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Title: Investigation of two-phase flow phenomena associated with corrosion in an SF/HLW repository in Opalinus Clay, Switzerland

Abstract

Gas generation from corrosion of the waste canisters and gas accumulation in the backfilled emplacement tunnels is a key issue in the assessment of long-term radiological safety of the proposed repository for spent fuel and high-level waste (SF/HLW) sited in the Opalinus Clay formation of Northern Switzerland. Previous modeling studies indicated a significant pressure buildup in the backfilled emplacement tunnels for those sensitivity runs, where corrosion rates were high and the permeability of the Opalinus Clay was very low. As an extension to those studies, a refined process model of the canister corrosion phenomena has been developed, which accounts not only for the gas generation but also for the water consumption associated with the chemical reaction of corrosion of steel under anaerobic conditions. The simulations with the new process model indicate, that with increasing corrosion rates and decreasing host-rock permeability, pressure buildup increased, as expected. However, the simulations taking into account water consumption show that the pressure buildup is reduced compared to the simulation considering only gas generation. The pressure reduction is enhanced for lower permeability of the Opalinus Clay and for higher corrosion rates, which correspond to higher gas generations rates and higher water consumption rates. Moreover, the simulatedmore » two-phase flow patterns in the engineered barrier system (EBS) and surrounding Opalinus Clay show important differences at late time of the gas production phase as the generated gas continues to migrate outward into the surrounding host rock. For the case without water consumption, the water flow indicates overall downward flow due to a change in the overall density of the gas-fluid mixture from that based on the initially prescribed hydrostatic pressure gradient. For the case with water consumption, water flow converges toward the waste canister at a rate corresponding to the water consumption rate associated with the corrosion reaction. The water flow toward the canister is maintained even for very low permeabilities of the Opalinus clay, sustaining the anaerobic corrosion of the steel canister.« less

Authors:
; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
Earth Sciences Division
OSTI Identifier:
971847
Report Number(s):
LBNL-2412E
TRN: US1001267
DOE Contract Number:  
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics and Chemistry of the Earth; Journal Volume: 333; Related Information: Journal Publication Date: 2008
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; ANAEROBIC CONDITIONS; BUILDUP; CHEMICAL REACTIONS; CONSUMPTION RATES; CONTAINERS; CORROSION; HYDROSTATICS; MIXTURES; PERMEABILITY; POSITIONING; PRESSURE GRADIENTS; PRODUCTION; SAFETY; SENSITIVITY; SPENT FUELS; STEELS; TWO-PHASE FLOW; WASTES; WATER

Citation Formats

Senger, R., Marschall, P., and Finsterle, S. Investigation of two-phase flow phenomena associated with corrosion in an SF/HLW repository in Opalinus Clay, Switzerland. United States: N. p., 2008. Web. doi:10.1016/j.pce.2008.10.034.
Senger, R., Marschall, P., & Finsterle, S. Investigation of two-phase flow phenomena associated with corrosion in an SF/HLW repository in Opalinus Clay, Switzerland. United States. doi:10.1016/j.pce.2008.10.034.
Senger, R., Marschall, P., and Finsterle, S. Mon . "Investigation of two-phase flow phenomena associated with corrosion in an SF/HLW repository in Opalinus Clay, Switzerland". United States. doi:10.1016/j.pce.2008.10.034. https://www.osti.gov/servlets/purl/971847.
@article{osti_971847,
title = {Investigation of two-phase flow phenomena associated with corrosion in an SF/HLW repository in Opalinus Clay, Switzerland},
author = {Senger, R. and Marschall, P. and Finsterle, S.},
abstractNote = {Gas generation from corrosion of the waste canisters and gas accumulation in the backfilled emplacement tunnels is a key issue in the assessment of long-term radiological safety of the proposed repository for spent fuel and high-level waste (SF/HLW) sited in the Opalinus Clay formation of Northern Switzerland. Previous modeling studies indicated a significant pressure buildup in the backfilled emplacement tunnels for those sensitivity runs, where corrosion rates were high and the permeability of the Opalinus Clay was very low. As an extension to those studies, a refined process model of the canister corrosion phenomena has been developed, which accounts not only for the gas generation but also for the water consumption associated with the chemical reaction of corrosion of steel under anaerobic conditions. The simulations with the new process model indicate, that with increasing corrosion rates and decreasing host-rock permeability, pressure buildup increased, as expected. However, the simulations taking into account water consumption show that the pressure buildup is reduced compared to the simulation considering only gas generation. The pressure reduction is enhanced for lower permeability of the Opalinus Clay and for higher corrosion rates, which correspond to higher gas generations rates and higher water consumption rates. Moreover, the simulated two-phase flow patterns in the engineered barrier system (EBS) and surrounding Opalinus Clay show important differences at late time of the gas production phase as the generated gas continues to migrate outward into the surrounding host rock. For the case without water consumption, the water flow indicates overall downward flow due to a change in the overall density of the gas-fluid mixture from that based on the initially prescribed hydrostatic pressure gradient. For the case with water consumption, water flow converges toward the waste canister at a rate corresponding to the water consumption rate associated with the corrosion reaction. The water flow toward the canister is maintained even for very low permeabilities of the Opalinus clay, sustaining the anaerobic corrosion of the steel canister.},
doi = {10.1016/j.pce.2008.10.034},
journal = {Physics and Chemistry of the Earth},
number = ,
volume = 333,
place = {United States},
year = {Mon Aug 04 00:00:00 EDT 2008},
month = {Mon Aug 04 00:00:00 EDT 2008}
}