Radiation Protection Refresher Course Module 1

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Radiation Protection Refresher CourseModule 1

• TRIUMF Radiation Protection Group

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Purpose and scope

• Review sources and hazards of ionizing radiation
  at TRIUMF
• Review of radiation activity and dose measurement
  units
• Review CNSC and TRIUMF dose limits NEW
  designation
• Review TRIUMF dose administration procedures
• Review methods for protection from external
  radiation
• Review Access Control measures and boot box
  technique
• Review methods for protection from internal
  radiation and contamination control
• Know how to operate radiation survey instruments
• Know how to dispose of radioactive waste
• Know what to do under the TRIUMF Emergency
  Response Plan in the event of a Radiation
  Emergency

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Ionizing radiation as a workplace hazard

• Ionizing radiation (IR) is one of several classes
  of hazards faced by TRIUMF workers. Others
  include
• - Mechanical (e.g. falling dropping objects
  on feet)
• - Electrical
• - Chemical
• - Noise
• - Ionizing radiation
• All types of hazards, including radiation, can be
  reduced by following appropriate safety
  procedures
• As with other hazards, the more you know about
  it, the better prepared you will be to work
  safely.

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Why ionizing radiation is a hazard
Ionizing radiation interacts with matter
Interaction results in energy loss
Energy loss in tissue results in a radiation
DOSE
Risk of long-term health effects increases with
increasing DOSE
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Types of radiation risk

• Acute risk Immediate harmful effects
• Acute risk from radiation is associated with
  large exposures received over a short period of
  time.
• Data suggest that there is a threshold dose below
  which acute effects are not present.
• Above the threshold value, the severity of the
  effects is proportional to the dose
• At TRIUMF the acute risk is very small, as
  exposures above the threshold are very unlikely.

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Types of radiation risk

• Chronic risk Harmful effects after prolonged
  exposure
• Chronic risk is always present since exposure to
  any radiation carries with it a slightly
  increased risk of cancer at a later date.
• Although it cannot be predicted who will develop
  cancer, it can be reasonably expected that the
  risk of developing cancer increases with the
  received dose.
• No threshold effect is observed.

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Long Term Somatic Effects
Risk of inducing cancer for working population is
4/Sv
Risk of fatal cancer in general population20
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A working population of 1000 is exposed to 100
mSv over a lifetime.
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Loss of life expectancy
Risks associated with radiation are much less
than risks which arise from other sources
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Sources of ionizing radiation at TRIUMF

• Activation
• The process by which energetic particles convert
  stable nuclides into radioactive ones.
• Types of Radiation
• Prompt Radiation
• Residual Radiation
• Sources of Residual Radiation
• Cyclotron systems which are activated
• Other Sources of Radiation
• Radiochemistry labs calibration sources Radio
  Frequency (RF) accelerator components (no beam
  necessary)

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Ionizing radiation hazards at TRIUMF

• ? (gamma) radiation X-rays
• What electromagnetic radiation from nuclear
  decays and interactions (?) decelerating
  electrons and atomic electron transitions
  (X-rays)
• Where
• Activated cyclotron/beamline components and
  shielding
• Accelerator Radio Frequency (RF) components
• Radiochemistry labs Calibration sources
• Properties
• Massless wide range of energies, depending on
  source
• Cannot be stopped completely, only attenuated
• Hazards
• External penetrating ? contributes to whole-body
  dose
• Internal Not a serious hazard most ?s leave
  the body before interacting
• Prompt hazard prompt ?s from (n, ? ) reactions
  in shielding penetrate shielding

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Ionizing radiation hazards at TRIUMF

• ß- (beta minus) radiation
• What electrons from nuclear decays
• Properties
• Light, low-energy, charged particles
• Not much penetrating power can be stopped
  completely by 1-2 cm of lucite or similar
  material
• Where
• Activated cyclotron/beamline components and
  shielding
• Radiochemistry labs
• Calibration sources
• Hazards
• External low penetrating power?contributes to
  skin dose only
• Internal significant internal hazard
• No prompt hazard, as ß- cannot penetrate
  shielding

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Ionizing radiation hazards at TRIUMF

• ß (beta plus) radiation
• What anti-electrons (positrons) from nuclear
  decays
• Where
• Activated cyclotron/beamline components and
  shielding
• Radiochemistry labs
• Air in cyclotron vault, beamline tunnels, and
  nearby areas
• Calibration sources
• Properties
• Light, low-energy, charged particles
• Like ß-, not much penetrating power interacting
  with electrons in matter, positrons will all
  eventually annihilate into ?s
• Hazards
• External skin dose as per ß-, with the addition
  whole-body ? dose
• Internal pre-annihilation significant internal
  hazard most ?s leave the body before
  interacting
• No prompt hazard, as ß cannot penetrate
  shielding

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Ionizing radiation hazards at TRIUMF

• n (neutron) radiation
• What neutral nuclear components
• Where
• Around cyclotrons, beamlines, production targets
  (Beam ON only!)
• Properties
• Heavy, neutral particles wide range of energies
• Interact with matter via nuclear scattering
• Hazards
• External penetrating ? contributes to whole-body
  dose
• Internal Not an internal hazard
• Prompt hazard Some fraction of prompt ns
  penetrate shielding

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Ionizing radiation hazards at TRIUMF

• a (alpha) radiation
• What helium nuclei (2 neutrons2 protons) from
  nuclear decays
• Properties
• Heavy, low-energy, charged particles
• Not much penetrating power can be stopped
  completely by a sheet of paper
• Where
• Not currently produced at TRIUMF, but there are
  plans to produce them at ISAC in the near future
• Calibration sources
• Hazards
• External very low penetrating power?not an
  external hazard
• Internal significant internal hazard

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Summary of radiation penetrating power

• Rules of thumb
• 1 cm of lead will attenuate ?s by a factor of 2
• 1 m of concrete will attenuate ns by a factor of
  10

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Summary of ionizing radiation hazards
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The person most responsible for your safety while
working at TRIUMF is
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Match each entry from column two with the best
description of it in column one.
Column 1
Column 2
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What is the most important property of ionizing
radiation with respect to its biological effects?
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Ionization means
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Which of the following types of hazards exist for
TRIUMF workers?(Select all of the correct
answers)
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"Chronic risk" means risk of
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The risk of a fatal cancer induced by
occupational exposure to ionizing radiation is
estimated to be 4/Sv . What is the probability
that someone with a lifetime exposure of 50 mSv
will develop a radiation-induced fatal cancer?
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"Activation" means
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25
An appropriate shielding for beta radiation is
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Which of the following radiation hazards is a
prompt hazard only?
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Which of the following types of radiation is not
currently produced at TRIUMF?
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Radiation Protection Refresher Course Exam
Question Feedback/Review Information Will Appear
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End of module 1 of the online refresher course

• You are now at the end of module 1 of the online
  portion of the refresher training.
• There are 2 more online modules to be
  completed
• followed by a short practical session.