Mechanism-based and data-based methods are widely used in fault detection of nuclear power plant. Each method has its advantages and disadvantages. In this paper, we propose weighted data-based fault detection method based on data which we called Implicit Model Approach (IMA) for nuclear power plant. By introducing weighted factor and Takagi-Sugeno modeling method, we extend the IMA-based fault detection from linear system to nonlinear system. At local operating point, linear IMA is utilized to generate sub-system residual function. Inspired by Parallel Distributed Control (PDC) method, we generate overall residual function and overall residual evaluation mechanism. Simulation analysis has verified the validity of the proposed algorithm. The significance of the weighted IMA lies in establishing a data-based and mechanism-friendly approach. This work can provide new route for fault detection of nonlinear nuclear power system.
{"title":"Weighted Data-Based Fault Detection Approach for Nonlinear Nuclear Power System","authors":"Zhaoxu Chen, Hongkuan Zhou, Zhiwu Ke, Xiao Qi, Zhiqiang Qiu","doi":"10.1115/icone29-90205","DOIUrl":"https://doi.org/10.1115/icone29-90205","url":null,"abstract":"\u0000 Mechanism-based and data-based methods are widely used in fault detection of nuclear power plant. Each method has its advantages and disadvantages. In this paper, we propose weighted data-based fault detection method based on data which we called Implicit Model Approach (IMA) for nuclear power plant. By introducing weighted factor and Takagi-Sugeno modeling method, we extend the IMA-based fault detection from linear system to nonlinear system. At local operating point, linear IMA is utilized to generate sub-system residual function. Inspired by Parallel Distributed Control (PDC) method, we generate overall residual function and overall residual evaluation mechanism. Simulation analysis has verified the validity of the proposed algorithm. The significance of the weighted IMA lies in establishing a data-based and mechanism-friendly approach. This work can provide new route for fault detection of nonlinear nuclear power system.","PeriodicalId":365848,"journal":{"name":"Volume 5: Nuclear Safety, Security, and Cyber Security","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125348302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As an indispensable component of the control system, the sensor usually works in high temperature, high pressure, strong vibration and other failure-prone environment. The complex, changeable, and high intensity working environment makes the sensors work unstable, which eventually leads to the sensor fault. Once the sensor fault occurs, the output signal will deviate from the normal value, which seriously decreases the accuracy, stability and reliability of the control system. To solve this problem, the researchers tried to locate the faulty sensors and recover the missing data by the expertise, which results in low accuracy and long-time consuming. In this paper, a novel data reconstruction method for padding the missing data of the faulty sensor is proposed. Based on the extensive redundancy and complementarity of the information obtained from various types of sensors, the data reconstruction of the target sensor is realized by combining the thermal system model with the strong tracking filter algorithm. Simulation data of the single pressure condenser system show that, under different sensor fault modes, the reconstruction accuracy deviation of the signal reconstructed by the algorithm is less than 5% compared with the normal signal. The application of the proposed algorithm can significantly improve the safety and reliability of the control system.
{"title":"Data Reconstruction of Faulty Sensors for the Nuclear Power Plants Control System: A Strong Tracking Filter Approach","authors":"Hongkuan Zhou, Wei Zheng, Mo Tao, Xiaojie Guo, Chonghai Huang, Wenting Chai, Kai-Hsang Chen, Zhaoxu Chen","doi":"10.1115/icone29-91642","DOIUrl":"https://doi.org/10.1115/icone29-91642","url":null,"abstract":"\u0000 As an indispensable component of the control system, the sensor usually works in high temperature, high pressure, strong vibration and other failure-prone environment. The complex, changeable, and high intensity working environment makes the sensors work unstable, which eventually leads to the sensor fault. Once the sensor fault occurs, the output signal will deviate from the normal value, which seriously decreases the accuracy, stability and reliability of the control system. To solve this problem, the researchers tried to locate the faulty sensors and recover the missing data by the expertise, which results in low accuracy and long-time consuming. In this paper, a novel data reconstruction method for padding the missing data of the faulty sensor is proposed. Based on the extensive redundancy and complementarity of the information obtained from various types of sensors, the data reconstruction of the target sensor is realized by combining the thermal system model with the strong tracking filter algorithm. Simulation data of the single pressure condenser system show that, under different sensor fault modes, the reconstruction accuracy deviation of the signal reconstructed by the algorithm is less than 5% compared with the normal signal. The application of the proposed algorithm can significantly improve the safety and reliability of the control system.","PeriodicalId":365848,"journal":{"name":"Volume 5: Nuclear Safety, Security, and Cyber Security","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116220873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Diversity design is an effective measure to avoid common cause failure, which is of great significance to improve the reliability and safety of nuclear power plants. Especially for those high-frequency occurring accidents mitigation, diversity design plays a significant role. In order to improve its reliability and safety, this paper takes a PWR nuclear power plant as the research object, establishes a diversity design method to mitigate high-frequency occurring accidents, and applies this method to optimize the design of nuclear power plant. In this paper, the safety system of the power station is studied, and a variety of design methods are applied to optimize the design scheme. The results show that this method not only significantly improves the reliability and safety of nuclear power plant, but also plays a great role in the economic operation of nuclear power plant.
{"title":"Research and Application of Diversity Design of Nuclear Power Plant Based on High-Frequency Occurring Accidents Mitigation","authors":"Jiaoshen Xu, Zheng-guang Liu","doi":"10.1115/icone29-93635","DOIUrl":"https://doi.org/10.1115/icone29-93635","url":null,"abstract":"\u0000 Diversity design is an effective measure to avoid common cause failure, which is of great significance to improve the reliability and safety of nuclear power plants. Especially for those high-frequency occurring accidents mitigation, diversity design plays a significant role. In order to improve its reliability and safety, this paper takes a PWR nuclear power plant as the research object, establishes a diversity design method to mitigate high-frequency occurring accidents, and applies this method to optimize the design of nuclear power plant. In this paper, the safety system of the power station is studied, and a variety of design methods are applied to optimize the design scheme. The results show that this method not only significantly improves the reliability and safety of nuclear power plant, but also plays a great role in the economic operation of nuclear power plant.","PeriodicalId":365848,"journal":{"name":"Volume 5: Nuclear Safety, Security, and Cyber Security","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129818291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Smuggling of nuclear material is one of the serious problems of nuclear security. Nuclear institutes and organizations put great efforts to protect these materials from dangerous hands by applying nuclear security policies, using monitoring tools, and developing access control systems. These techniques effectively prevent outsider threats but cannot provide high confidence withstanding insider threats. History offers many examples of violent employees, who broke the rules and smuggled nuclear material, taking advantage of their knowledge, experience, and authority to access the nuclear facility systems and their vulnerability. Nuclear smuggling operations can be through one insider, multi-insiders, or by the incorporation with an outsider, this makes the facility’s security planning a challenge. The analysis of smuggling crime shows that the motivations for performing insider threats vary. It includes but is not limited to financial gain, poor security culture, and revenge. Lessons learned from other insider crimes in non-nuclear fields are useful for developing nuclear facility plans. Thus, it is enormously important to continuously improve the security system, overcome instrumentation malfunctions, and strengthen the nuclear security culture in the facility. This paper provides a review and recommendations in the legal and technical framework to genuinely prevent insider nuclear threats against nuclear facilities.
{"title":"Nuclear Security Against Insider Smuggling: Review and Recommendations","authors":"Hiba Al-Khodire","doi":"10.1115/icone29-93455","DOIUrl":"https://doi.org/10.1115/icone29-93455","url":null,"abstract":"\u0000 Smuggling of nuclear material is one of the serious problems of nuclear security. Nuclear institutes and organizations put great efforts to protect these materials from dangerous hands by applying nuclear security policies, using monitoring tools, and developing access control systems. These techniques effectively prevent outsider threats but cannot provide high confidence withstanding insider threats.\u0000 History offers many examples of violent employees, who broke the rules and smuggled nuclear material, taking advantage of their knowledge, experience, and authority to access the nuclear facility systems and their vulnerability. Nuclear smuggling operations can be through one insider, multi-insiders, or by the incorporation with an outsider, this makes the facility’s security planning a challenge.\u0000 The analysis of smuggling crime shows that the motivations for performing insider threats vary. It includes but is not limited to financial gain, poor security culture, and revenge. Lessons learned from other insider crimes in non-nuclear fields are useful for developing nuclear facility plans. Thus, it is enormously important to continuously improve the security system, overcome instrumentation malfunctions, and strengthen the nuclear security culture in the facility. This paper provides a review and recommendations in the legal and technical framework to genuinely prevent insider nuclear threats against nuclear facilities.","PeriodicalId":365848,"journal":{"name":"Volume 5: Nuclear Safety, Security, and Cyber Security","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128485275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The coastal soil surrounding to the Nuclear Power Plants were mainly classified to brown soil and aeolian sandy soil in China. In previous research, focused on the elements of Cs-137 and Sr-85 vertical transfer in these soils, but the Co-60, which was the most important factor in the brown soil and aeolian sandy soil were still urgent research. In this study, experiments were conducted to determine the vertical transfer of Co-60 in brown soil and aeolian sandy soil. The soil around Shidaowan Nuclear Power Plant were studied by using undisturbed soil column methods and isotope tracer technology, and identify the factors influencing their migration depths in soil. The results show that with the increase of leaching test, the migration of Co-60 in aeolian sandy soil was greater than that in brown soil, but the difference gradually decreases with the progress of spray test; the content of Co-60 in leaching water was very few and cannot be detected due to the strong adsorption by soil; after three years of undisturbed soil column experiment, 72.36 ∼ 85.26% of Co-60 mainly was retarded in the range of 0∼5cm in both of the soil surface. It was proved that Co-60 was difficult to migrate to groundwater in a short period. The distribution of specific activity of Co-60 in soil was an individual exponential declining with depth of oil. The results showed that the radionuclide Co-60 had little impact on groundwater in the years after the nuclear accident, but it should pay attention to the change of radioactivity concentration in surface soil and then select appropriate soil remediation methods. The study will provide a scientific basis for post-accident environmental impact assessment and post-accident soil remediation in China.
{"title":"Study on Vertical Transfer of Radionuclide Co-60 in Broun Soil and Aeolian Sandy Soil Around Nuclear Power Plant","authors":"Qiong Zhang, Ye Yuanlv, Wang Bo, Chenbin Lu","doi":"10.1115/icone29-89818","DOIUrl":"https://doi.org/10.1115/icone29-89818","url":null,"abstract":"\u0000 The coastal soil surrounding to the Nuclear Power Plants were mainly classified to brown soil and aeolian sandy soil in China. In previous research, focused on the elements of Cs-137 and Sr-85 vertical transfer in these soils, but the Co-60, which was the most important factor in the brown soil and aeolian sandy soil were still urgent research. In this study, experiments were conducted to determine the vertical transfer of Co-60 in brown soil and aeolian sandy soil. The soil around Shidaowan Nuclear Power Plant were studied by using undisturbed soil column methods and isotope tracer technology, and identify the factors influencing their migration depths in soil. The results show that with the increase of leaching test, the migration of Co-60 in aeolian sandy soil was greater than that in brown soil, but the difference gradually decreases with the progress of spray test; the content of Co-60 in leaching water was very few and cannot be detected due to the strong adsorption by soil; after three years of undisturbed soil column experiment, 72.36 ∼ 85.26% of Co-60 mainly was retarded in the range of 0∼5cm in both of the soil surface. It was proved that Co-60 was difficult to migrate to groundwater in a short period. The distribution of specific activity of Co-60 in soil was an individual exponential declining with depth of oil. The results showed that the radionuclide Co-60 had little impact on groundwater in the years after the nuclear accident, but it should pay attention to the change of radioactivity concentration in surface soil and then select appropriate soil remediation methods. The study will provide a scientific basis for post-accident environmental impact assessment and post-accident soil remediation in China.","PeriodicalId":365848,"journal":{"name":"Volume 5: Nuclear Safety, Security, and Cyber Security","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124527392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jianmin Tong, Yibin Huang, Xiaojing Guo, Liu Chen, Peng Cong, Zhentao Wang, Guilai Xing, Liqiang Wang
Using X-ray or γ-ray to inspect vehicles is an effective way to find threats such as stowaways and contrabands hidden inside. Popularly used vehicle inspection devices at present require passengers to get off the vehicle, and then the vehicle is dragged by a conveyor to move through the inspection device. One disadvantage of such devices is that inspecting efficiency is very low. In this paper, a drive-through mode passenger vehicle inspecting system is introduced, with which passengers in a vehicle need not get off and efficiency is greatly improved. Patented high-pressure gas ionization chamber is used as radiation detector to collect the low radiation signal. A deep-learning study algorithm is adopted to realize image recognition to find specified object. The system can greatly increase security check efficiency with good image quality.
{"title":"A Drive-Through Passenger Vehicle Inspecting System Using X-Ray Digital Radiography","authors":"Jianmin Tong, Yibin Huang, Xiaojing Guo, Liu Chen, Peng Cong, Zhentao Wang, Guilai Xing, Liqiang Wang","doi":"10.1115/icone29-93780","DOIUrl":"https://doi.org/10.1115/icone29-93780","url":null,"abstract":"\u0000 Using X-ray or γ-ray to inspect vehicles is an effective way to find threats such as stowaways and contrabands hidden inside. Popularly used vehicle inspection devices at present require passengers to get off the vehicle, and then the vehicle is dragged by a conveyor to move through the inspection device. One disadvantage of such devices is that inspecting efficiency is very low. In this paper, a drive-through mode passenger vehicle inspecting system is introduced, with which passengers in a vehicle need not get off and efficiency is greatly improved. Patented high-pressure gas ionization chamber is used as radiation detector to collect the low radiation signal. A deep-learning study algorithm is adopted to realize image recognition to find specified object. The system can greatly increase security check efficiency with good image quality.","PeriodicalId":365848,"journal":{"name":"Volume 5: Nuclear Safety, Security, and Cyber Security","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115407517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhaoli Zheng, Jun Wu, Zhiwu Ke, Zhenxing Zhao, Xiaohu Yang, L. Dai
The supercritical carbon dioxide (SCO2) Brayton cycle has the characteristics of high power density and high thermal efficiency, which is an important development direction of the micro power plant. SCO2 turbine is the core component of the SCO2 Brayton cycle of which the dynamics have important influences on operational reliability of the entire system. With regard to the rotor of SCO2 turbine, the equations of motion is established by adopting finite element method. The complex eigenvalues of the rotor are solved in the state space, and the campbell diagram has been drawn to obtain the critical speeds. The steady state response of the rotor is obtained by the harmonic balance method, and the safety of the system is estimated based on API684. Results show that the rotor is not safe with its original geometric paramters. Aiming to improve the operational safety, an optimization method based on active learning is developed to maximize the separation margin. Results show that after the optimization, the separation margin has been greatly increased. Comparing with the genetic algorithm (GA) and the parttern search (PS) method, the iteration number of the active learning optimization method has been greatly reduced. The effectiveness of the developed optimization method is proved, and the study method and conclusions can serve as a reference to the optimization of SCO2 turbine rotors in the industry.
{"title":"Investigation on the Active Learning Optimization on Rotor Dynamics of SCO2 Turbine","authors":"Zhaoli Zheng, Jun Wu, Zhiwu Ke, Zhenxing Zhao, Xiaohu Yang, L. Dai","doi":"10.1115/icone29-91731","DOIUrl":"https://doi.org/10.1115/icone29-91731","url":null,"abstract":"\u0000 The supercritical carbon dioxide (SCO2) Brayton cycle has the characteristics of high power density and high thermal efficiency, which is an important development direction of the micro power plant. SCO2 turbine is the core component of the SCO2 Brayton cycle of which the dynamics have important influences on operational reliability of the entire system. With regard to the rotor of SCO2 turbine, the equations of motion is established by adopting finite element method. The complex eigenvalues of the rotor are solved in the state space, and the campbell diagram has been drawn to obtain the critical speeds. The steady state response of the rotor is obtained by the harmonic balance method, and the safety of the system is estimated based on API684. Results show that the rotor is not safe with its original geometric paramters. Aiming to improve the operational safety, an optimization method based on active learning is developed to maximize the separation margin. Results show that after the optimization, the separation margin has been greatly increased. Comparing with the genetic algorithm (GA) and the parttern search (PS) method, the iteration number of the active learning optimization method has been greatly reduced. The effectiveness of the developed optimization method is proved, and the study method and conclusions can serve as a reference to the optimization of SCO2 turbine rotors in the industry.","PeriodicalId":365848,"journal":{"name":"Volume 5: Nuclear Safety, Security, and Cyber Security","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127219302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiao Ding Li, Y. Gong, G. Li, Gang Bai, J. Zheng, Y. Qu, Zhe Li
Radioactive source liability insurance refers to the form of insurance in which the insurer shall be liable for compensation according to law when the insured uses radioactive sources to cause radiation damage or environmental pollution to a third party and is claimed for compensation. This paper deeply investigates the practical experience of various countries in the field of radioactive source liability insurance; this type of insurance has a lot of mature application experience in Europe & US, the two major nuclear damage compensation convention systems have not yet stipulated the liability insurance of radioactive sources, European countries have a strong awareness of applying for radioactive source liability insurance. Then it makes a detailed analysis of the current laws and regulations in the field of nuclear technology utilization and the current situation of liability insurance in the field of radioactive sources in China. At present, there is no special law on liability insurance in the field of radioactive sources, there are still several problems, including the weak awareness of risk prevention of enterprises using nuclear technology, the lack of social responsibility of some enterprises and their unwillingness to buy insurance. In order to solve the above problems, the following four recommendations are made. First, improve the legal and policy system of radioactive source liability insurance in China. Second, pilot the implementation of radioactive source compulsory liability insurance in high-risk industries or enterprises. Third, promote personalized insurance rates and insurance limits. Fourth, carry out health damage insurance for employees in the field of radioactive sources at an appropriate time. Finally, it provides a strong and valuable reference for the future radioactive source liability insurance in China.
{"title":"Research on Liability Insurance for Radioactive Sources and Suggestions to China","authors":"Xiao Ding Li, Y. Gong, G. Li, Gang Bai, J. Zheng, Y. Qu, Zhe Li","doi":"10.1115/icone29-93505","DOIUrl":"https://doi.org/10.1115/icone29-93505","url":null,"abstract":"\u0000 Radioactive source liability insurance refers to the form of insurance in which the insurer shall be liable for compensation according to law when the insured uses radioactive sources to cause radiation damage or environmental pollution to a third party and is claimed for compensation. This paper deeply investigates the practical experience of various countries in the field of radioactive source liability insurance; this type of insurance has a lot of mature application experience in Europe & US, the two major nuclear damage compensation convention systems have not yet stipulated the liability insurance of radioactive sources, European countries have a strong awareness of applying for radioactive source liability insurance. Then it makes a detailed analysis of the current laws and regulations in the field of nuclear technology utilization and the current situation of liability insurance in the field of radioactive sources in China. At present, there is no special law on liability insurance in the field of radioactive sources, there are still several problems, including the weak awareness of risk prevention of enterprises using nuclear technology, the lack of social responsibility of some enterprises and their unwillingness to buy insurance.\u0000 In order to solve the above problems, the following four recommendations are made. First, improve the legal and policy system of radioactive source liability insurance in China. Second, pilot the implementation of radioactive source compulsory liability insurance in high-risk industries or enterprises. Third, promote personalized insurance rates and insurance limits. Fourth, carry out health damage insurance for employees in the field of radioactive sources at an appropriate time. Finally, it provides a strong and valuable reference for the future radioactive source liability insurance in China.","PeriodicalId":365848,"journal":{"name":"Volume 5: Nuclear Safety, Security, and Cyber Security","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132056207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Baosheng Wang, Tengyue Ma, Lihong Bao, Zhenhui Ma, Pan Hu, Da Li, Chunlei Su, Lixin Chen, Xiuhuan Tang
Due to the epistemic uncertainties involved in the numerical values of its parameters and its modeling, the system may not accomplish its function as required. Functional failure becomes an important factors in the natural circulation system operation failure, which needs to be considered in the system reliability analysis. In order to solve the problem of multi-dimensional uncertainty parameters and small functional failure probability of passive systems, an efficient functional reliability estimation method based on improved response surface and importance sampling subset simulation was presented. This method was applied in natural circulation cooling in XAPR reactor core. Combined with MLOCA, the uncertainties related to the input parameters and the model were considered. And then the probability of functional failure and the sensitivity measures were estimated with the combination of response surface method and importance sampling subset simulation method. The assessment results show that the functional failure probability is 3.796 × 10−3, and it is fully considered the functional failure in the passive system reliability analysis. Meanwhile, this method has high computed efficiency and excellent computed accuracy compared with traditional probability analysis methods, and it is robust to nonlinear functional function of XAPR.
{"title":"Functional Reliability Investigation on Capacity of Reactor Core Natural Circulation Cooling in XAPR Under MLOCA","authors":"Baosheng Wang, Tengyue Ma, Lihong Bao, Zhenhui Ma, Pan Hu, Da Li, Chunlei Su, Lixin Chen, Xiuhuan Tang","doi":"10.1115/icone29-93526","DOIUrl":"https://doi.org/10.1115/icone29-93526","url":null,"abstract":"\u0000 Due to the epistemic uncertainties involved in the numerical values of its parameters and its modeling, the system may not accomplish its function as required. Functional failure becomes an important factors in the natural circulation system operation failure, which needs to be considered in the system reliability analysis. In order to solve the problem of multi-dimensional uncertainty parameters and small functional failure probability of passive systems, an efficient functional reliability estimation method based on improved response surface and importance sampling subset simulation was presented. This method was applied in natural circulation cooling in XAPR reactor core. Combined with MLOCA, the uncertainties related to the input parameters and the model were considered. And then the probability of functional failure and the sensitivity measures were estimated with the combination of response surface method and importance sampling subset simulation method. The assessment results show that the functional failure probability is 3.796 × 10−3, and it is fully considered the functional failure in the passive system reliability analysis. Meanwhile, this method has high computed efficiency and excellent computed accuracy compared with traditional probability analysis methods, and it is robust to nonlinear functional function of XAPR.","PeriodicalId":365848,"journal":{"name":"Volume 5: Nuclear Safety, Security, and Cyber Security","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130818071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
210Po has become a non-negligible radioactive safety problem in the fourth generation Lead-based Fast Reactor (LFR) due to its high toxicity and volatility. It will be produced by neutron irradiation of coolant and emits α ray. This may cause potential internal exposure hazards when workers are working in the plant. Polonium produced in the primary coolant circuit of the Reactor will be released to cover gas due to its volatility. This process is slow but not negligible. Therefore, the migration of polonium in the whole reactor and the distribution in the containment room for the M2LFR-1000 was preliminary analyzed. According to the radionuclide migration theory, the migration of polonium was analyzed theoretically, and the distribution of polonium was simulated by FLUENT. Two situations are simulated, one is normal operating condition and the other is leakage accident of covering gas. Preliminary calculation shows that polonium is distributed homogeneously throughout the space with the accumulation of radionuclides only at the certain special place, and the concentrations below safe levels under normal operating conditions. The method of analysis procedure can also be applied to analyze the distribution of other radionuclides.
{"title":"Preliminary Study on the Migration of Polonium-210 in Lead-Based Fast Reactor","authors":"Yali Qiu, Q. Zeng, Hongli Chen","doi":"10.1115/icone29-92104","DOIUrl":"https://doi.org/10.1115/icone29-92104","url":null,"abstract":"\u0000 210Po has become a non-negligible radioactive safety problem in the fourth generation Lead-based Fast Reactor (LFR) due to its high toxicity and volatility. It will be produced by neutron irradiation of coolant and emits α ray. This may cause potential internal exposure hazards when workers are working in the plant. Polonium produced in the primary coolant circuit of the Reactor will be released to cover gas due to its volatility. This process is slow but not negligible. Therefore, the migration of polonium in the whole reactor and the distribution in the containment room for the M2LFR-1000 was preliminary analyzed. According to the radionuclide migration theory, the migration of polonium was analyzed theoretically, and the distribution of polonium was simulated by FLUENT. Two situations are simulated, one is normal operating condition and the other is leakage accident of covering gas. Preliminary calculation shows that polonium is distributed homogeneously throughout the space with the accumulation of radionuclides only at the certain special place, and the concentrations below safe levels under normal operating conditions. The method of analysis procedure can also be applied to analyze the distribution of other radionuclides.","PeriodicalId":365848,"journal":{"name":"Volume 5: Nuclear Safety, Security, and Cyber Security","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131731490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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