The Nuclear Waste Management Organization (NWMO) has now published its Confidence in Safety reports for each of the two potential sites being considered to host a deep geological repository to store Canada’s used nuclear fuel.
In a media release, the not-for-profit organization responsible for finding a suitable location to construct and operate a deep geological repository to house Canada’s spent radioactive fuel rods said years of research and fieldwork have resulted in the organization’s confidence a DGR could be safely supported at either site.
“The Confidence in Safety reports outline the basis for the NWMO’s confidence that a deep geological repository can be constructed at either potential site, to safely and responsibly manage Canada’s used nuclear fuel for the very long term,” said Dr. Paul Gierszewski, director of safety and technical research at the NWMO, in a release. “Our work in Canada is grounded in decades of international research and scientific consensus that deep geological repositories represent the best solution for the safe, long-term management of used nuclear fuel.”
In 2010, the NWMO launched its site-selection process with 22 communities expressing interest in learning more about the project and their potential as hosts. Following several years of technical assessments and community engagements, two potential sites remain in the process – one in the Wabigoon Lake Ojibway Nation-Ignace area in northwestern Ontario and the other in the Saugeen Ojibway Nation-South Bruce area in southern Ontario.
The NWMO has said it intends to make a final site selection decision in 2023, and will only choose a site with a willing host community.
The community of South Bruce is set to hold a referendum sometime following this year’s municipal election to determine willingness among its citizens. The Saugeen Ojibway Nation will also have to express its willingness for the project to move forward, the NWMO has said.
The proposed DGR is Canada’s plan to store decades worth of spent nuclear waste. That waste is currently stored above ground – after cooling in pools at reactor sites for 10 or so years – in reinforced high-density concrete containers managed at facilities licensed for interim storage.
The NWMO is proposing to dig 500-plus metres underground at one of the two sites to build the DGR, and have it surrounded by “a natural shield of rock”. The DGR design uses additional engineered barriers to ensure the facility’s safety for many thousands of years, the release said.
The NWMO said their confidence in the safety of each site is built on an understanding of several “broad factors” including the characteristics of the geology and long-term stability of the rock and surrounding area, to the strength of the multiple-barrier system and the sites’ capabilities to support the safe construction, operation and closure of the repository.
The NWMO said both remaining potential sites share common features that support the overall safety of the project. According to the NWMO, the sites are located in stable, seismically quiet settings, with rock formations of the necessary depth, breadth and volume to isolate the repository.
Neither site has known economically exploitable resources within the rock (e.g., minerals, salt, gas), reducing the risk of human intrusion into the repository in the future, the NWMO said.
“Safety is our highest priority. It drives everything we do, from project design, engineering and environmental research to interweaving Indigenous Knowledge into our work and engaging with communities,” said Laurie Swami, NWMO President and CEO in a release. “These reports are the products of years of careful study by our science and engineering teams. They mark a major achievement in the site selection process that launched more than a decade ago.”
After a site is selected, and if the community has opted into the project, further technical studies will be undertaken with a 10-year timeline to the start of construction and a further 10 years to build the DGR and associated facilities. The operation of the DGR is expected to begin in 2043.
“The safety of a proposed site will be confirmed through a rigorous regulatory review of the repository design and safety case, including through the federal Impact Assessment Act process and licensing by the Canadian Nuclear Safety Commission. The regulatory and licensing process is expected to take approximately 10 years to complete,” the release said.
The Confidence in Safety reports may be read in full at www.nwmo.ca.
An overview of the 87-page report for the South Bruce site mentions the preferred host rock is the 360-485 million-year-old Cobourg Formation at about 650-metres deep, which is overlain by 200-metres of confining low-permeability shale formations.
There are no “active geological features” (e.g. faults) identified below the South Bruch site to date with two boreholes drilled, which is an indication of site stability. The report also mentions there is no appreciably flowing groundwater measured below 325-metres in depth in the two boreholes to date at the South Bruce site.
The report notes there is high confidence the regional infrastructure can support the construction, operation and closure of the repository and used fuel can be safely transported to the site using an all-road or road and rail combination transportation system.
“More site characterization is required, and is planned should the site be selected. However, the uncertainties that remain are less about the fundamental suitability of the bedrock to safely contain and isolate used nuclear fuel, and more about developing and documenting a thorough quantitative understanding of the site,” the report reads.