External Hazards Home Page
This wiki provides a structured and accessible overview of external hazards as they pertain to the risk assessment, hazard characterization, and operational resilience of nuclear power plants (NPPs). External hazards such as high winds, flooding, wildfires, extreme precipitation, and extreme heat events can potentially pose significant risks to NPPs. Understanding and mitigating these risks is essential for ensuring operational continuity, regulatory compliance, and public safety.
This wiki is designed for engineers, analysts, and technical professionals who are either new to the domain or seeking to apply industry guidance and methodologies in their work. It serves as both an educational resource and a practical reference, mapping out the landscape of external hazard assessment in the nuclear sector.
How External Hazards Are Managed
The nuclear industry addresses external hazards through a process that begins with identifying site-specific hazards and proceeds through hazard characterization, exposure assessment, and vulnerability assessment. Deterministic evaluation forms the foundation of this process, confirming that safety-related structures, systems, and components can withstand design basis hazard levels with adequate margins. Where additional insights are needed, probabilistic risk assessment and related analyses complement the deterministic evaluation by assessing risk across a broader range of scenarios. Mitigation, adaptation, and periodic reassessment can feed updated information back into the process, ensuring that the evaluations remain current as new data, methods, and operating experience become available.
The major sections of this wiki map directly to stages in this process. The Foundations and Catalog of Hazards pages address hazard identification and characterization. Methods and Tools covers the analytical approaches used for exposure assessment, vulnerability assessment, deterministic evaluation, and risk quantification. Industry Experience draws on operating experience to inform mitigation strategies.
Start Here
Choose a path based on what you need:
I'm New to External Hazards
- Foundations — What external hazards are and why they matter
- How External Hazards Are Addressed — The big picture
- Terms and Definitions — Key terminology
- Historical Context — How the field evolved
I Need Information on a Specific Hazard
- Overview pages for each hazard type
- Mechanisms, effects, and assessment approaches
- Hazard-specific references and guidance
I Have a Quick Question
- Common questions about external hazards
- Clarifications on terminology and scope
Site Map
The map below shows all pages in this wiki. Bold links are active pages with full content; italic links are under development and currently contain summary placeholders.
- Screening and Prioritization
- Deterministic Approaches
- Beyond Design Basis
- Probabilistic Risk Assessment
- Walkdowns and Field Verification
- Tornado Missile Risk Evaluator (TMRE)
- Tornado Missile Strike Calculator (TMSC)
- Probabilistic Flood Hazard Assessment (PFHA) Tools
- Joint Probability Method (JPM)
- Climate Vulnerability Assessment (CVA)
- CHIP Climate Projections
- Related Resources
- PRA Info landing page (parent program)
Intended Audience
This wiki is tailored for professionals working in nuclear safety, risk management, and plant operations:
- New engineers and analysts seeking to gain an overall understanding of external hazards.
- Experienced engineers and analysts seeking:
- Industry references, or
- Context for a specific type of assessment
EPRI technical point of contact: Chris Rochon (CRochon@epri.com)
Date last reviewed: 2026-06-02