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Radioactive contamination
 
 
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Radioactive contamination is the uncontrolled distribution of radioactive
Radioactive decay

Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type, called the parent nuclide transforming to an atom of a different type, called the daughter nuclide....
 material in a given environment. The amount of radioactive material released in an accident is called the source term.

oactive contamination is typically the result of a spill or accident during the production or use of radionuclide
Radionuclide

A radionuclide is an atom with an unstable Atomic nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created radiation particle within the nucleus, or else to an atomic electron ....
s (radioisotopes), an unstable nucleus which has excessive energy.






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Radiation Warning Symbol
Radioactive contamination is the uncontrolled distribution of radioactive
Radioactive decay

Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type, called the parent nuclide transforming to an atom of a different type, called the daughter nuclide....
 material in a given environment. The amount of radioactive material released in an accident is called the source term.

Sources of contamination

Radioactive contamination is typically the result of a spill or accident during the production or use of radionuclide
Radionuclide

A radionuclide is an atom with an unstable Atomic nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created radiation particle within the nucleus, or else to an atomic electron ....
s (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
Nuclear medicine

Nuclear medicine is a branch of medicine and medical imaging that uses radioactive isotopes in the diagnosis of disease. Nuclear medicine thus relies on the process of radioactive decay....
 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
Xenon

Xenon is a chemical element represented by the chemical symbol Xe. Its atomic number is 54. A colorless, heavy, odorless noble gas, xenon occurs in the Earth's atmosphere in trace amounts....
 in nuclear fuel reprocessing
Nuclear reprocessing

Nuclear reprocessing separates components of spent nuclear fuel such as:...
. In cases that radioactive material cannot be contained, it may be diluted to safe concentrations. Nuclear fallout
Nuclear fallout

Fallout is the residual radiation hazard from a nuclear explosion, so named because it "falls out" of the atmosphere into which it is spread during the explosion....
 is the distribution of radioactive contamination by a nuclear explosion
Nuclear explosion

A nuclear explosion occurs as a result of the rapid release of energy from an intentionally high-speed nuclear reaction. The driving reaction may be nuclear fission, nuclear fusion or a multistage cascading combination of the two, though to date all fusion based weapons have used a fission device to initiate fusion, and a pure fusion weapon...
. For a discussion of environmental contamination by alpha
Alpha particle

Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium atomic nucleus; hence, it can be written as He2+ or 42He2+....
 emitters please see actinides in the environment
Actinides in the environment

Actinides in the environment refer to the sources, environmental behaviour and effects of actinides in Earth's Ecosystem. Environmental radioactivity is not limited solely to actinides; also, actinides such as uranium and radium specifically are of note....
. 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.

Measurement

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

Certified Health Physicist is An official title granted by the , the certification board for health physics in the United States. A Certified Health Physicist is designated by the letters CHP or DABHP after his or her name....
.

Surface contamination

Surface contamination is usually expressed in units of radioactivity per unit of area. For SI
Si

Si, si, or SI may refer to :...
, this is becquerel
Becquerel

The becquerel is the SI derived unit of Radioactive decay. 1 Bq is defined as the activity of a quantity of radioactive material in which one atomic nucleus decays per second....
s per square meter (or Bq/m²). Other units such as picoCuries per 100 cm² or disintegrations per minute
Counts per minute

Counts per minute is a measure of radioactivity. It is the number of atoms in a given quantity of radioactive material that are detected to have decayed in one minute....
 per square centimeter (1 dpm/cm² = 166 2/3 Bq/m²) may be used. Surface contamination may either be fixed or removable. In the case of fixed contamination, the radioactive material cannot by definition be spread, but it is still measurable.

Hazards

In practice there is no such thing as zero radioactivity. Not only is the entire world constantly bombarded by cosmic ray
Cosmic ray

Cosmic rays are energetic particles originating from space that impinge on Earth's atmosphere. Almost 90% of all the incoming cosmic ray particles are protons, about 9% are helium nuclei and about 1% are electrons ....
s, but every living creature on earth contains significant quantities of carbon-14
Carbon-14

Carbon-14, 14C, or radiocarbon, is a radioactive isotope of carbon discovered on February 27, 1940, by Martin Kamen and Sam Ruben at the University of California Radiation Laboratory in Berkeley, California, though its existence had been suggested already in 1934 by Franz Kurie....
 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.

Low level contamination

The hazards to people and the environment from radioactive contamination depend on the nature of the radioactive contaminant, the level of contamination, and the extent of the spread of contamination. Low levels of radioactive contamination pose little risk, but can still be detected by radiation instrumentation. In the case of low-level contamination by isotopes with a short half-life, the best course of action may be to simply allow the material to naturally decay
Radioactive decay

Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type, called the parent nuclide transforming to an atom of a different type, called the daughter nuclide....
. Longer-lived isotopes should be cleaned up and properly disposed of, because even a very low level of radiation can be life-threatening when in long exposure to it. Therefore, whenever there's any radiation in an area, many people take extreme caution when approaching.

High level contamination

High levels of contamination may pose major risks to people and the environment. People can be exposed to potentially lethal radiation levels, both externally and internally, from the spread of contamination following an accident (or a deliberate initiation
Nuclear weapon

A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either nuclear fission or a combination of fission and nuclear fusion....
) involving large quantities of radioactive material. The biological effects of external exposure
Radiation poisoning

Radiation poisoning, also called "radiation sickness" or a "creeping dose", is a form of damage to organ tissue due to excessive exposure to ionizing radiation....
 to radioactive contamination are generally the same as those from an external radiation source not involving radioactive materials, such as x-ray
X-ray

X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequency in the range 30 Hertz to 30 Hertz and energies in the range 120 Electron volt to 120 keV....
 machines, and are dependent on the absorbed dose
Absorbed dose

Absorbed dose is a measure of the energy deposited in a medium by ionizing radiation. It is equal to the energy deposited per unit mass of medium, and so has the unit J/kg, which is given the special name gray ....
.

Biological effects

See also: Radiation poisoning
Radiation poisoning

Radiation poisoning, also called "radiation sickness" or a "creeping dose", is a form of damage to organ tissue due to excessive exposure to ionizing radiation....


The biological effects of internally deposited radionuclide
Radionuclide

A radionuclide is an atom with an unstable Atomic nucleus, which is a nucleus characterized by excess energy which is available to be imparted either to a newly-created radiation particle within the nucleus, or else to an atomic electron ....
s depend greatly on the activity and the biodistribution and removal rates of the radionuclide, which in turn depends on its chemical form. The biological effects may also depend on the chemical toxicity
Toxicity

Toxicity is the degree to which a substance is able to damage an exposed organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver ....
 of the deposited material, independent of its radioactivity. Some radionuclides may be generally distributed throughout the body and rapidly removed, as is the case with tritiated water
Tritium

Tritium is a radioactive isotope of hydrogen. The atomic nucleus of tritium contains one proton and two neutrons, whereas the nucleus of Hydrogen atom contains one proton and no neutrons....
. Some radionuclides may target specific organs and have much lower removal rates. For instance, the thyroid
Thyroid

The thyroid is one of the largest endocrine glands in the body. This gland is found in the neck inferior to the thyroid cartilage and at approximately the same level as the cricoid cartilage....
 gland takes up a large percentage of any iodine
Iodine

Iodine , is a chemical element that has the symbol I and atomic number 53. Naturally-occurring iodine is a single isotope with 74 neutrons....
 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
Nuclear fission

In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the atomic nucleus of an atom splits into smaller parts, often producing free neutrons and lighter atomic nucleus, which may eventually produce photons ....
; it was a major component of the radiation released from the Chernobyl disaster
Chernobyl disaster

The Chernobyl disaster was a nuclear reactor accident in 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....
, leading to many cases of pediatric thyroid cancer
Thyroid cancer

Thyroid cancer refers to any of four kinds of cancer tumors of the thyroid gland: papillary thyroid cancer, follicular thyroid cancer, medullary thyroid cancer or anaplastic thyroid cancer....
 and hypothyroidism
Hypothyroidism

Hypothyroidism is the disease state in humans and in animals caused by insufficient production of thyroid hormone by the thyroid gland. Cretinism is a form of hypothyroidism found in infants....
. On the other hand, radioactive iodine is used in the diagnosis and treatment of many diseases of the thyroid precisely because of the thyroid's selective uptake of iodine.

Means of contamination

Radioactive contamination can enter the body through ingestion
Ingestion

Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in the substance through the mouth into the gastrointestinal tract, such as through eating or drinking....
, inhalation
Inhalation

Inhalation is the movement of air from the external environment, through the air ways, and into the alveoli.Inhalation begins with the onset of contraction of the diaphragm , which results in expansion of the intrapleural space and an increase in negative pressure according to Boyle's Law....
, absorption
Absorption (skin)

Skin absorption is a route by which substances can enter the body through the skin. Along with inhalation, ingestion and injection, dermis absorption is a route of exposure for toxic substances and route of administration for medication....
, or injection
Injection (medicine)

An injection is an route of administration of putting liquid into the body, usually with a hollow hypodermic needle and a syringe which is pierced through the skin to a sufficient depth for the material to be forced into the body....
. For this reason, it is important to use personal protective equipment
Personal protective equipment

Personal protective equipment refers to protective clothing, helmets, goggles, or other garment designed to protect the wearer's body or clothing from injury by electrical hazards, heat, chemicals, and infection, for job-related occupational safety and health purposes, and in sports, martial arts, combat, etc....
 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.

See also

  • Background radiation
    Background radiation

    File:Kozloduy Nuclear Power Plant - Background radiation displays.jpgBackground radiation is the ionizing radiation constantly present in the environment, emitted from a variety of natural and artificial sources....
  • Chernobyl disaster
    Chernobyl disaster

    The Chernobyl disaster was a nuclear reactor accident in 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....
  • Criticality accident
    Criticality accident

    A criticality accident, sometimes referred to as an excursion or a power excursion, occurs when a nuclear chain reaction accidentally occurs in fissile material, such as enriched uranium or plutonium....
  • Exotic pollution
    Exotic pollution

    Exotic pollution is a general definition that includes attacks involving Radioactive contamination, Chemical Warfare, or Biological Warfare agents intended to cause harm or contaminate and make unfit for use....
  • Ionizing Radiation
    Ionizing radiation

    Ionizing radiation consists of subatomic particle radiation or electromagnetic radiation that are energetic enough to detach electrons from atoms or molecules, ionize them....
  • Kory Johnson
    Kory Johnson

    Kory Johnson is an American environmentalist from Arizona. She was awarded the Goldman Environmental Prize in 1998, for her fights against toxic and radioactive contamination....
  • Nuclear and radiation accidents
    Nuclear and radiation accidents

    This article covers notable accidents involving nuclear devices and radioactive decay materials. In some cases, a release of radioactive contamination occurs, but in many cases the accident involves a sealed source or the release of radioactivity is small while the direct irradiation is large....
  • Nuclear debate
  • Nuclear power
    Nuclear power

    Nuclear power is any nuclear technology designed to extract usable energy from atomic nucleus via controlled nuclear reactions. The only method in use today is through nuclear fission, though other methods might one day include nuclear fusion and radioactive decay ....
  • Radiation biology
  • Radiation poisoning
    Radiation poisoning

    Radiation poisoning, also called "radiation sickness" or a "creeping dose", is a form of damage to organ tissue due to excessive exposure to ionizing radiation....
  • Radioactive waste
    Radioactive waste

    Radioactive wastes are waste types containing radioactive decay chemical elements that do not have a practical purpose. They are usually the products of nuclear processes, such as nuclear fission....
  • Radiophobia
    Radiophobia

    Radiophobia is an abnormal fear of ionizing radiation, also used in the sense of fear of X-rays. The term is also used to general opposition to the use of nuclear energy....
  • Relative Biological Effectiveness
    Relative biological effectiveness

    Relative Biological Effectiveness is a health physics concept introduced in the 1950s, after it was noted that different types of radiation might affect living organisms differently....
  • Rongelap Atoll
    Rongelap Atoll

    Rongelap Atoll is an island-atoll located in Micronesia. It is a municipality of the Marshall Islands. The Atoll consists of 61 islets with a combined area of approximately 3 square miles ....