Nuclear fusion has been a pipedream for decades. Always 20 years away. Never 19. It’s easy to get jaded about this technology
and write it off as impossible, especially when nuclear fission energy already exists
and is being underutilised. But, by the end of this video, I hope that
I can change that feeling and get you as excited as I am about the potential of this technology. If we, as a civilization, actually pull it
off and invent a cost effective nuclear fusion power plant it would change the face of society. Clean safe fuels will allow every country
in the world to benefit from this technology. Allowing countries around the world to be
energy independent, preventing one of the leading causes of conflicts around the world,
as we fight for control of energy sources. Cheap, reliable and abundant energy is the
foundation of every sci-fi utopian society. It would solve our issues with climate change. Allow us to electrify industries that require
fossil fuels, like steel smelting. Allow us to create entirely new industries
that have been held back by energy costs, like water desalination. Providing the world with fresh clean water
to irrigate our lands and turn barren wastelands to fertile pastures. Ushering in an era of clean, safe abundance,
a utopian future that has been dreamed of for decades. Nuclear fusion experiments have been underway
since the very earliest years of the cold war, with the first generators firing up in
the 1950s in both the USA and USSR. The Soviet Union approached the problem with
a Tokamak design, while the Americans used a slightly different approach, the stellarator. Each design attempts to solve the same problem. Fusion in essence isn’t terribly complicated. We can make new elements by combining smaller
elements, and in the process release a lot of energy. However, to successfully combine elements
we need to overcome the electromagnetic repulsion that pushes them apart. Like pushing two north poles of a magnet together,
atoms will repel each other. In order to force them together we need to
input a tremendous amount of energy, but we can’t just grab individual atoms and force
them together like magnets. Instead, we create a plasma, essentially a
cloud of changed ions which, thanks to their charge, can be manipulated by a magnetic field. We can then confine the plasma within a magnetic
field preventing the ions from hitting the fusion generator walls, and gradually raise
its temperature to extremely high temperatures that would otherwise melt every solid material
in the universe. Raising the temperature of the plasma causes
the ions to move faster and faster. Raising the ions' kinetic energy so high that
their speed alone allows them to punch through the electromagnetic repulsion and collide. Both of these designs, the Tokamak and Stellator,
use slightly different methods of magnetic field confinement, generated by massive superconducting
magnets, to achieve fusion. The Tokamak became the leading design today
as a result of a release of information from the USSR on the tokamak design in 1968, which
showed a tremendous jump in energy efficiency. However, both designs used the same fuels. The exact reactants we use have a huge effect
on how much energy we need to put in, and what we get out at the end. Most reactions use two isotopes of hydrogen. A regular run of the mill hydrogen has one
proton in its nucleus with one electron in orbit. We could perform fusion with this kind of
hydrogen, but the energy we can extract out of the reaction is very low. Instead we frequently combine deuterium and
tritium together. Where hydrogen normally has one proton and
one electron and no neutrons, deuterium has one proton, one electron and one neutron,
while tritium has one proton and one neutron and two neutron. This combination is used for a couple of reasons. First, it has the largest probability of giving
us the exact result we want. Other reactions, like a regular hydrogen to
hydrogen reaction, have a very high probability of creating Helium 2, which is unstable and
almost instantly decays into 2 regular hydrogens again, and releases very little energy in
the process. [2] They have a lower probability of combining
to form deuterium, the reaction we actually want. Which then go on to fuse to form helium 3
and finally helium 4. This is the reaction chain that powers the
Sun, but the Sun has an unfathomable amount of particles making the probability issue
completely irrelevant AND the crushing gravity needed to create the conditions needed for
fusion. We need to supply those particles and the
energy needed to combine them ourselves, and if we can’t extract more energy than we
put in, that’s just a science experiment, not an energy source. We have successfully created many many fusion
reactions here on Earth, in fact, I witnessed the bright pink flashes of fusion myself while
visiting Helion recently. We know how to achieve fusion. The problem we are now trying to solve is
lowering the energy we need to input, while maximising the energy we can extract. So, step 1, we need fuels that require less
energy input that release more energy. That’s where deuterium and tritium come
in. When combined they have a very high probability
of creating helium 4, and release on average 17.6 Mega Electronvolts (MeV) for each and
every fusion event. For comparison, Uranium 235 produces about
11.4 times this energy for each fission event (200 MeV), but on a mass basis, that deuterium
tritium fusion reaction releases over four times as much energy as uranium fission, and
produces no dangerous radioactive products. Helium is actually quite a useful byproduct,
being used to cool MRI machines’ superconducting magnets, to fill rocket tanks after their
propellant has been expended to prevent them from exploding, and occasionally to make your
voice sound like Wendover Productions 6 years ago. Followed by this voice clip: https://youtu.be/6Oe8T3AvydU?t=539 And we will eventually run out of the gas,
so having a way to make it ourselves would be a nice back up. Deuterium is fairly common on earth, occurring
naturally in seawater. Making up about 0.02% of hydrogen in seawater. And because deuterium has an extra neutron,
it makes that water molecule heavier, giving it its name. Heavy Water. That difference allows us to separate it through
a number of means. Vacuum distillation allows us to take advantage
of heavy water's higher boiling point, while the girdler sulphide process separates heavy
water through chemical reactions. We can then simply electrolyse the heavy water
to separate the deuterium However, one of the issues facing nuclear
fusion is the rarity of tritium. Our primary source of tritium is nuclear reactor
moderator pools, which are often filled with heavy water. These pools are designed to absorb the high
energy neutrons given off during nuclear fission, and in doing so can become tritium. A hydrogen with 2 neutrons. [5] This source of tritium is becoming less prevalent
as nuclear power plants are gradually being shut down around the world due to competition
from cheaper forms of electricity. Currently total global reserves of tritium
is estimated at just twenty kilograms, which is not a lot considering ITER program, the
massive internationally funded fusion generator being built in France at the moment, estimates
a commercial reactor will need 300 grams of tritium every day to generate 800 MegaWatts
of electrical power. Meaning we would eat through the entire global
supply of tritium in just over 2 months. [6] 800 megawatts is enough to cover about
2% of France’s peak power consumption. Even if we could continue sourcing Tritium
from nuclear fission reactors, they only produce about 100 grams each per year. [7] This is a major problem, however we do have
a solution in mind. We can use the high energy neutrons spit out
from the fusion reactions to do a bit of alchemy wizardry. When those high energy neutrons encounter
lithium, they can split the lithium into tritium and helium. [7] Providing a steady supply
of tritium right where it’s needed. This is done in what is called a blanket around
the fusion chamber. The design of the blanket is one of the most
challenging parts of Tokamak fusion generator. ITER will test over 180 design variants of
this blanket that will line the donut shaped interior. Because, the blanket needs to do a lot more
than just breed tritium. It is also where the energy of the fusion
reactions gets converted to heat. 80% of the energy of the tritium deuterium
fusion reaction is carried away by those high energy neutrons in the form of kinetic energy. We need a way to convert that kinetic energy
to electricity. [8] As the fusion reaction rages in the centre
of the magnetically confined plasma, neutrons begin to erupt outwards, unaffected by the
magnetic field thanks to their neutral magnetic charge. Tokamaks convert the energy of these tiny
particles by slowing them down in the blanket, trading their kinetic energy with atoms in
the blanket to heat energy. This heat energy is then captured by high
pressure water being pumped through cooling channels, converting it to high pressure steam
to drive a steam turbine. Humanities tried and tested method of creating
electricity. The material that fulfils this role needs
some other unique properties. First, in order to optimise for heating AND
tritium breeding, we need the material to be a neutron multiplier. When the high energy neutron from the fusion
reaction enters the blanket wall we want it to strike an atom inside the blanket, and
release 2 neutrons. Creating an additional neutron that allows
the blanket to fulfil both roles of generating heat AND tritium. Beryllium is currently the leading candidate
for this role. When the neutron strikes it, it splits into
two helium 4 atoms and 2 neutrons. Multiplying our first neutron and allowing
our blanket to generate tritium and more heat. Beryllium, the same material used for the
James Webb Telescope mirrors, is the material of choice because the helium byproduct does
not contaminate the plasma, and critically, the material retains little tritium within
itself. We need the tritium to naturally escape the
metal, partially because we need to collect the gas to replenish our fuel, but also because
tritium is explosive, just like normal hydrogen. . However, Beryllium does have its problems. First, the sheer quantity of beryllium a commercial
fusion reactor will require. Current designs call for between 216 to 560
tonnes. This is an issue because beryllium is extremely
expensive, due to the limited supply of the material. Annual global supply last year amounted to
only 260 tonnes. The entire annual global supply of beryllium
could just about build one generator. Next, there are safety issues. Beryllium can contain large quantities of
uranium. China’s beryllium blanket module contains
100 parts per million uranium. So, 0.01 percent of the blanket is composed
of uranium. This isn’t an issue for most components
that are usually made out of beryllium. Like the beryllium, aluminium, copper engine
pistons that were banned from Formula 1 in 2001. However, it becomes a massive problem when
the uranium is exposed to those high energy neutrons. The same kind of neutrons that split uranium
in fission reactors. This creates fissile isotopes, or, in other
words, it makes the beryllium radioactive. [9] If there were 30 parts per million of uranium
to beryllium, in a commercial scale fusion reactor, that would mean there is 17 kilograms
of natural uranium and 123 grams of Uranium 235, the uranium needed for fission reactors. The byproducts of this ura nium would make
disposing of the blanket at the end of the generator's life incredibly difficult.[9] This all points to one major problem that
I see with Tokamak fusion reactors. Even if we manage to reach net energy output,
these generators don’t solve the biggest problem holding nuclear energy back. Cost. Nuclear fission power is a wonder technology
of the last century. It promised abundant, clean, cheap electricity. A technology that we scarcely even dreamed
of 2 centuries ago, as we first discovered the existence of the atom. Yet, we are closing down nuclear fission reactors
all across the world when we need that clean power more than ever, because it’s uneconomical. The cost of building a nuclear fission reactor,
and dealing with the radioactive byproducts when decommissioning it are two primary factors
making it uneconomical, and Tokamak reactors are driving straight towards the exact same
economic problem. However, one company is doing it differently,
Helion. The company I visited to witness nuclear fusion
reactions and interview their brilliant CEO David Kirtley. They are doing things completely differently
to everyone else in nuclear fusion research. They aren’t capturing energy with steam
power, eliminating the need for costly beryllium blankets. They are developing a method of making fuel
on site that doesn’t require lithium, instead using the cheap and plentiful deuterium to
create it during fusion. And they are using a completely different
magnetic confinement method to achieve nuclear fusion temperatures. Next week we will be releasing a full length
documentary about Helion right here on YouTube, so make sure to click the bell so you can
watch that as soon as it’s released. In the meantime, you can continue learning
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