RADIOACTIVE CONTAMINATION

 

 

Radioactive contamination is the uncontrolled distribution of radioactive materials in a given environment. The amount of radioactive materials released in an accident is called the source term.

 

 

Sources of contamination

• Results of a spill or accident during the production or use of radionuclides (radioisotopes), an unstable nucleus which has excessive energy.
• Contamination may occur from radioactive gases, liquids or particles. For example, if a radionuclide used in nuclear medicine is accidentally spilled, the materials could be spread by people as they walk around.
• Radioactive contamination may also be an inevitable result of certain processes, such as the release of radioactive xenon in nuclear fuel reprocessing.
• Nuclear fallout is the distribution of radioactive contamination by a nuclear explosion.
• Containment is what differentiates radioactive material from radioactive contamination. Therefore, radioactive material in sealed and designated containers is not properly referred to as contamination, although the units of measurement might be the same.

 

Biological effects

• Some radionuclides may be generally distributed throughout the body and rapidly removed, as is the case with tritiated water.
• Some radionuclides may target specific organs and have much lower removal rates. For instance, the thyroid gland takes up a large percentage of any iodine that enters the body. If large quantities of radioactive iodine are inhaled or ingested, the thyroid may be impaired or destroyed, while other tissues are affected to a lesser extent. Radioactive iodine is a common fission product leading to many cases of pediatric thyroid cancer and hypothyroidism.