Radiation Safety and You
Brian Kessler
Zettl Group Safety Talk
September 7, 2006
Types of Radiation
• Ionizing Radiation– Ionization potentials of the elements range
from 3.89 eV (Cs) to 24.6 eV (He)• Alpha Rays – He4 nucleas• Beta Rays – electrons/positrons• X-rays and Gamma Rays - photons with λ<50 nm
• Non-Ionizing Radiation• Radio waves, Micro waves, visible light• Neutrons – interact with nuclei
http://ehswprod.lbl.gov/EHSTraining/GERT/html/02whatis.html
Radiation Producing Machines in the Lab
• Transmission Electron Microscope– Electrons, Secondary
X-Rays
• Scanning Electron Microscope– Electrons, Secondary
X-Rays
• Electron Beam Evaporator
Dosage and How to Measure It
• Units:– Gray (Gy) = J/kg, physical amount of energy
absorbed– Sievert (Sv) = Q*N*Gy, biological effect of
energy absorbed (1 Sv = 100 rem)• Quality Factor (Q) depends on the type of radiation
– photons, electrons Q=1, Protons Q=5, Alpha particles Q=20
• N Factor (Q) depends on the exposed area– Gonads, N=0.20, Colon, Lung, Stomach N=0.12,
Bladder, Brain, Uterus, N = 0.05, Skin N=0.01
http://www.npl.co.uk/ionrad/quantities.html
Typical Exposure
• Significant Background Sources of Radiation– Cosmic Rays, Radon
Gas, Naturally Occuring Isotopes, Medical Diagnostics
• Annual Dose: 2 mSv• Fly LA-NY: 0.025 mSv• GI X-Ray Series : 2.2 mSv
http://ehswprod.lbl.gov/EHSTraining/GERT/html/02whatis.html
Radiation Danger
• Primary Risk - Cancer– Risk to General Population:
20%– Risk to individual with 100
mSv excess exposure: 20.4%
• Secondary Risk – Genetic Effects– Increased Risk of Mental
Retardation in Exposed Fetuses: 0.8%
http://ehswprod.lbl.gov/EHSTraining/GERT/html/04risks.html
How to Protect Yourself
• ALARA – A Low As Reasonably Achievable– Minimize Time– Maximize Distance– Use Appropriate
Shielding• Alpha Particles – a sheet
of paper
• Beta Particles – a sheet of metal
• Gamma Rays – thick lead or concrete
http://www.ehs.berkeley.edu/radsafety/rpmtraininghandout.pdf
What You Should Do Now
• Review and Complete Your General Employee Radiation Training through LBL:– http://ehswprod.lbl.gov/EHSTraining/GERT/default.htm
• Review Berkeley EHS Radiation Safety Website:– http://www.ehs.berkeley.edu/radsafety.html
Stay Safe!
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