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Reference Information

People and Discoveries

Commonly Encountered

Radionuclides

Americium-241

Cesium-137

Cobalt-60

Iodine-129 &-131

Plutonium

Radium

Radon

Strontium-90

Technetium-99

Tritium

Thorium

Uranium

Glossary

Acronyms

A-Z Subject Index

Site Map

Acute Exposure

a single exposure that results in biological harm or

death; usually characterized by a brief exposure

lasting no more than 7 days, as compared to

longer, continuing exposure over a period of time

Chronic Exposure

This link provides the

definition of chronic

exposure.

Radiation Health Effects

This page describes the

effects of both long-term

and acute exposure to

radiation.

A

Agreement State

a state that has signed an agreement with the Nuclear Regulatory Commission allowing the state to

regulate the use of by-product radioactive material within the state

NRC Agreement States

NRC's description of its program.

Organization of Agreement States

Organization through which Radiation control program

directors and staff from the 34 agreement states work

with each other and with the NRC on regulatory issues

associated with their agreements.

Alpha Particle

a positively charged particle made up of two neutrons and two protons emitted by certain radioactive

nuclei. Alpha particles can be stopped by thin layers of light materials, such as a sheet of paper, and

pose no direct or external radiation threat; however, they can pose a serious health threat if ingested or

inhaled.

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Alpha Particles

This fact sheet describes the basic properties, uses and

the health effects. It also discusses radiation protection

related to it.

Ambient Air

the air that surrounds us

Americium

a silvery metal; it is a man-made element whose isotopes americium-237 through -246 are all

radioactive. Americium-241 is formed spontaneously by the beta decay of plutonium-241. Trace

quantities of americium are widely used in smoke detectors, and as neutron sources in neutron moisture

gauges.

Americium

This fact sheet describes the basic properties and uses,

and the hazards associated with this radionuclide. It also

discusses radiation protection related to it.

Smoke Alarms

This page focuses mainly on the ionization chamber

technology.

Advanced Notice of Proposed Rulemaking (ANPRM)

an official notice by a government agency that it is preparing regulations on a specific topic. An ANPRM

frequently describes the approach the agency is taking in general terms, and may invite public comment.

Applicable or Relevant and Appropriate Requirement (ARAR)

Under the Comprehensive Environmental Responsibility, Cleanup and Liability Act (Superfund), cleanups

must follow two kinds of requirements:

applicable requirements meaning those that directly apply to the situation

relevant or appropriate requirements meaning those that apply to contaminants that are present at

the site or apply to a contaminated medium, such as water, at the site

For example, the standards for cleaning up uranium and thorium processing facility sites are frequently

considered "relevant and appropriate" for radiologically contaminated sites that did not conduct such

processing. ARARs can be federal, state, or local requirements.

Area

a general term referring to any portion of a site, up to and including the entire site.

Area of Elevated Activity

an area over which residual radioactivity exceeds a specified value DCGL(sub-EMC).

Atomic Mass number

the number of protons and neutrons in the nucleus of a nuclide. (The atomic mass number is not the

same as the chemical atomic weight, which is the average of all the naturally occurring isotopes of an

element weighted according to their relative abundances.)

Atomic Mass Unit (AMU)

AMU is equal to the mass of one-twelfth of a carbon-12 atom.
Weighing Atoms: Atomic Mass Units

This page explains the atomic mass units.

Atoms for Peace

President Eisenhower's 1954 initiative to allow the peaceful uses of atomic energy to be available to

other nations.

Authorities

the Presidential and legislative powers transferred to federal agencies through laws, Executive Orders,

and Presidential Decision Directives

Beneficiation

a set of processes used to reduce the particle size of mined ore to allow the desired mineral to be

separated from wastes and either used or further processed

Biological Effects of Ionizing Radiation (BEIR) Reports

reports of the National Research Council's committee on the Biological Effects of Ionizing Radiation

Becquerel (Bq)

a unit used to measure radioactivity. One Becquerel is the amount of a radioactive material that will

undergo one transformation in one second.

Often radioactivity is expressed in larger units like: thousands (Kq), or millions (MBq) of becquerels.

As a result of having one Becquerel being equal to one transformation per second, there are 3.7 x 10

10

(37 billion) Bq in one curie.

Curie

This page explains the unit curies.

Beta Particle

an electron or positron emitted by certain radioactive nuclei. Beta particles can be stopped by aluminum.

They can pose a serious direct or external radiation threat and can be lethal depending on the amount

received. They also pose a serious internal radiation threat if inhaled or ingested.

Beta Particles

This fact sheet describes the basic properties, uses and

the health effects. It also discusses radiation protection

related to it.

Binding Energy(cosmic glue)

the amount of energy required to break up a nucleus into its constituent parts, or conversely, the energy

released upon formation of the nucleus

By-Product Material

B
radioactive materials left over from the production or use of special nuclear material

the tailings or wastes produced by the extraction or concentration of uranium or thorium from any ore

processed primarily for its source material content

Regulatory definition : "(1) Any radioactive material (except special nuclear material) yielded in, or made

radioactive by, exposure incident to the process of producing or utilizing 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 these solution extraction

operations do not constitute "by-product material" within this definition (10 CFR 20.1003)."

Carcinogen

a cancer-causing substance

Radiation Health Effects

This page describes the effects of both long-term and

acute exposure to radiation.

Cerium

an iron-gray, lustrous metal. It is malleable, and oxidizes very readily at room temperature, especially in

moist air. The pure metal may ignite when scratched with a knife. Cerium-141, -143, and -144 are

radioisotopes of cerium. They emit beta particles during radioactive decay.

Cesium

a metal that may be stable (non radioactive) or unstable (radioactive). The most common radioactive

form of cesium is cesium-137. Another fairly common radioisotope is cesium-134. Cesium-137 is much

more significant as an environmental contaminant than cesium-134. It is also very useful in industry for

its strong radioactivity.

Chain Reaction

a reaction that initiates its own repetition. In a fission chain reaction, a fissionable nucleus absorbs a

neutron and fissions (splits) spontaneously, releasing additional neutrons. These, in turn, can be

absorbed by other fissionable nuclei, releasing still more neutrons. A fission chain reaction is selfsustaining when the number of neutrons released in a given time equals or exceeds the number of

neutrons lost by absorption in non-fissionable material or by escape from the system.

Characterize

to describe the characteristics of something, such as a waste or a waste site.For example, characterizing

a waste from mining or processing a naturally occurring radioactive material typically includes finding the

following types of information:

chemical and radionuclide content

level of radiation

physical description (is it liquid or solid; in big chunks or a fine powder, etc.)

amount

pH (is it an acid or a base

Chronic Exposure

exposure to a substance over a long period of time, possibly resulting in adverse health effects.

C
Exposure Pathways

This page describes the different routes by which radiation

can enter the body.

Radiation Health Effects

This page describes the effects of both long-term and

acute exposure to radiation.

Class I Survey

a type of final status survey that applies to areas with the highest potential for contamination, and meet

the following criteria: (1) impacted; (2) potential for delivering a dose above the release criterion; (3)

potential for small areas of elevated activity; and (4) insufficient evidence to support classification as

Class 2 or Class 3

Class 2 Survey

a type of final status survey survey that applies to areas that meet the following criteria: (1) impacted;

(2) low potential for delivering a dose above the release criterion; and (3) little or no potential for small

areas of elevated activity.

Class 3 Survey

a type of final status survey that applies to areas meeting the following criteria: (1) impacted; (2) little

or no potential of delivering a dose above the release criterion; and (3) little or no potential for small

areas of elevated activity.

Cobalt

a gray, hard, magnetic, ductile, and somewhat malleable metal, cobalt is relatively rare and generally

obtained as a byproduct of other metals, such as copper. Its most common radioactive isotope is cobalt60, which emits beta particles during radioactive decay.

Cobalt-60

This fact sheet describes the basic properties and uses,

and the hazards associated with this radionuclide. It also

discusses radiation protection related to it.

Compact

a group of two or more states formed to dispose of low-level radioactive waste on a regional basis. The

Low-Level Radioactive Waste Policy Act of 1980 encouraged states to form compacts to ensure

continuing low-level waste disposal capacity. As of December 2000, forty-four states have formed ten

compacts. No compact has successfully sited and constructed a disposal facility.

Conference of Radiation Control Program Directors (CRCPD)

an organization whose members represent state radiation protection programs

CRCPD

This Web site describes the activities of the organization,

provides access to their reports, and contains contact

information for the radiation control program directors in

each state.

Contamination
the deposition of unwanted radioactive material on the surfaces of structures, areas, objects, or people.

It may also be airborne, external, or internal (inside components or people).

Continuity of Operations

planning to ensure that the essential functions of an organization, such as an agency or the federal

government, can continue during a wide range of potential emergencies.

Responding to Radiological Emergencies

This Web site describes the role of EPA's Radiological

Emergency Response Team during a radiological

emergency.

Cooling Tower

a heat exchanger designed to aid in the cooling of water that was used to cool exhaust steam exiting the

turbines of a power plant. Cooling towers transfer exhaust heat into the air instead of into a body of

water.

Coordinating Agency

the agency responsible for the radiological facility or activity involved in the incident. Coordinating

agencies have primary responsibilities for federal activities related to the nuclear/radiological aspects of

the incident.

Cooperating Agency

agencies that provide support to the Coordinating Agency during the federal response to a radiological

emergency.

Criticality

a term used to describe the state of a fission reaction when the number of neutrons released by fission is

exactly balanced by the neutrons being absorbed and escaping. For example, reactor is said to be

"critical" when it achieves a self-sustaining nuclear chain reaction, as it does when the reactor is

operating.

Cumulative Dose

the total dose resulting from repeated exposures of ionizing radiation to an occupationally exposed

worker to the same portion of the body, or to the whole body, over a period of time.

Radiation Health Effects

This page describes the effects of both long-term and

acute exposure to radiation.

Curie

a measure of radioactivity based on the observed decay rate of approximately one gram of radium. The

Curie was named in honor of Pierre and Marie Curie, pioneers in the study of radiation.

One curie of radioactive material will have 37 billion atomic transformations (disintegrations) in one

second.

Curie

This page explains the unit curies.
Figures in History: Pierre and Marie Curie

This page provides information on the work and life of the

Curies.

Programs · Topics · References
Students/Teachers Librarians Reporters General Public Technical Users

PROGRAMS TOPICS REFERENCES

Reference Information

People and Discoveries

Commonly Encountered

Radionuclides

Americium-241

Cesium-137

Cobalt-60

Iodine-129 &-131

Plutonium

Radium

Radon

Strontium-90

Technetium-99

Tritium

Thorium

Uranium

Glossary

Acronyms

A-Z Subject Index

Site Map

Decay, Radioactive

the decrease in the amount of any radioactive

isotope with the passage of time due to the

spontaneous emission of radiation from the atomic

nuclei (either alpha or beta particles, often

accompanied by gamma radiation), and consequent

transformation to a different chemical form.

Why Are Some Atoms

Radioactive?

This page explains

radioactive atoms.

Decay Chains

This page explains decay

chains.

D

Decay Chain

the series of decays that certain radioisotopes go through before reaching a stable form. For example,

the decay chain that begins with Uranium-238 culminates in Lead-206, after forming intermediates such

as Uranium-234, Thorium-230, Radium-226, and Radon-222. Also called the "decay series."

Decay Chains

This page explains decay chains.

Decay Products

the isotopes or elements that form and the particles and high-energy electromagnetic radiation emitted

by the nuclei of radionuclides during radioactive decay. Also known as "decay chain products," "daughter

products," or "progeny" (the isotopes and elements).

Decommission

the process of removing a nuclear facility from service by reducing residual radioactivity in buildings or at

the site to a level that permits the release of the property for unrestricted use or maintenance under

protection for reasons of public health and safety. (see also, decontamination)

E

F

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Decontamination

the reduction or removal of contaminated radioactive material from a structure, object or person. (See

also decommission)

Depleted Uranium

uranium containing less 0.7% uranium-235, the amount found natural uranium (See also enriched

uranium.)

Uranium

This fact sheet describes the basic properties and uses,

and the hazards associated with this radionuclide. It also

discusses radiation protection related to it.

Dewatered

to have reduced the water content of recently produced wastes or other materials either mechanically or

by evaporation. For example, dewatering reduces the water in tailings to 30% by weight or less.

Dirty Bomb

commonly refers to a device that spreads radioactive material by exploding a conventional (non-nuclear)

explosive, such as dynamite. Because they do not involve the sophisticated technology required to create

a nuclear explosion, dirty bombs are much simpler to make than a true nuclear bomb.

Docket

a publicly accessible collection of documents that Federal agencies use in making regulatory decisions

Dose (radiation)

denotes the quantity of radiation or energy absorbed. Dose may refer to the following:

--absorbed dose, the amount of energy deposited per unit mass

--equivalent dose, the absorbed dose adjusted for the relative biological effect of the type of radiation

being measured

--committed dose, a dose that accounts for continuing exposures over long periods of time (such as 30,

50, or 70 years)

Radiation Health Effects

This page describes the effects of both long-term and

acute exposure to radiation.

Radiation Protection Basics

This page provides three Basic Concepts of Radiation

Protection.

Dose Rate

the radiation dose delivered per unit time

Dosimeter

a small portable instrument (such as a film badge, thermoluminescent, or pocket dosimeter) for

measuring and recording the total accumulated personal dose of ionizing radiation

--dosimetry, monitoring of individuals to accurately determine their radiation dose equivalent
Ecological Atlas

a series of maps that describe each aspect of an area's ecosystem. For example, one map in the series

would describe the biology (plant and wildlife); another would describe the geology; and so forth.

Electron

What is an Atom?

This page describes and explains atoms.

Emergency Removal action

steps taken to remove contaminated materials that pose an imminent threat to local residents (e.g.,

removal of leaking drums or the excavation of explosive waste).

Emergency Support Functions (ESF)

ESFs detail the missions, policies, structures, and responsibilities of federal agencies for coordinating

resource and programmatic support to states, tribes, and other federal agencies or other jurisdictions

and entities during Incidents of National Significance. The introduction to the ESF Annexes summarizes

the functions of ESF coordinators and primary and support agencies.

Environmental Radiation Ambient Monitoring System (ERAMS)

now known as RadNet, is a nationwide system of air, water, and milk sampling stations that monitor

radiation in the environment

RadNet

This page provides information about different RadNet

sampling programs.

End Products

the materials that leave the treatment facility or are disposed of onsite after all processing is completed

(e.g., ash from incineration, digested liquid or dewatered cake, dried pellets, compost).

Enriched Uranium

uranium in which the proportion of the isotope uranium-235 has been increased(See also depleted

uranium.)

Uranium

This fact sheet describes the basic properties and uses,

and the hazards associated with this radionuclide. It also

discusses radiation protection related to it.

Entomb

a method of decommissioning a nuclear facility in which radioactive contaminants are encased in longlived material, such as concrete. The entombment structure is maintained and monitored until the

radioactivity decays to a level allowing decommissioning and ultimately, safe unrestricted use of the

property.

Epidemiological Studies
studies of the distribution of disease and other health issues as related to age, sex, race, ethnicity,

occupation, economic status, or other factors

Radiation Health Effects

This page describes the effects of both long-term and

acute exposure to radiation.

Exposure(radiation)

a term relating to the amount of ionizing radiation that strikes a living or inanimate material. (This is a

general definition. In health physics, exposure is specifically defined as a measure of ionization in air

caused by x-ray or gamma radiation only.)

Exposure Pathways

This page describes the different routes by which radiation

can enter the body.

Fallout, nuclear

the slow descent of minute particles of radioactive debris in the atmosphere following a nuclear

explosion.

Federal Facilities Compliance Act (FFCA or FFCAct)

an amendment to RCRA, which requires DOE and other federal agencies, to follow RCRA regulations, and

requires DOE to develop plans for treating the hazardous components of radioactive wastes subject to

RCRA requirements.

Field Exercise (FX)

also known as "full scale exercise"; an emergency response training exercise that tests a major portion of

the functions in an emergency plan and/or operating procedures. Field exercises incorporate a high

degree of realism and an extensive involvement of resources and personnel. (See also table top

exercise.)

Exercises

This page provides information on exercises that range

from informal "walk through's" to highly complex, realistic

simulations of actual emergencies. It also provides

examples of the exercises in which EPA's Radiological

Emergency Response Team has participated.

Final Status Survey

measurements and sampling to describe the radiological conditions of a site, following completion of

decontamination activities (if any) in preparation for release.

Fissile Material

although sometimes used as a synonym for fissionable material, this term has acquired a more restricted

meaning. Namely, any material fissionable by thermal (slow) neutrons. The three primary fissile

materials are uranium-233, uranium-235, and plutonium-239.

Fission (fissioning)

the splitting of a nucleus into at least two other nuclei and the release of a relatively large amount of
energy. Two or three neutrons are usually released during this type of transformation. Fissioning is also

referred to as 'burning.' (See also fusion.)

Fissioning that occurs without any outside cause, such as bombardment with a neutron, is called

'spontaneous fission.'

Fuel Cycle

the series of steps involved in supplying fuel for nuclear power reactors. The fuel cycle can include

mining, milling, isotopic enrichment, fabrication of fuel elements, use in a reactor, re-enrichment of the

fuel material, re-fabrication into new fuel elements, and waste disposal.

Fuel Rod

a long, slender tube that holds fissionable material (fuel) for nuclear reactor use. Fuel rods are

assembled into bundles called fuel elements or fuel assemblies, which are loaded individually into the

reactor core.

Fusion

a reaction in which at least one heavier, more stable nucleus is produced from two lighter, less stable

nuclei. Reactions of this type are responsible for enormous release of energy, as in the energy of stars,

for example. (See also fission.)

Programs · Topics · References
Students/Teachers Librarians Reporters General Public Technical Users

PROGRAMS TOPICS REFERENCES

Reference Information

People and Discoveries

Commonly Encountered

Radionuclides

Americium-241

Cesium-137

Cobalt-60

Iodine-129 &-131

Plutonium

Radium

Radon

Strontium-90

Technetium-99

Tritium

Thorium

Uranium

Glossary

Acronyms

A-Z Subject Index

Site Map

Gamma Rays

high-energy electromagnetic radiation emitted by

certain radionuclides when their nuclei transition

from a higher to a lower energy state. These rays

have high energy and a short wave length. All

gamma rays emitted from a given isotope have the

same energy, a characteristic that enables

scientists to identify which gamma emitters are

present in a sample. Gamma rays are very similar

to x-rays.

Gamma Rays

This fact sheet describes

the basic properties, uses

and the health effects. It

also discusses radiation

protection related to it.

G

Geiger Counter

A radiation detection and measuring instrument. It consists of a gas-filled tube containing electrodes,

between which there is an electrical voltage, but no current flowing. When ionizing radiation passes

through the tube, a short, intense pulse of current passes from the negative electrode to the positive

electrode and is measured or counted. The number of pulses per second measures the intensity of the

radiation field. It is the most commonly used portable radiation detection instrument.

Generally Applicable Standards

Standards that apply to general categories of conditions or sites, rather than any specific situation.&

Under the Atomic Energy Act of 1954, EPA has authority to establish "generally&applicable environmental

standards for the protection of the general environment from radioactive material."

Genetic Effects

hereditary effects that can be passed on through reproduction due to changes in sperm or ova.

H

I

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Radiation Health Effects

This page describes the effects of both long-term and

acute exposure to radiation.

Geographical Information System(GIS)

a system for linking information to a particular geographical location. GISs are generally capable of

producing maps that show the location of the information. For example, a GIS containing TENORM

information might contain the name and number of acres at a TENORM site as well as information about

its longitude and latitude. A map printed from this system would show locations and sizes of TENORM

sites on a map of the United States.

Guidance

specific, suggested procedures and best practices that are similar to regulations but not legally

enforceable.

Gray (gy)

a unit of measurement for absorbed dose. It relates to the amount of energy actually absorbed in a

material, and is used for any type of radiation and any material. One gray is equal to one joule of energy

deposited in one kg of a material. The unit gray can be used for any type of radiation, but it does not

describe the biological effects of the different radiations. Absorbed dose is often expressed in terms of

hundredths of a gray, or centi-grays. One gray is equivalent to 100 rads.

Half-life

the time in which one half of the atoms of a radioactive isotope disintegrates into another nuclear form.

Half-lives vary from billionths of a billionth of a second to billions of years. Also called physical or

radiological half-life.

biological half-life the time an organism takes to eliminate one half the amount of a compound or

chemical on a strictly biological basis

effective half life incorporates both the radioactive and biological half-lives. It is used in calculating

the dose received from an internal radiation source.

Half-Life

This page describes and explains half-life.

Hazardous Waste

waste products that can pose a substantial or potential hazard to human health or the environment when

improperly managed. Hazardous waste is regulated at the federal level under the Resource Conservation

and Recovery Act. A waste may be hazardous because it has at least one of four characteristics -

ignitability, corrosivity, reactivity, or toxicity may be included on one of several lists of waste groups that

are known to be hazardous.

Hazardous and Solid Waste Amendments (HWSA)

1984 Act which amended RCRA to prohibit land disposal of untreated hazardous waste. It also increased

enforcement authority for EPA and established a program requiring corrective action.

Health Physics

a scientific field that focuses on radiation protection of humans and the environment. Health Physics uses

physics, biology, chemistry, statistics and electronic instrumentation to help protect individuals from any

damaging effects of radiation.
Health Physics Society:Public and Media Information

This Web site describes the activities of the organization,

provides access to their ask the experts (radiation safety),

fact sheets and a list of radiation definitions.

Careers in Radiation: Health Physicist

This link provides a description and explains the origin of

health physicist.

High-Level Radioactive Waste

the highly radioactive material resulting spent nuclear fuel reprocessing:

liquid waste directly produced in reprocessing

any solid material derived from the liquid wastes having a sufficient concentration of fission products.

Other highly radioactive materials can be designated as high-level waste, if they require permanent

isolation. This determination is made by the U.S. Nuclear Regulatory Commission based criteria established

in U.S. law.

Hormesis

the theory that low levels of radiation are beneficial to health

In-situ Leaching

extracting metals or other minerals from ore by allowing an acid-containing liquid to flow through the

ground that contains the minerals. The minerals are dissolved by the acid (leached) and captured when

the liquid is collected. Leaching is also used to recover minerals from waste rock that contains too low a

concentration of the mineral to be worth recovering by typical extraction (mining and processing)

methods.

incineration

high temperature combustion of materials in an enclosed device.

incinerator ash

ash from the incineration of waste.

in growth

in a sample, the buildup of radionuclides that are products of radioactive decay.

internal conversion

transmission of the excess energy of the nucleus to one of the orbital electrons; the electron may be

ejected from the atom (ionizing radiation).

Other Modes of Radioactive Decay: Isomeric Transition

This link describes and explains Isomeric Transition.

Iodine

a nonmetallic solid element. There are both radioactive and non-radioactive isotopes of iodine

Iodine

This fact sheet describes the basic properties and uses,

and the hazards associated with this radionuclide. It also

discusses radiation protection related to it.

Ion
(1) an atom or molecule that has too many or too few electrons, causing it to have an electrical charge,

and therefore, be chemically active (2) an electron that is not associated (in orbit) with a nucleus

Ionization

the process of adding one or more electrons to, or removing one or more electrons from, atoms or

molecules, thereby creating ions. High temperatures, electrical discharges, or nuclear radiation can cause

ionization.

Why Are Some Atoms Radioactive?

This page explains radioactive atoms.

Ionizing Radiation

any radiation capable of displacing electrons from atoms or molecules, thereby producing ions. Some

examples are alpha, beta, gamma, and X-rays. High doses of ionizing radiation may produce severe skin

or tissue damage.

Ionizing and Non-Ionizing Radiation

This page explains ionizing and non-ionizing radiation.

Irradiation

exposure to radiation.

Food Irradiation

This page describes and explains food irradiation.

Isomer (isomeric transition)

A nuclide having the same number of protons and neutrons but a different energy. One isomer is usually

less stable and (relatively) quickly transitions to the more stable form, releasing some energy in the

process.

Other Modes of Radioactive Decay: Isomeric Transition

This link provides information on Neutron Radiation,

Positron Decay, Electron Capture and Isomeric Transition.

Isotope

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

Nuclides and Isotopes

This page describes the distinctions between nuclides and

isotopes.

Programs · Topics · References
Students/Teachers Librarians Reporters General Public Technical Users

PROGRAMS TOPICS REFERENCES

Reference Information

People and Discoveries

Commonly Encountered

Radionuclides

Americium-241

Cesium-137

Cobalt-60

Iodine-129 &-131

Plutonium

Radium

Radon

Strontium-90

Technetium-99

Tritium

Thorium

Uranium

Glossary

Acronyms

A-Z Subject Index

Site Map

Karst

a type of topography in which there are numerous

sinkholes and large voids, such as caves. Karst is

caused when soluble rocks dissolve. Karst may

form when rainwater, reacting with carbon dioxide

from the air and forming carbonic acid, seeps

through the soil into the rock. Soluble rock includes

limestone and evaporite rocks, such as halite (salt)

and gypsum.

If substantial and abundant karst features were

present at the Waste Isolation Pilot Project, this

could increase the speed at which releases of

radionuclides travel away from the repository

through the subsurface.

Evaluation of KARST at

the WIPP Site (PDF) (127

pp, 7.29MB)

Assessment of the

Potential for Karst

in the Rustler Formation

at the WIPP Site

JK

Land Application

application of sewage sludge or other waste product to land to condition the soil or fertilize crops or other

vegetation.

Land Disposal Restrictions

restrictions mandated by the 1984 HSWA amendments to RCRA, which prohibit the disposal of hazardous

wastes into or on the land unless the waste meets treat ability standards of lower toxicity.

Lead-210

L

M

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An unstable form of lead in the uranium-238 decay chain, lead-210 is a significant source of beta

radiation.

Linear Energy Transfer (LET)

measures the rate of energy deposited per unit of distance a particle penetrates matter (for example,

tissue). The higher the LET, the more ionizing the radiation. As a result, interactions with tissue

(ionizations that damage the tissue) are more densely clustered.

Linear No Threshold Hypothesis

The theory that the number of cancers and some other effects of exposure to low levels of radiation are

proportionate to the number of cancers from exposure to higher levels of radiation. By extension, there is

no level of exposure that carries no risk of health effect, no matter how small the risk or exposure (no

"threshold" exposure). The precise effects are uncertain because it is very difficult to measure the effects

of low levels of radiation.

Liquid Scintillation Cocktail (LSC)

a common fluid used in medical laboratories to analyze DNA and proteins. It often uses radioactive

tracers and RCRA listed hazardous materials such as toluene and xylene. The combination of the two

make it a mixed waste. By volume it is the most common form of commercially generated (non-DOE)

mixed waste (71% in a 1990 national study).

Low-Activity Radioactive Waste

waste containing very low concentrations of radioactive material

Low-Level Mixed Waste (LLMW)

LLMW is waste that contains LLRW and hazardous waste.

Low-Level Radioactive Waste

radioactively contaminated industrial or research waste such as paper, rags, plastic bags, watertreatment residues. It is waste that does not meet the criteria for any of three other categories of

radioactive waste: spent nuclear fuel and high-level radioactive waste; transuranic radioactive waste; or

uranium mill tailings. Its categorization does not depend the level of radioactivity it contains.

Manhattan Project

the national program to develop the first atomic weapons during World War II

Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM)

a cooperative effort among EPA, the Nuclear Regulatory Commission, Department of Energy, and

Department of Defense; MARSSIM describes appropriate methods to design surveys to assess radioactive

contamination at sites.

MARSSIM

This Web site provides information on training, obtaining a

copy of MARSSIM, tools for implementing MARSSIM and

upcoming meeting information.

Maximum Contaminant Level (MCL)

the amount of a contaminant that may be present in drinking water under the Safe Drinking Water Act.

MCLs are the standards that drinking water treatment systems must meet.
Maximum Contaminant Level Goal (MCLG)

the risk-based level of a contaminant that may be present drinking water. under the Safe Drinking Water

Act. The MCLG for carcinogens is zero. The MCL may be higher than the MCLG because of the technical

or economic feasibility of meeting the MCLG.

Micro

symbol: μ, one millionth of a unit. For example a microgram ( μg ) is one millionth of a gram.

Micron

one millionth of a meter

Mills

industrial operations that process ores to extract desired minerals.

Mixed Waste

waste which contains both hazardous waste (as defined by RCRA and its amendments) and radioactive

waste (as defined by AEA and its amendments). It is jointly regulated by NRC or NRC's Agreement States

and EPA or EPA's RCRA Authorized States. The fundamental and most comprehensive statutory definition

is found in the Federal Facilities Compliance Act (FFCA) where Section 1004(41) was added to RCRA:

"The term 'mixed waste' means waste that contains both hazardous waste and source, special nuclear, or

by-product material subject to the Atomic Energy Act of 1954."

Mixed Transuranic Waste

waste which contains both hazardous waste (as defined by RCRA and its amendments) and transuranic

waste

Model (mathematical model)

a physical or mathematical representation of a natural system (reality) intended to mimic the behavior of

the real system, allowing description of data and predictions about the system.

Molecule

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.

Monitoring

the use of sampling and detection equipment to determine the levels of radiation or other toxic materials

in land, air, or water.

National Environmental Monitoring

This page provides information about different RadNet

sampling programs.

Monofill

landfills where only sewage sludge is disposed. Monofills include trenches and area fills.

Memorandum of Understanding (MOU)

an agreement between two (or more) parties, such as two Federal agencies, that describes how

responsibilities will be shared for a particular situation. For example, EPA has an MOU with DOE to share
information related to treatment of mixed waste.

mrem

millirem, one thousandth of a rem

Municipal Landfill

landfill that receives household waste, and that is not a land application unit, surface impoundment,

injection well, or waste pile. Such a landfill may be publicly or privately owned.

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Reference Information

People and Discoveries

Commonly Encountered

Radionuclides

Americium-241

Cesium-137

Cobalt-60

Iodine-129 &-131

Plutonium

Radium

Radon

Strontium-90

Technetium-99

Tritium

Thorium

Uranium

Glossary

Acronyms

A-Z Subject Index

Site Map

National Priorities List (NPL)

EPA's official list of sites that present sufficient

threat to human health or the environment to be

eligible for cleanup under the Superfund program.

Sites make the NPL if they score above 28.5 on the

Hazard Ranking System, which evaluates levels of

contamination and the potential for exposure to

humans and ecosystems.

Naturally Occurring Radioactive Materials

(NORM)

Radioactive materials that are found in nature.

Until recently, technologically enhanced naturally

occurring radioactive materials (TENORM) was

referred to simply as NORM. The words

"technologically enhanced" were added to

distinguish clearly between radionuclides as they

occur naturally and radionuclides that human

activity has concentrated or exposed to the

environment.

N

Naturally Occurring Radioactive Materials or Accelerator-Produced Radioactive Materials

(NARM)

Radioactive materials not covered under the AEA that are naturally occurring or produced by an

accelerator. Accelerators are used in sub-atomic particle physics research. These materials have been

traditionally regulated by States. A subset of NARM is NORM. NARM waste with more than 2 nCi/g of

226Ra or equivalent is commonly referred to as discrete NARM waste; below this threshold, the waste is

referred to as diffuse NARM waste. NARM waste is not covered under the AEA, not a form of LLW, and is

not regulated by NRC.

Neutrino

An unreactive particle that accompanies a beta particle. It has no charge and virtually no mass.

Radioactive Decay (Minor Modes)

This link provides information on Neutron Radiation,

O

P

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Positron Decay, Electron Capture and Isomeric Transition.

Neutron

a small particle possessing no electrical charge typically found within an atom's nucleus. A neutron has

about the same mass as a proton.

What is an Atom?

This page describes and explains atoms.

Neutron Poison

in reactor physics, a material other than fissionable material, in the vicinity of the reactor core that will

absorb neutrons. The addition of poisons, such as control rods or boron, into the reactor is said to be an

addition of negative reactivity.

Neutron Radiation

Neutron radiation is energy released from an atom in the form of neutral particles called neutrons.

Neutrons are part of the basic building blocks of atoms. They have no charge and are about the same

mass as a proton. Due to ion-producing collisions with matter and absorption/decay processes, neutrons

are a type of ionizing radiation.

Non-Ionizing Radiation

Radiation that has lower energy levels and longer wavelengths than ionizing radiation. It is not strong

enough to affect the structure of atoms it contacts, but is strong enough to heat tissue and can cause

harmful biological effects. Examples include radio waves, microwaves, visible light, and infrared from a

heat lamp.

Ionizing and Non-Ionizing Radiation

This page explains ionizing and non-ionizing radiation.

Non-Stochastic Effect

Effects that can be related directly to the dose received. The effect is more severe with a higher does,

i.e., the burn gets worse as dose increases. It typically has a threshold, below which the effect will not

occur. A skin burn from radiation is a non-stochastic effect. (See also stochastic effects.)

Radiation Health Effects

This page describes the effects of both long-term and

acute exposure to radiation.

Not In My Backyard (NIMBY)

Usually used to describe members of the public who are not opposed to an activity in principle (e.g.,

nuclear power or waste disposal), but do not want it located near their community.

Nuclear Energy

The heat energy produced by the process of nuclear reaction (fission or fusion) within a nuclear reactor

or by radioactive decay.

Nuclear Fuel Cycle
The series of steps involved in supplying fuel for nuclear power reactors. It can include mining, milling,

isotopic enrichment, fabrication of fuel elements, use in reactors, chemical reprocessing to recover the

fissionable material remaining in the spent fuel, re enrichment of the fuel material refabrication into new

fuel elements and waste disposal.

Nuclear Power Plant

An electrical generating facility using a nuclear reactor as its power (heat) source. The coolant that

removes heat from the reactor core is normally used to boil water. The steam produced by the boiling

water drives turbines that rotate electrical generators.

Nuclear Regulatory Commission

NRC is an independent regulatory agency created out of the Atomic Energy Commission in 1975 to

regulate the civilian uses of nuclear material. It has five Commissioners, who are nominated by the

President and confirmed by the Senate; the President designates one of the Commissioners as Chairman.

The NRC is responsible for ensuring that a civilian nuclear activities are carried out with adequate

protection of the public health and safety, the environment, and national security:operation of nuclear

power and fuel cycle plants nuclear medicine industrial use of radioactive materials use of radioactive

materials in research regulation of all AEA materials. Except in a few cases, NRC does not regulate the

Department of Energy's radioactive materials. NRC does not regulate NARM. You can learn more about

NRC at http://www.nrc.gov.

Nuclear Tracers

Radioisotopes that give doctors the ability to "look" inside the body and observe soft tissues and organs,

in a manner similar to the way X-rays provide images of bones. A radioactive tracer is chemically

attached to a compound that will concentrate naturally in an organ or tissue so that a picture can be

taken.

Nucleon

a proton or a neutron; a constituent of the nucleus

Nucleus

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

atom.

What is an Atom?

This page describes and explains atoms.

Nuclide

a general term applicable to all atomic forms of an element. Nuclides are characterized by the number of

protons and neutrons in the nucleus, as well as by the amount of energy contained within the atom.

What is an Atom?

This page describes and explains atoms.

Nuclides and Isotopes

This page describes the distinctions between nuclides and

isotopes

Order of Magnitude

a multiple of ten. For example, "two numbers differ by one order of magnitude" means one is about ten

times larger than the other. If they differ by two orders of magnitude, one is about 100 times larger than
the other.

Overburden

soil and rock that is covering a deposit of ore, such as uranium. Overburden is removed during mining

operations and generally stored in piles near the mine. It usually contains at least trace amounts of the

ore plus radioactive decay products.

Oxide

a compound formed by the reaction of oxygen with another element. For example, rust ferrous oxide is

iron that has combined with oxygen.

Pathways

the way in which people are exposed to radiation or other contaminants. The three basic pathways are

inhalation (contaminants are taken into the lungs), ingestion (contaminants are swallowed), and direct

(external) exposure (contaminants cause damage from outside the body).

Exposure Pathways

This page describes the different routes by which radiation

can enter the body.

Palladium

a steel-white metal, does not tarnish in air, and is the least dense and lowest melting of the platinum

group metals. When annealed, it is soft and ductile. Cold working increases its strength and hardness. It

is used in some watch springs.

At room temperatures the metal has the unusual property of absorbing up to 900 times its own volume

of hydrogen. Hydrogen readily diffuses through heated palladium and this provides a means of purifying

the gas.

Phased Disposal

a method of tailings management and disposal that uses lined impoundments, which are filled and then

immediately dried and covered to meet all applicable federal standards.

Phosphor

a substance that emits light when excited by radiation

Photon

a discrete "packet" of pure electromagnetic energy. Photons have no mass and travel at the speed of

light. The term "photon" was developed to describe energy when it acts like a particle (causing

interactions at the molecular or atomic level), rather than a wave. Gamma and X-rays are photons.

Gamma Rays

A a description of the properties, uses and health effects

of gamma and x-rays.

picocurie

ne one-trillionth (1/1,000,000,000,000) of a curie.
Curies

This page describes and explains the origin of the unit,

curie.

Pitchblende

a brown to black mineral that has a distinctive luster. It consists mainly of urananite (UO2), but also

contains radium. It is the main source of uranium ore.

Plume

Material spreading from a particular source and traveling through environmental media, such as air or

ground water. For example, a plume could describe the dispersal of particles, gases, vapors and aerosols

in the atmosphere, or the movement of contamination through an aquifer (dilution, mixing, adsorption

onto soil, etc.).

Plutonium

a heavy, man-made, radioactive metallic element. The most important isotope is Pu-239, which has a

half-life of more than 20,000 years; it can be used in reactor fuel and is the primary isotope in weapons.

One kilogram is equivalent to about 22 million kilowatt-hours of heat energy. The complete detonation of

a kilogram of plutonium produces an explosion equal to about 20,000 tons of chemical explosive.

Plutonium is a bone-seeking radiation hazard, and can be lethal depending on the dose and exposure

time.

Plutonium

This fact sheet describes the basic properties and uses,

and the hazards associated with this radionuclide. It also

discusses radiation protection related to it.

Polonium

a radioactive chemical element and a product of radium decay. Polonium is found in uranium ores.

Positron

a particle equal in mass to the electron but having a positive electronic charge.

Radioactive Decay (Minor Modes)

This link provides information on Neutron Radiation,

Positron Decay, Electron Capture and Isomeric Transition.

Power

(1- )

the probability of rejecting the null hypothesis when it is false. The power is equal to one minus the Type

II decision error rate, i.e. (1- ).

Power Reactor

a reactor designed to produce heat for electric generation, as distinguished from reactors used for

research, for producing radiation or fissionable materials or for reactor component testing.

Protective Action Guide

A protective action guide 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.
Protective Action Guides (PAGs)

This page provides information on when and how PAGs are

used during a radiation emergency, available training and

how to obtain a copy.

Proton

a small particle, typically found within an atom's nucleus, that possesses a positive electrical charge. The

number of protons is unique for each chemical element.

What is an Atom?

This page describes and explains atoms.

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Reference Information

People and Discoveries

Commonly Encountered

Radionuclides

Americium-241

Cesium-137

Cobalt-60

Iodine-129 &-131

Plutonium

Radium

Radon

Strontium-90

Technetium-99

Tritium

Thorium

Uranium

Glossary

Acronyms

A-Z Subject Index

Site Map

Qualitative Risk Assessment

a broad general analysis to determine whether a

more extensive analysis is necessary. It essentially

answers the question " safe or unsafe". (See also

quantitative risk assessment)

Quality Factor (Q)

The factor by which the absorbed dose (rad) is

multiplied to obtain a quantity that expresses, on a

common scale for all ionizing radiation, the

biological damage (rem) to an exposed individual.

It is used because some types of radiation, such as

alpha particles, are more biologically damaging

internally than other types.

Q

Quantitative Risk Assessment

a detailed analysis that provides a numerical probability that a particular kind of injury will occur (for

example, the number of additional cases of cancer in a group of 10,000).(See also qualitative risk

assessment

PROGRAMS TOPICS REFERENCES

Rad

(See Roentgen Absorbed Dose)

Radiation (ionizing)

energy given off as either particles or rays from the unstable nucleus of an atom

Why Are Some Atoms Radioactive?

This page explains radioactive atoms.

Can Unstable Atoms Become Stable?

This link explains unstable atoms.

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Radiation Protection Guide (RPG)

radiation dose which should not be exceeded without careful consideration for doing so; every effort

should be made to encourage the maintenance of radiation doses as far below this guide as practicable

Radiation Sickness (syndrome)

the set of symptoms that results when the whole body (or a large part of it) has received an exposure of

greater than 50 rads of ionizing radiation. The earliest symptoms are nausea, fatigue, vomiting, and

diarrhea. Hair loss, hemorrhaging, inflammation of the mouth and throat, and general loss of energy may

follow. If the exposure has been approximately 1,000 rad or more, death may occur within two to four

weeks.

Radiation Health Effects

This page describes the effects of both long-term and

acute exposure to radiation.

Radiation Warning Symbol

an officially prescribed symbol (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.

Symbols in Radiation Protection

This page provides definitions and images of radiation

symbols.

Radioactive Contamination

a deposit of radioactive material in any place where it may harm persons, equipment, or the

environment.

Radioactive Decay

The process in which an unstable (radioactive) nucleus emits radiation and changes to a more stable

isotope or element. A number of different particles can be emitted by decay. The most typical are alpha

or beta particles.

Can Unstable Atoms Become Stable?

This link explains unstable atoms.

Radioactivity

spontaneous transformation of the nucleus of an atom; this resulting in a new element, generally with

the emission of alpha or beta particles often accompanied by gamma rays

Radioassay

a test to detect and determine the amount of radioactive materials present that emit ionizing radiation. It

will detect transuranic nuclides, uranium, fission and activation products, naturally occurring radioactive

material and medical isotopes.

Radiogenic

caused by exposure to ionizing radiation
Ionizing and Non-ionizing Radiation

This page explains ionizing and non-ionizing radiation.

Radiological Dispersion Device (RDD)

a device or mechanism that is intended to spread radioactive material from the detonation of

conventional explosives or other means. An RDD is commonly known as a "dirty bomb."

Radiography

using radiation sources to "photograph" internal structures, such as turbine blades in jet engines. A

sealed radiation source, usually iridium-192 or cobalt-60, beams gamma rays at the object to be

checked. Gamma rays passing through flaws in the metal or incomplete welds strike special photographic

film (radiographic film) on the opposite side. The process is very similar to taking an x-ray to check for

broken bones.

Radioisotope

isotopes of an element that have an unstable nucleus. Radioactive isotopes are commonly used in

science, industry, and medicine. The nucleus eventually reaches a more stable number of protons and

neutrons through one or more radioactive decays. Approximately 3,700 natural and artificial

radioisotopes have been identified.

What is an Atom?

This page describes and explains atoms.

Nuclides & Isotopes

This page describes the distinctions between nuclides and

isotopes.

Radionuclides

This page provides a list of fact sheets on commonly

encountered radionuclides.

Radionuclide

an unstable form of a nuclide

Nuclides & Isotopes

This page describes the distinctions between nuclides and

isotopes

Radionuclides

This page provides a list of fact sheets on commonly

encountered radionuclides.

Radium

Radium is a naturally-occurring radioactive metal. Radium is a radionuclide formed by the decay of

uranium and thorium in the environment. It occurs at low levels in virtually all rock, soil, water, plants,

and animals. Radon is a decay product of radium.

Radium

This fact sheet describes the basic properties and uses,

and the hazards associated with this radionuclide. It also

discusses radiation protection related to it.

RadNet
a nationwide system of air, water, and milk sampling stations that monitor radiation in the environment

RadNet

This page provides information about different RadNet

sampling programs.

Radon

Radon is a naturally occurring radioactive gas found in soils, rock, and water throughout the U.S. Radon

causes lung cancer, and is a threat to health because it tends to collect in homes, sometimes to very

high concentrations. As a result, radon is the largest source of exposure to naturally occurring radiation.

Resource Conservation and Recovery Act

RCRA gives EPA the authority to control hazardous waste from cradle-to-grave. This includes the

minimization, generation, transportation, treatment, storage, and disposal of hazardous waste. RCRA

also sets forth a framework for the management of non-hazardous solid wastes. RCRA focuses only on

active and future facilities and does not address abandoned or historical sites, which are regulated under

the Comprehensive Environmental Restoration, Cleanup, and Liability Act (CERCLA)

Release Criterion

a regulatory limit expressed in terms of dose or risk.

Residual Radioactivity

radioactivity in structures, materials, soils, groundwater, and other media at a site resulting from

activities under the cognizant organization's control. This includes radioactivity from all sources used by

the cognizant organization, but excludes background radioactivity as specified by the applicable

regulation or standard. It also includes radioactive materials remaining at the site as a result of routine

or accidental releases of radioactive material at the site and previous burials at the site, even if those

burials were made in accordance with the provisions of 10 CFR Part 20.

Risk

the probability of injury, disease, or death under specific circumstances. Risk can be expressed as a

value that ranges from zero (no injury or harm will occur) to one hundred percent (harm or injury will

definitely occur). Risk-based standards limit the risk that releasing a contaminant to the environment

may pose rather than limiting the quantity that may be released.

absolute risk, the excess risk attributed to irradiation and usually expressed as the numeric difference

between irradiated and non-irradiated populations (e.g., 1 case of cancer per million people irradiated

annually for each rad). Absolute risk may be given on an annual basis or lifetime basis.

relative risk, the ratio between the number of cancer cases in the irradiated population to the number of

cases expected in the unexposed population. A relative risk of 1.1 indicates a 10 percent increase in

cancer due to radiation, compared to the "normal" incidence.

Risk Assessment

an evaluation of the risk to human health or the environment by hazards. Risk assessments may look at

either existing hazards or potential hazards. The assessment may be quantitative or qualitative.

Roentgen (R)

a unit of exposure to ionizing radiation. It is an indication of the strength of the ionizing radiation. 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.

Roentgen Absorbed Dose (rad)
a basic unit of absorbed radiation dose. It is being replaced by the 'gray,' which is equivalent to 100 rad.

One rad equals the dose delivered to an object of 100 ergs of energy, per gram of material.

Roentgen Equivalent Man (rem)

a unit of equivalent dose. Rem relates the absorbed dose in human tissue to the effective biological

damage of the radiation. Not all radiation has the same biological effect, even for the same amount of

absorbed dose.

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Students/Teachers Librarians Reporters General Public Technical Users

Reference Information

People and Discoveries

Commonly Encountered

Radionuclides

Americium-241

Cesium-137

Cobalt-60

Iodine-129 &-131

Plutonium

Radium

Radon

Strontium-90

Technetium-99

Tritium

Thorium

Uranium

Glossary

Acronyms

A-Z Subject Index

Site Map

Safe Secure Trailer

a specially designed trailer for transporting nuclear

materials. As its name implies, it is built for

security and to withstand severe impacts.

Sensitivity Analysis

an important part of mathematical modeling,

sensitivity is a measure of the change in the final

result compared to the change in an input

parameter. If a small input change generates a

large output change, the parameter is sensitive (or

the model is sensitive to that parameter). A

sensitivity analysis helps the modeler to bound the

model results and identify which uncertainties are

most important.

S

Sewage

solid, semi-solid, or liquid residue generated during the treatment of domestic sewage in a treatment

works. It includes, but is not limited to: domestic septage; scum or solids removed in primary,

secondary, or advanced wastewater treatment processes; and material derived from sewage sludge. It

does not include ash generated during the incineration of sewage sludge or grit and screenings generated

during preliminary treatment of domestic sewage in a treatment works.

Joint NRC/EPA Sewage Sludge Radiological Survey:

Survey Design and Test Site Results (PDF)

(17pp, 170K)

Shelter in Place

selecting a small, interior room, with no or few windows, and taking refuge there. It does not requires

sealing off the entire home or office building.

Sievert (Sv)

a unit used to derive a quantity called equivalent dose. This relates the absorbed dose in human tissue to

PROGRAMS TOPICS REFERENCES

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the effective biological damage of the radiation. Not all radiation has the same biological effect, even for

the same amount of absorbed dose. Equivalent dose is often expressed in terms of millionths of a

Sievert, or micro-Sievert. One Sievert is equivalent to 100 rem.

Site

any installation, facility, or discrete, physically separate parcel of land, or any building or structure or

portion thereof, that is being considered for survey and investigation.

Slope Factors

risk coefficients for radionuclides, risk per unit dose.

Heast Table 4: Radionuclide Slope Factors

This page provides the latest information and guidance on

using radionuclide slope factors from the Health Effects

Assessment Summary Tables (HEAST) - Radionuclides

Table (formerly Table 4).

Solid Waste

RCRA defines solid waste as any solid, semi-solid, liquid, or contained gaseous materials discarded from

industrial, commercial, mining, or agricultural operations, and from community activities.

Solid waste includes the following:

garbage

construction debris

commercial refuse

sludge from water supply or waste treatment plants

air pollution control facilities

other discarded materials

Solid waste does not include:

solid or dissolved materials in irrigation return flows or industrial discharges which are point sources

subject to permits under section 402 of the Clean Water Act

source, special nuclear, or byproduct material as defined by the AEA.

Solid Waste Landfill

See municipal waste landfill.

Somatic Effects of Radiation

effects of radiation that are limited to the exposed individual, as distinguished from genetic effects, which

may also affect subsequent generations.

Health Effects

This page describes the effects of both long-term and

acute exposure to radiation.

Source or Sealed Source

small, sealed metal cases containing radioactive materials used as references in research and industrial

processes. They are often part of specialized industrial devices that measure quantities as the moisture

content of soil or the density or thickness of materials. The sources are usually enclosed in a housing that

prevents the escape of the radiation. Often referred to as "radioactive sources" or "sealed sources."
Radiation Source Management

This site describes EPA's activities to reduce the use of

radioactive sources in industry, track exisitng sources and

recover orphan sources.

Source Material

uranium or thorium ores mined from the Earth. Source material is defined in 10 CFR 20.1003 as

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

2. Ores that contain, by weight, one-twentieth of 1 percent (0.05 percent), or more, of uranium,

thorium, or any combination or uranium and thorium. Source material does not include special

nuclear material.

Special Nuclear Material

SNM is defined in 10 CFR 20.1003 as

1. plutonium, uranium-233, uranium enriched in the isotope 233 or in isotope 235, and any other

material that the NRC, pursuant to the provisions of section 51 of the Atomic Energy Act, determines

to be special nuclear material (does not include source material)

2. any material artificially enriched by any of the foregoing (does not include source material).

Spent Nuclear Fuel

nuclear reactor fuel that has been used to the extent to that it can no longer effectively sustain a chain

reaction

Spontaneous Fission

fission that occurs without any outside cause.

Stable Nucleus

a nucleus in which the forces among its particles are balanced. See unstable nucleus as well.

Why Are Some Atoms Radioactive?

This page explains radioactive atoms.

Standards

See radiation protection standards.

Statutory Authority

responsibility and authority assigned by law to a state; a federal agency, department, bureau, etc.; or

other governmental organization

Stochastic Effects

effect that occur on a random basis with its effect being independent of the size of dose. The effect

typically has no threshold and is based on probabilities, with the chances of seeing the effect increasing

with dose. Cancer is a stochastic effect. (See also non-stochastic effects)

Health Effects

This page describes the effects of both long-term and

acute exposure to radiation.
Strontium

a silvery, soft metal, that rapidly turns yellow in air; one of the radioactive fission materials created

within a nuclear reactor during its operation. Its most common radioisotope is stronium-90, which emits

beta particles during radioactive decay.

Strontium

This fact sheet describes the basic properties and uses,

and the hazards associated with this radionuclide. It also

discusses radiation protection related to it.

Surface Disposal

placement of sewage sludge or other waste materials on an area of land for final disposal. It includes

monofills, surface impoundments, lagoons, waste piles, and dedicated disposal sites. It does not include

treatment and storage of sewage sludge, although placement on land for longer than 2 years is

considered surface disposal unless the site owner/operator retains written records demonstrating that the

operation constitutes a treatment or temporary storage site.

Tabletop Exercise (TTX)

an informal gathering of government officials and emergency response personnel to discuss an

emergency response operation based upon an emergency plan and its standard operating procedures.

The purpose of the TTX is to have participants practice problem solving and resolve questions of

coordination and assignment of responsibilities in a non-threatening format, under minimum stress. TTXs

can be use in preparation for a field exercise.

Exercises

This page provides information on exercises that range

from informal "walk throughs" to highly complex, realistic

simulations of actual emergencies. It also provides

examples of the exercises in which EPA's Radiological

Emergency Response Team has participated.

tailings

overburden and other waste rock from mining operations that contain concentrations of mineral ore that

are too low to make typical extraction methods economical.

Teratogenic Effects

non-hereditary effects from some agent that are seen in the offspring of the individual who was exposed

to the agent. The agent must be encountered during the gestation period.

Health Effects

This page describes the effects of both long-term and

acute exposure to radiation.

Terrestrial Radiation

radiation that is emitted by naturally occurring radioactive materials, such as uranium, thorium, and

radon in the earth. (see also naturally occurring radioactive materials)

Thorium

T
a naturally occurring radioactive metal found at very low levels in soil, rocks, water, plants and animals.

The most common naturally occurring forms of thorium are thorium-232, thorium-230 or thorium-228.

Thorium

This fact sheet describes the basic properties and uses,

and the hazards associated with this radionuclide. It also

discusses radiation protection related to it.

Transuranic

elements with atomic numbers higher than uranium (92). For example, plutonium and americium are

transuranics.

Waste Isolation Pilot Plant

This web site provides information on WIPP's oversight,

history of EPA's involvement in the WIPP program,

Inspections, Dockets, Certification and Recertification

Decisions, and Publications.

Tritium

Tritium (chemical symbol H-3) is a radioactive isotope of the element hydrogen (chemical symbol H)

Tritium

This fact sheet describes the basic properties and uses,

and the hazards associated with this radionuclide. It also

discusses radiation protection related to it.

Type I Decision Error

a decision error that occurs when the null hypothesis is rejected when it is true. The probability of

making a Type I decision error is called alpha ( ).

Type II Decision Error

a decision error that occurs when the null hypothesis is accepted when it is false. The probability of

making a Type II decision error is called beta ( ).

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People and Discoveries

Commonly Encountered

Radionuclides

Americium-241

Cesium-137

Cobalt-60

Iodine-129 &-131

Plutonium

Radium

Radon

Strontium-90

Technetium-99

Tritium

Thorium

Uranium

Glossary

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Uncertainty (uncertainty analysis)

During risk assessments,the need to make

assumptions or best judgments in the absence of

precise scientific data creates uncertainties.

Uncertainties attempt to define the usefulness of

the conclusion in making a decision. These

uncertainties are sometimes expressed qualitatively

and sometimes quantitatively. For example, a risk

may be determined to be 8 in 100,000, plus or

minus 1; meaning that it is between 7 and 9 in

100,000.

Unstable Nucleus

an atom is unstable (radioactive) if the forces

among the particles that make up the nucleus are

unbalanced, that is to say, if the nucleus has an

excess of internal energy. See also stable nucleus.

Why Are Some Atoms

Radioactive?

This page explains

radioactive atoms.

U

Uranium

a naturally occurring radioactive element whose principal isotopes are Uranium-238 and Uranium-235.

Natural uranium is a hard silvery-white shiny metallic ore that contains a minute amount of Uranium234.

Uranium

This fact sheet describes the basic properties and uses,

and the hazards associated with this radionuclide. It also

discusses radiation protection related to it.

Uranium Mill Tailings

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naturally radioactive residue from the processing of uranium ore. Although the milling process recovers

about 95 percent of the uranium, the residues, or tailings, contain several naturally-occurring radioactive

elements, including uranium, thorium, radium, polonium, and radon.

NESHAPs:

Subpart T: Disposal of Uranium Mill Tailings Piles

This page explains Disposal of Uranium Mill Tailings.

Subpart W: Operating Uranium Mill Tailings Piles

This page explains Operating Uranium Mill Tailings Piles.

Vadose Zone

the unsaturated, moisture-bearing layer of soil between groundwater and the surface

Vitrification

the process of converting materials into a glass-like substance, typically through a thermal process.

Radionuclides and other inorganics are chemically bonded in the glass matrix. Consequently vitrified

materials generally perform very well in leach tests. EPA has specified, under the land disposal

restrictions, vitrification as the treatment technology for high-level waste(55 FR 22627, June 1, 1990).

Whole Body Exposure

An exposure of the body to radiation, in which the entire body, rather than an isolated part, is irradiated.

X-rays

high-energy electromagnetic radiation emitted by atoms when electrons fall from a higher energy shell to

a lower energy shell. These rays have high energy and a short wave length. X-rays are very similar to

gamma rays.

Gamma Rays

A a description of the properties, uses and health effects

of gamma and x-rays.

Yellowcake

a mixture of uranium oxides that can vary in proportion and in color from yellow to orange to dark green

(blackish) depending on the temperature at which the material was dried (level of hydration and

impurities). Higher drying temperatures produce a darker, less soluble material. Yellowcake is commonly

referred to as U3O8. This fine powder is packaged in drums and sent to a conversion plant that produces

uranium hexafluoride (UF6) as the next step in the manufacture of nuclear fuel. (Ref. Nuclear Regulatory

Commission)

Yield

used to describe the power of an nuclear explosion; the amount of TNT required to create an equivalent

explosion

Yucca Mountain, Nevada

The site of the U.S. Department of Energy's proposed repository for spent nuclear fuel and high-level

radioactive waste. EPA established the public health and environmental radiation protection standards for

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the facility.

Zirconium

metallic element used in coating nuclear fuel rods and in corrosion-resistant alloys. Deposits of zirconium

(in the form of zircon or zirconium) frequently include natural radioactive materials.

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