Simulation of hydraulic disturbances caused by the underground rock characterization facility in Olkiluoto, Finland

Jari Löfman, Ferenc Mészáros

Research output: Chapter in Book/Report/Conference proceedingChapter or book articleProfessional

1 Citation (Scopus)

Abstract

A final repository for spent nuclear fuel is sought in Finland by Posiva (a company responsible for the construction and operation of the final nuclear-waste disposal facility in Finland, http://www.posiva.fi). A part of this project involves an underground rock characterization facility (ONKALO), which will consist of an 8,500 m long and 520 m deep system of tunnels, to be potentially extended with the drifts of the repository. The maximum hydraulic disturbance (water table drawdown, deep saline-water upconing and tunnel inflow) that might result from the construction and operation of the ONKALO facility were assessed by site-scale finite-element simulations. The drawdown was calculated by employing the free-surface approach. Tunnel inflows were obtained from the state of equilibrium, while the evolution of the salinity distribution was simulated using a time-dependent and coupled flow and salt transport model. The simulations showed that without engineering measures to limit inflow of groundwater into the ONKALO facility, the hydraulic disturbances would be significantly greater than with these measures implemented. Most of the inflow (330-1,100 L/min) would come from the conductive subhorizontal fracture zones intersected by the drifts. The water table could sink to a depth of about 200 m, and the depressed area could extend over the Olkiluoto Island. Groundwater salinity (expressed as total dissolved solids [TDS]) could locally rise from 22 g/L to over 50 g/L at the tunnel depth of 520 m. With tight grouting, the simulations showed that the depression in the water table can be confined to the immediate vicinity of the ONKALO, the maximum drawdown of the water table remained around 10 m, and the total inflow to the tunnels was about 20 L/min. Moreover, upconing of the saline water remained moderate.
Original languageEnglish
Title of host publicationDynamics of Fluids and Transport in Fractured Rock
EditorsBoris Faybishenko, John Gale, Paul A. Witherspoon
Place of PublicationWashington, DC
Pages129-149
Volume162
DOIs
Publication statusPublished - 2005
MoE publication typeD2 Article in professional manuals or guides or professional information systems or text book material

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inflow
tunnel
water table
hydraulics
disturbance
drawdown
rock
simulation
repository
salinity
groundwater
grouting
fracture zone
waste disposal
radioactive waste
salt
engineering
water

Cite this

Löfman, J., & Mészáros, F. (2005). Simulation of hydraulic disturbances caused by the underground rock characterization facility in Olkiluoto, Finland. In B. Faybishenko, J. Gale, & P. A. Witherspoon (Eds.), Dynamics of Fluids and Transport in Fractured Rock (Vol. 162, pp. 129-149). Washington, DC. https://doi.org/10.1029/162GM13
Löfman, Jari ; Mészáros, Ferenc. / Simulation of hydraulic disturbances caused by the underground rock characterization facility in Olkiluoto, Finland. Dynamics of Fluids and Transport in Fractured Rock. editor / Boris Faybishenko ; John Gale ; Paul A. Witherspoon. Vol. 162 Washington, DC, 2005. pp. 129-149
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Löfman, J & Mészáros, F 2005, Simulation of hydraulic disturbances caused by the underground rock characterization facility in Olkiluoto, Finland. in B Faybishenko, J Gale & PA Witherspoon (eds), Dynamics of Fluids and Transport in Fractured Rock. vol. 162, Washington, DC, pp. 129-149. https://doi.org/10.1029/162GM13

Simulation of hydraulic disturbances caused by the underground rock characterization facility in Olkiluoto, Finland. / Löfman, Jari; Mészáros, Ferenc.

Dynamics of Fluids and Transport in Fractured Rock. ed. / Boris Faybishenko; John Gale; Paul A. Witherspoon. Vol. 162 Washington, DC, 2005. p. 129-149.

Research output: Chapter in Book/Report/Conference proceedingChapter or book articleProfessional

TY - CHAP

T1 - Simulation of hydraulic disturbances caused by the underground rock characterization facility in Olkiluoto, Finland

AU - Löfman, Jari

AU - Mészáros, Ferenc

PY - 2005

Y1 - 2005

N2 - A final repository for spent nuclear fuel is sought in Finland by Posiva (a company responsible for the construction and operation of the final nuclear-waste disposal facility in Finland, http://www.posiva.fi). A part of this project involves an underground rock characterization facility (ONKALO), which will consist of an 8,500 m long and 520 m deep system of tunnels, to be potentially extended with the drifts of the repository. The maximum hydraulic disturbance (water table drawdown, deep saline-water upconing and tunnel inflow) that might result from the construction and operation of the ONKALO facility were assessed by site-scale finite-element simulations. The drawdown was calculated by employing the free-surface approach. Tunnel inflows were obtained from the state of equilibrium, while the evolution of the salinity distribution was simulated using a time-dependent and coupled flow and salt transport model. The simulations showed that without engineering measures to limit inflow of groundwater into the ONKALO facility, the hydraulic disturbances would be significantly greater than with these measures implemented. Most of the inflow (330-1,100 L/min) would come from the conductive subhorizontal fracture zones intersected by the drifts. The water table could sink to a depth of about 200 m, and the depressed area could extend over the Olkiluoto Island. Groundwater salinity (expressed as total dissolved solids [TDS]) could locally rise from 22 g/L to over 50 g/L at the tunnel depth of 520 m. With tight grouting, the simulations showed that the depression in the water table can be confined to the immediate vicinity of the ONKALO, the maximum drawdown of the water table remained around 10 m, and the total inflow to the tunnels was about 20 L/min. Moreover, upconing of the saline water remained moderate.

AB - A final repository for spent nuclear fuel is sought in Finland by Posiva (a company responsible for the construction and operation of the final nuclear-waste disposal facility in Finland, http://www.posiva.fi). A part of this project involves an underground rock characterization facility (ONKALO), which will consist of an 8,500 m long and 520 m deep system of tunnels, to be potentially extended with the drifts of the repository. The maximum hydraulic disturbance (water table drawdown, deep saline-water upconing and tunnel inflow) that might result from the construction and operation of the ONKALO facility were assessed by site-scale finite-element simulations. The drawdown was calculated by employing the free-surface approach. Tunnel inflows were obtained from the state of equilibrium, while the evolution of the salinity distribution was simulated using a time-dependent and coupled flow and salt transport model. The simulations showed that without engineering measures to limit inflow of groundwater into the ONKALO facility, the hydraulic disturbances would be significantly greater than with these measures implemented. Most of the inflow (330-1,100 L/min) would come from the conductive subhorizontal fracture zones intersected by the drifts. The water table could sink to a depth of about 200 m, and the depressed area could extend over the Olkiluoto Island. Groundwater salinity (expressed as total dissolved solids [TDS]) could locally rise from 22 g/L to over 50 g/L at the tunnel depth of 520 m. With tight grouting, the simulations showed that the depression in the water table can be confined to the immediate vicinity of the ONKALO, the maximum drawdown of the water table remained around 10 m, and the total inflow to the tunnels was about 20 L/min. Moreover, upconing of the saline water remained moderate.

U2 - 10.1029/162GM13

DO - 10.1029/162GM13

M3 - Chapter or book article

SN - 0-87590-427-0

SN - 978-0-875-90427-6

VL - 162

SP - 129

EP - 149

BT - Dynamics of Fluids and Transport in Fractured Rock

A2 - Faybishenko, Boris

A2 - Gale, John

A2 - Witherspoon, Paul A.

CY - Washington, DC

ER -

Löfman J, Mészáros F. Simulation of hydraulic disturbances caused by the underground rock characterization facility in Olkiluoto, Finland. In Faybishenko B, Gale J, Witherspoon PA, editors, Dynamics of Fluids and Transport in Fractured Rock. Vol. 162. Washington, DC. 2005. p. 129-149 https://doi.org/10.1029/162GM13