The Palmottu Natural Analogue Project

Transcription

1 The Palmottu Natural Analogue Project Technical Report Transport of Radionuclides in a Natural Flow System at Palmottu 1st 6-monthly Progress Report Contract No FI4W-CT , DG 12-WSME Compiled by Runar Blomqvistl and John Smellie2 Markku Paananenl $Task 1.1) Jan-Erik Ludvigson and Lasse Ahonenl (Task 1.2) Juhani Korkealaakso4 and German Galarza5 (Task 1.4) Bertil Grundfelt6 (WP 5) Geological Survey of Finland Conterra AB, Sweden Geosigma AB, Sweden Techical Research Center of Finland Universitat Politknica de Catalunya, Spain Kemakta Konsult AB, Sweden July 1996

2 CONTENTS I INTRODUCTION... 3 Task 1.1 Up-dating the structural model of the site... 5 Task 1.2 Hydraulic testing and interpretation... 8 Task 1.3 Hydrochemistry as an indicator of groundwater flow Task 1.4 Flow modelling and integrated evaluation of hydraulic and hydrogeochemical results Task 1.5 Low-contamination drilling Workpackage 5. PA-Activities I11 PROJECT DOCUMENTS Publications Internal Technical Reports Minutes. Planning Documents and Technical Documents ACKNOWLEDGEMENTS This document has been compiled by the Project Coordinator and the Task Leaders of Phase I of the Palmottu Project. It is based on contributions from most of the project participants; written contributions have been received from Veikko Hakkarainen. Juha Kaija. Pauliina Larnpinen and Timo Ruskeeniemi (GTK). Erik Gustavsson (Geosigma AB). Pedro Hernan (ENRESA). Berta de la Cruz. Elena Floria. Michael Garcia. Maria Turrero and Abel Yllera (Ciemat). Lasse Koskinen (V'IT Energy). Petteri Pitkhen (WTICI) and Jordi Bruno (QuantiSci).

3 I INTRODUCTION In December 1995 the Commission of the European Communities (the Commission) and the Geological Survey of Finland (GTK), Svensk Kihbriinslehantering AB (SKB), Empresa Nacional de Residuos Radioactivos S.A. (ENRESA) and the Bureau de Recherches Gblogiques et Minikres (BRGM) (the latter four jointly called the Contractors), agreed to carry out a project called "Transport of radionuclides in a natural flow system at Palmottu" under the Nuclear Fission Safety research and training programme (Contract No FI4W-CT , DG 12-WSME). The Project formally commenced on January lst, The four Project Contractors agreed to enter into a Consortium Agreement which specifies certain rights and obligations in carrying out the project work. The Contractors have the right to enter into associated contracts with the partners mentioned in the EC Contract (listed below); some of the Associated Contracts are already signed: * Finnish Centre for Radiation and Nuclear Safety, Finland (STUK); * RMC Environmental Ltd., United Kingdom (RMC-E); * University of Helsinki, Laboratory of Radiochemistry, Finland (UHRAD); * Technical Research Center of Finland, Nuclear Energy, Finland m Energy); * Technical Research Center of Finland, Communities and Infrastructure, Finland (V-TT/CI); * QuantiSci SL, Spain (QuantiSci). Major subcontracts to ENRESA and SKB, respectively, are the Centro de Ivestigaciones EnergCticas, Medioambientales y Tecnolbgicas, Institute de Medioambiente, Spain (Ciemat) and Conterra AB, Sweden. Additional subcontractors to ENRESA are the Universidad de Oviedo (UO) and the Universitat PolitCcnica de Catalunya (UPC) both from Spain, and to SKB are Geokema AB, Geosigma AB, Goteborg University, Intera Inc. (Intera) and Kemakta Konsult AB (Kemakta), all from Sweden. Kivikonsultit Oy, Posiva Oy and Suomen Malmi Oy, all from Finland, and Conterra AB, Geosigma Ab and SKB have acted as subcontractors to GTK. As defined in the EC Contract, the Palmottu Project is subdivided into two Phases (Phase I and Phase 11); commencement of the latter Phase, however, is dependant on the successful completion of Phase I. Phase I is scheduled from to and Phase I1 from to According to the Technical Annex of the Project, Phase I comprises the following Tasks related to Workpackages 1 and 5: Workpackage 1 : Understanding the natural flow system Task 1.1 Up-dating the structural model of the site Task 1.2 Hydraulic testing and interpretation Task 1.3 Hydrochemistry as an indicator of groundwater flow Task 1.4 Flow modelling and integrated evaluation of hydraulic and hydrogeochemical results Task 1.5 Low-contamination drilling Workpackage 5: Performance assessment exercise of Phase I The Initial Workshop, defined as one of the important milestones of the Palmottu Project, was held at SaariselH, Finnish Lapland on March 11-14, At the workshop, the Phase I programme of the Project was reviewed and up-dated. The main conclusions of the Workshop are presented as three Summary Minutes dealing with (1) hydrogeological testing and modelling, (2) hydrochemistry, and (3) performance assessment aspects (Korkealaakso and Blomqvist, 1996; Smellie and Blomqvist, 1996a; Grundfelt, 1996, respectively). During the

4 Hydrogeological Meeting at GTK, Helsinki on June 13-14, 1996, the hydrogeological programme was up-dated and detailed schedules drawn, as documented in the Meeting Minutes (Smellie and Blomqvist, 1996b). The schedules are presented as Appendices 2 and 3 of this Progress Report. The activities undertaken by the Project are described in detail for each of the major Tasks of Phase I in the following section of this report. In general, the progress made is in good accordance with the Technical Annex of the Project. Also, the manpower allocated to the various Tasks (see Appendix 1) is within the programme framework.

5 I1 SUMMARY OF WORK CARRIED OUT l[n Task 1.1 Updating the structural model of the site Objectives The target of the Task is to evaluate and integrate all available structural and hydrogeological data in order to produce an up-dated hydro-structural model of the Palmottu site. This model will serve as the starting point for the planning and execution of forthcoming hydraulic tests (e.g. cross-hole testing and tracer tests) and subsequent modelling activities. The conceptual hydro-structural model of Palmottu was up-dated based on additional data gathered from the site since 1994, when the previous model was compiled. The new data consisted of: * results from new boreholes R373 (1994) and R384 (1995); * hydraulic measurements (spinner, 16 holes; see Lampinen et al., 1996); * TV-logging (9 holes); * borehole radar results from R373 and R384 (Carlsten, 1996); * deviation measurements from 10 old boreholes (Suomen Malmi Oy, 1996); * results of principal component analysis (4 holes). The modelled block was extended to cover an area of 10 drilling profiles (profiles ) to a depth extent of 200 m below sea level. The starting point of the model was based on the results of the borehole radar survey, from which the orientations of reflectors, indicating fracture zones in the bedrock, are interpreted. In this work, the strongest reflectors were approximated as planes, and the intersections with every hole were calculated. Subsequently, all the data available (fracturing, hydraulic data, radar data etc.) were checked in order to find support for the intersections in every single borehole. Based on this examination, the most probable intersection depths in the borehole were determined. In some cases fracture zones coincided with lithological boundaries (structures V4 and V5) or high electrical conductivity were utilised (structures V1 and V2). After determining the intersection depths in the boreholes, the structures were digitised two-dimensionally using the Canadian PC-XPLOR and GEOMODEL-systems. The digitised structures were then transferred to Design Cad for three-dimensional modelling and visualisation. The basic idea of the up-dated model is similar to the previous model; the geometry of six subvertical and one subhorizontal structure were determined. However due to the new data, their geometry is now more accurate, and the model is in better accordance with the hydraulic information. The subhorizontal structure H1 proved to be the best hydraulic conductor of the model. Compared to the previous model, its orientation is slightly changed, and, according to borehole radar results, is formed by two planes with orientations 27"/18" and 17"/36", respectively. In Table 1, the lengths of the intersections of the structures and boreholes are presented; the hydraulically conductive intersections are boxed-in for clarification. Within this task, new field work for fracture zone identification and geometry was also carried out. Electrical resistivity and temperature were measured in four additional holes (R345, R354, R355, R356), and TV-logging in three old holes (R323, R337, R356). The work for statistical analysis of fracturing was started, and the first results with fracture orientations relative to schistosity are available from borehole R373. The precise levelling data covering 1

6 km2 around Palmottu was ordered from the National Board of Survey; the data should be available during June. TV-logging of the new geochemical borehole R385 and the short, supplementary borehole R386 was carried out. Borehole R385 was logged in two phases; the percussion-drilled part (hole length 0-65 m) and the rotary-drilled part (hole length m). In borehole R386, TV-logging covered the length interval m. Figure 1 shows an example of the results of the TV-logging. The up-dated hydro-structural model has been distributed (in a digitised form) to those copartners who need it for their own activities (Ciemat, Geosigma AB, UPC, VTTICI and VTT Energy). Forthcoming activities * Interpretation of precise levelling data in order to upgrade the regional frame for the present structural model. This work was planned to be completed by the end of June, but due to the delay of obtaining data, it will now be completed in September. * Continuation of TV-logging in additional boreholes in August-September. * Resistivity and temperature logging in the geochemical borehole R385 in August- September. * Continuation of statistical analysis of fracturing in September. * To supplement the structural model by taking into account all new data (deep borehole, fracture statistics etc.) and feedback from other tasks, in November-December. Fig. 1. Example of TV-loggin from borehole R385, 217 m to 223 m. The picture shows the borehole walls rolled out. An 6; cm open water-conductin fracture can be seen at m (indicated by an arrow), another fracture is visible at 217. f 0 m.

7 Table 1. Intersections of structures and boreholes (hole lengths). Hydraulically conductive intersections are boxed-in for clarification.

8 Task 1.2 Hydraulic testing and interpretation Objectives The hydraulic testing programme of this Task is targeted at identifying the most prominent groundwater flow paths of the Palmottu site and characterising their hydraulic properties. Various modelling approaches will be used in order to describe the hydraulic inhomogeneity of this rock mass. Approach Prior to the Initial Workshop in Saariselki, an evaluation of previous hydraulic results (mainly spinner tests) was carried out and a proposal for hydraulic connections at Palmottu was documented as a Technical Report of the Palmottu Project (Larnpinen et al., 1996). Based on this report a planning document (Ludvigson and Ahonen, 1996a) was prepared with a proposal for the following activities in 1996: * Installation of additional packers and measurement of hydraulic head in packed-off sections of boreholes * Additional flow meter (spinner) tests * Short-time cross-hole tests (connectivity tests) * Large-scale pumping test in combination with tracer test At the Saariselkii Workshop, proposals regarding hydraulic tests and their execution were presented and discussed, and a preliminary time schedule was worked out, as presented in the Minutes of the Hydrogeological Task Group. Following the Saariselki Workshop, more detailed proposals for the different test types were worked out. A proposal for the spinner measurements (Ludvigson and Ahonen, 1996b) and a proposal regarding the performance of the large-scale pumping and tracer test (Gustafsson and Ludvigson, 1996) were prepared. Additionally, a technical document regarding the evaluation of the cross-hole tests and the large-scale pumping and tracer test was also worked out (Nordqvist, Gustafsson and Ludvigson, 1996). These proposals were discussed in detail at the Hydrogeological Meeting in Helsinki Plans and schedules for hydraulic tests (Appendix 2) and modelling activities (Appendix 3) were agreed upon. Regarding the spinner measurements, it was recommended that the new deep borehole should be measured together with four of the following old 46 mm holes: R337, R356, R344, R354, R355, R323 and R341. Regarding the cross-hole tests, it was agreed to focus on four hydraulic structures deemed most important for the analogue studies, particularly the subhorisontal zone HI. A detailed test plan showing the proposed structures and pumping sections of the cross-hole tests is presented in Appendix 4. It was also proposed to perform a few tests in the new cored boreholes (076 mm), mainly to investigate the possibilities of (additional) subhorizontal zones in the central area. Regarding the large-scale pumping and tracer test, it was concluded that based on present knowledge this test should concentrate on the subhorizontal zone (HI). Generally, however, a more detailed location was not considered reasonable as long as the important cross-hole-testing data, and modelling results thereof, were missing. Based on the proposal by Gustafsson and Ludvigson (1996) the assumed subhorizontal zone should be pumped between double-packers from a centrally located borehole, and pressure measurements should be recorded in as many of the surrounding borehole sections as possible. Tracer break-through should only be measured in the pumped borehole section. However, as pointed out by the modelling group from

9 UPCICiemat, it would be of great advantage to be able to continuously measure the dilution of the tracers in the injection sections. This requires larger diameter boreholes than presently available at the site, at least 56 mm boreholes or larger percussion boreholes. The follow-up of an extensive tracer test will need more field time that can be guaranteed from the present schedule during the autumn of Because of the following reasons: (1) the incomplete grounds for the location and performance of a tracer test, (2) the fact that the results of the forthcoming cross-hole tests are still uninterpreted, and (3) due to the fact that there is a severe shortage of time before the approaching winter, the Workpackage Leaders, as well as the other experts of Workpackage 1, unanimously agreed on postponing the performance of the tracer test into the early field season of Results Conditioning: In January a campaign was arranged to recondition several boreholes which were blocked for various reasons. It was possible to re-open and successfully clean boreholes R336, R337, R345, R356 and R357. Two boreholes could not be re-opened and these can be considered permanently lost (R322 and R329). Installing of ~acker~: Pressures in previously installed packers decreased, partly severely, due to damage caused by freezing in winter. The water in the upper parts of the pressure tubes in boreholes R331, R318, R324, R333, R334, R336, R343, R346 and R348 had either frozen, and tubes disintegrated, or the valves at the top of the pressure tubes had been broken. During week 16 broken tubes and valves at the top of the boreholes were changed arid the packers were pressurised to 8 bars. After some time it was noticed that pressures were still decreasing in some packer systems, and during week 21 all previous valves were replaced with new ones, and the packers repressurised to 8 bars. Since then the pressure in the packer systems has been controlled weekly, to ensure reliable results. During April-June packers were installed in seven additional boreholes (R336, R357, R345, R356, R340, R341, R347, R323, R344); borehole R337 will be packed-off after conditioning of the casing is completed. Presently, part of the packer systems are connected to pressure vessels where nitrogen gas ensures constant pressures in packers. At the moment the total number of packed-off boreholes is 23 (Appendix 5), each borehole having 1-3 packers. Measurements of head value$: Water-level observations in open boreholes and packed-off sections of boreholes have regularly been measured by GTK. During the winter observations were carried out every two weeks, in April-June observations were made 1-2 times a week. Representative head values from packed-off sections have been recorded since week 21, and a first representative data set for distribution will be produced by early August. Internretation and modelling: Based on the up-dated structural model of the Palmottu study site, a three-dimensional channel network, with several two-dimensional planes, was constructed to fit the TRINET program by using the channel network generator TRINP3D. The work was performed as a co-operation between VTT-C1 and GTK. TRINET is a finite-element code for simulating advective and dispersive solute transport in three-dimensional networks of one-dimensional conductors. The most important local structures; V 1, V2, V4, V5, V6 and H1, were included in the model. In addition, some 30 centrally located boreholes were added as one-dimensional conductors. Present estimates of transmissivity and storativity, as well as boundary conditions, have been given for fracture zones in order to make an experimental design using the forward modelling approach for the forth-coming cross-hole tests and longterm pumping and tracer tests.

10 The UPCICiemat modelling group started their efforts by reviewing available structural and hydrogeological information of the study site, and continued by developing a preliminary hydro-structural framework for their 3-D modelling code TRANSIN to be used for the planning and interpretation of the forthcoming tracer test. Forthcoming activities The cross-hole-testing campaign will start in August and continue in September. The evaluation of the cross-hole tests will be carried out by Geosigma, V'IT-CIIGTK and UPCICiemat. V'IT- CIIGTK will utilize the data from the cross-hole tests in their inverse modelling approach, combined with analytical interpretations, to model the hydraulic conductivity distribution in the fracture system, as well as test the plausibility of the present structural model. UPCICiemat will complete and modify the hydro-structural frames defined for the modelling code TRANSIN in order to be able to test the potential localities for carrying out the forthcoming tracer test. Scoping calculations will also be needed to decide on the duration of the tracer test and to select pumping rate and the tracer injection sections. After the results of the cross-hole tests are available, the open technical questions of the tracer test will be discussed and agreed on. The number and type of tracers to be used, e.g. rhodamine and stable metal complexes, will be specified, partly based on detailed sorption studies by Ciemat. The type of tracer injection scheme to be used (particularly the time of injecting, either before start of pumping or at steady state) will be re-discussed and agreed upon during late Task 1.3 Hydrochemistry as an indicator of groundwater flow Objectives Groundwater chemistry is a powerful tool to establish and support the nature and direction of groundwater flow-paths in the bedrock. At Palmottu it is the intention to use existing hydrogeochemical databases, supported by on-going sampling and analysis of groundwaters from packed-off borehole sections at the site, to help validate and further refine the hydrostructural model which forms the basis of the hydrogeological modelling programme. Approach Hydrochemical studies documented from the Palmottu site show a variety of groundwater types, ranging from near-surface bicarbonate types to deeper saline varieties; 180-distinctive sulphaterich types representing cold climate recharge occur locally. Most of these data originate from open-hole sampling, but an increasing amount of additional data is being collected from packedoff borehole sections and should be available during the early autumn of 1996 at the same time as the first results from the deep geochemical borehole; the hydrochemistry will be used as an independent parameter to help validate the hydro-structural model. It may even be, in common with other site-specific studies carried out within national radioactive waste programmes, that the groundwater chemistry may represent the only quantitative way to produce a groundwater flow-path model of the Palmottu site. Evaluation of the hydrochemical data will involve: * a systematic quality assurance control of hydrochemical data (sampling, analysis, representativeness etc.); * characterisation of different groundwater types using standard hydrochemical plots and

11 Results principal component analysis; * groundwater mixing calculations; * geochemical equilibrium modelling and mass-balance reaction calculations; Hydrochemical data are presently being collected from isolated borehole sections to supplement existing open-hole data. Some 15 samples from various packed-off borehole sections have already been received; due to the very narrow hoses (12 mm) to be sampled, the usual working time to receive one sample is around 20 hours. Four first-strike samples (25 m, 67 m, 90 m and 406 m) and two samples (25 m and 67 m) for complete chemical characterisation (CCC) were received from the percussion hole part and the rotary-drilled parts of the deep geochemical hole. The analyses are under the way from these samples and the flushing water samples. First results from two parallel sample splits (Ciemat) are already available. Several samples of groundwater and fracture surface minerals from water-bearing fractures were taken for microbial studies for analysis at Goteborg University. The uppermost fracture zones at 25 m (Intera) and 67 m (Ciemat) were sampled for colloidal particles. No systematic evaluation of existing hydrochemical data has yet been conducted, apart from those conclusions already documented from earlier Palmottu studies. Work to refine and update available data sets is proceeding and standard hydrochemical plots are under the way. Isotope analysis for *H and 180 are presently being carried out on selected reference groundwater samples resulting from previous open-hole sampling campaigns; these data form the basis of reference data sets (together with geochemical and mineralogical data sets) to be used for future modelling purposes. Plans to tests the consistency of hydrochemistry and hydrogeology have been discussed and approved, and models using 13c data have been tested. More comprehensive efforts are presently limited by the scarcity of isotopic data (13C and 14C), and need to await results from the on-going sampling. Forthcoming activities The available borehole sections being sampled form part of the inter-borehole network of potential groundwater pathways which will be tested by the cross-hole test programme planned for August, Additional groundwater samples will be collected prior to and simultaneous to these pumping tests, with the goal of enabling a quantitative evaluation of groundwater flowpath directions based on changes or on lack of change in measured hydrochemical parameters. The complete chemical characterisation (CCC) of the various groundwater types of the deep geochemical hole will start at the beginning of July. The SKB-built mobile chemical sampling equipment and the laboratory wagon will be utilised for sampling. Samples for chemical analyses and environmental isotopes will be taken according to previously structured protocols. This campaign also include sampling for microbes (for Goteborg University) and colloidal particles (by Ciemat and Intera). The first workshop to initially address hydrochemical issues and their relevance in supporting the hydro-structural model will be organised for September. Modelling tasks and the comparison of hydraulic and hydrochemical models is scheduled for the end of this year. To test the consistency of hydrochemistry and hydrogeology, mass-balance reaction calculations (NETPATH) will be used in modelling chemical reactions along flow paths. 'C and 14C (residence time) results and natural conservative tracers will be used as additional criteria in testing the plausibility of reaction models and flow-paths. Finally, hydraulic and chemical flowpaths will be compared.

12 Task 1.4 Flow modelling and integrated evaluation of hydraulic and hydrogeochemical results Objectives This Task comprises: (1) flow modelling performed at regional, local and detailed scales, (2) evaluation and modelling of a combined pumping and tracer test, and (3) an integration and combined evaluation of all hydrogeological and hydrochemical information. The target is to define a natural flow path which will satisfy the needs of the forthcoming transport analogue study (Phase 11). Approach and Results The flow modelling work by VTT Energy is targeting at a detailed characterisation of deep groundwater flow under natural conditions at the Palmottu site. The numerical simulations will be performed with the FEFLOW code, which is based on the porous media model and finite element method. Although the scale of the local fracture zones is of prime importance for the analogue study, proper treatment of the hydraulic boundary condition calls for a regional flow domain scale. This model was defined based on available information on bedrock properties and water table observations, and it is confined by regional fracture zones. The size of the area is some 3 X 4 km2, and the vertical extent of the model is 700 m. The groundwater table, serving as the top boundary condition of the model, was defined for an area of S X 5 km2. Based on common experience from crystalline regimes in Scandinavia, the vertical extent of the regional fracture zones may exceed 500 m, whereas local structures may only reach down to 100 m. In this respect the information from the deep borehole may provide real site-specific observations concerning the local subvertical structures V1 to V6. For the modelling work, the regional fracture zones were given transmissivity values (depth depending) based on reference sites. For local structures, site-characteristic transmissivity values could partly be used. The finite element mesh for the regional flow domain and the appropriate files describing the hydraulic properties of the bedrock units (i.e., the fracture zones and the intervening rock matrix) and boundary conditions have been produced. In the finite element mesh, the fracture zones are presented as two-dimensional elements embedded in the three-dimensional mesh. Test computation runs have been made. A certain problem is caused by the fact that the wellcharacterised central area is quite small compared to the regional modelling domain, accordingly the calculated results are most representative for that part of the central area closest to ground surface. Information from the up-dated structural model and the forthcoming crosshole tests will be incorporated in model. Forthcoming activities The main focus of the VTT-CIIGTK approach will be to simulate (TRINET) the flow system within the central area of Palmottu. The idea is to explain the behaviour of flow in fracture zones, taking also into account the effects of the long period of open borehole conditions in the study site. The boundary values will be selected from the regional scale flow model provided by VTT Energy, and hydraulic parameters will be based on interpretations of the cross-hole tests. Head distribution of the structures will be taken from head measurements recorded from the packed-off sections in the boreholes. Different combinations of boundary conditions and hydraulic parameters will be tested during the modelling process. Regarding the evaluation of the pumping and tracer test, it was concluded at the Hydrogeological Meeting at Helsinki that two separate modelling efforts using different codes

13 will be performed (UPCICiemat and Geosigma AB). These modelling activities, however, have been postponed to the 1997 field season, but modelling to calibrate the tracer test will be carried out during Task 1.5 Low-contamination drilling Objectives The objectives are to improve and test drilling techniques which would allow the sampling of representative formation groundwaters before serious contamination by flushing (or open-hole effects) has taken place. In practice, hydrochemical sampling and restricted hydrogeological testing would be performed during drilling as soon as water-conducting fractures or fracture zones would be intercepted. This would be achieved by careful monitoring of important physical and hydraulic parameters such as flow-rate, hydraulic pressure, and flushing water loss and recovery. The major aspiration is that such representative groundwater samples will provide the reference hydrochemical (and environmental isotope, colloidal, microbial and organic) database at Palmottu, to which all existing and future groundwater data can be compared with and quantitatively evaluated. Background In the planning of the operation, previous experience from SKB, Posiva and ENRESA was integrated to arrive at an optimum method of approach. This resulted from workshop meetings held in Finland, Spain and Sweden during the period from October, 1995 to March 1996; drilling started on March 26th, Approach Planning the drilling and sampling of the deep borehole involved several stages: locating the deep borehole, locating a source for flushing water, and drilling and sampling the deep borehole. Drilling the deep borehole was to be Carried out in two stages. 1. Location of borehole: Based on several criteria: a) far enough away from the present drilled Palmottu site, b) to the east of the major subvertical structural discontinuity extending approx. N-S along the western margin of Lake Palmottu, and c) at a suitable inclination (- 70") such that the U-bearing horizons and the important conductive structures comprising the hydro-structural model of the Palmottu site can be verified. 2. Percussion borehole (- 80 m): The first stage of the drilling would entail a percussion borehole to around 80 m to collect "First-strike" samples of formation groundwater from the upper bedrock horizons. In particular, there would be a total absence of flushing water entering and contaminating the bedrock. 3. Source of flushing water: The second stage was to extend the percussion borehole to around 600 m using conventional air-lift rotary-cored techniques; this requires a source of flushing water. It was recommended that the flushing water be obtained from the bedrock itself to minimise contamination effects. For this purpose a nearby location to the deep borehole site should be selected. 4. Rotarv-cored drill hole: For conventional air-lift rotary-cored drilling, the percussion borehole is first required to be modified by reaming and casing. The major objective of the hole is to obtain rock core material and "First-strike" formation groundwaters relatively free from borehole activities.

14 5. Subsidiary rotarv-cored borehole: An additional cored borehole will be drilled parallel and close to the approx. 80 m percussion borehole. This will allow the collection of rock core material from this bedrock thickness, not possible from percussion drilling, for mineralogical characterisation. 6. Groundwater sampling: Collection of first-strike samples during drilling using downhole samplers designed for the purpose; samples to be analyzed for major elements and environmental isotopes. Following drilling, prior to complete chemical characterisation (CCC) from packed-off sections, the respective boreholes are to be flushed clean using nitrogen gas or pressurised water to minimise any oxidation effects. Results The drilling programme for the deep borehole R385 commenced in March 26th, 1996 with the successful completion three days later of the upper percussion borehole (diameter 165 mm; inclination 60") to a depth of 65 m. First-strike samples were recovered from the fracture zone at 25 m. After borehole completion, the sampled zones were confirmed following systematic hydraulic tests in the borehole conducted from packed-off sections (straddle lengths 2 m). Sampling for CCC was then carried out at 25 m and 34 m. The percussion borehole was then reamed and cased (l mm) to prepare for air-lift rotary-cored drilling. Preparation involved a securely cemented (La Farge) interface between the l mm casing and the bedrock at the hole bottom, and the installation of an inner 84/76 mm casing to house the drilling rods. Some problems were encountered with these installations, not least the presence of a large unstable fracture zone at 67 m observed at the very beginning of the rotary-cored drilling; these problems were solved by removing the outer casing, extending the percussion hole to m, and then re-casinglcementing the hole. However, before re-casing, a representative first-strike sample was taken from the 67 m fracture zone. To provide a flushing water supply for the rotary-cored drilling, two 165 mm wells (PK-1 and PK-2) were drilled, however with only limited success. Neither well could produce the volumes of water required for continuous drilling; in addition there were indications of increased salinity in the water in well PK-2. Since there was a risk that further drilled wells in the area may be similarly inadequate, a good alternative was to transport water from a wellproducing domestic source in nearby glaciofluvial deposits. Although the water differed from the formation groundwaters, its uniform chemistry, marginally oxidising character, low organic content,and the low amounts of tritium (- 8 TU), were a marked advantage over other less favourable sources such as Palmottu Lake. The flushing water was spiked with uranine (500 mg/m3). Drilling of the cored hole (76 mm diameter) re-commenced in May 10th and was terminated on June 2nd at a depth of 553 m, having accomplished the purpose of traversing the Palmottu uranium formation and passing the Eastern Granite. Four major fracture zones were intercepted at 90 m, 96 m, 222 m and 406 m; however, due to a malfunction in the downhole sampler, a representative first-strike sample was only collected from 90 m and a qualitative sample was received from 406 m. During drilling 240 m3 of drilling water were used with a recovery of 80%. The borehole has been subsequently cleaned by pumping spiked flushing water through the drilling rods. Indications are that -4% drilling water still remains in the borehole environment, and additional pumping is therefore necessary before CCC sampling is carried out. Drilling of borehole R386, located parallel to the upper percussion section of borehole R385, commenced in June 6th and was completed the. day after at a depth of m. The borehole has been cleaned. Boreholes R were logged using the SKI3 owned TV-imaging equipment on June 12th,

15 1996. An example of the high-quality images received is given in Figure 1 (on p. 6). Flow-meter measurements were carried out by Posiva Oy between June 10th and 19th at Palmottu. The results indicated five strongly conductive fracture zones with hydraulic conductivities in the order of 10-6m/s at 90 m, 96 m, 116 m, 222 m and 406 m. Of these zones the uppermost three had positive head values of approximately 3 m, whereas zone 222 m had an underpressure of 2 m and the deepest one was close to zero. Most of these fracture zones,are also visible from the fracture density logging of drill cores (Figure 2). Forthcoming activities Reporting of the drilling activities including the primary lithological information of the rock will be finished by early autumn. The detailed petrographical characterisation of the drill cores of the new boreholes will start in August as co-operation between GTK and Ciemat. / Granitic rocks A Mica gneiss Hornblende gneiss I/W\I Fracture zone Pyrrhotite U-mineralization Fig. 3 Lithology and fracture density recorded in drillcores from boreholes R385 and R386.

16 Workpackage 5, PA-Activities Preliminary plans for Workpackage 5, which extends over both phases of the project, were presented at the Saariselkii Workshop. Although the plans presented at Saariselkii were focused on activities within Phase I, a proposed goal for the work in Phase I1 was also presented. These items are summarised below. During the spring of 1996 the work within WP 5 has been focused on (1) planning of activities of Workpackage 5, and on preparation of (2) a mineralogical report of the main rocks types at Palmottu and (3) an internal project report aimed at giving an overview of data collected before the start of the Palmottu EC Project, i.e. before These reports and their intended use are further described below. To ensure close intergration the Leader of WP 5 has participated in the following meetings: * The Initial Workshop of the Palmottu Project at Saariselkii, March 11-14; * A meeting with GTK and University of Helsinki, Laboratory of Radiochemistry aimed at obtaining an overview of data collected at Palmottu before 1996, April 9-10; * The Hydrogeological Planning Meeting of the Palmottu Project, June Phase I According to the Technical Annex of the EC-Contract, Phase I of WP 5 consists of three parts: * Incorporation of PA expertise in Phase I; * Evaluation and systematisation of existing mineralogical, geochemical and hydrogeochemical data sets.based on PA needs; * Planning of Phase 11. The Technical Annex of Palmottu Project emphasises the involvement of PA-expertise in all activities of the Project, accordingly many scientist with a PA background participated in the planning work of the Saariselkii Workshop, e.g. from Kemakta, VTT Energy, QuantiSci, RMC-E, ENRESA, Conterra AB and GTK. The Workshop stressed the need of the Leader of WP 5 to be well informed about the activities within each Task of the Project. During January - March of 1996 a first document on the petrography and mineralogy of the main rock types at Palmottu was produced as a draft of a Technical Report (TR 96-03) of the Palmottu Project (Nissinen and Ruskeeniemi, 1996). The aim is to inform all partners of the mineralogy at Palmottu, and, also, to ensure that a common terminalogy will be used in the Project. Therefore, various partners will be asked to comment on the document before final printing. The data investigations performed prior to the EC Project, i.e. before 1996, are not compiled and organised in an easily accessible form. In order to facilitate the transform of data to project participants, it was proposed that a data report should be put together. An initial meeting with GTK and the Laboratory of Radiochemistry at University of Helsinki was held in April. The data report is to be regarded as a strictly internal project document. The report will contain descriptions of what kind of data that are available rather than a list of actual data. The report will also give reference to persons and documents where the data may be found. The report is planned to be completed during the summer 1996 and the Technical Committee will be given the opportunity to review the report. The detailed planning of the WP 5 activities of Phase I1 will be carried out during the autumn 1996.

17 Phase 11 The ideas presented for Phase I1 of WP 5 included the production of PA-oriented technical reports describing the contribution of the project to selected PA-relevant issues. It was identified that Palmottu has a potential to contribute at least to the following PA-relevant issues: * Mobilisation of uraninite, including the formation of secondary solid uranium phases; * Retardation of radionuclides, including interaction between dissolved species and rock minerals, sorption, matrix diffusion, etc. ; * The effects of climatic changes, in particular glaciations, on the rock and on groundwater system (flow directions, water composition, erc.). For each of these issues a report or a section of a report should be produced presenting the interpretations and evidence found at Palmottu. For some of the issues, notably the effects of climatic changes, the observations should be correlated with data from other sites in the region in order to put Palmottu in a proper regional context.

18 Publications Ruskeeniemi, T. and Blomqvist, R. (eds.), The Palmottu Natural Analogue Project, Progress Report Geological Survey of Finland, Nuclear Waste Disposal Research, 30 P. Internal Technical Reports Blomqvist, R. (edit.), Technical Annex of the EC-Project "Transport of Radionuclides in a natural Flow System at Palmottu (FI4W/CT95/0010). The Palmottu Natural Analogue Project, Technical Report 96-01, November 1995, 19 p. Carlsten, S., Detailed borehole radar measurements at Palmottu Study Site, Finland. The Palmottu Natural Analogue Project, Technical Report 96-04, March 1996 (draft), 45 p. Lampinen, P., Ahonen, T. and Blomqvist, R., Hydraulic Connections at Palmottu. Evaluation based on spinner tests and drawdown observations. The Palmottu Natural Analogue Project, Technical Report 96-02, February 1996 (draft), 30 p. + 4 Appendices. Nissinen, P. and Ruskeeniemi, T Mineralogy and Petrography at Palmottu. Main rock types. The Palmottu Natural Analogue Project, Technical Report 96-03, March 1996 (draft), 46 p. + 2 Appendices. Minutes, Planning Documents and Technical Documents AlmCn, K-E., Palmottu - Drilling and water sampling: Prerequisites, comments and questions. Palmottu Project, Technical Document, , 5 p. Grundfelt, B., Plans for Workpackage 5, PA-Activities. Palmottu Project, Initial Workshop at Saariselkii, Planning Document, , 2 p. Gustafsson, E. and Ludvigson, J.-E., Experimental design of the combined large-scale pumping and tracer test at Palmottu. Palmottu Project, Planning Document, , 4 p. + Figures. Korkealaakso, J. and Blomqvist, R., Minutes of the Hydrogeological Task Group Meeting at Saariselkii (Tasks 1.1, 1.2 and 1.4). Palmottu Project, Minutes of Initial Workshop, May 1996, 4 p. Lampinen, P. and Ludvigson, J-E., Hydraulic structures to be tested by the cross-holemethod at Palmottu in August - September Palmottu Project, Planning Document, , 4 p. Ludvigson, J.-E. and Ahonen, L., 1996a. Proposal to field hydraulic test programme at Palmottu in Palmottu Project, Planning Document, March 1966, 4 p. Ludvigson, J.-E. and Ahonen, L., 1996b. Spinner measurements in Palmottu in Palmottu Project, Planning Document, , 1 p. Nordqvist, R., Gustafsson, E. and Ludvigson, J.-E., Interpretation of cross-hole tests and large-scale pumping and tracer test. Palmottu Project, Planning Document, , 3 P. Smellie, J. and Blomqvist, R., 1996a. Conclusions of the Hydrogeochemical Discussions at Saariselkii (Task 1.3 and 1.5). Palmottu Project, Minutes of Initial Workshop, May 1996, 4 P. Smellie, J., Deep Borehole for Geochemical Studies. Palmottu Project, Planning Meeting in Madrid, Spain, Minutes, December 1995, 7 p. Smellie, J. and Blomqvist, R., 1996b. Hydrogeological Meeting at GTK, Helsinki, Minutes and Future Plans. Palmottu Project, Meeting Minutes, June 1996, 9 p.

19 Suomen Malmi Oy, 1996a. Boremac sivusuuntamittaus Palmotussa, tammikuu 1996 [Deviation measurements of boreholes with the Boremac method at Palmottu in January Palmottu Project, Technical Document, Suomen Malmi Oy, 1996b. Fotobor ja Boremac sivusuuntamittaukset Palmotussa kesikuussa 1996 peviation measurements with the Fotobor and Boremac methods at Palmottu in June Palmottu Project, Technical Document, ACKNOWLEDGEMENTS This work has been jointly funded by the: Commission of the European Communities, Geological Survey of Finland (GTK), Finnish Centre for Radiation and Nuclear Safety (STUK), Svensk Kknbrhslehantering AB (SKB), Empresa Nacional de Residuos Radioactivos S.A. (ENRESA), Centro de Ivestigaciones Energeticas, Medioarnbientales y Tecnoldgicas (Ciernat), Bureau de Recherches Gblogiques et Minikres (BRGM), Technical Research Center of Finland 0, Ministry of Trade and Industry in Finland, RMC Environmental and Posiva Oy. A critical review of the document by Dr. Henning von Maravic, the scientific officer from the Commission to the Palrnottu Project, is greatly appreciated.

20 Manpower Matrix (manpower in months per Task per Partner *) Plan for Phase I, Workpackagerrask G ~ K SKB ENRESA BRCM STUK RMC-M UHRAD YIT Ena. WTCI QUANTISCI Tofa1 I l. Understanding the natural flow system I I I 1.1 Updating the structural model of the site 1.2 Hydraulic testing and interpretation 1.3 Hydrogeochemistry as indicator of groundwater flow 1.4 Flow modelling and integrated evaluation of results 1.5 Low-contamination drilling 5. Performance assessment exercise of Phase I Project management/coordination/reporting TOTAL Manpower Matrix (manpower in months per Task per Partner *) Realised in Total * including subcontractors for SKB and ENRESA

21 FIELD ACTIVITIES AT PALMOTTU (Tasks 1.1, 1.2 and 1.3) April October 1996 of equipment for monitoring of hydr. head (Task 1.2) - sampling (Task 1.3) - pressure field monitoring (Task 1.2) - TV-camera (Task 1.1) Drilline and testing of new borehole Task 1.S - drilling of percussion bh, hydraulic testing (l), (Task 1.2) - drilling of cored boreholes - TV-camera (Task 1.1) - flow meter (Task 1.2) - chemical sampling (Task 1.3) Additional spinner measurements (Task 1.2) Cross hole testing (Task 1.2)

22 MODELLING AND PLANNING ACTIVITIES AT PALMOTTU (Task 1.4) July May 1997 Interpretation of cross-hole tests: Gcosigrna, UPClCiemat Long term pumping and tracer tests (L.T.P.T.): UPCICiemat (TRANSIN). Geosigma Flow modelling in regional and local scale: VlT Energy (FEFLOW) Flow modelling in local scale: VlT CUGTK (TRINET) Integrated evaluation of hydraulic and hydrogeochemical results: VlT CUGTK (inverse modelling) Hydrogeological Workshop Cornparision of modelling results and Technical Reporting Hydrogeological Repolt finalised

23 Appendix 411 Hydraulic structures to be tested by the cross-hole-method at Palmottu in August-September 1996 Pauliina Larnpinen and Jan-Erik Lugvigson The cross-hole-tests will be devoted toward the following structures: * H1 * v1 * western granite * eastern granite * other cases (the new boreholes and hydraulic (spinner) anomalies, which do not fit explained with the present fracture zone model Configuration for testing 1. The structure H1 Pumping Spinner C-H Transmissivity section m2/s 2. The structure V1 Pumping Spinner C-H Section Transmissivity m2/s

24 Appendix Western granite (structures V4 and VS) Pumping Spinner C-H Section Transmissivity m2/s 4. Eastern granite (structure V61 Pumping Spinner C-H Section Transmissivity m2/s 5. Other cases Pumping Spinner1 C-H Section Transmissivity Water cond. m2/s section

25 Appendix 511 Location of the packers at Palmottu installed in 1995, and the proposed structures V1 to V6 and H1 isolated by the packers. In some boreholes the packer configuration was changed, and the new depths are given within brackets. Borehole Packered Depth of packered Possible smcture(s) section (m l) removed after the first spinner measurement campaign 2, configuration changed after the first spinner measurement campaign 3, configuration changed after the second spinner measurement campaign

26 Appendix 512 Location of packers at Palmottu installed in BH NOTES STRUCTURES DEPTH OF PACKERED SECTIONS (m) R336 - V4, V Spinner-anom. 89.S-9 1.S, TV-camera H Spinner-anom , Fract. freq. (V1) > 10/m, TV-cam. - v1, v R357 - H Spinner-anom m, Fract. freq. V > 10/m, TV-camera S inner-anom., Fract.freq., TV-cam. V lh-119 m, Spinner-anom m - V1, V2, V4, V5, V6, V7, v9 R345 Spinner-anom m V3, V Spinner-anom m H S inner-anom., TV-cam., Fract. freq. V g-89 m Spinner-anom. Tv-cam m, Vl,V2,V5, S inner-anom m, Spinn. TV, V6, V7, V9 Pact. freq m - - * Packers not installed