Environmental Engineering Reference
which is usually more
than four-ifths uranium.
Then, more work is
needed. A process known
as enrichment increases
the amount of U-235,
raising the usual 0.7
percent to whatever level
is needed. For reactors,
the enriched uranium
material—in a form called
uranium oxide—is usually
shaped into little ceramic
pellets. These are then put
into fuel rods.
U-235 for use in
nuclear reactors can be
obtained in other ways
as well. Some countries
reprocess used, or spent,
fuel rods. These rods no
longer have enough U-235 to support a chain reaction, but they
still contain some, which can be extracted and processed to
make new fuel pellets.
Plutonium—more speciically, the isotope plutonium-239,
or Pu-239—can also be used for nuclear fuel. (It is also used
to make nuclear bombs.) Plutonium decays more rapidly than
uranium. As a result, almost none can be found in nature.
Instead, it is specially made from other elements. Special
reactors that are used to make a great deal of nuclear fuel such
A technician with a barrel of yellowcake, which
has been reined so that it is mostly uranium.