| fertile material | <physics> In nuclear physics, this refers to a nuclide which converts to fissile material upon neutron capture and subsequent radioactive decay. Examples include Uranium-238 and Thorium-232. (09 Oct 1997) |
|---|---|
| fill material | Any material used for the primary purpose of replacing an aquatic area with dry land or of changing the bottom elevation of a waterbody. The term does not include any pollutant discharged into the water primarily to dispose of waste. (09 Oct 1997) |
| fissile material | <radiobiology> Material containing a large number of easily fissionable nuclei which give off multiple neutrons in the fission process. Usual meaning is that if a sufficiently large amount of fissile material is put together, a fission chain reaction can occur. Sometimes used synonymously with fissionable material, i.e., material that can be fissioned (though often under restricted circumstances, such as only with thermal (slow) neutrons). A more restricted meaning use of fissile material limits the concept to those materials which can be fissioned by neutrons of all energies (fast & slow). Examples include Uranium-235 and Plutonium-239. (09 Oct 1997) |