Fallout Shelter: nuclear weapon effects

Attacks

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These are some of the effects and consequences of an attack that Fallout Shelter reports on. Since there are so many, they are divided into separate screens you can rapidly switch between.

You can also change the time after burst or location. The effect values shown are immediately updated.

Mushroom cloud

As the nuclear fireball expands and cools, a radioactive cloud forms. The cloud rises rapidly. It will reach its maximum height after about ten minutes. The cloud will gradually spread out, taking on the famous mushroom appearance. It will be visible for about an hour before spreading too thin to be seen.

The altitude of the cloud's top and bottom are critical, because most of the radioactive fallout will be spread by the winds between those altitudes before being affected by surface winds.

If you can safely do so, you'll want to see the mushroom cloud. Not only so you can tell your grandchildren about it but because people who attended atmospheric weapon tests report that the cloud has an awesome beauty that photos only hint at. Much in the way that seeing a space shuttle launch on TV can't compare with the visceral experience of being there.

The other consolation is that you can expect great sunsets for many weeks. Not exactly fair trades for the devastation, though....

• stabilized top of cloud
• stabilized bottom of cloud
• stabilized radius of cloud

Cratering effects (ground bursts)

If a burst is low enough that the fireball touches the ground, the great heat of the burst will vaporize anything it touches. The word apparent is used because some of the debris will fall back into the crater.

• crater radius
• apparent crater depth
• apparent crater volume
• height of crater lip

Surface wave effects (water bursts)

If an enemy wanted to destroy a coastal city, like New York, an underwater burst near the harbor would probably be more deadly than a ground or air burst because much of the energy goes into producing an enormous wave, potentially large enough to drown the city.

• peak wave height
• wave height now

Blast effects

A nuclear explosion releases a lot of energy very quickly. This turns everything nearby into hot gases under high pressure. The gases spread out rapidly, triggering a shock wave through the air, water, and ground. This shock, or blast, wave is one of the first effects experienced.

SCIENTIFIC EFFECTS

• peak overpressure
• peak reflected overpressure
• peak dynamic overpressure
• overpressure now
• reflected overpressure now
• dynamic overpressure now
• shock wave velocity
• peak wind velocity
• wind velocity now
• arrival time of shock front
• duration of shock front

EFFECTS ON PROPERTY

Reports severity of damage for:

• 21 different types of buildings and structures
• structural elements
• vehicles
• parked aircraft
• shipping
• trains
• power lines
• storage tanks
• construction equipment
• buried structures
• heavy machinery
• forests

EFFECTS ON PEOPLE

• eardrum rupture
• lung damage
• risk of death from direct blast effect
• risk of injury from being hurled by the blast
• risks from glass fragments:
  • skin laceration
  • abdominal injury
  • serious wounds
• risks from hurled debris:
  • concussion
  • skull fracture
  • other injuries
  • lethality
• protection provided by the structure you're in

Thermal effects

Roughly a third of the energy released by a nuclear weapon is emitted as light, heat, and UV rays in the first minute or so after the explosion. The actual fraction and duration depends on the height of the burst, the weapon yield, and the weapon's composition.

If you are close enough for retinal scarring or flash blindness, and you are looking in the direction of the burst,

There are two thermal pulses. The first is very brief (less than a second) but can cause temporary or permanent blindness, especially if you are looking in the direction of the explosion. The second also affects the eye, causes skin burns, and can start fires.

SCIENTIFIC EFFECTS

• maximum thermal power
• time of thermal maximum
• duration of thermal pulse
• peak radiant exposure
• radiant exposure now

BIOLOGICAL EFFECTS

• flash blindness
• retinal scarring
• first-degree burns
• second-degree burns
• third-degree burns

The severity of burns depends on skin tone; results are reported for light, medium, and dark skin. These are the burns due directly to thermal radiation on exposed skin. There may also be burns due to fires. (Be sure to check the effects on the type of clothing you typically wear.)

PROPERTY DAMAGE

Fires are a major hazard. In this section, Fallout Shelter reports on the effects of the burst's thermal radiation on 60 household and outdoor materials. A fire can also start as an indirect consequence of the damage caused by the high winds and shock wave.

Initial radiation effects

The initial radiation is the neutrons and gamma rays emitted from the fireball and the radioactive cloud within the first minute after the explosion. There are also alpha and beta particles present, but they are absorbed within a few yards of the cloud.

• unprotected gamma-ray dose
• unprotected neutron dose
• unprotected time you're at risk
• gamma-ray dose, given your protective shielding
• neutron dose, given your protective shielding
• time at risk, given your protective shielding

Electromagnetic fields

The electromagnetic effects of a nuclear explosion have the farthest impact of any of the immediate burst consequences. Electrical or electronic equipment can be damaged hundreds of miles away. At the same time, atmospheric ionization will disrupt radar and radio communications. Both effects, of course, will affect whether you can receive a GPS signal after a nuclear attack.

• distance affected by electromagnetic pulse
• duration of radio blackout

Delayed radiation effects (early fallout)

This is also called fallout. It's produced by the ground vaporized or sucked in, so air bursts and high-altitude bursts don't generate fallout. Only about 5% of the energy in a nuclear explosion contributes to fallout. Fallout is the only direct effect of a burst that requires long-term precautions.

Fallout Shelter only reports on early fallout, which is the fallout that reaches the ground during the first day after the nuclear explosion. Delayed fallout — whatever's left — is very fine, invisible particles that will spread worldwide. It is not a factor in defending against a nuclear attack because it's had a day or more to decay in the atmosphere and because it's spread so widely.

There is an open question as to whether a "nuclear winter" would result from a massive attack. But it's certainly not a consequence of a small number of weapons exploding.

By the way, we might as well discuss a misunderstanding — or perhaps misrepresentation — that often appears in public discussion of the hazards of radioactive materials. We often see people speaking about nuclear waste or fallout and saying that it will remain dangerous for tens of thousands to millions of years. The reality is that an object only has so much radioactivity in it. The more radioactive an object is, the more rapidly it decays to something safe. Conversely, the longer it's radioactive, the less dangerous it is.

Anyway, as covered on the previous page, fallout patterns depend on wind speed and direction at different altitudes. Near the ground, the exact terrain shapes the air flow, which means that two spots near each other could have quite different radiation levels. Further complicating matters, rain, flooding, and burst pipes or tanks will carry fallout — dramatically increasing exposure for some and reducing it for others.

• unprotected dose rate at specified time after blast
• unprotected cumulative dose at specified time after blast
• dose rate at specified time after blast, given your protective shielding
• cumulative exposure at specified time after blast, given your protective shielding
• safe time limit unprotected at specified time after blast
• expected immediate health consequences on people
• expected lethality to livestock
• expected long-term health consequences

Attacks

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