Sources of Radiation Natural Radiation Cosmic Radiation IAEA
- Slides: 17
Sources of Radiation Natural Radiation - Cosmic Radiation IAEA Day 3 – Lecture 8 1
Objective To learn about the Cosmic radiation from space, cosmogenic radionuclides, variance of cosmic radiation with latitude and altitude, and exposure from cosmic radiation IAEA 2
Content Ø Cosmic radiation Ø Cosmogenic radionuclides Ø Radiation variance with latitude and altitude Ø Dose rates from cosmic radiation IAEA 3
Types of Cosmic Radiation Ø Primary cosmic radiation Ø Secondary cosmic radiation IAEA 4
Primary Cosmic Radiation Ø Made up of extremely high energy particles (up to 1018 e. V) Ø Composed mostly of protons or sometimes larger particles Ø Large percentage comes from outside solar system Ø Some comes from sun in form of solar flares IAEA 5
Secondary Cosmic Radiation Ø Produced by interaction of primary cosmic radiation with the atmosphere Ø Is what we actually receive here on Earth Ø Lower energy radiations in the form of photons, electrons, neutrons, and muons IAEA 6
Background Radiation Galactic radiation is a component of the background radiation on earth. IAEA
Background Radiation Cosmic radiation contributes to the background radiation on earth. The earth’s atmosphere provides shielding from most of the cosmic radiation. IAEA
Background Radiation The dose from cosmic radiation is reduced at lower altitude due to the additional shielding by the earth’s atmosphere. IAEA
Cosmogenic Radionuclides Nuclide Half-life Source 14 C 5730 yr Cosmic-ray interactions, 14 N(n, p)14 C 0. 22 Bq/g 3 H 12. 3 yr Cosmic-ray Interactions with N and O 1. 2 x 10 -3 Bq/kg 7 Be 53. 3 days Cosmic-ray Interactions with N and O 0. 01 Bq/kg IAEA Natural Activity
Cosmic Ray Doses Subsonic Flight at 11 km Route Los Angeles – Paris Flight Duration Dose per round trip ( Gy) (hrs) 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 17. 4 44 Sydney - Acapulco IAEA
Cosmic Ray Doses Supersonic Flight at 19 km Route Flight Duration Dose per round trip ( Gy) (hrs) 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 IAEA
Typical Cosmic Ray Dose Rates Ø 4 x 10 -8 Sv/hr at ground level in Northeastern US Ø 2 x 10 -7 Sv/hr at 4. 6 km altitude Ø 3 x 10 -6 Sv/hr at 16. 8 km altitude IAEA 13
Natural Radiation Exposure Around the World IAEA 14
Effective Dose Equivalent to a Member of the Population of the United States Average Annual Effective Dose Equivalent Sv mrem Source 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 60 360 IAEA Total 15
Sources of Radiation Exposure In the United States IAEA 16
Where to Get More Information Ø Cember, H. , Johnson, T. E, Introduction to Health Physics, 4 th Edition, Mc. Graw-Hill, New York (2009) Ø UNSCEAR, Sources and Effects of Ionizing Radiation, 2008 Report to the General Assembly with Scientific Annexes, United Nations, New York, 2008 Ø International Atomic Energy Agency, Postgraduate Educational Course in Radiation Protection and the Safety of Radiation Sources(PGEC), Training Course Series 18, IAEA, Vienna (2002) IAEA 17
