This can be a limiting factor for certain locations, but in
general is not a large impediment in the United States.
Large clouds of non-polluting white steam rising from
a nuclear cooling tower are an iconic image of nuclear
energy to many, dramatically displaying the portion
of the water cycle where liquid is returned to vapor.
This design is employed where many factors dictate it
to be optimal, generally meaning water is not scarce.
There are other cooling designs used among the na-
tion’s 104 reactors which do not evaporate fresh water,
but merely circulate it back into the large body from
which it was drawn, consistent with necessary eco-
logical considerations. Additionally, approximately
71 percent of the world’s surface is covered by oceans
and seas. Nuclear cooling systems are not dependent
on fresh water only, and those located in coastal areas
can use sea water for cooling. Given that nearly half
of the world’s population lives within 100 miles of
the coast (Stewart 2011), nuclear reactors can often be
placed where water for cooling is not in competition
with water for other needs. When nuclear plants must
be located farther from population centers, electricity
can still be supplied, albeit with an associated cost of
greater transmission line losses. The need for cooling
is more a function of the heat cycle used to generate
electricity, than the fuel source, meaning plants of like
energy capacity will have similar water requirements
whether they are nuclear or coal powered, though in
the case of coal a portion of the waste heat is carried
away in the polluting smoke. Unique to nuclear plants
is the need to provide cooling for the fuel assembly
even when the plant is not generating electricity, as
residual heat from fissile fragments must be removed
for safety reasons.
sharon
(sharon)
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