Tutorial on Fundamentals of External Hazard Probabilistic Risk Assessment and Its Use in Risk-Informed, Performance-Based (RIPB) Applications

Date: Friday August 9, 2019

Time: 8:30 a.m. - 3:30 p.m.

Dedication:  This tutorial is dedicated to the memory of Dr. Robert P. Kennedy. Dr. Kennedy was the primary developer and motivator of the concepts, methods, and applications of the subjects discussed in this tutorial.

The prime objective of this tutorial is to familiarize participants who are inexperienced with PRA (probabilistic risk assessment) in general and with external hazard PRA in particular, with an emphasis on seismic PRA (SPRA) as a well-established and practiced methodology, and its applications to risk-informed decisions including the regulatory framework now under active development for the new advanced reactor designs. A second objective of this tutorial in the venue of SMiRT-25 is to motivate newcomers to become practitioners in this important area.

PRAs and risk results and other insights that they provide are already being incorporated along with the traditional deterministic framework to understand safety, and to improve safety and performance.  Our knowledge of natural hazards is continually improving which requires frequent evaluation of how new knowledge affects plant safety.  The PRA methods and results provide a very efficient mechanism to address this concern as exemplified by the recent implementation of the NRC's post-Fukushima Near Term Task Force recommendation 2.1 (NTTF 2.1) on external-hazards PRA. Also, the next phase of the nuclear power industry is the development of advanced reactors.  Both the industry and NRC are moving toward a more risk-informed regulatory framework.  The industry and regulators in the past have suffered from the lack of availability of knowledgeable and expert resources in some areas of PRA technologies.  This lack of resources may become more acute as we move toward implementation of a more risk-informed regulatory framework for the new generation of power plants.


Tentative outline of the tutorial:

Introduction and Keynote Lecture

Robert Budnitz

SPRA Methodology

    Hazard Analysis

Nilesh Chokshi 

    Plant Response/System Analysis

Robert Budnitz 

    Fragility Analysis

Gregory Hardy  

Application of SPRA

Mehdi Reisi Fard

John Richards

RIPB for Advanced Reactors

Amir Afzali

Nilesh Chokshi

International Panel on Use of

SPRA & SPRA Framework


Andrei Blahoianu


Nilesh Chokshi

Amir Afzali

Tsuyoshi Takada

Toshiaki Sakai

Emmanuel Viallet


Nilesh Chokshi