Wednesday, May 25, 2011

History of Nuclear Energy - Laura Wilcox

http://library.thinkquest.org/3471/nuclear_energy_body.html


    Nuclear EnergyNuclear Energy

    The sun and stars are seemingly inexhaustible sources of energy. That energy is the result of nuclear reactions, in which matter is converted to energy. We have been able to harness that mechanism and regularly use it to generate power. Presently, nuclear energy provides for approximately 16% of the world's electricity. Unlike the stars, the nuclear reactors that we have today work on the principle of nuclear fission. Scientists are working like madmen to make fusion reactors which have the potential of providing more energy with fewer disadvantages than fission reactors.

    Production

      Changes can occur in the structure of the nuclei of atoms. These changes are called nuclear reactions. Energy created in a nuclear reaction is called nuclear energy, or atomic energy.
      Nuclear energy is produced naturally and in man-made operations under human control.
      • Naturally: Some nuclear energy is produced naturally. For example, the Sun and other stars make heat and light by nuclear reactions.
      • Man-Made: Nuclear energy can be man-made too. Machines called nuclear reactors, parts of nuclear power plants, provide electricity for many cities. Man-made nuclear reactions also occur in the explosion of atomic and hydrogen bombs.
      Nuclear energy is produced in two different ways, in one, large nuclei are split to release energy. In the other method, small nuclei are combined to release energy.
      For a more detailed look at nuclear fission and nuclear fusion, consult the nuclear physics page.
      • Nuclear Fission: In nuclear fission, the nuclei of atoms are split, causing energy to be released. The atomic bomb and nuclear reactors work by fission. The element uranium is the main fuel used to undergo nuclear fission to produce energy since it has many favorable properties. Uranium nuclei can be easily split by shooting neutrons at them. Also, once a uranium nucleus is split, multiple neutrons are released which are used to split other uranium nuclei. This phenomenon is known as a chain reaction.
    Fission Diagram
    Fission of uranium 235 nucleus. Adapted from Nuclear Energy. Nuclear Waste*.
      • Nuclear Fusion: In nuclear fusion, the nuclei of atoms are joined together, or fused. This happens only under very hot conditions. The Sun, like all other stars, creates heat and light through nuclear fusion. In the Sun, hydrogen nuclei fuse to make helium. The hydrogen bomb, humanity's most powerful and destructive weapon, also works by fusion. The heat required to start the fusion reaction is so great that an atomic bomb is used to provide it. Hydrogen nuclei fuse to form helium and in the process release huge amounts of energy thus producing a huge explosion.

    Milestones in the History of Nuclear Energy

      • December 2, 1942: The Nuclear Age began at the University of Chicago when Enrico Fermi made a chain reaction in a pile of uranium.
      • August 6, 1945: The United States dropped an atomic bomb on Hiroshima, Japan, killing over 100,000.
      • August 9, 1945: The United States dropped an atomic bomb on Nagasaki, Japan, killing over 40,000.
      • November 1, 1952: The first large version of the hydrogen bomb (thousands of times more powerful than the atomic bomb) was exploded by the United States for testing purposes.
      • February 21, 1956: The first major nuclear power plant opened in England.

    Advantages of Nuclear Energy

      • The Earth has limited supplies of coal and oil. Nuclear power plants could still produce electricity after coal and oil become scarce.
      • Nuclear power plants need less fuel than ones which burn fossil fuels. One ton of uranium produces more energy than is produced by several million tons of coal or several million barrels of oil.
      • Coal and oil burning plants pollute the air. Well-operated nuclear power plants do not release contaminants into the environment.

    Disadvantages of Nuclear Energy

      The nations of the world now have more than enough nuclear bombs to kill every person on Earth. The two most powerful nations -- Russia and the United States -- have about 50,000 nuclear weapons between them. What if there were to be a nuclear war? What if terrorists got their hands on nuclear weapons? Or what if nuclear weapons were launched by accident?
      • Nuclear explosions produce radiation. The nuclear radiation harms the cells of the body which can make people sick or even kill them. Illness can strike people years after their exposure to nuclear radiation.
      • One possible type of reactor disaster is known as a meltdown. In such an accident, the fission reaction goes out of control, leading to a nuclear explosion and the emission of great amounts of radiation.
        • In 1979, the cooling system failed at the Three Mile Island nuclear reactor near Harrisburg, Pennsylvania. Radiation leaked, forcing tens of thousands of people to flee. The problem was solved minutes before a total meltdown would have occurred. Fortunately, there were no deaths.
        • In 1986, a much worse disaster struck Russia's Chernobyl nuclear power plant. In this incident, a large amount of radiation escaped from the reactor. Hundreds of thousands of people were exposed to the radiation. Several dozen died within a few days. In the years to come, thousands more may die of cancers induced by the radiation.
      • Nuclear reactors also have waste disposal problems. Reactors produce nuclear waste products which emit dangerous radiation. Because they could kill people who touch them, they cannot be thrown away like ordinary garbage. Currently, many nuclear wastes are stored in special cooling pools at the nuclear reactors.
        • The United States plans to move its nuclear waste to a remote underground dump by the year 2010.
        • In 1957, at a dump site in Russia's Ural Mountains, several hundred miles from Moscow, buried nuclear wastes mysteriously exploded, killing dozens of people.
      • Nuclear reactors only last for about forty to fifty years.

    The Future of Nuclear Energy

      Some people think that nuclear energy is here to stay and we must learn to live with it. Others say that we should get rid of all nuclear weapons and power plants. Both sides have their cases as there are advantages and disadvantages to nuclear energy. Still others have opinions that fall somewhere in between.
      What do you think we should do? After reviewing the pros and cons, it is up to you to formulate your own opinion. Read more about thepolitics of the issues or go to the forum to share your own opinions and see what others think.


No comments:

Post a Comment