Nuclear Detonation

A nuclear weapon is a device that uses a nuclear reaction to create an explosion with intense light, heat, a damaging pressure wave, and widespread radioactive material that can cause significant damage and casualties and contaminate the air, water, and ground surfaces for miles around. All nuclear devices cause deadly effects when detonated. Device types include a weapon carried by an intercontinental missile launched by a hostile nation or a small and portable Improvised Nuclear Device (IND) set off by a terrorist organization or other individual.

Disaster Planning
Nuclear Event
man wearing a gas mask

Likely Targets


strategic missile sites, military bases


centers like Washington, DC, state capitals


important transportation, major ports, airfields


communication centers, electrical power plants


manufacturing, industrial, technology, financial centers

Oil & Gas

petroleum refineries, chemical plants

Factors for degree of damage

Degree of Damage


weapon’s yield in kilotons or megatons


specifics of design and fuel used


explosion in the air (EMP) or at earth’s surface


densely or sparsely populated areas


time of year, time of day, weather conditions

imagery of a nuclear missle launch
Disaster Planning
What a Nuclear Detonation Does

An explosion will release three distinct forms of destructive energy: explosive blast, radiation, and fallout.

Explosive Blast

The blast can cause death, injury, and damage to structures several miles out. Much of the damage inflicted by a nuclear explosion is the result of its shock wave. There are two components to a blast’s shock wave: pressure and wind.

Wall of pressure - First, there’s the wall of pressure that expands outward from the explosion. It is this pressure, measured in psi (pounds per square inch), that blows away the walls of buildings. A typical two-story house subjected to 5 psi would feel the force of 180 tons on the side facing the blast.

Wind - Additionally, the blast creates a 160-mile-an-hour wind. And that’s only at 5 psi. The wind speed following a 20-psi blast would be 500 mph!


Radiation is energy that is released and travels at the speed of light. There are two types of radiation released: direct nuclear and thermal.

Direct Nuclear - The nuclear fission necessary to create the explosion releases gamma rays that damage the cells of the body and cause radiation sickness and/or death.

Thermal - Thermal radiation produces the intensely bright flash of light viewed hundreds of miles away causing temporary blindness for many who view the blast. Thermal radiation is intensely hot. Its heat and fire can cause death, burn injuries, and damage to structures several miles out. The damage a one-megaton explosion can cause varies based on several factors - see above. Here is an estimate of the possible damage this can cause to people even miles away.

  • 7 miles away = 1st degree burns
  • 6 miles away = 2nd degree burns
  • 5 miles away = 3rd degree burns

Radioactive Fallout

Nuclear Fallout refers to the radioactive material that descends slowly from the atmosphere after a nuclear detonation. When a nuclear weapon is detonated aboveground, radioactive materials are sent as high as 50 miles into the atmosphere.

The fallout pattern depends on wind speed, wind direction, and terrain. Being downwind will significantly affect how quickly fallout reaches your location.

Large particles fall to the ground near the explosion site, but lighter particles and gases travel into the upper atmosphere. The particles that are swept up into the atmosphere and fall back down to Earth are called fallout. These particles emit penetrating radiation that can cause radiation exposure and can injure people.

Radiation Sickness Symptoms

  • skin redness and blistering
  • bleeding from nose, mouth
  • bleeding from rectum
  • bloody stool and diarrhea
  • nausea and vomiting blood
  • confusion and fainting
  • fatigue and weakness
  • dehydration and fever
  • bruising and hair loss
  • skin inflammation
  • open sores on the skin
  • sloughing of skin
  • ulcers of mouth
  • ulcers of esophagus
  • ulcers of intestines
  • ulcers of stomach
Disaster Planning
Before a Nuclear Event Happens

What to Do Before

choose a shelter location | learn protection protocol | store supplies | create a hazard kit

For those living outside of ground zero, there are steps you can take to help mitigate the damage that can be done by a nuclear explosion and resulting fallout.

What to Do Before

For those living outside of ground zero, there are steps you can take to help mitigate the damage that can be done by a nuclear explosion and resulting fallout.

Choose a Shelter Location

Identify the best shelter location at home and near where you spend a lot of time, such as work and school. If you spend a lot of time commuting to work or other places, identify appropriate shelters you could use along the way.

Best locations
  • any place with thick and dense walls and roofs - brick or concrete buildings are best
  • underground areas like basements
  • if you don’t have a home basement, choose a room that can more easily be sealed off and be sure to stay away from outer walls
  • subways and tunnels
  • a windowless center area of middle floors in larger buildings
Unsafe locations
  • anywhere outside
  • any type of vehicle or mobile home

Learn Protection Protocol

The three factors to protecting yourself from a nuclear detonation are shielding, distance, and time. Any protection you can get, however temporary, is better than none. The more shielding, distance, and time you can take advantage of, the better off you will be.

Shielding - Protection from radioactive fallout would require taking shelter in an underground area or in the middle of a large building. The heavier and denser the materials - thick walls, concrete, bricks, books, and earth - between you and the fallout particles, the better.

Distance - The more distance between you and the fallout particles, the better. An underground area such as a home or office building basement offers more protection than the first floor of a building. A floor near the middle of a high-rise may be better, depending on what is nearby at that level on which significant fallout particles would collect. Flat roofs collect fallout particles, so the top floor is not a good choice, nor is a floor adjacent to a neighboring flat roof.

Time - Fallout radiation loses its intensity rapidly. After the first 24 hours, it has reduced by 80%. You should not leave your shelter during this time. Radioactive fallout poses the greatest threat to people during the first two weeks, by which time it has declined to about 1% of its initial radiation level. Your safest bet is to stay put for two weeks. If you're not home, that may not be possible.

Store Emergency Kits

Make sure you have emergency kits stored at home and at places you frequent just in case you need to shelter-in-place for at least 24 hours.

Grab & Go Bags

You don't have to evacuate from your home to reap the benefits of an evacuation kit. If you need to shelter in place for at least 24 hours to avoid the most dangerous fallout period, having a grab & go bag for each family member will give you food, water, cell phone charging capability, a hand-crank or other battery-powered radio, and other supplies to help see you through. It will even provide a change of clothing if decontamination is needed. Just make sure you grab your supplies on your way to your in-home shelter location.

Away-from-home Kits

If your child is at school or you are at work when shelter-in-place is necessary, a school kit and office kit will provide you with much-appreciated supplies. If you are driving and have to take shelter inside a building, you'll be able to grab your auto kit which will provide some of the same supplies.

Creating a Hazard Kit

A hazard kit will provide aid and protection against multiple hazards. Some items overlap and can be useful for different types of hazards. Store your hazards kit in the room designated for shelter-in-place.

  • Mira Safety CM-6M gas mask and filters
  • N95 particulate respirator
  • radiation detector - RadTriage or Geiger
  • potassium iodide
  • disposable gloves
  • duct tape, scissors & plastic sheeting
  • towels, wax paper, or foil
  • heavy duty trash bags
  • soap, baby shampoo & sponge
Disaster Planning
During a Nuclear Event

What to Do During

get inside | stay inside | stay tuned | decontaminate if exposed

Fallout is most dangerous in the first few hours after the detonation when it gives off the highest levels of radiation. It takes time for fallout to reach ground level, often more than 15 minutes for areas outside the immediate blast damage zones. This is enough time for you to be able to prevent significant radiation exposure by following some simple steps.

What to Do During

Fallout is most dangerous in the first few hours after the detonation when it gives off the highest levels of radiation. It takes time for fallout to reach ground level, often more than 15 minutes for areas outside the immediate blast damage zones. This is enough time for you to be able to prevent significant radiation exposure by following some simple steps.

Get Inside

When an attack is either imminent or happening, act out the 3-factors of protection.

With a warning

  • Act immediately
  • If you are home, grab your kids, your pets, your grab & go bags, and head to your shelter location.
  • If you're outside, immediately get inside the nearest building and move away from the window. This will help protect from the blast, heat, and radiation of the detonation.
  • If you are driving, keep the car windows and vents closed and use recirculating air. Pull over and find a sturdy building and go inside. Take your auto kit with you.

Without a warning

  • Do not look at the flash or fireball – it can blind you.
  • Take cover from the blast behind anything that might offer protection. Lie face down on the ground and cover your head to protect exposed skin from the heat and flying debris. If the explosion is some distance away, it could take 30 seconds or more for the blast wave to hit.
  • If you are in a vehicle, stop safely, and duck down within the vehicle.
  • After the shock wave passes, get inside the nearest but best-suited shelter location (like a basement or the middle of a building) for protection from potential fallout.
  • You may have 10 minutes or more before the fallout arrives to find an adequate shelter, depending on how close you are to the blast.
  • Be inside before the fallout arrives.
  • If fallout hits before you can get inside, once inside, follow decontamination procedures - see below.

Stay Inside

Once inside, stay where you are, even if you are separated from your family.

  • Inside is the safest place for all people in the impacted area.
  • Radiation levels are extremely dangerous right after the blast, then dissipate from there. At hour 24, the levels will have reduced dramatically.
  • Expect to stay where you are at least 24 hours unless told otherwise by officials.
  • Family should stay where they are inside. Reunite later to avoid exposure to dangerous radiation.
  • Keep your pets with you.

Stay Tuned

This is the time to be cautious and listen to the authories for guidance.

  • Battery-operated and hand-crank radios will function after a nuclear detonation. Cell phone, text messaging, television, and internet services may be disrupted or unavailable.
  • Tune into any media available for official information from emergency response officials.
  • If advised to evacuate, listen for information about routes, shelters, and procedures.
  • If you get evacuated, do not return until you are told it is safe to do so by local officials.


If you were outside when the fallout reached your area, get clean as soon as possible, to remove radioactive material that may have settled on your body.

  • Remove your outer layer of contaminated clothing to remove fallout and radiation from your body. This can remove up to 90% of radioactive material.
  • If practical, place your contaminated clothing in a plastic bag and seal or tie the bag. Place the bag as far away as possible from humans and animals so that the radiation it gives off does not affect others.
  • When possible, take a shower with lots of soap and water to help remove radioactive contamination from any skin or hair that was not covered. Do not scrub or scratch the skin.
  • Wash your hair with shampoo or soap and water. Do not use conditioner in your hair because it will bind radioactive material to your hair, keeping it from rinsing out easily.
  • Gently blow your nose and wipe your eyelids and eyelashes with a clean wet cloth. Gently wipe your ears.
  • If you cannot shower, use a wipe, or clean wet cloth to wipe your skin that was not covered by clothing.
  • Clean any pets that were outside after the fallout arrived. Gently brush your pet’s coat to remove any fallout particles and wash your pet with soap and water, if available.
Disaster Planning
After a Nuclear Event

What to Do After

taking potassium iodide | ending shelter-in-place | staying safe

The worst may be over but what happens next? Should you personally take potassium iodide? When can you come out of shelter? Being careful afterwards is just as crucial to your health.

What to Do After

The worst may be over but what happens next? Should you personally take potassium iodide? When can you come out of shelter? Being careful afterwards is just as crucial to your health.

Taking Potassium Iodide

Potassium iodide (KI) is a type of iodine that is not radioactive and can be used to help block one type of radioactive material, radioactive iodine (I-131), from being absorbed by the thyroid. It does not protect other parts of the body from other types of radiation.

Should you take KI after a nuclear blast?
  • Do NOT take KI unless instructed by a public health or emergency response official, or healthcare provider.
  • There are limits as to who should use KI and how much it can help.
  • It is recommended only for people under 40, and those who are pregnant or breastfeeding.
  • Doses recommended by the U.S. FDA depend on age.
  • KI can have harmful effects if not needed or not taken correctly.
  • Only use KI products that are approved by the U.S. FDA.

Ending Shelter-in-Place

  • The heaviest fallout would be limited to the area at or downwind of the explosion. 80% of the fallout would have occurred by the first 24 hours. Most people in these affected areas would most likely be allowed to come out of the shelter within a few days. If necessary, they will be evacuated to unaffected areas.
  • Always listen to your local emergency leaders for important news that may inlude information about when you can leave your shelter area, what you should do next, where you should go, and places to avoid. If you have been evacuated, return home only when instructed to do so.

Staying Safe

  • It is safe to eat or drink packaged food items or items that were inside a building. Do not consume food or liquids that were uncovered outdoors and may be contaminated by fallout.
  • If you are sick or injured, listen for instructions on how and where to get medical attention when authorities tell you it is safe to exit.
  • Stay away from damaged areas until they have been repaired.
  • Stay away from areas marked “radiation hazard” or “hazmat”.