Background radiation Flashcards
where does background radiation come from
- natural sources such as rocks and cosmic rays from space
- man-made sources such as the fallout from nuclear weapons
testing and nuclear accidents.
dose of radiation is measured in
Radiation dose is measured in sieverts (Sv)
1000 millisieverts (mSv) in Sv
1000 millisieverts (mSv) = 1 sievert (Sv)
How might the level of background radiation you are exposed to be affected by
The level of background radiation and radiation dose (you are exposed to) may be
affected by occupation and/or location
people living in certain parts of the uk experience a greater level of background radiation e.g. people living in regions with large amounts of granite e.g. Cornwall, Northern Scotland
people working in certain occupations can experience greater levels of background radiation
cabin crew and airline pilots may be exposed to higher levels of cosmic radiation
HOW TO DETECT THE RADIATION RELEASED
USING A GEIGER-MULLER TUBE
Explain why the geiger muller tube still gives a reading, if there is no radioactive isotope near
This is because there is radiation all around us, all the time
What is background radiation
The radiation which surrounds us at all times, arising from both natural and man-made sources
State some natural sources of background radiation
(radioactive) rocks - including granite - we find it in the ground - (in some parts of uk such as cornwall this can be a major source of background radiation)
cosmic rays from space - cosmic rays (very high energy particles which travel through space and crash into the Earth’s atmosphere)
– radiation from space
state some man-made sources of background radiation
fallout from nuclear weapons - nuclear weapons testing has released radioactive isotopes into the environment for decades.
nuclear accidents - radioactive isotopes are released by accidents at nuclear power stations
explain why the hazards associated with
radioactive material differ according to the half-life involved.
A short half life means the activity falls quickly - because the nuclei are very unstable and rapidly decay
Sources with a short half-life can be dangerous because of the high amount of radiation they emit at the start, but they quickly become safe
A long half life means the activity falls more slowly because most of the nuclei don’t decay for a long time - the source just sits there, releasing small amounts of radiation for a long time.
This can be dangerous because nearby areas are exposed to radiation for (millions of) years
what are nuclear radiations used for
Nuclear radiations are used in medicine for the:
- exploration of internal organs
- control or destruction of unwanted tissue
describe how nuclear radiations are used in medicine for the exploration of internal organs
Radioactive tracers are used to in the exploration of internal organs
This can be very useful .E.g. to check whether an organ is functioning properly or to see if a cancer has developed
Certain radioactive isotopes can be injected into people (or swallowed) and their progress around the body can be followed using an external detector. A computer converts the reading to display where the strongest reading is coming from.
A tracer is a radioactive isotope that can be used to track the movement of substances, like blood, around the body
Iodine-123 is a radioactive isotope, commonly used as a tracer in medicine
Describe how iodine-123 can be used to detect whether the thyroid gland is absorbing as it normally should do
Iodine-123 is absorbed by the thyroid gland just like normal iodine-127 but it is radioactive and gives out gamma radiation
This radiation can be detected outside the patient
The radiation produced can be monitored to see if the thyroid gland is working correctly
(if the scan shows that the thyroid has absorbed too much or too little iodine then the doctor can use this diagnose the patient’s condition)
Issues to consider when using radioactive tracers
The tracer must emit radiation that can pass out of the body and be detected (usually tracers emit gamma or beta radiation - alpha emitters are not used as tracers, as alpha particles will not pass out of the body)
The tracer must not be strongly ionising to minimise damage to body tissue ( this makes gamma emitters good tracers
The tracer must not decay into another radioactive isotope
The tracer must have a short half-life so it not present in the body for a long period. (so radioactivity inside the patient quickly disappears)
How can a tracer be used to detect a leak in a pipe
A leak in an underground industrial pipe can be found by adding a radioactive tracer to the liquid in the pipe.
This radiation travels through the pipe
A detector is moved along the ground above where the pipe
is buried.
The count rate will be found to increase where
the pipe is leaking as a larger amount of liquid containing the
radioactive tracer will collect there.
the radiation from the radioactive source will be picked up above the ground, enabling the leak in the pipe to be detected.
