WorldWideScience

Sample records for backfilling

  1. Backfill design 2012

    International Nuclear Information System (INIS)

    Autio, J.; Hassan, M. M.; Karttunen, P.; Keto, P.

    2013-12-01

    This report describes both the concept and the detailed design of backfilling in KBS-3V deposition tunnels. The purpose of the backfill is to keep the buffer in place, maintain favourable and predictable conditions for the buffer and the canister, and also favourable rock mechanical, hydrological and geochemical conditions in the near-field and to retard the transport of released radionuclides in case of canister failure. In addition to the description of the overall backfill design, detailed designs for the components of the backfill (foundation, block and pellet fill) are provided in this report. The deposition tunnel end plug design is not presented in this document. In the backfill design, the deposition tunnels are to be filled with a foundation layer material, precompacted clay blocks and extruded bentonite pellets. The foundation layer consists of Milos bentonite granules, which are compacted in situ in order to level the deposition tunnel floor, providing an even and stable base for the block filling. On the foundation layer, a rigid assemblage of overlapping layers of pre-compacted blocks made of Friedland clay are installed. The void space between the blocks and the rock wall is filled with extruded pellets made of bentonite similar to raw material of Cebogel QSE product. (orig.)

  2. Cementitious backfill in mining

    Energy Technology Data Exchange (ETDEWEB)

    Taute, A; Spice, J; Wingrove, A C [Van Niekerk, Kleyn Edwards (South Africa)

    1993-03-01

    This article describes the need for increased usage of backfill material in mining and presents some of the considerations for use of cemented materials. Laboratory test results obtained using a variety of cementitious binders and mine tailings are presented. 3 figs., 1 tab.

  3. Uniaxial backfill block compaction

    International Nuclear Information System (INIS)

    Koskinen, V.

    2012-05-01

    The main parts of the project were: to make a literature survey of the previous uniaxial compaction experiments; do uniaxial compaction tests in laboratory scale; and do industrial scale production tests. Object of the project was to sort out the different factors affecting the quality assurance chain of the backfill block uniaxial production and solve a material sticking to mould problem which appeared during manufacturing the blocks of bentonite and cruched rock mixture. The effect of mineralogical and chemical composition on the long term functionality of the backfill was excluded from the project. However, the used smectite-rich clays have been tested for mineralogical consistency. These tests were done in B and Tech OY according their SOPs. The objective of the Laboratory scale tests was to find right material- and compaction parameters for the industrial scale tests. Direct comparison between the laboratory scale tests and industrial scale tests is not possible because the mould geometry and compaction speed has a big influence for the compaction process. For this reason the selected material parameters were also affected by the previous compaction experiments. The industrial scale tests were done in summer of 2010 in southern Sweden. Blocks were done with uniaxial compaction. A 40 tons of the mixture of bentonite and crushed rock blocks and almost 50 tons of Friedland-clay blocks were compacted. (orig.)

  4. SEEPAGE/BACKFILL INTERACTIONS

    International Nuclear Information System (INIS)

    Mariner, P.

    2000-01-01

    As directed by written development plan (CRWMS M andO 1999a), a sub-model of seepage/backfill interactions is developed and presented in this document to support the Engineered Barrier System (EBS) Physical and Chemical Environment Model. The purpose of this analysis is to assist Performance Assessment Operations (PAO) and the Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift. In this analysis, a conceptual model is developed to provide PAO a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). The development plan calls for a sub-model that evaluates the effect on water chemistry of chemical reactions between water that enters the drift and backfill materials in the drift. The development plan specifically requests an evaluation of the following important chemical reaction processes: dissolution-precipitation, aqueous complexation, and oxidation-reduction. The development plan also requests the evaluation of the effects of varying seepage and drainage fluxes, varying temperature, and varying evaporation and condensation fluxes. Many of these effects are evaluated in a separate Analysis/Model Report (AMR), ''Precipitates Salts Analysis AMR'' (CRWMS M andO 2000), so the results of that AMR are referenced throughout this AMR

  5. SEEPAGE/BACKFILL INTERACTIONS

    Energy Technology Data Exchange (ETDEWEB)

    P. Mariner

    2000-04-14

    As directed by written development plan (CRWMS M&O 1999a), a sub-model of seepage/backfill interactions is developed and presented in this document to support the Engineered Barrier System (EBS) Physical and Chemical Environment Model. The purpose of this analysis is to assist Performance Assessment Operations (PAO) and the Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift. In this analysis, a conceptual model is developed to provide PAO a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). The development plan calls for a sub-model that evaluates the effect on water chemistry of chemical reactions between water that enters the drift and backfill materials in the drift. The development plan specifically requests an evaluation of the following important chemical reaction processes: dissolution-precipitation, aqueous complexation, and oxidation-reduction. The development plan also requests the evaluation of the effects of varying seepage and drainage fluxes, varying temperature, and varying evaporation and condensation fluxes. Many of these effects are evaluated in a separate Analysis/Model Report (AMR), ''Precipitates Salts Analysis AMR'' (CRWMS M&O 2000), so the results of that AMR are referenced throughout this AMR.

  6. The influence of backfill on seismicity

    CSIR Research Space (South Africa)

    Hemp, DA

    1990-09-01

    Full Text Available , that the seismicity has been reduced in areas where backfill had been placed. A factor complicating the evaluation of backfill on seismicity is the effect of geological structures on seismicity....

  7. Stability of reinforced cemented backfills

    International Nuclear Information System (INIS)

    Mitchell, R.J.; Stone, D.M.

    1987-01-01

    Mining with backfill has been the subject of several international meetings in recent years and a considerable research effort is being applied to improve both mining economics and ore recovery by using backfill for ground support. Classified mill tailings sands are the most commonly used backfill material but these fine sands must be stabilized before full ore pillar recovery can be achieved. Normal portland cement is generally used for stabilization but the high cost of cement prohibits high cement usage. This paper considers the use of reinforcements in cemented fill to reduce the cement usage. It is concluded that strong cemented layers at typical spacings of about 3 meters in a low cement content bulk fill can reinforce the fill and reduce the overall cement usage. Fibre reinforcements introduced into strong layers or into bulk fills are also known to be effective in reducing cement usage. Some development work is needed to produce the ideal type of anchored fibre in order to realize economic gains from fibre-reinforced fills

  8. Preparation for YMP backfill activities

    International Nuclear Information System (INIS)

    Conca, J.

    1998-01-01

    Yucca Mountain activities for FY 1999 are anticipated to require specific information on the chemical and physical properties of the candidate getter materials and other backfill components necessary for defensible modeling of the source term, and possible controlling of the source term. There should be three tasks to this activity: at the end of this report is a draft test plan reflecting the present funding anticipated, the other tasks may be added as funding becomes available. (Task 1) The immobilization capacity of the getter materials for specific radionuclides. This task will primarily include column sorption tests of getter materials with solutions spiked with radionuclides. The getter materials will include Apatite II, MgO (with NaPO 4 plus Ba,SrCO 3 and soluble sulfate, with and without Apatite II), Gibbsite/Boehmite, and Hematite. Radionuclides will include Pu, U, Np, Am, Ra, Tc, and Th. Experiments will be performed under various anticipated repository conditions and with anticipated solution compositions. Occasional batch tests will be used to obtain specific K d s and other thermodynamic data. Solid and liquid analyses will be needed for characterization of the effluent concentrations from the columns to assess performance and for use in geochemical modeling. (Task 2) Intrinsic stability of the getter materials under repository conditions. The use of any candidate getter material will depend upon its anticipated lifetime in the backfill environment. Literature search for any existing data will be performed and augmented by solubility experiments on the getter materials. This is especially important for the reactive materials such as MgO and the soluble sulfates and phosphates that may be a limited lifetime in the backfill. It is also necessary to decide how much getter material to emplace. (Task 3) Diffusion of radionuclides across a Richards Barrier. The Richards Barrier, if emplaced, will act as a hydraulic diversion barrier for the diversion of

  9. Creep consolidation of nuclear depository backfill materials

    International Nuclear Information System (INIS)

    Butcher, B.M.

    1980-10-01

    Evaluation of the effects of backfilling nuclear waste repository rooms is an important aspect of waste repository design. Consolidation of the porous backfill takes place as the room closes with time, causing the supporting stress exerted by the backfill against the intact rock to increase. Estimation of the rate of backfill consolidation is required for closure rate predictions and should be possible if the creep law for the solid constituent is known. A simple theory describing consolidation with a spherical void model is derived to illustrate this relationship. Although the present form of the theory assumes a homogeneous isotropic incompressible material atypical of most rocks, it may be applicable to rock salt, which exhibits considerable plasticity under confined pressure. Application of the theory is illustrated assuming a simple steady-state creep law, to show that the consolidation rate depends on the externally applied stress, temperature, and porosity

  10. Installation of the backfill and plug test

    International Nuclear Information System (INIS)

    Gunnarsson, D.; Borgesson, L.; Hokmark, H.; Hohannesson, L.E.; Sanden, T.

    2003-01-01

    The Backfill and Plug Test is a full scale test of backfill material, backfilling technique and a tunnel plug. The main objectives of the Backfill and Plug Test are: - to develop and test different materials and compaction techniques for backfilling of tunnels excavated by blasting; - to test the function of the backfill and its interaction with the surrounding rock in a tunnel excavated by blasting; - to develop technique for building tunnel plugs and to test the function. The installation was made in the Swedish underground laboratory, Aspo HRL, during 1999. The inner part of the tunnel is not used for the test but was filled with drainage material. The test volume, which is about 28 m long, can be divided into the following three parts: - the inner part filled with backfill containing 30% bentonite; - the outer part filled with backfill without bentonite and bentonite blocks and pellets at the roof; - the plug. Permeable layers divide the test volume into 11 test sections. The permeable layers are used for increasing the water saturation rate in the backfill and for applying hydraulic gradients between the layers for studying the flow of water in the backfill and in the near field rock. The permeable layers were installed every 2.2 m and each layer is divided into three units in order to separately measure the flow close to the roof, in the central areas of the tunnel and close to the floor. The outer part ends with a wall of prefabricated concrete beams that were used for temporary support of the backfill during the casting of the plug. The upper volume close to the plug is filled with bentonite pellets and blocks consisting of 20% bentonite and 80% sand. The backfill is instrumented with 34 pore water pressure cells, 21 total pressure cells, 57 sensors for monitoring the water saturation and 13 gauges for measuring the local hydraulic conductivity. The water pressures in the permeable mats are measured in all sections. Four pressure cylinders, 2 in the roof

  11. Numerical modelling approach for mine backfill

    Indian Academy of Sciences (India)

    Muhammad Zaka Emad

    2017-07-24

    Jul 24, 2017 ... conditions. This paper discusses a numerical modelling strategy for modelling mine backfill material. The .... placed in an ore pass that leads the ore to the ore bin and crusher, from ... 1 year, depending on the mine plan.

  12. Backfilling of deposition tunnels, in situ alternative

    International Nuclear Information System (INIS)

    Keto, P.

    2007-04-01

    The backfilling process described in this report is based on in situ compaction of a mixture of bentonite and ballast (30:70) into the deposition tunnel. This method has been tested in practice in various field tests by SKB, most recently in the Prototype repository test performed at Aespoe HRL. The backfill mixture is prepared above ground and transported to the repository level with a tank truck. The material is compacted into layers with an inclination of 35 deg C and a thickness of approximately 20 cm. The compaction is performed with a vibratory plate attached to a boom of an excavator. In order to keep up with the required canister installation rate determined for the Finnish repository, at least 13 layers need to be compacted daily. This means working in 2-3 shifts on the working days that are available for backfilling operations. The dry densities achieved in field tests for the wall/roof section of the backfill have been insufficient compared with the dry density criteria set for the backfill. In theory, it may be possible to reach dry densities that fulfil the criteria, although with a relatively small safety margin. Another open issue is whether the mixture of bentonite and ballast has sufficient self-healing ability to seal-off erosion channels after the tunnels have been closed and the backfill has reached full saturation. (orig.)

  13. Colonization of compacted backfill materials by microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Lucht, L.M.; Stroes-Gascoyne, S.; Miller, S.H.; Hamon, C.J.; Dixon, D.A

    1997-11-01

    Experiments were carried out to investigate the occurrence of pore clogging in backfill by bacterial activity. Four differently prepared and treated backfill materials were used to determine the effects of the quality and preparation method of the backfill materials on the occurrence of pore clogging. The backfills were compacted in permeameters which were infused with either groundwater or sterile distilled water. A constant pressure was applied to increase the rate of saturation. Results showed different inflow rates for the four materials despite the use of the same packing method for each specimen, the same dry density for each backfill and indications of similar initial pore volumes. These differences were likely caused by the fact that the two slowest-flowing permeameters contained a mixture of Na-bentonite and illitic shale simulating a glacial lake clay. Hydraulic conductivities measured ranged from 5 x 10{sup -11} m/s to 5 x 10{sup -12} m/s for the backfills containing glacial lake clay and 4 x 10{sup -12} m/s to 9 s 10{sup -13} m/s for the backfills containing a mixture of Na-bentonite and illitic shale. Weekly samples of outflow from the permeameters were analyzed microbially. Aerobic heterotrophs were low initially but stabilized around 10{sup 6} to 10{sup 7} colony forming units (CFU)/mL after about one week. Anaerobic heterotrophs stabilized at around 10{sup 2} to 10{sup 3} CFU/mL. Sulphate-reducing bacteria (SRB) were measured by the most probable number (MPN) method. Results showed low initial numbers but they stabilized around 10{sup 4} MPN/mL after one to two months. No significant numbers of aerobic or anaerobic sulphur oxidizing bacteria were found. Enumeration of methanogens indicated that they were generally present in the permeameters that contained non-autoclaved backfill. Results are partially inconclusive because of the lack of confirmation of methane gas present in the headspace of part of the MPN culture tubes. Microbial pore clogging

  14. Colonization of compacted backfill materials by microorganisms

    International Nuclear Information System (INIS)

    Lucht, L.M.; Stroes-Gascoyne, S.; Miller, S.H.; Hamon, C.J.; Dixon, D.A.

    1997-11-01

    Experiments were carried out to investigate the occurrence of pore clogging in backfill by bacterial activity. Four differently prepared and treated backfill materials were used to determine the effects of the quality and preparation method of the backfill materials on the occurrence of pore clogging. The backfills were compacted in permeameters which were infused with either groundwater or sterile distilled water. A constant pressure was applied to increase the rate of saturation. Results showed different inflow rates for the four materials despite the use of the same packing method for each specimen, the same dry density for each backfill and indications of similar initial pore volumes. These differences were likely caused by the fact that the two slowest-flowing permeameters contained a mixture of Na-bentonite and illitic shale simulating a glacial lake clay. Hydraulic conductivities measured ranged from 5 x 10 -11 m/s to 5 x 10 -12 m/s for the backfills containing glacial lake clay and 4 x 10 -12 m/s to 9 s 10 -13 m/s for the backfills containing a mixture of Na-bentonite and illitic shale. Weekly samples of outflow from the permeameters were analyzed microbially. Aerobic heterotrophs were low initially but stabilized around 10 6 to 10 7 colony forming units (CFU)/mL after about one week. Anaerobic heterotrophs stabilized at around 10 2 to 10 3 CFU/mL. Sulphate-reducing bacteria (SRB) were measured by the most probable number (MPN) method. Results showed low initial numbers but they stabilized around 10 4 MPN/mL after one to two months. No significant numbers of aerobic or anaerobic sulphur oxidizing bacteria were found. Enumeration of methanogens indicated that they were generally present in the permeameters that contained non-autoclaved backfill. Results are partially inconclusive because of the lack of confirmation of methane gas present in the headspace of part of the MPN culture tubes. Microbial pore clogging was not evident for the two fastest

  15. Backfilling of deposition tunnels, block alternative

    International Nuclear Information System (INIS)

    Keto, P.; Roennqvist, P.-E.

    2007-03-01

    This report presents a preliminary process description of backfilling the deposition tunnels with pre-compacted blocks consisting of a mixture of bentonite and ballast (30:70). The process was modified for the Finnish KBS-3V type repository assuming that the amount of spent fuel canisters disposed of yearly is 40. Backfilling blocks (400 x 300 x 300 mm) are prepared in a block production plant with a hydraulic press with an estimated production capacity of 840 blocks per day. Some of the blocks are modified further to fit the profile of the tunnel roof. Prior to the installation of the blocks, the deposition tunnel floor is levelled with a mixture of bentonite and ballast (15:85). The blocks are placed in the tunnel with a modified reach truck. Centrifugal pellet throwing equipment is used to fill the gap between the blocks and the rock surface with bentonite pellets. Based on a preliminary assessment, the average dry density achieved with block backfill is sufficient to fulfil the criteria set for the backfill in order to ensure long-term safety and radiation protection. However, there are uncertainties concerning saturation, homogenisation, erosion, piping and self-healing of the block backfill that need to be studied further with laboratory and field tests. In addition, development efforts and testing concerning block manufacturing and installation are required to verify the technical feasibility of the concept. (orig.)

  16. Uranium mill tailings backfill management. Final report

    International Nuclear Information System (INIS)

    Thomson, B.M.; Heggen, R.J.

    1984-01-01

    Backfilling, the disposal of spent uranium mill tailings in empty mine stopes, has been practiced in the Grants Mineral Belt of New Mexico for nearly 20 years. The principal objective of backfilling is the prevention of roof collapse and hydraulic connection with overlying aquifers, increasing mine dewatering requirements. Backfilling is accomplished by gravity feed of a slurry of sand-fraction tailings and treated mine water into the slope. The effects of backfilling on surface discharge of mine wastewater are negligible due to the small fraction of the total flow represented by slurry decant. Furthermore, quality of the decant is not significantly below that of other mine waters. Groundwater effects of backfilling may be classified as short-term (while the mine is operational) and long-term (after dewatering operations have been terminated). Short-term effects are insignificant because of rapid and continuous flow to the mine sump. Long-term effects on aquifer water quality are predicted to be minimal due to (1) the small amount of slurry liquor present after drainage, (2) the precipitation of SO 4 and CO 3 phases, and (3) the reestablishment of reducing conditions and subsequent precipitation of major contaminants including U, As, Mo, Se, and V. 28 references, 19 figures, 9 tables

  17. Flow and solute transport in backfilled tunnel and collapsed backfill - possible extension of Comp32

    International Nuclear Information System (INIS)

    Neretnieks, Ivars

    2006-09-01

    In the Swedish deep geological final repository for spent fuel the tunnels will be filled with a backfill with low permeability. However, some flow may take place in the backfill. Nuclides released from a leaking canister could diffuse up to the flowing water in the backfill and be transported downstream in the tunnel. At an intersection of the tunnel with a fracture zone the contaminated water might flow out into the zone.This report addresses the transport mechanisms and rate of transport from a leaking canister up through the buffer and backfill in the deposition hole, further into the backfill in the tunnel and the transport along the tunnel. Spreading by diffusion in the buffer and backfill as well as retardation of sorbing nuclides is accounted for.The transport mechanisms and rates of transport are described and some simple models with analytical solutions are used to quantify the processes. These simple solutions are used to gain insights into when different transport mechanisms are important. The simple solutions are used to simulate a base case example where a non-sorbing nuclide (iodide) and a sorbing nuclide (radium) move in the backfill by diffusion and by advective flow. The simple sample calculations show that it would take thousands of years for iodide to move 20 m along the tunnel and that a release pulse would spread out considerably over time. The sorbing nuclide 226 Ra with a half life of 1,600 years would be strongly retarded by sorption and would decay to insignificance during its migration along the tunnel. The consequences of a collapse of backfill leaving a channel above the backfill is also studied by a simple analytical model that accounts for water flowing in the collapsed part of the backfill at the ceiling of the tunnel. A nuclide that diffuses up to the flowing channel will flow with the ('rapidly' flowing) water but will be retarded by diffusion down into the backfill again. This down diffusion retards the nuclide migration

  18. Flow and solute transport in backfilled tunnel and collapsed backfill - possible extension of Comp32

    Energy Technology Data Exchange (ETDEWEB)

    Neretnieks, Ivars [Royal Inst. of Technology, Stockholm (Sweden). Dept. of Chemical Engineering and Technology

    2006-09-15

    In the Swedish deep geological final repository for spent fuel the tunnels will be filled with a backfill with low permeability. However, some flow may take place in the backfill. Nuclides released from a leaking canister could diffuse up to the flowing water in the backfill and be transported downstream in the tunnel. At an intersection of the tunnel with a fracture zone the contaminated water might flow out into the zone.This report addresses the transport mechanisms and rate of transport from a leaking canister up through the buffer and backfill in the deposition hole, further into the backfill in the tunnel and the transport along the tunnel. Spreading by diffusion in the buffer and backfill as well as retardation of sorbing nuclides is accounted for.The transport mechanisms and rates of transport are described and some simple models with analytical solutions are used to quantify the processes. These simple solutions are used to gain insights into when different transport mechanisms are important. The simple solutions are used to simulate a base case example where a non-sorbing nuclide (iodide) and a sorbing nuclide (radium) move in the backfill by diffusion and by advective flow. The simple sample calculations show that it would take thousands of years for iodide to move 20 m along the tunnel and that a release pulse would spread out considerably over time. The sorbing nuclide {sup 226}Ra with a half life of 1,600 years would be strongly retarded by sorption and would decay to insignificance during its migration along the tunnel. The consequences of a collapse of backfill leaving a channel above the backfill is also studied by a simple analytical model that accounts for water flowing in the collapsed part of the backfill at the ceiling of the tunnel. A nuclide that diffuses up to the flowing channel will flow with the ('rapidly' flowing) water but will be retarded by diffusion down into the backfill again. This down diffusion retards the nuclide

  19. Jetting and flooding of granular backfill materials : [summary].

    Science.gov (United States)

    2015-03-01

    Granular backfill materials on highway projects are often compacted by mechanical methods. : This requires the contractor to place backfill material into loose lifts of varying thickness : and use compaction equipment to reduce air voids and increase...

  20. Assessment of backfill design for KBS-3V repository

    International Nuclear Information System (INIS)

    Keto, Paula; Dixon, David; Jonsson, Esther; Gunnarsson, David; Boergesson, Lennart; Hansen, Johanna

    2009-12-01

    Posiva and SKB initiated a joint programme BACLO (Backfilling and Closure of the Deep repository) in 2003 with the aim to develop methods and materials for backfilling of deposition tunnels. This report summarises the work done in the third and final phase of the BACLO programme. The main objective of this phase was to study how the various processes active during backfill installation and saturation as well as technical constraints affect its design basis. The work focused on the performance and technical feasibility of a block backfill concept, which calls for filling the majority of the tunnel volume with pre-compacted backfill blocks and the remaining volume with bentonite pellets. Several backfill composition alternatives were chosen for study and they consisted of clay materials with differing amounts of swelling minerals. A large body of information was gained on the effect of different processes on the performance of these backfill options, e.g. water inflow, piping, erosion, self-healing, homogenisation and interaction between backfill and buffer in various laboratory and small-scale field tests. More practical tests included e.g. studies how the blocks and pellets could be installed to the deposition tunnel. Based on the new information on the effect of the processes investigated and the estimated achievable block filling degree and backfill density, recommendations were made concerning material selection, backfill layout and technical issues. In addition, issues requiring further attention to verify the long-term performance of the proposed backfill concept are identified and listed

  1. Assessment of backfill design for KBS-3V repository

    Energy Technology Data Exchange (ETDEWEB)

    Keto, Paula (B+tech, Eurajoki (Finland)); Dixon, David (AECL, Harwell (United Kingdom)); Jonsson, Esther; Gunnarsson, David (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)); Boergesson, Lennart (Clay Technology AB, Lund (Sweden)); Hansen, Johanna (Posiva (Finland))

    2009-12-15

    Posiva and SKB initiated a joint programme BACLO (Backfilling and Closure of the Deep repository) in 2003 with the aim to develop methods and materials for backfilling of deposition tunnels. This report summarises the work done in the third and final phase of the BACLO programme. The main objective of this phase was to study how the various processes active during backfill installation and saturation as well as technical constraints affect its design basis. The work focused on the performance and technical feasibility of a block backfill concept, which calls for filling the majority of the tunnel volume with pre-compacted backfill blocks and the remaining volume with bentonite pellets. Several backfill composition alternatives were chosen for study and they consisted of clay materials with differing amounts of swelling minerals. A large body of information was gained on the effect of different processes on the performance of these backfill options, e.g. water inflow, piping, erosion, self-healing, homogenisation and interaction between backfill and buffer in various laboratory and small-scale field tests. More practical tests included e.g. studies how the blocks and pellets could be installed to the deposition tunnel. Based on the new information on the effect of the processes investigated and the estimated achievable block filling degree and backfill density, recommendations were made concerning material selection, backfill layout and technical issues. In addition, issues requiring further attention to verify the long-term performance of the proposed backfill concept are identified and listed

  2. Implementation of Paste Backfill Mining Technology in Chinese Coal Mines

    Science.gov (United States)

    Chang, Qingliang; Zhou, Huaqiang; Bai, Jianbiao

    2014-01-01

    Implementation of clean mining technology at coal mines is crucial to protect the environment and maintain balance among energy resources, consumption, and ecology. After reviewing present coal clean mining technology, we introduce the technology principles and technological process of paste backfill mining in coal mines and discuss the components and features of backfill materials, the constitution of the backfill system, and the backfill process. Specific implementation of this technology and its application are analyzed for paste backfill mining in Daizhuang Coal Mine; a practical implementation shows that paste backfill mining can improve the safety and excavation rate of coal mining, which can effectively resolve surface subsidence problems caused by underground mining activities, by utilizing solid waste such as coal gangues as a resource. Therefore, paste backfill mining is an effective clean coal mining technology, which has widespread application. PMID:25258737

  3. Tunnel backfill erosion by dilute water

    Energy Technology Data Exchange (ETDEWEB)

    Olin, M. [VTT Technical Research Centre of Finland, Espoo (Finland)

    2014-03-15

    The goal was to estimate smectite release from tunnel backfill due to dilute groundwater pulse during post glacial conditions. The plan was to apply VTT's two different implementations (BESW{sub D} and BESW{sub S}) of well-known model of Neretnieks et al. (2009). It appeared difficult to produce repeatable results using this model in COMSOL 4.2 environment, therefore a semi-analytical approximate approach was applied, which enabled to take into account both different geometry and smectite content in tunnel backfill as compared to buffer case. The results are quite similar to buffer results due to the decreasing effect of smaller smectite content and the increasing effect of larger radius. (orig.)

  4. Tunnel backfill erosion by dilute water

    International Nuclear Information System (INIS)

    Olin, M.

    2014-03-01

    The goal was to estimate smectite release from tunnel backfill due to dilute groundwater pulse during post glacial conditions. The plan was to apply VTT's two different implementations (BESW D and BESW S ) of well-known model of Neretnieks et al. (2009). It appeared difficult to produce repeatable results using this model in COMSOL 4.2 environment, therefore a semi-analytical approximate approach was applied, which enabled to take into account both different geometry and smectite content in tunnel backfill as compared to buffer case. The results are quite similar to buffer results due to the decreasing effect of smaller smectite content and the increasing effect of larger radius. (orig.)

  5. Some characteristics of potential backfill materials

    International Nuclear Information System (INIS)

    Simpson, D.R.

    1983-05-01

    A backfill material is one of the multiple barriers that may be involved in the disposal of nuclear waste. Such backfill should be a desiccant with the hydrous product having acceptable stability; it should sorb any released radioisotopes, and it should reseal any breached site. The backfill must also have acceptable thermal conductivity. This report presents data on the rate of hydration and the nature of the product of reaction of some candidate backfill materials with water and with brine. Thermal conductivity data is reported for both the reactants and the products. Granular MgO at 150 0 C completely hydrates in less than 10 hours. At 60 0 C and 20 0 C, such extensive hydration requires about 100 and 1000 hours, respectively. The product of the reaction is stable to more than 300 0 C. A doped discalcium silicate was less reactive and the product contains less water of crystallization than the MgO. The reaction product of dicalcium silicate is cementous, but it has low thermal stability. Bentonite readily reacts with water and expands. The reaction product has the properties of vermiculite, which indicates that magnesium ions have diffused into the bentonite structure and are not simply adsorbed on the surface. If bentonite is emplaced in a saline environment, the properties of vermiculite, the reaction product, should also be considered. The thermal conductivity of MgO, discalcium silicate, and bentonite is primarily dependent on the porosity of the sample. A slight increase in thermal conductivity was found with increased temperature, in contrast to most rocks. If the conductive data for the different materials is equated to the same porosity, MgO has the superior thermal conductivity compared to bentonite or discalcium silicate

  6. Numerical calculation of backfilling of scour holes

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu; Baykal, Cüneyt; Fuhrman, David R.

    2014-01-01

    A fully-coupled hydrodynamic and morphologic CFD model is presented for simulating backfilling processes around structures. The hydrodynamic model is based on Reynolds-averaged Navier-Stokes equations, coupled with two-equation k-ω turbulence closure. The sediment transport model consists of sepa...... of structures: piles, and pipelines. Initial scour holes are generated by the same model. The numerical results appear to be in accord with the existing experimental information....

  7. Maximum support resistance with steel arch backfilling

    Energy Technology Data Exchange (ETDEWEB)

    1983-01-01

    A system of backfilling for roadway arch supports to replace timber and debris lagging is described. Produced in West Germany, it is known as the Bullflex system and consists of 23 cm diameter woven textile tubing which is inflated with a pumpable hydraulically-setting filler of the type normally used in mines. The tube is placed between the back of the support units and the rock face and creates an early-stage interlocking effect.

  8. Backfilling with Fairness and Slack for Parallel Job Scheduling

    Energy Technology Data Exchange (ETDEWEB)

    Sodan, Angela C; Wei Jin, E-mail: acsodan@uwindsor.ca [University of Windsor, Computer Science, Windsor, Ontario (Canada)

    2010-11-01

    Parallel job scheduling typically combines a basic policy like FCFS with backfilling, i.e. moving jobs to an earlier than their regular scheduling position if they do not delay the jobs ahead in the queue according to the rules of the backfilling approach applied. Commonly used are conservative and easy backfilling which either have worse response times but better predictability or better response times and poor predictability. The paper proposes a relaxation of conservative backfilling by permitting to shift jobs within certain constraints to backfill more jobs and reduce fragmentation and subsequently obtain better response times. At the same time, deviation from fairness is kept low and predictability remains high. The results of the experimentation evaluation show that the goals are met, with response-time performance lying as expected between conservative and easy backfilling.

  9. Backfilling with Fairness and Slack for Parallel Job Scheduling

    International Nuclear Information System (INIS)

    Sodan, Angela C; Wei Jin

    2010-01-01

    Parallel job scheduling typically combines a basic policy like FCFS with backfilling, i.e. moving jobs to an earlier than their regular scheduling position if they do not delay the jobs ahead in the queue according to the rules of the backfilling approach applied. Commonly used are conservative and easy backfilling which either have worse response times but better predictability or better response times and poor predictability. The paper proposes a relaxation of conservative backfilling by permitting to shift jobs within certain constraints to backfill more jobs and reduce fragmentation and subsequently obtain better response times. At the same time, deviation from fairness is kept low and predictability remains high. The results of the experimentation evaluation show that the goals are met, with response-time performance lying as expected between conservative and easy backfilling.

  10. Assessment of the oxygen consumption in the backfill. Geochemical modelling in a saturated backfill

    International Nuclear Information System (INIS)

    Grandia, Fidel; Domenech, Cristina; Arcos, David; Duro, Lara

    2006-11-01

    The consumption of oxygen in the deep disposal is a major concern due to the ability of this element to corrode the canisters where high level nuclear wastes (HLNW) are disposed. The anoxic conditions initially present in a deep geologic environment are disturbed by the excavation of the repository facilities. After sealing the deposition holes and tunnels using clay-based materials, oxygen remains dissolved in porewater or as a gas phase in the unsaturated pores. The main mechanisms of oxygen depletion that can be considered in the backfill materials are: (1) diffusion into the surrounding rock and (2) kinetic reactions with accessory minerals and organic matter existing in the backfill. In this report, a set of numerical simulations are carried out in one and two dimensions in order to test the effect on the oxygen concentration in the pore water of all these mechanisms. The backfill considered is a 0/70 mixture of MX-80 bentonite and crushed material from the excavation itself. In addition to organic matter, the solid phases with reducing capacity in the backfill are Fe(II)-bearing minerals: pyrite (FeS 2 ) and siderite (FeCO) (as accessory minerals in the bentonite) and Fe-biotite (from the crushed granite). In the simulations, other chemical processes like cation exchange and surface complexation onto clay surfaces, and thermodynamic equilibrium with calcite, gypsum and quartz are considered. Initial composition of porewater is obtained by equilibrating the Forsmark groundwater with the backfill material. The 1D simulation consists of a number of cells with no reactive minerals or organic matter representing granite. The central cell, however, contains oxygen and reactive minerals resembling a backfill. Oxygen is allowed to move only by diffusion. The 2D model simulates the interaction with a backfill of a granitic groundwater flowing through a fracture. Like in the 1D model, the backfill contains oxygen and reactive solids. The results are very similar in

  11. Assessment of the oxygen consumption in the backfill. Geochemical modelling in a saturated backfill

    Energy Technology Data Exchange (ETDEWEB)

    Grandia, Fidel; Domenech, Cristina; Arcos, David; Duro, Lara [Enviros Spain S.L., Barcelona (Spain)

    2006-11-15

    The consumption of oxygen in the deep disposal is a major concern due to the ability of this element to corrode the canisters where high level nuclear wastes (HLNW) are disposed. The anoxic conditions initially present in a deep geologic environment are disturbed by the excavation of the repository facilities. After sealing the deposition holes and tunnels using clay-based materials, oxygen remains dissolved in porewater or as a gas phase in the unsaturated pores. The main mechanisms of oxygen depletion that can be considered in the backfill materials are: (1) diffusion into the surrounding rock and (2) kinetic reactions with accessory minerals and organic matter existing in the backfill. In this report, a set of numerical simulations are carried out in one and two dimensions in order to test the effect on the oxygen concentration in the pore water of all these mechanisms. The backfill considered is a 0/70 mixture of MX-80 bentonite and crushed material from the excavation itself. In addition to organic matter, the solid phases with reducing capacity in the backfill are Fe(II)-bearing minerals: pyrite (FeS{sub 2}) and siderite (FeCO) (as accessory minerals in the bentonite) and Fe-biotite (from the crushed granite). In the simulations, other chemical processes like cation exchange and surface complexation onto clay surfaces, and thermodynamic equilibrium with calcite, gypsum and quartz are considered. Initial composition of porewater is obtained by equilibrating the Forsmark groundwater with the backfill material. The 1D simulation consists of a number of cells with no reactive minerals or organic matter representing granite. The central cell, however, contains oxygen and reactive minerals resembling a backfill. Oxygen is allowed to move only by diffusion. The 2D model simulates the interaction with a backfill of a granitic groundwater flowing through a fracture. Like in the 1D model, the backfill contains oxygen and reactive solids. The results are very similar in

  12. Tire Shred Backfill in Mechanically Stabilized Earth Wall Applications

    OpenAIRE

    Balunaini, Umashankar; Yoon, Sungmin; Prezzi, Monica; Salgado, Rodrigo

    2009-01-01

    Tire shred-soil mixture backfill for use in mechanically stabilized earth (MSE) walls has several advantages over traditional backfill materials: 1) good drainage, 2) high shear strength, 3) low compacted unit weight and 4) low lateral pressure exerted on retaining structures. This work presents the results of laboratory tests performed on tire shred-sand mixtures focusing on determining the properties required for their use as backfill in MSE wall applications. Three sizes of tire shreds are...

  13. Migration of radionuclides through backfill in a nuclear waste repository

    International Nuclear Information System (INIS)

    Lung, H.

    1986-01-01

    Four models are analyzed to predict the performance of a backfill layer as part of the waste package emplacement in a nuclear waste repository. The corresponding computer code for each model is also developed. The time-dependent mass transfer analysis on a spherical waste-backfill geometry indicates that the radioactive decay effect can enhance the mass transfer rate from the backfill instead of reducing it. The analysis yields the breakthrough time of the backfill layer, which in turn characterizes the backfill performance. A non-linear (Langmuir) sorption isotherm is used to describe the sorption saturation in the backfill. The steady state mass transport analysis through a prolate spheroidal waste-backfill geometry shows that a simple formula can be used to calculate the individual resistances to mass transport in backfill and in host rock. A general, non-recursive analytical solution is derived for a radioactive decay chain of arbitrary length in either a finite or a semi-infinite medium. Numerical examples are given for different boundary conditions and for different decay chains. The results justify that for a backfill layer made of low permeability material, a zero water velocity can be used in the backfill analysis. It is also shown that under normal repository conditions, the mass transfer rate from the backfill is quite small. For the daughter member with a smaller retardation coefficient than that of the mother nuclide, such as 226 Ra in the 234 U → 230 Th → 226 Ra chain, an interior maximum in the concentration profile appears in the backfill. This phenomenon can be seen only in a chain calculation

  14. Status of Sandia backfill-getter development studies

    International Nuclear Information System (INIS)

    Molecke, M.A.; Nowak, E.J.

    1980-01-01

    In this paper, specific functions desired of the backfill as well as various recent experimental studies, results, and current plans for further studies, and modeling of the backfill's effectiveness for delaying radionuclide release are presented. Experimental studies and results are as follows: smectite swelling clay, bentonite, has been selected as a major component in the backfill because of its favorable properties in contact with salt and brine solution; sorptive properties for Pu and Am in batch and column-type experiments are being measured; various materials such as synthetic zeolites, titanates, and charcoal show promise for sorbing fission products in brine; mechanisms of backfill alteration or degradation which may cause the backfill barrier to lose some of its chemical and physical effectiveness is being investigated, with pH, Eh, temperature, pressure, radiation, and backfill-getter overall composition as parameters of interest; hydrothermal backfill-brine reactions have been studied experimentally; geotechnical measurements on bentonite and bentonite-sand mixtures have yielded brine and water permeabilities in the microdarcy range; and engineering-scale work on backfill emplacement forms and techniques to be used in a repository is under investigation, and will culminate with an actual demonstration of backfill emplacement in a field test

  15. Development of a tunnel backfilling concept for nuclear waste disposal

    International Nuclear Information System (INIS)

    Gunnarsson, D.; Borgesson, L.

    2003-01-01

    In the main concept for disposal of the Swedish Nuclear Waste (KBS-3V) it is vital that the drifts can be backfilled with sufficiently good material at high density to fulfill the following requirements: - to obstruct upwards swelling of bentonite from the deposition holes, - to prevent or restrict the water flow in the tunnel and around the canister, - to resist chemical conversion for a long period of time, - not to cause any significant chemical conversion of the buffer surrounding the canister. Investigations and tests of backfill material and techniques have been running in the Swedish underground laboratory, Aspo HRL, since 1996. In the first test, Field Test of Tunnel Backfilling, the objectives were to test the manufacturing of backfill material, to develop and test a backfilling technique and to investigate what densities could be achieved with different backfill materials in the field. Horizontal layers were applied and compacted by a roller in 0.2 m thick layers to 1.5 m from the floor. The rest of the tunnel was backfilled with inclined layers. Five different backfill materials were tested; TBM-muck, TBM-muck crushed to a maximum grain size of 20 mm and crushed TBM-muck mixed with 10, 20 and 30% MX-80 bentonite. The main conclusions from these tests were that the technique for manufacturing backfill material and for backfilling the tunnel were suitable but that the horizontal backfill layers were sensitive to wet conditions, that the backfilling equipment needed to be improved to better reach the areas close to the rock walls and roof and that the durability of the equipment needed to be improved. For the continued development for the Backfill and Plug Test and the Prototype Repository it was decided that the backfilling should be made with inclined layers in the entire cross section of the tunnel in order to decrease the sensitivity to water inflow. The backfilling equipment was improved; two new compactors, the so-called slope compactor and the so

  16. Development of a tunnel backfilling concept for nuclear waste disposal

    Energy Technology Data Exchange (ETDEWEB)

    Gunnarsson, D.; Borgesson, L. [Clay Technology AB, Ideon, Lund (Sweden)

    2003-07-01

    In the main concept for disposal of the Swedish Nuclear Waste (KBS-3V) it is vital that the drifts can be backfilled with sufficiently good material at high density to fulfill the following requirements: - to obstruct upwards swelling of bentonite from the deposition holes, - to prevent or restrict the water flow in the tunnel and around the canister, - to resist chemical conversion for a long period of time, - not to cause any significant chemical conversion of the buffer surrounding the canister. Investigations and tests of backfill material and techniques have been running in the Swedish underground laboratory, Aspo HRL, since 1996. In the first test, Field Test of Tunnel Backfilling, the objectives were to test the manufacturing of backfill material, to develop and test a backfilling technique and to investigate what densities could be achieved with different backfill materials in the field. Horizontal layers were applied and compacted by a roller in 0.2 m thick layers to 1.5 m from the floor. The rest of the tunnel was backfilled with inclined layers. Five different backfill materials were tested; TBM-muck, TBM-muck crushed to a maximum grain size of 20 mm and crushed TBM-muck mixed with 10, 20 and 30% MX-80 bentonite. The main conclusions from these tests were that the technique for manufacturing backfill material and for backfilling the tunnel were suitable but that the horizontal backfill layers were sensitive to wet conditions, that the backfilling equipment needed to be improved to better reach the areas close to the rock walls and roof and that the durability of the equipment needed to be improved. For the continued development for the Backfill and Plug Test and the Prototype Repository it was decided that the backfilling should be made with inclined layers in the entire cross section of the tunnel in order to decrease the sensitivity to water inflow. The backfilling equipment was improved; two new compactors, the so-called slope compactor and the so

  17. Backfilling of trenches exposed to waves

    DEFF Research Database (Denmark)

    Hjelmager Jensen, Jacob; Fredsøe, Jørgen

    1997-01-01

    This paper treats the numerical prediction of initial and long-term morphology of small pipeline trenches. For this purpose a refined flow and sediment transport description is applied such that the entire mathematical problem is formulated and solved on a curvilinear grid using a k - ε turbulence......-closure. The backfilling process of trenches exposed to either waves or a steady current is of importance in relation to the implementation of pipelines in the marine environment. With respect to the sedimentation of trenches, the non-dimensional Trench-Keulegan-Carpenter number, KC = a/L, where a is the excursion length...

  18. 30 CFR 816.105 - Backfilling and grading: Thick overburden.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Backfilling and grading: Thick overburden. 816...-SURFACE MINING ACTIVITIES § 816.105 Backfilling and grading: Thick overburden. (a) Definition. Thick... surrounding terrain. (b) Performance standards. Where thick overburden occurs within the permit area, the...

  19. Backfilling and closure of the deep repository. Assessment of backfill concepts

    International Nuclear Information System (INIS)

    Gunnarsson, David; Boergesson, Lennart; Keto, Paula; Tolppanen, Pasi; Hansen, Johanna

    2004-06-01

    This report presents the results from work made in Phase 1 of the joint SKB-Posiva project 'Backfilling and Closure of the Deep Repository' aiming at selecting and developing materials and techniques for backfilling and closure of a KBS-3 type repository for spent nuclear fuel. The aim of phase 1, performed as a desk study, was to describe the potential of the suggested backfill concepts in terms of meeting SKB and Posiva requirements, select the most promising ones for further investigation, and to describe methods that can be used for determining the performance of the concepts. The backfilling concepts described in this report differ from each other with respect to backfill materials and installation techniques. The concepts studied are the following: Concept A: Compaction of a mixture of bentonite and crushed rock in the tunnel. Concept B: Compaction of natural clay with swelling ability in the tunnel. Concept C: Compaction of non-swelling soil type in the tunnel combined with application of pre-compacted bentonite blocks at the roof. Concept D: Placement of pre-compacted blocks; a number of materials are considered. Concept E: Combination of sections consisting of a) crushed rock compacted in the tunnel and b) pre-compacted bentonite blocks. The bentonite sections are installed regularly above every disposal hole. Concept F: Combination of sections consisting of a) crushed rock compacted in the tunnel and b) pre-compacted bentonite blocks. The distance between the bentonite sections is adapted to the local geology and hydrology.The assessment of the concepts is based on performance requirements set for the backfill in the deposition tunnels for providing a stable and safe environment for the bentonite buffer and canister for the repository service time. In order to do this, the backfill should follow certain guidelines, 'design criteria' concerning compressibility, hydraulic conductivity, swelling ability, long-term stability, effects on the barriers and

  20. Backfilling and closure of the deep repository. Assessment of backfill concepts

    Energy Technology Data Exchange (ETDEWEB)

    Gunnarsson, David; Boergesson, Lennart [Clay Technology AB, Lund (Sweden); Keto, Paula [Saanio Riekkola Oy (Finland); Tolppanen, Pasi [Jaakko Poeyry Infra (Finland); Hansen, Johanna [Posiva Oy, Helsinki (Finland)

    2004-06-01

    This report presents the results from work made in Phase 1 of the joint SKB-Posiva project 'Backfilling and Closure of the Deep Repository' aiming at selecting and developing materials and techniques for backfilling and closure of a KBS-3 type repository for spent nuclear fuel. The aim of phase 1, performed as a desk study, was to describe the potential of the suggested backfill concepts in terms of meeting SKB and Posiva requirements, select the most promising ones for further investigation, and to describe methods that can be used for determining the performance of the concepts. The backfilling concepts described in this report differ from each other with respect to backfill materials and installation techniques. The concepts studied are the following: Concept A: Compaction of a mixture of bentonite and crushed rock in the tunnel. Concept B: Compaction of natural clay with swelling ability in the tunnel. Concept C: Compaction of non-swelling soil type in the tunnel combined with application of pre-compacted bentonite blocks at the roof. Concept D: Placement of pre-compacted blocks; a number of materials are considered. Concept E: Combination of sections consisting of a) crushed rock compacted in the tunnel and b) pre-compacted bentonite blocks. The bentonite sections are installed regularly above every disposal hole. Concept F: Combination of sections consisting of a) crushed rock compacted in the tunnel and b) pre-compacted bentonite blocks. The distance between the bentonite sections is adapted to the local geology and hydrology.The assessment of the concepts is based on performance requirements set for the backfill in the deposition tunnels for providing a stable and safe environment for the bentonite buffer and canister for the repository service time. In order to do this, the backfill should follow certain guidelines, 'design criteria' concerning compressibility, hydraulic conductivity, swelling ability, long-term stability, effects on

  1. Concepts for backfilling and sealing of shafts

    International Nuclear Information System (INIS)

    Pierau, B.

    1990-01-01

    The disposal site is situated at a depth of 1000 to 1200 meters. It is covered by very thick cretatious mudstone layers forming the main barrier against the spread of radioactively contaminated water into the biosphere. Because of the excavation works and the resulting stress redistributions, the material surrounding the shafts is probably broken up, which leads to increased permeability in comparison with the intact rock. It is planned to backfill the shafts with an insoluble mineral mixture including a fine fraction necessary to achieve the sealing required. The joints and cracks in the brocken-up surrounding material are believed to be sealed by themselves due to swelling of the mudstone. Some strata of the mudstone contain more than 20% of smektite, a swelling clay mineral. Those regions, where the broken-up zone cannot be considered sure to self-seal due to swelling, are planned to be sealed by pressure grouting using clay suspension. (orig./HP) [de

  2. Backfilling techniques and materials in underground excavations: Potential alternative backfill materials in use in Posiva's spent fuel repository concept

    International Nuclear Information System (INIS)

    Dixon, D.A.; Keto, P.

    2009-05-01

    A variety of geologic media options have been proposed as being suitable for safely and permanently disposing of spent nuclear fuel or fuel reprocessing wastes. In Finland the concept selected is construction of a deep repository in crystalline rock (Posiva 1999, 2006; SKB 1999), likely at the Olkiluoto site (Posiva 2006). Should that site prove suitable, excavation of tunnels and several vertical shafts will be necessary. These excavations will need to be backfilled and sealed as emplacement operations are completed and eventually all of the openings will need to be backfilled and sealed. Clay-based materials were selected after extensive review of materials options and the potential for practical implementation in a repository and work over a 30+ year period has led to the development of a number of workable clay-based backfilling options, although discussion persists as to the most suitable clay materials and placement technologies to use. As part of the continuous process of re-evaluating backfilling options in order to provide the best options possible, placement methods and materials that have been given less attention have been revisited. Primary among options that were and continue to be evaluated as a potential backfill are cementitious materials. These materials were included in the list of candidate materials initially screened in the late 1970's for use in repository backfilling. Conventional cement-based materials were quickly identified as having some serious technical limitations with respect their ability to fulfil the identified requirements of backfill. Concerns related to their ability to achieve the performance criteria defined for backfill resulted in their exclusion from large-scale use as backfill in a repository. Development of new, less chemically aggressive cementitious materials and installation technologies has resulted in their re-evaluation. Concrete and cementitious materials have and are being developed that have chemical, durability

  3. The stochastic nuclide transport model for buffer/backfill materials

    International Nuclear Information System (INIS)

    Ma Liping; Han Yongguo

    2014-01-01

    Currently, study on nuclide migration law in geological disposal repository of high level waste is assumed buffer/backfill layer to be continuous medium, utilized the continuity equation, equation of state, the equations of motion, etc, formed a set of theory and method to estimate nuclide concentration distribution in buffer/backfill layer, and provided an important basis for nuclide migration rules of repository. However, it is necessary to study the buffer/backfill layer microstructure and subtly describe the pore structure and fracture system of the buffer/backfill layer, and reflect the changes in connectivity and in different directions of the buffer/backfill layer. Through using random field theory, the nuclide transport for the buffer/backfill layer in geological disposal repository of nuclear waste is described in the paper. This paper mainly includes that, t represents the time, ξ t ⊂ Z d = d represents the integer lattice, Z represents collectivity integers, d = l, 2, 3, for instance, d = 2, Z d = {(m, n) : m, n ∈ Z} the state point of ξ t is typically considered to be occupied by the nuclide concentration values of the buffer/backfill layer, ξ t also represents random set in the diagram of two dimensional integer lattice, namely, t ∈ [0, T], {ξ t ,0 ≤ t ≤ ⊂ T} Consequently, according to the stochastic process obtained above, the changes of the nuclide concentration values of the buffer/backfill layer or the buffer/backfill laboratory materials in the repository with the time can be known. (authors)

  4. Experimental Evaluation of Backfill in Scour Holes Around Offshore Monopiles

    DEFF Research Database (Denmark)

    Sørensen, Søren Peder Hyldal; Ibsen, Lars Bo; Frigaard, Peter

    2010-01-01

    be to allow the forming of a scour hole and hereby design the monopile with a larger penetration depth. The depth of the scour hole will change over time as the scour depth will increasewhen currents are dominating and backfilling of the scour hole will take placewhenwaves are dominating. Several researchers...... of the foundation for fatigue. A backfill test has been performed in the LargeWave Channel (GWK) of the Coastal Research Centre (FZK) in Hannover.The relative density of the backfilled soil material has based on soil samples and CPT measurements been determined to be in the range of 60–80%. The normalized time...

  5. Exchangeability of bentonite buffer and backfill materials

    Energy Technology Data Exchange (ETDEWEB)

    Savage, D. [Savage Earth Associates Ltd, Bournemouth (United Kingdom); Arthur, R. [Intera Inc, Ottawa, ON, (Canada); Luukkonen, A.

    2012-08-15

    Clay-based buffer and tunnel backfill materials are important barriers in the KBS-3 repository concept for final disposal of spent nuclear fuel in Finland. One issue that is relevant to material properties is the degree to which different bentonite compositions can be regarded as interchangeable. In Posiva's current repository design, the reference bentonite composition is MX-80, a sodium montmorillonite dominated clay. Posiva would like to be able to use bentonite with Ca-montmorillonite as the dominant clay mineral. However, at this stage, it is not clear what supporting data need to be acquired/defined to be able to place the state of knowledge of Ca-bentonite at the same level as that of Na-bentonite. In this report, the concept of bentonite exchangeability has been evaluated through consideration of how bentonite behaviour may be affected in six key performance-relevant properties, namely (1) mineralogical composition and availability of materials, (2) hydraulic conductivity, (3) mechanical and rheological properties, (4) long-term alteration, (5) colloidal properties, and (6) swelling pressure. The report evaluates implications for both buffer and backfill. Summary conclusions are drawn from these sections to suggest how bentonite exchangeability may be addressed in regulatory assessments of engineered barrier design for a future geological repository for spent fuel in Finland. Some important conclusions are: (a) There are some fundamental differences between Ca- and Na-bentonites such as colloidal behaviour, pore structure and long-term alteration that could affect the exchangeability of these materials as buffer or backfill materials and which should be further evaluated; (b) Additional experimental data are desirable for some issues such as long-term alteration, hydraulic properties and swelling behaviour, (c) The minor mineral content of bentonites is very variable, both between different bentonites and within the same bentonite type, it is not clear

  6. Time effects of water drainage from deposited back-fill

    International Nuclear Information System (INIS)

    Baranski, L.A.

    1976-01-01

    Time effects of water drainage from deposited back-fill in mine excavations are considered. The time dependence of drainage from the deposited material was determined from ''in situ'' measurements with the aid of radioisotope gauges. The measurements were performed for given drainage conditions and practically constant grain size composition. It was found that in a few hours after the end of the back-filling operation the mechanical properties of the deposited material are practically constant. (author)

  7. Electrical resisitivity of mechancially stablized earth wall backfill

    Science.gov (United States)

    Snapp, Michael; Tucker-Kulesza, Stacey; Koehn, Weston

    2017-06-01

    Mechanically stabilized earth (MSE) retaining walls utilized in transportation projects are typically backfilled with coarse aggregate. One of the current testing procedures to select backfill material for construction of MSE walls is the American Association of State Highway and Transportation Officials standard T 288: ;Standard Method of Test for Determining Minimum Laboratory Soil Resistivity.; T 288 is designed to test a soil sample's electrical resistivity which correlates to its corrosive potential. The test is run on soil material passing the No. 10 sieve and believed to be inappropriate for coarse aggregate. Therefore, researchers have proposed new methods to measure the electrical resistivity of coarse aggregate samples in the laboratory. There is a need to verify that the proposed methods yield results representative of the in situ conditions; however, no in situ measurement of the electrical resistivity of MSE wall backfill is established. Electrical resistivity tomography (ERT) provides a two-dimensional (2D) profile of the bulk resistivity of backfill material in situ. The objective of this study was to characterize bulk resistivity of in-place MSE wall backfill aggregate using ERT. Five MSE walls were tested via ERT to determine the bulk resistivity of the backfill. Three of the walls were reinforced with polymeric geogrid, one wall was reinforced with metallic strips, and one wall was a gravity retaining wall with no reinforcement. Variability of the measured resistivity distribution within the backfill may be a result of non-uniform particle sizes, thoroughness of compaction, and the presence of water. A quantitative post processing algorithm was developed to calculate mean bulk resistivity of in-situ backfill. Recommendations of the study were that the ERT data be used to verify proposed testing methods for coarse aggregate that are designed to yield data representative of in situ conditions. A preliminary analysis suggests that ERT may be utilized

  8. Tests to determine water uptake behaviour of tunnel backfill

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, David (Atomic Energy of Canada Limited (AECL) (Canada)); Anttila, S.; Viitanen, M. (Poeyry InfRa Oy (Finland)); Keto, Paula (Saanio and Riekkola Oy, Helsinki (Finland))

    2008-12-15

    A series of 27 large-scale tests have been completed at the 420 level of SKB's Aespoe Hard Rock Laboratory. These tests have examined the influence of natural Aespoe fracture zone water on the movement of water into and through assemblies of Friedland clay blocks and bentonite pellets/ granules. These tests have established the manner in which groundwater may influence backfill and backfilling operations at the repository-scale. Tests have established that it is critical to provide a clay block backfilling system with lateral support and confinement as quickly as possible following block installation. Exposure of the blocks to even low rates of water ingress can result in rapid loss of block cohesion and subsequent slumping of the block materials into the spaces between the blocks and the tunnel walls. Installation of granular or pelletized bentonite clay between the blocks and the walls resulted in a system that was generally stable and not prone to unacceptable short-term strains as water entered. Inflow of water into a backfilled volume does not result in uniform wetting of the pellet/granule filled volume and as a result there is the potential for rapid movement of water from the point(s) of ingress to the downstream face of the backfill. Depending on the inflow rate and flow path(s) developed this flow can be via discrete flow channels that are essentially non-erosive or else they can develop highly erosive flow paths through the clay block materials. Erosion generally tends to be highest in the period immediately following first water exit from the backfill and then decreases as preferential flow paths develop to channel the water directly through the backfill, bypassing large volumes of unsaturated backfill. At the scale examined in this study inflow rates of 0.1 l/min or less do not tend to be immediately problematic when the source is 0.6 m distant from the downstream face of the backfill. At larger scales or longer distances from the working face, it

  9. Tests to determine water uptake behaviour of tunnel backfill

    International Nuclear Information System (INIS)

    Dixon, David; Anttila, S.; Viitanen, M.; Keto, Paula

    2008-12-01

    A series of 27 large-scale tests have been completed at the 420 level of SKB's Aespoe Hard Rock Laboratory. These tests have examined the influence of natural Aespoe fracture zone water on the movement of water into and through assemblies of Friedland clay blocks and bentonite pellets/ granules. These tests have established the manner in which groundwater may influence backfill and backfilling operations at the repository-scale. Tests have established that it is critical to provide a clay block backfilling system with lateral support and confinement as quickly as possible following block installation. Exposure of the blocks to even low rates of water ingress can result in rapid loss of block cohesion and subsequent slumping of the block materials into the spaces between the blocks and the tunnel walls. Installation of granular or pelletized bentonite clay between the blocks and the walls resulted in a system that was generally stable and not prone to unacceptable short-term strains as water entered. Inflow of water into a backfilled volume does not result in uniform wetting of the pellet/granule filled volume and as a result there is the potential for rapid movement of water from the point(s) of ingress to the downstream face of the backfill. Depending on the inflow rate and flow path(s) developed this flow can be via discrete flow channels that are essentially non-erosive or else they can develop highly erosive flow paths through the clay block materials. Erosion generally tends to be highest in the period immediately following first water exit from the backfill and then decreases as preferential flow paths develop to channel the water directly through the backfill, bypassing large volumes of unsaturated backfill. At the scale examined in this study inflow rates of 0.1 l/min or less do not tend to be immediately problematic when the source is 0.6 m distant from the downstream face of the backfill. At larger scales or longer distances from the working face, it is

  10. Filling of recovered mining areas using solidifying backfill

    Directory of Open Access Journals (Sweden)

    Zeman Róbert

    2001-12-01

    Full Text Available The aim of this article is to explore the possibilities for filling recovered mining areas using solidifying backfill .The article describes the preparation of the backfill (backfill formulation with an eventual application using low quality sands, wastes from treatment plants and ash from power plants etc now to transport it as well as its application in practice. Advantageous and disadvantageous of this method are also mentioned.Several factors must be taken info consideration during the preparation process of the backfill mixture. Firstly, the quantities of each individual component must be constantly regulated. Secondly, the properties of each component must be respected. In addition, the needs of the pipeline transport system and the specific conditions of the recovered area to be filled must also be considered.Hydraulic transport and pneumo-hydraulic pipeline transport are used for handling the backfill. Pumps for transporting the solidifying backfill have to carry out demanding tasks.Due to the physical-mechanical properties of the backfill, only highly powerful pumps can be considered. Piston type pumps such as Abel Simplex and Duplex pumps with capacities of up to 100 m3.h-1 and operating pressures of up to 16 MPa would be suitable.This method has been applied abroad for different purposes. For example, solid backfill was used in the Hamr mine during exploitation of uranium using the room-and-pillar system mining method.In the Ostrava–Karvina Coal field, backfill was used in decontamination work, filling areas in a zone of dangerous deformations and for creating a dividing stratum during thick seam mining.Research info the use of solidifying backfill was also done in the Walsum mine in Germany. The aim of this research was:- to investigate the possibilities of filling a collapsing area in a working face using a solidifying mixture of power plant ash and water,- to verify whether towing pipelines proposed by the DMT corporation would be

  11. Application of Paste Backfill in Underground Coal Fires

    Science.gov (United States)

    Masniyom, M.; Drebenstedt, C.

    2009-04-01

    Coal fires are known from different coalfields worldwide. China, India, USA, Australia, Indonesia and South Africa are the main countries affected by coal fires. The fires is thermally intensive and cause numerous sinkholes, large-scale subsidence, air pollution, global warming, loss of mining productivity and increasing safety risk. The Wuda Inner Mongolia coalfield has been selected as a possible test area for paste backfill. The traditional methods, executed by fire fighting teams, by covering the coalfire areas with soil, blasting burning coal outcrops and injecting water in the subsurface fire pockets are continuously improved and extended. Initiatives to introduce modern techniques, such as backfill placement at fracture and borehole, to cool down the burning coal and cut off the air supply. This study is to investigate backfill materials and techniques suited for underground coal fires. Laboratory tests were carried out on physical, chemical and mechanical properties of different backfill materials and mixtures thereof. Special attention was paid to materials generated as by-products and other cheaply available materials e.g. fly ash from power plants. There is a good chance that one of the different material mixtures investigated can be used as a technically and economically viable backfill for underground coal fires.

  12. A historical review of Waste Isolation Pilot Plant backfill development

    International Nuclear Information System (INIS)

    Krumhansl, James L.; Molecke, Martin A.; Papenguth, Hans W.; Brush, Laurence H.

    2000-01-01

    Backfills have been part of Sandia National Laboratories' [Sandia's] Waste Isolation Pilot Plant [WIPP] designs for over twenty years. Historically, backfill research at Sandia has depended heavily on the changing mission of the WIPP facility. Early testing considered heat producing, high level, wastes. Bentonite/sand/salt mixtures were evaluated and studies focused on developing materials that would retard brine ingress, sorb radionuclides, and withstand elevated temperatures. The present-day backfill consists of pure MgO [magnesium oxide] in a pelletized form and is directed at treating the relatively low contamination level, non-heat producing, wastes actually being disposed of in the WIPP. Its introduction was motivated by the need to scavenging CO 2 [carbon dioxide] from decaying organic components in the waste. However, other benefits, such as a substantial desiccating capacity, are also being evaluated. The MgO backfill also fulfills a statutory requirement for assurance measures beyond those needed to demonstrate compliance with the US Environmental Protection Agency [EPA] regulatory release limits. However, even without a backfill, the WIPP repository design still operates within EPA regulatory release limits

  13. Research of Cemented Paste Backfill in Offshore Environments

    Science.gov (United States)

    Wang, Kun; Yang, Peng; Lyu, Wensheng; Lin, Zhixiang

    2018-01-01

    To promote comprehensive utilization of mine waste tailings and control ground pressure, filling mine stopes with cement paste backfill (CPB) is becoming the most widely used and applicable method in contemporary underground mining. However, many urgent new problems have arisen during the exploitation in offshore mines owing to the complex geohydrology conditions. A series of rheological, settling and mechanical tests were carried out to study the influences of bittern ions on CPB properties in offshore mining. The results showed that: (1) the bittern ion compositions and concentrations of backfill water sampled in mine filling station were similar to seawater. Backfill water mixed CPB slurry with its higher viscosity coefficient was adverse to pipeline gravity transporting; (2) Bleeding rate of backfill water mixed slurry was lower than that prepared with tap water at each cement-tailings ratio; (3) The UCS values of backfill water mixed samples were higher at early curing ages (3d, 7d) and then became lower after longer curing time at 14d and 28d. Therefore, for mine production practice, the offshore environments can have adverse effects on the pipeline gravity transporting and have positive effects on stope dewatering process and early-age strength growth.

  14. Piping and erosion in buffer and backfill materials. Current knowledge

    International Nuclear Information System (INIS)

    Boergesson, Lennart; Sanden, Torbjoern

    2006-09-01

    The water inflow into the deposition holes and tunnels in a repository will mainly take place through fractures in the rock and will lead to that the buffer and backfill will be wetted and homogenised. But in general the buffer and backfill cannot absorb all water that runs through a fracture, which leads to that a water pressure will be generated in the fracture when the inflow is hindered. If the counter pressure and strength of the buffer or backfill is insufficiently high, piping and subsequent erosion may take place. The processes and consequences of piping and erosion have been studied in some projects and several laboratory test series in different scales have been carried through. This brief report describes these tests and the results and conclusions that have emerged. The knowledge of piping and erosion is insufficient today and additional studies are needed and running

  15. Backfilling of deposition tunnels: Use of bentonite pellets

    International Nuclear Information System (INIS)

    Dixon, David; Sanden, Torbjoern; Jonsson, Esther; Hansen, Johanna

    2011-02-01

    The state of knowledge related to use of bentonite pellets as part of backfill or other gap filling components in repository applications is reviewed. How the pellets interact with adjacent sealing materials and the surrounding rock mass is a critical aspect in determining backfill behaviour. The key features and processes that determine how the pellet component of the KBS-3V deposition tunnel backfill will behave are discussed and recommendations related to what additional information needs to be developed are provided. Experiences related to pellet material composition, size, shape, placement options and more importantly, the density to which they can be placed all indicate that there are significant limitations to the achievable as-placed density of bentonite pellet fill. Low as-placed density of the pellet fill component of the backfill is potentially problematic as the outermost regions of tunnel backfill will be the first region of the backfill to be contacted by water entering the tunnels. It is also through this region that initial water movement along the length of the deposition tunnels will occur. This will greatly influence the operations in a tunnel, especially with respect to situations where water is exiting the downstream face of still open deposition tunnels. Pellet-filled regions are also sensitive to groundwater salinity, susceptible to development of piping features and subsequent mechanical erosion by through flowing water, particularly in the period preceding deposition tunnel closure. A review of the experiences of various organisations considering use of bentonite-pellet materials as part of buffer or backfill barriers is provided in this document. From this information, potential options and limitations to use of pellets or pellet-granule mixtures in backfill are identified. Of particular importance is identification of the apparent upper-limits of dry density to which such materials can to be placed in the field. These bounds will

  16. On the risk of liquefaction of buffer and backfill

    Energy Technology Data Exchange (ETDEWEB)

    Pusch, R. [Geodevelopment AB, Lund (Sweden)

    2000-10-01

    The necessary prerequisites for liquefaction of buffers and backfills in a KBS-3 repository exist but the stress conditions and intended densities practically eliminate the risk of liquefaction for single earthquakes with magnitudes up to M=8 and normal duration. For buffers rich in expandable minerals it would be possible to reduce the density at water saturation to 1,700 - 1,800 kg/m{sup 3} or even less without any significant risk of liquefaction, while the density at saturation of backfills with 10 - 15% expandable clay should not be reduced to less than about 1,900 kg/m{sup 3}. Since the proposed densities of both buffers and backfills will significantly exceed these minimum values it is concluded that there is no risk of liquefaction of the engineered soil barriers in a KBS-3 repository even for very significant earthquakes.

  17. On the risk of liquefaction of buffer and backfill

    International Nuclear Information System (INIS)

    Pusch, R.

    2000-10-01

    The necessary prerequisites for liquefaction of buffers and backfills in a KBS-3 repository exist but the stress conditions and intended densities practically eliminate the risk of liquefaction for single earthquakes with magnitudes up to M=8 and normal duration. For buffers rich in expandable minerals it would be possible to reduce the density at water saturation to 1,700 - 1,800 kg/m 3 or even less without any significant risk of liquefaction, while the density at saturation of backfills with 10 - 15% expandable clay should not be reduced to less than about 1,900 kg/m 3 . Since the proposed densities of both buffers and backfills will significantly exceed these minimum values it is concluded that there is no risk of liquefaction of the engineered soil barriers in a KBS-3 repository even for very significant earthquakes

  18. Ocean disposal of heat generating radioactive waste backfilling requirements

    International Nuclear Information System (INIS)

    1986-07-01

    This report describes the backfilling requirements arising from the disposal of HGW in deep ocean sediments. The two disposal options considered are the drilled emplacement method and the free fall penetrator method. The materials best suited for filling the voids in the two options are reviewed. Candidate materials are selected following a study of the property requirements of each backfill. Placement methods for the candidate materials, as well as the means available for verifying the quality of the filling, are presented. Finally, an assessment of the overall feasibility of each placement method is given. The main conclusion is that, although the proposed methods are feasible, further work is necessary to test in inactive trials each of the proposed filling methods. Moreover, it is difficult to envisage how two of the backfilling operations in drilled emplacement option can be verified by non destructive methods. (author)

  19. Backfilling of deposition tunnels: Use of bentonite pellets

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, David (Atomic Energy of Canada Limited (Canada)); Sanden, Torbjoern (Clay Technology AB (Sweden)); Jonsson, Esther (Swedish Nuclear Fuel and Waste Mangaement Co. (Sweden)); Hansen, Johanna (Posiva Oy (Finland))

    2011-02-15

    The state of knowledge related to use of bentonite pellets as part of backfill or other gap filling components in repository applications is reviewed. How the pellets interact with adjacent sealing materials and the surrounding rock mass is a critical aspect in determining backfill behaviour. The key features and processes that determine how the pellet component of the KBS-3V deposition tunnel backfill will behave are discussed and recommendations related to what additional information needs to be developed are provided. Experiences related to pellet material composition, size, shape, placement options and more importantly, the density to which they can be placed all indicate that there are significant limitations to the achievable as-placed density of bentonite pellet fill. Low as-placed density of the pellet fill component of the backfill is potentially problematic as the outermost regions of tunnel backfill will be the first region of the backfill to be contacted by water entering the tunnels. It is also through this region that initial water movement along the length of the deposition tunnels will occur. This will greatly influence the operations in a tunnel, especially with respect to situations where water is exiting the downstream face of still open deposition tunnels. Pellet-filled regions are also sensitive to groundwater salinity, susceptible to development of piping features and subsequent mechanical erosion by through flowing water, particularly in the period preceding deposition tunnel closure. A review of the experiences of various organisations considering use of bentonite-pellet materials as part of buffer or backfill barriers is provided in this document. From this information, potential options and limitations to use of pellets or pellet-granule mixtures in backfill are identified. Of particular importance is identification of the apparent upper-limits of dry density to which such materials can to be placed in the field. These bounds will

  20. Settlement in backfill pipelines: its causes and a novel online detection method

    CSIR Research Space (South Africa)

    Goosen, P

    2011-03-01

    Full Text Available always be determined reliably. This paper addresses what are considered to be the dominant parameters affecting backfill pipeline blockages. In particular, backfills with low water content and high cement content may undergo significant rheological...

  1. Evaluating the methodology and performance of jetting and flooding of granular backfill materials.

    Science.gov (United States)

    2014-11-01

    Compaction of backfill in confined spaces on highway projects is often performed with small vibratory plates, based : solely on the experience of the contractor, leading to inadequate compaction. As a result, the backfill is prone to : erosion and of...

  2. Backfilling and closure of the deep repository. Phase 3 - pilot tests to verify engineering feasibility. Geotechnical investigations made on unsaturated backfill materials

    International Nuclear Information System (INIS)

    Johannesson, Lars-Erik

    2008-12-01

    The investigations described in this report is a part of the third phase of the joint SKB-Posiva project 'Backfilling and Closure of the Deep Repository, BACLO'. The overall objective of the BACLO project is to develop backfilling concept for the deep repository that can be configured to meet SKB's and Posiva's requirements in the chosen repository sites. The project was divided into four phases, of which two have already been performed. The second phase of the BACLO project consisted of laboratory tests and deepened analyses of the investigated backfill materials and methods and resulted in recommendation to focus on the development and testing of the block placement concept with three alternative backfill materials. The third phase investigations comprise of laboratory and large-scale experiments aiming at testing the engineering feasibility of the concept. In addition, how site-specific constraints, backfilling method and materials affect the long-term functions of the barriers will be described and analysed in order to set design specifications for the backfill. The third phase of the BACLO project is divided into several subprojects. The work described in this report belongs to subproject 1 concerning processes during installation and saturation of the backfill that may affect the long-term function of the bentonite buffer and the backfill itself. One of the main functions of backfill is to restrict buffer expansion which can lead to decrease in buffer density in the deposition hole. The criterion used as a basis for the Baclo investigations was that the buffer density at saturation should not be below 1,950 kg/m 3 at the level of the canister. The same criterion was applied for the work described in this report. The upward swelling of the buffer and the enclosed compression of the backfill was first studied assuming that both the buffer and the backfill were saturated. The main objective of this work was to study a case where the buffer is fully saturated

  3. Backfilling and closure of the deep repository. Phase 3 - pilot tests to verify engineering feasibility. Geotechnical investigations made on unsaturated backfill materials

    Energy Technology Data Exchange (ETDEWEB)

    Johannesson, Lars-Erik (Clay Technology AB, Lund (Sweden))

    2008-12-15

    The investigations described in this report is a part of the third phase of the joint SKB-Posiva project 'Backfilling and Closure of the Deep Repository, BACLO'. The overall objective of the BACLO project is to develop backfilling concept for the deep repository that can be configured to meet SKB's and Posiva's requirements in the chosen repository sites. The project was divided into four phases, of which two have already been performed. The second phase of the BACLO project consisted of laboratory tests and deepened analyses of the investigated backfill materials and methods and resulted in recommendation to focus on the development and testing of the block placement concept with three alternative backfill materials. The third phase investigations comprise of laboratory and large-scale experiments aiming at testing the engineering feasibility of the concept. In addition, how site-specific constraints, backfilling method and materials affect the long-term functions of the barriers will be described and analysed in order to set design specifications for the backfill. The third phase of the BACLO project is divided into several subprojects. The work described in this report belongs to subproject 1 concerning processes during installation and saturation of the backfill that may affect the long-term function of the bentonite buffer and the backfill itself. One of the main functions of backfill is to restrict buffer expansion which can lead to decrease in buffer density in the deposition hole. The criterion used as a basis for the Baclo investigations was that the buffer density at saturation should not be below 1,950 kg/m3 at the level of the canister. The same criterion was applied for the work described in this report. The upward swelling of the buffer and the enclosed compression of the backfill was first studied assuming that both the buffer and the backfill were saturated. The main objective of this work was to study a case where the buffer is

  4. Ion-exchange equilibria and diffusion in engineered backfill

    International Nuclear Information System (INIS)

    Soudek, A.; Jahnke, F.M.; Radke, C.J.

    1984-01-01

    Engineered backfill can add confidence to confinement times of high-level nuclear waste stored in geologic media. This paper discusses the design and operation of a unique radial-flow diffusion cell to determine ion migration rates in backfill material under realistic repository conditions. New experimental results were reported for diffusion of CsCl in a background of NaCl into compacted bentonite and bentonite/quartz mixtures. Representation of the measured diffusion rates by the traditional, homogeneous porous-medium model significantly underestimates cesium penetration distances into the backfill. Surface diffusion is suggested as an additional mechanism by which cations transport in swollen montmorillonite; the surface diffusion coefficients for cesium is determined to be approximately 10 -7 cm 2 /s. An electrostatic site-binding model is developed for ion-exchange equilibria on montmorillonite clay. The effect of pH, ionic strength, and specific adsorption are evaluated and compared favorably to new, experimental exchange isotherms measured on disaggregated clay. The electrostatic site-binding model permits a prediction of the influence of backfill compaction on K/sub d/ values. We find that for strongly adsorbing cations, compactions has little effect. However, anions exhibit significant Donnan exclusion with clay compaction. 40 references, 12 figures

  5. Experimental Study of the Development of Scour and Backfilling

    DEFF Research Database (Denmark)

    Hartvig, Peres Akrawi; Thomsen, Jess Mccann; Frigaard, Peter

    2010-01-01

    This paper deals with the development of scour holes in time and space around individual offshore monopiles. It is based on physical flume tests of a model-scale pile subjected to current and/or irregular water waves. The main focus is on backfilling, i.e. the wave-induced or current...

  6. Ground motion studies in a backfilled stope at West Driefontein

    CSIR Research Space (South Africa)

    Goldbach, OD

    1991-10-01

    Full Text Available This report looks at the ground motion from 24 small magnitude seismic events recorded at various points inside a backfilled stope. The in-stope ground motion is compared to that recorded at an off-reef site. The seismic events are analysed...

  7. Backfill barriers for nuclear waste repositories in salt

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, E J; Odoj, R; Merz, E [eds.

    1981-06-01

    Backfill mixtures surrounding the waste form and canister can provide a neutral or slightly acidic, potentially reducing environment, prevent convective aqueous flow, and act as an effective radionuclide migration barrier. Bentonite is likely to remain hydrothermally stable but potentially sensitive to waste package interactions which could alter the pH, the ratio of dissolved wires, or the sorption properties of radionuclide species.

  8. Backfill composition for secondary barriers in nuclear waste repositories

    Science.gov (United States)

    Beall, Gary W.; Allard, Bert M.

    1982-01-01

    A backfill composition for sorbing and retaining hazardous elements of nuclear wastes comprises 50-70% by weight of quartz, 10-30% by weight of montmorillonite, 1-10% by weight of phosphate mineral, 1-10% by weight of ferrous mineral, 1-10% by weight of sulfate mineral and 1-10% by weight of attapulgite.

  9. Backfill formulations for a nuclear fuel waste disposal vault

    International Nuclear Information System (INIS)

    Yong, R.N.; Boonsinsuk, P.; Wong, G.; Ming, X.D.; Caporuscio, F.; Lytle, P.

    1987-01-01

    Atomic Energy of Canada Limited and Ontario Hydro are studying the concept of disposing of nuclear fuel wastes in a vault within the Canadian Shield. After nuclear waste containers have been emplaced in a vault, the vault will have to be backfilled permanently. A suitable backfill material should have low hydraulic conductivity and high radionuclide sorption capacity. The research was done with a goal of recommending a specification for formulating this backfill material. This report suggests that such a backfill material should be a mixture of coarse aggregates and swelling clay. Actual trial mixtures were prepared using crushed granite and natural Lake Agassiz clay. Various trial mixtures were subjected to constant-head permeability tests. The results indicate that the hydraulic conductivity of the aggregate-clay mixtures could be close to those of the clay (by itself) when the clay content was in the range of 25% or more. The resulting hydraulic conductivity of about 10 -10 m/s is considered to be low, especially since the maximum grain size is 19.1 mm. Selected mixtures were evaluated for free swell and swelling pressure, both of which increased with increasing clay content. When the clay content was 25%, the free swell was about 4%, compared with 6% for the 100% clay. The corresponding swelling pressure was about 16 kPa - in comparison to 48 kPa for the 100% clay. These results indicate that the proposed backfill material should contain about 25% clay, with a maximum grain size of 19.1 mm. The selected mixture was also tested to evaluate the effects of mixing methods, load-carrying capacity and compaction techniques suitable for the underground vault conditions. The proposed backfill material appeared to perform satisfactorily according to the criteria demanded. The backfill material proposed was further tested for its behaviour during water intake. The unsaturated hydraulic conductivity was found to be approximately 10 -10 m/s and the swelling pressure was

  10. The Buffer and Backfill Handbook. Part 2: Materials and techniques

    International Nuclear Information System (INIS)

    Pusch, Roland

    2001-12-01

    Improved technology and prospection yielding more pure and homogeneous raw materials for preparing buffers and backfills will ultimately outdate the clays and ballast materials described in the present part of the Handbook. It describes experimentally investigated materials of potential use in repositories but other, more suitable materials will replace them in the future. The Handbook will hence have to be reviewed regularly, making room for superior materials in future, upgraded Handbook versions. Buffer is the term for dense clay used for embedment of canisters with highly radioactive waste, while backfill is soil used for filling tunnels and shafts in repositories. Examples of soil materials of potential use as buffers and backfills in repositories of KBS-3 type are described in this part of the Handbook. They are: smectitic clay materials intended for preparation of buffers (canister-embedding clay) and used as clay component in artificially prepared tunnel and shaft backfills consisting of mixtures of clay and ballast. Ballast materials intended for backfilling of tunnels and shafts and used as components of artificially prepared backfills. Smectitic natural clay soils intended for use as buffers and backfills. Very fine-grained smectite clay used as grout for sealing rock fractures. In this part of the Handbook for Buffers and Backfills, description of various candidate materials will be made with respect to their mineral composition and physical properties, with respect to the groundwater chemistry that can be expected in a deep repository in Swedish bedrock. Chapter 3 deals with smectitic clay materials intended for embedment of heat-producing canisters with highly radioactive waste. Focus is on the nature of the buffer constituents, i. e. the smectite content, the non-expanding clay minerals colloidal and the accessory non-clay minerals as well as amorphous matter and organic substances. The dominant part of the chapter describes the occurrence and origin

  11. The Buffer and Backfill Handbook. Part 2: Materials and techniques

    Energy Technology Data Exchange (ETDEWEB)

    Pusch, Roland [Geodevelopment AB, Lund (Sweden)

    2001-12-01

    Improved technology and prospection yielding more pure and homogeneous raw materials for preparing buffers and backfills will ultimately outdate the clays and ballast materials described in the present part of the Handbook. It describes experimentally investigated materials of potential use in repositories but other, more suitable materials will replace them in the future. The Handbook will hence have to be reviewed regularly, making room for superior materials in future, upgraded Handbook versions. Buffer is the term for dense clay used for embedment of canisters with highly radioactive waste, while backfill is soil used for filling tunnels and shafts in repositories. Examples of soil materials of potential use as buffers and backfills in repositories of KBS-3 type are described in this part of the Handbook. They are: smectitic clay materials intended for preparation of buffers (canister-embedding clay) and used as clay component in artificially prepared tunnel and shaft backfills consisting of mixtures of clay and ballast. Ballast materials intended for backfilling of tunnels and shafts and used as components of artificially prepared backfills. Smectitic natural clay soils intended for use as buffers and backfills. Very fine-grained smectite clay used as grout for sealing rock fractures. In this part of the Handbook for Buffers and Backfills, description of various candidate materials will be made with respect to their mineral composition and physical properties, with respect to the groundwater chemistry that can be expected in a deep repository in Swedish bedrock. Chapter 3 deals with smectitic clay materials intended for embedment of heat-producing canisters with highly radioactive waste. Focus is on the nature of the buffer constituents, i. e. the smectite content, the non-expanding clay minerals colloidal and the accessory non-clay minerals as well as amorphous matter and organic substances. The dominant part of the chapter describes the occurrence and origin

  12. Analysis of factors affecting the stability of backfill materials

    International Nuclear Information System (INIS)

    Peacor, D.R.; Essene, E.J.; Lee, J.H.; Kuo, L.C.

    1984-01-01

    Storage of high-level nuclear waste in subsurface repositories involves a backfill material as a physical/chemical barrier between the solid waste canisters and host rock. Chemical, structural, and textural changes due to hydrothermal reaction may degrade the backfill performance over the life of the repository. In order to evaluate the potential for such changes, we have: (1) carried out hydrothermal experiments on candidate backfill materials (smectite, illite, basalt) under conditions analogous to those at the repository, (2) performed a complete characterization of these materials before and after hydrothermal treatment using EMPA, XRD, SEM/EDS, and, especially, STEM/AEM techniques, and (3) reviewed and analyzed geologic systems which are analogous to the backfill systems. These serve as natural experimental systems with ages up to many tens of millions of years. The Umtanum basalt contains up to 25% of immiscible, two-phase glasses and late opal and nontronite in fractures. These materials are especially subject to solution effects and the glass may provide K to groundwater. The kinetics of the smectite to illite and illite to muscovite transitions are primarily controlled by Al/Si diffusion which is sluggish, rather than by rapid alkali ion diffusion. Thus, even though smectite (bentonite), mixed-layer illite/smectite and illite are all metastable phases transitional to muscovite plus other phases, reactions occur so slowly that these phases are retained even within a geologic time scale for temperatures of approximately 150, 200 and 300 0 C, respectively. A high ratio of Ca/K (perhaps supplied by solution of calcite) inhibits the transitions. If clay layers are compacted to form a continuous matrix, water may be prevented from penetrating the backfill and promoting the clay mineral transition

  13. Disposal of coal combustion wastes in the hydraulic backfill process

    Science.gov (United States)

    Pierzyna, Piotr

    2017-11-01

    This article presents the results of studies regarding the physical properties of selected combustion by-products (CCPs) currently produced in the energy production industry. These properties have been compared with the requirements of the technologies applied in the Polish underground mines. The article gives special consideration to the application of the products in the hydraulic backfill technology. The possibility of using bottom-ashes and slags was considered. The amount of CCPs disposed in Polish hard coal mines is approximately 1.1 million Mg and the tendency is decreasing. In the past two years, approximately 100-150 thousand Mg of CCPs was used in the hydraulic backfill technology. The percentage of the fraction smaller than 0.1 mm is determining for the possibility of using a given type of CCPs in the backfill material. This practically excludes the possibility of using any fly ashes in that technology. In slags from conventional boilers and bottom ashes from fluidized bed boilers the fraction below 0.1 mm constitutes 25% of the total at maximum, which allows for their use in the materials used in hydraulic backfill as a component comprising from 30% to 60%, respectively. Slags (10 01 01) are characterized by the lack of bonding properties, which, in case of open backfill systems that are exposed to atmospheric conditions, constitutes an advantage in comparison to bottom ashes (10 01 24), which in turn definitely exhibit bonding properties. The solution of the problem of using bottom ashes is their supply and application on a current basis.

  14. Backfilling of KBS-3V deposition tunnels - possibilities and limitations

    International Nuclear Information System (INIS)

    Wimelius, Hans; Pusch, Roland

    2008-12-01

    By definition for the SKB repository concept, the backfill of KBS-3V deposition tunnels must be so designed that transport of dissolved matter is controlled by diffusion and not by advective water flow. This requires that the hydraulic conductivity of the backfill does not exceed about E-10 m/s. The backfilling materials also have to adequately resist compression caused by upward expansion of the buffer. It must also exert an effective pressure of at least 100 kPa on the rock in order to provide support to the rock and minimize spalling of the rock. These criteria are fulfilled by several approaches and options for backfill materials, placed and compacted layer wise or in the form of blocks of compacted clay powder. Based on the experience from comprehensive lab studies and considering practical issues, SKB has selected a concept where the major part of the backfill consists of stacked blocks that are surrounded by clay pellets. Using this concept a basis for a detailed evaluation, a study of three different techniques for placing the blocks has been undertaken. The three block placement techniques examined are the 'Block', 'Robot', and 'Module' methods. They involve different block sizes and techniques for handling and placing the blocks but the same way of preparing the foundation bed of the blocks and placing the pellet filling. The blasted tunnels have a varying cross section, caused by the orientation of the blast-holes. This requires that a varying fraction of blocks be installed in the backfilling along the blasted tunnel interval if sufficiently high density and low hydraulic conductivity is to be achieved. The efficiency of filling will depend on the type of clay used in the blocks. For example, using Friedland clay for block preparation, the filling efficiency must be 80% while it can be reduced to 60% if more smectite-rich clay is used. The use of a clay with high smectite content increases margins and is concluded to be superior from emplacement point

  15. Study on HDPE Mixed with Sand as Backfilled Material on Retaining Structure

    Science.gov (United States)

    Talib, Z. A.

    2018-04-01

    The failure of the retaining wall is closely related to backfill material. Granular soils such as sand and gravel are most suitable backfill material because of its drainage properties. However two basic materials are quite heavy and contribute high amount of lateral loads. This study was to determine the effectiveness High Density Polyethylene (HDPE) as a backfill material. HDPE has a lighter weight compare to the sand. It makes HDPE has potential to be used as backfill material. The objective of this study is to identify the most effective percentage of HDPE to replace sand as a backfill material. The percentage of HDPE used in this study was 20%, 30%, 50%, 75% and also 100%. Testing involved in this study were sieve analysis test, constant head permeability test, direct shear test and relative density test. The result shows that the HDPE can be used as backfilled material and save the cost of backfill material

  16. Backfilling of KBS-3V deposition tunnels - possibilities and limitations

    Energy Technology Data Exchange (ETDEWEB)

    Wimelius, Hans (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)); Pusch, Roland (Geodevelopment International AB, Lund (Sweden))

    2008-12-15

    By definition for the SKB repository concept, the backfill of KBS-3V deposition tunnels must be so designed that transport of dissolved matter is controlled by diffusion and not by advective water flow. This requires that the hydraulic conductivity of the backfill does not exceed about E-10 m/s. The backfilling materials also have to adequately resist compression caused by upward expansion of the buffer. It must also exert an effective pressure of at least 100 kPa on the rock in order to provide support to the rock and minimize spalling of the rock. These criteria are fulfilled by several approaches and options for backfill materials, placed and compacted layer wise or in the form of blocks of compacted clay powder. Based on the experience from comprehensive lab studies and considering practical issues, SKB has selected a concept where the major part of the backfill consists of stacked blocks that are surrounded by clay pellets. Using this concept a basis for a detailed evaluation, a study of three different techniques for placing the blocks has been undertaken. The three block placement techniques examined are the 'Block', 'Robot', and 'Module' methods. They involve different block sizes and techniques for handling and placing the blocks but the same way of preparing the foundation bed of the blocks and placing the pellet filling. The blasted tunnels have a varying cross section, caused by the orientation of the blast-holes. This requires that a varying fraction of blocks be installed in the backfilling along the blasted tunnel interval if sufficiently high density and low hydraulic conductivity is to be achieved. The efficiency of filling will depend on the type of clay used in the blocks. For example, using Friedland clay for block preparation, the filling efficiency must be 80% while it can be reduced to 60% if more smectite-rich clay is used. The use of a clay with high smectite content increases margins and is concluded to be

  17. Influence of regional support systems (pillars and backfill) on local areas and internal support requirements adjacent to that regional support.

    CSIR Research Space (South Africa)

    Squelch, AP

    2001-11-01

    Full Text Available was observed of backfill creating worse hangingwall conditions; instead it was observed that poor backfill placement was associated with the less favourable hangingwall conditions. • Generally, well placed backfill improves conditions in face areas... if it is kept close to the face and conventionally designed working area support that fits in well with the backfilling/mining cycle is implemented. Conversely, quality is not assured if backfill is not well placed. Also large fill-to-face distances...

  18. Federal Republic of Germany/backfilling and sealing program - outline

    International Nuclear Information System (INIS)

    Kappei, G.

    1986-01-01

    After 1978 the Asse salt mine was used exclusively for research work which serves to make available scientific and technical data for the planning, construction and operation of repositories for radioactive wastes. This presentation delineates the advantages of the geological formation rock salt with a view to the final disposal of radioactive wastes subsequent to a short description of the 'Waste Management Concept' of the Federal Republic of Germany. The individual components of the internationally accepted 'Multiple Barrier System' are described, while the technical barriers 'backfilling and sealing' are subject of special consideration. A general formulation of the requirements and objectives of each specific component in the backfilling and sealing system is presented. (orig./DG)

  19. Geotechnical investigations on backfill materials in the Asse salt mine

    International Nuclear Information System (INIS)

    Kappei, G.

    1986-01-01

    The compression behaviour of rock salt grit is being investigated by compression tests at the Asse salt mine. The various test parameters are introduced and their results are discussed. The permeability of rock salt grit with saturated NaCl-brine in dependency upon the grain size and compactness, resp. the porosity, is being determined at the Asse salt mine. The test equipment and the results determined here are shown. In addition to laboratory tests, geotechnical investigations are taking place in a carnallitic chamber of the Asse salt mine which had been backfilled in earlier years. They chiefly concern measurements of the deformation rates in drifts - which were mined between the chambers in remaining pillars - as well as horizontal deformation measurements in the backfilling. (orig./DG)

  20. Transport of soluble species in backfill and rock

    International Nuclear Information System (INIS)

    Chambre, P.L.; Lee, W.W.L.; Light, W.B.; Pigford, T.H.

    1992-03-01

    In this report we study the release and transport of soluble species from spent nuclear fuel. By soluble species we mean a fraction of certain fission product species. Our previously developed methods for calculating release rates of solubility-limited species need to be revised for these soluble species. Here we provide methods of calculating release rates of soluble species directly into rock and into backfill and then into rock. Section 2 gives a brief discussion of the physics of fission products dissolution from U0 2 spent fuel. Section 3 presents the mathematics for calculating release rates of soluble species into backfill and then into rock. The calculation of release rates directly into rock is a special case. Section 4 presents numerical illustrations of the analytic results

  1. Backfill barriers for nuclear waste repositories in salt

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, E J; Odoj, R; Merz, E [eds.

    1981-06-01

    Backfill materials were evaluated for containment of radionuclides, chemical modification of brine, and sensitivity to hydrothermal conditions. Experimental conditions were relevant to nuclear waste isolation in bedded salt. They were based on geologic conditions at the site of the Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico, USA. Conclusions are: backfill mixtures surrounding the waste form and canister can provide a neutral or slightly acidic, potentially reducing environment, prevent convective aqueous flow, and act as an effective radionuclide migration barrier; bentonite is likely to remain hydrothermally stable but potentially sensitive to waste package interactions which could alter the pH, the ratio of dissolved ions, or the sorption properties of radionuclide species; effects of irradiation from high level waste should be investigated.

  2. Bentonite as a backfill material for shallow land repositories

    International Nuclear Information System (INIS)

    Yalmali, V.S.; Deshingkar, D.S.

    2001-01-01

    Two commercially available indigenous bentonite samples were evaluated for their cesium and strontium sorption properties in distilled water and surface water. By converting them into sodium form, the distribution coefficients for both cesium (I) and strontium (II) increased. Sodium bentonite was recommended because of high sorption capacity for Cs(I), Mg(II) and Sr(II) for use as backfill material in shallow land repositories where cement waste form containing Cs, Sr and Be wastes are disposed. (author)

  3. Studies of the behaviour of backfill taking into account the interaction between rock and backfill, and other sealing components at a salina repository

    International Nuclear Information System (INIS)

    Diekmann, N.; Stuehrenberg, D.

    1991-09-01

    According to the present planning level of the designed Gorleben repository, the salt produced by opening up cavities for ultimate disposal will be used as salt fines for backfilling residual cavities after radioactive waste emplacement. The essential function properties of the backfill - compaction and permeability - were studied for salt fines, and the results achieved were discussed. (BBR) [de

  4. Optimum permeability for a cement based backfill material

    International Nuclear Information System (INIS)

    Jacobs, F.; Wittmann, F.H.; Iriya, K.

    1989-01-01

    In Switzerland it is planned to dispose low- and intermediate radioactive waste (LLW/ILW) in an underground repository. Between the materials present in a repository different chemical reactions may occur. Due to radiolytic decomposition, microbiological degradation and corrosion gas (mainly hydrogen) may be produced. The release of gas can cause the build-up of pressure in the cavern and finally lead to the formation of cracks and/or serious damage in the concrete structure or host rock. Through cracks a contamination of the groundwater and the biosphere could be possible. This investigation develops a suitable cement based material which can be used as backfill for the repository. Besides other aspects mentioned later a suitable backfill material has to be characterized by a certain minimum gas permeability and a as low as possible hydraulic conductivity. On the one hand gas permeability is necessary to release gas overpressure and on the other hand a low hydraulic conductivity should prevent leaching of backfill materials and contamination of the environment

  5. DEM Analysis of Backfilled Walls Subjected to Active Translation Mode

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein Khosravi

    2017-12-01

    Full Text Available In this paper, the problem of a retaining wall under active translation mode is investigated numerically. To this end, a series of numerical models is conducted using the discrete element code, PFC2D. The backfill soil is simulated by an assembly of separate cohesionless circular particles. Backfill soil was prepared by pouring soil particles from a specific height under gravity force and giving them enough time for appropriate settlement. Different heights of retaining walls are simulated and the lateral earth pressure on the wall is observed under both at-rest and active conditions. Numerical results compared with predictions from some analytical methods and measurements from physical models. The active state of earth pressure is defined as the earth pressure distribution corresponding to the values of wall displacement where the failure zone in the backfill is fully developed. The numerical results showed that the fully active state of earth pressure occurred at a wall displacement corresponding to the strains required for reaching the critical state in biaxial compressive tests.

  6. Effect of Initial Backfill Temperature on the Deformation Behavior of Early Age Cemented Paste Backfill That Contains Sodium Silicate

    Directory of Open Access Journals (Sweden)

    Aixiang Wu

    2016-01-01

    Full Text Available Enhancing the knowledge on the deformation behavior of cemented paste backfill (CPB in terms of stress-strain relations and modulus of elasticity is significant for economic and safety reasons. In this paper, the effect of the initial backfill temperature on the CPB’s stress-strain behavior and modulus of elasticity is investigated. Results show that the stress-strain relationship and the modulus of elasticity behavior of CPB are significantly affected by the curing time and initial temperature of CPB. Additionally, the relationship between the modulus of elasticity and unconfined compressive strength (UCS and the degree of hydration was evaluated and discussed. The increase of UCS and hydration degree leads to an increase in the modulus of elasticity, which is not significantly affected by the initial temperature.

  7. Relative Density of Backfilled Soil Material around Monopiles for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Sørensen, Søren Peder Hyldal; Ibsen, Lars Bo; Frigaard, Peter

    2012-01-01

    The relative density of backfilled soil material around offshore monopiles is assessed through experimental testing in the Large Wave Channel (GWK) of the Coastal Research Centre (FZK) in Hannover. The relative density of the backfill material was found to vary between 65 and 80 %. The dependency...... of the relative density of backfill on the maximum pile bending moment is assessed through three-dimensional numerical modeling of a monopile foundation located at the offshore wind farm at Horns Reef, Denmark....

  8. Investigations on backfilling and sealing of chambers and shafts in a final salt repository

    International Nuclear Information System (INIS)

    Glaess, F.; Kappei, G.; Schmidt, M.W.; Schwieger, K.; Starke, C.; Taubert, E.; Wallmueller, R.; Walter, F.; Tischle, N.R.; Haensel, W.; Meyer, T.

    1991-03-01

    Soil mechanical laboratory investigations as well as geotechnical in situ measurements were carried out. The laboratory tests provided important information on the material behaviour of selected backfill and sealing materials. Initial conclusions on the long-term behaviour of backfill and seals as well as on their interaction with the rock were gained with the results of in situ measurements in backfilled chambers and seals and in the surrounding rock of the Asse salt mine. (orig./DG) [de

  9. Assessment of backfill design for a KBS-3V repository: the BACLO program

    International Nuclear Information System (INIS)

    Jonsson, E.; Gunnarsson, D.; Hansen, J.; Keto, P.; Dixon, D.A.; Boergesson, L.

    2010-01-01

    Document available in extended abstract form only. Posiva and SKB initiated a joint programme BACLO (Backfilling and Closure of the Deep repository) in 2003 with the aim to develop methods and clay-based materials for backfilling the deposition tunnels of a repository utilizing the KBS-3V deposition concept. This paper summarises the work done in the third and final phase of the BACLO programme (2006-2008). The main objectives of this work were to examine backfill materials, deposition concepts and their importance to the clay-based block and pellet backfilling concept. Baclo Phase III was primarily intended to address the following four items: 1. evaluate options for design of block and pellet/granule materials for use in backfilling and in so doing provide a basis for selecting backfill materials; 2. provide a basis for recommending reference design(s) for backfilling through evaluation of materials, environmental processes and technical constraints likely to be encountered in a repository; 3. analyze how the potentially critical processes taking place during the installation and saturation phase affect the performance of the backfill and consequently the design basis for the backfill; and 4. evaluate how water will move through backfilled volumes and generally identify under what conditions water management will become an operational issue; and identify needs for further investigations and technical development. To address these objectives, studies were undertaken to examine how the various processes active during backfill installation and saturation as well as technical constraints affect its design basis. The work focused on the performance and technical feasibility of a block backfill concept, which calls for filling the majority of the tunnel volume with pre-compacted, clay-based backfill blocks and the remaining volume with bentonite pellets. Several backfill composition alternatives were chosen for study and they consisted of clay materials with differing

  10. Radon emanation from backfilled mill tailings in underground uranium mine.

    Science.gov (United States)

    Sahu, Patitapaban; Mishra, Devi Prasad; Panigrahi, Durga Charan; Jha, Vivekananda; Patnaik, R Lokeswara; Sethy, Narendra Kumar

    2014-04-01

    Coarser mill tailings used as backfill to stabilize the stoped out areas in underground uranium mines is a potential source of radon contamination. This paper presents the quantitative assessment of radon emanation from the backfilled tailings in Jaduguda mine, India using a cylindrical accumulator. Some of the important parameters such as (226)Ra activity concentration, bulk density, bulk porosity, moisture content and radon emanation factor of the tailings affecting radon emanation were determined in the laboratory. The study revealed that the radon emanation rate of the tailings varied in the range of 0.12-7.03 Bq m(-2) s(-1) with geometric mean of 1.01 Bq m(-2) s(-1) and geometric standard deviation of 3.39. An increase in radon emanation rate was noticed up to a moisture saturation of 0.09 in the tailings, after which the emanation rate gradually started declining with saturation due to low diffusion coefficient of radon in the saturated tailings. Radon emanation factor of the tailings varied in the range of 0.08-0.23 with the mean value of 0.21. The emanation factor of the tailings with moisture saturation level over 0.09 was found to be about three times higher than that of the absolutely dry tailings. The empirical relationship obtained between (222)Rn emanation rate and (226)Ra activity concentration of the tailings indicated a significant positive linear correlation (r = 0.95, p < 0.001). This relationship may be useful for quick prediction of radon emanation rate from the backfill material of similar nature. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Radial diffusion of radiocaesium and radioiodide through cementitious backfill

    Science.gov (United States)

    Felipe-Sotelo, M.; Hinchliff, J.; Drury, D.; Evans, N. D. M.; Williams, S.; Read, D.

    The function of the backfill material in a geological disposal facility (GDF) is to chemically condition the environment of the near field and thereby chemically retard the transport of the radionuclides present in the waste. This function of the backfill material is usually referred to as chemical containment. Diffusion experiments are being carried out over periods up to four years to assess the diffusion of Cs, Ni, Eu, Th, U and I (as I-) through Nirex Reference Vault Backfill (NRVB). The method uses cylinders of NRVB (40 mm diameter, 40-45 mm height) which can be doped via a central well with the radionuclides of interest. Diffusion occurs radially into a surrounding solution already pre-equilibrated with the cement. This paper shows the results obtained during the first two years for experiments undertaken using 137Cs and 125I- tracers with and without carrier. Comparison is made to tritiated water under identical experimental conditions. Breakthrough of Cs and I- occurred within the first week of the experiments, reaching steady state in the surrounding solution after 20-50 days. The maximum concentrations expected from the original inventories based on a simple dilution calculation have not been reached, indicating that retention in the matrix has occurred; ranging from 10% to 40% for Cs, and up to 50% for I-. Corresponding experiments using a solution containing cellulose degradation products (CDP) showed an increased diffusion for both Cs and I. Migration profiles have been obtained and the relative retention of each radionuclide has been confirmed using digital autoradiography. The results indicate that, for both isotopes, migration occurs through the cement matrix rather than through microfissures. However, whereas Cs is homogeneously distributed within the blocks, there is evidence of zones of preferential I- accumulation even where concentrations in solution have reached steady state. Transport modelling using GoldSim has replicated experimental

  12. Effects of grouting, shotcreting and concrete leachates on backfill geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Luna, Miguel; Arcos, David; Duro, Lara [Enviros Consulting, Valldoreix, Barc elona (Spain)

    2007-11-15

    The use of concrete to seal open fractures (grouting) and to impermeabilise the deposition tunnels (shotcreting) has been envisaged in the construction of a high level nuclear waste (HLNW) repository according to SKB designs. Nevertheless, the geochemical effect of using concrete in the repository is not fully understood. Concrete degradation due to the interaction with groundwater can affect the performance of other repository barriers, such as the backfill material used for sealing the deposition tunnels. One of the main effects of concrete degradation is the generation of alkaline plumes. For this reason, SKB is currently planning to use a type of concrete whose degradation result in lower pH values than those developed with Ordinary Portland Cement (OPC). In order to assess the long-term geochemical effect of including low-pH concrete elements in a HLNW repository, we performed a 2D reactive-transport model of a backfilled deposition tunnel that intersects a hydraulic conductive fracture which has been partially grouted. An additional case has been modelled where part of the deposition tunnel walls were covered with a shotcrete layer. The modelling results predict the development of a high-alkalinity plume, larger in the case of considering a grouted fracture, accompanied by the precipitation of CSH-phases in the fracture. However, the effect on the backfill material is only significant if concrete is in contact with the backfill (shotcrete case). In order to conduct these models, and considering that at the beginning of the present work there was not a specific composition for such a low-pH concrete, its composition has been assumed in order to meet the expected geochemical evolution of concrete degradation according to SKB expectations. This is a pH of pore water of around 11 and the degradation of CSH phases resulting in a source for Ca and Si into the system. For this reason, jennite and tobermorite have been selected, although it is known that jennite is

  13. Effects of grouting, shotcreting and concrete leachates on backfill geochemistry

    International Nuclear Information System (INIS)

    Luna, Miguel; Arcos, David; Duro, Lara

    2007-11-01

    The use of concrete to seal open fractures (grouting) and to impermeabilise the deposition tunnels (shotcreting) has been envisaged in the construction of a high level nuclear waste (HLNW) repository according to SKB designs. Nevertheless, the geochemical effect of using concrete in the repository is not fully understood. Concrete degradation due to the interaction with groundwater can affect the performance of other repository barriers, such as the backfill material used for sealing the deposition tunnels. One of the main effects of concrete degradation is the generation of alkaline plumes. For this reason, SKB is currently planning to use a type of concrete whose degradation result in lower pH values than those developed with Ordinary Portland Cement (OPC). In order to assess the long-term geochemical effect of including low-pH concrete elements in a HLNW repository, we performed a 2D reactive-transport model of a backfilled deposition tunnel that intersects a hydraulic conductive fracture which has been partially grouted. An additional case has been modelled where part of the deposition tunnel walls were covered with a shotcrete layer. The modelling results predict the development of a high-alkalinity plume, larger in the case of considering a grouted fracture, accompanied by the precipitation of CSH-phases in the fracture. However, the effect on the backfill material is only significant if concrete is in contact with the backfill (shotcrete case). In order to conduct these models, and considering that at the beginning of the present work there was not a specific composition for such a low-pH concrete, its composition has been assumed in order to meet the expected geochemical evolution of concrete degradation according to SKB expectations. This is a pH of pore water of around 11 and the degradation of CSH phases resulting in a source for Ca and Si into the system. For this reason, jennite and tobermorite have been selected, although it is known that jennite is

  14. Flowable Backfill Materials from Bottom Ash for Underground Pipeline

    Directory of Open Access Journals (Sweden)

    Kyung-Joong Lee

    2014-04-01

    Full Text Available The purpose of this study was to investigate the relationship between strength and strain in manufacturing controlled low strength materials to recycle incineration bottom ash. Laboratory tests for controlled low strength materials with bottom ash and recycled in-situ soil have been carried out. The optimum mixing ratios were 25%–45% of in-situ soil, 30% of bottom ash, 10%–20% of fly ash, 0%–3% of crumb rubber, 3% of cement, and 22% of water. Each mixture satisfied the standard specifications: a minimum 20 cm of flowability and 127 kPa of unconfined compressive strength. The average secant modulus (E50 was (0.07–0.08 qu. The ranges of the internal friction angle and cohesion for mixtures were 36.5°–46.6° and 49.1–180 kPa, respectively. The pH of all of the mixtures was over 12, which is strongly alkaline. Small-scale chamber tests for controlled low strength materials with bottom ash and recycled in-situ soil have been carried out. Vertical deflection of 0.88–2.41 mm and horizontal deflection of 0.83–3.72 mm were measured during backfilling. The vertical and horizontal deflections of controlled low strength materials were smaller than that of sand backfill.

  15. Retention Capability of Local Backfill Materials 1-Simulated Disposal Environment

    International Nuclear Information System (INIS)

    Ghattas, N.K.; Eskander, S.B.; El-Adham, K.A.; Mahmoud, N.S.

    2001-01-01

    In Egypt, a shallow ground disposal facility was the chosen option for the disposal of low and and intermediate radioactive wastes. The impact of the waste disposal facility on the environment depends on the nature of the barriers, which intend to limit and control contaminant migration. Owing to their physical, chemical and mechanical characteristics. Local soil materials were studied to illustrate the role of the back fill as part of an optimized safety multi-barrier system, which can provide the required level of protection of the environment and meet economic and regulatory requirements. A theoretical model was proposed to calculate the transport phenomena through the backfill materials. The credibility and validity of the proposed model was checked by the experimental results obtained from a three-arms arrangement system. The obtained data for the distribution coefficient (K d ) and the apparent diffusion coefficient (D a ) were in good agreement with those previously obtained in the literatures. Taking in consideration the prevailing initial conditions, the data calculated by the theoretical model applied show a reasonable agreement with the results obtained from experimental work. Prediction of radioactive cesium migration through the backfill materials using the proposed model was performed as a function of distance. The results obtained show that after 100 years, a fraction not exceeding 1E-9 of the original activity could be detected at 1m distance away from the waste material

  16. The feasibility of Backfilling a Repository of Spent Fuel: An Assessment of Recent Developments by SKB

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, David (TerraSalus Limited, Rutland (United Kingdom))

    2010-12-15

    In the Review Statement and Evaluation of SKB's RDandD programme 2007 (SKI Report 2008:48E), the former Swedish Nuclear Power Inspectorate (SKI) commented that considerable work remained to be done for knowledge of both practical management issues on backfilling and analysis of long-term backfill evolution to reach the same level as for the canister and the buffer. SKI considered that the backfill material had not been thoroughly reported in the RDandD programme. More concrete plans were also needed relating to large-scale demonstration experiments to investigate the performance of the backfill in as realistic conditions as possible. In the spring of 2009, noting that SKB had changed its concept for backfilling several times over the last few years, and after having visited SKB's most recent backfilling trials at Aespoe, both SSM and SSM's expert group BRITE had strong concerns regarding SKB's programme for backfilling the repository tunnels. Although the BRITE expert group has been keeping a watching brief over SKB's development work on backfilling, SSM has not undertaken a systematic assessment of SKB's work in this area since the SR-Can Safety Report was reviewed in 2006. Dr David Bennett, a member and secretary of the BRITE expert group, was asked to do such an assessment. This report describes the assessment results

  17. Evaluation of engineering aspects of backfill placement for high level nuclear waste (HLW) deep geologic repositories

    International Nuclear Information System (INIS)

    Roberds, W.; Kleppe, J.; Gonano, L.

    1984-04-01

    This report includes the identification and subjective evaluation of alternative schemes for backfilling around waste packages and within emplacement rooms. The aspects of backfilling specifically considered in this study include construction and testing; costs have not been considered. However, because construction and testing are simply implementation and verification of design, a design basis for backfill is required. A generic basis has been developed for this study by first identifying qualitative performance objectives for backfill and then weighting each with respect to its potential influence on achieving the repository system performance objectives. Alternative backfill materials and additives have been identified and evaluated with respect to the perceived extent to which each combination can be expected to achieve the backfill design basis. Several distinctly different combinations of materials and additives which are perceived to have the highest potential for achieving the backfill design basis have been selected for further study. These combinations include zeolite/clinoptilolite, bentonite, muck, and muck mixed with bentonite. Feasible alternative construction and testing procedures for each selected combination have been discussed. Recommendations have been made regarding appropriate backfill schemes for hard rock (i.e., basalt at Hanford, Washington, tuff at Nevada Test Site, and generic granite) and salt (i.e., domal salt on the Gulf Coast and generic bedded salt). 27 references, 8 figures, 31 tables

  18. The feasibility of Backfilling a Repository of Spent Fuel: An Assessment of Recent Developments by SKB

    International Nuclear Information System (INIS)

    Bennett, David

    2010-12-01

    In the Review Statement and Evaluation of SKB's RDandD programme 2007 (SKI Report 2008:48E), the former Swedish Nuclear Power Inspectorate (SKI) commented that considerable work remained to be done for knowledge of both practical management issues on backfilling and analysis of long-term backfill evolution to reach the same level as for the canister and the buffer. SKI considered that the backfill material had not been thoroughly reported in the RDandD programme. More concrete plans were also needed relating to large-scale demonstration experiments to investigate the performance of the backfill in as realistic conditions as possible. In the spring of 2009, noting that SKB had changed its concept for backfilling several times over the last few years, and after having visited SKB's most recent backfilling trials at Aespoe, both SSM and SSM's expert group BRITE had strong concerns regarding SKB's programme for backfilling the repository tunnels. Although the BRITE expert group has been keeping a watching brief over SKB's development work on backfilling, SSM has not undertaken a systematic assessment of SKB's work in this area since the SR-Can Safety Report was reviewed in 2006. Dr David Bennett, a member and secretary of the BRITE expert group, was asked to do such an assessment. This report describes the assessment results

  19. The backfilling and sealing of radioactive waste repositories. V. 2. Figure - Tables - Appendices

    International Nuclear Information System (INIS)

    1984-01-01

    The two volumes of this report present a review study about backfilling and sealing of radioactive waste repositories in granites, argillaceous and salt formations. Volume 2 contains all the figures, table and appendices A detailed account of candidate backfill materials is given in a standardized format

  20. BACCHUS 2: an in situ backfill hydration experiment for model validation

    International Nuclear Information System (INIS)

    Volckaert, G.; Bernier, F.; Alonso, E.; Gens, A.

    1995-01-01

    The BACCHUS 2 experiment is an in situ backfill hydration test performed in the HADES underground research facility situated in the plastic Boom clay layer at 220 m depth. The experiment aims at the optimization and demonstration of an installation procedure for a clay based backfill material. The instrumentation has been optimized in such a way that the results of the experiments can be used for the validation of hydro-mechanical codes such a NOSAT developed at the University of Catalunya Spain (UPC). The experimental set-up consists in a bottom flange and a central filter around which the backfill material was applied. The backfill material consist of a mixture of high density clay pellets and clay powder. The experimental set-up and its instrumentation are described in detail. The results of the hydro-mechanical characterization of the backfill material is summarized. (authors). 8 refs., 16 figs., 1 tab

  1. bentonite-sand mixture as new backfill/buffer material

    International Nuclear Information System (INIS)

    Cui Suli; Liu Jisheng; Zhang Huyuan; Liang Jian

    2008-01-01

    The mixture of bentonite and quartz sand is suggested as a new backfill/buffer material for geological disposal of HLW. To improve the further design of underground laboratory and in-situ industrial construction test, the optimization of sand addition to bentonite is focused at present research stage. Based on summarizing the research results abroad, laboratory tests were conducted on the mixture of GMZ001 bentonite and quartz sand, such as compaction test and swelling tests etc. Test data shows that GMZ bentonite-sand mixture exhibits a favorite compaction with a 30% sand addition, a highest swelling pressure with a 20% sand addition, and a decreasing plasticity with increases in sand addition and pore liquid concentration. (authors)

  2. Evaluation of backfill materials for a shallow-depth repository

    International Nuclear Information System (INIS)

    Buckley, L.P.; Arbique, G.M.; Tosello, N.B.; Woods, B.L.

    1986-11-01

    The focus of laboratory research effort on the disposal of low- and intermediate-level radioactive waste is to determine what conditions will dominate and which engineered barriers will be most effective for the retention of radionuclides. Initial studies have concentrated on the evaluation of a flooded repository and the assessment of backfill materials suitable for the adsorption of radioactivity, yet permeable enough to allow excess water to pass through the repository and into the underlying water table. Both physical and adsorption studies have been performed. Based on these preliminary experiments, it is felt that a mixture of 10 wt% clay and the remainder sand would satisfy the above criteria. Since both are available within the Ottawa Valley, they also have the added advantage of being more cost effective to use than imported materials

  3. Radionuclide sorption and migration studies of getters for backfill barriers

    International Nuclear Information System (INIS)

    Nowak, E.J.

    1980-07-01

    Bentonite and hectorite clay minerals were chosen for study and development as potential backfill materials for testing in the proposed Waste Isolation Pilot Plant (WIPP), a radioactive waste repository and test facility in bedded salt. This choice of materials was based on initial screening results which are presented and on the predicted physical properties of these materials. These properties were verified experimentally in concentrated brines specific to the WIPP site. Distribution coefficients, K/sub d/, were calculated from batch sorption measurements on bentonite and hectorite in the nearly saturated brines A and B. The resulting K/sub d/ values were in the range of (1 to 5) x 10 3 ml/g for europium; (2 to 40) x 10 3 ml/g for plutonium(IV); and (4 to 16) x 10 3 ml/g for americium(III). A silica- and calcite-containing sand mixed with bentonite and hectorite acted as a sorber of americium(III) but was merely an inert diluent for plutonium(IV). Pertechnetate anions (TcO 4 - ) sorbed on activated charcoal with K/sub d/ values in the range of (0.2 to 0.4) x 10 3 ml/g. Pertechnetate, cesium, and strontium ions in brine were not sorbed appreciably by bentonite or hectorite. Although experimental evidence is given for a possible role of solubility in the sorption of europium on getters, other data presented here and evidence from the literature are inconsistent with a simple single reaction sorption mechanism. It is concluded that a backfill containing bentonite on hectorite and activated charcoal is potentially an effective barrier to the migration of Eu(III), Pu(IV), and Am(III) cations and, with further development, to the migration of TcO 4 - anions as well

  4. Research on backfilling and sealing of Rooms and Galleries in a repository in salt

    International Nuclear Information System (INIS)

    Glaess, F.; Kappei, G.; Schmidt, M.W.; Schwieger, K; Starke, C.; Taubert, E.; Wallmueller, R.; Walter, F.

    1992-01-01

    The multibarrier concept for the final disposal of radioactive wastes comprises backfilling and sealing of the mine in order to guarantee a safe enclosure of the waste. To provide for these properties, soil mechanical laboratory as well as geotechnical in situ measurements were carried out at the Asse mine. The soil mechanical investigations were performed on salt grit and precompacted backfilling material of different grain-size distribution and clay admixtures. They showed a significant dependence upon permeability and compression velocity of the type and quantity of clay used. A favourable grain-size distribution of the salt results in an acceleration of its compaction ability. Besides the investigation on a laboratory scale, first conclusions were obtained on the long-term in situ behaviour of backfilled chambers and seals and their corresponding geomechanical interaction with the surrounding rock. The geotechnical in situ stress and deformation measurements in an approximately 27.000 m 3 large chamber have so far shown no supporting effect against the surrounding rock four years after backfilling. A compaction of up to 3% of the backfill was registered. In situ measurements as well as laboratory tests on drilling cores from 60 years old backfill showed porosities of approximately 7% and a compaction effect of the backfill from the wall, decreasing towards the centre of the chamber due to the converging rock. 108 figs., 8 refs., 24 tabs

  5. A multiphysics-viscoplastic cap model for simulating blast response of cemented tailings backfill

    Directory of Open Access Journals (Sweden)

    Gongda Lu

    2017-06-01

    Full Text Available Although a large number of previous researches have significantly contributed to the understanding of the quasi-static mechanical behavior of cemented tailings backfill, an evolutive porous medium used in underground mine cavities, very few efforts have been made to improve the knowledge on its response under sudden dynamic loading during the curing process. In fact, there is a great need for such information given that cemented backfill structures are often subjected to blast loadings due to mine exploitations. In this study, a coupled thermo-hydro-mechanical-chemical (THMC-viscoplastic cap model is developed to describe the behavior of cementing mine backfill material under blast loading. A THMC model for cemented backfill is adopted to evaluate its behavior and evolution of its properties in curing processes with coupled thermal, hydraulic, mechanical and chemical factors. Then, the model is coupled to a Perzyna type of viscoplastic model with a modified smooth surface cap envelope and a variable bulk modulus, in order to reasonably capture the nonlinear and rate-dependent behaviors of the cemented tailings backfill under blast loading. All of the parameters required for the variable-modulus viscoplastic cap model were obtained by applying the THMC model to reproducing evolution of cemented paste backfill (CPB properties in the curing process. Thus, the behavior of hydrating cemented backfill under high-rate impacts can be evaluated under any curing time of concern. The validation results of the proposed model indicate a good agreement between the experimental and the simulated results. The authors believe that the proposed model will contribute to a better understanding of the performance of hydrating cemented backfill under blasting, and also to practical risk management of backfill structures associated with such a dynamic condition.

  6. Basic experimental study on the backfilling material under saline seawater condition

    International Nuclear Information System (INIS)

    Kikuchi, Hirohito; Tanai, Kenji; Sugita, Yutaka

    2003-11-01

    In geological disposal of high-level radioactive waste, closure of repository is the technique of filling clearance using the backfilling material to preserve barrier performance of the engineered barrier system. The required performances of the backfilling material are clearance filling, low permeability and swelling pressure and stiffness. The expecting behaviors of the backfilling material are very complex which are decrease of section area of the tunnel due to creep displacement, decrease of performance of bentonite due to alteration of the concrete lining and so on. And ideal assessment of the clearance filling performance in the backfilled tunnel will be performed considering the coupled behaviors described above. However, there is not enough data to explain the expecting behaviors, and mechanisms of the coupled behaviors are not clarified yet. Therefore, the clearance filling performance of backfilling material was selected first. In this study, the clearance filling performance was tested using the clearance considering only decrease of the volume of the concrete lining due to alteration of the concrete. Basic examination of the backfilling material was performed, which focused on the feasibility of the backfilling material described in the H12 report and the adequate bentonite/sand mixture to obtain conservative filling clearance performance. Results of the examination showed, under test conditions that 30% of the volume of concrete lining decreases due to alteration and such volume become clearance between the backfilling material and concrete lining, in distilled water condition, the specification (bentonite/sand mixture) of the backfilling material described in H12 report almost filled the clearance. However, in saline seawater, 50% and more bentonite was required to fill the clearance. Since this examination fixed the clearance, water stopping performance will be examined in next phase. Through the saline seawater examination, the basic clearance

  7. Physical response of backfill materials to mineralogical changes in a basalt environment

    International Nuclear Information System (INIS)

    Couture, R.A.; Seitz, M.G.

    1983-01-01

    Backfill materials surrounding waste canisters in a high-level nuclear waste repository are capable of ensuring very slow flow of groundwater past the canisters, and thereby increase the safety of the repository. However, in the design of a repository it will be necessary to allow for possible changes in the backfill. In this experimental program, changes in permeability, swelling behavior, and plastic behavior of the backfill at the temperatures, pressures, and radiation levels expected in a repository are investigated. The emphasis is on investigation of relevant phenomena and evaluation of experimental procedures for use in licensing procedures. The permeability of a slightly compacted sand-clay mixture containing 25% bentonite, with a dry bulk density of 1.59 g/cm 3 , was determined to be 0.9 x 10 -18 m 2 in liquid water at 25 and 200 0 C, respectively. This is sufficiently low to demonstrate the potential effectiveness of proposed materials. In practice, fractures in the host rock may form short circuits around the backfill, so an even lower flow rate is probable. However, alteration by any of several mechanisms is expected to change the properties of the backfill. Crushed basalt plus bentonite is a leading candidate backfill for a basalt repository. Experiments show that basalt reacts with groundwater vapor or with liquid groundwater producing smectites, zeolites, silica, and other products that may be either beneficial or detrimental to the long-term performance of the backfill. Concentration of groundwater salts in the backfill by evaporation would cause immediate, but possibly reversible, reduction of the swelling abaility of bentonite. Moreover, under some circumstances, gamma radiolysis of moist air in the backfill could produce up to 0.5 mole of nitric acid or ammonia per liter of pore space. 27 references, 7 figures, 4 tables

  8. The backfilling and sealing of radioactive waste repositories. V. 1. Text - Reference - List of symbols

    International Nuclear Information System (INIS)

    1984-01-01

    The report is in two volumes: Volume 1 contains the main text, the references and a list of symbols, and Volume 2, all the figues, tables and appendices. In Volume 1, backfilling and sealing is considered in relation to the geological, physical and chemical environments. There follows a detailed evaluation of the role and performance of the backfilling and sealing system in terms of thermal, hydraulic, chemical buffering, radionuclide retention, mechanical properties and behaviour as well as longevity. The results of the listing, screening and classification of a comprehensive range of candidate backfill materials are summarized. The different candidate materials are examined

  9. Performance Comparison between Neutralization Tailings and Flotation Tailings Used for Backfill Mix and Mechanism Analysis

    OpenAIRE

    Han, Bin; Sun, Wei; Yu, Shaofeng; Liu, Chao; Yao, Song; Wu, Jianxun

    2016-01-01

    A comparison test of different tailings used for underground backfill was conducted, using neutralized tailings from BIOX and flotation tailings of Jinfeng Mine. Laboratory comparison test results show that, with neutralized tailings, when the cement dosage is at 19%, backfill UCS after 7 days, 14 days, and 28 days are 105%–163%, 80%–102%, and 33%–43%, respectively, which are higher than those of flotation tailings. When the cement dosage is at 12%, backfill UCS after 7 days, 14 days, and 28 ...

  10. Engineering solution for the backfilling and sealing of radioactive waste repositories

    International Nuclear Information System (INIS)

    Jorda, M.; Gouvenot, D.; Bonne, A.; Lees, T.P.; Schmidt, M.

    1990-01-01

    To ensure the safety of radioactive waste deep disposal, backfilling and sealing materials (engineered barriers) have to be used to fill residual voids. For granite medium, stress is put on emplacement techniques for cement- and clay-based materials, including in-situ validation. For clay medium, mined repository and deep boreholes drilled from the surface are considered. In the case of the first solution, the thermomechanical behaviour of a clay backfill is studied. In the same way, backfill made of excavated crushed salt is considered and thermomechanical properties evaluated by means of laboratory tests and in-situ experiments. Finally, basic works on quality assurance procedures and historic concretes behaviour are reported

  11. Mill tailings based composites as paste backfill in mines of U-bearing dolomitic limestone ore

    Directory of Open Access Journals (Sweden)

    Sandeep Panchal

    2018-04-01

    Full Text Available This paper elaborates on the development of paste backfill using mill tailings generated during the processing of a uranium ore deposit hosted in dolomitic limestone. The tailings have been characterized in terms of the physical, chemical and mineralogical properties. Time-dependent rheological behaviors and geotechnical properties of cemented paste backfill (CPB are also determined. The studies show that the mill tailing has the potential to form paste and the CPB has adequate strength to provide support to mine pillars, roofs, and walls. Keywords: Mining engineering, Uranium ore deposit, Tailings, Cemented paste backfill (CPB, Rheology, Compressive strength

  12. Deep repository - engineered barrier systems. Assessment of backfill materials and methods for deposition tunnels

    International Nuclear Information System (INIS)

    Gunnarsson, David; Moren, Lena; Sellin, Patrik; Keto, Paula

    2006-09-01

    The main objectives of this report are to: 1) present density criteria considering deposition tunnels for the investigated backfill materials, 2) evaluate what densities can be achieved with the suggested backfill methods, 3) compare the density criteria to achievable densities, 4) based on this comparison evaluate the safety margin for the combinations of backfill materials and methods and, 5) make recommendations for further investigations and development work. The backfilling methods considered in this report are compaction of backfill material in situ in the tunnel and placement of pre-compacted blocks and pellets. The materials investigated in the second phase of the SKB-Posiva backfilling project can be divided into three main categories: 1. Bentonite clays: two high-grade Na-bentonites from Wyoming (MX-80 and SPV200), one low-grade bentonite from Kutch (India Asha 230), and one high and one low-grade Ca-bentonite from Milos (Deponite CA-N and Milos backfill). The high-grade bentonites are used in different bentonite-ballast mixtures. 2. Smectite-rich mixed-layer clays: one from Dnesice-Plzensko Jih (DPJ) located in the Czech Republic and one from Northern Germany (Friedland clay). Mixtures of bentonite and ballast: Mixtures consisting of high-grade bentonite (0, 40 and 50 w-%) and crushed rock with different type of grain size distribution or sand. The relationships between dry densities and hydraulic conductivity, swelling pressure and compressibility in saturated state for these materials were investigated. Most of the tests were performed with a groundwater salinity of 3.5%. This salinity is comparable to sea water and can be expected to be at the high end of salinities occurring during the assessment period. The purpose of the investigations was to determine the dry densities required to meet the function indicator criteria. These densities are referred to as the density criteria. However throughout the assessment period a loss of material and thus

  13. Determination of the in situ modulus of the rockmass by the use of backfill measurements

    CSIR Research Space (South Africa)

    Gurtunca, RG

    1991-03-01

    Full Text Available In situ measurements and numerical modelling based on elastic theory showed that backfill stresses are considerably higher than originally thought. This has led to a change in understanding of rockmass behaviour. After describing previous work...

  14. Recycled Asphalt Pavement and Crushed Concrete Backfill: State-of-the-Art Review and Material Characterization

    Science.gov (United States)

    2001-10-01

    This report describes research results from the first year of a three-year study focused on the use of recycled asphalt pavement (RAP) and crushed concrete (CC) as backfill for mechanically stabilized earth (MSE) walls.

  15. Numerical simulation of wave-induced scour and backfilling processes beneath submarine pipelines

    DEFF Research Database (Denmark)

    Fuhrman, David R.; Baykal, Cüneyt; Sumer, B. Mutlu

    2014-01-01

    A fully-coupled hydrodynamic/morphodynamic numerical model is presented and utilized for the simulation of wave-induced scour and backfilling processes beneath submarine pipelines. The model is based on solutions to Reynolds-averaged Navier–Stokes equations, coupled with k−ω turbulence closure......≤30 demonstrate reasonable match with previous experiments, both in terms of the equilibrium scour depth as well as the scour time scale. Wave-induced backfilling processes are additionally studied by subjecting initial conditions taken from scour simulations with larger KC to new wave climates...... characterized by lower KC values. The simulations considered demonstrate the ability of the model to predict backfilling toward expected equilibrium scour depths based on the new wave climate, in line with experimental expectations. The simulated backfilling process is characterized by two stages: (1...

  16. Deep repository - engineered barrier systems. Assessment of backfill materials and methods for deposition tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Gunnarsson, David; Moren, Lena; Sellin, Patrik [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Keto, Paula [Saanio and Riekkola Oy, Helsinki (Finland)

    2006-09-15

    The main objectives of this report are to: 1) present density criteria considering deposition tunnels for the investigated backfill materials, 2) evaluate what densities can be achieved with the suggested backfill methods, 3) compare the density criteria to achievable densities, 4) based on this comparison evaluate the safety margin for the combinations of backfill materials and methods and, 5) make recommendations for further investigations and development work. The backfilling methods considered in this report are compaction of backfill material in situ in the tunnel and placement of pre-compacted blocks and pellets. The materials investigated in the second phase of the SKB-Posiva backfilling project can be divided into three main categories: 1. Bentonite clays: two high-grade Na-bentonites from Wyoming (MX-80 and SPV200), one low-grade bentonite from Kutch (India Asha 230), and one high and one low-grade Ca-bentonite from Milos (Deponite CA-N and Milos backfill). The high-grade bentonites are used in different bentonite-ballast mixtures. 2. Smectite-rich mixed-layer clays: one from Dnesice-Plzensko Jih (DPJ) located in the Czech Republic and one from Northern Germany (Friedland clay). Mixtures of bentonite and ballast: Mixtures consisting of high-grade bentonite (0, 40 and 50 w-%) and crushed rock with different type of grain size distribution or sand. The relationships between dry densities and hydraulic conductivity, swelling pressure and compressibility in saturated state for these materials were investigated. Most of the tests were performed with a groundwater salinity of 3.5%. This salinity is comparable to sea water and can be expected to be at the high end of salinities occurring during the assessment period. The purpose of the investigations was to determine the dry densities required to meet the function indicator criteria. These densities are referred to as the density criteria. However throughout the assessment period a loss of material and thus

  17. Thermo-Hydraulic Modelling of Buffer and Backfill

    International Nuclear Information System (INIS)

    Pintado, X.; Rautioaho, E.

    2013-09-01

    The temporal evolution of saturation, liquid pressure and temperature in the components of the engineered barrier system was studied using numerical methods. A set of laboratory tests was conducted to calibrate the parameters employed in the models. The modelling consisted of thermal, hydraulic and thermo-hydraulic analysis in which the significant thermo-hydraulic processes, parameters and features were identified. CODE B RIGHT was used for the finite element modelling and supplementary calculations were conducted with analytical methods. The main objective in this report is to improve understanding of the thermo-hydraulic processes and material properties that affect buffer behaviour in the Olkiluoto repository and to determine the parametric requirements of models for the accurate prediction of this behaviour. The analyses consisted of evaluating the influence of initial canister temperature and gaps in the buffer, and the role played by fractures and the rock mass located between fractures in supplying water for buffer and backfill saturation. In the thermo-hydraulic analysis, the primary processes examined were the effects of buffer drying near the canister on temperature evolution and the manner in which heat flow affects the buffer saturation process. Uncertainties in parameters and variations in the boundary conditions, modelling geometry and thermo-hydraulic phenomena were assessed with a sensitivity analysis. The material parameters, constitutive models, and assumptions made were carefully selected for all the modelling cases. The reference parameters selected for the simulations were compared and evaluated against laboratory measurements. The modelling results highlight the importance of understanding groundwater flow through the rock mass and from fractures in the rock in order to achieve reliable predictions regarding buffer saturation, since saturation times could range from a few years to tens of thousands of years depending on the hydrogeological

  18. Thermal simulation of drift emplacement. Geotechnical and geophysical investigations in and around backfilled galleries

    International Nuclear Information System (INIS)

    Schneefub, J.U.; Gommlich, G.E.

    1988-01-01

    The concept for the direct disposal of spent fuel in rock salt foresees the emplacement of large waste canisters on the floor of a disposal gallery. Subsequent to emplacement the drift is backfilled with salt grit. In a demonstration test six cylindrical containments are to be emplaced within distances of 3 m from each other in two parallel galleries of 14 m 2 , separated by a pillar of 10 m thickness. They will be heated up by a power output of approx. 1 kW/m to 200 degree C surface temperature by electrical heaters. The thermal and mechanical response of the salt rock and the backfilling to the artificial heating is to be investigated as follows: (1) measurement of the temperature field at the contained surface, in the backfill and in the rock salt; (2) deformation measurements of the salt rock around the heated drifts; (3) measurements of tunnel convergence in heated and unheated sections; (4) compaction measurements of the backfilling in heated and unheated areas; (5) measurement of rock stresses in areas very close to the galleries; and (6) pressure measurements in the backfilling, between backfilling and rock, and between backfilling and containers. The rock burst monitoring system of the Asse salt mine will be expanded to this special field of the mine to detect seismic events due to thermomechanical effects. Another seismoacoustic system will be installed to observe the compaction of the backfilling. This system must be calibrated for the relation between the density and velocities of seismic waves. It is planned to monitor the density by gamma-gamma log measurements. The changes in overall density during the entire experiment will be observed by gravimeter measurements of high precision

  19. Use of Gap-fills in the Buffer and Backfill of an HLW Repository

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae Owan; Lee, Min Soo; Choi, Heui Joo [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    The buffer and backfill are significant barrier components of the repository. They play the roles of preventing the inflow of groundwater from the surrounding rock, retarding the release of radionuclides from the waste, supporting disposal container against external impacts, and discharging decay heat from the waste. When the buffer and backfill are installed for the HLW repository, there may be gaps between the container and buffer and between the backfill and the wall of disposal tunnels, respectively. These gaps occur because spaces are allowed for ease of the installation of the buffer and backfill in excavated deposition boreholes and disposal tunnels. If the gaps are left without any sealing as they are, however, the buffer and backfill can't accomplish their functions as the barrier components. This paper reviews the gap-fill concepts of the developed foreign countries, and then suggests a gap-fill concept which is applicable for the KRS. The gap-fill is suggested to employ bentonite- based materials with a type of pellet, granule, and pellet-granule mixture. The roller compression method and extrusion-cutting method are applicable for the fabrication of the bentonite pellets which can have the high density and the required amount for use to the buffer and backfill. For the installation of the gap-fill, the pouring and then pressing method and the shotcrete- blowing method are preferable for the gap of the deposition borehole and the gap of the disposal tunnel, respectively.

  20. Design, production and initial state of the backfill and plug in deposition tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Boerjesson, Lennart; Gunnarsson, David; Johannesson, Lars-Erik; Jonsson, Esther

    2010-12-15

    The report is included in a set of Production reports, presenting how the KBS-3 repository is designed, produced and inspected. The set of reports is included in the safety report for the KBS-3 repository and repository facility. The report provides input on the initial state of the backfill and plug in deposition tunnels for the assessment of the long-term safety, SR-Site. The initial state refers to the properties of the engineered barriers once they have been finally placed in the KBS-3 repository and will not be further handled within the repository facility. In addition, the report provides input to the operational safety report, SR-Operation, on how the backfill and plug shall be handled and installed. The report presents the design premises and reference designs of the backfill and plug in deposition tunnels and verifies their conformity to the design premises. It also describes the production of the backfill from excavation and delivery of backfill material to installation in the deposition tunnel, and gives an outline of the installation of the plug. Finally, the initial states of the backfill and plug and their conformity to the reference designs and design premises are presented

  1. Backfilling behavior of a mixed aggregate based on construction waste and ultrafine tailings.

    Science.gov (United States)

    Chen, Qiusong; Zhang, Qinli; Xiao, Chongchun; Chen, Xin

    2017-01-01

    To study the possibility of utilizing mixed construction waste and ultrafine tailings (CW&UT) as a backfilling aggregate that can be placed underground in a mine, physicochemical evaluation, proportioning strength tests, and pumpability experiments were conducted. It was revealed that mixed CW&UT can be used as a backfilling aggregate due to the complementarities of their physicochemical properties. In addition, as the results of the proportioning strength tests show, the compressive strength of a cemented CW&UT backfilling specimen cured for 28 days, with a mass fraction of 72-74%, a cement-sand ratio of 1:12, and a CW proportion of 30%, is higher than 1.0 MPa, which meets the safety requirements and economic consideration of backfilling technology in many underground metal mines, and can also be enhanced with an increase in the cement-sand ratio. The results of the pumpability experiments show that cemented backfilling slurry based on CW&UT can be transported to the stope underground with a common filling pump, with a 16.6 MPa maximum pressure, with the condition that the time of emergency shut-down is less than approximately 20 min. All in all, the research to utilize mixed CW&UT as a backfilling aggregate can not only provide a way to dispose of CW&UT but also will bring large economic benefits and can provide constructive guidance for environmental protection.

  2. Behavior of cement paste as backfill in waste disposal boreholes

    International Nuclear Information System (INIS)

    Ferreira, Eduardo G.A.; Isiki, Vera L.K.; Miyamoto, Hissae; Marumo, Julio T.; Vicente, Roberto

    2011-01-01

    The Radioactive Waste Management Laboratory (GRR) at the Nuclear and Energy Research Institute (IPEN) in Sao Paulo, Brazil, is developing the concept a repository for disposition of disused sealed radioactive sources in a deep borehole, aiming at providing a feasible and inexpensive alternative for final disposal. A relevant fraction of the Brazilian inventory of sources has long half-life which prevents them to be disposed of in shallow ground disposal facilities. In the concept of repository under study, Portland cement paste is intended to be used as a backfill between the steel casing and the geological formation around the borehole. Cement paste will function as structural, an additional barrier against the migration of radionuclides outside the repository, and as a blockage against the transport of water between the different strata of the geological setting. The durability of cementitious materials under the conditions prevailing at the depth of disposal is as yet unknown. The objective of this research is to investigate the behavior of the cement paste and to estimate its service life. In this paper we present the results of mechanical strength measurements and chemical and mineralogical analysis of samples to detect the changes caused by radiation, temperature and aggressive chemicals present in ground water. Techniques of analysis included Inductively Coupled Plasma Atomic Emission Spectroscopy, Ion Chromatography, X-Ray Diffraction, and Thermo-Gravimetric Analysis. (author)

  3. Dessicant materials screening for backfill in a salt repository

    International Nuclear Information System (INIS)

    Simpson, D.R.

    1980-10-01

    Maintaining an anhydrous environment around nuclear waste stored in a salt repository is a concern which can be alleviated by using a desiccant material for backfilling. Such a desiccant should desiccate a brine yet be non deliquescent, the hydrated product should have moderate thermal stability, and the desiccant should have a high capacity and be readily available. From a literature search MgO and CaO were identified for detailed study. These oxides, and an intimate mixture of the two obtained by calcining dolomite, were used in experiments to further determine their suitability. They proved to be excellent desiccants with a high water capacity. The hydrates of both have moderate thermal stability and a high water content. Both MgO and CaO react in an alkaline chloride brine forming oxychloride compounds with different waters of crystallization. Some of these compounds are the Sorel Cements. CaO hydrates to Ca(OH) 2 which carbonates with CO 2 in air to form CaCO 3 and release the hydrated water. Thus the intimate mixture of CaO and MgO from calcined dolomite may serve as a desiccant and remove CO 2 from the repository atmosphere

  4. Dessicant materials screening for backfill in a salt repository

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, D.R.

    1980-10-01

    Maintaining an anhydrous environment around nuclear waste stored in a salt repository is a concern which can be alleviated by using a desiccant material for backfilling. Such a desiccant should desiccate a brine yet be non deliquescent, the hydrated product should have moderate thermal stability, and the desiccant should have a high capacity and be readily available. From a literature search MgO and CaO were identified for detailed study. These oxides, and an intimate mixture of the two obtained by calcining dolomite, were used in experiments to further determine their suitability. They proved to be excellent desiccants with a high water capacity. The hydrates of both have moderate thermal stability and a high water content. Both MgO and CaO react in an alkaline chloride brine forming oxychloride compounds with different waters of crystallization. Some of these compounds are the Sorel Cements. CaO hydrates to Ca(OH)/sub 2/ which carbonates with CO/sub 2/ in air to form CaCO/sub 3/ and release the hydrated water. Thus the intimate mixture of CaO and MgO from calcined dolomite may serve as a desiccant and remove CO/sub 2/ from the repository atmosphere.

  5. Mechanical interaction buffer/backfill. Finite element calculations of the upward swelling of the buffer against both dry and saturated backfill

    Energy Technology Data Exchange (ETDEWEB)

    Boergesson, Lennart (Clay Technology AB, Lund (Sweden)); Hernelind, Jan (5T-Engineering AB, Vaesteraas (Sweden))

    2009-10-15

    The mechanical interaction between the buffer material in the deposition hole and the backfill material in the deposition tunnel is an important process in the safety assessment since the primary function of the backfill is to keep the buffer in place and not allow it to expand too much and thereby loose too much of its density and barrier properties. In order to study the upwards swelling of the buffer and the subsequent density reduction a number of finite element calculations have been performed. The calculations have been done with the FE-program Abaqus with 3D-models of a deposition hole and the deposition tunnel. In order to refine the modelling only the two extreme cases of completely un-wetted (dry) and completely water saturated (wet) backfill have been modelled. For the wet case the influence of different factors has been studied while only one calculation of the dry case has been done. The calculated upwards swelling of the buffer varied between 2 and 15 cm for the different wet cases while it was about 10 cm for the dry case. In the wet reference case the E-modulus of the block and pellets fillings was 50 MPa and 3.24 MPa respectively, the friction angle between the buffer and the rock and canister was 8.7 deg and there were no swelling pressure from the backfill. There is a strong influence of the friction angle on both the upwards swelling and the canister heave. The friction is important for preventing especially canister displacements. The unrealistic case of no friction yielded strong unacceptable influence on the buffer with an upwards swelling of 15 cm and a strong heave of 5 cm of the canister. The influence of the backfill stiffness is as expected strong. Both buffer swelling and canister heave are twice as large at the E-modulus E = 25 MPa than at the E-modulus E = 100 MPa. The influence of the stiffness of the pellets filling is not strong since there are no pellets on the floor in the model used. The influence of the swelling pressure of the

  6. Mechanical interaction buffer/backfill. Finite element calculations of the upward swelling of the buffer against both dry and saturated backfill

    International Nuclear Information System (INIS)

    Boergesson, Lennart; Hernelind, Jan

    2009-10-01

    The mechanical interaction between the buffer material in the deposition hole and the backfill material in the deposition tunnel is an important process in the safety assessment since the primary function of the backfill is to keep the buffer in place and not allow it to expand too much and thereby loose too much of its density and barrier properties. In order to study the upwards swelling of the buffer and the subsequent density reduction a number of finite element calculations have been performed. The calculations have been done with the FE-program Abaqus with 3D-models of a deposition hole and the deposition tunnel. In order to refine the modelling only the two extreme cases of completely un-wetted (dry) and completely water saturated (wet) backfill have been modelled. For the wet case the influence of different factors has been studied while only one calculation of the dry case has been done. The calculated upwards swelling of the buffer varied between 2 and 15 cm for the different wet cases while it was about 10 cm for the dry case. In the wet reference case the E-modulus of the block and pellets fillings was 50 MPa and 3.24 MPa respectively, the friction angle between the buffer and the rock and canister was 8.7 deg and there were no swelling pressure from the backfill. There is a strong influence of the friction angle on both the upwards swelling and the canister heave. The friction is important for preventing especially canister displacements. The unrealistic case of no friction yielded strong unacceptable influence on the buffer with an upwards swelling of 15 cm and a strong heave of 5 cm of the canister. The influence of the backfill stiffness is as expected strong. Both buffer swelling and canister heave are twice as large at the E-modulus E = 25 MPa than at the E-modulus E = 100 MPa. The influence of the stiffness of the pellets filling is not strong since there are no pellets on the floor in the model used. The influence of the swelling pressure of the

  7. 2D and 3D finite element analysis of buffer-backfill interaction

    International Nuclear Information System (INIS)

    Leoni, M.

    2013-08-01

    Methods for backfilling and sealing of disposal tunnels in an underground repository for spent nuclear fuel are studied in cooperation between Finland (Posiva Oy) and Sweden (Svensk Kaernbraenslehantering AB, SKB) in 'BAckfilling and CLOsure of the deep repository' (Baclo) programme. Baclo phase III included modelling task force SP1: Finite element modelling of deformation of the backfill due to swelling of the buffer. The objective of the finite element modelling of the backfill was to study the interaction between the buffer and backfilling. The calculations aimed to find out how large deformations can happen in the buffer-backfill interface causing loosening of the buffer bentonite above the canister. The criterion used was that the saturated density of the buffer right above the canister should be higher than 1990 kg/m 3 . This report presents the results of finite element numerical analyses carried out by Wesi Geotecnica Srl. The modelling calculations were conducted with the so-called OL1-2 deposition tunnel geometry (Juvankoski 2009). Several parameters have been considered, varying from geometry variations to different mechanical constitutive models for different components of the model. In all analyses it has been assumed that the buffer material is fully saturated, thus exerting the isotropic swelling pressure estimated in the range 7 MPa .. 15 MPa, against a fully-dry backfill, which is no doubt the 'worst case scenario' with the highest risk to lead in decrease in dry density of the buffer. Friedland clay has been considered for backfill blocks and 30/70 mixture for foundation bed on which backfill blocks are installed. Preliminarily, finite element analyses have been performed with newly released PLAXIS 2D 2010 within the assumption of axial symmetry, the purpose of this first set of calculations being the evaluation of most relevant parameters influencing the deformations of buffer material. Hence, full 3D calculations have been performed with PLAXIS

  8. Deep repository - engineered barrier systems. Assessment of backfill materials and methods for deposition tunnels

    International Nuclear Information System (INIS)

    Gunnarsson, D.; Moren, L.; Sellin, P; Keto, P.

    2007-09-01

    The main objectives of this report are to: (1) present density criteria considering deposition tunnels for the investigated backfill materials, (2) evaluate what densities can be achieved with the suggested backfill methods, (3) compare the density criteria to achievable densities, (4) based on this comparison evaluate the safety margin for the combinations of backfill materials and methods and, (5) make recommendations for further investigations and development work. The backfilling methods considered in this report are compaction of backfill material in situ in the tunnel and placement of pre-compacted blocks and pellets. The materials investigated in the second phase of the SKB-Posiva backfilling programme can be divided into three main categories: (1) Bentonite clays: two high-grade Na-bentonites from Wyoming (MX-80 and SPV200), one low-grade bentonite from Kutch (India Asha 2 0), and one high- and one low-grade Ca-bentonite from Milos (Deponite CA-N and Milos backfill). The highgrade bentonites are used in different bentonite-ballast mixtures. (2) Smectite-rich mixed-layer clays: one from Dnesice-Plzensko Jih (DPJ) located in the Czech Republic and one from Northern Germany (Friedland clay). (3) Mixtures of bentonite and ballast: Mixtures consisting of high-grade bentonite (30, 40 and 50 w-%) and crushed rock with different type of grain size distribution or sand. The general conclusion from the comparison between estimated achievable densities and the density criteria is that placing pre-compacted blocks of swelling clay or 50/50 mixture and pellets in the tunnel results in the highest safety margin. (orig.)

  9. Optimization of backfill pellet properties AASKAR DP2 - Laboratory tests

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Linus; Sanden, Torbjoern [Clay Technology AB, Lund (Sweden)

    2012-12-15

    Bentonite pellets are planned to be used as a part of the backfill in the Swedish spent nuclear fuel deep repository concept KBS-3. This report describes testing and evaluation of different backfill pellet candidates. The work completed included testing of both pellet material and pellet type. The materials tested were sourced from India (ASHA), Greece (IBECO, 2 products) and Wyoming USA (MX-80 clay). The majority of the tests were completed on the ASHA clay as well as the IBECO-RWC-BF products, with only limited testing of the others. The pellets tested were manufactured using both extrusion and roller compaction techniques and had different sizes and geometries. The following tests have been performed and are presented in this report: 1. General tests. Water content, bulk density and dry density have been determined for both the pellet filling and the individual pellets. The compressibility of the pellet filling was tested with CRS-tests and the strength of the individual pellets was tested with a special compression test. The water content varied from 11.3% to 18.7% and was highest for the extruded pellets. The dry density was somewhat higher for the roller-compacted pellets and their compressibility was lower. The strength of the individual pellets was generally higher for the extruded pellets. 2. Erosion. The pellet filling will be exposed to groundwater inflow when installed in the tunnel. This flow could possibly cause significant erosion on the pellet filling. Erosion tests have been performed with comparisons in erosion resistance made on the various material- and pellet-types. The influence of variations in water salinity and flow rates was also tested. The IBECO extruded 6- and 10- mm diameter rods and the compacted Posiva spec.-A pellet filling seem to have the lowest tendency to erode. It is also the IBECO extruded pellet filling that withstands variations in water salinity and flow rates best. 3. Water storing capacity. The pellet filling

  10. Characterization of backfill mortars used in different tunnels in Spain

    Directory of Open Access Journals (Sweden)

    Cavalaro, S.

    2013-03-01

    Full Text Available The main objective of this paper is to compare typical backfill mortars used in Spanish tunnels to fill the annular void left between the lining and the ground by the TBM. Initially, a new experimental program is outlined using material corresponding to 6 mixes from 4 tunnels. The results obtained indicate a considerable difference in the density and in the rheological properties of the mixes tested. According to the estimations performed, this leads to a difference of up to 67% on the potency required from the pumps to inject the material. Furthermore, a correlation between the fine content and the rheological properties of the mix was observed. This correlation may be a practical tool to control and modify the performance of the mortars directly in the worksite.

    El objetivo principal del presente estudio es llevar a cabo la comparación de las dosificaciones de mortero de relleno empleadas en algunos de los grandes túneles españoles para rellenar el hueco anular dejado entre el terreno y el extradós de las dovelas. Inicialmente se hace una nueva propuesta experimental usando la composición y los materiales correspondientes a 6 dosificaciones usadas en 4 túneles. Los resultados obtenidos indican diferencias significativas en cuanto a la densidad, a la consistencia y a las propiedades reológicas. De acuerdo con las estimaciones realizadas, ello se traduce en diferencias de hasta un 67% en la potencia requerida del sistema de bombas de la tuneladora para inyectar el material. Por otro lado, se refleja una correlación entre el contenido de finos de la mezcla y las propiedades reológicas. Esa correlación puede servir para controlar y modificar dichas propiedades de manera fácil y rápida a pie de obra.

  11. Highly permeable, cement-bounded backfilling mortars for SMA repositories

    International Nuclear Information System (INIS)

    Jacobs, F.; Mayer, G.; Wittmann, F.H.

    1994-03-01

    In low- and intermediate-level waste repositories, gas is produced due e.g. to corrosion. This gas must be able to escape from the repository in order to prevent damage to the repository structure. A cement-based backfill should take over this function. For this purpose, the composition of cement-based materials was varied to study their influence on porosity and permeability. In parallel to this study the behaviour of fresh concrete, the liberation of the heat of hydration and the hardened concrete properties were investigated. To characterize the permeability of cement-based materials the following parameters are important: 1) composition of the material (pore fabric), 2) storage conditions (degree of saturation), 3) degree of hydration (age), 4) measuring fluid. A change in the composition of cement-based materials can vary the permeability by ten orders of magnitude. It is shown that, by using dense aggregates, the transport of the fluid takes place through the matrix and along the aggregate/matrix interface. By using porous aggregates the permeability can be increased by two orders of magnitude. In the case of a dense matrix, porous aggregates do not alter the permeability. Increasing the matrix content or interface content increases permeability. Hence light weight mortars are an obvious choice. Like-grained mixes showed higher permeabilities in combination with better mechanical properties but, in comparison to normal mixes, they showed worse flow properties. With the composition cement-: water-: aggregate content 1:0.4:5.33 the likegrained mix with aggregates ranging from 2 to 3 mm proved to be a suitable material. With a low compaction after 28 days this mix reaches a permeability of 4.10 -12 m 2 and an uniaxial cylinder compressive strength of 16 N/mm 2 . (author) 58 figs., 23 tabs., refs

  12. Performance Comparison between Neutralization Tailings and Flotation Tailings Used for Backfill Mix and Mechanism Analysis

    Directory of Open Access Journals (Sweden)

    Bin Han

    2016-01-01

    Full Text Available A comparison test of different tailings used for underground backfill was conducted, using neutralized tailings from BIOX and flotation tailings of Jinfeng Mine. Laboratory comparison test results show that, with neutralized tailings, when the cement dosage is at 19%, backfill UCS after 7 days, 14 days, and 28 days are 105%–163%, 80%–102%, and 33%–43%, respectively, which are higher than those of flotation tailings. When the cement dosage is at 12%, backfill UCS after 7 days, 14 days, and 28 days are 58%–77%, 50%–60%, and 28%–51%, respectively, which are higher than those of flotation tailings. Slurry fluidity of neutralized tailings is lower than that of flotation tailings, while, in these two tailings, the difference of slump and diffusivity values is less than 6%, which is not a significant difference in slurry fluidity. The reason for neutralized tailings showing higher UCS is as follows: during backfill curing, neutralization tailings produce abundant crystals of CaSO4·2H2O in interlaced structure which helps in combining aggregates closely; CaSO4·2H2O hydrates with C3A C4AF contained in the cement and forms clavate cement bacillus which works as a micro reinforcing steel bar. The test proved that neutralized tailings are more optimal for backfilling.

  13. Deformation Monitoring of Waste-Rock-Backfilled Mining Gob for Ground Control.

    Science.gov (United States)

    Zhao, Tongbin; Zhang, Yubao; Zhang, Zhenyu; Li, Zhanhai; Ma, Shuqi

    2017-05-05

    Backfill mining is an effective option to mitigate ground subsidence, especially for mining under surface infrastructure, such as buildings, dams, rivers and railways. To evaluate its performance, continual long-term field monitoring of the deformation of backfilled gob is important to satisfy strict public scrutiny. Based on industrial Ethernet, a real-time monitoring system was established to monitor the deformation of waste-rock-backfilled gob at -700 m depth in the Tangshan coal mine, Hebei Province, China. The designed deformation sensors, based on a resistance transducer mechanism, were placed vertically between the roof and floor. Stress sensors were installed above square steel plates that were anchored to the floor strata. Meanwhile, data cables were protected by steel tubes in case of damage. The developed system continually harvested field data for three months. The results show that industrial Ethernet technology can be reliably used for long-term data transmission in complicated underground mining conditions. The monitoring reveals that the roof subsidence of the backfilled gob area can be categorized into four phases. The bearing load of the backfill developed gradually and simultaneously with the deformation of the roof strata, and started to be almost invariable when the mining face passed 97 m.

  14. An Investigation of the Uniaxial Compressive Strength of a Cemented Hydraulic Backfill Made of Alluvial Sand

    Directory of Open Access Journals (Sweden)

    Guangsheng Liu

    2017-01-01

    Full Text Available Backfill is commonly used in underground mines. The quality control of the backfill is a key step to ensure it meets the designed strength requirement. This is done through sample collection from the underground environment, followed by uniaxial compression tests to obtain the Uniaxial Compressive Strength (UCS in the laboratory. When the cylindrical cemented backfill samples are axially loaded to failure, several failure modes can be observed and mainly classified into diagonal shear failure and axial split failure. To date, the UCS obtained by these two failure modes are considered to be the same with no distinction between them. In this paper, an analysis of the UCS results obtained on a cemented hydraulic backfill made of alluvial sand at a Canadian underground mine over the course of more than three years is presented. The results show that the UCS values obtained by diagonal shear failure are generally higher than those obtained by axial split failure for samples with the same recipe and curing time. This highlights the importance of making a distinction between the UCS values obtained by the two different modes of failure. Their difference in failure mechanism is explained. Further investigations on the sources of the data dispersion tend to indicate that the UCS obtained by laboratory tests following the current practice may not be representative of the in-situ strength distribution in the underground stopes due to segregation in cemented hydraulic backfill.

  15. Cemented Backfilling Technology of Paste-Like Based on Aeolian Sand and Tailings

    Directory of Open Access Journals (Sweden)

    Qinli Zhang

    2016-12-01

    Full Text Available Aeolian sand, tailings, and #32.5 Portland cement were used to produce backfilling aggregate, and physicochemical evaluations and proportioning tests were conducted. It is revealed that a mixture of aeolian sand and tailings can be used as a backfilling aggregate for the complementarities of their physicochemical properties; e.g., high Al2O3 content in the aeolian sand and CaO content in the tailings, coarse particles of aeolian sand and fine particles of tailings, etc. In addition, the optimal backfilling aggregate was shown to have a mass fraction of 72%–74%, a cement–sand ratio of 1:8, and an aeolian sand proportion of 25%. Furthermore, viscometer tests were used to analyze the rheological characteristics, and the slurry in these optimized proportions exhibited shear thinning phenomena with an initial yield stress, which belongs to paste-like—a cemented backfilling slurry with a higher mass fraction than a two-phase flow and better flowability than a paste slurry. Finally, the application of this backfilling technology shows that it can not only realize safe mining, but also bring huge economic benefits, and has some constructive guidance for environmental protection.

  16. EFFECTS OF THE BACK-FILLING TO THE STABILITY OF A CAISSON

    Science.gov (United States)

    Kikuchi, Yoshiaki; Shinsha, Hiroshi; Kawamura, Kensuke; Eguchi, Shinya

    The back-filling improves the stability of a caisson used for breakwater against wave force. But, the extent of the improvement of the stability is affected by the interaction among the back-filling and the caisson and the foundation. A series of the model loading experiments was carried out to clarify the effects of the interaction to the stability. In this series of experiments, horizontal static load was applied to the model caisson having back-filling. Sliding failure surface was estimated from the deformation of rubble mound and back-filling. Passive earth pressure by back-filling calculated by wedge theory was compared with the experimental results. New stability evaluation method considering circular arc failure mode was developed and evaluated its validity. Followings are main conclusions in this research; 1) Increment of stability of a caisson against wave force can be estimated from wedge theory. 2) Both sliding and bearing capacity stability were considered in one time using newly developed evaluation method considering circular arc failure mode.

  17. Field and laboratory investigations on pavement backfilling material for micro-trenching in cold regions

    Directory of Open Access Journals (Sweden)

    Leila Hashemian

    2017-07-01

    Full Text Available Micro-trenching is an innovative utility installation method that involves creating a narrow trench to place cable or conduit in the road pavement. Compared to other installation methods, micro-trenching provides minimal disturbance to the community and surrounding environment. Despite the advantages of micro-trenching, it is not widely accepted by municipalities because of its potential to damage the existing pavement. Quality of backfilling is an important factor in long-term sustainability of the micro-trench, particularly in cold regions. This paper investigates the performance of two typical micro-trench backfilling methods in cold climates by studying a pilot project in a parking lot in Edmonton, Alberta, followed by a laboratory evaluation of the material used. For this purpose, the installations were monitored through ground-penetrating radar, optical time-domain reflectometer, and visual observations for three years. The monitoring results revealed that conduit had significant vertical movement inside the trench; several premature failures were also observed in the backfilling material. Laboratory investigation showed that the backfilling material did not meet the criteria for use in cold climates, and micro-trench performance could be enhanced using alternative materials. Keywords: Micro-trench, Pavement backfilling material, Fiber optic installation, Ground-penetrating radar

  18. Effect of localized water uptake on backfill hydration and water movement in a backfilled tunnel: half-scale tests at Aespoe Bentonite Laboratory

    International Nuclear Information System (INIS)

    Dixon, D.; Jonsson, E.; Hansen, J.; Hedin, M.; Ramqvist, G.

    2011-04-01

    The report describes the outcome of the work within the project 'SU508.20 Impact of water inflow in deposition tunnels'. Project decision SKB doc 1178871 Version 3.0. Two activity plans have been used for the field work: AP TD SU50820-09-019 and AP TD SU 50820-09-071. SKB and Posiva have been examining those processes that may have particularly strong effects on the evolution of a newly backfilled deposition tunnel in a KBS-3V repository. These assessments have involved the conduct of increasingly large and complex laboratory tests and simulations of a backfilled tunnel section. In this series of four tests, the effect of water inflow into a backfilled tunnel section via an intersecting fracture feature was evaluated. The tests included the monitoring of mock-ups where water entered via the simulated fractures as well as evaluation of what the effect of isolated tunnel sections caused by localized water inflow would have on subsequent evolution of these isolated sections. It was found that even a slowly seeping fracture can have a substantial effect on the backfill evolution as it will cause development of a gasket-like feature that effectively cuts of air and water movement from inner to outer regions of the backfilled tunnel. Water entering via these fractures will ultimately move out of the tunnel via a single discrete flow path, in a manner similar to what was observed in previous 1/2-scale and smaller simulations. If the low-rate of water inflow from fracture is the only source of water inflow to the tunnel this will result in hydraulic behaviour similar to that observed for a single inflow point in previous tests. The presence of a fracture feature will however result in a larger proportion of water uptake by the process of suction than might occur in a point inflow situation and hence a more uniform water distribution will be present in the pellet fill. This also results in a greater tendency for water to be absorbed into the adjacent block fill material and

  19. Effect of localized water uptake on backfill hydration and water movement in a backfilled tunnel: half-scale tests at Aespoe Bentonite Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, D. [Atomic Energy of Canada Limited, Chalk River (Canada); Jonsson, E. [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Hansen, J. [Posiva Oy, Olkiluoto (Finland); Hedin, M. [Aangpannefoereningen, Stockholm (Sweden); Ramqvist, G. [Eltekno AB, Figeholm (Sweden)

    2011-04-15

    The report describes the outcome of the work within the project 'SU508.20 Impact of water inflow in deposition tunnels'. Project decision SKB doc 1178871 Version 3.0. Two activity plans have been used for the field work: AP TD SU50820-09-019 and AP TD SU 50820-09-071. SKB and Posiva have been examining those processes that may have particularly strong effects on the evolution of a newly backfilled deposition tunnel in a KBS-3V repository. These assessments have involved the conduct of increasingly large and complex laboratory tests and simulations of a backfilled tunnel section. In this series of four tests, the effect of water inflow into a backfilled tunnel section via an intersecting fracture feature was evaluated. The tests included the monitoring of mock-ups where water entered via the simulated fractures as well as evaluation of what the effect of isolated tunnel sections caused by localized water inflow would have on subsequent evolution of these isolated sections. It was found that even a slowly seeping fracture can have a substantial effect on the backfill evolution as it will cause development of a gasket-like feature that effectively cuts of air and water movement from inner to outer regions of the backfilled tunnel. Water entering via these fractures will ultimately move out of the tunnel via a single discrete flow path, in a manner similar to what was observed in previous 1/2-scale and smaller simulations. If the low-rate of water inflow from fracture is the only source of water inflow to the tunnel this will result in hydraulic behaviour similar to that observed for a single inflow point in previous tests. The presence of a fracture feature will however result in a larger proportion of water uptake by the process of suction than might occur in a point inflow situation and hence a more uniform water distribution will be present in the pellet fill. This also results in a greater tendency for water to be absorbed into the adjacent block fill

  20. Underground Cemented Backfill, a Design Procedure for an Integrated Mining Waste Management.

    Directory of Open Access Journals (Sweden)

    Abdelhadi KHALDOUN

    2018-01-01

    Full Text Available From several case studies around the world, it is well known that the binder represents the major part of backfilling operation cost. Therefore, in the case of Imiter operation, research were mainly focused on the optimization of binder content. To this end, the definition of the physical and chemical properties of the future formula ingredients, specifically: tailings, waste material and hydraulic binder, was necessary. Analytical verifications were conducted to predict the UCB mechanical strength according to the defined underground functions and delivery network. Experimental testing, including: uniaxial compression, Immediate Bearing Index (IBI and slump test, were then conducted to evaluate the possibility of reaching the required strength with the selected materials. The obtained results show that the tailings and mining wastes can be used as backfilling material with a specific binder content depending on each underground application. The followed approach can be applied for a prefeasibility evaluation for a backfilling facility.

  1. Colloids in the mortar backfill of a cementitious repository for radioactive waste

    International Nuclear Information System (INIS)

    Wieland, E.; Spieler, P.

    1999-01-01

    Colloids are present in groundwater aquifers and water-permeable engineered barrier systems and may facilitate the migration of radionuclides. A careful evaluation of colloid concentrations is required to assess the potential effect of colloids on nuclide migration and, consequently, on the safety of a repository for radioactive waste. A highly permeable mortar is foreseen to be used as backfill for the engineered barrier of the Swiss repository for low- and intermediate-level waste (L/ILW). The backfill is considered to be a chemical environment with a potential for colloid generation and, due to its high porosity, for colloid mobility. In this contribution a novel in-house built particle counting device is described, and measurements of colloid concentrations in the pore water of backfill mortar are presented. (author)

  2. Managing the risks of the backfill production line from material acquisition to installation

    International Nuclear Information System (INIS)

    Kiviranta, Leena; Kumpulainen, Sirpa; Keto, Paula; Autio, Jorma; Siivonen, Markku; Koho, Petri

    2012-01-01

    Document available in extended abstract form only. The tunnel backfill of Finnish KBS-3V type repository for spent nuclear fuel consists of foundation layer that is installed at site, pre-compacted backfill blocks that fill most of the tunnel and bentonite pellets to fill the gap between blocks and tunnel wall. In order to ensure the quality, availability, and timely delivery of backfill materials and components, and further to ensure the fulfillment of the requirements and specifications set for backfilling of deposition tunnels, the backfill production line was explored step-by-step, and risks related were defined and analyzed. The work described in this paper was initiated by Posiva Oy and is reported in Keto et al. (2012). The first part of the backfill production line is described in Figure 1 for Friedland clay that is designed to be used for the backfill blocks. It consists of excavation, processing and delivery of materials to backfill production facility. Second part of the production line consists of manufacturing of the backfill components, and the third part is the installation. A preliminary risk assessment was done in 2011 for the acquisition of Friedland clay and manufacturing and installation of foundation layer, blocks and pellets. The critical points of the production line were determined using a material flow description where risk is defined as a probability of something unwanted to happen times the severity of the consequences. Risk analysis was performed by going through the whole backfill production line step by step and analyzing all the incidents, which have occurred (or might occur) during the backfilling operations. A risk number from 1 to 25 was given to each step of the chain depending on how long delay the problem causes and how often it occurs. Low risk was the target for each step of the chain, medium risk was considered tolerable, for high risks management actions to decrease the risk number were considered and extremely high risks

  3. The advantages of a salt/bentonite backfill for Waste Isolation Pilot Plant disposal rooms

    International Nuclear Information System (INIS)

    Butcher, B.M.; Novak, C.F.; Jercinovic, M.

    1991-04-01

    A 70/30 wt% salt/bentonite mixture is shown to be preferable to pure crushed salt as backfill for disposal rooms in the Waste Isolation Pilot Plant (WIPP). This report discusses several selection criteria used to arrive at this conclusion: the need for low permeability and porosity after closure, chemical stability with the surroundings, adequate strength to avoid shear erosion from human intrusion, ease of emplacement, and sorption potential for brine and radionuclides. Both salt and salt/bentonite are expected to consolidate to a final state of impermeability (i.e., ≤ 10 -18 m 2 ) adequate for satisfying federal nuclear regulations. Any advantage of the salt/bentonite mixture is dependent upon bentonite's potential for sorbing brine and radionuclides. Estimates suggest that bentonite's sorption potential for water in brine is much less than for pure water. While no credit is presently taken for brine sorption in salt/bentonite backfill, the possibility that some amount of inflowing brine would be chemically bound is considered likely. Bentonite may also sorb much of the plutonium, americium, and neptunium within the disposal room inventory. Sorption would be effective only if a major portion of the backfill is in contact with radioactive brine. Brine flow from the waste out through highly localized channels in the backfill would negate sorption effectiveness. Although the sorption potentials of bentonite for both brine and radionuclides are not ideal, they are distinctly beneficial. Furthermore, no detrimental aspects of adding bentonite to the salt as a backfill have been identified. These two observations are the major reasons for selecting salt/bentonite as a backfill within the WIPP. 39 refs., 16 figs., 6 tabs

  4. Comments on US approach to backfilling: Thermochemical characterization of crushed salt

    International Nuclear Information System (INIS)

    Smith, S.; Hume, H.

    1988-01-01

    From recent studies and calculations, it has become apparent that expected brine in a United States salt repository would not seriously detract from the usefulness of rock salt as backfill. It also has been shown that adding clay to the salt might add to the pressure on the emplaced waste packages. Nevertheless, the Salt Repository Project has planned to evaluate a betonite/salt mixture during the next few years. The following items have also been discussed: advantages of backfilling, variables affecting crushed salt behavior, and the general approach to a preliminary testing program

  5. Backfilling of a Scour Hole around a Pile in Waves and Current

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu; Petersen, Thor Ugelvig; Locatelli, Luca

    2013-01-01

    This paper presents the results of an experimental investigation of the backfilling of scour holes around circular piles. Scour holes around a pile are generated either by a current or a wave. Subsequently, the flow climate is changed from current to wave, combined waves and current, or wave...... around the pile for the same wave (or combined waves and current) climate. The time scale of backfilling has been determined as a function of three parameters, namely, (1) the Keulegan-Carpenter number of the initial wave or current (which generates the initial scour hole); (2) that of the subsequent...

  6. Refinement of Foam Backfill Technology for Expedient Airfield Damage Repair; Phase 2: Development of Prototype Foam Dispensing Equipment and Improved Tactics, Techniques and Procedures

    Science.gov (United States)

    2017-12-01

    ER D C TR -1 7- 14 U.S. Air Force Rapid Airfield Damage Repair Modernization Program Refinement of Foam Backfill Technology for...Backfill Technology for Expedient Airfield Damage Repair Phase II: Development of Prototype Foam Dispensing Equipment and Improved Tactics...procedures (TTPs) for rapid airfield damage repair (RADR) using foam backfill technology . Three different prototype foam dispensing systems were

  7. Efficacy of backfilling and other engineered barriers in a radioactive waste repository in salt

    International Nuclear Information System (INIS)

    Claiborne, H.C.

    1982-09-01

    In the United States, investigation of potential host geologic formations was expanded in 1975 to include hard rocks. Potential groundwater intrusion is leading to very conservative and expensive waste package designs. Recent studies have concluded that incentives for engineered barriers and 1000-year canisters probably do not exist for reasonable breach scenarios. The assumption that multibarriers will significantly increase the safety margin is also questioned. Use of a bentonite backfill for surrounding a canister of exotic materials was developed in Sweden and is being considered in the US. The expectation that bentonite will remain essentially unchanged for hundreds of years for US repository designs may be unrealistic. In addition, thick bentonite backfills will increase the canister surface temperature and add much more water around the canister. The use of desiccant materials, such as CaO or MgO, for backfilling seems to be a better method of protecting the canister. An argument can also be made for not using backfill material in salt repositories since the 30-cm-thick space will provide for hole closure for many years and will promote heat transfer via natural convection. It is concluded that expensive safety systems are being considered for repository designs that do not necessarily increase the safety margin. It is recommended that the safety systems for waste repositories in different geologic media be addressed individually and that cost-benefit analyses be performed

  8. Vault-Scale Modelling of pH Buffering Capacity in Crushed Granite Backfills

    International Nuclear Information System (INIS)

    Benbow, Steven; Savage, David; Robinson, Peter; Watson, Sarah

    2004-04-01

    Some engineered barrier designs for geological repositories for radioactive wastes rely upon the use of cement as chemical conditioning agents for the wastes. Although the hyper alkaline pore fluids characteristic of cements may have a positive effect upon near-field performance, their migration into the geosphere poses problems regarding potentially deleterious interactions along groundwater flow paths, e.g. change of sorption or matrix diffusion properties of the host rock. To counteract these potential effects, SKB has developed the concept of a gravel backfill for its SFL 3-5 repository, where it is anticipated that the gravel would act as a 'sacrificial' reactive barrier between cement conditioned wastes and the geosphere. This role is dependent upon the reaction of silicate and aluminosilicate minerals in the gravel through hydroxyl ion-catalysed mineral dissolution reactions and the associated precipitation of hydroxyl ion bearing solids, such as calcium silicate hydrates. This barrier concept has been evaluated by the simulation of groundwater flow and chemical reaction of cement pore fluid through a realistic backfill geometry and various potential groundwater flow scenarios. Potential groundwater flow conditions through gravel backfill for the SFL 3-5 repository concept were modelled in 3D using MODFLOW. The regional groundwater flow field was assumed to be horizontal and its interaction with a homogeneous backfill of dimensions in accordance with published designs for the SKB SFL 3-5 repository, with uniform physical and hydraulic properties was investigated. The host rock also had uniform properties, except where simulations explicitly represented transmissive features. Calculations of cement pore fluid migration and reaction with backfill were carried out using Raiden2, a fully-coupled reaction-transport simulator. Flow fields generated in 3D with MODFLOW were converted to 2D 'slices' for reaction-transport calculations. The backfill was assumed to

  9. Backfilling and sealing of tunnels, shafts and boreholes. Volume 2: Appendices

    International Nuclear Information System (INIS)

    Studer, J.; Ammann, W.; Meier, P.; Mueller, Ch.; Glauser, E.

    1984-12-01

    The present report is a synthesis of the state of knowledge regarding backfilling and sealing of nuclear waste repositories. It is based on an evaluation of both the general and special publications concerning this problem (articles in scientific journals, research reports, conference papers and textbooks) and represents the state of knowledge up to summer 1984. In addition, it contains an outlook on the continuing work. This will serve to broaden the scientific base and to achieve the technical as well as economical optimization. The report consists of two volumes: Volume 1 Main Part, Volume 2 Appendices. Starting with the functions of backfilling and sealing in the safety concept assessment criteria and from these, taking into consideration the given conditions in the project 'Gewaehr 1985' ('Guarantee'), the requirements for the backfilling and sealing materials are formulated. The properties of several materials under consideration are discussed in the Appendix together with a detailed description of the most important of these materials. The reasons are given for the choice of the proposed materials for the project 'Gewaehr 1985'. Alternative backfilling and sealing concepts for repositories Type B and Type C are presented and reasons are given for the selected variants for the project 'Gewaehr 1985'. Chapter 10 represents a review of the report. This report is intended as a reference work for the corresponding chapters in the NGB reports (cf. /NGB 85-03, 1985/, /NGB 85-06, 1985/). (author)

  10. Buffer, backfill and closure process report for the safety assessment SR-Site

    International Nuclear Information System (INIS)

    Sellin, Patrik

    2010-11-01

    This report gives an account of how processes in buffer, deposition tunnel backfill and the closure important for the long-term evolution of a KBS-3 repository for spent nuclear fuel, will be documented in the safety assessment SR-Site

  11. The Community project on engineering aspects of backfilling and sealing of radioactive waste repositories

    International Nuclear Information System (INIS)

    Lake, L.M.; Bennett, A.

    1987-01-01

    This report summarizes the work carried out under CEC contracts about engineering aspects of backfilling and sealing of radioactive waste repositories, for the time period 1983-84. It complements a previous report (ref. EUR 9283) on the same topic, this latter covering the period 1980-82

  12. Prediction of unsaturated flow and water backfill during infiltration in layered soils

    Science.gov (United States)

    Cui, Guotao; Zhu, Jianting

    2018-02-01

    We develop a new analytical infiltration model to determine water flow dynamics around layer interfaces during infiltration process in layered soils. The model mainly involves the analytical solutions to quadratic equations to determine the flux rates around the interfaces. Active water content profile behind the wetting front is developed based on the solution of steady state flow to dynamically update active parameters in sharp wetting front infiltration equations and to predict unsaturated flow in coarse layers before the front reaches an impeding fine layer. The effect of water backfill to saturate the coarse layers after the wetting front encounters the impeding fine layer is analytically expressed based on the active water content profiles. Comparison to the numerical solutions of the Richards equation shows that the new model can well capture water dynamics in relation to the arrangement of soil layers. The steady state active water content profile can be used to predict the saturation state of all layers when the wetting front first passes through these layers during the unsteady infiltration process. Water backfill effect may occur when the unsaturated wetting front encounters a fine layer underlying a coarse layer. Sensitivity analysis shows that saturated hydraulic conductivity is the parameter dictating the occurrence of unsaturated flow and water backfill and can be used to represent the coarseness of soil layers. Water backfill effect occurs in coarse layers between upper and lower fine layers when the lower layer is not significantly coarser than the upper layer.

  13. Evaluation of the effect of sodium silicate addition to mine backfill, Gelfill − Part 1

    Directory of Open Access Journals (Sweden)

    M. Kermani

    2015-06-01

    Full Text Available In this paper, the mechanical properties of sodium silicate-fortified backfill, called Gelfill, were investigated by conducting a series of laboratory experiments. Two configurations were tested, i.e. Gelfill and cemented hydraulic fill (CHF. The Gelfill has an alkali activator such as sodium silicate in its materials in addition to primary materials of mine backfill which are tailings, water and binders. Large numbers of samples of Gelfill and CHF with various mixture designs were cast and cured for over 28 d. The mechanical properties of samples were investigated using uniaxial compression test, and the results were compared with those of reference samples made without sodium silicate. The test results indicated that the addition of an appropriate amount of an alkali activator such as sodium silicate can enhance the mechanical (uniaxial compressive strength and physical (water retention properties of backfill. The microstructure analysis conducted by mercury intrusion porosimetry (MIP revealed that the addition of sodium silicate can modify the pore size distribution and total porosity of Gelfill, which can contribute to the better mechanical properties of Gelfill. It was also shown that the time and rate of drainage in the Gelfill specimens are less than those in CHF specimens made without sodium silicate. Finally, the study showed that the addition of sodium silicate can reduce the required setting time of mine backfill, which can contribute to increase mine production in accordance with the mine safety.

  14. The behaviour of cemented backfill and the surrounding rockmass at western deep levels south mine

    CSIR Research Space (South Africa)

    York, G

    1992-11-01

    Full Text Available Cemented backfill is used at Western Deep Mine as local and regional support areas of high stopping width. The in situ performance is reported and compared to laboratory tests. A back analysis was carried out to obtain a more accurate value...

  15. Buffer, backfill and closure process report for the safety assessment SR-Site

    Energy Technology Data Exchange (ETDEWEB)

    Sellin, Patrik (ed.)

    2010-11-15

    This report gives an account of how processes in buffer, deposition tunnel backfill and the closure important for the long-term evolution of a KBS-3 repository for spent nuclear fuel, will be documented in the safety assessment SR-Site

  16. Results of a backfill monitoring programme at Vaal Reefs 5 Shaft

    CSIR Research Space (South Africa)

    Squelch, AP

    1990-08-01

    Full Text Available This report documents the results of the in situ measurements carried out in the 68-52 stope at Vaal Reefs 5 Shaft. The in situ stress-strain behaviour of classified tailing backfill has been measured in panel P3. There is good agreement between...

  17. Water saturation phase of the buffer and backfill in the KBS-3V concept. Special emphasis given to the influence of the backfill on the wetting of the buffer

    Energy Technology Data Exchange (ETDEWEB)

    Boergesson, Lennart; Faelth, Billy [Clay Technology AB, Lund (Sweden); Hernelind, Jan [5T Engineering AB, Vaesteraas (Sweden)

    2006-08-15

    The wetting and rate of saturation of the buffer and backfill materials in a KBS- V repository from the rock fractures and the rock matrix have been investigated by a large number of different finite element models and calculations. For most models the FE-code ABAQUS has been used but for investigation of the influence of trapped air in the backfill FE-code Code Bright was used. Both codes include completely coupled THM models, which have been used, but for some calculations it has been sufficient to limit the models to only use the hydraulic or thermohydraulic parts of the models. The following analyses have been made: 1. The influence of the backfill properties and wetting conditions on the water saturation phase of the buffer has been investigated with the old FEM-model used in earlier wetting calculations for SR-97. The old calculations have been updated regarding the influence of the backfill. The model is 2-dimensional with axial symmetry around the axis of the deposition hole. These calculations show that there is strong influence of wetting from the backfill if the rock is rather dry (K{sub rock} = 10{sup -13} m/s), while the influence is low if the rock is rather wet (K{sub rock} = 10{sup -12} m/s). At K{sub rock} = 10{sup -13} m/s the time to saturation decreases with a factor 2 in the absence of fractures and with a factor 1.5 with two fractures intersecting the hole when water is supplied from the backfill (30/70) compared to when no water is available. A completely dry rock yields very long time to saturation and of course decisive influence of the water supply from the backfill. If water is freely available at a water pressure of 5 MPa in the backfill it takes 250-500 years to reach full saturation of the buffer. If the water available in the backfill is limited to the initial amount (completely dry rock also around the tunnel and thus no addition of water from the rock in the tunnel) it will take several thousands years to reach some kind of

  18. Water saturation phase of the buffer and backfill in the KBS-3V concept. Special emphasis given to the influence of the backfill on the wetting of the buffer

    International Nuclear Information System (INIS)

    Boergesson, Lennart; Faelth, Billy; Hernelind, Jan

    2006-08-01

    The wetting and rate of saturation of the buffer and backfill materials in a KBS- V repository from the rock fractures and the rock matrix have been investigated by a large number of different finite element models and calculations. For most models the FE-code ABAQUS has been used but for investigation of the influence of trapped air in the backfill FE-code Code Bright was used. Both codes include completely coupled THM models, which have been used, but for some calculations it has been sufficient to limit the models to only use the hydraulic or thermohydraulic parts of the models. The following analyses have been made: 1. The influence of the backfill properties and wetting conditions on the water saturation phase of the buffer has been investigated with the old FEM-model used in earlier wetting calculations for SR-97. The old calculations have been updated regarding the influence of the backfill. The model is 2-dimensional with axial symmetry around the axis of the deposition hole. These calculations show that there is strong influence of wetting from the backfill if the rock is rather dry (K rock = 10 -13 m/s), while the influence is low if the rock is rather wet (K rock = 10 -12 m/s). At K rock = 10 -13 m/s the time to saturation decreases with a factor 2 in the absence of fractures and with a factor 1.5 with two fractures intersecting the hole when water is supplied from the backfill (30/70) compared to when no water is available. A completely dry rock yields very long time to saturation and of course decisive influence of the water supply from the backfill. If water is freely available at a water pressure of 5 MPa in the backfill it takes 250-500 years to reach full saturation of the buffer. If the water available in the backfill is limited to the initial amount (completely dry rock also around the tunnel and thus no addition of water from the rock in the tunnel) it will take several thousands years to reach some kind of equilibrium with a degree of

  19. Development and validation of a CFD model predicting the backfill process of a nuclear waste gallery

    International Nuclear Information System (INIS)

    Gopala, Vinay Ramohalli; Lycklama a Nijeholt, Jan-Aiso; Bakker, Paul; Haverkate, Benno

    2011-01-01

    Research highlights: → This work presents the CFD simulation of the backfill process of Supercontainers with nuclear waste emplaced in a disposal gallery. → The cement-based material used for backfill is grout and the flow of grout is modelled as a Bingham fluid. → The model is verified against an analytical solution and validated against the flowability tests for concrete. → Comparison between backfill plexiglas experiment and simulation shows a distinct difference in the filling pattern. → The numerical model needs to be further developed to include segregation effects and thixotropic behavior of grout. - Abstract: Nuclear waste material may be stored in underground tunnels for long term storage. The example treated in this article is based on the current Belgian disposal concept for High-Level Waste (HLW), in which the nuclear waste material is packed in concrete shielded packages, called Supercontainers, which are inserted into these tunnels. After placement of the packages in the underground tunnels, the remaining voids between the packages and the tunnel lining is filled-up with a cement-based material called grout in order to encase the stored containers into the underground spacing. This encasement of the stored containers inside the tunnels is known as the backfill process. A good backfill process is necessary to stabilize the waste gallery against ground settlements. A numerical model to simulate the backfill process can help to improve and optimize the process by ensuring a homogeneous filling with no air voids and also optimization of the injection positions to achieve a homogeneous filling. The objective of the present work is to develop such a numerical code that can predict the backfill process well and validate the model against the available experiments and analytical solutions. In the present work the rheology of Grout is modelled as a Bingham fluid which is implemented in OpenFOAM - a finite volume-based open source computational fluid

  20. Bentonite as backfill in a final repository for high-level waste: chemical aspects

    International Nuclear Information System (INIS)

    Grauer, R.

    1986-01-01

    The present Nagra concept for disposal of high-level waste foresees emplacing the steel containers enclosing the borosilicate glass in tunnels at a depth of 1000 to 1500 m. These tunnels are to be backfilled with bentonite. Bentonites are suitable as a backfill due to their swelling capability, their low hydraulic conductivity and their sorption properties. This report is restricted to chemical aspects of the backfill material: swelling capability, sorption properties and long-term stability. Under repository conditions, the swelling of monmorillonite upon water inflow is primarily innercrystalline. Cation adsorption, which is important for nuclide retention in the repository, can be described by appropriate models. It can be concluded from natural analogue studies and from laboratory experiments that the properties of the backfill material will not alter significantly over a periode of 10/sup 6/ years. Nevertheless in the long term, the formulation of mixed-layer illite/monmorillonite cannot be ruled out. Such mixed-layer clays still have good swelling and sorption properties. Given the quantity ratios foreseen, no adverse changes due to radioactive decay are to be expected. The interaction between the bentonite and the container corrosion products must, in the absence of literature data, be investigated experimentally. The type of reaction products expected (iron-containing clay minerals) and the high bentonite/iron ratio lead to the conclusion that the function of the backfill need not be impaired by these processes. Because of its better stability, a calcium bentonite is preferable to the sodium variant. A low iron content is desirable because, under reducing conditions, the surface charge of the montorillonite is increased by reduction of iron(III). Organic and sulphidic contaminants should also be kept to a minimum

  1. Development of backfill material as an engineered barrier in the waste package system. Interim topical report

    International Nuclear Information System (INIS)

    Wheelwright, E.J.; Hodges, F.N.; Bray, L.A.; Westsik, J.H. Jr.; Lester, D.H.; Nakai, T.L.; Spaeth, M.E.; Stula, R.T.

    1981-09-01

    A backfill barrier, emplaced between the containerized waste and the host rock, can both protect the other engineered barriers and act as a primary barrier to the release of radionuclides from the waste package. Attributes that a backfill should provide in order to carry out its required function have been identified. Primary attributes are those that have a direct effect upon the release and transport of radionuclides from the waste package. Supportive attributes do not directly affect radionuclide release but are necessary to support the primary attributes. The primary attributes, in order of importance, are: minimize (retard or exclude) the migration of ground water between the host rock and the waste canister system; retard the migration of selected chemical species (corrosive species and radionuclides) in the ground water; control the Eh and pH of the ground water within the waste-package environment. The supportive attributes are: self-seal any cracks or discontinuities in the backfill or interfacing host geology; retain performance properties at all repository temperatures; retain peformance properties during and after receiving repository levels of gamma radiation; conduct heat from the canister system to the host geology; retain mechanical properties and provide resistance to applied mechanical forces; retain morphological stability and compatibility with structural barriers and with the host geology for required period of time. Screening and selection of candidate backfill materials has resulted in a preliminary list of materials for testing. Primary emphasis has been placed on sodium and calcium bentonites and zeolites used in conjunction with quartz sand or crushed host rock. Preliminary laboratory studies have concentrated on permeability, sorption, swelling pressure, and compaction properties of candidate backfill materials

  2. Fat metaplasia and backfill are key intermediaries in the development of sacroiliac joint ankylosis in patients with ankylosing spondylitis

    DEFF Research Database (Denmark)

    Maksymowych, Walter P; Wichuk, Stephanie; Chiowchanwisawakit, Praveena

    2014-01-01

    step in this pathway. METHODS: We used the Spondyloarthritis Research Consortium of Canada (SPARCC) SI structural lesion score (SSS) method to assess fat metaplasia, erosions, backfill, and ankylosis on MRIs of the SI joints in 147 patients with AS monitored for 2 years. Univariate and multivariate...... regression analyses focused first on identifying significant MRI predictors of new backfill and fat metaplasia. We then assessed the role of backfill and fat metaplasia in the development of new ankylosis. All analyses were adjusted for demographic features, treatment, and baseline and 2-year change in SSS...

  3. Preliminary on-surface experiments for backfilling a HLW repository: the ESDRED project

    International Nuclear Information System (INIS)

    Bastiaens, W.

    2007-01-01

    ESDRED is a technological integrated project within the context of the Sixth Framework Program of EURATOM. The project aims to demonstrate the technical feasibility at an industrial scale of specific technologies related to the construction, operation and closure of a deep geological repository for spent fuel and long-lived radioactive waste. The Belgian design for high level waste disposal is based on the so-called Supercontainer concept. Within this concept, the waste is encased in a carbon steel overpack, which is consequently fitted into a 70 cm thick concrete shell, in its turn enveloped by a stainless steel liner. A Supercontainer measures about 2 m in diameter. In the design of the repository, the Supercontainers will be emplaced, one after the other, in disposal galleries. The space between the Supercontainers and the gallery lining needs to be filled up with a solid material. The most essential function of this component, referred to as backfill, is to prevent a collapse of the gallery. A secondary function is to limit the presence of free oxygen, to limit corrosion. In the ESDRED project EIG EURIDICE, together with SCK-CEN and ONDRAF/NIRAS, investigates technologies to apply the backfill. Two options to apply the backfill were investigated within the ESDRED project: fill the gap with a granular material and backfill the gap with a grout. The prime operational target will be to achieve a 100 percent filling of the gap. A wide variety of materials was tested. A number of considerations regarding long-term safety and operational feasibility impose constraints on the backfill component:it should preserve the corrosion-protective environment established by the Supercontainer; it should not act as a thermal isolator; it should not introduce organic materials that can give rise to the formation of migration-enhancing complexes between radionuclides and soluble organic compounds; it should be feasible to construct at a sufficiently high rate; the strength of the

  4. Simulation of water recovery and its effect on settlement of open-cut coal mine back-fill

    International Nuclear Information System (INIS)

    Naderian, A.R.; Williams, D.J.

    1996-01-01

    Open-cut coal mine back-fill usually undergoes significant settlement due to inundation by surface water infiltration and groundwater rise. The rate and magnitude of inundation settlement is difficult to predict and quantify due to the large number of contributing factors. Consequently, none of the available settlement models and theories has been able to successfully describe the inundation settlement occurring in back-filled open-cut coal mines. A combination of laboratory and numerical simulation of settlement is a valuable means of estimating the inundation settlement of back-fill. The settlements predicted by this simulation are in good agreement with previous observations of inundation settlement in open-cut coal mine back-fill. 11 refs., 14 figs., 1 tab

  5. Utilization of Foaming Technology in Cemented Paste Backfill of High-Mud Superfine Unclassified Tailings

    Directory of Open Access Journals (Sweden)

    Jian-wen Zhao

    2017-01-01

    Full Text Available Due to high-mud content in superfine unclassified tailings (SUT, the viscosity of cemented paste backfill (CPB is high and its pipeline transportation properties are poor. Foaming technology was introduced to prepare a new three-phase flow backfill (TFB using a foaming machine. Then the rheological parameters of TFB with different bubble ratio were measured and their pipeline transportation properties were simulated by Fluent. Besides, the simulation results were further verified by a semi-industrial loop test. The results indicate that the optimum ratio of TFB is a cement-sand ratio of 1 : 8, mass concentration of 70%, and bubble ratio of 20%. Compared with CPB, the decrease of bleeding rate, viscosity, and resistance loss of TFB is 27%, 25%, and 30%, respectively. Therefore, foaming technology is an innovative and feasible solution for high-mud CPB in reducing viscosity, decreasing resistance loss, and improving pipeline transporting efficiency.

  6. Properties of backfilling material for solidifying miscellaneous waste using recycled cement from waste concrete

    International Nuclear Information System (INIS)

    Matsuda, Atsuo; Yamamoto, Kazuo; Konishi, Masao; Iwamoto, Yoshiaki; Yoshikane, Toru; Koie, Toshio; Nakashima, Yoshio.

    1997-01-01

    A large reduction of total radioactive waste is expected, if recycled cement from the waste concrete of decommissioned nuclear power plants would be able to be used the material for backfilling mortar among the miscellaneous waste. In this paper, we discuss the hydration, strength and consistency of recycled cement compared with normal portland cement. The strength of recycled cement mortar is lower than that of normal portland cement mortar on the same water to cement ratio. It is possible to obtain the required strength to reduce the water to cement ratio by using of high range water-reducing AE agent. According to reducing of water to cement ratio, the P-type funnel time of mortar increase with the increase of its viscosity. However, in new method of self-compactability for backfilling mortar, it became evident that there was no difference between the recycled cement and normal portland cement on the self-compactability. (author)

  7. EXPERIMENTAL AND NUMERICAL INVESTIGATION OF FLEXIBLE BURIED PIPE DEFORMATION BEHAVIOR UNDER VARIOUS BACKFILL CONDITIONS

    Directory of Open Access Journals (Sweden)

    Niyazi Uğur TERZİ

    2009-01-01

    Full Text Available Deformation characteristics of polyethylene based flexible pipes are different than rigid pipes such as concrete and iron pipes. Deflection patterns and stress-strain behaviors of flexible pipes have strict relation between the engineering properties of backfill and its settlement method. In this study, deformation behavior of a 100 mm HDPE flexible pipe under vertical loads is investigated in laboratory conditions. Steel test box, pressurized membrane, raining system, linear position transducers and strain gauge rosettes are used in the laboratory tests. In order to analyze the buried pipe performance; Masada Derivation Formula which is mostly used by designers is employed. According to the test and mathematical studies, it is understood that relative density of backfill and its settlement method is a considerable effect on buried pipe performance and Masada Derivation method is very efficient for predicting the pipe performance.

  8. Study on the properties of Gaomiaozi bentonite as the buffer/backfilling materials for HLW disposal

    International Nuclear Information System (INIS)

    Liu Xiaodong; Luo Taian; Zhu Guoping; Chen Qingchun

    2007-12-01

    Systematic studies including mineral composition and structure, physico- chemical properties and thermal properties have been conducted on Gaomiaozi bentonite, Xinghe County, Inner Mongolia Autonomous Region. The compaction characteristics of bentonite and the influence of additive to bentonite have been discussed. The analysis of mineral composition and structure show that the bentonite ores are dominated by montmorillonite. Preliminary studies of the characteristics of ores indicated that No-type bentonite from the deposit has good absorption, excellent swelling and high cation exchangeability. The compressibility of bentonite will be improved by adding the additives such as quartz sand. The studies indicated that the characteristics of Gaomiaozi bentonite can satisfy the requirement of buffer/backfilling materials for HLW repository and the ores can be selected as the preferential candidate to provide buffer/backfill- ing materials for HLW repository in China. (authors)

  9. The chemistry of blended cements and backfills intended for use in radioactive waste disposal

    International Nuclear Information System (INIS)

    Glasser, F.; Tyrer, M.; Quillin, K.

    1999-01-01

    This project was initiated by Her Majesty's Inspectorate of Pollution (HMIP) at the time when UK NIREX had announced its intention to develop a repository for low and intermediate level nuclear waste in the vicinity of Sellafield. In this repository setting, two main barriers existed to the return of radio-isotopes to the biosphere: the natural, or geologic and hydrogeologic barriers, and the man-made barriers. These latter comprise relatively short-lived containers as well as an engineered backfill. The backfill was designed to condition a high pH in the repository, thereby lowering the solubility of many long-lived radionuclides yet not confine gases, which might be generated from chemical and radioactive waste within the repository vault. The Environment Agency for England and Wales had already taken independent steps to examine the suitability of alkaline backfills, based on Portland cement, limestone flour and Ca(OH) 2 , for the man-made barriers. Preliminary data on post-closure repository performance assessment at Sellafield suggested the importance of two additional factors which had not hitherto been considered in assessments: (i) temperature: Inclusion of heat generating waste could drive temperatures up to ∼80 deg. C in the post closure phase; (ii) salinity of deep groundwater: Much previous work has been done in initially-pure water but borehole analyses indicated high salinity at depth. Other potential deep repositories could also be saline. These impacts were likely to occur together throughout much of the post-closure phase: backfills were likely to be in prolonged contact with hot, saline groundwater. Previous studies demonstrated that cements achieve their performance by a sacrificial action. It is however essential that the cementitious materials should not dissolve too rapidly if prolonged backfill performance lifetimes are to be achieved. By dissolving cement backfills condition permeating water to a high pH and thereby lower the solubilities

  10. Study on the properties of Gaomiaozi bentonite as the buffer/backfilling materials for HLW disposal

    Energy Technology Data Exchange (ETDEWEB)

    Xiaodong, Liu [East China Inst. of Technology, Fuzhou (China); [Key Laboratory of Nuclear Resources and Environment of Ministry of Education, Fuzhou (China); Taian, Luo; Guoping, Zhu; Qingchun, Chen [East China Inst. of Technology, Fuzhou (China)

    2007-12-15

    Systematic studies including mineral composition and structure, physico- chemical properties and thermal properties have been conducted on Gaomiaozi bentonite, Xinghe County, Inner Mongolia Autonomous Region. The compaction characteristics of bentonite and the influence of additive to bentonite have been discussed. The analysis of mineral composition and structure show that the bentonite ores are dominated by montmorillonite. Preliminary studies of the characteristics of ores indicated that No-type bentonite from the deposit has good absorption, excellent swelling and high cation exchangeability. The compressibility of bentonite will be improved by adding the additives such as quartz sand. The studies indicated that the characteristics of Gaomiaozi bentonite can satisfy the requirement of buffer/backfilling materials for HLW repository and the ores can be selected as the preferential candidate to provide buffer/backfill- ing materials for HLW repository in China. (authors)

  11. Current status of preparing buffer/backfill block in HLW disposal abroad

    International Nuclear Information System (INIS)

    Yan Ming; Wang Xuewen; Zhang Huyuan

    2014-01-01

    There is an urgent need for China to commence the full-scale compaction test, resolving the preparation problem for buffer/backfill blocks when underground research laboratory project is planned for High Level Radioactive Waste (HLW) disposal. The foreign countries have some research about the preparation of buffer/backfill blocks in engineered barrier systems. The foreign research shows that installation of clay blocks with sector shape at waste pollution area is a feasible engineering method. Compacted clay blocks need to be cured in a cabinet with controlled temperature and humidity to avoid desiccation and surface powdering. A freeze mixing method, mixing powdered-ice and cooled bentonite, can be operated more easily and obtain more uniform hydration than the traditional mixing of water and bentonite. It is helpful to review and adsorb the foreign research results for the design of full-scale test of bentonite compaction. (authors)

  12. The simplified convergence rate calculation for salt grit backfilled caverns in rock salt

    International Nuclear Information System (INIS)

    Navarro, Martin

    2013-03-01

    Within the research and development project 3609R03210 of the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, different methods were investigated, which are used for the simplified calculation of convergence rates for mining cavities in salt rock that have been backfilled with crushed salt. The work concentrates on the approach of Stelte and on further developments based on this approach. The work focuses on the physical background of the approaches. Model specific limitations are discussed and possibilities for further development are pointed out. Further on, an alternative approach is presented, which implements independent material laws for the convergence of the mining cavity and the compaction of the crushed salt backfill.

  13. Stress Ratios in Entire Mine Stopes with Cohesionless Backfill: A Numerical Study

    Directory of Open Access Journals (Sweden)

    Pengyu Yang

    2017-10-01

    Full Text Available Evaluation of stress states in backfilled mine stopes (or similar openings, using arching theory, can be largely impacted by the value selected for the earth pressure coefficient, K = σ′h/σ′v. Recently, the current study’s authors addressed the debate about the value of K near the opening center, based on Rankine’s active coefficient (Ka and at-rest coefficient (K0. Here, stress ratios in vertical backfilled stopes are numerically assessed (in two dimension, 2D, considering both the independent and related backfill internal friction angle (ϕ′ and Poisson’s ratio (ν. Emphasis is placed on the backfill state near stope walls, where local rotation of stresses occurs, so the coefficient (K and principal stress ratio, Kps (= σ′3/σ′1, should be distinguished. Parametric analyses indicate that values of K and Kps depend on the position and the relationship between ϕ′ and ν. Near the opening center, K (= Kps is close to Ka when ν or ϕ′ is below a critical value; otherwise the value approaches K0, defined from ν. Near both walls, Kps is always close to Ka, while K is near K0 for related ν − ϕ′ cases and depends on their respective values for independent ν and ϕ′. Additional simulations conducted with interface elements indicate that the stress ratios near the opening center line are insensitive to interface roughness and are almost identical to values obtained without interfaces, but the stress ratios near walls may change for less rough or smooth interfaces.

  14. Active Thrust on an Inclined Retaining Wall with Inclined Cohesionless Backfill due to Surcharge Effect

    OpenAIRE

    Dewaikar, D. M.; Pandey, S. R.; Dixit, Jagabandhu

    2012-01-01

    A method based on the application of Kötter’s equation is proposed for the complete analysis of active thrust on an inclined wall with inclined cohesionless backfill under surcharge effect. Coulomb’s failure mechanism is considered in the analysis. The point of application of active thrust is determined from the condition of moment equilibrium. The coefficient of active pressure and the point of application of the active thrust are computed and presented in nondimensional form. One distinguis...

  15. Solubility constraints affecting the migration of selenium through the cementitious backfill of a geological disposal facility

    Energy Technology Data Exchange (ETDEWEB)

    Felipe-Sotelo, M., E-mail: m.felipe-sotelo@lboro.ac.uk; Hinchliff, J.; Evans, N.D.M.; Read, D.

    2016-03-15

    Highlights: • The availability of Ca controls the concentration of SeO{sub 3}{sup 2−} in solution. • Cellulose degradation products increase the solubility of SeO{sub 3}{sup 2−} at alkaline pH. • Selenite diffuses faster through the backfill NRVB than through fly ash cements. - Abstract: This work presents the study of the solubility of selenium under cementitious conditions and its diffusion, as SeO{sub 3}{sup 2−}, through monolithic cement samples. The solubility studies were carried out under alkaline conditions similar to those anticipated in the near-field of a cement-based repository for low- and intermediate-level radioactive waste. Experiments were conducted in NaOH solution, 95%-saturated Ca(OH){sub 2}, water equilibrated with a potential backfill material (Nirex reference vault backfill, NRVB) and in solutions containing cellulose degradation products, with and without reducing agents. The highest selenium concentrations were found in NaOH solution. In the calcium-containing solutions, analysis of the precipitates suggests that the solubility controlling phase is Ca{sub 2}SeO{sub 3}(OH){sub 2}·2H{sub 2}O, which appears as euhedral rhombic crystals. The presence of cellulose degradation products caused an increase in selenium concentration, possibly due to competitive complexation, thereby, limiting the amount of calcium available for precipitation. Iron coupons had a minor effect on selenium solubility in contrast to Na{sub 2}S{sub 2}O{sub 4}, suggesting that effective reduction of Se(IV) occurs only at E{sub h} values below −300 mV. Radial through-diffusion experiments on NRVB and in a fly ash cement showed no evidence of selenium breakthrough after one year. However, autoradiography of the exposed surfaces indicated that some migration had occurred and that selenium was more mobile in the higher porosity backfill than in the fly ash cement.

  16. Backfilling and sealing of repositories and access shafts and galleries in clay, granite and salt formations

    International Nuclear Information System (INIS)

    Lake, L.M.; Davies, I.L.; Gera, F.; Jorda, M.; McEwen, T.; Neerdael, B.; Schmidt, M.W.

    1985-01-01

    The paper summarizes the work carried out under ten Commission contracts in the field of backfilling and sealing radioactive waste repositories. It covers theoretical, laboratory and field trials and experiments involving three potential host types, namely clay, salt and hard rock. It concludes that maximum opportunity should be taken over the next 15 to 25 years with a view to obtaining first hand experience in real ground with real wastes

  17. Field and laboratory investigations on pavement backfilling material for micro-trenching in cold regions

    OpenAIRE

    Leila Hashemian; Mohammad Rezaei; Alireza Bayat

    2017-01-01

    Micro-trenching is an innovative utility installation method that involves creating a narrow trench to place cable or conduit in the road pavement. Compared to other installation methods, micro-trenching provides minimal disturbance to the community and surrounding environment. Despite the advantages of micro-trenching, it is not widely accepted by municipalities because of its potential to damage the existing pavement. Quality of backfilling is an important factor in long-term sustainability...

  18. Paste backfill of shallow mine workings for land reclamation in Canmore, Alberta

    International Nuclear Information System (INIS)

    Predika, R.; Beattie, A.; Beddoes, R.

    2008-01-01

    The coal mining history in Canmore, Alberta was presented along with reclamation activities that mine regulators carried out following closure of the mines after nearly 100 years of underground mining. The 7 seams that were mined commercially extend over distances of a few hundred feet and have been displaced by faults. Voids and collapsed rubble in shallow underground workings pose a risk of potential ground subsidence that can affect the stability of surface structures and infrastructure, including the planned development of the proposed Three Sisters Mountain Village on land above the abandoned mines. The village includes plans for 10,000 residential homes, 2 golf courses, and a resource centre. A mine works mitigation program involved drilling primary injection boreholes on a 15 m grid pattern to map the constraint zones in order to gain a better perspective of the subsidence issues as well as the effects of subsidence on structural stress and public safety. When determining mitigation criteria, various land uses and ranges of subsidence hazards were considered to be compatible with each land use. A paste backfill composed of aggregate from a locally available till overburden site was mixed with cement and injected into the void spaces. This paper described the cemented paste backfill injection method; confirmatory methods; maximum volume and pressure criteria; survey for ground uplift; and borehole camera and manual checks for cemented paste backfill in adjacent boreholes. Quality control testing was carried out by means of slump tests. It was concluded that cemented paste backfill mix could be used successfully to stabilize abandoned mine workings for land recovery. 8 refs., 5 tabs., 7 figs

  19. BENTONITE-QUARTZ SAND AS THE BACKFILL MATERIALS ON THE RADIOACTIVE WASTE REPOSITORY

    Directory of Open Access Journals (Sweden)

    Raharjo Raharjo

    2010-06-01

    Full Text Available An investigation of the contribution of quartz sand in the bentonite mixture as the backfill materials on the shallow land burial of radioactive waste has been done. The experiment objective is to determine the effect of quartz sand in a bentonite mixture with bentonite particle sizes of -20+40, -40+60, and -60+80 mesh on the retardation factor and the uranium dispersion in the simulation of uranium migration in the backfill materials. The experiment was carried out by the fixed bed method in the column filled by the bentonite mixture with a bentonite-to-quartz sand weight percent ratio of 0/100, 25/75, 50/50, 75/25, and 100/0 on the water saturated condition flown by uranyl nitrate solution at concentration (Co of 500 ppm. The concentration of uranium in the effluents in interval 15 minutes represented as Ct was analyzed by spectrophotometer, then using Co and Ct, retardation factor (R and dispersivity ( were determined. The experiment data showed that the bentonite of -60+80 mesh and the quartz sand of -20+40 mesh on bentonite-to-quartz sand with weight percent ratio of 50/50 gave the highest retardation factor and dispersivity of 18.37 and 0.0363 cm, respectively.   Keywords: bentonite, quartz sand, backfill materials, radioactive waste

  20. Hydraulic properties of buffer and backfill materials for high-level nuclear waste disposal

    International Nuclear Information System (INIS)

    Komine, Hideo; Ogata, Nobuhide

    2001-01-01

    The design and development of buffer and backfill materials, which fill up the disposal facility, are important for developing the technology of high-level nuclear wastes disposal. The compacted bentonite and sand-bentonite mixture are attracting greater attention as buffer and backfill materials because they have impermeable and swelling properties. This study investigated the hydraulic-conductivities at the different sand-bentonite mass ratio and dry density, which are the specifications of material, by the experimental works. This study also obtained the experimental data of hydraulic conductivities of the materials for 120 days at the farthest, and the permeability changes before and after swelling. Furthermore, this study proposed the evaluation method for hydraulic conductivity using the parameter 'Swelling volumetric strain of montmorillonite', which was proposed by the author. The evaluation method can obtain the hydraulic conductivity of buffer and backfill materials at various dry densities and bentonite contents. Therefore, the evaluation method can be used for designing the bentonite content and compaction density from the viewpoint of 'impermeability'. (author)

  1. Use of inorganic sorbents for treatment of liquid radioactive waste and backfill of underground repositories

    International Nuclear Information System (INIS)

    1992-11-01

    This document presents the results of a four year Co-ordinated Research Programme (CRP) on the ''Use of Inorganic Sorbents for Treatment of Liquid Radioactive Waste and Backfill of Underground Repositories'' (1987-1991). Many countries have research programmes aiming at developing processes which would provide efficient and safe concentration of radionuclides in waste streams into solid materials which could then be reliably immobilized into forms suitable for long term storage or disposal. Use of inorganic sorbents for this purpose is very attractive because of their resistance to radiation and chemical attack, strong affinity for one or more radionuclides, their compatibility with likely immobilization matrices and their availability at low cost. According to the fundamental multibarrier concept for disposal of radioactive waste, backfill material is one of the important engineered barriers. Inorganic materials such as clays, naturally occurring zeolites (clinoptilolite, modenite and chabasite) are promising backfill materials. Research in technical uses of inorganic material applications was covered within the framework of the Co-ordinated Research Programme reported in this technical document. Final contributions by participants at the last Research Co-ordination Meeting held in Rez, Czechoslovakia, from 4 to 8 November 1991, are presented here. Refs, figs and tabs

  2. A mathematical model of the behaviour of concrete backfill in an underground radioactive-waste repository

    International Nuclear Information System (INIS)

    Mistry, N.S.; Carlton, D.; Storer, G.

    1992-01-01

    This report concerns the mathematical modelling by the finite element method of the behaviour of concrete, one of the candidate materials for use in the backfilling and scaling of underground repositories for radioactive waste. In order to act as an assured physical barrier to ground water migration in the vicinity of the waste packages, a concrete backfill must remain intact and free from cracks. One of the risk periods during which mass concrete is susceptible to cracking is during the early days after casting when concrete undergoes rapid changes in internal temperatures and mechanical properties, including, most obviously, strength. Existing commercially available finite element codes do not have a model for concrete that can adequately represent these early age characteristics. The present study, therefore, is predominantly concerned with the development of a mathematical model for use within the ADINA finite element code to predict the time-dependent performance of concrete as a backfilling and sealing material. The evaluation of creep and shrinkage strains is based on the CEB-FIP Model Code together with Illston's approach to delayed and transitional thermal strains. The finite element material model developed is general and could be applied to various types of structure and loading. The model accounts for the ageing of concrete, multi-axial creep and creep recovery, the effect of external environmental humidity and changing internal temperatures. 32 refs., 31 figs., 1 tab

  3. Experimental investigation of the long term dissolution properties of a cement-based vault backfill

    International Nuclear Information System (INIS)

    Butcher, E.J.; Borwick, J.; Thorburn, A.A.; Williams, S.J.

    2012-01-01

    One concept for the long-term management of packages of intermediate-level radioactive waste (ILW) is to place them in underground vaults in a Geological Disposal Facility (GDF). After the packaged waste is placed in the vault it is planned to fill the space around the waste packages with a cement-based backfill prior to closure of the facility. The currently specified backfill is the NRVB (Nirex Reference Vault Backfill), composed of a blend of Portland cement, limestone flour and hydrated lime. Leaching trials are ongoing at the UK National Nuclear Laboratory (NNL) to investigate the dissolution of NRVB until pH values typical of calcium carbonate are achieved. The objective of this work is to determine the buffering capacity of samples of the NRVB, and to allow the sequential release of the alkalinity from the intact samples to be monitored. Leaching is being performed utilising three leachants: deionised water and two saline solutions. Trials have been performed in duplicate for each leachant to allow an initial assessment to be made of the reproducibility of the data produced. In order to simulate the conditions expected in the GDF the approach being used in the trials is a flow through experiment utilising a flexible wall permeameter, within a 35 deg temperature-controlled cell

  4. Use of Cemented Super-Fine Unclassified Tailings Backfill for Control of Subsidence

    Directory of Open Access Journals (Sweden)

    Lei Yang

    2017-11-01

    Full Text Available Known for its advantages in preventing geological and environmental hazards, cemented paste backfill (CPB has become a topic of interest for scientists and mining engineers in recent decades. This paper presents the results of a study on the use of cemented super-fine tailings backfill (CSUTB in an underground mine for control of surface subsidence. An analytical solution is developed based on the available model to calculate the required strength of backfill when in contact with non-cemented tailings (NCT. The effect of solid contents on the rheological properties of CSUTB is investigated. A reasonable mix proportion (RMP of CSUTB is determined for Zhongguan Iron Mine (ZGIM based on laboratory experiments. The validity of RMP in surface subsidence control is verified by a 3D numerical model. The obtained results show that CSUTB requires higher strength when in contact with NCT than when in contact with orebody. Rheological characteristics, e.g., slump, fluidity, and bleeding rate of fresh CSUTB, decrease with higher solids content, of which values with a certain solids content can be determined by quadratic polynomial regression equations. RMP with a cement to tailings (c/t ratio of 1:10 and a solids content of 70% is recommended for ZGIM, as it shows favorable mechanical and rheological abilities. The deformation parameters (curvature, inclination, and horizontal deformation rate obtained from numerical modeling are acceptable and lower than critical values, meaning CSUTB can feasibly be used with RMP in subsidence control.

  5. Performance of concrete backfilling materials for shafts and tunnels in rock formations

    International Nuclear Information System (INIS)

    Storer, G.; Mistry, N.; Galliara, J.

    1985-10-01

    This report (Part 2) describes the mathematical modelling studies carried out within a research project into the performance of concrete backfilling materials for shafts and tunnels comprising a hard rock geological disposal repository for High Level, Heat Generating Wastes (HLW/HGW) or Intermediate Level Wastes (ILW) with long lived isotopes. A complementary volume (Part 1) describes laboratory research studies into the development, manufacture and testing of a pre-placed aggregate concrete (PAC). The ongoing objective is to demonstrate that concrete will serve as a beneficial engineered barrier, part of a multi-barrier system, in isolating potentially harmful radionuclides from the biosphere. The report recognises that the backfill cannot be considered in isolation and that there are many interactions between the primary repository elements of host rock, waste and backfill. The interactions considered include mechanical, thermal, creep and moisture movement. Analyses were carried out using the ADINA finite element system, by programmed analytical formulae and using the TEMPOR program (for thermally driven moisture migration in concrete). The emphasis has been directed at establishing basic mathematical approaches to the understanding and quantification of the phenomena involved and applying them to simplified and idealised repository scenarios. The methods devised lay foundations for future work on more defined disposal scenarios. (author)

  6. DUSCOBS - a depleted-uranium silicate backfill for transport, storage, and disposal of spent nuclear fuel

    International Nuclear Information System (INIS)

    Forsberg, C.W.; Pope, R.B.; Ashline, R.C.; DeHart, M.D.; Childs, K.W.; Tang, J.S.

    1995-01-01

    A Depleted Uranium Silicate COntainer Backfill System (DUSCOBS) is proposed that would use small, isotopically-depleted uranium silicate glass beads as a backfill material inside storage, transport, and repository waste packages containing spent nuclear fuel (SNF). The uranium silicate glass beads would fill all void space inside the package including the coolant channels inside SNF assemblies. Based on preliminary analysis, the following benefits have been identified. DUSCOBS improves repository waste package performance by three mechanisms. First, it reduces the radionuclide releases from SNF when water enters the waste package by creating a local uranium silicate saturated groundwater environment that suppresses (1) the dissolution and/or transformation of uranium dioxide fuel pellets and, hence, (2) the release of radionuclides incorporated into the SNF pellets. Second, the potential for long-term nuclear criticality is reduced by isotopic exchange of enriched uranium in SNF with the depleted uranium (DU) in the glass. Third, the backfill reduces radiation interactions between SNF and the local environment (package and local geology) and thus reduces generation of hydrogen, acids, and other chemicals that degrade the waste package system. In addition, the DUSCOBS improves the integrity of the package by acting as a packing material and ensures criticality control for the package during SNF storage and transport. Finally, DUSCOBS provides a potential method to dispose of significant quantities of excess DU from uranium enrichment plants at potential economic savings. DUSCOBS is a new concept. Consequently, the concept has not been optimized or demonstrated in laboratory experiments

  7. Water uptake by and movement through a Backfilled KBS-3V deposition tunnel: results of large-scale simulations

    International Nuclear Information System (INIS)

    Dixon, D.A.; Ramqvist, G.; Jonsson, E.; Gunnarsson, D.; Hansen, J.

    2010-01-01

    Document available in extended abstract form only. Posiva and SKB initiated a joint programme BACLO (Backfilling and Closure of the Deep repository) in 2003 with the aim to develop methods and clay-based materials for backfilling the deposition tunnels of a repository utilizing the KBS-3V deposition concept. This paper summarises the results obtained in intermediate and large-scale simulations to evaluate water movement into and through backfill consisting of bentonite pellets and pre-compacted clay blocks. The main objectives of Baclo Phase III were related to examining backfill materials, deposition concepts and their importance to the clay-block and pellet backfilling concept. Bench-scale studies produced a large body of information on how various processes (e.g. water inflow, piping, erosion, self-healing, homogenisation and interaction between backfill and buffer), might affect the hydro-mechanical evolution of backfill components. The tests described in this paper examined the movement of water into and through assemblies of clay blocks and bentonite pellets/granules and represent a substantial up-scaling and inclusion of parameters that more closely simulate a field situation. In total, 27 intermediate-scale tests have been completed and 18 large-scale tests (∼ 1/2-tunnel cross-section) will be completed at SKB's Aespoe HRL by mid 2010. At intermediate-scale, point inflow rates ranging from 0.01 to 1.0 l/min were applied to block - dry pellet assemblies and water movement into and through the system was monitored. Tests determined that it is critical to provide clay blocks with lateral support and confinement as quickly as possible following block installation. Exposure of the blocks to even low rates of water ingress can result in rapid loss of block cohesion and subsequent slumping of the block materials into the spaces between the blocks and the tunnel walls. Installation of granular or pelletized bentonite clay between the blocks and the walls

  8. Properties of Shredded Roof Membrane–Sand Mixture and Its Application as Retaining Wall Backfill under Static and Earthquake Loads

    Directory of Open Access Journals (Sweden)

    Bennett Livingston

    2017-04-01

    Full Text Available About 20 billion square feet of Ethylene Propylene Diene Monomer (EPDM rubber is installed on roofs in the United States and most of them will be reaching the end of their lifespan soon. The purpose of this study is to investigate potential reuses of this rubber in Civil Engineering projects rather than disposing it into landfills. First, laboratory tests were performed on various shredded rubber-sand mixtures to quantify the basic geotechnical engineering properties. The laboratory test results show that the shredded rubber-sand mixture is lightweight with good drainage properties and has shear strength parameters comparable to sand. This indicates that the rubber-sand mixture has potential to be used for retaining wall backfill and many other projects. To assess the economic advantage of using shredded rubber-sand mixtures as a lightweight backfill for retaining walls subjected to static and earthquake loadings, geotechnical designs of a 6 m tall gravity cantilever retaining wall were performed. The computed volume of concrete to build the structural components and volume of backfill material were compared with those of conventional sand backfill. Results show significant reductions in the volume of concrete and backfill material in both static and earthquake loading conditions when the portion of shredded rubber increased in the mixture.

  9. Analysis on Filling Ratio and Shield Supporting Pressure for Overburden Movement Control in Coal Mining with Compacted Backfilling

    Directory of Open Access Journals (Sweden)

    Yanli Huang

    2016-12-01

    Full Text Available Since the weight of overburden is sustained by both the backfill body and the unmined solid coal in coal mining with compacted backfilling (CMCB panels, the stress and deformation characteristics of the surrounding rocks in coal mining are radically changed. The overburden movement control mechanism by coordinating with backfill body and shield in CMCB was studied systematically in this paper. Based on the analysis of deformational and structural characteristics of surrounding rock in CMCB panels, the methods of theoretical analysis, numerical simulation and engineering test are employed. The results show that the fracture of the main roof is mainly controlled by the filling ratio φ and is non-correlated to the shield supporting pressure p. However, p has a significant control effect on the deflection of roof within the shield canopy length, and adversely affects the filling ratio. With the increase of the filling ratio of the gob, the maximum sagging of the immediate and the main roofs, the peak front and the influence range of the abutment pressures are gradually reduced. Correspondingly, the stable period of internal pressure of backfill body in the gob is shortened. Engineering practice shows that the sagging of the gob roof, the distribution of the abutment pressure, the distribution of the internal pressure in the backfill body, and the ground surface sagging results obtained by the in-situ measurement are approximately corresponding to the theoretical analysis and numerical simulation results.

  10. Sorption of cesium and strontium from concentrated brines by backfill barrier materials

    International Nuclear Information System (INIS)

    Winslow, C.D.

    1981-03-01

    The sorption of radionuclides from potentially intruding groundwater at a nuclear waste repository is a major chemical function of backfill barriers. In this study, various materials (including clays, zeolites and an inorganic ion exchanger) were screened for the sorption of the fission products cesium and strontium in concentrated brines. Representative brines A and B for the Waste Isolation Pilot Plant (WIPP), a proposed radioactive waste repository and test facility in bedded salt were used. Sorption properties were quantified using empirical distribution coefficients, k/sub d/. Of the materials examined, sodium titanate had the highest k/sub d/ for the sorption of Sr(II) in both brine A (k/sub d/ = 125 ml/g) and brine B(k/sub d/ = 500 to 600 ml/g). A mordenite-type zeolite was the most effective getter for Cs(I) in brine A (k/sub d = 27 ml/g), while illite yielded the highest k/sub d/ for Cs(I) in brine B (k/sub d/ = 115 ml/g). The relative merit of these k/sub d/ values is evaluated in terms of calculated estimates of breakthrough times for a backfill barrier containing the getter. Results show that a backfill mixture containing these getters is potentially an effective barrier to the migration of Sr(II) and Cs(I), although further study (especially for the sorption of cesium from brine A) is recommended. Initial mechanistic studies revealed competing ion effects which would support an ion exchange mechanism. K/sub d/'s were constant over a Sr(II) concentration range of 10 -11 to 10 -5 M and a Cs(I) concentration range of 10 -8 to 10 -5 M, supporting the choice of a linear sorption isotherm as a model for the results. Constant batch composition was shown to be attained within one week

  11. Backfilling with mixtures of bentonite/ballast materials or natural smectitic clay?

    International Nuclear Information System (INIS)

    Pusch, R.

    1998-10-01

    Comparison of the performance of backfills of mixed MX-80 and crushed rock ballast, and a natural smectitic clay, represented by the German Friedland clay, shows that the latter performs better than mixtures with up to 30 % MX-80. Considering cost, Friedland clay prepared to yield air-dry powder grains is cheaper than mixtures of 30 % MX-80 and crushed ballast. Both technically and economically it appears that the Friedland clay is a competitive alternative to mixtures of 30 % MX-80 and crushed ballast. However, it remains to be demonstrated on a full scale that Friedland clay ground to a suitable grain size distribution can be acceptably compacted on site

  12. Failure of MPC overpack and inner container under corrosion and mechanical stresses in a backfilled drift

    International Nuclear Information System (INIS)

    Ladkany, S.G.; Rajagopalan, R.

    1995-01-01

    The thickness and time at failure of the 100mm thick overpack and the 9.5mm thick inner container of a Multi-purpose canister have been assessed due to loads resulting from temperature, overburden, backfill pressure and seismic loads. Critical stresses at various reduced thicknesses, resulting from pitting corrosion over the years of emplacement, have been evaluated using Finite element analysis. Both simple and continuous support conditions of the overpack have been considered in the analysis. The anticipated failure time due to corrosion of overpack and inner container is further reduced due to overburden, self and seismic loads

  13. BEHAVIOUR OF BACKFILL MATERIALS FOR ELECTRICAL GROUNDING SYSTEMS UNDER HIGH VOLTAGE CONDITIONS

    Directory of Open Access Journals (Sweden)

    S. C. LIM

    2015-06-01

    Full Text Available Backfill materials like Bentonite and cement are effective in lowering grounding resistance of electrodes for a considerable period. During lightning, switching impulses and earth fault occurrences in medium and high voltage networks, the grounding system needs to handle extremely high currents either for a short duration or prolonged period respectively. This paper investigates the behaviour of bentonite, cement and sand under impulse and alternating high voltage (50Hz conditions. Fulguritic-formation was observed in all materials under alternating high voltage. The findings reveal that performance of grounding systems under high voltage conditions may significantly change from the outcomes anticipated at design stage.

  14. Deep repository - Engineered barrier system. Erosion and sealing processes in tunnel backfill materials investigated in laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Sanden, Torbjoern; Boergesson, Lennart; Dueck, Ann; Goudarzi, Reza; Loennqvist, Margareta (Clay Technology AB, Lund (Sweden))

    2008-12-15

    SKB in Sweden and Posiva in Finland are developing and plan to implement similar disposal concepts for the final disposal of spent nuclear fuel. Co-operation and joint development work between Posiva and SKB with the overall objective to develop backfill concepts and techniques for sealing and closure of the repository have been going on for several years. The investigation described in this report is intended to acquire more knowledge regarding the behavior of some of the candidate backfilling materials. Blocks made of three different materials (Friedland clay, Asha 230 or a bentonite/ballast 30/70 mixture) as well as different bentonite pellets have been examined. The backfill materials will be exposed to an environment simulating that in a tunnel, with high relative humidity and water inflow from the rock. The processes and properties investigated are: 1. Erosion properties of blocks and pellets (Friedland blocks, MX-80 pellets, Cebogel QSE pellets, Minelco and Friedland granules). 2. Displacements of blocks after emplacement in a deposition drift (Blocks of Friedland, Asha 230 and Mixture 30/70). 3. The ability of these materials to seal a leaking in-situ cast plug cement/rock but also other fractures in the rock (MX-80 pellets). 4. The self healing ability after a piping scenario (Blocks of Friedland, Asha 230 Mixture 30/70 and also MX-80 pellets). 5. Swelling and cracking of the compacted backfill blocks caused by relative humidity. The erosion properties of Friedland blocks were also investigated in Phase 2 of the joint SKBPosiva project 'Backfilling and Closure of the Deep Repository, BACLO, which included laboratory scale experiments. In this phase of the project (3) some completing tests were performed with new blocks produced for different field tests. These blocks had a lower density than intended and this has an influence on the erosion properties measured. The erosion properties of MX-80 pellets were also investigated earlier in the project but

  15. Retardation of uranium and thorium by a cementitious backfill developed for radioactive waste disposal.

    Science.gov (United States)

    Felipe-Sotelo, M; Hinchliff, J; Field, L P; Milodowski, A E; Preedy, O; Read, D

    2017-07-01

    The solubility of uranium and thorium has been measured under the conditions anticipated in a cementitious, geological disposal facility for low and intermediate level radioactive waste. Similar solubilities were obtained for thorium in all media, comprising NaOH, Ca(OH) 2 and water equilibrated with a cement designed as repository backfill (NRVB, Nirex Reference Vault Backfill). In contrast, the solubility of U(VI) was one order of magnitude higher in NaOH than in the remaining solutions. The presence of cellulose degradation products (CDP) results in a comparable solubility increase for both elements. Extended X-ray Absorption Fine Structure (EXAFS) data suggest that the solubility-limiting phase for uranium corresponds to a becquerelite-type solid whereas thermodynamic modelling predicts a poorly crystalline, hydrated calcium uranate phase. The solubility-limiting phase for thorium was ThO 2 of intermediate crystallinity. No breakthrough of either uranium or thorium was observed in diffusion experiments involving NRVB after three years. Nevertheless, backscattering electron microscopy and microfocus X-ray fluorescence confirmed that uranium had penetrated about 40 μm into the cement, implying active diffusion governed by slow dissolution-precipitation kinetics. Precise identification of the uranium solid proved difficult, displaying characteristics of both calcium uranate and becquerelite. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Initial field testing definition of subsurface sealing and backfilling tests in unsaturated tuff

    International Nuclear Information System (INIS)

    Fernandez, J.A.; Case, J.B.; Tyburski, J.R.

    1993-05-01

    This report contains an initial definition of the field tests proposed for the Yucca Mountain Project repository sealing program. The tests are intended to resolve various performance and emplacement concerns. Examples of concerns to be addressed include achieving selected hydrologic and structural requirements for seals, removing portions of the shaft liner, excavating keyways, emplacing cementitious and earthen seals, reducing the impact of fines on the hydraulic conductivity of fractures, efficient grouting of fracture zones, sealing of exploratory boreholes, and controlling the flow of water by using engineered designs. Ten discrete tests are proposed to address these and other concerns. These tests are divided into two groups: Seal component tests and performance confirmation tests. The seal component tests are thorough small-scale in situ tests, the intermediate-scale borehole seal tests, the fracture grouting tests, the surface backfill tests, and the grouted rock mass tests. The seal system tests are the seepage control tests, the backfill tests, the bulkhead test in the Calico Hills unit, the large-scale shaft seal and shaft fill tests, and the remote borehole sealing tests. The tests are proposed to be performed in six discrete areas, including welded and non-welded environments, primarily located outside the potential repository area. The final selection of sealing tests will depend on the nature of the geologic and hydrologic conditions encountered during the development of the Exploratory Studies Facility and detailed numerical analyses. Tests are likely to be performed both before and after License Application

  17. Evaluation of a new method to estimate the hydration time of the tunnel backfill

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Urban (Computer-aided Fluid Engineering AB, Lyckeby (Sweden))

    2010-12-15

    A safety assessment of a repository requires that all stages (excavation, waste emplacement, etc) of a repository are analysed and understood. In this report the time after the waste emplacement will be in focus. One important issue during this phase is the saturation of the tunnel backfill. After the installation of the backfill, 30-50% of the pore space is filled with air; this volume will eventually be filled with water and it is the time scale for this hydration process that needs to be estimated. A method to estimate the hydration time of a repository has been suggested and evaluated. The key idea in the suggested method is to 'create' the volume initially filled with air by the use of the specific storage term and hence be able to stay within the single phase framework. A series of test cases, defined and simulated in /Boergesson et al. 2006/, are used to demonstrate and evaluate the method. Encouraging results have been obtained. It is also shown that the simulation model can be applied to a real world case

  18. The Buffer and Backfill Handbook. Part 3: Models for calculation of processes and behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Pusch, Roland [Geodevelopment AB, Lund (Sweden)

    2003-01-15

    The present document collects conceptual and mathematical models that have been proposed for describing the performance of buffers and backfills and processes in them that are related to their function under repository conditions. As in the preceding parts the following types of sealing components are defined. By definition, the buffer shall be so composed that radionuclide transport in the clay-based barriers takes place by diffusion and not by water flow, which makes it important to predict the extent and rate of diffusive transport of such elements through the buffer. It depends strongly on the density and homogeneity of the buffer, which in turn depend on the maturation rate and the ultimate degree of homogeneity of the buffer. They are influenced by the temperature and temperature gradient that exist in the initial phase of water saturation, in which the hydraulic interaction with the near field rock is also important. Design of suitable buffer and backfills hence requires that their performance can be quantified, which requires that the various processes can be modeled conceptually and expressed in mathematical form. Based on the present knowledge this can only be made for some of the involved mechanisms and for coupled processes there is still a very limited number of mathematically expressed computational codes. The models referred to here are conceptual in the first place, defining the respective processes and material property parameters. The quick development of computational tools, numerical as well as analytical, makes it irrelevant to give detailed descriptions of them, while the various assumptions on which they are based - especially the conceptual models - have been considered in some detail. The models of practical use are only described in general terms and examples at the end of the respective chapter illustrate how they can be utilized. A very important fact is that transport and rheological processes in a repository are hardly ever of simple

  19. Remaining porosity and permeability of compacted crushed rock salt backfill in a HLW repository. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Jobmann, M.; Mueller, C.; Schirmer, S.

    2015-11-15

    The safe containment of radioactive waste is to be ensured by the geotechnical barriers in combination with the containment-providing rock zone (CRZ). The latter is a key element of the recently developed concept of demonstrating the integrity of the geologic barrier (Krone et al., 2013). As stipulated in the safety requirements of the regulating body the CRZ has to have strong barrier properties, and evidence needs to be provided that it retains its integrity throughout the reference period (BMU, 2010). The underground openings excavated in the rock salt will close over time due to the creep properties of the rock salt. This process causes deformations in the surrounding rock salt, which leads to a change in stress state in the virgin rock and may impair the integrity of the containment-providing rock zone. In order to limit the effects of these processes, all underground openings will be backfilled with crushed salt. Immediately after backfilling, the crushed salt will have an initial porosity of approx. 35%, which - over time - will be reduced to very low values due to the creep properties of the rock salt. The supporting pressure that builds up in the crushed salt with increasing compaction slows down the creeping of the salt. Major influencing factors are the temperature (with higher temperatures accelerating the salt creeping) and the moisture of the salt, which - due to the related decrease in the resistance of the crushed salt - facilitates its compaction. The phenomenology of these processes and dependencies is understood to a wide extent. This project investigated the duration until compaction is completed and when and under what circumstances the crushed salt will have the sealing properties necessary to ensure safe containment. Thermo-hydro-mechanical (THM) processes play a crucial role in determining whether solutions which might enter the mine could reach the radioactive waste. This includes changes in material behaviour due to a partial or complete

  20. Assessment of (222)Rn emanation from ore body and backfill tailings in low-grade underground uranium mine.

    Science.gov (United States)

    Mishra, Devi Prasad; Sahu, Patitapaban; Panigrahi, Durga Charan; Jha, Vivekanand; Patnaik, R Lokeswara

    2014-02-01

    This paper presents a comparative study of (222)Rn emanation from the ore and backfill tailings in an underground uranium mine located at Jaduguda, India. The effects of surface area, porosity, (226)Ra and moisture contents on (222)Rn emanation rate were examined. The study revealed that the bulk porosity of backfill tailings is more than two orders of magnitude than that of the ore. The geometric mean radon emanation rates from the ore body and backfill tailings were found to be 10.01 × 10(-3) and 1.03 Bq m(-2) s(-1), respectively. Significant positive linear correlations between (222)Rn emanation rate and the (226)Ra content of ore and tailings were observed. For normalised (226)Ra content, the (222)Rn emanation rate from tailings was found to be 283 times higher than the ore due to higher bulk porosity and surface area. The relative radon emanation from the tailings with moisture fraction of 0.14 was found to be 2.4 times higher than the oven-dried tailings. The study suggested that the mill tailings used as a backfill material significantly contributes to radon emanation as compared to the ore body itself and the (226)Ra content and bulk porosity are the dominant factors for radon emanation into the mine atmosphere.

  1. Testing the frost resistance of backfilling materials for geothermal heat probes; Pruefung der Frostbestaendigkeit von Verfuellmassen fuer Erdwaermesonden

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Tobias; Schnell, Kurt [HDG Umwelttechnik GmbH, Kisslegg (Germany)

    2011-07-01

    Groundwater protection, general operational safety and the reliable operation over many years are the key factors in the use of geothermal probes. Backfilling materials with which probes are pressed in the hole meet these requirements. For several years, manufacturers and researchers devote a great attention to the issue of an adequate freeze-thaw resistance of these components.

  2. Applications of a computer model to the analysis of rock-backfill interaction in pillar recovery operations

    Energy Technology Data Exchange (ETDEWEB)

    Sinclair, T. J.E. [Dames and Moore, London, England, United Kingdom; Shillabeer, J. H. [Dames and Moore, Toronto (Canada); Herget, G. [CANMET, Ottawa (Canada)

    1980-05-15

    This paper describes the application of a computer model to the analysis of backfill stability in pillar recovery operations with particular reference to two case studies. An explicit finite difference computer program was developed for the purpose of modelling the three-dimensional interaction of rock and backfill in underground excavations. Of particular interest was the mechanics of stress transfer from the rock mass to the pillars and then the backfill. The need, therefore, for a model to allow for the three-dimensional effects and the sequence of operations is evident. The paper gives a brief description of the computer program, descriptions of the mines, the sequences of operations and how they were modelled, and the results of the analyses in graphical form. For both case studies, failure of the backfill was predicted at certain stages. Subsequent reports from the mines indicate that such failures did not occur at the relevant stage. The paper discusses the validity of the model and concludes that the approach accurately represents the principles of rock mechanics in cut-and-fill mining and that further research should be directed towards determining the input parameters to an equal degree of sophistication.

  3. Evaluation of pre-jamming indication parameter during blind backfilling technique

    Directory of Open Access Journals (Sweden)

    Susmita Panda

    2016-01-01

    Full Text Available Hydraulic blind backfilling is used to reduce subsidence problems above old underground water-logged coal mines. This paper describes experimental research on a fully transparent model of a straight underground mine gallery. An automatic data acquisition system was installed in the model to continuously record the sand and water flowrates along with the inlet pressure of the slurry near the model's inlet. Pressure signature graphs and pressure loss curves with bed advancement under different flow conditions are examined. Pressure signature analyses for various flowrates and sand slurry concentrations are conducted to evaluate a pre-jamming indication parameter, which could be used to indicate the arrival of the final stage of filling.

  4. Reuse of Cement Kiln Dust for backfilling and CO2 carbonation

    Directory of Open Access Journals (Sweden)

    Lutyński Marcin

    2017-01-01

    Full Text Available The study aims to investigate possible alternative paths of reusing Cement Kiln Dust in mining technologies or as mineral sorbent for CO2 capture. Properties of CKD and bottom slag slurry were assessed and these were ia.: chemical composition, compressive strength and excess water content. Results show that CKD/bottom slag slurry mixed in the proportion of 25%/75% can be used as a backfill material if concentration of contaminants in the leaching tests is at the acceptable level. Second part of the study was devoted to the assessment of CKD as a sorbent in Calcium looping technologies or for mineral carbonation. TGA and DSC study shows that the rate of CO2 capture (carbonation is determined by the free CaO content. The highest carbonation rate was within the temperature range of 600-800°C.

  5. Backfilling with mixtures of bentonite/ballast materials or natural smectitic clay?

    Energy Technology Data Exchange (ETDEWEB)

    Pusch, R. [Geodevelopment AB, (Sweden)

    1998-10-01

    Comparison of the performance of backfills of mixed MX-80 and crushed rock ballast, and a natural smectitic clay, represented by the German Friedland clay, shows that the latter performs better than mixtures with up to 30 % MX-80. Considering cost, Friedland clay prepared to yield air-dry powder grains is cheaper than mixtures of 30 % MX-80 and crushed ballast. Both technically and economically it appears that the Friedland clay is a competitive alternative to mixtures of 30 % MX-80 and crushed ballast. However, it remains to be demonstrated on a full scale that Friedland clay ground to a suitable grain size distribution can be acceptably compacted on site 14 refs, 32 figs, 6 tabs

  6. Status of assessment tools on the performance guarantee contents of backfill, bulkhead, tunnel and pit

    International Nuclear Information System (INIS)

    Kawakami, Susumu; Fujita, Tomoo; Yui, Mikazu

    2006-03-01

    In order to contribute to the safety standards and guidelines which a regulator will decide, a state-of-the-art assessment method is investigated and summarized in tables about performance guarantee contents of backfill, bulkhead, tunnel (access, main, connecting, disposal) and disposal pit. In addition, examples of assessment tools are described. In this report, summary of (1) basic properties of bentonite, including swelling, mechanical and hydraulic properties, (2) long-term behavior of bentonite, including extrusion/erosion into host rock, and alteration, (3) effect of high pH plume from cementitious material and (4) mechanical stability of the near-field is described. Check points, assessment methods for (based on the data obtained from the experimental results, the estimation value obtained from empirical equations and database, and the modeling calculations) and latest results of these R and D programs were also summarized. (author)

  7. 129I- and 99TcO4-scavengers for low level radioactive waste backfills

    International Nuclear Information System (INIS)

    Balsley, S.D.; Brady, P.V.; Krumhansl, J.L.; Anderson, H.L.

    1997-03-01

    Minimization of 129 I - and 99 TcO 4 - transport to the biosphere is critical to the success of low level radioactive waste (LLRW) storage facilities. Here we experimentally identify and classify optimal sorbent materials for inclusion in LLRW backfills. For low pH conditions (pH 4-5), Cu-sulfides and possibly imogolite-rich soils provide K d 's (surface-solution partition coefficients) of roughly 10 3 ml g -1 for iodide, and 10 2 ml g -1 for technetium. At near neutral pH, hydrotalcites, Cu-oxides, Cu-sulfides and lignite coal possess K d 's on the order of 10 2 ml g -1 for both iodine and technetium. At high pH (pH > 10), such as might occur in a cementitious LLRW facility, calcium monosulfate aluminate K d 's are calculated to be roughly 10 2 ml g -1 for both iodine and technetium

  8. DISPERSION AND SORPTION CHARACTERISTICS OF URANIUM IN THE ZEOLITE-QUARTZ MIXTURE AS BACKFILL MATERIAL IN THE RADIOACTIVE WASTE REPOSITORY

    Directory of Open Access Journals (Sweden)

    Herry Poernomo

    2010-06-01

    Full Text Available The experiment of sorption and dispersion characteristics of uranium in the zeolite-quartz mixture as candidate of raw material of backfill material in the radioactive waste repository has been performed. The objective is to know the effect of zeolite and quartz grain size on the zeolite-to-quartz weight ratio that gives porosity (ε, permeability (K, and dispersivity (α of uranium in the zeolite-quartz mixture as backfill material. The experiment was carried out by fixed bed method in the column filled by the zeolite-quartz mixture with zeolite-to-quartz weight percent ratio of 100/0, 80/20, 60/40, 40/60, 20/80, 0/100 wt. % in the water saturated condition flowed by uranyl nitrate solution of 500 ppm concentration (Co as uranium simulation which was leached from immobilized radioactive waste in the repository. The concentration of uranium in the effluents represented as Ct were analyzed by spectrophotometer Corning Colorimeter 253 every 15 minutes, then using Co and Ct uranium dispersivity (α in the backfill material was determined. The experiment data shown that 0.196 mm particle size of zeolite and 0.116 mm particle size of quartz on the zeolite-to-quartz weight ratio of 60/40 wt. % with ε = 0.678, K = 3.345x10-4 cm/second, and α = 0.759 cm can be proposed as candidate of raw material of backfill material in the radioactive waste repository.   Keywords: backfill material, quartz, radioactive waste, zeolite

  9. Basic characteristic test of buffer/backfill material under Horonobe groundwater condition

    International Nuclear Information System (INIS)

    Kikuchi, Hirohito; Tanai, Kenji

    2005-02-01

    By the second progress report (H12) on research and development for the geological disposal of high-level radioactive waste (HLW) in Japan, Japan Nuclear Cycle Development Institute (JNC) extended the data base of basic properties of compacted bentonite which were mainly obtained by using distilled water as test fluid. This report presents influence of Horonobe groundwater on the basic properties of buffer and backfill material. The Horonobe groundwater is a type of saline groundwater. The groundwater was sampled at GL-300 m or deeper by using bore hole HDB-6 of the underground laboratory of Horonobe site. In addition, basic properties are also obtained by using distilled water, synthetic seawater, and NaCl solution. Experimental results are as follows; 1) Swelling characteristics, hydraulic characteristics and mechanical characteristics of the buffer material and backfill material decrease by the influence of saline water. The relationship between effective clay density and swelling stress is described by the following equation. σ = exp (2.5786ρ b 3 - 12.238ρ b 2 + 21.818ρ b - 14.035) where σ is swelling stress [MPa], ρ b is effective clay density [Mg/m 3 ]. The relationship between effective clay density and intrinsic permeability is described by the following equation. κ = exp (-41.466 + 4.316ρ b - 4.069ρ b 2 ) where κ is intrinsic permeability [m 2 ], ρ b is effective clay density [Mg/m 3 ]. The relationship between effective clay density and unconfined compressive strength is described by the following equation. qu = 1.4 x 10 -4 exp (5.637ρ b ) where qu is unconfined compressive strength [MPa], ρ b is effective clay density [Mg/m 3 ]. 2) Saline water doesn't influence the thermal characteristic of the buffer material. The thermal conductivity and specific heat are derived by using the relationship that was obtained so far. (author)

  10. Engineered Barrier System - Long-term Stability of Buffer and Backfill. Synthesis and extended abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Apted, Mick; Arthur, Randy [Monitor Scientific LLC, Denver, CO (United States); Savage, Dave [Quintessa Ltd., Nottingham (GB)] (eds.)

    2005-09-15

    SKI is preparing to review the license applications being developed by the Swedish Nuclear Fuel and Waste Management Company (SKB) for an encapsulation plant and a deep repository for the geological disposal of spent nuclear fuel. As part of its preparation, SKI is conducting a series of technical workshops on key aspects of the Engineered Barrier System (EBS) of the repository. This workshop concerns the longterm stability of the buffer and the backfill. Previous workshops have addressed the overall concept for long-term integrity of the EBS, the manufacturing, testing and QA of the EBS and the performance confirmation for the EBS. The goal of this work is to achieve a comprehensive overview of all aspects of SKB's EBS work prior to the handling of forthcoming license applications. The reports from the EBS workshops will be used as one important basis in future review work. The workshops involve the gathering of a sufficient number of independent experts in different subjects of relevance to the particular aspect of EBS. A workshop starts with presentations and discussions among these experts. Following this, SKB presents recent results and responds to questions as part of an informal hearing. Finally, the independent experts and the SKI staff examine the SKB responses from different viewpoints. This report aims to summarise the issues discussed at the buffer and backfill workshop and to extract the essential viewpoints that have been expressed. The report is not a comprehensive record of the discussions and individual statements made by workshop participants should be regarded as opinions rather than proven facts. This reports includes apart from the workshop synthesis, questions to SKB identified prior or during the workshop, and extended abstracts for introductory presentations.

  11. Engineered Barrier System - Long-term Stability of Buffer and Backfill. Synthesis and extended abstracts

    International Nuclear Information System (INIS)

    Apted, Mick; Arthur, Randy; Savage, Dave

    2005-09-01

    SKI is preparing to review the license applications being developed by the Swedish Nuclear Fuel and Waste Management Company (SKB) for an encapsulation plant and a deep repository for the geological disposal of spent nuclear fuel. As part of its preparation, SKI is conducting a series of technical workshops on key aspects of the Engineered Barrier System (EBS) of the repository. This workshop concerns the longterm stability of the buffer and the backfill. Previous workshops have addressed the overall concept for long-term integrity of the EBS, the manufacturing, testing and QA of the EBS and the performance confirmation for the EBS. The goal of this work is to achieve a comprehensive overview of all aspects of SKB's EBS work prior to the handling of forthcoming license applications. The reports from the EBS workshops will be used as one important basis in future review work. The workshops involve the gathering of a sufficient number of independent experts in different subjects of relevance to the particular aspect of EBS. A workshop starts with presentations and discussions among these experts. Following this, SKB presents recent results and responds to questions as part of an informal hearing. Finally, the independent experts and the SKI staff examine the SKB responses from different viewpoints. This report aims to summarise the issues discussed at the buffer and backfill workshop and to extract the essential viewpoints that have been expressed. The report is not a comprehensive record of the discussions and individual statements made by workshop participants should be regarded as opinions rather than proven facts. This reports includes apart from the workshop synthesis, questions to SKB identified prior or during the workshop, and extended abstracts for introductory presentations

  12. Assessment of hydration process and mechanical properties of cemented paste backfill by electrical resistivity measurement

    Science.gov (United States)

    Xu, Wenbin; Tian, Xichun; Cao, Peiwang

    2018-04-01

    Cemented paste backfill (CPB) is an emerging mine backfill technique that allows environmentally hazardous tailings to return to the underground openings or stopes, thereby maximising the safety, efficiency and productivity of operation. Uniaxial compressive strength (UCS) is one of the most commonly used parameters for evaluating the mechanical performance of CPB; the prediction of the UCS of CPB structures from early to advanced ages is of great practical importance. This study aims to investigate the predictability of the UCS of CPB during the hydration process based on electrical resistivity (ER) measurement. For this purpose, the samples prepared at different cement-to-tailing ratios and solid contents were subjected to the ER test during the whole hydration process and UCS tests at 3, 7, 28 days of curing periods. The effect of cement-to-tailing ratio and solid content on the ER and UCS of CPB samples was obtained; the UCS values were correlated with the corresponding ER data. Microstructural analysis was also performed on CPB samples to understand the effect of microstructure on the ER data. The result shows that the ER of CPB decreases first and then increases with the speed which is faster in the previous part than the latter. The ER and UCS of CPB samples increased with increasing cement-to-tailing ratio and solid content and curing periods. A logarithmic relationship is established for each mixture in order to predict the UCS of CPB based on ER. Scanning electron microscope analyses have revealed that the microstructure of the CPB changes with the age from the initial floc to honeycomb, and eventually to the compact clumps. The ER properties of CPB samples were highly associated with their respective microstructural properties. The major output of this study is that ER test is effectively capable for a preliminary prediction of the UCS of CPB.

  13. Porewater salinity and the development of swelling pressure in bentonite-based buffer and backfill materials

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, D.A. [Atomic Energy of Canada Limited (Canada)

    2000-06-01

    At the depths proposed for a nuclear fuel waste repository, it is likely that saline groundwater conditions will be encountered in the granitic rocks of Finland and Canada. The potential for saline groundwater to influence of the ability of bentonite-based buffer and backfilling materials to swell and thereby generate swelling pressure has been reviewed. Based on the data collected from existing literature, it would appear that porewater salinities as high as 100 g/l will not compromise the ability of confined, bentonite-based materials to develop a swelling pressure of at least 100 kPa on its confinement, provided the effective clay dry density (ECDD), exceeds approximately 0.9 Mg/m{sup 3}. At densities less than approximately 0.9 Mg/m{sup 3} the swelling pressure of bentonite-based materials may be reduced and become sensitive to salt concentration. The influence of porewater salinity on swelling pressure can be compared on the basis of the ECDD required to develop 100 kPa of swelling pressure. In order to generate 100 kPa of swelling pressure an ECDD of approximately 0.7 Mg/m{sup 3} is required to be present under fresh water or brackish porewater conditions. This density would need to be increased to approximately 0.9 Mg/m{sup 3} where the groundwater conditions were saline. The impact that groundwater salinity will have on density specifications for buffer and backfilling materials are discussed with reference to the nuclear fuel waste disposal concepts of Finland and Canada. (orig.)

  14. Preliminary results from water content and density measurements of the backfill and buffer in the prototype repository at Aespoe HRL

    International Nuclear Information System (INIS)

    Johannesson, Lars-Erik; Grahm, Paer; Hagman, Patrik

    2012-01-01

    Document available in extended abstract form only. Since 2001 the Prototype Repository at Aespoe Hard Rock Laboratory has been carried out as a large-scale experimental installation of the KBS-3 Swedish/Finnish concept for final disposal of spent nuclear fuel. The Prototype Repository consists of a total of six full-scale deposition holes with a centre distance of 6 m, located in a TBM tunnel at a depth of 450 m. Each deposition hole is fitted with a full-scale bentonite buffer, consisting of altogether 14 blocks and a full-scale canister, Figure 1. The canisters are equipped with heaters to simulate the heat from spent nuclear fuel. There are two sections of the installation; The inner section (I) consisting of four deposition holes (no. 1-4) with buffer and canister, and the outer section (II) consisting of two deposition holes (no. 5-6). The deposition tunnel is filled with a mixture of crushed rock and bentonite (30% of bentonite). A massive concrete plug, designed to withstand full water and swelling pressures, separates the test area from the open tunnel system and a second plug separates the two sections. This layout provides two more or less independent test sections. The outer section was opened and retrieved during 2011. The backfill was excavated with a back-hoe loader in layers of two metres. Samples were taken in these layers with the object of determining density and water content. Important items of the backfill to examine were the contact between backfill and the tunnel wall and the contact between the buffer and backfill in the deposition holes. The water content of the backfill was determined by drying samples in an oven at a temperature of 105 C for 24 h and the density was determined by weighting the sample both in air and merged into paraffin oil with known density. Altogether more than 900 tons of backfill material was excavated from the tunnel and more than 1100 samples, distributed over 11 sections, were taken for determining the water

  15. Investigations of excavated clay-stone as backfill/seal material

    International Nuclear Information System (INIS)

    Zhang, Chun-Liang

    2012-01-01

    Document available in extended abstract form only. Crushed clay-stone produced by excavation activities of repository drifts has been investigated as backfill/seal material at the GRS laboratory. The raw aggregate with coarse grains is considered to be used for backfilling the repository openings and, in mixture with bentonite, for sealing the boreholes, drifts and shafts. The GRS research programme focused on characterizing the thermo-hydro-mechanical properties of the excavated Callovo-Oxfordian clay-stone (COX) and the clay-stone-bentonite mixtures, including mechanical compaction, gas and water permeability as function of porosity, water retention and saturation, swelling capacity, and thermal properties of the materials. The most important results are presented in this paper. Figure 1 shows the compaction and permeability behaviour of the excavated clay-stone with grains up to a size of 32 mm. The results were obtained on large samples of 280 mm diameter and 680 mm height under quasi-hydrostatic compression. The porosity and permeability decrease with increasing load. The porosity-mean stress relation is non-linear and may be expressed by an exponential function. The backfill becomes stiffer at low porosities and can sustain certain deviatoric loads. At porosity of ∼21 %, the strength is characterized by an inherent cohesion of 3.7 MPa and an internal friction angle of 12 deg.. Additionally, the compaction is also dependent on time or loading rate, water content, and temperature. The compaction of the porous backfill material leads to a reduction in permeability. The measured gas permeability decreases much faster at low porosities below ∼25 %. The gas permeability at porosity of ∼20 % becomes as low as that of 10 -20 - 10 -21 m 2 for the intact clay rock. This is probably due to disconnection of the pore network during the compaction. As sealing material, powdered COX clay-stone was mixed with MX80 bentonite powder in different ratios and compacted to

  16. Characterization of a backfill candidate material, IBECO-RWC-BF Baclo Project - Phase 3 Laboratory tests

    International Nuclear Information System (INIS)

    Johannesson, Lars-Erik; Sanden, Torbjoern; Dueck, Ann; Ohlsson, Lars

    2010-01-01

    A backfill candidate material, IBECO-RWC-BF, which origin from Milos, Greece, has been investigated. The material was delivered both as granules and as pellets. The investigation described in this report aimed to characterize the material and evaluate if it can be used in a future repository. The following investigations have been done and are presented in this report: 1. Standard laboratory tests. Water content, liquid limit and swelling potential are examples on standard tests that have been performed. 2. Block manufacturing. The block compaction properties of the material have been determined. A first test was performed in laboratory but also tests in large scale have been performed. After finishing the test phase, 60 tons of blocks were manufactured at Hoeganaes Bjuf AB. The blocks will be used in large scale laboratory tests at Aespoe HRL. 3. Mechanical parameters. The compressibility of the material was investigated with oedometer tests (four tests) where the load was applied in steps after saturation. The evaluated oedometer modulus varied between 34.50 MPa. Tests were made to evaluate the elastic parameters of the material (E, ν). Altogether three tests were made on specimens with dry densities of about 1,710 kg/m 3 . The evaluated E-modulus and Poisson's ratio varied between 231-263 MPa and 0.16-0.19 respectively. The strength of the material, both the compressive strength and the tensile strength were measured on specimens compacted to different dry densities. The test results yielded a relation between density and the two types of strength. Furthermore, tests have been made in order to determine the compressibility of the unsaturated filling of pellets. Two tests were made where the pellets were loosely filled in a Proctor cylinder and then compressed at a constant rate of strain during continuously measurement of the applied load. 4. Swelling pressure and hydraulic conductivity. There is, as expected, a very clear influence of the dry density on the

  17. FY:15 Transport Properties of Run-of-Mine Salt Backfill ? Unconsolidated to Consolidated.

    Energy Technology Data Exchange (ETDEWEB)

    Dewers, Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Heath, Jason E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Leigh, Christi D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-28

    The nature of geologic disposal of nuclear waste in salt formations requires validated and verified two-phase flow models of transport of brine and gas through intact, damaged, and consolidating crushed salt. Such models exist in other realms of subsurface engineering for other lithologic classes (oil and gas, carbon sequestration etc. for clastics and carbonates) but have never been experimentally validated and parameterized for salt repository scenarios or performance assessment. Models for waste release scenarios in salt back-fill require phenomenological expressions for capillary pressure and relative permeability that are expected to change with degree of consolidation, and require experimental measurement to parameterize and validate. This report describes a preliminary assessment of the influence of consolidation (i.e. volume strain or porosity) on capillary entry pressure in two phase systems using mercury injection capillary pressure (MICP). This is to both determine the potential usefulness of the mercury intrusion porosimetry method, but also to enable a better experimental design for these tests. Salt consolidation experiments are performed using novel titanium oedometers, or uniaxial compression cells often used in soil mechanics, using sieved run-of-mine salt from the Waste Isolation Pilot Plant (WIPP) as starting material. Twelve tests are performed with various starting amounts of brine pore saturation, with axial stresses up to 6.2 MPa (~900 psi) and temperatures to 90°C. This corresponds to UFD Work Package 15SN08180211 milestone “FY:15 Transport Properties of Run-of-Mine Salt Backfill – Unconsolidated to Consolidated”. Samples exposed to uniaxial compression undergo time-dependent consolidation, or creep, to various degrees. Creep volume strain-time relations obey simple log-time behavior through the range of porosities (~50 to 2% as measured); creep strain rate increases with temperature and applied stress as expected. Mercury porosimetry

  18. Preparation of fly ash-granulated blast furnace slag-carbide slag binder and application in total tailings paste backfill

    Science.gov (United States)

    Li, Chao; Hao, Ya-fei; Zhao, Feng-qing

    2018-03-01

    Based on activation and synergistic effect among various materials, a low-cost mine backfill cementing material, FGC binder, was prepared by using fly ash, granulated blast-furnace slag (GBFS), carbide slag and composite activator. The proper proportioning of FGC binder is obtained by response surface experiment optimization method: fly ash 62 %, GBFS 20 %, carbide slag 8 % and compound activators 10 %. Adjusting the material ratio obtains different cementing material which could satisfy requirements of different mined-out areas. With the mass ratio of cementing material and tailings 1:4∼1:8, the concentration of total solid 70 %, the compressive strength values of total tailings filling body at 28 d reaches 1.64∼4.14 MPa, and the backfilling cost is 20 % lower than using OPC cement.

  19. Experimental studies on the inventory of cement-derived colloids in the pore water of a cementitious backfill material

    International Nuclear Information System (INIS)

    Wieland, E.

    2001-06-01

    The potential role of near-field colloids for the colloid-facilitated migration of radionuclides has stimulated investigations concerning the generation and presence of colloids in the near-field of a repository for low- and intermediate level waste (L/ILW). The highly gas permeable mortar (Nagra designation: mortar M1) is currently favoured as backfill material for the engineered barrier of the planned Swiss L/ILW repository. The cementitious backfill is considered to be a chemical environment with some potential for colloid generation. In a series of batch-style laboratory experiments the physico-chemical processes controlling the inventory of colloids in cement pore water of the backfill were assessed for chemical conditions prevailing in the initial stage of the cement degradation. In these experiments, backfill mortar M1 or quartz, respectively, which may be used as aggregate material for the backfill, were immersed in artificial cement pore water (a NaOH/KOH rich cement fluid). Colloid concentrations in the cement pore water were recorded as a function of time for different experimental settings. The results indicate that a colloid-colloid interaction process (coagulation) controlled the colloid inventory. The mass concentration of dispersed colloids was found to be typically lower than 0.02 ppm in undisturbed batch systems. An upper-bound value was estimated to be 0.1 ppm taking into account uncertainties on the measurements. To assess the potential for colloid generation in a dynamic system, colloid concentrations were determined in the pore water of a column filled with backfill mortar. The chemical conditions established in the mortar column corresponded to conditions observed in the second stage of the cement degradation (a Ca(OH) 2 - controlled cement system). In this dynamic system, the upper-bound value for the colloid mass concentration was estimated to be 0.1 ppm. Implications for radionuclide mobility were deduced taking into account the

  20. Experimental studies on the inventory of cement-derived colloids in the pore water of a cementitious backfill material

    Energy Technology Data Exchange (ETDEWEB)

    Wieland, E

    2001-06-01

    The potential role of near-field colloids for the colloid-facilitated migration of radionuclides has stimulated investigations concerning the generation and presence of colloids in the near-field of a repository for low- and intermediate level waste (L/ILW). The highly gas permeable mortar (Nagra designation: mortar M1) is currently favoured as backfill material for the engineered barrier of the planned Swiss L/ILW repository. The cementitious backfill is considered to be a chemical environment with some potential for colloid generation. In a series of batch-style laboratory experiments the physico-chemical processes controlling the inventory of colloids in cement pore water of the backfill were assessed for chemical conditions prevailing in the initial stage of the cement degradation. In these experiments, backfill mortar M1 or quartz, respectively, which may be used as aggregate material for the backfill, were immersed in artificial cement pore water (a NaOH/KOH rich cement fluid). Colloid concentrations in the cement pore water were recorded as a function of time for different experimental settings. The results indicate that a colloid-colloid interaction process (coagulation) controlled the colloid inventory. The mass concentration of dispersed colloids was found to be typically lower than 0.02 ppm in undisturbed batch systems. An upper-bound value was estimated to be 0.1 ppm taking into account uncertainties on the measurements. To assess the potential for colloid generation in a dynamic system, colloid concentrations were determined in the pore water of a column filled with backfill mortar. The chemical conditions established in the mortar column corresponded to conditions observed in the second stage of the cement degradation (a Ca(OH){sub 2{sup -}} controlled cement system). In this dynamic system, the upper-bound value for the colloid mass concentration was estimated to be 0.1 ppm. Implications for radionuclide mobility were deduced taking into account the

  1. Backfill barriers: the use of engineered barriers based on geologic materials to assure isolation of radioactive wastes in a repository

    International Nuclear Information System (INIS)

    Apps, J.A.; Cook, N.G.W.

    1981-06-01

    A preliminary assessment is made to show that canisters fabricated of nickel-iron alloys, and surrounded by a suitable backfill, may produce an engineered barrier where the canister material is thermodynamically stable with respect to its environment. As similar conditions exist in nature, the performance of such systems as barriers to isolate radionuclides can be predicted over very long periods, of the order of 10 6 years

  2. Crushed aggregate-betonite mixtures as backfill material for the Finnish repositories of low- and intermediate-level radioactive wastes

    International Nuclear Information System (INIS)

    Holopainen, P.; Pirhonen, V.; Snellman, M.

    1984-03-01

    Backfill materials consisting of three components: crushed rock aggregate, finely ground rock aggregate and bentonite (3 to 2 per cent of weight) were studied. The production and installation procedures of the material were evaluated. Laboratory tests were made to determine the hydraulic conductivity and swelling potential of the materials. Chemical tests were made on the different materials and groundwaters. Mineralogical changes of the clay fraction were estimated. (author)

  3. Simulation of effects of redox and precipitation on diffusion of uranium solution species in backfill

    International Nuclear Information System (INIS)

    Carnahan, C.L.

    1987-12-01

    This investigation addresses the problem of prediction of the rate of migration of redox-sensitive solution species within packing and backfill materials under conditions of variable oxidation potential. Effects of changes of oxidation potential and precipitation of stable uranium compounds during diffusion of uranium from a region of high oxidation potential into a region of low oxidation potential were simulated numerically. Questions of particular interest addressed in the investigation were the existence of a moving ''redox front'' and the influence of precipitation-dissolution processes on uranium migration. The simulations showed that no expanding redox fronts existed at any simulated time up to 3.2 x 10 5 years (10 13 s). In simulations where precipitation of stable solids was not allowed, variations of oxidation potential did not affect total uranium concentrations in solution. Concentration profiles could be predicted simply by diffusion of the (constant) source concentrations. In simulations where precipitation of stable solids was allowed, uraninite and calcium uranate accumulated at the source-transport domain interface, while coffinite penetrated further into the transport domain. Total uranium concentrations in regions of precipitation were determined by solubilities of the precipitated solids, and were six to seven orders of magnitude lower than those in the simulations without precipitation, throughout the domain of transport. 14 refs., 7 figs., 2 tabs

  4. Buffer and backfill process report for the safety assessment SR-Can

    Energy Technology Data Exchange (ETDEWEB)

    Sellin, Patrik (comp.)

    2006-09-15

    This document compiles information on processes in the buffer and deposition tunnel backfill relevant for long-term safety of a KBS-repository. It supports the safety assessment SR-Can, which is a preparatory step for a safety assessment that will support the licence application for a final repository in Sweden. The purpose of the process reports is to document the scientific knowledge of the processes to a level required for an adequate treatment of the processes in the safety assessment. The documentation is not exhaustive from a scientific point of view, since such a treatment is neither necessary for the purposes of the safety assessment nor possible within the scope of an assessment. However, it must be sufficiently detailed to motivate, by arguments founded on scientific understanding, the treatment of each process in the safety assessment. The purpose is further to determine how to handle each process in the safety assessment at an appropriate degree of detail, and to demonstrate how uncertainties are taken care of, given the suggested handling.

  5. Salt content impact on the unsaturated property of bentonite-sand buffer backfilling materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Ming [Key Laboratory of Mechanics on Disaster and Environment in Western China, Lanzhou University, Lanzhou 730000 (China); Zhang Huyuan, E-mail: p1314lvp@yahoo.com.cn [Key Laboratory of Mechanics on Disaster and Environment in Western China, Lanzhou University, Lanzhou 730000 (China); Jia Lingyan; Cui Suli [Key Laboratory of Mechanics on Disaster and Environment in Western China, Lanzhou University, Lanzhou 730000 (China)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer SWCC and infiltration process of bentonite-sand mixtures is researched. Black-Right-Pointing-Pointer The k{sub u} of bentonite-sand mixtures was evaluated as the buffer backfilling materials. Black-Right-Pointing-Pointer Salt content impacting on the unsaturated property of bentonite-sand materials is small. - Abstract: Bentonite mixed with sand is often considered as possible engineered barrier in deep high-level radioactive waste disposal in China. In the present work, the vapor transfer technique and water infiltration apparatus were used to measure the soil water characteristic curve (SWCC) and unsaturated hydraulic conductivity (k{sub u}) of bentonite-sand mixtures (B/S) effected by salt content. Results show, the water-holding capacity and k{sub u} increase slightly with the concentration of Na{sup +} in pore liquid increasing from 0 g/L to 12 g/L, similar with the solution concentration of Beishan groundwater in China. Salt content in the laboratory produced only one order of magnitude increase in k{sub u}, which is the 'safe' value. The different pore liquid concentrations used in this study led to small differences in thickness of diffuse double layer of bentonite in mixtures, this might explain why some differences have been found in final values of k{sub u}.

  6. Determination of soil mechanics of salt rock as a potential backfilling material in an underground repository

    International Nuclear Information System (INIS)

    Kappei, G.

    1987-09-01

    Within the framework of the research and development project 'Backfilling and sealing of boreholes, chambers and roadways in a final dump', the Institute for Underground Dumping chose - from the broad range of possible stowing materials - the material 'salt spoil' and investigated its soil-mechanical properties in detail. Besides the implementation of soil-mechanical standard analyses (determination of the grain size distribution, bulk density, limits of storage density, proctor density, permeabilities, and shear strength) of two selected salt spoils (heap salt and rock salt spoil), the studies concentrated on the determination of the compression behaviour of salt spoil. In order to obtain data on the compaction behaviour of this material in the case of increasing stress, compression tests with obstructed lateral expansion were carried out on a series of spoil samples differing mainly in the composition of grain sizes. In addition to this, for a small number of samples of rock salt spoil, the creep behaviour at constant stress was determined after the compaction phase. (orig./RB) [de

  7. Feasibility of backfilling mines using cement kiln dust, fly ash, and cement blends

    Directory of Open Access Journals (Sweden)

    Beltagui H.

    2018-01-01

    Full Text Available Cement kiln dust (CKD is an industrial by-product of the cement manufacturing process, the composition of which can vary widely. Recent years of using alternative fuels have resulted in higher chloride and alkali contents within CKDs; as such, this limits the applications in which CKDs can be utilised. Using a CKD containing a high free lime content of 29.5%, it is shown that this CKD is capable of activating pulverized fuel ash (PFA due to its high alkalinity, which can be utilised in low strength un-reinforced applications. One potential application involves the backfill of mines, reducing the need for continuous maintenance of the mine. This study focuses on the compressive strength achieved by various blends of CKD, PFA, and cement. Samples were hand mixed and compacted in 100 mm x 50 mm diameter cylinders, and unconfined compressive strength measurements taken at 28 and 56 days. The hydration products were assessed through the use of x-ray diffraction and thermogravimetric analysis. Aiming to maximise the use of CKD at a water to binder (w/b ratio of 0.2, it was found that the maximum CKD content possible to achieve the required strength was 90% CKD blended with 10% cement.

  8. THM modelling of buffer, backfill and other system components. Critical processes and scenarios

    International Nuclear Information System (INIS)

    Aakesson, Mattias; Kristensson, Ola; Boergesson, Lennart; Dueck, Ann; Hernelind, Jan

    2010-03-01

    A number of critical thermo-hydro-mechanical processes and scenarios for the buffer, tunnel backfill and other filling components in the repository have been identified. These processes and scenarios representing different aspects of the repository evolution have been pinpointed and modelled. In total, 22 cases have been modelled. Most cases have been analysed with finite element (FE) calculations, using primarily the two codes Abaqus and Code B right. For some cases analytical methods have been used either to supplement the FE calculations or due to that the scenario has a character that makes it unsuitable or very difficult to use the FE method. Material models and element models and choice of parameters as well as presumptions have been stated for all modelling cases. In addition, the results have been analysed and conclusions drawn for each case. The uncertainties have also been analysed. Besides the information given for all cases studied, the codes and material models have been described in a separate so called data report

  9. The Buffer and Backfill Handbook. Part 1: Definitions, basic relationships and laboratory methods

    Energy Technology Data Exchange (ETDEWEB)

    Pusch, Roland [Geodevelopment AB, Lund (Sweden)

    2002-04-01

    Part 1 of this Handbook is focused on description of fundamental issues of soil physical and chemical arts and on soil mechanical definitions and relationships. Part 2 comprises a material data basis including also preparation and field testing methods. Part 3 provides a collection of physical and mathematical models and examples of how they can and should be applied. The present document, which has been prepared by Geodevelopment AB in co-operation with Scandia Consult AB and Clay Technology AB, Sweden, and with TVO, Finland, makes up Part 1. Most of the data and information emanate from the work that Geodevelopment AB and Clay Technology AB have performed for SKB but a number of results from experiments made in and for other organizations have been included as well. A significant number of experimental procedures and ways of characterizing buffers and backfills are included. The experience from the comprehensive international Stripa Project, concerning both systematic material investigations in the laboratory and the full-scale field experiments, has contributed significantly to this report. However, similar and additional information gained from later work in SKB's Aespoe Hard Rock Laboratory and from NAGRA and also from other waste-isolation projects have helped to make this document of assumed international interest.

  10. The Buffer and Backfill Handbook. Part 1: Definitions, basic relationships and laboratory methods

    International Nuclear Information System (INIS)

    Pusch, Roland

    2002-04-01

    Part 1 of this Handbook is focused on description of fundamental issues of soil physical and chemical arts and on soil mechanical definitions and relationships. Part 2 comprises a material data basis including also preparation and field testing methods. Part 3 provides a collection of physical and mathematical models and examples of how they can and should be applied. The present document, which has been prepared by Geodevelopment AB in co-operation with Scandia Consult AB and Clay Technology AB, Sweden, and with TVO, Finland, makes up Part 1. Most of the data and information emanate from the work that Geodevelopment AB and Clay Technology AB have performed for SKB but a number of results from experiments made in and for other organizations have been included as well. A significant number of experimental procedures and ways of characterizing buffers and backfills are included. The experience from the comprehensive international Stripa Project, concerning both systematic material investigations in the laboratory and the full-scale field experiments, has contributed significantly to this report. However, similar and additional information gained from later work in SKB's Aespoe Hard Rock Laboratory and from NAGRA and also from other waste-isolation projects have helped to make this document of assumed international interest

  11. THM modelling of buffer, backfill and other system components. Critical processes and scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Aakesson, Mattias; Kristensson, Ola; Boergesson, Lennart; Dueck, Ann (Clay Technology AB, Lund (Sweden)); Hernelind, Jan (5T-Engineering AB, Vaesteraas (Sweden))

    2010-03-15

    A number of critical thermo-hydro-mechanical processes and scenarios for the buffer, tunnel backfill and other filling components in the repository have been identified. These processes and scenarios representing different aspects of the repository evolution have been pinpointed and modelled. In total, 22 cases have been modelled. Most cases have been analysed with finite element (FE) calculations, using primarily the two codes Abaqus and Code-Bright. For some cases analytical methods have been used either to supplement the FE calculations or due to that the scenario has a character that makes it unsuitable or very difficult to use the FE method. Material models and element models and choice of parameters as well as presumptions have been stated for all modelling cases. In addition, the results have been analysed and conclusions drawn for each case. The uncertainties have also been analysed. Besides the information given for all cases studied, the codes and material models have been described in a separate so called data report

  12. Buffer and backfill process report for the safety assessment SR-Can

    International Nuclear Information System (INIS)

    Sellin, Patrik

    2006-09-01

    This document compiles information on processes in the buffer and deposition tunnel backfill relevant for long-term safety of a KBS-repository. It supports the safety assessment SR-Can, which is a preparatory step for a safety assessment that will support the licence application for a final repository in Sweden. The purpose of the process reports is to document the scientific knowledge of the processes to a level required for an adequate treatment of the processes in the safety assessment. The documentation is not exhaustive from a scientific point of view, since such a treatment is neither necessary for the purposes of the safety assessment nor possible within the scope of an assessment. However, it must be sufficiently detailed to motivate, by arguments founded on scientific understanding, the treatment of each process in the safety assessment. The purpose is further to determine how to handle each process in the safety assessment at an appropriate degree of detail, and to demonstrate how uncertainties are taken care of, given the suggested handling

  13. BACEKO II. Flow-through, open-front and saturation tests of pre-compacted backfill blocks in a quarter-scale test tunnel

    International Nuclear Information System (INIS)

    Keski-Kuha, E.; Nemlander, R.; Koho, P.

    2013-11-01

    The series of tests performed in BACEKO II project examined three different block materials for potential use in backfilling the repository; Friedland clay, 40/60-mixture of bentonite (40 %) and crushed rock (60 %) and Milos B clay in conjunction with pellet materials Cebogel QSE and Milos B clay. The testing program consisted of 9 tests, that continued the 1/4-scale tests executed in BACEKO 2008. The block backfilling degree of the 1/4-scale test tunnels was 73.8 % which was consistent with the material ratios associated with filling a repository tunnel having a 10 % over-excavation ratio. Some of these tests were conducted using a restraint installed at the front face of the setup and open-front tests were subsequently added in order to establish the time span which an open backfill front can remain stable should an interruption in the backfilling process occur. Additionally one flow-through test with higher salinity water (7 % TDS versus the 3,5 % TDS used in all other tests), was performed for an assembly constructed using Friedland clay. The rate of test assembly, consumption of materials and achieved densities were all monitored. During the tests, the erosion rates, progression of saturation and development of total pressure were monitored. In disassembling the tests, samples were collected for gravimetric water content measurement, the erosion pathways were identified and the sections were photographed with an infrared camera to illustrate the moister areas in the backfill. The greatest amounts of eroded material were observed in open-front tests where exiting water removed clay from the face of the backfill and formed a deepening channel in the block backfill. The open-front tests remained stable only until the outflow emerged. The properties of the pellet layer depend on the as-placed conditions which were operatordependant and also affect the outflow times. There was not much difference in the amount of erosion observed for the different block materials

  14. Manufacturing and performance of customized pellets used for buffer and backfill sealing in nuclear waste containment

    International Nuclear Information System (INIS)

    Holt, Erika; Marjavaara, Pieti; Man, Alex; Kim, Chang-Seok; Dixon, David

    2012-01-01

    Document available in extended abstract form only. Bentonite pellets are proposed for use in filling gaps between highly compacted bentonite and the surrounding rock walls. Previous studies typically focused on using commercially available bentonite pellets with good performance results typically being achieved but no comprehensive evaluations were undertaken. This paper summarizes the results of two recent studies completed on gap filling materials and customized pellets that were intended to see to what degree improvement of the pellet materials and placement density could be achieved and what this would mean to system behaviour. Although the joint project covered a wide range of potential materials and sealing applications, in this presentation, the focus is on the use of bentonite filling material in the outer gap between the rock surface and large highly-compacted bentonite buffer blocks used in Posiva's Reference vertical deposition design. The gap between the deposition hole's wall and the buffer is 50 mm, which should be filled with material prior to tunnel backfilling. The required dry density of the outer gap filling is 920 kg/m 3 , with an average buffer dry density of 1600 kg/m 3 at 100% saturation. At these densities, the thermal, hydraulic and mechanical behaviour of the system meet the requirements set for them. In the first part of this study, various types of commercially-available bentonite granular materials were used alone or in combination with finer material. Different placement methods were used to fill vertical gaps of either 25 or 35 mm width in a small-scale experimental mock-up. The sizes of the rectangular gap mock-up elements used in these tests were approximately 1 m in height and 2 m long. The results from the small scale tests suggest that all the filling materials and methods used during the test would achieve as-placed dry density of 800-1200 kg/m 3 , depending on material and placement method used. The lowest values were noted

  15. Review of the properties and uses of bentonite as a buffer and backfill material

    International Nuclear Information System (INIS)

    Savage, D.; Lind, A.; Arthur, R.C.

    1999-05-01

    Research carried out by SKB on the use and behaviour of bentonite as a buffer and backfill material in a radioactive waste repository has been reviewed. The following research areas have been evaluated: mechanical properties; hydraulic and other transport properties; geochemical properties; thermal properties and resaturation; gas migration; manufacturing and emplacement procedures. This review has shown that SKB has carried out much pioneering and world-leading research on bentonite, particularly with regard to analogue studies, microtextural work and practical manufacturing and emplacement procedures. However, there are a number of subject areas which appear less well addressed than others which require further attention: The extrapolation of experimental results of the mechanical properties of bentonite to repository timescales and repository conditions should be investigated further. There is a need for detailed microstructural analysis of materials as part of experimental programmes. This would enable SKB to build confidence in the interpretations of results and reveal whether the mechanical processes occurring during experimentation truly reflect expectations of the performance of the repository. The large amount of experimental, theoretical, empirical datasets and computer models of the mechanical properties of bentonite need to be collated to form a database which is assessable and relevant to those involved in performance assessment calculations. At present, the valuable results of many excellent research projects on mechanical properties of bentonite buffer are not readily available. There seems to be a relatively poor understanding of the mechanisms of radionuclide diffusion through compacted bentonite. Other international work suggests that diffusion coefficients are much lower than those applied by SKB in its PA work. The importance of surface diffusion to describe diffusion in bentonite for certain chemical species ascribed by SKB is not reflected in

  16. Review of the properties and uses of bentonite as a buffer and backfill material

    Energy Technology Data Exchange (ETDEWEB)

    Savage, D.; Lind, A. [QuantiSci Ltd., Melton Mowbray (United Kingdom); Arthur, R.C. [QuantiSci lnc., Denver, CO (United States)

    1999-05-01

    Research carried out by SKB on the use and behaviour of bentonite as a buffer and backfill material in a radioactive waste repository has been reviewed. The following research areas have been evaluated: mechanical properties; hydraulic and other transport properties; geochemical properties; thermal properties and resaturation; gas migration; manufacturing and emplacement procedures. This review has shown that SKB has carried out much pioneering and world-leading research on bentonite, particularly with regard to analogue studies, microtextural work and practical manufacturing and emplacement procedures. However, there are a number of subject areas which appear less well addressed than others which require further attention: The extrapolation of experimental results of the mechanical properties of bentonite to repository timescales and repository conditions should be investigated further. There is a need for detailed microstructural analysis of materials as part of experimental programmes. This would enable SKB to build confidence in the interpretations of results and reveal whether the mechanical processes occurring during experimentation truly reflect expectations of the performance of the repository. The large amount of experimental, theoretical, empirical datasets and computer models of the mechanical properties of bentonite need to be collated to form a database which is assessable and relevant to those involved in performance assessment calculations. At present, the valuable results of many excellent research projects on mechanical properties of bentonite buffer are not readily available. There seems to be a relatively poor understanding of the mechanisms of radionuclide diffusion through compacted bentonite. Other international work suggests that diffusion coefficients are much lower than those applied by SKB in its PA work. The importance of surface diffusion to describe diffusion in bentonite for certain chemical species ascribed by SKB is not reflected in

  17. SR-Site Data report. THM modelling of buffer, backfill and other system components

    Energy Technology Data Exchange (ETDEWEB)

    Aakesson, Mattias; Boergesson, Lennart; Kristensson, Ola (Clay Technology AB, Lund (Sweden))

    2010-03-15

    This report is a supplement to the SR-Site data report. Based on the issues raised in the Process reports concerning THM processes in buffer, backfill and other system components, 22 modelling tasks have been identified, representing different aspects of the repository evolution. The purpose of this data report is to provide parameter values for the materials included in these tasks. Two codes, Code{_}Bright and Abaqus, have been employed for the tasks. The data qualification has focused on the bentonite material for buffer, backfill and the seals for tunnel plugs and bore-holes. All these system components have been treated as if they were based on MX-80 bentonite. The sources of information and documentation of the data qualification for the parameters for MX-80 have been listed. A substantial part of the refinement, especially concerning parameters used for Code{_}Bright, is presented in the report. The data qualification has been performed through a motivated and transparent chain; from measurements, via evaluations, to parameter determinations. The measured data was selected to be as recent, traceable and independent as possible. The data sets from this process are thus regarded to be qualified. The conditions for which the data is supplied, the conceptual uncertainties, the spatial and temporal variability and correlations are briefly presented and discussed. A more detailed discussion concerning the data uncertainty due to precision, bias and representativity is presented for measurements of swelling pressure, hydraulic conductivity, shear strength, retention properties and thermal conductivity. The results from the data qualification are presented as a detailed evaluation of measured data. In order to strengthen the relevance of the parameter values and to confirm previously used relations, either newer or independent measurements have been taken into account in the parameter value evaluation. Previously used relations for swelling pressure, hydraulic

  18. SR-Site Data report. THM modelling of buffer, backfill and other system components

    International Nuclear Information System (INIS)

    Aakesson, Mattias; Boergesson, Lennart; Kristensson, Ola

    2010-03-01

    This report is a supplement to the SR-Site data report. Based on the issues raised in the Process reports concerning THM processes in buffer, backfill and other system components, 22 modelling tasks have been identified, representing different aspects of the repository evolution. The purpose of this data report is to provide parameter values for the materials included in these tasks. Two codes, Code B right and Abaqus, have been employed for the tasks. The data qualification has focused on the bentonite material for buffer, backfill and the seals for tunnel plugs and bore-holes. All these system components have been treated as if they were based on MX-80 bentonite. The sources of information and documentation of the data qualification for the parameters for MX-80 have been listed. A substantial part of the refinement, especially concerning parameters used for Code B right, is presented in the report. The data qualification has been performed through a motivated and transparent chain; from measurements, via evaluations, to parameter determinations. The measured data was selected to be as recent, traceable and independent as possible. The data sets from this process are thus regarded to be qualified. The conditions for which the data is supplied, the conceptual uncertainties, the spatial and temporal variability and correlations are briefly presented and discussed. A more detailed discussion concerning the data uncertainty due to precision, bias and representativity is presented for measurements of swelling pressure, hydraulic conductivity, shear strength, retention properties and thermal conductivity. The results from the data qualification are presented as a detailed evaluation of measured data. In order to strengthen the relevance of the parameter values and to confirm previously used relations, either newer or independent measurements have been taken into account in the parameter value evaluation. Previously used relations for swelling pressure, hydraulic

  19. Mechanical and hydraulic behaviour of compacting crushed salt backfill at low porosities. Project REPOPERM. Phase 2

    Energy Technology Data Exchange (ETDEWEB)

    Kroehn, Klaus-Peter; Czaikowski, Oliver; Wieczorek, Klaus; Zhang, Chun-Liang; Moog, Helge; Friedenberg, Larissa [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) gGmbH, Koeln (Germany); Stuehrenberg, Dieter; Heemann, Ulrich [Bundesanstalt fuer Geowissenschaften und Rohstoffe (BGR), Hannover (Germany); Jobmann, Michael; Mueller, Christian; Schirmer, Sonja [DBE Technology GmbH (DBE TEC), Peine (Germany)

    2017-02-15

    The compaction behavior of crushed salt has been extensively investigated by means of experimental as well as theoretical work. The readiness of numerical tools for the application to modeling the complex coupled thermo-hydro-mechanical processes in the crushed salt backfilled in a repository in salt rock has also been demonstrated. Compaction tests were performed under repository-relevant conditions. These tests were supplemented by laboratory work aiming at specific aspects of compaction. The following list covers the topics of these investigations as well as the main results. - Revisiting the determination of the porosity in relevant, past experiments (BGR). - Influence of the grain size distribution on compaction (BGR). - Triaxial compaction test with dry material at low porosities (BGR). - Investigation of the influence of humidity on compaction covers several subtopics. - Permeability associated with low porosity includes two subtopics. - Constitutive equations for two -phase flow (GRS). - Microstructural Investigations (DBE TEC). Parallel to the experimental work attention focussed on several aspects of the basics for modelling the compaction of crushed salt. This work covers checking the validity of the established numerical tools as well as exploring new methods. Topics and main results are listed here: - Development/definition and comparison of constitutive models (BGR). - Benchmark calculations (BGR and GRS). - Capability of scaling-rules for capillary pressure from the oil industry (GRS). - Application of discrete element codes to compacting crushed salt (DBE TEC). Finally, repository-relevant scenarios are discussed as a basis for a realistic but generic numerical model of brine inflow in to a converging back filled drift under a thermal gradient (GRS). This exercise demonstrates the feasibility of modelling crushed salt compaction as a fully coupled thermohydraulic-mechanical process including two-phase flow effects.

  20. Hydro-mechanical behaviour of crushed COx argillite used as backfilling material in HLW repository

    International Nuclear Information System (INIS)

    Tang Chaosheng; Shi Bin; Cui Yujun; Anh-Minh Tang

    2010-01-01

    At present, the crushed Callovo-Oxfordian (COx) argillite powder is proposed as an alternative backfilling material in France, which will be constructed in the engineering barrier of high-level radioactive waste (HLW) repository. In this investigation, the compression behavior of two crushed COx argillite powders (coarser one and finer one) was studied by running l-D compression tests with several loading-unloading cycles. After the final dry density 2.0 g/cm 3 was reached, the specimen was flooding with distilled water and the evolution of axial stress was studied during saturation process. The effects of initial axial stress level and grain size distribution (GSD) on hydro-mechanical behaviour of compacted specimen were analyzed. The results show that the compression curves are significantly influenced by the GSD of the soils. To obtain the same degree of compaction, the axial stress applied to finer soil is much higher than that of coarser soil. In addition, the compression index of the finer soil is bigger than that of coarser soil. The swelling index at initial water content increases with the dry density and seems to be independent of the GSD. During saturation, the initial lower axial stress causes obvious swelling behavior for both the coarser and finer powder samples and the corresponding axial stress increase gradually. At initial higher axial stress condition, monotone collapse behavior is observed for the coarser powder samples. Whereas the axial stress decrease firstly, then increase and finally decrease again for the finer powder samples. After saturation, the equilibrium axial stresses of finer powder samples are higher than that of coarser powder samples. (authors)

  1. Strength and microstructure characteristics of the recycled rubber tire-sand mixtures as lightweight backfill.

    Science.gov (United States)

    Zhang, Tao; Cai, Guojun; Duan, Weihong

    2018-02-01

    The disposal of scrap rubber tires has induced critical environmental issue worldwide due to the rapid increase in the number of vehicles. Recycled scrap tires as a construction material in civil engineering have significant environmental benefits from a waste management perspective. A systematic study that deals with strength and microstructure characteristics of the rubber-sand mixtures is initiated, and mechanical response of the mixtures is discussed in this investigation. Experiments were conducted to evaluate the effects of rubber fraction on the basic properties including mass density (ρ), stress-strain characteristics, shear strength, and unconfined compression strength (q u ) of the rubber-sand mixtures. Additionally, scanning electron microscopy (SEM) was carried out to reveal the microstructure characteristics of the mixtures with various rubber fractions. A discussion on the micromechanics of the mixtures also was conducted. This study demonstrates that the ρ, friction angle, and q u decrease linearly with an increase in rubber fraction, whereas shear strain at peak increases. The stress-strain characteristics of the rubber-sand mixtures shift from brittle to ductile as the rubber fraction increase. These changes are attributed to remarkably lower stiffness and higher compressibility of the rubber particle compared with those of the conventional mineral aggregates. With an increase in the rubber fraction, the mechanical response of rubber-sand mixtures exhibits two types: sand-like material and rubber-like material. Rubber particle possesses the capacity to prevent the contacted sand particles from sliding at lower rubber fraction, whereas it transmits the applied loadings as the rubber fraction increased. This outcome reinforces the practicability of using recycled rubber tire-sand mixtures as a lightweight backfill in subbase/base applications.

  2. Protocol for characterization of clay as a backfill and coverage layers for surface repository

    International Nuclear Information System (INIS)

    Santos, Daisy M.M.; Tello, Clédola C.O.

    2017-01-01

    The Radioactive Waste Management includes the operations since generation of the waste until its storage in repository, ensuring the protection of human beings and the environment from the possible negative impacts. The radioactive waste is segregated, treated, conditioned in suitable packages for posterior storage or disposal in repository. The 'RBMN Project' objective is to implement the repository for the disposal of low and intermediate level radioactive wastes generated by nuclear activities in Brazil, proposing a definitive solution for their storage. Engineered and natural barriers as the backfill and coverage layers will compose the disposal system of a near surface repository, concept proposed by the 'RBMN Project'. The use of these barriers aims to avoid or restrict the release of radionuclides from the waste to the human beings and environment. The waterproofing barriers are composed of clays. Certainly, for the national repository, will be used those clays existing in the place where it will be constructed. Them some basic tests will have to be carried out to verify the suitability of these clays as barriers. These tests were determined and performed with reference clay, a Brazilian bentonite constituted of 67.2% montmorillonite. The results were compared with national and international literature of materials with similar mineralogical features. The values found with 95% of confidence interval were 9.73±0,35 μm for granulometric size; 13,3±0,6% for the moisture content and 816±9 mmol.kg -1 for the capacity of cationic exchange. A protocol for characterization of clay was elaborated presenting these tests for it future use. (author)

  3. Protocol for characterization of clay as a backfill and coverage layers for surface repository

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Daisy M.M.; Tello, Clédola C.O., E-mail: marymarchezini@gmail.com, E-mail: tellocc@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2017-07-01

    The Radioactive Waste Management includes the operations since generation of the waste until its storage in repository, ensuring the protection of human beings and the environment from the possible negative impacts. The radioactive waste is segregated, treated, conditioned in suitable packages for posterior storage or disposal in repository. The 'RBMN Project' objective is to implement the repository for the disposal of low and intermediate level radioactive wastes generated by nuclear activities in Brazil, proposing a definitive solution for their storage. Engineered and natural barriers as the backfill and coverage layers will compose the disposal system of a near surface repository, concept proposed by the 'RBMN Project'. The use of these barriers aims to avoid or restrict the release of radionuclides from the waste to the human beings and environment. The waterproofing barriers are composed of clays. Certainly, for the national repository, will be used those clays existing in the place where it will be constructed. Them some basic tests will have to be carried out to verify the suitability of these clays as barriers. These tests were determined and performed with reference clay, a Brazilian bentonite constituted of 67.2% montmorillonite. The results were compared with national and international literature of materials with similar mineralogical features. The values found with 95% of confidence interval were 9.73±0,35 μm for granulometric size; 13,3±0,6% for the moisture content and 816±9 mmol.kg{sup -1} for the capacity of cationic exchange. A protocol for characterization of clay was elaborated presenting these tests for it future use. (author)

  4. Mechanical and hydraulic behaviour of compacting crushed salt backfill at low porosities. Project REPOPERM. Phase 2

    International Nuclear Information System (INIS)

    Kroehn, Klaus-Peter; Czaikowski, Oliver; Wieczorek, Klaus; Zhang, Chun-Liang; Moog, Helge; Friedenberg, Larissa; Stuehrenberg, Dieter; Heemann, Ulrich; Jobmann, Michael; Mueller, Christian; Schirmer, Sonja

    2017-02-01

    The compaction behavior of crushed salt has been extensively investigated by means of experimental as well as theoretical work. The readiness of numerical tools for the application to modeling the complex coupled thermo-hydro-mechanical processes in the crushed salt backfilled in a repository in salt rock has also been demonstrated. Compaction tests were performed under repository-relevant conditions. These tests were supplemented by laboratory work aiming at specific aspects of compaction. The following list covers the topics of these investigations as well as the main results. - Revisiting the determination of the porosity in relevant, past experiments (BGR). - Influence of the grain size distribution on compaction (BGR). - Triaxial compaction test with dry material at low porosities (BGR). - Investigation of the influence of humidity on compaction covers several subtopics. - Permeability associated with low porosity includes two subtopics. - Constitutive equations for two -phase flow (GRS). - Microstructural Investigations (DBE TEC). Parallel to the experimental work attention focussed on several aspects of the basics for modelling the compaction of crushed salt. This work covers checking the validity of the established numerical tools as well as exploring new methods. Topics and main results are listed here: - Development/definition and comparison of constitutive models (BGR). - Benchmark calculations (BGR and GRS). - Capability of scaling-rules for capillary pressure from the oil industry (GRS). - Application of discrete element codes to compacting crushed salt (DBE TEC). Finally, repository-relevant scenarios are discussed as a basis for a realistic but generic numerical model of brine inflow in to a converging back filled drift under a thermal gradient (GRS). This exercise demonstrates the feasibility of modelling crushed salt compaction as a fully coupled thermohydraulic-mechanical process including two-phase flow effects.

  5. Characterization of a backfill candidate material, IBECO-RWC-BF Baclo Project - Phase 3 Laboratory tests

    Energy Technology Data Exchange (ETDEWEB)

    Johannesson, Lars-Erik; Sanden, Torbjoern; Dueck, Ann; Ohlsson, Lars (Clay Technology AB, Lund (Sweden))

    2010-01-15

    A backfill candidate material, IBECO-RWC-BF, which origin from Milos, Greece, has been investigated. The material was delivered both as granules and as pellets. The investigation described in this report aimed to characterize the material and evaluate if it can be used in a future repository. The following investigations have been done and are presented in this report: 1. Standard laboratory tests. Water content, liquid limit and swelling potential are examples on standard tests that have been performed. 2. Block manufacturing. The block compaction properties of the material have been determined. A first test was performed in laboratory but also tests in large scale have been performed. After finishing the test phase, 60 tons of blocks were manufactured at Hoeganaes Bjuf AB. The blocks will be used in large scale laboratory tests at Aespoe HRL. 3. Mechanical parameters. The compressibility of the material was investigated with oedometer tests (four tests) where the load was applied in steps after saturation. The evaluated oedometer modulus varied between 34.50 MPa. Tests were made to evaluate the elastic parameters of the material (E, nu). Altogether three tests were made on specimens with dry densities of about 1,710 kg/m3. The evaluated E-modulus and Poisson's ratio varied between 231-263 MPa and 0.16-0.19 respectively. The strength of the material, both the compressive strength and the tensile strength were measured on specimens compacted to different dry densities. The test results yielded a relation between density and the two types of strength. Furthermore, tests have been made in order to determine the compressibility of the unsaturated filling of pellets. Two tests were made where the pellets were loosely filled in a Proctor cylinder and then compressed at a constant rate of strain during continuously measurement of the applied load. 4. Swelling pressure and hydraulic conductivity. There is, as expected, a very clear influence of the dry density on the

  6. Deep repository - engineered barrier systems. Half scale tests to examine water uptake by bentonite pellets in a block-pellet backfill system

    International Nuclear Information System (INIS)

    Dixon, David; Lundin, Cecilia; Oertendahl, Ellinor; Hedin, Mikael; Ramqvist, Gunnar

    2008-12-01

    In order to examine the behaviour of water entering a section of tunnel that had recently been backfilled using a combination of bentonite pellets and compacted, smectitic clay blocks, a series of large-scale tests have been completed. These tests, done at a scale of approximately 0.5 that of an emplacement tunnel were completed in a mock-up constructed in the Buffer Laboratory at SKB's Aespoe Hard Rock Laboratory. A total of 12 tests, undertaken under well controlled conditions were completed, examining the effects of inflow rate, inflow location and time on assemblies of blocks and pellets. Water was supplied to the assembly at rates ranging from 0.1 to 2.5 l/min and the time for water exit, the exit location, potential for erosion of backfill, the rate of water uptake and resistance of the assembly to water influx were all monitored for periods of 3 to 7 days. The testing time was selected to simulate a reasonable duration for unanticipated backfilling interruption. Longer durations were not necessary and risked both the stability of the system and the loss of the early stage conditions through progression of swelling and homogenization. Testing determined that initial water movement through backfill is largely controlled by the pellets. Water influx of up to 30 l/h at a single location was diverted by the pellets forming essentially horizontal flow channels (pipes) along the chamber wall - pellet interface. These piping features directed the majority of the incoming water around the backfill and towards the unconfined downstream face of the assembly. The time required for the water to exit the assembly was dependant on a combination of inflow rate and distance that it needed to travel. Water typically exited the face of the backfill at well-defined location(s) and once established, these features remained for the duration of the test. The exiting water typically carried only limited eroded material but could cause some disruption of the downstream face of the

  7. Deep repository - engineered barrier systems. Half scale tests to examine water uptake by bentonite pellets in a block-pellet backfill system

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, David (Atomic Energy of Canada Limited (AECL) (Canada)); Lundin, Cecilia (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)); Oertendahl, Ellinor (NCC (Sweden)); Hedin, Mikael (Aangpannefoereningen, Stockholm (Sweden)); Ramqvist, Gunnar (Eltekno AB (Sweden))

    2008-12-15

    In order to examine the behaviour of water entering a section of tunnel that had recently been backfilled using a combination of bentonite pellets and compacted, smectitic clay blocks, a series of large-scale tests have been completed. These tests, done at a scale of approximately 0.5 that of an emplacement tunnel were completed in a mock-up constructed in the Buffer Laboratory at SKB's Aespoe Hard Rock Laboratory. A total of 12 tests, undertaken under well controlled conditions were completed, examining the effects of inflow rate, inflow location and time on assemblies of blocks and pellets. Water was supplied to the assembly at rates ranging from 0.1 to 2.5 l/min and the time for water exit, the exit location, potential for erosion of backfill, the rate of water uptake and resistance of the assembly to water influx were all monitored for periods of 3 to 7 days. The testing time was selected to simulate a reasonable duration for unanticipated backfilling interruption. Longer durations were not necessary and risked both the stability of the system and the loss of the early stage conditions through progression of swelling and homogenization. Testing determined that initial water movement through backfill is largely controlled by the pellets. Water influx of up to 30 l/h at a single location was diverted by the pellets forming essentially horizontal flow channels (pipes) along the chamber wall - pellet interface. These piping features directed the majority of the incoming water around the backfill and towards the unconfined downstream face of the assembly. The time required for the water to exit the assembly was dependant on a combination of inflow rate and distance that it needed to travel. Water typically exited the face of the backfill at well-defined location(s) and once established, these features remained for the duration of the test. The exiting water typically carried only limited eroded material but could cause some disruption of the downstream face of

  8. Evaluation for swelling characteristics of buffer and backfill materials for high-level nuclear waste disposal. Influence of sand-bentonite content and cation compositions in bentonite

    International Nuclear Information System (INIS)

    Komine, Hideo; Ogata, Nobuhide

    1999-01-01

    Compacted bentonite and sand-bentonite mixture are attracting greater attention as buffer and backfill materials for disposal pits and access tunnels in the underground facilities for repositories of high-level nuclear waste. Buffer and backfill materials must have the swelling characteristics and are expected to fill up the space between these materials and surrounding ground by swelling. This role is called as 'Self-sealing'. To design the specifications, such as dry density, bentonite content and size, of buffer and backfill materials for the disposal facilities of high-level nuclear wastes described above, we must evaluate the swelling characteristics of compacted bentonite and sand-bentonite mixtures. For this purpose, this study proposed the evaluation formula for swelling characteristics of buffer and backfill materials containing bentonite. This study derived new equations for evaluating the relationship between the swelling deformation of compacted bentonite and sand-bentonite mixtures, and the swelling behavior of montmorillonite minerals, which are swelling clay minerals. This study also proposed new equations for evaluating the ion compositions of bentonite, ion concentration of pore water and the specific surface of bentonite, which significantly influence the swelling characteristics of buffer and backfill materials. The evaluation formula proposed in this study is presented by combining the above-mentioned new equations with theoretical equations, of which are the Gouy-Chapman diffuse double layer theory and the van der Waals force, of repulsive and attractive forces of montmorillonite minerals. (author)

  9. Application of mine water leaching protocol on coal fly ash to assess leaching characteristics for suitability as a mine backfill material.

    Science.gov (United States)

    Madzivire, Godfrey; Ramasenya, Koena; Tlowana, Supi; Coetzee, Henk; Vadapalli, Viswanath R K

    2018-04-16

    Over the years, coal mining in the Mpumalanga Province of South Africa has negatively affected the environment by causing pollution of water resources, land subsidence and spontaneous coal combustion. Previous studies show that in-situ treatment of acid mine drainage (AMD) using coal fly ash (CFA) from local power stations was possible and sludge recovered out of such treatment can be used to backfill mines. In this article, the authors have attempted to understand the leaching characteristics of CFA when placed underground as a backfill material using the mine water leaching protocol (MWLP). The results show that the migration of contaminants between the coal fly ash and the AMD in the mine voids depends on the pH and quality of the mine water. While backfilling mine voids with CFA can neutralize and scavenge between 50% and 95% of certain environmentally sensitive elements from AMD such as Fe, Al, Zn, Cu, Ni, Co and Mn. At this moment, it is also important to point out that certain scavenged/removed contaminants from the AMD during initial phases of backfilling can be remobilized by the influx of acidic water into the mine voids. It has therefore been concluded that, while CFA can be used to backfill mine voids, the influx of fresh acidic mine water should be avoided to minimize the remobilization of trapped contaminants such as Fe, Al, Mn and As. However, the pozzolanic material resulting from the CFA-AMD interaction could prevent such influx.

  10. SORPTION AND DISPERSION OF STRONTIUM RADIONUCLIDE IN THE BENTONITE-QUARTZ-CLAY AS BACKFILL MATERIAL CANDIDATE ON RADIOACTIVE WASTE REPOSITORY

    Directory of Open Access Journals (Sweden)

    Herry Poernomo

    2010-12-01

    Full Text Available The experiment of sorption and dispersion characteristics of strontium in the mixture of bentonite-quartz, clay-quartz, bentonite-clay-quartz as candidate of raw material for backfill material in the radioactive waste repository has been performed. The objective of this research is to know the grain size effect of bentonite, clay, and quartz on the weight percent ratio of bentonite to quartz, clay to quartz, bentonite to clay to-quartz can be gives physical characteristics of best such as bulk density (rb, effective porosity (e, permeability (K, best sorption characteristic such as distribution coefficient (Kd, and best dispersion characteristics such as dispersivity (a and effective dispersion coefficient (De of strontium in the backfill material candidate. The experiment was carried out in the column filled by the mixture of bentonite-quartz, clay-quartz, bentonite-clay-quartz with the weight percent ratio of bentonite to quartz, clay to quartz, bentonite to clay to quartz of 100/0, 80/20, 60/40, 40/60, 20/80, 0/100 respectively at saturated condition of water, then flowed 0.1 N Sr(NO32 as buffer solution with tracer of 0.05 Ci/cm3 90Sr as strontium radionuclide simulation was leached from immobilized radioactive waste in the radioactive waste repository. The concentration of 90Sr in the effluents represented as Ct were analyzed by Ortec b counter every 30 min, then by using profile concentration of Co and Ct, values of Kd, a and De of 90Sr in the backfill material was determined. The experiment data showed that the best results were -80+120 mesh grain size of bentonite, clay, quartz respectively on the weight percent ratio of bentonite to clay to quartz of 70/10/20 with physical characteristics of rb = 0.658 g/cm3, e = 0.666 cm3/cm3, and K = 1.680x10-2 cm/sec, sorption characteristic of Kd = 46.108 cm3/g, dispersion characteristics of a = 5.443 cm, and De = 1.808x10-03 cm2/sec can be proposed as candidate of raw material of backfill material

  11. Performance of backfill materials in near surface disposal facilities for low and intermediate level radwaste. Appendix 4: China (a)

    International Nuclear Information System (INIS)

    Cunli, G.; Yawen, H.; Zhiwen, F.; Anxi, C.; Xiuzhen, L.; Jinsheng, Z.

    2001-01-01

    Full text: Backfill material is an important component of a multi-barriered disposal facility for low and intermediate level radioactive waste. This appendix describes the work concerning 'performance study on engineering materials of shallow land disposal of low and intermediate level radwaste'. At the time of the CRP, China had planned to establish five regional disposal sites for low-and-intermediate level radioactive waste. According to the potential distribution of these sites, forty-three sampling points were selected through information survey and table discussion. After field survey and screening, eight of them were selected for further studies in laboratory. Basic physical and chemical properties of each sample were measured in laboratory. The results indicate that no one of the samples can individually function as the backfill material in a multi-barriered near surface facility. Then nine additives for adsorption modification were tested using a static method. Further adsorption tests were conducted: three additives screened out in previous experiment were evaluated using the static method. Results obtained show that the Kd values of mixtures of 90% NW-3 and 10% BC for Co-60, Cs-134 and Sr-85, compared with those of 100% NW-3, are 4.8, 4.6 and 4.7 times higher, respectively. Effects of contact time, pH of tracer solutions and radionuclide concentrations of tracer solutions on Kd values of three samples, NW-3, BC and 90% NW-3 with 10% BC, were also be evaluated using the static method. Column tests were performed to evaluate migration of Co-60, Cs-134 and Sr-85 in NW-3 columns with different densities. The column tests were carried out for 210 days. However, no breakthrough was obtained. Long term performance of backfill materials was assessed through natural analogue. We compared Chinese ancient tombs with near-surface low and intermediate level radioactive waste (LILW) disposal facilities. Both were designed based upon multi-barrier principle. Then three

  12. Sodium Silicate Gel Effect on Cemented Tailing Backfill That Contains Lead-Zinc Smelting Slag at Early Ages

    OpenAIRE

    Guo, Lijie; Li, Wenchen; Yang, Xiaocong; Xu, Wenyuan

    2018-01-01

    This paper presents the results of an experimental study on the priming effect of sodium silicate gel (SS) on cemented tailing backfill (CTB) that contains lead-zinc smelting slag. CTB and cemented paste (CP) containing lead-zinc smelting slag samples with SS of 0 and 0.4% of the mass of the slag were prepared and cured at 20°C for 1, 3, 7, and 28 days. Mechanical test and pore structure analyses were performed on the studied CTB samples, microstructural analyses (X-ray diffraction analysis a...

  13. A new approach for helium backfilling and leak testing seal-welded capsules in a hot cell

    International Nuclear Information System (INIS)

    Strasslsund, E.K.; Berger, D.N.

    1992-05-01

    Gamma irradiation sources containing radioactive 137 Cesium Chloride are being produced at the US Department of Energy's Hanford Site as part of a Westinghouse Hanford company/Pacific Northwest Laboratory cooperative program. New equipment was developed to leak test the double-encapsulated sources in a hot cell. The equipment, which includes a helium backfill chamber and end cap press , a vacuum chamber, and a helium mass spectrometer, has provided technicians with the capability to detect leaks in sealed sources as small as 1. 0x10 -7 atm cm 3 /S helium

  14. Pressurized grout remote backfilling at AML sites near Beulah and Zap, North Dakota

    International Nuclear Information System (INIS)

    Weiner, E.J.; Dodd, W.E.

    1999-01-01

    The Abandoned Mine Lands (AML) Division of the North Dakota Public Service Commission (PSC) is charged with the reclamation of hazardous abandoned mine sites in North Dakota. Several underground lignite coalmines were operated near the cities of Beulah and Zap, North Dakota, from the early 1900's until about 1955. Coal seams in this area were relatively thick and the overburden generally shallow. As these mines have deteriorated with time, deep collapse features, or sinkholes, have surfaced in many areas. These features are very dangerous, especially when they occur at or near residential and commercial areas and public roads. In the past five years, sinkholes have surfaced beneath a commercial building (boat dealership, lounge, and gas station) and beneath a nearby occupied mobile home north of Beulah. sinkholes have also surfaced near KHOL Radio Station in Beulah and in the right of way of a public road south of Zap. The AML Division has conducted several emergency sinkhole-filling projects in these areas. In 1995--97, the AML Division conducted exploratory drilling which confirmed the presence of collapsing underground mines at these sites. The remediation of these sites around Beulah/Zap will take place over several years and involve three or more separate contracts due to budget considerations. In 1997, the AML Division began reclamation at these sties utilizing pressurized grout remote backfilling. In this technique, a cementitious grout is pumped through cased drill holes directly into the mine cavities to fill them and thereby stabilize the surface from collapse. The successful contractor for Phase One of the project was The Concrete Doctor, Inc. (TCDI). This paper will concentrate on Phase One of this work performed from June through September 1997. This project is especially interesting because grout was pumped through holes drilled inside the occupied commercial building. Grout was also pumped through angled holes that intercepted mined workings directly

  15. Pressurized grout remote backfilling at AML sites near Beulah and Zap, North Dakota

    Energy Technology Data Exchange (ETDEWEB)

    Weiner, E.J.; Dodd, W.E.

    1999-07-01

    The Abandoned Mine Lands (AML) Division of the North Dakota Public Service Commission (PSC) is charged with the reclamation of hazardous abandoned mine sites in North Dakota. Several underground lignite coalmines were operated near the cities of Beulah and Zap, North Dakota, from the early 1900's until about 1955. Coal seams in this area were relatively thick and the overburden generally shallow. As these mines have deteriorated with time, deep collapse features, or sinkholes, have surfaced in many areas. These features are very dangerous, especially when they occur at or near residential and commercial areas and public roads. In the past five years, sinkholes have surfaced beneath a commercial building (boat dealership, lounge, and gas station) and beneath a nearby occupied mobile home north of Beulah. sinkholes have also surfaced near KHOL Radio Station in Beulah and in the right of way of a public road south of Zap. The AML Division has conducted several emergency sinkhole-filling projects in these areas. In 1995--97, the AML Division conducted exploratory drilling which confirmed the presence of collapsing underground mines at these sites. The remediation of these sites around Beulah/Zap will take place over several years and involve three or more separate contracts due to budget considerations. In 1997, the AML Division began reclamation at these sties utilizing pressurized grout remote backfilling. In this technique, a cementitious grout is pumped through cased drill holes directly into the mine cavities to fill them and thereby stabilize the surface from collapse. The successful contractor for Phase One of the project was The Concrete Doctor, Inc. (TCDI). This paper will concentrate on Phase One of this work performed from June through September 1997. This project is especially interesting because grout was pumped through holes drilled inside the occupied commercial building. Grout was also pumped through angled holes that intercepted mined workings

  16. The solubility of nickel and its migration through the cementitious backfill of a geological disposal facility for nuclear waste.

    Science.gov (United States)

    Felipe-Sotelo, M; Hinchliff, J; Field, L P; Milodowski, A E; Holt, J D; Taylor, S E; Read, D

    2016-08-15

    This work describes the solubility of nickel under the alkaline conditions anticipated in the near field of a cementitious repository for intermediate level nuclear waste. The measured solubility of Ni in 95%-saturated Ca(OH)2 solution is similar to values obtained in water equilibrated with a bespoke cementitious backfill material, on the order of 5×10(-7)M. Solubility in 0.02M NaOH is one order of magnitude lower. For all solutions, the solubility limiting phase is Ni(OH)2; powder X-ray diffraction and scanning transmission electron microscopy indicate that differences in crystallinity are the likely cause of the lower solubility observed in NaOH. The presence of cellulose degradation products causes an increase in the solubility of Ni by approximately one order of magnitude. The organic compounds significantly increase the rate of Ni transport under advective conditions and show measurable diffusive transport through intact monoliths of the cementitious backfill material. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Initial field testing definition of subsurface sealing and backfilling tests in unsaturated tuff; Yucca Mountain Site Characterization Project

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, J.A. [Sandia National Labs., Albuquerque, NM (United States); Case, J.B.; Tyburski, J.R. [I. T. Corp., Albuquerque, NM (United States)

    1993-05-01

    This report contains an initial definition of the field tests proposed for the Yucca Mountain Project repository sealing program. The tests are intended to resolve various performance and emplacement concerns. Examples of concerns to be addressed include achieving selected hydrologic and structural requirements for seals, removing portions of the shaft liner, excavating keyways, emplacing cementitious and earthen seals, reducing the impact of fines on the hydraulic conductivity of fractures, efficient grouting of fracture zones, sealing of exploratory boreholes, and controlling the flow of water by using engineered designs. Ten discrete tests are proposed to address these and other concerns. These tests are divided into two groups: Seal component tests and performance confirmation tests. The seal component tests are thorough small-scale in situ tests, the intermediate-scale borehole seal tests, the fracture grouting tests, the surface backfill tests, and the grouted rock mass tests. The seal system tests are the seepage control tests, the backfill tests, the bulkhead test in the Calico Hills unit, the large-scale shaft seal and shaft fill tests, and the remote borehole sealing tests. The tests are proposed to be performed in six discrete areas, including welded and non-welded environments, primarily located outside the potential repository area. The final selection of sealing tests will depend on the nature of the geologic and hydrologic conditions encountered during the development of the Exploratory Studies Facility and detailed numerical analyses. Tests are likely to be performed both before and after License Application.

  18. Characterisation of bentonites from Kutch, India and Milos, Greece - some candidate tunnel back-fill materials?

    International Nuclear Information System (INIS)

    Olsson, Siv; Karnland, Ola

    2009-12-01

    During the past decades comprehensive investigations have been made on bentonite clays in order to find optimal components of the multi-barrier system of repositories for radioactive waste. The present study gives a mineralogical characterisation of some selected bentonites, in order to supply some of the necessary background data on the bentonites for evaluating their potential as tunnel back-fill materials. Two bentonites from the island of Milos, Greece (Milos BF 04 and BF 08), and two bentonites from Kutch, India (Kutch BF 04 and BF 08) were analysed for their grain size distribution, cation exchange properties and chemical composition. The mineralogical composition was determined by X-ray diffraction analysis and evaluated quantitatively by use of the Siroquant software. Both the bulk bentonite and the 63 μm. The bentonite is distinguished by a high content of dolomite and calcite, which make up almost 25% of the bulk sample. The major accessory minerals are K-feldspars and plagioclase, whereas the content of sulphur-bearing minerals is very low (0.06% total S). Smectite makes up around 60% of the bulk sample, which has a CEC value of 73 meq/100 g. The pool of interlayer cations has a composition Mg>Ca>>Na>>K. The X-ray diffraction characteristics and the high potassium content (1.03% K 2 O) of the Na>Mg>>K. The 2 O) which indicates that also this smectite may be interstratified with a few percent illitic layers. Based on the charge distribution the smectite should be classified as montmorillonite but in this case Fe predominates over Mg in the octahedral sheet. The structural formula suggests that this smectite has the lowest total layer charge of the smectites examined. Kutch BF 04 contains essentially no particles >63 μm. The bentonite has a high content of titanium and iron-rich accessory minerals, such as anatase, magnetite, hematite and goethite. Other accessory minerals of significance are feldspars and quartz, whereas the content of sulphur

  19. Use of the mixture of clay and crushed rock as a backfill material for low and intermediate level radioactive waste repository. Appendix 10: Republic of Korea

    International Nuclear Information System (INIS)

    Cho, W.J.; Lee, J.O.; Hahn, P.S.; Chun, K.S.

    2001-01-01

    At the time of the CRP, a repository for low and intermediate level radioactive wastes arising from nuclear power plant operation and radioisotope application in the Republic of Korea was to be constructed in the bedrock below ground surface. As the intermediate level waste cavern would contain the major part of radionuclide inventory in the cavern, the radionuclide release from the intermediate level waste cavern was therefore important from the viewpoint of disposal facility performance. The then current design concept suggested that the intermediate level waste would be emplaced into the compartment made of reinforced concrete, and the space between the concrete wall and cavern surface would be backfilled with a clay-based material. As compacted clay-based materials have a low hydraulic conductivity and the hydraulic gradient in a disposal cavern was expected to be relatively low, molecular diffusion was considered to be the principal mechanism by which radionuclides would migrate through the backfill. The mixture of calcium bentonite and crushed rock was being suggested as a candidate backfill material. This appendix summarises the KAERI research activities on the evaluation of hydraulic conductivity, radionuclide diffusion coefficient, and mechanical properties of the candidate clay-based backfill material for the intermediate level waste cavern

  20. The in-situ experiment for performance confirmation of engineered barrier system at Horonobe Underground Research Laboratory. Examination of backfill material using muck from URL construction

    International Nuclear Information System (INIS)

    Nakayama, Masashi; Ohno, Hirokazu; Tanai, Kenji; Fujita, Tomoo; Sugita, Yutaka

    2016-06-01

    The Horonobe Underground Research Laboratory (URL) Project has being pursued by Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, northern Hokkaido. The URL Project consists of two major research areas, “Geoscientific Research” and “Research and Development on Geological Disposal Technologies”, and proceeds in three overlapping phases, “Phase I: Surface-based investigations”, “Phase II: Investigations during tunnel excavation” and “Phase III: Investigations in the underground facilities”, over a period of around 20 years. Phase III investigation was started in 2010 fiscal year. The in-situ experiment for performance confirmation of engineered barrier system (EBS experiment) was prepared from 2013 to 2014 fiscal year at G.L.-350m gallery (Niche No.4), and heating by electric heater in simulated overpack started in January, 2015. One of objectives of the experiment is acquiring data concerned with Thermal – Hydrological – Mechanical – Chemical (THMC) coupled behavior. These data will be used in order to confirm the performance of engineered barrier system. In EBS experiment, the backfill material using mixture of bentonite and muck from Horonobe URL construction was used for backfilling a part of Niche No.4. This report shows the results of properties of the backfill material, confirmation test of compaction method and making backfill material block, and so on. From these results, it was confirmed that the backfill material would satisfy target value of the permeability and the swelling pressure. (author)

  1. The influence of the presence of sulphate on methanogenesis in the backfill of a Canadian nuclear fuel waste disposal vault: a laboratory study

    International Nuclear Information System (INIS)

    Sheppard, M.I.; Stroes-Gascoyne, S.; Motycka, M.; Haveman, S.A.

    1997-09-01

    Microbial gas production in the clay-based buffer and backfill materials of a nuclear waste disposal vault could produce gas bubbles or a separate gas phase, depending on quantities produced and the kinetics of the process. Gas production may affect the performance of the clay-based barriers. Results from previous laboratory experiments suggested that the presence of backfill or backfill clay prevented methane production in groundwater systems, likely because of inherently high sulphate concentrations in the clay. The work presented here shows that methane production in groundwater/clay systems is possible, but only at sulphate concentrations <35 mg/L. Sulphate concentrations in laboratory systems were lowered by the addition of Ba, and also by natural (microbiological or chemical) processes occurring over time (almost 700 d). Nutrient additions (acetate, diesel fuel) appeared to increase the magnitude of methane production but not necessarily speed the onset of methanogenesis. A high pH did not reduce or enhance methanogenesis, and the role of Fe in creating suitable conditions was not clear. Methane production rates in laboratory systems containing groundwater and backfill or backfill clay ranged from 0.1 to 0.125 mole%/d. In the presence of Ba-acetate, a rate as high as 0.7 mole%/d was observed. It is recommended that all microbial gas production experiments be continued for an adequate period of time, because of the considerable time required to develop suitable conditions for methanogenesis in laboratory systems. Methane production rates in water-limited clay environments, such as those expected in a nuclear fuel waste disposal vault, are needed as well as modelling of methane production for incorporation into vault performance optimization and safety assessments. (author)

  2. The influence of the presence of sulphate on methanogenesis in the backfill of a Canadian nuclear fuel waste disposal vault: a laboratory study

    Energy Technology Data Exchange (ETDEWEB)

    Sheppard, M I; Stroes-Gascoyne, S; Motycka, M; Haveman, S A

    1997-09-01

    Microbial gas production in the clay-based buffer and backfill materials of a nuclear waste disposal vault could produce gas bubbles or a separate gas phase, depending on quantities produced and the kinetics of the process. Gas production may affect the performance of the clay-based barriers. Results from previous laboratory experiments suggested that the presence of backfill or backfill clay prevented methane production in groundwater systems, likely because of inherently high sulphate concentrations in the clay. The work presented here shows that methane production in groundwater/clay systems is possible, but only at sulphate concentrations <35 mg/L. Sulphate concentrations in laboratory systems were lowered by the addition of Ba, and also by natural (microbiological or chemical) processes occurring over time (almost 700 d). Nutrient additions (acetate, diesel fuel) appeared to increase the magnitude of methane production but not necessarily speed the onset of methanogenesis. A high pH did not reduce or enhance methanogenesis, and the role of Fe in creating suitable conditions was not clear. Methane production rates in laboratory systems containing groundwater and backfill or backfill clay ranged from 0.1 to 0.125 mole%/d. In the presence of Ba-acetate, a rate as high as 0.7 mole%/d was observed. It is recommended that all microbial gas production experiments be continued for an adequate period of time, because of the considerable time required to develop suitable conditions for methanogenesis in laboratory systems. Methane production rates in water-limited clay environments, such as those expected in a nuclear fuel waste disposal vault, are needed as well as modelling of methane production for incorporation into vault performance optimization and safety assessments. (author) 30 refs., 6 tabs., 27 figs.

  3. Effect of desliming of sulphide-rich mill tailings on the long-term strength of cemented paste backfill.

    Science.gov (United States)

    Ercikdi, Bayram; Baki, Hakan; İzki, Muhammet

    2013-01-30

    This paper presents the effect of desliming on the short- and long-term strength, stability and rheological properties of cemented paste backfill (CPB) produced from two different mill tailings. A 28-day unconfined compressive strength (UCS) of ≥1.0 MPa and the maintenance of stability over 224 days of curing were selected as the design criteria for the evaluation of paste backfill performance. Desliming induced some changes in the physical, chemical, mineralogical and rheological properties of the tailings. CPB mixture of the deslimed tailings achieved the required consistency at a lower water to cement ratio. The short-term UCSs of CPB samples of the deslimed tailings were found to be 30-100% higher than those samples of the reference tailings at all the binder dosages and curing times. CPB samples of the deslimed tailings achieved the long-term stability at relatively low binder dosages (e.g. 5 wt% c.f. ≥6.1% for the reference tailings). It was also estimated that desliming could allow a 13.4-23.1% reduction in the binder consumption depending apparently on the inherent characteristics of the tailings. Over the curing period, generation of sulphate and acid by the oxidation of pyrite present in the tailings was also monitored to correlate with the strength losses observed in the long term. Scanning electron microscope (SEM) and Mercury Intrusion Porosimetry (MIP) analyses provided an insight into the microstructure of CPB and the formation of secondary mineral phases (i.e. gypsum) confirming the beneficial effect of desliming. These findings suggest that desliming can be suitably exploited for CPB of sulphide-rich mill tailings to improve the strength and stability particularly in the long term and to reduce binder consumption. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Characterisation of bentonites from Kutch, India and Milos, Greece - some candidate tunnel back-fill materials?

    Energy Technology Data Exchange (ETDEWEB)

    Olsson, Siv; Karnland, Ola (Clay Technology AB, Lund (Sweden))

    2009-12-15

    During the past decades comprehensive investigations have been made on bentonite clays in order to find optimal components of the multi-barrier system of repositories for radioactive waste. The present study gives a mineralogical characterisation of some selected bentonites, in order to supply some of the necessary background data on the bentonites for evaluating their potential as tunnel back-fill materials. Two bentonites from the island of Milos, Greece (Milos BF 04 and BF 08), and two bentonites from Kutch, India (Kutch BF 04 and BF 08) were analysed for their grain size distribution, cation exchange properties and chemical composition. The mineralogical composition was determined by X-ray diffraction analysis and evaluated quantitatively by use of the Siroquant software. Both the bulk bentonite and the <1mum fraction were analyzed when relevant. Prior to the chemical analyses the <1 mum fractions were converted to homo-ionic clays and purified by dialysis. The chemical data were used for calculating the structural formula of the smectites. Milos BF 04 contains ca. 10% particles >63 mum. The bentonite is distinguished by a high content of dolomite and calcite, which make up almost 25% of the bulk sample. The major accessory minerals are K-feldspars and plagioclase, whereas the content of sulphur-bearing minerals is very low (0.06% total S). Smectite makes up around 60% of the bulk sample, which has a CEC value of 73 meq/100 g. The pool of interlayer cations has a composition Mg>Ca>>Na>>K. The X-ray diffraction characteristics and the high potassium content (1.03% K{sub 2}O) of the <1 mum fraction suggest that the smectite is interstratified with ca. 10% illitic layers. Based on the charge distribution the smectite should be classified as montmorillonite and according to the structural formula, Mg predominates over Fe in the octahedral sheet. However, remnants of Mg-carbonates, if present, may be a source of error in the formula calculation. Milos BF 08 has a

  5. Large-scale Experiment for Water and Gas Transport in Cementitious Backfill Materials (Phase 1 ): COLEX I

    International Nuclear Information System (INIS)

    Mayer, G.; Wittmann, F.H.; Moetsch, H.A.

    1998-05-01

    In the planned Swiss repository for low- and intermediate-level radioactive waste, the voids between the waste containers will be backfilled with a highly permeable mortar (NAGRA designation: mortar M1 ). As well as providing mechanical stability through filling of voids and sorbing radionuclides, the mortar must divert gases formed in the repository as a result of corrosion into the neighbouring host rock. This will prevent damage which could be caused by excess pressure on the repository structures. Water transport, which is coupled to gas transport, is also of interest. The former is responsible for the migration of radionuclides. Up till now, numerical simulations for a repository situation were carried out using transport parameters determined for small samples in the laboratory. However, the numerical simulations still had to be validated by a large-scale experiment. The investigations presented here should close this gap. Investigations into gas and water transport were carried out using a column (up to 5.4 m high) filled with backfill mortar. The column has a modular construction and can be sealed at the top end with a material of defined permeability (plug or top plug). The possibility to vary the material of the plug allows the influence of the more impermeable cavern lining or possible gas escape vents in the cavern roof to be investigated. A gas supply is connected to the bottom end and is used to simulate different gas generation rates from the waste. A total of 5 experiments were carried out in which the gas generation rate, the column height and the permeability of the plug were varied. Before the start of the experiments, the mortar in the column and the plug were saturated with water to approx. 95 %. In all the experiments, an increase in pressure with time could be observed. The higher the gas generation rate and the lower the permeability of the plug, the more quickly this occurred. At the beginning, only water flow out of the top of the column

  6. Sandstone uranium deposits of Meghalaya: natural analogues for radionuclide migration and backfill material in geological repository for high level radioactive waste disposal

    International Nuclear Information System (INIS)

    Bajpai, R.K.; Narayan, P.K.

    2008-01-01

    Sandstone uranium deposits serve as potential natural analogue to demonstrate safety offered by geological media against possible release of nuclear waste from their confinement and migration towards biosphere. In this study, available database on geochemical aspects of Domisiat uranium deposit of Meghalaya has been evaluated to highlight the behavior of radionuclides of concern over long term in a geological repository. Constituents like actinides (U and Th), fission products and RE elements are adequately retained in clays and organic matters associated with these sandstone deposits. The study also highlights the possibility of utilization of lean ore discarded during mining and milling as backfill material in far field areas and optimizing near field buffers/backfills in a geological repository located in granitic rocks in depth range of 400-500m. (author)

  7. From the semicircular vault to the flattened vault in masonry bridges. The influence of rise/span ratio and the resistant backfill in the breaking load

    Directory of Open Access Journals (Sweden)

    J. R. Urruchi-Rojo

    2017-04-01

    Full Text Available The shape of the vaults in masonry bridges has evolved during the history, so that we can find bibliography where, besides recommending one way of build instead of others depending on the period, is also prescribed the way to carry out the backfill of the extrados. All of this emerged initially as a result of the experiences acquired during the construction and the observation of bridges. Hence, during the 18th century new formulations started to arise, but they led to one result in some cases and to the opposite in others. This article tries to make a comparison between some of these formulations, as well as carrying out an analysis of the influence of both, the lowering rise/span ratio of the vaults and the presence of a resistant backfill in its extrados, on the variation of the breaking load.

  8. Review of the sorption of radionuclides on the bedrock of Haestholmen and on construction and backfill materials of a final repository for reactor wastes

    International Nuclear Information System (INIS)

    Kulmala, S.; Hakanen, M.

    1992-10-01

    Imatran Voima Oy (IVO) has plans to build a final repository for reactor wastes in the bedrock of the nuclear power plant site at Haestholmen, Loviisa. This report summarizes the sorption studies of radionuclides in Finnish bedrock performed at the Department of Radiochemistry, University of Helsinki. The values of mass distribution ratios, K d , and surface distribution ratios, K a ; of carbon, calsium, Zirconium, niobium, cobalt, nickel, strontium, cesium, uranium, plutonium, americium, thorium, chlorine, iodine and technetium are surveyed. Special attention is paid to the sorption data for construction and backfill materials of rector waste repository and the bedrock of Haestholmen. Safety assessment of a repository includes calculations of migration of the waste element in construction materials and backfill in the nearfield and in bedrock. Retardation by sorption of waste nuclides compared to groundwater flow is described by using distribution ratios between solid materials and water. (orig.)

  9. Backfill barriers: the use of engineered barriers based on geologic materials to assure isolation of radioactive wastes in a repository. [Nickel-iron alloys

    Energy Technology Data Exchange (ETDEWEB)

    Apps, J.A.; Cook, N.G.W.

    1981-06-01

    A preliminary assessment is made to show that canisters fabricated of nickel-iron alloys, and surrounded by a suitable backfill, may produce an engineered barrier where the canister material is thermodynamically stable with respect to its environment. As similar conditions exist in nature, the performance of such systems as barriers to isolate radionuclides can be predicted over very long periods, of the order of 10/sup 6/ years.

  10. Feasibility studies of air placed techniques as emplacement means of different backfilling materials in underground radioactive waste disposal

    International Nuclear Information System (INIS)

    Atabek, R.; Conche, P.; Lajudie, A.; Revertegat, E.

    1992-01-01

    Air placed techniques are likely to be used as emplacement means of different backfilling materials in underground waste repositories. A literature survey of the air placed techniques and equipments leads to the choice of the dry process taking into account the emplacement constraints (distance: 300 m, flow: 10 m 3 /h) and the large variety of materials to be placed. Tests performed in the case of cement-based materials (with and without addition of silica fumes), for different types of cement and as a function of the incidence of the jet, show that it is possible to put in place mortars of good quality. However heterogeneity in the material composition is found when the jet is stopped. This problem may be partly solved by a better automation of the process. Complementary tests, carried out with the preselected clay of Fourges Cahaignes, clearly demonstrate the ability of the air placed technique to put in place pure clay: a dry density of 1.50kg/m 3 is reached in the case of coarse material and for a final water content of 30% (in weight). Feasibility tests performed on clay-sand mixtures are not conclusive due to an unappropriate granulometry distribution of the sand. 11 figs., 9 tabs

  11. Performance of concrete backfilling materials for shafts and tunnels in rock formations. Volume 1: concrete selection and properties

    International Nuclear Information System (INIS)

    Casson, R.B.J.; Davies, I.L.

    1986-01-01

    Preplaced Aggregate Concrete (PAC) consists of graded coarse aggregate, immobilised by cementitious grout injected into the voids. PAC can be considered as a suitable backfill material for mined radioactive waste repositories. PAC is also reported to be amenable to mechanical/remote placement and have usefully improved properties when compared with conventionally placed concretes. In particular reduced shrinkage and heat cycle during cement hydration, higher densities and improved plant economics are claimed. This study attempts to establish the validity of these claims both from reported experience and by practical demonstration through experimentation. A literature study supported the claims made for the PAC system but all reported experiences recorded the use of organic admixtures (workability aids, retarders etc). Because of the lack of long term durability data on such admixtures, especially in a radiation environnement, it was decided to prepare a sample of PAC without organic admixtures. Considerable experimental difficulties were encountered in obtaining a satisfactory quality for test specimens. The necessary grout fluidity was only achieved by the inclusion of bentonite. The test data collected indicates that the PAC system employed did not improve mechanical properties compared with conventional concretes. This is attributed to the non-usage of organic admixtures to achieve the expected performance. Further research on low permeability concretes would require the use of organic admixtures. The effect of radiation on these materials, and their leaching rate needs to be quantified

  12. Sodium Silicate Gel Effect on Cemented Tailing Backfill That Contains Lead-Zinc Smelting Slag at Early Ages

    Directory of Open Access Journals (Sweden)

    Lijie Guo

    2018-01-01

    Full Text Available This paper presents the results of an experimental study on the priming effect of sodium silicate gel (SS on cemented tailing backfill (CTB that contains lead-zinc smelting slag. CTB and cemented paste (CP containing lead-zinc smelting slag samples with SS of 0 and 0.4% of the mass of the slag were prepared and cured at 20°C for 1, 3, 7, and 28 days. Mechanical test and pore structure analyses were performed on the studied CTB samples, microstructural analyses (X-ray diffraction analysis and thermal gravity analysis were performed on the studied CP samples, whereas the electrical conductivity of CTB was monitored. The results reveal that SS has a significant positive effect on cementitious activity of binder mixed by cement and lead-zinc smelting slag. This activation leads to the acceleration of binder hydration process, the formation of more cement hydration products in the CTBs, and the refinement of their pore structure, which is favorable for the strength development of CTB.

  13. Stratigraphic architecture of back-filled incised-valley systems: Pennsylvanian-Permian lower Cutler beds, Utah, USA

    Science.gov (United States)

    Wakefield, Oliver J. W.; Mountney, Nigel P.

    2013-12-01

    The Pennsylvanian to Permian lower Cutler beds collectively form the lowermost stratigraphic unit of the Cutler Group in the Paradox Basin, southeast Utah. The lower Cutler beds represent a tripartite succession comprising lithofacies assemblages of aeolian, fluvial and shallow-marine origin, in near equal proportion. The succession results from a series of transgressive-regressive cycles, driven by repeated episodes of climatic variation and linked changes in relative sea-level. Relative sea-level changes created a number of incised-valleys, each forming through fluvial incision during lowered base-level. Aeolian dominance during periods of relative sea-level lowstand aids incised-valley identification as the erosive bounding surface juxtaposes incised-valley infill against stacked aeolian faces. Relative sea-level rises resulted in back-flooding of the incised-valleys and their infill via shallow-marine and estuarine processes. Back-flooded valleys generated marine embayments within which additional local accommodation was exploited. Back-filling is characterised by a distinctive suite of lithofacies arranged into a lowermost, basal fill of fluvial channel and floodplain architectural elements, passing upwards into barform elements with indicators of tidal influence, including inclined heterolithic strata and reactivation surfaces. The incised-valley fills are capped by laterally extensive and continuous marine limestone elements that record the drowning of the valleys and, ultimately, flooding and accumulation across surrounding interfluves (transgressive surface). Limestone elements are characterised by an open-marine fauna and represent the preserved expression of maximum transgression.

  14. Effects of water inflow and early water uptake on buffer and backfill materials in a KBS-3V repository

    International Nuclear Information System (INIS)

    Boergesson, L.; Sanden, T.; Dueck, A.; Nilsson, U.; Goudarzi, R.; Andersson, L.; Jensen, V.

    2012-01-01

    Document available in extended abstract form only. Bentonite is an excellent sealing material when it has reached full water saturation and swelling pressure. However, bentonite is not good for sealing inflowing water from fractures with potential to build high water pressure. It cannot stop inflow of water at the depth of a repository. The water inflow into the pellets filled slots in the deposition holes and the tunnels in a KBS-3V repository is expected to continue until these slots are water filled and the water flow stopped by an end plug. Then the water pressure gradient is transferred from the fracture/bentonite interface to the plug and the bentonite will have time to homogenize and seal. This scenario leads to a number of processes that can either be harmful to the bentonite or affect the water saturation and homogenization evolution. Last year a project (EVA) started in order to investigate the processes involved by this early water inflow. The project aims at developing a model for the processes piping, erosion, water filling of pellets filled slots, early water absorption and resulting water pressure increase against the plug. The project studies the effects of water inflow in deposition holes and deposition tunnels and the emergence of piping and erosion during installation and wetting of the buffer and backfill until all slots and the pellet fillings have been water filled and piping and erosion have ceased. The project includes laboratory tests of nine different processes and modeling. The laboratory program includes tests of the following processes: 1. Erosion; 2. Piping; 3. Water flow in pellet filled slots; 4. Sealing ability of bentonite; 5. Water absorption of the bentonite blocks; 6. Formation of water or gel pockets in a pellet filled slot; 7. Formation and outflow of bentonite gel; 8. Self-sealing of cracks by eroding water; 9. Buffer swelling before placement of backfill. The laboratory tests are ongoing and preliminary results and

  15. Natural analogue study on backfill materials from ancient Chinese constructions for LILW disposal. Appendix 5: China (b)

    International Nuclear Information System (INIS)

    Cunli, G.; Zhiwen, F.; Xiuzhen, L.; Yawen, H.; Anxi, C.; Jinsheng, Z.

    2001-01-01

    Full text: The objective of this work was to contribute to the demonstration of the long term safety of low-and-intermediate level radioactive waste (LILW) disposal using information from a natural analogue study on ancient Chinese constructions. The work firstly compared LILW near surface disposal facilities with Chinese ancient tombs in respects of siting, engineering structures, design and construction procedures and indicates that they are both based upon multi-barrier principle. After extensive literature and field survey, three materials were collected from two Chinese ancient tombs and one ancient architectures for further laboratory study. The three materials were studied in laboratories from the point of view of radioactive waste disposal in near surface facilities to obtain information concerning their basic physical and chemical properties, engineering properties and radionuclide adsorption abilities. The results show that the two materials from the ancient tombs have low permeability and strong adsorption for 60 Co and 134 Cs. The saturated permeabilities of the two ancient materials are in the order of 10 -1 0 m/s and the distribution coefficients for the two radionuclides are all in the order of 10 1 m 3 /kg. The conclusion was that the then current LILW disposal option in near-surface would be effective for a long term period of time, and clay materials, as backfill materials for LILW near-surface disposal facilities would very effective in preventing water intrusion and retarding radionuclide release even over a long term of period. Overall the LILW disposal option was considered to be safe in long term. (author)

  16. Aespoe Hard Rock Laboratory. Backfill and Plug test. Hydraulic testing of core drilled boreholes in the ZEDEX drift

    Energy Technology Data Exchange (ETDEWEB)

    Ludvigson, Jan-Erik; Nordqvist, Rune; Ekman, Lennart; Hansson, Kent (GEOSIGMA AB, Uppsala (Sweden))

    2009-07-01

    The present report documents the performance and results of hydraulic testing in selected core boreholes in the Zedex drift. The holes will be used as rock instrumentation boreholes during the Backfill and Plug Test at Aespoe HRL. The testing involves both 1 m long boreholes with 56 mm diameter as well as longer boreholes c. 5 m, 8 m and 25 m long with 56 mm or 76 mm diameter. Only single-hole tests were performed. The tests were carried out as short-time constant head injection tests since all boreholes tested (except one) were non-flowing before tests. The injection phase was followed by a pressure recovery phase. Furthermore, the tests were carried out as single-packer tests. A specially designed test system was used for the tests. The main evaluation of the tests was performed on data from the recovery phase by a new approach based on a non-linear regression technique combined with a flow simulation model (SUTRA). The tests in the 1 m-holes (testing the interval c. 0.3-0.7 m in the rock perpendicular to the tunnel face) show that the hydraulic conductivity of the superficial rock around the Zedex drift in general is low. However, during testing in some boreholes, visible leakage in the rock occurred through superficial fractures into the tunnel. These fractures were mainly located in the floor of the Zedex drift and are probably blast-induced. These fractures have a high hydraulic conductivity. The tests in the longer boreholes show that the hydraulic conductivity further into the rock in general is below c. 1x10-10 m/s. Increased hydraulic conductivity (c.1.5x10-8 m/s) was only observed in the flowing borehole KXZSD8HL.

  17. Laboratory determination of migration of Eu(III) in compacted bentonite–sand mixtures as buffer/backfill material for high-level waste disposal

    International Nuclear Information System (INIS)

    Zhou, Lang; Zhang, Huyuan; Yan, Ming; Chen, Hang; Zhang, Ming

    2013-01-01

    For the safety assessment of geological disposal of high-level radioactive waste (HLW), the migration of Eu(III) through compacted bentonite–sand mixtures was measured under expected repository conditions. Under the evaluated conditions, advection and dispersion is the dominant migration mechanism. The role of sorption on the retardation of migration was also evaluated. The hydraulic conductivities of compacted bentonite–sand mixtures were K=2.07×10 −10 –5.23×10 −10 cm/s, The sorption and diffusion of Eu(III) were examined using a flexible wall permeameter for a solute concentration of 2.0×10 −5 mol/l. The effective diffusion coefficients and apparent diffusion coefficients of Eu(III) in compacted bentonite–sand mixtures were in the range of 1.62×10 –12 –4.87×10 –12 m 2 /s, 1.44×10 –14 –9.41×10 –14 m 2 /s, respectively, which has a very important significance to forecast the relationship between migration length of Eu(III) in buffer/backfill material and time and provide a reference for the design of buffer/backfill material for HLW disposal in China. - Highlights: • The migration progress of Eu(III) in compacted bentonite–sand mixtures was researched. • The hydraulic conductivity of cominpacted bentonite–sand mixtures was measured. • The migration length of Eu(III) in buffer/backfill material after a certain period of time was forecasted

  18. Project ANSICHT. Final repository concept and backfilling and sealing concept for the final repository site model SUeD; Projekt ANSICHT. Endlagerkonzept sowie Verfuell- und Verschlusskonzept fuer das Endlagerstandortmodell SUeD. Technischer Bericht

    Energy Technology Data Exchange (ETDEWEB)

    Jobmann, Michael; Lommerzheim, Andree

    2015-08-03

    In the frame of ANSICHT the methodology for the demonstration of safe enclosure for high-level heat generating radioactive wastes is described. The report is based on the safety requirements for final repository concepts and shows a first backfilling and sealing concept that was developed for the final repository site model SUeD. The final repository model SUeD is based on a horizontal line storage concept, the Gorleben (VSG) and ERATO container concept and the mine layout were adopted and adapted to the given conditions. The backfill and sealing concept includes migration barriers, line closures and shaft closures in the frame of a redundant and diverse enclosure system. For all technical and geotechnical barrier components the long-term functional requirements were defined. The backfilling concept of underground cavities considers the variety of possible cavities in the line and infrastructure areas.

  19. Hydraulic hoisting and backfilling

    Science.gov (United States)

    Sauermann, H. B.

    In a country such as South Africa, with its large deep level mining industry, improvements in mining and hoisting techniques could result in substantial savings. Hoisting techniques, for example, may be improved by the introduction of hydraulic hoisting. The following are some of the advantages of hydraulic hoisting as against conventional skip hoisting: (1) smaller shafts are required because the pipes to hoist the same quantity of ore hydraulically require less space in the shaft than does skip hoisting equipment; (2) the hoisting capacity of a mine can easily be increased without the necessity of sinking new shafts. Large savings in capital costs can thus be made; (3) fully automatic control is possible with hydraulic hoisting and therefore less manpower is required; and (4) health and safety conditions will be improved.

  20. Total flotation and backfill

    Directory of Open Access Journals (Sweden)

    Carlos Villachica León

    2001-03-01

    Full Text Available Kolektívna flotácia a zavážanie (TFB boli navrhnuté ako ve¾mi výhodný technologický postup pre dosiahnutie trvalého rozvoja pri podzemnej ažbe polymetalických rúd v Peru. Táto technológia zlepšuje ekonomiku, znaène znižuje väèšinu environmentálnych problémov, ktoré súvisia s prevádzkovaním jemných odpadov, kyslými vodami a nadmerným používaním chemikálií v úpravniach.Kolektívna flotácia (TF je založená na mimoriadne hrubom mletí a flotácii sulfidov neželezných kovov s výnimkou pyritu. Získaný produkt je kolektívny koncentrát s hmotnosou 15-25 % hmotnosti vyaženej rudy. Postup umožòuje ve¾mi jednoduchú schému aplikácie flotaèného režimu a flotaèného okruhu bez stupòov triedenia, zahusovania a filtrácie. Úpravne pracujúce v TF režime sú tak malé, že ich je možné inštalova v podzemí, èím sa znaène znížia náklady a infraštruktúra potrebné pre manipuláciu s rudou a jej dopravou na povrch.Odpady z TF prevádzkovanej v podzemí sú hrubozrné takže je možné ich zavážanie bez predchádzajúceho triedenia za úèelom odstránenia jemných podielov. Tým sa znižuje množstvo odpadu, ktoré sa má èerpa na povrch až na 5-10 % hmotnosti vyaženej rudy. Kolektívny koncentrát sa èerpá na povrch, kde sa premie¾a a separuje na koncentráty Cu, Pb a Zn a pyritový koncentrát. V prípade Peru táto separaèná jednotka (SP môže by vzdialená od miesta ažby.V prípade novej baníckej technológie TFB dochádza k dramatickým zmenám pri návrhu a projektovaní banského diela. Technológiu TFB je možné tiež úspešne aplikova v jestvujúcich baniach, kde je nutné aži hlboko uložené ložiská. V tejto práci sa popisujú skúšky s TFB technológiou pre Zn-Pb ložisko ve¾kej håbky. V týchto skúškach sa dosiahli výažnosti pre Zn a Pb do 90 % pre koncentrát tvoriaci 15 % vyaženej rudy pri hrubom mletí (25 % - 200 mesh pri porovnaní s jemným mletím (57-60 % - 200 mesh , ktoré sa aplikuje na štandardných úpravniach s produkciou selektívnych koncentrátov. Výsledky flotaèných testov pri jemnosti mletia 18 % - 200 mesh je potrebné zlepši doplòujúcou gravitaènou úpravou. Testy perlokácie ukázali, že odpady z TF procesu je možné priamo použi pre zavážanie banského diela.Pri štúdiu kinetiky flotácie sa zistilo, že v porovnaní so štandardným flotaèným okruhom je tiež výhodná a že pre TFB proces sa vyžadovali maximálne 2 flotaèné cely s èasom zdržania 10 minút. Stupeò kondiciovania sa vylúèil prípravou zmesi umožòujúcej simultánnu aktiváciu a nakoncentrovanie sulfidov Zn v rámci stupòa mletia. Vïaka tomuto postupu bolo možné uvažova o TFB ako o technologickom postupe.

  1. Contact-metamorphic illitization and related consequences for the functioning of backfill barriers in high level radioactive waste repositories (South Africa)

    International Nuclear Information System (INIS)

    Buehmann, C.

    2000-01-01

    A clay barrier, consisting of smectite, is common to most disposal designs for HLW repositories. Concerns are that elevated temperatures and long time periods may alter the two properties, the barrier is employed: a high swelling as well as cation exchange capacity (CEC). A ''natural analogue'' approach has therefore been attempted to predict smectite characteristics and stability in relation to time/temperature. The following investigations were performed in order to determine changes in swelling capacity and CEC: (1) Conversion of smectite to other clay minerals. (2) Changes in the layer charge characteristics of the clay minerals. (3) Swelling potential measurements of the smectitic interlayer. Smectite was thermally unstable and transformed into illite via illite/smectite interstratifications (I/S) and chlorite at temperature exceeding about 100 deg. C. The swelling potential was directly related to the proportion of smectite. As a conclusion it can be stated that elevated temperatures (> 70 deg. C) result in the transformation of smectite into illite. For backfill purposes it is recommended that the clay content in the backfill barrier should be as high as technically possible and that mixing the bentonite with K-bearing minerals (granite) should be avoided. (author)

  2. M4FT-16LL080303052-State of Knowledge for Colloid Facilitated Radionuclide Transport and Update on Actinide Diffusion in Bentonite Backfill

    Energy Technology Data Exchange (ETDEWEB)

    Zavarin, Mavrik [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Glenn T. Seaborg Inst.. Physical and Life Sciences; Joseph, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Glenn T. Seaborg Inst.. Physical and Life Sciences

    2016-08-16

    This progress report (Level 4 Milestone Number M4FT-16LL080303052) summarizes research conducted at Lawrence Livermore National Laboratory (LLNL) within the Crystalline Disposal R&D Activity Number FT-16LL080303051 and Crystalline International Collaborations Activity Number FT-16LL080303061. The focus of this research is the interaction of radionuclides with Engineered Barrier System (EBS) and host rock materials at various physico-chemical conditions relevant to subsurface repository environments. They include both chemical and physical processes such as solubility, sorption, and diffusion. The colloid-facilitated transport effort focused on preparation of a draft manuscript summarizing the state of knowledge and parameterization of colloid-facilitated transport mechanisms in support of reactive transport and performance assessment models for generic crystalline repositories. This draft manuscript is being submitted as a level 3 milestone with LANL as the primary author. LLNL’s contribution to that effort is summarized only briefly in the present report. A manuscript summarizing long-term U(VI) diffusion experiments through bentonite backfill material was recently accepted for publication; the contents of that manuscript are summarized in the present report. The Np(IV) diffusion experiments were started mid-year and are ongoing. The completion of these experiments is planned for early FY17. Our progress in quantifying Np(IV) diffusion in bentonite backfill is summarized in the present report. Our involvement with the NEA TDB project was summarized in a recent Argillite Disposal activity report. It is not included in this report.

  3. Physical and chemical properties of bentonite as backfill and sealing material in a final repository of radioactive wastes. A literature study

    International Nuclear Information System (INIS)

    Schmidt, W.; Kessler, J.; Sitz, P.

    1992-11-01

    Results of a literature study concerning the properties and the changes in properties of bentonite backfill are presented on the basis of current concepts envisaged for final disposal of radioactive waste in Switzerland. The literature preferentially used in this study is that of NAGRA, international papers and special publications from universities in Germany, Austria and Switzerland. Mechanical, physico-mineralogical and chemical properties of bentonite and bentonite-water systems are considered as the central point, particularly taking into account the types MX-80 and Montigel which are favoured in the Swiss concept. Technological problems associated with radioactive waste disposal are only touched on or are taken as being understood. Special attention is paid to considering mutual interactions between different complexes of properties, considering certain aspects of longevity and long-term stability, the discussion is focused on potential physical and chemical impacts of the bentonite backfill. Further investigations should consider the interrelations between mechanical and physical properties, diffusion properties and the influence on bentonite of higher temperatures, of water vapor, of iron corrosion products and of the products of interactions in the water-concrete system. (author) figs., tabs., refs

  4. Aespoe Hard Rock Laboratory. Prototype Repository. Analyses of microorganisms, gases and water chemistry in buffer and backfill, 2009

    Energy Technology Data Exchange (ETDEWEB)

    Lydmark, Sara (Microbial Analytics Sweden AB (Sweden))

    2010-09-15

    chemistry. The in 2007 improved sampling and analysis protocols worked very well. Also, the molecular methods that were tested for the first time in the Prototype showed promising potential. IPR 08-01 revealed that many of the hydrochemical sampling points differ quite remarkably from each other. The 16 sampling points were therefore divided into seven sampling groups with similar properties. The properties of one sampling group (i.e., KBU10002+8) resembled those of the groundwater, while others (i.e., KBU10004+6, KBU10005, and KFA01-04) differed, for example, in microbial composition, salinity, sulphate content, pH, and the concentrations of calcium, potassium, magnesium, sodium, and many dissolved metals, actinides, and lanthanides. One sampling group contained sampling points that seemed to be in contact with tunnel air (KBU10003+7). Another sampling group contained sampling points near the canisters in the buffer (KB513-614) with very little pore water with high pH and a high salt content. One sampling point in the backfill, which had not been reached by the groundwater as of May 2007 (KBU10001), now consisted of pore water with properties resembling those of groundwater. The gas composition in the sampling groups was uniform in that the proportion of nitrogen in the extracted gas was increasing and the oxygen content decreasing with time. In most sampling groups, the oxygen content in the pore water had decreased from 3-7% as of May 2007 to 0.6-4% in 2009. This can also be compared with the proportion of oxygen in the gas phase in 2005, which was 10-18%. Hydrogen, methane, helium, and carbon dioxide concentrations varied, especially in the sampling groups with extractable pore water. ATP analyses demonstrated that the biomass in the Prototype repository is high compared to the surrounding groundwater. The microbiological results indicated that aerobic microbes, such as MOB and CHAB, thrived in the aerobic Prototype environment

  5. Aespoe Hard Rock Laboratory. Prototype Repository. Analyses of microorganisms, gases and water chemistry in buffer and backfill, 2009

    International Nuclear Information System (INIS)

    Lydmark, Sara

    2010-09-01

    . The in 2007 improved sampling and analysis protocols worked very well. Also, the molecular methods that were tested for the first time in the Prototype showed promising potential. IPR 08-01 revealed that many of the hydrochemical sampling points differ quite remarkably from each other. The 16 sampling points were therefore divided into seven sampling groups with similar properties. The properties of one sampling group (i.e., KBU10002+8) resembled those of the groundwater, while others (i.e., KBU10004+6, KBU10005, and KFA01-04) differed, for example, in microbial composition, salinity, sulphate content, pH, and the concentrations of calcium, potassium, magnesium, sodium, and many dissolved metals, actinides, and lanthanides. One sampling group contained sampling points that seemed to be in contact with tunnel air (KBU10003+7). Another sampling group contained sampling points near the canisters in the buffer (KB513-614) with very little pore water with high pH and a high salt content. One sampling point in the backfill, which had not been reached by the groundwater as of May 2007 (KBU10001), now consisted of pore water with properties resembling those of groundwater. The gas composition in the sampling groups was uniform in that the proportion of nitrogen in the extracted gas was increasing and the oxygen content decreasing with time. In most sampling groups, the oxygen content in the pore water had decreased from 3-7% as of May 2007 to 0.6-4% in 2009. This can also be compared with the proportion of oxygen in the gas phase in 2005, which was 10-18%. Hydrogen, methane, helium, and carbon dioxide concentrations varied, especially in the sampling groups with extractable pore water. ATP analyses demonstrated that the biomass in the Prototype repository is high compared to the surrounding groundwater. The microbiological results indicated that aerobic microbes, such as MOB and CHAB, thrived in the aerobic Prototype environment

  6. Quantitative mineralogy and preliminary pore-water chemistry of candidate buffer and backfill materials for a nuclear fuel waste disposal vault

    International Nuclear Information System (INIS)

    Quigley, R.M.

    1984-07-01

    The quantitative mineralogy of seven candidate buffer and backfill materials for a nuclear fuel waste disposal vault is presented. Two of the materials were coarse grained: one a blended very pure silica sand, and the other a crushed plagioclase-rich granite or granodiorite. Five materials were fine-grained soils containing abundant clay minerals. Of these, three were fairly pure, Cretaceous, ash-derived bentonites that contained up to 3 percent of soluble sulphates; one was a freshwater glacial clay containing 59 percent interlayered smectite-illite; and one was a crushed Paleozoic shale containing abundant illite and chlorite. The adsorbed cation regimes and the pore-water chemistry of the clays are discussed

  7. Sorption of plutonium and americium on repository, backfill and geological materials relevant to the JNFL low-level radioactive waste repository at Rokkasho-Mura

    International Nuclear Information System (INIS)

    Baston, G.M.N.; Berry, J.A.; Brownsword, M.; Heath, T.G.; Tweed, C.J.; Williams, S.J.

    1995-01-01

    An integrated program of batch sorption experiments and mathematical modeling has been carried out to study the sorption of plutonium and americium on a series of repository, backfill and geological materials relevant to the JNFL low-level radioactive waste repository at Rokkasho-Mura. The sorption of plutonium and americium on samples of concrete, mortar, sand/bentonite, tuff, sandstone and cover soil has been investigated. In addition, specimens of bitumen, cation and anion exchange resins, and polyester were chemically degraded. The resulting degradation product solutions, alongside solutions of humic and isosaccharinic acids were used to study the effects on plutonium sorption onto concrete, sand/bentonite and sandstone. The sorption behavior of plutonium and americium has been modeled using the geochemical speciation program HARPHRQ in conjunction with the HATCHES database

  8. Comparative simulation study of coupled THM processes near back-filled and open-drift nuclear waste repositories in Task D of the International DECOVALEX Project

    International Nuclear Information System (INIS)

    Rutqvist, J.; Birkholzer, J.T.; Chijimatsu, M.; Kolditz, O.; Liu, Quan-Sheng; Oda, Y.; Wang, Wenqing; Zhang, Cheng-Yuan

    2006-01-01

    As part of the ongoing international DECOVALEX project, four research teams used five different models to simulate coupled thermal, hydrological, and mechanical (THM) processes near underground waste emplacement drifts. The simulations were conducted for two generic repository types, one with open and the other with back-filled repository drifts, under higher and lower post-closure temperature, respectively. In the completed first model inception phase of the project, a good agreement was achieved between the research teams in calculating THM responses for both repository types, although some disagreement in hydrological responses are currently being resolved. Good agreement in the basic thermal-mechanical responses was also achieved for both repository types, even though some teams used relatively simplified thermal-elastic heat-conduction models that neglect complex near-field thermal-hydrological processes. The good agreement between the complex and simplified process models indicates that the basic thermal-mechanical responses can be predicted with a relatively high confidence level

  9. Aespoe Hard Rock Laboratory. Prototype repository. Analyses of microorganisms, gases, and water chemistry in buffer and backfill, 2010

    International Nuclear Information System (INIS)

    Lydmark, Sara

    2011-06-01

    divided into seven sampling groups, each with similar properties. The properties of one sampling group (i.e. KBU10002 + KBU10008) resembled those of the groundwater, while others (i.e. KBU10004 + KBU10006, KBU10005, and KFA01-KFA04) differed, for example, in microbial composition, salinity, sulphate content, and the concentrations of calcium, potassium, magnesium, sodium, and many dissolved metals, actinides, and lanthanides. One sampling group comprised sampling points that seemed to be in contact with tunnel air (KBU10003 + KBU10007). Another sampling group comprised sampling points, near the canisters in the buffer (KB513-614), with very little pore water with high pH and a high salt content. One sampling point in the backfill, which had not been reached by the groundwater as of May 2007 (KBU10001), now yielded pore water with properties resembling those of groundwater. The gas composition in the sampling groups was uniform in that the proportion of nitrogen in the extracted gas was increasing while the oxygen content was decreasing with time. ATP analyses demonstrated that the biomass in the Prototype was higher than in the surrounding groundwater. The microbiological results indicated that aerobic microbes, such as methane-oxidizing bacteria and culturable heterotrophic bacteria, thrived in the aerobic Prototype environment. The chemical data indicated differences between the sampling groups: concentrations of sodium and potassium were higher in the Prototype pore water than in the groundwater outside it, while calcium was lower than in the groundwater. Obviously, cation exchange occurs in the montmorillonite interlayers. At sampling points containing active microbes, copper, rubidium, vanadium, and uranium were enriched up to 225 times the groundwater levels; microbes are possibly responsible for dissolving these substances by excreting compound-specific ligands. Overall, the observations presented here strongly support our hypothesis that oxygen will be consumed by

  10. Aespoe Hard Rock Laboratory. Prototype repository. Analyses of microorganisms, gases, and water chemistry in buffer and backfill, 2010

    Energy Technology Data Exchange (ETDEWEB)

    Lydmark, Sara [Microbial Analytics Sweden AB, Moelnlycke (Sweden)

    2011-06-15

    therefore divided into seven sampling groups, each with similar properties. The properties of one sampling group (i.e. KBU10002 + KBU10008) resembled those of the groundwater, while others (i.e. KBU10004 + KBU10006, KBU10005, and KFA01-KFA04) differed, for example, in microbial composition, salinity, sulphate content, and the concentrations of calcium, potassium, magnesium, sodium, and many dissolved metals, actinides, and lanthanides. One sampling group comprised sampling points that seemed to be in contact with tunnel air (KBU10003 + KBU10007). Another sampling group comprised sampling points, near the canisters in the buffer (KB513-614), with very little pore water with high pH and a high salt content. One sampling point in the backfill, which had not been reached by the groundwater as of May 2007 (KBU10001), now yielded pore water with properties resembling those of groundwater. The gas composition in the sampling groups was uniform in that the proportion of nitrogen in the extracted gas was increasing while the oxygen content was decreasing with time. ATP analyses demonstrated that the biomass in the Prototype was higher than in the surrounding groundwater. The microbiological results indicated that aerobic microbes, such as methane-oxidizing bacteria and culturable heterotrophic bacteria, thrived in the aerobic Prototype environment. The chemical data indicated differences between the sampling groups: concentrations of sodium and potassium were higher in the Prototype pore water than in the groundwater outside it, while calcium was lower than in the groundwater. Obviously, cation exchange occurs in the montmorillonite interlayers. At sampling points containing active microbes, copper, rubidium, vanadium, and uranium were enriched up to 225 times the groundwater levels; microbes are possibly responsible for dissolving these substances by excreting compound-specific ligands. Overall, the observations presented here strongly support our hypothesis that oxygen will be

  11. Understanding the Alteration of Bentonite Backfill Using Coupled THMC Modeling for a Long Term Heater Test at the Grimsel Underground Research Lab

    Science.gov (United States)

    Birkholzer, J. T.; Zheng, L.; Xu, H.; Rutqvist, J.

    2017-12-01

    Compacted bentonite is commonly used as backfill material in emplacement tunnels of nuclear waste repositories because of its low permeability, high swelling pressure, and retardation capacity of radionuclide. To assess whether this backfill material can maintain these favorable features when undergoing heating from the waste package and hydration from the host rock, we need a thorough understanding of the thermal, hydrological, mechanical, and chemical evolution of bentonite under disposal conditions. Dedicated field tests integrated with THMC modeling provide an effective way to deepen such understanding. Here, we present coupled THMC models for an in situ heater test which was conducted at the Grimsel Test Site in Switzerland for 18 years. The comprehensive monitoring data obtained in the test provide a unique opportunity to evaluate bentonite integrity and test coupled THMC models. We developed a modeling strategy where conceptual model complexity is increased gradually by adding/testing processes such as Non-Darcian flow, enhanced vapor diffusion, thermal osmosis and different constitutive relationships for permeability/porosity changes due to swelling. The final THMC model explains well all the THM data and the concentration profiles of conservative chemical species. Over the course of modeling the in situ test, we learned that (1) including Non-Darcian flow into the model leads to a significant underestimation of hydration rate of bentonite, (2) chemical data provide an important additional piece of information for calibrating a THM model; (3) key processes needed to reproduce the data include vapor diffusion, as well as porosity and permeability changes due to swelling and thermal osmosis; (4) the concentration profiles of cations (calcium, potassium, magnesium and sodium) were largely shaped by transport processes despite their concentration levels being affected by mineral dissolution/precipitation and cation exchange. The concentration profiles of p

  12. Comments on the feasibility studies concerning the decommissioning options LAW retrieval, relocation and backfilling for the Asse facility with respect to the applicability of the BfS evaluation criteria

    International Nuclear Information System (INIS)

    Alt, Stefan; Kallenbach-Herbert, Beate; Neles, Julia

    2009-01-01

    The comments on the feasibility studies cover the decommissioning options LAW retrieval, relocation and backfilling for the Asse facility with respect to the applicability of the BfS evaluation criteria. The respective BfS criteria include the evaluation with respect to the safety during the operational phase, the environmental impacts in case of an uncontrollable brine intrusion; the preliminary long-term safety assessment; the feasibility; and the time required.

  13. Settlement mechanism of the backfilled ground around nuclear power plant buildings. Part 2. A series of centrifuge tests and a numerical simulation by using FEM about a typical test result

    International Nuclear Information System (INIS)

    Kawai, Tadashi; Ishimaru, Makoto

    2009-01-01

    During the Niigataken Chuetsu-oki earthquake, rather large settlements of the backfill ground around the rigid and stable buildings were observed. In this study, five cases of centrifuge tests with shaking events were conducted to reproduce the similar type of the settlements in order to examine the mechanism of the settlements. The results from those tests showed that the ground was settled by the negative dilatancy of sandy soils anywhere in the model ground and the additional settlements were suddenly caused when the backfill ground was apart from the rigid wall modeling the rigid and stable buildings, namely a sliding failure in an active state was occurred in the backfill ground near the structure. It was confirmed that these settlements were able to be estimated by a simple method proposed in this report, in which only the differences between the self-weight of the sliding block and the soil strength calculated at the initial stress conditions were considered as the driving forces of the sliding failure, and then the accelerations calculated from the forces being divided by the mass of the sliding block were simply integrated two times with respected to the time when the ground was apart from the structure. Further, a numerical simulation by using FEM about a typical test result was conducted, and these settlements were well simulated. (author)

  14. National waste terminal storage repository in a bedded salt formation for spent unreprocessed fuel. Special study No. 3. Waste retrieval from backfilled regions

    International Nuclear Information System (INIS)

    1978-09-01

    Methods and costs were studied for delayed canister retrieval from rooms that had been backfilled immediately after canister storage. The effects of this method of storage on mine geometry, thermal and rock mechanics environments, mine development and operations, mine ventilation, time schedule, retrieval machinery and safety were investigated. Salt and air temperatures were determined. Pillar width, number of rooms, extraction ratio, tonnages of mined salt, and salt handling and hoisting requirements were calculated. The required changes in mining equipment were established. Salt handling and elapsed time schedules were developed. Ventilation requirements - size and number of shafts, size the arrangement of airways, number of stacks, and size and number of fans were then calculated. The development sequence of these facilities was established. Canister retrieval problems were analyzed for canisters stuck in the hole as well as free. Retrieval methods and machinery were studied and are described. Safety with respect to both radiation and room collapse was studied and compared with CDR safety conditions. The effects of a reduced themal loading of 30 KW/acre on temperatures, room closure, mine layout, ventilation and ground control were studied and reported. A cost estimate was prepared, giving cost differentials between the base CDR costs and Special Study No. 3. Two appendices are included. The first contains nine Heat Transfer memoranda that state the thermal basis of this study. The second appendix provides a detailed operating time analysis of the retrieval machinery

  15. Research and Development of a New Silica-Alumina Based Cementitious Material Largely Using Coal Refuse for Mine Backfill, Mine Sealing and Waste Disposal Stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Henghu Sun; Yuan Yao

    2012-06-29

    Coal refuse and coal combustion byproducts as industrial solid waste stockpiles have become great threats to the environment. To activate coal refuse is one practical solution to recycle this huge amount of solid waste as substitute for Ordinary Portland Cement (OPC). The central goal of this project is to investigate and develop a new silica-alumina based cementitious material largely using coal refuse as a constituent that will be ideal for durable construction, mine backfill, mine sealing and waste disposal stabilization applications. This new material is an environment-friendly alternative to Ordinary Portland Cement. The main constituents of the new material are coal refuse and other coal wastes including coal sludge and coal combustion products (CCPs). Compared with conventional cement production, successful development of this new technology could potentially save energy and reduce greenhouse gas emissions, recycle vast amount of coal wastes, and significantly reduce production cost. A systematic research has been conducted to seek for an optimal solution for enhancing pozzolanic reactivity of the relatively inert solid waste-coal refuse in order to improve the utilization efficiency and economic benefit as a construction and building material.

  16. Settlement mechanism of the backfilled ground around nuclear power plant buildings. Part 1. A series of 1G shaking table tests

    International Nuclear Information System (INIS)

    Ishimaru, Makoto; Kawai, Tadashi

    2008-01-01

    The large ground settlement locally occurred at the backfilled ground around the Kashiwazaki-Kariwa Nuclear Power Plant buildings during the Niigataken Chuetsu-oki Earthquake in 2007. The purposes of this study are to verify the assumed mechanism of the settlement and to discuss the influence factors on the settlement. For these purposes, we conducted a series of 1G shaking table tests using a rigid structure and sand. In the tests, parameters, which were variously changed, are related to two factors; one is the horizontal ground displacement relative to the structure, the other is the ground strength against the sliding failure. The following results were obtained: (1) All the results showed that the ground settlement sizes near the structure were larger than the ground settlement sizes far from the structure, (2) From the video observed at the ground near the structure, it was found that the settlement locally occurred due to the sliding failure after the ground was separated from the structure, (3) The ground settlement sizes near the structure were large as the horizontal ground displacement sizes were large, and the soil strength arising from fines affected the ground settlement sizes near the structure. (author)

  17. TrigDB back-filling method in EEW for the regional earthquake for reducing false location of the deep focus earthquake event by considering neighborhood triggers and forced association.

    Science.gov (United States)

    Park, J. H.; Chi, H. C.; Lim, I. S.; Seong, Y. J.; Pak, J.

    2017-12-01

    During the first phase of EEW(Earthquake Early Warning) service to the public by KMA (Korea Meteorological Administration) from 2015 in Korea, KIGAM(Korea Institute of Geoscience and Mineral Resources) has adopted ElarmS2 of UC Berkeley BSL and modified local magnitude relation, travel time curves and association procedures so called TrigDB back-filling method. The TrigDB back-filling method uses a database of sorted lists of stations based on epicentral distances of the pre-defined events located on the grids for 1,401 × 1,601 = 2,243,001 events around the Korean Peninsula at a grid spacing of 0.05 degrees. When the version of an event is updated, the TrigDB back-filling method is invoked. First, the grid closest to the epicenter of an event is chosen from the database and candidate stations, which are stations corresponding to the chosen grid and also adjacent to the already-associated stations, are selected. Second, the directions from the chosen grid to the associated stations are averaged to represent the direction of wave propagation, which is used as a reference for computing apparent travel times. The apparent travel times for the associated stations are computed using a P wave velocity of 5.5 km/s from the grid to the projected points in the reference direction. The travel times for the triggered candidate stations are also computed and used to obtain the difference between the apparent travel times of the associated stations and the triggered candidates. Finally, if the difference in the apparent travel times is less than that of the arrival times, the method forces the triggered candidate station to be associated with the event and updates the event location. This method is useful to reduce false locations of events which could be generated from the deep (> 500 km) and regional distance earthquakes happening on the subduction pacific plate boundaries. In comparison of the case study between TrigDB back-filling applied system and the others, we could get

  18. Environmental assessment of the reuse of municipal solid waste incineration bottom ash in quarry backfilling; Evaluation environnementale de la valorisation de machefers d'incineration d'ordures menageres en remplissage de carriere

    Energy Technology Data Exchange (ETDEWEB)

    Brons-Laot, G.

    2002-10-15

    The leaching behaviour of three different MSWI bottom ashes-based materials containing hydraulic binders is assessed in the conditions specified by the quarry backfilling application. An adapted approach methodology is applied: - physical, mineralogical and chemical characterizations of materials, - use of parametric tests to determine the effect of main scenarios factors on the release, - chemical modelling based on mineralogical and experimental leaching data with geochemical calculation codes, - chemical reaction / transport coupled modelling. The main results demonstrate that: - the batch and dynamic tests allow to obtain enough data to model and to predict the long term behaviour, - the chemical modelling of the solid / liquid equilibrium permits the determination of the chemical reactions involved and the prediction of pollutants solubilization in different chemical contexts, - the new materials (source term) present a low environmental impact in the conditions specified by the considered scenarios. (author)

  19. Erosion and deposition by supercritical density flows during channel avulsion and backfilling: Field examples from coarse-grained deepwater channel-levée complexes (Sandino Forearc Basin, southern Central America)

    Science.gov (United States)

    Lang, Jörg; Brandes, Christian; Winsemann, Jutta

    2017-03-01

    Erosion and deposition by supercritical density flows can strongly impact the facies distribution and architecture of submarine fans. Field examples from coarse-grained channel-levée complexes from the Sandino Forearc Basin (southern Central America) show that cyclic-step and antidune deposits represent common sedimentary facies of these depositional systems and relate to the different stages of avulsion, bypass, levée construction and channel backfilling. During channel avulsion, large-scale scour-fill complexes (18 to 29 m deep, 18 to 25 m wide, 60 to > 120 m long) were incised by supercritical density flows. The multi-storey infill of the large-scale scour-fill complexes comprises amalgamated massive, normally coarse-tail graded or widely spaced subhorizontally stratified conglomerates and pebbly sandstones, interpreted as deposits of the hydraulic-jump zone of cyclic steps. The large-scale scour-fill complexes can be distinguished from small-scale channel fills based on the preservation of a steep upper margin and a coarse-grained infill comprising mainly amalgamated hydraulic-jump zone deposits. Channel fills include repeated successions deposited by cyclic steps with superimposed antidunes. The deposits of the hydraulic-jump zone of cyclic steps comprise regularly spaced scours (0.2 to 2.6 m deep, 0.8 to 23 m long) infilled by intraclast-rich conglomerates or pebbly sandstones, displaying normal coarse-tail grading or backsets. These deposits are laterally and vertically associated with subhorizontally stratified, low-angle cross-stratified or sinusoidally stratified sandstones and pebbly sandstones, which were deposited by antidunes on the stoss side of the cyclic steps during flow re-acceleration. The field examples indicate that so-called spaced stratified deposits may commonly represent antidune deposits with varying stratification styles controlled by the aggradation rate, grain-size distribution and amalgamation. The deposits of small-scale cyclic

  20. Compression Characteristics of Solid Wastes as Backfill Materials

    OpenAIRE

    Meng Li; Jixiong Zhang; Rui Gao

    2016-01-01

    A self-made large-diameter compression steel chamber and a SANS material testing machine were chosen to perform a series of compression tests in order to fully understand the compression characteristics of differently graded filling gangue samples. The relationship between the stress-deformation modulus and stress-compression degree was analyzed comparatively. The results showed that, during compression, the deformation modulus of gangue grew linearly with stress, the overall relationship bet...

  1. Mass transport of soluble species through backfill into surrounding rock

    International Nuclear Information System (INIS)

    Kang, Chul Hyung; Park, Hun Hwee

    1992-01-01

    Some soluble species may not be solubility-limited or congruent-released with the matrix species. For example, during the operation of the nuclear reactor, the fission products can be accumulated in the fuel-cladding gap, void, and grain boundaries of the fuel rods. In the waste package for spent-fuel placed in a geologic repository, the high solubility species of these fission products accumulated in the 'gap', e.g. cesium or iodine are expected to dissolve rapidly when ground water penetrates fuel rods. The time and space dependent mass transport for high solubility nuclides in the gap is analyzed, and its numerical illustrations are demonstrated. The approximate solution that is valid for all times is developed, and validated by comparison with an asymptotic solution and the solution obtained by the numerical inversion of Laplace transform covering the entire time span. (Author)

  2. Backfilling the Grid with Containerized BOINC in the ATLAS computing

    CERN Document Server

    Wu, Wenjing; The ATLAS collaboration

    2018-01-01

    Virtualization is a commonly used solution for utilizing the opportunistic computing resources in the HEP field, as it provides a unified software and OS layer that the HEP computing tasks require over the heterogeneous opportunistic computing resources. However there is always performance penalty with virtualization, especially for short jobs which are always the case for volunteer computing tasks, the overhead of virtualization becomes a big portion in the wall time, hence it leads to low CPU efficiency of the jobs. With the wide usage of containers in HEP computing, we explore the possibility of adopting the container technology into the ATLAS BOINC project, hence we implemented a Native version in BOINC, which uses the singularity container or direct usage of the target OS to replace VirtualBox. In this paper, we will discuss 1) the implementation and workflow of the Native version in the ATLAS BOINC; 2) the performance measurement of the Native version comparing to the previous Virtualization version. 3)...

  3. Effect of material parameters on the compactibility of backfill materials

    International Nuclear Information System (INIS)

    Keto, P.; Kuula-Vaeisaenen, P.; Ruuskanen, J.

    2006-05-01

    The effect of different parameters on compactibility of mixture of bentonite and ballast as well as Friedland-clay was studied in laboratory with two different types of compaction tests. The material parameters varied were grain size distribution of the ballast material, grain shape, water ratio and bentonite content (15/30%). The other parameters varied were salinity of the mixing water, mixing process and compaction method and energy. Ballast materials with varying grain size distributions were produced from Olkiluoto mica-gneiss with different type of crushing processes. In addition, sand was chosen for ballast material due to its uniform grain size distribution and rounded grain shape. The maximum grain size of the ballast materials was between 5-10 mm. When comparing the compactibility of ballast materials, the highest dry densities were gained for ballast materials with graded grain size distribution. The compaction behaviour of the tested bentonite ballast mixtures is dominated by the bentonite content. The other parameters varied did not have significant effect on the compactibility of the mixtures with bentonite content of 30%. This can be explained with the amount of bentonite that is higher than what is needed to fill up the volume between the ballast grains. The results gained with the two different compaction tests are comparable. Both the bentonite/ballast mixtures and the Friedland clay behaved similarly when compacted with three different compaction pressures (180, 540 and 980 kPa). (orig.)

  4. geophysical investigation of abandoned back-filled railway line

    African Journals Online (AJOL)

    ABAYOMI ADESOLA OLAOJO, MICHAEL ADEYINKA OLADUNJOYE AND MORUFFDEEN. ADEDAPO ADABANIJA. (Received 01 April ... terrain has gentle undulation and relatively flat and its. 37. Abayomi Adesola Olaojo, Department of .... Conference, 8:1423-1433. Akintorinwa, O. J and Adeusi, F. A., 2009. Integration of.

  5. 30 CFR 715.14 - Backfilling and grading.

    Science.gov (United States)

    2010-07-01

    ... implement the postmining land use plan. (ii) The vertical distance between terraces shall be as specified by... case may highwalls be left as part of terraces. (iv) Culverts and underground rock drains shall be used...

  6. Prevention of spontaneous combustion of backfilled plant waste material.

    CSIR Research Space (South Africa)

    Adamski, SA

    2003-06-01

    Full Text Available Since Grootegeluk Coal Mine commenced operation in 1980 all plant discards and inter-burden material have been stacked on discards dumps, a practice that has led to the spontaneous combustion of the waste material on these dumps. From 1980 to 1988...

  7. Study on low permeable backfill materials. Backfill materials for waste disposal facilities; Koshisuisei juten zairyo ni kansuru kenkyu. Hoshasei haikibutsu shobun shisetsu eno tekiyosei kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Shiraishi, F; Konishi, M; Shiraishi, H [Okumura Corp., Osaka (Japan)

    1994-11-15

    A discussion was given on the fundamental properties of mortar made from cement mixed with silica fume. Four kinds of silica fumes with different particle size distributions were used. The following results were obtained: distribution of pores in mortar admixed with silica fume shifts to the smaller radius side; while the admixture increases the compression strength in mortar, the increasing trend varies depending on the kinds of silica fumes; this is thought to be caused from the difference in pozzolan activity between silica fumes; and the strength increase is caused by densification of the structure due to the pozzolan reaction that is generated after hydration, or in other words, decrease in the pore volume. The applicability of the mortar was investigated as a filling mortar to fill up clearances between wastes. It was found that the filling performance can be controlled by mixing silica fume at an adequate level and adjusting the viscosity. The diffusion coefficient for the admixed concrete is smaller by 30% to one digit than that for the ordinary concrete. High-performance water stopping concrete of 0.11 {times} 10{sup 4}cm {sup 2}/s at maximum was obtained. The concrete can be regarded as a material having superb filling and water stopping performances. 6 refs., 4 figs., 5 tabs.

  8. Placement of pre-compacted and in situ compacted dense backfill materials in shaft seals

    International Nuclear Information System (INIS)

    Martino, J.; Dixon, D.; Kim, C.S.

    2010-01-01

    Document available in extended abstract form only. In 2003, a decision was made to discontinue operation of Atomic Energy of Canada Limited's (AECL's) Underground Research Laboratory (URL) and ultimately to decommission and permanently close the underground portion of this facility. As part of the Nuclear Legacy Liability Program (NLLP) being funded by Natural Resources Canada (NRCan), an ongoing program of work is being undertaken to decommission and deal with facilities that are no longer part of AECL's mandate or operations. The URL is included in these facilities. Part of this work is the installation of seals at the intersection of the access and ventilation shafts and an ancient thrust fault, Fracture Zone 2 (FZ2), approximately 275 m below surface. These seals are being installed in order to limit the potential for mixing of deeper saline and shallower, less saline groundwater. The seal design in each shaft is similar with a heavily reinforced lower concrete component, a central bentonite clay-sand component and an upper un-reinforced concrete component. The main shaft at the URL at the location of the seal is circular (∼5-m diameter), and was excavated using careful drill and blast techniques. The seal itself consists of two keyed, conical sectioned, 3-m-thick by 5 to 6-m diameter concrete segments that confine a 6-m-thick swelling clay section. The ventilation shaft at the URL is 1.8 m in diameter and was excavated using raise-boring. The ventilation shaft will consist of two keyed, conical sectioned, 2-m-thick concrete by 1.8 to 2.8 m diameter concrete segments confining a 5-m-thick assembly of pre-compacted clay-sand blocks. The concrete is a low pH concrete designed for repository use, which can develop a 70 MPa unconfined compressive strength after 28 days. It has a pH of less than 11 achieved by substitution of 75% of the cement powder with silica fume and ground silica so the likelihood of free calcium and an alkaline plume is greatly reduced. The concrete provides confinement for the swelling clay. Two approaches were taken for the central clay unit in each seal. The main shaft uses compacted in situ clay-based material with 40% dry mass Wyoming sodium bentonite (200 mesh gradation), and 60% uniform gradation, water washed sand (< 2% of - 200 mesh size), with a target dry density of 1.80 ± 0.05 Mg/m 3 . The ventilation shaft uses pre-compacted clay blocks composed of 70% Kunigel V1 bentonite and 30% uniform gradation, water washed sand. These blocks were originally prepared in 1998 for the Tunnel Sealing Experiment (TSX) and unused materials were stored underground under plastic sheets. The blocks were designed to be hand placed and are approximately 35 cm x 10 cm x 18 cm in size which is convenient for use in construction of the ventilation shaft seal. In situ compaction required pre-blending of the clay-based material in order to achieve a clay component that is homogeneous with respect to density and initial degree of saturation. Because of the volume involved and in order to test a technique that is both time and cost efficient regarding material preparation, a conventional concrete dry batching truck was utilized. An auger on the truck blended the raw materials, with a water tank supplying the required water. The resulting material was bagged and stored for use once it was quality checked. Clay was delivered to the seal location in the main shaft once the lowermost concrete portion of the seal was cured for 28 days. The bagged clay was transferred to a shaft clam-shell bucket and transported to the seal location and then dumped. The clay material was manually spread to an initial ∼20 cm thickness for compaction and once compaction was completed each lift was approximately 10 cm in thickness. The clay volume in the shaft is approximately 117 m 3 (6-m-thick). Compaction was accomplished by use of two relatively small, hand-operated impact compactors. Along the perimeter of the shaft (and in areas where instrument cables were installed) a smaller impact compactor was used. The compaction and other construction operations needed to be conducted carefully as the concrete, clay and surrounding rock mass of main shaft seal are being monitored via a suite of approximately 60 sensors that record temperature, strain, hydraulic and mechanical pressure as well as water content within the seal. Hand tamping was performed immediately around the cables as necessary to protect them. This paper presents the details of the work completed in the main shaft of late fall of 2009. The ventilation shaft clay placement will involve a volume of approximately 13 m 3 and utilize techniques developed in the TSX. Blocks will be cut as required and field fitted into the space where the seal is located. Granular or pelletized bentonite will be poured and compacted as space permits at the perimeter in any gaps that remain after block installation. This seal will not be monitored but past work has indicated that low hydraulic conductivities can be achieved under a high hydraulic gradient for clay seal components constructed from pre-compacted blocks. The operational experiences and lessons learned from installation of both clay barrier types will be discussed in the paper. (authors)

  9. Performance of concrete backfilling materials for shafts and tunnels in rock formations

    International Nuclear Information System (INIS)

    Casson, R.B.J.

    1985-10-01

    Preplaced Aggregate Concrete (PAC) consists of graded coarse aggregate, placed and packed into position, and then immobilised by cementitious grout injected into the voids between the aggregate pieces. PAC is also reported to be amenable to mechanical/ remote placement and have usefully improved properties when compared with conventionally placed concretes. This study attempts to establish the validity of these claims both from reported experience and by practical demonstration through experimentation. A literature study supported the claims made for the PAC system but all reported experiences recorded the use of organic admixtures in order to obtain the improved concrete properties. Because of the lack of long term durability data on such admixtures especially in a radiation environment, it was decided to prepare a sample of PAC without organic admixtures. Considerable experimental difficulties were encountered in obtaining a satisfactory quality 1m cube of PAC from which test specimens could be cut. The necessary grout fluidity was only achieved by the inclusion of bentonite. The test data collected indicates that the PAC system employed on this occasion did not improve either the short term or longer term mechanical properties compared with conventional concretes. (author)

  10. Study of backfilling of fissures in granite by precipitation of silica

    International Nuclear Information System (INIS)

    Ribstein, A.; Ledoux, E.; Bourg, A.; Oustriere, P.; Sureau, J.F.

    1985-01-01

    The discharge of high-activity radioactive wastes in granitic formations heats the rock in the area of the waste repository. Silica, a constituent of granite, may be dissolved by subterranean water in the heated area and reprecipitated in the colder outer zone. The aim of this study is to quantify this phenomenon experimentally and to assess its extent and effects by means of a numerical model

  11. Microstructures and physical properties of "backfill" clays: comparison of residua and sedimentary montmorillonite clays

    Czech Academy of Sciences Publication Activity Database

    Přikryl, R.; Ryndová, T.; Boháč, J.; Weishauptová, Zuzana

    2003-01-01

    Roč. 23, 1-4 (2003), s. 149-156 ISSN 0169-1317 R&D Projects: GA AV ČR IAA2046101 Institutional research plan: CEZ:AV0Z3046908 Keywords : bentonite * montmorillonite-rich clay * hydrophysical properties Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.287, year: 2003

  12. Draft Test Plan for Brine Migration Experimental Studies in Run-of-Mine Salt Backfill

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Amy B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stauffer, Philip H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reed, Donald T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Boukhalfa, Hakim [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Caporuscio, Florie Andre [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Robinson, Bruce Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-02

    The primary objective of the experimental effort described here is to aid in understanding the complex nature of liquid, vapor, and solid transport occurring around heated nuclear waste in bedded salt. In order to gain confidence in the predictive capability of numerical models, experimental validation must be performed to ensure that (a) hydrological and physiochemical parameters and (b) processes are correctly simulated. The experiments proposed here are designed to study aspects of the system that have not been satisfactorily quantified in prior work. In addition to exploring the complex coupled physical processes in support of numerical model validation, lessons learned from these experiments will facilitate preparations for larger-scale experiments that may utilize similar instrumentation techniques.

  13. Numerical simulation of scour and backfilling processes around a circular pile in waves

    DEFF Research Database (Denmark)

    Baykal, Cüneyt; Sumer, B. Mutlu; Fuhrman, David R.

    2017-01-01

    –Stokes equations. The modelincorporates (1) k-ω turbulence closure, (2) vortex shedding processes, (3) sediment transport (both bed andsuspended load), as well as (4) bed morphology. The numerical simulations are carried out for a selected set oftest conditions of the laboratory experiments of Sumer et al. (1997......, 2013a), and the numerical results arecompared with those of the latter experiments. The simulations are carried out for two kinds of beds: rigid bed,and sediment bed. The rigid-bed simulations indicate that the vortex shedding for waves around the pile occursin a “one-cell” fashion with a uniform...... shedding frequency over the height of the cylinder, unlike the case forsteady current where a two-cell structure prevails. The rigid-bed simulations further show that the horseshoevortex flow also undergoes substantial changes in waves. The amplification of the bed shear stress around thepile (including...

  14. Influence of backfill moisture content on the pullout capacity of geotextile reinforcement in MSE walls.

    Science.gov (United States)

    2012-12-01

    Sources of high-quality soils to meet design standards for the construction of reinforced soil structures are : in many cases rare and in short supply. An economical alternative to coarse-grained, free-draining soils : consists of using locally avail...

  15. CTL Industries simplifies mining processes : fill containment system a simple solution for backfilling stopes

    Energy Technology Data Exchange (ETDEWEB)

    Larmour, A.

    2010-12-01

    Several large mining companies are interested in a patent-pending fill containment system designed to replace shotcrete fences after a stope has been filled. The existing process is extremely labour and material intensive. This article discussed how the new system has made work easier, safer and increased the bottom line. The article described the design and specifications of the shotcrete containment system. The advantages of the system include no wait time for customers for shotcrete teams to build fences, and it is a quick, easy process that takes about 3 hours to set up, inflate and fill. The article also outlined a shaft guide electronic profiling mechanism that had been developed to complement the shaft guide laminating device. The product electronically measures shaft guides in mine shafts to determine how much wear has occurred on the timber. Last, the article described a refuge station door sealant kit with a cabinet that contains items required to seal the refuge station door should an emergency occur. This quick and easy system replaces the previous method in which clay slugs are soaked in a five-gallon pail of water and applied by hand. 1 ref., 1 fig.

  16. Study of backfill material composition for shallow land radioactive wastes disposal

    International Nuclear Information System (INIS)

    Sukarman-Aminjoyo; Sukrosono; Supardi

    1996-01-01

    The composition of back fill material for shallow land radioactive wastes disposal has been investigated by using bentonite, magnetic and quartz sands. The aim of this research is to observe the kind of mineral suitable for back fill material. The research was done for each mineral material and for the mixture of those three minerals. Firstly 2 grams of bentonite. magnetite or quartz sand was put into a glass column of 1.2 cm in diameter. Then the Sr-90 liquid waste was flown through out the column. In this experiment the adsorption velocity, through velocity, adsorption capacity and decontamination factor were determined for the grain size of 10 up to 100 mesh. By the same method the experiment was done for the mix of those three minerals. The experiment result indicated that the grain size mineral influenced the parameter of adsorption velocity, through velocity, adsorption capacity and decontamination factor. The relatively good result was obtained for the grain size of 80 mesh. Among the three kinds of minerals, bentonite had the highest of adsorption capacity and decontamination factor, while its adsorption velocity and through velocity were the lowest. The mixture of that three minerals gave better result than that mixture of two mineral component. The usage of the mineral mixture with the grain size of 80 mesh and the weight ratio between that component of 1:1:1, resulted in the decontamination factor of 68.44, the adsorption capacity of 235 ml/g, the adsorption velocity of 31x10 -3 ml/sec. and the through velocity of 1.82x10 -3 ml/sec

  17. [Radiographic appraisal between metal and bone interosculate backfill after total hip arthroplasty with trabecular metal cup].

    Science.gov (United States)

    Li, Wei; Zhou, Yi-Xin; Wu, Jian; Xu, Hui; Ji, Song-Jie

    2009-02-15

    To evaluate the bone refilling in the interface between the trabecular metal (TM) acetabular shell and the bone surface according to consecutive X film measuring after surgery. From July 2006 to July 2007, 35 patients (40 hips) accepted total hip replacement using trabecular metal monoblock acetabular cup system (TM). The cup was made of a ellipse shaped press fit Tantalum shell and high cross-linked PE liner (Longevity) with 28 mm inner diameter. The patients demography was: 16 male (20 hips), 19 female (20 hips), 5 bilateral hip replacements, age from 41 - 71 (mean 53), including 18 avascular necrosis hips, 16 osteoarthritis hips (including those secondary to a dysplasia hip), 4 avascular necrosis hips after femoral neck fracture, 2 Ankylosis Spondylitis. All the 40 total hip replacements used posterior approach, using hemispherical acetabular reamer and 2 mm press fit of final metal shell without screw fixation. The consecutive X film was taken at the end time of surgery and 2, 6, 12, 24 weeks, and 12 months. The clinical results was evaluate according to Harris scoring system, and the standard pelvis AP X film was measured at the interface between metal shell and the acetabular bone surface, witch was divided into five regions (A, B, C, D, E). Totally 32 patients (37 hips) were followed with average 8.7 months (7 - 12 months). The Harris before surgery was 50.5 (32 - 85), promoted to 91.0 (72 - 100), including 29 excellent, 6 good, 2 fair, and the total excellent and good rate was 94.6%. Complications include 4 patients leg length discrepancy from 1 - 2 cm, 3 patients moderate thigh pain and released after conservative therapy. No infection and dislocation was found. Twenty-one patients (23 hips) were found lucent line at the bone-metal interface from 1 - 5 mm, most common in B region and BC boundary than C, D, and CD boundary. All the patients followed was found the lucent line disappeared and refilled with bone at X film 24 weeks after surgery, however, no patients was found osteolysis and cup migration. The trabecular metal has strong capacity of bone conductive and bone inducement.

  18. Geochemical studies of backfill aggregates, lake sediment cores and the Hueco Bolson Aquifer

    Science.gov (United States)

    Thapalia, Anita

    This dissertation comprises of three different researches that focuses on the application of geochemistry from aggregates, lake sediment cores and Hueco Bolson Aquifer. Each study is independent and presented in the publication format. The first chapter is already published and the second chapter is in revision phase. Overall, three studies measure the large scale (field) as well as bench scale (lab) water-rock interactions influenced by the climatic and anthropogenic factors spans from the field of environmental geology to civil engineering. The first chapter of this dissertation addresses the chemical evaluation of coarse aggregates from six different quarries in Texas. The goal of this work is to find out the best geochemical methods for assessing the corrosion potential of coarse aggregates prior to their use in mechanically stabilized earth walls. Electrochemical parameters help to define the corrosion potential of aggregates following two different leaching protocols. Testing the coarse and fine aggregates demonstrate the chemical difference due to size-related kinetic leaching effects. Field fines also show different chemistry than the bulk rock indicating the weathering impact on carbonate rocks. The second chapter investigates zinc (Zn) isotopic signatures from eight lake sediment cores collected both from pristine lakes and those impacted by urban anthropogenic contamination. Zinc from the natural weathering of rocks and anthropogenic atmospheric pollutants are transported to these lakes and the signatures are recorded in the sediments. Isotopic analysis of core samples provides the signature of anthropogenic contamination sources. Dated sediment core and isotopic analysis can identify Zn inputs that are correlated to the landuse and population change of the watersheds. Comparison of isotopic data from both pristine and urban lake sediment core also serves as an analog in other lake sediment cores in the world. The third chapter studies on Hueco Bolson Aquifer that an important sources of water in the El Paso/Cd. Juraez metroplex. To delineate the boundary between fresh and brackish water from the northern Hueco Bolson Aquifer, we utilize an integrative geochemical, geophysical, and sedimentological approach. The goal of this study is to use geophysical well-log analysis and the water chemical analysis for identifying the changes in the quality of the groundwater. A detailed microgravity survey is utilized to explore the subsurface geological structures that control the conduits and/or barriers of groundwater flow. A detailed geochemical analysis of aquifer samples provide salinity of groundwater that will complement to the subsurface structures obtained from the geophysical study. This fundamental research in developing methods from an integrated approach to estimate aquifer quality can be used as an analog for similar studies in other arid regions.

  19. Mineralogical, chemical and physical study of potential buffer and backfill materials from ABM. Test Package 1

    International Nuclear Information System (INIS)

    Kumpulainen, S.; Kiviranta, L.

    2011-07-01

    In the ABM experiment, three test packages with centre steel heaters surrounded by stacks of compacted bentonite rings of various clay materials were placed in boreholes in Aespoe tunnel. The first parcel was saturated with Aespoe groundwater and the heater was turned on simultaneously with the start of saturation. This parcel was excavated 30 months after its installation. Chemical, mineralogical and physical properties of the MX-80, Dep-CaN, Asha and Friedland clay samples from the ABM parcel 1 were analysed and compared to reference samples. Chemical analyses (ICP-AES, C, CO 3 , S, water soluble SO 4 , Fe 2+ /Fe 3+ ), exchangeable cation analyses, mineralogical analyses (XRD, FTIR) and selective extractions were used to determine changes in the chemistry and mineralogy of ABM materials. Swelling pressure and hydraulic conductivity measurements were performed both for extracted samples and for ground and recompacted samples. Major changes in exchangeable cation composition were observed in all samples originating from equilibration with Aespoe groundwater and interactions with equilibrated waters from neighbouring block materials. Some minor changes in chemical composition were observed as well. Increases in soluble sulphate content in the vicinity of the heater were thought to result from precipitation of sulphate salts. Decreases in sodium content and increases in calcium content were ascribed to changes in exchangeable cations. Interaction with iron was observed to occur only in the close vicinity (first few mm) of the heater. No significantly measureable change in mineralogical composition was seen in any of the studied materials. Extracted Dep-CaN samples showed a slight decrease in swelling pressure. However, when the material was ground, compacted and measured again the swelling pressure was fully recovered. No related change in hydraulic conductivities was observed. (orig.)

  20. Properties of container and backfill materials for the final disposal of highly radioactive fission products

    International Nuclear Information System (INIS)

    Mirschinka, V.

    1983-11-01

    The qualifications of six metallic alloys to serve as canister materials for an in-can glass smelting process were studied. These alloys are: N 6 1.4864 (X 12NiCrSi3616, Thermax 16/36), No. 2.4816 (NiCr15Fe, Inconel 600), No. 2.4610 (Hastelloy C4), No. 2.4778 (UMCO50), No. 1.5415 (15MO3), No. 1.1005 (ZSH-Spezial). The mechanical properties of any of the six materials at high temperatures were found to be sufficient. The chemical interactions between glass and metal were investigated by glass smelting tests and electron microprobe analyses, showing that chromium as an alloying element of the crucible material may affect the quality of the glass product by causing inhomogeneities and a violent blistering in the glass matrix. The resistance against corrosion by concentrated salt solutions under elevated pressure and temperature similar to final depository conditions was tested showing that the presence of a bentonite suspension in the salt solution reduces the corrosion attack of the metal significantly. Diffusion experiments of salt solutions doted with radioactive isotopes Na-22 and Cl-36 as tracer substances were made to show the retardation behaviour of salt ions in compacted bentonite. However, a long-term barrier effect of the bentonite against salt ion diffusion could not be verified. (orig./HOE)

  1. An evaluation of the effectiveness of backfill as regional support in reducing seismicity

    CSIR Research Space (South Africa)

    Hemp

    1992-05-01

    Full Text Available stream_source_info Hemp_1992.pdf.txt stream_content_type text/plain stream_size 36 Content-Encoding ISO-8859-1 stream_name Hemp_1992.pdf.txt Content-Type text/plain; charset=ISO-8859-1 ...

  2. Depleted uranium oxides as spent-nuclear-fuel waste-package invert and backfill materials

    International Nuclear Information System (INIS)

    Forsberg, C.W.; Haire, M.J.

    1997-01-01

    A new technology has been proposed in which depleted uranium, in the form of oxides or silicates, is placed around the outside of the spent nuclear fuel waste packages in the geological repository. This concept may (1) reduce the potential for repository nuclear criticality events and (2) reduce long-term release of radionuclides from the repository. As a new concept, there are significant uncertainties

  3. Feasibility of backfilling mines using cement kiln dust, fly ash, and cement blends

    OpenAIRE

    Beltagui, Hoda; Sonebi, Mohammed; Maguire, K.; Taylor, Susan

    2018-01-01

    Cement kiln dust (CKD) is an industrial by-product of the cement manufacturing process, the composition of which can vary widely. Recent years of using alternative fuels have resulted in higher chloride and alkali contents within CKDs; as such, this limits the applications in which CKDs can be utilised. Using a CKD containing a high free lime content of 29.5%, it is shown that this CKD is capable of activating pulverized fuel ash (PFA) due to its high alkalinity, which can be utilised in low ...

  4. Refinement of Foam Backfill Technology for Expedient Airfield Damage Repair- Phase I: Laboratory Evaluation of Foam Materials

    Science.gov (United States)

    2016-11-01

    trend is expected, because the foam materials are primarily composed of the same compounds ; only minor differences in the formula- tions are present...process. Fracture of this nature may be expected during use of this material in the field. ERDC TR-16-16 33 Figure 22. Foam-iT! SLOW specimens...Slow were produced with flat bottoms. However, this material was fairly brittle, as indicated by the fracturing observed on one of the specimens shown

  5. The influence of discontinuity interfaces on physical, chemical and mechanical properties and the behaviour of repository backfill materials (Czech Republic)

    International Nuclear Information System (INIS)

    Slovak, J.; Pacovsky, J.

    2000-01-01

    Safe disposal (isolation) of high radioactive waste requires solving many non-standard engineering problems which are complicated due to the demand of reliability of underground repository construction with respect to long term safety. Required durability of most engineered structures is about 10-100 years. Proposed underground repository construction must guarantee the demand for safe disposal of highly radioactive waste for 100 thousand to 1 million years. Extrapolation methodologies are developed and applied on findings of experimental research. One of the techniques is used in geotechnical sciences to determine data needed for the extrapolation the cyclical impact of different processes. Repeated impact of the same action or diversifying the different actions can accelerate some processes which are slow at normal conditions. Long term cyclical impact of moisture on a section of the barrier system (loaded by temperature) may cause changes of the quality of properties, such as permeability, sorption capacity, thermal conductivity and swelling capacity. (author)

  6. 30 CFR 717.14 - Backfilling and grading of road cuts, mine entry area cuts, and other surface work areas.

    Science.gov (United States)

    2010-07-01

    ... control, or roads. (2) The vertical distance between terraces shall be as specified by the regulatory... as part of terraces. (4) Culverts and underground rock drains shall be used on the terrace only when...

  7. Hydraulic properties of domestic bentonite-sand mixture as a backfill material in the high-level waste repository

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Won Jin; Lee, Jae Owan; Kang, Chul Hyung [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2000-02-01

    This study is intended to investigate the effect of dry density and sand content on hydraulic conductivities of bentonite-sand mixtures. The hydraulic conductivities of bentonite-sand mixtures with dry densities of 1.6 and 1.8 Mg/m{sup 3} are lower than 10{sup -11} m/s if their sand contents are less than 70 wt%. However at the sand content of 90 wt%, the hydraulic conductivities increase sharply. In the case of sand contents not exceeding 70 wt%, the logarithm of the hydraulic conductivity of bentonite-sand mixture increase linearly with increasing sand content. The hydraulic conductivity of the mixture can be explained using 'effective clay dry density' concept. 16 refs., 21 figs., 5 tabs. (Author)

  8. Electrophoretically active sol-gel processes to backfill, seal, and/or densify porous, flawed, and/or cracked coatings on electrically conductive material

    Science.gov (United States)

    Panitz, Janda K.; Reed, Scott T.; Ashley, Carol S.; Neiser, Richard A.; Moffatt, William C.

    1999-01-01

    Electrophoretically active sol-gel processes to fill, seal, and/or density porous, flawed, and/or cracked coatings on electrically conductive substrates. Such coatings may be dielectrics, ceramics, or semiconductors and, by the present invention, may have deposited onto and into them sol-gel ceramic precursor compounds which are subsequently converted to sol-gel ceramics to yield composite materials with various tailored properties.

  9. Experimental Research on Foamed Mixture Lightweight Soil Mixed with Fly-Ash and Quicklime as Backfill Material behind Abutments of Expressway Bridge

    Directory of Open Access Journals (Sweden)

    Xin Liu

    2017-01-01

    Full Text Available To promote the utilization of fly-ash, based on the orthogonal experiment method, wet density and unconfined compressive strength of Foamed Mixture Lightweight Soil mixed with fly-ash and quicklime (FMLSF are studied. It is shown that the wet density and unconfined compressive strength of FMLSF increase with the increase of cement content, while decreasing with the increase of foam content. With the mixing content of fly-ash increase, the wet density and unconfined compressive strength of FMLSF increase firstly and then decrease. Scanning Electron Microscope (SEM tests show that ball effect or microaggregate effect of fly-ash improves the wet density and unconfined compressive strength of FMLSF. With the mixing content of quicklime increase, the wet density and unconfined compressive strength of FMLSF increase firstly within a narrow range and then decrease. In addition, the primary and secondary influence order on wet density and 28-day compressive strength of FMLSF are obtained, as well as the optimal mixture combination. Finally, based on two abutments in China, behind which they are filled with FMLSF and Foamed Mixture Lightweight Soil (FMLS, the construction techniques and key points of quality control behind abutment are compared and discussed in detail, and the feasibility of utilization fly-ash as FMLSF is verified by the experimental results.

  10. Design considerations for sealing the shafts of a nuclear fuel waste disposal vault

    International Nuclear Information System (INIS)

    Mortazavi, M.H.S.; Chan, H.T.; Radhakrishna, H.S.

    1985-05-01

    The shafts in an underground disposal system, which constitute potential pathways between the disposal vault and the biosphere, should be effectively sealed if the system is to perform as a hydrodynamic and geochemical barrier for the safe containment of nuclear fuel waste. In the design of the shaft backfill, consideration should be given to ensure that the backfill and the backfill/rock interface remain intact. Design-related problems, including critical pathways for the transport or radionuclides, configuration of shaft backfill and its functional requirements, the state of stress in a backfilled shaft with particular emphasis on the arching and load transfer phenomenon are discussed in this report

  11. Consequences of using crushed crystalline rock as ballast in KBS-3 tunnels instead of rounded quartz particles

    International Nuclear Information System (INIS)

    Push, R.

    1995-02-01

    The basic question has been whether such replacement alters the hydraulic conductivity and compressibility as well as expandability and also if the physical and chemical stabilities are altered. The key factor is the microstructural constitution of the bentonite/ballast mixtures, which is primarily controlled by the grain size distribution of the ballast. The compact ability of backfills with quartz sand (SB) is higher than that of backfills with crushed rock as ballast (RB). The physical stability of RB backfills in terms of piping and erosion resistance will be somewhat lower than that of SB backfills. The chemical stability is practically independent of whether the ballast is pure quartz or rock with K-bearing minerals because the temperature in the backfill will be too low to yield significant smectite to illite conversion in the short heating period. In order to reach the same densities of SB and RB backfills, which turn out to give fairly similar physical properties, the latter backfills need more effective compaction or, alternatively, a higher bentonite content. It is estimated that if the bentonite content in RB backfills is not increased while the density is enhanced to what is achievable, these backfills will serve equally well as SB backfills with the densities implied by the basic KBS-3 concept. 23 refs, 27 figs, 7 tabs

  12. Consequences of using crushed crystalline rock as ballast in KBS-3 tunnels instead of rounded quartz particles

    Energy Technology Data Exchange (ETDEWEB)

    Push, R [Clay Technology AB (Sweden)

    1995-02-01

    The basic question has been whether such replacement alters the hydraulic conductivity and compressibility as well as expandability and also if the physical and chemical stabilities are altered. The key factor is the microstructural constitution of the bentonite/ballast mixtures, which is primarily controlled by the grain size distribution of the ballast. The compact ability of backfills with quartz sand (SB) is higher than that of backfills with crushed rock as ballast (RB). The physical stability of RB backfills in terms of piping and erosion resistance will be somewhat lower than that of SB backfills. The chemical stability is practically independent of whether the ballast is pure quartz or rock with K-bearing minerals because the temperature in the backfill will be too low to yield significant smectite to illite conversion in the short heating period. In order to reach the same densities of SB and RB backfills, which turn out to give fairly similar physical properties, the latter backfills need more effective compaction or, alternatively, a higher bentonite content. It is estimated that if the bentonite content in RB backfills is not increased while the density is enhanced to what is achievable, these backfills will serve equally well as SB backfills with the densities implied by the basic KBS-3 concept. 23 refs, 27 figs, 7 tabs.

  13. Parametric study of the effects of thermal environment on a waste package for a tuff repository

    Energy Technology Data Exchange (ETDEWEB)

    Johnstone, J K; Sundberg, W D; Krumhansl, J L [Sandia National Laboratories Albuquerque, NM, (USA)

    1982-12-31

    The thermal environment has been modeled in a simple reference waste package in a tuff repository for a variety of variables. The waste package was composed of the waste form, canister, overpack and backfill. The emplacement hole was 122cm dia. Waste forms used in the calculations were commercial high level waste (CHLW) and spent fuel (SF). Canister loadings varied from 50 to 100 kW/acre. Primary attention was focused on the backfill behavior in the thermal and chemical environment. Results are related to the maximum temperature calculated for the backfill. These calculations raise serious concerns about the effectiveness of the backfill within the context of the total waste package.

  14. The repair of ground cover of Bolivia-Brazil gas pipeline near Paraguay River crossing, in a swamp soft soil region, using geo synthetics reinforced backfilling; Reparo da cobertura do gasoduto Bolivia-Brasil junto ao Rio Paraguai, em trecho com solo mole, utilizando aterro reforcado com geosinteticos

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Cesar Augusto; Jorge, Kemal Vieira; Bechuate Filho, Pedro [TBG - Transportadora Brasileira Gasoduto Bolivia Brasil S.A., Campo Grande, MS (Brazil). Gerencia Regional Centro Oeste (CRGO); Teixeira, Sidnei H.C. [Geohydrotech Engenharia S.C. Ltda., Braganca Paulista, SP (Brazil)

    2005-07-01

    TBG - Transportadora Gasoduto Bolivia-Brasil S.A, executes routine maintenance works at the Gas Pipeline Right of Way, seeking its integrity. In the wetlands of Pantanal, near the Paraguay river crossing, the organic-alluvial soil was submitted to the process of subsidence. This process, associated with the river water flow erosion, shrank the soil volume and diminished or extinguished the pipeline land cover. The pipeline was exposed to the environment, and submitted to tension stresses and the risk of low cycle fatigue during the floods. The cathodic protection system also had to be evaluated, specially in the drought. To mitigate the problem, the embankment technique was adopted using sandy soil, reinforced with polyester geo-webs and with woven polipropene geo-textiles. The solution also used geo-webs with soil-cement as protection elements against the degradation of the geo-textiles blankets. Some monitoring works are associated with those interventions: monitoring of cathodic protection; topographical verification of horizontal and vertical displacements of the pipeline; levels of land covering, and rainfalls and flood measurement. The base of the embankment was built with hydraulic transported soil, and at the end consistently supported the gas pipeline. (author)

  15. Operational forest stream crossings effects on water quality in the Virginia Piedmont

    Science.gov (United States)

    Wallace M. Aust; Matthew B. Carroll; M. Chad Bolding; Andy Dolloff

    2011-01-01

    Water quality indices were examined for paired upstream and downstream samples for 23 operational stream crossings and approaches during four periods. Stream crossings were (1) portable bridges (BRIDGE), (2) culverts backfilled with poles (POLE), (3) culverts with earth backfill (CULVERT), and (4) reinforced fords (FORD). The four operational periods were (1) prior to...

  16. Geochemical assessment of nuclear waste isolation. Report of activities during fiscal year 1982

    International Nuclear Information System (INIS)

    1983-07-01

    The status of the following investigations is reported: canister/overpack-backfill chemical interactions and mechanisms; backfill and near-field host rock chemical interactions mechanisms; far-field host rock geochemical interactions; verification and improvement of predictive algorithms for radionuclide migration; and geologic systems as analogues for long-term radioactive waste isolation

  17. Geochemical assessment of nuclear waste isolation. Report of activities during fiscal year 1982

    Energy Technology Data Exchange (ETDEWEB)

    1983-07-01

    The status of the following investigations is reported: canister/overpack-backfill chemical interactions and mechanisms; backfill and near-field host rock chemical interactions mechanisms; far-field host rock geochemical interactions; verification and improvement of predictive algorithms for radionuclide migration; and geologic systems as analogues for long-term radioactive waste isolation.

  18. LOAD ON BURIED PRESSURE CONDUITS WITH REFERENCE TO ...

    African Journals Online (AJOL)

    width of conduit or trench; the shearing forces on the plane between the backfill and adjacent earth; for embankment condition, the amounL of relative settlement between the backfill and adjacent earth; the rigidity of the conduit support under embankment loading. Table 3. Selected values of c'' for use in Eq. 8. Sand and.

  19. Sadhana | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Numerical modelling of mine backfill material needs special attention as the numerical model must behave realistically and in accordance with the site conditions. This paper discusses a numerical modelling strategy for modelling mine backfill material. Themodelling strategy is studied using a case study mine from ...

  20. Information base for waste repository design. Volume 5. Decommissioning of underground facilities

    International Nuclear Information System (INIS)

    Guiffre, M.S.; Plum, R.L.; Koplick, C.M.; Talbot, R.

    1979-01-01

    This report discusses the requirements for decommissioning a deep underground facilitiy for the disposal of radioactive waste. The techniques for sealing the mined excavations are presented and an information base on potential backfill materials is provided. Possible requirements for monitoring the site are discussed. The performance requirements for backfill materials are outlined. The advantages and disadvantages of each sealing method are stated

  1. 44 CFR 208.39 - Reimbursement for personnel costs incurred during Activation.

    Science.gov (United States)

    2010-10-01

    ...) Reimbursement of additional salary and overtime costs. DHS will reimburse any identified additional salary and...). (g) Reimbursement for Backfill costs upon Activation. DHS will reimburse the cost to Backfill System... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Reimbursement for personnel...

  2. P.Y. Okyere

    African Journals Online (AJOL)

    Administrator

    ABSTRACT. In this study, the efficiency of materials available for free, namely palm kernel oil cake, tyre ash, wood ash and powdered cocoa shell, as conductive backfill for reducing earth electrode resis- tance was evaluated. Earth rod of 30-cm length and 14-mm diameter was installed for each backfilling material at a site ...

  3. An analysis of the factors affecting the hydraulic conductivity and swelling pressure of Kyungju ca-bentonite for use as a clay-based sealing material for a high level waste repository

    International Nuclear Information System (INIS)

    Cho, Won Jin; Lee, Jae Owen; Kwon, Sang Ki

    2012-01-01

    The buffer and backfill are important components of the engineered barrier system in a high-level waste repository, which should be constructed in a hard rock formation at a depth of several hundred meters below the ground surface. The primary function of the buffer and backfill is to seal the underground excavation as a preferred flow path for radionuclide migration from the deposited high-level waste. This study investigates the hydraulic conductivity and swelling pressure of Kyungju Ca-bentonite, which is the candidate material for the buffer and backfill in the Korean reference high-level waste disposal system. The factors that influence the hydraulic conductivity and swelling pressure of the buffer and backfill are analyzed. The factors considered are the dry density, the temperature, the sand content, the salinity and the organic carbon content. The possibility of deterioration in the sealing performance of the buffer and backfill is also assessed.

  4. Experimental Study on the Interaction Between Contacting Barrier Materials for Containment of Radioactive Wastes

    Science.gov (United States)

    Huang, W. H.; Chang, H. C.

    2017-12-01

    The disposal of low- and intermediate-level radioactive wastes requires use of multi-barriers for isolation of the wastes from the biosphere. Typically, the engineered barriers are composed of a concrete vault, buffer and backfill materials. Zhishin clay and Black Hill bentonite were used as raw clay material in making buffer and backfill materials in this study. These clays were compacted to make buffer material, or mixed with Taitung area argillite to produce backfill material for potential application as barriers for the disposal of low- and intermediate-level radioactive wastes. The interaction between concrete barrier and the buffer/backfill material is simulated by an accelerated migration test to investigate the effect of contacting concrete on the expected functions of buffer/backfill material. The results show buffer material close to the contact with concrete exhibits significant change in the ratio of calcium/sodium exchange capacity, due to the move of calcium ions released from the concrete. The shorter the distance from the contacting interface, the ratio of the calcium/sodium concentration in buffer/backfill materials increases. The longer the distance from the interface, the effect of the contact on alteration in clays become less significant. Also, some decreases in swelling capacity in the buffer/backfill material near the concrete-backfill interface are noted. Finally, a comparison is made between Zhisin clay and Balck Hill bentonite on the interaction between concrete and the two clays. Black Hill bentonite was found to be influenced more by the interaction, because of the higher content of montmorillonite. On the other hand, being a mixture of clay and sand, backfill material is less affected by the decalsification of concrete at the contact than buffer material.

  5. Loviisa Power Station - final disposal of reactor waste

    International Nuclear Information System (INIS)

    Vaajasaari, Marja

    1987-01-01

    This report is based on the earlier published results of research into the properties and function of the candidate backfill materials. The results of the backfill material research, and the sealing concepts presented in the literature have been evaluatedand applied to sealing the Loviisa Reactor Waste Repository taking into consideration the local rock and groundwater conditions. It is emphasised that the applicability of the presented backfill materials and plugs to repository sealing must still be carefully evaluated on the basis of detailed studies and the local environment. 24 refs

  6. Source term measurements on vitrified HLW

    International Nuclear Information System (INIS)

    Hough, A.; Marples, J.A.C.

    1988-01-01

    The equilibrium concentrations of Tc-99, Np-237, Pu-239/240 and Am-241 have been measured in the presence of materials likely to be present in a vitrified HLW repository: glass, iron, backfill and rock. Results were measured under both oxidising and reducing conditions and at pH values set by the backfill bentonite and cement. Under reducing conditions and with cementitious backfills, the equilibrium concentrations ranged from three to 30 times allowed drinking water levels for the four isotopes. (author)

  7. Sea materials experimental plans

    International Nuclear Information System (INIS)

    1987-07-01

    This Seal Materials Performance Test Plan describes the plan for testing materials that will be used to seal a high-level nuclear waste repository in salt at a proposed site in Deaf Smith County, Texas. The need for sealing and backfilling the repository and the use of various sealing materials are described. The seal materials include mined salt backfills, cementitious bulkheads and plugs, and earthen backfills. The laboratory testing program for characterizing the behavior and performance of these materials is described. This report includes plans for screening materials, evaluating candidate materials to be tested, and testing a representative set of materials

  8. Emissivity Engineered Infrared Materials, 3-Dimensionally Patterned by Two Photon Lithography

    National Research Council Canada - National Science Library

    Dunn, Bruce

    2001-01-01

    .... Metal back-filling of copper into porous membranes was accomplished using electrodeposition methods and complementary fundamental studies were able to establish some of the details of this metallization process...

  9. Combined analytical model for preformance assessment of the waste package/geologic medium systems

    International Nuclear Information System (INIS)

    Ray, A.K.; Nair, S.; Nuttall, H.E.

    1982-01-01

    For sparsely soluble isotopes leaching rates are probably controlled by solubility limits. For a situation like this backfill provides a significant resistance to escape of nuclides from the repository. Isotope 129 I shows significant concentration level at a 10 km downstream distance. For this isotope the backfill thickness of 0.25 m used in the test case is not sufficient to reduce the concentration to an insignificant level. Materials for backfill and thickness of the backfill probably have to be chosen from the consideration of nuclides like 129 I. The three dimensional transport model used here provides a relatively more accurate estiamtes of concentration levels and discharge rates than the one dimensional model

  10. 77 FR 40079 - Notice of Availability of the Final Environmental Impact Statement for the Hycroft Mine Expansion...

    Science.gov (United States)

    2012-07-06

    ...,895 acres, which includes 2,172 acres of new surface disturbance. The existing open pit operation and...; expand four existing open pits; backfill all or portions of three open pits; build a dispatch center and...

  11. Clay modified crushed salt for shaft sealing elements. Material optimization and evaluation in field tests

    Energy Technology Data Exchange (ETDEWEB)

    Glaubach, Uwe; Hofmann, Martin; Gruner, Matthias; Kudla, Wolfram [TU Bergakademie Freiberg (Germany). Inst. of Mining and Special Civil Engineering

    2015-07-01

    Salt-based materials are intended to use for backfill and sealing systems in geotechnical barriers in underground HLW-repositories. Due to the creep of the saliniferous host rock, the salt backfill will be compacted during several hundreds or thousands years of operation to a minimum of porosity resp. permeability. To raise the sealing potential of a salt-based backfill, the porosity after construction should be minimized by optimal material performance and compaction performance. A procedure to optimize the grain size distribution of crushed salt and its water and clay content is described. The optimized salt fraction gets a better compaction behavior than straight mine-run salt. The addition of a filler-like material (e.g. Friedland Clay Powder) reduces the total porosity and permeability. Backfill columns made from crushed salt and clay probably include an instant sealing function.

  12. 10 CFR 60.142 - Design testing.

    Science.gov (United States)

    2010-01-01

    ... construction, a program for in situ testing of such features as borehole and shaft seals, backfill, and the... effectiveness of borehole and shaft seals before full-scale operation proceeds to seal boreholes and shafts. ...

  13. Decontamination and decommissioning of the Organic Moderated Reactor Experiment facility (OMRE)

    International Nuclear Information System (INIS)

    Hine, R.E.

    1980-09-01

    This report describes the decontamination and decommissioning (D and D) of the Organic Moderated Reactor Experiment (OMRE) facility performed from October 1977 through September 1979. This D and D project included removal of all the facilities and as much contaminated soil and rock as practical. Removal of the reactor pressure vessel was an unusually difficult problem, and an extraordinary, unexpected amount of activated rock and soil was removed. After removal of all significantly contaminated material, the site consisted of a 20-ft deep excavation surrounded by backfill material. Before this excavation was backfilled, it and the backfill material were radiologically surveyed and detailed records made of these surveys. After the excavation was backfilled and graded, the site surface was surveyed again and found to be essentially uncontaminated

  14. Pervious Pavement System Evaluation

    Science.gov (United States)

    Porous pavement is a low impact development stormwater control. The Urban Watershed Management Branch is evaluating interlocking concrete pavers as a popular implementation. The pavers themselves are impermeable, but the spaces between the pavers are backfilled with washed, grade...

  15. Pervious Pavement System Evaluation- Abstract 1

    Science.gov (United States)

    Porous pavement is a low impact development stormwater control. The Urban Watershed Management Branch is evaluating interlocking concrete pavers as a popular implementation. The pavers themselves are impermeable, but the spaces between the pavers are backfilled with washed, gra...

  16. Pervious Pavement System Evaluation- Abstract

    Science.gov (United States)

    Porous pavement is a low impact development stormwater control. The Urban Watershed Management Branch is evaluating interlocking concrete pavers as a popular implementation. The pavers themselves are impermeable, but the spaces between the pavers are backfilled with washed, gra...

  17. Screening of mine dirt as addition to concrete. Description of testing plant. Results

    Energy Technology Data Exchange (ETDEWEB)

    Gnodtke, M

    1977-08-01

    An experimental facility for screening mine dirt during haulage operations is described. The screening material, adding sand and a binder, can be made into a concrete aggregate at low costs and used as backfilling material.

  18. Evaluation of low-pH cement degradation in tunnel plugs and bottom plate systems in the frame of SR-Site

    Energy Technology Data Exchange (ETDEWEB)

    Grandia, Fidel; Galindez, Juan-Manuel; Molinero, Jorge; Arcos, David (Amphos XXI Consulting S.L., Barcelona (Spain))

    2010-09-15

    Low-pH concrete plugs are going to be used during the backfilling of depositional tunnels of the high-level nuclear waste repository. The stability of these plugs, however, is thought to be affected by water-concrete interaction that may lead to cement degradation and dissolution. Alkaline plumes derived from such a degradation could jeopardize the chemical stability of the clay material in the backfill due to the enhanced dissolution kinetics under high-pH solutions. In this study, the cement durability of concrete plugs to be used in the repository is numerically evaluated by performing reactive transport simulations based on the geochemical degradation of the cement compounds, mainly calcium silicate hydrates (CSH). The implementation of degradation process into the geochemical model is based on a solid solution approach for CSH alteration. The numerical model also takes into account the dependency of transport properties (e.g. molecular diffusion coefficient) with the changes in porosity due to mineral precipitation-dissolution. The simulations predict that the effect of low-pH concrete alteration on the stability of backfill materials would be low. The main process governing geochemistry in the backfill-concrete boundary would be the quick loss of porosity due to ettringite precipitation. The very high molar volume of this mineral enhances the rate of clogging. The ettringite formation is mainly driven by the high sulphate concentration in the backfill porewater, which in turn is controlled by the equilibrium with gypsum in the backfill. The release and diffusion of calcium (from CSH replacement) and Al (from katoite dissolution) from concrete causes ettringite precipitation at the concrete-backfill boundary. The loss of porosity dramatically reduces solute diffusion and, consequently, the backfill-concrete system remains almost invariably for hundreds of years

  19. Evaluation of low-pH cement degradation in tunnel plugs and bottom plate systems in the frame of SR-Site

    International Nuclear Information System (INIS)

    Grandia, Fidel; Galindez, Juan-Manuel; Molinero, Jorge; Arcos, David

    2010-09-01

    Low-pH concrete plugs are going to be used during the backfilling of depositional tunnels of the high-level nuclear waste repository. The stability of these plugs, however, is thought to be affected by water-concrete interaction that may lead to cement degradation and dissolution. Alkaline plumes derived from such a degradation could jeopardize the chemical stability of the clay material in the backfill due to the enhanced dissolution kinetics under high-pH solutions. In this study, the cement durability of concrete plugs to be used in the repository is numerically evaluated by performing reactive transport simulations based on the geochemical degradation of the cement compounds, mainly calcium silicate hydrates (CSH). The implementation of degradation process into the geochemical model is based on a solid solution approach for CSH alteration. The numerical model also takes into account the dependency of transport properties (e.g. molecular diffusion coefficient) with the changes in porosity due to mineral precipitation-dissolution. The simulations predict that the effect of low-pH concrete alteration on the stability of backfill materials would be low. The main process governing geochemistry in the backfill-concrete boundary would be the quick loss of porosity due to ettringite precipitation. The very high molar volume of this mineral enhances the rate of clogging. The ettringite formation is mainly driven by the high sulphate concentration in the backfill porewater, which in turn is controlled by the equilibrium with gypsum in the backfill. The release and diffusion of calcium (from CSH replacement) and Al (from katoite dissolution) from concrete causes ettringite precipitation at the concrete-backfill boundary. The loss of porosity dramatically reduces solute diffusion and, consequently, the backfill-concrete system remains almost invariably for hundreds of years

  20. Information base for waste repository design. Volume 5. Decommissioning of underground facilities. Technical report

    International Nuclear Information System (INIS)

    Giuffre, M.S.; Plum, R.L.; Koplik, C.M.; Talbot, R.

    1979-03-01

    This report is Volume 5 of a seven volume document on nuclear waste repository design issues. This report discusses the requirements for decommissioning a deep underground facility for the disposal of radioactive waste. The techniques for sealing the mined excavations are presented and an information base on potential backfill materials is provided. Possible requirements for monitoring the site are discussed. The performance requirements for backfill materials are outlined. The advantages and disadvantages of each sealing method are stated

  1. Design of a deposit of waste materials coming from mining exploitations

    International Nuclear Information System (INIS)

    Castro, Alvaro; Pinzon, Hernan; Vargas, William; Pinzon, Andres

    2005-01-01

    This paper presents the design process and stability assessment of a waste backfill in a limestone quarry method. The study shows the geotechnical and mining features of waste and underground materials affected by backfill. The mainly waste materials are: clay, gravel, and blocks of clay stone, sandstone and limestone, all to be disposed by a layered embankment. The constructive method is selected and the stability analysis of deposit and soil foundation was made by equilibrium method without considering deformations

  2. Deliverable 3.1_ITER Project_Guidelines on best practice to be adopted in situ for TEBM use

    OpenAIRE

    Di Sipio, Eloisa; Berteermann, David

    2017-01-01

    The present guidelines concern the best practice to be adopted in situ for the installation of a special form of ground source collector, the helix system, and the use of Thermally Enhanced Backfilling Material (TEBM) as backfilling material in very shallow geothermal application. These best practice are based on the experience acquired on the ITER test site, located in Eltersdorf (Germany), and benefit from skill, expertise and multy-year experience of the two industrial partners of ITER ...

  3. Mechanics of granular-frictional-visco-plastic fluids in civil and mining engineering

    Science.gov (United States)

    Alehossein, H.; Qin, Z.

    2013-10-01

    The shear stress generated in mine backfill slurries and fresh concrete contains both velocity gradient dependent and frictional terms, categorised as frictional viscous plastic fluids. This paper discusses application of the developed analytical solution for flow rate as a function of pressure and pressure gradient in discs, pipes and cones for such frictional Bingham-Herschel-Bulkley fluids. This paper discusses application of this continuum fluid model to industrial materials like mine and mineral slurries, backfills and fresh concrete tests.

  4. Long-term rheological and transport properties of dry and wet salt rocks

    International Nuclear Information System (INIS)

    Spiers, C.J.; Peach, C.J.; Brzesowsky, R.H.; Schutjens, P.M.T.M.; Liezenberg, J.L.; Zwart, H.J.

    1988-01-01

    This report forms a final report on Aims 1 to 3 of Contract No FI1W-0051-NL. It is opened in Section 2 with a consideration of the theoretical background necessary for a state-of-the-art treatment of compaction creep in granular salt and backfill materials (Aim 3). Fundamental experimental work on compaction creep in wet and dry salt aggregates is presented in Sections 3 and 4 respectively. In Section 5 this is extended to investigate the influence of backfill variables (such as brine content, grain-size distribution, and additives content) on the compaction creep behaviour of granular salt, and to develop a generally applicable constitutive law for salt backfill and cement materials. In Section 6 an optimal (i.e. fast-compaction/retention-efficient) backfill recipe is proposed. Experiments designed to test/verify the applicability of our general constitutive law to this recipe, to determine its permeability versus porosity characteristics, and to clarify the very long term properties and microstructure of both backfill and cement, are also reported. The conclusions drawn complete our work on backfill. Section 7 deals with work done on the long-term constitutive behaviour of salt rock (Aim 1) and on creep-induced dilatancy (Aim 2). Investigations into the permeability characteristics of dilated salt and (fractured) anhydrite rock are reported in Section 8. The report is terminated in Section 9 with an overall summary of results and conclusions

  5. Behavior of crushed salt under heat source in boreholes in a salt mine (Amelie Mine, Alsace Potash Mines, France)

    International Nuclear Information System (INIS)

    Ghoreychi, M.

    1991-01-01

    The study of thermomechanical interaction between rock salt and crushed salt, used as a backfilling material at the final stage of radioactive waste disposal in salt formations, led to perform an in situ test at the Amelie Mine(The Alsace Potash Mines in France). The field tests site is located at a depth of 520m and the tests were performed in six parallel boreholes. Five boreholes were backfilled using three types of crushed salt, changing by their grain size (fine = 0.4 mm; natural = 1 mm; coarse = 2 mm). The sixth borehole was not backfilled in order to witness for rock salt behavior without backfilling confinement. Except the first borehole used as a pilot test, the four backfilled boreholes were heated during four months with two levels of heat output (1.6 kW, then 2.2 kW). Cooling was also followed during four months after heating interruption. The maximum of temperature obtained on the wall of the backfilled boreholes was about 100 0 C during the first field test and 130 0 C during the second. The thermal diffusivity of rock mass and the coefficient of heat exchange by convection are studied. In spite of the case that the crushed salt thermal conductivity is initially ten times less than of rock salt, no excessive temperature concentration was obtained on the heat sources

  6. Tests for evaluation of pellets as foundation bed material KBP1003 - ASKAR

    International Nuclear Information System (INIS)

    Johnsson, Anna

    2011-12-01

    The reference design for the backfill of deposition tunnels, described in SKB (2010), include bentonite blocks, bentonite pellets and a foundation bed of bentonite pellets or granulate. The tunnel floor needs to be flat and have sufficient bearing capacity to make it possible to stack the backfill blocks according to the reference design. To achieve a flat foundation the tunnel floor will be covered with a bed of pellets or granulate made of bentonite clay. The bed can be either compacted or non compacted. Bed tests have been performed as a part of the project KBP1003 DP1 Design, which is a subproject of KBP1003 ASKAR. The main objectives for KBP1003 DP1 is to define all requirements for the backfill and its production and installation prior to start of the large scale tests, based on given perquisites. KBP1003 is based on the reference design for the backfill of deposition tunnels which was developed in 2010 (SKB 2010). The concept for installation and block design has been further developed during the project. A new dimension of the backfill blocks has been developed; the chosen dimension makes it possible to gain overlapping joints between the blocks by block stacking. The further developed concept is hereinafter referred to as the ASKAR-concept. The purpose of the performed bed tests was to define the bed requirements in the backfill installation to enable stable stacking of backfill blocks. The tests included stacking of blocks on different bed materials, on blasted and wire sawn floor, with and without concurrent water inflow. The bed tests was subdivided into four main parts: - block stacking on different bed compositions - block stacking on bed during water inflow - block stacking in a realistic test tunnel - block stacking on the upper part of the deposition hole and bevel

  7. Tests for evaluation of pellets as foundation bed material KBP1003 - ASKAR

    Energy Technology Data Exchange (ETDEWEB)

    Johnsson, Anna (ES-Konsult AB (Sweden))

    2011-12-15

    The reference design for the backfill of deposition tunnels, described in SKB (2010), include bentonite blocks, bentonite pellets and a foundation bed of bentonite pellets or granulate. The tunnel floor needs to be flat and have sufficient bearing capacity to make it possible to stack the backfill blocks according to the reference design. To achieve a flat foundation the tunnel floor will be covered with a bed of pellets or granulate made of bentonite clay. The bed can be either compacted or non compacted. Bed tests have been performed as a part of the project KBP1003 DP1 Design, which is a subproject of KBP1003 ASKAR. The main objectives for KBP1003 DP1 is to define all requirements for the backfill and its production and installation prior to start of the large scale tests, based on given perquisites. KBP1003 is based on the reference design for the backfill of deposition tunnels which was developed in 2010 (SKB 2010). The concept for installation and block design has been further developed during the project. A new dimension of the backfill blocks has been developed; the chosen dimension makes it possible to gain overlapping joints between the blocks by block stacking. The further developed concept is hereinafter referred to as the ASKAR-concept. The purpose of the performed bed tests was to define the bed requirements in the backfill installation to enable stable stacking of backfill blocks. The tests included stacking of blocks on different bed materials, on blasted and wire sawn floor, with and without concurrent water inflow. The bed tests was subdivided into four main parts: - block stacking on different bed compositions - block stacking on bed during water inflow - block stacking in a realistic test tunnel - block stacking on the upper part of the deposition hole and bevel

  8. Preliminary conceptual designs for advanced packages for the geologic disposal of spent fuel

    Energy Technology Data Exchange (ETDEWEB)

    Westerman, R.E.

    1979-04-01

    The present study assumes that the spent fuel will be disposed of in mined repositories in continental geologic formations, and that the post-emplacement control of the radioactive species will be accomplished independently by both the natural barrier, i.e., the geosphere, and the engineered barrier system, i.e., the package components consisting of the stabilizer, the canister, and the overpack; and the barrier components external to the package consisting of the hole sleeve and the backfill medium. The present document provides an overview of the nature of the spent fuel waste; the general approach to waste containment, using the defense-in-depth philosophy; material options, both metallic and nonmetallic, for the components of the engineered barrier system; a set of strawman criteria to guide the development of package/engineered barrier systems; and four preliminary concepts representing differing approaches to the solution of the containment problem. These concepts use: a corrosion-resistant meta canister in a special backfill (2 barriers); a mild steel canister in a corrosion-resistant metallic or nonmetallic hole sleeve, surrounded by a special backfill (2 barriers); a corrosion-resistant canister and a corrosion-resistant overpack (or hole sleeve) in a special backfill (3 barriers); and a mild steel canister in a massive corrosion-resistant bore sleeve surrounded by a polymer layer and a special backfill (3 barriers). The lack of definitive performance requirements makes it impossible to evaluate these concepts on a functional basis at the present time.

  9. Seismic passive earth resistance using modified pseudo-dynamic method

    Science.gov (United States)

    Pain, Anindya; Choudhury, Deepankar; Bhattacharyya, S. K.

    2017-04-01

    In earthquake prone areas, understanding of the seismic passive earth resistance is very important for the design of different geotechnical earth retaining structures. In this study, the limit equilibrium method is used for estimation of critical seismic passive earth resistance for an inclined wall supporting horizontal cohesionless backfill. A composite failure surface is considered in the present analysis. Seismic forces are computed assuming the backfill soil as a viscoelastic material overlying a rigid stratum and the rigid stratum is subjected to a harmonic shaking. The present method satisfies the boundary conditions. The amplification of acceleration depends on the properties of the backfill soil and on the characteristics of the input motion. The acceleration distribution along the depth of the backfill is found to be nonlinear in nature. The present study shows that the horizontal and vertical acceleration distribution in the backfill soil is not always in-phase for the critical value of the seismic passive earth pressure coefficient. The effect of different parameters on the seismic passive earth pressure is studied in detail. A comparison of the present method with other theories is also presented, which shows the merits of the present study.

  10. CFD Analysis on the Passive Heat Removal by Helium and Air in the Canister of Spent Fuel Dry Storage System

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Do Young; Jeong, Ui Ju; Kim, Sung Joong [Hanyang University, Seoul (Korea, Republic of)

    2016-05-15

    In the current commercial design, the canister of the dry storage system is mainly backfilled with helium gas. Helium gas shows very conductive behavior due to high thermal conductivity and small density change with temperature. However, other gases such as air, argon, or nitrogen are expected to show effective convective behavior. Thus these are also considered as candidates for the backfill gas to provide effective coolability. In this study, to compare the dominant cooling mechanism and effectiveness of cooling between helium gas and air, a computational fluid dynamics (CFD) analysis for the canister of spent fuel dry storage system with backfill gas of helium and air is carried out. In this study, CFD simulations for the helium and air backfilled gas for dry storage system canister were carried out using ANSYS FLUENT code. For the comparison work, two backfilled fluids were modeled with same initial and boundary conditions. The observed major difference can be summarized as follows. - The simulation results showed the difference in dominant heat removal mechanism. Conduction for helium, and convection for air considering Reynolds number distribution. - The temperature gradient inside the fuel assembly showed that in case of air, more effective heat mixing occurred compared to helium.

  11. Thermo-mechanical analysis for determining the optimum design of a deposition hole using FLAC3D

    International Nuclear Information System (INIS)

    Kwon, Sang Ki; Park, Jeong Hwa; Choi, Jong Won; Kang, Chul Hyung

    2002-01-01

    In this study, the vertical location of canister in a deposition hole was determined from the thermo-mechanical coupling analysis using the three-dimensional finite difference code, FLAC3D. A FISH program was made and used for the modeling for different conditions. The following conclusions could be drawn from the study. (1) The canister moves downward initially, but moves upward with time due to the thermal expansion of buffer. (2) The tunnel floor above the deposition hole remains elastic until 100 years after the emplacement of the canister if the top buffer thickness is more than 1.5 m. (3) It was found that the peak temperature decreases with the increase of the buffer and backfill thickness, when backfilling is done immediately after the emplacement. (4) Without swelling pressure, the maximum tensile stress is up to 18 MPa at 100 days after the emplacement. Since the swelling pressure from the buffer confines the thermal expansion of the canister, the mechanical stability of canister is improved with the swelling pressure. (5) When the air temperature in the tunnels is maintained at 27 .deg. C by ventilation, the peak temperature with delayed backfilling for 50 years is about 75 .deg. while it is over 90 .deg. with immediately backfilling. (6) The buffer and backfill thickness above the canister in a deposition hole should be at least 2 m based on literature review and the computer simulations

  12. Drafting of the closure of the Asse salt mine. Final report

    International Nuclear Information System (INIS)

    Schneefuss, J.U.

    2001-01-01

    The report of the R and D-project 'Drafting of the closure of the Asse salt mine' contains the results of the first phases 'Basic findings' and 'Predrafting'. These phases were started after the backfilling of the south flank of the Asse salt mine was permitted in accordance to 2.2 of the operating program 'Future work at the Asse salt mine'. The knowledge status of May 2000 is reported. The result obtained in this program provides the basis for future drafting the closure of the Asse salt mine. The final results will include the long-term safety assessment to obtain the permission of the mining authorities for the closure of the Asse salt mine. The evaluation of the basic data has shown that further investigations are necessary. During the predrafting period the method for backfilling of the cavities, transport of the backfill and backfill and closure of the shafts were developed. Other parts of the concept for the closure are not finalized (control of the brine inflow when starting backfilling above the 658-m-level, minimizing of the possible effects of dissolution of carnallitite, avoiding of squeezing brines from deeper cavities through the disposal chambers etc.). (orig.) [de

  13. Real-time gamma imaging of technetium transport through natural and engineered porous materials for radioactive waste disposal.

    Science.gov (United States)

    Corkhill, Claire L; Bridge, Jonathan W; Chen, Xiaohui C; Hillel, Phil; Thornton, Steve F; Romero-Gonzalez, Maria E; Banwart, Steven A; Hyatt, Neil C

    2013-12-03

    We present a novel methodology for determining the transport of technetium-99m, a γ-emitting metastable isomer of (99)Tc, through quartz sand and porous media relevant to the disposal of nuclear waste in a geological disposal facility (GDF). Quartz sand is utilized as a model medium, and the applicability of the methodology to determine radionuclide transport in engineered backfill cement is explored using the UK GDF candidate backfill cement, Nirex Reference Vault Backfill (NRVB), in a model system. Two-dimensional distributions in (99m)Tc activity were collected at millimeter-resolution using decay-corrected gamma camera images. Pulse-inputs of ~20 MBq (99m)Tc were introduced into short (disposal of nuclear waste and potentially to a wide variety of other subsurface environments.

  14. Depth optimization for the Korean HLW repository System within a discontinuous and saturated granitic rock mass

    International Nuclear Information System (INIS)

    Kim, Jhin Wung; Bae, Dae Seok; Choi, Jong Won

    2005-12-01

    The present study is to evaluate the material properties of the compacted bentonite, backfill material, canister cast iron insert, and the rock mass for the Korean HLW repository system. These material properties are either measured, or taken from other countries, through the evaluation of the thermal, hydraulic, and mechanical interaction behavior of a repository. After the evaluation of the material properties, the most appropriate and economical depth as well as the layout of a single layer repository is to be recommended. Material properties used for the granitic rock mass, rock joints, PWR spent fuel, disposal canister, compacted bentonite, backfill material, and ground water are the data collected domestically, and foreign data are used for some of the data not available domestically. The repository model includes a saturated granitic rock mass with joints, PWR spent fuel in a disposal canister surrounded by compacted bentonite inside a deposition hole, and backfill material in the rest of the space within a repository cavern

  15. Vacuum technologies developed for at-400A Type B transportation and storage package

    International Nuclear Information System (INIS)

    Franklin, K.W.; Cockrell, G.D.

    1995-01-01

    The AT-400A TYPE B transportation and storage container will be used at Pantex Plant for the transportation and interim storage of plutonium pits. The AT-400A was designed by a joint effort between Sandia National Labs, Los Alamos National Labs, Lawrence Livermore National Laboratory, and Mason and Hanger-Silas Mason Co., Inc. In order to meet the requirements for transportation and storage, five different vacuum technologies had to be developed. The goals of the various vacuum technologies were to verify the plutonium pit was sealed, perform the assembly verification leak check in accordance with ANSI N-14.5 and to provide a final inert gas backfill in the containment vessel. This paper will discuss the following five vacuum technologies: (1) Pit Leak Testing, (2) Containment Vessel Purge and Backfill with tracer gas, (3) Containment Vessel Leak Testing, (4) Containment Vessel Purge and Final Backfill, and (5) Leak Testing of the Containment Vessel Gas Transfer tube

  16. The equilibrium leach testing of ferric/aluminium hydroxide flocs

    International Nuclear Information System (INIS)

    Biddle, P.; Greenfield, B.F.; Greenham, P.S.; Rees, J.H.

    1987-09-01

    Equilibrium leach tests have been carried out on ferric/aluminium hydroxide flocs using cement and resin matrices, and cement and clay backfills in both air and nitrogen atmospheres. The equilibrium concentrations of a number of actinides and fission products were measured in leachates obtained over periods of up to a year. The lowest equilibrium actinide concentrations were found in leachates from systems with a cement backfill. Cement matrix-cement backfill was the most promising combination for limiting concentrations of long-lived radionuclides, resin-clay the least. Comparison of leachate concentrations with limiting drinking water concentrations are made and the high degree of protection afforded by candidate near field components shown. (author)

  17. The equilibrium leach testing of ferric/aluminium hydroxide flocs

    International Nuclear Information System (INIS)

    Biddle, P.; Greenfield, B.F.; Greenham, P.S.; Rees, J.H.

    1987-09-01

    Equilibrium leach tests have been carried out on ferric/aluminium hydroxide flocs using cement and resin matrices, and cement and clay backfills in both air and nitrogen atmospheres. The equilibrium concentrations of a number of actinides and fission products were measured in leachates obtained over periods of up to a year. The lowest equilibrium actinide concentrations were found in leachates from systems with a cement backfill. Cement matrix-cement backfill was the most promising combination for limiting concentrations of long-lived radionuclides, resin-clay the least. Comparisons of leachate concentrations with limiting drinking water concentrations are made and the high degree of protection afforded by candidate near field components shown. (author)

  18. The sorption behavior of Cs+ ion on commercially available natural Vermiculite

    International Nuclear Information System (INIS)

    Patra, Kankan; Deokar, U.V.; Khot, A.R.; Mathew, P.; Ganesh, G.; Tripathi, R.M.

    2018-01-01

    Progress of the nuclear energy programme depends upon the effective management of nuclear waste generated during the different stages of nuclear fuel cycle. The radioactive wastes require suitable and safe management from beginning of their generation until the storage in repository. The backfill layer is considered one of the most important components of the engineering barrier of the repository. It is important to know the properties of the materials that can be used as backfill layer. Vermiculite was selected for the research as it is one of the promising candidates for the natural barrier. The objective of this research was to characterize vermiculite clays in order to evaluate the viability of their use in the backfill layer, one of the radioactive waste repository barriers. Efforts were made to evaluate the distribution of Cesium ions and there thermodynamics parameter in natural vermiculite in Tarapur plant site

  19. MCO gas composition for low reactive surface areas

    International Nuclear Information System (INIS)

    Packer, M.J.

    1998-01-01

    This calculation adjusts modeled output (HNF-SD-SNF-TI-040, Rev. 2) by considering lower reactive fuel surface areas and by increasing the input helium backfill overpressure from 0.5 to 1.5 atm (2.5 atm abs) to verify that MCO gas-phase oxygen concentrations can remain below 4 mole % over a 40 year interim period under a worst case condition of zero reactive surface area. Added backfill gas will dilute any gases generated during interim storage and is a strategy within the current design capability. The zero reactive surface area represents a hypothetical worst case example where there is no fuel scrap and/or damaged spent fuel rods in an MCO. Also included is a hypothetical case where only K East fuel exists in an MCO with an added backfill overpressure of 0.5 atm (1.5 atm abs)

  20. Swedish mines. Underground exploitation methods

    International Nuclear Information System (INIS)

    Paucard, A.

    1960-01-01

    Between 1949 and 1957, 10 engineers of the Mining research and exploitation department of the CEA visited 17 Swedish mines during 5 field trips. This paper presents a compilation of the information gathered during these field trips concerning the different underground mining techniques used in Swedish iron mines: mining with backfilling (Central Sweden and Boliden mines); mining without backfilling (mines of the polar circle area). The following techniques are described successively: pillar drawing and backfilled slices (Ammeberg, Falun, Garpenberg, Boliden group), sub-level pillar drawing (Grangesberg, Bloettberget, Haeksberg), empty room and sub-level pillar drawing (Bodas, Haksberg, Stripa, Bastkarn), storage chamber pillar drawing (Bodas, Haeksberg, Bastkarn), and pillar drawing by block caving (ldkerberget). Reprint of a paper published in Revue de l'Industrie Minerale, vol. 41, no. 12, 1959 [fr

  1. Study on seismic stability of seawall in man-made island. Pt. 1. Shaking table tests on dynamic behavior of seawall constructed on the bedrock

    International Nuclear Information System (INIS)

    Tochigi, Hitoshi; Kanatani, Mamoru; Kawai, Tadashi

    1999-01-01

    In the development of siting technology for off-shore nuclear power plants on man-made island, assessing the stability of seawall which ensures the safety of backfill ground against ocean waves and earthquakes is indispensable. In assessing seismic stability of seawall, evaluation of dynamic nonlinear behavior like sliding and settlement is an important factor. For this purpose, shake-table tests of seawall model have been carried out. By the experiments in the case of well compacted backfill ground, it is indicated that dynamic failure of caisson type seawall constructed on the strong seabed ground is mainly induced by the sliding of caisson toward the sea and followed by the settlement of backfill ground. And as the influence of armour embankment on the seismic stability of seawall, we experimentally showed that the sliding displacement of caisson during earthquake is reduced by the lateral pressure of armour units and armour embankment works effectively to rise up earthquake resistance capability of seawall. (author)

  2. The ESDRED project: Engineering studies and demonstration of repository designs

    International Nuclear Information System (INIS)

    Verstricht, J.

    2009-01-01

    The construction, operation and closure of a deep geological repository for spent fuel and long-lived radioactive waste in clay involves specific technologies. The demonstration of these techniques at an industrial scale is being carried out in the frame of a technological integrated project within the sixth Framework Programme of EURATOM. The Belgian design for high level waste disposal is based on the so-called Supercontainer concept. Within this concept, the waste is encased in a carbon steel overpack, which is consequently fitted into a 70 cm thick concrete shell, in its turn enveloped by a stainless steel liner. A Supercontainer measures about 2 m in diameter. In the design of the repository, the Supercontainers will be emplaced, one after the other, in disposal galleries. The space between the Supercontainers and the gallery lining needs to be filled up with a solid material. The most essential function of this component, referred to as backfill, is to prevent a collapse of the gallery. A secondary function is to limit the presence of free oxygen, to limit corrosion. In the ESDRED project EIG EURIDICE, together with SCK-CEN and ONDRAF/NIRAS, investigates technologies to apply the backfill. After testing two techniques to apply the backfill in 2007 at limited scale (unite with granular material and grouting with backfill mortar), grouting was selected as the preferred technique. This technique then should be tested at full-scale (30 m long mock-up). First, a full-scale structure needs to built, including an extensive instrumentation programme. In addition, the logistical needs to ensure a continuous backfill operation have to be worked out. The objective is to have the almost 100 m 3 backfilled in 4 hours

  3. The effect of geosphere conditions on the lifetimes of copper containers

    International Nuclear Information System (INIS)

    King, F.; Kolar, M.

    1997-12-01

    The effects of variations in geosphere conditions and of the properties of the backfill material on the performance of the engineered barriers have been examined using a numerical Cu container failure model. The thickness of the exclusion zone between the vault and the nearest major water-bearing fracture has been varied between 1 and 50 m. The groundwater [O 2 ] has been varied between limits of 1 and 7360 ng·g -1 , the latter value being equivalent to the hypothetical situation of aerated saline groundwater at the ambient rock temperature of 17 degrees C. The properties of the excavation-disturbed zone (EDZ) have been varied to simulate both blast-induced and stress-induced damage. Finally, the effect of the particle size of crushed granite, of reduced heat output from the container and the effect of substituting pyrite for biotite on the performance of the backfill material has been determined. The impact of these variables on the corrosion rate, the extent of the four O 2 -consumption reactions and the fate of FE(II) dissolved from the biotite (or pyrite) in the backfill and EDZ has been examined. The results of the various simulations suggest that the engineered barriers (the container and the buffer and backfill materials) can isolate the fuel almost indefinitely, regardless of the geosphere conditions. Copper containers are predicted not to fail by corrosion within the analysis period of ∼10 5 a. The robustness of the engineered barriers is a result of (i) the low rates of mass transport in saturated buffer and backfill materials and (ii) the presence of an excess of redox-buffering FE(II) minerals in the backfill. (author)

  4. Laboratory corrosion tests on candidate high-level waste container materials: Results from the Belgian programme

    International Nuclear Information System (INIS)

    Druyts, F.; Kursten, B.; Iseghem, P. Van

    2004-01-01

    The Belgian SAFIR-2 concept foresees the geological disposal of conditioned high-level radioactive waste in stainless steel containers and overpacks placed in a concrete gallery backfilled with Boom clay or a bentonite-type backfill. In addition to earlier in situ experiments, we used a laboratory approach to investigate the corrosion properties of selected stainless steels in Boom clay and bentonite environments. In the SAFIR-2 concept, AISI 316L hMo is the main candidate overpack material. As an alternative, we also investigated the higher alloyed stainless steel UHB 904L. Our study focused on localised corrosion and in particular pitting. We used cyclic potentiodynamic polarisation measurements to determine the pit nucleation potential E NP and the protection potential E PP . The evolution of the corrosion potential with time was determined by monitoring the open circuit potential in synthetic clay-water over extended periods. In this paper we present and discuss some results from our laboratory programme, focusing on long-term interactions between the stainless steel overpack and the backfill materials. We describe in particular the influence of chloride and thio-sulphate ions on the pitting corrosion behaviour. The results show that, under geochemical conditions typical for geological disposal, i.e. [Cl-] ∼ 30 mg/L for a Boom clay backfill and [Cl-] ∼ 90 mg/L for a bentonite backfill, neither AISI 316L hMo nor UHB 904L is expected to present pitting problems. An important factor in the long-term prediction of the corrosion behaviour however, is the robustness of the model for the evolution of the geochemistry of the backfill. Indeed, at chloride levels higher than 1000 mg/L, we predict pitting corrosion for AISI 316L hMo. (authors)

  5. Results from simulated contact-handled transuranic waste experiments at the Waste Isolation Pilot Plant

    International Nuclear Information System (INIS)

    Molecke, M.A.; Sorensen, N.R.; Krumhansl, J.L.

    1993-01-01

    We conducted in situ experiments with nonradioactive, contact-handled transuranic (CH TRU) waste drums at the Waste Isolation Pilot Plant (WIPP) facility for about four years. We performed these tests in two rooms in rock salt, at WIPP, with drums surrounded by crushed salt or 70 wt % salt/30 wt % bentonite clay backfills, or partially submerged in a NaCl brine pool. Air and brine temperatures were maintained at ∼40C. These full-scale (210-L drum) experiments provided in situ data on: backfill material moisture-sorption and physical properties in the presence of brine; waste container corrosion adequacy; and, migration of chemical tracers (nonradioactive actinide and fission product simulants) in the near-field vicinity, all as a function of time. Individual drums, backfill, and brine samples were removed periodically for laboratory evaluations. Waste container testing in the presence of brine and brine-moistened backfill materials served as a severe overtest of long-term conditions that could be anticipated in an actual salt waste repository. We also obtained relevant operational-test emplacement and retrieval experience. All test results are intended to support both the acceptance of actual TRU wastes at the WIPP and performance assessment data needs. We provide an overview and technical data summary focusing on the WIPP CH TRU envirorunental overtests involving 174 waste drums in the presence of backfill materials and the brine pool, with posttest laboratory materials analyses of backfill sorbed-moisture content, CH TRU drum corrosion, tracer migration, and associated test observations

  6. Analysis of the forced vibration test of the Hualien large scale soil-structure interaction model using a flexible volume substructuring method

    International Nuclear Information System (INIS)

    Tang, H.T.; Nakamura, N.

    1995-01-01

    A 1/4-scale cylindrical reactor containment model was constructed in Hualien, Taiwan for foil-structure interaction (SSI) effect evaluation and SSI analysis procedure verification. Forced vibration tests were executed before backfill (FVT-1) and after backfill (FVT-2) to characterize soil-structure system characteristics under low excitations. A number of organizations participated in the pre-test blind prediction and post-test correlation analyses of the forced vibration test using various industry familiar methods. In the current study, correlation analyses were performed using a three-dimensional flexible volume substructuring method. The results are reported and soil property sensitivities are evaluated in the paper. (J.P.N.)

  7. Study on the basic property of Gaomiaozi bentonite, inner mongolia

    International Nuclear Information System (INIS)

    Liu Yuemiao; Xu Guoqing; Liu Shufen; Chen Zhangru

    2001-01-01

    Buffer/backfill material layer is one of important engineered barriers in the HLW geological repository. The geologic setting of Gaomiaozi bentonite deposit is introduced, and the mineral composition, physical and chemical property, basic geotechnical property, swelling property and permeability of highly compacted bentonite of main ore bed has been studied. The study results show that montmorillonite content of Gaomiaozi bentonite is relatively high, physical and chemical property, geotechnical property and impermeability are good. So Gaomiaozi bentonite deposit could be regarded as supply base of buffer/backfill material for HLW geological repository

  8. Direct methods of soil-structure interaction analysis for earthquake loadings(II)

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Chung Bang; Lee, S R; Kim, J M; Park, K L; Oh, S B; Choi, J S; Kim, Y S [Korea Advanced Institute of Science Technology, Daejeon (Korea, Republic of)

    1994-07-15

    In this study, methods for 3-D soil-structure interaction analysis have been studied. They are 3-D axisymmetric analysis method, 3-D axisymmetric finite element method incorporating infinite elements, and 3-D boundary element methods. The computer code, named as 'KIESSI - PF', has been developed which is based on the 3-D axisymmetric finite element method coupled with infinite element method. It is able to simulate forced vibration test results of a soil-structure interaction system. The Hualien FVT post-correlation analysis before backfill and the blind prediction analysis after backfill have been carried out using the developed computer code 'KIESSI - PF'.

  9. A disposal centre for irradiated nuclear fuel: conceptual design study

    International Nuclear Information System (INIS)

    1980-09-01

    This report describes a conceptual design of a disposal centre for irradiated nuclear fuel. The surface facilities consist of plants for the preparation of steel cylinders containing irradiated nuclear fuel immobilized in lead, shaft headframe buildings, and all necessary support facilities. The undergound disposal vault is located on one level at a depth of 1000 metres. The cylinders containing the irradiated fuel are emplaced on a one-metre thick layer of backfill material and then completely covered with backfill. All surface and subsurface facilities are described, operations and schedules are summarized, and cost estimates and manpower requirements are given. (auth)

  10. Impact assessment of shallow land burial for low-level waste: modelling of the water flow and transport of radionuclides in the near-field

    Energy Technology Data Exchange (ETDEWEB)

    Walravens, J; Volckaert, G

    1996-09-18

    The Belgian concept for disposal of low-level waste consists of storage of waste drums into a concrete vault backfilled with a cementitious grout. The vault is placed above the water table and will be covered with a multilayer cap of clay, gravel, and sandy materials. The SCK/CEN is charged with the long-term performance assessment of the disposal site. The main processes and parameters determining the radioactivity release from the site are identified. The principal processes are the infiltration through the top cover and the sorption of waste on the backfill. The release of radionuclides from the site was modelled with the PORFLOW numerical code.

  11. Feasibility and economic consequences of retrievable storage of radioactive waste in the deep underground

    International Nuclear Information System (INIS)

    Prij, J.; Heijdra, J.J.

    1995-01-01

    The economic consequences of retrievable storage have been investigated by comparing two extreme options of retrievable storage. In one option the storage facility is kept in operation using minimal backfill of the storage galleries. In the other option the storage facility is completely backfilled, sealed and abandoned. In the second option construction of a new mine will be necessary in case of retrieval. The point in time has been determined when the second option will be cheaper than the first. This has been done for clay, granite and rock salt as host formation, and both for vitrified waste and spent fuel. (authors)

  12. Direct methods of soil-structure interaction analysis for earthquake loadings

    International Nuclear Information System (INIS)

    Yun, J. B.; Kim, J. M.; Kim, Y. S. and others

    1993-07-01

    The objectives of this study are to review the methods of soil- structure interaction system analysis, particularly the direct method, and to carry out the blind prediction analysis of the Forced Vibration Test(FVT) before backfill in the course of Hualien LSST project. The scope and contents of this study are as follows : theoretical review on soil-structure interaction analysis methods, free-field response analysis methods, modelling methods of unbounded exterior region, hualien LSST FVT blind prediction analysis before backfill. The analysis results are found to be very well compared with the field test results

  13. Direct methods of soil-structure interaction analysis for earthquake loadings(II)

    International Nuclear Information System (INIS)

    Yun, Chung Bang; Lee, S. R.; Kim, J. M.; Park, K. L.; Oh, S. B.; Choi, J. S.; Kim, Y. S.

    1994-07-01

    In this study, methods for 3-D soil-structure interaction analysis have been studied. They are 3-D axisymmetric analysis method, 3-D axisymmetric finite element method incorporating infinite elements, and 3-D boundary element methods. The computer code, named as 'KIESSI - PF', has been developed which is based on the 3-D axisymmetric finite element method coupled with infinite element method. It is able to simulate forced vibration test results of a soil-structure interaction system. The Hualien FVT post-correlation analysis before backfill and the blind prediction analysis after backfill have been carried out using the developed computer code 'KIESSI - PF'

  14. Development of rock segment for reduction of amount of cement use

    International Nuclear Information System (INIS)

    Tada, Hiroyuki; Kumasaka, Hiroo; Saito, Akira; Nakaya, Atsushi; Ishii, Takashi; Sanada, Masanori; Noguchi, Akira; Kishi, Hirokazu; Nakama, Shigeo; Fujita, Tomoo

    2013-01-01

    The authors have been developing methods for constructing tunnels using the minimum quantities of cement-type support materials in high-level radioactive waste disposal facilities and advancing research and development about the technical formation of rock segment using low alkali mortar. In this study, the mechanical characteristic values concerning the rock segment and backfill materials were examined. The stability analysis of drift supported by the rock segment and backfilling with gravel were performed. Technical formation and effectiveness of the support planned for further reduction in cement influence was confirmed from the study result. (author)

  15. Considerations for creating a free-standing monolith

    International Nuclear Information System (INIS)

    Salsman, J.M.

    1985-01-01

    The Texas Low-Level Radioactive Waste Disposal Authority is investigating alternatives to shallow-land burial for low-level radioactive waste. This alternative proposes a standard shallow-land burial trench with a reinforced concrete floor over a sand bottom, backfilling the trench voids with concrete instead of sand and using a concrete cap covered with clay and top soil. The use of concrete backfilled trenches in a geologically stable, semi-arid area can provide an additional degree of safety, but their use in a geologically unfavorable area could actually create problems. Three reasons for using concrete backfill are: better intruder barriers, creation of a concrete monolith, and lower susceptibility to subsidence. A fourth nontechnical reason is that the public seems to be infatuated with concrete, which may prove to be the best reason for a concrete backfilled trench. The additional cost of using concrete is approximately $7.78/ft 3 of waste buried if the concrete is commercially purchased; however, if a batch plant is utilized, the cost is reduced to $1.43/ft 3

  16. Recycling of wastes from uranium mining and metallurgy and recovery of useful resources in China

    International Nuclear Information System (INIS)

    Pan Yingjie; Xue Jianxin; Chen Zhongqiu

    2012-01-01

    Recycling of wastes from uranium mining and metallurgy in China and recovery of useful resources are summarized from the aspects such as recovery of uranium from mine water, reusing of waste water, decontaminating and recycling of radioactivity contaminated metal, backfill of gangues and tailings, and comprehensive recovery and utilization of associated uranium deposits. (authors)

  17. Uranium mill tailings regulation and the generic environmental impact statement

    International Nuclear Information System (INIS)

    Rogers, V.C.

    1980-01-01

    The following topics are discussed: the history of the Canadian uranium industry; the Canadian management of uranium mining wastes; Canadian federal and provincial effluent guidelines for radium-226; tailings and mine water management; backfill; liquid effluents from tailings storage; barium chloride treatment; mine water (Fay Mine); mine water (Dubyna Mine); and revegetation. 22 refs

  18. 10 CFR 61.13 - Technical analyses.

    Science.gov (United States)

    2010-01-01

    ... air, soil, groundwater, surface water, plant uptake, and exhumation by burrowing animals. The analyses... processes such as erosion, mass wasting, slope failure, settlement of wastes and backfill, infiltration through covers over disposal areas and adjacent soils, and surface drainage of the disposal site. The...

  19. Author Details

    African Journals Online (AJOL)

    Okyere, PY. Vol 28, No 2 (2008) - Articles Performance of Automotive SLI Battery under Constant Current Constant Voltage Charge Algorithm in Solar PV Application Abstract PDF · Vol 29, No 2 (2009) - Articles Evaluation Of Four Local Materials As Backfill To Achieve A Low Earth Electrode Resistance Abstract PDF · Vol 30 ...

  20. The aeration period of a model nuclear waste repository

    International Nuclear Information System (INIS)

    Sharland, S.M.; Tasker, P.W.

    1987-02-01

    We have constructed a model of the evolution of oxygen in a cement backfill which includes both its depletion through the canister corrosion reactions and its migration in the cement pores. The results indicate that the duration in which mild steel waste canisters may be subject to localised corrosion is very much shorter than the intended lifetime of the repository components, provided there is no external source of oxygen. For canisters spaced 1.2m apart, the model predicts a maximum aeration period of approximately 65 years, assuming high oxygen content and diffusivity in the backfill and low leakage current on the canisters (0.01 μA cm -2 ). In such a case a reducing environment is established throughout the backfill within this period. Under conditions of more restricted oxygen transport, reducing conditions are still established within a relatively short time in the immediate vicinity of the canisters, but the oxidation potential elsewhere in the backfill is then controlled by the uniform corrosion rate of the canisters. (author)

  1. Analysis and Prevention of Geo-Environmental Hazards with High-Intensive Coal Mining: A Case Study in China’s Western Eco-Environment Frangible Area

    Directory of Open Access Journals (Sweden)

    Qiang Sun

    2017-06-01

    Full Text Available This study seeks to address the problems of major geo-environmental hazards caused by high-intensive coal mining in China’s western eco-environment frangible area including strong mining pressure, surface subsidence, soil and water loss, and land desertification. Using the high-intensive mining at the Xiao-jihan Coal Mine, this paper investigates the compaction characteristics of aeolian sand-based backfilling materials, and then the evolution of water-conducting fractures and surface deformation laws with different backfill material’s compression ratios (BMCRs by using physical simulation and numerical simulation analysis methods. This study presents the technical system of water-preserved and environmental protection with rapid-backfilling methods in China’s western eco-environment frangible area. The backfill coal mining technique and application prospects are assessed and discussed. The results will be helpful for coordinated development of coal resources exploitation and environmental protection in China’s western eco-environment frangible area.

  2. From mine to meadow

    Energy Technology Data Exchange (ETDEWEB)

    Gualdron, R; Camacho, R [Intercor, Barranquilla (Colombia). Environmental Engineering Division

    1993-10-01

    This article describes the rehabilitation of dumps and backfill areas at the world's largest export coal mine, El Cerrejon Zone Norte, in Northern Colombia. The rehabilitation process includes the preparation of surfaces and slopes, the placement of topsoil and the revegetation and reforestation of the prepared areas. 8 photos.

  3. Tracking Trends: Students' Information Use in the Social Sciences and Humanities, 1995-2008

    Science.gov (United States)

    Smyth, Joanne B.

    2011-01-01

    This study uses citation analysis to examine students' dissertations and theses in history, psychology, and education, noting changes in research practices since the introduction of electronic journals and other online sources. Some findings challenge earlier studies, showing that students are making greater use of journal backfiles and that this…

  4. THERMALLY CONDUCTIVE CEMENTITIOUS GROUTS FOR GEOTHERMAL HEAT PUMPS. PROGRESS REPORT BY 1998

    Energy Technology Data Exchange (ETDEWEB)

    ALLAN,M.L.; PHILIPPACOPOULOS,A.J.

    1998-11-01

    Research commenced in FY 97 to determine the suitability of superplasticized cement-sand grouts for backfilling vertical boreholes used with geothermal heat pump (GHP) systems. The overall objectives were to develop, evaluate and demonstrate cementitious grouts that could reduce the required bore length and improve the performance of GHPs. This report summarizes the accomplishments in FY 98.

  5. 76 FR 72901 - Notice of Petitions by Firms for Determination of Eligibility To Apply for Trade Adjustment...

    Science.gov (United States)

    2011-11-28

    .... attachments for excavators and backfill equipment and other attachments and parts for heavy equipment. Modular... furniture in wood, metal, stone and upholstery. Verne Q. Powell Flutes, Inc........ 1 Clock Tower Place, 24-Oct-11 The firm manufactures Suite 300, Maynard, intermediate and MA 01754. student musical...

  6. 40 CFR 278.1 - Definitions.

    Science.gov (United States)

    2010-07-01

    ... laws and with consideration of site-specific risk assessments. (g) Flowable fill—a cementitious slurry... primarily as a backfill in lieu of compacted earth. (h) Granular road base—road base typically constructed... layer by rolling over it with heavy compaction equipment. The aggregate base layers serve a variety of...

  7. Physical and numerical modelling of earth pressure on anchored sheet pile walls in sand

    DEFF Research Database (Denmark)

    Krogsbøll, Anette Susanne; Fuglsang, Leif D

    2006-01-01

    The influence of wall flexibility on earth pressure, bending moments and failure modes is studied. Numerical models are compared to results from model tests carried out in a geotechnical centrifuge. The back-fill is dry sand and failure is introduced by allowing the wall to rotate around the anchor...

  8. Experimental simulations of interactions between glass and environmental materials, from laboratory benches to in-site testing

    International Nuclear Information System (INIS)

    Godon, N.

    1997-01-01

    This paper summarizes the results of 26 long-duration tests simulating a variety of storage conditions. The effects of the back-filling materials, glass cracking and the nature of the host rock are discussed. Moreover, two experiments have been in progress for over 15 and 7 years in a granite medium and a clay medium. (author)

  9. 10 CFR 50.10 - License required; limited work authorization.

    Science.gov (United States)

    2010-01-01

    ... retaining walls within an excavation, installation of foundations, or in-place assembly, erection..., subsurface preparation, placement of backfill, concrete, or permanent retaining walls within an excavation... plant emergency operating procedures; (iii) SSCs whose failure could prevent safety-related SSCs from...

  10. 10 CFR 63.133 - Design testing.

    Science.gov (United States)

    2010-01-01

    ... design, such as, for example, borehole and shaft seals, backfill, and drip shields, as well as the... placement is begun. (d) Tests must be conducted to evaluate the effectiveness of borehole, shaft, and ramp seals before full-scale operation proceeds to seal boreholes, shafts, and ramps. ...

  11. Concept for Underground Disposal of Nuclear Waste

    Science.gov (United States)

    Bowyer, J. M.

    1987-01-01

    Packaged waste placed in empty oil-shale mines. Concept for disposal of nuclear waste economically synergistic with earlier proposal concerning backfilling of oil-shale mines. New disposal concept superior to earlier schemes for disposal in hard-rock and salt mines because less uncertainty about ability of oil-shale mine to contain waste safely for millenium.

  12. Enhancement of the glass corrosion in the presence of clay minerals: testing experimental results with an integrated glass dissolution model

    International Nuclear Information System (INIS)

    Godon, N.; Vernaz, E.Y.

    1992-01-01

    Recent glass dissolution experiments, conducted at 90 deg C in the presence of potential backfill materials, indicate remarkably faster glass corrosion in the presence of clay, compared to tests where the glass is leached either alone or with alternative backfill materials. This effect correlates with the clay content in the backfill, and may be attributed to the removal of silica from solution. Scorpion, or dissolution with reprecipitation of a silica-rich clay, have been proposed as possible mechanisms for the silica consumption. The results of some experiments have been tested against a glass dissolution model, in which a widely used kinetic equation for glass corrosion is coupled with diffusive silica transport through a single porosity, linearly sorbing medium, which represents the backfilling. Because the glass corrosion rates imposed by the kinetic equation are inversely proportional to the silicic acid concentration of the leachant contacting the glass, the model predicts enhanced glass dissolution if silica is sorbed by the porous medium. The experimental data proved to be consistent with the predicted enhancement of the glass dissolution. Moreover, the model-estimated distribution coefficients for silica sorption (K d ) fall within the range of values extracted from available literature data, thus supporting the hypothesis that the observed high corrosion rates are due to sorption of silica on the clay mineral surfaces. (author)

  13. 78 FR 42977 - Petitions for Modification of Application of Existing Mandatory Safety Standards

    Science.gov (United States)

    2013-07-18

    ... provide for rock burst potential. (4) Mining higher and/or wider increases cycle times, increases exposure... rock conditions. To ensure a safe work environment, the company has employed a combination of good mining practices, rock bolting fixtures, surface support, backfill, and timber in its ground support plan...

  14. Joining of beryllium by braze welding technique: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Banaim, P.; Abramov, E. [Ben-Gurion Univ. of the Negev, Beersheba (Israel); Zalkind, S.; Eden, S.

    1998-01-01

    Within the framework of some applications, there is a need to join beryllium parts to each other. Gas Tungsten Arc Braze Welds were made in beryllium using 0.3 mm commercially Aluminum (1100) shim preplaced at the joint. The welds exhibited a tendency to form microcracks in the Fusion Zone and Heat Affected Zone. All the microcracks were backfilled with Aluminum. (author)

  15. Slurry walls and slurry trenches - construction quality control

    International Nuclear Information System (INIS)

    Poletto, R.J.; Good, D.R.

    1997-01-01

    Slurry (panel) walls and slurry trenches have become conventional methods for construction of deep underground structures, interceptor trenches and hydraulic (cutoff) barriers. More recently polymers mixed with water are used to stabilize the excavation instead of bentonite slurry. Slurry walls are typically excavated in short panel segments, 2 to 7 m (7 to 23 ft) long, and backfilled with structural materials; whereas slurry trenches are fairly continuous excavations with concurrent backfilling of blended soils, or cement-bentonite mixtures. Slurry trench techniques have also been used to construct interceptor trenches. Currently no national standards exist for the design and/or construction of slurry walls/trenches. Government agencies, private consultants, contractors and trade groups have published specifications for construction of slurry walls/trenches. These specifications vary in complexity and quality of standards. Some place excessive emphasis on the preparation and control of bentonite or polymer slurry used for excavation, with insufficient emphasis placed on quality control of bottom cleaning, tremie concrete, backfill placement or requirements for the finished product. This has led to numerous quality problems, particularly with regard to identification of key depths, bottom sediments and proper backfill placement. This paper will discuss the inspection of slurry wall/trench construction process, identifying those areas which require special scrutiny. New approaches to inspection of slurry stabilized excavations are discussed

  16. Plutonium Immobilization Can Loading Preliminary Specifications

    Energy Technology Data Exchange (ETDEWEB)

    Kriikku, E.

    1998-11-25

    This report discusses the Plutonium Immobilization can loading preliminary equipment specifications and includes a process block diagram, process description, equipment list, preliminary equipment specifications, plan and elevation sketches, and some commercial catalogs. This report identifies loading pucks into cans and backfilling cans with helium as the top priority can loading development areas.

  17. Conference summaries

    International Nuclear Information System (INIS)

    1986-01-01

    This volume contains conference summaries of the international conference on radioactive waste management of the Canadian Nuclear Society. Topics of discussion include: storage and disposal; hydrogeology and geochemistry; transportation; buffers and backfill; public attitudes; tailings; site investigations and geomechanics; concrete; economics; licensing; matrix materials and container design; durability of fuel; biosphere modelling; radioactive waste processing; and, future options

  18. Three-dimensional thermal analysis of a high-level waste repository

    International Nuclear Information System (INIS)

    Altenbach, T.J.

    1979-04-01

    The analysis used the TRUMP computer code to evaluate the thermal fields for six repository scenarios that studied the effects of room ventilation, room backfill, and repository thermal diffusivity. The results for selected nodes are presented as plots showing the effect of temperature as a function of time. 15 figures, 6 tables

  19. 75 FR 34666 - Stream Protection Rule; Environmental Impact Statement

    Science.gov (United States)

    2010-06-18

    ... rule means that we will need to prepare a new environmental impact statement rather than the supplement.... Establishing corrective action thresholds. Land Forming and Fill Optimization. Revising the backfilling and... Original Contour Exceptions. Limiting variances and exceptions from approximate original contour...

  20. Bentonite Permeability at Elevated Temperature

    Directory of Open Access Journals (Sweden)

    Katherine A. Daniels

    2017-01-01

    Full Text Available Repository designs frequently favour geological disposal of radioactive waste with a backfill material occupying void space around the waste. The backfill material must tolerate the high temperatures produced by decaying radioactive waste to prevent its failure or degradation, leading to increased hydraulic conductivity and reduced sealing performance. The results of four experiments investigating the effect of temperature on the permeability of a bentonite backfill are presented. Bentonite is a clay commonly proposed as the backfill in repository designs because of its high swelling capacity and very low permeability. The experiments were conducted in two sets of purpose-built, temperature controlled apparatus, designed to simulate isotropic pressure and constant volume conditions within the testing range of 4–6 MPa average effective stress. The response of bentonite during thermal loading at temperatures up to 200 °C was investigated, extending the previously considered temperature range. The results provide details of bentonite’s intrinsic permeability, total stress, swelling pressure and porewater pressure during thermal cycles. We find that bentonite’s hydraulic properties are sensitive to thermal loading and the type of imposed boundary condition. However, the permeability change is not large and can mostly be accounted for by water viscosity changes. Thus, under 150 °C, temperature has a minimal impact on bentonite’s hydraulic permeability.

  1. A review of recent advances in numerical modelling of local scour problems

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu

    2014-01-01

    A review is presented of recent advances in numerical modelling of local scour problems. The review is organized in five sections: Highlights of numerical modelling of local scour; Influence of turbulence on scour; Backfilling of scour holes; Scour around complex structures; and Scour protection ...

  2. Method to Predict Long Time Span of Scour Around Offshore Wind Turbine Foundations

    DEFF Research Database (Denmark)

    Dixen, Martin; Lohmann, Iris P.; Christensen, Erik Damgaard

    2012-01-01

    tables have been made based on full 3D numerical simulations of the flow and sediment transport for fixed configurations of the scour hole. When changing the governing parameters which are causing the scour development around the structure, the erosion rate or backfilling rate can be calculated from...

  3. Implementation and testing of an improved methodology to simulate resaturation processes with DarcyTools

    International Nuclear Information System (INIS)

    Enssle, Carl Philipp; Poppei, Joachim

    2010-12-01

    In the work reported here, an elaborated approach is presented that incorporates a transient saturation dependent moisture capacity into the definition of the specific storage and hence includes the capillarity. Doing so, the saturation dependent capillarity of the backfilling, which may strongly affect the evolution of the resaturation process, is taken into account

  4. 30 CFR 716.2 - Steep-slope mining.

    Science.gov (United States)

    2010-07-01

    ... burial does not cause, or add to, instability of the backfill. Woody materials may be chipped and... planning agencies, if any, constitutes an equal or better economic or public use. (iii) The permittee has... standards established to assure the stability, drainage, and configuration necessary for the intended use of...

  5. Innovative Extraction Method for a Coal Seam with a Thick Rock-Parting for Supporting Coal Mine Sustainability

    Directory of Open Access Journals (Sweden)

    Meng Li

    2017-10-01

    Full Text Available As thick rock partings delay the efficient mining of coal seams and constrain the sustainable development of coal mines, an innovative extraction method for a coal seam with thick rock parting was proposed. The coal seams were divided into different sub-zones according to the thickness of rock parting and then the sub-zones were mined by separately using three mining schemes involving full-seam mining, combined mining using backfill and caving (CMBC, and reducing height mining. Afterwards, the study introduced the basic mechanism and key devices for the CMBC and analysed the working state of the backfill support in detail. Moreover, the method for calculating the length of the backfill zone was proposed to design the length of backfill zone and the influences of four factors (including bulking coefficient of rock parting on the length of the backfill zone were also explored. By taking the No. 22203 panel, Buertai mine, Inner Mongolia, China as an example, the mined coal resource by using the CMBC extraction method will increase by 1.83 × 106 tons and the recovery ratio will rise from 56.2% to 92.4% compared with mining of the 2-2 upper coal seam alone. Moreover, by applying CMBC, a series of environmental and ecological problems caused by rock parting is reduced, which can improve the environment in mined areas. The research can provide technological guidance for mining panels of a coal seam with a thick rock parting and the disposal thereof under similar conditions.

  6. The improvement of the technology and equipment for the utilization of solid industrial wastes by means of adding them to the cast of hardening filling mixtures

    Directory of Open Access Journals (Sweden)

    E. P. Volkov

    2017-12-01

    Full Text Available The article provides an assessment of mining operations in underground mines which apply backfill systems, as well as the volume of enrichment waste accumulated during the exploitation of ore deposits. The use of high-quality cement and expensive inert fillers by many mining companies significantly increases the cost of backfill, while the technologies for increasing the activity of the binder are only partially used. The adoption of low-quality binders (cement and milled granulated slags, the investigation of new economically advantageous technologies for producing filling mixtures, as well as the use of binders and fillers, which can be used as tails of enrichment waste, will promote the spreading of backfill systems. In the practice of mining, it is an urgent task, which should be solved. This solution will significantly expand the raw material base of many mining enterprises; it will also increase their efficiency and address environmental protection issues. The conditions and regularities of increasing the reaction properties of many dump products, changing their rheological properties in time, as well as ways to create, and maintain the activity of the filling mixture during its preparation and pipeline transportation, remain insufficiently studied. We also consider the concept of improving the systems of pipeline transportation of cast hardening of filling mixtures to ensure reliable and uninterrupted delivery of the obtained backfilling mixtures with the reduced water content. It is associated with the use of the special hydrodynamic actuators mounted on a backfilling pipeline. As the activating devices the original patented designs of activators providing high efficiency of restoration of rheological properties of stowage mixes at their transportation on the underground stowage pipeline are offered and described. Based on the theoretical justification of the proposed design solutions, we can conclude that the proposed trigger device

  7. A study of the operational logistics in the disposal plant for spent nuclear fuel

    International Nuclear Information System (INIS)

    Sylvaenne, O.; Kaskinen, T.; Kuussaari, P.

    2003-02-01

    The final disposal plant for spent nuclear fuel comprises an encapsulation facility that will be built on the surface, other support activities above ground, and a repository that will be constructed deep in the bedrock. This report analyses the final repository operational logistics. The desktop research report is compiled of data taken from several existing planning reports covering the planning periods 1997-2002. The logistics specialised description of the final repository considers most areas in the daily operation of the facility. Among these are: Disposal tunnel excavation; construction and transports; Tunnel preparation for canisters; Reception of spent nuclear fuel transport casks; Encapsulation process; Preparation of bentonite blocks for canister holes, block laying; Final disposal of canisters; and Preparation of backfilling material and backfilling. The transport and handling volumes have certain cycles. Rock will be excavated during one contiguous period in 3 years, backfilling takes two weeks in a month and the deposition of canisters also two weeks. Thus the material flows vary greatly due to their cyclical nature. The transport and handling volumes are considerable, by far largest single item being excavated rock with about 5000 annual truck loads during the active excavation period, backfilling is about 1300 loads yearly at a steady pace. The report covers and summarises material flows, handling methods and equipment, buffering, storage and transports. It suggests some changes to operational procedures. Proposals have been made as to the location of the encapsulation facility and the methods of material transport. The logistical 'hot' issues, entry of the main transport ramp, rock field, rock crushing process, bentonite storage, bentonite brick production and backfiller production are all proposed to be located close to each other to minimise driving distance. It has also been proposed that the bentonite block buffer should rather be located at

  8. The Effects of High Salinity Groundwater on the Performance of Clay Barriers

    International Nuclear Information System (INIS)

    Savage, David

    2005-08-01

    Potential changes in groundwater chemistry during the operational or post-closure periods of the Swedish repository for spent fuel could affect the performance of both the bentonite buffer and repository backfill. For example, the up-coning of saline groundwater could lead to decreased swelling pressures in both the bentonite buffer and tunnel backfills, and could also induce 'piping'. SKB is considering these issues as part of its 'SR-Can' safety assessment. This report reviews evidence for the behaviour of swelling clays in groundwaters of varying salinity with special relevance to the SKB programme. Smectite clays can absorb water into clay inter-layers with the most important parameters being: the surface density of charge of the clay; the charge and solvation behaviour of the inter-layer ions; and the electrolyte concentration or activity of water. Two categories of swelling are generally observed: innercrystalline swelling caused by the hydration of the exchangeable cations in the dry clay; and osmotic swelling, resulting from concentration gradients in ion concentrations between clay surfaces and pore water. Several models exist to interpret and predict the swelling behaviour of clays. SKB currently prefer an interpretation of clay swelling pressure where clay particles are viewed as 'macro-ions' and the entire clay-water system can be considered as a 'polyelectrolyte'. SKB use the term 'Donnan exclusion' to estimate the amount of introduced ions into the clay and hence the amount of reduced swelling pressure due to contact with a saline solution. Donnan exclusion is the process whereby the migration of anions through the narrow aqueous film surrounding clay platelets is restricted due to the repulsion by the negative charge of the clay platelets. SKB's experimental work shows that: There is an exponential relation between swelling pressure and mean basal interlamellar spacing of the clay. Ions from the external electrolyte solution enter the clay volume

  9. The Effects of High Salinity Groundwater on the Performance of Clay Barriers

    Energy Technology Data Exchange (ETDEWEB)

    Savage, David [Quintessa Ltd., Nottingham (United Kingdom)

    2005-07-01

    Potential changes in groundwater chemistry during the operational or post-closure periods of the Swedish repository for spent fuel could affect the performance of both the bentonite buffer and repository backfill. For example, the up-coning of saline groundwater could lead to decreased swelling pressures in both the bentonite buffer and tunnel backfills, and could also induce 'piping'. SKB is considering these issues as part of its 'SR-Can' safety assessment. This report reviews evidence for the behaviour of swelling clays in groundwaters of varying salinity with special relevance to the SKB programme. Smectite clays can absorb water into clay inter-layers with the most important parameters being: the surface density of charge of the clay; the charge and solvation behaviour of the inter-layer ions; and the electrolyte concentration or activity of water. Two categories of swelling are generally observed: innercrystalline swelling caused by the hydration of the exchangeable cations in the dry clay; and osmotic swelling, resulting from concentration gradients in ion concentrations between clay surfaces and pore water. Several models exist to interpret and predict the swelling behaviour of clays. SKB currently prefer an interpretation of clay swelling pressure where clay particles are viewed as 'macro-ions' and the entire clay-water system can be considered as a 'polyelectrolyte'. SKB use the term 'Donnan exclusion' to estimate the amount of introduced ions into the clay and hence the amount of reduced swelling pressure due to contact with a saline solution. Donnan exclusion is the process whereby the migration of anions through the narrow aqueous film surrounding clay platelets is restricted due to the repulsion by the negative charge of the clay platelets. SKB's experimental work shows that: There is an exponential relation between swelling pressure and mean basal interlamellar spacing of the clay. Ions from the

  10. Seismic pressure effect on retaining walls; Presiones generadas por sismo en muros de retencion

    Energy Technology Data Exchange (ETDEWEB)

    Bonola, Isaac; Aviles, Javier [Instituto Mexicano de Tecnologia del Agua, Jiutepec, Morelos (Mexico)

    2006-04-15

    Retaining walls are auxiliary works used in different hydraulic structures. In seismically active areas, the dynamic pressures generated by the backfill must be appropriately evaluated at the design stage. Currently, a number of methods for estimating the seismic response of this type of works are available; however, most of them are simplified and not all the parameters involved have been examined. In this paper, a hybrid boundary and finite element method is presented for gravity walls in which the backfill can be represented by a horizontally layered medium. The effect of lateral extension of the backfill can be included in the model by introducing a vertical boundary coupling the movement of the backfill with that of the surrounding soil. The wave propagation analysis in the layered medium is carried out for both horizontal and vertical harmonic excitation; the latter excitation may cause important responses under certain situations. To illustrate the applicability of the proposed method, results for two numerical examples are presented: one for dry backfill and other for saturated backfill, considering in both cases the variations of dynamic properties of the soil with the depth. [Spanish] Los muros de retencion son estructuras auxiliares utilizadas en distintas obras hidraulicas. En zonas sismicas, las presiones dinamicas generadas por el relleno deben evaluarse adecuadamente en la etapa de diseno. Actualmente existen numerosos metodos para estimar la respuesta sismica de este tipo de estructuras; sin embargo, la mayoria de ellos son simplificados y no todos los parametros involucrados han sido examinados. En este trabajo se presenta un metodo hibrido de frontera y elemento finito para muros de gravedad en el que el relleno puede representarse por un medio estratificado horizontalmente. En el modelo puede incluirse el efecto de la extension lateral del relleno, introduciendo una frontera vertical que acopla el movimiento del relleno con el del suelo

  11. Environmental safety case and cement-related issues for intermediate-level waste in a co-located geological disposal facility

    International Nuclear Information System (INIS)

    Norris, Simon; Williams, Steve

    2012-01-01

    Simon Norris of the NDA described safety case and cement-related issues for a geological disposal facility for ILW. The Environmental Safety Case (ESC) needs to demonstrate a clear understanding of: - The disposal facility in its geological setting. - How the disposal system will evolve. - How the various components of system (including cementitious materials) contribute to meeting the requirement of providing a safe long-term solution for the disposed wastes. The ESC must include and support the key environmental safety arguments with underpinning lines of reasoning and detailed analysis, assessments and supporting evidence (including those relating to cementitious materials). In an ILW disposal system, cementitious materials could be used in several ways: - As in-package grouting materials and package materials. - Backfill material. - Shotcrete and other vault lining technologies that could be employed during construction and operation. - Engineered seals. - Structural materials. Given that cementitious materials will play important roles in the disposal system - and within a general strategy for managing uncertainty - the NDA is conducting, or has recently conducted, research into the following topics: - Assessment of the potential for interactions between disposal modules for low- and intermediate-level wastes and for HLW and spent fuel. - The effect of possible cementitious vault liners (e.g. composed from shotcrete) on the early post-closure evolution of waste-derived gas in a geological disposal facility for low- and intermediate-level wastes. - The evolution of cementitious backfill materials, including cracking, and related evolution of groundwater flow and chemistry in the vault environment of a geological disposal facility. - Evidence from nature and archaeology relevant to the long-term properties of cement. - Interaction of waste-derived gas (particularly carbon-14 bearing gas) with cementitious materials in the facility near-field. - The choice of in

  12. Effect of the mineral precipitation-dissolution at tunnel walls during the operational and post-operational phases

    Energy Technology Data Exchange (ETDEWEB)

    Domenech, Cristina; Arcos, David; Duro, Lara; Grandia, Fidel [Enviros Consul ting, Valldoreix, Barcelona (Spain)

    2007-11-15

    The extent of reversibility of the geochemical conditions disturbed during the construction and operational phases is of importance in order to assess the chemical evolution of the repository system. In this regard, it is essential to have a deep understanding of the chemical status of the repository system at closure in order to describe its immediate geochemical evolution beyond this point. This project assesses the dissolution and precipitation of minerals due to the interaction with groundwater in the deposition tunnel wall-rock during the operational phase (prior to tunnel backfilling) and during the saturation phase, also considering the effect on the backfill material. We have performed a 2D model in which a fracture intersecting the main tunnel has been considered. The project has been developed in two consecutive stages. The first stage simulates the precipitation and dissolution of minerals in the tunnel wall rock during the operational phase (100 years after excavation) when the tunnel is empty and filled with air. During this stage, water flows through fractures into the tunnel. The results of the model suggest that the interaction between groundwater, fracture-filling minerals, and atmospheric O{sub 2}(g) and CO{sub 2}(g) present in the tunnel leads to the precipitation of secondary minerals (calcite and iron(III) oxy-hydroxide) that do not significantly affect the porosity of the area surrounding the tunnel. The second stage starts after the operational phase, once the tunnel is backfilled, and simulates the interaction of groundwater with fracture-filling minerals and the backfill material. The model implemented assumes that the backfill is already water saturated and that water flows following the regional head gradient. Moreover, it also assumes that O2(g) is still present in the tunnel wall, as a result of the operational phase disturbances. The results show that oxygen will oxidise pyrite in the backfill and promote the precipitation of Fe

  13. AN ANALYSIS OF THE THERMAL AND MECHANICAL BEHAVIOR OF ENGINEERED BARRIERS IN A HIGH-LEVEL RADIOACTIVE WASTE REPOSITORY

    Directory of Open Access Journals (Sweden)

    S. KWON

    2013-02-01

    Full Text Available Adequate design of engineered barriers, including canister, buffer and backfill, is important for the safe disposal of high-level radioactive waste. Three-dimensional computer simulations were carried out under different condition to examine the thermal and mechanical behavior of engineered barriers and rock mass. The research looked at five areas of importance, the effect of the swelling pressure, water content of buffer, density of compacted bentonite, emplacement type and the selection of failure criteria. The results highlighted the need to consider tensile stress in the outer shell of a canister due to thermal expansion of the canister and the swelling pressure from the buffer for a more reliable design of an underground repository system. In addition, an adequate failure criterion should be used for the buffer and backfill.

  14. PILOT-SCALE EVALUATION OF ENGINEERED BARRIER SYSTEMS FOR THE YUCCA MOUNTAIN PROJECT

    International Nuclear Information System (INIS)

    Webb, S.W.; George, J.T.; Finley, R.E.

    2001-01-01

    This paper describes two quarter-scale experiments (1.4 m diameter) and associated numerical analyses on granular backfill engineered barrier systems in support of the Yucca Mountain Project for the potential repository. The two configurations include a sloped capillary barrier and a plain backfill. The tests involve application of dyed water as a constant line infiltration source along the top of the test set-up, monitoring water movement through the test, and measuring water exiting the experiments. A complete water balance estimate is made for each test, and observed water movement is compared with (1) detailed numerical analyses conducted using the TOUGH2 code for unsaturated flow in porous media and (2) posttest observations. The results of the testing and analyses show that for the injection rates and configuration applied, the capillary barrier design diverts a significant amount of all injected water and the TOUGH2 pretest predictions show qualitative and quantitative agreement with the experimental data

  15. Conceptual design for relocation of the underground monitoring systems to ground surface

    International Nuclear Information System (INIS)

    Toya, Naruhisa; Ogawa, Ken; Iwatsuki, Teruki; Ohnuki, Kenji

    2015-09-01

    One of the major subjects of the ongoing geoscientific research program, the Mizunami Underground Research Laboratory (MIU) Project in the Tono area, central Japan, is accumulation of knowledge on a recovery of the geological environment during and after the facility closure. Then it is necessary to plan the observation system which can be use of after the backfill of research tunnels. The main purpose of this report is contribution to the detailed design for relocation of the underground monitoring systems to ground surface. We discussed the restriction and requirement for the underground monitoring systems which can be use of after the backfill. Furthermore, we made the conceptual design for relocation of the current underground monitoring systems to ground surface. (author)

  16. Regional hydrocarbon contaminated soil recycling facility standards

    International Nuclear Information System (INIS)

    Warren, R.

    1992-01-01

    In an effort to protect the environment from uncontrolled releases of petroleum products, the Canadian Petroleum Products Institute member companies have initiated environmental upgrading programs for their underground fuel storage systems in British Columbia. These programs have been restricted in recent years as a result of environmental regulations targeting contaminated soil, which is generated when underground storage tanks are upgraded to current standards. The soil requiring treatment is typically sand backfill containing a nominal value of petroleum product. These soils can be treated in an engineered basin using bioremediation technology to reduce the level of contamination. Depending on the degree of treatment, the soil can be recycled as backfill or reused as landfill cover. An overview is presented of the basin treatment process and design. Natural bioremediation is enhanced with nutrients, water and oxygen addition. 4 figs

  17. The interaction between contacting barrier materials for containment of radioactive wastes

    International Nuclear Information System (INIS)

    Chang, Hao-Chun; Wang, Chun-Yao; Huang, Wei-Hsing

    2012-01-01

    Document available in extended abstract form only. The disposal of low-level radioactive wastes requires multi-barrier facilities to contain the wastes from contamination. Typically, the engineered barrier is composed of a concrete vault backfilled with sand/bentonite mixture. The backfill material is a mixture of bentonite and sand/gravel produced from crushing the rocks excavated at the site. With a great swelling potential, bentonite is expected to serve the sealing function, while the crushed sand/gravel improves the workability of the mixture. Due to the nature of radioactive wastes, the disposal site is designed for a service life of 300 years or more, which is much longer than typical engineering or earth works. With such a long service life, the site is subject to groundwater intrusion and geochemical evolution. The near-field environment evolution can be a complex problem in a disposal site. In the vicinity of the concrete vault in a disposal site, the high-alkali concrete environment can cause changes in the pore solution and alter the nature of backfill materials. Therefore, the interaction between the concrete and the backfill material needs to be assessed, such that the barriers serve the expected functions for a long time. Materials and Methods A locally available Zhishin clay and a bentonite originated from Black Hill, Wyoming, USA were used as raw clay materials in this study. Zhishin clay and Black Hill (BH) bentonite are mixed with Taitung area hard shale to produce the backfill material. An experimental program was conducted analysing the soil properties of these 2 bentonites. And an accelerated migration test was devised to understand the loss of calcium leaching of concrete on characteristics of backfill material. The 2 barrier materials (concrete and backfill) were placed in contact and then an electric gradient applied to accelerate the move of cations between the 2 barriers. Fig. 1 shows a schematic diagram of the accelerated migration test

  18. Dynamic stiffness of pile groups in a multilayered soil. Part 1

    International Nuclear Information System (INIS)

    Ohta, Y.; Hijikata, K.; Kobayashi, Y.

    1989-01-01

    For evaluating the dynamic stiffness of the pile group foundations, forced vibration tests are executed on pile group foundation models. Two types of test models are used, one is a single pile model and the other a four-pile model. Dividing the tests into 4 steps, the forced vibration tests are performed. Step 1 is for the single pile model, and steps 2 to 4 are for the four-pile model. In step 2 and step 3, the gap effects between the foundation bottom and the ground surface are examined. In step 4, the backfill effects are obtained. Based on the test results, the pile group effects, the gap effects and the backfill effects on the dynamic characteristics of the pile group foundations are described in this paper

  19. Decontamination and decommissioning of the SPERT-I seepage pit at the Idaho National Engineering Laboratory. Final report

    International Nuclear Information System (INIS)

    Suckel, R.A.

    1984-11-01

    This report describes the decontamination and decommissioning of the SPERT-I seepage pit. Prior to its decontamination and decommissioning, the seepage pit was surrounded by an earthen dike varying from 2 to 6 ft above the pit bottom. A 6-in., cast iron, underground waste line originated at the pit tank in the reactor building and ran approximately 68 ft to the seepage pit. The soil in the seepage pit contained low-level radioactive contamination. The soil surface was removed to a depth of 2.5 ft and shipped to the Radioactive Waste Management Complex (RWMC). The waste line that contained fixed contamination was removed and also sent to the RWMC. The pit was backfilled with radiologically clean soil, reducing the surface activity to background. A permanent marker was erected over the backfilled pit to indicate that presence of residual subsurface radioactive contamination. 5 references, 26 figures, 3 tables

  20. Mobility and survival of sulphate-reducing bacteria in compacted and fully water saturated bentonite - microstructural aspects

    International Nuclear Information System (INIS)

    Pusch, R.

    1999-12-01

    Sulphate-reducing bacteria will not be able to enter MX-80 buffer clay with the intended bulk density, i.e. 1900-2100 kg/m 3 . Nor will they be able to survive and migrate in such environment. The only circumstances under which sulphate-reducing bacteria can enter, survive and migrate in engineered soil barriers in a KBS-3-type repository are those prevailing in backfills with lower MX-80 contents than about 10 % or in more smectite-rich, poorly compacted backfills saturated with electrolyte-rich pore water with Ca as dominating cation. In the phase of hydration and expansion of canister-embedding buffer, bacteria can enter the initially very soft clay gel at the rock/buffer contact to a depth of about a centimeter

  1. Waste package performance analysis

    International Nuclear Information System (INIS)

    Lester, D.H.; Stula, R.T.; Kirstein, B.E.

    1982-01-01

    A performance assessment model for multiple barrier packages containing unreprocessed spent fuel has been applied to several package designs. The resulting preliminary assessments were intended for use in making decisions about package development programs. A computer model called BARIER estimates the package life and subsequent rate of release of selected nuclides. The model accounts for temperature, pressure (and resulting stresses), bulk and localized corrosion, and nuclide retardation by the backfill after water intrusion into the waste form. The assessment model assumes a post-closure, flooded, geologic repository. Calculations indicated that, within the bounds of model assumptions, packages could last for several hundred years. Intact backfills of appropriate design may be capable of nuclide release delay times on the order of 10 7 yr for uranium, plutonium, and americium. 8 references, 6 figures, 9 tables

  2. Sorption of Pu onto some kinds of clay

    International Nuclear Information System (INIS)

    Jia Haihong; Si Gaohua; Liu Wei; Yu Jing

    2010-01-01

    There are rich clay mines holding in one area, so it's necessary to know about these clays' sorption capacity to Pu, for building radioactive waste repository in the area. Distribution coefficients of Pu onto different clays were acquired in static method, with the result about 104. The size of clay is different, but the result of Kds is near. In addition, it's estimated how far Pu moves in the most rapid speed in the clay based on these Kids', disregarding the influence of Pu-colloid. In a word, as a kind of backfilling material clays in the area can effectively prevent Pu from moving to environment, and when designing the backfilling layer, it's not necessary to catch clays through NO.200 sieve, if only considering the influence of Kd. (authors)

  3. An Evaluation of Parallel Job Scheduling for ASCI Blue-Pacific

    International Nuclear Information System (INIS)

    Franke, H.; Jann, J.; Moreira, J.; Pattnaik, P.; Jette, M.

    1999-01-01

    In this paper we analyze the behavior of a gang-scheduling strategy that we are developing for the ASCI Blue-Pacific machines. Using actual job logs for one of the ASCI machines we generate a statistical model of the current workload with hyper Erlang distributions. We then vary the parameters of those distributions to generate various workloads, representative of different operating points of the machine. Through simulation we obtain performance parameters for three different scheduling strategies: (i) first-come first-serve, (ii) gang-scheduling, and (iii) backfilling. Our results show that backfilling, can be very effective for the common operating points in the 60-70% utilization range. However, for higher utilization rates, time-sharing techniques such as gang-scheduling offer much better performance

  4. Thermal simulation of drift emplacement (TSS): In-situ instrumentation and numerical modeling of stress measurement methods

    International Nuclear Information System (INIS)

    Heusermann, S.

    1988-01-01

    In the course of the planned demonstration test Thermal Simulation of Drift Emplacement (TSS) BGR is carrying out in-situ-measurements of rock stresses, rock deformability and permeability of salt rock and backfill material. The following techniques developed and proved by BGR during the last years are planned to be used in the TSS project: overcoring technique, dilatometer technique, hard inclusion technique, slot-cutting techniques, large-flatjack technique, compensation tests in laboratory, vacuum tests, injection tests, and tracer tests. The purpose of measurements is to determine: the initial stress state; stress gradients around test drifts; stress change caused by mining activities, by creep and stress relaxation and by temperature; the in-situ load-deformation behavior of rock salt; the permeability of rock salt around test drifts; the compaction behavior of backfill material; and the load-deformation behavior of rock salt and borehole grout in laboratory tests

  5. The potential for vault-induced seismicity in nuclear fuel waste disposal: experience from Canadian mines

    International Nuclear Information System (INIS)

    Martin, C.D.; Chandler, N.A.

    1996-12-01

    A seismic event which causes damage to an underground opening is called a rockburst. Practical experience indicates that these damaging seismic events are associated with deep mines where extraction ratios are greater than 0.6. For the arrangement being considered by AECL for nuclear fuel waste disposal vaults, extraction ratios, for the room and pillar design, will be less than 0.3. At this extraction ratio the stress magnitudes will not be sufficient to induce seismic events that can damage the underground openings. Documented world-wide experience shows that unless the underground opening is very close to the source of a naturally occurring seismic event, such as an earthquake, the opening will also not experience any significant damage. Backfilling a disposal vault will improve its resistance to earthquake damage. Backfilling a disposal vault will also reduce the total convergence of the openings caused by thermal loads and hence minimize the potential for thermally-induced seismic events. (author)

  6. Nonmetallic engineered barriers, their properties and role in a geologic repository for high level radioactive waste

    International Nuclear Information System (INIS)

    Lisy, F.

    1994-01-01

    The efficiency of engineered barrier systems depends to a great extent on the properties of the materials used. Backfill and sealing materials must fulfill certain requirements and criteria. They must feature low hydraulic conductivity, high retardation capacity, extremely good sorption properties for a wide range of radionuclides potentially leachable from the deposited waste, low permeability, good compatibility with engineered and natural barriers, good workability, and availability in the necessary quantity and at a reasonable price. Some basic properties are presented of materials which fulfill, to a considerable degree, these requirements and which are thus suggested as suitable backfills, sealings of buffers, namely clay- and cement-based materials (concretes, mortars, etc.). A brief information is also given on some other materials like bitumen, asphalt, etc. (Z.S.) 4 refs

  7. Soil-Structure Interaction for Non-Slender, Large-Diameter Offshore Monopiles

    DEFF Research Database (Denmark)

    Sørensen, Søren Peder Hyldal

    conducted. The initial part of p-y curves for non-slender piles has been investigated by means of numerical modelling. The general behaviour of eccentrically loaded non-slender piles has been investigated by physical modelling. These tests have been conducted in the pressure tank at Aalborg University....... The monopile foundation concept has been employed as the foundation for the majority of the currently installed offshore wind turbines. Therefore, this PhD thesis concerns the soil-pile interaction for non-slender, large-diameter offshore piles. A combination of numerical and physical modelling has been....... Hence, the application of an overburden pressure is possible. The timescale of the backfill process and the compaction of soil material backfilled around piles in storm conditions have been investigated by means of large-scale physical modelling....

  8. Investigation of sheet steel St 37.2 under mechanical impact

    International Nuclear Information System (INIS)

    Berg, H.P.; Brennecke, P.; Koester, R.; Friehmelt, V.

    1990-01-01

    Special waste originating, e.g. from chemical industry and radioactive wastes are emplaced in disposal mines. Slinger stowing is an approved technique to fill up residual voids in emplacement rooms. If it should be applied, possible mechanical loads on the integrity of sheet steel containers have to be considered. By theoretical calculations and by experiments under variation of different parameters using test specimen and backfill material from the Konrad mine using the container type V as an example it has been shown that sheet steel St 37.2 with a wall thickness of 3 mm will withstand mechanical impact imposed by backfill particles having a speed of 24 m/s. (orig.) [de

  9. Standard test method for laboratory evaluation of magnesium sacrificial anode test specimens for underground applications

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1997-01-01

    1.1 This test method covers a laboratory procedure that measures the two fundamental performance properties of magnesium sacrificial anode test specimens operating in a saturated calcium sulfate, saturated magnesium hydroxide environment. The two fundamental properties are electrode (oxidation potential) and ampere hours (Ah) obtained per unit mass of specimen consumed. Magnesium anodes installed underground are usually surrounded by a backfill material that typically consists of 75 % gypsum (CaSO4·2H2O), 20 % bentonite clay, and 5 % sodium sulfate (Na2SO4). The calcium sulfate, magnesium hydroxide test electrolyte simulates the long term environment around an anode installed in the gypsum-bentonite-sodium sulfate backfill. 1.2 This test method is intended to be used for quality assurance by anode manufacturers or anode users. However, long term field performance properties may not be identical to property measurements obtained using this laboratory test. Note 1—Refer to Terminology G 15 for terms used ...

  10. Behavior of a nuclear power plant ventilation stack for wind loads

    International Nuclear Information System (INIS)

    Venkatachalapathy, V.

    2012-01-01

    This paper describes behavior of self supporting tall reinforced concrete (RC) ventilation stack of a nuclear power plant (NPP) for wind loads. Since the static and equivalent dynamic wind loads are inter-dependant on overall size of the stack, proper sizing of the stack geometry is important for reducing wind loads. The present study investigated the influence of engineered backfill soil on lateral response of ventilation stack. Ignoring backfill soil stiffness up to ground height does not allow to predict actual critical wind velocity causing across wind oscillation. The results show that proposed modification in the stack geometry modeled using 2D beam-spring elements is economical than that of single tapered geometry. Shaft diameter reduced in the proposed geometry indicates that there is a scope for overall space savings in the NPP layout. (author)

  11. Soil Structure Interaction for Integral Abutment Bridge Using Spring Analogy Approach

    International Nuclear Information System (INIS)

    Thanoon, W A; Abdulrazeg, A A; Jaafar, M S; Kohnehpooshi, O; Noorzaei, J

    2011-01-01

    The reaction of the backfill behind the abutments and adjacent to the piles plays a significant role in the behavior of the Integral bridge. The handling of soil-structure interaction in the analysis and design of integral abutment bridges has always been problematic due to its complexity. This study describes the implementation of a 2-D finite element model of IAB system which explicitly incorporates the soil response. The superstructure members and the pile have been represented by means of three-node isoperimetric beam elements with three degree of freedom per node. The Eight node isoperimetric quadrilateral element has been used to model the abutment. The backfill was idealized by uncoupled 'Winkler' spring. The applic1ability of this model is demonstrated by analyzing a single span IA bridge. The results have shown that the shear forces at the tops of the supported piles were only 12% to 16% of the load which at the top of abutment.

  12. Soil Structure Interaction for Integral Abutment Bridge Using Spring Analogy Approach

    Energy Technology Data Exchange (ETDEWEB)

    Thanoon, W A [Faculty Engineering, Nizwa University (Oman); Abdulrazeg, A A; Jaafar, M S; Kohnehpooshi, O [Department of Civil Engineering, University Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Noorzaei, J, E-mail: jamal@eng.upm.edu.my [Institute of Advance Technology, University Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2011-02-15

    The reaction of the backfill behind the abutments and adjacent to the piles plays a significant role in the behavior of the Integral bridge. The handling of soil-structure interaction in the analysis and design of integral abutment bridges has always been problematic due to its complexity. This study describes the implementation of a 2-D finite element model of IAB system which explicitly incorporates the soil response. The superstructure members and the pile have been represented by means of three-node isoperimetric beam elements with three degree of freedom per node. The Eight node isoperimetric quadrilateral element has been used to model the abutment. The backfill was idealized by uncoupled 'Winkler' spring. The applic1ability of this model is demonstrated by analyzing a single span IA bridge. The results have shown that the shear forces at the tops of the supported piles were only 12% to 16% of the load which at the top of abutment.

  13. Characteristics of the excavation response zone as applied to shaft sealing

    International Nuclear Information System (INIS)

    Jakubick, A.T.; Klein, R.; Gray, M.N.; Keil, L.D.

    1989-01-01

    Effective sealing of an underground repository requires high quality seals. Clay-based backfills in combination with cement plugs are the possible candidates. An important component of the shaft sealing program is the development of techniques to predict and monitor the flow in the excavation response zone (ERZ) and at the seal-rock interface. The mechanical and hydraulic performance of the seal and backfill and the flow characteristics of the ERZ under in situ conditions will be tested in three experimental shafts to be excavated in the URL. The use of the vacuum permeability technique for characterization of the hydraulic properties and of the permeability distribution in the ERZ under various geomechanical conditions is discussed

  14. Eco-trench: a novel trench solution based on reusing excavated material and a finishing layer of expansive concrete

    International Nuclear Information System (INIS)

    Blanco, A.; Pujadas, R.; Fernández, C.; Cavalaro, S.H.P.; Aguado, A.

    2017-01-01

    Installing utility pipelines generates a significant amount of trench arisings, which are usually transported to landfills instead of being reused as backfill material. This practice generates CO2 emissions and wastes raw materials. This paper presents a more sustainable solution, an eco-trench, which is based on re-using trench arisings as backfill and adding a top layer of expansive concrete to improve the eco-trench’s structural performance. The technical feasibility of the eco-trench was evaluated through a finite element model, which identified the degree of expansion in concrete required to avoid failure or subside the stresses caused by traffic. The potential expansion of concrete was measured under confined conditions in the laboratory by means of a novel test developed for this purpose. The results showed that adding calcium oxide generates the required internal stress. The results were then confirmed in a pilot experience. [es

  15. NAK WP-cave project: Thermally induced convective motion in groundwater in the near field of the WP-cave after filling and closure

    International Nuclear Information System (INIS)

    Hopkirk, R.J.

    1989-04-01

    The thermal convective motion induced in groundwater due to the decay heat generated by the high-level waste in the WP-Cave has been studied by means of coupled thermo-hydraulic numerical models. The WPC concept is proposed as an alternative to the KBS-3 repository concept for construction in crystalline rock. However, in the absence of specific site fissure data, the rock mass has been modelled as a quasi-porous medium. The repository was assumed to be filled 40 years after unloading of the spent fuel. For a further 100 years the whole repository is cooled, before being backfilled and sealed off. Maximum waste temperatures and the fluid fluxes crossing the backfilled bentonite diffusion barrier were monitored to 3000 years after fuel unloading. At the same time, the effects of the hydraulic cage and of a highly permeable rock zone beneath the central storage volume on the induced fluid flows have been assessed. (orig.)

  16. Eco-trench: a novel trench solution based on reusing excavated material and a finishing layer of expansive concrete

    Directory of Open Access Journals (Sweden)

    A. Blanco

    2017-09-01

    Full Text Available Installing utility pipelines generates a significant amount of trench arisings, which are usually transported to landfills instead of being reused as backfill material. This practice generates CO2 emissions and wastes raw materials. This paper presents a more sustainable solution, an eco-trench, which is based on re-using trench arisings as backfill and adding a top layer of expansive concrete to improve the eco-trench’s structural performance. The technical feasibility of the eco-trench was evaluated through a finite element model, which identified the degree of expansion in concrete required to avoid failure or subside the stresses caused by traffic. The potential expansion of concrete was measured under confined conditions in the laboratory by means of a novel test developed for this purpose. The results showed that adding calcium oxide generates the required internal stress. The results were then confirmed in a pilot experience.

  17. Mobility and survival of sulphate-reducing bacteria in compacted and fully water saturated bentonite - microstructural aspects

    Energy Technology Data Exchange (ETDEWEB)

    Pusch, R. [Geodevelopment AB, Lund (Sweden)

    1999-12-01

    Sulphate-reducing bacteria will not be able to enter MX-80 buffer clay with the intended bulk density, i.e. 1900-2100 kg/m{sup 3}. Nor will they be able to survive and migrate in such environment. The only circumstances under which sulphate-reducing bacteria can enter, survive and migrate in engineered soil barriers in a KBS-3-type repository are those prevailing in backfills with lower MX-80 contents than about 10 % or in more smectite-rich, poorly compacted backfills saturated with electrolyte-rich pore water with Ca as dominating cation. In the phase of hydration and expansion of canister-embedding buffer, bacteria can enter the initially very soft clay gel at the rock/buffer contact to a depth of about a centimeter.

  18. Joint DOE/NRC field study of tracer migration in the unsaturated zone

    International Nuclear Information System (INIS)

    Nyhan, J.; Polzer, W.; Essington, E.; Cokal, E.; Lane, L.; Lopez, E.; Stallings, E.; Walker, R.

    1986-03-01

    The results of a joint DOE/NRC field experiment to evaluate leaching and transport of solutes in a sandy silt backfill used for shallow land burial operations at Los Alamos are presented for steady-state and unsteady-state flow conditions. The migration of iodide, bromide, and lithium through the backfill material is studied as functions of depth and time and they are compared with one another. The bromide and iodide tracer data are used to estimate the diffusion coefficient, the tortuosity factor, and dispersivity. These values are used to calculate effective dispersion coefficients for subsequent analyses of the retardation factor and the distribution coefficient for lithium using least squares procedures. The results of the tracer migration study are discussed relative to challenges facing the waste management community, and chemical transport modeling opportunities are presented for a modeling workshop to be held in FY86

  19. Research to develop guidelines for cathodic protection of concentric neutral cables, volume 1

    Science.gov (United States)

    Hanck, J. A.; Nekoksa, G.

    1981-08-01

    Data associated with corrosion of concentric neutrals (CN) of direct buried cables from field tests conducted at 36 bellholes excavated in California, Oklahoma, and North Carolina are presented. The electrochemical, chemical, bacteriological, and sieve analyses of native soil and imported backfill samples are included. Up to 129 values were determined for each bellhole and stored on cards as a data bank. All values were statistically analyzed and correlated with corrosion found. The severity of corrosion correlated best with CN corrosion potentials, CN resistance measurements, coarseness of backfill, and soil resistivity. The guidelines for installation of cathodic protection on CN cables are to be based upon the evaluation of over 100 experimental cathodic protection systems and upon laboratory testing for protection criteria with and without ac effects.

  20. Scour properties of mono bucket foundation

    DEFF Research Database (Denmark)

    Stroescu, Ionut Emanuel; Frigaard, Peter Bak

    2016-01-01

    Field experience proved that the Mono Bucket Foundations (MBFs) have good response against scour development. Moreover, the ratio between large diameter (bucket lid) and the small diameter (shaft tower) is the driving parameter for the process of erosion/backfill, like scour protection diameter...... in the case of scour protected monopiles. However, the structural design to reduce the scour development for MBFs is still open to optimization. The influences of parameters that generate backfill and scour, the transfer load webs and the misalignment with seabed, have not been systematically studied until...... analysis compared with real surveys and existing studies showed good agreements. Scour protection based on collar solution shows high efficiency when scour protection should be required. The paper demonstrates good agreement between field measurements and small-scale studies. The unique value of the field...

  1. Controlled low strength materials (CLSM), reported by ACI Committee 229

    International Nuclear Information System (INIS)

    Rajendran, N.

    1997-01-01

    Controlled low-strength material (CLSM) is a self-compacted, cementitious material used primarily as a backfill in lieu of compacted fill. Many terms are currently used to describe this material including flowable fill, unshrinkable fill, controlled density fill, flowable mortar, flowable fly ash, fly ash slurry, plastic soil-cement, soil-cement slurry, K-Krete and other various names. This report contains information on applications, material properties, mix proportioning, construction and quality-control procedures. This report's intent is to provide basic information on CLSM technology, with emphasis on CLSM material characteristics and advantages over conventional compacted fill. Applications include backfills, structural fills, insulating and isolation fills, pavement bases, conduit bedding, erosion control, void filling, and radioactive waste management

  2. Using a multiphase flow code to model the coupled effects of repository consolidation and multiphase brine and gas flow at the Waste Isolation Pilot Plant

    International Nuclear Information System (INIS)

    Freeze, G.A.; Larson, K.W.; Davies, P.B.; Webb, S.W.

    1995-01-01

    Long-term repository assessment must consider the processes of (1) gas generation, (2) room closure and expansions due to salt creep, and (3) multiphase (brine and gas) fluid flow, as well as the complex coupling between these three processes. The mechanical creep closure code SANCHO was used to simulate the closure of a single, perfectly sealed disposal room filled with water and backfill. SANCHO uses constitutive models to describe salt creep, waste consolidation, and backfill consolidation, Five different gas-generation rate histories were simulated, differentiated by a rate multiplier, f, which ranged from 0.0 (no gas generation) to 1.0 (expected gas generation under brine-dominated conditions). The results of the SANCHO f-series simulations provide a relationship between gas generation, room closure, and room pressure for a perfectly sealed room. Several methods for coupling this relationship with multiphase fluid flow into and out of a room were examined. Two of the methods are described

  3. Design and construction issues associated with sealing of a repository in salt

    International Nuclear Information System (INIS)

    Cook, R.

    1991-01-01

    The isolation of radioactive wastes in geologic repositories requires that man-made penetrations such as shafts, tunnels and boreholes are adequately sealed. This paper presents the current design and construction issues for sealing a repository in salt and outlines some proposed solutions. The sealing components include shaft seals, tunnel seals, panel seals, and disposal room backfill. The performance requirements and construction constraints determine the types of materials selected and their necessary properties. The current issues of interest include: (1) selection of materials for rigid bulkheads used to promote recovery of the disturbed zone permeability; (2) the selection of bulkhead geometry to cutoff flow through more permeable zones, or zones where recovery of the backfill properties occurs more slowly or not at all; and (3) the interaction of fluids with hazardous wastes with brine and, subsequently, with seal materials that might affect seal material longevity. 19 refs., 5 figs., 1 tab

  4. Modeling of release of radionuclides from an engineered disposal facility for shallow-land disposal of low-level radioactive wastes

    International Nuclear Information System (INIS)

    Matsuzuru, H.; Suzuki, A.

    1989-01-01

    The computer code, ENBAR-1, for the simulation of radionuclide releases from an engineered disposal facility has been developed to evaluate the source term for subsequent migration of radionuclides in and through a natural barrier. The system considered here is that a waste package (waste form and container) is placed, together with backfill materials, into a concrete pit as a disposal unit for shallow-land disposal of low-level radioactive wastes. The code developed includes the following modules: water penetration into a concrete pit, corrosion of a drum as a container, leaching of radionuclides from a waste form, migration of radionuclides in backfill materials, release of radionuclides from the pit. The code has the advantage of its simplicity of operation and presentation while still allowing comprehensive evaluation of each element of an engineered disposal facility to be treated. The performance and source term of the facility might be readily estimated with a few key parameters to define the problem

  5. Direct methods of soil-structure interaction analysis for earthquake loadings(II)

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Chung Bang; Lee, S. R.; Kim, J. M.; Park, K. L.; Oh, S. B.; Choi, J. S.; Kim, Y. S. [Korea Advanced Institute of Science Technology, Daejeon (Korea, Republic of)

    1994-07-15

    In this study, methods for 3-D soil-structure interaction analysis have been studied. They are 3-D axisymmetric analysis method, 3-D axisymmetric finite element method incorporating infinite elements, and 3-D boundary element methods. The computer code, named as 'KIESSI - PF', has been developed which is based on the 3-D axisymmetric finite element method coupled with infinite element method. It is able to simulate forced vibration test results of a soil-structure interaction system. The Hualien FVT post-correlation analysis before backfill and the blind prediction analysis after backfill have been carried out using the developed computer code 'KIESSI - PF'.

  6. Radionuclide getters in the near-field chemistry of repositories

    International Nuclear Information System (INIS)

    Holland, T.R.; Lee, D.J.

    1990-08-01

    This programme of work has assessed the radionuclide sorption efficiency of selected inorganic 'getters' incorporated into cement as a means of enhancing the retention of radioactive species by the proposed repository backfill. The study has shown that most of the materials tested retained considerable sorptive properties for radium and caesium after incorporation into cement. However, poor retention of iodine prompted a search for a specific iodine getter. Apart from encapsulated activated carbon, the specific getters tested showed no improved sorption above that of the cement matrix. A study of factors influencing sorption, showed that the getter concentration was the only factor causing a major change in sorption efficiency. Retesting of samples after 12 months sorption indicated that, in general, a slight degree of desorption had taken place. An engineering assessment, examining the physical characteristics of a selected backfill formulation, was carried out, demonstrating the practicability of the process. (author)

  7. Equilibrium leach testing of Magnox swarf and sludge

    International Nuclear Information System (INIS)

    Amin, A.; Angus, M.J.; Kirkham, I.A.; Tyson, A.

    1988-10-01

    A static equilibrium leach test has been developed to simulate repository conditions after ground water has penetrated the near field barrier. The repository components - waste, matrix and backfill - have been equilibrated with water for up to one year. Leachates were analysed for U, Pu, Np 237 , Am 241 , Cs 137 , Sr 90 , Tc 99 , I 129 and C 14 . Results are presented for leaching from Magnox fuel cladding wastes using a combination of matrices, backfills and atmospheric conditions. The equilibrium concentrations were generally very low and have been compared with the concentration of each isotope in drinking water that would give an adult an annual effective dose equivalent of 0.1mSv. (author)

  8. Equilibrium leach testing of Magnox swarf and sludge

    International Nuclear Information System (INIS)

    Amin, A.; Angus, M.J.; Kirkham, I.A.; Tyson, A.

    1987-10-01

    A static equilibrium leach test has been developed to simulate repository conditions after ground water has penetrated the near field barrier. The repository components - waste, matrix and backfill - have been equilibrated with water for up to one year. Leachates were analysed for U, Pu, Np 237 , Am 241 , Cs 137 , Sr 90 , Tc 99 , I 129 and C 14 . Results are presented for leaching from Magnox fuel cladding wastes using a combination of matrices, backfills and atmospheric conditions. The equilibrium concentrations were generally very low and have been compared with the concentration of each isotope in drinking water that would give an adult an annual effective dose equivalent of 0.1mSv. (author)

  9. Particle-scale Analysis of Key Technologies on Cut-and-over Tunnel in Slope Engineering

    Directory of Open Access Journals (Sweden)

    J.H. Yang

    2014-08-01

    Full Text Available When the shallow tunnel is constructed on the slope terrain in the mountains, there are the potential risks such as landslide induced by cutting the slope and the non-compacted backfill material during the construction of the cut-andcover tunnel. In order to solve these problems, based on a practical engineering, the optimized construction plans of the cut-and-cover tunnel were analyzed by particle flow code (PFC, the key parts of the open-cut construction were identified, and the anti-slide piles countermeasures were proposed. Furthermore, the grouting reinforcement process for the non-compacted backfill material around the shallow tunnel was simulated by PFC, and the variation characteristics of the porosity and grouting pressure were revealed as well. The results are of great value to the similar engineering.

  10. An analysis of the thermal and mechanical behavior of engineered barriers in a high-level radioactive waste repository

    International Nuclear Information System (INIS)

    Kwon, S.; Cho, W. J.; Lee, J. O.

    2013-01-01

    Adequate design of engineered barriers, including canister, buffer and backfill, is important for the safe disposal of high level radioactive waste. Three-dimensional computer simulations were carried out under different condition to examine the thermal and mechanical behavior of engineered barriers and rock mass. The research looked at five areas of importance, the effect of the swelling pressure, water content of buffer, density of compacted bentonite, emplacement type and the selection of failure criteria. The results highlighted the need to consider tensile stress in the outer shell of a canister due to thermal expansion of the canister and the swelling pressure from the buffer for a more reliable design of an underground repository system. In addition, an adequate failure criterion should be used for the buffer and backfill.

  11. In situ testing of titanium and mild steel nuclear waste containers at the WIPP site

    International Nuclear Information System (INIS)

    Molecke, M.A.

    1990-01-01

    An overview of the Waste Isolation Pilot Plant (WIPP) in situ tests on the corrosion of titanium and mild steel for high level waste containers is presented. The tests at Sandia have moved out of the laboratory into a test underground facility in order to evaluate the performance of the waste package material. The tests are being performed under both near-reference and accelerated salt repository conditions. Some containers are filled with high level waste glass (non-radioactive); others contain electric heaters. Backfill material is either bentonite/sand or crushed salt. In other tests metals and glasses are exposed directly to brine. The tests are designed to study the corrosion and metallurgy of the canister and overpack materials; the feasibility and performance of backfill materials; and near-field effects such as brine migration

  12. Layout Optimization for the Repository within a discontinuous and saturated granitic rock mass

    International Nuclear Information System (INIS)

    Kim, Jhin Wung; Choi, Jong Won; Bae, Dae Seok

    2005-12-01

    The objective of the present study is a layout optimization of a single and double layer repositories within a repository site with special joint set arrangements. Single and double layer repository models, subjected to the variation of repository depth, cavern spacing, pitch, and layer spacing, are analyzed for the thermal, hydraulic, and mechanical interaction behavior during the period of 2000 years from waste emplacement. Material properties used for the granitic rock mass, rock joints, PWR spent fuel, disposal canister, compacted bentonite, backfill material, and groundwater are the data collected domestically, and foreign data are used for some of the data not available domestically. The repository model includes a saturated granitic rock mass with joints, PWR spent fuel in a disposal canister surrounded by compacted bentonite inside a deposition hole, and backfill material in the rest of the space within a repository cavern

  13. Tabulated In-Drift Geometric and Thermal Properties Used In Drift-Scale Models for TSPA-SR

    International Nuclear Information System (INIS)

    N.D. Francis

    2000-01-01

    The objective of this calculation is to provide in-drift physical properties required by the drift-scale models (both two- and three-dimensional) used in total system performance assessments (TSPA). The physical properties include waste package geometry, waste package thermal properties, emplacement drift geometry including backfill and invert geometry and properties (both thermal and hydrologic), drip shield geometry and thermal properties, all tabulated in a single source

  14. Design confirmation and demonstration for EBS: current developments in several european national programmes as part of the EP6 EURATOM Esdred project

    International Nuclear Information System (INIS)

    Bock, Ch. de; Londe, L.; Weber, H.

    2007-01-01

    In the context of the technological project ESDRED: 'Engineering Studies and Demonstration of Repository Designs', the national waste management agencies ANDRA, ONDRAF/NINAS and NAGRA are currently in the process of demonstration testing the construction of the buffer/backfill component inside the disposal drifts for high level waste (HLW). ESDRED is co-funded by the European Commission (EC) as part of the sixth Euratom research and training Framework Programme (FP6) on nuclear energy (2002-2006). The work aims to demonstrate the technical feasibility at an industrial scale of the construction of the buffer around the disposal package and/or the associated activity of backfilling the remaining voids within the disposal drift. The tests described in this paper are performed in a workshop on the surface, which will enable a better control over the test conditions and facilitate the evaluation of the test results. The following configurations are being tested: - a prefabricated buffer in a horizontal disposal cell (representative of the ANDRA design); - granular and grout backfills in a horizontal disposal drift (representative of the ONDRAF/NIRAS design); - a combination of a prefabricated and a granular buffer in a horizontal disposal drift (representative of the NAGRA design). After the preceding stages of defining the functional requirements of the buffer/backfill component, computer simulation, laboratory testing and designing the buffer prototypes or disposal drift mockups, the work is currently focused on the execution phase of the demonstration testing. The work, although conducted by the agencies in parallel, is characterised by frequent mutual status reporting and exchange of 'lessons-learned' within the context of ESDRED. The work on the in-workshop demonstrators is scheduled to be finalized by the end of 2006. (authors)

  15. Condition Assessment Survey (CAS) Program. Deficiency standards and inspections methods manual: Volume 1, 0.01 Foundations and footings

    Energy Technology Data Exchange (ETDEWEB)

    1993-05-01

    General information is presented for asset determinant factor/CAS repair codes/CAS cost factors; guide sheet tool & material listing; testing methods; inspection frequency; standard system design life tables; system work breakdown structure; and general system/material data. Deficiency standards and inspection methods are given for footings - spread/strip/grade beams; foundation walls; foundation dampproofing/waterproofing; excavation/backfill/ and piles & caissons.

  16. Weathering products of basic rocks as sorptive materials of natural radionuclides

    International Nuclear Information System (INIS)

    Omelianenko, B.I.; Niconov, B.S.; Ryzhov, B.I.; Shikina, N.D.

    1994-06-01

    The principal requirements for employing natural minerals as buffer and backfill material in high-level waste (HLW) repositories are high sorptive properties, low water permeability, relatively high thermal conductivity, and thermostability. The major task of the buffer is to prevent the penetration of radionuclides into groundwater. The authors of this report examined weathered basic rocks from three regions of Russia in consideration as a suitable radioactive waste barrier

  17. Hydro-mechanical evolution of the EDZ as transport path for radionuclides and gas: insights from the Mont Terri rock laboratory (Switzerland)

    International Nuclear Information System (INIS)

    Paul Marschall, P.; Giger, S.; La Vassière De, R.

    2017-01-01

    The excavation damaged zone (EDZ) around the backfilled underground structures of a geological repository represents a release path for radionuclides, which needs to be addressed in the assessment of long-term safety. Additionally, the EDZ may form a highly efficient escape route for corrosion and degradation gases, thus limiting the gas overpressures in the backfilled repository structures. The efficiency of this release path depends not only on the shape and extent of the EDZ, but also on the self-sealing capacity of the host rock formation and the prevailing state conditions, such as in situ stresses and pore pressure. The hydro-mechanical and chemico-osmotic phenomena associated with the formation and temporal evolution of the EDZ are complex, thus precluding a detailed representation of the EDZ in conventional modelling tools for safety assessment. Therefore, simplified EDZ models, able to mimic the safety-relevant functional features of the EDZ in a traceable manner are required. In the framework of the Mont Terri Project, a versatile modelling approach has been developed for the simulation of flow and transport processes along the EDZ with the goal of capturing the evolution of hydraulic significance of the EDZ after closure of the backfilled underground structures. The approach draws on both empirical evidence and experimental data, collected in the niches and tunnels of the Mont Terri rock laboratory. The model was benchmarked with a data set from an in situ self-sealing experiment at the Mont Terri rock laboratory. This paper summarises the outcomes of the benchmark exercise that comprises relevant empirical evidence, experimental data bases and the conceptual framework for modelling the evolution of the hydraulic significance of the EDZ around a backfilled tunnel section during the entire re-saturation phase. (authors)

  18. Treatment and disposal of radioactive wastes from nuclear power plants. Program for encapsulation, deep geologic deposition and research, development and demonstration

    International Nuclear Information System (INIS)

    1995-09-01

    Programs for RD and D concerning disposal of radioactive waste are presented. Main topics include: Design, testing and manufacture of canisters for the spent fuels; Design of equipment for deposition of waste canisters; Material and process for backfilling rock caverns; Evaluation of accuracy and validation of methods for safety analyses; Development of methods for defining scenarios for the safety analyses. 471 refs, 67 figs, 21 tabs

  19. Mitigation of Traffic-Induced Ground Vibration by Inclined Wave Barriers

    DEFF Research Database (Denmark)

    Andersen, Lars; Augustesen, Anders Hust

    2009-01-01

    Double sheet pile walls can be used as wave barriers in order to mitigate ground vibrations from railways. The present analysis concerns the efficiency of such barriers, especially with regard to the influence of the barrier inclination and the backfill between the walls. Thus, the screening capa...... of reference following the load. This allows a computation of the steady state response to a harmonically varying point source moving at different speeds typical for a train....

  20. Computer simulation of an internally pressurized radioactive waste disposal room in a bedded salt formation

    International Nuclear Information System (INIS)

    Brown, W.T.; Weatherby, J.R.

    1991-01-01

    The Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico was created by the U.S. Department of Energy as an underground research and development facility to demonstrate the safe storage of transuranic waste generated from defense activities. This facility consists of storage rooms mined from a bedded salt formation at a depth of about 650 meters. Each room will accommodate about 6800 55-gallon drums filled with waste. After waste containers are emplaced, the storage rooms are to be backfilled with mined salt or other backfill materials. As time passes, reconsolidation of this backfill will reduce the hydraulic conductivity of the room. However, gases produced by decomposition and corrosion of waste and waste containers may cause a slow build-up of pressure which can retard consolidation of the waste and backfilled salt. The authors have developed a finite-element model of an idealized disposal room which is assumed to be perfectly sealed. The assumption that no gas escapes from the disposal room is a highly idealized and extreme condition which does not account for leakage paths, such as interbeds, that exist in the surrounding salt formation. This model has been used in a parametric study to determine how reconsolidation is influenced by various assumed gas generation rates and total amounts of gas generated. Results show that reductions in the gas generation, relative to the baseline case, can increase the degree of consolidation and reduce the peak gas pressure in disposal rooms. Even higher degrees of reconsolidation can be achieved by reducing both amounts and rates of gas generation. 8 refs., 4 figs., 1 tab

  1. Validation of FRP Matting Requirements

    Science.gov (United States)

    2016-08-01

    end loader was used to load and transport crushed stone for the crater backfill (Figure 7). For the larger craters, stone was loaded into dump trucks ...Craig A. Rutland August 2016 Approved for public release; distribution is unlimited. The U.S. Army Engineer Research and Development Center...ERDC) solves the nation’s toughest engineering and environmental challenges. ERDC develops innovative solutions in civil and military engineering

  2. Demonstration and Validation of Controlled Low-Strength Materials for Corrosion Mitigation of Buried Steel Pipes: Final Report on Project F09-A17

    Science.gov (United States)

    2015-12-01

    steel surfaces. Two different CLSM blends were tested. Both used cement and a flowability admixture, but one used native soil instead of standard...by about 63% in the soil cement . Therefore, CLSMs can reduce the cost of applying CP to buried steel structures. The return-on-investment ratio for...was exposed in the native-soil backfill to deter- mine the corrosion rate in the absence of any flowable fill or soil cement . The removable steel

  3. Using Frozen Barriers for Containment of Contaminants

    Science.gov (United States)

    2017-09-21

    barriers are constructed of grout slurry and plastic or steel sheet pilings. Circumferential barriers can be used to completely enclose a source of...2.1.1 Slurry walls A soil-bentonite slurry trench cutoff wall (slurry wall) is excavated and backfilled with grout, cement , or soil-bentonite...installation requires a mixing area, and there is a substantial amount of excavation and the need to dispose of spoil. The advantages of cement -based

  4. A review of geotechnical behavior of stabilized soils:Design and analysis considerations

    OpenAIRE

    Makusa, Gregory Paul

    2013-01-01

    Utilization of stabilization technology for improving the engineering properties of soft soils and sediments for structural backfill, such as land reclamation is increasing. Mass stabilization solidification provides a comprehensive technology for improving the geotechnical properties of the problematic soils for civil engineering applications; hence, solving the problem of scarcity of natural resources, meanwhile, providing a sustainable solution for management of contaminated sediments.In g...

  5. Application of deep hole blasting to shaft sinking in a hard rock-type uranium mine in south china

    International Nuclear Information System (INIS)

    Feng Haisheng; Zeng Lingguo; Ding Dexin

    2009-01-01

    The shaft for backfilling in the 43 exploratory line on the 200 m level in the Mianhuakang mining area in a hard rock uranium mine in South China could not be excavated by using conventional shaft sinking methode since it was near the fault zone and the rock around it was broken and water-bearing. Therefore, the shaft was excavated by using deep hole blasting. This paper presented the design for the blasting and the construction. (authors)

  6. Research program to study the gamma radiation effects in Spanish bentonites

    International Nuclear Information System (INIS)

    Dies, J.; Tarrasa, F.; Cuevas de las, C.; Miralles, L.; Pueyo, J. J.

    2000-01-01

    The engineering barrier of a radioactive waste underground disposal facility, placed in a granitic host rock, will consist of a backfill of compacted bentonite blocks. At first, this material will be subjected to a gamma radiation field, from the waste canister, and heat from the spent fuel inside the canister. Moreover, any groundwater that reaches the repository will saturate the bentonite. For these reasons the performance of the engineered barrier must be carefully assessed in laboratory experiments. (Author)

  7. The Reverse Approach for Monopile Scour

    DEFF Research Database (Denmark)

    Hartvig, Peres Akrawi

    2012-01-01

    The present paper deals with the theoretical and numerical modeling of scouring and backfilling around an offshore monopile. Based on existing relations for the bed load and the bed update, and a new model for the sediment pickup, it demonstrates the possibility of computing the mean bed shear...... stress if the bed and bed update is estimated. The present concepts may be useful for developing methods for scour forecasting....

  8. Hydro-mechanical evolution of the EDZ as transport path for radionuclides and gas: insights from the Mont Terri rock laboratory (Switzerland)

    Energy Technology Data Exchange (ETDEWEB)

    Paul Marschall, P.; Giger, S. [National Cooperative for the Disposal of Radioactive Waste (NAGRA), Wettingen (Switzerland); La Vassière De, R. [Agence Nationale pour la Gestion des Déchets Radioactifs ANDRA, Meuse Haute-Marne, Center RD 960, Bure (France); and others

    2017-04-15

    The excavation damaged zone (EDZ) around the backfilled underground structures of a geological repository represents a release path for radionuclides, which needs to be addressed in the assessment of long-term safety. Additionally, the EDZ may form a highly efficient escape route for corrosion and degradation gases, thus limiting the gas overpressures in the backfilled repository structures. The efficiency of this release path depends not only on the shape and extent of the EDZ, but also on the self-sealing capacity of the host rock formation and the prevailing state conditions, such as in situ stresses and pore pressure. The hydro-mechanical and chemico-osmotic phenomena associated with the formation and temporal evolution of the EDZ are complex, thus precluding a detailed representation of the EDZ in conventional modelling tools for safety assessment. Therefore, simplified EDZ models, able to mimic the safety-relevant functional features of the EDZ in a traceable manner are required. In the framework of the Mont Terri Project, a versatile modelling approach has been developed for the simulation of flow and transport processes along the EDZ with the goal of capturing the evolution of hydraulic significance of the EDZ after closure of the backfilled underground structures. The approach draws on both empirical evidence and experimental data, collected in the niches and tunnels of the Mont Terri rock laboratory. The model was benchmarked with a data set from an in situ self-sealing experiment at the Mont Terri rock laboratory. This paper summarises the outcomes of the benchmark exercise that comprises relevant empirical evidence, experimental data bases and the conceptual framework for modelling the evolution of the hydraulic significance of the EDZ around a backfilled tunnel section during the entire re-saturation phase. (authors)

  9. Research program to study the gamma radiation effects in Spanish bentonites; Programa de investigacion para estudiar los efectos de la radiacion gamma en bentonitas calcicas espanolas

    Energy Technology Data Exchange (ETDEWEB)

    Dies, J; Tarrasa, F [Universidad Politecnica de Catalunya (Spain); Cuevas de las, C; Miralles, L; Pueyo, J J [Universidad de Barcelona (Spain)

    2000-07-01

    The engineering barrier of a radioactive waste underground disposal facility, placed in a granitic host rock, will consist of a backfill of compacted bentonite blocks. At first, this material will be subjected to a gamma radiation field, from the waste canister, and heat from the spent fuel inside the canister. Moreover, any groundwater that reaches the repository will saturate the bentonite. For these reasons the performance of the engineered barrier must be carefully assessed in laboratory experiments. (Author)

  10. CATSIUS CLAY PROJECT: Calculation and testing of behaviour of unsaturated clay as barrier in radioactive waste repositories: stage 3: validation exercises at a large in situ scale

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, E E; Alcoverro, J

    1999-07-01

    Stage 3 of CATSIUS CLAY Project: Validation Exercises at a Large in situ Scale includes two Benchmarks: Benchmark 3.1: In situ Hydration of Boom Clay Pellets (BACCHUS 2) and Benchmark 3.2: FEBEX Mock-up Test. The BACCHUS 2 in situ test was performed in the HADES underground laboratory (Mol, Belgium) to demonstrate and optimize an installation procedure for a clay based material and to study its hydration process. After drilling a vertical shaft (540 mm in diameter, 3.0 m in length) in the host Boom clay, a central filter (90 mm in diameter) was placed, the remaining space was filled with a mixture of clay pellets and clay powder and the assembly was sealed at the upper end by a resin plug (0.20 m in thickness) over which concrete was poured. The test was instrumented so that it could be used as a validation experiment. Total stress, pore water pressure and water content measurements were performed both in the backfill material and in the surrounding clay massif. Once the installation was complete, the natural hydration of the backfill material began (day 0). To accelerate the hydration process, on day 516 water was injected through the central filter. On day 624, after the saturation of the backfill was reached, the hydraulic circuit was closed and the undrained response of the system backfill-host clay was monitored until an overall steady state was reached. Partners were asked to provide predictions for the evolution of the pore water pressure and total pressure of various points where appropriate sensors are installed. This benchmark addresses the Hydro-Mechanical response of an unsaturated low density clay barrier under natural and artificial hydration. (Author)

  11. Engineered barrier development for a nuclear waste repository in basalt: an integration of current knowledge

    International Nuclear Information System (INIS)

    Smith, M.J.

    1980-05-01

    This document represents a compilation of data and interpretive studies conducted as part of the engineered barriers program of the Basalt Waste Isolation Project. The overall objective of these studies is to provide information on barrier system designs, emplacement and isolation techniques, and chemical reactions expected in a nuclear waste repository located in the basalts underlying the Hanford Site within the state of Washington. Backfills, waste-basalt interactions, sorption, borehole plugging, etc., are among the topics discussed

  12. Coupled modelling of convergence, steel corrosion, gas production and brine flow in a rock salt repository

    International Nuclear Information System (INIS)

    Becker, D.A.; Hirsekorn, R.P.

    2013-01-01

    This poster presents the global simulation of the behaviour of thick-walled steel containers piled up in a borehole in a rock salt repository. The simulation takes into account: the convergence by the creeping of rock salt, the backfill and waste compaction, the porosity dependent flow resistance, the anaerobic corrosion (iron to magnetite transformation, gas production, brine consumption, water consumption and salt precipitation) and pressure development. Mechanical influence of corrosion has not yet been taken into account in the integrated code LOPOS

  13. Panel session: Disposal of HLW - ready for implementation

    International Nuclear Information System (INIS)

    Heremans, R.; Come, B.; Barbreau, A.; Girardi, F.

    1986-01-01

    The paper is a report of a panel session at the European Community conference on radioactive waste management and disposal, Luxembourg 1985, concerning the safe and long-term disposal of high-activity and long-lived waste. The subjects discussed include: geological barriers including deep sea-bed sediments, engineered barriers, technological problems (repository construction, waste emplacement, backfilling and sealing), safety analysis, performance assessment of disposal system components, and finally institutional, legal and financial aspects of geological disposal. (U.K.)

  14. Proceedings of the 1985 conference on coal mine subsidence in the Rocky Mountain Region

    Energy Technology Data Exchange (ETDEWEB)

    Hynes, J.L. (ed.)

    1986-01-01

    A total of 20 papers were presented at the conference on the following subjects: reclamation projects; geological surveys; history and evolution of mining; essential components of mine subsidence; subsidence related damage; core recovery of poorly consolidated materials; evaluation of subsurface conditions; remote video inspection of abandoned coal mines; use of progressive failure model for subsidence prediction; chimney subsidence sinkhole development; analytical methods of subsidence prediction; monitoring networks; architectural mitigating measures; backfilling; awareness and planning; administrative aspects; mine subsidence insurance; risk management.

  15. Nuclear waste management. Quarterly progress report, July-September 1980

    Energy Technology Data Exchange (ETDEWEB)

    Chikalla, T.D.

    1980-11-01

    Research is reported on: high-level waste immobilization, alternative waste forms, TRU waste immobilization and decontamination, krypton solidification, thermal outgassing, /sup 129/I fixation, unsaturated zone transport, well-logging instrumentation, waste management system and safety studies, effectiveness of geologic isolation systems, waste/rock interactions, engineered barriers, backfill material, spent fuel storage (criticality), barrier sealing and liners for U mill tailings, and revegetation of inactive U tailings sites. (DLC)

  16. Simulation approaches for the two-phase flow in saline repositories using the code TOUGH2-GRS. Report in the frame of the project ZIESEL. Two-phase flow in a saline repository using the example ERAM; Ansaetze zur Simulation der Zweiphasenstroemung in salinaren Endlagern mit dem Code TOUGH2-GRS. Bericht im Vorhaben ZIESEL. Zweiphasenfluss in einem salinaren Endlager am Beispiel des ERAM

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, Martin; Fischer, Heidemarie; Seher, Holger; Weyand, Torben

    2016-10-15

    The simulation approaches for the two-phase flow in saline repositories using the code TOUGH2-GRS cover the following issues: simulation of gravitational flows in horizontal galleries without vertical discretization, homogenization approach for the simulation of the two-phase flow in converging partly backfilled galleries, qualification of the convergence approach implemented by GRS into the code TOUGH2-GRS, discretization effects during replacement of liquid by gas, consequences for the system analyses in the frame of the project ZIESEL.

  17. BSLD threshold driven power management policy for HPC centers

    OpenAIRE

    Etinski, Maja; Corbalán González, Julita; Labarta Mancho, Jesús José; Valero Cortés, Mateo

    2010-01-01

    In this paper, we propose a power-aware parallel job scheduler assuming DVFS enabled clusters. A CPU frequency assignment algorithm is integrated into the well established EASY backfilling job scheduling policy. Running a job at lower frequency results in a reduction in power dissipation and accordingly in energy consumption. However, lower frequencies introduce a penalty in performance. Our frequency assignment algorithm has two adjustable parameters in order to enable fine grain energy-perf...

  18. Scientific basis for nuclear waste management XX

    International Nuclear Information System (INIS)

    Gray, W.J.; Triay, I.R.

    1997-01-01

    The proceedings are divided into the following topical sections: Glass formulations and properties; Glass/water interactions; Cements in radioactive waste management; Ceramic and crystalline waste forms; Spent nuclear fuel; Waste processing and treatment; Radiation effects in ceramics, glasses, and nuclear waste materials; Waste package materials; Radionuclide solubility and speciation; Radionuclide sorption; Radionuclide transport; Repository backfill; Performance assessment; Natural analogues; Excess plutonium dispositioning; and Chernobyl-related waste disposal issues. Papers within scope have been processed separately for inclusion on the data base

  19. Underground transportation and handling system for Pollux-casks

    International Nuclear Information System (INIS)

    Schrimpf, C.

    1988-01-01

    The concept for the underground transportation and handling system for Pollux-casks was optimized in a first phase by dividing the process in the repository up into the several transportation and manipulation steps. For each step, the possibilities were described and evaluated by means of a list of criteria (technical, safety and economical criteria). The following concept for the transportation and handling was developed: The casks are transported to the unloading area of the surface facilities by railway or truck. After removal of the transport protection, the entry control is performed. The cask is lifted from the vehicle and placed on a railbound transportation vehicle. This transport unit is transferred to the shaft and placed there ready for shaft hoisting. With the hoisting cage protruding, the transport unit is placed on the hoisting cage by means of a pushing-on device, locked, and then conveyed underground. After arrival on the emplacement level, the transport unit is pulled-off from the hoisting cage and taken over by a mine locomotive and transferred through the transportation and access drifts as far as to the emplacement site. There the locomotive pushed the rail transport vehicle into the emplacement drift, as far as to the designated emplacement position. At the emplacement position, the cask is again lifted by means of hoisting equipment. The rail transport vehicle is pulled out of the emplacement drift and returned to the surface for reloading. After deposition of the cask on the drift floor, the emplacement equipment is pulled back in order to give the operation space free for the slinger backfill truck. Within preceding tests two different backfilling techniques were investigated under realistic conditions: pneumatic backfilling and slinger backfilling. The slinger truck was found to be the most suitable for the designated purpose

  20. Proceedings of the Canadian Nuclear Society 2. international conference on radioactive waste management

    International Nuclear Information System (INIS)

    1986-01-01

    These proceedings contain 136 papers on waste management from 19 countries. An index of the delegates and their affiliations is included. Emphasis was laid on the Canadian program for geologic disposal in hard rock. Sessions dealt with the following: storage and disposal, hydrogeology and geochemistry, transportation, buffers and backfill, public attitudes, tailings, site investigations and geomechanics, concrete, economics, licensing, matrix materials and container design, durability of fuel, biosphere modelling, radioactive waste processing, and future options