Ionizing and NonIonizing Radiation Awareness CHEM 605 Fall 2006

1
Ionizing and Non-Ionizing Radiation
AwarenessCHEM 605Fall 2006

• Mary J. Handy
• Health Physicist, Laser Safety Officer
• Dept. of Radiological and Environmental Management

2
Definitions

• Radioactivity
• Spontaneous emission of particles and/or
  electromagnetic radiation from an unstable
  nucleus.
• Ionizing Radiation
• Radiation of sufficient energy to strip electrons
  from the orbit of an atom.
• Non-Ionizing Radiation
• Radiation without sufficient energy to strip
  electrons from the orbit of an atom (unlike
  ionizing radiation), yet enough energy to excite
  orbital electrons.
• Contamination
• Radioactive material in an unwanted location.
• Half-Life
• The time required for any given radioisotope to
  decrease to one-half its original quantity
• After 10 half-lives, the radioactivity is 99.9
  gone

3
Ionizing Radiation Examples

• There are 4 main types of radioactive emissions,
  each of which has different shielding
  requirements
• Alpha
• Shielded by air, skin, paper
• Beta
• Shielded by skin, aluminum, wood, Plexiglas
• Gamma/x-rays
• Shielded by lead
• Neutrons
• Shielded by hydrogen-containing materials, water,
  paraffin

4
Non-Ionizing Radiation Examples

• Laser
• Magnet
• MRIs (magnetic resonance imaging) formally
  known as NMRs (nuclear magnetic resonance)
• Cathode ray tubes
• Charged particle beams
• Mass spectrometers
• Solenoid valves
• Magnetic levitation trains
• Radiofrequency
• Cell phones
• Antennas
• Microwave ovens
• Power stations

5
Exposure

• There are two ways that an individual can be
  exposed to radiation
• Internal exposure (ionizing only)
• By mouth, nose, eyes, skin absorption, or any
  open cut
• Main concern with alpha and low energy beta
• External exposure
• Energy is passed through the body and/or absorbed
  by tissues
• Main concern with high energy beta, gamma, and
  neutron radiation

6
Rules to Reduce Radiation Exposure

• Time
• Reduce time in areas of radiation exposure.
• Distance
• Keep your distance from sources of radiation
  exposure- exposure drops very quickly.
• Shielding
• Use proper shielding to reduce exposure if
  shielding is necessary.
• Contamination Control (ionizing only)
• PPE
• Surveys

7
Background Ionizing Radiation

• Average Annual Background Radiation Exposure in
  the US is approximately 360 mrem

8
Biological Effects - Ionizing

• Effects depend on dose
• Can range from no effect (low dose) to death
  (high dose) with acute doses
• Damage to DNA considered most significant
• Single strand break- repaired easily
• Double strand break- rare but not repaired easily
• DNA strands break thousands of times an hour
  under normal situations and the body repairs it.
  Increased risk of cancer with radiation can occur
  when there is an increase of occurrence causing a
  higher probability that strands do not get fixed
• This is only one of several steps required to
  induce tumors

9
Biological Effects - Ionizing

• Acute (one-time) high level dose
• Can cause radiation damage and symptoms quickly
• Not likely with any sources on campus
• Chronic (long-term) low level dose
• Effects, if any, appear after 20-30 years
• Risk of cancer with 1 rem of radiation increases
  from the normal rate of 20 to 20.03.

10
Ionizing Radiation Regulations

• Radioactive material users must be licensed by
  the Nuclear Regulatory Commission or state agency
• Radiation Safety Officer (RSO) makes procedures
  manual which must be followed because it is
  enforceable by law
• Must assure compliance with the Nuclear
  Regulatory Commission, Department of
  Transportation, Indiana State Department of
  Health, and Indiana Department of Environmental
  Management Regulations.

11
Exposure Limits Ionizing Radiation

• Radiation workers can receive a whole body dose
  of 5000 mrem/yr
• Pregnant radiation workers can receive 500 mrem/9
  month gestation period
• Minors are limited to 10 of adult doses
• Public is limited to 100 mrem/year
• Average dose the public receives is 360 mrem/yr
• Average dental x-ray- 10 mrem
• Head/neck x-ray- 20 mrem
• Cross-country airline flight- 5 mrem

12
Radiation Safety Guidelines

• Warn everyone about presence of radionuclides
• Label all radioactive materials
• Lock up radionuclides
• Wear PPE
• Conduct surveys (radiation detectors, wipe tests)
• Keep records/inventory of radioactive materials
  (RAM)
• Contact RSO before moving any materials to a
  different location

13
Radiation Safety Guidelines

• Make sure special equipment is ordered ahead of
  time
• Develop a contingency plan in case of accident
• Be sure to have proper personnel dosimetry (film
  badges, finger badges), if applicable
• Proper monitoring equipment in working condition
• Proper shielding design (consult RSO)
• Make sure Principal Investigator is approved for
  specific nuclide and quantity

14
Geiger- Mueller Counters

• For contamination and exposure determination
• Good audible response
• Can saturate at high count rates - use audio
• Cannot detect low energy betas very efficiently
  (S-35, C-14, H-3)

15
Security-NRC Main Area of Emphasis

• Secure laboratories when unoccupied
• Secure RAM if laboratory security is not feasible
• Challenge visitors or unauthorized individuals
• Account for RAM through inventory records

16
LASER

• Light Amplification by Stimulated Emission of
  Radiation

Optical Cavity
Lasing Medium
Emitted Wavelength
Partially Reflecting Mirror
Fully Reflecting Mirror
Pumping System
17
Laser Hazard Classification Scheme

• Class 1 normally cannot produce a hazard.
• Class 2 may present some potential for hazard if
  viewed directly for extended periods of time.
• Class 3a normally would not produce a hazard if
  viewed for only momentary periods with the
  unaided eye.
• Class 3b can produce a hazard if viewed
  directly or specular (i.e. mirror-like)
  reflection.
• Class 4 can produce a hazard not only from
  direct or specular reflections, but also from a
  diffuse reflection. In addition, such lasers may
  produce fire hazards and skin hazards.
• Class 3b and 4 lasers are required to register
  with laser safety program.

18
Can I be in a room with a Class IIIb or IV laser
if I havent had Laser Safety Training?

• Yes, as long as
• The laser is not in operation, OR
• The laser system is totally enclosed (where the
  Nominal Hazard Zone (NHZ) is the laser system, OR
• The laser system is surrounded by barriers (which
  would be the NHZ) and you are on the outside of
  the NHZ, OR
• You are authorized to be in the NHZ, are wearing
  the appropriate laser safety equipment, AND are
  NOT operating the laser.

19
Biological Effects Non-ionizing Laser Beam
Hazards

• Eye Damage
• Thermal
• Photochemical
• Photoacoustic
• Skin Damage
• range from mild reddening (erythema) to
  blistering
• depend upon exposure dose rate, exposure dose,
  and conduction of heat away from the site of
  absorption
• possible carcinogenic effects

20
Biological Effects Non-ionizing Laser
Non-Beam Hazards

• Inhalation hazards
• Cryogenic Effects
• Toxic/Carcinogenic Effects
• Possible hearing loss
• Ionizing Radiation Exposure
• Lacerations
• Electrocution
• Burns

21
Postings - Laser
22
Biological Effects Non-ionizing Radiofrequency

• Heating of the body
• Cataracts
• Developing fetus is at no greater risk than
  mother
• Two areas of the body, the eyes and the testes,
  are particularly vulnerable to RF heating because
  of the relative lack of available blood flow to
  dissipate the excessive heat load.
• Cancer? Conflicting studies.

23
Postings RF/EME
24
Biological Effects Non-Ionizing Magnets

• Could effect electromagnetic devices (e.g.
  cardiac pacemakers)
• Attracts ferrous objects, both inside and outside
  body (i.e. flying metal objects!)
• Occurring at 2 T or greater (static magnets)
• Nauseousness, vertigo, magnetophosphenes (i.e.
  flickering light in eyes)
• Induction of electrical potential within blood

25
Postings - Magnet
26
Emergency Procedures Injury

• Assist injured personnel first, call 911 if
  serious injury (Medical problems take priority
  over radiological concerns).
• Monitor personnel, check for contamination.
• Control area - inform other workers and keep
  people out of the area.
• Notify radiation safety office at REM- 46371.

27
Emergency Procedures Fire

• Sound fire alarm.
• Contact fire department. Inform them of the
  incident.
• Turn power off to system if using x-ray or other
  radiation-producing device, if possible.
• Evacuate area or use fire extinguisher.
• Contact REM (49-46371).

28
REM Contact List

• REM Main Number- 46371
• Jim Schweitzer- 42350
• Radiation Safety Officer and Director, REM
• Mary Handy- 42721
• Laser Safety Officer / Health Physicist
• Mark Pflug- 42693
• Health Physicist
• Deb Smith- 40205
• Health Physicist