Radiation Safety for Radiation Workers by msb21215

VIEWS: 0 PAGES: 45

									 Principles
of Radiation




Industrial Studies 4020
Topics in Industrial Studies
Environmental Safety Management
 Review
• Atomic number                  Atomic mass
 Number of Protons ONLY        Number of Protons & Neutrons
                                 (weight)



    Atomic Mass
                          14               Chemical Symbol
                          12
                             C
   Atomic Number
 So, what is it ?

 3
Hydrogen – 3 contains one proton + two neutrons.
It’s a radioactive isotope of hydrogen also known
                    as tritium
                   Isotopes
• Same number of protons; different number of
  neutrons

• Same chemical properties

• Different nuclear properties

1                     2                       3
1H                    1
                          H                   1H
Hydrogen                                     * Tritium
                     Deuterium         1 Proton, 2 Neutrons
1 Proton         1 Proton, 1 Neutron
                                            * Note: Tritium is Radioactive
  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
   Radioactivity
                                   Man made
• Natural                            Phosphorus-32 (P-32)
  –   Uranium                        Sulfur-35 (S-35)
  –   Thorium                        Calcium-45 (Ca-45)
  –   Potassium-40                   Chromium-51 (Cr-51)
                                     Zinc-65 (Zn-65)
  –   Carbon-14 (C-14)
                                     Rubidium-86 (Rb-86)
  –   Hydrogen-3 (H-3) (tritium)     Iodine-125 (I-125)
       Background Radiation

            mrem/yr
Cosmic         27
Terrestrial    28
Inhaled        200
Internal       39
Man-made       63
     Total:    357
Radiation
Emission / propagation of     Microwave    light bulb
energy through space or       cell phone   UV lamp
material medium as waves or   radio / TV   laser
particles                     heat lamp     x-rays
Ionizing Radiation
Alpha Particles
2 Protons + 2 Neutrons

Short Range in Air

Not an External Hazard

Internal Hazard
Beta Particles
Negligible Mass

Long Range in Air

Internal/External Hazard

Charged
 Gamma Rays/Photons
Gamma photons & X-Ray both electromagnetic
      differ only by place of origin

No mass or charge

Highly-penetrating
          Neutrons
Very Long Range

Very Penetrating

Difficult to detect
Other modes of Decay
•Positron emission
•Electron capture
•Fission
•Electron
Activity
• Decay is a statistical process.
   – Cannot predict when a particular atom will decay.

   – Can predict when certain amount (%) will have decayed.
Units of Activity

Curie (Ci)
– 1 Ci = 37,000,000,000 dps (3.7 x 1010 dps) or
  1 Ci = 2.22 x 1012 dpm


Becquerel (Bq)
– 1 Bq = 1 dps
– 1 Ci = 37,000,000,000 Bq = 37 GBq (Giga Becquerel)
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
Decay Rate

Half-life,
  A= A0 e 0.693t/T½


 A = A0 (½)# of half-lives
Non-Ionizing Radiation
Questions?
Radiation
 Safety


Industrial Studies 4020
Topics in Industrial Studies
Environmental Safety Management
Radiation Hazards
• External Hazard (exposure from outside the body)
  – High-energy beta (i.e., energy > 300 keV or > 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 may
       pose only slight hazard
     • If stored in organ, slowly excreted (effective half-life)
  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)
Low Dose Biological Effects
ALARA
As Low As Reasonably Achievable

 Benefits outweigh risks?

Lower Dose =
Lower Risk
Monitoring Workers

• Whole body badge (TLD)

• Collar or Ring TLD

• Bioassay -- thyroid (iodine)

• urinalysis (tritium)
Occupational Exposure Limits
Accumulated Dose                 Not to Exceed
Equivalent to:             mrem/yr    rem/yr mSv/yr
Whole Body                 5,000         5     50

Lens of the Eye            15,000      15    150

Skin of Whole Body         50,000      50     500

Extremities of Whole       50,000      50     500
Body -- Hands, Feet, etc
General Safety Measures
• TIME                          • DISTANCE
 Exposure increases with time
                                    Exposure decreases
                                    with distance
                                v

• SHIELDING
 Plastic for beta
 Lead for gamma
Time vs Exposure
Increased exposure (risk)
  over time

Linear

3 mR/hr * 4 hr = ???
  Distance vs Exposure




      2
I1d1 = I2d2              2
  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
Detectors/ Monitors
Detectors/ Monitors
  1)   Capable of Detecting

  2)   Efficiency

  3)   Calibration
 Industrial Uses of Radiation




http://www.epa.gov/rpdweb00/source-reduction-management/applications.html
Industrial Uses of Radiation
Lasers
X-rays
Gauges
Wireless exit signs
X-ray Fluorescence
(XRF)
 Industrial Uses of Radiation

Moisture/density gauges
Radiography
Static control
Smoke detectors

http://www.epa.gov/rpdweb00/source-reduction-management/applications.html
Emergency Response

• Lifesaving and serious injury take precedence over
  radiation exposure and contamination

• Control Access to Area

• Call for Help
Radioactive
  Waste


 Industrial Studies 4020
 Topics in Industrial Studies
 Environmental Safety Management
    Types of Radioactive Waste
Spent Fuel - Withdrawn from a nuclear reactor
             following irradiation

High-level waste - Highly radioactive material from
                   reprocessing spent nuclear fuel

Transuranic - Man-made elements above
              atomic number 92
      Types of Radioactive Waste
NORM – Naturally-occurring radioactive material
       (primarily uranium & thorium

Special Nuclear - Pu, U-233, or uranium enriched in the
Material          isotopes U-233 or U-235

Low-level waste - not high-level radioactive waste,
                  spent nuclear fuel, transuranic waste,
                  or certain by-product material
  Solid Waste

• Landfill

• Decay

• Incinerate

• Supercompaction
LSC Vial Waste
•
Aqueous Waste
• Hold for decay

• Sanitary sewer
    Table II
    POTW
•
Mixed Waste
• RCRA/AEA – Dual regulation

• EPA/State Conditional exemption

• Department of
  Energy
Questions?

								
To top