Photo by DS stories from Pexels: https://www.pexels.com/photo/a-notepad-with-a-question-mark-drawing-6991443/
These are questions that the Communications Office have received via email from the website audience; hence the rather conversational tone. We attempt to answer each question with the available facts. The top FAQs are the ones that receive most views on our website. If you have a question, write to us!
How do both fission and fusion generate energy?
While it might seem confusing that energy can be generated by both fusion and fission, as they appear to be quite opposite processes, the explanation lies in the size of the nuclei.
Where does the plasma colour come from?
The colour comes from the fuel, which is basically hydrogen. Hydrogen gives out two different colours, a strong red and aqua-blue, which combine to give the pink colour that shows up in most pictures.
How are alpha particles produced and are they dangerous?
An alpha particle is produced by the alpha decay of a radioactive nucleus. Because the nucleus is unstable a piece of it is ejected, allowing the nucleus to reach a more stable state.
Does fusion give off radiation?
The fusion reaction releases neutrons, which would be quite dangerous to humans, however the production of neutrons ceases within milliseconds when the plant is turned off.
How much power is needed to start the reactor and to keep it working?
For fusion to occur we need to create and maintain plasma at extremely high temperatures. Additionally we need to contain the plasma by energising large magnetic coils.
How do the magnetic fields contain the plasma and how are these fields set up and powered?
As the ions in the plasma are charged they respond to magnetic fields. By setting up magnetic field lines toroidally around the interior of the tokamak, the ions and electrons in the plasma are forced to travel tightly around these field lines.
Would a sustainable D-D fusion reaction require much more energy compared to D-T fusion?
JET, so far the only operational fusion experiment capable of producing fusion energy, is routinely operated with Deuterium only, for a number of reasons.
Since plasma is a super heated substance, will it cause the burning of the reactor?
The answer is one of the key advantages of fusion as a potential energy source over nuclear fission power stations – its inherent safety.
How much more energy will it take a Tokamak over the “breakeven point” to actually produce power due to loss of energy in the processes of electricity production?
Breakeven is achieved when the energy from fusion reactions is larger than the energy required to sustain the plasma.
What is the temperature generated in a tokamak?
In order for fusion to occur in the very hot gas – or plasma –created inside JET, the plasma must be heated to temperatures in excess of 150 million degrees Celsius.
What is a lithium blanket and how does it work?
The blanket is a layer surrounding the vessel in a fusion powerplant. It will absorb the energy from the fusion neutrons produced in the plasma, boiling water via a heat exchanger, which will be used to drive a steam turbine and produce electricity.
Should you not try fusion under pressure as that is how it takes place in the sun?
Strangely enough, the sun is a very inefficient fusion reactor, producing only 1 watt per cubic metre – luckily it is very big so the total is a lot of power. Here on earth we are aiming for efficiencies a million times better than that!
How long is the longest sustained fusion reaction achieved by JET and elsewhere?
Most of the experiments that are carried out in fusion research use only deuterium, rather than a combination of deuterium and tritium (D-T).
How can we get more energy out than in?
The First Law of Thermodynamics explains how the amount of energy gained from something cannot exceed the amount put in. So it seems to violate the laws of thermodynamics – but…
How do fission and fusion reactions compare?
In fission, energy is gained by splitting apart heavy atoms into smaller atoms whereas fusion is combining light atoms, which form a heavier one. Both reactions release energy.
How do fission and fusion compare as sources of energy?
Using nuclear fission and fusion for generating electricity requires very different technologies and engineering.
How does fusion work?
Fusion releases energy when the nuclei of two forms of hydrogen (in our case, we use deuterium and tritium) are collided together at such high velocities that they stick together or fuse.