中級 美國腔 1063 分類 收藏
When you think of the word nuclear, what comes to mind?
It's probably some terrifying thought.
I can't blame anyone for being nervous.
It's a technology that we've been using
for decades that can really reduce global

but it's not exactly something environmentalists
are that excited about.

The first thing many people think of is nuclear
war and mushroom clouds.

You add into that major events like Three
Mile Island and Chernobyl and now most recently

and those have had incredibly profound consequences
on people's immediate feelings and images

and associations with this technology.
This isn't something where the public has
the view wrong.

It is a technology with a reputation that's
been earned.

I mean, if a nuclear power plant was being
built in my town, I'd be pretty nervous

about it.
However, as a conservationist, that makes
me feel really conflicted because these power

plants don't emit CO2,
and that's the main pollutant that's causing
climate change.

When you look at the technology and you ask

How are we going to solve this problem of
climate change?

To not have nuclear energy be on the table
makes the job much harder.

Now for the most part these plants work really

They supply about 20 percent of the electricity
on the US power grid.

But almost all of them in the US were built
over 35 years ago.

In fact, they look like something out of a
vintage movie set.

And historically they've had two big problems:
They produce radioactive nuclear waste and
they can be vulnerable to a disaster like

a nuclear meltdown.
Nuclear meltdowns happen because water that's
used to cool the radioactive fuel rods can't

be pumped in.
Usually due to something like a backup power

This fuel heats up rapidly, and since these
reactors operate at high pressure, there can

be explosions from all of this excess heat.
You can think of it like a balloon popping
and releasing the air inside — but in this

case, radioactive air.
Leslie Dewan is trying to fix this.
She runs a startup company called Transatomic

They're trying to build new power plants
without this problem.

Our reactors operate at atmospheric pressure
and you don't need that typical containment

You don't need the big stacks.
You have a lot more flexibility in the architecture
of the plant.

And that low pressure also means there's
no way to have that nuclear balloon pop scenario.

But it isn't just about stopping disasters.
The fuel itself is toxic and has to be stored
underground for thousands of years.

And unfortunately we don't use it very efficiently.
The solid fuel can only stay in the reactor
for a limited amount of time before it starts

to break itself down and you have to physically
remove it.

You can only extract about 4 percent of the
energy that you could conceivably get out

of the uranium, and the rest is left behind
as waste.

This is like opening up a bottle of water,
taking a sip, and then tossing it out.

But that's actually how older reactors use
nuclear fuel.

The next-generation reactors are using fuel
much more efficiently.

Transatomic's reactor design will use the
fuel in a liquid form so that it can stay

in the reactor for a longer period of time.
A lot of the advanced nuclear reactors can
consume much more of the energy from the uranium.

You can get much, much higher fuel utilization.
Which means that you're leaving significantly
less waste behind.

And this is a trend in the field.
There's a huge interest to phase out conventional
fuel rods for different forms of fuel, for

a variety of reasons.
In the last 20 or 30 years, we've developed
different types of fuel, which cannot melt.

And which in fact—
What do you mean by that?
Physically cannot melt.
That's Per Peterson, he's a nuclear engineer
at the University of California Berkeley who's

working on a next-generation reactor design
that uses an entirely different form of fuel.

Many older plants still use conventional fuel

This new design, known as a fuel pebble, encases
uranium in a golf-ball sized sphere.

It's made of a very strong ceramic material
that can withstand much higher temperatures,

so it cannot melt and is safer to use.
Now this one was built to demonstrate that
you can fabricate it.

So it does not have uranium in it, but every
other way it is identical to the real thing.

Same weight and everything like that?
And they're designed to be very safe.
You can drop this thing from 10 meters onto
a steel plate and it won't break.

Or if I wanted to I could drop it right now.
So essentially, that fuel pebble is designed
to be its own self-contained system.

If a power failure does happen, the pebbles
just empty into a holding tank where they

cool down on their own.
No need for backup generators or water to
keep it cool to prevent a meltdown.

Okay, so why hasn't this happened yet?
I mean we have better materials, we have reactors
with new designs and fuels that makes less

It actually sounds like we have the answers
to our problems.

So what's the catch?
You know the old phrase, you never get a second
chance to make a first impression?

People's first impression of nuclear energy
and nuclear power was mushroom clouds.

And if it's got the word "nuclear" associated
with it, it's just going to be very difficult

to convince people, no, no, we mean it this

This one's safe.
It puts nuclear energy in a very challenging

Right now even solar and wind are cheaper
than nuclear power.

So there isn't a lot of economic incentive
to build these power plants.

And if no one wants to build them, then companies
that make the parts go out of business or

go somewhere else where new plants are being
built, like China.

Those that are under construction now, the
economics have been really grim.

The number of plants that have been started
and the price overruns have been massive.

One of the problems is just simply transporting
the components.

Instead of getting parts locally like we did
in the 1960s and '70s, the parts today are

shipped from overseas.
And these aren't just basic nuts and bolts
— these are huge complicated components.

If a section of a reactor vessel breaks during
transport, it needs to be fixed or a new one

needs to be built and reshipped, taking more
time and money to complete.

I think that it's going to be very interesting
to see how startup companies tackle those

And this is a very different space from where
the traditional technology evolved.

Now rapid innovation has happened in other

Look at SpaceX for example.
They went from a concept rocket to delivering
supplies to the International Space Station

in a matter of years.
The technologies that are being researched
now that look very promising range from small

modular reactors where the whole nuclear power
plant comes on the back of a flatbed truck,

gets parked, plugged in, and when the fuel
is used up simply gets taken away as a unit

to be reprocessed.
These small modular reactors could have specific

Like powering a data center that's using
electricity around the clock.

We have startups building cheaper, smaller
reactors that don't melt down.

We have engineers making fuel that doesn't
produce much waste.

While the public image of nuclear energy is
rooted in the past, the nuclear energy of

today is a whole different ballgame.
People like me view nuclear as being a necessary
piece of carbon-free energy production.

There's less of that fear of nuclear, and
more of, sort of a need to use everything

in our toolbox to combat climate change.
There are other energy sources that we may
be overlooking.

For example, scientists are actually turning
to poop to power cars.

Head over to climate.universityofcalifornia.edu
for more.



核能爭議的再思考 (The fight to rethink (and reinvent) nuclear power)

1063 分類 收藏
Ting 發佈於 2019 年 3 月 12 日


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