Hazard and Consequence Analysis for Digital Systems - A New Approach to Risk Analysis in the Digital Era for Nuclear Power Plants

摘要

Nuclear power plant (NPP) licensees may use several approaches and tools when assessing vulnerabilities and hazards. The United States Nuclear Regulatory Commission (NRC) and NPPs traditionally use fault tree analysis (FTA) and probabilistic risk assessment (PRA) extensively for risk analysis. Since 1975 and beginning with WASH-1400. NUREG/75-014 , the NRC and its licensees have used PRA to determine the likelihood that a hazard will occur and determine the frequency of associated consequences as a measure of risk , , .PRA has demonstrated substantial value to assessing risk in NPPs that rely heavily on analog and active systems. The ability of these traditional risk assessment tools to address potential failures and/or undesired behaviors of next generation NPPs will be challenged. Next generation NPPs (e.g., AP1000 and small modular reactors) are expected to rely more on digital and passive systems-whose behaviors are not as aligned with core tenets of reliability theory-as their predecessors. For example, cyber-attacks have not been shown to follow the probabilistic patterns necessary for PRA-type analysis. In addition, traditional risk assessment tools do not account for systems that perform their functions but still lead to inadequate behavior.