The DECOVALEX II project was an extension of the DECOVALEX I project (1992–1994), for a period of four years (1995-1999). The project was initiated by recognizing the need for a proper evaluation of the current capacities of numerical modeling of coupled thermo-hydro-mechanical (THM) processes in fractured geological media for less characterized, more complex and realistic in-situ experiments at larger scales—as compared to the small scaled, well characterized and relatively much simpler laboratory experiments investigated during the DECOVALEX I project.
The overall objective of the DECOVALEX II project was to increase the understanding of various coupled THM processes of importance for radionuclide release and transport from a repository to thebiosphere and how they can be described by mathematical models, with focus on large scale in-situ experiments. An additional objective was to evaluate how studies conducted in the DECOVALEX I and DECOVALEX II projects could be used for design and performance assessment of radioactive waste repositories.
Motivated by the outstanding issue of the need to model field scale THM experiments and to enable better understanding of the constitutive behavior and modelling of rock fractures, from the DECOVALEX I project, four Tasks were defined for the DECOVALEX II project as follows.
Task 1:Numerical modeling of the effects of Nirex’s RCF Shaft excavation at Sellalfield, UK, in two steps. The 1st step was the numerical modeling of the coupled hydro-mechanical responses of the host rock mass to the RCF3 pumping test; and the second step was modeling the responses of host rock mass to the planned shaft excavation, including study of the excavation-induced disturbed zone (EDZ).
Task 2:Numerical study of PNC’s in-situ THM experiment at the Kamaishi Mine, Japan, which was an integrated investigation of a complete rock-buffer-heater system under in-situ conditions over a long period of heating-cooling time.
Task 3:Review of the state-of-the-art of the constitutive relations of rock joints.
Task 4:Production of a report on the current understanding of the coupled THM processes related to design and performance assessment of radioactive waste repositories.
The management style was the same as that for the DECOVALEX I project, with the Steering Committee deciding the Tasks to be studied and the project’s finances and schedule, SKI as the executive party managing the project finances, and the Division of Engineering Geology at KTH (Royal Institute of Technology, Stockholm, Sweden) serving as the project’s Secretariat. The funding organizations and research teams are listed in Table 1 and Table 2, respectively.
|Atomic Energy of Canada, Ltd., Canada (stopped in 1996)||AECL|
|Ontario Hydro, Canada (started in 1996, replacing AECL)||OH|
|Atomic Energy Control Board, Canada||AECB|
|Agence Nationale Pour la Gestion des Dèches Radioactifs, France||ANDRA|
|Environmental Agency, UK||EA|
|Institut de Protection et de Sûreté Nucléaire, France||IPSN|
|United Kingdom Nirex Ltd., UK||Nirex|
|Japan Nuclear Cycle Development Institute (former PNC), Japan||JNC|
|Swedish Nuclear Fuel and Waste Management Co., Sweden||SKB|
|Swedish Nuclear Power Inspectorate, Sweden||SKI|
|Empresa Nacional de Residoos Radioactivids, S. A., Spain||ENRESA|
|Center for Radiation and Nuclear Safety, Finland||STUK|
|Full name, Country||Acronym||FO|
|Centre d’Informatique Géologique (CIG), Ecole Nationale Supérieure des Mines de Paris, France||PSM||IPSN|
School of Civil Engineering, Kyoto University, Japan
Faculty of Agriculture, Iwate University, Japan
HAZAMA Corporation, Japan
Geological Isolation Technology Section, Tokai Works JNC, Japan.
|ITASCA Consultants s.a., France||ITAf||ANDRA|
|Technical Research Center of Finland, Communities and Infrastructure, VTT, Finland||VTT||STUK|
|Earth Science Division, Lawrence Berkeley Laboratory, USA||LBNL||SKI|
|ITASCA Rokmekanik AB, Sweden||ITAs||SKB|
|Division of Engineering Geology, Royal Institute of Technology, Sweden||KTH||SKI|
|CLAY Technology AB, Sweden||CLAY||SKB|
|Centre for Land Use and Water Resources Research, University of Newcastle, UK||UNEW||EA|
|Atomic Energy Control Board, Canada||AECB||AECB|
|Departmento Ingenieeria Hidràulica, Universidad Politécnica Valencia, Spain||UPV||ENRESA|
Six reports were generated during the time of DECOVALEX II project, published by SKI:
11 papers generated by the DECOVALEX II project were published in a special issue of the International Journal of Rock Mechanics and Mining Sciences, in 2001: Volume 38, Issue 1. Reference information about these papers generated by the research teams for the different Tasks in which they participated is listed at the end of the description of each Task in the following sections.