Nuclear - Energy Policy Analysis: A Conceptual Framework - page 39

Figure 3.1 The Nuclear Fuel Cycle

Uranium mines
and mills

Conversion to UF 6 Enriching UF 6

Depleted uranium
tails storage

Fuel

UO 2 fuel
fabrication

Power reactor

Spent fuel

Long-term
storage

Reactor storage

Low level wastes

Low-level waste
storage

severe in roadless areas. Revegetation of mined lands takes anywhere from one growing season in
wet climates to ten years in arid locations like the western United States, where most exploration
for uranium occurs. Although large sample pits dug during coal exploration are seldom excavated
for uranium ore, other impacts from exploration drilling such as equipment noise and possible
contamination by drilling muds and fluids may be severe in uranium exploration.
The principle methods of uranium mining are box cut mining, open pit mining, and in situ
leaching. As with coal, the choice of mining method depends primarily on the depth of burial and
thickness of the uranium deposit.

UNDERGROUND URANIUM MINING

Although it is seldom used in the United States today, if uranium is buried too far below the
surface for open pit mining, an underground mine may be used with tunnels and shafts dug to
access and remove uranium ore. There is less waste material removed from underground mines
than open pit mines, but underground mining exposes workers to higher levels of radon gas than
surface mining.
Other ores, such as copper, gold, and silver, are often mined in association with uranium. Once
an ore body has been identified, a shaft is sunk in the vicinity of the ore veins, and crosscuts are
driven horizontally to the veins at various levels, usually every 329 to 492 feet (100 to 150 meters).
Similar tunnels, known as drifts, are driven along the ore veins from the crosscut. The next step
is to drive tunnels through the deposit from level to level. These are known as raises when driven
upward and winzes when driven downward. Raises are subsequently used to develop stopes where
ore is mined from veins.
A stope, which is the workshop of an underground mine, is an excavation from which ore is
extracted. Two methods of stope mining are commonly used. In the cut-and-fill or open stoping