Nuclear fission atomic bomb

Since weapons based on nuclear fission ( atomic bombs ) are in principle fast homogeneous reactors, the following section is dedicated to the principle of nuclear weapons. 

Arranging for the imcontrolled, large-scale release of energy produced during nuclear fission is a relatively simple tadc. Fission (atomic) bombs are essentially devices in which a chain reaction is initiated and then allowed to continue c i its own. The problems of designing a stem by which fission energy is released at a constant and useable rate, however, are much more difficult... 

Plutonium is also used as a fuel in nuclear power plants and in making nuclear weapons (atomic bombs). The isotope used for this purpose is plutonium-239. It is used because it will undergo nuclear fission. Very few isotopes will undergo nuclear fission. Two isotopes of uranium, uranium-233 and uranium-235, are among these. But uranium-233 does not occur at all in nature and uranium-235 occurs in only very small amounts. 

The step from nuclear fission to a nuclear chain reaction and the atomic bomb was, in principle, quite straightfoiward. In practice, however, it consumed more time and money than was ever foreseen. Although it was her basic insight that eventually led to the fission bomb dropped on Hiroshima, Meitner refused to work on the bomb and, for humanitarian reasons, hoped that it would not work. 

The process of nuclear fission was discovered more than half a century ago in 1938 by Lise Meitner (1878-1968) and Otto Hahn (1879-1968) in Germany. With the outbreak of World War II a year later, interest focused on the enormous amount of energy released in the process. At Los Alamos, in the mountains of New Mexico, a group of scientists led by J. Robert Oppenheimer (1904-1967) worked feverishly to produce the fission, or atomic, bomb. Many of the members of this group were exiles from Nazi Germany. They were spurred on by the fear that Hitler would obtain the bomb first Their work led to the explosion of the first atomic bomb in the New Mexico desert at 5 30 a.m. on July 16,1945. Less than a month later (August 6,1945), the world learned of this new weapon when another bomb was exploded... 

A nuclear fission explosion. Such a dramatic and destructive release of energy had never been seen before the development of the "atomic bomb" during World War II. 

The potential of nuclear fission was first realized in the atomic bomb. In 1945, the United States dropped two bombs of unprecedented power, one on Hiroshima and the other on Nagasaki, Japan. Both were fission weapons. 

Understanding fusion invites another question If fusing nuclei releases energy, how did the early atomic bombs work In those bombs, nuclei were not fused, they were broken apart by nuclear fission. So, where does the energy of atomic bombs come from An important piece of the answer came from a brilliant Jewish scientist who fled Nazi Germany shortly before World War II. 

Shortly after Japan s December 7,1941 attack on Pearl Harbor, the U.S. became more driven to expedite its timetable for developing the first fission weapon because of fear that the U.S. lagged behind Nazi Germany in efforts to create the first atomic bomb. On December 2, 1942 at 3 49 p.m., Enrico Fermi and Samuel K. Allison achieved the world s first controlled, self-sustained nuclear chain reaction in an experimental reactor using natural uranium and graphite. 

A heavy nucleus can split into lighter nuclei by undergoing nuclear fission. Nuclear power plants use controlled nuclear fission to provide energy. Uncontrolled nuclear fission is responsible for the massive destructiveness of an atomic bomb. 

Because the isotope uranium-235 is fissionable, meaning that it produces free neutrons that cause other atoms to split, it generates enough free neutrons to make it unstable. When the unstable U-235 reaches a critical mass of a few pounds, it produces a self-sustaining fission chain reaction that results in a rapid explosion with tremendous energy and becomes a nuclear (atomic) bomb. The first nuclear bombs were made of uranium and plutonium. Today, both of these fuels are used in reactors to produce electrical power. Moderators (control rods) in nuclear power reactors absorb some of the neutrons, which prevents the mass... 

One day as the Italian physicist Enrico Fermi and George Uhlenbeck (who had come to the United States on a visit) were looking out a window overlooking Manhattan, Fermi remarked, You realize, George, that one small fission bomb could destroy most of what we see outside Fermi was soon to be doing some of the preliminary experimental work that preceded the American atomic bomb project. It was Fermi who produced the first controlled nuclear chain reaction. 

Niels Bohr was a physicist, not a chemist. I devote a chapter to his life because he was the scientist who explained why Mendeleev s periodic table had the properties it did. Widely known as a soccer player in his youth, Bohr became the most influential physicist of the first half of the twentieth century. His life, too, was touched by political events. A Jew living in occupied Denmark, Bohr had to flee the country to avoid arrest by the Nazis. In 1939 Bohr discovered a theory that explained nuclear fission, and suggested that uranium 235 could be used to make a bomb. Though he played only a minor role in the American atomic bomb project, Bohr was the first to ponder the political implications of the bomb. 

Modern nuclear power is based on harnessing the energy released in a fission reaction. The development of atomic energy started in the 1930s with the discovery that atoms could be split with neutrons. This discovery laid the foundation for building the first atomic bombs during World War 11. A basic reaction representing the fission of uranium can be represented as ... 

J Ju elements in the periodic table exist in unstable versions called radioisotopes (see Chapter 3 for details). These radioisotopes decay into other (usually more stable) elements in a process called radioactive decay. Because the stability of these radioisotopes depends on the composition of their nuclei, radioactivity is considered a form of nuclear chemistry. Unsurprisingly, nuclear chemistry deals with nuclei and nuclear processes. Nuclear fusion, which fuels the sun, and nuclear fission, which fuels a nuclear bomb, are examples of nuclear chemistry because they deal with the joining or splitting of atomic nuclei. In this chapter, you find out about nuclear decay, rates of decay called half-lives, and the processes of fusion and fission. 

Nuclear flssion Nuclear fission, the splitting of an atomic nucleus, doesn t occur in nature. Humans first harnessed the tremendous power of fission during the Manhattan Project, an intense, hush-hush effort by the United States that led to the development of the first atomic bomb in 1945. Fission has since been used for more-benign purposes in nuclear power plants. Nuclear power plants use a highly regulated process of fission to produce energy much more efficiently than is done in traditional, fossil fuel-burning power plants. 

Another example of a nuclear fission explosion is the explosion of an atomic bomb. Nuclear fission explosions may also take place in a nuclear reactor if a breakdown occurs and a critical mass is achieved. 

Fission weapons or bombs They derive their power from nuclear fission when heavy nuclei such as uranium (U) or plutonium (Pu) are bombarded by neutrons and split into lighter elements, more neutrons and energy. The newly generated neutrons then bombard other nuclei which then split and bombard other nuclei and so on. This process continues and leads to a nuclear chain reaction which releases large amount of energy. These are also historically called atomic bombs or atom bombs or A-bombs. 

Is it possible for a nuclear fission power plant to blow up like an atomic bomb ... 

If in the explosion of one atom bomb 50.0 g of 299Pu were scattered about in the atmosphere before it had a chance to undergo nuclear fission, how much... 

Atomic (or Nuclear) Bomb. A weapon invented during WWII and developed in the United States as a joint effort with the British and Canadian governments. It utilizes for its destructive effect the energy of an Atomic or Nuclear Explosion (qv). Since atomic explosions are of two types, fission and fusion, atomic bombs are of. corresponding types. However, it has been necessary to first initiate an atomic explosion with a nuclear fission reaction in order to bring about the conditions under which a nuclear fusion(thermonuclear) reaction can occur. 

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