Surely you've read history books informing the nuclear bombs used in World War II. And also must have seen science fiction movies where nuclear bombs were dropped or detonated ("Fail Safe," "Dr. Strangelove," "The Next Day", "The Testament," "Shadows in the Future" and "The Peacemaker , "just to name a few). In the news, while many countries have negotiated disarmament of their nuclear weapons arsenals, others have sought to develop nuclear weapons programs.
It is known that these devices have an immense destructive power, but how do they work? In this article, we will discuss the physics that makes the nuclear bomb so powerful, as it is designed and what happens after the explosion.
Nuclear bombs utilizes the forces, strong and weak, that hold the nucleus of the atom together, especially atoms with unstable nuclei (see How Nuclear Radiation Works for details). There are two basic modes of nuclear energy to be released from an atom:
In both processes, fusion or fission, a large amount of heat energy and radiation is emitted.
To build an atomic bomb is accurate:
Danger in Iran
Iran informed the UN nuclear agency that is building a second uranium enrichment plant, which should exacerbate Western fears that the country wishes to develop a nuclear bomb.
Early pumps used for nuclear fission device, and the latest melt pumps require activation by fission pump. The following types of projects will be addressed devices:
The fission bomb using an element such as uranium-235 to cause a nuclear explosion. If you have read How Nuclear Radiation Works , then you know what the underlying degeneration and the radioactive fission basic process. Uranium-235 has an extra property that enables both nuclear power generation and for the generation of a nuclear bomb. The U-235 is one of the few materials that support the induced fission . If a free neutron step inside a nucleus of U-235, it will be absorbed immediately, making the nucleus unstable and causing it to crack.
The figure at right shows the nucleus of the element uranium-235 with close proximity to a neutron. As soon as the nucleus captures the neutron, it will be cracked into two smaller atoms and expel two or three new neutrons (the number of ejected neutrons depends on how the U-235 atom was cracked). The two new atoms emit one gamma radiation as they adjust to their new states (see How Nuclear Radiation Works ). There are three aspects of the fission process that make it interesting:
The difference in weight is converted to energy at a rate governed by the equation e = mc 2 . In the case of 450 g (1 lb) of highly enriched uranium, as used in a nuclear bomb, will be equal to 1 million gallons or 3,785,412 liters of gasoline. When considering that 450 g of uranium occupy less volume than a baseball and that one million gallons of gasoline fill a cube edge of 15.24 meters (15.24 meters is the height of a five-story building), can If have an idea of the amount of energy available in just a little U-235.
To enable these properties of U-235, a sample of uranium must be enriched. Uranium for use in weapons is composed of at least 90% U-235.
of a pump fission, the fuel must be separated masses subcritical , that do not support fission, to prevent premature detonation. Critical mass is the minimum fissurável material required to ensure support for a nuclear fission reaction. This separation makes possible the occurrence of several problems in the fission bomb, which project should be solved:
To join the subcritical masses with supercritical mass, two techniques are used:
neutron generator . This generator is a small sphere of polonium-beryllium, separated by a blade inside the fuel fissurável. This generator:
Finally, the fission reaction is confined within a dense material, known as reflector nuclear reactor , which is usually composed of uranium-238. The reflector nuclear reactor heats up and expands through the central zone of fission. This expansion exerts a pressure back reflector and decelerates the expansion of the central zone. The nuclear reactor reflector will also reflect neutrons back into the central area of fission, increasing the efficiency of the reaction.