Nuclear fallout

Fallout spread throughout Europe, with Northern Scandinavia receiving a heavy dose, contaminating reindeer herds in Lapland, and salad greens becoming almost unavailable in France.

[3] The larger particles spill out of the stem and cascade down the outside of the fireball in a downdraft even as the cloud rises, so fallout begins to arrive near ground zero within an hour.

In case of water surface bursts, the particles tend to be rather lighter and smaller, producing less local fallout but extending over a greater area.

After the Crossroads underwater test, it was found that wet fallout must be immediately removed from ships by continuous water washdown (such as from the fire sprinkler system on the decks).

After the Castle Bravo test, white dust—contaminated calcium oxide particles originating from pulverized and calcined corals—fell for several hours, causing beta burns and radiation exposure to the inhabitants of the nearby atolls and the crew of the Daigo Fukuryū Maru fishing boat.

The base surge is a cloud that rolls outward from the bottom of the subsiding column, which is caused by an excessive density of dust or water droplets in the air.

For underwater bursts, the visible surge is, in effect, a cloud of liquid (usually water) droplets with the property of flowing almost as if it were a homogeneous fluid.

The two alternative versions both ascribe the high radiation levels at north Rongelap to a downwind hot spot caused by the large amount of radioactivity carried on fallout particles of about 50–100 micrometres size.

Under special meteorological conditions, such as a local rain shower that originates above the radioactive cloud, limited areas of heavy contamination just downwind of a nuclear blast may be formed.

For 1 MeV energy gamma rays, an exposure of 1 röntgen in air produces a dose of about 0.01 gray (1 centigray, cGy) in water or surface tissue.

Because of the large amount of short-lived fission products, the activity and radiation levels of nuclear fallout decrease very quickly after being released; it is reduced by 50% in the first hour after a detonation,[17] then by 80% during the first day.

Some of the possible delayed consequences of radiation injury, with the rates above the background prevalence, depending on the absorbed dose, include carcinogenesis, cataract formation, chronic radiodermatitis, decreased fertility, and genetic mutations.

Of all the pregnant women who were close enough to be exposed to the prompt burst of intense neutron and gamma doses in the two cities, the total number of children born with microcephaly was below 50.

[23][24][25] The surviving women of Hiroshima and Nagasaki who could conceive and were exposed to substantial amounts of radiation went on and had children with no higher incidence of abnormalities than the Japanese average.

[31] In an April 2014 article in Popular Science, Sarah Fecht argues that the group's work, specifically the widely discussed case of cherry-picking data to suggest that fallout from the 2011 Fukushima accident caused infant deaths in America, is "junk science", as despite their papers being peer-reviewed, independent attempts to corroborate their results return findings that are not in agreement with what the organization suggests.

[35] The dangers of nuclear fallout do not stop at increased risks of cancer and radiation sickness, but also include the presence of radionuclides in human organs from food.

[38] Mammals particularly are extremely sensitive to nuclear radiation, followed by birds, plants, fish, reptiles, crustaceans, insects, moss, lichen, algae, bacteria, mollusks, and viruses.

[38] Climatologist Alan Robock and atmospheric and oceanic sciences professor Brian Toon created a model of a hypothetical small-scale nuclear war that would have approximately 100 weapons used.

If enough soot was introduced in the upper atmosphere the planet's ozone layer could potentially be depleted, affecting plant growth and human health.

[41] During the Cold War, the governments of the U.S., the USSR, Great Britain, and China attempted to educate their citizens about surviving a nuclear attack by providing procedures on minimizing short-term exposure to fallout.

A practical fallout shield is ten halving-thicknesses of a given material, such as 90 cm (36 inches) of packed earth, which reduces gamma ray exposure by approximately 1024 times (210).

While full body shielding in a secure fallout shelter as described above is the most optimal form of radiation protection, it requires being locked in a very thick bunker for a significant amount of time.

In the event of a nuclear catastrophe of any kind, it is imperative to have mobile protection equipment for medical and security personnel to perform necessary containment, evacuation, and any number of other important public safety objectives.

The mass of the shielding material required to properly protect the entire body from high energy radiation would make functional movement essentially impossible.

This has led scientists to begin researching the idea of partial body protection: a strategy inspired by hematopoietic stem cell transplantation (HSCT).

[49] The Office of Civil Defense conducted four case studies to find the cost of turning four standing schools into fallout shelters and what their capacity would be.

Passed by Congress in 1957, the Price-Anderson Act ensured government assistance above the $60 million covered by private insurance companies in the case of a nuclear reactor accident.

The AEC's regulations against potential nuclear reactor fallout were centered on the ability of the power plant to the Maximum Credible Accident (MCA).

[65] In addition, comparing screening campaigns for children inside the Fukushima prefecture and in the rest of the country revealed no significant difference in the risk of thyroid cancer.

In 1989, the World Association of Nuclear Operators (WANO) was formed to cooperate with the IAEA to ensure the same three pillars of reactor safety across international borders.