Gas migration and two-phase flow through engineered and geological barriers for a deep repository for radioactive waste

Directorate-General For Research And Innovation European Commission

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A joint EC/NEA status Report
Nuclear energy and safety

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• Publié par: DIRECTORATE-GENERAL-FOR-RESEARCH-AND-INNOVATION-EUROPEAN-COMMISSION
• Nombre de lectures: 16
• Langue: English
• Poids de l'ouvrage: 13 Mo

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Gas Migration and Two-Phase Flow
through Engineered and Geological Barriers
for a Deep Repository for Radioactive Waste
A Joint EC/NEA Status Report
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EUR 19122 ENEUROPEAN COMMISSION
DGDG Research/D.11.3 -- RR && TT programme "Nuclear fissionfission safetysafety 1994-98"1994-98"
Contact: Mr G. A. Cottone
Address: European Commission, rue de la Loi/Wetstraat 200 (M075 5/43), B-W49 Brussels
Tel. [phone]; fax [phone]European Commission Nuclear Energy Agency
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Gas Migration and Two-Phase Flow
throughthrough Engineered andand Geological Barriers
for a Deep Repository for Radioactive Waste
A Joint EC/NEA Status Report
W. R. Rodwell ', A. W. Harris ', S. T. Horseman 2, P. Lalieux 3, W. Muller \
L. Ortiz Amaya 5 and K. Pruess 6
11 AEAAEA Technology, Harwell, UKUK
22 BritishBritish GeologicalGeological Survey,Survey, Keyworth,Keyworth, UKUK
3 OECD Nuclear Energy Agency, Issy-les-Moulineaux, F
4 Institut fur Sicherheitstechnologie (ISTec), Kòln, D
5 Nuclear Reasearch Centre SCK.CEN, Mol, B
66 Lawrence Berkeley NationalNational Laboratory,Laboratory, UniversityUniversity ofof California,California, USAUSA
Directorate-General
Science,Science, Research andand Development
1999 EUR 19122 ENLEGAL NOTICE
Neither the European Commission nor any person acting on behalf of the Commission is responsible for
the use which might be made of the following information.
A great deal of additional information on the European Union is available on the Internet.
It can be accessed through the Europa server (http://europa.eu.int).
Cataloguing datadata cancan bebe foundfound atat thethe endend ofof thisthis publication.publication.
Luxembourg: Office for Official Publications of the European Communities, 1999
ISBN 92-828-8132-6
© European Communities, 1999
Reproduction is authorised provided the source is acknowledged.
Printed inin BelgiumBelgium
Printed on white chlorine-free paperFOREWORD
In underground repositories for radioactive waste, significant quantities of gases may be
generated due to several processes. These gases may migrate through the engineered barrier
system and the natural geological barrier. It is therefore recommended that the potential
impactimpact ofof gasgas accumulation andand migrationmigration onon thethe performance ofof thethe variousvarious barriersbarriers shouldshould
bebe addressedaddressed andand assessedassessed in thethe development of safetysafety casescases for radioactive wastewaste
repositories.
Significant effort has and continues to be expended in numerous national and international
programmes in attempts to understand and assess this potential impact, notably in the
framework ofof thethe EuropeanEuropean Commission's NuclearNuclear FissionFission Safety programme.programme. TheseThese effortsefforts
have resulted in significantly improved understanding of the relevant processes and produced
an important collection of experimental data.
hi this context, it was considered timely to undertake a review ofthe knowledge gained so far
and establish the current status of the basic understanding ofthe gas issue.
To ensure proper coverage of all the R&D work already carried out within national and
international programmes, and to avoid duplication of efforts, the elaboration of the status
report has been set up under the joint auspices of the European Commission (EC) and the
Nuclear Energy Agency of the Organisation for Economic Co-operation and Development
(NEA/OECD). The work has been commissioned from a group of authoritative experts by the
European Commission, inin thethe frameworkframework ofof itsits R&DR&D programmeprogramme onon NuclearNuclear FissionFission Safely,
and by several national waste management organisations represented within the NEA Co¬
ordinating Group for Site Evaluation and Design of Experiments for Radioactive Waste
Disposal (SEDE).
TheThe presentpresent reportreport providesprovides aa synthesissynthesis ofof availableavailable information,information, identifiesidentifies keykey conceptsconcepts andand
mechanisms andand theirtheir coupling, evaluatesevaluates thethe current approachesapproaches toto modellingmodelling andand assessing
the impact of gas on repository performance, highlights, wherever possible, some of the
unresolved issues, and presents recommendations for further work.
The opinions and conclusions expressed are those of the authors only and do not necessarily
reflect thethe viewsviews ofof thethe funding organisations,organisations, anyany ECEC and/orand/or OECDOECD Member country,country, oror
international organisation.
mACKNOWLEDGEMENTS
The status report has been jointly supported by the European Commission and a consortium
ofnational organisations active in the field of radioactive waste management and represented
within the NEA Co-ordinating Group for Site Evaluation and Design of Experiments for
Radioactive Waste Disposal (SEDE):
-- ANDRA, FranceFrance (National(National Radioactive WasteWaste ManagementManagement Agency);Agency);
ENRESA, Spain Agency for Radioactive Waste);
- IPSN, France (Nuclear Protection and Safety Institute);
- ONDRAF/NIRAS, Belgium (National Organisation for Radioactive Waste and
Fissile Materials);
Ontario PowerPower Generation, Canada;
- NAGRA, Switzerland (National Co-operative for the Disposal of Radioactive
Waste);
- N1REX, United Kingdom;
- SKB, Sweden (Swedish Nuclear Fuel and Waste Management Company);
SKI, Power Inspectorate); and
-- UKEA, UnitedUnited KingdomKingdom (Environment Agency);
- USDOE/YMP, United States (Department ofEnergy, Yucca Mountain Project).
Furthermore, GRS, Germany (Company for Reactor Safety) and SCK/CEN, Belgium (Nuclear
Energy Research Centre) contributed to the status report by providing a thorough review of the
draftdraft versions.versions.
All these organisations are deeply thanked for their support and for their fruitful reviews and
comments.
The EC and the NEA wish to express their gratitude to the authors of this report - A.W. Harris,
S.T.S.T. Horseman,Horseman, Ph.Ph. Lalieux,Lalieux, W.W. Muller,Muller, L.L. OrtizOrtiz Amaya, K.K. Pruess andand W.R.W.R. RodwellRodwell -- andand toto
allall theirtheir colleagues,colleagues, tootoo numerous toto bebe quotedquoted here,here, whowho havehave helpedhelped themthem inin theirtheir task.task. InIn
particular, the EC and the NEA wish to commend W.R. Rodwell for his effective management
of the report drafting.
B. Haijtink and Ph. Lalieux were responsible for the co-ordination of this report on behalf of
thethe EC/DGX1IEC/DGX1I andand thethe NEANEA WasteWaste Management Division respectively.respectively.
IVEXECUTIVE SUMMARY
In recent years it has become apparent that:
a) in many scenarios for the disposal of radioactive waste in geological media, gas
migration and two-phase flows may occur in the engineered barrier systems
associated with a repository and in the geosphere in the vicinity of the repository, and
b) mechanisms may exist by which these flows might potentially have an impact on the
performance of the geosphere or engineered barriers.
Significant effort has been and continues to be expended in numerous national and
international programmes in attempts to understand the potential impact of gas migration,
andand ofof two-phasetwo-phase gas-gas-waterwater processes,processes, onon thethe performance ofof underground radioactive wastewaste
repositories, and to provide modelling tools or approaches that will allow these impacts to be
assessed. In the light of these efforts, it was considered timely and of widespread benefit to
undertake a review (Status Report) to establish the current status of the basic understanding
that exists of gas migration and two-phase gas-water flow processes and their potential
impacts onon thethe performanceperformance ofof engineeredengineered andand geological barriers forfor thethe deepdeep disposaldisposal ofof
radioactive waste.waste. ThisThis reportreport hashas beenbeen preparedprepared toto fulfil thethe needneed for suchsuch anan overview.overview. It
has been prepared as a joint EC (DG XH) and NEA project, with funding providedjointly by
the EC through its R&D programme on Nuclear Fission Safety, and by several national waste
management organisations represented within the NEA Co-ordinating Group for Site
Evaluation and Design of Experiments for Radioactive Waste Disposal (SEDE).
The report is intended to cover work published prior to January 1999, but does also include
some work known to the authors that was being prepared for publication at that time.
The following limitations on the scope and ambitions of the report should be noted:
a)a) TheThe reviewreview isis restricted inin itsits aimsaims toto two-phase flowflow involvinginvolving gasgas andand waterwater only.only.
(The potential presence of non-aqueous phase liquids in a repository environment is
not discussed.)
b) The focus is on long term safety issues, and thus the emphasis is on gas migration and
two-phase flow after repository closure (with account taken of the operational phase
inin asas farfar asas itit determines thethe initialinitial