The work was undertaken on behalf of Canada's Nuclear Waste Management Organization, which assisted Ontario Power Generation in seeking regulatory approval for DGR construction. The suite of postclosure safety assessment documents totalling around 2,500 pages represent the culmination of more than four years' work by a team of over 20 consultants. The impacts associated with a Normal Evolution Scenario and four Disruptive Scenarios were evaluated using the AMBER code.
The assessment modelling was supported by the FRAC3DVS-OPG and T2GGM codes for detailed groundwater and gas calculations. T2GGM is a TOUGH2 based gas and water transport code with a coupled Gas Generation Model (GGM). It has been used to calculate the generation and build up of gas in the repository due to the corrosion and microbial degradation of the metallic and organic wastes present and the two-phase exchange of gas and groundwater between the repository and the surrounding rock and between the rock and the surface environments.
The post-closure safety assessment forms part of the supporting documentation for the DGR's Environmental Impact Statement and Preliminary Safety Report, which were submitted for regulatory review in April 2011. The submission was necessary to secure an approved environmental assessment and a site preparation and construction licence.
In January 2012, a Joint Review Panel was appointed by the federal Minister of the Environment and the President of the Canadian Nuclear Safety Commission and mandated to assess the environmental effects of the DGR project and to obtain the information required for the consideration of the Licence to Prepare a Site and Construct the project.
In May 2015, the Panel submitted its Environmental Assessment Report to the Canadian federal government recommending the approval of DGR project. It contains the conclusions, rationale and recommendations on the safety of the DGR and its ability to safely protect the environment and the public. The Report has been presented to the federal Minister of the Environment who will consider the recommendations and make a decision.
(Image courtesy of the Nuclear Waste Management Organization and Ontario Power Generation - Artist's Rendition of the Deep Geologic Repository)