Some buildings at White Sands, such as the Public Affairs Office, contain granite rock taken from the Organ Mtns. which is radioactive. The rocks naturally contain measurable, but harmless, amounts of such radioactive elements as uranium and thorium.

What is this thing called "radiation" which gets people excited and ignites heated discussions and arguments?

Radiation comes from the nucleus of individual atoms. Simple atoms like carbon and oxygen are very stable. The nucleus of an oxygen atom is made up of eight protons and eight neutrons. This organization holds together very well.

The nucleus of a more complex atom like uranium is not as stable. Uranium has 92 protons and 146 neutrons in its core. These unstable atoms tend to break down into simpler forms. When a uranium atom breaks down during normal radioactive decay it emits subatomic particles and gamma rays. This is where the word "radiation" comes from since the atom radiates particles and rays.

Health physicists are concerned with four emissions from the nucleus of these atoms. One of these radiations is the alpha particle which is big and travels fairly slowly compared to other atomic particles. Alpha particles are each basically composed of two protons and two neutrons. They travel about one to three inches in the air and are easily stopped by a single sheet of paper.

Another radiation is the beta particle which is basically an electron which is very light and moves at almost the speed of light. These particles are more energetic than alpha particles but can be stopped by a thin sheet of metal or very heavy clothing.

The third form of nuclear radiation is the gamma ray. This is a type of electromagnetic radiation like visible light, radio waves and X-rays. They travel at the speed of light. It can take an inch or more of lead, iron or eight inches of concrete to stop gamma rays.

In addition to the above, neutrons are also emitted by some radioactive substances. Neutrons are very penetrating but are not very common. Neutrons do have the capability of striking the nucleus of another atom and changing a stable atom into an unstable, and, therefore radioactive one. Neutrons emitted in nuclear reactors are contained in the reactor vessel but they do make the material in the walls of the vessel radioactive.

Radioactive elements emit these radiations until they have reached a stable state. For some man-made radioactive materials this occurs in a few seconds. For other elements a small volume can emit radiation over a period of thousands of years. As they break down they turn into other elements. For instance, the Public Affairs rock walls contain forms of bismuth and thallium which are made as uranium breaks down on its way to becoming lead.

Next week, the second part of this article will talk about the dangers and risks of radiation.

Go to part 2