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9 GLOSSARY

absorbed dose:  The energy imparted to a material by ionizing radiation per
unit mass of irradiated material.  An absorbed dose of 1 rad is equivalent to
absorption of 100 erg/g or 0.01 Joule/kg.
activity:  The rate of disintegration (transformation) or decay of radioactive
material.  The units of activity are the curie (Ci) and the becquerel (Bq).
acute:  Happening over a short time period, usually referring to accidents.
airborne release rate (ARR):  The airborne release fraction over the leak time
duration.
air quality:  A measure of the levels of pollutants in the air.
air quality standards:  The prescribed level of pollutants in the outside air
that cannot be exceeded legally during a specified time in a specified area.
alpha particle:  A positively charged particle consisting of two protons and
two neutrons that is emitted from the nucleus of certain nuclides during
radioactive decay.  It is the least penetrating of the three common types of
radiation (alpha, beta, and gamma).
ambient air:  The surrounding atmosphere, usually the outside air, as it
exists around people, plants, and structures.  It is not the air in immediate
proximity to emission sources.
annulus:  Space between the two walls of a double-shell tank.
aquifer:  A subsurface geologic formation that contains sufficient saturated
permeable material to conduct groundwater and to yield significant quantities
of groundwater.
atmospheric dispersion coefficient:  The normalized ground level concentration
of a contaminant in air at a specified distance from an emission source. Also
called -/Q and expressed in units of s/m3
atom:  The basic component of all elements; it is the smallest part of an
element having all the chemical properties of that element.  Atoms are made up
of protons and neutrons (in the nucleus) and electrons.
atomic mass:  The number of protons and neutrons in an atom.  For example,
uranium-238 has an atomic mass of 238 (92 protons and 146 neutrons).
As Low As Reasonably Achievable (ALARA):  Making every reasonable effort to
maintain exposures to radiation as far below the dose limits in 10 CFR 20 as
is practical consistent with the purpose for which a licensed activity is
undertaken, taking into account the state of technology, the economics of
improvements in relation to state of technology, the economics of improvements
in relation to benefits to public health and safety, and other societal and
socioeconomic considerations, and in relation to utilization of nuclear energy
and licensed material in the public interest.
background radiation:  The amount of radiation to which a member of the
population is exposed from natural sources, such as terrestrial radiation due
to naturally occurring radionuclides in the soil, cosmic radiation originating
in outer space, and naturally occurring radionuclides deposited in the human
body.
basalt:  a dark, fine-grained rock of volcanic origin.
beta particle:  An elementary particle emitted from a nucleus during
radioactive decay.  It is negatively charged, is identical to an electron, and
is easily stopped by a thin sheet of metal.
biota:  The plant and animal life of a region.
bounding:  A process used in impact analysis in which conservative assumptions
and/or analytical techniques are used.  Bounding assures that impacts are not
underestimated, and by encompassing actions with impacts of greatest
significance, bounding also ensures that all reasonably foreseeable impacts
are included in the analysis. 
cancer:  A malignant tumor of potentially unlimited growth, capable of
invading surrounding tissue or spreading to other parts of the body by
metastasis.
capable (fault):  Descriptive term for a geological fault which has moved at
or near the ground surface within the past 35,000 years, or has moved two or
more times during the last 500,000 years.
carcinogen:  An agent that may cause cancer.  Ionizing radiations are physical
carcinogens; there are also chemical and biological carcinogens.
carcinogenic:  Exhibiting the characteristics of a carcinogen.
cask:  A container designed for shipping, storage, and disposal of radioactive
material that affords protection from accidents and provides shielding for
radioactive material.  The design features include special shielding,
handling, and sealing features to provide positive containment and to minimize
personnel exposure.
chemical processing:  Chemical treatment of materials to separate specific
constituents.
chronic:  Occurring over a long time period, or continuous, as opposed to
acute.  
Code of Federal Regulations (CFR):  A documentation of the regulations of
federal executive departments and agencies.
committed dose equivalent:  The dose equivalent to organs or tissues of
reference that will be received from an intake of radioactive material by an
individual during the 50-year period following the intake.
committed effective dose equivalent (CEDE):  The sum of the products of the
weighting factors applicable to each of the  body organs or tissues that are
irradiated and the committed dose equivalent to those organs or tissues.
community (environmental justice definition):  A group of people or a site
within a given area exposed to risks that potentially threaten health,
ecology, or land values.
complexants:  Chemicals, usually organic, which assist in chelating (a type of
chemical bonding) metallic atoms; examples include citrates,
ethylenediamenetetraacetic acid (EDTA), and hydroxyethylenediamenetetraacetic
acid (HEDTA).
condensate:  Liquid obtained by condensation of a gas or a vapor.
confined aquifer:  A subsurface water-bearing region having defined,
relatively impermeable upper and lower boundaries and whose pressure is
significantly greater than atmospheric throughout.
conservative:  Conservative choices of parameters or assumptions are those
that would tend to overestimate rather than underestimate impacts.
contaminant:  Any gaseous, chemical, or other material that contaminates the
air, soil, or water.
contamination (contaminated material):  The deposition, solvation or
infiltration of radionuclides on or into an object, material or area; the
presence of unwanted radioactive materials or their deposition, particularly
where it might be harmful. The term also refers to the presence of any
hazardous substance at levels greater than those that occur naturally in the
surrounding environment.
controlled area:  An area, outside of a restricted area but inside the site
boundary, access to which can be limited for any reason.
corrosion:  The destruction of metal by chemical or electrochemical processes.
crib:  An underground structure designed to receive liquid waste which can
percolate into the soil directly an/or after traveling to a connected tile
field.
critical:  A condition in which a fissionable material is capable of
sustaining a nuclear reaction.
criticality:  State of being critical; refers to a self- sustaining nuclear
chain reaction in which there is an exact balance between production and loss
of neutrons in the absence of extraneous sources
cumulative effects:  Additive environmental, health, and socioeconomic effects
that result from a number of similar activities in an area.
curie (Ci):  A unit of measure of radioactivity equal to 37 billion
disintegrations per second.  
decay product:  A nuclide formed by the radioactive decay of another nuclide,
which is called the parent.
decay, radioactive:  The spontaneous transformation of one nuclide into a
different nuclide or into a different energy state of the same nuclide.  The
process results in the emission of nuclear radiation (alpha, beta, or gamma
radiation).
decommissioning:  Decommissioning operations remove facilities such as
processing plants, waste tanks, and burial grounds from service and reduce or
stabilize radioactive contamination.
decontamination:  Removal of radioactive contamination from facilities, soils,
or equipment by washing, chemical action, mechanical cleaning, or other
techniques.
derived concentration guide (DCG):  The concentration of a radionuclide in air
or water that, under conditions of continuous exposure for one year by one
exposure mode (i.e., ingestion of water, submersion in air, or inhalation),
would result in an effective dose equivalent of 100 mrem [(0.1 rem = 1
milisievert (mSv)].
design basis accident (DBA):  An accident that is considered credible enough
to be used to establish design and performance requirements for systems,
structures, and components important to safety.
design basis earthquake (DBE):  The maximum intensity earthquake that might
occur along the nearest capable fault to a structure.  Structures are built to
withstand a design basis earthquake.
dispersion:  Phenomenon by which a material placed in a flowing medium
gradually spreads and occupies an ever-increasing portion of the low flow
domain.
dose:  A generic term often used to refer to absorbed dose, dose equivalent,
effective dose equivalent, committed effective dose equivalent, or total
effective dose equivalent.
dose equivalent:  A term used to express the amount of effective radiation
when modifying factors have been considered.  It is the product of absorbed
dose (rads) multiplied by a quality factor, distribution factor, and other
modifying factors.  It is measured in rem.
dose rate:  The radiation dose delivered per unit time (e.g., rem per year).
double-shell tank (DST):  A reinforced concrete underground vessel with two
inner steel liners to provide containment and backup containment of liquid
wastes; the annulus between the two steel liners is instrumented to detect
leaks from the inner liner.
ecology:  The science dealing with the relationship of all living things with
each other and with the environment.
ecosystem:  A complex of the community of living things and the environment
forming a functioning whole in nature.
effective dose equivalent (EDE):  The sum of the products of the dose
equivalent to the organ or tissue and the weighting factors applicable to each
of the body organs or tissues that are irradiated.
effluent:  A liquid waste, discharged into the environment, usually into
surface streams.
Effluent Treatment Facility:  A treatment facility on the Hanford Site that
receives low-level liquid effluents and removes organic, hazardous, and
radioactive contaminants.  The final product of this plant is water that is
pumped to the Treated Effluent Disposal Facility.
emergency response planning guidelines (ERPG) values:  These values, which are
specific for each chemical, are established for three general severity levels: 
exposure to concentrations greater than ERPG-1 values for a period of time
greater than 1 hour results in an unacceptable likelihood that a person would
experience mild transient adverse health effects, or perception of a clearly
defined objectional odor; exposure to concentrations greater than ERPG-2
values for a period of time greater than 1 hour results in an unacceptable
likelihood that a person would experience or develop irreversible or other
serious health effects, or symptoms that could impair one's ability to take
protective action; exposure to concentrations greater than ERPG-3 values for a
period of time greater than 1 hour results in an unacceptable likelihood that
a person would experience or develop life-threatening health effects.
emission standards:  Legally enforceable limits on the quantities and/or kinds
of air contaminants that may be emitted into the atmosphere.
endangered species:  Plants and animals in an area that are threatened with
either extinction or serious depletion of a species.
environment:  The sum of all external conditions and influences affecting the
life, development, and ultimately, the survival of an organism.
Environmental Impact Statement (EIS):  A legal document required by the
National Environmental Policy Act (NEPA) of 1969, as amended, to assess the
environmental impacts of major Federal actions.
environmental justice:  The fair treatment of people of all races, cultures,
incomes, and educational levels with respect to the development,
implementation, and enforcement of environmental laws, regulations, and
policies.  Fair treatment implies that no population of people should be
forced to shoulder a disproportionate share of the negative environmental
impacts of pollution or environmental hazards due to a lack of political or
economic strength.
erosion:  The process in which soil is carried away by the action of wind or
water.
evaporator:  A facility that mechanically reduces the water content in tank
waste to concentrate the waste  to reduce storage needs.
exceedence:  A value that exceeds a prescribed limit.
exposure (to radiation):  A measure of ionization produced in air by X-rays or
gamma radiation, measured in roentgens. Also the condition of being made
subject to the action of radiation.  Acute exposure generally refers to a high
level of exposure of short duration; chronic exposure is lower-level exposure
of long duration.
fault:  A fracture or a zone of fractures within a rock formation along which
vertical, horizontal, or transverse slippage has occurred in the past.
fission:  The splitting or breaking apart of a heavy atom such as uranium. 
When a uranium atom is split, large amounts of energy and one or more neutrons
are released.
fission products:  A general term for the complex mixture of nuclides produced
as a result of nuclear fission.  Most, but not all, nuclides in the mixture
are radioactive, and they decay, forming additional (daughter) products, with
the result that the complex mixture of fission products formed contains about
200 different isotopes of over 35 elements.
floodplain:  Valley floor constructed by an active river and periodically
covered with floodwater from that river during intervals of over-bank flow.
fuel (nuclear, reactor):  Fissionable material used as the source of power
when placed in a critical arrangement in a nuclear reactor.
gamma rays:  High-energy, short wavelength electromagnetic radiation
accompanying fission and emitted from the nucleus of an atom.  Gamma rays are
very penetrating and require dense materials (e.g., lead) for shielding.
genetic effects:  Radiation- or chemical-induced effects (primarily mutations)
that affect the descendants of the exposed individual; also called
"hereditary" effects.
geology:  The science that deals with the earth:  the materials, processes,
environments, and history of the planet.
greenhouse:  In radiation protection, a temporary structure used as a
confinement barrier between a radioactive work area and a non-radioactive area
to prevent the spread of contamination.
groundwater:  The supply of fresh water under the earth's surface in an
aquifer.
half-life (radiological):  The time in which half the atoms of a radioactive
substance disintegrate to another nuclear form; used as a measure of the
persistence of radioactive materials.  Half-lives vary from millionths of a
second to billions of years.
hazardous waste:  A solid waste or combination of solid wastes that, because
of its quantity, concentration, or physical, chemical or infectious
characteristics, may cause or significantly contribute to an increase in
mortality or an increase in serious, irreversible , or incapacitating
reversible illness or pose a substantial present or potential hazard to human
health or the environment when properly treated, stored, transported, disposed
of, or otherwise managed. In this regulatory definition solid wastes may also
be in a liquid phase.
health effects:  Detrimental effects on human health as the result of exposure
to radiation or toxic chemicals.
heavy metals:  Metallic elements of high molecular weight, such as mercury,
chromium, cadmium, lead, and arsenic, that are toxic to plants and animals at
certain concentrations.
high-efficiency metal filter (HEMF):  A filter that performs the same function
as a high-efficiency particulate air (HEPA) filter, but which can be washed to
allow re-use.
high-efficiency particulate air (HEPA) filter:  A type of filter designed to
remove 99.95 percent of the particles down to 0.3 mm in diameter from a
flowing air stream.
high activity waste:  Any waste that is above NRC Class C (10 CFR 61.55)
waste.
high-level waste (HLW):  The highly radioactive wastes that result from
processing of spent nuclear fuel, including liquid waste produced directly in
reprocessing, and any solid waste derived from the liquid, that contains a
combination of TRU waste and fission products in concentrations that require
permanent isolation (DOE Order 5820.2).  All waste in Hanford's HLW storage
tanks is radioactive and is managed as HLW, although some wastes do not meet
the definition of HLW.
hydraulic sluicing (past practice sluicing):  A method for removing slurry
from double-shell tanks by dissolving/suspending in water and pumping the
waste from the tanks.                                        
intensity (earthquake):  A numerical rating used to describe the effects of
earthquake ground motion on people, structures, and the earth's surface.  The
numerical rating is based on an earthquake intensity scale such as the
Modified Mercalli Intensity Scale commonly used in the United States.
interim stabilization:  Removing the liquids that can be readily pumped from
single-shell tank wastes and transferring these liquids to double-shell tanks.
interim storage:  The temporary holding of waste on or away from the
generator's site when disposal space is not available.  Monitoring and human
control are provided for interim storage facilities.
interstitial liquid (interstitial liquor):  Liquid in a waste matrix
accommodated in the pore spaces; some is capable of gravity drainage while the
rest is held by capillary forces.
ion:  An atom or molecule that has gained or lost one or more electrons and
has become electrically charged.
ionization:  The process that creates ions.  Nuclear radiation, x-rays, high
temperatures, and electric discharges can cause ionization.
ionizing radiation:  Alpha particles, beta particles, gamma rays, x-rays,
neutrons,high speed protons, and other particles capable of producing ions.
irradiation:  Exposure to radiation.
isotopes:  Different forms of the same chemical element that are distinguished
by different numbers of neutrons in the nucleus.  a single element may have
many isotopes; some may be radioactive and some may be stable. 
latent period:  The period or state of seeming inactivity between the time of
exposure of tissue to an acute radiation dose and the onset of radiation
sickness.
latent cancer fatality (LCF):  The death of an individual due to a cancer
induced by previous exposure to radiation or toxic chemicals.
low-income communities:  A community where 25 percent or more of the
population is identified as living in poverty.
long-lived radionuclides:  Radioactive isotopes with half-lives greater than
about 30 years.
low-level waste:  Radioactive waste not classified as high-level waste, spent
fuel, transuranic waste, or byproduct waste per Atomic Energy Act - Section
11e(2), and DOE Order 5820.2.
maximally exposed off-site individual (MEOSI):  A hypothetical member of the
public assumed to permanently reside at the location of highest calculated
dose.
mitigation:  A series of actions implemented to ensure that project impacts
will result in no net loss of habitat value or wildlife populations.  The
purpose of these actions is to avoid, minimize, rectify or compensate for any
adverse environmental impact.
mixed waste:  Waste that contains both radioactive and hazardous chemical
components.     
Modified Mercalli Intensity (MMI) Scale:  A scale of measure used in the U.S.
to show earthquake intensity.
nanocurie (nCi):  One billionth of a curie.
National Environmental Policy Act of 1969 (NEPA):  Law that requires that
Federal agencies assess the environmental consequences associated with their
actions.
National Register of Historic Places (NRHP):  A list maintained by the
National Park Service of architectural, historical, archaeological, and
cultural sites of local, state, or national importance.
natural radiation or natural radioactivity:  Background radiation.  Some
elements are naturally radioactive whereas others are induced to become
radioactive by bombardment in a reactor or accelerator.  Naturally occurring
radiation is indistinguishable from induced radiation.
Neutralized Current Acid Waste (NCAW):  The highly radioactive liquid waste
remaining after plutonium is removed from dissolved irradiated fuel during
reprocessing.  It is the most radioactive of the waste streams from
reprocessing operations.
Neutralized Cladding Removal Waste (NCRW):  Waste that results from dissolving
and removing the zirconium cladding from irradiated N Reactor fuel in the
plutonium-uranium extraction process (PUREX).  This waste has been neutralized
to permit low-corrosive storage in carbon steel tanks.  This waste stream has
transuranic contamination.
neutron:  A particle existing in or emitted from the atomic nucleus; it is
electrically neutral and has a mass about equal to that of a stable hydrogen
atom.  Neutrons are used to split heavy atoms in the fission reaction.
nitrogen oxides (NOx):  A mixture of nitrogen-oxygen containing compounds
primarily formed as gaseous waste effluents in the combustion of most fossil
fuels.
nuclear radiation:  Radiation, usually alpha, beta, or gamma, which emanates
from an unstable atomic nucleus.
Nuclear Regulatory Commission (NRC):  The independent Federal commission that
licenses and regulates nuclear facilities.
nucleus:  The positively charged center of an atom.
nuclide:  A species of atom having a specific mass, atomic number, and nuclear
energy state.
offsite:  Outside the boundaries of the Hanford Site.
off-site population:  The collective sum of individuals located within an
80-kilometer (50-mile) radius of the accident location.
onsite:  Any place within the Hanford Site boundary.
operations:  All aspects of the operation of a plant or facility including
engineering, maintenance, safety, and process operations.
organic compounds:  Chemicals compound containing carbon.
particulates:  Solid particles small enough to become airborne.
past practice sluicing:  See hydraulic sluicing
pH:  A measure of the hydrogen ion concentration in aqueous solution.  Acidic
solutions have a pH from 0 to 7, basic solutions have a pH from 7 to 14.
picocurie (pCi):  One trillionth of a curie.  
permeability:  Ability of rock, groundwater, soil, or other substance to
transmit liquid.
person-rem:  The radiation dose commitment to a given population; the sum of
the individual doses received by a population segment.
plume:  The distribution of contaminants a distance away from a point source
in a medium like groundwater or air.  
population dose (population exposure):  Summation of individual radiation
doses received by all those exposed to the source or event being considered.
precipitate:  An insoluble solid that can be separated from liquid by
filtration (used as a noun).
prevention of significant deterioration (PSD):  This standard establishes the
acceptable amount of deterioration in air quality.  When the air quality of an
area meets the standards for a specific pollutant, the area is declared to be
in attainment for that pollutant.  When the air quality of an area does not
meet the standard for a specific pollutant, the area is said to be in non-
attainment for that pollutant.  PSD requirements allow maximum allowable
increases (increments) in ambient air pollutant concentration (sulfur dioxide,
particulate, nitrogen oxide) for construction or modification of facilities
which by definition do not "significantly deteriorate" the existing baseline
air quality.
public comment:  A written or verbal statement made in response to a position
proposed by a government agency.
rad:  The special unit of absorbed dose from ionizing radiation equal to an
absorbed dose of 0.01 joules per kilogram of irradiated material.
radiation (ionizing):  See ionizing radiation.
radiation monitoring (radiation protection monitoring, monitoring):  The
measuring of radiation levels, concentrations, surface area concentrations or
quantities of radioactive material and the use of the results of these
measurements to evaluate potential exposures and doses.
radiation survey:  Evaluation of an area or an object with instruments to
detect, identify and quantify radioactive materials and radiation fields
present.
radiation shielding:  Reduction of radiation by interposing a shield of
absorbing material between a radioactive source and a person, laboratory area,
or radiation-sensitive device.
radiation area:  Area containing radioactive materials in quantities
significant enough to require control of personnel entry into the area.     
radioactive (decay):  Undergoing spontaneous nuclear transformation in which
nuclear particles or electromagnetic energy are emitted.
radioactive waste:  Solid, liquid, or gaseous material of negligible economic
value that contains radionuclides in excess of threshold quantities.
radioactivity:  The property of spontaneous decay or disintegration of
unstable atomic nuclei, accompanied by the emission of radiation.
radioisotopes:  Radioactive isotopes, i.e, unstable isotopes of an element
that will eventually undergo radioactive decay.
radionuclide:  A nuclide that is radioactive.
receptor:  Individuals or populations that could be exposed to radiation,
radioactive materials, or toxic chemicals.
rem (roentgen equivalent man):  The special unit of any of the quantities
expressed as dose equivalent.  The dose equivalent in rems is equal to the
absorbed dose in rads multiplied by a quality factor. One rem = 0.01 Sv.
reprocessing:  The process by which spent fuel is separated into waste
material for disposal and into material such as uranium and plutonium to be
reused.     
respirable fraction (RF):  That fraction of airborne droplets or particulate
matter (aerosol) with individual particle aerodynamic equivalent diameter less
than 10 microns.  This is assumed to be important for inhalation consequences. 
Non-condensable gases and vapors have a respirable fraction of 1.
Richter scale:  A scale by which earthquakes are measured with graded steps
from 1 through 10.  Each step is approximately 60 times greater than the
preceding step and is adjusted for different regions of the earth.
risk:  Quantitative expression of possible impact that considers both the
probability that a hazard causes harm and the consequences of that event
(e.g., for cancer risk, the product of the annual frequency of occurrence
multiplied by the number of latent cancer fatalities).
roentgen:  A unit of measure of ionizing electromagnetic radiation exposure (X
and gamma rays)
salt cake:  Concentrated waste in the form of crystallized salts resulting
from the evaporation of liquid high-level waste.
salt well:  A hole drilled or sluiced into a salt cake and lined with a
cylindrical screen to permit drainage and jet pumping of interstitial liquid.
seismic load:  The force due to earthquakes.
seismicity:  The relative distribution and frequency of earthquakes.
shield:  An engineered body of absorbing material used to protect personnel
from radiation. Shielding is often provided by materials such as concrete,
water, lead, or earth
shrubb-steppe:  An important habitat type found on the Hanford Site.  Shrub-
steppe is characterized by vegetation requiring little moisture in areas of
extreme temperature range.  It is considered a priority habitat by Washington
State.
single-shell tank (SST):  Older style Hanford HLW underground storage tank
composed of a single carbon steel liner surrounded by concrete. 
sludge:  The precipitated solids (primarily oxides and hydroxides) that settle
to the bottom of the storage tanks containing liquid high-level waste.
sluicing:  A method of waste retrieval which utilizes a high-volume, low-
pressure stream of liquid to mobilize the waste prior to pumping.
slurry:  A suspension of solid particles (sludge) in water.
solid waste (radioactive):  Either solid radioactive material or solid objects
that contain radioactive material or bear radioactive surface contamination.
source term:  The quantity of radioactive material, released by an accident or
operation, which causes exposure after transmission or deposition.
stabilization:  Treatment of waste or a waste site to protect the biosphere
from contamination.
stack:  A vertical pipe or flue designed to exhaust gases and suspended
particulates.
storage:  Retention of material in a manner permitting retrieval.
subchronic (exposure):  Exposures with durations ranging from 2 weeks to 7
years.
subsidence:  Gradual or sudden sinking of the ground surface below natural
grade level due to slow decay and compression of material or collapse of a
large void space.
sump:  A collection point (depression or tank) for liquids prior to their
transfer.
supernatant:  The radioactive layer of highly-mobile liquid containing soluble
salts that remains above the salt cake and/or insoluble sludge in a waste
tank; also called free liquid.
surface water:  All water on the Earth's surface, as distinguished from
groundwater.
tank:  A large steel-lined concrete container located underground for storage
of liquid waste.
tank farm:  An installation of interconnected underground tanks for the
storage of high-level radioactive liquid wastes.
tectonic:  Pertaining to or designating the rock structures resulting from
deformation of the earth's crust.     
terrane:  Any rock formation or series of formations.
toxicity:  The quality or degree of being poisonous or harmful to plant or
animal life.
transuranic (TRU) waste:  Radioactive waste containing alpha-emitting
transuranic radionuclides with half-lives greater than 20 years and
concentrations greater than 100 nanocuries per gram of waste.
Treated Effluent Disposal Facility (TEDF):  A facility on the Hanford Site
that receives treated effluent from the Effluent Treatment Facility and
disposes of it below ground where it percolates down through the vadose zone.
Tri-Party Agreement:  The Hanford Federal Facility Agreement and Consent
Order.  It is an agreement signed in 1989 and amended in 1994 by the U.S.
Department of Energy, the U.S. Environmental Protection Agency, and the
Washington State Department of Ecology that identifies milestones for key
environmental restoration and waste management actions.
200 Areas plateau:  Highest portion on the Hanford Site (excluding Rattlesnake
and Gable Mountains), containing most of the waste processing and storage
facilities.
242-A Evaporator:  A facility in the 200 East Area that concentrates dilute
liquid waste from the double-shell tanks to reduce the volume of waste in the
tanks.
unconfined aquifer:  An aquifer that has a water table or surface at
atmospheric pressure.
unplanned release:  Unplanned discharge of contaminated liquid or particulate
material.
vadose zone:  The unsaturated region of soil between the ground surface and
the water table.
volatile organic compounds (VOCs):  Organic compounds with a vapor pressure
greater than 0.44 pounds per square inch at standard temperature and pressure. 
volatilize:  Cause to pass off as a vapor.
volume reduction (waste volume reduction):  Various methods of waste treatment
such as evaporation of liquids or compaction of solids, aimed at reducing the
volume of waste.
waste concentration:  Removal of excess water from liquid waste or slurries.
waste form:  The form in which a waste exists at the time of interest.
watchlist tanks:  Tanks that have been identified as watchlist tanks in
accordance with Public Law 101-510, section 3137, Safety Measures for Waste
Tanks at Hanford Nuclear Reservation, 1990.  These tanks have been identified
as the Priority 1 Hanford Site Tank Farm Safety Issues: " Issues /situations
that contain most necessary conditions that could lead to worker (onsite) or
offsite radiation exposure through an uncontrolled release of fission
products, e.g., Tank SY-101."
water table:  Upper boundary of an unconfined aquifer surface below which soil
saturated with groundwater occurs.
water quality standard:  Provisions of state or Federal law that consist of a
designated use or uses for the waters of the United States and water quality
criteria for such waters based upon those uses.  Water quality standards are
used to protect the public health or welfare, enhance the quality of water,
and serve the purposes of the Clean Water Act.
wind rose:  A diagram designed to show the distribution of wind directions at
a given location; one variation shows wind speed groupings by direction.
x-rays:  A penetrating form of electromagnetic radiation emitted when the
inner orbital electrons of an excited atom return to their normal state.