Abstract
The instrumentation and control (I&C) systems for the Lungmen nuclear power plant are fully digitized based on microprocessor and software technology, and extensively utilize multiplexing networks. That is, undetectable software faults and common cause failures due to software errors may occur, and that will defeat the redundancy of a nuclear power plant (NPP). A diverse backup implementation for the digital I&C systems is an important means to defense against undetectable software faults. This research is to explore the feasibility and preliminary design of using FPGA-based instrumentation and control systems for nuclear power plants (PWR type Maanshan NPP and ABWR type Lungmen NPP). First, this research explores a concepture design of using FPGA-based triple-redundant system for Anticipated-Transient-Without-Scam Mitigation System and Actuation Circuit (AMSAC) for Taipower’s Maanshan PWR type NPP. A simulated interface between AMSAC system and simplifed reactor/plant systems is developed to provide a test environment to validate the triple-redundant FPGA-based system. Second, this paper presents a new feed-water controller under the automatic power regulating system (APR) for Taipower’s Lungmen ABWR type NPP (LMNPP). The new feed-water controller is designed by using a rule-based hierarchical fuzzy logic control algorithm and is implemented by using the modern FPGA technology. The FPGA-based feed-water controller is integrated into the LMNPP’s full-scope engineering simulator with APR system for validation and performance evaluation. Under automatic power maneuvers, two trajectories in the power/flow map have been tested and compared with the origin design. The transient response and the steady state tracking capability are evaluated and showed satisfactory results. The results demonstrate that the FPGA-based hierarchical fuzzy logic controller is a practical approach for automatic power operations in advanced nuclear power plant applications. Third, this paper presents the system assessment of a quad-redundant RPS system design for Taipower’s Lungmen ABWR type NPP by utilizing FPGA technology. The FPGA-based RPS system has been assessed by using the LMNPP’s full-scope engineering simulator. Accident scenarios and abnormal conditions are inserted into the engineering simulator in order to activate the function of the FPGA-based RPS. The assessment results demonstrate that the FPGA-based nuclear instrumentation and control system is a practical approach to implement a diverse backup for nuclear power plant applications and can easily be used for the modernization of Taipower’s nuclear power plant analog systems. The software-free FPGA-based system may reduce the safety risk of undetectable software faults and common cause failures, and also minimize the regulatory licensing efforts and cost. Final, the sensitivity study of probabilistic risk assessment (PRA) shows that RPS combined with ARI (Alternative Rod Insertion) contributes significant influence on the core damage frequency (CDF) calculation of LMNPP. The PRA sensitivity study is independent of the RPS technology.