Flow reduction due to degassing and redissolution phenomena
- Lawrence Berkeley Laboratory, Berkeley, CA (United States)
At the Stripa mine in Sweden, flow and transport experiments in a water-saturated fractured granite were conducted to investigate techniques for site characterization for a geologic nuclear waste repository. In the Simulated Drift Experiment, measured water inflow to an excavated drift with pressure held at 1 bar was only 1/9th the value expected based on inflow to boreholes with pressure held at 2.7 bars. Several physical and chemical mechanisms were hypothesized to be responsible for this reduction in flow. One possibility is that significant degassing of dissolved nitrogen takes place between 2.7 and 1 bars, credating a two-phase regime with an accompanying decrease in fluid mobility, resulting in a decrease in flow to the drift. To investigate this process, theoretical studies on degassing and redissolution phenomena have been carried out, beginning with an idealized model which yields a simple analytical solution, then relaxing some of the simplifying assumptions and using TOUGH2 to study the phenomena numerically. In conjunction with these theoretical studies, laboratory experiments on flow and degassing in transparent fracture replicas are being carried out, and are being used to check the modeling approach. We need to develop a fundamental understanding of degassing and redissolution in particular and two-phase flow phenomena in general for flow in fractures and fracture networks, in order to successfully model conditions around a nuclear waste repository, where long time and large space scales may preclude conclusive field experiments.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 107189
- Report Number(s):
- LBL-37200; CONF-9503110-; ON: DE95014788; TRN: 95:006737-0029
- Resource Relation:
- Conference: TOUGH 95: transport of unsaturated ground water and heat workshop, Berkeley, CA (United States), 20-22 Mar 1995; Other Information: PBD: Mar 1995; Related Information: Is Part Of Proceedings of the TOUGH Workshop `95 Lawrence Berkeley Laboratory, Berkeley, California, March 20--22, 1995; Pruess, K. [ed.]; PB: 380 p.
- Country of Publication:
- United States
- Language:
- English
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RADIOACTIVE WASTE MANAGEMENT
RADIOACTIVE WASTES
UNDERGROUND DISPOSAL
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