Sealed Source Tracking


Introduction

Possession and movement of high-risk radioactive sealed sources are regulated by the Canadian Nuclear Safety Commission (CNSC).

CNSC manages Canada's national inventory of high-risk radioactive sealed sources. The National Sealed Source Registry (NSSR) helps CNSC track the locations of all high-risk radioactive sealed sources in Canada and increases the security and safety of those sources.

The Sealed Source Tracking System (SSTS) is an electronic add-on to the NSSR that provides licensees with a more convenient and efficient way to report any movement of sealed sources.

What is a sealed source?

A radioactive sealed source is defined in CNSC Nuclear Substances and Radiation Devices Regulations as:

“a radioactive nuclear substance in a sealed capsule or in a cover to which the substance is bonded, where the capsule or cover is strong enough to prevent contact with or the dispersion of the substance under the conditions for which the capsule or cover is designed”.

What are the categories of sealed sources?

In 2005, the International Atomic Energy Agency (IAEA) published a risk-based ranking of radioactive sources and practices, which uses five categories1. The category assigned to each practice or radioactive nuclear substance (enclosed in the sealed source) takes into account factors such as the following:

  1. The radiological risk associated with the source
  2. The nature of the work (or application for which the source is used)
  3. The mobility of the source
  4. The experience from reported accidents
  5. Typical versus unique activities within an application

These factors were used to assign sources and practices to one of five categories. If not managed safely and securely, Category 1 sources are considered to pose the greatest risk to human health, while Category 5 sources pose the lowest risk2.

1 IAEA, Categorization of Radioactive Sources, Safety Guide RS-G-1.9 (2005).
2 IAEA, Categorization of Radioactive Sources, Safety Guide RS-G-1.9 (2005), Table 3.

A.1 Category 1 (very high risk)

Category 1 sources are classified as "personally extremely dangerous".

These sealed sources, if not safely managed or securely protected, would be likely to cause permanent injury (in some cases fatal) to a person handling or coming in contact with them for a period of a few minutes. Exposure would be fatal if a person were close to it in an unshielded manner for a few minutes to an hour. Category 1 sources are associated with licensed activities to which the CNSC’s Class II Nuclear Facilities and Prescribed Equipment Regulations apply.

Examples of Category 1 source usage:
  • Self-shielded irradiators: Gamma sources are used in these irradiators for experimental purposes or as a means of sterilization. Gamma irradiation kills bacteria by breaking down bacterial DNA and inhibiting cell division. Blood products, for example, are sterilized in self shielded irradiators.
    Cobalt-60 Gammacell

    Image 1: Cobalt-60 Gammacell

  • Gamma knife radiosurgery: An advanced form of surgery, performed with highly focused beams of radiation. As many as 201 radioactive sealed sources create intersecting beams of gamma radiation, which deliver a concentrated dose of radiation to a precise area of the brain. These radiation beams form the "knife".
    Elekta Gamma Knife

    Image 2: Elekta Gamma Knife

    Gamma Knife in use

    Image 3: Gamma Knife in use

  • Radioactive source teletherapy: External beam radiotherapy (otherwise known as "teletherapy") is the most frequently used form of radiotherapy. Radiotherapy is the medical use of radiation (produced by a radioactive sealed source mounted inside the machine) as part of cancer treatment or to control malignant cells.
    Co-60 Teletherapy

    Image 4: Co-60 Teletherapy

A.2 Category 2 (high risk)

Category 2 sources are classified as "personally very dangerous".

These sealed sources, if not safely managed or securely protected, could cause permanent injury to a person handling it, or coming in contact with them, for a short period of time (minutes to hours), or be fatal if close to it in an unshielded manner for a few days. Category 2 sources are associated with licensed activities to which the CNSC’s Nuclear Substances and Radiation Devices Regulations generally apply.

Example of Category 2 source usage
  • Industrial radiography is a non-destructive testing (NDT) application that uses gamma radiation from a highly radioactive source, and photographic film, for the detection of internal physical imperfections (such as voids, cracks, flaws, segregations, pores and inclusions) in pressure vessels, pipelines, ships and reactor components. Radiography produces images on photographic film, similar to X-ray images, which show varying densities according to the amount of radiation absorbed in the material.
    Industrial radiography camera

    Image 5: Industrial radiography camera which contains the radioactive sealed source

    NDT pipeline inspection

    Image 6: NDT pipeline inspection, using industrial radiography equipment

A.3 Category 3 (moderate risk)

Category 3 sources are classified as "personally dangerous".

These sealed sources, if not safely managed or securely protected, could cause permanent injury to a person either handling them, or otherwise coming in contact with them, for some hours. Although unlikely, it could be fatal to be close to this amount of unshielded radioactive nuclear substances for a period of days to weeks. Category 3 sources are associated with licensed activities to which the CNSC’s Nuclear Substances and Radiation Devices Regulations apply.

Examples of Category 3 source usage:
  • Industrial gauges: These gauges are usually installed in fixed positions for measuring and process control purposes. These include density gauges, level gauges, belt mass meters, and thickness gauges. The radioactive sealed source is mounted inside the gauge and projects a radiation beam, through the material, and is picked up by a detector to provide a measurement.
    Industrial fixed gauge

    Image 7: Industrial fixed gauge

  • Brachytherapy delivers a concentrated dose of radiation to cancerous tissue from within. High dose rate (HDR) brachytherapy is the placement of a small, highly radioactive sealed source, for a short period of time, directly into cancerous tissues. The procedure is sometimes guided by ultrasound or 3D computerized mapping techniques.
    HDR Brachytherapy

    Image 8: HDR Brachytherapy

A.4 Category 4 (low risk)

Category 4 sources are classified as "unlikely to be personally dangerous".

It is very unlikely that anyone would be permanently injured by these sealed sources. However, if this unshielded radioactive nuclear substance is not safely managed or securely protected, although unlikely, it could temporarily injure someone handling it, in contact with it, or who is close to it for several weeks. Category 4 sources are associated with licensed activities to which the CNSC’s Nuclear Substances and Radiation Devices Regulations apply.

Example of Category 4 source usage

Low dose rate industrial gauges, such as moisture and density gauges, are used to measure the density of asphalt, soil, aggregate or concrete, as well as the moisture content of soil or aggregate.

Portable gauge

Image 9: Portable gauge

Portable gauge in use

Image 10: Portable gauge in use

A.5 Category 5 (very low risk)

Category 5 sources are classified as "most unlikely to be personally dangerous".

No one could be permanently injured by this radioactive nuclear substance. Category 5 sources are associated with licensed activities to which the CNSC’s Nuclear Substances and Radiation Devices Regulations apply.

Examples of Category 5 source usage:
  • Nickel-63 sources, in electron capture detectors, are used in gas chromatography instruments. They detect minute amounts of chemical compounds, such as halogenated organic chemicals in environmental samples. Pesticide levels in foodstuffs, for example, are measured with these detectors.
    Nickel-63 sealed source used in electron capture detectors

    Image 11: Nickel-63 sealed source used in electron capture detectors

  • Low dose rate (LDR) brachytherapy involves exposure to small radioactive sealed sources for a few hours or days. Ocular melanoma is one example of a tumour that can be treated with LDR brachytherapy. In another example, radioactive seeds of iodine-125 are surgically implanted to treat prostate cancer.
    Low dose rate brachytherapy

    Image 12: Low dose rate brachytherapy

Why it's important to track sealed sources

High-risk sealed sources contain potentially dangerous radioactive material. If these sealed sources are misused, misplaced or abandoned, injuries and fatalities can occur.

Closely monitoring the movement of sealed sources through a national registry complies with the International Atomic Energy Agency's (IAEA) Code of Conduct on the Safety and Security of Radioactive Sources. This Code aims to enhance the safety and security of radioactive sources internationally.

Our online Sealed Source Tracking System (SSTS) is the first of its kind. Just one of the reasons Canada is a world leader in nuclear safety.

What does the Sealed Source Tracking System do?

The SSTS keeps track of movements of radioactive sealed sources from one location to another - using the Internet.

Licensees can now report the following activities online:

  • Receipt
  • Transfer
  • Import
  • Export

What is needed to use the Sealed Source Tracking System?

Only CNSC licensees who are authorized to possess high-risk sealed sources can use this system. These licensees must obtain an authorization code from their CNSC licensing officer.

Licensees using the system are required to provide:

  • The date of transaction
  • Serial number of source
  • Where the source is coming from - CNSC licence number (if applicable) and address
  • Where the source is going - CNSC licence number (if applicable) and address
  • Model name/serial number of prescribed equipment (such as radiography camera, irradiator, teletherapy machine)
  • Model/name of source assembly (in the case of radiography camera)

Transfers and exports must be reported at least 7 days before the actual shipment takes place.

Receipts and imports must be reported within 48 hours of reception.

What are the benefits of the Sealed Source Tracking System?

  • Alerts the shipper if the recipient is not licensed by CNSC
  • Alerts the shipper if the receiving location is not authorized
  • Helps CNSC to monitor the possession and movement of sealed sources, and prevent any unauthorized possession of sources which could harm Canadians
  • It's quick, easy and convenient