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Title: Numerical study of the THM effects on the near-field safety of ahypothetical nuclear waste repository - BMT1 of the DECOVALEX IIIproject. Part 3: Effects of THM coupling in sparsely fracturedrocks

Abstract

BENCHPAR project, the impact of thermal-hydrological-mechanical (THM) couplings on the performance of a bentonite-back-filled nuclear waste repository in near-field crystalline rocks is evaluated in a Bench-Mark Test problem (BMT1) and the results are presented in a series of three companion papers in this issue. This is the third paper with focus on the effects of THM processes at a repository located in a sparsely fractured rock. Several independent coupled THM analyses presented in this paper show that THM couplings have the most significant impact on the mechanical stress evolution, which is important for repository design, construction and post-closure monitoring considerations. The results show that the stress evolution in the bentonite-back-filled excavations and the surrounding rock depends on the post-closure evolution of both fields of temperature and fluid pressure.It is further shown that the time required to full resaturation may play an important role for the mechanical integrity of the repository drifts.In this sense, the presence of hydraulically conducting fractures in the near-field rock might actually improve the mechanical performance of the repository. Hydraulically conducting fractures in the near-field rocks enhances the water supply to the buffers/back-fills, which promotes a more timely process of resaturation and development of swelling pressures inmore » the back-fill, thus provides timely confining stress and support to the rock walls. In one particular case simulated in this study, it was shown that failure in the drift walls could be prevented if the compressive stresses in back-fill were fully developed within 50 years,which is when thermally induced rock strain begins to create high differential (failure-prone) stresses in the near-field rocks.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE; Canadian Nuclear Safety Commission, Commissariat al'Energie At omique, European Commission. BENCHPAR project ContractFIKW-CT-2000-00066, Institut de Radioprotection et de Surete Nucleaire,Japan Nuclear Fuel Cycle Development Institute, Swedish Nuclear PowerInspectorate
OSTI Identifier:
860962
Report Number(s):
LBNL-56308
R&D Project: 8Y3801; TRN: US0600217
DOE Contract Number:  
DE-AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
International Journal of Rock Mechanics & Mining Sciences
Additional Journal Information:
Journal Volume: 42; Journal Issue: 5-6; Related Information: Journal Publication Date: 10/2005
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 58 GEOSCIENCES; CONSTRUCTION; DESIGN; FRACTURES; IGNEOUS ROCKS; METAMORPHIC ROCKS; MONITORING; PERFORMANCE; RADIOACTIVE WASTES; SAFETY; STRAINS; STRESSES; SWELLING; WATER SUPPLY

Citation Formats

Rutqvist, J., Chijimatsu, M., Jing, L., Millard, A., Nguyen,T.S., Rejeb, A., Sugita, Y., and Tsang, C.F. Numerical study of the THM effects on the near-field safety of ahypothetical nuclear waste repository - BMT1 of the DECOVALEX IIIproject. Part 3: Effects of THM coupling in sparsely fracturedrocks. United States: N. p., 2004. Web.
Rutqvist, J., Chijimatsu, M., Jing, L., Millard, A., Nguyen,T.S., Rejeb, A., Sugita, Y., & Tsang, C.F. Numerical study of the THM effects on the near-field safety of ahypothetical nuclear waste repository - BMT1 of the DECOVALEX IIIproject. Part 3: Effects of THM coupling in sparsely fracturedrocks. United States.
Rutqvist, J., Chijimatsu, M., Jing, L., Millard, A., Nguyen,T.S., Rejeb, A., Sugita, Y., and Tsang, C.F. Thu . "Numerical study of the THM effects on the near-field safety of ahypothetical nuclear waste repository - BMT1 of the DECOVALEX IIIproject. Part 3: Effects of THM coupling in sparsely fracturedrocks". United States. https://www.osti.gov/servlets/purl/860962.
@article{osti_860962,
title = {Numerical study of the THM effects on the near-field safety of ahypothetical nuclear waste repository - BMT1 of the DECOVALEX IIIproject. Part 3: Effects of THM coupling in sparsely fracturedrocks},
author = {Rutqvist, J. and Chijimatsu, M. and Jing, L. and Millard, A. and Nguyen,T.S. and Rejeb, A. and Sugita, Y. and Tsang, C.F.},
abstractNote = {BENCHPAR project, the impact of thermal-hydrological-mechanical (THM) couplings on the performance of a bentonite-back-filled nuclear waste repository in near-field crystalline rocks is evaluated in a Bench-Mark Test problem (BMT1) and the results are presented in a series of three companion papers in this issue. This is the third paper with focus on the effects of THM processes at a repository located in a sparsely fractured rock. Several independent coupled THM analyses presented in this paper show that THM couplings have the most significant impact on the mechanical stress evolution, which is important for repository design, construction and post-closure monitoring considerations. The results show that the stress evolution in the bentonite-back-filled excavations and the surrounding rock depends on the post-closure evolution of both fields of temperature and fluid pressure.It is further shown that the time required to full resaturation may play an important role for the mechanical integrity of the repository drifts.In this sense, the presence of hydraulically conducting fractures in the near-field rock might actually improve the mechanical performance of the repository. Hydraulically conducting fractures in the near-field rocks enhances the water supply to the buffers/back-fills, which promotes a more timely process of resaturation and development of swelling pressures in the back-fill, thus provides timely confining stress and support to the rock walls. In one particular case simulated in this study, it was shown that failure in the drift walls could be prevented if the compressive stresses in back-fill were fully developed within 50 years,which is when thermally induced rock strain begins to create high differential (failure-prone) stresses in the near-field rocks.},
doi = {},
journal = {International Journal of Rock Mechanics & Mining Sciences},
number = 5-6,
volume = 42,
place = {United States},
year = {2004},
month = {9}
}