Ionizing Radiation
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Ionizing radiation consists of
subatomic particles or electromagnetic
waves that are energetic enough to
detach electrons from atoms or
molecules, ionizing them.
Ionizing Radiation
Alpha Particles: consist of two protons
and two neutrons bound together into a
particle
 Beta Particles: Beta particles are highenergy, high-speed electrons or positrons
emitted by certain types of radioactive
nuclei
 Gamma Rays: Gamma rays are short
wavelength electromagnetic radiation, not
particles.
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Ionizing Radiation
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Shielding
◦ Alpha Particles: Sheet of paper
◦ Beta Particles: Plastic shields
◦ Gamma Rays: Lead of a certain thickness
Ionizing Radiation

There are four standard ways to limit exposure:
◦ Time: Limiting or minimizing the exposure time will reduce
the dose from the radiation source.
◦ Distance: Radiation intensity decreases sharply with
distance, according to an inverse square law.
◦ Shielding: Barriers of lead, concrete, or water give effective
protection from radiation formed of energetic particles
such as gamma rays and neutrons. The effectiveness of a
material in shielding radiation is determined by its halve
value thicknesses, the thickness of material that reduces
the radiation by half.
◦ Containment: Radioactive materials are confined in the
smallest possible space and kept out of the environment.
Inverse Square Law
Where:
I1 = Intensity 1 at D1
I2 = Intensity 2 at D2
D1 = Distance 1 from source
D2 = Distance 2 from source
Inverse Square Law Example

The radiation exposure to a person was
measured at 5 mR/hour of gamma
radiation when the source was located a
distance of one foot away. Increasing the
distance to two feet would result in an
exposure of how many mR/hour?
Non-ionizing Radiation

Extremely Low Frequency Radiation (ELF)
◦
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Extremely Low Frequency (ELF) radiation at 60 HZ is produced by power lines, electrical wiring,
and electrical equipment.
Radiofrequency and Microwave Radiation
Microwave radiation (MW)
◦
Radiofrequency and Microwave Radiation
Microwave radiation (MW) is absorbed near the skin, while Radiofrequency (RF) radiation may be
absorbed throughout the body.
◦
Sources of RF and MW radiation include radio emitters and cell phones.
Infrared Radiation (IR)
◦
The skin and eyes absorb infrared radiation (IR) as heat.
◦
Sources of IR radiation include furnaces, heat lamps, and IR lasers.
Visible Light Radiation
◦
The different visible frequencies of the electromagnetic (EM) spectrum are "seen" by our eyes as
different colors.
◦
Excessive visible radiation can damage the eyes and skin.
Ultraviolet Radiation (UV)
◦
Ultraviolet radiation (UV) has a high photon energy range and is particularly hazardous because
there are usually no immediate symptoms of excessive exposure.
◦
Lasers typically emit optical (UV, visible light, IR) radiations and are primarily an eye and skin hazard.
Applicable OSHA Standards
General Duty Clause 5(a)(1)
 Ionizing radiation falls under a variety of OSHA standards
including:

◦ 1910.1096 , Ionizing radiation (general industry).
◦ 1926.53 , Ionizing radiation (construction).
◦ 1915.57 , Uses of fissionable material in ship repairing and
shipbuilding. Ionizing radiation requirements for ship repairing
and shipbuilding activities.
◦ 1910.120 , Hazardous waste operations and emergency
response. This HAZWOPER standard contains requirements
relating to ionizing radiation at hazardous waste sites.
◦ 1926.65 , Hazardous waste operations and emergency
response. This HAZWOPER standard for the construction
industry; also contains requirements relating to ionizing
radiation at hazardous waste sites.
OSHA Directives

Memorandum of Understanding Between
the OSHA and the U.S. Nuclear Regulatory
Commission. CPL 02-00-086 [CPL 2.86],
(1989, December 22).
◦ Delineates the authorities, responsibilities, and
other activities between OSHA and NRC for
occupational health and safety at radiation sites.

OSHA Coverage of Ionizing Radiation
Sources Not Covered by Atomic Energy Act
of 1954.
◦ STD 01-04-001 [STD 1-4.1], (1978, October 30).
OSHA Standards Cover
Exposure limits
 Employee Monitoring
 Warning signals
 Signage
 Material storage
 Incident notification/reporting
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