What do atomic bombs do

In some cases, the fires ignited by the explosion can coalesce into a firestorm, preventing the escape of survivors. Though difficult to predict accurately, it is expected that thermal effects from a nuclear explosion would be the cause of significant casualties.

Initial radiation. Nuclear detonations release large amounts of neutron and gamma radiation. Relative to other effects, initial radiation is an important cause of casualties only for low-yield explosions less than 10 kilotons. When a nuclear detonation occurs close to the ground surface, soil mixes with the highly radioactive fission products from the weapon. The debris is carried by the wind and falls back to Earth over a period of minutes to hours. By contrast, the radiation dose from fallout is delivered over an extended period, as described in Chapter 5.

Most of the dose from fallout is due to external exposure to gamma radiation from radionuclides deposited on the ground, and this is the only exposure pathway considered by the computer models that the Defense Threat Reduction Agency DTRA and Lawrence Livermore National Laboratory LLNL used to estimate health effects for this study. Below is a discussion of the possible. Radiation has both acute and latent health effects. Acute effects include radiation sickness or death resulting from high doses of radiation greater than 1 sievert [Sv], or rems delivered over a few days.

The principal latent effect is cancer. Estimates of latent cancer fatalities are based largely on results of the long-term follow-up of the survivors of the atomic bombings in Japan. The results of these studies have been interpreted by the International Commission on Radiological Protection ICRP 1 in terms of a lifetime risk coefficient of 0. Thus, there is no consideration of the presumed greater sensitivity to radiation of the very young and the elderly.

Also, there is no consideration of the sensitivity of the fetus. From the experience in Japan, it is known that substantial effects on the fetus can occur, and these effects depend on the age stage of organogenesis of the fetus. The transfer of radio nuclides to the fetus resulting from their intake by the mother is another pathway of concern. Radiation dose coefficients for this pathway have been published by the ICRP. Another long-term health effect that is not considered here is the induction of eye cataracts.

This effect has been noted in the Japanese studies and also in a study of the Chernobyl cleanup workers. Compared to the fatalities from prompt, acute fallout and latent cancer fatalities, the absolute number of effects on the fetus is small and is captured within the bounds of the uncertainty. The number of eye cataracts, based on the experience of the Chernobyl workers, is not small.

The occurrence of eye cataracts in the now aging Japanese population is several tens of percent among those more heavily exposed. Finally, there has been a recently confirmed finding that the Japanese survivors are experiencing a statistically significant increase in the occurrence of a number of noncancer diseases, 6 including hypertension, myocardial infarction, thyroid disease, cataracts, chronic liver disease and cirrhosis, and, in females, uterine myoma.

There has been a negative response in the occurrence of glaucoma. A nominal risk coefficient for the seven categories of disease is about 0.

The largest fraction of the risk is due to thyroid disease. Thermal radiation may make fire a collateral effect of the use of surface burst, airburst, or shallow-penetrating nuclear weapons. The potential for fire damage depends on the nature of the burst and the surroundings. If there is a fireball, fires will be a direct result of the absorption of thermal radiation. Fires can also result as an indirect effect of the destruction caused by a blast wave, which can, for example, upset stoves and furnaces, rupture gas lines, and so on.

A shallow-penetrating nuclear weapon of, say, to kilotons at a 3 to 5 meter depth of burst will generate a substantial fireball that will not fade as fast as the air blast. Detonation of a nuclear weapon in a forested area virtually guarantees fire damage at ranges greater than the range of air-blast damage.

If the burst is in a city environment where buildings are closely spaced, say less than 10 to 15 meters, fires will spread from burning buildings to adjacent ones. In Germany and Japan in World War II, safe separation distance ranged from about 30 to 50 feet for a 50 percent probability of spread , but for modern urban areas this distance could be larger. This type of damage is less likely to occur in suburban areas where buildings are more widely separated.

Once started, fire spread continues until the fire runs out of fuel or until the distance to the next source of fuel is too great.

Thus, fire caused directly by thermal ignitions, fire caused indirectly by disruptive blast waves, and spread of fire are all potential, but uncertain, effects. The area over which casualties would occur as a result of the various weapon effects outlined above depends primarily on the explosive yield of the weapon and the height or depth of the burst.

The areas affected by initial nuclear radiation and fallout also depend on the design of the weapon in particular, the fraction of the yield that is derived from fission reactions , and, in the case of fallout, on weather conditions during and after the explosion notably wind speed and direction, atmospheric stability, precipitation, and so on , terrain, and geology in the area of the explosion.

The following calculations assume that the entire population is static and in the open. As an illustrative example, 7 Figure 6. As discussed in Chapter 5 , both of these weapons would produce a ground shock of about 1 kilobar at a depth of 70 meters.

Figure 6. Under these conditions and assumptions, the 10 kiloton EPW is estimated to result in about , casualties, compared with , casualties for the. Thus, in this example the use of an EPW would reduce casualties by about a factor of eight compared with a surface burst with equal destructive capacity against a buried target.

Fallout is responsible for about 75 percent of the casualties from the 10 kiloton explosion compared with about 60 percent of the casualties from the kiloton explosion.

The hazard to people entering the area after the explosion in these scenarios would be due largely to external gamma radiation from fallout. This hazard decreases rapidly with time: the dose rate after 1 week is 10 times less than the dose rate 1 day after the explosion, and after 2 months it is reduced by an additional factor of Figures 6. Depending on the risk that is judged acceptable by commanders,. For example, a soldier entering the 10 millisieverts per hour 1, millirems per hour contour 1 day after the explosion would accumulate a total dose of about 0.

Army guidance for situations in which troops might receive as much as 0. The estimates shown in Figures 6. The number of civilian casualties that would result from an attack depends on many variables, including the following: the distribution of the population around the point of detonation and the degree of sheltering that they have against blast, thermal, and radiation effects; weapon yield and design; height or depth of burst; and weather conditions during and after the explosion.

As shown below, the estimated number of casualties ranges over four orders of magnitude—from hundreds to over a million—depending on the combination of assumptions used.

To explore in a parametric way the range of possibilities, the committee selected three notional targets:. Target A: an underground command-and-control facility in a densely populated area 3 kilometers from the center of a city with a population of about 3 million;. Target B: an underground chemical warfare facility 60 kilometers from the nearest city and 13 kilometers from a small town; and. Target C: a large, underground nuclear weapons storage facility 20 kilometers from a small town.

In each case, the committee asked DTRA to estimate the mean number of casualties deaths and serious injuries from prompt effects, and acute effects of fallout from external gamma radiation resulting from attacks with earth-penetrating weapons with yields ranging from 1 kiloton to 1 megaton, for populations completely in the open and completely indoors.

The means are averages over annual wind patterns, but they ignore precipitation. DTRA also estimated the mean number of casualties resulting from surface bursts with yields from 25 kilotons to 7. For selected cases, the committee asked the Lawrence Livermore National Laboratory to estimate the number of deaths from prompt effects and fallout, and to quantify the variability in acute and latent deaths from fallout owing to wind patterns.

For Figures 6. Note that for a given yield there is little or no difference between the effects of surface bursts and the EPWs. The curves for Targets B and C are steeper a. The number of casualties is similar for surface bursts of the same yield. Note that for yields of less than kilotons, fallout is responsible for more casualties than are prompt effects. This is particularly true for Targets B and C, for which fallout is the only effect of low-yield explosions that can reach population centers.

It is always useful to compare model predictions against relevant experience. Fortunately, the relevant experience is very limited. In the case of the 15 kiloton device detonated over Hiroshima, an estimated 68, persons died and 76, persons were injured out of a total population of , For the 21 kiloton device detonated over Nagasaki, it is estimated that 38, persons died and 21, persons were injured out of a total population of , The Hiroshima and Nagasaki weapons were detonated at a fallout-free height of about meters and therefore produced no local fallout.

As mentioned, the results shown in Figures 6. Assuming that the entire population remains indoors and is thereby shielded from radiation reduces mean total casualties by a factor of up to 4 for Target A, and by a factor of 2 to 8 for Targets B and C. Not accounted for are post attack movement or evacuation of the population, but it is unlikely that individuals could, by fleeing the area of an attack, reduce their exposure to fallout significantly more than by remaining indoors.

Indeed, some people might greatly increase their exposure to fallout if they were to move through highly contaminated areas, as might occur if a major road out of the city were directly under the path of the cloud. Thus, in a population that has received no warning of an attack, the actual effects of sheltering and evacuation are likely to lie between the two extremes for a population that is assumed to be entirely indoors and one that is assumed to be entirely outdoors.

The use of an EPW instead of a surface-burst weapon generally will result in fewer casualties, because the yield of the EPW can be 15 to 25 times smaller than the yield of a surface-burst weapon for a given level of damage against a hard and deeply buried target HDBT. For Target A, casualties are reduced by a factor of 7 at low yields appropriate for target depths of less than meters and by a factor of 2 at high yields and deeper targets.

For Target B, casualties are reduced by a factor of 10 to 30, and for Target C, by a factor of 15 to 60, depending on the yield and assumptions about shielding.

In general, the reduction factor is larger for targets in rural or remote areas. The DTRA results presented above do not include latent cancer deaths from fallout.

In the case of Target B, however, the inclusion of cancer deaths doubled the total number of fatalities. Including cancer deaths has little effect on the ratios shown in Figure 6.

The results given in Figures 6. Casualties from fallout can be substantially higher or lower, depending on the particular wind conditions during and immediately following the attack. For Target A, estimated fatalities from fallout vary by more than an order of magnitude depending on wind direction, ranging from 90, to , for acute effects and from. For Target B estimated fatalities from fallout vary by more than two orders of magnitude depending on wind direction, from 3, to 1 million for acute fatalities, and ranging from 3, to , for latent fatalities; total fatalities vary by a factor of 50, from about 15, to , Similarly large variations in fatalities are also possible if the target is just outside a major city.

For example, if the detonation is moved 30 kilometers northwest of Target A hereafter referred to as Target A , total fatalities vary from 50, to nearly 2 million, depending on whether the wind blows away from or toward the city center. Note that these estimates do not include the effects of precipitation, which would wash out and concentrate fallout in particular areas which may or may not be populated.

The committee expects that including the effects of precipitation would make the weather-related variability in the estimated number of casualties significantly greater than is suggested by this analysis. Of course, as mentioned frequently, Figure 6. In the case of Target A, for example, the 50 percent confidence interval for deaths due to acute effects of fallout based solely on variability in wind direction is , to ,; that is, there is a 75 percent chance of exceeding , deaths from acute effects of fallout, and a 25 percent chance of more than , deaths.

They exit the Earth's atmosphere, travel thousands of miles to their targets and re-enter the atmosphere to deploy their weapons.

Cruise missiles have shorter ranges and smaller warheads than ballistic missiles, but they are harder to detect and intercept. They can be launched from the air, from mobile launchers on the ground and from naval ships. Designed to target smaller areas, TNWs include short-range missiles, artillery shells, land mines and depth charges. Portable TNWs, such as the Davy Crockett rifle, make it possible for small one- or two-man teams to deliver a nuclear strike. The detonation of a nuclear weapon unleashes tremendous destruction, but the ruins would contain microscopic evidence of where the bombs' materials came from.

The detonation of a nuclear bomb over a target such as a populated city causes immense damage. The degree of damage depends upon the distance from the center of the bomb blast, which is called the hypocenter or ground zero. The closer you are to the hypocenter, the more severe the damage. The damage is caused by several things:. At the hypocenter, everything is immediately vaporized by the high temperature up to million degrees Fahrenheit or million degrees Celsius. Outward from the hypocenter, most casualties are caused by burns from the heat, injuries from the flying debris of buildings collapsed by the shock wave and acute exposure to the high radiation.

Beyond the immediate blast area, casualties are caused from the heat, the radiation and the fires spawned from the heat wave. In the long term, radioactive fallout occurs over a wider area because of prevailing winds. The radioactive fallout particles enter the water supply and are inhaled and ingested by people at a distance from the blast. Scientists have studied survivors of the Hiroshima and Nagasaki bombings to understand the short-term and long-term effects of nuclear explosions on human health.

Radiation and radioactive fallout affect those cells in the body that actively divide hair, intestine, bone marrow, reproductive organs.

Some of the resulting health conditions include:. These conditions often increase the risk of leukemia, cancer , infertility and birth defects. Scientists and physicians are still studying the survivors of the bombs dropped on Japan and expect more results to appear over time.

In the s, scientists assessed the possible effects of nuclear warfare many nuclear bombs exploding in different parts of the world and proposed the theory that a nuclear winter could occur. In the nuclear-winter scenario, the explosion of many bombs would raise great clouds of dust and radioactive material that would travel high into Earth's atmosphere.

These clouds would block out sunlight. The reduced level of sunlight would lower the surface temperature of the planet and reduce photosynthesis by plants and bacteria. The reduction in photosynthesis would disrupt the food chain, causing mass extinction of life including humans.

This scenario is similar to the asteroid hypothesis that has been proposed to explain the extinction of the dinosaurs. Proponents of the nuclear-winter scenario pointed to the clouds of dust and debris that traveled far across the planet after the volcanic eruptions of Mount St. Nuclear weapons have incredible, long-term destructive power that travels far beyond the original target.

This is why the world's governments are trying to control the spread of nuclear-bomb-making technology and materials and reduce the arsenal of nuclear weapons deployed during the Cold War.

It's also why nuclear tests conducted by North Korea and other countries draw such a strong response from the international community. The Hiroshima and Nagasaki bombings may be many decades past, but the horrible images of that fateful August morning burn as clear and bright as ever. Sign up for our Newsletter! Mobile Newsletter banner close.

Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. How Nuclear Bombs Work. Hiroshima Peace Memorial stands as a visible reminder of the day the Japanese city was bombed on Aug.

After that fateful day, the structure was the only thing still standing in the vicinity of the explosion. Atomic Structure and Radioactivity " ". An atom, in the simplest model, consists of a nucleus and orbiting electrons.

Alpha decay: A nucleus ejects two protons and two neutrons bound together, known as an alpha particle. Beta decay: A neutron becomes a proton, an electron and an antineutrino. The ejected electron is a beta particle. Spontaneous fission: A nucleus splits into two pieces. In the process, it can eject neutrons, which can become neutron rays.

The nucleus can also emit a burst of electromagnetic energy known as a gamma ray. Gamma rays are the only type of nuclear radiation that comes from energy instead of fast-moving particles. Nuclear Fission Nuclear bombs involve the forces, strong and weak, that hold the nucleus of an atom together, especially atoms with unstable nuclei. Nuclear Fuel " ". Officials from the Manhattan Project, the code name for the U.

That's Dr. Robert J. Oppenheimer in the white hat. The probability of a U atom capturing a neutron as it passes by is fairly high. In a bomb that is working properly, more than one neutron ejected from each fission causes another fission to occur.

It helps to think of a big circle of marbles as the protons and neutrons of an atom. If you shoot one marble -- a single neutron -- into the middle of the big circle, it will hit one marble, which will hit a few more marbles, and so on until a chain reaction continues. The process of capturing the neutron and splitting happens very quickly, on the order of picoseconds 0.

In order for these properties of U to work, a sample of uranium must be enriched ; that is the amount of U in a sample must be increased beyond naturally occurring levels. This particular resource used the following sources:. Skip to main content. Nuclear Chemistry. Search for:. The Atomic Bomb. Learning Objective Describe the chemical reaction which fuels an atomic bomb.

Key Points Atomic bombs are nuclear weapons that use the energetic output of nuclear fission to produce massive explosions. Only two nuclear weapons have been used in the course of warfare, both by the U. If one of these bombs were ever used, the effect would be catastrophic. The heart of a nuclear explosion reaches a temperature of several million degrees centigrade. Over a wide area the resulting heat flash literally vaporises all human tissue.

People inside buildings or otherwise shielded will be indirectly killed by the blast and heat effects as buildings collapse and all inflammable materials burst into flames.

Those in underground shelters who survive the initial heat flash will die as all the oxygen is sucked out of the atmosphere. Outside the area of total destruction there will be a gradually increasing percentage of immediate survivors. However most of these will suffer from fatal burns, will be blinded, bleeding and suffering massive internal injuries. Survivors will be affected within a matter of days by radioactive fall-out.