Nuclear Energy Explained: How does it work? 1/3

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. [Intro] It all started in the 1940s. 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, helping the world get back on its feet. Everyone’s imagination was running wild. Would electricity become free? 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, but hard in real life. 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 between 1970 and 1985. But which type of reactor to build,
given how many different types there were to choose from? A surprising underdog candidate
won the day: the light water reactor. It wasn’t very innovative, and it wasn’t
too popular with scientists, but it had some decisive advantages: it was there, it worked, and it wasn’t
terribly expensive. So, what does a light water reactor do? Well, the basic principle is shockingly
simple: it heats up water using an artificial
chain reaction. Nuclear fission releases several million
times more energy than any chemical reaction could. Really heavy elements on the brink of
stability, like uranium-235, get bombarded with neutrons. 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 runaway reaction in an atomic bomb. 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 to drive the turbines anyway.

The light water reactor became prevalent
because it’s simple and cheap. However, it’s neither the safest, most
efficient, nor technically elegant nuclear reactor. 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 sparked new discussions and concerns. While in the 1980s 218 new nuclear power
reactors went live, their number and nuclear’s global share of
electricity production has stagnated since the end of the ’80s. So what’s the situation today? 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. So, should we use nuclear energy? The pro and contra arguments will be
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