Background radiation sources question

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Homework Statement:
Hello, I have been revising and found a question concerning background radiation. I am not struggling too greatly to name the sources of background radiation but rather in understanding what the question is asking;

"Name the main sources of background radiation and state their relative importance"

By stating their relative importance does this mean state how greatly they contribute to the total background radiation? And perhaps considering how afflicting these sources are in relation to their dose? i.e. although radon gas is arguably the largest contributor less people are afflicted by this natural source than say the victims of the bombings of Hiroshima, even thought the total contribution of nuclear weapons is substantially less at ~0.3%.
Thank you to anyone who replies 👍
Relevant Equations:
Background radiation
Several sources of background radiation include;
  • Radon gas from soil, rocks and building minerals; since radon is produced by the decay of uranium ore present in certain rocks e.g. granite. On Earth, approximately 42-51% of background radiation is the result of naturally radioactive gases like radon.
  • Cosmic rays; being charged particles from the the Sun and stars that collide with atoms in Earth’s upper atmosphere and magnetic field to produce an air shower of radiation, typically beta and gamma radiation, although most do not reach the surface of the Earth, contributing ~10-14% of the overall background radiation. The dose from cosmic radiation varies in due to differences in elevation and to the effects of the earth’s magnetic field at different locations on Earth.
  • Another source of radiation is ingested internally from food and drink; as two of the essential elements of the human body, being potassium and carbon, have radioactive isotopes that significantly contribute to the background radiation dose on Earth at 9-12%.
  • There are abundant artificial sources also, since human activity has contributed to the overall background radiation through the use of medical X-rays, implementing nuclear weapons testing and producing radioactive waste from nuclear power stations.
    • In particular, medical imaging, e.g. using X-rays, and employing radioisotopes for diagnostics and radiation treatment contribute 12-15% of the overall background radiation.
    • Nuclear testing in the between the 1940s-1960s resulted in a substantial increase in radioactive contamination which affected not just the immediate surrounding area but additionally dispersed globally, i.e as a result of nuclear fallout, contributing ~ 0.3%
My query is I do not know whether I have suitably responded to this question, specifically in discussing their relative importance.
 

Answers and Replies

  • #2
Halc
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"Name the main sources of background radiation and state their relative importance"
It would help if there was some context to the question. What course is asking this question?

My first thought on reading that statement was to think of the cosmic microwave background radiation (CMBR) which has significant importance to the big bang theory, but your answers seem to suggest a course looking for importance to human health.
 
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It would help if there was some context to the question. What course is asking this question?

My first thought on reading that statement was to think of the cosmic microwave background radiation (CMBR) which has significant importance to the big bang theory, but your answers seem to suggest a course looking for importance to human health.
Thank you for your reply. This is just a a standard A-Level question I was revising, focusing on the topic on nuclear radiation.
 
  • #4
I think it makes sense to "state their relative importance" by comparing 2 factors amongst sources: radiation doses and the source's radiation's effects.
For the doses comparison, you can visit the "National Council on Radiation Protection & Measurements (NCRP), Report No. 160", while for the effects I think you can research about "effects on human" and "role in science".
 
  • #5
Steve4Physics
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By stating their relative importance does this mean state how greatly they contribute to the total background radiation?"
Yes - but biggest-to-smallest is sufficient (unless your syllabus specifically requires you to learn approximate percentages - which is extremely unlikely).

And perhaps considering how afflicting these sources are in relation to their dose?
No. The wording in the question would be much more specific if that were required.

The amount of detail required in the answer depends on how many marks are allocated. Suppose there are 4 marks. Try to make 5 points to cover yourself. In this case my answer would be:

The main contributors to background radiation are (in order):
- radon (alpha emitter) produced by naturally occurring radioisotopes in the earth’s crust;
- other naturally occurring radioisotopes in rocks and building material;
- artificial sources (e.g. medical sources, nuclear power plants);
- cosmic rays.
The above relative importance may be location-dependent. E.g. the above ordering might not apply near Chernobyl (leakage of artificial sources).

Note 1. I haven't included food/drink in the above list as the question is about background radiation, not human exposure level.

Note 2. If you get the chance, look through old papers and their mark-schemes. You can then see what level of detail is required for these descriptive types of question.
 

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