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6. Use of unsealed radioisotopes in teaching & research

6.1 GENERAL

The Internal Permit Holder must ensure that only persons properly trained and informed of the hazards involved are allowed to handle radioisotopes. In the case of undergraduate students, handling should be limited to sources of a type and activity commensurate with the knowledge and training of the students at a any given stage of their academic careers. A copy of the Internal Permit shall be prominently displayed in each laboratory in which unsealed radioisotopes are stored and/or used.

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6.2 CLASSIFICATIONS OF RADIONUCLIDES

The CNSC has grouped radionuclides into 3 groups. The 3 groups are shown below:

Class A Radionuclides: are long-lived or emit alpha radiation

Na-22 Na-24 Co-60 Zn-65 Sb-124
Ir-192 Ta-182  
All Alpha Emitters and their daughter isotope

Class B Radionuclides: are long-lived or emit beta or gamma radiation

As-74

Fe-59 In-111 Sc-46 Sr-85
Au-198 Ga-67 In-114m Se-75 Sr-90
Br-82 Gd-153 Nb-95 Sm-153  
Co-58 Hg-203 Rb-84 Sn-113  
F-18 I-131 Rb-86 Sn-123  

Class C Radionuclides: are short-lived and emit beta or gamma radiation

Au-195m Cl-36 Kr-81 Re-188 Tl-201
C-14 Co-57 Nb-98 Ru-103 Xe-127
Ca-45 Cr-51 Ni-63 S-35 Xe-133
Cd-109 H-3 P-32 Sr-89 Y-90
Ce-133 I-123 P-33 Tc-99 Yb-169
Ce-144 I-125 Re-186 Tc-99m  

Note: Most frequently used radioisotopes at McGill University are Class C. Isotopes in bold and italic are commonly found in our laboratory facilities.

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6.3 RADIOISOTOPE LABORATORIES

6.3.1 Classification of Laboratories

Any laboratory or area in which unsealed radioisotopes are stored, handled or used shall be designated to that effect and should comply with specific requirements regarding the general layout, the types of materials and the instrumentation provided. The Environmental Safety Office should ascertain the adequacy of the facilities before unsealed radioisotopes are used in a new laboratory.

Most research and teaching laboratories used for "tracer" investigations are of the "low level" type - essentially a basic chemistry laboratory plus some additional facilities. However, CNSC Regulatory Document R-52 (Design Guide for Basic and Intermediate Levels Radioisotope Laboratories) recommends the upgrading of such laboratories whenever more than minimum activities or Annual Limit of Intake (ALIs) of radioisotope are likely to be used.

The maximum activity of radioactive material that may be stored, handled or used in a laboratory of given classification depends on the "radiotoxicity" of the radionuclide concerned, as expressed by the ALI and the type of procedure undertaken. Appendix C gives the toxicity classification of various radionuclides and the "modifying factors" applying to procedures of different types. The maximum activities thus determined must not be exceeded.

For radioprotection purposes, the list of rooms or laboratories are designated for the use and storage of nuclear substance primarily in terms of how much radioactive material is to be handled. See Appendix F for more information on the Levels of use of unsealed nuclear substances.

Room classifications and purposes

Storage Room
A room, where any supplies of sealed or unsealed nuclear substances are kept without being handled. Examples include storage of waste and/or decaying radioactive material and supplies of nuclear substances held for future use.
Basic-Level Laboratory
A room, in which an unsealed nuclear substance is used which is larger than one "exemption quantity" as defined in section 1 of the Nuclear Substances and Radiation Devices Regulations, and where the largest quantity of each unsealed nuclear substance in one container does not exceed five (5) times its corresponding Annual Limit of Intake (ALI), as defined in section 12 (1) of the Radiation Protection Regulations.
Intermediate-Level Laboratory
A room, where the largest quantity of each unsealed nuclear substance in one container does not exceed 50 times its corresponding ALI.
High-Level Laboratory
A room, where the largest quantity of each unsealed nuclear substance in one container does not exceed 500 times its corresponding ALI.
Containment-Level Room
A room, where the largest quantity of each unsealed nuclear substance in one container exceeds 500 times its corresponding ALI.

6.3.2 Requirements for Radioisotope Laboratory Facilities

The type of laboratory required for radioisotope work depends upon several factors including the amount of radioactive material used, the type of operation performed, and the radiotoxicity of the radioisotope. Facilities must be approved by the RSO prior to any work beginning with radioactive materials. Renovated or new facilities shall meet CNSC's requirements in Regulatory Guide R-52 "Design Guide for Basic and Intermediate Levels Radioisotope Laboratories".

Work areas to be designated as radioisotope laboratories shall meet the requirements set out below, which refer to features related to radiation safety. Requirements have been separated to show essential requirements as distinct from those which are recommended. The latter group ought to receive appropriate consideration with a view to possible upgrading of the facilities.

Location

  1. Choose areas to minimize overall movement of radioactive materials.
  2. Select locations that minimize potential exposures to disinterested persons.
  3. Arrange for storage or preparation rooms to be adjacent to the active working area.
  4. Consider floor-loading requirements, ease of access to ventilation ducts for fume hoods, location of drains for sinks, and similar matters. The result of the test shall be recorded.

Ventilation

Adequate ventilation is essential for safety in radioisotope laboratories, as well as in chemical and biological facilities. The comfort of personnel should not be ignored as a factor of overall safety in the work area. Fume hoods are the most important single item and are essential if any work might result in the production of airborne radioactivity such as particulate, aerosols or gases. Although fume hoods may not be required in the initial stages of a project, the design of laboratory facilities should contemplate future needs.

The following are essential requirements for radioactive fume hoods:

  1. Air vented through the hood will be vented without recirculation.
  2. The fume hood will be constructed of smooth, impervious, washable and chemical resistant material.
  3. The linear face velocity of the fume hood will be between 0.5 and 1.0 metre/second.(100 and 200 feet/minute).
  4. Before radioactive material is used in the fume hood, the hood will be tested to verify the flow rate and the absence of counter-currents or eddie-currents. The results of the test shall be recorded.
  5. Fume hood filters will be monitored for radioactive contamination before disposal.
  6. The fume hood exhaust duct will be constructed of corrosion-resistant material.
  7. All joints in the exhaust duct will be smoothly finished and sealed.
  8. The fume hood exhaust fan will be placed close to the discharge point.
  9. Exhaust stack height will ensure acceptable dilution, dispersion and elimination of unacceptable re-entry through building openings.
  10. Exhaust ducts from fume hoods in radioisotope laboratories will be identified on plans supplied to maintenance personnel.
  11. Laboratory will be at negative pressure with respect to surrounding areas.

In addition, the following considerations are recommended:

  1. All air from the laboratory will be vented through the fume hood.
  2. Consideration will be given to the weight of shielding that must be supported by the working surface of the fume hood.
  3. The working surface of the hood should have raised edges.
  4. A readily visible flow-measuring device will be included on the face of the fume hood.
  5. The fume hood exhaust duct will be marked at 3 metre intervals with radiation warning symbols.
  6. The fume hood motor will be mounted outside the exhaust duct.

Finishing and fixtures

It is essential that:

  1. Flooring will have an impervious surface with a strippable coating.
  2. All joints in the flooring will be sealed.
  3. Counter surfaces will have a smooth, impervious, washable and chemical resistant finish.
  4. All joints on the counter will be sealed.
  5. Sinks will be made of a material that is readily decontaminated.

It is recommended that:

  1. Walls and ceilings will have smooth, impervious, washable finishes.
  2. Cupboards and shelving will have smooth, impervious, chemical-resistant and washable finishes.
  3. Light fixtures will be easy to clean.
  4. Light fixtures will be enclosed.
  5. Sinks will have overflow outlets.
  6. Taps will be operable by means not requiring hand contact.
  7. An emergency shower will be provided.

Plumbing

It is essential that:

  1. Chemical resistance of the drains should be considered.
  2. Drains from the radioisotope laboratory will be identified on plans supplied to maintenance personnel.

It is recommended that:

  1. Faucets with vacuum or cooling line attachments will have back-flow protection devices.
  2. The drain from the laboratory will go directly to the main building sewer.
  3. The drain line will be marked at 3 metre intervals with radiation warning symbols.
  4. Sink drain traps will be readily accessible for monitoring.

Storage

For the storage of both radioactive stocks and wastes, it is essential that:

  1. Materials that may give rise to radioactive aerosols or gases be stored in an appropriately vented area.
  2. Appropriate shielding be provided for storage locations.

It is recommended that:

  1. An area to store waste outside the laboratory be provided.

Security

It is essential that all areas in which radioactive materials are used or stored be secured against unauthorized entry. For small quantities of radioactive material, door closers, good locks on doors and/or cabinets will suffice; more elaborate measures may be required in other circumstances.

Miscellaneous

FOOD OR BEVERAGE PREPARATION FACILITIES SHALL BE EXCLUDED FROM THE LABORATORY.

In addition it is recommended that:

  1. Provision be made for hanging up potentially contaminated laboratory clothing within the laboratory.
  2. Provision be made for an appropriate radiation monitoring device to be installed in the laboratory.
  3. Provision be made for emergency lighting in the laboratory.

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6.4 POSTING

All approved locations must be posted with an approved Radioactive Warning Sign, in any area where the activity of any radioisotope may exceed 100 Exemption Quantities (EQ) or exposure may exceed 25 uSv/hour. Required signs and labels are according to the following:

All points of entry, laboratory, storage area, or other licensed area
Radioactive Warning Sign, Lab Information Card with Permit Holder name and office phone #, 24 hour contact number
Inside the lab, in a prominent location
Copy of the Internal Permit, CNSC Safety Poster that corresponds to the Lab Classification
Storage Location
Radioactive Warning Sign
Work Area
Radioactive Warning Sign or Tape identifying the workstation

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6.5 POSTING OF RADIATION WARNING SIGNS

Radioactive Warning Signs (RWS) may not be used in a place where the radiation or nuclear substance is not present. The same argument goes for radiation working areas; signage should be kept to minimum because too many signs may incur unwanted fear. According to the CNSC, RWS must be magenta or black on yellow background (i.e. the universal trefoil & letters in magenta or black) and with the appropriate wording "RAYONNEMENT-DANGER-RADIATION"

Composition of the radiation symbol

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6.6 INVENTORY REQUIREMENTS

Every Permit Holder must establish and maintain an inventory of unsealed radioisotopes in his possession, listing the activity in stock of each radionuclide in a specific chemical form, with the location(s) of storage and use, together with data on the disposal of radioactive waste (see Appendix J-1). This information can also be obtained by Permit Holders if they use Radiation Tracking System (RTS) report commands.

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6.7 STORAGE OF RADIOACTIVE MATERIAL

  • All radioactive material must be stored in shielded containers which are marked with:
    • a description of the contents of the container, including radionuclide, chemical form, physical form if appropriate, maximum activity on a stated date, and;
    • a radiation warning sign.
  • All containers must be stored in a safe area, which must be lockable.
  • The storage area must be of fire resistant construction.
  • The storage facility must have sufficient shielding to reduce the radiation in occupied and accessible areas to levels that are consistent with the dose limits summarized in Section 3.7 & 3.8. The permissible dose-equivalent rate (Sv per hour) at any location depends:
    • on the occupancy factor, which may range from 1/16 for an accessible but rarely occupied area to 1 for an area assumed to be permanently occupied;
    • the category of the occupants, i.e. NEWs, Radiation Users or other (non-radiation) persons.
    • The maximum dose-equivalent rates for full occupancy (= 40 X 50 = 2000 hours/year) are:
      • for NEWs, 7.5μSv/h (0.75 mrem/h), giving 15 mSv/year (the investigational level); and
      • for Radiation Users and non-radiation workers, 0.5μSv/h (0.05 mrem/h), giving 1 mSv/year (the investigational level). Any accessible area where the dose rate level may exceed 25μSv/h (2.5 mrem/h) must be indicated with a radiation warning sign. Note that both investigational levels are beyond the action levels as explained in Section 3.7.
  • Gaseous or volatile radioactive materials must be kept in a fume hood provided with adequate ventilation.
  • It is strictly forbidden to store or consume any kind of food or beverage in an area where radioactive materials are used or stored.
  • Details of the storage locations of radioactive materials, including type of radionuclide(s) and maximum activity of each type, must be supplied in an application for an Internal Permit. Environmental Health & Safety must be notified of any significant changes (for example, the deletion or addition of a radionuclide, or change in personnel or a change in location of a storage or use area).
  • A room in which the total of the exemption quantities (see Section 8.2.1) of the radionuclides stored within exceeds 100 must display a warning sign on the door, giving details of the nuclides in storage.

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6.8 LABORATORY HANDLING OF UNSEALED RADIOISOTOPES

In any laboratory where both radioactive and non-radioactive work is carried out, a separate area must be set aside for radioisotope work and this confined work section be clearly designated as the "radioactive area".
  • Laboratories must be kept locked when not attended.
  • Smoking, eating, drinking and storage of food or beverages and applying cosmetics or contact lenses are prohibited in any area used for storage and manipulation of radioactive materials.
  • Pipetting of radioactive solutions must not be carried out by mouth.
  • Whenever possible, procedures involving radioactive materials should be carried out in trays or on benches lined with disposable absorbent material.
  • Procedures that might produce airborne radioactive contamination (example: gases, vapours, mists and dust) should be carried out in a fume hood.
  • Procedures involving dry radioactive powders should be carried out in a glove box.
  • Keep contaminated glassware segregated from clean glassware.
  • Disposable containers and instruments should be used if possible.
  • Personal protection equipment (e.g. protective eyewear and lab coat) must be worn. When hand contamination is possible, protective gloves are required. Closed shoes must be worn.
  • After handling unsealed radioactive materials, and before leaving the laboratory, users must wash their hands and ensure that hands, clothing and shoes are free of radioactive contamination.
  • Equipment, other tools and utensils used for work with radioactive material should not be used for other purposes and should be surveyed for contamination prior to removal from the laboratory.
  • Have a radiation monitor available when working with radioactive materials, and use it to arrange procedures so as to minimize personal radiation exposure. It must be remembered that these instruments are ineffective to radiation produced by weak beta emitters such as H-3, C-14 and S-35 for which special contamination monitoring like wipe tests is required.
  • Wipe tests must be made on surfaces and equipment likely to become contaminated with radioactive material. These tests should be made either weekly for frequent regular use or after each significant workload. Records of the tests must be properly documented and filed (see Sections 5.4 and 5.7 for further details), preferably in a binder like the McGill Radiation Log Book.