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‫الرحيم‬
ّ ‫الرمحن‬
ّ ‫بسم هللا‬
Course :
Health Safety & Radiation Protection (RAD453)
Chapter 3: Sources of Radiation
Omrane KADRI, Ph.D.
[email protected]
Office 2021
1
Outline
1) Introduction
2) Natural Background Radiation
3) Man-Made radiation sources
4) Source of exposure
5) How radiation is used
6) Summary
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2) Introduction
Scientists have studied radiation for over 100 years and •
we know a great deal about it.
Radiation is part of nature. All living creatures, from the •
beginning of time, have been, and are still being, exposed
to radiation.
Sources of radiation can be divided into two categories: •
Natural Background Radiation •
Man-Made Radiation •
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3) Natural Background Radiation
Cosmic Radiation •
Terrestrial Radiation •
Internal Radiation •
Radon •
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3) Cosmic Radiation
The earth, and all living things on it, are
constantly bombarded by radiation from outer
space, similar to a steady drizzle of rain.
•
Charged particles from the sun and stars
interact with the earth’s atmosphere and
magnetic field to produce a shower of
radiation.
•
The amount of cosmic radiation varies in
different parts of the world due to differences
in elevation and to the effects of the earth’s
magnetic field.
•
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3) Terrestrial Radiation
Radioactive material is also found throughout
nature in soil, water, and vegetation.
•
Important radioactive elements include uranium
and thorium and their radioactive decay products
which have been present since the earth was
formed billions of years ago.
•
Some radioactive material is ingested with food
and water. Radon gas, a radioactive decay product
of uranium is inhaled.
•
The amount of terrestrial radiation varies in
different parts of the world due to different
concentrations of uranium and thorium in soil.
•
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3) Internal Radiation
People are exposed to radiation from radioactive
material inside their bodies. Besides radon, the most
important internal radioactive element is naturally
occurring potassium-40 but uranium and thorium are
also present.
•
The amount of radiation from potassium-40 does not
vary much from one person to another. However,
exposure from radon varies significantly from place to
place depending on the amount of uranium in the
soil.
•
On average, in the United States radon contributes
55% of all radiation exposure from natural and manmade sources. Another 11% comes from the other
radioactive materials inside the body.
•
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3) Radon

Naturally occurring radioactive gas

Second leading cause of lung cancer

Estimated 14,000 deaths per year

Easy to test for

short and long term tests available

EPA guideline is 4 pCi/L

Fixable

Radon in water from drilled wells can also be an entry method
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4) Man-Made Radiation Sources
Annual Dose from Background Radiation
Total exposure
Man-made sources
Medical X-Rays
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Radon 55.0%
Other 1%
Internal 11%
Cosmic 8%
Man-Made 18%
Terrestrial 6%
Nuclear
Medicine 4%
Consumer
Products 3%
Total US average dose equivalent = 360 mrem/year
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4) Man-Made Radiation Sources
The Nuclear Regulatory Commission and other federal and •
state agencies regulate exposure from man-made
radiation sources. Different regulations apply to two
distinct groups:
Members of the public–
Occupational workers–
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5) Source of Exposure
Examples of man-made sources •
of radiation to members of the
public:
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Student activity: Guess which
sources contribute the most to
man-made radiation exposure:
Natural gas –
(1) –
Lantern mantles –
(2) –
Medical diagnosis –
(3) –
Building materials –
(4) –
Nuclear power plants –
(5) –
Coal power plants –
(6) –
Tobacco –
(7) –
Phosphate fertilizers –
(8) –
•
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0
0.4
0.2
Nuclear Plant
Lantern
Mantles
2
Coal Plant
4
Natural Gas
10
Phosphate
Fertilizer
30
Building
Material
70
Medical
Smoking
(perWeek)
5) Source of Exposure
Annual Average Dose (mrem/year)
man-made source
60
60
50
40
25
20
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0.15
6) How Radiation is Used
Science •
carbon dating to determine age –
instruments to measure density –
power satellites –
Medicine •
x-rays and nuclear medicine –
diagnose and treat illness –
Industry •
smoke detectors –
kill bacteria and preserve food –
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6) How Radiation is Used
Radiation in Medicine
Radiation used in •
medicine is the largest
source of man-made
radiation.
Most of our exposure is •
from diagnostic x-rays.
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Summary
• Sources of Radiation Exposures
– Occupational (work-related)
• Radiography in aircraft activity
– Non-occupational
• Naturally occurring sources
– Radon
– Sources in the human body
– Sources in earth’s crust (terrestrial)
– Cosmic radiation
• Manmade sources
– Tobacco products Medical radiation
– Building materials Consumer products
– Industrial sources Atmospheric testing of nuclear
weapons.
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Quiz N°2
Take a white paper •
Write (on top of the page): •
Quiz N°2 (RAD 453) –
Full Name: –
Student Number: –
Answer: •
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