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Centers for disease control and prevention - Radiation protection terms
Category: Sciences > Radiation
Date & country: 27/04/2012, US
Words: 58

Activity (radioactivity)
the rate of decay of radioactive material expressed as the number of atoms breaking down per second measured in units called becquerels or curies.

Ambient air
the air that surrounds us.

the smallest particle of an element that can enter into a chemical reaction.

Atomic mass number
the total number of protons and neutrons in the nucleus of an atom.

Atomic mass unit (amu)
1 amu is equal to one twelfth of the mass of a carbon-12 atom.

Atomic number
the total number of protons in the nucleus of an atom.

an assessment of radioactive materials that may be present inside a person

a cancer-causing substance.

the ratio of the amount of a specific substance in a given volume or mass of solution to the mass or volume of solvent.

Critical mass
the minimum amount of fissile material that can achieve a self-sustaining nuclear chain reaction.

Decay constant
the fraction of a number of atoms of a radioactive nuclide that disintegrates in a unit of time. The decay constant is inversely proportional to the radioactive half-life.

Decay, radioactive
disintegration of the nucleus of an unstable atom by the release of radiation.

Deposition density
the activity of a radionuclide per unit area of ground. Reported as becquerels per square meter or curies per square meter.

a non-radioactive isotope of the hydrogen atom that contains a neutron in its nucleus in addition to the one proton normally seen in hydrogen. A deuterium atom is twice as heavy as normal hydrogen. See also tritium.

Dirty bomb
a device designed to spread radioactive material by conventional explosives when the bomb explodes. A dirty bomb kills or injures people through the initial blast of the conventional explosive and spreads radioactive contamination over possibly a large area

Dose (radiation)
radiation absorbed by person

Dose rate
the radiation dose delivered per unit of time.

assessment (by measurement or calculation) of radiation dose.

an elementary particle with a negative electrical charge and a mass 1/1837 that of the proton. Electrons surround the nucleus of an atom because of the attraction between their negative charge and the positive charge of the nucleus. A stable atom will have as many electrons as it has protons. The number of electrons that orbit an atom determine its chemical properties. See also neutron.

Electron volt (eV)
a unit of energy equivalent to the amount of energy gained by an electron when it passes from a point of low potential to a point one volt higher in potential.

Enriched uranium
uranium in which the proportion of the isotope uranium-235 has been increased by removing uranium-238 mechanically. See also depleted uranium.

the study of the distribution and determinants of health-related states or events in specified populations; and the application of this study to the control of health problems.

Exposure (radiation)
a measure of ionization in air caused by x-rays or gamma rays only. The unit of exposure most often used is the roentgen. See also contamination.

Exposure rate
a measure of the ionization produced in air by x-rays or gamma rays per unit of time (frequently expressed in roentgens per hour).

External exposure
exposure to radiation outside of the body.

Fission (fissioning)
the splitting of a nucleus into at least two other nuclei that releases a large amount of energy. Two or three neutrons are usually released during this transformation. See also fusion.

Hot spot
any place where the level of radioactive contamination is considerably greater than the area around it.

Internal exposure
exposure to radioactive material taken into the body.

a nonmetallic solid element. There are both radioactive and non-radioactive isotopes of iodine. Radioactive isotopes of iodine are widely used in medical applications. Radioactive iodine is a fission product and is the largest contributor to people

exposure to radiation.

a nuclide of an element having the same number of protons but a different number of neutrons.

Latent period
the time between exposure to a toxic material and the appearance of a resultant health effect.

Megaton (Mt)
the energy of an explosion that is equivalent to an explosion of 1 million tons of TNT. One megaton is equal to a quintillion (1018) calories. See also kiloton.

a combination of two or more atoms that are chemically bonded. A molecule is the smallest unit of a compound that can exist by itself and retain all of its chemical properties.

pertaining to the pathologic process resulting in the formation and growth of an abnormal mass of tissue.

Nuclear energy
the heat energy produced by the process of nuclear fission within a nuclear reactor or by radioactive decay.

a proton or a neutron; a constituent of the nucleus of an atom.

the central part of an atom that contains protons and neutrons. The nucleus is the heaviest part of the atom.

Polonium (Po)
a radioactive chemical element and a product of radium (Ra) decay. Polonium is found in uranium (U) ores.

Prenatal radiation exposure
radiation exposure to an embryo or fetus while it is still in its mother

Protective Action Guide (PAG)
a guide that tells state and local authorities at what projected dose they should take action to protect people from exposure to unplanned releases of radioactive material into the environment.

Radiation warning symbol
a symbol prescribed by the Code of Federal Regulations. It is a magenta or black trefoil on a yellow background. It must be displayed where certain quantities of radioactive materials are present or where certain doses of radiation could be received.

Radioactive decay
the spontaneous disintegration of the nucleus of an atom.

Radioactive material
material that contains unstable (radioactive) atoms that give off radiation as they decay.

health effects caused by exposure to ionizing radiation.

1) medical

Radiological or radiologic
related to radioactive materials or radiation. The radiological sciences focus on the measurement and effects of radiation.

an unstable and therefore radioactive form of a nuclide.

Risk assessment
an evaluation of the risk to human health or the environment by hazards. Risk assessments can look at either existing hazards or potential hazards.

Roentgen (R)
a unit of exposure to x-rays or gamma rays. One roentgen is the amount of gamma or x-rays needed to produce ions carrying 1 electrostatic unit of electrical charge in 1 cubic centimeter of dry air under standard conditions.

ability of an analytical method to detect small concentrations of radioactive material.

the material between a radiation source and a potentially exposed person that reduces exposure.

Stable nucleus
the nucleus of an atom in which the forces among its particles are balanced. See also unstable nucleus.

waste rock from mining operations that contains concentrations of mineral ore that are too low to make typical extraction methods economical.

Thermonuclear device

(chemical symbol H-3) a radioactive isotope of the element hydrogen (chemical symbol H). See also deuterium.

United Nations Scientific Committee on the Effects of Atomic Radiation. See also http

Whole body count
the measure and analysis of the radiation being emitted from a person