Repository engineering demonstration success for NWMO

The NWMO is responsible for designing and implementing Canada's plan for the safe, long-term management of used nuclear fuel. Used fuel will ultimately be placed in a deep geological repository about 500 metres underground. Inside the natural shield of the solid bedrock, a series of five engineered and natural barriers will be used to contain and isolate the material. These barriers include fuel containers made of thick carbon steel, coated with corrosion-resistant copper, which are placed inside "buffer boxes" of compressed bentonite clay. The buffer boxes provide additional protection against corrosion or degradation: bentonite is an effective barrier to both water flow and microbial growth.

NWMO's technical specialists and engineering partners designed and fabricated specialised prototype equipment and components for the demonstration. A life-size model of an underground storage room was built at NWMO's proof test facility in Oakville, Ontario, with exact dimensions and interior walls lined with simulated rock tiling.

During the demonstration, used fuel containers were encased in buffer boxes which were then lifted and precisely placed into the storage room after which all the remaining space from floor to ceiling was filled with loose granular bentonite. The room was then methodically emptied to evaluate the installation of the engineered-barrier system. In-depth analysis is now underway to assess the results and yield insights that will support the ongoing design and planning of the deep geological repository, NWMO said.

"All elements of the demonstration performed as expected and according to plan," said NWMO Vice-President and Chief Engineer Chris Boyle, who added that the demonstration - and the prototype equipment used to achieve it - was the result of "made-in-Canada" innovation and collaboration.

Two areas are currently being studied as possible hosts for Canada's geologic repository, having been narrowed down from a list of 22 interested communities through a process launched by NWMO in 2010 to identify a preferred site with informed and willing hosts. These are the Wabigoon Lake Ojibway Nation-Ignace area in north-western Ontario and the Saugeen Ojibway Nation-South Bruce area in southern Ontario. Once a preferred site with informed and willing hosts is identified - which NWMO expects to happen in 2023 - the project will be subject to a rigorous licensing and regulatory decision-making process before construction begins.