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Safety Assessment
The safety of the DGR during the operational phase (preclosure) and over the long-term (postclosure), after operations have ceased and the facility has been decommissioned, was studied. These technical studies contribute to the Environmental Impact Statement and the Preliminary Safety Report submissions supporting the site preparation/construction licence application. Canadian and international guidelines were followed in the safety assessments.
These safety assessments were conducted in an iterative manner, as more detailed site characterization and facility design information became available and in turn providing feedback to the design. The safety studies will continue, incorporating information learned during construction, and would be presented as part of a future operating licence application before any wastes would actually be emplaced.
Conclusions from the preliminary safety assessment work include:
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The facility can be constructed and operated safely.
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The host rock is effective in providing long-term isolation and containment.
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The majority of radioactivity will decay in and around the repository.
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The potential dose to a person assumed to be living on top of the repository would likely be negligible, much less than 0.1 microSieverts per year.
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This is well below the public dose limit, and the natural background radiation dose rate. (The Sievert is a unit of measure used to describe the effective dose of ionizing radiation received by people. Dose is often expressed in millionths of a Sievert, or microSievert. The natural background dose rate is about 2,000 microSieverts).
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Future scenarios considered in the safety assessment include: earthquakes, glaciation, human intrusion into repository, failure of the shaft seal, failure of the borehole seals, and a vertical fault near the repository.
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Even under extreme assumptions about future scenarios, the impacts on people living around the repository site (i.e. around the current Bruce nuclear site) would be at or below the natural background radiation dose rate.
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