Re “CNL working to accomplish responsible action in managing Canada’s nuclear research and development legacy,” (The Hill Times, letters to the editor, Dec. 14, 2020). The letter from Joe McBrearty, president and CEO of Canadian Nuclear Laboratories (CNL), deepens my concern about the handling of Canada’s $8-billion nuclear waste liability. Mr. McBrearty says the Chalk River Mound beside the Ottawa River, 150 km north of Ottawa-Gatineau, "will contain only low-level radioactive waste which contains radionuclides that require isolation and containment for only a few hundred years.” Unfortunately, this claim does not stand up to scrutiny. Last month, the CNL published its final environmental impact statement listing a partial inventory of radionuclides that would go into the gigantic five-to-seven storey radioactive mound (a.k.a. the “NSDF”). Twenty-five out of the 30 radionuclides listed in the inventory are long-lived, with half-lives ranging from four centuries to more than four billion years. To take just one example, the man-made radionuclide, Neptunium-237, has a half-life of two million years such that, after two million years have elapsed, half of the material will still be radioactive. The inventory includes four isotopes of plutonium, one of the most deadly radioactive materials known, if inhaled or ingested. It is incorrect to say that these materials “require isolation and containment for only a few hundred years.” Many of them will be dangerously radioactive for more than 100,000 years. The International Atomic Energy Agency states that materials like this must be stored tens of meters or more underground, not in an above-ground mound. The CNL inventory also includes a very large quantity of cobalt-60, a material that gives off so much strong gamma radiation that lead shielding must be used by workers who handle it in order to avoid dangerous radiation exposures. The International Atomic Energy Agency considers high-activity cobalt-60 sources to be “intermediate-level waste” and specifies that they must be stored underground. The addition of high-activity cobalt-60 sources means that hundreds of tons of lead shielding would be disposed of in the mound along with other hazardous materials, such as arsenic, asbestos, PCBs, dioxins and mercury. CNL’s environmental impact statement describes several ways that radioactive materials would leak into surrounding wetlands that drain into the Ottawa River, during filling of the mound and after completion. It also describes CNL’s intent to pipe water polluted with tritium and other radioactive and hazardous substances from the waste treatment facility directly into Perch Lake which drains into the Ottawa River. I stand by my original conclusion: we need parliamentarians to step up now to stop this deeply flawed project and prevent the Ottawa River from being permanently contaminated by a gigantic, leaking radioactive landfill that would do little to reduce Canada’s $8-billion nuclear waste liability. Lynn Jones Ottawa, Ont.