Technical report 6/2015/ENG EXPERIMENTAL PROGRAMME AT BUKOV UNDERGROUND RESEARCH FACILITY Authors: Václava Havlová et al. ÚJV Řež, a.s. Praha, July 2015 |1| Authors: Václava Havlová Lenka Rukavičková Lubomír Staš Jaroslav Pacovský Karel Sosna Milan Hokr Miroslav Černík Pavel Špaček Jiří Mikeš Martin Milický Michal Polák Contents 1 Introduction ...................................................................................................... 11 2 Underground research facility (URF) Bukov ................................................. 12 3 Concept of the experiment and research proposal....................................... 14 4 Proposed experimental and research activities in Bukov URF ................... 15 4.1 Detailed geological and hydrogeological characterisation of the underground (URF area and crosscut tunnel area) .........................................................................................15 4.2 Testing of long-term monitoring methods of the processes in the DGR depth ........18 4.2.1 Long-term hydrogeological monitoring.............................................................18 4.2.2 Monitoring of changes in stress state and changes in behavior and character of underground workings over time ......................................................................................19 4.2.3 Monitoring of macro- and micro-seismicity ......................................................21 4.2.4 Displacement monitoring on faults ...................................................................23 4.2.5 Geophysical monitoring with focus on testing the methodologies for rock massif homogeneity verification in the vicinity of mine work ........................................................24 4.2.6 Monitoring of microbiological contamination and the gradual colonization of the environment by the microorganisms ................................................................................28 4.3 Testing of groundwater hydraulic models and radionuclide transport models within DGR fractured rock environment.......................................................................................30 4.3.1 Hydrodynamic tests in the boreholes ...............................................................30 4.3.2 Hydraulic model assessment ...........................................................................32 4.3.3 Programme of migration/tracer tests ...............................................................34 4.3.4 Determination of groundwater age and origin ..................................................42 4.3.5 Transport model testing ...................................................................................43 4.4 Testing of rock mass influence on changes of potential engineering barrier properties ..........................................................................................................................45 4.4.1 Corrosion experiments under anaerobic conditions in granitic host rock ..........45 4.4.2 The influence of microbes on degradation of engineered barriers and the penetration of microorganisms in bentonite ......................................................................49 4.4.3 Material interaction experiments (cement, bentonite) ......................................50 4.5 Testing of EDZ and EdZ formation and development in metamorphic rock in DGR depth 53 4.5.1 Different EDZ behaviour due to use of different excavation methods - I. .........53 4.5.2 Different EDZ behaviour due to use of different excavation methods - II. ........54 4.5.3 Different EDZ behaviour due to use of different excavation methods - III. .......56 4.5.4 Influence of internal rock structure and present structural domains on the URF behaviour and stability .....................................................................................................57 5 General requirements for ensuring implementation of monitoring, research and experimental work at the Bukov URF ............................................................ 58 6 Conclusions ..................................................................................................... 59 7 References ........................................................................................................ 60 List of figures: Fig. 1 Schematic position of Bukov URF (Dvořáková et al. 2014) ........................................13 Fig. 2 Schematic figure of borehole system for fracture network connectivity study .............36 Fig. 3 An example of dipole experiment instrumentation in discrete fracture (NAGRA 2000) .............................................................................................................................................36 Report number: Experimental programme in the Bukov URF SURAO TZ 6/2015/ENG List of abbreviations: DFN Discrete fracture network DGR Deep geological repository EB Engineering barriers ECPM Equivalent continuous porous medium EdZ Engineering disturbed zone EDZ Excavation damage zone GPR Ground Penetrating Radar GW Groundwater HDT Hydrodynamic Test HG Hydrogeological HLW High level waste NGS Next generation sequencing PCR Polymerase chain reaction P-T Press-temperature QA Quality assurance R&D Research and development REE Rare earth elements SC Supercontainer SNF Spent nuclear fuel SONS State Organisation for Nuclear Safety SRB Sulphate reducing bacteria SÚRAO Radioactive Waste Authority THMC Thermal-hydro-mechanical-chemical URF Underground research facility URL Underground research laboratory UV Ultraviolet light WPT Water pressure test 6 Report number: Experimental programme in the Bukov URF SURAO TZ 6/2015/ENG Abstract Construction of deep underground facility Bukov enables to perform scientific and experimental activities under conditions close to the condition of the deep geological repository. Until the final site will be selected and a confirmation laboratory will be built within this site, Bukov facility will be used as a test site for evaluation of host rock in the depth that is relevant to the considered depth of deep geological repository. In the presented report a proposal of monitoring, scientific and experimental activities is presented, divided into following topics: 1. Specification of geological and hydrogeological characteristics of URL. The activities will follow up recently launched geological characterization of the site. The outcomes will contain detailed description of lithological variability, structural data and description of ductile, ductile-fragile and particularly fragile structure, which has been intersected by the shaft. Furthermore, they will contain hydrogeological and hydrogeochemical characteristics of saturated fragile structures and underground water in the shaft. 2. Testing of long-term monitoring processes in the repository depth. Within this topic long-term monitoring of processes in the deep underground facility will be studied: • Long-term monitoring of hydrogeology • Monitoring of stress and underground facility changes in time • Monitoring of potential shifts on faults • Geophysical monitoring focused on methods studying the homogeneity of the rock massif • Monitoring of microbial contamination 3. Testing of hydrogeological models and radionuclide models in the fractured repository environment. The focus of this topic is to test transport models using different techniques and experiments in the fractured environment, considering also matrix diffusion Testing will use following activities/techniques: • Hydrodynamic tests in the boreholes • Evaluation using hydraulic model • Migration experiments in boreholes (advection transport, diffusion transport, fracture network connectivity) • Determination of underground water age and origin 4. Testing of host rock environment influence on engineering barrier properties under repository environment. The goal of the methods, mentioned in the report, will be influence of rock massif real conditions on engineering barrier materials (bentonite, cement). Complex experiments will be constructed in order to study several processes in the same time: corrosion, microbial influence, bentonite changes, etc. Following experiments are proposed: • Corrosion experiments 7 Report number: Experimental programme in the Bukov URF SURAO TZ 6/2015/ENG • Mock-up type experiments • Cement – bentonite experiment Besides from those experiments, will be studied the microbial influence on the processes in the engineering barrier, evaluating the rate of potential influence on corrosion and material property changes. 5. Testing of formation and development of EDZ an EdZ in metamorphic rocks under repository depth. The goal is to observe EDZ in time so that its development will be observed in relation to the other parameters (massif rheology, changes caused by heat loading, desaturation of the massif, etc.). Within the topic a broad range of techniques and methods was presented, starting with geophysical method towards hydraulic testing or use of geotechnical classification of rock massif. Selection of the activities will become as a base for R&D programme at URL Bukov. The basic presumption for implementation of mentioned activities are: • Development of supporting on-ground centre • Development of supporting technical and scientific team in-situ • Development of high quality contractors • Ensure DIAMO smooth and pro-active support • Ensuring of shaft working system • Ensuring that the experiments will not influence each other • Supporting laboratory research and modelling programme Keywords Underground research facility,