The degree of agreement between a measurement and the true value of the quantity measured.

Air particulates

Airborne particles that include dust, dirt, and other pollutants that occur as particles, and any pollutants that may be associated with or carried on the dust or dirt.


An exact fractional portion of a sample taken for analysis.

Alpha particle

A charged particle, identical to the helium nucleus, comprising two protons and two neutrons that are emitted during decay of certain radioactive atoms. Alpha particles are stopped by several centimeters of air or a sheet of paper.

Ambient air

The surrounding atmosphere, usually the outside air, as it exists around people, plants, and structures. It does not include the air next to emission sources.


A saturated layer of rock or soil below the ground surface that can supply usable quantities of ground water to wells and springs. Aquifers can be a source of water for domestic, agricultural, and industrial uses.

Background radiation

Ionizing radiation from sources other than LBNL. Background may include cosmic radiation; external radiation from naturally occurring radioactivity in the earth (terrestrial radiation), air, and water; internal radiation from naturally occurring radioactive elements in the human body; and radiation from medical diagnostic procedures.

Becquerel (Bq)

Unit of radioactive decay equal to one disintegration per second (SI unit).

Beta particle

A charged particle, identical to the electron, that is emitted during decay of certain radioactive atoms. Most beta particles are stopped by less than 0.6 centimeters of aluminum.

Categorical process

An industrial process governed by federal regulation(s) of wastewater discharges.

Collective effective dose equivalent

The sum of the effective dose equivalents of all individuals in an exposed population within a certain radius, usually 80 kilometers for NESHAPs compliance. This value is expressed in units of person-sievert (SI) or person-rem (conventional).


Any hazardous or radioactive material present in an environmental medium such as air, water, or vegetation.

Controlled area

Any Laboratory area with controlled access to protect individuals from exposure to radiation and radioactive materials.

Cosmic radiation

High-energy particulate and electromagnetic radiation that originates outside the earth’s atmosphere. Cosmic radiation is part of the natural background radiation.


Unit of radioactive decay equal to 2.22 ´ 1012 disintegrations per minute (conventional units).


A release of a liquid into an area not controlled by LBNL.


The quantity of radiation energy absorbed during a given period of time.

Dose, absorbed

The energy imparted to matter by ionizing radiation per unit mass of irradiated material. The unit of absorbed dose is the gray (SI) or rad (conventional).

Dose, effective

The hypothetical whole-body dose that would give the same risk of cancer mortality and/or serious genetic disorder as a given exposure and that may be limited to just a few organs. The effective dose equivalent is equal to the sum of individual organ doses, each weighted by degree of risk that the organ dose carries. For example, a 1-millisievert dose to the lung, which has a weighting factor of 0.12, gives an effective dose that is equivalent to 0.12 millisievert (1 ´ 0.12).

Dose, equivalent

A term used in radiation protection that expresses all types of radiation (alpha, beta, and so on) on a common scale for calculating the effective absorbed dose. It is the product of the absorbed dose and certain modifying factors. The unit of dose equivalent is the sievert (SI) or rem (conventional).

Dose, maximum boundary

The greatest dose commitment, considering all potential routes of exposure, from a facility’s operation to a hypothetical individual who is in an uncontrolled area where the highest dose rate occurs. It assumes that the hypothetical individual is present 100% of the time (full occupancy), and it does not take into account shielding by obstacles such as buildings or hillsides.

Dose, maximum individual

The greatest dose commitment, considering all potential routes of exposure, from a facility’s operation to an individual at or outside the LBNL boundary where the highest dose rate occurs. It takes into account shielding and occupancy factors that would apply to a real individual.

Dose, population

The sum of the radiation doses to individuals of a population. It is expressed in units of person-sievert (SI) or person-rem (conventional). For example, if 1000 people each received a radiation dose of 1 sievert, their population dose would be 1000 person-sievert.


A portable detection device for measuring the total accumulated exposure to ionizing radiation. See also Thermoluminescent dosimeter.


Commonly used to describe the flow of groundwater from higher to lower concentration. Analogous to “downstream.”

Effective dose equivalent

Abbreviated EDE, it is the sum of the products of the dose equivalent received by specified tissues of the body and a tissue-specific weighting factor. This sum is a risk-equivalent value and can be used to estimate the health risk of the exposed individual. The tissue-specific weighting factor represents the fraction of the total health risk resulting from uniform whole-body irradiation that would be contributed by that particular tissue. The EDE includes the committed EDE from internal deposition of radionuclides and the EDE due to penetrating radiation from sources external to the body. EDE is expressed in units of sievert (SI) or rem (conventional).


A liquid waste discharged to the environment.


A release of air to the environment containing gaseous or particulate matter having one or more contaminants.

Environmental remediation

The process of improving a contaminated area to a noncontaminated or safe condition.


A measure of the ionization produced in air by x-ray or gamma radiation. The unit of exposure is the coulomb per kilogram (SI) or roentgen (conventional).

External radiation

Radiation originating from a source outside the body.

Gamma radiation

Short-wavelength electromagnetic radiation of nuclear origin that has no mass or charge. Because of its short wavelength (high energy), gamma radiation can cause ionization. Other electromagnetic radiation, such as microwaves, visible light, and radio waves, have longer wavelengths (lower energy) and cannot cause ionization.


A subsurface body of water in a zone of saturated soil sediments.

Half-Life, radioactive

The time required for the activity of a radioactive substance to decrease to half its value by inherent radioactive decay. After two half-lives, one-fourth of the original activity remains (1/2 ´ 1/2); after three half-lives, one-eighth of the original activity remains (1/2 ´ 1/2 ´ 1/2); and so on.

Hazardous waste

Waste exhibiting any of the following characteristics: ignitability, corrosivity, reactivity, or EP-toxicity (yielding toxic constituents in a leaching test). Because of its concentration, quantity, physical, or chemical characteristics, it may (1) cause or significantly contribute to an increase in mortality rates or cases of serious irreversible illness or (2) pose a substantial present or potential threat to human health or the environment when improperly treated, stored, transported, disposed of, or handled.

Internal radiation

Radiation from a source within the body as a result of deposition of radionuclides in body tissues by processes such as ingestion, inhalation, or implantation. Potassium (40K), a naturally occurring radionuclide, is a major source of internal radiation in living organisms.


A common unit for reporting radiation dose. A millirem is one thousandth (10–3) of a rem. See Rem.


A species of atom characterized by what constitutes the nucleus, which is specified by the number of protons, number of neutrons, and energy content; or, alternatively, by the atomic number, mass number, and atomic mass. To be regarded as a distinct nuclide, the atom must be able to exist for a measurable length of time.

Organic compound

A chemical whose primary constituents are carbon and hydrogen.

Part B permit

The second, narrative section submitted by generators in the RCRA permitting process. It details the procedures followed at a facility to protect human health and the environment.


The unit of population dose, which expresses the sum of radiation exposures received by a population. For example, two persons, each with a 0.5-rem exposure, receive 1 person-rem, and 500 people, each with an exposure of 0.002 rem, also receive 1 person-rem.


A measure of hydrogen ion concentration in an aqueous solution. Acidic solutions have a pH less than 7, basic solutions have a pH greater than 7, and neutral solutions have a pH of 7.


Generally, a small-diameter, nonpumping well used to measure the elevation of the water table or potentiometric surface. The water table is an imaginary surface that represents the static head of groundwater and is defined by the level to which water will rise.


Any hazardous or radioactive material present in an environmental medium such as air, water, or vegetation.


The degree of agreement between measurements of the same quantity.


Any process used to reduce a pollutant load before wastewater enters the sewer system.

Priority pollutants

A set of organic and inorganic chemicals identified by US/EPA as indicators of environmental contamination


A unit of absorbed dose from ionizing radiation (0.877 rad/roentgen).

Radiation protection standard

Limits on radiation exposure regarded as necessary for protection of public health. These standards are based on acceptable levels of risk to individuals.


Electromagnetic energy in the form of waves or particles.


The property or characteristic of a nucleus of an atom to spontaneously disintegrate, accompanied by the emission of energy in the form of radiation.


Arising from radiation or radioactive materials.


An unstable nuclide. See nuclide and radioactivity.

Recharge zone

An area of the ground in which surface water migrates to the groundwater.


Acronym for “roentgen equivalent man.” A unit of ionizing radiation, equal to the amount of radiation needed to produce the same biological effect to humans as 1 rad of high-voltage x-rays. It is the product of the absorbed dose, quality factor, distribution factor, and other necessary modifying factors. It describes the effectiveness of various types of radiation in producing biological effects.


See Environmental remediation.


A unit of radiation exposure that expresses exposure in terms of the amount of ionization produced by x or gamma rays in a volume of air. One roentgen is 2.58 ´ 104 coulombs per kilogram of air.


A unit of radiation dose equivalent. The sievert is the SI unit equivalent to the rem. It is the product of the absorbed dose, quality factor, distribution factor, and other necessary modifying factors. It describes the effectiveness of various types of radiation to produce biological effects. One sievert equals 100 rem.


Any operation or equipment that produces, discharges, and/or emits pollutants (e.g., pipe, ditch, well, or stack).


Pertaining to or deriving from the earth.

Terrestrial radiation

Radiation emitted by naturally occurring radionuclides, such as 40K; the

natural decay chains 235U, 233U, or 232Th; or cosmic-ray induced radionuclides in the soil.

Thermoluminescent dosimeter

A type of dosimeter. After being exposed to radiation, the material in the dosimeter (lithium fluoride) luminesces on being heated. The amount of light that the material emits is proportional to the amount of radiation (dose) to which it was exposed. See also Dosimeter.


A radionuclide of hydrogen with a half-life of 12.3 years. The very low energy of its radioactivity decay makes it one of the least hazardous radionuclides.

Uncontrolled area

An area beyond the boundaries of a controlled area. See Controlled area.


Opposite of the direction of groundwater flow from a designated area of interest. Analogous to “upstream.”

Vadose zone

The partially saturated or unsaturated region of the ground above the water table that does not yield water to wells.

Wind rose

A graph that shows the frequency and intensity of wind from different directions at a particular site.

Table G-1     Prefixes Used with Sl (Metric) Units

Prefix Factor Symbol
exa 1,000,000,000,000,000,000 = 1018 E
peta 1,000,000,000,000,000 = 1015 P
tera 1,000,000,000,000 = 1012 T
giga 1,000,000,000 = 109 G
mega 1,000,000 = 106 M
kilo 1,000 = 103 k
hecto 100 = 102 h*
deka 10 = 101 da*
deci 0.1 = 10–1 d*
centi 0.01 = 10–2 c*
milli 0.001 = 10–3 m
micro 0.000001 = 10–6 m
nano 0.000000001 = 10–9 n
pico 0.000000000001 = 10–12 p
femto 0.000000000000001 = 10–15 f
atto 0.000000000000000001 = 10–18 a
*Avoid where practical.

Table G-2      Conversion Factors for Selected Sl (Metric) Units

To convert Sl unit

To U.S. conventional unit

Multiply by



square centimeters

square inches


square meters

square feet


square kilometers

square miles







micrograms per gram

parts per million


milligrams per liter

parts per million


























pounds per square foot







2.7 ´ 10-11










coulomb per kilogram





degrees Celsius

degrees Fahrenheit

1.8, then add 32



meters per second

miles per hour




cubic meters

cubic feet