Name: Nuclear Energy Explained：How does it work? 1/3
Uploaded: 2015-05-24T15:59:57.000Z
Duration: 5 min 18 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Have you ever been in an argument
about nuclear power?

We have, and we found it
frustrating and confusing,

so let’s try and get to grips
with this topic.

After the shock and horror of the war
and the use of the atomic bomb,

nuclear energy promised to be a peaceful
spin-off of the new technology,

Everyone’s imagination was running wild.

Could nuclear power help
settle the Antarctic?

Would there be nuclear-powered cars,
planes, or houses?

It seemed that this was just a few
years of hard work away.

One thing was certain: the future
was atomic.

Just a few years later, there was a sort
of atomic age hangover;

as it turned out, nuclear power was very
complicated and very expensive.

Turning physics into engineering
was easy on paper,

Also, private companies thought that
nuclear power was much too risky

as an investment; most of them would much
rather stick with gas, coal, and oil.

But there were many people who
didn’t just want to abandon

the promise of the atomic age;
an exciting new technology,

the prospect of enormously
cheap electricity,

the prospect of being independent
of oil and gas imports,

and, in some cases, a secret desire to
possess atomic weapons

provided a strong motivation
to keep going.

Nuclear power’s finest hour finally came
in the early 1970s, when

war in the Middle East caused oil prices
to skyrocket worldwide.

Now, commercial interest and investment
picked up at a dazzling pace.

More than half of all the nuclear reactors
in the world were built

But which type of reactor to build,
given how many different types

A surprising underdog candidate
won the day:

It wasn’t very innovative, and it wasn’t
too popular with scientists,

it was there, it worked, and it wasn’t
terribly expensive.

Well, the basic principle is shockingly
simple:

it heats up water using an artificial
chain reaction.

Nuclear fission releases several million
times more energy

Really heavy elements on the brink of
stability, like uranium-235,

The neutron is absorbed, but the result
is unstable.

Most of the time, it immediately splits
into fast-moving lighter elements,

some additional free neutrons, and
energy in the form of radiation.

The radiation heats the surrounding water,
while the neutrons repeat the process

with other atoms, releasing more
neutrons and radiation

in a closely controlled chain reaction,
very different from the fast, destructive

In our light water reactor, a moderator
is needed to control the neutrons’ energy.

Simple, ordinary water does the job, which
is very practical, since water’s used

The light water reactor became prevalent
because it’s simple and cheap.

However, it’s neither the safest, most
efficient, nor technically elegant

The renewed nuclear hype lasted barely
a decade, though;

in 1979, the Three Mile Island nuclear
plant in Pennsylvania

barely escaped a catastrophe when
its core melted.

In 1986, the Chernobyl catastrophe
directly threatened Central Europe

with a radioactive cloud, and in 2011
the drawn-out Fukushima disaster

While in the 1980s 218 new nuclear power
reactors went live,

their number and nuclear’s global share of
electricity production has stagnated

Today, nuclear energy meets around 10% of
the world’s energy demand.

There are about 439 nuclear reactors
in 31 countries.

About 70 new reactors are under
construction in 2015,

most of them in countries
which are growing quickly.

All in all, 116 new reactors are
planned worldwide.

Most nuclear reactors were built more than
25 years ago with pretty old technology.

More than 80% are various types of
light water reactor.

Today, many countries are faced with
a choice: the expensive replacement of

the aging reactors, possibly with more
efficient, but less tested models,

or a move away from nuclear power towards
newer or older technology

with different cost and environmental
impacts.

The pro and contra arguments will be
presented here next week.

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