It was in in the year 1940, at the University of California at Berkeley, where Seaborg discovered Plutonium when he added a tremendous amount of deuterons (the nuclei in atoms of deuterium) to Uranium, which transmuted it into Plutonium. Shortly after, Seaborg was able to isolate Plutonium239 which is an isotope used in atomic bombs.
Plutonium is a highly dangerous and poisonous element because it rapidly gives off radiation in the form of alpha particles. Alpha particles as are identical to the nucleus of a helium atom and consist of two protons and two neutrons tightly bound together. Although the particles can only travel about five centimeters in the air, they can cause great damage when the enter the body. As a result of that, they can cause cancer and other serious health problems. Beyond the danger of their radiation, Plutonium will spontaneously explode when a certain amount (called critical mass) is kept together. Soon after the discovery of Plutonium, it was discovered that at least two oxidation states existed. It is now known to exist in oxidation states with the charges of +3, +4, +5, and +6.
Currently, there are fifteen known isotopes of Plutonium”, with mass numbers ranging between 232 and 246. The most important isotope is plutonium239 (also known as Pu-239). “When struck by a neutron, this isotope undergoes a process called fission.” In fission, when struck by a neutron, the nucleus of the plutonium atom is split into two nearly equal parts and energy is released. Although the energy released by one atom is not much, the splitting of the nucleus releases more neutrons, which strike more plutonium atoms. This process is called a chain-reaction and produces enormous amounts of energy. This energy is often used to power nuclear reactors, or to provide the energy for nuclear weapons.
Although plutonium is useful for generating electricity in nuclear power plants for our homes, it has other uses as well. The Plutonium isotope Pu238 is used to power all the long-range space missions. This isotope has a half life of almost 90 years. Batteries would not last long enough to power a space mission and solar power decreases to fast as the distance from the sun increases, making solar power unusable with current technology. However, the heat from the radioactive decay of Plutonium is being used to generate electricity to power spacecrafts' instruments.
Although Pu-239 is such an efficient use for energy, disposing of its waste has become a major problem. When uranium is converted to Pu-239, a waste with a half-life of around 24,100 years is produced. To dispose of it, it should clearly be identified and safely taken to an authorized company.
Another large problem for scientists creating power with plutonium is actually getting the chain-reaction to work. Often, only the first few atoms struck by the deuterons convert to Plutonium. Unfortunately for the scientists, the whole problem is a matter of probabilities and chance. “There are four factors that determine whether the reaction occurs. They are 1) escape, 2) non-fission capture by uranium, 3) non-fission capture by impurities, and 4) fission capture.” The first three factors cause the uranium to lose neutrons, the last is what causes the reaction. If the loss of neutrons is less than that of those produced, by fission capture, the reaction occurs. Otherwise, plutonium is not made, and the chain-reaction stops immediately.
The half-life of atoms of Plutonium was very important to Seaborg and his assistants back in 1940. In fact, all of his other radioactive discoveries were based on the finding of Pu-238. For example, “Pu-241 decays with a half-life of about thirteen years emitting negatively charged beta particles or also known as electrons. It then converts to Am-241, an isotope of americium, which emits alpha particles for 470 years, before turning into Am-242, which converts to Cm-242, an isotope of curium, in only sixteen hours.” The Cm-242 emits alpha particles for about 162 days before ending the decay of Plutonium 241.
Plutonium can be used as fuel for many prototype breeder reactors and existing light water reactors, which create electricity for local habitants, giving countries, with a surplus amount of uranium, a chance to go into the plutonium industry. Although with the advantage of providing electricity for the country and getting new source of income, it also as a very big disadvantage. An example is a current situation in Brazil where the US army had taken over the Uranium and Plutonium industries and used the uranium in their nuclear bombs. The Plutonium was used as fuel in their missiles. This was done so that the missiles would travel faster causing a bigger impact when they explode, and also release radioactivity. What I basically mean to say it that Plutonium can be used for war.
Another disadvantage is that it is hard to dispose. What many countries have done to overcome this problem is dump the radioactivity Plutonium into the seas, destroying marine life. Due to this problem much of Brazilian marine life forms were in danger. It took a very long time to settle the problem. But even today many countries make that mistake. Unfortunately, even I cannot suggest a better solution to this problem....
Bibliography (text):
http://www.electronicreferences.com/view.php/Science/623.HTM
http://www.pu.org/main/facts/pu.html
www.webelements.com/webelements/scholar/elements/plutonium/key.html
Encarta 1999 (CD)
The Usborne Illustrated Dictionary of Science. Authors: Corinne Stockley, Chris Oxlade, Jane Wertheim
Friend living in Brazil
Bibliography (pictures):
www.chemsoc.org/viselements/pages/ data/plutonium_data.html
www.nobel.se/chemistry/laureates/ 1951/seaborg-bio.html
web.umr.edu/~reactor/ basicphysics.html
www.floridatoday.com/space/explore/ probes/cassini/tower2.jp
