Fluid and ionic transport properties of deformed salt rock

European Commission Directorate-General For The Information Society And Media Directorate-General For Research And Innovation

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Nuclear energy and safety
Environment policy and protection of the environment

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• Publié par: EUROPEAN-COMMISSION-DIRECTORATE-GENERAL-FOR-THE-INFORMATION-SOCIETY-AND-MEDIA-DI
• Nombre de lectures: 9
• Langue: English
• Poids de l'ouvrage: 2 Mo

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imission of the European Communities
nuclear science
and technology
Fluid and ionic transport properti
of deformed salt rock
Report
EUR 10926 EN Commission of the European Communities
nuclear science
and technology
Fluid and ionic transport properties
of deformed salt rock
C.J. Peach, C.J. Spiers,
A.J. Tankink, H.J. Zwart
Department of Structural and Applied Geology
Institute of Earth Sciences
State University of Utrecht, The Netherlands
Contract No WAS-153-80-7-N(N)
Final report
January 1984 —June 1985
Work performed under contract in the framework of the European Atomic
Energy Community's cost-sharing research programme on
'Radioactive waste management and disposal'
Directorate-General
Science, Research and Development PARI H!r?. Biblioth.
KV€UR10926EN 1987
CL Published by the
COMMISSION OF THE EUROPEAN COMMUNITIES
Directorate-General
Telecommunications, Information Industries and Innovation
Bâtiment Jean Monnet
LUXEMBOURG
LEGAL NOTICE
Neither the Commission of the European Communities nor any person acting on
behalf of then is responsible for the use which might be made of the
following information
Cataloguing data can be found at the end of this publication
Luxembourg: Office for Official Publications of the European Communities, 1987
ISBN 92-825-6921 -7 Catalogue number: CD-NA-10926-EN-C
© ECSC-EEC-EAEC, Brussels • Luxembourg, 1987
Printed in Belgium CONTENTS
1. GENERAL INTRODUCTION 1
1.1. Scope of Research Programme
1.2. Scope of Present Report
2. GAS PERMEABILITY WORK 3
2.1. Apparatus and Measurement Methods
2.1.1. Apparatus
2.1.2. Method 7
2.1.2.1. Theory
2.1.2.2. Practice 9
2.1.3. Klinkenberg Effect 10
2.2. Permeability Measurements on Natural Starting Material
(Asse Speisesalz)4
2.3. Permeabilitys on Experimentally Deformed
Material 19
2.4. Permeability Decay Characteristics of Dry, Dilated
Salt Rock 22
2.4.1. Methods
2.4.2. Results
2.4.3. Conclusions 30
3. BRINE PERMEABILITY WORK3
3.1. Apparatus and Measurement Methods 3
3.1.1. Apparatus
3.1.2. Measurement Methods7 3.1.2.1. Theoretical Considerations 37
3.1.2.2. Practice (Steady-State Flow Method) 40
3.2. Long Term Permeability Decay Experiment on Wet, Dilated
Salt Rock 42
3.2.1. Method
3.2.2. Results5
3.2.3. Conclusions 54
4. ION MIGRATION/RETENTION EXPERIMENTS 56
4.1. Migration/Retention Tests at NTP using Sr2+, Cs+ and Fe3+ . 57
4.1.1. General Experimental Procedure7
4.1.1.1. Method 5
4.1.1.2. Sample Preparation and Setting Up 5
4.1.1.3. Test Termination, Sectioning, and Analysis9
4.1.2. Experiments on Intact Salt 60
4.1.2.1. Conditions
4.1.2.2. Results of Spectroscopic Analysis of Salt Slices . . 6
4.1.2.3. Microstructural/Microchemical Observations 6
4.1.2.4. Conclusions 61
4.1.3. Experiments on Deformed Salt
4.1.3.1. Conditions
4.1.3.2. Results of Spectroscopic Analysis of Salt Slices . . 6
4.1.3.3. Microstructural and Microchemical Observations ... 62
4.1.3.4. Discussion5
4.1.3.5. Conclusions8
4.2. Migration/Retention Test at 80°C, 1 atm using Sr2+ and Cs+ . 69
- IV 4.2.1. Experimental Method and Conditions 69
4.2.2. Results 70
4.2.3. Discussion/Conclusions
4.3. Long Term Flow-Through Retention Test at NTP 72
4.3.1. Experimental method and Conditions
4.3.2. Results
4.3.3. Discussion/Conclusions 75
4.4. Long Term Flow-Through Retention Test at Elevated Pressure . 77
4.4.1. Apparatus, Starting Material and Brine Composition ... 77
4.4.2. Experimental Method and Conditions 77
4.4.3. Analytical Methods 78
4.4.4. Results of Analyses
4.4.5. Discussion/Conclusions 80
4.5. Migration/Retention Tests using Tc-Contaminated Brine ... 83
4.5.1. Experimental Method and Conditions3
4.5.2. Results 84
4.5.3. Discussion/Conclusions
5. SUMMARY6
Acknowledgements9
References 90
V 1. GENERAL INTRODUCTION
1.1. Scope of Research Programme
In planning for the disposal of radioactive waste in salt formations,
it is important to consider the scenario that brine may eventually
gain access to the repository area or to the surrounding near-field.
The present Utrecht programme is concerned with determining the effect
of brine on salt rock rheology (mechanical flow), and whether or not
creep-related effects, such as dilatancy (volume increase occurring
via microcracking during deformation) and solution-transfer processes,
might facilitate or hinder ionic transport through salt. The specific
objectives of the programme are as follows:
1) to determine the rheological and dilatant properties of "dry" salt
rock (i.e. salt rock containing inherent brine only) under relevant
P-T conditions;
2) to determine the effects of added brine on rheological and dilatant
behaviour;
3) to study ionic transport in deformed and deforming salt rock.
The project is based around a triaxial testing machine (referred to
the Heard apparatus - see Spiers et al, 1986) designed with the capa­
bility of measuring sample volume change, in addition to conventional
rheological parameters (differential stress, strain rate, strain,
temperature, pressure, pore fluid pressure).
1.2. Scope of .Present Report
This is a final report on the work done under objective 3 of the
research programme, i.e. on transport properties (see above).
This work was carried out during the final 18 months of the
programme, namely during the period 1/1/1984 - 30/6/1985.
- 1 As previously outlined by Peach eţ^ al (1984 a,b), the transport
of gas­ and brine­bourne radionuclides through salt rock or salt
backfill material can be considered to be determined by the
following factors:
a) convection­ or convergence­forced fluid flows via whatever
permeability exists;
b) diffusion via connected pores;
c) ionic or molecular retention/sorption/desorption effects;
d) gravitational and solution/preciptation driven transport
of brine/gas pockets.
The work documented in the present report was directed largely
at the measurement of creep­induced permeability in salt rock,
at determining the permeability persistance/decay characteristics
of creep­dilated salt rock under hydrostatic conditions) and
at ion migration/retention experiments on both deformed and
undeformed material. The permeability work was carried out
using both gas (argon) and brine, and involved the design and
construction of corresponding permeametry systems for use in
conjuction with the Heard triaxial machine (see Spiers eţ^ al,
1986). The work performed using gas is reported in Section 2, while
that performed using brine is described in Section 3. The ion
migration/retention studies undertaken are described in Section 4.
2+ +
These involved the use of contaminant species such as Sr ,Cs,
3+ 2+
Fe , Pb and TcO, . An overall summary of conclusions is presen­
ted in Section 5.