3D THM modelling of Finnish spent nuclear fuel repository

This paper presents modelling of the long-term performance of engineered barrier systems (EBS) in crystalline host rock in terms of coupled thermo-hydro-mechanical (THM) processes in a specific case, considering also the impact of salinity linked with geochemistry. This study has been used as a supp...

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Authors: Toprak, Erdem|||0000-0001-9006-3504, Olivella Pastallé, Sebastià|||0000-0003-3976-4027, Pintado, Xavier, Niskanen, Mika
Format: article
Publication Date:2024
Country:España
Institution:Universitat Politècnica de Catalunya (UPC)
Repository:UPCommons. Portal del coneixement obert de la UPC
Language:English
OAI Identifier:oai:upcommons.upc.edu:2117/421119
Online Access:https://hdl.handle.net/2117/421119
https://dx.doi.org/10.3389/fbuil.2024.1465051
Access Level:Open access
Keyword:Nuclear waste repository design
Engineered barrier system
THM coupled processes
BBM
Double structure model
CODE_BRIGHT
Àrees temàtiques de la UPC::Enginyeria civil::Geotècnia::Mecànica de sòls
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spelling 3D THM modelling of Finnish spent nuclear fuel repositoryToprak, Erdem|||0000-0001-9006-3504Olivella Pastallé, Sebastià|||0000-0003-3976-4027Pintado, XavierNiskanen, MikaNuclear waste repository designEngineered barrier systemTHM coupled processesBBMDouble structure modelCODE_BRIGHTÀrees temàtiques de la UPC::Enginyeria civil::Geotècnia::Mecànica de sòlsThis paper presents modelling of the long-term performance of engineered barrier systems (EBS) in crystalline host rock in terms of coupled thermo-hydro-mechanical (THM) processes in a specific case, considering also the impact of salinity linked with geochemistry. This study has been used as a supporting document for the safety case in the operating licence application for the Olkiluoto spent nuclear fuel repository in Finland. The disposal design chosen is the KBS-3V (Kärnbränslesäkerhet in Swedish, “nuclear fuel safety”; 3, version number; V, vertical) which consists of placing the canisters in vertical deposition holes surrounded by the EBS. The buffer components consist of compacted blocks of Wyoming-type bentonite surrounded by pillow pellets manufactured with the same material. Bulgarian and/or Italian granular filling (GraFi) materials are the backfilling material in the deposition tunnels. The Barcelona basic model (BBM) was considered for modelling the geomechanical behaviour of compacted buffer blocks and GraFi materials filling the deposition tunnels. The Barcelona expansive model (BExM), which consists of a double structure (macro–micro porosity), was considered for the pellets. A laboratory testing campaign (thermal conductivity, water retention curve, oedometer, and infiltration tests) was carried out in order to calibrate the THM model parameters of the corresponding materials. Model-data uncertainties, challenges in 3D THM modelling, and the methodology followed have been provided in terms of modelling capabilities. We implemented 3D THM simulation of an individual deposition hole (canister, notch/chamfer, and buffer materials) drilled into a deposition tunnel (backfill material) in CODE_BRIGHT as a finite element method (FEM) program. This study presents results related to THM performance of the EBS, such as peak temperature, time required to reach full saturation in buffer and backfill, the evolution of dry densities according to permeabilities, the development of swelling pressure in buffer and backfill, and, consequently, deformations in buffer and backfill domains. A sensitivity analysis plan was followed in order to deal with various factors affecting the long-term THM performance of the EBS. In the sensitivity analysis, buffer and backfill design options (different filling material alternatives), geological conditions (saline water, rock permeability, and heterogeneous rock) and numerical simulation options (different numerical model options, issues related to geometry and meshing) were investigated. The performance targets and design specifications set for the buffer and backfill are also discussed. The paper concludes with a summary how the THM design under a certain configuration (geometry, initial conditions, boundary conditions, and buffer and backfill materials) meets the performance targets set for the buffer, backfill, and host rock.Peer ReviewedFrontiers20242024-10-0120242024-12-19journal articlehttp://purl.org/coar/resource_type/c_6501VoRhttp://purl.org/coar/version/c_970fb48d4fbd8a85info:eu-repo/semantics/articleapplication/pdfhttps://hdl.handle.net/2117/421119https://dx.doi.org/10.3389/fbuil.2024.1465051reponame:UPCommons. Portal del coneixement obert de la UPCinstname:Universitat Politècnica de Catalunya (UPC)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2Attribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/info:eu-repo/semantics/openAccessoai:upcommons.upc.edu:2117/4211192026-05-27T15:37:01Z
dc.title.none.fl_str_mv 3D THM modelling of Finnish spent nuclear fuel repository
title 3D THM modelling of Finnish spent nuclear fuel repository
spellingShingle 3D THM modelling of Finnish spent nuclear fuel repository
Toprak, Erdem|||0000-0001-9006-3504
Nuclear waste repository design
Engineered barrier system
THM coupled processes
BBM
Double structure model
CODE_BRIGHT
Àrees temàtiques de la UPC::Enginyeria civil::Geotècnia::Mecànica de sòls
title_short 3D THM modelling of Finnish spent nuclear fuel repository
title_full 3D THM modelling of Finnish spent nuclear fuel repository
title_fullStr 3D THM modelling of Finnish spent nuclear fuel repository
title_full_unstemmed 3D THM modelling of Finnish spent nuclear fuel repository
title_sort 3D THM modelling of Finnish spent nuclear fuel repository
dc.creator.none.fl_str_mv Toprak, Erdem|||0000-0001-9006-3504
Olivella Pastallé, Sebastià|||0000-0003-3976-4027
Pintado, Xavier
Niskanen, Mika
author Toprak, Erdem|||0000-0001-9006-3504
author_facet Toprak, Erdem|||0000-0001-9006-3504
Olivella Pastallé, Sebastià|||0000-0003-3976-4027
Pintado, Xavier
Niskanen, Mika
author_role author
author2 Olivella Pastallé, Sebastià|||0000-0003-3976-4027
Pintado, Xavier
Niskanen, Mika
author2_role author
author
author
dc.subject.none.fl_str_mv Nuclear waste repository design
Engineered barrier system
THM coupled processes
BBM
Double structure model
CODE_BRIGHT
Àrees temàtiques de la UPC::Enginyeria civil::Geotècnia::Mecànica de sòls
topic Nuclear waste repository design
Engineered barrier system
THM coupled processes
BBM
Double structure model
CODE_BRIGHT
Àrees temàtiques de la UPC::Enginyeria civil::Geotècnia::Mecànica de sòls
description This paper presents modelling of the long-term performance of engineered barrier systems (EBS) in crystalline host rock in terms of coupled thermo-hydro-mechanical (THM) processes in a specific case, considering also the impact of salinity linked with geochemistry. This study has been used as a supporting document for the safety case in the operating licence application for the Olkiluoto spent nuclear fuel repository in Finland. The disposal design chosen is the KBS-3V (Kärnbränslesäkerhet in Swedish, “nuclear fuel safety”; 3, version number; V, vertical) which consists of placing the canisters in vertical deposition holes surrounded by the EBS. The buffer components consist of compacted blocks of Wyoming-type bentonite surrounded by pillow pellets manufactured with the same material. Bulgarian and/or Italian granular filling (GraFi) materials are the backfilling material in the deposition tunnels. The Barcelona basic model (BBM) was considered for modelling the geomechanical behaviour of compacted buffer blocks and GraFi materials filling the deposition tunnels. The Barcelona expansive model (BExM), which consists of a double structure (macro–micro porosity), was considered for the pellets. A laboratory testing campaign (thermal conductivity, water retention curve, oedometer, and infiltration tests) was carried out in order to calibrate the THM model parameters of the corresponding materials. Model-data uncertainties, challenges in 3D THM modelling, and the methodology followed have been provided in terms of modelling capabilities. We implemented 3D THM simulation of an individual deposition hole (canister, notch/chamfer, and buffer materials) drilled into a deposition tunnel (backfill material) in CODE_BRIGHT as a finite element method (FEM) program. This study presents results related to THM performance of the EBS, such as peak temperature, time required to reach full saturation in buffer and backfill, the evolution of dry densities according to permeabilities, the development of swelling pressure in buffer and backfill, and, consequently, deformations in buffer and backfill domains. A sensitivity analysis plan was followed in order to deal with various factors affecting the long-term THM performance of the EBS. In the sensitivity analysis, buffer and backfill design options (different filling material alternatives), geological conditions (saline water, rock permeability, and heterogeneous rock) and numerical simulation options (different numerical model options, issues related to geometry and meshing) were investigated. The performance targets and design specifications set for the buffer and backfill are also discussed. The paper concludes with a summary how the THM design under a certain configuration (geometry, initial conditions, boundary conditions, and buffer and backfill materials) meets the performance targets set for the buffer, backfill, and host rock.
publishDate 2024
dc.date.none.fl_str_mv 2024
2024-10-01
2024
2024-12-19
dc.type.none.fl_str_mv journal article
http://purl.org/coar/resource_type/c_6501
VoR
http://purl.org/coar/version/c_970fb48d4fbd8a85
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://hdl.handle.net/2117/421119
https://dx.doi.org/10.3389/fbuil.2024.1465051
url https://hdl.handle.net/2117/421119
https://dx.doi.org/10.3389/fbuil.2024.1465051
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2
Attribution 4.0 International
http://creativecommons.org/licenses/by/4.0/
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2
Attribution 4.0 International
http://creativecommons.org/licenses/by/4.0/
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Frontiers
publisher.none.fl_str_mv Frontiers
dc.source.none.fl_str_mv reponame:UPCommons. Portal del coneixement obert de la UPC
instname:Universitat Politècnica de Catalunya (UPC)
instname_str Universitat Politècnica de Catalunya (UPC)
reponame_str UPCommons. Portal del coneixement obert de la UPC
collection UPCommons. Portal del coneixement obert de la UPC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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