The extreme temperature provided by the primary then causes fusion between these hydrogen isotopes, releasing vast quantities of energy. But initial data suggests that this may not be the case. While as yet unconfirmed by the Comprehensive Test Ban Treaty Organisation , the seismic shock of the test registered 5.
However, it is possible North Korea has tested a third weapon type: a boosted fission weapon. Upon detonation of the weapon, the fusion fuel is compressed and heated, undergoing nuclear fusion. While some energy is released by this process, this is relatively small when compared to that released by fission. The major contribution of the fusion reaction is to supply a large number of additional neutrons. These flood the core of the fission weapon, inducing many more fission reactions and significantly increasing the efficiency and so the yield of the weapon.
The result is a very explosive chain reaction. The bombs dropped on Hiroshima and Nagasaki exploded with the yield of 15 kilotons and 20 kilotons of TNT, respectively, according to the Union of Concerned Scientists. In contrast, the first test of a thermonuclear weapon, or hydrogen bomb, in the United States in November yielded an explosion on the order of 10, kilotons of TNT.
Thermonuclear bombs start with the same fission reaction that powers atomic bombs — but the majority of the uranium or plutonium in atomic bombs actually goes unused.
In a thermonuclear bomb, an additional step means that more of the bomb's explosive power becomes available. First, an igniting explosion compresses a sphere of plutonium, the material that will then undergo fission.
Fission can be self-sustaining because it produces more neutrons with the speed required to cause new fissions. This creates the chain reaction.
The very first uranium bomb, Little Boy, dropped on Hiroshima in , used 64 kilograms of 80 percent enriched uranium. In fission weapons, a mass of fissile material, either enriched uranium or plutonium, is assembled into a supercritical mass—the amount of material needed to start an exponentially growing nuclear chain reaction.
The implosion method is considered more sophisticated than the gun method and only can be used if the fissile material is plutonium. The inherent radioactivity of uranium will then release a neutron, which will bombard another atom of U to produce the unstable uranium, which undergoes fission, releases further neutrons, and continues the process. The uranium atom can split any one of dozens of different ways, as long as the atomic weights add up to uranium plus the extra neutron.
The following equation shows one possible split, namely into strontium 95 Sr , xenon Xe , and two neutrons n , plus energy:. The difference comes from how that energy is created. An atomic bomb uses fission, that is, the breaking of an atom's nucleus into smaller particles. This results in the release of neutrons and lots of energy that become an atomic explosion.
In comparison, a hydrogen bomb is about fusion — fusing atomic nuclei together to combine into bigger ones. A hydrogen bomb, or a thermonuclear bomb, contains a fission weapon within it but there is a two-stage reaction process. It uses the energy from a primary nuclear fission to set off a subsequent fusion reaction.
The energy released by fusion is three to four times greater than the energy released by fission, giving the "hydrogen" bomb, or H-bomb, more power. The name comes from the fact that it uses a fusion of tritium and deuterium, hydrogen isotopes. Essentially, an H-bomb is only limited by the amount of hydrogen within it and can be made as powerful as its builder wishes it to be, making it a big threat should a perceived "rogue" state like North Korea develop one.
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