Nuclear waste management of the Olkiluoto and Loviisa power plants

Transcription

1 Nuclear waste management of the Olkiluoto and Loviisa power plants Summary of the activities during 2009

2 Images in the cover demonstrate the welding of the copper canister lid, inspection station for canister sealing weld, the substation of the canister lift and backfilling of deposition tunnel. Images are from the Final disposal and encapsulation -animation that was completed in 2009.

3 Abstract This report is a summary of nuclear waste management activities during 2009 for the Olkiluoto and Loviisa power plants. The summary includes a report of the status and actions of nuclear waste management by the power companies in 2009, as prescribed by the Nuclear Energy Act and Decree. In 2000, the Government made a decision-in-principle regarding Posiva s application for final disposal of spent fuel in Olkiluoto, Eurajoki. In 2003, the Ministry of Trade and Industry decided that the preliminary reports and plans required for the construction licence of the final disposal facility must be submitted during The construction licence must be applied for by the end of Preparations for the disposal of spent fuel are progressing in line with the long-term programme of research, technical design and development (abbreviated TKS in Finnish). The year 2009 was still part of the three-year period described in the TKS-2006 programme. The new TKS-2009 programme was published in the autumn of It contains an account of the planned actions and their preparations during At the end of 2009, the quantity of spent fuel in storage at the Olkiluoto power plant amounted to a total of 7,212 bundles containing an approximate total of 1,220 tonnes of uranium. At the same time, the quantity of spent fuel in storage at the Loviisa power plant amounted to a total of 3,961 bundles corresponding to an approximate quantity of 477 tonnes of fresh uranium. The layout of ONKALO was revised during 2009 to better correspond to the needs of vertical and horizontal disposal. In addition, the plans further specified the extent of ONKALO to be implemented before submitting the construction licence application in During the year, the access tunnel was excavated up to chainage The bedrock has been of relatively good quality. The EDZ 09 programme was established as a continuation of the EDZ 300 programme reported in the spring 2009 because the open questions outstanding from the previous programme required further investigations. In conjunction with the new programme, an investigation niche was also quarried at chainage The project report will be completed in early In canister design, a number of supplementary analyses were conducted during 2009 in order to verify that the technical requirements are met. The analyses will continue during Posiva produced a report on the current status of development work concerning the canister manufacturing process. It contains a summary of the development work for canister components and their associated manufacturing tests, a comparison of different manufacturing methods as well as an account of the current situation regarding manufacturing capabilities of canister components. Canister lid weld tests were conducted in 2009 in compliance with the preliminary welding instructions developed earlier. The development work for bentonite buffer has continued in line with the development programme produced by Posiva. The work has consisted of the bentonite buffer design work and studying its associated parameters as well as development of the manufacturing and installation processes for bentonite blocks. The most substantial operation during 2009 was that of preparing the backfill plan for deposition tunnels and reporting the work carried out during the TKS period approaching its completion. The plan is based on pre-compacted blocks surrounded by pellet backfill as well as a floor levelling layer, and the quantities of different components involved have been revised from the previous plan. The requirements have also been worked on with a view to developing the deposition tunnel excavation process. Three new boreholes were drilled in the eastern part of the Olkiluoto site in They were utilised for continuing the general characterisation work of the eastern area with respect to the geological, hydrogeological and hydrogeochemical properties of the bedrock as well as for studying the eastern lineament bounding the island of Olkiluoto. An investigation trench was made near borehole OL-KR51, and a geological mapping survey was carried out for it. The sampling of water from deep boreholes concentrated on holes drilled in Research was carried out in ONKA- LO during 2009 in order to establish the excavation induced changes and the properties of the bedrock surrounding ONKALO. The research activities in ONKALO included mapping, probing hole measurements, drilling studies, groundwater sampling, flow measurements and rock-mechanical measurements. Pilot holes were drilled in the access tunnel of ONKALO at chainages 3459 and The drilling of pilot holes and the associated hole surveys interrupted the excavation operations. As in previous years, the modelling of the Olkiluoto site is coordinated by the Olkiluoto Modelling Task Force whose work involves interpretation and modelling work of the different research disciplines (geology, hydrogeology, 3

4 geochemistry and rock mechanics), aimed at complementing the understanding of the site. The Olkiluoto Site Description 2008, the third successive description of the disposal site, was published in It includes updated models from all lines of research. The outline design phases of both the encapsulation plant and the repository ended at the end of 2009 with a report on the status of planning at that stage. The primary alternative is still an encapsulation plant connected to the repository by a canister shaft. The design and planning work for the disposal facility has been carried out in close co-operation with the implementation planning work for ONKALO in order to ensure the compatibility of facilities. The layout of repository facilities was updated in the plan on the basis of the latest bedrock data. The major tasks in 2009 aimed at producing the safety principles included in the work for compiling a report on Models and data. This report will be completed in Preparations were also made in 2009 for a summary report concerning the Safety Case, and it will also be completed in Biosphere-related work took place during 2009 according to the TKS-2006 programme, a separate biosphere work plan and the revised Safety Case plan. The goal of this work was to produce an updated description of the biosphere, forecasts for the future terrain and ecosystems, as well as radionuclide migration simulations and a dose assessment. Reports concerning these will be completed in early In parallel with the vertical disposal solution now constituting Posiva s reference solution, the horizontal disposal solution has been developed jointly with Svensk Kärnbränslehantering AB (SKB). The decision to continue the development work for the horizontal disposal solution was taken in the spring The main goal of planning during the current project phase is to resolve the questions identified as important during the previous phase of the study. Many of these questions are related to the buffer and its behavior. The long-term changes possibly caused by the construction of ONKA- LO are monitored using a special programme established for the purpose. The results of monitoring studies are published separately for each field of research as part of the series of Posiva s working reports. Posiva has produced a nuclear nonproliferation control manual that describes the nuclear non-proliferation control during the construction phase of ONKALO until The nuclear non-proliferation control manual was updated in The EIA procedure regarding the expansion of the repository, started in 2008, was completed when the Ministry of Employment and the Economy issued its statement in March 2009 regarding the EIA Report. Immediately after that, Posiva submitted its decision-in-principle application for depositing spent nuclear fuel from Loviisa 3. In September 2009, TVO and Fortum submitted a status report to the Ministry of Employment and the Economy regarding the state of preparations for the documents required for the construction licence application for the encapsulation plant and the repository. In the same connection, Posiva submitted draft attachments to the construction licence application. At the end of 2009, Posiva submitted to STUK (the Radiation and Nuclear Safety Authority) preliminary versions of the licensing documents referred to in section 32 of the Nuclear Energy Decree. The well-established practical measures regarding operating waste from Olkiluoto and Loviisa were continued, as were the research and study projects on this subject. The total amount of operating waste accumulated at the Olkiluoto power plant by the end of 2009 was 6,407 m 3. Of the waste originating from Olkiluoto, 5,244 m 3 has been disposed of in the VLJ repository in Olkiluoto. In Loviisa, trial operation runs of the liquid waste solidification plant using cementing/concrete techniques took place during The studies during operation of the Loviisa repository facilities continued in 2009 in line with the monitoring plan. Of the waste originating from Loviisa, 1,610 m 3 has been disposed of in the VLJ repository in Hästholmen. A report was produced during 2009 in Olkiluoto regarding the decommissioning costs of the OL3 plant unit. The results will be presented in the preliminary decommissioning plan for the OL3 plant unit. The studies carried out in Loviisa included one on the licensing process for decommissioning and the project comparing the separation of storage pool no. 2 for spent fuel as an independent unit to the dry storage of spent fuel in containers at the Loviisa power plant. 4

5 Table of contents ABSTRACT... 3 INTRODUCTION... 7 SPENT FUEL MANAGEMENT... 8 Operating principle and time schedule... 8 Present status of storage operations... 8 ONKALO Planning/design of ONKALO The construction of ONKALO Development of construction methods DEVELOPMENT OF THE DISPOSAL SOLUTION Spent fuel Disposal canister Bentonite buffer Backfilling of deposition tunnels and closure of the facilities Bedrock characteristics at the disposal site DESIGN AND PLANNING OF THE ENCAPSULATION PLANT AND REPOSITORY Encapsulation plant Repository PRODUCTION OF EVIDENCE IN SUPPORT OF THE SAFETY CASE Plan for the production of evidence in support of the Safety Case Performance of release barriers Bedrock as a release barrier Biosphere General research DEVELOPMENT OF THE HORIZONTAL DISPOSAL SOLUTION OLKILUOTO MONITORING PROGRAMME Rock mechanics Hydrological features Hydrogeochemistry The environment Foreign materials CONTROL OF NUCLEAR MATERIALS AND NUCLEAR NON-PROLIFERATION CONTROL

6 OPERATING WASTE MANAGEMENT The Olkiluoto power plant The Loviisa power plant DECOMMISSIONING REPORTS The Olkiluoto power plant The Loviisa power plant OTHER ACTIVITIES Management of quality and the environment Licences and permits Management of research data PROVISIONS FOR THE COST OF NUCLEAR WASTE MANAGEMENT LIST OF REPORTS

7 Introduction There are two companies using nuclear power to generate electricity in Finland, Teollisuuden Voima Oyj (hereinafter TVO ) and Fortum Power and Heat Oy (hereinafter Fortum ). According to the Nuclear Energy Act, TVO and Fortum are responsible for all procedures related to the management of the waste they have produced, and their appropriate preparation and related expenses. According to the Nuclear Energy Act, the Ministry of Employment and the Economy (abbreviated TEM in Finnish) decides on the principles to be followed in nuclear waste management. These principles were presented by the Ministry of Trade and Industry (abbreviated KTM in Finnish; its duties are now looked after by TEM) in its decisions of 19 March 1991, 26 September 1995 and 23 October 2003, and these decisions form the basis for both the practical implementation of nuclear waste management and the R&D work concerning future operations. Posiva Oy (hereinafter Posiva ) is a company jointly owned by the above companies. It is in charge of R&D work aimed at the final disposal of spent nuclear fuel as well as the construction and operation of the encapsulating plant and repository at a later stage. TVO and Fortum will separately take care of all operations related to the handling and final disposal of low- and intermediatelevel operating waste and to the decommissioning of power plants. Posiva is responsible for producing the annual report on nuclear waste management operations at the Olkiluoto and Loviisa nuclear power plants. This is the report on operations in 2009; it contains the report required by the Nuclear Energy Act and Decree on the status of nuclear waste management at the said power companies in 2009, as well as a report of the preparations made for the future costs of nuclear waste management. Teollisuuden Voima Oyj has two boiling water reactors in Olkiluoto, Eurajoki, each with a rated electrical output of 860 MWe. Olkiluoto 1 (OL1) was first connected to the national grid in September 1978, followed by Olkiluoto 2 (OL2) in February In 2009, the utilisation rate of OL1 was 97,0 % while that of OL2 was 95,1 %. The operating licences for the OL1 and OL2 power plant units and the low-level waste (MAJ storage), intermediate-level waste (KAJ storage) and interim spent fuel storage (KPA storage) are valid until the end of The operating licence for the Olkiluoto repository for operating waste (VLJ repository) is valid until the end of A third NPP unit is also under construction in Olkiluoto, i.e. the Olkiluoto 3 (OL3) unit. The Loviisa power plant of Fortum Power and Heat Oy has two pressurized water reactors, both with a rated electrical output of 488 MWe. The commercial operation of Loviisa 1 (LO1) began in May 1997, and that of Loviisa 2 (LO2) in January in 2009, the utilisation rate of LO1 was 96,0 % while that of LO2 was 95,4 %. The operating licences for the LO1 and LO2 plant units and for their nuclear fuel and nuclear waste management facilities are valid until the end of 2027 for LO1 and until the end of 2030 for LO2. The operating licence for the reactor waste repository (VLJ repository) is valid until the end of

8 Spent fuel management Operating principle and time schedule In compliance with the Nuclear Energy Act and decisions of the KTM, preparations are made for disposing of all spent fuel currently held at the Olkiluoto and Loviisa plants inside the Finnish bedrock. In its decision of 23 October 2003, the KTM changed the schedule of preparations for the disposal of spent fuel so that the preliminary reports and plans required for the construction licence for the encapsulation plant and the repository must be submitted in The final reports and plans must be available by the end of The final disposal operations are scheduled to commence in Before that, the temporary storage of spent fuel takes place on the power plant sites. In December 2000, the Government made a decision-in-principle regarding Posiva s application for final disposal of spent fuel in Olkiluoto, Eurajoki. Parliament ratified the decision almost unanimously in May The decision-inprinciple remains valid until 17 May A decision-in-principle concerning a new nuclear power plant unit (OL3) to be built in Finland was made in At the same time, a decision-in-principle concerning the construction of the repository for spent nuclear fuel as an expanded facility was made so that spent fuel from OL3 can also be disposed of in the repository. The nuclear waste management obligation of the OL3 plant unit only begins when the plant is operational. Preparations for the disposal of spent fuel are progressing in line with the long-term (TKS) programme of research, technical design and development published in 2000 (Posiva ). The three-year period including 2009 ( ) was described in the TKS-2006 programme published in The TKS-2009 programme, describing the activities planned for and their preparations, was published in September Present status of storage operations The fuel spent in Olkiluoto is temporarily stored in the power plant units and in the interim spent fuel storage (KPA storage) at the power plant site. In 2009, the available storage capacity in the KPA storage amounted to 7,146 storage positions. The KPA storage facility can accommodate the spent fuel of approximately 30 years worth of production at the OL1 and OL2 units. The KPA storage expansion project began in The site and construction work is scheduled for Overall time schedule for nuclear waste management. 8

9 so that the extension could be commissioned in early The premises of the expansion work are the exhaustion of storage capacity at the OL1 and OL2 plant units as well as the future needs of OL3. Three pools will be constructed in the expansion project. A new pool must be in operation for the OL1 and OL2 plant units in 2014, while the OL3 unit is expected to need its first pool in The expansion project is implemented as a structural alteration project of a nuclear facility. The OL1/OL2 operating licence has ample capacity for storing the fuel from these units. The permission for expanding the capacity and for storing fuel to accommodate for the needs of OL3 will be applied for in connection with the operating licence application for OL3. During the year being reported, the 30th refuelling operation took place at OL1 and the 28th at OL2. At the end of the year, the quantity of spent fuel in storage amounted to a total of 7,212 bundles containing an approximate total of 1,220 tonnes of uranium. Of all the bundles in storage, 6,150 were placed in the KPA storage, 502 in the water pools of OL1 and 560 at OL2. Additionally, 500 assemblies were in use in the OL1 reactor, with another 500 in use in the OL2 reactor. The figures include fuel placed in fuel rod racks (one per plant) used for the storage of damaged fuel rods. Spent fuel produced in Loviisa is also stored at the power plant and in the interim spent fuel storage. New spent fuel storage pools were last constructed at the Loviisa site in A decision has been made to equip the current pools with high-density racks. This will provide additional capacity until 2020 when the transportation of spent fuel for disposal is expected to start. Two new racks were procured in both 2007 and Two more racks will be procured in each of the years 2011, 2015 and At the end of 2009, the quantity of spent fuel in storage at the Loviisa power plant amounted to a total of 3,961 bundles corresponding to an approximate quantity of 477 tonnes of fresh uranium. Of that number, 294 assemblies were stored at LO1 and 336 at LO2. Spent fuel storages 1 and 2 held 480 and 2,851 bundles, respectively. Additionally, 313 assemblies were in use in the LO1 reactor, with another 313 in use in the LO2 reactor. 9

10 ONKALO ONKALO, the underground research facility, provides accurate information for the detailed design of repository facilities and for assessing the safety and construction engineering solutions. ONKALO allows for the testing of disposal techniques in actual conditions. The building permit application for ONKALO was submitted to the Municipality of Eurajoki in May 2003, and the construction work began in June The construction phase now in progress will advance to level -420 m. The technical facilities required for disposal operations will be located at level -437 m. Research activities have taken place in ONKALO ever since the construction work began. Planning/design of ONKALO The layout design work for ONKALO has been carried out in parallel with the design work for the repository. The layout of ONKALO was revised during 2009 to better accommodate the needs of the KBS-3H and KBS-3V solutions. The extent to which ONKALO will be implemented before submitting the construction licence application was also further specified in the plans. The preliminary plans for tunnel contract TU5 were produced during the summer The section of access tunnel included in tunnel contract TU4 ends at the approximate level of -420 m from where the access tunnel will continue to the technical facilities located at level -437 m. The TU5 plans include architectural, construction engineering and rock engineering design work. These plans will be submitted to the Radiation and Nuclear Safety Authority (STUK) for inspection in compliance with the preliminary inspection procedure at the beginning of 2010, two months before the subject contract is 10 scheduled to start. This preliminary inspection procedure was introduced at the TU4 phase. Planning during the on-going work on TU4 and inspection of plans to the extent required by the work took place in Planning during the on-going work on TU4, the contract that began in August 2008, will continue in early The planning of HPAC work and electrical work has continued for the on-going contracts (HPAC4 and E4) during the whole year as planning carried out during production. The construction of ONKALO During the year, the excavation of the access tunnel advanced to chainage The chainage number corresponds to the length of the access tunnel in metres. The personnel and ventilation shafts had already been drilled to level -290 m, and preparations for raise boring were made during 2009 up to the level of -437 m. The bedrock quality has been relatively good, and there has been little need for grouting. During the year, the tunnels were systematically reinforced using both bolts and fibre-reinforced shotcrete. This was, among other things, done in order to ensure appropriate safety at work in spite of increased stresses in the bedrock. The HPAC and electrical work for the access tunnel progressed as planned and reached chainage 3700 at the end of the year. There were no significant quality deviations or environmental damage during the year. The communication of construction work progress to public authorities has continued in compliance with what has been agreed. Development of construction methods GROUTING OPERATIONS Bedrock sealing in compliance with the grouting method developed in the R20 programme was tried out in the autumn The utilisation of this method will be further developed over the course of the normal production process. The purpose of the method developed is

11 to grout the bedrock using low-ph cement, smaller volumes of cement and fewer metres of holes remaining outside the tunnel profile. In addition, colloidal silica was added to the materials to be used for sealing, and it was tested in pilot grouting operations. MANAGEMENT OF EXCAVATION DAMAGED ZONES Excavation reduces the ability of bedrock to constrict the flow of groundwater. Part of this change is caused by the dynamic, immediate load exerted by the explosion. This is evidenced by so-called Excavation Damaged Zone, or EDZ. EDZ and their management is one area determined by Posiva as having a significant impact on the longterm safety of disposal. This is why EDZ management has a central role in Posiva s development activities implemented through different programmes and R&D projects. The EDZ 300 programme was implemented during and reported in Posiva s Working Report in the spring The production and verification methods tested during the programme proved to be feasible, although in need of certain further actions. That is why a new R&D project (EDZ 09) was established. Its goals included: development of the management of excavation operations, taking geological conditions and the deployed excavation parameters into account in the modelling of fracture formation, further studies regarding the use of ground penetrating radar, conduct of parallel comparison studies, improving the usefulness of ground penetrating radar as a verification tool, and testing of other geophysical methods providing comparison values. The EDZ 09 programme was established, among other reasons, because the open questions outstanding from the previous programme required further investigations. The purpose of the project is to further develop the methods and produce new information for determining the significance of EDZs. However, assessing the implications of EDZ on long-term safety is not included within the scope of this project. The functional objective of the project is to produce information that can be utilised for setting the requirements for taking EDZ into account in planning and implementation when the excavation of ONKALO continues. The fact that assessing the impact of EDZ on long-term safety may include considerable uncertainties will be taken into account when producing the material. The work in the project is aimed at introducing the EDZ verification and assessment methods and zone controlling procedures to excavation work before tunnel excavation work continues after TU4. The project was initiated in late 2008, and the excavation of the investigation niche (PL3620) began in the spring The location and cross-section of the tunnel were chosen to correspond, as closely as possible, to the disposal conditions. The excavation work was completed in the autumn, after which the measurements for verifying excavation damage and the associated comparison tests could commence. The field work was completed in early November 2009 and the processing of the results and their reporting could begin. The results required by the goals set were achieved by comparing the impact of different excavation methods and by developing the excavation process. It was shown that the excavation parameters affecting the degree of excavation damage can be identified and managed, although some suggestions for improvement were also made. The partial report regarding excavation will be completed in February The prediction of excavation damage using the calculation methods has, so far, not produced results useful for the project. This is because the geological conditions in the studied subject vary extensively, and testing them is very difficult and time-consuming. Measurements before and after excavation concentrated on the applied use of ground penetrating radar for observing excavation damage. This practice was started in the previous programme. It was found during the previous programme that the ground penetrating radar can be used to evidence that the excavation damage caused by well-controlled excavation can be detected with sufficient reliability. Observations made with the ground penetrating radar were compared with other results that were obtained from microseismic tests, hydrological measurements and geological mapping carried out at the same spots. The method proved to be even more suitable for a verification tool than was previously thought. This opinion is supported by both the ground penetrating radar observations and seismic measurements and other geophysical measurements made for comparison purposes. The measurement results material is extensive and requires plenty of cross-comparisons. The work will be completed in March The results of the project will be utilised for requirements management of future demonstration operations and for guiding the planning work. The development of excavation methods will continue by verification of drilling accuracy and the application of the methods on the construction of repository facilities. The utilisation of ground penetrating radar for verifying excavation damage will be further developed. 11

12 Development of the disposal solution The disposal solution foreseen for the spent fuel produced by TVO and Fortum is originally based on the KBS-3 solution developed SKB. The spent fuel bundles are inserted into copper-cast iron canisters and placed several hundred metres deep inside the bedrock. Compacted bentonite blocks are placed in the deposition holes between the rock and the canister. When the disposal operations are finished, all quarried facilities and access routes to the repository are backfilled and sealed off. The canister, bentonite and bedrock form a multi-barrier against the release of radioactive substances. The copper shell of the canister has excellent resistance against groundwater-induced corrosion, and the cast iron insert ensures mechanical durability. Bentonite restricts the access of groundwater to the canister surface and protects the canister from minor bedrock movements. The conditions surrounding the canister deep inside the bedrock will remain stable for long periods of time. The bedrock also protects the deposited fuel from external interference. Spent fuel It is important for the safety of disposal that it is known how quickly radioactive substances may be released from spent fuel and how quickly the fuel may dissolve when it comes into contact with water after disposal. Spent fuel mainly consists of uranium dioxide (UO2, about 96%). UO2 represents a reduced state of uranium where the oxidation state of uranium is U(IV). UO2 has low solubility and it is stable in reducing groundwater conditions. If water penetrates a damaged canister, the solubility of the UO2 matrix is a critical parameter when assessing the stability of spent fuel under disposal conditions. In oxidising conditions, oxidation of U(IV) to a considerably more soluble state U(VI) may occur. The tests regarding the reduction of U(VI) by Fe(II) in NaCl and NaHCO3 solutions (WR ) were completed in The tests were carried out under oxygen-free conditions in a nitrogen atmosphere. The purpose of the tests was to study the effect of Fe(II) in the solution on the oxidation state of uranium and observe any signs of the 12 reduction of U(VI). The tests showed that Fe(II) will reduce oxidation state U(VI) to U(IV). The results of solubility tests on uranium under high ph conditions and in saline water under reducing conditions (WR ) were also reported in The solubility tests indicated that the solubility of uranium increased with increased ph in a 0,01 M NaCl solution. During 2009, Posiva initiated investigations regarding studies related to high fuel burn-up that may be required and will be carried out jointly with its owners and the Swedish and Swiss nuclear waste organisations (SKB and Nagra). Disposal canister CANISTER DESIGN WORK A number of complementary analyses regarding canister design were conducted during 2009 in order to verify that the technical requirements are met. In these analyses, the initial data used, besides the geometric measurement data for the canister, are the physical, mechanical, metallurgic, thermomechanical, chemical and fracture-mechanical properties of the manufacturing materials. Some of these properties depend on the manufacturing process of the components and, for this reason, the measurement results from manufacturing tests have been included in the initial data for design analyses. On the other hand, the analyses on crack resistance and other technical analyses also set requirements for manufacturing, and the fulfilment of the respective specifications must again be verified with measurements and verifications. Requirements, manufacture and the verification of properties with demonstrations constitute a chain through which canister performance, qualitative and functional validation and the likely initial state can all be established. A rock displacement has been shown to be a critical load case for the durability of the canister insert. Therefore, this constitutes the load case determining the dimensions of the canister insert. The combination of magnitude, velocity and direction of the load determines the maximum crack corresponding to the lowest operating temperature of the canister material allowable in the

13 design parameters that will not grow to a harmful extent during loading. A safety factor is then determined for the maximum crack size thus determined, taking into account any inaccuracies in calculations, manufacture and crack size assessment. The resulting computational maximum size of fault is included in the manufacturing specification. NDT methods must be used for material integrity checks after manufacture to ascertain with sufficient reliability that no cracks exceeding this limit are present. Analyses and material studies aimed at establishing the durability of the insert of the canister were conducted in cooperation with SKB during These analyses and studies are expected to be completed and reported during Copper has proved to be such a ductile material that excessive crack growth will not occur with any realistically possible size of initial crack. Therefore, the critical factor for this material regarding its integrity requirements is corrosion resistance. However, the size of existing initial cracks is the design basis for dimensioning the cast iron insert, and rock displacement is the design load case for the canister structure. The breaking resistance of cast iron has been determined in mechanical breaking tests at different temperatures. These durability and crack resistance Copper tube manufacture using the pierce and draw method. analyses will be continued and further revised during CANISTER MANUFACTURE Posiva produced a report (POSIVA ) regarding the current status of development work for the canister manufacturing process. It contains a summary of the development work for canister components and their associated manufacturing tests, a comparison of different manufacturing methods as well as an account of the current situation regarding manufacturing capabilities of canister components. In 2009, Posiva and SKB co-operated in a project for developing the canister manufacturing techniques, both with respect to the copper exterior and the interior made of nodular graphite cast iron. Three different methods are being developed for manufacturing the copper exterior of the canister: pierce and draw, extrusion and forging. The pierce and draw method allows the manufacture of a copper canister with a bottom, whereas the extrusion and forging methods will produce a copper tube. The copper blanks for canister manufacture are cast in Finland. Two copper blanks were cast by Posiva in 2009 as part of the canister manufacturing method development work. In 2009, two copper canisters with bottoms were manufactured in Germany using the pierce and draw method. Three rings and the bottom were cut off from both canisters to analyse their mechanical properties and microstructure. One canister complied with the manufacturing requirements, but the other had a larger-than-permitted grain size at the bottom and tube wall sections. The results obtained from the manufacturing tests will be further analysed in early 2010, and the knowledge thus obtained will be utilised in preparations for the next manufacturing tests. No tubes were extruded in 2009, but the development work for the method continued as further tests were carried out using an earlier extruded tube. The extrusion process was also modelled, and laboratory-scale extrusion tests were carried out on the basis of this modelling work. The objective was to find, with the help of modelling and extrusion tests, such parameters for the extrusion process that would produce tubes with a more homogenous microstructure. The results of the modelling and extrusion tests will be utilised in the next full-scale extrusion tests. One copper tube was forged in Sweden at the end of The tube will be examined and some results from this manufacturing test will be available in The grain growth in tubes manufactured using both the extrusion method and the pierce and draw method was studied by varying the temperature and duration of heat treatment in the annealing furnace. The results obtained from the studies will be utilised for developing the respective manufacturing methods. The development work for cast iron inserts of disposal canisters continued in Finland, Sweden and Germany. Two BWR canister inserts were cast in Finland, while one PWR canister insert was cast in Sweden and five in Germany. The BWR canister inserts are required for 13

14 nuclear waste produced in the plants now in operation in Olkiluoto, while the PWR canister is similar to the EPR canister that will be required for disposal of spent fuel produced at the OL3 plant. Of the two BWR canister inserts cast in Finland, one complied with the manufacturing requirements regarding material properties, mechanical properties and the degree of formation of graphite nodules, but the channels for spent fuel, formed in the casting process, were twisted and molten iron had entered the fuel channels in both castings. Therefore, neither insert complied with the manufacturing requirements in all respects. One PWR canister insert was cast in Sweden. The examination of the insert has not been completed yet, but the preliminary results indicate that the material properties and geometry seem to be compliant with the requirements. Five PWR canister inserts were cast in Germany. The first one failed. The others complied with the requirements regarding the straightness of fuel channels. Three inserts had good mechanical properties and microstructures. The examination of the last cast insert has not yet been completed. CANISTER SEALING The development work for the canister sealing method concentrated in 2009 on the final reporting of results from the series of test welds made in the previous year and on the development work planned on the basis of these results. The demonstration series and its results are discussed in closer detail below in the section entitled Canister demonstration project EB-DEMO. The preliminary quality requirements for welds have been produced, and they will be reported in the summary report for welding development work in early The studies on Electron Beam Welding (EBW) have continued at the Department of Materials Science of the Tampere University of Technology. These studies concentrate on producing welds free of defects and their properties. The results will primarily be used for optimising the welding process. The preliminary results indicate that the quality of cover sealing welds is 14 reasonably good; the smallest dimension of solid material in individual welds has been at least 43 mm and the minimum material thickness is 35 mm in all canister welds. The minimum material thickness must be at least 40 mm in 90 % of canister welds. However, the weld penetration is unnecessarily deep, causing deformation and thus also residual stresses. Two canister lid sealing weld tests were conducted in early 2009 in compliance with the preliminary welding instructions developed earlier. These tests were a continuation of the welding parameters optimization process initiated in 2007, and they were also made for the purpose of establishing a suitable window for these parameters. The process of analysing the non-destructive tests carried out on these test welds is in progress. The destructive tests of these lid welds will being in The report of the residual stress test measurements initiated in 2006 was completed in The stresses measured in EBW welds were higher than expected. However, the measurement methods used provide too conservative results compared with reality. Therefore, the measurement results will be re-analysed using more accurate material models. In order to establish these material models, a study was initiated at the Tampere University of Technology with the objective of establishing the elastic-plastic behaviour of the copper and EBW weld used for the disposal canister for the purpose of determining the correction for elasticity. The empirical part of the study has been completed, and the report will be produced during The welding tests associated with studying the residual stresses in EBW welds began in the spring During the latter part of the year, the tests were supplemented by welding covers on 890 mm and 450 mm long tubes. The purpose of the tests was to establish whether residual stresses can be sufficiently influenced by varying welding parameters. The temperatures and weldinginduced deformations during the welding process were measured. These results will be used for verification of the numerical modelling of the welds. The numerical modelling of welding-induced deformations and residual stress will continue in The welded lids can later be used for the possible tests on the stress-releasing annealing process. The earlier tested preliminary welding instructions were deployed in all welding tests. The instructions have been found to be functioning well and easy to apply. Tests on radius measuring instruments have been carried out with the objective of adjusting the EBW equipment. The measuring instruments allow for documenting the properties of the electron beam and verifying the quality of radius. As a result, the reproducibility of the system can be further improved. The work for producing instructions and their inclusion in the preliminary welding instructions began in 2009 in preparation for introducing the measuring instrument to production use. Another focus area in the canister sealing process was that of increasing the depth of knowledge in the Friction Stir Welding (FSW) method patented by SKB and accumulation of related experience by carrying out FSW lid welds at SKB s canister welding laboratory in Oskarshamn. One lid was welded to a 250 mm long tube in the spring After that, the weld was subjected to NDT by SKB. The destructive tests in the project will continue in early 2010 when the final report on these tests will also be produced. The tests have allowed Posiva to gain experience concerning the feasibility of the FSW method and equipment while the Finnish level of expertise in weld research has also been considerably improved. CANISTER INSPECTIONS A co-operation agreement on inspection activities was signed in 2009 between SKB and Posiva. Within the framework of the agreement, the reliability of inspection procedures will be assessed in the NDT Reliability IV/V project that mainly concentrates on studying the reliability of inspections carried out by automatic mechanisms, as well as on the influence of human factors on inspections. It was found in the earlier NDT Reliability II/III project that faults

15 can be readily detected using US techniques but the inspection system has to be evaluated in cases where the orientation of the fault is unfavourable for detection. A qualification procedure compliant with the recommendations of the ENIQ (European Network for Inspection Qualification) was also analysed in the project. On the basis of these results, the NDT reliability IV/V project will concentrate on the assessment of certain parameters (such as those associated with inspection instructions and faults to be detected). The work of compiling lists of faults found in all canister components and welds has been initiated for the purpose of developing the inspection procedures. This work will be supplemented by metallographic tests on the detected fault indications. The reliability of the NDT methods applied will be assessed, in part, on the basis of these results. This work will continue in Four copper tubes were inspected in 2009 using US and eddy current testing methods and visual inspections. The inspections revealed a few surface defects, mainly in the eddy current tests and visual inspections. The depths of these faults are still being analysed, and the work will continue in The eddy current testing technique for copper tubes has been developed to detect any faults on or close to the surface. The process of visual inspection of copper components has been further developed, and the detection capabilities of the method will be assessed in The technique for analysing weld inspection results has been developed with the main objective of detecting faults, but also for the purpose of determining the size of faults using mainly the US, eddy current and X-ray methods. A Probability of Detection (POD) curve was calculated for the X-ray method used on the basis of measurements. The POD curve allows for the assessment of the smallest radial defect detectable with a dimension of about 1 mm. This work will continue in future years, and the goal is to develop similar assessment methods for different methods (US, eddy current and visual inspection). The work in 2010 and 2011 Installation of the canister tube on the rotary table of the welding chamber for a welding test. will concentrate on assessing the process of determining the fault dimensions. Welds produced with the friction stir welding method were also inspected during 2009 using US and eddy current methods. The inspections produced certain fault indications in areas where welding parameters had been adjusted well outside the optimal parameter range. Fault indications were received both at the root of the weld and close to its surface. Preliminary instructions for US inspection of the cast-iron insert were produced. The feasibility of the instructions was tested by inspecting two full-size inserts, and the principle of continual improvement will be applied to rectify any defects as experience is accumulated. The inspections of inserts revealed certain types of faults, primarily close to the outer surface. The measurement results of faults present close to the surface will be studied using metallographic methods, and their origin will be determined. In addition, one clear fault indication was received close to the bottom of one insert, and the defect could be identified as an air bubble of about 20 x 20 x 30 mm in size. A report has been produced regarding the inspection techniques for welds and components, and it will be published during the first half of The report will discuss the methods used for inspecting the welds and the components. 15

16 Method developed by Posiva for determining the location of the close corner of the channel in the insert using phased US techniques. CANISTER DEMONSTRATION PROJECT EB-DEMO During , Posiva implemented the EB-DEMO project aimed at demonstrating the actual standard of canister sealing and seal inspection technology prevailing in the company at that time. The parameters for the welding process were chosen on the basis of results obtained from earlier welding tests, and they were not altered during the series of tests conducted even though the tests involved welding three sets of four lid welds each. All welds in the first set had plenty of defects bad enough to cause rejection; the second only had a few, while all welds in the third set were acceptable. It is obvious that the defects causing rejection were not caused by minor disturbances to the welding process. Instead, the impurities deposited on the test pieces to be welded caused a number of welding faults, and the number of these faults decreased when the quality and cleanliness of the pieces was brought up to the standard required for EB welding. Metal sheets were also welded in conjunction with the demonstration. These welds confirmed the opinion that the quality flaws detected in the cover welds during the demonstration were to do with the surface quality of components, not with the actual EB welding process. The final report was produced in It states that acceptable welds can be produced on the copper shells of canisters using the current competence in EB welding and NDT techniques, and that their acceptable quality can be reliably verified. Bentonite buffer The development work for bentonite buffer has continued in line with the development programme produced by Posiva. The work has consisted of the bentonite buffer design work and studying its associated parameters as well as development of the manufacturing and installation processes for bentonite blocks. The requirements concerning the buffer have been compiled as a design basis. They have been used as the basis for assessing and updating the reference plan produced earlier for the buffer. Development work for the buffer has been initiated. It involves studying alternative solutions for parts of the buffer structure. Studies have been initiated for obtaining the input values for the planning. They involve studies on how the buffer blocks start swelling when wetted with water in conjunction with their installation, as well as studies on filling the space between the bedrock and buffer blocks using different materials. The development work for buffer block manufacture has included studies on the suitability of isostatic compression methods for the manufacture of large bentonite blocks. The feasibility of manufacturing parameters has been studied and development work for the mould structure has been continued by the small-scale manufacture of test blocks. The results obtained have resulted in the decision to manufacture medium-sized (35 % of full-scale blocks) and large (70 %) bentonite blocks. The isostatic compression method can be used to manufacture several blocks at time. Pressing plants of sufficient size have been sought in this connection to enable the manufacture of full-scale blocks. The development work for bentonite buffer installation techniques has involved testing the impact that the size of blocks has on their ease of installation. The test results have also been used as the basis for investigating the functionality of installation equipment and the effect of deviations in the deposition hole on the installation clearances required. The installation tests were carried out using full-scale objects. Both small and large blocks were used. The small blocks weighed 35 kg and they were laid out to form ring-shaped and cylindrical blocks of full size which were then installed in one package. The large blocks were tubular and cylindrical blocks with a maximum weight of 5,000 kg. The material used for the blocks was a concrete mix with the same weight and surface quality as bentonite blocks. A full-scale deposition hole of modular construction was manufactured of steel. Its parameters can be adjusted to correspond to the dimensions and tolerances of holes drilled in the bedrock. 16

17 Bentonite blocks produced by the isostatic compression method at the VTT research laboratory. Backfilling of deposition tunnels and closure of the facilities The most substantial operation during 2009 was that of preparing the backfill plan for deposition tunnels and reporting the work carried out during the TKS period approaching its completion. The plan is based on pre-compacted blocks and side pellets as well as a floor levelling layer, and the quantities of different components involved have been revised from the previous plan. The requirements have also been worked on with a view to developing the deposition tunnel excavation process. The final report of the Baclo programme, produced jointly with SKB and published during 2009, was used as the basis for reporting. A three-year programme is under preparation for the purpose of verifying the backfilling material plan; part of this work will be implemented jointly with SKB. During the year, tests were carried out at the Äspö bentonite laboratory that form the basis for studying the contribution of tunnel seepage waters to the behaviour of backfill materials. Background information will also be obtained in this connection regarding the need to restrict the flow of seepage waters in the tunnels. Regarding the production of backfill material, preliminary tests for the serial production use of the uniaxial compression method have been initiated. The details studied in these tests include the impacts of pressure, water content and temperature on the end result and block quality. Regarding the installation of backfill material, preliminary tests have been carried out for the 40:60 mix of bentonite and crushed rock to be used for floor levelling. The results will help plan the actual floor installation tests. The installation of blocks using the modular installation method has been planned, and the results of this work were utilised when producing the plan for backfill material. The preliminary testing of the backfill material plan regarding its different components will take place in 2010, after which the actual implementation planning for different prototypes will commence. Tests have been carried out to study the chemical composition of different backfill materials, particularly that of alternative materials. Laboratory-scale results have been obtained of the selfhealing capability of the backfill material, and these results will be utilised for, among other things, the assessment of alternative materials. The smallscale concrete tunnel tests have been reported and the erosion properties of different materials (Blocks of Friedland clay and blocks of 40:60 bentonite and crushed rock mixture) compared in a situation where the tunnel has been filled as full of blocks as possible. The tests will continue in The principal plan for the plugs to be inserted at tunnel mouths was published in early The preliminary plan for the closure of other facilities will not be completed before 2010 because all the basic information for the process has not been obtained yet. Posiva is also monitoring the closure-related project of URL, the research laboratory of AECL of Canada where two combination plugs (concrete structure combined with a mixture of bentonite and rock aggregate) are constructed at a depth of several hundred metres down the shaft. Bedrock characteristics at the disposal site INVESTIGATIONS CARRIED OUT FROM GROUND SURFACE Three new boreholes, OL-KR51, OL-KR52 and OL-KR53, were drilled in the eastern part of the Olkiluoto site in The 17

18 Locations of boreholes OL-KR1 OL-KR53. borehole depths were 650 m, 427 m and 300 m, respectively. Boreholes OL-KR51 and OL-KR52 were utilised for continuing the general characterisation work of the eastern area with respect to the geological, hydrogeological and hydrogeochemical properties of the bedrock. Borehole OL-KR53 was primarily drilled for the purpose of studying the eastern lineament bounding the island of Olkiluoto. The research data obtained from the boreholes is required for designing the repository facilities. Of the borehole studies, flow measurements and geophysical standard measurements were already completed during The chemical analyses of groundwater samples will be carried out in One investigation trench, OL-TK17, was excavated in the eastern part of the site during The trench runs almost parallel to borehole OL-KR51 in the northern part of its ground level projection. Geological mapping of the exposed rock surface was produced. Soil samples were also taken from the trench at 25-metre intervals. The results obtained from the trench will be used for updating the geological model. The data obtained from soil samples will also be utilised for the soil thickness model. In 2009, the borehole studies concentrated on the eastern part of the site. Geophysical measurements in the boreholes continued as in previous years. In addition to geophysical standard measurements, all boreholes drilled in 2008 and 2009 were investigated using a video camera. In addition, measurements were carried out for establishing the electrical conductivity of the bedrock. The geophysical results are used as complementary information when updating both the geological and hydrogeological site model. Hydrogeological studies in the survey site continued by measurements of flow characteristics in the bedrock from holes drilled in the eastern survey area. The measurements were taken using both the Posiva Flow Log and a HTU (Hydraulic Testing Unit). The HTU measurements concentrated on the depth range of metres. Transverse flow measurements continued as part of the recharge test monitoring measurements in short bedrock holes OL- PP66 OL-PP69 drilled in the vicinity of boreholes OL-KR14 OL-KR18. The measurements were taken to establish the effect of pumping on the natural state of flow prevailing in the boreholes. The results will be reported in 2010, and they will be used for producing groundwater flow models and as basic information for planning other studies, such as water sampling programmes. The sampling of groundwater from deep boreholes concentrated on boreholes drilled in The work concentrated in particular on trying to obtain samples of saline groundwater below a depth of 400 m and from fractures of low water conductivity. Sampling has been continued to establish the locations where saline groundwater is present. Microbes and gases dissolved in groundwater were another area of interest. Water sampling from the borehole drilled under the seabed (OL-KR47) was completed. The recharge test start- 18

19 ed in 2008 is continuing. The chemical changes possibly occurring in groundwater have been monitored through sampling campaigns. The results for the first year of testing will be reported during the spring The results will be used for updating the hydrogeochemical model. STUDIES CONDUCTED IN ONKALO Research was carried out in ONKALO during 2009 in order to establish the excavation-induced changes and the properties of the bedrock surrounding ONKALO. Research data was produced during the year on the quality and properties of the bedrock as well as on its hydrogeological and hydrochemical properties. The research data was used inter alia for planning grouting and reinforcement operations and for further specification of different models describing the properties of the bedrock. Most of the studies were conducted while excavation operations were in progress; excavation was only suspended when pilot boreholes were being drilled. The research activities carried out during excavation operations included mapping, probing hole measurements, drilling studies, groundwater sampling, flow measurements and rock-mechanical measurements. The work for mapping geological characteristics and seepage water continued as the excavation work progressed. During the early phases of geological mapping, information is collected for the immediate needs of the excavation and planning operations, and later when excavation has progressed further, mapping is done for documenting the types of rock, bedrock quality, detailed geological characteristics and seepage water volumes. By the end of 2009, systematic geological mapping had progressed to chainage Measuring weirs were utilised for seepage water measurements; they are used for metering the volumes of accumulated water as well as its chemical properties (ph, EC). Probe holes are drilled in the tunnel profile at approximately 20-metre intervals. Measurements related to ingress of groundwater, water loss and flow rates are regularly performed in the holes. The total exit flow rate of the hole is also measured in connection with water loss. The flow rates of probe holes will be measured if the hole output exceeds 30 ml/min. All flow measurement results obtained from ONKALO will be utilised when producing a more detailed hydrogeological model of the Olkiluoto bedrock. During 2009, pilot boreholes ONK- PH10 and ONK-PH11 were drilled in the access tunnel at chainages 3459 and The boreholes were about 180 m and 130 m long. The excavation work was suspended for the duration of drilling the pilot holes and carrying out the associated hole studies. Normally, the pilot boreholes are subjected to geophysical measurements included in the standard regime, optical imaging, flow logging, water loss tests and water sampling. For borehole ONK-PH11, the tests were supplemented with acoustic imaging, and the water loss measurements were taken using Posiva s own equipment. In 2009, the pilot and probing hole measurements were supplemented by flow logging in new groundwater stations drilled in ONKALO, in shaft grouting holes (mainly for the purpose of planning grouting work) and at chainage 3620 in connection with EDZ studies. The measurements of state of rock stress continued as in previous years. The measurements began with new preliminary tests for checking the operation of the measurement instrument in the conditions prevailing in the shaft at a depth of 265 metres. The purpose of the method is to measure the secondary stress field surrounding the quarried space. This allows for computing the in situ state of stress prevailing in the area. The tests were carried out by first drilling out strain gauges installed in the bedrock and the LVDT sensor cells later installed in the same locations. The rock samples with strain gauges were also tested in the biaxial cell. The method was utilised in late 2009 for determining the state of stress in research facility 3 (EDZ investigation niche). In addition to the above, the work for determining the state of rock stress continued with convergence measurements at the lower ends of shafts. They were carried out at inlet air shaft levels 180 m and -290 m. The purpose of the measurements is to monitor the rock deformation caused by raise boring. Several factors, including the shape of the tunnel and the penetration point of the shaft, cause interference to the measurements. An optical fibre measurement system was installed around the theoretical profile of the shaft at the end of the inlet air shaft at level -180 m to supplement the conventional convergence measurements. The purpose of this instrumentation was to monitor the deformation of the shaft during raise boring. Temperature variations and deposition of airborne dust on the optical fibres proved problematic for the instrumentation. The measurement results did not allow the determination of the degree of deformation. The monitoring of bedrock temperature changes continued in the first research facility (PL1475). The temperature monitoring system installed in the autumn 2008 has now operated systematically after the malfunctions observed in the spring The purpose of these measurements is to monitor the transfer of heat into the bedrock as the temperature of the quarried rock changes. The planning of investigation niche studies continued in 2009, and some of the studies were initiated. The niche studies carried out in ONKALO include: rock spalling studies (POSE), hydrogeological interaction test (HYDCO), sulphate reduction test (SURE), and the test for establishing the retention properties of the bedrock (REPRO). Of these, the HYDCO and REPRO tests are at the planning stage, and work in the tunnel will commence during The first research holes for the SURE test were drilled, and the basic studies regarding them were completed. The study plan for POSE is also ready and work in the tunnel has began. MODELLING WORK The Olkiluoto Modelling Task Force (OMTF) coordinates the modelling work of the Olkiluoto. The work of the OMTF involves interpretation and 19

20 modelling work of the different research disciplines (geology, hydrogeology, geochemistry and rock mechanics), aimed at complementing the understanding of the site. The output of this work, the description of the disposal site, will be used as basic information for both the designers of the repository and the analyses of long-term safety. The Olkiluoto Site Description 2008, the third successive description of the disposal site, was published in It includes updated models from all lines of research. The sections below present the key results of each field of research for the round of updating models. The results of modelling gave no reason to change the opinions regarding the suitability the bedrock for geologic disposal. Geological and geophysical modelling The Site Description 2008 published in early 2009 presented version 1.1 of the geological model. The model was updated to version 2.0 during This model will be presented as a working report in early 2010 and used as the basis for the following round of site modelling work. The statistical model (the so-called DFN model) of bedrock fractures in Olkiluoto was also reported in Work for updating it on the basis of new mapping material also started during the year. Geological modelling comprises four parts: the ductile deformation model, rock type model, alteration model and brittle deformation model. The ductile deformation model describes the plastic deformations taking place in the bedrock. The properties of throughout orientation of the bedrock was analysed as the most important of these. The orientation data, together with mapping results of exposed bedrock and drill core surveys, is utilised when modelling the rock type distribution in the Olkiluoto bedrock. The purpose of the metamorphosis model is to use borehole data to produce a three-dimensional model of the hydrothermal alteration observed in the bedrock. The current understanding is that this phenomenon that has, among other things, produced clay minerals in the bedrock, was mainly created 20 about 1.6 billion years ago as a result of penetration of rapakivi granite into the bedrock of the nearby areas. The brittle deformation model, in turn, tries to produce a very detailed description of the brittle fault and fracture zones present in the bedrock. According to current knowledge, the faults in the Olkiluoto area were originally so-called overthrow faults that were re-activated by later occurrences in the bedrock hundreds of millions of years ago. The results of modelling will be assessed using the prognosis and materialisation analyses introduced earlier where the predicted characteristics are compared with the geological characteristics actually observed in ONKALO. The results from this comparison work will help better target the research and modelling methods when assessing the suitability of the disposal bedrock. As in the geological site model published early in the year (version 1.1), the update now carried out is also based on detailed data obtained from drill cores regarding ductile characteristics, types of rock, degree of alteration and brittle zones. The focus of the new drill core material is in the eastern part of the island, which allows the production of a more reliable geological description of this area as well. In addition to geological data, the modelling also extensively utilised geophysical data. Many geophysical methods are particularly suitable for modelling fragmented bedrock zones. Geophysical methods were used to obtain information about the distribution of zones between boreholes and outside the survey site. New data has also been used to further specify the geometry of the zones. Other partial models of the geological model were also developed during 2009 on the basis of new information. The geological model will continue to form the basis for other models. An updated model (version 1.1) of the ONKALO area was published in In this model, the geological and geophysical modelling work was integrated and the updated models were supplemented with hydrogeological data. Hydrogeological modelling The focal areas of surface hydrogeological modelling in Olkiluoto for 2009 were the assessment of the impact of seepage waters in ONKALO and the modelling of the basic state of the recharge test. The main objective of the calculations made using the surface hydrogeological model of Olkiluoto was to assess the impact of seepage water volumes in ONKALO on the level of groundwater in the soil layers and on pressure heads in short boreholes in particular, as well as to assess how waters seeping into ONKALO affect the water balance of the entire island and what the origin of these seepage waters is. The model calculations were carried out using several different values for seepage water flows and by allocating the seepage waters separately to the tunnel and shafts of ONKALO. The modelling results were used as background data when updating the limit values for seepage water in ONKALO. The results of modelling indicate that the seepage waters in ONKALO lower the groundwater levels, particularly during years of less rainfall. The results show that the groundwater table in the surroundings of ONKALO may, for short periods, be below the seawater level if the seepage water flows to ONKALO at a rate of 180 litres/minute or more. When the total seepage water flow rates are below this value, the groundwater table stays above sea level. The calculated maximum drop in groundwater table is about 5.5 m when the total flow of seepage water is 140 litres/min or less. The calculations show that the impact of ONKALO on both the thickness of the unsaturated layer and the extent of the affected area clearly increases when the seepage water volume is 180 litres/min or more. A version of the surface hydrological model was produced in 2009 and it can be used for analysing the results of the recharge test. The first version of the model only described the main zones conducting water. The measurements and the model both show that local zones of high water conductivity are very important in the recharge test scale, which is why the model will be

21 further specified regarding the description of zones during The updated hydrogeological structural and flow model was reported in Site Description After that, hydrogeological modelling work has been done in connection with analyses of long-term safety and in particular as support for the development work of rock suitability criteria. For the rock suitability criteria development work, a modelling-based estimate was produced in 2009 on how the seepage waters entering the repository will be distributed between different deposition tunnels. In the basic scenario, the average distance between bedrock fractures with a water conductivity in excess of m 2 /s is 23 metres. However, the distances between these bedrock fractures with very low water conductivity vary a great deal. The results of the estimation work are based on analyses that do not take into account the possibility of placing the deposition holes in bedrock sections with minimal fragmentation, chosen on the basis of pilot borehole data and later verified in the actual deposition holes. On the other hand, the model assessment shows that the long fractures intersecting the repository facilities have little impact on the distribution of seepage waters. In connection with the bedrock suitability criteria, the rise or upconing of saline water present much deeper inside the bedrock than the repository was also assessed in In the basic scenario, the salinity of groundwater at the disposal depth would increase from its original value (16 g/l) to approximately 40 g/l during one hundred years of rock construction work. Hydrogeochemical modelling The updated hydrogeological groundwater model was reported in Site Description Much more is known about the chemical composition of groundwaters in fractures of low water conductivity now than during the previous version of the model. The increase in knowledge on microbes and isotopes has also improved the understanding of factors controlling the composition of infiltrating groundwater. On the basis of observations made in connection with updating the model, the research activities of future years will be directed at studying the processes significant to long-term safety. These include the studies on the processes affecting the sulphide quantities, the origin of methane dissolved in the groundwater as well as the relationship between groundwaters and matrix waters. During the autumn 2009, the hydrogeochemical modelling and interpretation work focused on preparing background material for the next round of modelling. An extensive process of assessing the representativeness of data on the electrical conductivity of groundwater began in the autumn. The objective of this work is to select representative measurement data for the update of the groundwater salinity model scheduled for the summer The work for interpreting the isotope results obtained from the entire groundwater material also began. This work will be completed in the spring The first trial models for establishing the origin of methane have already been produced, and this work will be reported early in Reactive transport modelling work has also been carried out for the recharge test. The results of modelling are in the process of being reported. Rock-mechanical modelling The rock-mechanical block model was reported in the autumn At the same time, modelling work continued using new data and structural interpretations. The input data used for modelling included that obtained from rockmechanical studies carried out in boreholes and ONKALO, geological mapping and geophysical measurements. The end results of modelling include a description of the bedrock quality and the mechanical parameters of brittle structures and bedrock with few fractures as well as the spatial distribution of rock strength and its state of rock stress. Rock-mechanical analyses were carried out during 2009 for the purpose of predicting the degree of rock damage in the demo facilities and technical facilities of ONKALO. The analyses were carried out using a 3D edge element program (Examine 3D), taking into account the measured deviations of bedrock stress and rock strength values. The result was a forecast of the probability of bedrock damage and its depth. The forecasts will be reported in In addition to the above, phenomena occurring and possibly observed in the vicinity of the rock-mechanical research facility were simulated. Due to moving the research facility to another location, the simulation will be repeated during 2010 when the latest interpretation of stress data from the research depth will be available. The material and the simulation will be reported in Rock Suitability Criteria The Rock Suitability Criteria (RSC) programme defines the suitability criteria for the bedrock and the suitable volumes of bedrock for the needs of layout design and disposal operations. The preliminary, or RSC-I, criteria were published as a Posiva Working Report in the spring 2009 (TR ). The testing of RSC-I criteria began with pilot borehole ONK-PH10 drilled in the access tunnel of ONKALO. The tests will be reported in early In order to verify the test results, geochemical samples and samples related to studies of structural geology were taken from ONKALO for analysis. A Master s Thesis on local phenomena associated with rock faults was also produced. The development work for RSC-II criteria began in late autumn 2009 on the basis of test results obtained for RSC-I criteria. The development work will, in part, take place in co-operation with SKB. The plan for the RSC programme was updated towards the end of the year, particularly with respect to the coordination of planning and construction work. The update also emphasised the importance of developing the quality management system of the entire programme. The demonstration of criteria of the RSC programme begins in ONKA- LO at the disposal depth in the so-called demonstration tunnel in late The planning work for the RSC programme demonstration has begun. 21

22 Design and planning of the encapsulation plant and repository The facility complex consists of an encapsulation plant to be constructed at ground level, other auxiliary buildings and structures at ground level and the underground repository. The construction work for the encapsulation plant and repository will begin when the construction licence has been granted. The operations of the facility are scheduled to start in 2020 after the operating licence has been granted. The spent fuel brought from the interim storage is packaged into canisters in the encapsulation plant and transferred to the repository in a lift. The current plans involve excavation the repository facilities on one level at -420 m. Access to the underground facilities is through the access tunnel and shafts. Deposition holes will be drilled in the floors of the deposition tunnels for inserting the canisters. The canisters will be completely surrounded by bentonite blocks that will swell considerably when becoming wet. The facilities will be expanded as the disposal operations progress by excavation more deposition and central tunnels. The planning and design work for the encapsulation plant and repository progresses in three-year periods. Encapsulation plant The draft design phase of the encapsulation plant ended at the end of 2009 with a report on the status of planning at that stage. The primary alternative is still an encapsulation plant connected to the repository by a canister shaft. The equipment design work for the encapsulation plant has produced plans for the canister weld inspection station, the fuel transport container transfer trolley and the docking station. Equipment for X-ray, US, eddy current and visual 22 inspection of the weld are foreseen for the inspection station. The different methods will complement each other and help ensure that the weld complies with the prescribed requirements. The fuel transport container transfer trolley operates in the transport container transfer corridor and is capable of moving transport containers of different sizes to the docking station of the fuel processing chamber. The equipment plans now completed supplement the equipment plans for the encapsulation plant so that equipment plans of at least a preliminary level are available for all main equipment in the fuel encapsulation process. These preliminary plans form a comprehensive basis for further equipment design work aimed at designing and producing prototype equipment. Draft system descriptions were produced for certain encapsulation plant systems as part of the preliminary licensing documentation submitted to the authorities for their perusal. The results of their assessment will be taken into account when the final system

23 Computer image of the disposal canister weld inspection station. descriptions are submitted in connection with the construction licence application. Repository The outline design phase of the repository ended at the end of 2009 with a report on the status of planning. The layout of repository facilities was updated in the plan on the basis of the latest bedrock data. In addition, the layout determining features of the bedrock structure, determined as part of the RSC programme, were now used for layout design for the first time. The design and planning work for the repository has been carried out in close co-operation with the implementation planning work for ONKALO in order to ensure the compatibility of facilities. The repository design is based on an alternative where the canisters are transported via the canister shafts in a canister lift from the encapsulation plant to the disposal level. The plan involves a total of five shafts, three of which will be implemented as part of ONKALO and two later. The updated plan is for an approximate fuel quantity of 5,500 tu. This quantity will cover the spent fuel produced by the plants currently in operation or under construction during their planned operating life. The repository facilities are laid out on one level at a depth of metres. The plan also includes an updated description of the implementation, from its phasing to different expansion phases. The repository also includes the buildings at ground level assisting in its operations. Of these, the ventilation building and lift building are among the most important. The ventilation building feeds fresh intake air to the entire repository and removes the exhaust air from underground facilities. The ventilation building is connected to all ventilation shafts. The lifting equipment building is located above the personnel shaft, and it houses the machinery of the lift intended for all personnel transports in the facility. The implementation planning for the buildings has already begun, and the buildings will be, in part, built already in connection with the construction of ONKALO layout plan for the repository. 23

24 Production of evidence in support of the safety case Plan for the production of evidence in support of the Safety Case In keeping with the schedule confirmed by the Ministry of Trade and Industry in 2003, Posiva is making preparations for submitting its application for the construction licence for an encapsulation plant and repository for spent nuclear fuel towards the end of In the licence application, the long-term safety of disposal is discussed in the so-called safety case. According to an internationally adopted definition, safety case refers to all the technical-scientific documentation, analyses, observations, tests and other evidence that are used to substantiate the safety of disposal and the reliability of the assessments thereof. The main reports included in the safety case and their foreseen schedule until 2012 are shown in the Safety Case Plan 2008 (POSIVA ). The major tasks in 2009 included the work for compiling the Models and Data report. The report will be completed in In addition, work was done in 2009 for producing the Interim Summary Report of the Safety Case 2009 that will also be completed in This Interim Summary Report outlines the current status of Posiva s safety case regarding the disposal of spent fuel in the Olkiluoto bedrock using a disposal method based on the KBS-3 principle. The work for producing the FEP (Features, Events and Processes) database report, process report and scenario formation report began in The process report presents a description of significant features, events and processes (FEP) and the interactions between them. The scenario formation report presents the systematic selection of sequences of events in the disposal site and the repository for scenario analysis. Performance of release barriers The technical release barriers are the primary factor ensuring long-term safety in Posiva s safety concept. The safety of the KBS-3 solution is primarily based on the long-term isolation of radionuclides in disposal canisters, and on technical release barriers ensuring the leaktightness of these canisters, as well as on natural conditions and processes. The performance studies have concentrated on establishing the behaviour of the copper canister and the bentonite protecting it, as well as on studying the harmful processes. The studies have been carried out both in international co-operation for example, in EU framework programmes and in the Äspö rock laboratory and also using exclusively Finnish resources. The studies produce input data for future safety assessments and discuss and develop the requirements for planning and designing the repository facilities, tunnels, shafts, backfill materials and sealing structures. The BENTO programme, aimed at developing expertise in the use of bentonite, has involved studies related to the technical design and development work of the buffer as well as to reducing the uncertainties associated with the safety case and methods development work in order to develop the necessary routines. Work has been done for developing the mineralogical and chemical characterisation of bentonite and to establish the water saturation process and the properties of bentonite completely saturated with water. Development work for both the empirical and numerical methods has been carried out in all areas. The main individual areas for investing resources were: saturation with water in general, erosion of buffer materials possibly associated with the early stage of water saturation, interaction between saturated bentonite and concrete, interaction between saturated bentonite and iron, cementation of saturated bentonite caused by salts and silicates, the effect of high salinity on the swelling pressure of saturated bentonite, repeated freezing and subsequent thawing of saturated bentonite, and erosion of buffer materials in conditions prevailing after an ice age as a result of dilute melt water possibly entering the repository facilities. Another goal of the BENTO programme is to increase the competence and resources of bentonite-related R&D work, as well as the research instrumentation used for the purpose. Development work in these areas took place in During 2009, Posiva participated in several international research projects on the behaviour of bentonite, and in the preparatory work of these projects. These included the 7th framework programme of the EU, entitled FORGE (Fate Of Repository GasEs), the CFM (Colloid Formation and Migration) project by the Grimsel Rock Laboratory, and the FEBEXe (Collaboration in the Full Scale Engineered Barrier Experiment in Crystalline Host Rock), which all began in In FORGE, Posiva participated in producing a description, based on current knowledge, of the migration of gases inside bentonite. In CFM, Posiva participated in developing 24

25 a method for estimating the degree of erosion in clay caused by dilute waters. The results indicate that the factors limiting the phenomenon are independent on the set-up used for the test. The FE- BEXe project continued the monitoring of the long-term test and collection of data from it. In addition to the above, Posiva has also participated in coordination work in the EBS Task Force for the development of assessment procedures and modelling tools regarding technical barriers. The modelling of test cases carried out in this context has shown that the predictability of THM (Thermo-Hydro- Mechanical) phenomena provided by the different models is very limited in very similar ways. Test cases regarding chemical developments in bentonite were prepared in order to create a common approach. In 2009, Posiva participated in the ABM (Alternative Buffer Materials) project in progress at Äspö, and which has been running for several years. Its purpose is to study the long-term processes taking place in different bentonite materials in a full-scale test. The first actual samples were obtained for analysis in the spring 2009, and the results will be reported in In addition, Posiva participated in the Large Scale Gas Injection Test (LASGIT). This test, studying the migration of gases in saturated bentonite, has been continued by repeating stages already carried out for the purpose of producing statistical certainty for the results. The first phase of the tests showed that gases migrate in saturated bentonite through predictable mechanisms. Posiva participated, in the role of an expert, in an international study of natural analogue, the purpose of which was to accumulate knowledge on the longterm stability of bentonite under high ph conditions. The studies take place in Cyprus. The second phase of the study took place in 2009 and it involved selecting the best subjects among the samples analysed in the first phase for the studies to be carried out in the third phase. SKB and Posiva continued their joint empirical research on the corrosion of copper under conditions corresponding to those during final disposal. A report (WR ) was published in 2009 regarding studies conducted in Canada and where empirical results were used as the basis for modelling the behaviour of corrosion potential of copper in compacted sulphite-containing bentonite. Further, the work for updating the State of the Art report (Posiva ) on the corrosion of copper produced in 2002 continued in 2009 in co-operation with SKB. In addition, during 2009 Posiva and SKB have planned and initiated studies regarding the corrosion of copper in water. One of the purposes of these studies is to repeat the tests published by Hultquist and Szakálos in 2008 regarding which a workshop was organised by Kärnavfallsrådet in November The results of this event will be taken into account when planning further actions. The stress corrosion studies initially scheduled to start in 2009 were postponed to 2010 due to limitations in the personnel and equipment resources of the laboratory foreseen to carry out the tests. The work for assessing the long-term safety implications of residual stresses possibly present in the EBW welds on copper began in The cement studies related to longterm safety continued with Nagra of Switzerland, JAEA of Japan and NDA of Great Britain in the LCS (Long-term Cement Studies) project aimed at studying the interactions of grouting cement with bedrock in situ in Grimsel, Switzerland. The purpose of the laboratory tests conducted in support of the field tests is to model the dissolving of cement and its interactions with the bedrock. The first phase of the project ended at the turn of the year , and the work for reporting its results is still in progress. The second phase of the LCS project has began, and it is scheduled to continue during In 2009, a study (WR ) was conducted regarding the stability of silica colloids released from silica sol and their sorption in radionuclides (Eu- 152) in saline and low-salinity groundwater simulations. The tests revealed that the salinity of groundwater has a significant effect on the release and stability of silica colloids. This means that no significant release of silica colloids from silica sol is expected to take place in the Olkiluoto groundwater conditions of moderate or high salinity. However, the possible combined effect of silica and bentonite colloids, as well as the effect of melt waters after an ice age must be taken into account when assessing the significance of colloids. The concentrations of released silica colloids are slightly higher than the natural colloid concentrations determined from groundwater surrounded by granite rocks. Bedrock as a release barrier The results calculated by REPCOM software, used for migration modelling of the surrounding rock areas, were assessed in 2009 by comparing them with the results obtained from Gold- Sim modelling. In a conservative case where the model parameters are selected by overestimating the resulting radiation doses, the results calculated using REPCOM were well in line with those obtained using the GoldSim model. In a more realistic case (in a situation corresponding to less harmful radiation effects) that takes into account the limited solubility of radionuclides, the model calculations using REPCOM and the GoldSim model produced different results because the ability of REPCOM to process more realistic situations is limited. The development work for the radionuclide migration model (MARFA) continued in 2009 in collaboration with SKB. MARFA software allows taking into account limited and unlimited matrix diffusion, equilibrium sorption, longitudinal dispersion, radioactive decay and in-growth. The capabilities for processing the effect of changes in external conditions over a long period of time (land uplift, climate change) on migration routes and the locations where these routes surface were also developed for version 3.3. of the software. Co-operation in the Task Force for groundwater flow and solute transport at the Äspö Rock Laboratory continued. 25

26 Work on surveying the species of earthworm found in Olkiluoto in the summer Photo: Marko Nieminen / Faunatica Oy. The contents and time schedule of the Task 8 package was planned in The purpose of this package is to study the modelling of bentonite tests. The spent fuel safety analysis will include an estimate of the behaviour of radionuclides in the geosphere. As part of this estimate, the migration of radionuclides as well as their retention in the rock material and surfaces of bedrock fractures will be analysed. The magnitude of retention of dissolved radionuclides is described by the distribution factor. The value of the distribution factor depends on the conditions, which is why the values best describing the distribution in the analysed chemical and physical environments (types of rock and minerals present in Olkiluoto and the composition of its groundwater) are selected for the migration estimates. The empirical work for updating the values of these parameters for the most important radionuclides began in 2008, and it continued in keeping with the planned schedule in The work for reporting its results is still in 26 progress. The work is scheduled to still continue during Biosphere Biosphere-related work has taken place during 2009, in keeping with the TKS programme, a separate biosphere work plan (POSIVA ) and the revised Safety Case (POSIVA ). The goal of this work was to produce an updated description of the biosphere (POSIVA ), forecasts for future terrain and ecosystems, as well as radionuclide migration simulations and a dose assessment. Reports of these will be completed in early Collectively, these reports constitute a holistic assessment of the biosphere. In addition, a project was initiated in 2009 for developing the numerical methods used for estimating the uncertainties associated with the terrain model and land uplift model, while the extensive research project regarding the retention of radionuclides in soil and sediments continued. A research project of many years, based on automatic measurements, was initiated for further specifying the sedimentation conditions in sea areas. The modelling methods were developed particularly by combining the terrain forecasts and radionuclide migration modelling through a more detailed soil and surface hydrology model. Posiva has also actively participated in the operations of the international BIOPROTA forum for example, by heading the joint project for testing the methods for assessing ambient radiation levels which will produce its final report in early On a regional level, Posiva participated in various projects including the Jokivarressa (By the Riverside) and the Muuttuva Selkämeri (Changing Bothnian Sea) projects. General research In 2009, Posiva started, in co-operation with SKB and NWMO of Canada, the three-year Greenland Analogy Project (GAP) with the main objective of estab-

27 lishing the effects of the ice sheet on the circulation and chemical properties of groundwater. The results of this project will be required for assessing the safety of disposal deploying the KBS-3 solution in ice age conditions. The results of this project will also help to analyse the degree of realism in the existing ice age models and modelling of groundwater chemistry during an ice age. Posiva is working with the Finnish Meteorological Institute on an update of the climatic scenario for Olkiluoto. The purpose of this update work is to asses the duration of cold periods (ice ages), i.e. the extent of their impacts in Olkiluoto on a time scale spanning 100,000 years. The update work also takes into account the probability of such cold periods occurring, as well as any warm periods that may occur. The material accumulated from the climatic scenarios will be utilised for the safety analysis studies concerning Olkiluoto, including the modelling of the formation of permafrost and the evolution of ground level hydrology, biosphere and groundwaters deep inside the bedrock. One of the objectives of the Geo- Satakunta project was to produce a model describing the structure of the Kokemäenjoki River and its estuary, maps of suitability for construction and information on brittle deformation in the Satakunta region. The project began in 2000 and continued in 2008 under the title InnoGeo. The concluding seminar of the project was organised in April 2009, and the final report will be completed during Posiva is participating in the PAMI- NA (Performance Assessment Methodologies in Application to Guide the Development of the Safety Case) project belonging to the 6th framework programme of the EU; it is concerned with the development of methodology for safety analyses and dealing with its uncertainties. As part of this project, Posiva participated in a task package aimed at compiling a collection of State of the Art style regarding the handling of uncertainties. The project ended in 2009 and the results will be reported during Researchers from the GAP project by the edge of an ice sheet in Greenland. 27

28 Development of the horizontal disposal solution In parallel with the vertical disposal solution (KBS-3V) now constituting Posiva s reference solution, the horizontal disposal solution (KBS-3H) has been developed jointly with SKB. The decision to continue developing the horizontal disposal solution was taken in the spring 2008, and a new project entitled Täydentävä tutkimusvaihe (Supplementary research phase) was initiated with SKB for This research phase will consist of solving problems identified in the plans to date as well as preparing a plan for initiating the next phase. The next phase for years will include full-scale testing of system components, preparation of the final technical plan as well as the production of a safety case for Olkiluoto and Forsmark in Sweden. The goal to be achieved by 2014 is that the information obtained should allow a detailed comparison of the 3V and 3H alternatives. This would then form the basis for making the decision regarding full-scale testing of the entire system, either for the 3V or the 3H alternative. The objective of safety studies conducted during the current phase of the project is to accumulate sufficient information on the effects of iron, titanium and copper on bentonite to a allow making, with the support of technical studies, a holistic assessment of which material should be used for the protective cylinder of the supercontainer. The tests for studying the interactions between protective cylinder material and bentonite have concentrated on the physical, mineralogical and chemical properties of bentonite. Another important part of the work is that of determining the long-term safety requirements of the horizontal disposal solution. The main goal of planning during the current project phase is to resolve the questions identified as important during the previous phase of the study. Many of these questions are related to the buffer and its behavior. Of the design alternatives, DAWE (Drainage, Artificial Watering and Air Evacuation) and STC (Semi Tight Compartment), the latter has been deemed to be associated with serious uncertainties. This is why the main focus of the project is on the DAWE design alternative, and the important buffer issues associated with it have been studied in laboratory conditions by modelling and/or in theoretical analyses. The buffer-related design objective is to produce detailed plans for the buffer to be inserted between the spacer plug and the supercontainer. In the DAWE design alternative for horizontal disposal, an artificial wetting method is used to ensure the wetting and swelling process of buffer material. A wetting alternative based on short pipes led through the compartment plug was devised in The laboratory tests for studying erosion in this alternative have been completed. One of the many questions to be resolved is rock spalling and its significance as a potential flow route at the ceiling of the deposition drift. Rock spalling is the result of stress-induced loads (bedrock stress), excavation work and thermal stresses caused by an increase in bedrock temperature. The analyses on the spalling of the Olkiluoto bedrock will be updated during 2010 when the results of the POSE (Posiva Spalling Experiment) field test carried out in ONKALO (regarding spalling strength, etc.) are available. The backfill Illustration of the KBS-3H solution principle. 28

29 components used for backfill solutions near the plugs as well as in drift sections unsuitable for depositing supercontainers have also been designed during this project phase. The detailed design of the end plug for the deposition drift also takes place during this project phase. The two other sub-projects of the horizontal disposal solution development project are entitled Tuotanto ja toiminta (Production and operation) and Demonstraatio ja täysimittakaavaisten testien suunnittelu (Demonstration and planning of full-scale tests). The objective of the first sub-project is the development of production lines, plants and system descriptions. The remaining tests for the installation device are also included in this sub-project, as are the industrial safety and environmental issues related to the KBS-3H solution as well as the layout studies for the Forsmark and Olkiluoto repository facilities. The latter sub-project will be responsible for manufacturing components and production equipment and their installation and testing in Äspö, as well as for the planning for the next project phase. Full-scale testing of the partitioning plug was carried out during The work for specifying the Rock Suitability Criteria (RSC) for the horizontal disposal solution will begin in The KBS-3H layout will also be updated to correspond to the KBS-3V layout produced in

30 Olkiluoto monitoring programme The long-term changes possibly caused by the construction of ONKALO are monitored using a special programme (OMO) established for the purpose (Posiva ). The scope of the programme includes rock-mechanical, hydrological and hydrochemical monitoring and the monitoring of the environment and foreign substances. The results of monitoring studies are published separately for each field of research as part of the series of Posiva s working reports. Rock mechanics In 2009, rock-mechanical monitoring continued as in previous years. Microseismic data was continuously analysed and monitored. The new metering station installed in ONKALO at the end of 2008 has operated without any problems. Preparations were made in late 2009 for installing the next metering station in ONKALO. The purpose of the new metering positions is to develop the metering station network and to further improve the accuracy of results. GPS measurements in Olkiluoto and its surrounding areas were taken in the spring and autumn as in previous years. Precision levelling of the fixed points in the bedrock was also performed in the vicinity of ONKALO and the VLJ repository. The purpose of these measurements was the same as that of the microseismic measurements, i.e. to further reinforce the opinion regarding the stability of the Olkiluoto bedrock and to assess, among other things, the variations in the land uplift rate in Olkiluoto and its neighbouring areas. A development plan was drawn up for the GPS station network in Its purpose is to expand the area of observations by a few new measurement points and to improve the accuracy of measurements by updating part of the stations for continuous measurement. During 2009, convergence measurements were carried out in ONKALO at two levels (-180 m and 290 m) during and after shaft raise boring. The purposes of these measurements include studying the deformations of bedrock caused by raise boring and further specifying the data on bedrock stability. The processing of convergence measurement data provided further information on the field of stress prevailing in the Olkiluoto area. Hydrological features Hydrological monitoring continued in 2009 mainly following the same programme as in The biggest change from previous years was in the change of focus from monitoring the flow conditions in boreholes to monitoring pressures. Groundwater level observations were made in both shallow groundwater tubes and boreholes and in deep open boreholes using manual methods once a month. The monitoring of pressure heads took place using the automatic pressure monitoring network of multiple-plugged boreholes (GWMS). ONKALO, HZ20A and B structures and the GWMS pressure monitoring network ( the black disks represent plugs; the pressure monitoring sections are marked in blue ). 30

31 The supply of GWMS data by and its online monitoring operated in 2009 as planned, and data processing and analysis was further developed. By the end of 2009, a total of 27 deep boreholes had been fitted with multiple plugs and added to the monitoring network; one of these holes was fitted with multiple plugs during The need to increase the number of holes with plugs, expressed in R&D plan TKS- 2006, was in the main satisfied during 2007 and 2008 when all deep boreholes located near ONKALO and penetrating major water-conducting structures were fitted with plugs. Increasing the number of plugged boreholes has significantly improved the accuracy of pressure monitoring and prevented the conveyance of pressures through open holes. Now geochemical observations also have indications of the positive effects of plugging in the form of reduced mixing of waters from different waterconducting structures. Major waterconducting HZ20 structures were penetrated by the access tunnel of ONKA- LO in late 2008 as well as at the turn of , and the same structures were penetrated by shaft grouting holes during The impacts of structure penetration-related leaks on groundwater pressure were monitored and analysed during A quarterly memorandum was compiled during 2009 as planned, discussing the results of level and pressure head measurements and analysing the short-term impacts of other field events and ONKA- LO construction work on pressure heads. In addition, the flow conditions in open holes ware monitored, together with groundwater salinity, runoff surface water volumes, seawater level and seepage waters in ONKALO. Transverse flow measurements were only made in campaigns while instrumentation development work continued. Of the parameters included in the hydrological monitoring programme, the runoff surface water volumes, rainfall (including snow), thickness of ground frost and seepage are reported in the annual environmental monitoring report. The monitoring activities in ONKA- LO continued during 2009 with measurements of total seepage water volumes taken approximately every two weeks. The measurements are taken, as far as possible, for the entire length of the tunnel and from measuring weirs, the total number of which at the end of 2009 was seven (at chainages 208, 580, 1255, 1970, 3003, 3125 and 3356). Structures HZ20A and B are located between measuring weirs 3125 and The average total volume of seepage waters in ONKALO has increased from 2008 (20 litres/min in 2008, 33 litres/ min in 2009). The main reasons for this are the penetration of HZ20 structures and raise boring of three shafts to level -290 m. A visual inspection of seepage water volumes covering the entire length of the tunnel was carried out twice in 2009 in order to identify the location of leaking fractures and zones and to monitor any changes taking place in them. Hydrogeochemistry The hydrogeochemical monitoring programme was, in the main, implemented in line with the sampling plans drawn up in However, slight changes were made to the original sampling plan in the autumn 2009 when indications of possible changes in salinity for example, in research boreholes OL-KR1 and OL-KR7 were received from SAMPO scanning. Local changes in salinity and impacts of the Korvensuo basin in the groundwater pipes and bedrock holes in its vicinity can be observed among the results of 2009 sampling. The monitoring results will be reported in the spring 2010, and the plan is to also analyse the reasons for changes in that connection. The changes in groundwater composition may be caused by different sampling methods used at different times, the construction of ONKALO or other construction works in the area. Groundwater samples have been taken in ONKALO according to the programme, primarily from groundwater stations. Five groundwater stations were regularly monitored during the year. Studies of groundwater chemistry and microbiology have been conducted on the groundwater stations. The composition of groundwaters has remained the same in the areas near ONKALO. The studies on the immediate impacts of ONKALO construction work continued with water sampling from fractures leaking water as well as from measuring weirs and waters pumped from ONKALO. The construction of ONKALO, in particular shotcreting, causes from time to time considerably high ph values (10 12) in waters pumped from ONKALO. However, it has been found that the ph of water pumped from ONKALO neutralizes reasonably quickly in the sedimentation pool and the drain ditch leaving it, and no harmful effects on the environment have been observed so far. The environment The work of monitoring the surface environment in Olkiluoto continued in 2009, primarily in line with the planned research programme. As in the previous year, several campaign-style studies were carried out in addition to regular studies. In addition to the actual monitoring studies, other environmental studies were also conducted, as in previous years, in order to describe the current state of the area. The regular monitoring of the state of forests continued throughout the year on three intensive testing plots, including observations on the vegetation, forest litter, root systems, microclimate, wet deposition and grove water. The fourth intensive testing plot was established at the western end of the Olkiluoto island, and the intention is to have the entire study regime in operation there during Preparations are being made with the new intensive testing plot and five other testing plots for changes in land usage on the survey area. The seepage waters from the dumping site for rock material quarried from ONKALO were monitored on three occasions. Water samples were taken from the Korvensuo basin and from the Eurajoki river, as well as from the four ditches fitted with automatic measuring weirs in The water levels and water quality in three privately-owned 31

32 drilled wells was also monitored. Samples of animal plankton were taken at one observation location in the sea for the purpose of supplementing the monitoring programme that TVO is obligated to operate. A seasonal survey of game stock was conducted by interviewing local hunters. The trapping campaign of 2008 for small mammals was repeated as part of the monitoring programme, albeit with a smaller number of traps. The populations of ants, gastropods and earthworm were surveyed in addition to the actual monitoring programme. An extensive aerial photography campaign was carried out in late May, covering an area of over 200 km 2 from the coast to the centre of Eurajoki. The purpose of repeated aerial photography campaigns is to monitor any changes taking place in land use, and with it, also in the natural habitat. The environmental surveys commissioned by TVO were also monitored in addition to the above environmental studies carried out by Posiva. Foreign materials The monitoring and control of foreign materials is part of Posiva s monitoring programme. Foreign substances refer to all those materials and substances used for constructing ONKALO that are not part of the disposal system. Records were kept during 2009 of foreign materials, and the materials manual was updated with respect to the permitted and prohibited construction materials. The impact of cement and its additives as well as that of materials used for concealed drainage on microbial growth was also studied in The study on the impact of colloid silica, used as the grouting material for small fractures, on the migration of radionuclides in a possible transient situation was also completed during By the end of 2009, a total of 521,000 kg of cement had been used for grouting and 2,416,000 kg for shotcreting. During the entire construction project so far, 836,000 kg of explosives and 12,500 temporary and final reinforcement bolts have been used. 32

33 Control of nuclear materials and nuclear non-proliferation control The purpose of nuclear non-proliferation control by Posiva is to ensure compliance with the relevant legislation and international treaties governing the matter during the construction phase of ONKALO. Posiva has produced a nuclear nonproliferation control manual that describes the nuclear non-proliferation control during the construction phase of ONKALO from 2012 until the planned construction licence application phase for the final repository. The nuclear nonproliferation control manual was updated in The manual defines the preliminary, actual and monitoring data concerning ONKALO that is reported quarterly to STUK. In addition, STUK carries out physical inspections, including the inspections of the ONKALO rock facilities and periodic inspections of the entire nuclear non-proliferation control system. During 2009, STUK performed three periodic inspections of nuclear non-proliferation control measures in ONKALO, plus an inspection of the entire nuclear non-proliferation control system. Representatives from the IAEA and Euratom participated in the inspections as observers. No cause for complaint concerning ONKALO nuclear non-proliferation control was raised in these inspections. The monitoring of the excavation of underground rock facilities is based on the requirement to demonstrate that ONKALO does not include any facilities which are not indicated in the design data. Monitoring makes use of the microseismic station network built in Olkiluoto; the surveillance data of the network provides up-to-date information about blasting in Olkiluoto and in the nearby area. This system has proven to be a good and only method available to date for monitoring the excavation operations from the outside. However, the microseismic monitoring system is only capable of detecting blasting, and it does not detect work performed using the so-called tunnel boring method, but filters it out as background noise. Posiva has investigated the possibilities for making observations of the tunnel drilling method during the process of raise boring the shafts in 2007 and The results indicated that observation is technically possible but requires special equipment. The investigations will continue during the next raise boring operation in order to improve the cost effectiveness of monitoring through automation. The reporting and monitoring operations are now well established and comply with the definitions of the nuclear non-proliferation control manual. 33

34 Operating waste management The Olkiluoto repository for operating waste (VLJ repository) was commissioned in The repository consists of two rock silos, a hall connecting the two and auxiliary facilities constructed at a depth of metres inside the bedrock in the Ulkopää cape of the Olkiluoto island. The facilities can be accessed both via the access tunnel and a shaft. Low-level waste is deposited in the rock silo inside a concrete box, while a silo of steel-reinforced concrete has been constructed for intermediate-level waste in the other rock silo. The silo for low-level waste has a capacity of about 5,000 m 3, while the capacity of the intermediatelevel waste silo is about 3,500 m 3. A preliminary design for the extension of the VLJ repository has been prepared in order to correspond to the increase in the operating life of OL1 and OL2 from the initial 40 years to the current 60 years, and in order to implement a disposal plan for operating and decommissioning waste from the OL3 plant unit under construction. The decision has also been made to take the needs of the possible fourth power plant unit (OL4) into account in the future expansion plan for the repository facilities. Low-level and intermediate-level operating waste generated at the Loviisa power plant is finally disposed of in facilities built in the bedrock of the Hästholmen island. Construction work on the repository began in 1993, and its first phase was completed at the end of The repository was commissioned for disposal use in the summer The Loviisa repository consists of a metre-long access tunnel, tunnel and hall facilities built at a depth of about 110 metres and of personnel and ventilation shafts. The facility was built in two stages. The first construction stage involved excavation all facilities and access routes. Two deposition tunnels were quarried for maintenance waste, and a repository hall was quarried for solidified waste. The second deposition tunnel and solidified waste hall were completed during the second stage that ended in The status of storage and disposal at the end of 2009 is shown in the table below. The Olkiluoto power plant OPERATING PRINCIPLE The majority of operating waste is immediately packed for processing, storage and disposal. The intermediatelevel ion exchange resins used for the purification of circulating water are solidified in bitumen, and the composition is poured into steel drums. A part of the low-level waste (compressible miscellaneous maintenance waste) is 34 compacted in steel drums using a hydraulic press, while another part (scrap metal and filter rods) is packed, without compaction, in steel and concrete cases and steel drums. The drums containing compressible waste are compressed so that the final height of the drum is approximately one-half of the original, with the diameter of the drum remaining unchanged. Scrap metal may also be processed before packing to reduce its volume. Scrap chopped up with a metal chopper may be used to fill up any empty space in the concrete cases transported to the repository. This improves the packing efficiency of metal waste. Miscellaneous liquid waste and slurry is solidified by mixing the waste with a binding agent in a drum that forms the packaging of the solidified product. If applicable, the volume of liquids and slurries is reduced through evaporation prior to solidification.

35 Operating waste is temporarily stored in the storages and fuel pools of the power plant units, the low- and intermediate-level waste interim storage facilities (the KAJ and MAJ storages) and, in small quantities, in the KPA storage at the Olkiluoto power plant site. Low and intermediate-level waste generated during the operation of the power plant is disposed of in the current waste silos of the repository for operating waste (the VLJ repository). Waste with very low activity concentration is exempted from control and taken to the landfill area located at the Olkiluoto power plant site or handed over to another party for recycling or other purposes. CURRENT STATUS OF STORAGE AND DISPOSAL The status of storage and disposal at the end of 2009 is shown in the table on the next page. The waste is packed in barrels (200 litres in each, about 100 litres when compressed), to steel crates (1.3 or 1.4 m 3 in each) and in concrete crates (5.2 m 3 or 3.9 m 3 net in each). The barrels and crates are stored, when required, in storage facilities of plant units and the KAJ storage before their final disposal in the VLJ repository. Before transferring them to the VLJ repository, the barrels and steel crates are placed in large and small concrete crates as follows: 16 barrels, or a combination of seven barrels and two steel crates, are placed in each large concrete crate and 12 barrels are placed in each small concrete crate. The number of barrels accommodated by the concrete boxes can be doubled by compressing them. Dismantled waste from inside the reactor, such as core lattices and steam separators, is included in the waste packed in crates of 1.8 m 3 for long-term storage in the fuel pools of plant units. Large contaminated metal components are stored in the KAJ storage and in the MAJ storage extension. In addition, unpacked operating waste such as used ventilation filters and resins without bitumen, are stored at the plant units, while waste oil is stored at the interim spent fuel storage (KPA storage). Part of the scrap metal is packed in the concrete crates used in the VLJ repository. Part of the unpacked waste is to be later released from control for recycling use or dumping on landfill sites. For example, waste oil of very low activity, of which some 7.2 m 3 had accumulated by the end of 2009, may later be released from control for recycling. The waste buildings at the plant units can accommodate about 1,000 barrels each. Mostly only very low-level maintenance bags and scrap to be released from control is kept at the MAJ storage. The KAJ storage can accommodate barrels, crates and large contaminated metal components corresponding to a total volume of some 6,000 barrels. The capacity of the intermediatelevel waste silo in the VLJ repository (expressed in 200 litre barrels) is 17,360 barrels while that of the low-level waste silo is 24,800 barrels. In other words, the total storage capacity of these two silos is about 8,400 m 3 of operating waste packed in barrels. This corresponds to the quantity of waste generated by two plant units during years of operation. More repository facilities can be constructed in the bedrock of the area as required as an extension of the VLJ repository to accommodate the disposal needs of operating and decommissioning waste. The small waste items held by the Radiation and Nuclear Safety Authority OPERATING WASTE GENERATED BY THE OLKILUOTO POWER PLANT Reactor buildings (m 3 ) VLJ repository (m 3 ) Other storages (m 3 ) OL1 OL2 KAJ silo MAJ silo Others KAJ MAJ Spent fuel interim storage Total LOW-LEVEL WASTE Scrap 0,2 2400,1 0,2 2400,5 Unpacked scrap 18,0 1040,0 1058,0 Maintenance waste 10,0 13,2 928,6 3,2 955,0 Miscellaneous waste 0,8 2,4 3,2 Solidified liquids 4,0 0,2 92,2 96,4 Waste oil 7,2 7,2 INTERMEDIATE-LEVEL Scrap 247, ,1 Resin powders 21,0 35,0 1262,0 1318,0 Resin granules 10,2 258,2 0,2 268,6 TOTAL ,3 3420,9 56,2 18,2 1040,2 7,2 6407,0 35

36 The Olkiluoto VLJ repository in its extended state, seen from south-west. The two silos seen on the background belong to the part of the VLJ repository in use. The expansion plan has space reserved for the operating waste of two new plant units and decommissioning waste of four plant units. are stored, by separate agreement, in the Olkiluoto VLJ repository. These small waste items mainly consist of radioactive substances used in hospitals, research institutes and industrial plants. So far, about 57 m 3 of small waste items has been accumulated in the VLJ repository. Expressed in terms of disposal volume, the filters of OL1 and OL2 plant units have a total of 4,845 kg (computational figure) of resin powders and granules in bitumen. The waste containers in the waste buildings of the OL1 plant unit contain an additional 6,000 kg (computational figure) of resin powders, while those in the OL2 plant unit have 1,800 kg (computational figure) of resin granules in bitumen. RESEARCH RELATED TO OPERATING WASTE Microbiological decay of low-level maintenance waste is being studied in a large-scale test performed with testing equipment erected in the VLJ repository excavation tunnel. The study serves to further specify the amount of gas generated from maintenance waste and to further knowledge of the whole decay process under conditions which are similar to those after the VLJ repository 36 has been sealed off. In addition, the release of activity from the waste barrels to surrounding water is also monitored. The most important parameter achieved in this test is the rate of gas generation in maintenance waste; this parameter is needed for the VLJ repository safety analysis. In the long-term, the rate of gas generation has been of the order of dm 3 /month which is one order of magnitude lower than what was estimated in the original safety analysis. The ph of the test tank clearly decreased during the gas generation test. At the beginning of the test in , the ph was while it has been 8 9 during IN-SERVICE STUDIES REGARDING THE VLJ REPOSITORY In-service monitoring of the VLJ repository rock facilities continued during the year being reported in compliance with the research and monitoring programme produced earlier. The results of hydrological monitoring of the VLJ repository during 2008 were reported in mid Extensive monitoring samples were last collected from the groundwater stations in the spring The most significant changes in groundwater quality were a decrease in sodium and chloride concentration and the halving of potassium concentration in two years. The next extensive sampling campaign is scheduled for 2011 in the VLJ repository bedrock research and monitoring programme. In the spring 1993, ten test bolts were installed in the research tunnel of the Olkiluoto VLJ repository for the purpose of determining the rate of corrosion in rock bolts. The purpose of the study is to produce information of the corrosion resistance of zinc-plated rock reinforcement bolts in the conditions prevailing at the Olkiluoto VLJ repository assuming that the cement plaster protecting the bolts has totally lost its protective properties. The first test bolt was drilled out in 1996 and the next in The results for the latter bolt were reported in The next bolt is scheduled to be drilled out in 2010 provided that the conditions in the bedrock are found to be sufficiently representative for reliable results. The Loviisa power plant Low-level and intermediate-level reactor waste generated at the Loviisa NPP is processed and stored at the plant. Used ion exchange resins and evaporator

37 bottoms are stored in tanks in the liquid waste storage. Trial runs of the liquid waste solidification plant based on cementation took place in , and the plant will be commissioned in In the early 1990s, a method was introduced in Loviisa for separating radioactive cesium from evaporation residue into a very small waste volume. The removal of cesium reduces the activity of the evaporation residue to such a low level that it can be discarded using normal drainage procedures. By the end of 2009, a total of more than 1,300 m 3 of evaporation residue had been purified at the cesium separation plant using 29 ion exchange columns, each with a volume of eight litres. The next cesium extraction campaign will take place in Dry maintenance waste generated in power plant maintenance and repair work is packed into 200-litre steel drums. Compressible waste is pressed into the drums using a baling press; in this way, one drum may be made to hold three to four times more waste than without compression. In 2009, 3 m 3 of hazardous waste released from control and 1,080 fluorescent tubes were sent to Ekokem Oy. Metal waste generated in the controlled area is exempted from control in campaigns, as the situation requires, and collected into suitable waste batches. Before official exemption from control, metal waste found uncontaminated in Total amount of waste At the plant/ in storage buildings At the repository Activity (m 3 ) (m 3 ) (GBq) Used ion exchange resins Evaporation residues Solidified evaporation residues and ion exchange resins Solvents solidified by absorption OPERATING WASTE GENERATED BY THE LOVIISA POWER PLANT 17 < 1 24 < 1 Maintenance waste radiation monitoring is kept in interim storage in a storage hall located in the yard area. In 2009, a total of 48,520 kg of metal waste was released from control and sent to Kuusakoski Oy. Interim storage of radioactive metal waste takes place in the storage facilities of the controlled area. The storage hall for maintenance waste barrels to be released from control also holds one ocean-freight container full of contaminated metal waste. This metal waste will eventually be disposed of in the VLJ repository. A project concerning the renovation of the low-level maintenance waste treatment and storage facilities is underway. In the autumn 2007, the construction of a conventional storage and repair shop building, exempt from control, started. The electrical and machine repair shops have already moved to the new building. After the completion of the new building and removal of functions, the controlled area will be extended to the facilities, which then become vacant. In the controlled area extension at LO1, facilities for maintenance waste treatment, a decontamination facility and a repair shop facility will be implemented. For LO2, facilities for metal waste and recyclable metal handling will be implemented. The new facilities in the controlled area are due to be fully commissioned in Gammaspectroscopic measuring equipment for drum waste (determination of gamma activity, automatic drum conveyor, weighing rotator, etc.) was ordered in 2008 and will be installed in The finishing work of the solidification plant (cementing plant) for liquid/ wet active operating waste was completed in 2008, and trial operation using evaporation residue took place. Trial operation on used ion exchange resins took place in 2009, and the process of obtaining an operating licence for production use was postponed to In 2009, low-level solvent waste was solidified by absorption in 200-litre barrels so that a total volume of 7 m 3 of barrels was accumulated. The status of storage and disposal at the end of 2009 is shown in the table below. Used ion exchange resins and evaporation residues are stored in the liquid waste storage. 1.7 m 3 of this is kept in solidified form in barrel-shaped waste containers. The solvent waste solidified by absorption and maintenance waste are kept in 200-litre barrels. REPOSITORY Low-level and intermediate-level waste generated in the operation of the Loviisa power plant is finally disposed of in facilities built in the power plant area bedrock. The repository received its operating licence in 1998 and was commissioned as a maintenance waste repository in The repository consists of a 1,170 metre long access tunnel, tunnel and hall facilities built at a depth of about 110 metres, and of personnel and ventilation shafts. The facility was built in two stages. The first construction stage involved excavation all facilities and access routes. Two deposition tunnels were quarried for maintenance waste, and a repository hall was quarried for solidified waste. At this stage, only one maintenance waste tunnel was completely built as well as the systems serving the whole disposal plant. The construction and installation work of the second stage of the repository was performed in The finishing work of the earlier constructed maintenance waste repository facility 2 (HJT2) began in November 2004, and this facility was commissioned for disposal 37

38 tainer s concrete surface, and no corrosion has been detected in the concrete reinforcements of the container. The test results were last reported in 2004 together with the results of the halfscale container test, and this procedure is to be repeated in Maintenance waste repository at the Loviisa power plant. use in May The construction and installation work of the earlier quarried solidified waste repository (KJT) started in the spring 2005, and they were completed at the same time as the seepage water pool built in the repository facilities. Finishing operations were carried out in The solidified waste repository will be needed for the disposal of waste packages to be brought from the solidification plant starting in Separate research programmes have been compiled for in-service research concerning the access tunnel and hall facilities. STUDIES ON SOLIDIFICATION METHODS Storage testing of radioactive ion exchange resin solidified in half-scale disposal containers in 1987 continued. The waste packages have been stored in groundwater at the Loviisa power plant for 21 years and, as expected, they are still in good condition. No structural damage has been detected in the concrete surface of the containers, and the composition of the storage water has been relatively stable. Radioactivity monitoring of the storage water has not revealed any signs of nuclide release from the solidified product contained in the concrete containers. The latest report on test results was drawn up in 2004, and the next report is due in In 1980, old inactive ion exchange resin from the Loviisa power plant was solidified in a full-scale disposal container. The disposal container was kept in storage until mid-1983, and it has since then been kept in slowly flowing fresh water at the Pyhäkoski power plant. The condition of the disposal container has been monitored after 1, 3, 5, 9, 13, 15 and 21 years of storage. Rusting can be clearly seen on the steel lifting lugs and fastenings but no structural damage has been detected on the con- IN-SERVICE STUDIES REGARDING THE REPOSITORY The in-service studies on the repository continued in 2009 in line with the monitoring programme. The aim of the programme is to investigate and monitor the characteristics and behaviour of groundwater and the bedrock in the immediate surroundings of the disposal facilities as well as long-term changes in their behaviour. The monitoring programme has included the monthly monitoring of groundwater levels in ground-level research holes. The position of fresh and so-called saline groundwater in the holes was measured on four occasions during the year. The electrical conductivity and pressure of groundwater as well as the seepage water volumes have been measured at the repository facilities once a month. Some pressure and seepage water measurements have also run continuously. The measurements concentrated on the seepage water pools and on the five purposebuilt groundwater stations. The research programme on groundwater chemistry included sampling and analysis of samples from groundwater stations LPVA3 and LPVA5. In addition, the results of samples taken in the previous year from station LPVA2 were reported. Bedrock monitoring has been performed mainly using an automated rock-mechanical measuring system. Visual inspections of the facilities also continued in The groundwater in the island of Hästholmen is characterized by the fact that its level clearly depends on the seawater level. This is most evident in deep boreholes where the groundwater level is close to the seawater level. In shallow holes, the level is a few metres higher, depending on the topography. During the time the repository facilities were being constructed, the groundwater level sank locally by a few metres in the areas 38

39 surrounding the facilities, but the slow rising of the levels has been observed since the facilities were completed. As a whole, no significant changes have taken place in water levels that seem to have stabilised roughly at the 1996 level. The borderline between fresh and saline groundwater has remained between levels -30 m and -80 m as in previous years, i.e. clearly above the repository facilities that are located roughly at level -110 m. The electrical conductivity measured in conjunction with seepage water measurements varies from one part of the facilities to another, as in previous years, in the range 500 1,600 ms/m. These values represent both the intermediate zone and the saline zone. The electrical conductivity increases with increasing depth (and salinity) and reaches its maximum value at station LPVA5 (level -110 m). The conductivity of seepage water pumped into the sea (a mixture of all seepage waters) has been about 1,200 ms/m on average. The analysis results of samples taken from groundwater stations have not significantly changed from previous years. The ph value at station LP- VA2 (7.4) has slightly increased (previous value 7.2 ± 0.1), while the ph at LPVA3 has remained constant (7.7 ± 0.1) since 1999, as has the ph at LP- VA5 (7.6 ± 0.1), which has been the same since The electrical conductivity and TDS values of groundwater were at LPVA2 1,340 ms/m and 7,600 mg/l, at LPVA3 1,100 ms/m and 5,800 mg/l, and at LPVA5 1,550 ms/m and 8,880 mg/l, respectively. The groundwater is of the Na-Ca-Cl type, and its TDS classification is that of brackish water. The effects of seawater level variations and location are clearly evident in the groundwater pressure values. The pressure increases with increasing depth and reaches its maximum value bar at station LPVA5 located at the lowest point (at an approximate level of -110 m) where it is about 10.3 bar, slightly lower that the theoretical value of 11 bar. The amount of seepage water was measured, as usual, at seven different points around the disposal facilities. After excavation work was completed in 1996, total seepage was about 300 l/min at its highest, from which it has fairly constantly fallen to about 80 l/min by the end of About half of the seepage water amount comes from the access tunnel and the other half from other facilities. Measurement results indicate that the maintenance waste facilities are practically dry. The results of rock-mechanical measurements show that the stability of the facilities has remained good and, for example, that the construction of the repository for solidified waste has not diminished the stability of rock in the immediate surroundings either. During the construction work in , more variations were observed in bedrock movements, mainly as a result of the higher temperature in the hall, but now the movements have returned to their pre-construction level. Extensometer measurements indicate that the dislocations taking place at the ceilings and walls of rock facilities have been of the same order as in previous years, below 0.1 mm. Bedrock movements in the vehicle access and connecting tunnel are monitored by convergence measurements that have a resolution of 0.5 mm. The results indicate that the movement has been smaller than 1 mm. The bedrock temperature near the facilities at a depth of -110 m is about 8 12 degrees. Visual inspection of the facilities indicates that their overall stability is Maintenance waste repository at the Loviisa power plant. 39