Radiation Glossary S-T
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.
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 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.
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
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.
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."
Source Material
uranium or thorium ores mined from the Earth. Source material is defined in 10 CFR 20.1003 as
- Uranium, or thorium or any combination of uranium and thorium in any physical or chemical form
- 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
- 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)
- 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.
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)
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.
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.
T
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.
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.
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
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.
Transuranic
elements with atomic numbers higher than uranium (92). For example, plutonium and americium are transuranics.
Tritium
Tritium (chemical symbol H-3) is a radioactive isotope of the element hydrogen (chemical symbol H)
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 ().