P2 - Global warming, Nuclear Radiations, Exploring our solar system Flashcards
What are radioactive materials?
Substances that give out nuclear radiation all the time
What does radioactivity involve?
A change in the structure of the radioactive atom, and the release of one or more of the three types of nuclear radiation
What are the three types of nuclear radiation?
Alpha, beta and gamma
Each type of radiation has a different penetrative power, what does this mean?
The different radiations can pass through different thicknesses of materials
What do alpha, beta and gamma radiations cause?
Ionisation
What can ionisation do?
Damage healthy molecules in living cells, resulting in the death of the cell; this can lead to cancer
What safety measures do people who handle radioactive materials need to take?
Wearing protective clothing, keeping their distance by using tongs to hold the material wherever possible, trying to minimise exposure time, and storing radioactive materials in clearly labelled and shielded containers.
What can absorb alpha particles?
a few centimetres of air, or thin paper
What can beta particles pass through, and what absorbs them?
They can pass through a few centimetres of air and thin paper, can be absorbed by a few centimetres of aluminium
What can gamma rays pass through, and what stops them?
They can pass through a few centimetres of air, thin paper and a few centimetres of aluminium. Needs many centimetres of lead or metres of concrete to stop it
What happens during ionisation?
A particle gains or loses electrons, leaving the atom charged
What type of ion does a gain in electrons make?
A negative ion
What type of ion does a loss of electrons make?
A positive ion
Which alpha radiation emitting material does most smoke detectors contain?
Americium-241
Why do most smoke detectors contain Americium-241, which emits alpha radiation?
The emitted alpha particles ionise air particles and the ions formed are attracted to the oppositely charged electrodes. This produces a current in the circuit. When smoke enters the space between the two electrodes, less ionisation takes place and an alarm is triggered
What is a tracer?
A small amount of a radioactive substance that is put into a system so that its progress through the system can be followed using a radiation detector
What can a beta emitter tracer be used to observe?
How elements such as nitrogen and phosphorus move through a plant, from root to leaf
Why is beta radiation used in a paper thickness gauge?
Because when beta radiation passes through paper, some is absorbed. If the paper thickness is too great, more beta radiation is absorbed; less passes through to the detector. This indicates that the thickness of the paper needs to be reduced.
Why can gamma radiation be used to treat cancer?
Because it destroys cancerous cells
Why can gamma radiation be used to sterilise medical equipment?
Because it can destroy microorganisms like bacteria.
How can non-destructive tests be carried out on welds?
By using gamma radiation. A gamma source is placed on one side of the material, and any cracks/defects are then seen using a detector on the other side.
What happens to spent fuel?
It’s taken to be reprocessed
How is low-level radioactive waste disposed of?
It’s sealed and buried in landfill sites
How is high-level radioactive waste disposed of?
It’s enclosed in glass and stored underground in steel cylinders
