Radiation Safety for Radiation Workers

1
Principles of Radiation
Industrial Studies 4020 Topics in Industrial
Studies Environmental Safety Management
2
Review

• Atomic number Atomic
  massNumber of Protons ONLY Number of
  Protons Neutrons
  (weight)

Atomic Mass
14
C
Chemical Symbol
12
Atomic Number
3
So, what is it ?
3
H
Hydrogen 3 contains one proton two neutrons.
Its a radioactive isotope of hydrogen also known
as tritium
4
Isotopes

• Same number of protons different number of
  neutrons
• Same chemical properties
• Different nuclear properties

1
2
3
H
H
H
1
1
1
Hydrogen 1 Proton
Tritium 1 Proton, 2 Neutrons
Deuterium 1 Proton, 1 Neutron
Note Tritium is Radioactive
5
Radioactivity

• Atoms with too many neutrons or protons are
  unstable and emit energy to become more stable.
• Energy is carried away by a- / b-particle or x-
  / g-ray.
• These atoms are called radioactive and the
  process is called radioactive decay

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Radioactivity
Man made Phosphorus-32 (P-32) Sulfur-35
(S-35) Calcium-45 (Ca-45) Chromium-51
(Cr-51) Zinc-65 (Zn-65) Rubidium-86
(Rb-86) Iodine-125 (I-125)

• Natural
• Uranium
• Thorium
• Potassium-40
• Carbon-14 (C-14)
• Hydrogen-3 (H-3) (tritium)

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Background Radiation
mrem/yr Cosmic 27 Terrestrial 28 Inhaled
200 Internal 39 Man-made 63 Total 357
8
Radiation

• Microwave light bulb
• cell phone UV lamp
• radio / TV laser
• heat lamp x-rays

Emission / propagation of energy through space or
material medium as waves or particles
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Ionizing Radiation
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Alpha Particles
2 Protons 2 NeutronsShort Range in AirNot
an External Hazard Internal Hazard
11
Beta Particles
Negligible MassLong Range in AirInternal/Exter
nal Hazard Charged
12
Gamma Rays/Photons
Gamma photons X-Ray both electromagnetic
differ only by place of origin No mass or
chargeHighly-penetrating
13
Neutrons
Very Long RangeVery PenetratingDifficult to
detect
14
Other modes of Decay

• Positron emission
• Electron capture
• Fission
• Electron

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Activity

• Decay is a statistical process.
• Cannot predict when a particular atom will
  decay.
• Can predict when certain amount () will have
  decayed.

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Units of Activity

• Curie (Ci)
• 1 Ci 37,000,000,000 dps (3.7 x 1010 dps) or1
  Ci 2.22 x 1012 dpm
• Becquerel (Bq)
• 1 Bq 1 dps
• 1 Ci 37,000,000,000 Bq 37 GBq (Giga
  Becquerel)

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Quantities Units

• Beta and gamma radiation about equally damaging
• 1 R 1 rad 1 rem
• Alpha radiation causes greater cellular damage
• 1 rad of a 20 rem

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Decay Rate

• Half-life, A A0 e 0.693t/T½A A0 (½) of
  half-lives

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Non-Ionizing Radiation
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Questions?
21
RadiationSafety
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22
Radiation Hazards

• External Hazard (exposure from outside the body)
• High-energy beta (i.e., energy gt 300 keV or gt 0.3
  MeV)
• Gamma and X-rays
• Neutrons
• Internal Hazard
• Radioactive material enters body by
  eating/drinking in radiation area, by breathing
  vapors/aerosols, or skin absorption
• In body, it is treated like non-radioactive
  elements
• If not incorporated into organ, rapidly excreted
  and maypose only slight hazard
• If stored in organ, slowly excreted (effective
  half-life)

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Acute Biological Effects

• Whole body, external acute exposure effects
• 25 rad some chromosome aberrations
• 50 rad minor blood changes
• 100 rad 2 radiation sickness
• 400 rad 50 die in 60 days (LD50/60)
• 700 rad lethal single exposure
• 6000 rad cancer therapy (local)

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Low Dose Biological Effects
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ALARAAs Low As Reasonably Achievable

• Benefits outweigh risks? Lower Dose
  Lower Risk

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Monitoring Workers

• Whole body badge (TLD)
• Collar or Ring TLD
• Bioassay -- thyroid (iodine)
• urinalysis (tritium)

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Occupational Exposure Limits
Not to Exceed mrem/yr rem/yr mSv/yr 5,000
5 50 15,000 15
150 50,000 50 500 50,000 50
500
Accumulated Dose Equivalent to Whole Body Lens
of the Eye Skin of Whole Body Extremities of
Whole Body -- Hands, Feet, etc
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General Safety Measures

• TIME
• Exposure increases with time
• SHIELDING
• Plastic for beta
• Lead for gamma

• DISTANCE
• Exposure decreases with distance
• v

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Time vs Exposure

• Increased exposure (risk)over time
• Linear
• 3 mR/hr 4 hr ???

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Distance vs Exposure

• I1d12 I2d22

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Exposure Shielding
No shielding needed for alpha or low-energy beta

• Thick, dense (i.e., lead) for gamma / x-rays
• Plastic beta
• Hydrogeneous (or boron cadmium) for neutrons

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Detectors/ Monitors
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Detectors/ Monitors
1) Capable of Detecting 2) Efficiency3) Calibr
ation
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Industrial Uses of Radiation

• http//www.epa.gov/rpdweb00/source-reduction-manag
  ement/applications.html

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Industrial Uses of Radiation
Lasers X-raysGauges Wireless exit signs
X-ray Fluorescence(XRF)
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Industrial Uses of Radiation
Moisture/density gauges Radiography Static
controlSmoke detectors

• http//www.epa.gov/rpdweb00/source-reduction-manag
  ement/applications.html

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Emergency Response

• Lifesaving and serious injury take precedence
  over radiation exposure and contamination
• Control Access to Area
• Call for Help

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RadioactiveWaste
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39
Types of Radioactive Waste
Spent Fuel - Withdrawn from a nuclear reactor
following
irradiationHigh-level waste - Highly
radioactive material from
reprocessing spent nuclear
fuel Transuranic - Man-made elements above
atomic number 92
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Types of Radioactive Waste
NORM Naturally-occurring radioactive
material (primarily uranium
thoriumSpecial Nuclear - Pu, U-233, or uranium
enriched in the Material
isotopes U-233 or U-235Low-level waste - not
high-level radioactive waste,
spent nuclear fuel, transuranic
waste, or
certain by-product material
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Solid Waste

• Landfill
• Decay
• Incinerate
• Supercompaction

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LSC Vial Waste

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Aqueous Waste

• Hold for decay
• Sanitary sewer Table II POTW

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Mixed Waste

• RCRA/AEA Dual regulation
• EPA/State Conditional exemption
• Department ofEnergy

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Questions?