Environmental Engineering Reference
In-Depth Information
Technical Note
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(cont.)
LWRs are expected to remain thework horses of nuclear energy
until at least mid-century when something new may be needed.
The highway starts with an LWR
fleet initially fueled with
enriched uranium. When a fuel load is used up it contains a
signi
cant amount of plutonium and that plutonium is
extracted (reprocessed) and mixed with unenriched uranium
to make a new fuel called MOX (a mixture of uranium
and plutonium oxides). This new fuel is used to get about a
third more nuclear energy from the original enriched uran-
ium fuel than would otherwise be possible. The leftovers
from the plutonium extraction process contain americium,
neptunium, and curium which have to be isolated from the
environment for hundreds of thousands of years.
An off-ramp for spent fuel involves the development of
geological repositories that are safe for the very long term.
Materials put into these repositories initially will be
emplaced in a manner that allows them to be retrieved if so
desired. If new technology comes along that can treat this
material to make it easier to store, that new technology can
be used, otherwise the repository will be sealed.
With the assumptions made on the expansion of nuclear
power, a shortage of natural uranium needed for lifetime
fueling of the LWR
fleet may occur about mid-century. An
on-ramp if new fuel is needed requires the development of a
new generation of advanced nuclear reactors that can breed
new fuel from depleted uranium. The necessary R&D will
be done over the next
years so they will be ready for
large-scale commercial development around mid-century if
needed and economical.
The same technology that can be used to breed new fuel
can be tweaked to allow these reactors to destroy the long-
lived components of spent reactor fuel, creating a second
off-ramp for spent fuel. These new reactors can be used,
even if not needed for power,
to reduce the required
