Teacher's notes and answers to questions in the book - Hodder Plus ...

WJEC GCSE Additional Science Teacher’s Notes
13. Why are high temperatures and pressures needed for nuclear fusion
High temperatures and pressures are needed to ensure that enough protons get close enough for
the process of nuclear fusion to occur.
14. What are deuterium and tritium How are they different to ‘normal’ hydrogen
Deuterium and tritium are isotopes of hydrogen. They both contain a single proton (like normal
hydrogen) but a deuterium nucleus has an extra neutron, and tritium has two extra neutrons.
15. What is a plasma
A plasma is an ionised gas.
16. How is the plasma of deuterium and tritium confined inside a tokamak reactor
A toroidal (ring doughnut) shaped magnetic field confines the plasma inside the tokamak
reactor.
17. How are the high temperatures generated within a tokamak reactor
The high temperatures are generated by passing huge electric currents through the plasma.
18. How could the energy of a nuclear fusion reactor be used to produce electricity
The high kinetic energy of the neutrons emitted during the fusion process could be used to heat
water as the basis of electricity generation.
19. Why do nuclear fusion reactors need a lot of shielding
Nuclear fusion reactors produce huge numbers of high energy neutrons which need to be
contained to prevent damage to the human operators.
Discussion point
Other rival nuclear fusion reactor designs (such as HiPER – the European High Power laser Energy
Research facility) would use high powered lasers to heat a small quantity of deuterium and tritium inside a
small spherical pellet. Such designs have been shown to work, producing small quantities of nuclear fusion.
The trick is to get a continuous feed of fusion fuel into the laser beams in a short enough time to sustain the
reaction. Use the internet to find out about nuclear fusion reactors that use lasers (the process is called
Inertial Confinement Fusion or ICF). How might it compare to tokamak based reactors
Using a search engine with the key words ‘inertial confinement fusion’ will find many different
websites devoted to Laser ICF. Tokamak reactors currently represent the best ‘chance’ of
producing a commercially viable nuclear fusion reactor.
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