What is Radiation?
From the U.S. Nuclear Regulatory Commission(NRC) - June 23, 2003
All material is composed of atoms. Atoms are comprised of various parts -- the nucleus that contains minute particles called protons and neutrons, and an outer shell made up of other particles called electrons. The nucleus carries a positive electrical charge, the electrons a negative electrical charge. As electrons are bound to the nucleus of the atom, so are the particles within the nucleus. These forces within the nucleus work toward a strongly stable balance. The process by which the nuclei of atoms work toward becoming stable is to get rid of excess energy. Unstable nuclei may emit a quantity of energy, or they may emit a particle. This emitted atomic energy or particle is what we call radiation.
Types of Radiation
There are two basic kinds of radiation: One kind of radiation is tiny fast-moving particles that have both energy and mass (weight) known as particle radiation. The other kind of radiation is pure energy with no weight. This kind of radiation is like vibrating or pulsating waves of electrical and magnetic energy. The radiation waves are called electromagnetic waves or electromagnetic radiation.
Ionizing/non-ionizing Ionization is the process of removing electrons from atoms, leaving two electrically charged particles (ions) behind. Some forms of radiation like visible light, microwaves, or radio waves do not have sufficient energy to remove electrons from atoms and hence, are called non-ionizing radiation. The negatively charged electrons and positively charged nuclei may cause changes in living tissue.
Radioactive Decay Large unstable atoms can become more stable by emitting radiation. This process is called radioactive decay. This radiation can be emitted in the form of a positively charged ALPHA particle, a negatively charged BETA particle, or GAMMA RAYS.
Fission or Nuclear Fission Some elements can split as a result of absorbing an additional neutron. This is called fission or nuclear fission. Such isotopes are called fissile isotopes. One particular fissile isotope is Uranium-235. This is the isotope used in commercial nuclear reactors. When a nucleus fissions three important events occur which result in the release of energy. These events are: release of radiation, release of neutrons (usually two or three), and two new nuclei (fission products) are formed.
