Radioactive Contamination

1.Definition.

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

2.Source of Contamination.

Radioactive contamination is typically the result 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 material 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. In cases that radioactive material cannot be contained, it may be
diluted to safe concentrations. Nuclear fallout is the distribution of radioactive
contamination by a nuclear explosion. For a discussion of environmental
contamination by alpha emitters please see actinides in the environment.
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.

3.Measurement.

Radioactive contamination may exist on surfaces or in volumes of material or air. In a nuclea
power plant, detection and measurement of radioactivity and contamination is often the job of
a Certified Health Physicist.

4.Hazards.

In practice there is no such thing as zero radioactivity. Not only is the entire world constantly
bombarded by cosmic rays, but every living creature on earth contains significant quantities
of carbon-14 and most (including humans) contain significant quantities of potassium-40.
These tiny levels of radiation are not any more harmful than sunlight, but just as excessive
quantities of sunlight can be dangerous, so too can excessive levels of radiation.

5.Meaning of Contamination.

Radioactive contamination can enter the body through ingestion, inhalation, absorption, or injection. For this reason, it is important to use personal protective equipment when working with radioactive materials. Radioactive contamination may also be ingested as the result of eating contaminated plants and animals or drinking contaminated water or milk from exposed animals. Following a major contamination incident, all potential pathways of internal exposure should be considered.

6.Effects of Radioactive Contamination.

One of the effect of the Radioactive contamination is Chernobyl Disaster.

The Chernobyl disaster was a nuclear reactor accident at the Chernobyl Nuclear Power Plant in Ukraine, then part of the Soviet Union. It is considered to be the worst nuclear power plant disaster in history and the only level 7 instance on the International Nuclear Event Scale. It resulted in a severe release of radioactivity following a massive power excursion which destroyed the reactor. Two people died in the initial steam explosion, but most deaths from the accident were attributed to radiation. On 26 April 1986 01:23:45 a.m. (UTC+3) reactor number four at the Chernobyl plant, near Pripyat in the Ukrainian Soviet Socialist Republic, exploded. Further explosions and the resulting fire sent a plume of highly radioactive fallout into the atmosphere and over an extensive geographical area. Four hundred times more fallout was released than had been by the atomic bombing of Hiroshima.
The plume drifted over extensive parts of the western Soviet Union, Eastern Europe, Western Europe, Northern Europe, and eastern North America, with light nuclear rain falling as far as Ireland. Large areas in Ukraine, Belarus, and Russia were badly contaminated, resulting in the evacuation and resettlement of over 336,000 people. According to official post-Soviet data,about 60% of the radioactive fallout landed in Belarus.
The accident raised concerns about the safety of the Soviet nuclear power industry, slowing its expansion for a number of years, while forcing the Soviet government to become less secretive. The countries of Russia, Ukraine, and Belarus have been burdened with the continuing and substantial decontamination and health care costs of the Chernobyl accident. It is difficult to accurately quantify the number of deaths caused by the events at Chernobyl, as the Soviet-era cover-up made it difficult to track down victims. Lists were incomplete, and Soviet authorities later forbade doctors to cite "radiation" on death certificates.
The 2005 report prepared by the Chernobyl Forum, led by the International Atomic Energy Agency (IAEA) and World Health Organization (WHO), attributed 56 direct deaths (47 accident workers, and nine children with thyroid cancer), and estimated that there may be 4,000 extra cancer deaths among the approximately 600,000 most highly exposed people.Although the Chernobyl Exclusion Zone and certain limited areas remain off limits, the majority of affected areas are now considered safe for settlement and economic activity.