Ontario Power Generation's Response to the Joint Review

Attachment 1 to OPG letter, Albert Sweetnam to Dr. Stella Swanson, “Deep Geologic Repository Project for Low and Intermediate Level Waste – Submission of
Responses to the Final Sub-set of Package #4 Information Requests”, CD#: 00216-CORR-00531-00143.
IR# EIS Guidelines
Section
Information Request and Response
For the NE-GG1 (increased gas generation in the repository) and NE-GT5 (as NE-GG1 but also with increased
permeability and reduced gas entry pressures for shaft seal materials) cases, enhanced gas generation causes
repository pressures to increase rapidly, which in turn initiates gas flow up the shaft. This prevents complete
resaturation of the shaft sealing materials below the Guelph Formation. However, as shown in Figure 2, the shaft
materials above the Guelph Formation still resaturate quickly because of their proximity to more permeable rock and
would isolate the biosphere from repository sourced gas.
Figure 2: 2D Shaft Model Results for Bentonite-Sand Shaft Material Saturation at Selected
Formations
The gas flows in the shafts calculated by T2GGM are imported directly into the AMBER safety assessment model (see
Appendix J.4.3 of QUINTESSA 2011). A range of calculation cases with differing assumptions as to the performance
and resaturation rates of the shaft have been evaluated in AMBER for the Normal Evolution Scenario. These are
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