Nuclear Power
Wesley Granath, Caleb Sponheim, Perry Anderson
Describe how neutrons produced in a fission reaction may be used to
initiate further fission reactions (chain reaction)
1. Neutron: the key to nuclear
reactions
2. Neutron is shot into a high
mass atom
3. The atom absorbs the
neutron and fission into two
new atoms, creating an
explosion.
4. The resulting explosion
sends two neutrons from the
atom to other new atoms,
therein creating a chain
reaction
5. This chain reaction is what
nuclear energy is known for.
Distinguish between controlled nuclear fission (power production) and
uncontrolled nuclear fission (nuclear weapons)
a.Controlled Nuclear Fission
b. -Uses restrictions so that the reaction doesn’t get out of control
c.-Is under constant surveillance
d.-Measures undertaken so the reaction can be slowed down.
e.Uncontrolled nuclear Fission
f. -Refers to nuclear weapons
g.-Needing to get as much energy out as possible
h.-As fast as possible reaction
i. -Used because of their destruction to weight ratio.
j. -Completely uncontrolled
Describe what is meant by fuel enrichment
• The process or transforming natural uranium into U-235 uranium
• Natural uranium:
• 99.284% U-238
• .711% U-235
• U-235 is the fissile material
• Enriched uranium
• Low-enriched uranium (reactor grade)
• 3-4% U-235
• Weapons grade uranium
• 90% U-235 Uranium
METHODS OF ENRICHMENT
Diffusion:
1.Gaseous diffusion
a.-Forcing the uranium in gas form through a membrane, creating a
separation between the compounds.
2.Thermal diffusion
a.-Put out of commission in favor of gaseous diffusion
Centrifuge
1.Gas centrifuge
a.-Large number of
rotating cylinders
b.-Much better than
diffusion
c.-54% of enriched
uranium comes from
this method
2.Zippe centrifuge
a.-An improved method
using heat along with a
centrifuge
b.-Used by Pakistan
Laser:
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-Much more efficient
-More economically viable
-None are ready for use, however.
Other :
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-Aerodynamic processes
• Can be considered non-rotating centrifuges.
-Electromagnetic isotope separation
• Used in world war two for the Hiroshima bomb
4. Describe the main energy transformations that take place in a nuclear power
station
• -Step one: nuclear energy is weaned from
enriched uranium
• -Step two: the heat created from the resulting
chain reaction turns water into steam
• -Step three: this superheated steam is used to
turn turbines, creating electricity.
5. Discus the role of the moderator and the control rods in the production of
controlled fission in a thermal fission reactor
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-located inside the core of the reactor
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Control Rods:
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-contain pellets made of efficient neutron capturers
(such as cadmium or boron)
-raised and lowered in core, when fully lowered
fission cannot occur because they absorb free
neutrons
Moderator:
-slows down the high speed neutrons in the core. If a
neutron is moving too fast it will pass through the
235U, for fission to take place they need to be
slowed.
-most common moderator is water
6.
Discuss the role of the heat exchanger in a fission reactor
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Heat Exchanger:
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-located outside the core
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- the coolant circulates
through the heat
exchanger
- heat is transferred into
another medium
- this energy can then
be used in heat engines
to generate power
7. Describe how neutron capture by a nucleus of uranium-238 results in
the production of a nucleus of plutonium-239
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- when uranium-238 is struck by a
neutron it absorbs it into ins
nucleus, but does not fission
-by absorbing loose neutrons
uranium-238 can prevent nuclear
reactions from occurring
process:
- the fissioning of uranium-235
produces neutrons
-these are absorbed by uranium238, where they stay, which
converts the uranium-238 into
plutonium-239
8. Describe the importance of plutonium-239 as a nuclear fuel
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-the primary fissile isotope used to produce nuclear
weapons
- transuranic element (atomic number is higher than 92),
all are manmade
-can be split by both slow and fast neutrons, results in a
little more than 2 neutrons which can split another
plutonium nucleus, which creates a sustainable chain
reaction
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- radioactive
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- half-life: 24,110 years (really really long)
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-very efficient compared to other isotopes
Discuss safety issues and risks
associated with the production of nuclear
power
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The main safety issue arising from nuclear power is
the health effects due to radiation. Subatomic
particles can penetrate deep inside the human body
where they can cause cancer or harm cells.
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Another risk of nuclear power is the possibility of
reactor accidents. Most plants have a back-up
system that, in the event of a failure, will limit the
harm done. High doses of radiation can destroy
body functions and cause death within 60 days of
exposure.
Radioactive waste is a concern of nuclear energy.
Waste products must be isolated from contact with
people for long periods of time. “High level waste” is
converted to a rock like form and placed deep
underground, where it has an average lifetime of
one billion years
A common estimate is that the effects of routine
releases of radioactivity from nuclear plants may
reduce our life expectancy by fifteen minutes.
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A nuclear meltdown at a modern power plant should
be contained inside the reactor’s containment
structure, a steel or reinforced concrete structure that
encloses the nuclear reactor.
In 1986, the Chernobyl Nuclear Power Plant in the
then Soviet Union, suffered a meltdown when a
reactor exploded and the resulting fire sent four times
as much highly radioactive fallout than had been
released in the Hiroshima bombing.
Outline problems with producing nuclear
power using nuclear fusion
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Nuclear fusion is the process of joining together
several like-charged atomic nuclei to form a heavier
nucleus. Doing this absorbs or releases energy.
Nuclear fusion occurs naturally in stars and in the
sun. We have achieved artificial fusion but we
cannot completely control it thus far.
There are many problems associated with nuclear
fusion that we don't know enough about to do it
safely.
The likelihood of small industrial accidents including
the release of radioactivity is unknown.
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Nuclear fusion requires precisely controlled conditions
of temperature, pressure, and magnetic field. In the
event of a reactor being damaged, these conditions
would not be met. Therefore, the event of a
catastrophic major release of radioactivity is highly
unlikely.
Nuclear fusion releases small amounts of helium and
tritium, an isotope of hydrogen, which could be
harmful after a cumulative buildup.
Sankey diagram