Why a deep geological repository?

In 2002, the Government of Canada asked the NWMO to study possible approaches for the long-term management of Canada's used nuclear fuel. The study focused on three approaches identified by the government — deep geological disposal, storage at nuclear reactor sites and above-ground centralized storage — as well as a number of other approaches.

Recommending an approach

In November 2005, we submitted our final report to the Minister of Natural Resources, recommending an approach known as Adaptive Phased Management (APM). The technical end point of APM is the containment and isolation of Canada's used fuel in a deep geological repository. The approach was adopted as Canada’s plan in June 2007.


Being responsible to the needs of future generations

The options study clearly identified the deep geological repository as the appropriate approach. A deep geological repository uses a combination of engineered and natural barriers to safely contain and isolate used fuel. It can be actively managed and monitored for as long as society wishes to do so. It can also be sealed at a future date, when the community, the NWMO and regulators agree that it is appropriate to do so. The repository would then be passively safe, meaning it would not rely upon human institutions and active management in order to contain and isolate used fuel over the long term. This responsive and prudent approach is consistent with what Canadians said is required to ensure safe management of the used fuel for tens of thousands of years.
NWMO president and CEO, Laurie Swami (right), signing a co-operation agreement with SKB in Toronto on May 14, 2018

International best practices

Canada’s use of a deep geological repository is consistent with international best practices. This approach is the culmination of more than 30 years of research, development and demonstration of technologies and techniques.

There is also consensus among major nuclear regulatory and monitoring organizations that deep geological repositories are the responsible way forward.
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Additional background on the deep geological repository approach 

  • A geological repository uses multiple barriers that include the waste form, container, sealing materials and the host rock. The system is designed such that the failure of one component would not jeopardize the safety of the containment system as a whole.
  • The host rock would be stable and predictable over long periods of time.
  • The low permeable host rock would ensure that the waters in the deep rock are isolated and do not mix with surface waters.
  • The deep geological repository system would maintain a chemical and hydrological environment that is favourable to the stability and performance of the repository.
  • Natural analogues provide evidence that engineered-barrier system components are stable for very long periods under similar deep geologic conditions.
  • The depth of the repository would be such that future inadvertent human intrusion into the closed repository would be very unlikely.
  • International progress on repository implementation gives assurance that geological disposal is a sound technical solution and provides practical experience.
  • Safety assessment case studies indicate that any impacts are likely to be well below recommended dose constraints and natural background dose rates.
  • A geological repository can be built and operated safely using proven technologies.
  • The radionuclides in the used fuel decay with time.
  • The repository site can be monitored to confirm repository system performance.

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An icon of a shield

Canada's plan

Multiple-barrier system
An icon of a shield


Canada's deep geological repository