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Review 8.2 The Cold War for your test on Unit 8 – Cold War & Decolonization (1900-Present). For students taking AP World History: Modern.
The atomic bomb could kill everyone within about a mile radius. The hydrogen bomb could kill every human being in a 5-10 mile radius. By 1959, the Soviets developed an intercontinental ballistic missile which was capable of delivering a nuclear warhead to the mainland of the United States.
Oct 12, 2024 · A nuclear weapon is a device designed to release energy in an explosive manner as a result of nuclear fission, nuclear fusion, or a combination of the two. Fission weapons are commonly referred to as atomic bombs, and fusion weapons are referred to as thermonuclear bombs or, more commonly, hydrogen bombs.
- Concerns about the devastating effects of nuclear weapons have driven governments to negotiate arms control agreements. Some of the earliest ones i...
- The first test of a nuclear weapon occurred in the United States on July 16, 1945, at the Alamogordo Bombing Range in south-central New Mexico. The...
- The Soviet Union had the most nuclear weapons during the Cold War. The Soviet stockpile reached a peak of about 33,000 operational warheads in 1988...
- Overview
- The properties and effects of atomic bombs
atomic bomb, weapon with great explosive power that results from the sudden release of energy upon the splitting, or fission, of the nuclei of a heavy element such as plutonium or uranium.
When a neutron strikes the nucleus of an atom of the isotopes uranium-235 or plutonium-239, it causes that nucleus to split into two fragments, each of which is a nucleus with about half the protons and neutrons of the original nucleus. In the process of splitting, a great amount of thermal energy, as well as gamma rays and two or more neutrons, is released. Under certain conditions, the escaping neutrons strike and thus fission more of the surrounding uranium nuclei, which then emit more neutrons that split still more nuclei. This series of rapidly multiplying fissions culminates in a chain reaction in which nearly all the fissionable material is consumed, in the process generating the explosion of what is known as an atomic bomb.
Many isotopes of uranium can undergo fission, but uranium-235, which is found naturally at a ratio of about one part per every 139 parts of the isotope uranium-238, undergoes fission more readily and emits more neutrons per fission than other such isotopes. Plutonium-239 has these same qualities. These are the primary fissionable materials used in atomic bombs. A small amount of uranium-235, say 0.45 kg (1 pound), cannot undergo a chain reaction and is thus termed a subcritical mass; this is because, on average, the neutrons released by a fission are likely to leave the assembly without striking another nucleus and causing it to fission. If more uranium-235 is added to the assemblage, the chances that one of the released neutrons will cause another fission are increased, since the escaping neutrons must traverse more uranium nuclei and the chances are greater that one of them will bump into another nucleus and split it. At the point at which one of the neutrons produced by a fission will on average create another fission, critical mass has been achieved, and a chain reaction and thus an atomic explosion will result.
In practice, an assembly of fissionable material must be brought from a subcritical to a critical state extremely suddenly. One way this can be done is to bring two subcritical masses together, at which point their combined mass becomes a critical one. This can be practically achieved by using high explosives to shoot two subcritical slugs of fissionable material together in a hollow tube. A second method used is that of implosion, in which a core of fissionable material is suddenly compressed into a smaller size and thus a greater density; because it is denser, the nuclei are more tightly packed and the chances of an emitted neutron’s striking a nucleus are increased. The core of an implosion-type atomic bomb consists of a sphere or a series of concentric shells of fissionable material surrounded by a jacket of high explosives, which, being simultaneously detonated, implode the fissionable material under enormous pressures into a denser mass that immediately achieves criticality. An important aid in achieving criticality is the use of a tamper; this is a jacket of beryllium oxide or some other substance surrounding the fissionable material and reflecting some of the escaping neutrons back into the fissionable material, where they can thus cause more fissions. In addition, “boosted fission” devices incorporate such fusionable materials as deuterium or tritium into the fission core. The fusionable material boosts the fission explosion by supplying a superabundance of neutrons.
Fission releases an enormous amount of energy relative to the material involved. When completely fissioned, 1 kg (2.2 pounds) of uranium-235 releases the energy equivalently produced by 17,000 tons, or 17 kilotons, of TNT. The detonation of an atomic bomb releases enormous amounts of thermal energy, or heat, achieving temperatures of several million degrees in the exploding bomb itself. This thermal energy creates a large fireball, the heat of which can ignite ground fires that can incinerate an entire small city. Convection currents created by the explosion suck dust and other ground materials up into the fireball, creating the characteristic mushroom-shaped cloud of an atomic explosion. The detonation also immediately produces a strong shock wave that propagates outward from the blast to distances of several miles, gradually losing its force along the way. Such a blast wave can destroy buildings for several miles from the location of the burst.
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- The Editors of Encyclopaedia Britannica
Another difference is the immediate and residual radiation energy from nuclear weapons. This can be adjusted to put more energy into radiation (the so-called neutron bomb) so that the bomb can be used to irradiate advancing troops without killing friendly troops with blast and heat.
Jul 15, 2020 · In the 75 years since the first successful test of a plutonium bomb, nuclear weapons have changed the face of warfare. Here, troops in the 11th Airborne division watch an atomic explosion at...
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Oct 12, 2024 · Nuclear weapon - Gun Assembly, Implosion, Boosting: In order to produce a nuclear explosion, subcritical masses of fissionable material must be rapidly assembled into a supercritical configuration. The simplest weapon design is the pure fission gun-assembly device, in which an explosive propellant is used to fire one subcritical mass down a ...
