Module 9: U of T Policies, Standards, and Procedures for Radiation Safety

9.1 U of T Radiation Safety Policies

The ALARA concept has been adopted by the UTRPA as the basic philosophy governing the use of radioactive materials at the U of T.

The UTRPA radiation safety policies are presented in the “University of Toronto Ionizing Radiation Safety – Policies and Procedures Manual”. It is the responsibility of all persons who supervise work with radioactive materials to become familiar with the information presented in this manual.

In addition to the information and requirements set out in the “Manual”, the UTRPA may require additional compliance as necessary. Each policy will be approved by the UTRPA and notification sent to each permit holder. The policies are effective upon approval by the UTRPA.

The main policies are:

  • Disciplinary action (4-step policy)
  • Security of radioisotope laboratories
  • Decommissioning
  • Laboratory decontamination
  • Foodstuffs in radioactive laboratories
  • Counting facilities
  • Interrupted laboratories

9.2 U of T Radiation Internal Standards

According to ICRP recommendations, the CNSC has established the following limits for effective dose levels in Canada:

Person Period Effective/Equivalent Dose (mSv)
Nuclear Energy Workers (NEW) One-year dosimetry period* 50 (whole body)
150 (lens of an eye)
500 (skin)
500 (hand and feet)
Five-years dosimetry period** 100 (whole body)
One-year dosimetry period* 20 (whole body)
Pregnant NEW Balance of the pregnancy 4 (whole body)
Members of the public One calendar year 1 (whole body)
15 (lens of an eye)
50 (skin)
50 (hand and feet)
* Every year from January 1st to December 31st ** The current five-years dosimetry period is 2011.01.01-2015.12.31

 

The UTRPA established administrative investigation levels for dose received by a person working with radioactive materials at U of T. The role of the investigation level is to allow for intervention in preventing further exposure. Each time the TLD results are received by the RPS, they are checked against the investigation levels. Action is taken if these investigation levels are exceeded.

The investigation levels at U of T are:

  • 0.4 mSv for effective whole body dose
  • 10 mSv for extremity dose

The bioassay program enables the RPS to immediately detect possible intake of radioactive materials. For radio-iodine, the reporting limit set by the CNSC is 10,000 Bq from a person’s thyroid. However, at U of T, the internal administrative investigation level is set at 1,000 Bq.

Loose contamination limits, determined by swipes, are established by the CNSC for each radionuclide in controlled and public areas. These limits vary from 3 Bq/cm2 to 30 Bq/cm2 for the radioisotopes used as open sources in U of T labs. In accordance with the ALARA principle, in U of T any detectable loose contamination must be removed whenever possible. The minimum detectable activity (MDA) for the method used to determine the contamination must be 0.05 Bq/cm2 for alpha emitting radionuclides, and 0.5 Bq/cm2 for all other radionuclides. If the removal is not possible, the surface should be covered to prevent the spread of radioactive contamination.

CNSC regulations require that signs indicating the presence of radioactive materials must be posted when there is a reasonable probability that a person in the area, room or vehicle, will be exposed to an effective dose rate greater than 25 mSv/h. According to ALARA U of T standard requires that the signs should be posted at a level 10 times lower: 2.5 mSv/h (0.25 mrem/h).

9.3 U of T Radiation Procedures

9.3.1 Procedures for Ordering, Receiving and Transferring Radioactive Materials

9.3.1.1 Obtaining Radioactive Materials

The Radiation Protection Service must be notified of all radioisotope orders, transfers, and gifts before receipt. Permit holders, authorized staff and students can obtain radioactive materials for storage and use in their own designated radioisotope laboratories only.

Currently, all radioisotope orders must be processed using one the following options:

  • the computerised Administrative Management System (AMS), which is accessed by either the departmental business officer or the permit holder
  • the UShop, which is accessed by the permit holder or lab member.

All orders for radioactive materials submitted via the AMS and UShop systems are automatically routed to Radiation Protection Service for approval. The purchaser must provide ALL of the following information for approval of the order:

  • permit number
  • permit holder’s name
  • radioisotope (e.g., P-32)
  • chemical form (e.g., dCTP)
  • total activity per unit ordered (e.g., 0.250 mCi)
  • number of units ordered (e.g., 2 units)
  • supplier
  • date of request
  • delivery location
  • name of lab member/authorized user requesting
  • laboratory telephone number

The link to the purchase request form is: Purchase request

N.B.: Since the AMS and Usource systems are designed specifically for the processing of new purchases, Radiation Protection Service must be notified of any gifts, donations, exchanges and transfers of radioactive materials by email to: sandu.sonoc@utoronto.ca before receipt or transfer. All radioactive materials must be received, used, and disposed of in designated radioisotope laboratories under the same permit.

The Radiation Protection Service must be contacted for assistance whenever radioactive materials need to be transported between buildings or to external institutions. The transport of radioactive materials between buildings is strictly prohibited without prior permission from the RPS.

9.3.1.2 Receiving Radioactive Materials

Caution must be exercised when receiving and opening radioisotope shipments. The packing slip and label information should be compared with the original order to ensure that the correct compound has been delivered. A dose rate meter should be used to check the dose rate being emitted by the package and compare the reading with the value identified on the radiation warning labels (if applicable). The following table describes the dose rate limits for each type of radiation warning label:

9.3.1.3 Radiation Warning Labels: (what they mean)
  • No label: no significant radiation fields outside package (less than 5 mSv/hr)
  • White I: maximum radiation level < 5 mSv/hr at any location on the external surface of the package
  • Yellow II: maximum radiation level > 5 mSv/hr but < 0.5 mSv/hr on surface of the package and maximum radiation level < 0.01 mSv/hr at 1 m away from the package
  • Yellow III: maximum radiation level > 0.5 mSv/hr but < 2 mSv/hr on surface of the package and maximum radiation level < 0.1 mSv/hr at 1 m away from the package
9.3.1.4 Procedure for Receiving Radioisotope Packages
  • Receive radioisotope packages in a designated radioisotope laboratory
  • Wear laboratory coat and gloves
  • If the package shows evidence of leaking, (decolouration), tampering, or if it is damaged
    • Inform RPS and your PH immediately
    • Store package in a fume-hood in a secure place
    • Control the spread of contamination
    • Identify any contaminated areas
    • Mark the contaminated area
    • Inform all lab personal about the possible area being contaminated
    • Clean the contaminated area
    • Check the effectiveness
    • Record the results
  • Check radiation dose rates (if applicable) and compare the result with the type of warning label, as well as the written value. Dose rates exceeding the described limits may suggest an incorrect shipment or leakage from the internal container
  • Open the package in a fume hood, if contents are volatile
  • Wipe test the package and radioisotope container – contact RPS if contamination is found
  • Avoid direct contact with the radioactive material, shield if necessary
  • Compare the information on the packing slip with the container label – contact RPS if there are any inconsistencies
  • Confirm the receipt of the package on the web application of the EHS database. File a copy of the packing slip in the lab (inventory binder)
  • Deface or remove radiation labels from packaging and check for contamination before disposing. Non-contaminated packaging should be disposed of as regular waste, while contaminated packaging must be disposed of in the solid radioactive waste container. Do not put non-radioactive materials in the radioactive waste containers

9.3.2 Procedures for Working with Radioactive Materials

During the general training received at RPS (or equivalent) by all workers with radioactive materials in U of T, general work procedures with radioactive materials are presented.

9.3.2.1 Specific Work Procedures

Each Permit Holder develops a specific set of working procedures. This is a condition of obtaining and keeping a radioisotope permit. The Permit Holder is responsible for training students and staff under his/her supervision in these working procedures. Any change in the procedures and/or radioisotopes (or any increase in the amount used) should be reported in writing to the RPS, with a formal request to amend the permit.

9.3.2.2 Wearing TLDs

Persons handling radioisotopes other than H-3, C-14 and S-35, of activity more than 1.35 mCi per vial/container, must wear Thermo Luminescent Dosimeters (TLDs) whole body and ring. The TLD is the primary source of information for personal exposure, as it measures the accumulated personal dose. TLDs are replaced and analysed on a quarterly basis for the open source workers and for Nuclear Energy Workers (NEWs). All personal dose reports are sent to the NEWs. A “Whole Body” TLD records dose to the skin and body, while an extremity TLD (finger TLD) records the superficial dose to the hands and extremities. TLDs should be stored away from sources of ionizing and UV radiation when not in use.

9.3.2.3 Bioassay Requirements

Bioassays are performed on individuals to determine whether there has been an uptake of radioisotopes in the body. Users of radio-iodine (I-125 or I-131) working with activities greater 2 MBq without containment, or greater than 200 MBq in a fume hood during a period of 24 hours, must register for the thyroid bioassay. The bioassay measurement determines the amount of radio-iodine in the person’s thyroid. Other radionuclides are monitored for uptake by urinalysis. This type of bioassay is necessary for all users of unbound, volatile radionuclides (e.g. tritiated water).

The radioisotope and its biological half-life determine the frequency of bioassay monitoring:

  • Within four days of usage of I-131 and I-125
  • Within four days of usage for tritium users

Since the bioassay requirements for tritium is dependent on the chemical form of the labelled material, users of large quantities of H-3 (0.96 GBq or 26 mCi at a time) must consult with Radiation Protection Service to determine whether registration in the tritium bioassay program is necessary. All recorded uptakes are investigated to verify that safe work procedures are being followed and that the fume hood and experimental apparatus are working properly.

9.3.2.4 Actions Taken to Protect a Pregnant Worker

To protect the foetus, pregnant women working with radioactive materials should inform their supervisors in writing, indicating the expected date of birth. The supervisor will contact the university RPS and the following actions will be taken:

  • An RSO will contact the pregnant worker and analyse the working procedures
  • An estimate of the dose for the remaining period of the pregnancy will be performed, with special attention to the possible internal and external irradiation of the abdomen
  • If a dose above 0.4 mSv is expected, a change in procedures will be recommended
  • If a change in procedures is not possible, it will be suggested that non-radioactive work be assigned to the worker until completion of the pregnancy
  • An electronic dosimeter may be issued to the worker who decides to continue to work with radioactive materials. The electronic dosimeter allows for direct reading (at any moment) of external dose
  • An action level is established for each specific case and communicated to the worker. In the event of a reading above this action level, the worker must notify the RPS immediately

9.3.3 Procedure for Disposal of Radioactive Materials

Radioactive waste can be characterized into distinct categories (described in further detail below). All radioactive waste must be segregated and disposed of into the proper containers. All material that is determined to be contaminated should be treated and disposed of as radioactive waste.

All efforts must be made to prevent the disposal of non-radioactive waste, such as paper and packaging, into the radioactive waste stream. As part of the Environmental Protection Service group, the Radiation Service technicians provide labs with radioactive waste supplies including jars, bags, and waste tags. Any request for waste supplies should be directed to the technicians by e-mail or by phone:

  • EMAIL: hazwaste.ehs@utoronto.ca
  • TEL: (416) 978-2050
9.3.3.1 Dry / Solid Radioactive Waste
  • Dispose of materials such as contaminated gloves, filter and auto-radiography paper, gels, and lead-free radioisotope source containers into the yellow solid radioactive waste container
  • Do not dispose of counting vials or free liquids in the solid waste container
  • Place broken glass and sharps into a durable box or securely wrap before disposing into the solid waste container to prevent puncture and potential injury to the Radiation Service technicians
  • Complete the required information on the waste tag when disposing of solid waste
9.3.3.2 Liquid Waste
  • Dispose of all liquids and buffers into the appropriate liquid waste containers
  • Complete the required information on the waste tag when disposing of liquid waste
  • Liquid radioactive waste is segregated into three categories (see below) to facilitate the “decay-in-storage” of shorter-lived radioisotope species
  • Dispose of mixed radioisotope liquid waste into the container designated for the longer lived species:
9.3.3.3 Three Liquid Waste Categories / Containers

1. M9-1

for isotopes with half-life < 30 days (i.e., P-32, P-33, I-131, Cr-51)

2. M9-2

for isotopes with half-lives > 30 days but < 90 days (i.e., S-35, Fe-59, I-125)

3. M9-3

for isotopes with half-lives > 90 days (i.e., H-3, C-14, Ca-45)

9.3.3.4 Liquid Scintillation Vials
  • Collect used counting vials into a durable, leak-proof cardboard box, durable bags or lined buckets
  • Separate plastic and glass vials
  • Label with radiation tape, mark as “waste vials”, and place beside solid waste container
  • Vial waste does not need to be characterized for documentation purposes
9.3.3.5 Animal Carcasses and Bedding
  • Identify a freezer or storage bin in a designated location that can be used for the storage of animal carcasses and bedding
  • Place waste materials into durable, leak-proof plastic bags
  • Complete the required information on the waste tags and notify the radiation service technicians of the storage location
9.3.3.6 Lead Radioisotope Shipping Pots
  • Check lead shipping pots for contamination and deface radiation labels
  • Collect lead shipping pots into a durable box and label box with radiation tape – place beside solid waste container for pickup by the waste technicians
  • Clean the contaminated lead shipping pots and proceed like above
  • Lead shipping pots should be disposed of as radioactive waste only if they are contaminated and could not be cleaned
9.3.3.7 Shipping Boxes
  • Check shipping boxes and packaging for contamination and deface radiation labels
  • Dispose of non-contaminated packaging as regular waste

9.4 Laboratory Compliance Checklist

9.4.1 Signs, Labels and Housekeeping

  • Make certain that the current radioisotope permit is posted in all designated radiation laboratories
  • All benches, equipment, containers and storage areas used for radioactive materials must be labelled with radiation tape or stickers
  • CNSC rule card must also be posted, along with the radioisotope permit, in all designated labs
  • The laboratory must be kept neat and tidy. Active areas for the use of radioactive materials must be free of extraneous equipment and supplies

9.4.2 Lab Classification and Supervision

  • All locations being used for handling or storing radioactive materials must be indicated on the permit
  • All radioisotopes in storage, and in use, must be within delivery rate limits as indicated on the permit
  • Activity of isotopes handled on the bench and/or fume hood must be within laboratory designation limits
  • The permit holder or designate must be available to supervise. For any absence of more than a month, the permit holder must notify the RPS before leaving

9.4.3 Training and Knowledge

  • All staff and students must have completed the U of T Radiation Safety Course (or equivalent) before handling radioactive materials
  • Radioisotope users must demonstrate adequate knowledge of safe work practices, and have a clear understanding of all regulatory requirements

9.4.4 Security

  • Laboratories must be locked when unattended
  • Storage areas must be secured or locked when unattended

9.4.5 Food Prohibition

  • Do no eat, drink, store food or apply make-up in radioactive laboratories
  • There must be no evidence of food consumption or storage of food utensils or containers in designated radioisotope laboratories
  • There must be no disposal of food or food containers in laboratory waste receptacles

9.4.6 Inventory

  • All open sources of radioactive materials in use and in storage must have corresponding inventory records. All new orders have an inventory record automatic generated by the EHS database
  • A separate inventory form must be prepared and maintained whenever an open source is diluted, processed or separated into different products that are subsequently utilised
  • Daily usage, remaining quantities and final disposal dates must be recorded on the inventory forms
  • The Radiation Protection Service must be notified of any relocation of sealed sources or planned disposal
  • Inventory records must be kept for a minimum of three years

9.4.7 Contamination Control and Detection Criteria

  • Documented contamination surveys must be done within seven days of work with radioactive materials
  • Survey locations must be identified in contamination records and include all active benches, equipment and floors
  • The contamination survey results must be logged into the EHS database as soon as the contamination monitoring is complete
  • A copy of the contamination survey results must also be kept in shared radioisotope laboratories whenever open sources of radioisotope are used in these locations
  • Contaminated areas must be cleaned and re-monitored. Results from contamination clean-up must be recorded both before and after decontamination
  • The Radiation survey technique must be appropriate and adequate for the type of isotopes used (meets the 0.5 Bq/cm² contamination action threshold criteria)
  • Survey meters must be calibrated annually and must be in good working condition. Instruments should be given pre-operational checks before each use (e.g., checking the battery)
  • Liquid scintillation counters and well-crystal gamma counters should be routinely serviced and calibrated according to the manufacturer’s specifications
  • Count and record a blank and standard (e.g. H-3, C-14) with each set of swipes
  • Monitoring records from LSC must be kept for minimum of three years
  • Dose rates due to fixed contamination that exceeds 2.5 mSv/h (0.25 mrem/h) must be posted (post the reading, the unit and the date and time of the reading)

9.4.8 Personnel Dosimetry

  • Persons handling radioisotopes other than H-3, C-14 and S-35 of activity more than 50 MBq (1.35 mCi) must wear current reading period TLDs
  • TLDs must be stored away from any source of radiation
  • Dosimetry records are available for dosimetry wearers to view online (http://www.ehs.utoronto.ca/services/radiation/read_your_dose_record.htm)
  • TLDs must be returned to the supplier for analysis in a timely manner

9.4.9 Lab and Personnel Safety

  • Areas used for work with radioactive materials must be properly identified, contained, prepared, and sequestered whenever possible
  • Appropriate shielding must be available and used properly when needed
  • Laboratory coats, gloves and other appropriate protective equipment must be worn by radioisotope users
  • Dose rates from any source exceeding 2.5 mSv/h (0.25 mrem/h) must be posted
  • The fume hood must be functioning properly
  • Laboratory necessities must be readily available (absorbent pads, wipe test paper, decontamination solution, etc.)
9.4.9.1 Bioassays
  • Persons working with radio-iodine in quantities greater than 50 MBq (1.35 mCi) must participate in the thyroid bioassay program
  • Persons working with more than twice ALI quantities of radionuclides at a time without containment must participate in the urinalysis bioassay program (criteria is case specific)
9.4.9.2 Radioactive Waste Disposal
  • All radioactive materials must be deposited into appropriate waste containers and the required information must be recorded on the waste tags
  • Radioactive waste containers must be adequately shielded or stored in a location that minimises potential exposures to all personnel
  • Proper procedures for waste disposal must be followed at all times (i.e., sharps boxed or wrapped before being disposed of into solid waste container, liquid waste disposed of into appropriate liquid waste containers)
  • Radiation symbols on lead/plastic pots or radioisotope containers must be defaced when re-used for non-radioactive work
  • Containers re-used to store radioisotope must be re-labelled with a description of the current contents

9.4.10 Room Commissioning and Decommissioning

  • A formal written request should be sent to the RPS for the addition of a new room to the radioisotope permit
  • An RSO will visit the room, fill in the commissioning form and submit it for review by the building manager or equivalent, to ultimately be approved by the Senior Radiation Safety Officer
  • After approval, the Permit Holder will be notified and a change to the permit will be implemented before work with radioactive materials commences in the new room
  • A formal written request must also be submitted to the RPS for room decommissioning
  • An RSO will visit the room to make certain that all radioactive materials have been disposed of, confirm contamination control by swipes and direct radiation monitoring, and remove all radioactive signs
  • A room decommissioning form will then be filled out by the RSO and approved by the Radiation Safety Officer
  • After approval, the Permit Holder will be notified and a change to the permit will be implemented

9.4.11 Inventory and Leak Testing of Sealed Sources

  • A detailed inventory of all sealed sources is kept for each permit by the Permit Holder as well as by the RSO in charge of sealed sources
  • Any sealed source over 50 MBq (1.35 mCi) must be tested for leakage every year

9.4.12 Decommissioning of Devices with Radioactive Sources

  • A formal written request must be sent to the RPS
  • The RPS will arrange to remove and dispose of any radioactive source from the device
  • An RSO will conduct a contamination check of the device
  • A formal report will be sent to the Permit Holder and records of the device decommissioning will be kept in the RPS files
  • The permit will then be amended

9.4.13 Decommissioning of Instruments and Furniture used for Radioactive Work

  • A formal written request must be sent to the RPS
  • An RSO will conduct a contamination check of the object
  • A formal report will be sent to the Permit Holder and records of the decommissioning will be kept in the RPS files