Berkeley Lab Generic Presentation

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Radiation Protection Fundamentals
Craig Maxwell - RCT Radiation Protection
Group Lawrence Berkeley National Laboratory
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Objectives

• Familiarize you with some of the basics of
  Radiation and Radioactive Decay
• Discuss some of the common instruments found in
  research labs
• Review control methods used to reduce exposure

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Structure of the Atom
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• Ionizing radiation
• High energy radiation
• Gamma-rays, x-rays - photons
• Particles alpha, beta, neutron
• Ejects electrons from atoms
• Produces an altered atom - an ion
• Non-ionizing radiation
• Low energy
• Lasers, RF, microwaves, IR, visible
• Excites electrons
• Produces heat

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Alpha Decay
4He Nucleus Ejected from Nucleus
internal hazard
stopped by paper
found in soil, radon and other radioactive
materials
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Beta Decay
Either too many neutrons or too many protons
skin, eye and internal hazard
stopped by plastic
Naturally occurring in food, air and water
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Gamma / X-ray Decay

• Emission of a photon
• Often occurs after ? or ? when nucleus is in an
  excited state

stopped by lead
naturally present in soil and cosmic radiation
medical uses
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Types of Ionizing Radiation
Paper
Plastic
Lead
Concrete
Alpha
Helium nucleus (2 protons, 2 neutrons) 2 charge
Beta
Electron 1 or -1 charge
Gamma and X-rays
Photon 0 charge
Neutron
Neutron 0 charge
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Radiation Quantities and Units
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Radiation Weighting Factors (WR)
Absorbed dose (Rad/Gy) x WR Equivalent dose
(rem)
Photons, electrons muons (all energies) 1
Beta positron 1
Neutrons 5-20
Alpha, fission fragments, heavy nuclei 20
10CFR835
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Sources of Ionizing Radiation

• Radioactive materials
• Naturally occurring (uranium, carbon-14, )
• Artificial (activated by neutrons from a reactor
  or accelerator beam)
• Radiation Producing Machines
• X-ray machines (characteristic, bremstrahlung)
• Accelerators (ion beams, neutrons, x-rays)

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Background and Manufactured Radiation In the
U.S. Contributes 360 mrem per year
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Manufactured Sources of Radiation
Cigarette Smoking - 1300 mrem
Medical 53 mrem

Medical Doses A Dental exam (16 mrem) B
Mammogram (25 mrem) C Tc-99m cardiac function
(75 mrem) D Cranial CT multiple scans (up to 5
rem) E Full body CT screening one scan ( 1
to 2 rem) F Spiral whole body CT scan ( 3 to 10
rem)

Building Materials - 3.6 mrem
Smoke Detectors - 0.0001
mrem
mrem
Fallout lt 1
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Whole Body Annual Dose Limits
RADIATION WORKER - Federal NRC Limits Whole
Body - 5000 mrem/year Extremities - 50,000
mrem/year Skin - 50,000 mrem/year Eyes - 15000
mrem/year Pregnant - 500 mrem/term / 50
mrem/month General Pubic - 100 mrem/year
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Effect of Dose and Dose Rate
5 min
100 rems
Localized effects gt500 REM Skin radiation
burn
20 years
Whole body effects LD50/30 500 RAD
Chronic exposures may increase cancer risk.
100,000 people exposed to 100 mREM 4 or 5
additional cancers
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Risk Perspective

• Average Estimated Days Lost Due to Daily
  Activities
• Health Risk Ave. Est. Days Lost
• Unmarried Male 3,500
• Cigarette Smoking 2,250
• Unmarried Female 1,600
• Coal Miner 1,100
• 25 Overweight 777
• Alcohol (U.S. average) 365
• Construction Worker 227
• Driving a Motor Vehicle 207
• 100 mrem/year for 70 years 10

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• Radiation
• vs
• Contamination

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Radiation Vs. Radioactive Contamination
Radiation is particles or waves of energy emitted
from unstable atoms. Radioactive
Contamination is radioactive material usually in
any location you do not want it. Exposing a
material to radiation does not necessarily make
it radioactive, but radioactive material on a
non-radioactive item, makes the item contaminated.
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Radiation Survey Meters

• Two common Ion Chamber radiation survey
  instruments are

Victoreen
Bicron
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Beta Contamination Instrument

• Ludlum 3

Type Normally equipped with a Geiger-Mueller
44-9 (pancake) probe Detects Beta, gamma
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Alpha/Beta Contamination Instrument

• Ludlum 2224

Type Plastic scintillation for beta detection
that has a ZnS (Ag) coating for alpha
detection Detects Alpha and Beta
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Other Instrumentation

Ludlum 16 with a 44-3 thin window NaI probe
Liquid Scintillation (LSC)
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Instrument performance

• Dead or low batteries - erratic or no detection
• Calibration has changed - may read high or low
• Defective cable or other problems
• Poor survey technique
• angle of probe to source - only detects part
• to far from source - radiation absorbed by air
• survey too fast only detects part
• You must use them correctly if you expect them to
  work for you

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Radiation Contamination

• Control Methods
• Used to reduce exposure to
• radiation and
• radioactive material contamination

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Engineering Controls

• Containment
• Glove box
• Glove bag

• Ventilation
• Fume Hood
• Bio Safety Cabinet

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Engineering Controls cont.

• Interlocks
• Tamper-Proof Screws/Bolts
• Flange Padlocks
• Security Seals
• Shielding
• Access controls (e.g. card key)

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Administrative Controls

• Regulations
• Formal Authorizations
• Facility policies and procedures
• Labels, signs, and postings
• Routine radiation surveys
• Machine operational restrictions

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ALARA As Low As Reasonably Achievable

• ALARA Techniques
• Time - (Reduce)
• Distance (Increase)
• Shielding (Proper Shielding)

Reduce Radiation Doses
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Control Methods

• Engineering
• Administrative
• ALARA Techniques
• Time
• Distance
• Shielding
• Missing Control

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Exposure Prevention Methods

• Protective clothing such as lab coats, gloves
  safety glasses
• Self-monitoring to reduce the spread of
  radioactive contamination

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Good Work Practices
Use deliberate movements and apply lessons
learned from cold runs (mock-ups).
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Respect and Understand the Postings
Treat all radiological areas as if everything was
contaminated.
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Common sources of radioactive contamination

• Sloppy work practices
• Poor housekeeping
• Opening radioactive materials/systems without
  proper controls
• Leak or tears in containers
• Damaged Sealed Sources
• Spills

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Upon Completion of Work
Be sure to survey yourself
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Upon Completion of Work
Hand washing is a good work practice and an
important final step after working with any
radioactive material.
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Final Thoughts

• It is our mission to ensure that research and
  learning continue in the safest manner possible.
• Be a mentor
• Be a resource
• Lead by example
• Always use best practices