In 1950, the first commercial nuclear power plants were built. The public was promised a non-polluting, resource-rich type of energy, but how safe was, and is, nuclear energy? Although there are fewer than 500 licensed nuclear power plants in the world, many nuclear accidents have already endangered civilian lives. Major accidents are not only probable, but inevitable (Fairchild 29). Nuclear energy may seem like the ideal energy source for the future: however, there are many negative effects of nuclear energy that can lead to very dangerous situations. Energy has always been among man's fundamental concerns, along with food and shelter. Participate in all activities, from walking to using even the most complicated equipment. Humanity has faced the challenge of meeting its energy needs without risking human health and the environment. The numerous types of energy are mechanical, thermal, chemical, electrical, radiant, and atomic (Microsoft Encarta). In 1987 oil provided 32% of the world's energy. This is followed by coal with 26%, natural gas with 17%, biomass with 15% and nuclear energy with only 4% (Galperin 19). With major energy sources running out, nations are looking for new sources to provide energy for our society. Nuclear energy, the newest type of energy, was studied to see if it would be the most promising type of energy for the future. Surprisingly, nuclear energy was discovered by accident. In 1896, French scientist Antoine Henri Becquerel conducted an experiment with uranium salts and discovered that these salts emitted their own light when exposed to sunlight. Marie and Pierre Curie were fascinated by the possibilities of Becquerel rays. The Curies discovered exactly what rays were and called the phenomenon radioactivity (Halacy 6). During World War II, many scientists from around the world came to the United States to work on reactors and nuclear weapons. Very successfully, they continued after World War II and focused more on nuclear energy. Scientists immediately understood that nuclear energy would be a great source of energy because of the amount of energy it would release. Splitting a penny's worth of uranium would produce as much energy as seven and a half tons of coal (Lilienthal 85). A nuclear power plant is the place where energy is formed when nuclear fission or fusion occurs. So far, however, only the power of fission has been controlled and used to produce energy. There are many parts of the nuclear power plant, including the reactor, generator, control room, cooling systems, and power, air, and water lines. The heart of the nuclear power plant is the reactor core, which contains several hundred fuel assemblies. The reactor core is enclosed in a pressurized steel tank