ICONE19-43159 Conceptual Design of an FPGA-Based AMSAC System for Taiwan's Maanshan NPP

Abstract

Maanshan nuclear power plant (NPP) is the third NPP operated by Taiwan Power Company (TPC) for more than 20 years. The anticipated-transient-without-scam mitigation system and actuation circuit (AMSAC) for Maanshan NPP was implemented based on microprocessor technology, and the obsolete issue will soon become a problem. With microprocessor design, undetectable software faults and common cause failures may exist. It is worthwhile to investigate an alternative digital design approach in advance. The field programmable gate array (FPGA) technology has been used extensively for commercial applications and has also gained regulatory acceptance recently for nuclear power plant applications. The present research is to explore the feasibility and conceptual design of using triple-redundant FPGA-based AMSAC system in Maanshan NPP. The AMSAC is a diverse and backup system for reactor protection system (RPS), and prevent primary pressure exceed 3200psig if an anticipated-transient-without-scam (ATWS) event occurs. The requirements of AMSAC system are to provide turbine trip, start auxiliary feedwater, and isolate stream generators. Due to flash-based technology, superior reliability, and 128-bit write-protection-security, Actel's FPGAs are widely used in military and space applications. Actel's SmartFusion mixed signal FPGA chip is chosen to be the target FPGA platform, which integrates flash-based FPGA, 32-bit ARM Cortex-M3 MCU, programmable analog and digital peripherals, to offer customization, IP-protection, and ease-of-use development tools. SamrtFusion FPGA is ideal for true system-on-chip (SoC) solutions. Programmable analog peripherals of SamrtFusion chip include 12-bit SAR ADCs, Sigma-Delta DACs, voltage/current/temperature monitors, high-speed comparators and up to 32 analog inputs/outputs. The proposed FPGA-based board contains SRAM, UART, 10/100 Ethernet. SRAM is partitioned into two divisions, all are fully Readable/Writeable for FPGA-Fabric, and only one division is read-only for UART to transmit status. UART is connected to NPP/Simulator for real-time monitoring or portable computer for maintenance purpose. The MCU integrated with 10/100 Ethernet are reserved for connecting to NPP's plant computers for non-safety-related processes in future expansions. The proposed FPGA-based AMSAC system contents three divisions, each division includes an independent FPGA board and DC power supply. A software Verification and Validation Plan (V&VP) is developed at the beginning of the study, and will be processed during the whole development lifetime. A Maanshan NPP engineering simulator with modeling of reactor and plant systems will be developed to provides an integrated-dynamic-interactive test environment to validate the triple-redundant FPGA-based AMSAC system. The software-free FPGA-based nuclear instrumentation and control systems (I&C) can easily be used for the modernization of the TPC's nuclear power plant analog systems and thus may reduce regulatory licensing efforts and cost.