Risks of Radiation

    OCR
    GCSE

    Ionising radiation poses biological risks by removing electrons from atoms to form ions, which can damage DNA strands within living cells. This damage may lead to mutations causing cancer or, at high acute doses, cell death and radiation sickness. A critical distinction must be made between irradiation, where an object is exposed to a source, and contamination, where radioactive atoms are deposited on or in an object. Safety protocols prioritize the reduction of dose, measured in Sieverts (Sv), by maximizing distance, minimizing exposure time, and utilizing appropriate shielding materials like lead or concrete.

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    Objectives
    3
    Exam Tips
    4
    Pitfalls
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    Key Terms
    5
    Mark Points

    What You Need to Demonstrate

    Key skills and knowledge for this topic

    • Award 1 mark for explicitly stating that irradiation is exposure to radiation from an external source, whereas contamination involves radioactive atoms getting onto or into an object
    • Credit responses that link the high ionising power of alpha radiation to significant cellular damage only if the source is ingested or inhaled
    • Award 1 mark for identifying that gamma sources pose the greatest external hazard due to their high penetrating power allowing them to reach internal organs
    • Candidates must explain that safety precautions (e.g., lead aprons, tongs) reduce risk by minimising exposure time, increasing distance, or absorbing radiation
    • Award 1 mark for linking the unit Sievert (Sv) to the biological harm caused by radiation dose

    Example Examiner Feedback

    Real feedback patterns examiners use when marking

    • "You have correctly identified the type of radiation, but you must explain *why* it is dangerous in this specific context (internal vs external)"
    • "Be careful not to confuse irradiation with contamination—remember, light irradiates you but doesn't make you glow; radiation is similar"
    • "Good calculation of the remaining count rate, but you forgot to subtract the background radiation first"
    • "To achieve full marks on this evaluation, compare the risks of the source directly with the benefits of its use"

    Marking Points

    Key points examiners look for in your answers

    • Award 1 mark for explicitly stating that irradiation is exposure to radiation from an external source, whereas contamination involves radioactive atoms getting onto or into an object
    • Credit responses that link the high ionising power of alpha radiation to significant cellular damage only if the source is ingested or inhaled
    • Award 1 mark for identifying that gamma sources pose the greatest external hazard due to their high penetrating power allowing them to reach internal organs
    • Candidates must explain that safety precautions (e.g., lead aprons, tongs) reduce risk by minimising exposure time, increasing distance, or absorbing radiation
    • Award 1 mark for linking the unit Sievert (Sv) to the biological harm caused by radiation dose

    Examiner Tips

    Expert advice for maximising your marks

    • 💡When evaluating medical isotopes, explicitly trade off the benefit of a short half-life (reduced patient exposure) against the need for it to last long enough for the procedure
    • 💡Structure safety answers using the 'Time, Distance, Shielding' framework—be specific (e.g., 'use tongs to increase distance' rather than just 'move away')
    • 💡In 6-mark extended response questions about nuclear waste, you must address both the type of radiation emitted and the duration of the risk (half-life)

    Common Mistakes

    Pitfalls to avoid in your exam answers

    • Incorrectly stating that objects exposed to radiation (irradiated) become radioactive themselves
    • Failing to distinguish between the danger of alpha sources outside the body (blocked by skin) versus inside the body (highly damaging to DNA)
    • Vaguely stating radiation 'kills cells' without specifying that lower doses cause DNA mutations leading to cancer, while high doses cause radiation sickness
    • Forgetting to subtract background radiation count rates before performing half-life or risk calculations

    Study Guide Available

    Comprehensive revision notes & examples

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    Key Terminology

    Essential terms to know

    Mechanisms of ionisation and DNA mutation
    Irradiation versus Contamination
    Safety protocols: Time, Distance, Shielding
    Radiation Dose (Sieverts) and Background Radiation
    Perceived risk versus actual risk

    Likely Command Words

    How questions on this topic are typically asked

    State
    Explain
    Calculate
    Evaluate
    Suggest
    Describe

    Practical Links

    Related required practicals

    • •{"code":"P8","title":"Investigation of absorption of radiation","relevance":"Demonstrates the effectiveness of different shielding materials (paper, aluminium, lead) which underpins safety protocols"}

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