Nuclear Power

    OCR
    GCSE

    Nuclear power generation relies principally on induced nuclear fission, where a slow-moving neutron is absorbed by a large, unstable nucleus (typically Uranium-235 or Plutonium-239), causing it to split into two smaller daughter nuclei. This process releases significant thermal energy via the kinetic energy of the particles and emits two or three neutrons, which must be moderated to sustain a controlled chain reaction. Candidates must distinguish fission from nuclear fusion, the process powering stars where light nuclei join under extreme temperature and pressure to overcome electrostatic repulsion. Assessment focuses on the function of reactor components, the balancing of nuclear equations, and the evaluation of environmental impacts compared to fossil fuels.

    0
    Objectives
    3
    Exam Tips
    3
    Pitfalls
    4
    Key Terms
    4
    Mark Points

    What You Need to Demonstrate

    Key skills and knowledge for this topic

    • Award 1 mark for stating that a slow-moving neutron is absorbed by a Uranium-235 nucleus, causing it to become unstable and split
    • Credit responses that identify the release of 2-3 neutrons and kinetic energy as the primary products of the fission reaction
    • Award 1 mark for explaining that control rods (boron) absorb excess neutrons to regulate the rate of the chain reaction
    • Candidates must link the high temperatures required for fusion to the kinetic energy needed to overcome electrostatic repulsion between positively charged nuclei

    Example Examiner Feedback

    Real feedback patterns examiners use when marking

    • "You correctly identified fission as splitting atoms, but you must specify that a *neutron* initiates this process"
    • "Good comparison of energy outputs. To improve, explain *why* fusion requires such high temperatures using ideas about charge"
    • "You mixed up the moderator and control rods — remember: Moderator slows (Modifies speed), Control rods absorb (Control rate)"
    • "Strong evaluation of environmental impact. For full marks, mention the specific issue of long-term storage for high-level radioactive waste"

    Marking Points

    Key points examiners look for in your answers

    • Award 1 mark for stating that a slow-moving neutron is absorbed by a Uranium-235 nucleus, causing it to become unstable and split
    • Credit responses that identify the release of 2-3 neutrons and kinetic energy as the primary products of the fission reaction
    • Award 1 mark for explaining that control rods (boron) absorb excess neutrons to regulate the rate of the chain reaction
    • Candidates must link the high temperatures required for fusion to the kinetic energy needed to overcome electrostatic repulsion between positively charged nuclei

    Examiner Tips

    Expert advice for maximising your marks

    • 💡When describing a chain reaction, explicitly state that released neutrons are absorbed by *other* Uranium nuclei to trigger further fission
    • 💡In 6-mark evaluation questions, contrast the high energy density of nuclear fuel (small mass, huge energy) with the long-term economic cost of decommissioning
    • 💡Use the term 'daughter nuclei' rather than 'parts' or 'bits' when describing the split fragments of the uranium atom

    Common Mistakes

    Pitfalls to avoid in your exam answers

    • Confusing the function of the moderator (slowing neutrons to ensure absorption) with control rods (absorbing neutrons to stop/slow the reaction)
    • Stating that nuclear power plants release carbon dioxide during operation (confusing construction emissions with operational emissions)
    • Describing the product of fusion merely as 'energy' without identifying the formation of a heavier nucleus (Helium) from lighter nuclei

    Study Guide Available

    Comprehensive revision notes & examples

    Read Study Guide

    Key Terminology

    Essential terms to know

    Induced nuclear fission and chain reactions
    Functions of reactor components (moderator, control rods, coolant, shielding)
    Nuclear fusion principles and conditions
    Safety, waste management, and environmental impact

    Likely Command Words

    How questions on this topic are typically asked

    Describe
    Explain
    Evaluate
    Compare
    Calculate

    Ready to test yourself?

    Practice questions tailored to this topic