Fissile Material - sdmp-00330129

DOE-HDBK-XXXX-2005

06/30/2005

72. FISSILE MATERIAL. General definition:

Although sometimes used as a synonym for fissionable material, this term has acquired a more

restricted meaning; namely, any material fissionable by low-energy (i.e., thermal or slow)

neutrons. Fissile materials include U-235, U-233, Pu-239, and Pu-241. (See fissionable

material.) [Derived from NRC Glossary]

Definition specific to hazardous materials transportation

Means plutonium-238, plutonium-239, plutonium-241, uranium-233, uranium-235, or any

combination of these radionuclides. The definition does not apply to unirradiated natural

uranium and depleted uranium, and natural uranium or depleted uranium that has been

irradiated in a thermal reactor. Certain additional exceptions are provided in 49 CFR 173.453.

[49 CFR 173.403]

73. FISSION. A nuclear transformation that is typically characterized by the splitting of a heavy

nucleus into at least two other nuclei, the emission of one or more neutrons, and the release of

a relatively large amount of energy. Fission of heavy nuclei can occur spontaneously or be

induced by neutron bombardment. [Derived from RHH, BEIR III]

74. FISSION PRODUCTS. Nuclei (fission fragments) formed by the fission of heavy elements,

plus the nuclides formed by the fission fragments' radioactive decay. [NRC Glossary, HPRH,

ANSI N1.1]

75. FISSIONABLE MATERIAL. Commonly used as a synonym for fissile material, the meaning

of this term has been extended to include material that can be fissioned by fast neutrons, such

as uranium-238. [NRC Glossary]

76. FLOODPLAINS. The lowlands and relatively flat areas adjoining inland and coastal waters

and the flood prone areas of offshore islands. Floodplains include, at a minimum, that area with

at least a 1.0 percent chance of being inundated by a flood in any given year.

The base floodplain is defined as the area which has a 1.0 percent or greater chance of being

flooded in any given year. Such a flood is known as a 100-year flood.

The critical action floodplain is defined as the area which has at least a 0.2 percent chance of

being flooded in any given year. Such a flood is known as a 500-year flood. Any activity for

which even a slight chance of flooding would be too great (e.g., the storage of highly volatile,

toxic, or water reactive materials) should not occur in the critical action floodplain.

The probable maximum flood is the hypothetical flood that is considered to be the most severe

reasonably possible flood, based on the comprehensive hydrometeorological application of

maximum precipitation and other hydrological factors favorable for maximum flood runoff

(e.g., sequential storms and snowmelts). It is usually several times larger than the maximum

recorded flood. [Derived from 10 CFR 1022.4, DOE Glossary]

A-16