Review of Fire Common Mode Analysis and Probabilistic Safety Assessment of Fire Common Modes for an Operating Nuclear Power Plant

Abstract

Fire common mode analysis (a.k.a. Fire Vulnerability Analysis, FVA) is usually performed after the completion of the design of a nuclear power plant. Any discrepancies in equipment or cable layout during the construction or operation phases could result in new potential fire common modes, which pose new safety threats to the plant. Consequently, it is necessary to perform a review of the fire common mode analysis for an operating nuclear power plant. Any newly identified fire common modes that need to be addressed might require modification either by protection or by physical separation. In prioritizing the modifications regarding these fire common modes, probabilistic safety assessment (PSA) provides quantitative insights into the safety benefits of eliminating any newly identified fire common modes. This article introduces the general process of FVA and discusses the tasks of cable data collecting and plant walkdown, which are two fundamental steps of the process of FVA for an operating nuclear power plant. In the second part, an example is also provided of performing probabilistic safety assessment on fire common modes, based on which the analyst can prioritize the common mode list in terms of safety benefits if they are to be eliminated.