The deep geological repository is a network of underground tunnels and placement rooms for used nuclear fuel containers. It is designed to safely contain and isolate Canada's used nuclear fuel over the long term.

The repository will be constructed at a depth of about 500 metres below the ground's surface, depending on rock characteristics at the site. To construct the deep geological repository, rock excavation would primarily be done using a method that involves controlled drilling and blasting. Rock boring technology may also be used depending on the final design and site conditions.

A conceptual layout for a repository would require an underground footprint of about two kilometres by three kilometres (about 600 hectares or 1,480 acres). The actual underground footprint at any particular site would depend on a number of factors, including the characteristics of the rock, the location of underground features in the rock, the final design of the repository and the total inventory of used fuel to be managed. The repository will also include areas for offices, maintenance facilities, services, monitoring and testing.
This conceptual diagram shows a deep geological repository, including facilities on the surface, a main shaft complex leading to underground placement rooms and a ventilation exhaust shaft.

The repository design uses a multiple-barrier system. A series of engineered and natural barriers work together to contain and isolate used nuclear fuel from people and the environment.

The final layout of the repository will depend on a number of factors, including characteristics of the chosen site, final design of the barrier system, final safety considerations, and inventory of used fuel to be managed.

Monitoring

There will be an extensive environmental and operational monitoring program for ground and surface water, radiation, air quality, fire and more. This monitoring will start prior to construction and will continue through operations. There will also be an extended monitoring period following placement of the used nuclear fuel.