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MAGNETICALLY CONFINED NUCLEAR FUSION: THE FUTURE OF
ENERGY
Nathan Knueppel ([email protected])
THE SOLUTION TO THE WORLD’S
ENERGY CRISIS
With the burning of fossil fuels contributing to increased
global warming, an effective, alternative form of energy is
needed that can sustain the world’s power requirements [1].
Nuclear fusion has the potential to replace our dependency on
coal and other fossil fuels, and, per research, provide clean
energy for millions of years [2]. The greatest challenges
facing nuclear fusion are: containing the plasma necessary to
carry out the fusion reaction, creating a reactor that can
generate more energy than it requires to run, dealing with the
radioactive materials generated by the reaction, and making a
reactor that is economically feasible. 35 nations of the world,
including the United States, are currently collaborating to
make energy from nuclear fusion a reality by utilizing
magnetic plasma confinement, in a project known as the
International Thermonuclear Experimental Reactor (ITER),
showing that, despite the obstacles, nuclear fusion is being
taken seriously as a solution worth researching [3]. I find
nuclear chemistry to be very interesting, and believe strongly
in protecting the environment before it is ruined by fossil
fuels. Thus, I believe that nuclear fusion confined using
magnetic fields, a prime example being the Affordable,
Robust, Compact (ARC) reactor being developed by the
Massachusetts Institute of Technology (MIT), has the
potential to provide the clean energy that the world needs.
WHAT IS NUCLEAR FUSION, AND HOW
DOES IT PRODUCE ENERGY?
Nuclear fusion occurs when two isotopes of hydrogen,
deuterium, which has one neutron instead of zero, and tritium,
which has two neutrons instead of zero, are combined to form
helium, a neutron, and energy [4]. To initiate the reaction, the
two atoms are heated to approximately 212 million degrees
Fahrenheit using microwaves, turning the gasses into plasma,
an electrically charged state of matter in which the electrons
of the atoms have been stripped away. The incredible
temperature makes up for the fact that the pressure present in
stars, the most common sources of fusion reactions, is
impossible to replicate for extended periods of time on Earth
[2]. These pressures have only been generated momentarily
University of Pittsburgh Swanson School of Engineering
11.1.2016
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when detonating thermonuclear warheads. Both pressure and
heat are required for fusion to occur, so a lack of one requires
an increase in the other. The neutron and energy released by
the fusion reaction generate heat, which is then used to
convert water into steam, driving a turbine that turns
mechanical energy into electrical energy, like how current
fission reactors generate energy [5]. These incredible
temperatures generated pose a problem, noted in “Fired Up,”
an article in the New Scientist scientific journal by David
Hambling and Richard Webb, that, “no conceivable reactor
material can withstand the heat of this plasma” [4]. While a
considerable obstacle, magnetic confinement provides a
solution.
Containing the plasma
The current solution for containing the plasma is known
as a tokamak. The ITER Organization defines a tokamak as
a, “donut-shaped vacuum chamber” around which super
magnets are coiled [6]. These magnets interact with the
electrically-charged plasma to confine the system within the
reactor, and are widely viewed as the most practical method
for making nuclear fusion feasible [2]. By holding the plasma
in place, a tokamak keeps the hydrogen isotopes close enough
to fuse. Containing the plasma is not the only problem facing
energy from nuclear fusion, however.
OBSTACLES TO NUCLEAR FUSION
The three other primary obstacles to nuclear fusion are
the cost of building a reactor, the efficiency of current
reactors, and the generation of radioactive materials. ITER,
which is being constructed in France, has already cost $21
billion, and is expected to cost a total of $40 billion before it
is finished [4,7]. In my opinion, with the cost being divided
amongst 35 nations, the reactor is not very expensive when
you look at the potential it holds. Unfortunately, once built,
prototype reactors have not proven cost-efficient, as there has
yet to be a reactor created that can produce more energy than
it requires to maintain the reaction [7]. I see this lack of
efficiency as a challenge engineers can tackle in designing a
reactor. The third obstacle is that the constant bombardment
of neutrons into the shielding materials of the reactor wall
weakens the structure, as the shielding is turned into
Nathan Knueppel
radioactive dust that settles in the reactor [2]. Despite these
issues, I remain confident that nuclear fusion is the best
solution to our energy needs. In fact, the ARC reactor from
MIT looks to address many of these problems in its design.
The ARC reactor: the next step forward
Several technological and design advances integrated
into the ARC reactor address the issues nuclear fusion faces.
For one, the ARC reactor utilizes new rare-earth barium
copper oxide (REBCO) superconducting tapes in its tokamak
design. These tapes produce much stronger magnetic fields
than current reactor designs, thus allowing for smaller,
cheaper reactors [7]. An important note for engineers is
presented in “A small, modular, efficient fusion plant” by
David Chandler from the MIT News Office, which states that,
“the achievable fusion power increases with the fourth power
of the increase in the magnetic field. Thus, doubling the field
would produce a 16-fold increase in the fusion power” [7].
The stronger magnetic fields generated in the ARC lead to a
roughly tenfold increase in the fusion power, which I believe
could be increased even further if engineers focus on creating
stronger super magnets. Any small increase in the magnetic
field results in an exponential increase in power, a
relationship that should be taken advantage of. The ARC
reactor’s design is more efficient too, and will produce
roughly three times more power than is needed to sustain its
reactions, being the first reactor to pass the “break-even”
point and generate more power than is required to maintain
the reaction [7].
To solve the issue of the shielding material being turned
into radioactive waste and weakening the reactor walls, the
ARC reactor utilizes liquid shielding that can be circulated out
and replaced easily [7]. Engineering neutron-resistant liquid
shielding materials will decrease the amount of radioactive
wastes created in a fusion reactor, making the energy cleaner.
I find the advances made by the team at MIT to be very
encouraging steps forward towards making energy from
nuclear fusion a reality, as the major flaws in fusion have been
addressed. I look forward to when the design is finished and
tests can be run. With the amount of work going into making
nuclear fusion possible, I think it is important to look at why
this energy is superior to other forms of power.
WHY PURSUE NUCLEAR FUSION OVER
OTHER ENERGY SOURCES?
The energy created by nuclear fusion is much greater
than the energy from other sources, the fuel materials will last
for millions of years, the reaction has no chance of resulting
in a meltdown, and the byproducts from it are much safer than
those of current nuclear energy sources. The energy released
from the reaction of one deuterium and one tritium atom is
17.6 megaelectron volts, approximately 10,000,000 times the
energy of a typical chemical reaction [5]. David Hambling
2
and Richard Webb from New Scientist compare the energy
from fusion to that of coal in their article, “one gram, or .002
pounds, of deuterium-tritium fuel yields the same combustion
heat as 10 metric tons, or 22046 pounds, of coal” [4]. The
difference in energy produced is staggering to me, and
constitutes a major reason to make fusion reactors reality.
The fuel for these reactions, while not common naturally, can
be produced from very common materials.
The article “Provide Energy from Fusion,” by the
National Academy of Engineering explains where the supply
of deuterium could come from. “Deuterium is a relatively
uncommon form of hydrogen, but water – each molecule
comprising two atoms of hydrogen and one atom of oxygen –
is abundant enough to make deuterium supplies essentially
unlimited” [2]. When describing what the source of tritium,
which is very rare naturally, would be, the same article had
this to say, “Simple nuclear reactions can convert lithium into
the tritium needed to fuse with deuterium. Lithium is more
abundant than lead or tin in the Earth’s crust, and even more
lithium is available from seawater”. The article finishes by
explaining that the supplies of both water and lithium on Earth
could power fusion reactions for millions of years. Since
seawater is so abundant, I see no reason why it can’t be used
as fusion fuel. The reactions carried out are also safe, and
produce safer waste that current energy sources.
The amount of fuel used in a fusion device is very small,
“about the weight of a postage stamp” per the Culham Center
for Fusion Energy’s article, “Introduction to Fusion” [8]. This
prevents any large nuclear accidents from occurring. As
challenging as it is to get a fusion reaction functioning, any
disruption causes the reaction to cease, another safety feature.
In addition, the radioactive materials generated will be safe to
recycle or dispose of in only 100 years, as opposed to the
plutonium-239 that can be generated in fission reactions,
which has a half-life of 24,000 years [8,9]. Best of all, the
reaction produces zero carbon emissions, and thus will not
further global warming.
CONCLUSION
With global warming becoming a growing concern,
energy from nuclear fusion stands poised to be the solution to
the world’s energy needs. The use of tokamaks and magnetic
fields to confine the plasma used in fusion reactions has
helped advance the feasibility of a functioning reactor. If
engineers and scientists worked towards developing stronger
super magnets and liquid shielding materials resistant to the
neutrons produced in a fusion reaction, the potential power
generated by a reactor could greatly increase, while the
byproducts would decrease. I believe that nuclear fusion is
the future of clean, sustainable energy, free from the dangers
of meltdowns typically associated with nuclear power, and
worth the efforts of engineers to finally see an almost
unlimited power source realized.
Nathan Knueppel
SOURCES
[1] “A Blanket Around the Earth.” NASA. 10.27.2016.
Accessed 10.29.2016. http://climate.nasa.gov/causes/.
[2] “Provide Energy from Fusion.” The National Academy of
Engineering.
2016.
Accessed
10.27.2016.
http://www.engineeringchallenges.org/9079.aspx.
[3] “What is ITER?.” ITER Organization. 2016. Accessed
10.27.2016. https://www.iter.org/proj/inafewlines.
[4] D. Hambling and R. Webb. “Fired Up.” New Scientist
Vol. 229. Issue 3058. 2016. Accessed 10.27.2016.
http://web.b.ebscohost.com/ehost/detail/detail?vid=7&sid=b
9959e18-ac0d-40e2-816b7dd67bb34408%40sessionmgr107&hid=128&bdata=JnNpd
GU9ZWhvc3QtbGl2ZQ%3d%3d#AN=112614073&db=aph
. p. 34-37
[5] “How Fusion Works.” Culham Center for Fusion Energy.
2012.
Accessed
10.29.2016.
http://www.ccfe.ac.uk/How_fusion_works.aspx.
[6] “What is a Tokamak?.” INTER Organization. 2016.
Accessed 10.29.2016. https://www.iter.org/mach/Tokamak.
[7] D. Chandler. “A small, modular, efficient fusion plant.”
Massachusetts Institute of Technology. 8.10.2015. Accessed
10.29.2016.
http://news.mit.edu/2015/small-modularefficient-fusion-plant-0810.
[8] “Introduction to Fusion.” Culham Center for Fusion
Energy.
2012.
Accessed
10.29.2016.
http://www.ccfe.ac.uk/introduction.aspx.
[9] “Backgrounder on Radioactive Waste.” United States
Nuclear Regulatory Commission. 4.3.2015. Accessed
10.29.2016.
http://www.nrc.gov/reading-rm/doccollections/fact-sheets/radwaste.html.
ACKNOWLEDGEMENTS
I would like to acknowledge my writing instructor, Amanda
Brant, for taking the time to advise me on how I can improve
my writing. I am grateful to have someone who can provide
specific examples of ways to fix my writing. I would also like
to acknowledge my friend, Julia Meikle, who helped me
correct the grammatical and phrasing mistakes I made. I
know you have work of your own to do, and am thankful that
you could take the time to help me as well.
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