The reliability and availability of the reactor protection system （RPS） can be improved by using M out of N judg- ment system. By analyzing two quantitative indicators, the rate of refusal to operate and mal-operati...The reliability and availability of the reactor protection system （RPS） can be improved by using M out of N judg- ment system. By analyzing two quantitative indicators, the rate of refusal to operate and mal-operation rate, a strict math- ematical formula and an approximate calculation are stated. The differences of a series of judgment systems are discussed on condition that the unsafe failure probability and the security failure probability are both 0.1. Based on given parameters （A, B,P, Q）： A is upper limit of the refusal rate for the RPS, B is upper limit of the real-operation rate, P and Q are basic protection unit rates corresponding to refusal rate and mal-operation rate, respectively. According to these parameters, the values of N and M can be solved.展开更多
The digital reactor protection system(RPS)is one of the most important digital instrumentation and control(I&C)systems utilized in nuclear power plants(NPPs).It ensures a safe reactor trip when the safety-related ...The digital reactor protection system(RPS)is one of the most important digital instrumentation and control(I&C)systems utilized in nuclear power plants(NPPs).It ensures a safe reactor trip when the safety-related parameters violate the operational limits and conditions of the reactor.Achieving high reliability and availability of digital RPS is essential to maintaining a high degree of reactor safety and cost savings.The main objective of this study is to develop a general methodology for improving the reliability of the RPS in NPP,based on a Bayesian Belief Network(BBN)model.The structure of BBN models is based on the incorporation of failure probability and downtime of the RPS I&C components.Various architectures with dual-state nodes for the I&C components were developed for reliability-sensitive analysis and availability optimization of the RPS and to demonstrate the effect of I&C components on the failure of the entire system.A reliability framework clarified as a reliability block diagram transformed into a BBN representation was constructed for each architecture to identify which one will fit the required reliability.The results showed that the highest availability obtained using the proposed method was 0.9999998.There are 120 experiments using two common component importance measures that are applied to define the impact of I&C modules,which revealed that some modules are more risky than others and have a larger effect on the failure of the digital RPS.展开更多
Overall purpose of a power uprate and lifetime extension project （PLEX） is to modernize the power station cost-efficiently resulting in fulfilling the following overall requirements. The primary target is to meet th...Overall purpose of a power uprate and lifetime extension project （PLEX） is to modernize the power station cost-efficiently resulting in fulfilling the following overall requirements. The primary target is to meet the requirements provided by the local regulations from the regulatory offices. The controlling, monitoring and power supply of safety functions have to comply with these regulations. Any deviations from the existing safety analysis report （SAR） have to be corrected. On top of the safety measures the general technical status should be raised to extend the lifetime to 60 years. A high availability during the modernization has to be assured.展开更多
Primary frequency regulation is one of the important regulation means to maintain the stable operation of the power grid, and for a single unit, especially the nuclear power unit, the frequency regulation process is a...Primary frequency regulation is one of the important regulation means to maintain the stable operation of the power grid, and for a single unit, especially the nuclear power unit, the frequency regulation process is an unstable factor. With the increasing capacity of nuclear motor assembly machine, it is bound to shoulder the heavy responsibility of peak shaving and frequency modulation. However, its own particularity determines that it cannot be as flexible as thermal power plants and other power plants in terms of frequency modulation, and it is necessary to find a balance between maintaining the stability of the power grid and the safe and stable operation of units. Taking 650MW nuclear power steam turbine unit as an example, this paper introduces and analyzes in detail the control principle, control process, frequency modulation parameter setting of its primary frequency modulation, as well as the adverse effects of reactor protection actions such as reactor over power that may be caused by transient events and primary frequency modulation process. By taking technical measures such as adjusting the mode of primary frequency modulation operation, we can reduce the impact of external network faults on the unit, summarize the experience of transient disposal, and improve the plan, improve the ability of the main control operator to judge and deal with the transient, so as to ensure that the unit can meet the requirements of the primary frequency modulation response of the power grid on the basis of safe and stable operation.展开更多
基金Research Project of Hunan Province Education Department(No.14C0972)
文摘The reliability and availability of the reactor protection system （RPS） can be improved by using M out of N judg- ment system. By analyzing two quantitative indicators, the rate of refusal to operate and mal-operation rate, a strict math- ematical formula and an approximate calculation are stated. The differences of a series of judgment systems are discussed on condition that the unsafe failure probability and the security failure probability are both 0.1. Based on given parameters （A, B,P, Q）： A is upper limit of the refusal rate for the RPS, B is upper limit of the real-operation rate, P and Q are basic protection unit rates corresponding to refusal rate and mal-operation rate, respectively. According to these parameters, the values of N and M can be solved.
文摘The digital reactor protection system(RPS)is one of the most important digital instrumentation and control(I&C)systems utilized in nuclear power plants(NPPs).It ensures a safe reactor trip when the safety-related parameters violate the operational limits and conditions of the reactor.Achieving high reliability and availability of digital RPS is essential to maintaining a high degree of reactor safety and cost savings.The main objective of this study is to develop a general methodology for improving the reliability of the RPS in NPP,based on a Bayesian Belief Network(BBN)model.The structure of BBN models is based on the incorporation of failure probability and downtime of the RPS I&C components.Various architectures with dual-state nodes for the I&C components were developed for reliability-sensitive analysis and availability optimization of the RPS and to demonstrate the effect of I&C components on the failure of the entire system.A reliability framework clarified as a reliability block diagram transformed into a BBN representation was constructed for each architecture to identify which one will fit the required reliability.The results showed that the highest availability obtained using the proposed method was 0.9999998.There are 120 experiments using two common component importance measures that are applied to define the impact of I&C modules,which revealed that some modules are more risky than others and have a larger effect on the failure of the digital RPS.
文摘Overall purpose of a power uprate and lifetime extension project （PLEX） is to modernize the power station cost-efficiently resulting in fulfilling the following overall requirements. The primary target is to meet the requirements provided by the local regulations from the regulatory offices. The controlling, monitoring and power supply of safety functions have to comply with these regulations. Any deviations from the existing safety analysis report （SAR） have to be corrected. On top of the safety measures the general technical status should be raised to extend the lifetime to 60 years. A high availability during the modernization has to be assured.
文摘Primary frequency regulation is one of the important regulation means to maintain the stable operation of the power grid, and for a single unit, especially the nuclear power unit, the frequency regulation process is an unstable factor. With the increasing capacity of nuclear motor assembly machine, it is bound to shoulder the heavy responsibility of peak shaving and frequency modulation. However, its own particularity determines that it cannot be as flexible as thermal power plants and other power plants in terms of frequency modulation, and it is necessary to find a balance between maintaining the stability of the power grid and the safe and stable operation of units. Taking 650MW nuclear power steam turbine unit as an example, this paper introduces and analyzes in detail the control principle, control process, frequency modulation parameter setting of its primary frequency modulation, as well as the adverse effects of reactor protection actions such as reactor over power that may be caused by transient events and primary frequency modulation process. By taking technical measures such as adjusting the mode of primary frequency modulation operation, we can reduce the impact of external network faults on the unit, summarize the experience of transient disposal, and improve the plan, improve the ability of the main control operator to judge and deal with the transient, so as to ensure that the unit can meet the requirements of the primary frequency modulation response of the power grid on the basis of safe and stable operation.
