Hello and welcome to TILclimate, the
podcast where you learn about climate
change from real scientists and experts.
I’m your host, Laur Hesse Fisher, with the
MIT Environmental Solutions Initiative.
We’re continuing our series on
energy and climate in partnership
with the MIT Energy Initiative.
In our last few episodes, we’ve covered
the challenges of adapting our electric
grid to take on much more clean energy.
But there’s another way to generate
tons of electricity without pumping
greenhouse gases in the atmosphere--a
technology that’s already mature,
widespread, and competitive with fossil
fuels and also, very controversial.
I’m talking about nuclear power.
Today, we’ll explore how nuclear
power works, why even some climate
advocates don’t agree on using it, and
why many energy experts including
many at MIT say it’s a critical
part of our clean energy future.
To dig into this, we sat down with
an MIT professor who has spent his
career studying nuclear energy.
I'm Jacopo Boungiorno, I'm a
professor in the department of
nuclear science and engineering,
I'm also the director of the center
for advanced nuclear energy systems.
Let’s jump right in.
What exactly is nuclear power?
It all starts with a process called
nuclear fission, which is where a nucleus
inside an atom splits, releasing some of
the energy that binds the atom together.
This shows up in a form of heat and
then you can convert that heat into
electricity that is sent to the grid.
So in that sense it's a heat source
just like burning coal, natural gas
or getting heat directly from the sun.
But the primary energy source
in this case is Uranium.
Uranium is a heavy metal that’s
found in rocks all over the world.
For this episode, it’ll be helpful
to know that most of the Uranium out
there is a kind called Uranium-238.
And you need to alter or enrich some
of that to another type, Uranium-235, in
order to use it in nuclear power plants.
More about that later.
The first nuclear power plant was
built in 1954, near Moscow--and for
the next 30 years, power plants started
popping up all around the world.
At the time, many people saw nuclear power
as a huge leap forward from fossil fuels.
For one, Uranium is super abundant.
There is an enormous amount of Uranium out
there, more than enough to, to continue
to use nuclear and grow it actually,
and grow its use for, for centuries
that essentially affords countries
a certain level of energy security.
The second feature that makes nuclear
attractive is that the energy density
of the Uranium fuel is many orders of
magnitude higher than conventional fuels.
And it has to do with the fact that
a nuclear reaction breaks nuclear
bonds, not chemical bonds and
therefore liberates a lot more energy.
Just to give you an idea, a nuclear
power plant that would generate
enough to power the city of Boston
would require on the order of three
kilograms of Uranium-235 fuel per day.
And that's something that I can hold,
you know, on the palm of my hand.
So, that tells you how much
energy there is in this material.
Today, we see another very
important benefit of nuclear power.
These power plants don’t emit
any of the greenhouse gases
that are driving climate change.
You have an energy source that essentially
does not have any emissions into the
atmosphere and so that's the first
reason why people are interested in
nuclear now; because of course we're
trying to minimize the carbon emissions
into the atmosphere to prevent massive
global warming and climate change.
Nuclear power could have an especially
important role to play because
it’s both clean and dispatchable.
That means that, unlike wind and solar,
nuclear power can be revved up to produce
electricity exactly when we need it.
If you want to dig into this
topic a little more, check out
our episode on renewable energy.
Today, about 20% of our
electricity in the U.S.
is generated using nuclear power.
That’s more than solar, wind,
and hydropower combined.
in the US over 50%, five zero,
of our carbon free electricity
today comes from nuclear.
So it's already the largest clean energy
source that we have on the grid today.
Ok, but hold on if nuclear power is
such a great way to get cheap, clean,
reliable electricity and we’re already
using it--, why aren’t we building more?
Well, many people and even entire
countries are nervous about it.
There are three main concerns: nuclear
waste, nuclear bombs, and accidents.
Let’s start with waste--which
is radioactive, and needs
to be kept away from people.
In our community we call it spent fuel.
It's basically the material, the uranium
and the products of the fission reaction
that come out of the reactor when the
reactor is refueled and it's usually
put in water pools and it cools down for
between five or ten years after which,
the spent fuel is put in dry casks.
So these are steel and concrete little
containers and they are air cooled.
In the United States, these
dry casks are stored at the
nuclear power plants themselves.
Other countries are building
underground storage facilities
to store their nuclear waste.
Finland is planning to store waste
in a bedrock that’s been around
for about 1 billion years and is
not susceptible to earthquakes.
They say their waste will
be safe for 100,000 years.
It's one of few industries I think, in the
whole economy that actually takes care of
its materials from cradle to grave, right?
So nothing is emitted into the
atmosphere or in an uncontrolled manner.
I don't think any of the other power
generation technologies do this.
There’s another reason we need to be
really careful about uranium, and it’s the
second big fear people have about nuclear
energy: the risk of nuclear proliferation.
The issue is that there are materials
that are used in civil nuclear
power plants that potentially
can be used for nuclear weapons.
The fuel that is used in
nuclear power plants is very
low enrichment, I mentioned 5%.
That material is not weapons material.
As we mentioned earlier, we need
to enrich some of the uranium
to use it in power plants.
In fact, we need to enrich 5% of it.
To create a bomb, you would need to
enrich way more uranium—at least 90%.
There’s also an issue that the uranium
could be modified into plutonium, another
material that could be used for weapons.
And the way to handle it, quite
frankly, is to just have a very,
very tight control of all those
materials throughout the overall cycle.
But it is- it is a real concern and,
uh, you know, it's something that has
to be- that- that secure regime has
to be strengthened as much as possible
if nuclear is to grow internationally.
And then there’s the third
main concern, accidents.
When Uranium atoms are split inside a
nuclear reactor, they give off radioactive
particles, which in high doses can
cause terrible damage to our bodies.
Now, in normal conditions, that radiation
stays safely inside the reactor--in
fact, reactors are so well designed
for this that a nuclear plant actually
emits less radiation than a coal plant.
The main concern that I think people
have is associated with fairly
spectacular, rare events, accidents.
The Chernobyl accident, in 1986 in
modern-day Ukraine, was by far the worst.
If you look at the, exactly at
what happened at Chernobyl, the
operators deliberately disabled
the safety systems because they
wanted to conduct an experiment.
Well, you don't conduct an experiment
on a commercial local power plant.
As a result, the power plant
exploded, releasing the radiation
that was inside the reactor.
The first responders, these were
soldiers of the Soviet army that
were sent to basically throw
sand on the burning rubble.
Those were exposed to some pretty
horrendous levels of radiation.
And many of those died.
People who lived nearby were
also exposed to radiation.
The landmark report that assessed the
impacts of Chernobyl found that locals
who drank contaminated milk right after
the accident had higher cases of cancer.
And yet the same report found that the
radiation that by far most people in the
area experienced over their lifetime due
to the accident was actually really low
well below the levels that are known to
increase your risks of getting cancer.
The radiation exposure was even lower
for the tragic Fukushima accident,
which took place in Japan in 2011.
The accident occurred following
the earthquake and tsunamis,
which devastated that area
Including flooding the power
station, which led to the
reactor leaking radiation.
By the Japanese government’s official
account, over 2,000 people died as a
result but not from the radiation.
For Fukushima, you're looking
at an integrator over a lifetime
exposure of the order of 20 mSv.
What does 20 mSv mean?
So just to put things in perspective,
when you go to do a CT scan to
your torso, or you do some kind of
radiation imaging, you typically get
about a third to half of that dose.
And so, you know, assuming that
you do a couple of CT scans over
the course of your lifetime, it's
about the same amount of radiation.
The evacuation of 150,000 people from
the Fukushima area was a tragic mistake.
The amount of damage that has been done by
moving people, for example, out of, older
people out of hospitals and hospices and
things of that type was much, much greater
than any, health, damage that would have
been caused by exposure to radiation
because the radiation levels were so low.
Right, those 2,000 people who died
from the accident passed away due
to complications of evacuating
the area, not from the radiation.
It’s really terrible.
It's unfortunate all to avoid
two CT scans to the chest.
The question we’re really getting at,
of course, is: is nuclear power safe?
When it comes to risk and public health
impact, there is no way to be particularly
cheerful or positive, you have to look
at the hard cold numbers and compare.
And so if you compare nuclear to coal,
to natural gas, to solar, wind, hydro,
other ways to generate electricity,
it turns out that nuclear has the the
lowest actually, mortality rate per
unit, energy per unit, energy generated.
So how can this be?
The World Health Organization estimates
that over 3 million people worldwide
die every year from asthma, lung
cancer, and other illnesses caused
by air pollution from fossil fuels.
I was shocked to learn that if you
include worker accidents in the mix too,
nuclear power has actually had a lower
death toll even than solar and wind.
This was really surprising for
me, and it might be for you, too.
We’re including the studies
in our show notes so you can
read up on it for yourself.
Given all of this the fact that nuclear
power doesn’t emit CO2, that it can
deliver electricity on demand, that the
health risks are relatively really low,
and that the technology is evolving to be
safer and cleaner many energy experts
think we need to build more nuclear
as a part of a clean energy future.
The intermittency that is inherent in
solar and wind forces you to have backup.
You, you're going to need
to meet demand, right?
And if it's not met by a low carbon
sources like nuclear or wind then it's
met by either coal or natural gas.
This is not to say that we don't
need renewables we do need them.
But not alone.
You do need a, a, you
know, a diverse portfolio.
That's what all our analysis is showing is
that the best way to decarbonize is with
a portfolio of low carbon technologies.
If you’re hearing a running theme in
this energy and climate series, it's
that each clean energy technology
has its benefits and its challenges.
And that we can take advantage of the
benefits and reduce the challenges by
building a mix of different technologies.
It’s up to us to decide what role
nuclear power plays in this mix.
If you want to learn more about
nuclear power, we highly recommend Dr.
Buongiorno’s online course from EdX,
which we’ll link to in our show notes.
He also gives a great recap of the
MIT Energy Initiative’s report on
the future of nuclear, which you
can find at energy.mit.edu/podcast.
OK so we’ve talked a lot about
technologies that we can deploy
immediately to clean our electricity grid.
But what about new, potentially big impact
technologies that are on the horizon?
In our next two episodes, we’re going
to dig into carbon capture and storage,
and fusion energy, so stick with us.
Thanks to Dr.
Jacopo Boungiorno for joining us
today and thank you for listening.
