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Encyclopedia > Background radiation

Background radiation is the ionizing radiation emitted from a variety of natural and artificial radiation sources: sources in the Earth and from those sources that are incorporated in our food and water, which are incorporated in our body, and in building materials and other products that incorporate those radioactive sources; radiation sources from space (in the form of cosmic rays); and sources in the atmosphere which primarily come from both the radon gas that is released from the earth's surface and subsequently decays to radioactive atoms that become attached to airborne dust and particulates, and the production of radioactive atoms from the bombardment of atoms in the upper atmosphere by high-energy cosmic rays. Today, a small fraction of background radiation also comes from radioactive tools such as smoke detectors and self-luminous dials and signs, and from global radioactive contamination due to historical nuclear weapons testing, nuclear power station or nuclear fuel reprocessing accidents, and from nomal operation of the nuclear power industry. Sometimes included in background radiation are routine medical procedures like X-ray imaging; this is purposeful diagnostic exposure which dwarfs all other human-caused background radiation in the population of the industrialized world. Ionizing radiation is either particle radiation or electromagnetic radiation in which an individual particle/photon carries enough energy to ionize an atom or molecule by completely removing an electron from its orbit. ... Radiation in physics is a process of emission of energy or particles. ... Earth (often referred to as The Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth in order of size. ... Layers of Atmosphere - not to scale (NOAA) Outer space, also called just space, refers to the relatively empty regions of the Universe outside the atmospheres of celestial bodies. ... Cosmic rays can loosely be defined as energetic particles originating outside of the Earth. ... Layers of Atmosphere (NOAA) Air redirects here. ... Residential ceiling-mounted smoke detector A smoke detector is a safety device that detects airborne smoke and issues an audible alarm, thereby alerting nearby people to the danger of fire. ... The radiation warning symbol (trefoil). ... Preparation for an underground nuclear test at the Nevada Test Site in the 1980s. ... A nuclear power plant (NPP) is a thermal power station in which the heat source is one or more nuclear reactors. ... Nuclear reprocessing separates any usable nuclear fuels (e. ... A nuclear power station. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz...

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Natural background radiation

Natural background radiation comes from two primary sources: cosmic radiation and terrestrial sources. The worldwide average background dose for a human being is about 2.4 mSv per year [1] (pdf). This exposure is mostly from cosmic radiation and natural isotopes in the Earth. This is far greater than human-caused background radiation exposure, which in the year 2000 amounted to an average of about 0.01 mSv per year from historical nuclear weapons testing, nuclear power accidents and nuclear industry operation combined [1], and is greater than the average exposure from medical tests, which ranges from 0.04 to 1 mSv per year. Cosmic rays can loosely be defined as energetic particles originating outside of the Earth. ...


Cosmic radiation

The Earth, and all living things on it, are constantly bombarded by radiation from outer space. This radiation primarily consists of positively charged ions from protons to iron nuclei derived from the sun and from other sources outside our solar system. This radiation interacts with atoms in the atmosphere to create secondary radiation, including X-rays, muons, protons, alpha particles, pions, electrons, and neutrons. The immediate dose from cosmic radiation is largely from muons, neutrons, and electrons, and this dose varies in different parts of the world based largely on the geomagnetic field and altitude. This radiation is much more intense in the upper troposphere, c. 10km altitude, and is thus of particular concern for airline crews and frequent passengers, who spend many hours per year in this environment. Here, the radiation exposure is not primarily due to the cosmic ray interaction with the thin atmosphere, but with the dense fuselage of the aircraft, causing relatively high background radiation in the cabin while the aircraft is at high altitude. Similarly, cosmic ray interaction with spacecraft components produces secondary radiation that causes higher background exposure in astronauts than in humans on the surface of Earth. Astronauts in low orbits, such as in the International Space Station or the Space Shuttle, are at low risk because the magnetic field of the Earth shields out most cosmic rays. Outside low Earth orbit, as experienced by the Apollo astronauts who travelled to the moon, this background radiation is much more intense, and represents a considerable obstactle to potential future long term human exploration of the moon or Mars. Properties In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... A semi-accurate depiction of the helium atom. ... The Sun is the star at the center of our solar system. ... The solar system comprises the Earths Sun and the retinue of celestial objects gravitationally bound to it. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... The moons shadow, as seen in muons 700m below ground at the Soudan 2 detector. ... Properties In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... An alpha particle is deflected by a magnetic field Alpha particles (named after the first letter in the Greek alphabet, α) are a highly ionizing form of particle radiation which have low penetration. ... In particle physics, pion (short for pi meson) is the collective name for three subatomic particles: Ï€0, Ï€+ and π−. Pions are the lightest mesons and play an important role in explaining low-energy properties of the strong nuclear force. ... Properties The electron (also called negatron, commonly represented as e−) is a subatomic particle. ... Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 939. ... Dose can refer to several things: n An amount of medication to be taken at one time. ... The cause of Earths magnetic field (the surface magnetic field) is not known for certain, but is possibly explained by dynamo theory. ... The Troposphere is the lowermost portion of Earths atmosphere. ... A Boeing 747-400 belonging to Virgin Atlantic Airways, one of the UKs largest airlines. ... In an aircraft, the fuselage is the main body section that holds crew and passengers or cargo. ... A spacecraft is designed to leave Earths atmosphere and operate beyond the surface of the Earth in outer space. ... U.S. Space Shuttle astronaut Bruce McCandless II using a manned maneuvering unit (MMU) outside the Challenger in 1984. ... Earth (often referred to as The Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth in order of size. ... In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... International Space Station insignia ISS Statistics Crew: 2 As of March 5, 2006 Perigee: 352. ... The Space Shuttle Columbia seconds after engine ignition, 1981 (NASA). ... Current flowing through a wire produces a magnetic field (B, labeled M here) around the wire. ... Lycian Apollo, early Imperial Roman copy of a fourth century Greek original (Louvre Museum) In Greek and Roman mythology, Apollo (Greek: Απόλλων, Apóllōn; or Απελλων, Apellōn), the ideal of the kouros,[1] was the archer-god of medicine and healing and also a bringer of death-dealing plague; as... Bulk composition of the moons mantle and crust estimated, weight percent Oxygen 42. ... For the Roman god, see Mars (mythology). ...


Cosmic rays also cause elemental transmutation in the atmosphere, in which secondary radiation generated by the cosmic rays combine with atomic nuclei in the atmosphere to generate different radioactive isotopes. Many so-called cosmogenic nuclides can be produced, but probably the most notable is carbon-14, which is produced by interactions with nitrogen atoms. These cosmogenic nuclides eventually reach the earth's surface and can be incorporated into living organisms. The production of these nuclides varies slightly with short-term variations in solar cosmic ray flux, but is considered practically constant over long scales of thousands to millions of years. The constant production, incorporation into organisms and relatively short half-life of carbon-14 are the principles used in radiocarbon dating of ancient biological materials such as wooden artifacts or human remains. // Transmutation is the conversion of one object into another. ... The nucleus (atomic nucleus) is the center of an atom. ... Isotopes are atoms of a chemical element whose nuclei have the same atomic number, Z, but different atomic weights, A. The word isotope, meaning at the same place, comes from the fact that isotopes are located at the same place on the periodic table. ... Carbon-14 is the radioactive isotope of carbon discovered February 27, 1940, by Martin Kamen and Sam Ruben. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... Radiocarbon dating is a radiometric dating method that uses the naturally occurring isotope carbon-14 to determine the age of carbonaceous materials up to ca 60,000 years. ...


Terrestrial sources

Radioactive material is found throughout nature. It occurs naturally in the soil, rocks, water, air, and vegetation. The major radionuclides of concern for terrestrial radiation are common elements with low-abundance radioactive isotpes, like potassium and carbon, or rare but intensely radioactive elements like uranium, thorium, radium and radon. Most of these sources have been decreasing, due to radioactive decay since the formation of the Earth, because there is no significant amount currently transported to the Earth. Thus, our present dose from uranium-238 is only half as much as it originally was because of its 4.5 billion year half-life, and potassium-40 (half life 1.25 billion years) is only at about 8% of original activity. Many shorter half-life and thus more intensely radioactive isotopes have not decayed out of the terrestrial environment, however, because of natural ongoing production of them. Examples of these are carbon-14 (cosmogenic), radium-226 (decay product of uranium-238) and radon-222 (decay product of radium-226). Soil is the material on the surface of a lithosphere subject to weathering, and especially the earthy portion of that material. ... Atoms of chemical elements may have many isotopes (different forms) with the same atomic numbers but different atomic weights / atomic mass numbers. ... General Name, Symbol, Number potassium, K, 19 Chemical series alkali metals Group, Period, Block 1, 4, s Appearance silvery white Atomic mass 39. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Atomic mass 12. ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Atomic mass 238. ... General Name, Symbol, Number thorium, Th, 90 Chemical series Actinides Group, Period, Block n/a, 7, f Appearance silvery white Atomic mass 232. ... General Name, Symbol, Number radium, Ra, 88 Chemical series alkaline earth metals Group, Period, Block 2, 7, s Appearance silvery white metallic Atomic mass (226) g/mol Electron configuration [Rn] 7s2 Electrons per shell 2, 8, 18, 32, 18, 8, 2 Physical properties Phase solid Density (near r. ... General Name, Symbol, Number radon, Rn, 86 Chemical series noble gases Group, Period, Block 18, 6, p Appearance colorless Atomic mass (222) g/mol Electron configuration [Xe] 4f14 5d10 6s2 6p6 Electrons per shell 2, 8, 18, 32, 18, 8 Physical properties Phase gas Melting point 202 K (-71 °C... Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles (radiation). ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Atomic mass 238. ... General Name, Symbol, Number potassium, K, 19 Chemical series alkali metals Group, Period, Block 1, 4, s Appearance silvery white Atomic mass 39. ... General Name, Symbol, Number radium, Ra, 88 Chemical series alkaline earth metals Group, Period, Block 2, 7, s Appearance silvery white metallic Atomic mass (226) g/mol Electron configuration [Rn] 7s2 Electrons per shell 2, 8, 18, 32, 18, 8, 2 Physical properties Phase solid Density (near r. ... There are two objects with this name: Unterseeboot 238 Uranium-238, the most common isotope of uranium This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... General Name, Symbol, Number radon, Rn, 86 Chemical series noble gases Group, Period, Block 18, 6, p Appearance colorless Atomic mass (222) g/mol Electron configuration [Xe] 4f14 5d10 6s2 6p6 Electrons per shell 2, 8, 18, 32, 18, 8 Physical properties Phase gas Melting point 202 K (-71 °C... General Name, Symbol, Number radium, Ra, 88 Chemical series alkaline earth metals Group, Period, Block 2, 7, s Appearance silvery white metallic Atomic mass (226) g/mol Electron configuration [Rn] 7s2 Electrons per shell 2, 8, 18, 32, 18, 8, 2 Physical properties Phase solid Density (near r. ...


Some of the essential elements that make up the human body, mainly potassium and carbon, have radioactive isotopes that add significantly to our background radiation dose. An average human contains about 30 milligrams of potassium-40 and about 10-8 grams of carbon-14. Excepting internal contamination by external radioactive material, the largest component of internal radiation exposure from biologically functional components of the human body is from potassium-40.


Radon

Radon is a terrestrial source of radiation that is of particular concern because, although on average it is very rare, this intensely radioactive element can be found in high concentrations in many areas of the world, where it represents a significant health hazard. Radon is a decay product of uranium, which is relatively common in the earth's crust, but generally concentrated in ore-bearing rocks scattered around the world. Radon seeps out of these ores into the atmosphere or into ground water, and in these localities it can accumulate within dwellings and expose humans to high concentrations. The widespread construction of well insulated and sealed homes in the northern industrialized world has led to radon becoming the primary source of background radiation in some localities in northern North America and Europe. Some of these areas, including Cornwall and Aberdeenshire in the United Kingdom have high enough natural radiation levels that nuclear licensed sites cannot be built there—the sites would already exceed legal radiation limits before they opened, and the natural topsoil and rock would all have to be disposed of as low-level nuclear waste. General Name, Symbol, Number radon, Rn, 86 Chemical series noble gases Group, Period, Block 18, 6, p Appearance colorless Atomic mass (222) g/mol Electron configuration [Xe] 4f14 5d10 6s2 6p6 Electrons per shell 2, 8, 18, 32, 18, 8 Physical properties Phase gas Melting point 202 K (-71 °C... Cornwall (Cornish: Kernow) is a county at the extreme South-West of England on the peninsula that lies to the west of the River Tamar. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Low-level waste (LLW) is a term used to describe nuclear waste that does not fit into the categorical definitions for high-level waste (HLW), spent nuclear fuel (SNF), transuranic waste (TRU), or certain byproduct materials known as 11e(2) wastes, such as uranium mill tailings. ...


Radiation exposure from radon is indirect. Radon has a short half-life (4 days) and decays into other solid particlulate radium-series radioactive nuclides. These radioactive particles are inhaled and remain lodged in the lungs, causing continued exposure. People in affected localities can receive up to 10 mSv per year background radiation [1]. Radon is thus the second leading cause of lung cancer after smoking, and accounts for 15,000 to 22,000 cancer deaths per year in the US alone 2. Nearly all the decay products of radioactive decay are themselves radioactive. ... Lung cancer is a cancer of the lungs characterized by the presence of malignant tumours. ... Smoking may refer to: Smoke, a product of fire Tobacco smoking, a common recreational practice Recreational drug use, use of psychoactive drugs for recreational purposes Smoking, a method for curing food. ...


Human-caused background radiation

Frequent above-ground nuclear exposions between the 1940s and 1960s scattered a substantial amount of radioactive contamination. Some of this contamination is local, rendering the immediate surroundings highly radioactive, while some of it is carried longer distances as nuclear fallout; some of this material is dispersed worldwide. The increase in background radiation due to these tests peaked in 1963 at about 0.15 mSv per year worldwide, or about 7% of average background dose from all sources. The Limited Test Ban Treaty of 1963 prohibited above-ground tests, thus by the year 2000 the worldwide dose from these historical tests has decreased to only 0.005 mSv per year [1]. The radiation warning symbol (trefoil). ... Map of hypothetical fallout dispersal after a large-scale nuclear attack against the United States. ... The Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space, and Under Water, often abbreviated as the Partial Test Ban Treaty (PTBT), Limited Test Ban Treaty (LTBT), or Nuclear Test Ban Treaty (NTBT), although the former also refers to the Comprehensive Test Ban Treaty (CTBT), is a treaty...


Nuclear reactors may also release a certain amount of radioactive contamination. Under normal circumstances, a modern nuclear reactor releases minuscule amounts of radioactive contamination. However, reprocessing plants released waste, including plutonium, directly into the ocean. Major accidents, which have fortunately been relatively rare, have also released some radioactive contamination into the environment; this is the case, for example, with the Windscale fire (Sellafield accident) and the Chernobyl accident. General Name, Symbol, Number plutonium, Pu, 94 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery white Atomic mass (244) g/mol Electron configuration [Rn] 5f6 7s2 Electrons per shell 2, 8, 18, 32, 24, 8, 2 Physical properties Phase solid Density (near r. ... On October 10, 1957, the graphite core of a British nuclear reactor at Windscale, Cumbria, caught fire releasing substantial amounts of radioactive contamination into the surrounding area. ... The Sellafield facility on the Cumbrian coast, United Kingdom Sellafield is the name of a nuclear site, close to the village and railway station of Seascale, () [1] operated by British Nuclear Fuels Limited (BNFL), but owned since 1 April 2005 by the Nuclear Decommissioning Authority. ... The nuclear power plant at Chernobyl prior to the completion of the sarcophagus. ...


The amount of radioactive contamination released by human activity is rather small, in global terms, but the radiation background is also rather low. Some sources claim that the Earth's background radiation level has tripled since the beginning of the twentieth century. In fact, the total amount of radioactivity released by man is inconsequential to the large quantities of radioactivity in the natural environment [2] (pdf).


Artificial radiation sources

The radiation from natural and artificial radiation sources are identical in their nature and their effects. These materials are distributed in the environment, and in our bodies, according to the chemical properties of the elements. The Nuclear Regulatory Commission, the Environmental Protection Agency, and other U.S. and international agencies, require that licensees limit radiation exposure to individual members of the public to 100 mrem (1 mSv) per year, and limit occupational radiation exposure to adults working with radioactive material to 5 rem (50 mSv) per year, and 10 rem (100 mSv) in 5 years. NRC headquarters in Bethesda, MD. Nuclear Regulatory Commission (or NRC) is a United States government agency that was established by the Energy Reorganization Act in 1974, and was first opened January 19, 1975. ... EPA redirects here. ... The Röntgen equivalent man or rem (symbol rem) is an obsolete unit of radiation dose. ... The sievert (symbol: Sv) is the SI derived unit of dose equivalent. ...


The exposure for an average person is about 360 millirems/year, 80 percent of which comes from natural sources of radiation. The remaining 20 percent results from exposure to artificial radiation sources, such as medical X-rays, industrial sources like smoke detectors and a small fraction from nuclear weapons tests. In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Residential ceiling-mounted smoke detector A smoke detector is a safety device that detects airborne smoke and issues an audible alarm, thereby alerting nearby people to the danger of fire. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 kilometers (11 mi) above the hypocenter. ...


Other usage

In other contexts, background radiation may simply be any radiation that is pervasive. A particular example of this is the cosmic microwave background radiation, a nearly uniform glow that fills the sky in the microwave part of the spectrum; stars, galaxies and other objects of interest in radio astronomy stand out against this background. In cosmology, the cosmic microwave background radiation (most often abbreviated CMB but occasionally CMBR, CBR or MBR) is a form of electromagnetic radiation discovered in 1965. ... Microwave image of 3C353 galaxy at 8. ...


In a laboratory, background radiation refers to the measured value from any sources that affect an instrument when a radiation source sample is not being measured. This background rate, which must be established as a stable value by multiple measurements, usually before and after sample measurement, is subtracted from the rate measured when the sample is being measured.


Background radiation for occupational doses measured for workers is all radiation dose that is not measured by radiation dose measurement instruments in potential occupational exposure conditions. This includes both "natural background radiation" and any medical radiation doses. This value is not typically measured or known from surveys, such that variations in the total dose to individual workers is not known. This can be a significant confounding factor in assessing radiation exposure effects in a population of workers who may have significantly different natural background and medical radiation doses. This is most significant when the occupational doses are very low.


References

[1] United Nations Scientific Committee on the Effects of Atomic Radiation


[2] Radon and Cancer: Questions and Answers - National Cancer Institute (USA)


  Results from FactBites:
 
Background radiation - Wikipedia, the free encyclopedia (836 words)
A particular example of this is the cosmic microwave background radiation, a nearly uniform glow that fills the sky in the microwave part of the spectrum; stars, galaxies and other objects of interest in radio astronomy stand out against this background.
This background rate, which must be established as a stable value by multiple measurements, usually before and after sample measurement, is subtracted from the rate measured when the sample is being measured.
Background radiation for occupational doses measured for workers is all radiation dose that is not measured by radiation dose measurement instruments in potential occupational exposure conditions.
Cosmic microwave background radiation - Wikipedia, the free encyclopedia (3754 words)
The cosmic microwave background was predicted by George Gamow, Ralph Alpher, and Robert Hermann in 1948.
The interpretation of the cosmic microwave background was a controversial issue in the 1960s with some proponents of the steady state theory arguing that the microwave background was the result of scattered starlight from distant galaxies.
The period after the emission of the cosmic microwave background and the observation of the first stars is semi-humorously referred to by cosmologists as the dark age, and is a period which is under intense study by astronomers (See 21 centimeter radiation).
  More results at FactBites »

 
 

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