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A Collection of Radiation Safety Terms...
α
A symbol for alpha particle.

α particle
A synonym for alpha particle.

γ ray
A synonym for gamma ray.

absorbed dose
The amount of energy of an ionizing radiation absorbed per unit mass of material. The standard unit for absorbed dose is the gray.

Symbol: D.
Synonym: imparted specific energy.
Related to collective dose.
Related to committed dose equivalent.
Related to committed effective dose equivalent.
Related to dose.
Related to dose equivalent.
Related to effective dose equivalent.
Related to gray.
Related to integral absorbed dose.
Related to total effective dose equivalent.


absorption
nuclear reactions and particulate radiation

   (1) The process of taking up kinetic energy of a particle.

   (2) The process of combining a particle with an atom, a nucleus, or another particle.

   (3) The decrease of the number of particles in a beam as it passes through matter.

electromagnetic radiation

   (1) The process of transferring the energy of electromagnetic radiation to matter.

   (2) The decrease of the number of photons in a beam as it passes through matter.

Related to Compton scattering.
Related to photoelectric effect.


activation
Of or pertaining to the process of inducing radioactivity by bombarding a nuclide with radiation.

accelerator
A device that uses electrostatic or electromagnetic fields to increase the kinetic energy of a particle.

Related to cyclotron. Related to linear accelerator.

activity
(1) (Colloquial) Radioactivity; the dose rate of a sample.

(2) The rate of decay of a population of radioactive nuclides. Activity can also refer to the emission rate of a radiation from a sample, useful for samples with nuclides that emit multiple radiations per disintegration. The activity of a sample is given by -λN when it contains one dominant nuclide that has a single half life. In this expression, λ is the decay constant and N is the number of atoms of that particular nuclide. N is more specifically defined as the number of nuclei in a particular nuclear state, a definition that accounts for systems in which a particular nuclide can exist in a number of isomeric states and the ground state. When the total activity is defined by a two or more radioactive nuclides or isomers, it is given by the expression -λ1N1 + λ2N2 + ... λnNn, where the terms define the decay constant and number of atoms for each isomer and nuclide.

(3) (10CFR20) The rate of disintegration (transformation) or decay of radioactive material. The units for activity are further defined as the curie (Ci) and the becquerel (Bq).

Synonym: decay rate.
Synonym: disintegration rate.


acute dose
The amount of a substance that produces an acute exposure to a biological system. For radiation it is the amount of energy deposited in the biological system or a specific tissue or component of that system.

Related to acute radiation dose.

acute exposure
A short, intense exposure to a microorganism, radiation or a toxic substance severe enough that the recovery of the biological system cannot readily occur. Acute exposures generally last less than one day.

Related to acute dose. Related to chronic exposure.

agreement state
A State of the U.S. that has entered into an agreement with the Nuclear Regulatory Commission under the Atomic Energy Act of 1954 (68 Stat 919), subsection 274b, allowing that State to regulate the use of by-product radioactive materials within its borders.

Acronym: AS.
Related to nonagreement state.


ALARA
An acronym for as low as reasonably achievable.

ALI
An acronym for annual limit on intake.

annual dose limit
The maximum dose that may be received in a calendar year.

as low as reasonably achievable
A goal for reducing radiation doses to levels far below the dose limits, taking into account the state of technology, the economics of improvements in relation to state of technology, the economics of improvements in relation to benefits to the public health and safety, and other societal and socioeconomic considerations, and in relation to utilization of nuclear energy and licensed materials in the public interest.

Acronym: ALARA.
References: 10CFR20, 10CFR30, 10CFR70, 10CFR72.


anion
A negatively charged ion.

Synonym: negative ion.
Related to cation.
Related to ion.


atom
The smallest particle of a chemical element. An atom consists of a small, dense nucleus surrounded by a cloud of electrons. The nucleus contains protons and neutrons that account for much of the atomic mass. Chemical properties are defined largely by the number of protons in the nucleus. An atom is said to be ionized when the number of electrons is not equivalent to the number of protons; the resulting electrical charge is the number of protons minus the number of electrons.

Related to exotic atom.
Related to ion.


AS
An acronym for agreement state.

attenuation
Of or pertaining to the process of attenuating radiation.

background radiation
(1) (general) Radiation that interferes with measurements. Cosmic rays and radioactivity in soil, water and air are forms of ambient radiation that often interferes with low count rate measurements. Other forms of background radiation include sources of radiation observable by the detector, contamination of samples, incomplete absorption of radiation in the detector or incomplete charge collection by the detector.

(2) (10CFR20) Ambient radiation. Radiation from cosmic sources; naturally occurring radioactive materials, including radon (except as a decay product of source material or special nuclear material); and global fallout as it exists in the environment from the testing of nuclear explosive devices. Background radiation does not include radiation from source material, by-product material, or special nuclear materials regulated by the Nuclear Regulatory Commission.

becquerel
The SI standard unit of radioactivity defined as 1.0 disintegrations per second.

Symbol: Bq.
Related to curie.
Related to microcurie.
Related to millicurie.
Related to megacurie.
Related to nanocurie.
Related to picocurie.


beta particle
The electron or positron (the antiparticle of the electron) emitted by a nucleus during beta decay. The name beta was coined by Rutherford in 1897.

Reference: E. Rutherford. Phil. Mag. 47, 109 (1897).
Symbol: β.
Symbol: β-.
Symbol: β+.
Synonym: beta.
Synonym: beta radiation.
Synonym: beta ray.
Synonym: decay electron.
Synonym: disintegration electron.
Related to alpha particle.
Related to beta decay.
Related to gamma ray.
Related to positron.


bioassay
The determination of kinds, quantities or concentrations, and, in some cases, the locations of radioactive material in the human body, whether by direct measurement (in vivo counting) or by analysis and evaluation of materials excreted or removed from the human body.

Synonym: radiobioassay.

biological half-life
The time required for the concentration of a particular substance in a biological system to be reduced by one half. A biological half-life includes only normal processes for eliminating substances, thereby excluding radioactive decay.

Synonym: biologic half-life.
Related to effective half-life.
Related to half-life.


body burden
The amount of a toxic substance in the body of a human or animal.

Bq
A symbol for becquerel.

bremsstrahlung
A synonym for bremsstrahlung radiation.

bremsstrahlung radiation
Electromagnetic radiation emitted when energetic charged particles are accelerated in the Coulomb fields of atomic nuclei. A continuous spectrum of x rays is produced.

by-product
A material produced by a process or system that is not the primary product. An example is uranium depleted in the nuclide 235U which is a by-product of the uranium enrichment process.

by-product material
Any radioactive material other than special nuclear material yielded in, or made radioactive by, exposure to the radiation incident to the process of producing or utilizing special nuclear material.

Reference: 10CFR20.1003.

calibration
The process of determining the numerical relationship between the observed output of a measurement system and the value, based upon reference standards, of the characteristic being measured.

Reference: 10CFR74.4.

calibration factor
A normalization factor that converts between the value of a measured parameter and the actual value of that parameter in a system. The need for calibration factors arises because detectors and sensors do not directly sample a parameter but instead produce a response that scales with the value of the parameter. An example is the measurement of a gamma-ray energy by a radiation detector that produces an electrical pulse whose total charge is proportional to the energy deposited by a gamma ray.

Reference: LA-UR-95-1911.

cation
A positively charged ion.

Synonym: anode ray.
Synonym: positive ion.
Related to anion.
Related to ion.


CDE
An acronym for committed dose equivalent.

CEDE
An acronym for committed effective dose equivalent.

CF
An acronym for calibration factor.

charged particle
A synonym for ion.

chronic dose
A dose delivered over a period of greater than one day.

Related to acute dose.

chronic exposure
One or more exposures that occur over a period longer than one day.

Related to acute exposure. Related to chronic dose.

chronic radiation dose
A single or multiple doses delivered over a period of greater than one day. Chronic radiation doses can be low enough to cause few effects and to permit recovery, and they can be severe enough to cause radiation sickness and death.

Related to acute radiation dose.
Related to radiation dose.
Related to radiation dose rate.
Related to radiation sickness.


Ci
A symbol for curie.

collective dose
The sum of individual doses received in a given period of time by a specified population from exposure to a specified source of radiation.

Related to absorbed dose.
Related to committed dose equivalent.
Related to committed effective dose equivalent.
Related to dose.
Related to dose equivalent.
Related to effective dose equivalent.
Related to integral absorbed dose.
Related to total effective dose equivalent.


committed dose equivalent
The dose equivalent to organs or tissues of reference (T) that will be received from an intake of radioactive material by an individual during the 50-year period following the intake.

Symbol: HT,50.
Symbol: H50.
Acronym: CDE.
Related to absorbed dose.
Related to collective dose.
Related to committed effective dose equivalent.
Related to dose.
Related to dose equivalent.
Related to effective dose equivalent.
Related to integral absorbed dose.
Related to total effective dose equivalent.
Reference: 10CFR20.1003.


committed effective dose equivalent
Acronym: CEDE.
Related to absorbed dose.
Related to collective dose.
Related to committed dose equivalent.
Related to dose.
Related to dose equivalent.
Related to effective dose equivalent.
Related to integral absorbed dose.
Related to total effective dose equivalent.
Reference: NUREG-0544, Rev. 4.


contamination
A synonym for radioactive contamination.

controlled area
(1) It is the area outside of a restricted area but within the area whose access is limited by the operator (licensee). Generally, it is the non-restricted area within the site boundary.

(2) A surface location, to be marked by suitable monuments, extending horizontally no more than 10 kilometers in any direction from the outer boundary of the underground facility, and the underlying subsurface, which area has been committed to use as a geologic repository and from which incompatible activities would be restricted following permanent closure.

(3) It is the area immediately surrounding the storage installation for which the licensee exercises authority over its use and within which spent fuel storage operations are performed.

References: 10CFR20, 10CFR60, 10CFR72.

cosmic radiation
Radiation from outer space. Cosmic rays.

cosmic rays
Relativistic (very-high-energy) particles that enter the Earth's atmosphere and secondary radiations produced by the interaction of these particles with the atmosphere. Photons or particles from outer space. High-energy cosmic rays, with energies of 104-1010 GeV, originate from outside our solar system, while lower-energy cosmic rays (<104 GeV) from our sun. Solar cosmic rays are primarily protons and helium.

coulomb
The SI unit of electric charge defined as 1.0 A-s.

Symbol: C.
Related to abcoulomb.
Related to ampere hour.
Related to faraday.
Related to statcoulomb.


count
(1) A single event recorded by radiation detection equipment. (2) The total number of events recorded over a period of time.

critical organ
The organ or part of a body most sensitive to radiation damage by an ingested radioactive nuclide or by an external radiation source.

curie
A unit of radioactivity defined as 3.7x1010 disintegrations per second. Originally it was defined as the radon emitted by 1 g of radium. An older symbol for the curie is c.

Symbol: Ci.
Related to becquerel.
Related to microcurie.
Related to millicurie.
Related to megacurie.
Related to nanocurie.
Related to picocurie.


DAC
An acronym for derived air concentration.

daughter product
A synonym for daughter nuclide.

decay
A synonym for radioactive decay.

declared pregnant woman
A woman who has voluntarily informed her employer, in writing, of her pregnancy and the estimated date of conception.

Reference: 10CFR20.

decontamination
The process of removing unwanted contaminants from the surface of an object or from an area. Decontamination is designed to reduce the risks of exposure. Contaminants can be radioactive, chemical, or biological. This term applies to removal by washing, biological agents, chemical action, mechanical cleaning, or other techniques.

Related to immediate decontamination.
Related to operational decontamination.
Related to radioactive contamination.
Related to thorough decontamination.


deep dose
A synonym for deep-dose equivalent.

deep-dose equivalent
The dose equivalent to tissue at a depth of one centimeter due to external radiation.

Symbol: Hd.
Synonym: deep dose.
Related to total organ dose equivalent.


delayed health effects
Effects of radiation that appear long after the original exposure.

Related to nonstochastic effects.
Related to stochastic effects.


depleted uranium
Uranium in which 235U has an isotopic abundance of less than is found in nature. It is less than approximately 0.711%.

Related to enriched uranium.
Related to natural uranium.


derived air concentration
The concentration of a given radionuclide in air which, if breathed by the reference man for a working year of 2,000 hours under conditions of light work, results in an intake of 1 ALI. Derived air concentration values are given in Table 1, Column 3, of appendix B to 10CFR part 20.1001-20.2401.

Reference: 10CFR20.
Acronym: DAC.
Related to annual limit on intake.
Related to light work.
Related to reference man.


deterministic effects
A synonym for nonstochastic effects.

disintegration
A synonym for radioactive decay.

disintegrations per minute
The number of decays that occur per minute for a population of a nuclide or a sample containing radioactive material.

disintegrations per second
The number of decays that occur per second for a population of a nuclide or a sample containing radioactive material.

dose
The amount of energy of a radiation absorbed in matter. The SI standard unit of dose is the gray.

Synonym: dosage.
Synonym: radiation dose.
Related to absorbed dose.
Related to collective dose.
Related to committed dose equivalent.
Related to committed effective dose equivalent.
Related to dose equivalent.
Related to effective dose equivalent.
Related to gray.
Related to integral absorbed dose.
Related to total effective dose equivalent.


dose equivalent
A synonym for equivalent dose.

dose rate
The radiation dose per unit time.

Synonym: dosage rate.

dosimeter
A device that measures radiation dose.

Synonym: dose meter.

dosimetry
Of or pertaining to the process of measuring radiation dose.

dpm
A symbol for the measurement unit decays per minute.

dps
A symbol for the measurement unit decays per second.

EDE
An acronym for effective dose equivalent.
Reference: 10CFR20.1003; 10CFR30.4; 10CFR70.4; 10CFR76.4; DOE-EH-413-9713; DOE Order 6430.1A.

effective dose
A measure of dose in which the type of radiation and the sensitivity of tissues and organs to that radiation is taken into account.

Related to effective dose equivalent.

effective dose equivalent
The sum of the dose equivalents to the organ or tissue (HT) and the weighting factors (WT) applicable to each of the body organs or tissues that are irradiated.

Symbol: HE.
Acronym: EDE.
Related to absorbed dose.
Related to collective dose.
Related to committed dose equivalent.
Related to committed effective dose equivalent.
Related to dose.
Related to dose equivalent.
Related to effective dose.
Related to integral absorbed dose.
Related to total effective dose equivalent.
Related to tissue weighting factor.


effective half-life
The time required for the concentration of a radionuclide in a biological system to be reduced by one half. An effective half-life includes all processes of elimination, including radioactive decay.

Related to biological half-life.
Related to half-life.


efficiency
The probability an incident radiation will interact with a detection medium forming a recordable event. Efficiency can also be defined as the probability an incident radiation will deposit all its energy inside the detection medium. This definition is especially appropriate for gamma-ray spectroscopy where Compton scattering and other photon-interaction processes result in a degraded electrical signal and thus a loss of detected energy.

electromagnetic radiation
Radiation consisting of interacting electric and magnetic waves. Examples include gamma rays, x-rays, ultraviolet and visible light.

Acronym: EMR.
Synonym: photon.
Related to gamma ray.
Related to ionizing radiation.
Related to nonionizing radiation.
Related to x-ray.


electron
A basic constituent of the atom. The electron is a fundamental particle that has a mass of 0.000548579903 ± 0.000000000013 atomic mass units (0.51099907 ± 0.00000015 MeV). A free, unbound electron is stable against radioactive decay. The electron is a lepton with a spin of 1/2 and a charge of -1. The positron is the antiparticle of the electron.

Symbol: e-.
Synonym: corpuscle.
Synonym: negative thermion.
Synonym: negaton.
Synonym: negatron.
Related to positron.


electron capture
A synonym for electron capture decay.

electron volt
A unit of energy defined as 1.60919x10-19 joules. It is the energy required to raise an electron through a potential difference of 1 volt. The electron volt is not an SI unit but its use is valid unit within the International System of units.

Symbol:  eV.
Symbol: (obsolete) ev.
Related to joule.


erg
A unit of energy defined as exactly 1x10-7 J.

Related to joule.

exposure
Of or pertaining to the process of being exposed to ionizing radiation or to radioactive material.

Reference: 10CFR20.
Related to ionizing radiation.
Related to nonionizing radiation.


external dose
That portion of the dose equivalent received from radiation sources outside the body.

external radiation
Generally it is radiation from sources outside a body.

extremity
A hand, forearm, elbow, foot, ankle, lower leg, or knee. Extremities are often considered separately from the rest of the body because they are less susceptible to radiation.

Reference: 10CFR20.
eye dose equivalent
The external exposure of the lens of the eye. It is taken as the dose equivalent at a tissue depth of 0.3 centimeters (300 mg/cm2).

film badge
A small badge containing photographic film that is worn by personnel to monitor radiation exposure. Gamma rays and beta particles that interact with the film cause a darkening whose intensity is a function of dose.

Related to dose.
Related to film ring.


fission
The process of splitting a heavy nucleus into two lighter nuclei. Spontaneous fission is a type of radioactive decay for some nuclides, such as 252Cf. In other nuclides fission is induced through the reaction of an incident radiation with the nucleus. Neutron-induced fission of 235U is a common example. Considerable energy is released during the fission reaction and this energy can be used to produce heat and electricity.

Synonym: atomic fission.
Synonym: nuclear fission.
Related to fission fragment.
Related to fission neutron.
Related to fission product.
Related to neutron chain reaction.
Related to neutron generation.
Related to nuclear fusion.
Related to photofission.
Related to spontaneous fission.
Related to ternary fission.


Geiger-Müller counter
A synonym for Geiger-Müller detector.

GM counter
A synonym for Geiger-Müller counter which is a synonym for Geiger-Müller detector.

gray
An SI unit of absorbed radiation dose. One gray is equivalent to an energy absorption of 1 J/kg. It has replaced the rad, an older standard. One gray is equivalent to 100 rad.

Symbol: Gy.
Related to absorbed dose.
Related to roentgen absorbed dose.
Related to sievert.
Reference: 10CFR10; NUREG-0544, Rev. 4.


Gy
A symbol for gray.
Reference: 10CFR20.1004; 10CFR34.3; DOD 3150.8-M; DOE-HDBK-1106-97; USACHPPM TG 204.
half-value layer
A synonym for half-value thickness.

half-value thickness
That amount of an absorber which is required to reduce the intensity of a radiation by one half.

Symbol: D.
Synonym: half-value layer.


Hd
A symbol for deep-dose equivalent.

HE
A symbol for effective dose equivalent.

HE,50
A symbol for committed effective dose equivalent.

health physics
The study of the effects of radiation on humans, the monitoring of radiation exposure and the reduction of health risks associated with radiation exposure.

Acronym: HP.

high radiation area
An area, accessible to individuals, in which radiation levels could result in an individual receiving a dose equivalent in excess of 0.1 rem (1 mSv) in 1 hour at 30 centimeters from the radiation source or from any surface that the radiation penetrates.

Reference: 10CFR20.
Related to radiation area.
Related to very high radiation area.


hot spot
Location where the radioactivity or radiation is higher than expected. Part of a fuel element surface that has become overheated.

Hs
A symbol for shallow-dose equivalent.

HT
A symbol for committed equivalent dose.

individual monitoring devices
Devices designed to be worn by a single individual for the assessment of dose equivalent such as film badges, thermoluminescence dosimeters (TLDs), pocket ionization chambers, and personal (lapel) air sampling devices.

Synonym: individual monitoring equipment.
Reference: 10CFR20.1003.


individual monitoring equipment
A synonym for individual monitoring devices.

intake
Material ingested, inhaled, or absorbed through the skin or otherwise introduced into the body.

Related to uptake.

internal radiation
Radiation produced by the decay of radioactive material in the body.

inverse square law
The intensity of a radiation field is inversely proportional to the square of the distance from the source.

ion
An atom or molecule that has a non-zero electric charge.

Synonym: charged particle.
Related to anion.
Related to atom.
Related to cation.


ionization
Of or pertaining to the process of ionizing an atom, ion or molecule.

ionization chamber
A volume that contains a detection gas and electrodes which is used to count radiations or monitor radiation fields.

Related to ionization detector.

ionizing radiation
Any electromagnetic or particulate radiation capable of producing ionization in matter. Examples of ionizing radiation include alpha particles, beta particles, gamma rays x-rays, neutrons, high-speed electrons, high-speed protons, and other particles capable of producing ions. This definition excludes non-ionizing radiation, such as radio- or microwaves, or visible, infrared, or ultraviolet light.

Synonym: ionising radiation.
Related to electromagnetic radiation.
Related to nonionizing radiation.
Related to radiation.


isotopic tracer
A synonym for tracer.

isotope
Two or more nuclides with the same number of protons. Isotopes are the same chemical element. The nuclides 5Li, 6Li, 7Li, and 8Li, all have 3 protons and are thus isotopes. Isotope is often incorrectly used in place of the term nuclide.

Related to isobar.
Related to isomer.
Related to isotone.
Related to nuclide.


J
A symbol for joule.

joule
An SI unit of energy defined as 1.0 kg m2/s2 or 1.0 N m.

Symbol: J.
kinetic energy
Energy possessed by a particle, nucleon, nucleus, atom or other body by virtue of its motion.

label
(1) A synonym for labeled atom. (2) A specific nuclide, stable or radioactive, attached to a molecule. Labels are used to track chemical or other processes. For a stable nuclide to be considered a label, the presence of the nuclide must perturb the isotopic ratio normally present in the sample.

labeled compound
A molecule that contains a specific stable or radioactive nuclide.

Synonym: labeled molecule.

LD-50/30
A symbol for median lethal dose 50/30.

LD-50/60
A symbol for median lethal dose 50/60.

mCi
A symbol for millicurie.

micro
A unit prefix equivalent to 10-6.

Symbol: μ.

microcurie
A unit of radioactivity equivalent to 1.0x10-6 curies. The becquerel has replaced the curie as a unit of radioactivity.

Symbol: μCi.
Related to becquerel.
Related to curie.
Related to megacurie.
Related to millicurie.
Related to nanocurie.
Related to picocurie.


milli
A unit prefix equivalent to 10-3.

Symbol: m.

millicurie
A unit of radioactivity equivalent to 0.001 curies. The becquerel has replaced the curie as a unit of radioactivity.

Symbol: mCi.
Related to becquerel.
Related to curie.
Related to megacurie.
Related to microcurie.
Related to nanocurie.


milliroentgen
A unit of radiation exposure equivalent to 0.001 roentgen.

Symbol: mR.
Related to roentgen.


monitoring
The measurement of radiation levels, concentrations, surface area concentrations or quantities of radioactive material and the use of the results of these measurements to evaluate potential exposures and doses.

Synonym: radiation monitoring.
Synonym: radiation protection monitoring.


mR
A symbol for milliroentgen.

nano
A unit prefix equivalent to 10-9.

Symbol: n.

NARM
An acronym for naturally occurring or accelerator-produced radioactive materials.

neutron
A basic constituent of the atomic nucleus. The neutron is a fundamental particle, has a mass of 1.008664904 ± 0.000000014 atomic mass units (939.56563 ± 0.00028 MeV). Free, unbound neutrons are produced in fission and in some radioactive decay processes (especially beta decay). A free neutron is unstable, having a half life of 614.6±1.3 s and decaying by β- decay. The neutron is a hadron that is composed of three quarks, udd, and it has a spin-parity of 1/2+ and a magnetic moment of -1.91304275±0.00000045.

Symbol: n.
Related to Bragg neutron.
Related to neutron.
Related to proton.


nonstochastic effects
Health effects, the severity of which varies with the dose and for which a threshold is believed to exist. Radiation-induced cataract formation is an example of a nonstochastic effect.

Reference: 10CFR20.
Synonym: deterministic effects.
Related to stochastic effects.


NRC
Acronym for Nuclear Regulatory Commission.

natural background radiation
Ionizing radiation produced by cosmic rays, the interaction of cosmic rays with matter, and from the decay of non-anthropogenic radioactive materials.

natural radiation
A synonym for natural background radiation.

NORM
An acronym for naturally-occurring radioactive material.

Nuclear Regulatory Commission
The U.S. Nuclear Regulatory Commission (NRC) is an independent agency established by the Energy Reorganization Act of 1974 to regulate civilian use of nuclear materials. NRC is headed by a five-member Commission.

The NRC's mission is to regulate the Nation's civilian use of byproduct, source, and special nuclear materials to ensure adequate protection of public health and safety, to promote the common defense and security, and to protect the environment.

The NRC's regulatory mission covers three main areas: (1) Reactors - Commercial reactors for generating electric power and nonpower reactors used for research, testing, and training; (2) Materials - Uses of nuclear materials in medical, industrial, and academic settings and facilities that produce nuclear fuel; (3) Waste - Transportation, storage, and disposal of nuclear materials and waste, and decommissioning of nuclear facilities from service.

Acronym: NRC.
Web Site: NRC


nucleus
A synonym for atomic nucleus.

nuclide
An atom or a collection of atoms whose nuclei have a specified number of protons and neutrons. Isotope is often (incorrectly) used for the term nuclide. The term nuclide was originally proposed by T.P. Kohman in 1947.

Related to isobar.
Related to isomer.
Related to isotone.
Related to isotope.


occupational dose
An individual’s ionizing radiation dose (external and internal) as a result of that individual's work assignment. Occupational dose does not include doses received as a medical patient or doses resulting from background radiation or participation as a subject in medical research programs.

Reference: 10CFR835.2.

particle accelerator
A synonym for accelerator.

photon
A quantum of electromagnetic radiation such as a gamma ray or an x-ray. It is a boson and has a mass of 0, a charge of 0 and a spin of 1.

Related to electromagnetic radiation.
Related to gamma ray.
Related to X-ray.


pico
A unit prefix equivalent to 10-12.

Symbol: p.

pig
A heavily shielded container designed to safely store or transport radioactive materials.

Related to cask.
Related to cave.
Related to coffin.


pocket dosimeter
A small ionization detector that is generally used to monitor whole body exposure.

positron
The antiparticle of the electron. Its mass and spin are identical to that of the electron but it has a charge of +1.

Symbol: e+.
Symbol: β+.
Synonym: positive electron.
Synonym: positon.
Related to beta particle.
Related to electron.
Related to exotic atom.


protective barrier
A material or a set of materials that absorbs radiation and is designed to reduce exposure.

proton
A basic constituent of the atomic nucleus. The proton is a fundamental particle, has a mass of 1.007276470 ± 0.000000012 atomic mass units (938.27231 ± 0.00028 MeV). Chemical elements are defined by the number of protons in the nucleus, which is equal to the atomic number of that element. Free, unbound protons are stable with respect to radioactive decay with the lower limit of their half life as 1.1x1025 yr. The proton is a hadron that is composed of three quarks, uud, and it has a spin-parity of 1/2+ and a magnetic moment of +2.792847386 ± 0.000000063.

Symbol: p.
Related to atomic number.
Related to electron.
Related to neutron.
Related to nucleon.


public dose
The dose received by a member of the public from exposure to radiation or to radioactive material released by a licensee, or to any other source of radiation under the control of a licensee. Public dose does not include occupational dose or doses received from background radiation, from any medical administration the individual has received, from exposure to individuals administered radioactive material and released under section 35.75, or from voluntary participation in medical research programs.

Reference: 10CFR20.1003.

QF
A symbol for quality factor.
Reference: 10CFR20.1003; DOE G 421.1-1.


quality factor
A measure of the effectiveness of a radiation at producing injury in a biological system. It is dependent on the linear energy transfer of a radiation. The dose times the quality factor is known as an equivalent dose. The quality factor has been superceded by the radiation weighting factor in the definition of the equivalent dose, except for calculations.

   x-rays: QF = 1
   Gamma Rays: QF = 1
   Beta Particles: QF = 1
   Neutrons, Unknown Energy: QF = 10
   High-Energy Protons: QF = 10
   Alpha Particles: QF = 20
   Multiple-Charged Particle: QF = 20
   Heavy particles, unknown charge: QF = 20
   Fission Fragments: QF = 20
   Neutrons E less than 1x10-3 MeV: QF = 2
   Neutrons E = 0.001 MeV: QF = 2.5
   Neutrons E = 0.01 MeV: QF = 7.5
   Neutrons E = 0.1 MeV: QF = 11
   Neutrons E = 0.5 MeV: QF = 9
   Neutrons E = 1 MeV: QF = 8
   Neutrons E = 2.5 MeV: QF = 7
   Neutrons E = 5 MeV: QF = 6.5
   Neutrons E = 7 MeV: QF = 7.5
   Neutrons E = 10 MeV: QF = 8
   Neutrons E = 14 MeV: QF = 7
   Neutrons E = 20 MeV: QF = 5.5
   Neutrons E = 40 MeV: QF = 4
   Neutrons E = 60 MeV: QF = 3.5
   Neutrons E ≥100 MeV: QF = 3.5.


Symbol: QF.
Related to dose equivalent.
Related to roentgen equivalent man.
Related to sievert.
Reference: 10CFR20.1003; NUREG-0544, Rev. 4.


R
A symbol for roentgen.

rad
(1) A symbol for roentgen absorbed dose.
(2) A symbol for radiation absorbed dose.


radiation area
An area, accessible to individuals, in which radiation levels could result in an individual receiving a dose equivalent in excess of 0.005 rem (0.05 mSv) in 1 hour at 30 centimeters from the radiation source or from any surface that the radiation penetrates.

Reference: 10CFR20.
Related to high radiation area.
Related to very high radiation area.


radiation dose
A synonym for dose.
Reference: 10CFR20.1003.


radiation safety officer
An individual with responsibility for the overall radiation safety program at the facility.

Acronym: RSO.
Reference: 10CFR36.


radioactive decay
Spontaneous emission by a nucleus of photons or particles.

The spontaneous transformation of one nuclide into another by emission of particles, absorption of an orbital electron, or by fission. It also refers to gamma-ray and conversion electron emission that only reduces the excitation energy of the nucleus.

Synonym: atom disintegration.
Synonym: atomic disintegration.
Synonym: decay.
Synonym: disintegration.
Synonym: nuclear disintegration.
Synonym: radioactive disintegration.


radioactive half-life
A synonym for half-life.

radioactivity
Of or pertaining to radioactive nuclides, or objects or matter containing radioactive nuclides.

radiobioassay
A synonym for bioassay.

radiography
The examination of the structure of materials by nondestructive methods, utilizing sealed sources of byproduct materials. Radiations can be used to produce images of an object either by measuring their transmission through or their interaction with the object. Medical x-rays and x-ray baggage inspection are examples of transmission measurements. A neutron baggage inspection system images an object by measuring the spatial distribution of capture gamma rays produced by the reaction of neutrons with nitrogen in the object. Autoradiography describes the process of imaging an object using radiations produced by the radioactive decay of nuclides in the object. The radionuclides can be the result of radionuclide tagging, contamination by some source, or they can be produced by irradiating the object with neutrons or other radiations.

References: 10CFR30, 10CFR34.

radioisotope
A synonym for radionuclide.

radiology
The study and use of radiation and radioactive substances for the treatment of disease.

radionuclide
A radioactive nuclide.

Synonym: radioisotope.

radiosensitivity
The sensitivity of a cell, organ or organism to the exposure of radiation.

Related to radioresistance.

radiotoxicity
The hazard posed by a radiation or radioactive material to a cell, organ or organism.

reference man
A hypothetical aggregation of human (male or female) physical and physiological characteristics arrived at by international consensus. These characteristics may be used by researchers and public health workers to standardize results of experiments and to relate biological insult from ionizing radiation to a common base.

relative biological effectiveness
The ratio of an absorbed dose of a radiation to that of a standard which will give comparable damage in a biological material.

Acronym: RBE.
Synonym: biologic effectiveness of radiation.
Reference: NUREG-0544, Rev. 4.


rem
A symbolfor for roentgen equivalent man.
Reference: NUREG-0544, Rev. 4.


restricted area
An area, access to which is limited for the purpose of protecting individuals against undue risks from exposure to radiation and radioactive materials. Restricted area does not include areas used as residential quarters, but separate rooms in a residential building may be set apart as a restricted area.

Related to controlled area.
Related to unrestricted area.
Reference: 10CFR20.1003.


roentgen
A unit of radiation exposure defined as the amount of x- or gamma-radiation that produces 1 esu of charge per cm3 of dry air at 0 °C and 760 torr.

Symbol: R.
Related to milliroentgen.


RSO
An acronym for radiation safety officer.

scintillation counter
A synonym for scintillation detector.

sealed source
A radioactive source specifically manufactured, obtained, or retained for the purpose of utilizing the emitted radiation. The sealed radioactive source consists of a known quantity of radioactive material contained within a sealed capsule, sealed between layers of non-radioactive material, or firmly fixed to a non-radioactive surface by electroplating or other means intended to prevent leakage or escape of the radioactive material.

Any special nuclear material that is encased in a capsule rod, element, etc. designed to prevent leakage or escape of the special nuclear material and that prevents removal of the special nuclear material without penetrating the casing.

Any by-product material that is encased in a capsule designed to prevent leakage or escape of the by-product material.

Synonym: sealed radioactive source.

sievert
The SI unit of absorbed dose defined as the number of grays times a quality factor. The sievert represents a dose equivalent or a dose that is correlated with injury due to radiation exposure.

Symbol: Sv.
Related to gray.
Related to quality factor.
Related to roentgen equivalent man.
Reference: NUREG-0544, Rev. 4.


SNM
An acronym for special nuclear material.

source material
(1) Uranium or thorium, or any combination thereof, in any physical or chemical form.

(2) Ores that contain by weight one-twentieth of one percent (0.05%) or more of (i) uranium, (ii) thorium, or (iii) any combination thereof. Source material does not include special nuclear material.

References: 10CFR20, 10CFR30, 10CFR72, 10CFR76.

special nuclear material
The plutonium nuclides, 233U, and uranium enriched in 235U.

Acronym: SNM.
Related to source material.


specific activity
The radioactivity of an isotope per unit weight of the element in a sample. The number of radioactive decays per unit mass of a sample. Additional Note: 10CFR part 71 includes the note that the radioactivity is uniformly distributed through the material.

stable isotope
A synonym for stable nuclide.

stochastic effects
Health effects that occur randomly and for which the probability of the effect occurring, rather than its severity, is assumed to be a linear function of dose without threshold. Hereditary effects and cancer incidence are examples of stochastic effects.

Reference: 10CFR20.
Related to nonstochastic effects.


Sv
A symbol for sievert.
Reference: 10CFR20.1004; 10CFR34.3; DOD 3150.8-M; DOE G 421.1-1; DOE-HDBK-1106-97.


TEDE
An acronym for total effective dose equivalent.
Reference: 10CFR20.1003; 10CFR50.2; 10CFR63.2; 10CFR835.2; DOE G 440.1-3; DOE G 441.1-3; DOE G 441.1-11; DOE M 231.1-2; USACHPPM TG 204.


thermoluminescent dosimeter
A synonym for thermoluminescence dosimeter.

tissue weighting factor
A normalization factor applied to equivalent doses to account for different sensitivities of tissues and organs. Tissue weighting factors recommended in ICRP publication 60 are bladder: 0.05; bone surface: 0.01; breast: 0.05; colon: 0.12; esophagus: 0.05; gonads: 0.20; liver: 0.05; lung: 0.12; red bone marrow: 0.12; skin: 0.01; stomach: 0.12; thyroid: 0.05; and remainder: 0.05.

Symbol: wT.
Synonym: organ weighting factor.
Related to radiation weighting factor.
Reference: ICRP Publication 60.


TLD
An acronym for thermoluminescence dosimeter.

TODE
An acronym for total organ dose equivalent.

total effective dose equivalent
The sum of the deep-dose equivalent (for external exposures) and the committed effective dose equivalent (for internal exposures).

Acronym: TEDE.
Related to absorbed dose.
Related to collective dose.
Related to committed dose equivalent.
Related to committed effective dose equivalent.
Related to dose.
Related to dose equivalent.
Related to effective dose equivalent.
Related to integral absorbed dose.
Reference: 10CFR20.1003; NUREG-0544, Rev. 4.


total organ dose equivalent
The sum of the deep-dose equivalent and the committed dose equivalent for an organ.

Acronym: TODE.
Related to committed dose equivalent.
Related to deep-dose equivalent.
Related to dose.


tracer
A nuclide incorporated into a molecule to provide information on chemical processes and pathways. The tracer can be radioactive or an enriched stable isotope of an element.

Synonyms: indicator; isotope tracer; isotopic indicator; isotopic tracer.

tracer, isotopic
See instead isotopic tracer.

tritium
An isotope of hydrogen with a single proton and two neutrons. Tritium is radioactive with a half-life of 12.33 years. It is found in nature as a result of the interaction of cosmic rays in the upper atmosphere. A tritium nucleus is called a triton.

Symbol: 3H.
Symbol: T.
Related to deuterium.
Related to hydrogen.
Related to triton.


uptake
Material injected into the body or absorbed through the gastrointestinal or respiratory tracks.

Related to intake.

unrestricted area
Any area, access to which is not controlled by the licensee for purposes of protection of individuals from exposure to radiation and radioactive materials, and any area used for residential quarters.

References: 10CFR20, 10CFR60.
Related to controlled area.
Related to restricted area.


unstable isotope
(colloguial term)
A synonym for radioactive nuclide.


very high radiation area
An area, accessible to individuals, in which radiation levels could result in an individual receiving an absorbed dose in excess of 500 rads (5 grays) in 1 hour at 1 meter from a radiation source or from any surface that the radiation penetrates. Note: At very high doses received at high dose rates, units of absorbed dose (e.g., rads and grays) are appropriate, rather than units of dose equivalent (e.g., rems and sieverts).

Reference: 10CFR20.
Related to high radiation area.
Related to radiation area.


weighting factor
A measure of the effectiveness of a radiation at producing injury in a biological system. It is dependent on the linear energy transfer of a radiation. The dose times the quality factor is known as a dose equivalent. Gonads: wT = 0.25; Breast: wT = 0.15; Red Bone Marrow: wT = 0.12; Lung: wT = 0.12; Thyroid: wT = 0.03; Bone Surface: wT = 0.03; Remainder: wT = 0.30; Whole Body: wT = 1.00.

References: 10CFR20, 10CFR70.
Symbol: wT.
Related to effective dose equivalent.


WT
A symbol for tissue weighting factor.

x-rays
Photons or electromagnetic radiation produced by the de-excitation of bound atomic electrons. The energy of an x-ray is equivalent to the difference in energy of the initial and final atomic state minus the binding energy of the electron.

Synonym: (Obsolete) x radiation.
Related to electromagnetic radiation.
Related to gamma ray.
Related to photon.








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