Potential Failure Mode Screening Analysis

The introduction of potential failure mode analysis (PFMA) to dam safety practice has been a positive development. Any time new methods or approaches are implemented in practice there is a period of development that adds efficiency and consistency to future applications. In the case of PFMA, there continues to be an evolution in practice and guidance as failure, near-failure, and fail-to-function incidents are observed and studied. For instance, major events such as the 2017 Oroville Spillway Incident precipitated changes to the Federal Energy Regulatory Commission engineering guidelines on PFMA. As the industry moves beyond considering and developing modes of failure to making either semi-quantitative or quantitative estimates of risk, a logical and rational screening process is necessary to focus efforts to timely dam-safety decision making while not missing risk contributors due to arbitrary, biased, or overly subjective screening processes. In this paper we discuss the screening of potential failure modes in the context of performing a Quantitative Risk Analysis (QRA) for dams.