by us and which form a part of the total amount of radiation which we are exposed to during our lives. Radiation has undoubtedly been present in the world and the universe since its creation and has resulted in the natural radiation background which surrounds us today. Radiation, the sending out of particles, or invisible "bullets" from an atom can be both natural, meaning it can be found occurring in certain rocks and minerals, or it can be created by man. The atom, then, is the basis of this radioactivity, and a brief discussion of the atom and its relation to man and to radioactivity will be undertaken to helm lay the foundation for the understanding of the sections in the report ‘to follow. If we look at ourselves and at other objects, we see that these things appear to be more or less solid. Yet scientists also know that all matter is made up of smaller parts or components. Thus, while we can look at a beach as a whole, we also know that this physical thing we call a “beach" is also composed of millions of tiny bits of sand. Further investigation will show that the sand itself is made up of many different kinds of minerals, these minerals are made up of smaller parts called molcules, and the molecules made up of atoms, which are, for the practical purposes of this report, the smallest particles of matter which we shall discuss. The atom, we might compare to a solar system like our own. system, the sun at the center has, An atom is similar in structure. revolving around it, Around the center, In a solar a number of planets. or nucleus, revolve a number of electrons. The nucleus, however, is not generally of one substance, but several, like a handful of marbles tightly bound together by an electrical charge, which is also involved like gravity in a solar system in keeping the electrons operating in their regular positions close J0102bb