1

Workshop on Probabilistic Flood Hazard 

Assessment

Panel 1: Federal Agencies’ Interests 

and Needs in PFHA

Co-Chairs:

Nilesh Chokshi, NRC and Mark Blackburn, DOE

Rapporteurs:

Christopher Cook, NRC and Marie Pohida, NRC

January 29, 2012

Rockville, MD
Panel 1: Objective

Panel 1 will be a forum to highlight the participating 

Federal agencies’ interests and needs regarding 

Probabilistic Flood Hazard Assessments (PFHA). 

The presentations will include NRC staff’s 

perspectives on the development of a PFHA 

approach within a risk context. Other presentations 

will focus on probabilistic approaches presently 

used or under development by the participating 

agencies, as well as ongoing efforts to develop 

consensus standards.
Panel 1 Presentations

• NRC Staff Needs in PFHA ........................Fernando Ferrante, NRC

• Probabilistic Hazard Assessment Approaches: Transferable 

Methods from Seismic hazard...................Annie Kammerer, NRC

• Reclamation Dam Safety PFHA Perspective...J.ohn England, BOR

• FERC Need for PFHA...................................David Lord, FERC

• American Nuclear Society Standards Activities to Incorporate 

Probabilistic Approaches......John Stevenson & Ray Schneider, W
Panel 1 Panelists and 

Rapporteurs

• Panelists:

- Charles Ader, NRC

- Fernando Ferrante, NRC

- Annie Kammerer, NRC

- John England, BoR

- David Lord, FERC

- Patrick Regan, FERC

- John Stevenson, ANS-2.31

- Ray Schneider, Westinghouse

• Rapporteurs

- Christopher Cook, NRC

- Marie Pohida, NRC
Panel 1 Questions for 

Discussion

• What are the roles of deterministic and probabilistic hazard analysis in 

determining a design basis and conducting a risk assessment? How should 

they complement each other?

• What is the status of PFHA? For which flood causing mechanisms PFHAs 

can be conducted? What improvements are needed for their use in a risk 

assessment?

• Given the inherent large uncertainties, how should these be dealt with?

• What are the impediments, if any, for other flood causing mechanisms to 

develop PFHA approaches? How they can be overcome?

• What are your perceptions about the utility and usefulness of a PFHA for your 

agency missions?

• Is formal expert interaction approach like SSHAC a viable approach for 

PFHA? What PFHA specific consideration should be applied?

• Given the use of PFHA in the development of Design Basis Flooding 

determination, what is, or should be, the role of Beyond Design Basis 

Flooding in design and, if required how should it be determined?
Key Observations and Messages

• Risk-informed approaches are being used and are being 

incorporated in safety assessments and decision-making.

• It is not a question of deterministic vs. risk assessment. 

These are complementary processes.

• SSHAC type of approach is viable and has been used to 

systematically addresses issue of uncertainties considering 

the state-of-knowledge including lack of data for extreme 

events. 

• What are the impediments to a PFHA? – Willingness to try, 

availability of experts, communication. (Technical challenges 

are being met).

• Need for multi-disciplinary teams for assessments and need 

for incorporating risk analysis in educational systems
Path Forward

• Establish understanding of commonality and 

differences in risk-informed approaches and 

decision criteria among the federal agencies.

• Collaborative and coordinated efforts with other 

federal agencies, industry, standard bodies, and 

other stakeholders.

• Consider implementation of SSHAC type of 

approaches for selected hazards.