Direct-use material: Material that is directly usable in nuclear weapons. Such materials include highly enriched uranium (HEU) and separated plutonium.

Dissolution: The process of putting a material into solution.

Downblend: Dilution of HEU with depleted uranium or natural uranium to convert it into low enriched uranium (LEU).

Drug master file (DMF): A document submitted to the Food and Drug Administration (FDA) by a Mo-99 producer describing the facility in which the Mo-99 is made; the production process itself, including any raw materials used in production; and product test methods, specifications, stability, and release criteria that may be used as a source of information when FDA approval is sought.

Eluting: Recovering an isotope (Tc-99m) by passing a saline solution through the alumina column of the generator.

Enriched uranium: Uranium with a higher concentration of the U-235 isotope than found naturally.

Enrichment: Process used to increase the concentration of the uranium-235 (U-235) isotope in a material relative to U-238.

Fission: Process whereby a large atomic nucleus (such as uranium) is split into two (and sometimes three) smaller nuclei.

Fission cross-section: Probability that a nucleus will capture a neutron and fission, usually expressed in barns.

Fission fragments: Smaller atomic fragments resulting from fission of a large nucleus.

Formula quantities: Special nuclear material in strategic quantities. For HEU this quantity is greater than 5 kg.

Greater-Than-Class-C waste: Radioactive waste that contains concentrations of certain radionuclides above the Class C limits in 10 CFR ­§61.55.

Greenfield construction: Construction of new facilities for producing and/or processing Mo-99.

Half-life: The time required for a quantity of radioactive material to decay to half of its initial value.

High-level waste: Highly radioactive materials containing fission products and transuranic elements produced as a byproduct of the reactions that occur inside nuclear reactors.

Highly enriched uranium: Uranium enriched to concentrations greater than or equal to 20 percent by weight of U-235.

Hot cell: Shielded workspace for working with highly radioactive materials.