SAFETY AND WORK PROCEDURES IN RESEARCH USING RADIATION

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SAFETY AND WORK PROCEDURES IN RESEARCH USING
RADIATION
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Contents

• Introduction
• Types and Characteristic of Radiation Sources
• Radiation Hazard
• Facility Planning
• Classification of Work Areas
• Work Procedures for Unsealed Sources
• Procedure in Working with Sealed Sources
• Safety Equipment
• Transportation
• Treatment and Disposal of Waste
• Monitoring

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Introduction
Radiation in Research
Education
Industry
Medicine
Agriculture
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Introduction
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Types and Characteristics of Radiation Sources
The first step in managing radiation hazards is
to identify the types and characteristics of the
radiation source
Types of Radiation Sources
Sealed Radioactive Sources
Unsealed Radioactive Sources
Nuclear Reactor
Irradiating Apparatus
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Types and Characteristics of Radiation Sources

• There are two types of reactor nuclear
• Nuclear power plant
• Research reactor
• xxxxx.

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Types and Characteristics of Radiation Sources

• There are numerous types of irradiating apparatus
  used in research. Examples
• X-rays
• XRD
• XRF
• XPSS
• ESM machines
• Linear accelerator etc
• Unlike radionuclide, these radiation sources will
  only emit radiation when high voltage is applied
  to it or when it is switched ON. Safety
  engineering features are built into their design.

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Types and Characteristics of Radiation Sources

• Radionuclides may be categorized into
• Sealed radionuclides
• Sealed radionuclide or sealed source is radiation
  source consisting of any radioactive material,
  nuclear material or prescribed substance firmly
  incorporated in solid and effectively inactive
  material, or sealed in an inactive container of
  sufficient strength to prevent, under normal
  conditions of use, any dispersion of its
  contents.
• Sealed sources when intact posed an external
  radiation hazards.
• Unsealed radionuclides
• These are exposed radionuclides usually in solid,
  liquid and gaseous forms.
• Unsealed radionuclides posed internal and
  external radiation hazards.

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Types and Characteristics of Radiation Sources
Characteristics of Radiation
Radiation of different quality exerts different
Linear Energy Transfer (LET). LET is defined as
the amount of energy transferred to the media per
unit distance it traverses in the media (keV ?-1).
Quality (e.g. types of radiation the sources
emit, i.e. alpha, beta, gamma, neutron and heavy
charged particles).

• Radiation quantity
• source activity (Bq)
• activity concentration (Bq ml-1 or Bq g-1)
• dose it produces (Sv, Gy)

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Types and Characteristics of Radiation Sources
3 categories of radionuclide are used in research
Radionuclides with long half-lives
Radionuclides with medium half-lives
Radionuclides with short half-lives
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Radiation Hazard
Types of Radiation Hazard
Internal Radiation Exposure
External Radiation Exposure
Contamination
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Radiation Hazard

• Radiation hazards may be divided according to
• External radiation exposure
• Hazard is related to high penetrating radiation
  source outside the body.
• Such radiation (e.g. electromagnetic radiation,
  high-energy beta and neutron) could penetrate the
  skin and body to cause harm to the body.
• Internal radiation exposure
• Hazard is related to radiation source in the
  body.
• It involves radiation with low penetrating power
  but usually with high LET that can cause
  significant internal damage (e.g. alpha and beta
  particles).

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Radiation Hazard

• Contamination
• Contamination involves deposition of radionulide
  on the outer surface of the body (e.g. skin), or
  on wall and floor surfaces of building.
• Contamination involves unsealed radionuclides or
  originally sealed radionuclides that leaks due to
  a compromise seal.
• Radionuclide contamination is both an internal
  radiation hazard when it is ingested, inhaled or
  penetrated the skin and into the body, and an
  external radiation hazard if the radiation is
  highly penetrating.

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Facility Planning

• Selection of locations and arrangements of work
  areas, radioactive waste storeroom, and office
• Facility planning may involve selection of
  locations and arrangements of work areas
  (including laboratories), radioactive waste
  storeroom and office. Such selections depend on
• Types of radiation used
• Physical properties of radionuclides
• Quantity of radionuclides to be kept
• Methods of using radionuclides and
• Methods of disposing the radionuclides.

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Facility Planning

• Construction consideration
• Facility construction is dependent on types of
  radiation, physical and chemical properties of
  radionuclide, quantity of radionuclides to be
  used, stored and disposed.
• Consideration must take into account the stage of
  construction (e.g. whether it is on the plan or
  during modification).
• It is relatively cheaper to make any modification
  of facility at the planning stage compared to
  when the building or facility is fully completed.

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Facility Planning

• Work place design
• Work place design depends on
• Types of radiation
• Radionuclide quantity
• Sealed and unsealed conditions
• Methods of use and
• Storage and disposal of radioactive waste.
• Work place is designed to provide for protection
  and safety in compliance with the applied
  standards.

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Facility Planning

• Work place design
• Design must meet engineering, performance and
  functional specifications.
• Design must meet quality norms commensurate with
  the protection and safety significance of
  components and systems.
• Design must incorporate the need for
  classification of working areas, storerooms to
  store radiation source and waste.
• If radioactive dust or gas is to be used than a
  proper ventilated room must be considered.

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Facility Planning

• Work place design
• A control barrier must be erected at the entrance
  of a controlled room used to handle unsealed
  sources.
• Radiation monitoring equipments (e.g. hand and
  foot monitor, survey meters etc.), and personal
  protective equipment are placed at the
  entrance/exit to the working area.
• Specially built shielded room must be erected for
  irradiating apparatus and sealed sources.

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Facility Planning

• Work place design
• Shielded rooms for irradiating apparatus and
  sealed sources have some general requirements.
  These include
• Room is designed and built according to the
  standards required for its purpose
• Room must be classified and demarcated
  appropriately and
• All necessary control measures and procedures in
  accordance to its classification must be
  enforced.
• Besides safety, the overall work place design
  must provide for comfort of work and security of
  the facility.

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Facility Planning

• Work place design
• Work place design includes storage area. Storage
  area should at least
• have adequate shielding for the types of
  radiation
• allow easy access to stored materials
• be ventilated
• be under locked security (e.g. bomb pit for
  storing radiation sources used in NDT)
• have appropriate label with warning signage and
• include dedicated delay tanks for temporary
  storage of liquid waste.
• Work place design is not limited to the planning
  stage. Modification and alteration of work place
  could come when new work activity is introduced
  to the facility. Consequently, workplace design
  comes after construction of the facility.

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Classification of Work Area
Radiation Work Areas
Supervised Areas
Controlled Area
Clean Area
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Classification of Work Areas

• Clean area
• Area where the expected maximum dose for that
  area does not exceed the dose limit for a member
  of the public.
• Supervised area
• Work area for which the occupational exposure
  conditions are kept under review even though
  specific protective measures and safety
  provisions are not normally needed.

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Classification of Work Areas

• Controlled area
• Work area where specific protection measures and
  safety provisions are or could be required for
  controlling normal exposures or preventing the
  spread of contamination during normal working
  condition, and preventing or limiting the extent
  of potential exposures.
• Area where the expected maximum Permissible Dose
  Limit is greater than 3/10 (6 mSv y-1).
• This area is subject to special rules for the
  purposes of protection against ionizing radiation
  and to which access is controlled.

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Work Procedures for Unsealed Sources

• One method in developing safe work procedure is
  through Job Safety Analysis.
• Safe work procedure must be
• Written in a language that is concise, precise
  and easy to understand by the intended user and
• Must include not only the method of carrying out
  the task but also the elements of safety and
  emergency actions to be taken when the needs
  arises.

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Work Procedures for Unsealed Sources

• All safe work procedures must be tested before
  use and reviewed periodically to ensure their
  relevancy and appropriateness for the intended
  purposes.
• All safe work procedures need to be explained to
  users. While most procedures require briefing and
  explanation some require prior training, while
  others need to be further complemented with
  supervision.
• All safe work procedures must be developed
  following radiation risk assessment.

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Work Procedures for Unsealed Sources

• Handling techniques
• The objectives of handling techniques in works
  related to radiation source are to reduce
  exposure and to prevent contamination.
• Handling techniques involve
• The use of shielded room for work with very high
  radioactivity
• The use of remote control apparatus (e.g. tongs)
  to handle sources
• Procedure to transfer liquid sample (e.g. should
  never pipette with the mouth)
• The use of suitable waste bin for different
  radionuclides, and physical properties of waste
  (e.g. liquid, solid or gaseous waste) and
• The use of correct personal protective equipment
  when handling unsealed radionuclides. E.g. the
  use of rubber gloves and laboratory coats while
  handling unsealed sources.

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Work Procedures for Unsealed Sources

• Separation of activity and dilution of
  concentration
• The safest way to work with radiation source is
  to use the optimum amount or quantity.
  Radionuclides are not cheap and a posed radiation
  risk when used in excess.
• Lower activity means lower doses. If spillage and
  contamination occur, then the cleaning up process
  will only involve low activity and concentration.
  
• It is important to follow the recommendations of
  supplier on the need to separate and dilute the
  radionuclides.

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Work Procedures for Unsealed Sources

• Radioactive gases
• Radioactive gases can cause internal radiation
  exposure. The use of proper ventilation system
  with continuous monitoring of discharge must be
  installed in facility using radioactive gases.
• Vertical laminar flow may be considered for use
  in handling radioactive gases but care must be
  taken to prevent air turbulence in the hood.
• All exhaust system related to possible discharge
  of radionulide outside the working must be
  strictly monitored and controlled. No release of
  radioactive materials for disposal, recycling or
  reuse is allowed without prior written approval
  of the appropriate authority.

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Work Procedures for Unsealed Sources

• Handling low activity sources
• This is normally related to handling
  environmental materials containing low activity
  naturally occurring radioactive sources. Although
  the source activity is low, care must always be
  taken to ensure unnecessary exposure to the
  radiation.
• Care must also be taken to ensure that the level
  of activity remains below the permissible level
  (e.g. ALI and DAC) approved by the authority.
• Area monitoring of work area and storage room
  must be carried out continuously.
• The concept of ALARA must always be used during
  handling of low activity sources to ensure the
  lowest achievable dose exposure.

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Procedure in Working with Sealed Sources

• Time, shielding and distance
• Time, shielding and distance are three principles
  of methods of control that can be incorporated
  into engineering as well as management controls
  of radiation hazard.
• Longer exposure times means higher dose of
  exposure and vice versa.
• Thickness, density as well as types of materials
  (Z number) determine the effectiveness of shield
  against a particular radiation quality. Generally
  thicker material increases the attenuation of
  radiation intensity. High Z materials (e.g. Pb)
  are effective in attenuating electromagnetic
  radiation (e.g. gamma and x-rays). Low Z
  materials (e.g. H) are effective in attenuating
  neutron sources.
• Inverse square law is used to reduce dose through
  distance.

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Procedure in Working with Sealed Sources

• Leak test
• A radiation leak is divided into two
• Design leak or allowed leakage by the
  manufacturer on a particular apparatus and
• Defect of sealed sources, apparatus or machine.
• Leak test is a physical test conducted on sealed
  sources to ensure the integrity of the source
  capsule. Leak test is also done on irradiation
  machine (e.g. X-ray machine).

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Procedure in Working with Sealed Sources

• Leak test
• Level of radiation leakage is determined based on
  the deviation of measured dose from the dose of
  design leak.
• Purpose of leak test is to confirm the
  classification of sealed sources and performance
  of irradiation machine is maintained at all times
  during its use.
• Leaks due to defect of sealed sources, apparatus
  or machine must be assessed periodically
  (interval is prescribed by the authority) or
  whenever damage of the source (if radiation
  source, it is the capsule or seal) is suspected,
  or when there is a presence of contamination
  (allowable leaked activity 185 Bq).

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Procedure in Working with Sealed Sources

• Methods used in leak test
• Test methods used in detecting and measuring
  leaks from sealed sources may be divided into
  two
• Radioactive methods
• Example of radioactive methods include
• Wipe (smear) test
• Cellulose tape test
• Scrub test
• Soaked-I test
• Soaked-II test

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Procedure in Working with Sealed Sources

• Methods used in leak test
• Test methods used in detecting and measuring
  leaks from sealed sources may be divided into
  two
• Non-radioactive methods
• Examples of non-radioactive methods include
• Vacuum bubble test
• Hot liquid bubble
• Gas pressurization bubble test
• Helium test
• Helium pressurization test
• Water pressurization test

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Procedure in Working with Sealed Sources

• Methods used in leak test
• Counting equipment is used in leak tests.
• Counting equipment used in leak tests are similar
  to that used to detect the types of radionuclide,
  radiation as well as to measure the activity of
  the leak source.
• Liquid scintillation counters may be used for
  beta emitters while gamma counters may be used to
  measure gamma emitters.

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Safety Equipment

• Storage equipment
• Storage equipment include portable radioactive
  waste container for temporary storage of waste
  emitting different types of radiation emitters.
  (e.g. lead pot).
• Transport equipment
• Transport equipment may be divided into on-site
  and off-site equipment.
• On-site transport equipment is usually designed
  for transporting low activity sources.
• Sources are carried in transport container with
  secondary shielding by trained personnel.

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Safety Equipment

• Laboratory equipment
• Containers are used to temporarily store
  radioactive materials. Containers to store gamma
  emitters must be lead lined. Containers may be
  made of disposable materials (e.g. plastic bags)
  that may be disposed after used.
• Disposable tools include disposable pipettes, and
  dishes. Disposable tools are used with unsealed
  sources.
• Remote arm (or tongs) may be used to handle
  radiation sources at a distance.
• Shields are another example of laboratory
  equipment. Shield may be portable or permanently
  fixed. Example of portable shields for beta
  particles is Perspex.

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Safety Equipment

• Personal Protective Equipment (PPE)
• PPE are used to reduce the likelihood of exposure
  and/or contamination, and their radiological
  impact should exposure or contamination do occur.
  Examples of PPE include overalls, aprons, rubber
  gloves, footwear, safety goggles and visors, and
  even respirators and breathing apparatus.
• PPE such as lead apron and lead glasses are used
  to reduce exposure to penetrating ionizing
  radiation (e.g. x-ray and gamma-ray).
• PPE should always be the last choice of radiation
  risk control after all other risk control
  measures have been considered and preferably
  implemented. Preference should be given to
  engineering control followed by administrative
  control in controlling radiological risk.

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Transportation

• Movement of radioactive material within and
  off-site of the premise shall be carried out
  according to Radiation Protection (Transport)
  Regulations 1989.
• Get an approval from AELB 14 days before
  transportation.

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Treatment and Disposal of Waste

• Research facility produces radioactive wastes
  through the use of unsealed sources. These wastes
  could be the element itself or the radionuclides
  tagged to a non-radioactive compound.
• Problem of disposing the radioactive waste is now
  complicated by the presence of chemical
  compounds, which by itself could be toxic to the
  ecosystem.

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Treatment and Disposal of Waste

• Radioactive wastes mix with other toxic chemical
  compounds must be treated before disposal.
  Treated radioactive wastes may be disposed either
  through delay and decay, dilute and disperse or
  concentrate and contain.
• Long-lived radionuclides or radionuclides with
  long half-life (e.g. U-238 and Th-232) require
  them to be kept in a proper container and stored
  in a safe place.
• Radionuclides with short half-life (e.g. P-32)
  may require that it be temporarily stored to
  facilitate the radionuclides to decay to its
  stable form before being treated in a
  non-radioactive procedure or discharged into the
  environment.
• Radionuclide may be diluted and dispersed if they
  are naturally found in the environment and is at
  a concentration similar to that in the
  environment (e.g. H-3 and C-14).

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Treatment and Disposal of Waste

• Treatment process for radioactive waste does not
  differ from other non-radioactive waste except
  for the needs to provide for shielding against
  ionizing radiation.
• General procedure of waste management involves
• classification of the waste
• pre-treatment
• treatment
• conditioning
• storage
• disposal

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Treatment and Disposal of Waste

• Classification of waste
• Is done based on its half-live and activity. IAEA
  proposed that radioactive waste be classified
  according to
• Exempted waste (EW) its disposal results in an
  exposure of less than 0.01 mSv to the public
• Low and intermediate level waste with short
  half-lives (LILW-SL)
• Low and intermediate level waste with long
  half-lives (LILW-LL) A 30 years half-life is
  used to differentiate between short and long
  half-lives and
• High level waste (HLW).
• Waste may also classified according to the
  physical properties of the waste, i.e. solid,
  liquid or gaseous wastes. Except for research
  reactor facility, most research facility does not
  produce high-level waste.

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Treatment and Disposal of Waste

• Pretreatment
• At this stage the waste is categorized and
  separated according to its physical state or
  stabilizing it with specific materials.
  Pretreatment helps to reduce the volume of the
  waste.
• Treatment
• The main purpose of treatment is to reduce the
  waste volume. At this stage the principles of
  delay and decay, and concentrate and contain is
  applied where practicable. Treatment may also
  increase the volume (e.g. in dilute and
  disperse).
• Conditioning
• At this stage, binding matrix is added to liquid
  or solid waste to become homogenous solid
  monolith with low leach ability.

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Treatment and Disposal of Waste

• Storage
• With some costs research facility may send their
  waste to MINT for storage. Otherwise some
  research facility stores their own waste. Delay
  tank should be used for temporary storage of
  short half-lives radionuclides before disposal
  into the environment or treated as
  non-radioactive waste.
• Disposal
• Upon treatment radioactive waste will eventually
  be disposed off into appropriate repository. MINT
  does provide repository for organization that are
  unable to dispose of their waste. Wastes from
  sealed sources are disposed according to the
  procedures approved by the appropriate authority.

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Monitoring

• Objectives of monitoring are to obtain an
  estimate on the doses received by radiation
  workers in the controlled and supervised areas.
• Two types of monitoring that need
• to be done in a research facility
• area monitoring, and
• personnel monitoring.
• In the case of personnel monitoring, monitoring
  is carried out on exposures from internal and
  external radiation. One example of internal
  radiation monitoring is the use of whole body
  counter.

X-Ray
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Monitoring

• Monitoring starts before operation, continues
  during operation and after operation ceases. Such
  monitoring practice is pertinent for facility
  that uses unsealed radionuclide sources.
• Radiation monitoring is carried out using
  specialized equipment that includes
• Dosimeters (pocket dosimeters, film and TLD
  badge) are used to measure accumulated dose
  received by radiation workers over the preset
  time and
• Geiger Mueller survey meters may be used to
  monitor external radiation including detecting
  and measuring surface contamination.

Alpha
Beta and Gamma
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Summary
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Thank Youfor your attention