Overall
Why Prepare?
Citizen
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Basic Preparedness
Getting Informed
Planning and Checklists
Special Needs
Disaster Supplies Kit
Shelter
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Natural Hazards
Floods
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Tornadoes
Winter storms and extreme cold
Extreme heat
Earthquakes
Volcanoes
Landslides and debris flow
Tsunamis
Fires
Wildfires

Technological Hazards
Hazardous materials incidents
Household chemical emergencies
Nuclear power plant emergencies

Terrorism
Explosions
Biological threats
Chemical threats
Nuclear blasts
Radiological dispersion device events

Recovering from Disaster
Health and safety guidelines
Returning home
Seeking disaster assistance
Coping with disaster
Helping others
 

Nuclear Blast
A nuclear blast is an explosion with intense light and heat, a damaging pressure wave and widespread radioactive material that can contaminate the air, water and ground surfaces for miles around. All nuclear devices cause deadly effects when exploded, including blinding light, intense heat (thermal radiation), initial nuclear radiation, blast, fires started by the heat pulse and secondary fires caused by the destruction.

Hazards of Nuclear Devices

The extent, nature and arrival time of these hazards are difficult to predict. The geographical dispersion of hazard effects will be defined by the following:

The size of the device; a more powerful bomb will produce more distant effects.

Height above the ground the device was detonated. This will determine the extent of blast effects.

Nature of the surface beneath the explosion; some materials are more likely to become radioactive and airborne than others. Flat areas are more susceptible to blast effects.

Existing meteorological conditions; wind speed and direction will affect arrival time of fallout; precipitation may wash fallout from the atmosphere.


Radioactive Fallout

Even if individuals are not close enough to the nuclear blast to be affected by the direct impacts, they may be affected by radioactive fallout. Any nuclear blast results in some fallout. Blasts that occur near the earth’s surface create much greater amounts of fallout than blasts that occur at higher altitudes. This is because the tremendous heat produced from a nuclear blast causes an up-draft of air that forms the familiar mushroom cloud. When a blast occurs near the earth’s surface, millions of vaporized dirt particles are drawn into the cloud. As the heat diminishes, radioactive materials that have vaporized condense on the particles and fall back to Earth. This fallout material decays over a long period of time, and is the main source of residual nuclear radiation.
Fallout from a nuclear explosion may be carried by wind currents for hundreds of miles if the right conditions exist.
Nuclear radiation cannot be seen, smelled or otherwise detected by normal senses. Radiation can only be detected by radiation monitoring devices. This makes radiological emergencies different from other types of emergencies. Monitoring can project the fallout arrival times, which will be announced through official warning channels. However, any increase in surface build-up of gritty dust and dirt should be a warning for taking protective measures.
In addition to other effects, a nuclear weapon detonated in or above the earth’s atmosphere can create an electromagnetic pulse (EMP), a high-density electrical field. An EMP acts like a stroke of lightning but is stronger, faster and shorter. An EMP can seriously damage electronic devices connected to power sources or antennas. This includes communication systems, computers, electrical appliances and automobile or aircraft ignition systems. The damage could range from a minor interruption to actual burnout of components. Most electronic equipment within 1,000 miles of a high-altitude nuclear detonation could be affected. Battery-powered radios with short antennas generally would not be affected. Although an EMP is unlikely to harm most people, it could harm those with pacemakers or other implanted electronic devices.

Protection from a Nuclear Blast

The danger of a massive strategic nuclear attack on the United States is predicted by experts to be less likely today. However, terrorism, by nature, is unpredictable.
If there were threat of an attack, people living near potential targets could be advised to evacuate or they could decide on their own to evacuate to an area not considered a likely target. Protection from radioactive fallout would require taking shelter in an underground area or in the middle of a large building.
In general, potential targets include:
Strategic missile sites and military bases

Centers of government and state capitals

Important transportation and communication centers

Manufacturing, industrial, technology and financial centers

Petroleum refineries, electrical power plants and chemical plants

Major ports and airfields
The three factors for protecting oneself from radiation and fallout are distance, shielding and time.
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.

Shielding - the heavier and denser the materials between you and the fallout particles, the better.

Time - fallout radiation loses its intensity fairly rapidly. In time, you will be able to leave the fallout shelter. Radioactive fallout poses the greatest threat to people during the first two weeks, by which time it has declined to about 1 percent of its initial radiation level.
Remember that any protection, however temporary, is better than none at all, and the more shielding, distance and time you can take advantage of the better protection you have.

Take Protective Measures
What can I do Before a Nuclear Blast?

To prepare for a nuclear blast, you should do the following:

Find out from officials if any public buildings in your community have been designated as fallout shelters. If none have been designated, make your own list of potential shelters near your home, workplace and school. These places would include basements or the windowless center area of middle floors in high-rise buildings, as well as subways and tunnels

If you live in an apartment building or high-rise, talk to the manager about the safest place in the building for sheltering and about providing for building occupants until it is safe to go out

During periods of increased threat increase your disaster supplies to be adequate for up to two weeks
Taking shelter during a nuclear blast is absolutely necessary. There are two kinds of shelters - blast and fallout.
Blast shelters are specifically constructed to offer some protection against blast pressure, initial radiation, heat and fire

Fallout shelters do not need to be specially constructed for protecting against fallout. They can be any protected space, provided that the walls and roof are thick and dense enough to absorb the radiation given off by fallout particles


What do I do During a Nuclear Blast?
If an attack warning is issued:
Take cover as quickly as you can, below ground if possible, and stay there until instructed to do otherwise

Listen for official information and follow instructions
If you are caught outside and unable to get inside immediately:
Do not look at the flash or fireball - it can blind you

Take cover behind anything that might offer protection

Lie flat on the ground and cover your head.

If the explosion is some distance away, it could take 3 0 seconds or more for the blast wave to hit

Take shelter as soon as you can, even if you are many miles from ground zero where the attack occurred - radioactive fallout can be carried by the winds for hundreds of miles.

Remember the three protective factors: Distance, shielding and time.


What do I do After a Nuclear Blast?

Decay rates of the radioactive fallout are the same for any size nuclear device. However, the amount of fallout will vary based on the size of the device and its proximity to the ground. Therefore, it might be necessary for those in the areas with highest radiation levels to shelter for up to a month.
The heaviest fallout would be limited to the area at or downwind from the explosion and 80 percent of the fallout would occur during the first 24 hours.
People in most of the areas that would be affected could be allowed to come out of shelter within a few days and, if necessary, evacuate to unaffected areas.

Returning to Your Home

Remember the following:

Keep listening to the radio and television for news about what to do, where to go and places to avoid

Stay away from damaged areas.

Stay away from areas marked “radiation hazard” or “HAZMAT”
Follow the instructions for returning home