A Study on Quantification of Operator Manual Action for Fire PSA

The purpose of this paper is to describe the fire HRA (Human Reliability Analysis) method for domestic fire PSA (Probabilistic Safety Assessment) at full power operation and considerations for quantifying OMA (Operator Manual Action) using the fire HRA method. OMAs are actions performed by operators to manipulate components and equipment from outside the MCR (Main Control Room) to achieve and maintain post-fire hot shutdown, but do not include "repairs" by NUREG-1852. NEI 00-01 classified impacted cable/component by MSO (Multiple Spurious Operation) as either a required or important to safe shutdown cable/component and established OMA as one of the measures to mitigate the effects of MSO of the important to safe shutdown cable/component for fire area assessment. More broadly NRC defined post-fire OMA as actions performed by plant personnel on plant equipment to recover from a fire outside MCR. Currently, domestic NPPs have selected OMAs to mitigate MSO by considering the feasibility and reliability factors in way of a deterministic approach based on NUREG-1852. In this study, the existing fire HRA method is reviewed to quantify OMA to model it into fire PSA. To achieve this goal, complementary factors of the fire HRA method for OMA quantification such as wearing SCBA (Self-Contained Breathing Apparatus) outside MCR and the need to establish detailed timelines to model the relation between MCRA (Main Control Room Abandonment) and OMA were derived.

Keywords: Fire human reliability analysis, Operator manual action, Multiple spurious operation.

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