Enclosed space designated to protect occupants from radioactive debris from a nuclear explosion
For the 2015 video game, see Fallout Shelter. For the Island Records studio known as The Fallout Shelter, see 22 St Peter's Square. For the Yugoslav hard rock band signed as Atomic Shelter on some of their albums, see Atomsko Sklonište.
A fallout shelter sign in the United States of America, designed in 1961 by United States Army Corps of Engineers director of administrative logistics support function Robert W. BlakeleyIdealized American fallout shelter, around 1957
A fallout shelter is an enclosed space specially designated to protect occupants from radioactive debris or fallout resulting from a nuclear explosion. Many such shelters were constructed as civil defense measures during the Cold War.
During a nuclear explosion, matter vaporized in the resulting fireball is exposed to neutrons from the explosion, absorbs them, and becomes radioactive. When this material condenses in the rain, it forms dust and light sandy materials that resemble ground pumice. The fallout emits alpha and beta particles, as well as gamma rays.
Much of this highly radioactive material falls to Earth, subjecting anything within the line of sight to radiation, becoming a significant hazard. A fallout shelter is designed to allow its occupants to minimize exposure to harmful fallout until radioactivity has decayed to a safer level, over a few weeks or months.
Principle
A fallout shelter is designed to protect its occupants from:
the mechanical and thermal effects of a nuclear explosion (or nuclear accident);[1]
radioactive fallout, allowing them to survive for a period of time deemed sufficient to allow them to escape safely.
History
North America
Fallout shelter water storage can: a 66 liters (17+1⁄2U.S.gal) barrel issued by the U.S. Department of Defense, Office of Civil Defense. 1963
The National Emergency Alarm Repeater (NEAR) program was developed in the United States in 1956 during the Cold War to supplement the existing siren warning systems and radio broadcasts in the event of a nuclear attack. The NEAR civilian alarm device was engineered and tested but the program was not viable and was terminated in 1967.[3]
In the U.S. in September 1961, under the direction of Steuart L. Pittman, the federal government started the Community Fallout Shelter Program.[4][5] A letter from President Kennedy advising the use of fallout shelters appeared in the September 1961 issue of Life magazine.[6] From 1961 to 1963, home fallout shelter sales grew, but eventually[when?] there was a public backlash against the fallout shelter as a consumer product.[7]
In November 1961, in Fortune magazine, an article by Gilbert Burck appeared that outlined the plans of Nelson Rockefeller, Edward Teller, Herman Kahn, and Chet Holifield for an enormous network of concrete-lined underground fallout shelters throughout the United States sufficient to shelter millions of people to serve as a refuge in case of nuclear war.[8]
The United States ended federal funding for the shelters in the 1970s.[9] In 2017, New York City began removing the yellow signs since members of the public are unlikely to find edible food and usable medicine inside those rooms.[10]
Atomitat
The Atomitat was an underground house in Plainview, Texas: it was designed by Jay Swayze and completed in 1962. The house was designed in response to the fear of nuclear war during the Cold War. The house was designed to be an "atomic-habitat" which met the United States Civil Defense specifications.[11] It was the first bunker-house to meet their specifications as a nuclear shelter.[12] Swayze also built an underground house for the 1964 New York World's Fair: it was called the Underground World Home.[13]
Europe
Similar projects have been undertaken in Finland, which requires all buildings with area over 600m2 to have an NBC (nuclear-biological-chemical) shelter, and Norway, which requires all buildings with an area over 1000m2 to have a shelter.[14]
The former Soviet Union and other Eastern Bloc countries often designed their underground mass-transit and subway tunnels to serve as bomb and fallout shelters in the event of an attack. Currently, the deepest subway line in the world is situated in St Petersburg in Russia, with an average depth of 60 meters, while the deepest subway station is Arsenalna in Kyiv, at 105.5 meters.[15]
Germany has protected shelters for 3% of its population, Austria for 30%, Finland for 70%, Sweden for 81%,[16] and Switzerland for 114%.[17]
Another underground facility is Željava Air Base, situated on the border between Bosnia and Herzegovina and Croatia under the Gola Plješevica mountain, near the city of Bihać. It was the largest undergroundairport and military air base in the Socialist Federal Republic of Yugoslavia (SFRY), and one of the largest in Europe. The role of the facility was to establish, integrate and coordinate a nationwide early warning radar network in SFRY akin to NORAD in the US. The complex contained tunnels in total length of 3.5km (2.2mi), and the bunker with four entrances protected by 100-ton pressurized doors, three of which were customized for use by fixed-wing aircraft. capable in housing two full fighter squadrons, one reconnaissance squadron, and associated maintenance facilities. It was designed and built to sustain a direct hit from a 20-kilotonnuclear bomb, equivalent to that dropped on Nagasaki. The underground facility was lined with semicircular concrete shields, arranged every 10km (6.2mi), to cushion the impact of incoming strike. The complex included an underground water source, power generators, crew quarters, and other strategic military facilities. It also housed a mess hall that could feed 1,000 people simultaneously, along with stores of food, fuel and arms sufficient to last 30 days. Fuel was supplied by a 20km (12mi) underground pipe network connected to a military warehouse on Pokoj Hill near Bihać. Nowadays, they are popular for urban exploration.[22][23][24]
Switzerland built an extensive network of fallout shelters, not only through extra hardening of government buildings such as schools, but also through a building regulation requiring nuclear shelters in residential buildings since the 1960s (the first legal basis in this sense dates from 4 October 1963).[25] Later, the law ensured that all residential buildings built after 1978 contained a nuclear shelter able to withstand a blast from a 12-megaton explosion at a distance of 700 metres.[26] The Federal Law on the Protection of the Population and Civil Protection still requires that every inhabitant should have a place in a shelter close to where they live.[17]
The Swiss authorities maintained large communal shelters (such as the Sonnenberg Tunnel until 2006) stocked with over four months of food and fuel.[26] The reference Nuclear War Survival Skills declared that, as of 1986, "Switzerland has the best civil defense system, one that already includes blast shelters for over 85% of all its citizens."[27] As of 2006, there were about 300,000 shelters built in private residences, institutions and hospitals, as well as 5,100 public shelters for a total of 8.6 million places, a level of coverage equal to 114% of the population.[17]
In Switzerland, most residential shelters are no longer stocked with the food and water required for prolonged habitation and a large number have been converted by the owners to other uses (e.g., wine cellars, ski rooms, gyms),[26] but a legal obligation to ensure that the shelters are properly maintained remains in effect.[17]
In the United Kingdom, a network of fallout shelters were built across the country for use by the Royal Observer Corps in its nuclear reporting role.[28] Other shelters were built for the purposes of the ROTOR radar system[29] and the regional seat of government scheme.[30] The Pindar complex in London is intended to provide its inhabitants with fallout protection in the event of nuclear attack,[31] as was the earlier Central Government War Headquarters in Corsham.[32]
Details of shelter construction
Door of a public fallout shelter in Switzerland (2014).Large fire door, sealing a fallout and air raid shelter inside the basement parking garage of a hotel in Germany.
Shielding
A basic fallout shelter consists of shields that reduce gamma ray exposure by a factor of 1000. The required shielding can be accomplished with 10 times the thickness of any quantity of material capable of cutting gamma ray exposure in half. Shields that reduce gamma ray intensity by 50% (1/2) include 1 centimetre (0.4in) of lead, 6cm (2.4in) of concrete, 9cm (3.5in) of packed earth or 150 metres (500ft) of air. When multiple thicknesses are built, the shielding multiplies. Thus, a practical fallout shield is ten halving-thicknesses of packed earth, reducing gamma rays by approximately 1024 times (210).[33]
Usually, an expedient purpose-built fallout shelter is a trench; with a strong roof buried by 1m (3ft) of earth. The two ends of the trench have ramps or entrances at right angles to the trench, so that gamma rays cannot enter (they can travel only in straight lines). To make the overburden waterproof (in case of rain), a plastic sheet may be buried a few inches below the surface and held down with rocks or bricks.[34]
Blast doors are designed to absorb the shock wave of a nuclear blast, bending and then returning to their original shape.[35]
Climate control
Dry earth is a reasonably good thermal insulator, but over several weeks of habitation, a shelter will become dangerously hot.[36] The simplest form of effective fan to cool a shelter is a wide, heavy frame with flaps that swing in the shelter's doorway and can be swung from hinges on the ceiling. The flaps open in one direction and close in the other, pumping air. (This is a Kearny air pump, or KAP, named after the inventor, Cresson Kearny.)
Unfiltered air is safe, since the most dangerous fallout has the consistency of sand or finely ground pumice.[36] Such large particles are not easily ingested into the soft tissues of the body, so extensive filters are not required. Any exposure to fine dust is far less hazardous than exposure to the fallout outside the shelter. Dust fine enough to pass the entrance will probably pass through the shelter.[36] Some shelters, however, incorporate NBC-filters for additional protection.
Locations
Effective public shelters can be the middle floors of some tall buildings or parking structures, or below ground level in most buildings with more than 10 floors. The thickness of the upper floors must form an effective shield, and the windows of the sheltered area must not view fallout-covered ground that is closer than 1.5km (1mi). One of Switzerland's solutions is to use road tunnels passing through the mountains, with some of these shelters being able to protect tens of thousands.[37]
Fallout shelters are not always underground. Above ground buildings with walls and roofs dense enough to afford a meaningful protection factor can be used as a fallout shelter.[38]
Contents
A battery-powered radio may be helpful to get reports of fallout patterns and clearance. However, radio and other electronic equipment may be disabled by electromagnetic pulse. For example, even at the height of the Cold War, EMP protection had been completed for only 125 of the approximately 2,771 radio stations in the United States Emergency Broadcast System. Also, only 110 of 3,000 existing Emergency Operating Centers had been protected against EMP effects.[39] The Emergency Broadcast System has since been supplanted in the United States by the Emergency Alert System.
The reference Nuclear War Survival Skills includes the following supplies in a list of "Minimum Pre-Crisis Preparations": one or more shovels, a pick, a bow-saw with an extra blade, a hammer, and 0.1mm (4 mils) polyethylene film (also any necessary nails, wire, etc.); a homemade shelter-ventilating pump (a KAP); large containers for water; a plastic bottle of sodium hypochlorite bleach; one or two KFMs (Kearny fallout meters) and the knowledge to operate them; at least a 2-week supply of compact, nonperishable food; an efficient portable stove; wooden matches in a waterproof container; essential containers and utensils for storing, transporting, and cooking food; a hose-vented 20 litres (5USgal) can, with heavy plastic bags for liners, for use as a toilet; tampons; insect screen and fly bait; any special medications needed by family members; pure potassium iodide, a 60mL (2USfloz) bottle, and a medicine dropper; a first-aid kit and a tube of antibiotic ointment; long-burning candles (with small wicks) sufficient for at least 14 nights; an oil lamp; a flashlight and extra batteries; and a transistor radio with extra batteries and a metal box to protect it from electromagnetic pulse.[40]
Inhabitants should have water on hand, 4–8 litres (1–2USgal) per person per day. Water stored in bulk containers requires less space than water stored in smaller bottles.[41]
Kearny fallout meter
Commercially made Geiger counters are expensive and require frequent calibration. It is possible to construct an electrometer-type radiation meter called the Kearny fallout meter, which does not require batteries or professional calibration, from properly-scaled plans with just a coffee can or pail, gypsum board, monofilament fishing line, and aluminum foil.[42] Plans are freely available in the public domain in the reference Nuclear War Survival Skills by Cresson Kearny.[43]
Use
Inhabitants should plan to remain sheltered for at least two weeks (with an hour out at the end of the first week– see Swiss Civil Defense guidelines), then work outside for gradually increasing amounts of time, to four hours a day at three weeks. The normal work is to sweep or wash fallout into shallow trenches to decontaminate the area. They should sleep in a shelter for several months. Evacuation at three weeks is recommended by official authorities.[citation needed]
If available, inhabitants may take potassium iodide at the rate of 130mg/day per adult (65mg/day per child) as an additional measure to protect the thyroid gland from the uptake of dangerous radioactive iodine, a component of most fallout and reactor waste.[44]
Relative abilities of three different types of ionizing radiation to penetrate solid matter.
The protection factor provided by 10cm of concrete shielding where the source is the idealised Chernobyl fallout.
The protection factor provided by 20cm of concrete shielding where the source is the idealised Chernobyl fallout.
The protection factor provided by 30cm of concrete shielding where the source is the idealised Chernobyl fallout.
Calculated relative gamma dose rates from atomic bomb and Chernobyl fallout
Different types of radiation emitted by fallout
Alpha (α)
In the vast majority of accidents, and in all atomic bomb blasts, the threat due to beta and gamma emitters is greater than that posed by the alpha emitters in the fallout. Alpha particles are identical to a helium-4 nucleus (two protons and two neutrons), and travel at speeds in excess of 5% of the speed of light. Alpha particles have little penetrating power; most cannot penetrate through human skin. Avoiding direct exposure with fallout particles will prevent injury from alpha radiation.[46]
Beta (β)
Beta radiation consists of particles (high-speed electrons) given off by some fallout. Most beta particles cannot penetrate more than about 3 metres (10ft) of air or about 3mm (1⁄8in) of water, wood, or human body tissue; or a sheet of aluminum foil. Avoiding direct exposure with fallout particles will prevent most injuries from beta radiation.[47]
The primary dangers associated with beta radiation are internal exposure from ingested fallout particles and beta burns from fallout particles no more than a few days old. Beta burns can result from contact with highly radioactive particles on bare skin; ordinary clothing separating fresh fallout particles from the skin can provide significant shielding.[47]
Gamma (γ)
Gamma radiation penetrates further through matter than alpha or beta radiation. Most of the design of a typical fallout shelter is intended to protect against gamma rays. Gamma rays are better absorbed by materials with high atomic numbers and high density, although neither effect is important compared to the total mass per area in the path of the gamma ray. Thus, lead is only modestly better as a gamma shield than an equal mass of another shielding material such as aluminum, concrete, water or soil.
Some gamma radiation from fallout will penetrate into even the best shelters. However, the radiation dose received while inside a shelter can be significantly reduced with proper shielding. Ten halving thicknesses of a given material can reduce gamma exposure to less than 1⁄1000 of unshielded exposure.[48]
Weapons versus nuclear accident fallout
The bulk of the radioactivity in nuclear accident fallout is more long-lived than that in weapons fallout. A good table of the nuclides, such as that provided by the Korean Atomic Energy Research Institute, includes the fission yields of the different nuclides. From this data it is possible to calculate the isotopic mixture in the fallout (due to fission products in bomb fallout).[citation needed]
Other matters and simple improvements
While a person's home may not be a purpose-made shelter, it could be thought of as one if measures are taken to improve the degree of fallout protection.
Measures to lower the beta dose
The main threat of beta radiation exposure comes from hot particles in contact with or close to the skin of a person. Also, swallowed or inhaled hot particles could cause beta burns. As it is important to avoid bringing hot particles into the shelter, one option is to remove one's outer clothing, or follow other decontamination procedures, on entry. Fallout particles will cease to be radioactive enough to cause beta burns within a few days following a nuclear explosion. The danger of gamma radiation will persist for far longer than the threat of beta burns in areas with heavy fallout exposure.[49]
Measures to lower the gamma dose rate
The gamma dose rate due to the contamination brought into the shelter on the clothing of a person is likely to be small (by wartime standards) compared to gamma radiation that penetrates through the walls of the shelter.[49] The following measures can be taken to reduce the amount of gamma radiation entering the shelter:
Roofs and gutters can be cleaned to lower the dose rate in the house.
The top inch of soil in the area near the house can be either removed or dug up and mixed with the subsoil. This reduces the dose rate as the gamma rays have to pass through the topsoil before they can irradiate anything above.
Nearby roads can be rinsed and washed down to remove dust and debris; the fallout would collect in the sewers and gutters for easier disposal. In Kyiv after the Chernobyl accident a program of road washing was used to control the spread of radioactivity.
Windows can be bricked up, or the sill raised to reduce the hole in the shielding formed by the wall.
Gaps in the shielding can be blocked using containers of water. While water has a much lower density than that of lead, it is still able to shield some gamma rays.
Earth (or other dense material) can be heaped up against the exposed walls of the building; this forces the gamma rays to pass through a thicker layer of shielding before entering the house.
Nearby trees can be removed to reduce the dose due to fallout which is on the branches and leaves. It has been suggested by the US government that a fallout shelter should not be dug close to trees for this reason.[50]
Fallout shelters in popular culture
The international distinctive sign of civil defense personnel and infrastructures.
In the Only Fools and Horses episode "The Russians are Coming", aired in 1981, Derek Trotter buys a lead fallout shelter, then decides to construct it in fear of an impending nuclear war caused by the Soviet Union.
In 1999, the film Blast from the Past was released. It is a romantic comedy film about a nuclear physicist, his wife, and son that enter a well-equipped, spacious fallout shelter during the 1962 Cuban Missile Crisis. They do not emerge until 35 years later, in 1997. The film shows their reaction to contemporary society.
The Fallout series of computer games depicts the remains of human civilization after an immensely destructive global nuclear war; the United States of America had built underground fallout shelters known as vaults, that were advertised to protect the population against a nuclear attack, but almost all of them were in fact meant to lure subjects for long-term human experimentation.
Paranoia, a role-playing game, takes place in a city-sized fallout shelter, which has become ruled by an insane computer.
An episode of the sitcom Malcolm in the Middle features a subplot revolving around Reese and Dewey discovering a previously unknown fallout shelter in their backyard and trapping their father Hal in it, who soon becomes smitten with the shelter's 1960s decor.
The Metro 2033 book series by Russian author Dmitry Glukhovsky depicts survivors' life in the subway systems below Moscow and Saint-Petersburg after a nuclear exchange between the Russian Federation and the United States of America.
Fallout shelters are often featured on the reality television show Doomsday Preppers.[52]
The Silo series of novellas by Hugh Howey feature extensive fallout-style shelters that protect the inhabitants from an initially unknown disaster.
The 2019 US film The Tomorrow Man centers around a reclusive man whose main preoccupation is tending to his in-home fallout shelter and the conspiracy theories that could put it to use.
↑ Morris, Alec (1996). "UK Control & Reporting System from the End of WWII to ROTOR and Beyond". In Hunter, Sandy (ed.). Defending Northern Skies. Royal Air Force Historical Society. p.104.
↑ Grant, Matthew (2010). After the Bomb: Civil Defence and Nuclear War in Britain, 1945–68. London: Palgrave Macmillan. ISBN978-0-230-20542-0.
↑ "T 640/384"(PDF). Archived(PDF) from the original on April 7, 2024. Retrieved April 7, 2024.
↑ Kearny, Cresson H (1986). Nuclear War Survival Skills. Oak Ridge, TN: Oak Ridge National Laboratory. pp.37–45. ISBN0-942487-01-X. The 3-foot thickness of earth shown (or a 2-foot thickness of concrete) will provide an effective barrier, attenuating (absorbing) about 99.9%, of all gamma rays from fallout." "A right-angle turn, either from a vertical or horizontal entry, causes a reduction of about 90%." "...a large piece of 4-mil-thick polyethylene was placed over the mound. This waterproof material served as a "buried roof" after it was covered with more earth.
↑ "Secret U.S. Bunkers". Lost Worlds. Episode 18. August 29, 2007. The History Channel.
Background radiation is a measure of the level of ionizing radiation present in the environment at a particular location which is not due to deliberate introduction of radiation sources.
A beta particle, also called beta ray or beta radiation, is a high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic nucleus, known as beta decay. There are two forms of beta decay, β− decay and β+ decay, which produce electrons and positrons, respectively.
Nuclear fallout is residual radioactive material propelled into the upper atmosphere following a nuclear blast, so called because it "falls out" of the sky after the explosion and the shock wave has passed. It commonly refers to the radioactive dust and ash created when a nuclear weapon explodes. The amount and spread of fallout is a product of the size of the weapon and the altitude at which it is detonated. Fallout may get entrained with the products of a pyrocumulus cloud and when combined with precipitation falls as black rain, which occurred within 30–40 minutes of the atomic bombings of Hiroshima and Nagasaki. This radioactive dust, usually consisting of fission products mixed with bystanding atoms that are neutron-activated by exposure, is a form of radioactive contamination.
A bunker is a defensive military fortification designed to protect people and valued materials from falling bombs, artillery, or other attacks. Bunkers are almost always underground, in contrast to blockhouses which are mostly above ground. They were used extensively in World War I, World War II, and the Cold War for weapons facilities, command and control centers, and storage facilities. Bunkers can also be used as protection from tornadoes.
Acute radiation syndrome (ARS), also known as radiation sickness or radiation poisoning, is a collection of health effects that are caused by being exposed to high amounts of ionizing radiation in a short period of time. Symptoms can start within an hour of exposure, and can last for several months. Early symptoms are usually nausea, vomiting and loss of appetite. In the following hours or weeks, initial symptoms may appear to improve, before the development of additional symptoms, after which either recovery or death follow.
Ionizing radiation, including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel up to 99% of the speed of light, and the electromagnetic waves are on the high-energy portion of the electromagnetic spectrum.
Radiation protection, also known as radiological protection, is defined by the International Atomic Energy Agency (IAEA) as "The protection of people from harmful effects of exposure to ionizing radiation, and the means for achieving this". Exposure can be from a source of radiation external to the human body or due to internal irradiation caused by the ingestion of radioactive contamination.
Radioactive contamination, also called radiological pollution, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids, or gases, where their presence is unintended or undesirable.
"Duck and cover" is a method of personal protection against the effects of a nuclear explosion. Ducking and covering is useful in offering a degree of protection to personnel located outside the radius of the nuclear fireball but still within sufficient range of the nuclear explosion that standing upright and uncovered is likely to cause serious injury or death. In the most literal interpretation, the focus of the maneuver is primarily on protective actions one can take during the first few crucial seconds-to-minutes after the event, while the film of the same name and a full encompassing of the advice also cater to providing protection up to weeks after the event.
Neutron activation is the process in which neutron radiation induces radioactivity in materials, and occurs when atomic nuclei capture free neutrons, becoming heavier and entering excited states. The excited nucleus decays immediately by emitting gamma rays, or particles such as beta particles, alpha particles, fission products, and neutrons. Thus, the process of neutron capture, even after any intermediate decay, often results in the formation of an unstable activation product. Such radioactive nuclei can exhibit half-lives ranging from small fractions of a second to many years.
A blast shelter is a place where people can go to protect themselves from blasts and explosions, like those from bombs, or in hazardous worksites, such as on oil and gas refineries or petrochemical facilities. It differs from a fallout shelter, in that its main purpose is to protect from shock waves and overpressure instead of from radioactive precipitation, as a fallout shelter does. It is also possible for a shelter to protect from both blasts and fallout.
Geiger counter is a colloquial name for any hand-held radiation measuring device in civil defense, but most civil defense devices were ion-chamber radiological survey meters capable of measuring only high levels of radiation that would be present after a major nuclear event.
A radiation burn is a damage to the skin or other biological tissue and organs as an effect of radiation. The radiation types of greatest concern are thermal radiation, radio frequency energy, ultraviolet light and ionizing radiation.
Lead shielding refers to the use of lead as a form of radiation protection to shield people or objects from radiation so as to reduce the effective dose. Lead can effectively attenuate certain kinds of radiation because of its high density and high atomic number; principally, it is effective at stopping gamma rays and x-rays.
Cresson Henry Kearny wrote several survival-related books based primarily on research performed at Oak Ridge National Laboratory.
The Kearny fallout meter, or KFM, is an expedient radiation meter. It is designed such that someone with a normal mechanical ability would be able to construct it before or during a nuclear attack, using common household items.
The Kearny air pump is an expedient air pump used to ventilate a shelter. The design is such that a person with normal mechanical skills can construct and operate one. It is usually human-powered and designed to be employed during a time of crisis. It was designed to be used in a fallout shelter, but can be used in any situation where emergency ventilation is needed, as after a hurricane.
Nuclear War Survival Skills or NWSS, by Cresson Kearny, is a civil defense manual. It contains information gleaned from research performed at Oak Ridge National Laboratory during the Cold War, as well as from Kearny's extensive jungle living and international travels.
A gamma ray, also known as gamma radiation (symbol γ ), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically shorter than those of X-rays. With frequencies above 30 exahertz (3×1019 Hz) and wavelengths less than 10 picometers (1×10−11 m), gamma ray photons have the highest photon energy of any form of electromagnetic radiation. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation gamma rays based on their relatively strong penetration of matter; in 1900, he had already named two less penetrating types of decay radiation (discovered by Henri Becquerel) alpha rays and beta rays in ascending order of penetrating power.
The medical effects of the atomic bomb upon humans can be put into the four categories below, with the effects of larger thermonuclear weapons producing blast and thermal effects so large that there would be a negligible number of survivors close enough to the center of the blast who would experience prompt/acute radiation effects, which were observed after the 16 kiloton yield Hiroshima bomb, due to its relatively low yield:
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