The Problem with Nuclear Fusion
The Problem with Nuclear Fusion
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Credits:
Writer/Narrator: Brian McManus
Editor: Dylan Hennessy
Animator: Mike Ridolfi
Animator: Eli Prenten
Sound: Graham Haerther
Thumbnail: Simon Buckmaster
References:
[1] https://aip.scitation.org/doi/10.1016…
[2]
http://hyperphysics.phy-astr.gsu.edu/…
[3] http://hyperphysics.phy-astr.gsu.edu/…
[4] https://world-nuclear.org/information…
[5] https://www.osti.gov/servlets/purl/68…
[6] https://www.iter.org/sci/FusionFuels#…
[7] https://link.springer.com/article/10…
[8] https://www.iter.org/sci/MakingitWork…
[9] https://www.sciencedirect.com/science…
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Thank you to AP Archive for access to their archival footage.
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Content
0.31 -> Nuclear fusion has been a pipedream for decades.
4.52 -> Always 20 years away.
5.98 -> Never 19.
6.98 -> It’s easy to get jaded about this technology
and write it off as impossible, especially
13.33 -> when nuclear fission energy already exists
and is being underutilised.
17.81 -> But, by the end of this video, I hope that
I can change that feeling and get you as excited
24.33 -> as I am about the potential of this technology.
28.49 -> If we, as a civilization, actually pull it
off and invent a cost effective nuclear fusion
34.82 -> power plant it would change the face of society.
38.91 -> Clean safe fuels will allow every country
in the world to benefit from this technology.
47.01 -> Allowing countries around the world to be
energy independent, preventing one of the
51.06 -> leading causes of conflicts around the world,
as we fight for control of energy sources.
57.14 -> Cheap, reliable and abundant energy is the
foundation of every sci-fi utopian society.
64.43 -> It would solve our issues with climate change.
67.1 -> Allow us to electrify industries that require
fossil fuels, like steel smelting.
72.21 -> Allow us to create entirely new industries
that have been held back by energy costs,
77.48 -> like water desalination.
79.42 -> Providing the world with fresh clean water
to irrigate our lands and turn barren wastelands
84.74 -> to fertile pastures.
86.46 -> Ushering in an era of clean, safe abundance,
a utopian future that has been dreamed of
92.689 -> for decades.
94.5 -> Nuclear fusion experiments have been underway
since the very earliest years of the cold
99.619 -> war, with the first generators firing up in
the 1950s in both the USA and USSR.
106.4 -> The Soviet Union approached the problem with
a Tokamak design, while the Americans used
110.99 -> a slightly different approach, the stellarator.
113.88 -> Each design attempts to solve the same problem.
117.11 -> Fusion in essence isn’t terribly complicated.
120.49 -> We can make new elements by combining smaller
elements, and in the process release a lot
125.84 -> of energy.
127.04 -> However, to successfully combine elements
we need to overcome the electromagnetic repulsion
132.92 -> that pushes them apart.
133.92 -> Like pushing two north poles of a magnet together,
atoms will repel each other.
138.76 -> In order to force them together we need to
input a tremendous amount of energy, but we
144.48 -> can’t just grab individual atoms and force
them together like magnets.
149.15 -> Instead, we create a plasma, essentially a
cloud of changed ions which, thanks to their
155.599 -> charge, can be manipulated by a magnetic field.
159.28 -> We can then confine the plasma within a magnetic
field preventing the ions from hitting the
164.129 -> fusion generator walls, and gradually raise
its temperature to extremely high temperatures
169.59 -> that would otherwise melt every solid material
in the universe.
174.81 -> Raising the temperature of the plasma causes
the ions to move faster and faster.
180.01 -> Raising the ions' kinetic energy so high that
their speed alone allows them to punch through
185.37 -> the electromagnetic repulsion and collide.
189.19 -> Both of these designs, the Tokamak and Stellator,
use slightly different methods of magnetic
194.9 -> field confinement, generated by massive superconducting
magnets, to achieve fusion.
201.22 -> The Tokamak became the leading design today
as a result of a release of information from
206.68 -> the USSR on the tokamak design in 1968, which
showed a tremendous jump in energy efficiency.
214.569 -> However, both designs used the same fuels.
218.43 -> The exact reactants we use have a huge effect
on how much energy we need to put in, and
223.65 -> what we get out at the end.
226 -> Most reactions use two isotopes of hydrogen.
228.39 -> A regular run of the mill hydrogen has one
proton in its nucleus with one electron in
233.98 -> orbit.
234.98 -> We could perform fusion with this kind of
hydrogen, but the energy we can extract out
239.5 -> of the reaction is very low.
242.21 -> Instead we frequently combine deuterium and
tritium together.
246.06 -> Where hydrogen normally has one proton and
one electron and no neutrons, deuterium has
251.829 -> one proton, one electron and one neutron,
while tritium has one proton and one neutron
257.94 -> and two neutron.
259.9 -> This combination is used for a couple of reasons.
262.69 -> First, it has the largest probability of giving
us the exact result we want.
268.259 -> Other reactions, like a regular hydrogen to
hydrogen reaction, have a very high probability
273.46 -> of creating Helium 2, which is unstable and
almost instantly decays into 2 regular hydrogens
280.54 -> again, and releases very little energy in
the process.
283.75 -> [2]
284.75 -> They have a lower probability of combining
to form deuterium, the reaction we actually
289.32 -> want.
290.32 -> Which then go on to fuse to form helium 3
and finally helium 4.
296.199 -> This is the reaction chain that powers the
Sun, but the Sun has an unfathomable amount
302.139 -> of particles making the probability issue
completely irrelevant AND the crushing gravity
308.56 -> needed to create the conditions needed for
fusion.
312.57 -> We need to supply those particles and the
energy needed to combine them ourselves, and
318 -> if we can’t extract more energy than we
put in, that’s just a science experiment,
323.169 -> not an energy source.
325.05 -> We have successfully created many many fusion
reactions here on Earth, in fact, I witnessed
331.79 -> the bright pink flashes of fusion myself while
visiting Helion recently.
337.039 -> We know how to achieve fusion.
339.16 -> The problem we are now trying to solve is
lowering the energy we need to input, while
343.74 -> maximising the energy we can extract.
346.419 -> So, step 1, we need fuels that require less
energy input that release more energy.
352.62 -> That’s where deuterium and tritium come
in.
356.1 -> When combined they have a very high probability
of creating helium 4, and release on average
362.41 -> 17.6 Mega Electronvolts (MeV) for each and
every fusion event.
368.63 -> For comparison, Uranium 235 produces about
11.4 times this energy for each fission event
375.31 -> (200 MeV), but on a mass basis, that deuterium
tritium fusion reaction releases over four
381.53 -> times as much energy as uranium fission, and
produces no dangerous radioactive products.
388.44 -> Helium is actually quite a useful byproduct,
being used to cool MRI machines’ superconducting
394.22 -> magnets, to fill rocket tanks after their
propellant has been expended to prevent them
398.62 -> from exploding, and occasionally to make your
voice sound like Wendover Productions 6 years
404.38 -> ago.
405.38 -> Followed by this voice clip: https://youtu.be/6Oe8T3AvydU?t=539
409.58 -> And we will eventually run out of the gas,
so having a way to make it ourselves would
414.35 -> be a nice back up.
416.5 -> Deuterium is fairly common on earth, occurring
naturally in seawater.
420.53 -> Making up about 0.02% of hydrogen in seawater.
424.569 -> And because deuterium has an extra neutron,
it makes that water molecule heavier, giving
429.759 -> it its name.
430.97 -> Heavy Water.
432.539 -> That difference allows us to separate it through
a number of means.
436.62 -> Vacuum distillation allows us to take advantage
of heavy water's higher boiling point, while
442.11 -> the girdler sulphide process separates heavy
water through chemical reactions.
447.28 -> We can then simply electrolyse the heavy water
to separate the deuterium
451.25 -> However, one of the issues facing nuclear
fusion is the rarity of tritium.
456.97 -> Our primary source of tritium is nuclear reactor
moderator pools, which are often filled with
462.21 -> heavy water.
463.68 -> These pools are designed to absorb the high
energy neutrons given off during nuclear fission,
469.61 -> and in doing so can become tritium.
472.139 -> A hydrogen with 2 neutrons.
474.19 -> [5]
475.19 -> This source of tritium is becoming less prevalent
as nuclear power plants are gradually being
479.449 -> shut down around the world due to competition
from cheaper forms of electricity.
485.14 -> Currently total global reserves of tritium
is estimated at just twenty kilograms, which
490.491 -> is not a lot considering ITER program, the
massive internationally funded fusion generator
495.94 -> being built in France at the moment, estimates
a commercial reactor will need 300 grams of
502 -> tritium every day to generate 800 MegaWatts
of electrical power.
507.169 -> Meaning we would eat through the entire global
supply of tritium in just over 2 months.
513.05 -> [6] 800 megawatts is enough to cover about
2% of France’s peak power consumption.
518.53 -> Even if we could continue sourcing Tritium
from nuclear fission reactors, they only produce
523.39 -> about 100 grams each per year.
525.68 -> [7]
526.68 -> This is a major problem, however we do have
a solution in mind.
530.93 -> We can use the high energy neutrons spit out
from the fusion reactions to do a bit of alchemy
536.99 -> wizardry.
538.19 -> When those high energy neutrons encounter
lithium, they can split the lithium into tritium
543.36 -> and helium. [7] Providing a steady supply
of tritium right where it’s needed.
548.67 -> This is done in what is called a blanket around
the fusion chamber.
552.79 -> The design of the blanket is one of the most
challenging parts of Tokamak fusion generator.
557.72 -> ITER will test over 180 design variants of
this blanket that will line the donut shaped
565.11 -> interior.
566.11 -> Because, the blanket needs to do a lot more
than just breed tritium.
570.63 -> It is also where the energy of the fusion
reactions gets converted to heat.
574.93 -> 80% of the energy of the tritium deuterium
fusion reaction is carried away by those high
580.52 -> energy neutrons in the form of kinetic energy.
584.399 -> We need a way to convert that kinetic energy
to electricity.
587.72 -> [8]
588.72 -> As the fusion reaction rages in the centre
of the magnetically confined plasma, neutrons
593.44 -> begin to erupt outwards, unaffected by the
magnetic field thanks to their neutral magnetic
599.26 -> charge.
600.75 -> Tokamaks convert the energy of these tiny
particles by slowing them down in the blanket,
606.14 -> trading their kinetic energy with atoms in
the blanket to heat energy.
610.7 -> This heat energy is then captured by high
pressure water being pumped through cooling
614.92 -> channels, converting it to high pressure steam
to drive a steam turbine.
620.15 -> Humanities tried and tested method of creating
electricity.
624.23 -> The material that fulfils this role needs
some other unique properties.
628.3 -> First, in order to optimise for heating AND
tritium breeding, we need the material to
634.04 -> be a neutron multiplier.
635.529 -> When the high energy neutron from the fusion
reaction enters the blanket wall we want it
641.09 -> to strike an atom inside the blanket, and
release 2 neutrons.
646.83 -> Creating an additional neutron that allows
the blanket to fulfil both roles of generating
651.65 -> heat AND tritium.
654.25 -> Beryllium is currently the leading candidate
for this role.
657.75 -> When the neutron strikes it, it splits into
two helium 4 atoms and 2 neutrons.
662.512 -> Multiplying our first neutron and allowing
our blanket to generate tritium and more heat.
664.28 -> Beryllium, the same material used for the
James Webb Telescope mirrors, is the material
668.91 -> of choice because the helium byproduct does
not contaminate the plasma, and critically,
675.529 -> the material retains little tritium within
itself.
679.29 -> We need the tritium to naturally escape the
metal, partially because we need to collect
683.709 -> the gas to replenish our fuel, but also because
tritium is explosive, just like normal hydrogen.
690.5 -> .
691.5 -> However, Beryllium does have its problems.
693.26 -> First, the sheer quantity of beryllium a commercial
fusion reactor will require.
699.06 -> Current designs call for between 216 to 560
tonnes.
704.459 -> This is an issue because beryllium is extremely
expensive, due to the limited supply of the
710.25 -> material.
711.76 -> Annual global supply last year amounted to
only 260 tonnes.
716.329 -> The entire annual global supply of beryllium
could just about build one generator.
722.18 -> Next, there are safety issues.
724.6 -> Beryllium can contain large quantities of
uranium.
727.97 -> China’s beryllium blanket module contains
100 parts per million uranium.
732.959 -> So, 0.01 percent of the blanket is composed
of uranium.
738.31 -> This isn’t an issue for most components
that are usually made out of beryllium.
742.57 -> Like the beryllium, aluminium, copper engine
pistons that were banned from Formula 1 in
747.75 -> 2001.
748.75 -> However, it becomes a massive problem when
the uranium is exposed to those high energy
753.64 -> neutrons.
754.64 -> The same kind of neutrons that split uranium
in fission reactors.
758.86 -> This creates fissile isotopes, or, in other
words, it makes the beryllium radioactive.
763.92 -> [9]
764.92 -> If there were 30 parts per million of uranium
to beryllium, in a commercial scale fusion
769.29 -> reactor, that would mean there is 17 kilograms
of natural uranium and 123 grams of Uranium
777.48 -> 235, the uranium needed for fission reactors.
781.23 -> The byproducts of this ura nium would make
disposing of the blanket at the end of the
785.65 -> generator's life incredibly difficult.[9]
788.949 -> This all points to one major problem that
I see with Tokamak fusion reactors.
795.029 -> Even if we manage to reach net energy output,
these generators don’t solve the biggest
800.22 -> problem holding nuclear energy back.
803.29 -> Cost.
804.3 -> Nuclear fission power is a wonder technology
of the last century.
808.16 -> It promised abundant, clean, cheap electricity.
811.49 -> A technology that we scarcely even dreamed
of 2 centuries ago, as we first discovered
816.47 -> the existence of the atom.
818.67 -> Yet, we are closing down nuclear fission reactors
all across the world when we need that clean
824.97 -> power more than ever, because it’s uneconomical.
830.06 -> The cost of building a nuclear fission reactor,
and dealing with the radioactive byproducts
835.05 -> when decommissioning it are two primary factors
making it uneconomical, and Tokamak reactors
841.75 -> are driving straight towards the exact same
economic problem.
846.699 -> However, one company is doing it differently,
Helion.
850.57 -> The company I visited to witness nuclear fusion
reactions and interview their brilliant CEO
857.16 -> David Kirtley.
858.69 -> They are doing things completely differently
to everyone else in nuclear fusion research.
863.75 -> They aren’t capturing energy with steam
power, eliminating the need for costly beryllium
868.94 -> blankets.
870.18 -> They are developing a method of making fuel
on site that doesn’t require lithium, instead
875.87 -> using the cheap and plentiful deuterium to
create it during fusion.
880.78 -> And they are using a completely different
magnetic confinement method to achieve nuclear
886.31 -> fusion temperatures.
887.68 -> Next week we will be releasing a full length
documentary about Helion right here on YouTube,
894.33 -> so make sure to click the bell so you can
watch that as soon as it’s released.
899.64 -> In the meantime, you can continue learning
about the physics of Nuclear Fusion with this
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909.019 -> Electromagnets play a pivotal role in many
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914.009 -> trains and even MRI machines.
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Source: https://www.youtube.com/watch?v=BzK0ydOF0oU