Canada demonstrates engineered barrier system for SNF disposal

June 9, 2022, 7:00AMRadwaste Solutions
A modified forklift with a customized handling attachment is used to move spent fuel containers and their heavy bentonite clay housings. It can move autonomously or be manually operated remotely from outside the room, as needed. (Photo: NWMO)

Canada’s Nuclear Waste Management Organization (NWMO) has announced that it has successfully completed a full-scale demonstration of the engineered barriers that are designed to contain and isolate Canada’s spent nuclear fuel in a deep geological repository.

Responsible for the long-term management of Canada’s spent nuclear fuel, the NWMO said the demonstration was the culmination of more than eight years of preparation, including the design and fabrication of specialized prototype equipment and components by the organization’s technical specialists and engineering partners.

“All elements of the demonstration performed as expected and according to plan,” said Chris Boyle, vice president and chief engineer at the NWMO. “The demonstration shows not only the NWMO’s ability to install the engineered-barrier system, but also the caliber of our technical teams, who are invested in the project’s success and committed to doing what’s right for Canadians and Indigenous peoples.”

The repository: The NWMO is currently in the process of selecting a site to construct a geologic repository in solid rock 500 meters (1,640 feet) underground. The repository design will use a series of five engineered and natural barriers to isolate the spent fuel.

Beginning with 22 interested communities, the NWMO has, after numerous technical studies and extensive local engagement, narrowed its search to two potential host areas: the Wabigoon Lake Ojibway Nation–Ignace area in northwestern Ontario and the Saugeen Ojibway Nation–South Bruce area in southern Ontario.

The demonstration: As part of the demonstration, the NWMO built a life-size model of one of the repository’s underground storage rooms at its proof test facility in Oakville, Ontario, with the exact dimensions and interior walls lined with simulated rock tiling. Over several days, customized heavy machinery moved containers designed for spent fuel into the room and filled the remaining space with protective material that will ensure that the containers retain their strength and durability for many thousands of years.

During the process, spent fuel containers made of thick carbon steel and coated with corrosion-resistant copper were encased in protective layers, called buffer boxes. Made of compressed bentonite clay, the boxes provide additional protection against corrosion or degradation.

Once assembled, each spent fuel container in its buffer box weighs 8,000 kilograms (17,637 pounds)—heavier than a large elephant. One by one, containers were lifted and precisely placed into the storage room. Later, all the remaining space from floor to ceiling was filled with loose granular bentonite.

After the demonstration was completed, the room was methodically emptied to carefully evaluate the installation of the engineered-barrier system. The NWMO said that an 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.

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