10. Nuclear fission occurs in a nuclear reactor. (i) What is nuclear fission?
(ii) What is the role of neutrons in nuclear fission? (iii) Name a fuel used in a nuclear reactor.
(iv) In a nuclear reactor, how can the fission be controlled or stopped?
(6) (6) (6) (6)
(v) How is the energy produced in a nuclear reactor used to generate electricity? (9) (vi) Give one advantage and one disadvantage of a nuclear reactor as a source of energy. (5)
2005
12. (d) Na-25 is a radioactive isotope of sodium. It has a half-life of 1 minute. What is meant by radioactivity? Name a detector of radioactivity. Explain the term half-life.
What fraction of a sample of Na-25 remains after 3 minutes? Give one use of a radioactive isotope.
Higher Level 2012
8. Nuclear fission reactors are used as an energy source in many parts of the world, but it is only recently that the use of nuclear fusion as a possible power source is achieving some encouraging results.
The ITER nuclear facility at Caderache in south-east France is a global collaboration that has been formed to ‘demonstrate that fusion is an energy source of the future’. It is expected to begin testing in 2016.
Energy can be produced in a fusion reaction by combining a deuterium and a tritium nucleus as follows:
1 2 H + 1 3 H → 2 4 He + n + energy
deuterium helium
(6) (6) (6) (6) (4)
energy tritium neutron (i) Distinguish between nuclear fission and nuclear fusion. (12)
(ii) What are the advantages of fusion over fission in terms of fuel sources and reaction products?
