Quick facts about low level waste

July 2019 (updated April 11, 2022)

The Chalk River Mound is a proposed above-ground landfill facility for more than one million tons of federally-owned “legacy” radioactive wastes. It would stand 5-7 stories high and be located on the side of a hill surrounded by wetlands, less that one kilometre from the Ottawa River.

It is often said that the Chalk River mound would “only contain low level waste”. It is incorrect to assume that this means the wastes and the mound would be innocuous and low risk. Here are some quick facts:

Low level does not mean low hazard. All categories of radioactive waste contain materials that emit ionizing radiation that can cause DNA damage, birth defects, leukaemia, cancer and chronic diseases. Low level waste is no exception to this.

Low level refers to how much protection a worker needs to handle the waste. Canada’s nuclear industry uses the terms “low”, “intermediate”, and “high” to designate short-term risks of waste handling by workers — not long-term risks of public exposure. “High-level waste” – irradiated nuclear fuel – gives off very intense heat and gamma radiation that can kill an exposed human in seconds. Such wastes must be handled remotely and workers must be shielded from the radiation. Workers must also be shielded from “intermediate-level waste” such as reactor parts, filters, resins, and solidified medical isotope waste. “Low-level waste” is a term for materials that pose risks with longer exposures, or that emit less penetrating forms of alpha and beta radiation. Alpha and beta emitters can be handled by workers without shielding but are highly dangerous if inhaled or ingested.

Many long-lived hazardous radioactive materials are destined for disposal in the mound. Radionuclides with half-lives* of up to billions of years would be disposed of in the mound. Over six metric tons of uranium-238, with a 4.5-billion-year half-life, are destined for disposal in the mound according to the environmental impact statement. More than six tonnes of Thorium-232 and significant quantities of man-made alpha emitters such as americium, neptunium, and plutonium are destined for the mound. In fact, five plutonium isotopes, including plutonium-239 with a 24,000-year half-life, are proposed for disposal. The waste inventory includes strontium-90 and cesium-137, with half-lives of around 30 years. It also includes large amounts of carbon-14, with a 5,700-year half-life. Carbon-14 is a “weak” beta emitter, but if inhaled or ingested it incorporates into human DNA and other biological molecules, where it persists for a longer period, and can cause biological damage.

Low level waste only refers to the radioactive portion of the materials destined for the mound. According to the environmental impact statement, many other toxic, hazardous and long-lived substances would go into the mound, including materials contaminated with PCBs, asbestos, arsenic, and mercury.

In many cases it may be impossible to separate low level from intermediate level waste. Canada’s legacy nuclear wastes are a complex mixture of hundreds of manmade radioactive substances created by nuclear fission. Nuclear weapons research at Chalk River generated a very wide range of wastes – far more complex than those from power reactors.  Wastes were not consistently analyzed over the years, and records prior to 1954 were lost.  Wastes were dumped in the sand, creating radioactive plumes of tritium, carbon-14 and strontium-90 that have contaminated large quantities of soil. A former AECL waste expert has warned that separating long-lived, higher-activity waste from short-lived, low-activity waste may be impossible. Shipping containers with building demolition debris from the Chalk River and Whiteshell Laboratories are being stacked near the mound site.  If the mound proposal is approved, these would be driven into the mound area and covered with contaminated soil. 

The mound would not contain and isolate waste. The Chalk River mound would fail to meet international safety standards that require that radioactive waste be kept out of the biosphere for the duration of its radiological hazard. Putting long-lived radioactive wastes on the surface increases risks of accidents and leaks during disposal operations and extreme weather events such as downbursts, tornadoes and extreme rainfall. Long-lived wastes would permanently contaminate the Ottawa River and expose large numbers of people to low levels of radiation over millennia. International safety standards require that these wastes be stored underground. Properly managing these wastes by packaging them, labelling and storing them underground in stable rock away from drinking water sources would create many long term well-paying jobs and establish Canadian leadership to deal with the global radioactive waste problem.

* The “half life” of a radionuclide is the period of time required for half of its atoms to disintegrate (explode) giving off harmful “atomic radiation”.  If you multiply the half-life by 10, that’s how long it takes for the amount of the radionuclide to be reduced by a factor of a thousand. 

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