Modelling
Modelling is necessary to make predictions of the performance of a deep geological repository over the many millennia during which contained radionuclides remain harmful to humans and the environment. Whether performance be measured in terms of risk (ecological or human health) or in terms of mass flux of radionuclides passing a point of regulatory compliance, numerical modelling of complex physical and chemical processes is required. Some of the many processes that must be considered include the interaction of the formation water with the repository following closure of the facility, generation of heat by radionuclide decay, release of radionuclides from emplaced canisters into low-permeability backfill, migration of radionuclides by diffusion and as solute within flowing groundwater, fluid and solute interaction between the rock matrix and fractures contained within it, and the physical effects of earthquakes and glaciation.
Because of the long time frame over which model predictions are required, the complexity of the processes being modelling, and important safety implications of the work, modelling must be conducted with great rigour, and with due consideration of uncertainty (i.e. in future events, and in the true interaction between processes). To the latter end, models are often constructed within a probabilistic framework, such that the results of multiple simulations are presented in terms of probability distributions, for use in risk assessment.
From our early history as the developers of the first groundwater code to couple density- and viscosity-dependent flow, energy transport, and contaminant transport in three dimensions (see our history) to the present day, Intera has experience in all aspects of this type of modelling. Supported by our in house software, we use all manner of models including TOUGH2, SWIFT, FRAC3DVS, and MODFLOW, and have worked on projects around the world.
Intera’s recent experience in modeling involves detailed numeric modelling in support of the Postclosure Safety Assessment for Ontario Power Generation’s Deep Geologic Repository, proposed for the long-term storage of low and intermediate level nuclear waste at a depth of 680 metres near Kincardine, Ontario. Fully saturated groundwater flow and transport modeling of a single radionuclide (Cl-36) from the facility through the intact rock and the excavation disturbed zone (EDZ) surrounding facility shafts was performed using FRAC3DVS. Two-phase gas transport modeling was used to assess the impact of gases generated by waste corrosion and decomposition. In this case, an analytic gas generation model (GGM) was coupled to the TOUGH2 numeric model to predict repository pressures and the flow of free-phase and dissolved gas from the facility and through the intact rocks and EDZ.
Other modelling projects in support of radioactive waste management initiatives include:
- Scoping Level Modeling of Radionuclide Transport from the Proposed Deep Geological Repository at the Bruce Site, for Ontario Power Generation (OPG)
- Analysis of Large Scale Gas Injection Test, for Nuclear Waste Management Organization (NWMO)
- Glaciation Scenario: Groundwater and Radionuclide Transport Studies at a Hypothetical Repository Site, for NWMO
- Modeling of Radionuclide Transport from a Hypothetical Deep Geological Repository, for OPG
- Effects of Vault Geometry on Contaminant Transport, for OPG
- Review of Radionuclide Screening Model and Safety Assessment Scoping Model for a Used Fuel Disposal Facility, for OPG
- Groundwater Flow and Contaminant Transport Modelling at the Port Granby WMF, for Low-Level Radioactive Waste Management Office of Atomic Energy Canada Limited
- Probabilistic Modeling of Radionuclide Release from a Geologic Repository for Nuclear Fuel Wastes
- Preliminary Performance Assessment of Proposed Low-Level Radioactive Waste Management Facilities, for Ministerial Siting Task Force of Natural Resources Canada
- Demonstration of M3 Modelling for Cigar Lake Hydrogeochemical Data, for Canadian Nuclear Safety Commission
- Drilling Impact Study (DIS): Evaluation of the Influences of Drilling on Groundwater Quality, for SKB – Swedish Nuclear Fuel and Waste Management Co.
- Hydrogeologic and Heat Transport Simulations for a Nuclear Waste Repository
- Simulation of the Hydrogeologic Impact of an Underground Research Laboratory in Crystalline Rock, for Canadian Nuclear Fuel Waste Management Program
Intera News & Updates
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22/03/2010 Intera wins 3-year contract for gas transport modelling of the Lasgit Experiment (Large Scale Gas Injection Test).
12/02/2010
3 years and 5000 metres later: drilling at DGR is now complete.
25/02/2010
Dr. Robert Walsh provides mView and TOUGH2 training to Nippon-Koei Research Division in Tsukuba-shi, Japan.
28/01/2010
New Website released.
