Projects on the effects of gas in underground storage facilities for radioacive waste (Pegasus project)

Directorate-General For Research And Innovation European Commission

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Proceedings of a progress meeting held in Mol, Belgium, 28 and 29 May 1997
Nuclear energy and safety

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• Publié par: DIRECTORATE-GENERAL-FOR-RESEARCH-AND-INNOVATION-EUROPEAN-COMMISSION
• Nombre de lectures: 17
• Langue: English
• Poids de l'ouvrage: 6 Mo

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ISSN 1018-5593
European Commission
Projects on the effects of gas in underground
storage facilities for radioactive waste
(Pegasus project)
Proceedings of a progress meeting held in Mol, Belgium,
28 and 29 May 1997
Report
EUR 18167 EN EUROPEAN COMMISSION
Edith CRESSON, Member of the Commission
responsible for research, innovation, education, training and youth
DG XII/F.5 — R & Τ specific programme 'Nuclear fission
safety 1994-98'(NFS 2)
Contact: Mr G. A. Cottone
Address: European Commission, rue de la Loi 200 (MO 75 5/43),
B-1049 Bruxelles — Tel. [phone]; fax [phone] European Commission
nuclear science
and technology
Projects on the effects of gas in underground
storage facilities for radioactive waste
(Pegasus project)
Proceedings of a progress meeting held in Mol, Belgium,
28 and 29 May 1997
Compiled by
B. Haijtink
European Commission
Rue de la Loi 200
B-1049 Brussels
W. Rodwell
AEA Technology
A 31 Winfrith
Dorset DT2 8DH
United Kingdom
R & Τ specific programme 'Nuclear fission safety 1994-98'
Area C: Radioactive waste management and disposal and decommissioning
Directorate-General
Science, Research and Development
1998 EUR 18167 EN LEGAL NOTICE
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Luxembourg: Office for Official Publications of the European Communities, 1998
ISBN 92-828-2757-7
© European Communities, 1998
Reproduction is authorised provided the source is acknowledged.
Printed in Luxembourg
PRINTED ON WHITE CHLORINE-FREE PAPER CONTENTS
Summary V
Introduction 1
Session I Gas Generation in Radioactive Waste Repositories 3
Chairperson : W. Müller, ISTec, Köln (D)
Gas Generation in Typical Low- Level Reactor Operating Waste 5
M. Valkiainen, L. Kall, M.Itavaara, V. Pitkänen, VTT (FIN),
M. Nykyri, Safram Oy (FIN), A. Haworth, M. Tearie, AEA (UK)
Correlation Between Experimental Gas Generation Measurements and 23
Characteristic Waste Parameters
W. Müller, H. Kannen, ISTec (D)
Gas Generation by Anaerobic Corrosion in Clay 31
L. Ortiz, F. Holvoet, SCK/CEN (B)
Gas Generation and Measurements in the FEBEX Project9
N. Jockwer, GRS (D)
Session II Gas Migration in Low Permeability Fractured Rock 45
Chairperson : W.R. Rodwell, AEA Technology, Winfrith (UK)
Review and Modelling of Natural Gas Migration 47
K. Clark, M. Stenhouse, M. Impey, W. Zhou, P. Grindrod, R. Brown, A. Lind,
M. White, QuantiSci Ltd (UK)
The visualisation of gas flow in fractures by Positron Emission Tomography 61
M.P. Gardiner, C. Brock, AEA Technology (UK), D. Parker, P.Dee, Univ. of
Birmingham (UK)
Simulation of Gas Migration in Single Rough Fractures and Comparison 77
of Results with Data from Positron Emission Tomography Experiments
R.F. McCarthy, W.R. Rodwell, AEA Technology (UK)
Field and laboratory studies into the transport of particles by gas micro-bubbles 105
S. Lombardi, A, Rinaldini, S. Beaubien, Univ. Roma (I)
Sella field gas injection experiment - Present position and future proposals 121
J.L. Knight, UK Nirex (UK) Session III Gas Migration through Saliferous Formations 123
Chairperson : E. Alonso, UPC, Barcelona (E)
Gas Migration in Salt 125
W.Müller,ISTec(D), G. Pusch, V. Reitenbach, Techn Univ. Clausthal (D)
GasGenerationandMigration in Crushed Salt 139
T.Rothfuchs,J.Droste, H.K. Feddersen,GRS(D), W. Bechtold FZK/PTE(D)
Session IV Gas Flow through Argillaceous Formations151
Chairperson : M. Put, SCK/CEN, Mol (Β)
Gas Migration in Clay 153
J. Harrington,S.Horseman,BGS(UK)
Gas MigrationinClayunderIsotropic Stress Conditions173
L. Ortiz, G.Volckaert,SCK/CEN(B)
Physical soil model tests in centrifuge177
V. Fioravante,S. Airoldi, B.A. Costantino ISMES (I)
Gas Migration through clay-based backfill and sealing materials and related 195
in-situ tests
G. Volckaert, L. Ortiz, F-X Holvoet, SCK/CEN (B)
Single Capillary Model of Gas Pathway Propagation in Boom clay 211
G.P. Wood, M.D. Impey, P. Grindrod, RC Brown, QuantiSci Ltd(UK)
Modelling Laboratory Gas Migration Experiments 227
C. Delahaye, E.E. Alonso, UPC (E)
List of participants 245
IV Summary
It is evident from these proceedings that the R&D work supported by the European
Commission and cofunding organisations under the PEGASUS umbrella, and particularly at
the present time within the PROGRESS project, addresses significant scientific issues
relating to gas generation and migration in potential European repository systems for the
underground disposal of radioactive wastes. The research areas covered conveniently divide
into the four categories represented by the sessions held during the meeting: gas generation,
and gas migration from repositories in the three main potential host rocks being considered
in Europe, low permeability fractured rock, saliferous formations, and argillaceous
formations. These topics parallel the four workpackages of the PROGRESS project.
For the different host rock types a further division of attention can be made between gas
migration in the far field and migration though near-field engineered features. The latter is
addressed by the two papers relating to saliferous host rocks (Müller et al. and Rothfuchs et
al.), in which the emphasis is on gas migration through crushed salt refill material as its
properties evolve after emplacement, and by the papers by Jockwer (gas generation and
migration in bentonite backfill) and Volckaert et al. (migration in clay-based backfill and
seals).
In the gas generation area a general theme of the work reported is the study of the
relationship between gas generation (and its modelling) in well characterised experimental
systems and the prediction of gas generation from coupled processes in real packaged and
emplaced wastes. Valkiainen et al. report laboratory experiments and modelling studies
preparatory to carrying out large-scale underground gas generation tests, which are also
described. Müller and Kannen are concerned about the practical limitations in data that is
available for use in predicting gas generation in real waste packages, and to develop
correlations between gas production and characteristic parameters that can be determined for
waste packages.
Ortiz and Holvoet describe experiments to measure gas production from the anaerobic
corrosion of steel waste canister material in the presence of Boom Clay. Laboratory
experiments are in progress and in situ experiments are planned. Preliminary results of the
laboratory experiments on the corrosion of the chosen stainless steel suggest that gas
generation from this source may pose negligible problems.
The session on gas migration in low permeability fractured rock included two main strands,
the use of data from natural systems as possible evidence for the occurrence of particular
mechanisms of gas migration, and studies of the fundamental processes involved in gas
migration through water-saturated rock. Identification of natural analogue gas migration
data which are adequate to discriminate between the occurrence of different mechanisms of
gas migration would be invaluable in building confidence in and refining current
understanding of gas migration. The comprehensive review by Clark et al. was designed to
identify and interpret data from the hydrocarbon industry that might serve this purpose, but it
was concluded that natural analogue gas migration data from the sources considered was
insufficiently detailed or quantitative to fully meet this aspiration. Lombardi et al. report on-going field investigations in areas exhibiting soil-gas anomalies to look for evidence for the
natural occurrence of the transport of heavy micro-particles in endogenic gas fluxes through
rock fractures. It is postulated that these fluxes may occur as microbubbles, and plans for
laboratory experiments to investigate microbubble transport through porous materials in the y are also described.
In addition to the work on microbubbles, study of the fundamental processes of gas
migration is also represented by two papers on gas migration in saturated single rock
fractures. Gardiner et al. describe the use of positron emission tomography (PET) to follow
gas displacement of water from single natural fractures, and McCarthy and Rodwell report
theoretical attempts to simulate the process. An important issue identified in these two
studies is the relationship of the resolution achievable using the PET technique to the detail
in which it is necessary to follow the gas front advance in order to provide a satisfactory
comparison with model predictions. Developing basic knowledge of the processes involved
in gas migration in rock fractures is considered an important route to addressing the issues
relating to the performance of the geosphere barrier that are identified in the Introduction.
As menti