Dalhousie University Radiation Safety Office

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Dalhousie UniversityRadiation Safety Office

• Refresher Training
• 2007

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Principal Investigator Responsibilities

• It is the responsibility of the P.I. to ensure
  that all workers in their research group who will
  be handling nuclear substances are registered
  with the Radiation Safety Office and have
  completed required radiation safety training.
• Workers within the research group who carry out
  their duties in a registered radiation lab must
  receive instruction relating to the radiation
  hazards even if they will not be handling nuclear
  substances themselves.

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Canadian Regulations

• The Canadian Nuclear Safety Commission (CNSC)
  regulates the use of nuclear energy and materials
  to protect health, safety and the environment and
  to respect Canadas international commitments on
  the peaceful use of nuclear energy.
• http//www.cnsc-ccsn.gc.ca

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Dalhousie UniversityRadiation Safety Program
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Radiation Safety Committee

• Dr. Stan Cameron Chemistry
• Dr. A. Chatt SLOWPOKE
• Dr. R. Dunlap Physics
• Prof. K. Hall - Physics
• Dr. K. Hewitt Physics
• Dr. D. Hoskin (Chair) Pathology
• P. Jones (Secretary) RSO
• Dr. W. Louch EHS
• Ms. K. Murphy Pharmacology
• Dr. N. Ridgway ARC
• Dr. M. Zentilli Earth Sciences

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Instructions

• Refresher training is intended for those
  nuclear substance workers who have previously
  attended the Radiation Safety Training course
  prior to May 2005. The refresher training module
  is not intended to substitute for the full day
  training session required of all new or
  previously untrained workers. Refresher training
  must be documented by submitting the required
  form and quiz found in the Forms section of the
  EHS web site at http//www.dal.ca/safety

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An Overview of Bill C-45

• The Government of Canada, through the
  Department of Justice, should institute a study
  of the accountability of corporate executives and
  directors for the wrongful or negligent acts of
  the corporation and should introduce in the
  Parliament of Canada such amendments to
  legislation as are necessary to ensure that
  corporate executives and directors are held
  properly accountable for workplace safety.
• Report of the Westray Mine Public Inquiry,
  Recommentation 73

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New Legal Duty to Prevent Harm

• New section 217.1 of the Criminal Code creates a
  legal duty not only in relation to work but to
  all tasks
• Everyone who undertakes, or has the authority,
  to direct how another person does work or
  performs a task is under a legal duty to take
  reasonable steps to prevent bodily harm to that
  person, or any other person, arising from that
  work or task.

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Application of Legal Duty

• Applies to all activities of an organization, not
  just employment-related tasks
• Duty is imposed upon individuals who have control
  and direction over others (or authority to do so)
  in the performance of a task
• Duty is owed to people performing the task and
  those who may be affected by the task (i.e. the
  public)

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Consequences for individuals

• Personally exposed to charge of criminal
  negligence causing death or bodily harm where
• Contravene the new duty in failing to take
  reasonable steps to prevent bodily harm
• Demonstrate a wanton or reckless disregard for
  the lives or safety of others
• Penalty on Conviction
• 10 years in prison in the case of injury
• Life imprisonment in the event of death

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Conducting Contamination SurveysContamination
Criteria

• Nuclear Substances are assigned classifications
  as follows
• Class A - typically long-lived and emit alpha
  radiation
• Class B - typically long lived and emit beta or
  gamma radiation
• Class C - typically short-lived and emit beta
  and gamma radiation

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CNSC Contamination Criteria

• The licensee shall ensure that for nuclear
  substances listed .
• non-fixed contamination in all areas, rooms or
  enclosures where unsealed nuclear substances are
  used or stored does not exceed
• i) 3 Bq per square centimetre for all Class A
  radionuclides
• ii) 30 Bq per square centimetre for all Class B
  radionuclides or
• iii) 300 Bq per square centimetre for all Class
  C radionuclides
• Averaged over an area not exceeding 100 square
  centimetres and

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CNSC Contamination Criteria contd

• non-fixed contamination in all other areas does
  not exceed
• i) 0.3 Bq per square centimetre for all Class A
  radionuclides
• ii) 3 Bq per square centimetre for all Class B
  radionuclides
• iii) 30 Bq per square centimetre for all Class
  C radionuclides
• Averaged over an area not exceeding 100 square
  centimetres
• In keeping with our ALARA policy contamination
  limits are set at regulatory limits, however,
  every effort should be made to maintain
  contamination levels below the 2-3 times
  background rule of thumb.

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Contamination Criteria typically 32P will be
the only nuclear substance for which you may not
be required to do a wipe test survey.
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Dalhousie Monitoring Requirements

• Item 15 16 of the Laboratory Poster
• 15. Monitor laboratory for loose contamination at
  least weekly.
• 16. Maintain records of non-use periods.

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Conducting Contamination SurveysContamination
Criteria as defined in Dalhousies ALARA policy
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Conducting Contamination SurveysContamination
Criteria as defined in Dalhousies ALARA policy

• At Dalhousie typically Class B C nuclear
  substances are used. In keeping with our ALARA
  policy contamination limits are set at regulatory
  limits, however, every effort should be made to
  maintain contamination levels below the 2-3 times
  background rule of thumb.

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Types of Contamination Surveys

• Direct Survey
• A direct survey measures both fixed and loose
  contamination on a surface. The survey is
  conducted using a portable survey meter.

• Indirect Survey (wipe test)
• An indirect survey measures only removable or
  loose contamination on a surface. The survey is
  conducted by wiping the surface with a suitable
  absorbent material and then counting the wipe
  with an appropriate counter.

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Selection of Contamination Monitoring Instruments

• Hand-held Instrument
• Thin window GM detector 1
• Ion chamber with ? window 2
• Gas filled proportional 3
• Thin layer NaI detector 4
• Thin crystal NaI detector 5
• Sandwich NaI detector 6
• Zinc sulphide detector 7

• Others
• Gas flow proportional A
• LS counter B
• Well crystal NaI counter C
• Semiconductor ? spectrometer D

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Selection of Contamination Monitoring Instruments

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Direct Survey

• The direct survey involves the use of a
  portable radiation detection instrument. This
  method can detect both fixed and removable
  (loose) contamination on a surface if the energy
  of the nuclear substance is in the range of
  detection for the instrument used, however, it
  cannot distinguish between the two. Direct
  surveys may be used when background radiation
  levels are negligible compared to licence
  criteria. This method allows the operator to
  easily survey both large and irregular surfaces.
  The main advantage of this method is that the
  operator will get an immediate result. The direct
  survey is a valuable tool for monitoring work
  surfaces at the end of each procedure. It can
  also be used to perform personal monitoring of
  clothing prior to leaving the lab.

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Typical Instruments seen in Dalhousie Laboratories
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Direct Surveys Routine Performance Checks on
Survey Meters

• Prior to every use inspect the instrument
  carefully
• Are there indications it may have been dropped
• Is there any visible damage to the meter
• Does the cable show any sign of breakage
• Is the meter free of contamination
• Is the needle in the zero position
• Does the needle bounce around excessively when
  the meter is moved

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Direct Survey contd

• Verify that the instruments audible response is
  working and keep audio on during all procedures
• Turn the range selector knob to the highest scale
  (least sensitive) and let the needle stabilize.
  Continue turning to more sensitive scales until a
  response is observed
• Check the response of the meter on each
  operational scale with a radiation check source
  that gives a reading close to mid-scale. The
  reading should not deviate from the value by more
  than 10
• Have the instrument calibrated annually, if
  required by CNSCs document R-117, Requirements
  for Gamma Radiation Survey Calibration

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Direct Survey contd

• Prior to beginning your direct survey you must
  first perform a battery check followed by a
  background check in an area of known low activity

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Direct Survey - Procedure

• Pass the probe over the area to be monitored
  taking care that the probe does not come in
  contact with the surface being monitored. Measure
  with an S shaped motion. If the meter needle
  reads off scale, gently turn the range selection
  knob to a higher scale.

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Direct Survey contd

• Typical areas to be monitored
• work benches, equipment, fume hoods, floor
  areas, storage areas etc.. Once you have
  completed your survey record your results and
  clean any contaminated areas. If a high count
  rate persists you should perform a wipe test to
  determine if the residual activity is loose or
  fixed

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Direct Survey contd

• Ensure that results are recorded and filed in
  your Radiation Safety Records book.

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Direct Survey Useful Tips

• Always ensure that the instrument is turned OFF
  when not in use to preserve battery life
• Do not allow the instrument to get wet
• Use care to avoid puncturing the window as this
  will render the unit unusuable
• Do not put undue stress on cables and cable
  connectors
• Avoid exposing the unit to physical shock and/or
  extremes of temperature
• NEVER change detector probes with the instrument
  on
• NEVER tamper with the instruments high voltage

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Indirect Survey (wipe test)

• The indirect survey or wipe test is the most
  sensitive method for determining the amount of
  removable contamination. It is the only method
  for determining whether contamination is loose
  (removable) or fixed.

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Indirect Survey contd

• Prepare a plan for wipe testing the lab, either
  in the form of a lab floor plan, or in the case
  of large multi-user facilities a list of
  locations with an identifier on each location to
  be tested.

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Indirect survey contd

• At a minimum the following locations must be
  included in your wipe test
• ? workbench
• ? floor near workbench
• ? fume hood (including sash, ledge, work
  surface)
• ? floor near fume hood
• ? wash up sink
• ? floor near sink
• ? storage fridge or freezer
• ? floor near fridge/freezer
• ? equipment used
• ? telephone receivers, door knobs, computer key
  boards

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Indirect Survey contd

• Items to be included on wipe test cart
• filter paper or Q-tips
• suitable solvent
• tongs
• counting vials

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Indirect Survey contd

• Using a Q-Tip or a filter paper disk moistened
  with a suitable solvent wipe a representative
  area (100 cm2) in an S shaped motion. Use only
  one wipe per location.

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Indirect Survey contd

• Prepare a control sample using a clean swab or
  filter. The control provides the background count
  rate to which you will compare your sample
  results. Allow the wipes to air dry.

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Indirect Survey contd

• Prepare samples for counting by placing the
  filter or swab in a LS counting vial. If you are
  using a filter ensure that you place the wiped
  side up on the bottom of the vial.

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Indirect Survey contd

• Add an appropriate cocktail

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Indirect Survey contd

• Mark the cap with correct wipe identification and
  re-cap vial

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Indirect Survey contd

• Count using a counting window appropriate for the
  nuclear substance for which you are surveying.

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Indirect Survey contd

• Once samples have been counted and results
  interpreted re-test any areas that were
  identified as hot

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Indirect Survey contd

• An area within the workspace has been identified
  as contaminated. This area will be cleaned
  immediately and re-wiped to check for any further
  residual contamination

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Indirect Survey

• Ensure that results are recorded and filed in
  your Radiation Safety Records book.

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Indirect Survey contd

• Remember that the wipe efficiency is only about
  10.

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Indirect Survey contd

• Once counting is complete and results filed
  dispose of vials as per University guidelines

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Indirect Survey useful tips

• Factors such as chemiluminesence and static can
  cause false positive results.
• A moist filter or Q-Tip improves the survey
  sensitivity enabling more activity to be
  transferred.
• Using a large filter may cause the filter to fold
  in on itself or attach to the side of the vial,
  thus reducing the counting efficiency
  particularly for lower energy beta emitters.
• LS counting efficiencies are normally provided by
  the manufacturer.