1. 1
   A laboratory technician needs to move a sealed radioactive source from a storage safe to a demonstration bench for a lesson on radioactivity, following the school's safety procedures for handling radioactive materials.

   (a)

   Which piece of equipment should the technician use to move the source, in order to increase the distance between the source and their body?

   [1 mark]

   • ALong-handled tongs
   • BBare hands
   • CA pencil
   • DA magnifying glass

   (b)

   Which of the following actions would reduce the technician's overall radiation dose while carrying out the demonstration?

   [1 mark]

   • ARemoving all shielding from around the source
   • BHolding the source as close to the body as possible
   • CPointing the source directly at their own eyes for a clearer view
   • DMinimising the time spent close to the source

   (c)

   State two further safety precautions, other than using tongs and minimising handling time, that the technician should follow when using the radioactive source during the classroom demonstration.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A nuclear power plant worker is responsible for handling fuel rods in the reactor core, which emit strongly penetrating gamma radiation, and the worker operates remote-controlled machinery from behind a thick concrete and lead wall.

   (a)

   What is the main purpose of this thick wall?

   [1 mark]

   • ATo speed up the rate of radioactive decay
   • BTo increase the temperature of the reactor
   • CTo absorb (shield) the radiation and prevent it reaching the worker
   • DTo generate additional electrical power

   (b)

   The worker also wears a small device clipped to their clothing throughout their shift, which records the total amount of radiation they have been exposed to. What is this type of device commonly used for in radiation safety?

   [1 mark]

   • ACooling the nuclear reactor
   • BMonitoring an individual worker's cumulative radiation dose
   • CGenerating the gamma radiation used in the reactor
   • DIncreasing the worker's exposure time to the source

   (c)

   Explain why remote-controlled machinery, operated from behind a thick concrete and lead wall, is used to handle the fuel rods, rather than a worker directly handling them with long-handled tools as might be used for a weaker laboratory source.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A cancer treatment centre uses a gamma ray source to treat a tumour deep inside a patient's body, while the treatment team tries to minimise the radiation dose received by the surrounding healthy tissue and by staff working nearby.

   (a)

   Explain how the treatment team could use the ideas of shielding and distance to protect staff working in the treatment room while the source is in use, and explain why gamma radiation, rather than alpha or beta radiation, is chosen for this deep-tissue treatment.

   [3 marks]

   (b)

   The treatment team also carefully limits the total exposure time of the gamma source during each session, and positions the patient so the beam is focused as precisely as possible on the tumour from several different angles. Explain how limiting exposure time and focusing the beam from several angles both help to reduce unwanted radiation damage, and suggest one reason why using several different angles, rather than one continuous angle, is particularly effective at protecting the healthy tissue surrounding the tumour.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A company transports sealed radioactive sources by road between a supplier and various hospitals and industrial sites, and must ensure the safety of drivers, warehouse staff and members of the public throughout the process.

   (a)

   Explain the three main safety precautions used to reduce a person's exposure to ionising radiation (reducing exposure time, increasing distance, and using shielding), and describe, giving specific examples relevant to the transport and handling of sealed sources by road, how each of these three precautions could be applied in practice by the company's drivers and warehouse staff.

   [6 marks]

   (b)

   The company is reviewing its safety procedures after a new industrial customer requests a much stronger gamma source than any it has transported before, to be used in an industrial thickness gauge. Explain how the company's approach to reducing exposure time, increasing distance and using shielding might need to change for this stronger source compared with the weaker sources it usually transports, and discuss why simply relying on one of these three precautions alone (for example, shielding) would not be considered good safety practice, even if that one precaution alone seemed sufficient to reduce the dose to an acceptable level.

   [6 marks]

   Total for question 4: 12 marks

End of questions