Scheduled maintenance and condition-based online monitoring are among the focal points of recent research to enhance nuclear plant safety.One of the most effective ways to monitor plant conditions is by implementing a...Scheduled maintenance and condition-based online monitoring are among the focal points of recent research to enhance nuclear plant safety.One of the most effective ways to monitor plant conditions is by implementing a full-scope,plant-wide fault diagnostic system.However,most of the proposed diagnostic techniques are perceived as unreliable by operators because they lack an explanation module,their implementation is complex,and their decision/inference path is unclear.Graphical formalism has been considered for fault diagnosis because of its clear decision and inference modules,and its ability to display the complex causal relationships between plant variables and reveal the propagation path used for fault localization in complex systems.However,in a graphbased approach,decision-making is slow because of rule explosion.In this paper,we present an enhanced signed directed graph that utilizes qualitative trend evaluation and a granular computing algorithm to improve the decision speed and increase the resolution of the graphical method.We integrate the attribute reduction capability of granular computing with the causal/fault propagation reasoning capability of the signed directed graph and comprehensive rules in a decision table to diagnose faults in a nuclear power plant.Qualitative trend analysis is used to solve the problems of fault diagnostic threshold selection and signed directed graph node state determination.The similarity reasoning and detection ability of the granular computing algorithm ensure a compact decision table and improve the decision result.The performance of the proposed enhanced system was evaluated on selected faults of the Chinese Fuqing 2 nuclear reactor.The proposed method offers improved diagnostic speed and efficient data processing.In addition,the result shows a considerable reduction in false positives,indicating that the method provides a reliable diagnostic system to support further intervention by operators.展开更多
Oil cleaning agents generated from nuclear power plants(NPPs)are radioactive organic liquid wastes.To date,because there are no satisfactory industrial treatment measures,these wastes can only be stored for a long tim...Oil cleaning agents generated from nuclear power plants(NPPs)are radioactive organic liquid wastes.To date,because there are no satisfactory industrial treatment measures,these wastes can only be stored for a long time.In this work,the optimization for the supercritical water oxidation(SCWO)of the spent organic solvent was investigated.The main process parameters of DURSET(oil cleaning agent)SCWO,such as temperature,reaction time,and excess oxygen coefficient,were optimized using response surface methodology,and a quadratic polynomial model was obtained.The determination coefficient(R^(2))of the model is 0.9812,indicating that the model is reliable.The optimized process conditions were at 515 C,66 s,and an excess oxygen coefficient of 211%.Under these conditions,the chemical oxygen demand removal of organic matter could reach 99.5%.The temperature was found to be the main factor affecting the SCWO process.Ketones and benzene-based compounds may be the main intermediates in DURSET SCWO.This work provides basic data for the industrialization of the degradation of spent organic solvents from NPP using SCWO technology.展开更多
Visual inspection of the key components of nuclear power plants(NPPs)is important for NPP operation and maintenance. However,the underwater environment and existing radiation will lead to image degradation,thus making...Visual inspection of the key components of nuclear power plants(NPPs)is important for NPP operation and maintenance. However,the underwater environment and existing radiation will lead to image degradation,thus making it difficult to identify surface defects. In this study,a method for improving the quality of underwater images is proposed.By analyzing the degradation characteristics of underwater detection image,the image enhancement technology is used to improve the color richness of the image,and then the improved dark channel prior(DCP)algorithm is used to restore it. By modifying the estimation formula of transmittance and background light,the correction of insufficient brightness in DCP restored image is realized. The proposed method is compared with other state-of-the-art methods. The results show that the proposed method can achieve higher scores and improve the image quality by correcting the color and restoring local details,thus effectively enhancing the reliability of visual inspection of NPPs.展开更多
The nuclear power plant is suitable for base-load operation, while the pumped-storage unit mainly gives play to capacity benefit in the electric power system;hence, the integrated development and hybrid operation mode...The nuclear power plant is suitable for base-load operation, while the pumped-storage unit mainly gives play to capacity benefit in the electric power system;hence, the integrated development and hybrid operation mode of the two can better meet the needs of the electric power system. This article first presents an analysis of the necessity and superiority of such mode, then explains its meaning and analyzes the working routes. Finally, it proposes the business modes as follows: low price pumping water electricity plus nuclear power in the near term;nuclear power shifted to pumped storage power participating in market competition in the middle term;and, in the long term, nuclear power shifted to pumped storage power as primary and serving as an electric power system when needed.展开更多
Fault diagnostics is important for safe operation of nuclear power plants(NPPs). In recent years, data-driven approaches have been proposed and implemented to tackle the problem, e.g., neural networks, fuzzy and neuro...Fault diagnostics is important for safe operation of nuclear power plants(NPPs). In recent years, data-driven approaches have been proposed and implemented to tackle the problem, e.g., neural networks, fuzzy and neurofuzzy approaches, support vector machine, K-nearest neighbor classifiers and inference methodologies. Among these methods, dynamic uncertain causality graph(DUCG)has been proved effective in many practical cases. However, the causal graph construction behind the DUCG is complicate and, in many cases, results redundant on the symptoms needed to correctly classify the fault. In this paper, we propose a method to simplify causal graph construction in an automatic way. The method consists in transforming the expert knowledge-based DCUG into a fuzzy decision tree(FDT) by extracting from the DUCG a fuzzy rule base that resumes the used symptoms at the basis of the FDT. Genetic algorithm(GA) is, then, used for the optimization of the FDT, by performing a wrapper search around the FDT: the set of symptoms selected during the iterative search are taken as the best set of symptoms for the diagnosis of the faults that can occur in the system. The effectiveness of the approach is shown with respect to a DUCG model initially built to diagnose 23 faults originally using 262 symptoms of Unit-1 in the Ningde NPP of the China Guangdong Nuclear Power Corporation. The results show that the FDT, with GA-optimized symptoms and diagnosis strategy, can drive the construction of DUCG and lower the computational burden without loss of accuracy in diagnosis.展开更多
It is necessary to develop an automatic fault diagnosis system to avoid a possible nuclear disaster caused by an inaccurate fault diagnosis in the nuclear power plant by the operator. Because Radial Basis Function Neu...It is necessary to develop an automatic fault diagnosis system to avoid a possible nuclear disaster caused by an inaccurate fault diagnosis in the nuclear power plant by the operator. Because Radial Basis Function Neural Network (RBFNN) has the characteristics of optimal approximation and global approximation. The mixed coding of binary system and decimal system is introduced to the structure and parameters of RBFNN, which is trained in course of the genetic optimization. Finally, a fault diagnosis system according to the frequent faults in condensation and feed water system of nuclear power plant is set up. As a result, Genetic-RBF Neural Network (GRBFNN) makes the neural network smaller in size and higher in generalization ability. The diagnosis speed and accuracy are also improved.展开更多
A nuclear power plant real-time engineering simulator was developed based on general-purpose ther- mal-hydraulic system simulation code RELAP5. It mainly consists of three parts:improved thermal-hydraulic system simul...A nuclear power plant real-time engineering simulator was developed based on general-purpose ther- mal-hydraulic system simulation code RELAP5. It mainly consists of three parts:improved thermal-hydraulic system simulation code RELAP5,control and protection system and human-machine interface. A normal transient of CHASHMA nuclear power plant turbine step load change from 100% to 90% of full power,was simulated by the en- gineering simulator as an application example. This paper presents structure and main features of the engineering simulator,and application results are shown and discussed.展开更多
The purpose of this study is to establish an intelligent expert system for nuclear power plant emergency response.A new framework of environmental risk management methodology by the concept of pattern recognition was ...The purpose of this study is to establish an intelligent expert system for nuclear power plant emergency response.A new framework of environmental risk management methodology by the concept of pattern recognition was introduced in this paper.A knowledge-based decision support system for emergency response and risk management of nuclear power plant was also discussed.The mathematical pattern relationship of accidental release effects on neighboring area and the corresponding response measures were presented in this paper.With this decision system,the decision maker can specify the procedure and minimize their human error in the decision process.The improvement of risk response and the quality of management system could be upgraded by this system.Besides,the methodology can also be served as a basis for the future development of environmental risk response system design.展开更多
A quantitative environmental assessment method and the corresponding computer code are introduced in this paper. By the consideration of all fuel cycle steps,it gives that the public health risk of China nuclear power...A quantitative environmental assessment method and the corresponding computer code are introduced in this paper. By the consideration of all fuel cycle steps,it gives that the public health risk of China nuclear power industry is 5.2 × 10-1 man /(GW.a), the occupational health risk is 2.5 man /(GW.a), and the total health risk is 3.0 man /(GW.a). After the health risk calculation for coal mining, transport, burning up and ash disposal, it gives that the public health risk of China coal-fired power industry is 3.6mall/(GW-a), the occupational health risk is 50man /(GW.a), and the total is 54man /(GW.d). Accordingly, the conclusion that China nuclear power industry is an industry with high safety and cleanness is derived at the end.展开更多
This study presents a probabilistic safety analysis(PSA)method for the external event of extreme snowfall on a floating nuclear power plant(FNPP)deployed in the Bohai Sea.We utilized the Weibull and Gumbel extreme val...This study presents a probabilistic safety analysis(PSA)method for the external event of extreme snowfall on a floating nuclear power plant(FNPP)deployed in the Bohai Sea.We utilized the Weibull and Gumbel extreme value distributions to fit the collected meteorological data and obtained a hazard curve for the event of an extreme snowfall where the FNPP is located,providing a basis for the frequency of extreme snowfall-initiating events.Our analysis indicates that extreme snowfall primarily affects the ventilation openings of the equipment,leading to the failure of devices such as the diesel generators.Additionally,extreme snowfall can result in a loss of off-site power(LOOP).Therefore,the developed extreme snowfall PSA model is mainly based on the LOOP event tree,considering responses such as snowfall removal by personnel.Our calculations indicate a core damage frequency(CDF)of 1.13×10^(-10) owing to extreme snowfall,which is relatively low.The results of the cut-set analysis indicate that valve failures in the core makeup tank(CMT),passive residual heat removal system(PRS),and in-containment refueling water storage tank(IRWST)significantly contribute to the CDF.展开更多
The fuzzy logic and neural networks are combined in this paper, setting upthe fuzzy neural network (FNN ) ; meanwhile, the distinct differences and connections between thefuzzy logic and neural network are compared. F...The fuzzy logic and neural networks are combined in this paper, setting upthe fuzzy neural network (FNN ) ; meanwhile, the distinct differences and connections between thefuzzy logic and neural network are compared. Furthermore, the algorithm and structure of the FNN areintroduced. In order to diagnose the faults of nuclear power plant, the FNN is applied to thenuclear power planl, and the intelligence fault diagnostic system of the nuclear power plant isbuilt based on the FNN . The fault symptoms and the possibility of the inverted U-tube breakaccident of steam generator are discussed. In order to test the system' s validity, the invertedU-tube break accident of steam generator is used as an example and many simulation experiments areperformed. The test result shows that the FNN can identify the fault.展开更多
A plan of surveillance monitoring Qinshan Nuclear Power Plant (QNPP) has been implemented since 1992, the objective of which is to establish the database of environmental radiation information around QNPP, and to dete...A plan of surveillance monitoring Qinshan Nuclear Power Plant (QNPP) has been implemented since 1992, the objective of which is to establish the database of environmental radiation information around QNPP, and to detect any unplanned discharge of radioactive materials from QNPP. This paper presents the monitoring results for radionuclide concentrations in the environmental matrices before and after QNPP operation. The radionuclide con- centrations in vegetation, food, atmosphere, soil and littoral soil samples have been determined. After operation of QNPP, the mean values of 137Cs, Sr and H in water are 0.6, 4.9 mBq/L and 1.7 Bq/L, respectively; the mean values 90 3 of137Cs in soil and littoral soil are 3.5 and 2.7 Bq/kg, respectively; the mean values of137Cs in rice, green cabbage, meat, mullet, milk and tea are 0.033, 0.039, 0.081, 0.069, 0.018 and 0.62 Bq/kg, respectively; the mean values of 90 Sr in rice, green cabbage and tea are 0.081, 0.315 and 4.1 Bq/kg, respectively; gross β activity in fallout is 0.9 Bq·m-2·d-1. Compared with the data before QNPP’s operation, no significant difference has heen observed in the radioactivity of137Cs, Sr, H and the gross β activity in ambient environmental matrices from 1992 to 2001, and 90 3 there are only some fluctuations within the range of background.展开更多
1GME037MV is the thrust wear detector of turbine.Before the turbine run up,the value of this channel often fluctuated.The engineer checked the channel,terminal,continuity,insulation,and driver and so on,no problem was...1GME037MV is the thrust wear detector of turbine.Before the turbine run up,the value of this channel often fluctuated.The engineer checked the channel,terminal,continuity,insulation,and driver and so on,no problem was found.At last,when disconnecting the end of the detector from the driver,then re-connected the end to the driver,the channel value is OK,after a while it became wrong again.Measured the resistance of the detector,it is 13O hm when the channel is OK,and 76 Ohm when the channel is wrong.According to the result of the checked,the conclusion is the character of the detector had changed.Both the measured value GME037MV and GME038MV are high 0.7mm,the turbine will trip,In the end the detector of GME037MV was replaced when the unit shut down.展开更多
基金supported by the project of State Key Laboratory of Nuclear Power Safety Monitoring Technology and Equipment(No.KA2019.418)the Foundation of Science and Technology on Reactor System Design Technology Laboratory(HT-KFKT-14-2017003)+1 种基金the technical support project for Suzhou Nuclear Power Research Institute(SNPI)(No.029-GN-B-2018-C45-P.0.99-00003)the project of the Research Institute of Nuclear Power Operation(No.RIN180149-SCCG)
文摘Scheduled maintenance and condition-based online monitoring are among the focal points of recent research to enhance nuclear plant safety.One of the most effective ways to monitor plant conditions is by implementing a full-scope,plant-wide fault diagnostic system.However,most of the proposed diagnostic techniques are perceived as unreliable by operators because they lack an explanation module,their implementation is complex,and their decision/inference path is unclear.Graphical formalism has been considered for fault diagnosis because of its clear decision and inference modules,and its ability to display the complex causal relationships between plant variables and reveal the propagation path used for fault localization in complex systems.However,in a graphbased approach,decision-making is slow because of rule explosion.In this paper,we present an enhanced signed directed graph that utilizes qualitative trend evaluation and a granular computing algorithm to improve the decision speed and increase the resolution of the graphical method.We integrate the attribute reduction capability of granular computing with the causal/fault propagation reasoning capability of the signed directed graph and comprehensive rules in a decision table to diagnose faults in a nuclear power plant.Qualitative trend analysis is used to solve the problems of fault diagnostic threshold selection and signed directed graph node state determination.The similarity reasoning and detection ability of the granular computing algorithm ensure a compact decision table and improve the decision result.The performance of the proposed enhanced system was evaluated on selected faults of the Chinese Fuqing 2 nuclear reactor.The proposed method offers improved diagnostic speed and efficient data processing.In addition,the result shows a considerable reduction in false positives,indicating that the method provides a reliable diagnostic system to support further intervention by operators.
基金supported by Shanghai Sail Program(No.19YF1458000).
文摘Oil cleaning agents generated from nuclear power plants(NPPs)are radioactive organic liquid wastes.To date,because there are no satisfactory industrial treatment measures,these wastes can only be stored for a long time.In this work,the optimization for the supercritical water oxidation(SCWO)of the spent organic solvent was investigated.The main process parameters of DURSET(oil cleaning agent)SCWO,such as temperature,reaction time,and excess oxygen coefficient,were optimized using response surface methodology,and a quadratic polynomial model was obtained.The determination coefficient(R^(2))of the model is 0.9812,indicating that the model is reliable.The optimized process conditions were at 515 C,66 s,and an excess oxygen coefficient of 211%.Under these conditions,the chemical oxygen demand removal of organic matter could reach 99.5%.The temperature was found to be the main factor affecting the SCWO process.Ketones and benzene-based compounds may be the main intermediates in DURSET SCWO.This work provides basic data for the industrialization of the degradation of spent organic solvents from NPP using SCWO technology.
基金supported by the National Natural Science Foundations of China (Nos. 51674031,51874022)。
文摘Visual inspection of the key components of nuclear power plants(NPPs)is important for NPP operation and maintenance. However,the underwater environment and existing radiation will lead to image degradation,thus making it difficult to identify surface defects. In this study,a method for improving the quality of underwater images is proposed.By analyzing the degradation characteristics of underwater detection image,the image enhancement technology is used to improve the color richness of the image,and then the improved dark channel prior(DCP)algorithm is used to restore it. By modifying the estimation formula of transmittance and background light,the correction of insufficient brightness in DCP restored image is realized. The proposed method is compared with other state-of-the-art methods. The results show that the proposed method can achieve higher scores and improve the image quality by correcting the color and restoring local details,thus effectively enhancing the reliability of visual inspection of NPPs.
基金funded by the Project “Resource Characteristics of Main Watersheds and Key Issues in Development and Utilization of Hydroelectricity in South America and Africa”the National Science Foundation of China (U1766201)
文摘The nuclear power plant is suitable for base-load operation, while the pumped-storage unit mainly gives play to capacity benefit in the electric power system;hence, the integrated development and hybrid operation mode of the two can better meet the needs of the electric power system. This article first presents an analysis of the necessity and superiority of such mode, then explains its meaning and analyzes the working routes. Finally, it proposes the business modes as follows: low price pumping water electricity plus nuclear power in the near term;nuclear power shifted to pumped storage power participating in market competition in the middle term;and, in the long term, nuclear power shifted to pumped storage power as primary and serving as an electric power system when needed.
文摘Fault diagnostics is important for safe operation of nuclear power plants(NPPs). In recent years, data-driven approaches have been proposed and implemented to tackle the problem, e.g., neural networks, fuzzy and neurofuzzy approaches, support vector machine, K-nearest neighbor classifiers and inference methodologies. Among these methods, dynamic uncertain causality graph(DUCG)has been proved effective in many practical cases. However, the causal graph construction behind the DUCG is complicate and, in many cases, results redundant on the symptoms needed to correctly classify the fault. In this paper, we propose a method to simplify causal graph construction in an automatic way. The method consists in transforming the expert knowledge-based DCUG into a fuzzy decision tree(FDT) by extracting from the DUCG a fuzzy rule base that resumes the used symptoms at the basis of the FDT. Genetic algorithm(GA) is, then, used for the optimization of the FDT, by performing a wrapper search around the FDT: the set of symptoms selected during the iterative search are taken as the best set of symptoms for the diagnosis of the faults that can occur in the system. The effectiveness of the approach is shown with respect to a DUCG model initially built to diagnose 23 faults originally using 262 symptoms of Unit-1 in the Ningde NPP of the China Guangdong Nuclear Power Corporation. The results show that the FDT, with GA-optimized symptoms and diagnosis strategy, can drive the construction of DUCG and lower the computational burden without loss of accuracy in diagnosis.
文摘It is necessary to develop an automatic fault diagnosis system to avoid a possible nuclear disaster caused by an inaccurate fault diagnosis in the nuclear power plant by the operator. Because Radial Basis Function Neural Network (RBFNN) has the characteristics of optimal approximation and global approximation. The mixed coding of binary system and decimal system is introduced to the structure and parameters of RBFNN, which is trained in course of the genetic optimization. Finally, a fault diagnosis system according to the frequent faults in condensation and feed water system of nuclear power plant is set up. As a result, Genetic-RBF Neural Network (GRBFNN) makes the neural network smaller in size and higher in generalization ability. The diagnosis speed and accuracy are also improved.
文摘A nuclear power plant real-time engineering simulator was developed based on general-purpose ther- mal-hydraulic system simulation code RELAP5. It mainly consists of three parts:improved thermal-hydraulic system simulation code RELAP5,control and protection system and human-machine interface. A normal transient of CHASHMA nuclear power plant turbine step load change from 100% to 90% of full power,was simulated by the en- gineering simulator as an application example. This paper presents structure and main features of the engineering simulator,and application results are shown and discussed.
基金Supported by Jinwen University of Science and Technology
文摘The purpose of this study is to establish an intelligent expert system for nuclear power plant emergency response.A new framework of environmental risk management methodology by the concept of pattern recognition was introduced in this paper.A knowledge-based decision support system for emergency response and risk management of nuclear power plant was also discussed.The mathematical pattern relationship of accidental release effects on neighboring area and the corresponding response measures were presented in this paper.With this decision system,the decision maker can specify the procedure and minimize their human error in the decision process.The improvement of risk response and the quality of management system could be upgraded by this system.Besides,the methodology can also be served as a basis for the future development of environmental risk response system design.
文摘A quantitative environmental assessment method and the corresponding computer code are introduced in this paper. By the consideration of all fuel cycle steps,it gives that the public health risk of China nuclear power industry is 5.2 × 10-1 man /(GW.a), the occupational health risk is 2.5 man /(GW.a), and the total health risk is 3.0 man /(GW.a). After the health risk calculation for coal mining, transport, burning up and ash disposal, it gives that the public health risk of China coal-fired power industry is 3.6mall/(GW-a), the occupational health risk is 50man /(GW.a), and the total is 54man /(GW.d). Accordingly, the conclusion that China nuclear power industry is an industry with high safety and cleanness is derived at the end.
文摘This study presents a probabilistic safety analysis(PSA)method for the external event of extreme snowfall on a floating nuclear power plant(FNPP)deployed in the Bohai Sea.We utilized the Weibull and Gumbel extreme value distributions to fit the collected meteorological data and obtained a hazard curve for the event of an extreme snowfall where the FNPP is located,providing a basis for the frequency of extreme snowfall-initiating events.Our analysis indicates that extreme snowfall primarily affects the ventilation openings of the equipment,leading to the failure of devices such as the diesel generators.Additionally,extreme snowfall can result in a loss of off-site power(LOOP).Therefore,the developed extreme snowfall PSA model is mainly based on the LOOP event tree,considering responses such as snowfall removal by personnel.Our calculations indicate a core damage frequency(CDF)of 1.13×10^(-10) owing to extreme snowfall,which is relatively low.The results of the cut-set analysis indicate that valve failures in the core makeup tank(CMT),passive residual heat removal system(PRS),and in-containment refueling water storage tank(IRWST)significantly contribute to the CDF.
文摘The fuzzy logic and neural networks are combined in this paper, setting upthe fuzzy neural network (FNN ) ; meanwhile, the distinct differences and connections between thefuzzy logic and neural network are compared. Furthermore, the algorithm and structure of the FNN areintroduced. In order to diagnose the faults of nuclear power plant, the FNN is applied to thenuclear power planl, and the intelligence fault diagnostic system of the nuclear power plant isbuilt based on the FNN . The fault symptoms and the possibility of the inverted U-tube breakaccident of steam generator are discussed. In order to test the system' s validity, the invertedU-tube break accident of steam generator is used as an example and many simulation experiments areperformed. The test result shows that the FNN can identify the fault.
文摘A plan of surveillance monitoring Qinshan Nuclear Power Plant (QNPP) has been implemented since 1992, the objective of which is to establish the database of environmental radiation information around QNPP, and to detect any unplanned discharge of radioactive materials from QNPP. This paper presents the monitoring results for radionuclide concentrations in the environmental matrices before and after QNPP operation. The radionuclide con- centrations in vegetation, food, atmosphere, soil and littoral soil samples have been determined. After operation of QNPP, the mean values of 137Cs, Sr and H in water are 0.6, 4.9 mBq/L and 1.7 Bq/L, respectively; the mean values 90 3 of137Cs in soil and littoral soil are 3.5 and 2.7 Bq/kg, respectively; the mean values of137Cs in rice, green cabbage, meat, mullet, milk and tea are 0.033, 0.039, 0.081, 0.069, 0.018 and 0.62 Bq/kg, respectively; the mean values of 90 Sr in rice, green cabbage and tea are 0.081, 0.315 and 4.1 Bq/kg, respectively; gross β activity in fallout is 0.9 Bq·m-2·d-1. Compared with the data before QNPP’s operation, no significant difference has heen observed in the radioactivity of137Cs, Sr, H and the gross β activity in ambient environmental matrices from 1992 to 2001, and 90 3 there are only some fluctuations within the range of background.
文摘1GME037MV is the thrust wear detector of turbine.Before the turbine run up,the value of this channel often fluctuated.The engineer checked the channel,terminal,continuity,insulation,and driver and so on,no problem was found.At last,when disconnecting the end of the detector from the driver,then re-connected the end to the driver,the channel value is OK,after a while it became wrong again.Measured the resistance of the detector,it is 13O hm when the channel is OK,and 76 Ohm when the channel is wrong.According to the result of the checked,the conclusion is the character of the detector had changed.Both the measured value GME037MV and GME038MV are high 0.7mm,the turbine will trip,In the end the detector of GME037MV was replaced when the unit shut down.
