Colleen: How do we solve climate change? Ask 100 people and
you’ll get 100 answers. And if one of the people you ask is
Bill Gates, you might hear that we should turn to nuclear
energy to help us reach our climate goals. But while
generating nuclear power doesn’t create carbon emissions, it
does come with a host of other challenges… like
affordability, safety, and the unsolved question of how to
safely dispose of nuclear waste.
Almost
every nuclear reactor operating today is what’s known as a
light-water reactor, because they use ordinary water to cool
their hot radioactive core. To try and solve the biggest
challenges of nuclear energy, the industry is turning away
from light water reactors and looking toward new designs
that use other materials to cool the core. The industry
calls these new designs quote-unquote advanced reactors and
claims they will help us build a clean energy future that’s
also safe and affordable.
So…
are these claims accurate? Today’s guest is Dr. Edwin Lyman,
a physicist and director of nuclear power safety at the
Union of Concerned Scientists. He just released the report
“Advanced isn’t always better,” an independent review of
these new designs that cuts through the hype coming from the
nuclear industry. Ed wants to make sure we don’t waste money
designing and building reactors that aren’t safe and don’t
improve on what we already have.
He
explains how today’s nuclear reactors work, what’s different
about so-called advanced reactors, and whether or not they
deliver on the benefits they promise. Ed also tells us about
the Natrium reactor being designed by Bill Gates’ company
TerraPower… and what he’d say to Bill Gates if they met at a
dinner party.
Colleen: Ed, welcome back to the podcast.
Ed: Thank
you for having me again.
Colleen: So, we’ve talked in the past about small modular
reactors, the Chernobyl disaster. And today, I want to dig
into non-light- water reactors. You just published a
technical analysis looking at the safety, security, and
environmental impacts of this proposed new suite of nuclear
reactors. First off, how are they different from the nuclear
reactors that the U.S. currently operates?
Ed: Sure.
So, the U.S. currently has 94 nuclear reactors to produce
electrical power. And they all use ordinary water as a
coolant to remove heat from the hot fuel to convey that heat
to a power generation system, which generates steam and
produces electricity. These reactors have a main
characteristic as they don’t use water to cool the fuel, but
they use other substances. For instance, you can use a
liquid metal like liquid sodium as a coolant, or you can use
a gas like helium, or in some cases, the fuel cools itself
as a liquid and it cools itself.
Colleen: So, can you run through the new advanced reactors
that you evaluated?
Ed: Yes.
The first main class of reactors is called fast reactors.
And these differ from our existing fleet because they don’t
have materials that slow down neutrons. So, when a nucleus
of uranium fuel is fissioned, it’s struck by a neutron and
it’s split apart, and it releases energy and other neutrons.
And those other neutrons will then strike other uranium
nuclei, and you have what’s called a chain reaction. And
that generates a steady level of heat which can then be used
to produce electricity. That’s how the nuclear reactors
work.
But in the water-cooled reactors that we
have now, those water molecules actually slow down the
neutrons. So, when a neutron is produced by fission, it has
a certain energy. But as it collides with water molecules,
it slows down. It turns out that makes it…essentially, that
makes the fission reactions more efficient. So, you can use
less concentrated fuel. So, that’s a certain approach to
designing a nuclear reactor that we use today.
But in a fast reactor, you don’t have a
material that slows down those neutrons. So, they remain
high-energy, and that has different properties than
light-water reactors. In fact, some of the advantages that
the developers of these reactors claim, stems from this
property of having fast neutrons. And in order to do that,
you need a coolant other than water. You need something that
won’t actually slow down those neutrons. And so, that’s why
a substance like liquid sodium is used to cool those
reactors.
Then there’s another category which is
called high-temperature gas-cooled reactors. And as the name
suggests, they don’t use water to cool the fuel, but they
use a high-pressure gas, most commonly, helium, which you
pump through the reactor vessel. And the gas will then be
pumped out after it’s heated up, and then used again to boil
water and produce electricity.
The third category is a much different
type of reactor than the others. And that’s a molten-salt
fueled reactor. And the reactors that we use today use a
solid material as the fuel, which is something that’s
desirable. You have a solid material surrounded by a metal
cladding. But in a molten-salt fueled reactor, the fuel
itself is a liquid. It’s a hot molten salt where the uranium
and other fuel materials are dissolved in that fuel. Again,
that has…according to the proponents of that technology,
that gives you certain advantages over solid fueled
reactors. But it also has quite a few disadvantages that we
can talk about.
Colleen: How long have these types of reactors been studied?
Ed: These
reactors, by and large, are very old technology. So, people
often call them advanced reactors, but…because that’s not
really an accurate characterization. We don’t really use
that in our report. In fact, some of these reactor designs
were conceived before the light-water reactor that we use
today in the United States. So, they date, you know, from
the days of the Manhattan Project in the 1940s. And some of
these technologies were actually attempted as early as the
1950s, both in the U.S. and other parts of the world.
Colleen: Ed, I know from reading the report that each of
these reactor types has their problems. Let’s narrow down to
fast reactors for our audience. What do proponents say about
them?
Ed: So
again the benefit of a fast reactor is, primarily, the dream
for which it was first conceived. Because of the special
properties of fast neutrons, the fast reactor, in theory,
could operate in a mode where it could generate not only its
own fuel, but actually produce a little extra fuel for
another reactor. So, this is what’s called a fast breeder
reactor. And this is one of the reasons why the Manhattan
Project scientists who may have had too much time on their
hands at one point, dreamed of this reactor.
They thought it would be a way to fuel
nuclear power forever without having to use uranium
resources, which they thought had to be saved for nuclear
weapons. Because it was thought uranium was a very rare
commodity at the dawn of the nuclear age and that the U.S.
would need all it could get for nuclear weapons. So, if you
had a reactor that could actually breed its own fuel, you
wouldn’t have to compete with that.
And the other potential advantage of a
fast reactor is that it has the ability to actually utilize
other types of fuels efficiently, in particular, some of the
materials in the spent nuclear fuel from current reactors,
which has a very long half-life. That means it persists in
the environment for tens or hundreds of thousands of years.
That kind of material is not utilized very efficiently in
current reactors, but a fast reactor could actually convert
more of that to energy. So, sometimes, fast reactors are
called burner reactors and their proponents tout them as
being able to burn spent fuel to take existing spent fuel
and essentially destroy it or recycle it. These are the
terms that are here.
Colleen: So what are some of the problems with fast
reactors?
ED: First
of all, it’s not…doesn’t really live up to its hype in a
real system. So, yes, in theory, a fast reactor could
operate as a breeder or a burner. But what I discuss in my
report is if you look at real systems in a real electricity
system and how these reactors actually work, it would take a
very, very long time to make a dent, let’s say, in the spent
nuclear fuel stockpile we have now or it would take a very
long time to actually breed fuel in a way that you can say
you’re being more efficient than the current systems.
So, it’s not really realistic to claim
these reactors can burn spent fuel or to breed new plutonium
in an effective way. So, the benefits aren’t that great, but
the risks are very significant. Because in either one of
those cases, a breeder reactor or a burner reactor will also
need to reprocess spent fuel to produce that new fuel for
the reactor. And reprocessing is a technology where you take
nuclear waste, spent nuclear fuel, and you put it through a
chemical process to extract the materials that you want to
use in a fuel, primarily, plutonium and separate that from
other radioactive waste that you can’t recycle in a reactor.
And the problem with doing that is that plutonium, in
addition to being a potential nuclear fuel, is also a
nuclear weapons material. So, when you separate it from
spent nuclear fuel, you’re essentially making it easier for
a [00:08:30] country or a terrorist group that wants to
acquire nuclear weapons. It makes it easier to get that
material.
And so, therefore, any nuclear power
system that uses reprocessing is inherently more dangerous
from a nuclear proliferation perspective than the system we
have now which is operating light-water reactors without
reprocessing the spent fuel. In addition, fast reactors have
serious safety issues which the proponents like to gloss
over.
For instance, we’re all familiar with
Chernobyl and we’d discussed that in a previous podcast. One
of the main initiators of the Chernobyl disaster was the
reactor had a design flaw where under certain circumstances,
if the reactor heats up, it actually undergoes a positive
feedback. So, the hotter it gets, the more power it produces
and you have essentially what’s called a massive power
excursion that led to explosion of the reactor. That’s
something you don’t want to have in your nuclear reactor. In
fact, the light-water reactors in the U.S. today have the
opposite behavior. If the reactor heats up, the nuclear
reaction tends to shut down.
But fast reactors typically are more like
Chernobyl in that if they heat up and that liquid sodium
coolant starts to boil, then you actually get more and more
fission. So, the power of the reactor can increase by a
factor of 100 in a matter of seconds. And so, you have a
situation where you can have, again, a core meltdown or even
an explosion. So, it’s that instability that I worry about
with regards to safety.
Colleen: So, Ed, are these fast reactors, are they just
theories or have any of them been built or any pieces of
them built to do actual testing?
Ed: Yes.
Fast reactors, there’s been a fascination with them in the
U.S. and other countries. So, actually, the first fast
reactor was built back in 1951 here in the United States.
And there have been a number of demonstration and test fast
reactors in the U.S., in the Soviet Union and now Russia, in
the United Kingdom, in France, in Japan, in India, where
most of them are located. And the actual record with these
reactors has been extremely mixed.
One problem with using liquid sodium as,
you know, any mischievous high school student has ever tried
this can tell you is that it doesn’t…that sodium metal
doesn’t play very well with water. In fact, if it comes in
contact with water or air, it can actually catch fire. So,
you’re using a potentially flammable coolant in your nuclear
reactor. And so, the developers have to put in all sorts of
extra safety systems to make sure they can detect if there’s
a sodium leak that could actually lead to a fire. In fact,
this is really one of the biggest issues that affect the
reliability of fast reactors around the world.
But the reactors, by and large, had not
been demonstrated on the scale and using the same fuel and
safety systems that are being proposed for the generation of
fast reactors that are being talked about to be built today.
Colleen: So, I’m assuming, with the climate crisis upon us,
could the potential risks justify the enormous public and
private investments needed to get them up and running?
Ed: Well,
that’s one of the fundamental questions here is obviously,
we’re facing this potentially devastating climate crisis and
we need to evaluate every possible tool that could help us
to deeply decarbonize the energy sector as rapidly as
possible. So, nuclear, overall, nuclear power is a potential
option for doing that. But that doesn’t mean nuclear power
should just be given the benefit of the doubt and any
cockamamie idea that someone comes up with is something that
the federal government investors should throw billions of
dollars at. Because it will take many billions of dollars
and probably a couple of decades at least before any new
reactor design could be actually commercialized and have a
hope of being safe and reliable.
So, one of the reasons why I pursue this
report is to examine some of the claims that are being made
about these reactors. Because if there’s no real benefit to
pursuing a radically different type of reactor design than
the one we have now, then…if there’s no real benefit, then
those investments wouldn’t be justified. So, I think it’s
very important for the public to date to make sure that they
know what the facts are and where claims are being made,
what the actual subtlety is or caveats or fundamental truth
about those technologies is being discussed. And so, people
are not misled into supporting very speculative reactor
designs that are essentially high-risk, low-benefit
technology.
Colleen: Well, you know, Ed, you’re making me think of Bill
Gates. He’s touting these technologies as a promising
solution for meeting our climate targets. And, you know,
he’s a successful guy. He has a lot of power to persuade. I
mean, if I set up a dinner party for the two of you, what
would you want to talk to him about?
Ed: Yeah.
So, I wanna tell Bill Gates that he really needs to go
beyond what his advisors may be telling him. Sure, he’s
obviously a very successful person and not an idiot. But
when he talks about nuclear power, he really demonstrates
that there’s some gaps in his understanding. I get the
feeling that he has not done an independent review for
himself of the projects that he’s funding. In particular,
through a company called TerraPower which Gates founded and
which he’s the chief investor in.
This company is developing a
sodium-cooled fast reactor called the Natrium. And this is
moving forward because the Department of Energy selected the
Natrium design as one of two that will be part of what’s
called the Advanced Reactor Demonstration Program, which was
created by congress in 2019 as a public/private partnership
to build two advanced demonstration reactors by 2027. That’s
the very aggressive goal. And the Natrium reactor won one of
those awards. So, they are pursuing a demonstration reactor.
But, again, the sodium-cooled fast
reactor, has a lot of liabilities and not a whole lot of
benefit. In fact, the Natrium itself, because of the fuel
it’s going to use, has even less benefit than a fast reactor
would, in theory. Because, again, one of the real…only
advantages to taking on the additional risks associated with
a fast reactor is you could get this benefit of breeding
plutonium, expanding or producing your own fuel, and
reducing the need for actual mined uranium.
But in the case of the Natrium, it turns
out it would probably take two to three times more uranium
to generate a kilowatt/hour power from that reactor than
from current light-water reactors. So, it would actually be
less uranium efficient than current reactors. So, why would
you invest billions of dollars in developing a technology
when it doesn’t even meet that basic test of having the
benefit that you thought it would have?
Colleen: So, one of the goals of your report is to provide
the technical analysis so that policy decisions that are
being made are well-informed. What are some of the
recommendations that you make in the report?
Ed: One
of the primary recommendations is that the Advanced Reactor
Demonstration Program I just mentioned with the goal of
building two commercial reactors that would be connected to
the grid and generate power by 2027, that that program
actually be suspended. Because I don’t think that the safety
data is available yet to support that kind of deployment.
It’s possible these, one or both of these reactors, will be
built at ordinary utility sites. Utility is going to expect
that the reactor will operate at full capacity without
significant reliability problems. So, in order to have a
reactor like that, essentially a commercial reactor that’s
ready to generate commercial power, you need to have a basis
for licensing that reactor in that mode, and also enough
technical information to be able to understand the problems
with operating it and to operate reliably. And I do not
believe that the existing record is here to support the
safety analysis.
So, the Nuclear Regulatory Commission,
which is the regulator of nuclear power plants in the United
States will have to license those reactors. And they’re
going to be faced with the question of whether they should
license a commercial-sized reactor based on the spotty
safety database that exists. In the past, the NRC has said,
“Well, if you want to build a new reactor type that hasn’t
operated commercially, in order for us to license it, you’re
going to need to probably build a prototype, and to run that
either a smaller scale or full scale.” But you run in a mode
that’s not for generating power, but for doing safety
testing, for qualifying fuel which is always a very
important safety measure to make sure that the nuclear fuel
is safe under the conditions that it will be used, and other
critical testing to support licensing that commercial
reactor.
And so, I feel like they’ve skipped this
development step, and the NRC doesn’t have the information
they’ll need to really make a safety finding to license
these demonstration reactors. So, I’ve argued that the
program should be slowed down, that the NRC should have the
opportunity to consider what additional data it’ll need to
license those large reactors which would most likely involve
building a prototype where, because you’re going to be using
it for safety testing to address uncertainties in the safety
of the design, you’re going to want to have additional
features that may not be in the commercial reactor.
For instance, many of these reactor
designs don’t include a conventional containment. The
nuclear reactors we have operating today in the U.S. have
reinforced concrete containment structures, which are
designed to prevent leakage of radiation in the event of an
accident, and even in the event of an explosion like what we
saw at Fukushima Daiichi in 2011, that they would provide
some protection against that. But a number of these reactors
won’t have any real containment at all because the
developers argue that the reactors are so safe they won’t
need one. But that is a statement that really has to be
verified. And so, you’d want to use a prototype to test
certain scenarios. But because you don’t know how they’re
going to play out, you’d want that prototype to have a
containment even if the commercial design doesn’t have one.
So, the prototypes could look a lot different than the
designs that are being pursued under this program. And I’ve
argued to slow it down.
Another conclusion is that I don’t think
there is due diligence when the Department of Energy has
awarded these demonstration project awards. I’m not
confident that the process is really examining whether these
reactors have all the benefits that they claim they do. And
I think there has to be a better vetting of reactor designs
before billions of dollars of public money is committed to
these reactors because we don’t want to subsidize the
development of unsafe reactors.
Colleen: If nuclear power needs to be part of the climate
solution, why not continue to use what we have? I understand
the reactors that we have are aging out. But why not either
shore those up or use the same design that we currently have
where we wouldn’t have to go through the lengthy and costly
development phase?
Ed: Yes,
that is the baseline we have is the operating light-water
reactor fleet as well as what are called the evolutionary
design changes that is building off that experience and
trying to do better, but having the same fundamental design
using water as a coolant. And without having to take a
position on what the role of nuclear power should be in deep
decarbonization, you can ask the question, “Are these
advanced reactors better?” Or if you’re going to invest tens
of billions of dollars in new nuclear reactor designs, would
it make more sense to focus on the existing technologies on
how to improve them with respect to safety and cost? So,
that’s really the baseline. But the operating reactor fleet
has its problems. And, you know, we’ve seen what happened in
Fukushima Daiichi at a light-water reactor. They clearly are
susceptible to core melt accidents, especially in the event
of a severe earthquake or flood. And so, they have been
somehow discredited in the eye of the public.
And also, they’re costly, the current
fleet. In some parts of the United States, nuclear power is
no longer economical because not only natural gas is
cheaper, but also wind and solar is cheaper than nuclear
power under certain conditions. And so, a number of
operating plants are not economic anymore. And as far as new
plants go, those have turned out to be extremely
cost-prohibitive. And so, the only two nuclear reactors
under construction in the United States right now in the
State of Georgia are running at twice the original estimated
cost, up to, I think, now $28 billion for that project. And
they’re taking twice as long, at least, as originally
planned.
So, the light-water reactor has lost some
credibility. And I feel like that’s what’s driving the
messaging from the nuclear industry today is they feel like
they have to show the public they have something different
and they can do better with something different. But the
problem is that this… we’re not talking about messaging
here. We’re trying to win public hearts and minds it’s not
what needs to be done. It needs to be done as to address
these fundamental safety and cost issues of nuclear power.
And just doing something different for the sake of the fact
that it’s different is not necessarily the best approach.
Colleen: Well, nuclear power is certainly a subject that is
fraught. And I appreciate your expertise and the clarity
that you bring to the issue. Ed, thanks for joining me on
the podcast.
Ed: Thank
you. It’s been a pleasure.
