Integrated Fire Probabilistic Risk Assessment (PRA) Modeling in Support of Operational Efficiency

Fire Probabilistic Risk Assessment (PRA) has been a challenging area for the safe operation and regulation of nuclear power plants (NPPs) due to the complex and dynamic progression of underlying physical failure mechanisms and their interaction with human actions affecting systems, structures, and components (SSCs). Since the introduction of risk‐informed, performance‐based fire protection approaches in 2005, the U.S. NRC and the nuclear industry have faced many obstacles in their efforts to increase realism in Fire PRAs (Criterion b.1, second bullet). The NFPA‐805 Fire PRA transition is highly resource‐intensive, and the advantages of a risk‐informed, performance‐based approach have not yet been fully realized due to excessive conservatism in the current Fire PRA methodology. This research aims to improve the efficiency of risk-informed, performance‐based fire protection for NPPs by advancing the current Fire PRA methodology using a risk-informed strategy originated by Co‐PI Professor Zahra Mohaghegh from the University of Illinois at Urbana‐Champaign (UIUC). (See IND FOA FY2019 Resume Mohaghegh ARD‐19‐17979.pdf.) The three‐phase strategy implemented in this research is as follows:

• Phase I: Development of a streamlined approach to performing more efficient screening of Fire PRA scenarios for limiting the number of fire scenarios that need detailed Fire PRA modeling.
• Phase II: Implementation of an Integrated PRA (I‐PRA) methodological framework to reduce the excessive conservatism (i.e., increase the realism) in the current Fire PRA methodology by adding more explicitness and resolution to the underlying physics and human performance models.
• Phase III: Conduct experimental validation of fire brigade performance models to justify their incorporation into I‐PRA. Experiments will be conducted at the Illinois Fire Service Institute (IFSI) (see IND FOA FY2019 Capabilities ARD‐19‐17979.pdf) to run live scenarios of Fire Brigade response in an Auxiliary Building Switchgear compartment.