are calculated to see if they meet the corresponding verification criteria. If they do not meet the verification criteria, the dedicated safety system equipment is optimized and improved.

[0037] This application distinguishes between inputting the design temperature and the maximum temperature of the new seawater into different analytical models. Specifically, it inputs the design temperature of the new seawater into the heat transfer coefficient verification model, the normal power operation model, and the residual heat removal system shutdown model to identify any weaknesses in the SEC / RRI heat exchanger, downstream equipment of the RRI cooling water system, and RRA equipment of the residual heat removal system when the overall seawater temperature rises. Meanwhile, it inputs the maximum temperature of the new seawater into the accident operation model to identify various accidents that may occur when the seawater temperature rises to its maximum value, i.e., the worst-case scenario. This ensures the safe and stable operation of the nuclear island system and guarantees reactor safety through equipment optimization and accident prevention.

[0038] In some embodiments, step S2, the comprehensive evaluation based on model analysis results includes: comprehensively evaluating the heat exchanger margin calculation results, the downstream margin calculation results on the equipment cooling water side, the seawater cooling time under different waste heat discharge system influence conditions, and the accident analysis results.

[0039] Based on the heat exchanger margin calculation results, equipment cooling water downstream margin calculation results, seawater cooling time under different waste heat discharge system operating conditions, and accident analysis results obtained from the above embodiments, the impact analysis results of the new seawater design temperature and the new seawater maximum temperature on the nuclear island system equipment are obtained, and a high-temperature seawater improvement scheme is formulated to avoid the one-sidedness of independent improvement analysis.

[0040] This invention calculates the design temperature and maximum temperature of the new seawater by acquiring historical data of the inlet seawater temperature, and inputs these data into various analysis models to conduct a full-process analysis of the impact of high-temperature new seawater on the nuclear island system. This yields a comprehensive analysis result of the impact of high-temperature new seawater. Furthermore, it proposes a model evaluation method to prevent the nuclear power plant from reducing its design margin due to rising cold source temperatures after long-term operation, and to prevent the nuclear island system from being affected by heat transfer due to rising new seawater temperatures. This ensures the safe and stable operation of the nuclear island system and guarantees reactor safety.

[0041] The present invention also constructs a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the method for analyzing the effects of high-temperature seawater on nuclear island systems as described in any of the above embodiments.

[0042] It is understood that the above embodiments only illustrate some implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above embodiments or technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. That is, the embodiments described "in some embodiments" can be freely combined with any of the preceding and following embodiments. Therefore, all equivalent transformations and modifications made within the scope of the claims of the present invention should be covered by the claims of the present invention.

Claims

1. A method of analyzing a high-temperature influence of seawater on a nuclear island system, characterized by, The method comprises the following steps: S1: obtaining the inlet seawater temperature historical data of the heat exchanger during the operation of the nuclear island system, and inputting the inlet seawater temperature historical data into a seawater temperature prediction model to obtain a new seawater design temperature and a new seawater maximum temperature; S2: inputting the new seawater design temperature and the new seawater maximum temperature into an analysis model to obtain a model analysis result, and obtaining a seawater high-temperature influence analysis result based on the model analysis result.

2. The nuclear island system seawater high temperature influence analysis method according to claim 1, characterized by, The heat exchanger is an important plant water system heat exchanger.

3. The nuclear island system seawater high temperature influence analysis method according to claim 1, characterized by, The step S2 further comprises: obtaining the device parameters and the operation parameters of the nuclear island system; The method for establishing the analysis model comprises: establishing the analysis model by a preset method based on the device parameters and the operation parameters.

4. The nuclear island system seawater high temperature influence analysis method according to claim 1, characterized by, The analysis model comprises: a heat exchange coefficient checking model; The step S2 comprises: obtaining the heat transfer efficiency under different working conditions based on the new seawater design temperature, and inputting the heat transfer efficiency under different working conditions into the heat exchange coefficient checking model to obtain a heat exchanger margin calculation result.

5. The nuclear island system seawater high temperature influence analysis method according to claim 4, characterized by, The method for obtaining the heat transfer efficiency under different working conditions is: Obtaining the operation data of the nuclear island system under different working conditions, and establishing a thermal hydraulic model under different working conditions based on the operation data under different working conditions, and inputting the new seawater design temperature into the thermal hydraulic model under different working conditions to obtain the heat transfer efficiency under different working conditions.

6. The nuclear island system seawater high temperature influence analysis method according to claim 4, characterized by, The analysis model further comprises: a normal power operation working condition model; The step S2 further comprises: obtaining the outlet temperature downstream of the cooling water side based on the new seawater design temperature under the normal power operation working condition, and inputting the outlet temperature downstream of the cooling water side into the normal power operation working condition model to obtain a device cooling water side downstream margin calculation result.

7. The nuclear island system seawater high temperature influence analysis method according to claim 6, characterized by, The analysis model further comprises: a residual heat removal system shutdown working condition model; The step S2 further comprises: inputting the new seawater design temperature into the residual heat removal system shutdown working condition model to obtain the cooling time of the primary loop to a preset temperature under different working conditions.

8. The nuclear island system seawater high temperature influence analysis method according to claim 7, characterized by, The analysis model further comprises: an accident working condition model; The step S2 further comprises: inputting the new seawater maximum temperature into the accident working condition model to obtain an accident analysis result.

9. The nuclear island system seawater high temperature influence analysis method according to claim 8, characterized by, In the step S2, the comprehensive evaluation based on the model analysis result comprises: comprehensive evaluation of the heat exchanger margin calculation result, the device cooling water side downstream margin calculation result, the seawater cooling time under different residual heat removal system influence working conditions, and the accident analysis result.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to realize the nuclear island system seawater high-temperature influence analysis method according to any one of claims 1-9.

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