DEFINITIONNuclear physics is the field ofphysics that studies the buildingblocks and interactions of atomicnuclei.
The atomAn atom consists of a positivecharged atomic nucleus where youcan find protons and neutrons and itconsists of a negative chargedatomic shell with electrons. In everyatom the number of the electrons isequal to the number of the protonsso it is neutral.
NUCLEAR ENERGYProductionChanges can occur in the structure of thenuclei of atoms. These changes are callednuclear reactions. Energy created in a nuclearreaction is called nuclear energy, or atomicenergy.Nuclear energy is produced naturally and inman-made operations under human control.Naturally: Some nuclear energy is producednaturally. For example, the Sun and other starsmake heat and light by nuclear reactions.Man-Made: Nuclear energy can be man-madetoo. Machines called nuclear reactors, parts ofnuclear power plants, provide electricity formany cities. Man-made nuclear reactions alsooccur in the explosion of atomic and hydrogenbombs.Nuclear energy is produced in two differentways, in one, large nuclei are split to releaseenergy. In the other method, small nuclei arecombined to release energy.
Nuclear Fission: In nuclear fission, the nuclei ofatoms are split, causing energy to be released. Theatomic bomb and nuclear reactors work by fission. Theelement uranium is the main fuel used to undergonuclear fission to produce energy since it has manyfavourable properties. Uranium nuclei can be easily splitby shooting neutrons at them.Fission of uranium 235 nucleus.Nuclear Fusion: In nuclear fusion, the nuclei ofatoms are joined together, or fused. This happens onlyunder 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 hydrogenbomb, humanitys most powerful and destructiveweapon, also works by fusion. The heat required to startthe fusion reaction is so great that an atomic bomb isused to provide it. Hydrogen nuclei fuse to form heliumand in the process release huge amounts of energy thusproducing a huge explosion.
Advantages of Nuclear Energy1.The Earth has limited supplies of coal and oil. Nuclear powerplants could still produce electricity after coal and oil becomescarce.2.Nuclear power plants need less fuel than ones which burn fossilfuels. One ton of uranium produces more energy than is producedby several million tons of coal or several million barrels of oil.Disadvantages of Nuclear EnergyThe nations of the world now have more than enough nuclearbombs to kill every person on Earth. The two most powerfulnations -- Russia and the United States -- have about 50,000nuclear weapons between them. What if there were to be anuclear war? What if terrorists got their hands on nuclearweapons? Or what if nuclear weapons were launched by accident?1.Nuclear explosions produce radiation. The nuclear radiationharms the cells of the body which can make people sick or evenkill them. Illness can strike people years after their exposure tonuclear radiation.2.One possible type of reactor disaster is known as a meltdown. Insuch an accident, the fission reaction goes out of control, leadingto a nuclear explosion and the emission of great amounts ofradiation.
Milestones in the History of NuclearEnergyA more in depth and detailed history of nuclear energy ison the nuclear past page.December 2, 1942: The Nuclear Age began at theUniversity of Chicago when Enrico Fermi made achain reaction in a pile of uranium.August 6, 1945: The United States dropped anatomic bomb on Hiroshima, Japan, killing over100,000.August 9, 1945: The United States dropped anatomic bomb on Nagasaki, Japan, killing over40,000.November 1, 1952: The first large version of thehydrogen bomb (thousands of times morepowerful than the atomic bomb was exploded bythe United States for testing purposes.February 21, 1956: The first major nuclear powerplant opened in England
RADIOACTIVITYRadioactivity means that atoms decays. The reason for thisdecays is that they are instable. A atomic nucleus is instablewhen he is to heavy or when a balance is missing betweenthe protons and the neutrons. The activity is the number ofdecays devided by a certain time. the unit of the activity isbecquere. 1 becquerel is one decay per second. So 20becquerels are 20 decays per second.