Industry Experience
INDUSTRY EXPERIENCE
Operating experience from plant events, regulatory actions, and industry studies provides essential context for understanding how external hazards affect nuclear power plants in practice. The pages in this section organize significant events, recurring lessons, and mitigation strategies drawn from licensee event reports, NRC communications, INPO guidance, and EPRI technical studies. Content in this section is drawn from operating experience and industry studies — it provides practical context for the hazard overview and methods pages but is not a substitute for formal guidance or regulatory requirements.
How to Use This Section
Each industry experience page is organized around individual hazards areas and follows a common structure:
- Key Industry Events — summary table of significant events that have affected or challenged nuclear plants
- Sources of Operating Experience — the databases, reporting systems, and publications that document plant-level events
- Mitigation Strategies — protective measures and operational practices that have been implemented across the fleet
- Lessons Learned — recurring themes and common failure modes
These pages draw on publicly available reports and findings from industry assessments. Where an event or finding originates from a proprietary source, it is anonymized without attribution to a specific utility or site.
Industry Experience Pages
| Hazard Area | Scope | Key Themes |
|---|---|---|
| High Winds | Tornadoes, hurricanes, straight-line winds, and wind-borne missiles | Missile protection configurations and barrier considerations; LOOP at high wind speeds; pre-storm preparation; portable mitigation equipment deployment under wind conditions |
| External Flooding | Riverine, coastal, storm surge, tsunami, dam failure, local intense precipitation | Fukushima lessons; sustained riverine flood response; flood barrier maintenance |
| Extreme Temperature | Extreme heat, elevated cooling water temperatures, cold weather events | Discharge-limit shutdowns and derates; cooling water intake temperature exceedances; cold-weather equipment protection; climate vulnerability assessment findings |
| Wildfire | Wildfire-related threats to nuclear plant sites and adjacent transmission infrastructure | Electrical grid disruption; smoke and air quality effects; vegetation management; access and egress challenges |
| Compound and Cascading Hazards | Multi-hazard scenarios involving concurrent or sequential external events | Combined wind and flood events; seismic-induced flooding; multi-unit dependency challenges |
Recurring Observations Across Hazards
Several observations recur across hazard areas and are worth noting for analysts approaching any external hazard:
- Pre-event preparation is an important determinant of outcome. Events where plants had time to prepare and execute established procedures consistently resulted in better outcomes than events with limited warning time.
- Loss of offsite power is common amongst external hazards events. Across all external hazard types, LOOP is the most frequently observed plant-level consequence, making LOOP recovery and diesel generator reliability central concerns.
- Multi-unit sites require explicit staffing and resource assumptions. Large external events generally affect all units at a multi-unit site in a similar way and within the same timeframe, exposing dependencies between shared systems, staffing, and staged mitigation equipment. The Fukushima accident demonstrated the importance of evaluating those dependencies explicitly rather than assuming that each unit can be managed independently.
- Flood and wind protection features depend on maintenance. Multiple NRC information notices and inspection findings have documented degraded barriers, failed penetration seals, and procedural deficiencies that reduced the effectiveness of installed protection.
- Climate trends are shifting the baseline. Industry climate vulnerability assessments have identified that historical hazard frequencies and intensities may not bound future conditions, supporting proactive assessment of operating and design margins as part of ongoing margin management [3002023814].
Related Pages
- Catalog of Hazards — hazard descriptions and assessment approaches
- Historical Context and Evolution — evolution of external hazard regulation
EPRI technical point of contact: Chris Rochon (CRochon@epri.com)
Date last reviewed: 2026-05-27