iaea sources of radiation natural radiation - cosmic radiation day 3 – lecture 8 1
TRANSCRIPT
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Sources of Radiation
Natural Radiation - Cosmic Radiation
Day 3 – Lecture 8
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Objective
To learn about the Cosmic radiation from space, cosmogenic radionuclides, variance of cosmic radiation with latitude and altitude, and exposure from cosmic radiation
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Content
Cosmic radiation
Cosmogenic radionuclides
Radiation variance with latitude and altitude
Dose rates from cosmic radiation
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Types of Cosmic Radiation
Primary cosmic radiation
Secondary cosmic radiation
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Primary Cosmic Radiation
Made up of extremely high energy particles (up to 1018 eV)
Composed mostly of protons or sometimes larger particles
Large percentage comes from outside solar system
Some comes from sun in form of solar flares
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Secondary Cosmic Radiation
Produced by interaction of primary cosmic radiation with the atmosphere
Is what we actually receive here on Earth
Lower energy radiations in the form of photons, electrons, neutrons, and muons
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Background Radiation
Galactic radiation is a component of the
background radiation on earth.
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Background Radiation
Cosmic radiation contributes to the background radiation on earth. The earth’s atmosphere provides shielding from most of the cosmic radiation.
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Background Radiation
The dose from cosmic radiation is reduced at lower altitude due to the additional shielding by the earth’s atmosphere.
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Cosmogenic Radionuclides
Nuclide Half-life Source Natural Activity
14C 5730 yr Cosmic-ray interactions, 14N(n,p)14C
0.22 Bq/g
3H 12.3 yr Cosmic-rayInteractionswith N and O
1.2 x 10-3 Bq/kg
7Be 53.3 days Cosmic-rayInteractionswith N and O
0.01 Bq/kg
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Cosmic Ray DosesSubsonic Flight at 11 km
RouteFlight Duration
(hrs)Dose per round trip
(Gy)
Los Angeles – Paris 11.1 48
Chicago – Paris 8.3 36
New York - Paris 7.4 31
New York - London 7.0 29
Los Angeles - New York 5.2 19
Sydney - Acapulco 17.4 44
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Cosmic Ray DosesSupersonic Flight at 19 km
RouteFlight Duration
(hrs)Dose per round trip
(Gy)
Los Angeles – Paris 3.8 37
Chicago – Paris 2.8 26
New York – Paris 2.6 24
New York – London 2.4 22
Los Angeles - New York 1.9 13
Sydney - Acapulco 6.2 21
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Typical Cosmic Ray Dose Rates
4 x 10-8 Sv/hr at ground level in Northeastern US
2 x 10-7 Sv/hr at 4.6 km altitude
3 x 10-6 Sv/hr at 16.8 km altitude
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Natural Radiation Exposure Around the World
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Effective Dose Equivalent to a Member of the Population of the United States
Source
Average AnnualEffective Dose Equivalent Sv mrem
Inhaled (radon and decay products) 2000 200
Other Internbally Deposited Radionuclides
390 39
Terrestrial Radiation 280 28
Cosmic Radiation 27 27
Cosmogenic Radioactivity 10 1
Rounded Total from Natural Sources 3000 300
Rounded Total from Artificial Sources 600 60
Total 3600 360
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Sources of Radiation ExposureIn the United States
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Where to Get More Information
Cember, H., Johnson, T. E, Introduction to Health Physics, 4th Edition, McGraw-Hill, New York (2009)
UNSCEAR, Sources and Effects of Ionizing Radiation, 2008 Report to the General Assembly with Scientific Annexes, United Nations, New York, 2008
International Atomic Energy Agency, Postgraduate Educational Course in Radiation Protection and the Safety of Radiation Sources(PGEC), Training Course Series 18, IAEA, Vienna (2002)