RADIOACTIVE AGENTS

Use of nuclear material by terrorists would likely involve
one of four scenarios below. Fortunately, the most
devastating scenarios are the least likely.

• Detonation of a nuclear device: nuclear explosion
  
• Meltdown of a nuclear reactor: melting of the
  nuclear fuel within a reactor with limited release of
  radioactive materials into the environment if reactor
  containment is also breached
  
• Dispersal of material though use of conventional
  explosives: a radiation dispersal device (RDD) or
  “dirty bomb”
  
• Non-explosive dispersal of nuclear material: placing
  radioactive materials in public places

Principles of Radiation

Radiation is everywhere. Visible sunlight and radar are forms non-ionizing radiation, as are television and radio signals. Cell phones use non-ionizing radiation to transmit our conversations.

Ionizing radiation is radiation that can injure living
tissue by transferring energy to vital cell components. Ionizing radiation is a natural part of our environment. Everyone is continuously exposed to a small amount of ionizing radiation, called background radiation. Sources of background radiation are both
natural and man-made.

Ionizing radiation transfers energy to cells in the body. If the radiation is strong enough, the cell will be killed. Less severe radiation exposure and damage may exceed the cell’s ability to repair itself or leave permanent alteration in the cells functioning or genetic material (e.g., predispose to development of cancer).

There are two types of ionizing radiation:

• Electromagnetic (wave) radiation
• Particle radiation

Ionizing electromagnetic radiation consists of gamma rays and x-rays. These waves have no mass or charge and can pass through tissue easily, irradiating casualties but leaving no radioactivity behind. They transfer kinetic energy to tissue as they pass through it, damaging the atoms that make up cells.

Particle radiation consists of alpha particles, beta particles, and neutrons. Alpha and beta particles do not travel very far from their source and cannot penetrate skin effectively.