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THE USE OF MOLTEN SALTS AND THORIUM IN LIQUID SOLUTION IN
NUCLEAR REACTORS
Brendan Schuster, bjs111@pitt.edu, Mahboobin 4:00, Kristy Sturgess, kms302@pitt.edu, Mena, 4:00
Abstract— As of January 2016, nuclear power stations
provided over 11% of the world’s electricity with reliable
power and without carbon dioxide emissions. This number
will surely increase as we continue to use nuclear power
plants. There are several problems concerning current
nuclear reactors: they use uranium, an extremely rare
element, they have safety issues, produce large amounts of
dangerous radioactive waste, and require large amounts of
money to run and to refine the uranium. In order for nuclear
energy to advance, we must engineer solutions to the
aforementioned issues. Using thorium instead of uranium
may be able to solve these problems. It is naturally more
abundant in nature and does not need to be refined and
purified like uranium does.
Current nuclear plants require electricity to cool off the
core if there is a need for an emergency shutdown. This is
greatly decreases the safety of nuclear plants, especially when
a meltdown can be catastrophic. The molten salt reactors are
inherently safer because they shut down without human
intervention. Molten salt thorium reactors are also cheaper
to construct than current uranium reactors because of the
innate safety features of using liquid fuels. This innovation
greatly increases the amount of energy we can harvest from
fission, and increase the efficiency of turning thermal energy
into electricity. Lastly, these reactors produce far less waste
than current uranium reactors, and this waste is harmful for
a much shorter time.
If implemented into the world today, we would have a
clean, sustainable energy that can efficiently reduce our
carbon emissions by replacing fossil fuels with nuclear
reactors that are fueled by thorium.
Key words- Breeding, Ethical Concerns,
Sustainability, Molten Salt Reactor, Thorium
Energy
THE NEED FOR CLEAN ENERGY
Fossil fuels are limited, non-renewable resources that the
world uses as a primary mean to generate electricity. In fact,
62.6% of energy production comes directly from coal and
natural gas [1]. However, 46% of carbon dioxide emissions
come from electricity and heat production [2]. One clear
University of Pittsburgh, Swanson School of Engineering 1
2016/03/04
downside to using fossil fuels is the production of carbon
dioxide. When this gas is released into the atmosphere, it
pollutes the air creating detrimental outcomes for our
environment, such as accelerating the melting of our glaciers,
and speeding up climate change [1]. There is a current drive
to increase the amount of clean energy production, which is
energy production that does not create carbon dioxide as a
byproduct or other unmanageable byproducts. Nuclear energy
can be the answer to our clean energy production problems.
France has shown that it is possible to run a country primarily
on nuclear power, providing 76.9% of their electricity from
nuclear energy [2]. There are a few problems we currently
face in the long term for current nuclear reactors, such as
finding a new nuclear fuel source besides uranium, increasing
the safety of nuclear reactors, and finding ways to dispose of
radioactive waste.
New Ideas for Nuclear Energy
Current global assessment models predict that in the
future, carbon-neutral energies will become extremely
important [3]. Carbon-neutral energy refers to energy
production without the emissions of carbon dioxide. We can
already see the shift starting to occur because in the past few
decades, there has been a growing emphasis on “green”
technologies. Currently, nuclear energy is the only carbon
neutral energy that can meet the increasing energy demands,
but it still has some problems [4]. Furthermore, if nuclear
energy wants to continue onward, it needs to greatly increase
the safety in terms of reducing radiation leakage, finding a
new source of fuel, and reduce the production of harmful
radioactive nuclear waste. The answer lies in a new
generation of nuclear reactors called molten salt thorium
reactors. These reactors can improve greatly on all aspects of
the issues presented. Thorium is a metal that can solve the
long term and short-term problems of current nuclear reactors
due to many factors including its abundance, waste
management, and safety concerns.
SUITIBILITY OF THORIUM
Thorium is three times more abundant in Earth’s crust than
uranium is. It has already been mined and accumulates from
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rare metal earth mining in countries such as China, Brazil, and
India [2]. Fortunately, thorium only has one isotope that is
usable for fission. Fission is the process of splitting an atom
in order to create energy. Uranium’s primary isotope used for
fission, U-235, comprises only 0.7% of the uranium we find
in the ground [1]. All of the thorium mined from the ground
can be used for nuclear fuel, which makes it more favorable.
Molten salt thorium reactors will utilize thorium more
effectively, efficiently, and at a cheaper cost than current
nuclear reactors [2].
Thorium is immensely energy dense; you can hold a
lifetime’s supply of energy in the palm of your hand [5]. The
MSR can harvest almost all of the energy that thorium gives
off compared to the low efficiencies of current uranium plants
[1]. In the United States alone, we have a 32,000 metric ton
stockpile of thorium buried in a shallow trench in Nevada.
This could produce almost as much energy as the United
States uses in three years [5]. However, we aren’t the only
country to have reserves of thorium. Australia, Norway, and
Canada all have large reserves of thorium as well.
Internationally, uranium levels are too low to support the
current nuclear programs for years to come. China and India,
two of the most populous places on Earth, do not have enough
uranium to fuel nuclear reactors. However, they have large
amounts of thorium [4]. Molten salt reactors use primarily
thorium as the fuel, but they can also use spent nuclear fuel to
run. This means we can use radioactive waste in the molten
salt design to create energy. The current radioactive waste is
a nuisance to deal with and it is stockpiling more and more as
we continue to use uranium reactors. It does not currently
affect the environment, but a leakage of radiation is extremely
harmful. Nuclear plants must hold their nuclear waste for
years in water tanks until it is cool enough to be buried deep
underground [1].
program ended the research of thorium molten salt reactors
for a long time. Since then, different designs have shown that
they can solve the problems the engineers at Oak Ridge faced.
After the program termination, thorium molten salt reactors
received almost no international funding, and improving these
designs almost came to a standstill [4].
HOW IT WORKS
Current designs for the molten salt reactors fixed the
plumbing issue by implementing a two-fluid design, meaning
there are two ways for the liquid to enter and exit the core.
This two fluid design also means that within the reactor, there
is something called a blanket and a core. The core (green
shaded area between white rods in Figure 1) of our nuclear
reactor contains fissile 233U, or spent uranium fuel, mixed
with fluoride salts in a liquid solution. Uranium bonds with
the fluoride creating liquid uranium tetra-fluoride (UF4). The
blanket solution (in white rods and plumbing channels in
Figure 1) will consist of thorium tetra-fluoride, beryllium, and
lithium. It will be kept molten through the radiating heat of
the core. [6]. The fissile material is needed to start the reaction
because thorium is not naturally radioactive. The thorium
nucleus needs to be bombarded with neutrons to start any sort
of chain reaction [6]. When the blanket solution is bombarded
with neutrons from the core, the thorium-232 (regular thorium
isotope) enters beta decay, meaning it loses an electron and a
neutron is transformed into a proton [6]. The resulting
thorium-233 with an extra proton beta then decays into
protactinium-233, which decays again into 233U (UF4), our
original fissile material in the core.
Thorium Reactors in the Past
The idea of molten salt nuclear reactors has been around
since the 1950s. Oak Ridge Laboratory was the first in the
United States to begin researching the liquid fluoride salt
design [4]. This design showed great inherent safety. The
scientists were able to shut the reactor down when they went
home for the weekend. This shows that even sixty years ago,
these were much safer than traditional uranium water reactors
[5]. One of the problems with their design was that if there
was one crack in the plumbing of the reactor, the entire system
needed to be replaced. This was due to the complicated
reactor. Unfortunately, the reactor was shut down in the 1970s
for reasons that were more political than technical [4]. During
this time, plutonium was useful for creating nuclear weapons,
so uranium fission was highly valued for the plutonium rich
nuclear waste. Now that priorities have shifted, the nuclear
waste from MSR reactors has many more benefits [7].
The issues with the corrosion of the pipes lead to the
termination of the program, even though the problems were
well on their way to being addressed. This termination of the
FIGURE 1 [7]
MSR reactor core with thorium blanket in white rods.
The molten salt blanket enters and exits the core accepting
neutrons. Impurities are cleaned out before reintroducing
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liquid to the core. In the right side of the figure, pure liquid
fluoride salts pass heat to turbines, creating energy.
We must then move the resulting U233 from the blanket
solution into the core; this is where the benefit of the liquid
solution comes in handy. By bubbling fluoride gas through
the blanket solution (Off gas systems), UF4 turns into gaseous
uranium hexafluoride (UF6), while not affecting the rest of the
thorium tetra-fluoride [6]. This means the fission products
either quickly form stable fluorides that will stay within the
salt, or are volatile and insoluble so they can be continuously
removed [4]. The gaseous uranium hexafluoride is bubbled
out and then reduced back down to uranium tetra-fluoride.
This fissile material will then be added into the core solution
to produce more heat and to continue the reaction [6]. The
liquid solutions require the use of fluoride salts because the
ionic bonds formed between the metals and salts withstand an
extremely large amount of heat and radiation before breaking
down. The liquid solution also allows harmful byproducts of
the fission process bubble out of the solution (chemical
processing in Figure 1). Whatever is not bubbled out of the
liquid solution will be kept and instead, we will fluorinate the
core solution. This takes all of the uranium tetra-fluoride from
the core and converts it to UF6 like in the blanket solution [6].
Then, we can reduce the UF6 from the core back to UF4. We
can then successfully remove impurities from the core and
from the blanket solution that is impossible with solid fuel
uranium rods in use today.
The extremely high temperature is also much better suited
for heat transfer [5]. The salts can reach extreme temperatures
without boiling since their boiling point is incredibly high due
to their ionic bonds. Boiling water reactors use low power
turbines to create energy with a lower energy transfer. Our
primary salt that runs through the core passes heat off to
another liquid fluoride, which will directly be used to turn a
power turbine and create electrical energy. In fact, these
reactors can work at an efficiency of 45% compared to regular
nuclear plants or coal plants, which have an efficiency of
about 33% [6].
Figure 2 [9]
Fission process of MSR breeding
At the end of the process, the U233 releases neutrons that the
thorium atom accepts, continuing the energy producing
process.
Thorium to Uranium Breeding Cycle
Thorium atoms are also much more likely to collide with
neutrons in the liquid solution because many impurities, like
xenon, are bubbled out of the solution. This provides a much
better neutron economy compared to normal uranium rods,
which become more impure with time. Neutron economy
refers to the suitability of the surroundings for thorium atoms
and molecules to accept a neutron. The greater the neutron
economy, the more likely thorium will convert into
protactinium, then soon after, uranium [6].
MSR reactors were able to reach breeding when they were
researched at Oak Ridge. Since then, we have been able to get
the breeding coefficient up to 1.13 [8]. This means that 113%
of the uranium or fissile material to start up the reactor core
was present after all the thorium is spent. This is incredibly
efficient because thorium would be the only metal that needs
to be added into a blanket solution to continue the fission
process. This is an important aspect not only because of
efficiency, but also because transportation of radioactive
materials can pose a risk to the public. The only radioactive
material that needs to be brought to the plant would be the
initial fissile startup material. Using unrefined uranium or
transuranic wastes, such as plutonium, as the startup material
will lower the initial breeding ratio, but it is still possible to
keep the ratio above one. Keeping the transuranic wastes in
the core can slightly decrease the neutron economy, but we
must consider sacrificing slight efficiency because these
materials that were once considered wastes are used as fuel
for more fission.
Efficiency and Breeding
Another useful feature that the molten salt reactor has is
breeding. In nuclear terms, breeding refers to producing more
fissile material as the reactor core creates energy. Breeding is
extremely useful because the thorium, which is a naturally
unstable isotope, is hit with a neutron turning it eventually
into fissionable uranium. When all of the thorium is used up
in the blanket solution, the core still has fissionable material
inside of it [8]. Figure 2 shows the process of thorium decay.
First thorium-232 accepts a neutron, then it beta decays into
protactinum-233. After this it decays into uranium-233,
releasing neutrons to start the process again.
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The breeding economy remains the best when graphite is
used as the moderator. A moderator works by slowing down
the neutrons blasted from the core atoms, because the
neutrons are moving too fast to collide and stay with another
atom’s nucleus [6]. When the neutron is slowed down, the
thorium has a higher chance of accepting the neutron to start
the fission chain reaction. Graphite also allows for the core to
run on low enriched uranium or transuranic wastes. To further
improve breeding coefficients, we can remove the
protactinium from the blanket solution and allow it to break
down into uranium in a separate area, because it has a halflife of 17 days (the protactinium will break down into
uranium) [4]. By removing these atoms from the blanket, we
increase the neutron economy and the chance that a thorium
atom will transform into protactinium, and later uranium.
One disadvantage to the higher breeding ratios and
increased neutron economy is the damage inflicted to the
structural materials that hold the core and blanket salts. When
the graphite moderator slows down a neutron, it is colliding
with a neutron and then it bounces back off. MSR reactors can
run at a higher temperature and power production level, but
this means that the graphite lifespan can greatly decrease.
Estimations indicate that the graphite can last from 2.7 to 30
years, depending on the power production output [8].
Graphite is a very cheap and abundant material, so replacing
it will not be very expensive. Despite this, we are concerned
with efficiency and sustainability of every aspect of the
reactor. The lifespan of the graphite moderator and the
plumbing is one of the biggest engineering problems we have
yet to solve. However, breeding is an extremely efficient
mean of fission that current uranium reactors cannot come
close to achieving and this makes energy production with the
MSR an invaluable form of energy production [6].
for nuclear weapons like waste produced from current
reactors. If every developing country starts a nuclear program
with uranium reactors, they will have material to easily make
nuclear weapons. If thorium energy is deployed here, they
will have clean energy without the means to produce nuclear
warheads.
Certain designs of MSR reactors are incredibly efficient
and sustainable. One design has been called the “30 year
design” because it can keep a high energy conversion ratio
without any fuel processing beyond chemistry control
(purifying the salts) while still maintaining a high breeding
ratio and great utilization of the uranium after it has been
converted from thorium [4]. The lower power density in the
core increases the lifetime of the graphite to 30 years and
allows for continuous running until all the thorium is spent.
This is a great accomplishment because current uranium
reactors are incapable of breeding because the fission of
uranium does not create viable products for continuation of
fission in the same reactor, and there is no way to purify the
fuel [6]. Furthermore, current reactors must shut down to
rotate uranium rods, which is costly for the plant and
inefficient because the uranium rods are still going through
fission, meaning we are wasting energy.
More Reasons to Make the Switch
The efficiency of current uranium reactors is dismal. Fuel
rods need to be cycled through the core and some current
uranium plants need to shut down every 18 months to cycle
out uranium fuel rods [6]. The solid fuel rods make it
impossible to remove impurities, such as xenon, which
undermines the efficiency of the fuel because it can accept a
huge number of neutrons without breaking down into smaller
atoms. Since it appears in solid fuel rods, there is no way to
remove it and the neutron economy drops far below the
efficiency of the MSR design [6].
While xenon quickly decays, it can set the fission chain
reaction off balance, which if not managed carefully by taking
the rods out and rotating them in cycles in the core, can cause
an unstable core and an explosion like the Chernobyl disaster.
At the Chernobyl reactor, a temporary chemical imbalance in
a fuel rod caused it to overheat, resulting in a meltdown that
leaves the surrounding area uninhabitable to this day [1].
After this accident, ethical issues of safety were fully realized.
WHY WE SHOULD SWITCH FROM
URANIUM
These MSR reactors have been selected as one of the
generation IV designs, meaning it highlights efficiency (in
terms of cost and energy), safety, and are proliferation
resistance [1]. Proliferation resistance is an ethical concern
that will be discussed later in the paper. Currently, nuclear
energy is not recognized as an effective countermeasure to
global warming because of the concerns it produces with
nuclear proliferation, safety, and radioactive waste [4]. Also,
according to a global assessment model, nuclear fission
energy may not produce much of the world’s energy if the
issues of safety, waste disposal, and proliferation are not
adequately addressed [2]. Proliferation resistance is the
utilization and deployment of a nuclear power plant without
significantly increasing the abundance of nuclear weapons [6].
Generation IV plants are not expected to deploy until 2030
because they are still under development [10]. The selection
means that this design shows great potential for use of longterm sustainability. Thorium’s nuclear waste cannot be used
Cost Efficiency
If this innovation is going to acquire funding, the cost
efficiency of energy production has to be reasonable. With
higher efficiency in terms of using all of the energy that our
thorium fuel contains, molten salt reactors are more efficient
than uranium reactors. Because of the higher temperatures
that exist in the core and blanket salts, the thermal to electrical
energy efficiency of the MSR is much higher than current coal
and uranium plants [6]. The cost right now is high because the
experience curve is very small and we must consider that there
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has been almost no funding for this innovation internationally
[11].
A cost analysis conducted in Canada estimated that
running a thorium plant is more financially attractive than
uranium plants due to the higher burn up of thorium fuel [11].
The thorium plant is estimated to produce $72/MWhr
compared to $74/MWhr for current uranium plants. The
construction of these plants is also cheaper because they do
not require the huge pressure dome that encloses water
reactors because MSRs run at normal atmospheric pressure.
It saves a vast amount of money during construction when
you do not need a 19-centimeter thick steel dome to contain
the pressure in the event of the water boiling [5]. Some may
also argue that the fluoride salts are expensive to use, but they
are currently used in the current uranium enrichment process
for uranium which is the type of fuel that all of the current
uranium reactors need in order to run [6].
The mining of thorium is also cheaper because there is
only one isotope; there are stockpiles of our fuel lying
dormant and ready to use. The cost of holding transuranic
waste is also costly and most plants must store it on site. There
is 10,000 times less waste produced from the MSR than
current reactors and it is not nearly as volatile [4]. This
innovation is exponentially more efficient if these plants are
estimated to be cheaper to build and run, even when a definite
design has not been chosen.
Bringing in fuel and storing fuel becomes much cheaper,
also. There is a huge reduction in the amount of waste
produced and fuel transportation will not require extra safety
measures, resulting in cheaper production of energy in the
long term [7].
Thorium does not produce plutonium when it undergoes
fission, and this is the primary element that is used in nuclear
weapons. Current reactor sites and disposal sites are
becoming plutonium mines [4]. Since it poses such a large
risk, nuclear energy may not be the best option in the future if
there are other carbon-neutral energies because of the
production of plutonium. Another remarkable aspect of MSR
designs is that they can actually utilize plutonium, or spent
transuranic waste, as a startup fissile material in their cores
[8]. Using up dangerous materials instead of producing them
shows that we can finally utilize our transuranic wastes.
In the United States, nuclear waste disposal is a huge
concern because there are no sites where plants can legally
dump their wastes [10]. It is extremely dangerous to store
nuclear wastes on site of the reactors, but many nuclear sites
have begun to do this because there is nowhere else to put it
[1]. This is not sustainable in the long term because the
transuranic wastes radiate dangerously even after the plants
will close. It is ridiculous to think that a current nuclear
reactor will be running in 50,000 years, but the dangerous
wastes will still be producing harmful radiation. This means
that we will eventually have to deal with these wastes
somehow instead of pushing the problem under the rug.
There have been projects such as Yucca Mountain to store
this nuclear waste. However, after construction was already
started, the government shut it down and left nuclear facilities
with nowhere to place their radioactive waste. Now, there are
only temporary storing facilities [5]. The dangerous wastes
also make current reactors a place where someone can get
their hands on plutonium that can then be used to create
nuclear weapons. The MSR plants would not have to worry
about where they will need to send their waste off and be no
such targets for plutonium because they do not produce
useable radioactive products [6].
ETHICAL CONCERNS
As demonstrated, it is evident that molten salt reactors are
superior in efficiency and waste production. We must also
consider the aspect of proliferation resistance now because as
more countries develop nuclear energy and technology, they
will also gain the knowledge of how to create nuclear
weapons. Thorium reactors were not chosen for further
research because during this time they were starting research,
there was an emphasis on plutonium production [4].
The United States was the first country to create nuclear
weapons and more plutonium was a good thing. This was one
of the reasons the government decided to fund uranium plants
instead. Water-cooled reactors also seemed ideal because
there is no shortage of coolant, and water-cooled reactors
would work perfectly on submarines for this reason [4].
Priorities since then have greatly shifted because we are not
in a nuclear arms race and limiting the production of nuclear
weapons is the ethical thing to do. As stated above, using
thorium as the primary element in nuclear reactors will reduce
the amount of nuclear weapons being created and it will
diminish the tension on nuclear warfare.
Safety Issues
Thorium molten salt reactors are superior to current plants
as well in terms of safety. Unlike current reactors, these plants
can shut down without electricity, and even human
intervention. The salts are kept running through the reactor
while a salt plug is kept frozen by blowing cool gas over it
(refer to Figure 1). If the power goes out, cool gas stops
blowing on the frozen plug, and the heated liquid salts from
the reactor melt it, and the liquids drain through a pipe into a
drain tank [5]. The liquid fuel salts do not overheat and boil
like the water does in current reactors, so once in the drain
tank, the fuel will cool down on its own. Current uranium
plants require electricity to keep water pumping through the
core to avoid overheating the fuel rods [1]. Since there is no
need for a huge steel dome, these reactors can be built in a
more compact area and there is almost no threat of a
meltdown because of how easy it is to shut down the reactor
[4]. This incredible safety allows these plants to be built in
high-energy consuming areas and around cities due to almost
Proliferation resistance
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no threat of a meltdown.
Inherent safety is something that we must be concerned
with because the safety and well being of the public is of
utmost importance. Lastly, the waste produced from these
plants is far less dangerous as time goes on than current
transuranic wastes [4]. This is because the MSR can remove
impurities from the liquid fuel as the reaction continues unlike
the solid uranium rods, and reintroduce any radioactive
materials until they absorb a neutron and undergo a fission
reaction [2]. Solid uranium rods become polluted with heavier
actinides such as plutonium, americium, and curium, that
leave it dangerously radioactive for extremely long amounts
of time [6].
With the idea of feasible nuclear breeding, transportation
of volatile nuclear fuel into the plant will not be needed.
Thorium will need to be transported to the plant, but it is not
radioactive so there is no danger. Less waste is also produced
because of almost 100% burn up of thorium into other
elements [8]. Waste management of the small amount of spent
fuel will not be as big of an issue as uranium plants. The
byproducts of highly enriched uranium, which is used in
current uranium reactors, produce transuranic waste that is
extremely dangerous for up to 100,000 years. The waste
produced from the MSR remains at hazardous radio-toxicity
levels for only a few hundred years [2].
It is not surprising to see that other countries around the
world have realized the potential that thorium energy has.
China is currently looking into implementing thorium reactors
along with India. The reactor design China is using will offer
enhanced safety and proficient economics compared to
current nuclear reactors [10]. India is implementing a more
aggressive plan for thorium energy with several breeder
reactor designs being built. Both of the plans that India and
China are applying construct solid fuel reactors instead of
liquid fuel, mainly because the molten salt reactor innovation
is still in research and development. The China Academy of
Sciences has taken headway on researching the MSR design
and they hope to obtain full intellectual property rights to this
innovation. They are currently building a 5 MW reactor
prototype that will hopefully be running by the year 2020. The
United States and China are collaborating on researching
liquid salt cooled reactors right now in hopes to gain
experience using liquid salts as a cooling system before fully
employing liquid salt as a source of fuel. This research also
aims to increase the lifespan of the graphite moderator and
plumbing systems [10].
Why This Should Matter
If we want truly safe, clean energy then using thorium is
our best choice. This advancement can produce huge amounts
of energy with a fraction of the waste than current uranium
nuclear reactors are generating. With no risk of meltdowns,
we can produce the cleanest energy possible at a cheaper price
than current coal plants or current nuclear reactors. As energy
demands increase internationally and fossil fuel supplies
decrease more rapidly, the need for engineers to find a
sustainable new source of energy becomes more imperative.
This design offers the best solution to make a fast and cost
efficient conversion from fossil fuels, paired with the great
nonproliferation that would make it reasonable to employ this
technology in the developing world where fossil fuel
consumption is an exigent problem [6].
MOVING FORWARD WITH THORIUM
If this energy is more efficient than typical uranium, then
why is it not already in place? It has been proven extremely
difficult to restart the clock on nuclear energy [6]. The entire
world is already so deeply integrated with uranium energy and
it would be incredibly costly to construct upwards of a
thousand molten salt reactors around the world for a full start
up. Only in the past twenty or so years have the concerns of
nuclear waste disposal and carbon neutral energy come into
play [6]. One must also keep in mind that there has been
almost no funding for this type of reactor since the Oak Ridge
plant was shut down [4]. The push for increased safety only
occurred after the accident at Fukushima [12]. When an
earthquake caused the power to go out at water-cooled
uranium reactor, there was no way to cool the uranium rods
or to pump the water through the core. The water turned into
steam, causing immense pressure in the reactor. An explosion
occurred that spewed radiation from the core for six days.
This accident showed that nuclear reactors could be prone to
extreme situations such as natural disasters. When one
accident can lead to such damage, you have to be careful not
to place nuclear reactors so close to cities because over
100,000 people had to be evacuated from the surrounding area
[12]. There is definitely a possibility of this happening again
in the future, which is why this issue of safety needs to be
addressed.
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ACKNOWLEDGEMENTS
We would like to thank Allison Bundy, our co-chair, for
bringing clarity and brevity to our proposal. We would also
like to thank Janine Carlock for her helpful input and tips.
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