Your Local Risks · Hazard Guide
Nuclear and radiological incidents are among the least likely emergencies most Americans will face — but they require specific responses that differ from other hazards. Knowing what to do in advance makes a significant difference in outcome.
Scope of this guide
This page covers nuclear and radiological incidents in the context of infrastructure accidents — nuclear power plant emergencies and radiological material accidents — not weapons scenarios. The most relevant U.S. precedent is the 1979 Three Mile Island accident in Pennsylvania, where a partial reactor meltdown led to the precautionary evacuation of pregnant women and young children within a 5-mile radius. No one was killed by the accident, but it reshaped how the U.S. regulates nuclear power and communicates with surrounding communities.
There are 93 operating nuclear reactors at 55 power plant sites across the United States. About 3 million people live within 10 miles of a nuclear power plant. If you are among them, the preparation steps on this page are specifically relevant to you. If you are not, your relevant nuclear preparedness question is likely radiological material transport incidents — which happen along transportation corridors throughout the country.
Our approach: All preparedness steps on this page are drawn from official federal and state guidance — FEMA, the NRC, and state emergency management agencies. We do not speculate beyond official guidance on nuclear topics.
Types of incidents
The most likely significant nuclear incident in the U.S. involves a reactor at an existing power plant. Plants are classified on a 1–7 scale (Three Mile Island was a 5; Chernobyl and Fukushima were 7). The NRC and state agencies maintain active communication with communities in Emergency Planning Zones.
Who it affects: residents within ~50 miles
Radioactive materials are transported by road, rail, and air for medical, industrial, and research purposes. Transportation accidents involving these materials require specific emergency response but typically affect a localized area. Follow emergency management instructions; do not approach the scene.
Who it affects: nearby residents along corridor
A radiological dispersal event involves conventional materials spreading radioactive material over a limited area. The primary responses — shelter-in-place, evacuation of a defined area, decontamination — are managed by hazmat and emergency management teams. Follow official instructions.
Who it affects: localized area; follow official guidance
The protocol
FEMA's guidance for nuclear and radiological incidents follows a consistent three-step framework. These three actions apply to virtually all nuclear emergency scenarios and are the most protective immediate response available to a household.
Any substantial building reduces your exposure to external radiation significantly. A brick or concrete building provides considerably more protection than a wood-frame home. A basement provides more protection than above-ground floors. Get inside the most substantial structure available and move to the interior, away from windows.
Close all windows and doors. Shut off HVAC, air conditioning, and all ventilation systems. The goal is to minimize the amount of outside air entering the building. Keep doors and windows closed until official guidance says it is safe to open them or to leave.
Monitor your NOAA weather radio, local TV, or your county emergency management agency's official channels. Follow all official instructions, including any direction to take potassium iodide if it is being distributed, when to evacuate, and when it is safe to return to normal activities.
Before it happens
If you live within 10 miles of a nuclear power plant, contact your county emergency management agency to register for Emergency Planning Zone notifications. Most utilities also mail preparedness information to residents in the EPZ annually.
The Emergency Planning Zone for your nearest nuclear plant will have designated evacuation routes. Know them before you need them. Your county emergency management agency publishes these routes; your nuclear utility may also include them in their annual household mailing.
Some states distribute potassium iodide (KI) to households within 10 miles of nuclear power plants. Contact your state emergency management agency to determine if your area participates in a KI distribution program. Follow official dosing and timing guidance — KI is only protective when used correctly for the right type of exposure.
A battery-powered NOAA weather radio is the most reliable notification system for nuclear and radiological alerts, particularly if power and cell service are disrupted. It is also the most useful preparedness item for every other hazard on this site — one investment covers multiple scenarios.
Official resources
For nuclear and radiological preparedness, we direct you to primary official sources. These agencies maintain current, verified guidance that reflects actual regulatory frameworks and emergency planning requirements.
The foundation
The most important preparation for nuclear and radiological incidents is knowing how you'll receive official guidance quickly. The Your Local Risks hub walks through signing up for county alerts, identifying your nearest emergency management contacts, and building the NOAA radio setup that works when other systems don't.
Set up your local alerts