ScholarWorks@중앙대학교

초록

The nuclear power industry faces increasing challenges due to a shrinking supplier base for safety-critical digital instrumentation and control (I&C) systems and stringent regulatory requirements. To address these challenges, the adoption of IEC 61508 Safety Integrity Level (SIL) certified commercial digital devices has been proposed as a viable alternative. This study investigates the applicability of IEC 61508 SIL-certified devices within nuclear power plant I&C systems, specifically assessing their suitability through Probabilistic Safety Assessment (PSA) and risk model calculations using AIMS-PSA. The Reactor Protection System (RPS), a critical safety system, must be assigned SIL3 to ensure compliance with nuclear safety requirements. Since the RPS is designed as a 2-out-of-4 (2oo4) system, the SIL of each RPS channel depends on common cause failure (CCF) probability and is determined as SIL2 or SIL3. This study highlights how PSA's risk-informed methodology can refine safety integrity requirements, ensuring a systematic, quantitative approach to evaluating the integration of SIL-certified commercial-grade digital devices in nuclear applications. By leveraging third-party certification frameworks like IEC 61508, nuclear utilities can enhance regulatory compliance while ensuring a stable supply of digital equipment, potentially replacing traditional commercial-grade dedication (CGD) processes. This research establishes a robust, risk-informed assessment methodology for integrating commercial digital devices into nuclear safety-critical systems, enhancing the reliability, practicality, and regulatory acceptance of CGI implementation in the nuclear power sector.

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