Radioactive atoms

Many of the fission fragments produced when atoms are split (fissioned) are unstable and release radiation to achieve stability. Once an atom reaches stability, it is no longer radioactive. More specifically, there are three major forms of radiation:

  • Alpha particles
  • Beta particles
  • Gamma rays

All three can produce similar biological effects, but are different in many ways.

Alpha radiation

Alpha radiation consists of particles with a positive electric charge. They readily collide with and are stopped by the atoms and molecules in the matter they encounter. These alpha particles can be stopped by the first layer of skin, a few inches of air or a sheet of paper.

Beta radiation

Beta radiation consists of particles with a negative electric charge. Because they are slightly faster and smaller, beta particles can travel a little farther than alpha particles. However, wood or a thin sheet of metal can block these particles.

Gamma radiation

Gamma radiation is an electromagnetic ray similar to, but stronger than, X-rays. Gamma radiation can easily pass through the human body, but can be stopped by lead several inches thick or concrete several feet thick.


From the standpoint of health and safety, concern about radiation stems from its ability to ionize other elements. Ionization involves the change of the electron structure of an atom. Radiation can knock electrons from their orbit, altering atoms and molecules (groups of atoms). Depending on type and quantity, uncontrolled radiation can damage the human body or environment.

Barriers to radiation

This picture explains the barriers to the different forms of radiation.

Barriers to Radiation