Radioactive waste is not classified by the amount of radioactivity it gives off but by the source from which it comes.

Additional Inventory-TRU waste produced prior to 1970 and buried in trenches at various DOE sites and all nondefense or commercial waste that DOE believes will be generated through 2033; some of the Additional Inventory is also contaminated with PCBs

Alpha particles-relatively large, positively charged particles emitted by uranium and heavier elements. Can be stopped by paper or skin, but extremely damaging if swallowed or inhaled

Aquifer-a saturated layer of rock or soil beneath the surface that can supply large amounts of water

Backfill-filling the empty spaces in the waste rooms and covering the stacked drums with salt, magnesium oxide or some other material

Basic Inventory-defense TRU waste that has been placed in retrievable storage since 1970 and defense TRU waste that would continue to be generated through 2033

Bedded salt-deep salt deposits left over from an ancient sea interspersed with clay and shale

Beta particles-negatively charged particles. Can travel a few yards through air. Stopped by aluminum

Brine reinjection-brine is often an unwanted byproduct of oil recovery. Unwanted brine can be reinjected underground into the same borehole it came up or into other, unused boreholes

Contact-handled transuranic waste (CH-TRU)-has a radiation dose rate on the container surface of 200 millirem per hour or less and can be handled without special equipment

Creep-the tendency of salt to move into any open area and fill it

Criticality event-a self-sustaining nuclear chain reaction which releases instantaneous radiation. Occurs when a large enough amount of fissionable materials (like uranium 235 and plutonium 239) are brought together

Curie-a measure of the rate of radioactive decay; 1 curie is a large amount of radioactivity, equal to 37 billion radioactive disintegrations per second (the radioactivity of one gram of radium)

Decay heat-as radioactive materials decay or decrease in activity over time, they spontaneously emit radioactivity (alpha, beta, gamma, etc.) and heat

Decommissioning-the process of removing a building or area from use and decontaminating and disposing of it or placing it on standby

Electrostatic-relating to static electricity; capable of producing a static electrical spark

Emplace-to put in position as in emplacing the RH-TRU canisters horizontally in the waste room walls and stacking the CH-TRU drums in the waste rooms for disposal

Fuel Assembly-a bundle of uranium fuel rods; the fuel from nuclear reactors-highly radioactive

Gamma rays-electromagnetic radiation similar to light or X-rays, but much more energetic. Requires lead or concrete shielding

Half-life-time required for half of a radioactive substance to lose its activity. For example, starting with 1 pound of plutonium, in 24,000 years, half will decay away leaving 1/2 pound of plutonium. In another 24,000 years half of the remaining plutonium will decay away leaving 1/4 pound of plutonium. About 10 half-lives are required for a substance to decay to safe levels

Headspace-the empty space at the top of a sealed drum (or waste room) where flammable gases could concentrate

High-level waste (HLW)-the highly radioactive byproduct of reprocessing spent nuclear fuel and irradiated targets from reactors. HLW is liquid until it is treated

Hot cell-a heavily shielded room for viewing and handling radioactive materials robotically

Hydrofraction-The practice of purposely fracturing a formation with pressurized water in order to extract resources

Hydrology-the study of water-especially underground sources of water-and water flow patterns

Infrastructure-all the parts of the system necessary to prepare, process and package waste for disposal at WIPP

Interbed (sometimes called marker bed)-A relatively thin layer of contrasting material running through a formation; in the Salado salt at WIPP, the interbeds are made up of clay or shale

Ion-an atom or compound that carries an electrical charge

Lag storage-In some of the action alternatives in the SEIS-II, the large volume of waste in the Total Inventory would be treated within 35 years, but because only a relatively small amount of the RH-TRU waste could be emplaced every year and because of the amount of time required to excavate additional underground panels, waste would have to remain stored at the treatment sites for over 100 years awaiting disposal; waste emplacement would ³lag behind² waste treatment

Latent Cancer Fatality-a measure of the number of cancer deaths in a population that are caused by the populationıs exposure to a carcinogen like radiation

Low-level waste (LLW)-all radioactive waste not classified as high-level waste, spent nuclear fuel or transuranic waste. Further divided into contact-handled, remote-handled; alpha and non-alpha

Mixed waste-contains both radioactive and hazardous components like solvents and heavy metals

Nanocurie-one billionth of a curie

Neutron-a particle with no electrical charge. Can pass through concrete and lead

Nuclide-a species of atom characterized by the constitution of its nucleus; that is, the number of protons, neutrons and energy content. To be a distinct nuclide, the atom must be capable of existing for a measurable length of time

Operational phase-the process and time during which waste would be brought to WIPP and placed underground for permanent disposal

Penetrating radiation-radiation that is able to penetrate many materials including the human body. Gamma rays, Beta particles and neutrons are types of penetrating radiation

Potash-a mineral used in fertilizer; a nonrenewable resource essential for agriculture

Pyrophoric-capable of bursting into flame on contact with air. Plutonium, uranium and thorium are pyrophoric metals

Radiation-any radiation displacing electrons from atoms, thereby producing ions

Radiolysis-Radionuclides in the waste that come into contact with organic materials like wood or plastics, irradiate those materials and cause those materials to break down or decompose. This process releases various other chemical compounds and gases like hydrogen and vinyl chloride.

Radionuclide-an unstable nuclide capable of spontaneous transformation into other nuclides through changes in its nuclear configuration or energy level; this transformation is accompanied by the emission of photons or particles.

Rem-measure of the accumulation of radioactivity received over a period of time related to the amount of damage caused to living tissue

Remote-handled transuranic waste (RH-TRU)-has a radiation dose rate on the container surface of above 200 millirem per hour and must be heavily shielded with lead for handling. The radiation dose of most RH-TRU is below 100 rem per hour but the RH-TRU external gamma dose rate can reach 30,000 rem per hour. No RH-TRU at WIPP can have a surface dose rate above 1000 rem per hour and only 5% of the RH-TRU can be above 100 rem per hour

Resuspension-the process whereby radioactive particles that have been spread on the ground are again suspended in the air from wind, plowing, etc.

Retrievably stored-waste that can be removed intact from the storage environment

Risk assessment-the process of figuring out how likely an accident or incident is and the probable results of such an event

Solubility-the amount of a substance that can be dissolved in a liquid under specified conditions

Spent fuel rods-reactor fuel that has become too radioactive to be used

Subsidence-the process of sinking or falling to a lower level

Total inventory-The Basic Inventory (including the excess RH-TRU waste) and the Additional Inventory with or without PCB-contaminated TRU waste

Transportation phase-the process in which waste would be transported from storage facilities to WIPP. Mostly coincides with the operational phase

Uranium inventory-how much and what kinds of uranium are in the waste

Volatile Organic Compound (VOC)-primarily solvents that can become gaseous. Some VOCs are flammable

Waste characterization-sampling, monitoring, and analysis to determine the nature of the waste in the drums

Waste form-the physical form of the waste-whether it is solid, liquid, etc. An unmodified waste form is one that has not been changed; for instance, liquids that have not been treated and solidified

Water flooding for secondary recovery of oil-after the bulk of the oil in an oil well flows or is pumped out of a borehole, some oil may remain. By injecting water or brine into the formation where this oil lies, enough pressure is created to bring that oil to the surface.