Methodological and Practical Comparison of Integrated Probabilistic Risk Assessment (I-PRA) with the Existing Fire PRA of Nuclear Power Plants

Tatsuya Sakurahara, Zahra Mohaghegh, Seyed Reihani, Ernie Kee

Research output: Contribution to journalArticlepeer-review


Nearly half of the U.S. nuclear power plants (NPPs) are in the process of transitioning, or have already transitioned, to a risk-informed, performance-based fire protection program. For this transition, Fire Probabilistic Risk Assessment (Fire PRA) is used as a foundation for fire risk evaluation. To increase realism in Fire PRA by reducing conservative bias, the authors have developed an Integrated Probabilistic Risk Assessment (I-PRA) methodological framework that does not require major changes to the existing plant Probabilistic Risk Assessments (PRAs). The underlying failure mechanism models associated with fire events are developed in a separate module, which can be interfaced and connected to the existing plant PRA. This paper explains the areas of methodological advancements in I-PRA, comparing them with the existing Fire PRA of NPPs. This comparison is further demonstrated in a realistic case study that applies the I-PRA framework to a critical fire-induced scenario at an NPP. The core damage frequency (CDF) for the selected scenario, computed by the I-PRA framework, is compared with the results of the Full Compartment Burn screening method and the existing Fire PRA methodology. Using the I-PRA framework, the CDF for the selected scenario has decreased by a factor of 20 compared with the Full Compartment Burn screening approach and by a factor of 2 compared to the existing Fire PRA methodology based on NUREG/CR-6850 and the subsequent NUREGs that have updated the data and methods for individual steps.

Original languageEnglish (US)
Pages (from-to)354-377
Number of pages24
JournalNuclear Technology
Issue number3
StatePublished - Dec 2 2018


  • Fire Probabilistic Risk Assessment
  • Integrated Probabilistic Risk Assessment framework
  • NUREG/CR-6850

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Condensed Matter Physics


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