DEFINITIONS

absorbed dose The energy imparted by ionizing radiation per unit mass of irradiated material. The units of absorbed dose are the rad and the gray (Gy).

activity The rate of disintegration (transformation) or decay of radioactive material. The units of activity are the curie (Ci) and the becquerel (Bq).

As Low As Reasonably Achievable (ALARA) – Making every reasonable effort to maintain exposures as far below the dose limits as is practical, taking into account economic considerations and other societal concerns.

becquerel (Bq) The SI unit of activity. 1 Bq equals 1 disintegration per second.

byproduct material As used in the Atomic Energy Act:

(1)

Any radioactive material (except special nuclear material) yielded in, or made radioactive by, exposure to the radiation incident to the process of producing or using special nuclear material; and

(2)

The tailings or wastes produced by the extraction or concentration of uranium or thorium from ore processed primarily for its source-material content, including discrete surface wastes resulting from uranium-solution extraction processes. Underground ore bodies depleted by solution-extraction operations do not constitute byproduct material according to this definition.

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

committed dose equivalent (H_T,50) The dose equivalent to organs or tissues of reference (T) that will be received from an intake of radioactive material by a person during the 50-y period after the intake.

committed effective dose equivalent (H_E,50) The sum of the products, for each body organ or tissue that is irradiated, of the applicable weighting factor and the committed dose equivalent to the organ or tissue (H_E,50 = Σw_TH_T,50).

curie (Ci) The conventional unit of activity. 1 Ci equals 3.7 × 10¹⁰ disintegrations per second, which equals 3.7 × 10¹⁰ Bq.

dose or radiation dose A generic term that means absorbed dose, dose equivalent, effective dose equivalent, committed dose equivalent, committed effective dose equivalent, or total effective dose equivalent.

dose equivalent (H_T) The product of the absorbed dose in tissue, the quality factor, and all other necessary modifying factors at the location of interest. The units of dose equivalent are the rem and the sievert (Sv).

effective dose (E) The sum of weighted equivalent doses to all tissues and organs of the body (ICRP 1991). E = Σw_TH_T, where H_T is the equivalent dose and w_T is the tissue weighting factor.

effective dose equivalent (H_E) The sum of the products, for each body organ or tissue that is irradiated, of the dose equivalent to the organ or tissue and the applicable weighting factor (H_E = Σw_TH_T).

equivalent dose (H_T) In radiation protection, the absorbed dose averaged over a tissue or organ rather than a point, as is the case for dose equivalent) and weighted for the radiation quality that is of interest. For this quantity, the weighting factor is called the radiation weighting factor instead of the quality factor, as used in earlier dosimetric quantities.

external dose The dose received from radiation sources outside the body.

exposure A quantity used to express external ionizing radiation, or to indicate presence of radionuclides or radiation affecting individuals or populations (for example, “exposure” to radionuclides in the environment).

gray (Gy) The SI unit of absorbed dose. 1 Gy equals an absorbed dose of 1 J/kg (100 rad).

internal dose The dose received from radioactive material taken into the body.

limits (dose limits) The permissible upper bounds of radiation doses.

member of the public Any person except when that person is receiving an occupational dose.

quality factor (Q) The modifying factor that is used to derive dose equivalent from absorbed dose for purposes of radiation protection.

rad The special unit of absorbed dose. 1 rad equals an absorbed dose of 100 ergs per gram or 0.01 J per kg (0.01 Gy).

radiation (ionizing radiation) Alpha particles, beta particles, gamma rays, x rays, neutrons, high-energy electrons, high-energy protons, and other particles capable of producing ionization in matter. (As used in this report, radiation does not include nonionizing radiation, such as radiowaves, microwaves, visible, infrared, or ultraviolet light.)

reference man A hypothetical aggregation of human physical and physiologic characteristics arrived at by international consensus. These characteristics can be used by researchers and public-health workers to standardize results of experiments and to relate biologic insult to a common base.

relative biological effectiveness (RBE) The ratio of the absorbed dose of a reference radiation (usually 200 keV x rays) to the absorbed dose of the test radiation required to produce the same degree of biologic effect. The RBE of the test radiation depends on the exact biologic effect in a given species of organism under a given set of exposure conditions.

rem The special unit of any of the quantities expressed as dose quivalent. The dose equivalent equals the product of the absorbed dose in rads and the quality factor (1 rem = 0.01 Sv).

roentgen (R) The unit of exposure. One roentgen equals the amount of x or gamma radiation required to produce ions carrying a charge of 1 electrostatic unit (esu) per cubic centimeter (2.58 × 10^{− 4} coulomb per kg) of dry air under standard conditions.

sievert (Sv) The SI unit of any of the quantities expressed as dose equivalent. The dose equivalent in sieverts is equal to the product of the absorbed dose in grays and the quality factor (1 Sv = 100 rem).

source material As defined under the Atomic Energy Act:

(1)

Uranium, thorium, or any combination of uranium and thorium in any physical or chemical form; or

(2)

Ores that contain, by weight, 0.05% or more of uranium, thorium, or any combination thereof. Source material does not include special nuclear material.

special nuclear material As defined under the Atomic Energy Act:

(1)

Plutonium, uranium-233, uranium enriched in uranium-233 or in uranium-235, and any other material that the Nuclear Regulatory Commission, pursuant to the provisions of Section 51 of the act, determines to be special nuclear material, but not including source material; or

(2)

Any material artificially enriched by any of the foregoing, but not including source material.

Total Effective Dose Equivalent (TEDE) The sum of the deep-dose equivalent (for external exposures) and the committed effective dose equivalent (for internal exposures). It is a term used by some organizations to emphasize that the sum of the contributions from external and internal sources is meant. This term is not a part of the recommendations of the ICRP or NCRP. The term effective dose equivalent, without the modifier “total,” is sufficient to imply contributions from external and internal sources.

uranium fuel cycle The operations of milling of uranium ore, chemical conversion of uranium, isotopic enrichment of uranium, fabrication of uranium fuel, generation of electricity by a light-water-cooled nuclear power plant using uranium fuel, and reprocessing of spent uranium fuel to the extent that these activities directly support the production of electric power for public use. Does not include mining operations, operations at waste-disposal sites, transportation of radioactive material in support of these operations, and the reuse of recovered nonuranium special nuclear and byproduct materials from the cycle.

weighting factor (w_T) For an organ or tissue (T), the proportion of the risk of stochastic effects resulting from irradiation of that organ or tissue to the total risk of stochastic effects when the whole body is irradiated uniformly.

whole body For purposes of external exposure, the head, trunk (including male gonads), arms above the elbow, and legs above the knee.

working level (WL) Any combination of short-lived radon decay products in 1 L of air that will result in the ultimate emission of alpha-particle energy equal to 1.3 × 10⁵ MeV (2.08 × 10⁻⁵ J per m³). Also equals the total energy emitted by alpha particles from short-lived radon decay products in equilibrium with radon gas in air at a concentration of 100 pCi/L (3.7 kBq per m³).

LIST OF ACRONYMS

AEC

Atomic Energy Commission

ALARA

As low as reasonably achievable

AK

Alaska

ARAR

Applicable or relevant and appropriate requirement

BEIR

Biological Effects of Ionizing Radiations

BSEE

Bachelor of Science in Electrical Engineering

CEC

Commission of the European Communities

CERCLA

Comprehensive Environmental Response, Compensation, and Liability Act

CFR

Code of Federal Regulations

CRCPD

Conference of Radiation Control Program Directors

DHHS

Department of Health and Human Services

DOE

Department of Energy

EC

European Communities

EDTA

Ethylenediamine tetraacetic acid

EPA

Environmental Protection Agency

ERR

Excess relative risk

FR

Federal Register

FRC

Federal Radiation Council

FUSRAP

Formerly Utilized Sites Remedial Action Program

GAO

Government Accounting Office

HI

Hawaii

HPS

Health Physics Society

IAEA

International Atomic Energy Agency

ICRP

International Commission on Radiological Protection

ICRU

International Commission on Radiation Units and Measurements

MCL

Maximum contaminant level

MCLG

Maximum contaminant level goal

MTHM

Metric tons of heavy metal

NARM

Naturally occurring and accelerator-produced radioactive materials

NCP

National contingency plan

NCRP

National Council on Radiation Protection and Measurements

NESHAP

National Emission Standards for Hazardous Air Pollutants

NJ

New Jersey

NORM

Naturally occurring radioactive materials

NPDES

National pollutant discharge elimination system

NRC

Nuclear Regulatory Commission

NYU

New York University

OSTP

Office of Science and Technology Policy

PG

Phosphogypsum

PIC

Pressurized ionization chamber

RCRA

Resource Conservation and Recovery Act

Rn

Radon

ROD

Record of Decision

RR

Relative risk

SAB

Science Advisory Board of the Environmental Protection Agency

SFMP

Surplus Facilities Management Program

SI

Systeme International (units)

SSRCR

Suggested state regulations for the control of radiation

TBC

To be considered

TEDE

Total effective dose equivalent

TENORM

Technologically enhanced naturally occurring radioactive materials

TLD

Thermoluminescent dosimeter

TSCA

Toxic Substances Control Act

UIC

Underground injection control

UK

United Kingdom

UNSCEAR

United Nations Scientific Committee on the Effects of Atomic Radiation

UMT

Uranium mill tailings

UMTRCA

Uranium Mill Tailings Radiation Control Act

US

United States

USDW

Underground source of drinking water

US EPA

Environmental Protection Agency

WL

Working level

WLM

Working level month