Jupitersterrain 5

        In 1957, at a dump site in Russia's Ural Mountains severa hundred miles from Moscow, buried nuclear wastes mysteriously exploded, killing dozens of people

        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 than fission reactors

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 for example, the Sun and other stars make heat and light by nuclear reactions

Man-Made 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 when nuclei are split to release energy 

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


 
        Nuclear Fusion: The nuclei of atoms are 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

Nuclear reactors only last for about forty to fifty years.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 

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

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Nuclear power generates a number of radioactive by-products, including tritium, cesium, krypton, neptunium and forms of iodine.

Caesium or cesium^{[note 1]} ( /ˈsiːziəm/ see-zee-əm) is a chemical element with symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28 °C (82 °F), which makes it one of only five elemental metals that are liquid at (or near) room temperature. Caesium is an alkali metal and has physical and chemical properties similar to those of rubidium and potassium. The metal is extremely reactive and pyrophoric, reacting with water even at −116 °C (−177 °F). It is the least electronegative element having a stable isotope, caesium-133. Caesium is mined mostly from pollucite, while the radioisotopes, especiallycaesium-137, a fission product, are extracted from waste produced by nuclear reactors

Tritium illumination is the use of gaseous tritium, a radioactive isotope of hydrogen, to create visible light. Tritium emits electrons, and when they interact with a phosphor material,fluorescent light is created, a process called radioluminescence. As tritium illumination requires no electrical energy, it found wide use in applications such as emergency exit signs and illumination of wristwatches. More recently, many applications using radioactive materials have been replaced with photoluminescent materials.

Krypton, like the other noble gases, can be used in lighting and photography. Krypton ( /ˈkrɪptɒn/ krip-ton; from Greek: κρυπτός kryptos "the hidden one") is a chemical element with symbol Kr and atomic number 36. It is a member of group 18 (noble gases) elements. A colorless, odorless, tasteless noble gas, krypton occurs in trace amounts in the atmosphere, is isolated by fractionally distilling liquified air, and is often used with other rare gases in fluorescent lamps. Krypton is inert for most practical purposes.

Neptunium ( /nɛpˈtjuːniəm/ nep-tew-nee-əm) is a chemical element with the symbol Np and atomic number 93. A radioactive metal, neptunium is the first transuranic element, and belongs to the actinide series. Its most stable isotope, ²³⁷Np, is a by-product of nuclear reactors and plutonium production, and it can be used as a component in neutron detection equipment. Neptunium is also found in trace amounts in uranium ores due to transmutation reactions.

http://www.epa.gov/cleanenergy/energy-and-you/affect/nuclear.html & Wiki 

Archimedes screw. In some designs, the screw is fixed to the casing and they rotate together instead of the screw turning within a stationary casing. A screw could be sealed with pitch resin or some other adhesive to its casing, or cast as a single piece in bronze. Some researchers have postulated this as being the device used to irrigate the Hanging Gardens of Babylon, one of the Seven Wonders of the Ancient World

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