Although no other country has used such a weapon of mass destruction since World War II, experts say it would be even more catastrophic if a hydrogen bomb were to be dropped instead of an atomic one. Simply speaking, experts say a hydrogen bomb is the more advanced version of an atomic bomb.
An atomic bomb uses either uranium or plutonium and relies on fission, a nuclear reaction in which a nucleus or an atom breaks apart into two pieces. To make a hydrogen bomb, one would still need uranium or plutonium as well as two other isotopes of hydrogen, called deuterium and tritium. The hydrogen bomb relies on fusion, the process of taking two separate atoms and putting them together to form a third atom.
In both cases, a significant amount of energy is released, which drives the explosion, experts say. However, more energy is released during the fusion process, which causes a bigger blast. Morse said the atomic bombs dropped on Japan were each equivalent to just about 10, kilotons of TNT. Its destructive power was several megatons of TNT. The blast produced a light brighter than a thousand suns and a heatwave felt 50 kilometres away.
The Soviet Union detonated a hydrogen bomb in the megaton range in August The US exploded a 15 megaton hydrogen bomb on 1st March, It had a fireball of 4. 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. In comparison, during the period of February to August , the US bombing of Japanese cities — notably Tokyo, Nagoya, Osaka and Kobe — by Bs delivered about kilotons of high explosives and incendiaries to urban areas in hundreds of raids, resulting in a large number of deaths and causing widespread destruction.
Some 80, to , people were killed in a single bomber raid on Tokyo. About 80 square kilometers of those four cities was destroyed in ten days during March. Overall 67 Japanese cities were partly destroyed, , people were killed and 5 million more made homeless.
To the , deaths from the blast or acute radiation exposure at Hiroshima and Nagasaki have since been added those due to radiation induced cancers and leukaemia, which amounted to some within 30 years, and which may ultimately reach about Some 93, exposed survivors were still being monitored 50 years later. There was an increase in leukaemia beginning about two years later and peaking at four to six years later, and other cancers beginning about ten years later.
There was no evident to suggest an increase in leukaemia at less than mSv acute dose. At an acute dose of mSv, an increased cancer risk of 1. There was concern about ingestion or inhalation of radionuclides, but fires released far higher levels of non-radioactive carcinogens.
Additionally, no genetic damage has been detected in survivors' children, despite careful and continuing investigation by a joint Japanese-US foundation. The major source of exposure in both cities was from the penetrating gamma radiations, and to a lesser extent from the neutrons mostly at Hiroshima , emitted during and shortly after fission.
There were two further, and smaller, sources of exposure. One, already mentioned, was due to the 'black rain' which fell in some areas, carrying down radioactive materials from within the rising cloud of fission products.
The exposures due to these depositions are in general estimated to have been small, but some increased activity from the fission product radionuclide caesium remained detectable for many years in soil and farm products in the Nishiyama district east of Nagasaki. The second additional form of exposure resulted from the effect of neutrons in inducing radioactivity in various stable chemical elements such as in iron or concrete structures or roofing tiles.
The total absorbed doses of radiation from these activation products are estimated to be less than one per cent of that from the neutrons which induced them. They could however have caused a significant exposure of people who entered the city within a few days of the explosions. The atmospheric testing of some nuclear weapons up to caused people to be exposed to radiation in a quite different way. The Japanese atomic bombs had caused lethal exposures locally from radiation at the time of the explosions, but very little radiation more than a few kilometres away.
On the other hand, subsequent atmospheric tests did not cause any substantial direct exposures of people at the time of the tests. However, the fission products released into the atmosphere caused the whole world population to be exposed to very low but continuing annual doses from fallout. In at least two instances these fission products also caused substantial irradiation to small populations exposed to local fallout close to the site of testing.
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 immediate energy release per atom is about million electron volts Me. Of the energy produced, 93 percent is the kinetic energy of the charged fission fragments flying away from each other, mutually repelled by the positive charge of their protons.
This initial kinetic energy imparts an initial speed of about 12, kilometers per second. Here, their motion is converted into X-ray heat, a process which takes about a millionth of a second.
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