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8/4/2019 Radiation Wk2
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Radiation Safety
and Radiation Applications
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What is Radiation? Natural and man-
made
Studied for over 100years
Particles and Rays
Different effects for
different radiations Not all radiation is
harmful
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What kinds of radiation are there? Alpha Particlesa
Helium nucleus
Beta Particlesb An energetic electron emitted from the nucleus
X-Rays
Light wave emitted from the electrons in an atom Gamma Raysg
Light wave emitted from the nucleus
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Two general categories of
ionizing radiation:
PARTICLES
alpha
neutron
beta
PHOTONS
X-ray
gamma ray
102-5
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This is theelectromagneticSpectrum
Ionizing forms ofelectromagnetic include
Gamma Rays
X-rays UV forms the cusp but
is non-ionizing
Non ionizing are notaddress in this module
Electromagnetic Radiation Spectrum
10^21
10^20
10^1910^18
10^17
10^16
10^15
10^14
10^1310^12
10^11
10^10
10^9
10^8
10^710^6
10^5
10^4
10^3
10^2
10^1Frequency (Hz)
Radio Waves
Micro Waves
Infrared Rays
Visible Light
Ultraviolet Rays
X-rays
Gamma Rays
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Summary of Types of Radiation
Alpha particles Stopped with paper Only a danger if internalized
Beta particles Stopped with cardboard or Plexiglas Can be a danger to skin or if internalized
Gamma rays
Stopped with increasingly dense material Mostly an irradiation hazard
Neutrons Stopped by water
Irradiation and activation hazard
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How do we measure exposure? Geiger-Mueller Tube
Demo
Ionization Chambers
TLD for personnelexposures
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Where can radiation be found? Nuclear Reactors
Power plants
Nuclear Waste
Nature
Naturally occurring
Fallout from atmospherictesting
Homes Radon
Building Materials
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Nuclear Reactors Power plants
Palo Verde
Waste
Spent fuel
Low-level waste
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Radiation in the environment Natural
Uranium and
Thorium in the soil Radon gas
Fallout
Atmospheric testing
CTBT in effect 1963
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Medical Exposures Doses vary tremendously based on type of treatment
US Average: 53 mrem/yr
Examples: Chest x-ray (~20 mrem)
Dental x-ray (hundreds of mrem)
CAT Scan (50-5000 mrem)
Cardiac Catherization (~10 rem)
Radiotherapy (~200 rem each)
Nuclear Medicine (2000mrem/target organ
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Weapons Dose depends on many factors
Size of bomb
Type of bomb Location
Weather
Time
Dirty Bombs
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Internal Sources Our body tissues 39 mrem/yr
Carbon-14
Potassium-40
Radium-226
Diet
Water
Food
Brazil nuts No Salt
Whiskey
Milk
Salad Oil
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Consumer Products US Average 11 mrem/yr
Products include:
Orange fiesta ware
Ceramics
Porcelains
Luminous dials Smoke Detectors
Lantern Mantles
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Good Radiation vs. Bad Radiation
In the publics eye, there are two types of
radiation
Good radiation benefits humans any medicalexposure is goodradiation
Bad radiation is detrimental to humans anyindustrial/commercial exposure is badradiation; many even include natural exposure inthis category
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Radiation Exposure Normally receive
300 mrem per year
Same as 30 chest x-rays
Workers allowed upto 5000 mrem/year
Public exposuremust be less than500 mrem/year
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Measurement of Dose
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Stands for As Low As ReasonablyAchievable
Requirement for all facilities andpersonnel
ALARA can be achieved via
Training/knowledge
Protection methods
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Protection Against Radiation
Time Distance
Shielding
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Inverse square law
Source: 100 mrem/hr @1 foot
2 feet
25 mrem/hr 10 feet
1 mrem/hr
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100mrem/hr
1/2 Thickness
Shield
50 mrem/hr
SHIELD
One Half
Value Layer
MINIMIZE DOSE
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Low Alarm(Vehicle Present)
Vehicle just leaving
Exceeded an alarm threshold
Examples of alarm settings:
Low Alarm: 0.5uR/hr-50uR/hr
High Alarm: 50uR/hr-150uR/hr
Danger: All detectors above 150uR/hr
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Truck Detectors
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Conclusions Radiation
Can be detected
High level effects known
Low Level effects still debated
Annual Exposure
300 mrem/year
Varies widely
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