Frequently Asked Questions: Tritium Releases and Dose Consequences in Canada in 2006

Q1. What is the purpose and scope of this report?
Q2. How was the study conducted?
Q3. What does the study conclude?
Q4. What are the acceptable dose limits of tritium in Canada?
Q5. Are any of the tritium levels reported in this study higher than the acceptable public dose limits for tritium in Canada?
Q6. Why are the levels of tritium in groundwater high at some of the facilities?
Q7. Is there a health risk related to the levels of tritium groundwater?

Q1. What is the purpose and scope of this report?

A1. The Tritium Releases and Dose Consequences in Canada in 2006 report is one of a series of research studies being produced by the Canadian Nuclear Safety Commission (CNSC) under its Tritium Studies Project.  The goal of the research is to expand the body of knowledge on tritium and to further enhance regulatory oversight of tritium-related activities in Canada.

This report provides information on:

• tritium production and use
• tritium releases to the environment during 2006 from CNSC licensed facilities
• levels of tritium measured in the soil, water, air and vegetation around CNSC licensed facilities releasing tritium to the environment
• estimated tritium doses to members of the public and workers resulting from releases in 2006

Q2. How was the study conducted?

A2. The information in this report was compiled from the 2006 annual compliance and environmental monitoring reports submitted to the CNSC by licensees of major facilities.  These licensed facilities included CANDU nuclear reactors, research reactors, nuclear waste management facilities, tritium processing facilities, research facilities, and chemical laboratories.

Q3. What does the study conclude?

A3. The study reports that:

• releases of tritium from nuclear facilities in 2006 were a small fraction of the regulatory limits
• doses to workers or members of the public living near nuclear facilities were a fraction of the CNSC dose limits
• concentrations of tritium in drinking water sources around nuclear facilities were all below the Canadian drinking water quality guideline of 7,000 becquerels per litre (Bq/l)
• elevated levels of tritium in groundwater do not contribute to the radiation dose of workers or the public

Based on these results, the CNSC concludes that 2006 tritium releases from CANDU nuclear reactors, research reactors, nuclear waste management facilities, tritium processing facilities, research facilities, and chemical laboratories were effectively controlled to prevent risk from tritium exposure to the health of the public, nuclear workers, and the environment.

Q4. What are the acceptable dose limits of tritium in Canada?

A4. The CNSC regulates nuclear facilities to protect health and the environment, and specifies dose limits from exposure to all sources of radiation from CNSC licensed activities, including tritium. Most countries with technologies similar to those in Canada have the same radiation dose limits as Canada for workers and members of the public

• For the general public, the Canadian dose limit is 1 milliSievert (mSv) per year.
• For nuclear energy workers, the Canadian dose limit is 50 mSv per year and 100 mSv over 5 years.  

Q5. Are any of the tritium levels reported in this study higher than the acceptable public dose limits for tritium in Canada?

A5. No. Releases of tritium to the environment in 2006 by CNSC licensed facilities resulted in doses to members of the public that were well below the public dose limit of 1 mSv per year.

Q6. Why are the levels of tritium in groundwater high at some of the facilities?

A6. Licensees are not permitted to discharge tritium directly to groundwater. Elevated tritium levels in groundwaters are due to historical malfunctions and practices, or the washout of stack emissions. This past contamination is being addressed by licensees as required by the CNSC.

Q7. Is there a health risk related to the levels of tritium groundwater?

A7. No. Current groundwater contamination does not pose a health risk to workers or the public because the groundwater found in contaminated areas is not used as a source of drinking water. To put it in perspective, tritium levels in public drinking water supplies near licensed facilities for the year 2006 were typically less than 20 Bq/l, which represents a very small fraction of the Canadian Drinking Water Quality Guideline of 7,000 Bq/l.  Over time, the tritium levels will diminish through natural processes.