Lesson 3.8.1.8

3.8.1.8 Safety aspects Quiz: AQA Physics, Unit 8

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.8.1.8, Safety aspects: 20 multiple choice questions for the AQA Physics (7408), Unit 8: Nuclear physics (A-level only), written with Revision Ninja.

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The 20 questions

  1. Why is the remote handling of reactor fuel used?

    • to limit the radiation dose to workers from the highly radioactive fuel and waste
    • to avoid contact between the fuel and air only
    • because the fuel is non-radioactive and needs robots to move it
    • because remote handling makes the fuel cooler

  2. Which material is commonly used to shield gamma radiation?

    • a thin layer of aluminium foil
    • a thin sheet of paper
    • a few centimetres of air
    • dense material such as lead or thick concrete

  3. What is the purpose of an emergency shut-down in a reactor?

    • to vent steam to reduce the pressure in the turbines
    • to increase the reactor power briefly for safety tests
    • to stop the chain reaction quickly, for example by inserting control rods fully into the core
    • to remove the fuel permanently from the reactor vessel

  4. What is high-level radioactive waste?

    • the building materials used to construct the reactor
    • water used to cool the reactor, which is at room temperature
    • paper and cloth used in cleaning the plant, which is low level
    • spent fuel, which is highly radioactive and needs cooling and long-term storage

  5. Why must some radioactive waste be stored for very long periods?

    • some isotopes have long half-lives, so they remain hazardous for thousands of years
    • the waste keeps its radioactivity only when in contact with water
    • the waste must be cooled so that it decays faster
    • the waste becomes stable after a few hours of decay

  6. Which is a standard safety principle when handling radioactive sources?

    • keep the source close to the body so that the dose is uniform
    • maximise time near the source and minimise distance to it
    • minimise time of exposure, maximise distance from the source, and use shielding
    • store the source in a sealed glass container with no shielding

  7. A worker at 2 m from a gamma source receives a dose rate of 40 microsieverts per hour. What dose rate does the worker receive at 4 m?

    • 5 microsieverts per hour
    • 10 microsieverts per hour
    • 80 microsieverts per hour
    • 20 microsieverts per hour

  8. A source is moved from 1 m to 3 m away from a worker. By what factor does the dose rate change?

    • a factor of 6
    • a factor of 9
    • a factor of 3
    • a factor of 27

  9. Which statement about the balance of risk and benefit in nuclear technology is correct?

    • risks are only relevant inside a laboratory and not in the wider world
    • radiation has no benefits when used in medicine
    • the benefits are always greater than the risks, so no balance is needed
    • benefits such as electricity or medical diagnosis must be weighed against the risks of exposure and waste

  10. Which source of background radiation is present naturally everywhere?

    • cosmic rays produced only by man-made satellites
    • fallout from nuclear weapons only
    • medical X-rays only
    • radon gas, released from rocks and soil

  11. A radiation worker receives 4 mSv in a year, where the annual limit is 20 mSv. What fraction of the limit has been used?

    • 4%
    • 2%
    • 80%
    • 20%

  12. Why is a gamma source preferred to an alpha source for measuring the thickness of thick steel?

    • alpha is easier to detect through thick steel than gamma
    • alpha has a longer range in steel than gamma
    • gamma penetrates thick steel and can be detected on the far side, whereas alpha is stopped by very thin layers
    • gamma is absorbed completely by a few millimetres of steel

  13. Why is dense concrete used as shielding around a reactor?

    • it reflects all gamma rays back into the reactor core
    • it increases the activity of nearby sources
    • it slows alpha particles to zero energy
    • it absorbs gamma radiation and neutrons, reducing the dose outside the reactor

  14. Why is cooling still needed after a reactor is shut down?

    • decay heat is zero after shut-down, so coolant is unnecessary
    • coolant is only needed to lubricate the control rods
    • decay heat from the fuel can reach damaging temperatures, so cooling must continue after shut-down
    • coolant must be removed to start the chain reaction again

  15. Which factors determine the risk from a sealed radioactive source?

    • its mass only, since heavier sources are more dangerous
    • its colour and surface finish only
    • the year in which the source was manufactured
    • its activity, the type of radiation emitted, and the time and distance of exposure

  16. A worker receives a dose of 2.0 mSv over 30 days. What is the average daily dose?

    • about 15 mSv per day
    • about 0.0067 mSv per day
    • about 0.067 mSv per day
    • about 0.60 mSv per day

  17. Which statement about radioactive waste management is correct?

    • waste only needs storage if it is in liquid form
    • waste is classified by activity and half-life, and is stored or disposed of with shielding and containment appropriate to its class
    • all waste is recycled completely, so none needs storing
    • all waste is safe for ordinary landfill after one year

  18. Why does the activity of spent fuel fall with time, yet the material remains dangerous?

    • the activity falls to zero within a single day
    • the activity is constant because all half-lives are infinite
    • the activity rises as fission products accumulate in the fuel
    • short-lived isotopes decay quickly, but long-lived isotopes keep the activity hazardous for many years

  19. Why must radiation workers wear a dosimeter?

    • to act as a control rod if the reactor overheats
    • to shield the worker from alpha particles
    • to record the dose received, so that total exposure can be kept within safe limits
    • to measure the activity of the source being handled

  20. Which reactor safety feature acts without an external power supply?

    • an operator's switch in the control room that must be held down
    • a pump that draws extra coolant from a mains-powered supply
    • a fuel enrichment monitor that reports on the isotope mix
    • gravity-driven insertion of control rods into the core during shut-down

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