Environmental
nuclear power relies on
fission
nuclear fission
the splitting of a 235U atom into two smaller atoms
when a neutron is absorbed by a 235U nucleus
that nucleus becomes unstable and undergoes fission and releases heat and more neutrons
fission at a high 235U concentration could result in
an amplifying reaction
amplifying reaction requires an average of more than
one neutron from each fission event hits another 235U nucleus and stimulates a fission event
at the right concentration an average of only
one neutron stimulates a subsequent fission
when you have the right concentration to stimulate only one subsequent fission the excess neutrons are absorbed by
non-fissle nuclei
sustaining nuclear reaction
controlled nuclear reaction where excess neutrons are absorbed by non-fissle nuclei
fissle
(of a nuclide) capable of undergoing fission induced by low-energy neutrons, as uranium 233 and 235.
how do you control the rate of nuclear fission
inserting control rods that absorb neutrons between fuel rods
by inserting control rods that absorb reactions you are maintaining a
sustaining reaction and a constant level of energy is produced
water circulated in the reaction chamber picks up the
heat before passing through a heat exchanger
reaction-chamber water is contaminated so
it is restricted to the containment sturcture
in nuclear power plants heat is transferred to water which is turned into
steam which drives turbogenerator which creates electricity
4 concerns about nuclear power
1. radiation 2. disposal of radioactive wastes 3. accidents 4. environmental concerns
radiation
depending on the level of exposure to the radioisotopes, may lead to short-term health problems
disposal of radioactive wastes
there is no universally agreed upon means of safely handling long term radioactive wastes
come radioisotopes can be toxic for
>200,000 years
three mile island
in PA; no health effects; 1st real incident; small radiation released; operator error; the plant/part of plant has been shut down since
Chornobyl/Chernobyl
ukraine; huge deal; operator error; steam explosion; testing to see how much the machine can handle; gasses released; found in sweden and elsewhere; people had to evacuate
Fukushima
2011; plant was by an ocean and a tsumani hit; not operator error; machine wasn’t able to handle a double error; the tsunami shut off the electricity to the emergency turn off
similar to fossil fuels uranium ore is
a crustal resource with similar problems of extraction and use
because of accidents and environmental concerns
there is not much interest in expanding nuclear power
3 positives of nuclear power
1. best option for replacing FF/already developed in places 2. a large supply of fuel 3. potential for energy for billions of years
the supply of 235U in natural uranium
is good for well over 100 years
with breeder reactors the US can
have plenty of energy for billions of years to come
two options for the future of energy
bullish on renewables or continue to have FF dominate and renewables remain small fraction
both projections for the future of energy
predict a steady rise in the total energy budget
an appropriate response to the future of energy would be
conservation
high prices encourage or coerce conservation but US citizens object to
government manipulation of energy prices unless energy is made cheaper
with conservation we would draw down FFs more slowly and thus
have more time to develop alternative energy technologies with out an energy catastrophe
breeder reactor
A breeder reactor is a nuclear reactor capable of generating more fissile material than it consumes[1
breeder reactor
A breeder reactor is a nuclear reactor capable of generating more fissile material than it consumes[1
fissle
In nuclear engineering, a fissile material is one that is capable of sustaining a chain reaction of nuclear fission.
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