Energy in crisis: nuclear power on the agenda | Podcasts
We’ve heard of nuclear fission – the splitting of the atom in common parlance – but there is another form of nuclear energy, which boasts of being almost limitless and which is said to be safer and cleaner. It’s nuclear fusion. Rather than breaking atoms apart, fusion involves bringing smaller atoms together to make larger ones. This is the process that powers the Sun, so we know it works. The challenge is to try to recreate the conditions inside a star that make fusion possible here on Earth! One of the places they are trying to do this, with some success now, is JET – the Joint European Torus, in Culham. Evelyna Wang went for a walk…
Fernanda – Fusion occurs when two light elements merge together and release more energy than before.
Evelyna – This was Fernanda Rimney, plasma physicist and chief operating officer of JET. JET stands for Joint European Torus. The shape of the reactor is included in the name. JET is a torus, or donut. This form is essential for research.
Fernanda – The way we confine this very hot plasma, the very hot fuel that we need to produce fusion, is by using magnetic fields. Plasma is made up of iridescent particles. They stick to the magnetic field.
Evelyna – The fuel, or plasma, must be extremely hot, over one hundred million degrees Celsius, if the atoms are to acquire enough energy to fuse together. However, it is not that simple. As the plasma heats up, it wants to expand outward – it wants to collide with other matter which, in turn, cools it. The solution is to trap him with large magnets, forcing him to spiral around the reactor. Researchers here at JET have had success. Late last year, the team set a new record for the longest meltdown ever: five seconds. I was looking forward to seeing JET up close, but the first stop on my visit was the control room.
Fernanda – The glow that we see on the screens is plasma. We have cameras looking inside the ship. The simple view you get here is just to check that everything is fine.
Evelyna – Am I allowed to ask what experiments they are currently conducting?
Fernanda – Now they are conducting the cleaning experiments; so, quite low power, very low temperature experiments. Starting tomorrow, we resume running some of the higher temperature experiments. We’re going to put some extra heating into the plasma and then we’ll continue with those until the end of the week.
Evelyna – We have yet to determine the optimal conditions for experimenting with plasma. As funny as it sounds, that was JET’s original goal. It was built to study plasma. These experiments will better inform the nuclear fusion reactors of the future to allow us, one day, hopefully, to beat the current record.
Fernanda – Most experiences are a scan of something. You have your base plasma and then you tweak the heating power slightly, plasma density slightly, magnetic fields. You are trying to change one setting at a time.
Evelyna – Everyone seems so busy!
Evelyna – From the control room it was a quick walk to the next building where the fusion reactor actually was.
Fernanda – It’s going to be very noisy.
Evelyn – Alright. wow.
Fernanda – Behind those yellow doors (that’s where it came from). Because the machine is running, these doors are closed and there is another shield, a secondary shield.
Evelyna – The meeting room was a huge warehouse teeming with people moving around in large boxes. There was even a giant crane planted in the center. Because JET is in constant use, I couldn’t get my hands on the actual reactor, but I was able to see the next best thing.
Fernanda – You can see the model up there.
Evelyna – Is it the line?
Fernanda – It’s not just a line. JET is built in sections like an orange – it is built from eight octants. When they built it, they built nine. They built an additional one as a test. It was, full size, and this is the one.
Evelyna – From where I was standing, the replica looked like a metal donut supported by large metal scaffolding. Compared to the real reactor, the mockup lacked all the external wiring, thick tubes for cooling water, and giant magnets. But still, I climbed the stairs and leaned my face against the window.
Fernanda – This is the size of JET.
Evelyna – This is about the size of four shipping containers arranged in a cube. Inside was a big, hollow donut. Metal plates lined the walls like scales. Oddly enough, inside the model was a large square looking robot. Fernanda told me that the maintenance inside the reactor is done by the remote-controlled robot named Mascot. The replica of the reactor is used to train operators to maneuver this robot. To get an idea of what she meant, we went to the remote manipulation room.
Fernanda – This is the remote control room.
Evelyna – That’s so cool!
Fernanda – Yeah, that’s one of the coolest things ever.
Evelyna – Inside, there are two handles in the middle of the room, and on the walls are several large television screens.
Fernanda – Basically there would be one person controlling her from here.
Evelyna – So they just stand there and use the handles?
Fernanda – They use the handle and the manipulator, and the mascot goes into the torus and does whatever is necessary from taking tiles or unscrewing things and then putting things back. The mascot has cameras, so there’s a full view of what the person is doing. It is no coincidence that the people who designed JET were all people with a dual background in physics and engineering. It was really central to the design and operation ever since.
Evelyna – The lessons and experiences made at JET inform the design of ITER or International Thermonuclear Experimental Reactor, a new fusion reactor being built in France that is twice as large.