WEBVTT
Kind: captions
Language: en

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This is the control room for JET,

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the Joint European Torus at Culham Centre
for Fusion Energy.

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JET is a nuclear fusion experiment,

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a scientific research facility that's hopefully

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one step on the journey to plentiful, clean
fusion power.

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When it's running, the reactor vessel is literally

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the hottest place in the solar system,

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ten times hotter than the core of the sun,
and right now,

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we are just a couple of minutes away from
an experiment --

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or as they call it here, a pulse.

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We're running a series of experiments at the
moment looking at disruptions.

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Plasmas really don't want to be there.

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When they cease to be, they create quite a
lot of mechanical energy

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which can shake the machine, and in future
power plants

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we really want to try and mitigate against these problems.

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So right now, enormous, 700-tonne flywheels
are being spun up

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to provide enough energy for the experiment.

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Less than a hundredth of a gram of gas is
already in a vacuum vessel next to the torus,

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and when the pulse starts, it'll be pushed
in and heated:

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by enormous magnets, by injecting hydrogen
atoms,

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and just by dumping huge amounts of radio
frequency power into it,

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making it into a superheated plasma.

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And then it'll hit about a hundred million
degrees Celsius,

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and we will start to see nuclear fusion.

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With fission, you're always trying to slow
it down and control that reaction.

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And we have exactly the opposite thing.

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And therefore it's not possible to see a situation

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where you could have a large-scale accident
as you could with fission.

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Now, there are huge numbers of machine protection
systems watching the experiment.

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If anything goes wrong, power gets cut and
the whole system just stops.

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But if something's more subtly wrong,

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there's one safety feature you might not expect.

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Up in the ceiling are surround-sound speakers,

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hooked up to microphones in the reactor hall,
where no human is allowed.

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Those speakers relay the sound from the experiment

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to the crew here in the control room in real
time, as if they were standing --

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as if this point where I'm standing right
here --

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was in the middle of the torus.

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And all the high-tech machine protection equipment
here is necessary,

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every single bit of it. Computers can react
so much faster than us:

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that human delay between incident and response
could be the difference

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between a safe shutdown and some rather expensive
repair bills.

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But if something is subtly wrong,

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like when you get a faint, weird noise in
your car,

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humans might be able to notice before computers
do.

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A couple of years ago, we had a disruption
and we could hear this clanging noise.

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And we were able to pinpoint the exact area,
and what we believed it was

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which was a clamp which held a pipe,

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and we were immediately able to walk into
the area,

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go to where we believed it was,

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and found it -- and then could replace it.

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The engineers here: they're taken a human
ability --

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that feeling that's been honed by hundreds of millions
of years of evolution,

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that something is just subtly wrong, something
is off --

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and they've put it to work on one of the most
incredible things

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that humanity has ever constructed.

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All right. Here goes the pulse.

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[Five, four, three, two, one, zero...]

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