Appendix E
Glossary
calcination:
The decomposition of a material to a granular ceramic, usually involving an oxidizing atmosphere at an elevated temperature, for the purpose of changing its properties (e.g., to dehydrate or to form another phase). At the Idaho National Engineering and Environmental Laboratory, the calcination process injected waste into a fluidized bed to evaporate the water and decompose other material constituents into ''calcine.'
calcine:
A general term for the granular ceramic generated by calcination. For the INEEL HLW program, it is a specific product from a fluidized bed calciner.
cladding:
The outer protective layer, usually metal, over a fuel element.
contact-handled transuranic (CH-TRU):
A classification of TRU waste with a surface contact surface dose rote < 200 mrem/hour. The term derives from operational safety considerations; such waste could be handled safely, at least for short exposure times, by human contact at or near the surface of the waste container.
curie (Ci):
A measure of radioactivity equal to 3.7 × 1010 disintegrations per second, a historical unit representing approximately the radioactivity of 1 gram of radium-226. The Systeme Internationale (SI) unit for radioactivity is the Becquerel, 1 disintegration per second.
Decontamination Factor (DF):
The (dimensionless) ratio of the concentration of a species of interest that is in an original, input stream (to a process) to the concentration in a final, output stream. The typical quantity of interest that is used for this ratio is the radioactivity per unit volume or mass of carrier (e.g., solvent) material.
Environmental Assessment (EA) glass:
The alkali borosilicate glass developed at the Savannah River Site, used in the environmental assessment of the Defense Waste Processing Facility (DWPF) there, and specified in the Waste Acceptance Product Specification (WAPS) as a benchmark for comparison, based on the PCT leaching test. The WAPS requires that HLW glasses be as durable (in PCT leach test analyses) as EA glass.
fiuidized bed:
A cushion of hot gas blown through the porous bottom of a container, used to float a powdered material as a means of drying, heating, quenching, or calcining [modified from Parker (1994)]. This process converts a material to a powder form, which behaves as if it were a fluid stirred by the action of high-velocity gases in a region in which a bed of large inert particles are similarly agitated. Both powder and gases exit the chamber and separate when the gas velocity lowers, enabling the powder to settle. Sometimes the conversion can be done without a particle bed by using the impact of the gas stream on the walls of the chamber or the self-comminution by the calcine itself.
high activity waste (HAW):
Highly radioactive waste, used in this report to denote a concentrated fraction of the initial inventory of high-level waste.
high-level waste (HLW):
High-level waste is (1) irradiated reactor fuel; (2) liquid wastes re-salting from the operation of the first-cycle solvent extraction system, or equivalent, and the concentrated wastes from subsequent extraction cycles, or equivalent, in a facility for reprocessing irradiated reactor fuel; and (3) solids into which such liquid wastes have been convened (Source: 10 CFR 63 of the USNRC). in loose terms, HLW is the waste containing fission products and actinides that results from the re-processing of spent nuclear fuel and which requires permanent isolation in a geologic repository.
highly enriched uranium (HEU):
Uranium with more than 20 percent of the uranium-235 isotope.
ion exchange:
A chemical reaction in which mobile hydrated ions of a solid are exchanged, equivalent for equivalent, for ions of like charge in solution [from Parker (1994)]. One or more of the ionic species in solution are selectively absorbed on a solid and retained.
low-level waste (LLW):
Any radioactive waste that is not spent fuel or high-level waste.
mixed waste (MW):
Waste that contains both chemically hazardous constituents regulated under RCRA and radioactive materials regulated under the Atomic Energy Act.
partitioning:
A process that divides an input stream into two or more output streams. A mixture of solids can be partitioned based on differences in material properties. A liquid phase with two or more chemical species can be partitioned using selective media to segregate the species based on their differences in chemical reactivity.
raffinate:
The aqueous solution remaining after the metal has been extracted by the solvent; the tailing of the solvent extraction system.
remote-handled transuranic (RH-TRU):
A classification of TRU waste with a surface contact surface dose rate ≥200 mrem/hour. The term derives from operational safety considerations; such waste would need to be handled remotely, to provide adequate radiation shielding for workers.
reprocessing:
Recovery of fissile and fertile material for further use from spent fuel by chemical separation of uranium and plutonium from other transuranic elements and fission products. Selected fission products may also be recovered. This operation results in the separation of wastes.
separations factor:
The ratio of distribution coefficients (Kd) of two different elements in a given stage of a multi-stage solvent extraction process. A detailed, multi-stage process includes other effects such as the change in volume of solution clue to other inputs such as scrub flows, that dilute the radionuclide species of interest irrespective of any separations achieved in extraction stages. These are usually expressed using an "extraction factor," which is the ratio, for two phases, of the product of each phase's distribution coefficient and flow rate.
solvent extraction:
The separation of materials of different chemical types and solubilities by selective solvent action [from Parker (1994)]. This term is a general process for separating one or more chemicals solubilized in one solvent by the use of a second solvent that is (1) insoluble in the first solvent and (2) selective in its ability to bind one or more of the chemical constituents. After comixing and agitation of the two solvents, they separate, with the second having extracted the chemical species of interest.
spent nuclear furl (SNF):
Fuel that has been withdrawn from a nuclear reactor following irradiation, the constituent elements of which have not been separated by reprocessing.
sum of fractions:
The USNRC's 10 CFR 61 lists values of allowed concentrations (i.e., activity in Ci/m3) for a number of fission products and activation products for three different classes of low-level waste (A, B, C). For each individual radioisotope in a specific waste, the ratio of the actual activity to the respective limit represents the fraction of the allowed limit contributed by that isotope. Actual waste usually contains a mixture of several radioisotopes. To account for the contributions of all constituent radioisotopes in such mixtures, while remaining within the allowed limit for that waste class, the sum of these fractions for all radioisotopes present must be less than one. To allow margins for upsets, equipment failures, and other causes of process and feed variations, it is necessary in practice for the design point "sum of fractions" to be considerably less than 1 during normal operations. These considerations imply that the practical limit for each radioisotope is much less than the USNRC-stated limit.
transtwanic (TRU) waste:
Waste contaminated with transuranic elements with half-lives greater than 20 years, in concentrations greater than 100 nCi/g.
