In a thermal nuclear reactor, sustaining and controlling the chain reaction is essential for safe power generation.
Which of the following statements is correct?
The moderator material should ideally consist of nuclei with high mass numbers so that elastic collisions result in the maximum possible energy transfer from fast neutrons.
Control rods, made of materials with very small neutron capture cross-sections, are lowered into the core to absorb excess thermal neutrons.
To maintain a steady rate of energy release, the average number of neutrons produced in each fission event that go on to initiate a subsequent fission must be exactly one.
Natural uranium is enriched with Uranium-238 because Uranium-238 has a much larger probability of undergoing fission when absorbing a thermal neutron than Uranium-235.
128 exam-style questions on AQA A Level Physics Radioactivity (A-level only), covering Rutherford scattering (A-level only), $\alpha$ , $\beta$ and $\gamma$ radiation (A-level only), Radioactive decay (A-level only), Nuclear instability (A-level only), Nuclear radius (A-level only), Mass and energy (A-level only), Induced fission (A-level only), and Safety aspects (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.