WorldWideScience

Sample records for backfilling

  1. Backfill design 2012

    International Nuclear Information System (INIS)

    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. Uniaxial backfill block compaction

    International Nuclear Information System (INIS)

    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.)

  3. Systematic Selection and Application of Backfill in Underground Mines

    OpenAIRE

    Masniyom, Manoon

    2009-01-01

    The use of backfill in underground mining is increasing due to need for systematic backfilling of mine openings and workings to avoid surface damage, increase safety and contribution to sustainable mining. This study is to investigate backfill materials and new methods suited for systematic selection and application of backfill in underground mines. Laboratory tests were carried out on physical, chemical and mechanical properties of different backfill materials and mixtures thereof. Special a...

  4. Colonization of compacted backfill materials by microorganisms

    International Nuclear Information System (INIS)

    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 106 to 107 colony forming units (CFU)/mL after about one week. Anaerobic heterotrophs stabilized at around 102 to 103 CFU/mL. Sulphate-reducing bacteria (SRB) were measured by the most probable number (MPN) method. Results showed low initial numbers but they stabilized around 104 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-flowing permeameters

  5. A Historical Review of WIPP Backfill Development

    Energy Technology Data Exchange (ETDEWEB)

    Brush, L.H.; Krumhansl, J.L.; Molecke, M.A.; Papenguth, H.W.

    1999-07-15

    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. It's introduction was motivated by the need to scavenging CO{sub 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.

  6. A Historical Review of WIPP Backfill Development

    International Nuclear Information System (INIS)

    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. It's introduction was motivated by the need to scavenging CO2 [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

  7. Performance of cemented coal gangue backfill

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qin-li; WANG Xin-min

    2007-01-01

    Possibility of cemented gangue backfill was studied with gangue of Suncun Coal Mine, Xinwen Coal Group, Shandong,and fly ash of nearby thermal power plant, in order to treat enormous coal gangue on a large scale and to recovery safety coal pillars.The results indicate that coal gangue is not an ideal aggregate for pipeline gravity flow backfill, but such disadvantages of gangue as bad fluidity and serious pipe wear can be overcome by addition of fly ash. It is approved that quality indexes such as strength and dewatering ratio and piping feature of slurry can satisfy requirement of cemented backfill if mass ratio of cement to fly ash to gangue higher middle and long term comprehensive strength.

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

    OpenAIRE

    Qingliang Chang; Jianhang Chen; Huaqiang Zhou; Jianbiao Bai

    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 a...

  9. Time-dependent nuclide transport through backfill into a fracture

    International Nuclear Information System (INIS)

    This paper presents a transient analysis of radionuclide transport through backfill into a fissure. This report considers a waste canister surrounded by backfill in a borehole intersected by a fracture, in water-saturated rock. Radionuclides are released at a constant concentration C/sub s/ at the waste surface into the backfill. Ground water flows in the fissure. We assume no ground-water flow in the backfill, so that radionuclide transport through the backfill is controlled by molecular diffusion. 3 refs., 2 figs

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

    International Nuclear Information System (INIS)

    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

  11. 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

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

    Directory of Open Access Journals (Sweden)

    Qingliang Chang

    2014-01-01

    Full Text Available 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.

  13. 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

  14. Tunnel backfill erosion by dilute water

    International Nuclear Information System (INIS)

    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 (BESWD and BESWS) 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.)

  15. 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.)

  16. Some characteristics of potential backfill materials

    International Nuclear Information System (INIS)

    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 1500C completely hydrates in less than 10 hours. At 600C and 200C, such extensive hydration requires about 100 and 1000 hours, respectively. The product of the reaction is stable to more than 3000C. 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

  17. Wormhole Formation in RSRM Nozzle Joint Backfill

    Science.gov (United States)

    Stevens, J.

    2000-01-01

    The RSRM nozzle uses a barrier of RTV rubber upstream of the nozzle O-ring seals. Post flight inspection of the RSRM nozzle continues to reveal occurrence of "wormholes" into the RTV backfill. The term "wormholes", sometimes called "gas paths", indicates a gas flow path not caused by pre-existing voids, but by a little-understood internal failure mode of the material during motor operation. Fundamental understanding of the mechanics of the RSRM nozzle joints during motor operation, nonlinear viscoelastic characterization of the RTV backfill material, identification of the conditions that predispose the RTV to form wormholes, and screening of candidate replacement materials is being pursued by a joint effort between Thiokol Propulsion, NASA, and the Army Propulsion & Structures Directorate at Redstone Arsenal. The performance of the RTV backfill in the joint is controlled by the joint environment. Joint movement, which applies a tension and shear load on the material, coupled with the introduction of high pressure gas in combination create an environment that exceeds the capability of the material to withstand the wormhole effect. Little data exists to evaluate why the material fails under the modeled joint conditions, so an effort to characterize and evaluate the material under these conditions was undertaken. Viscoelastic property data from characterization testing will anchor structural analysis models. Data over a range of temperatures, environmental pressures, and strain rates was used to develop a nonlinear viscoelastic model to predict material performance, develop criteria for replacement materials, and quantify material properties influencing wormhole growth. Three joint simulation analogs were developed to analyze and validate joint thermal barrier (backfill) material performance. Two exploratory tests focus on detection of wormhole failure under specific motor operating conditions. A "validation" test system provides data to "validate" computer models and

  18. Design, production and initial state of the deposition tunnel backfill

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. In the Finnish KBS-3V type repository for spent nuclear fuel the deposition tunnels are closed with backfill consisting of different clay based components and a concrete plug constructed at the mouth of the deposition tunnels. The work described in this paper was initiated by Posiva Oy and is reported in Keto et al. (2012). The objectives of the report was to present the design basis, requirements, design, production and initial state of the backfill and to work as background material for the construction license application for the Finnish repository for spent nuclear fuel. This paper is limited to presenting the backfill part of the work. The performance targets for the backfill are to limit advective flow along the deposition tunnels, keep the buffer in place and contribute to the mechanical stability of deposition tunnels. In addition, the chemical composition of the backfill shall not jeopardize the performance of the buffer, canister or bedrock. The backfill design consists of three different main components: foundation layer installed at site, pre-compacted backfill blocks and bentonite pellets. Approximately 86% of the nominal tunnel volume will be filled with backfill blocks and the remaining volume with the other two components. The backfill blocks consist of Friedland clay from Germany with smectite content between 30-38%. The foundation layer material and pellets consist of bentonite clay from Greece with smectite content of 75-90%. The production chain for backfill consists of excavation and processing of the materials at site, delivery, acceptance of the material batch to production, transport, handling and storage of raw materials and components in different phases and manufacturing and installation of backfill components. Quality control is included in all phases of the production chain. The initial state of the backfill describe the material properties of the components and the average properties

  19. 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

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

    International Nuclear Information System (INIS)

    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 (FeS2) 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 both

  1. Backfilling with Fairness and Slack for Parallel Job Scheduling

    International Nuclear Information System (INIS)

    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.

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

    International Nuclear Information System (INIS)

    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

  3. 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

  4. Strata movement controlling effect of waste and fly ash backfillings in fully mechanized coal mining with backfilling face

    Institute of Scientific and Technical Information of China (English)

    Zhang Jixiong; Zhang Qiang; Huang Yanli; Liu Jinwei; Zhou Nan; Zan Dongfeng

    2011-01-01

    A fully mechanized coal mining with backfilling (FMCMB) provides advantages of safety and efficiency for coal mining under buildings,railways,and water bodies.According to the field geological conditions,we analyzed the controlling effect of strata movement by the waste and fly ash backfilling in FMCMB face.Based on the key strata theory,we established the equivalent mining thickness model,and analyzed the action of the bulk factor of backfilling body to the equivalent mining thickness.In addition,we numerically simulated the controlling function of the strata movement by backfilling bodies with different strength.And the numerical simulation result show that the deformation of stratum and the subsidence of surface can be controlled by FMCMB.The result provides references to the effective execution of fully mechanized coal mining with solid waste backfilling in goal.

  5. A numerical evaluation of continuous backfilling in cemented paste backfilled stope through an application of wick drains

    Institute of Scientific and Technical Information of China (English)

    Li Li; Yang Pengyu

    2015-01-01

    Cemented paste backfill (CPB) is gaining popularity in many underground mines worldwide. Sufficient water is added into CPB to make a flowable material for pipe transportation. Barricades are built near the drawpoints to prevent in-rush of the fill slurry. To avoid barricade failures resulting from excessive backfill pressures, backfilling is typically performed with a plug pour followed by a final pour. The inter-val between the two pours should be shortened or removed to increase mining productivity and avoid pipe clogging. Recently, Li proposed to apply wick drains in backfilled stopes to promote drainage and consolidation. The preliminary simulations by considering an instantaneous filling indicated that the drainage of CPB can be significantly accelerated by using wick drains. Barricade was not considered. Here, some new numerical modellings are presented with more representative filling sequences, stope geometry, and different draining configurations. The results illustrate that the stope can be backfilled continuously by using wick drains.

  6. Dedicated heterogeneous node scheduling including backfill scheduling

    Science.gov (United States)

    Wood, Robert R.; Eckert, Philip D.; Hommes, Gregg

    2006-07-25

    A method and system for job backfill scheduling dedicated heterogeneous nodes in a multi-node computing environment. Heterogeneous nodes are grouped into homogeneous node sub-pools. For each sub-pool, a free node schedule (FNS) is created so that the number of to chart the free nodes over time. For each prioritized job, using the FNS of sub-pools having nodes useable by a particular job, to determine the earliest time range (ETR) capable of running the job. Once determined for a particular job, scheduling the job to run in that ETR. If the ETR determined for a lower priority job (LPJ) has a start time earlier than a higher priority job (HPJ), then the LPJ is scheduled in that ETR if it would not disturb the anticipated start times of any HPJ previously scheduled for a future time. Thus, efficient utilization and throughput of such computing environments may be increased by utilizing resources otherwise remaining idle.

  7. 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)

    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

  8. Exchangeability of bentonite buffer and backfill materials

    International Nuclear Information System (INIS)

    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

  9. Numerical modeling of subsidence associated with different backfill configurations

    International Nuclear Information System (INIS)

    Due to the continuing use of abandoned mine lands over room and pillar mines it has become important to control the damages caused by surface subsidence. This paper deals with an investigation of the subsidence associated with different backfill configurations. Subsidence corresponding to a typical room and pillar abandoned mine in a number of geological columns were studied by using the finite element method. Subsidence profile was determined by the incorporation of bulking factors and varying depths of backfill. The results of the study show that the grout backfill configurations can be altered to reach a desired subsidence profile. This may increase the ability to protect a structure from large differential settlements without totally backfilling the mine. 10 refs., 5 figs., 4 tabs

  10. Shrinkage of backfill gutta-percha upon cooling

    OpenAIRE

    Lottanti, Silvio; Tauböck, Tobias T; Zehnder, Matthias

    2014-01-01

    INTRODUCTION The temperature and related shrinking kinetics of gutta-percha injected from heat guns are not known; therefore, we investigated them in this study. METHODS The temperatures of 3 different backfill gutta-percha brands extruded from 3 commercially available heat guns set to 200°C were studied. To validate the results, temperature development of 1 gutta-percha brand injected from a heat gun during a simulated backfilling procedure was assessed in single-rooted human teeth contai...

  11. Status of Research on Magnesium Oxide Backfill

    Energy Technology Data Exchange (ETDEWEB)

    PAPENGUTH,HANS W.; KRUMHANSL,JAMES L.; BYNUM,R. VANN; WANG,YIFENG; KELLY,JOHN W.; ANDERSON,HOWARD; NOWAK,E. JAMES

    2000-07-31

    For the WIPP, chemical and physical characteristics of MgO suggest it to be the most beneficial backfill choice, particularly because it has the ability to buffer the aqueous chemical conditions to control actinide volubility. In the current experimental program, the authors are developing a technical basis for taking credit for the complete set of attributes of MgO in geochemical, hydrogeological, and geomechanical technical areas, resulting in an improved conceptual model for the WIPP such as the following. Water uptake by MgO will delay the development of mobile actinides and gas generation by microbes and corrosion. Reduced gas generation will reduce or even eliminate spallings releases. As MgO hydrates, it swells, reducing porosity and permeability, which will inhibit gas flow in the repository, in turn reducing spallings releases. Hydration will also result in a self-sealing mechanism by which water uptake and swelling of MgO adjacent to a groundwater seep cuts off further seepage. Reaction with some groundwaters will produce cementitious materials, which will help to cement waste particles or produce a cohesive solid mass. Larger particles are less likely to be entrained in a spallings release. If sufficient water eventually accumulates in a repository to support microbial gas generation, magnesium carbonate cements will form; also producing good cohesion and strength.

  12. Status of Research on Magnesium Oxide Backfill

    International Nuclear Information System (INIS)

    For the WIPP, chemical and physical characteristics of MgO suggest it to be the most beneficial backfill choice, particularly because it has the ability to buffer the aqueous chemical conditions to control actinide volubility. In the current experimental program, the authors are developing a technical basis for taking credit for the complete set of attributes of MgO in geochemical, hydrogeological, and geomechanical technical areas, resulting in an improved conceptual model for the WIPP such as the following. Water uptake by MgO will delay the development of mobile actinides and gas generation by microbes and corrosion. Reduced gas generation will reduce or even eliminate spallings releases. As MgO hydrates, it swells, reducing porosity and permeability, which will inhibit gas flow in the repository, in turn reducing spallings releases. Hydration will also result in a self-sealing mechanism by which water uptake and swelling of MgO adjacent to a groundwater seep cuts off further seepage. Reaction with some groundwaters will produce cementitious materials, which will help to cement waste particles or produce a cohesive solid mass. Larger particles are less likely to be entrained in a spallings release. If sufficient water eventually accumulates in a repository to support microbial gas generation, magnesium carbonate cements will form; also producing good cohesion and strength

  13. System design of backfill - An ongoing project with the aim to test SKB's backfill installation concept in tunnel conditions

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. SKB in Sweden is developing and implementing concepts for final disposal of spent nuclear fuel. A KBS-3V repository consists of deposition tunnels with copper canisters containing spent fuel placed in vertical deposition holes. The canisters are embedded in highly compacted bentonite. After placement of canisters and bentonite, the deposition tunnels are backfilled with pre-compacted blocks of bentonite stacked on a bed of bentonite pellets. The remaining slot between the blocks and rock wall will be filled with bentonite pellets. The project described in this abstract is an ongoing project aiming to further develop the concept for backfill described in SKB's licence application for a Spent Fuel Repository in Forsmark. Results from this project will give important input for the Preliminary Safety Analysis Report (PSAR) needed to get permission to start the construction of the Spent Fuel Repository. The main objective with this project is to ensure that the method selected for backfill including methods for inspection works as intended with reasonable efficiency. The backfill design needs to be set since it forms the basis for requirements on deposition tunnels, deposition sequence etc. This project System Design of Backfill was started in early 2010 and will continue until the end of 2013. The project budget is 26 MSEK. The work consists of investigations, calculations, laboratory tests, tests in the Bentonite Laboratory and underground tests at Aespoe HRL, Sweden. The project objective is to further develop SKB's reference concept for backfill by performing a system design and to ensure that the reference method works as intended with reasonable efficiency. The stacking pattern for backfill blocks has been developed, see Figure 1. A stacked brick pattern is more stable than a pattern with continuous joints which implies less need for a compacted foundation bed. A conclusion from performed tests is that it is

  14. Tests to determine water uptake behaviour of tunnel backfill

    International Nuclear Information System (INIS)

    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

  15. 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

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

    International Nuclear Information System (INIS)

    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 CO2 [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

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

    Energy Technology Data Exchange (ETDEWEB)

    KRUMHANSL,JAMES L.; MOLECKE,MARTIN A.; PAPENGUTH,HANS W.; BRUSH,LAURENCE H.

    2000-06-05

    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{sub 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.

  18. Ocean disposal of heat generating radioactive waste backfilling requirements

    International Nuclear Information System (INIS)

    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

    International Nuclear Information System (INIS)

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

    International Nuclear Information System (INIS)

    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

  1. On the risk of liquefaction of buffer and backfill

    International Nuclear Information System (INIS)

    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/m3 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/m3. 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

  2. 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

  3. 30 CFR 819.19 - Auger mining: Backfilling and grading.

    Science.gov (United States)

    2010-07-01

    ... environment. (5) Spoil placed on the outslope during previous mining operations shall not be disturbed if such... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Auger mining: Backfilling and grading. 819.19 Section 819.19 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF...

  4. Ion-exchange equilibria and diffusion in engineered backfill

    International Nuclear Information System (INIS)

    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 cm2/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. Protection against flashback by backfilling with rock salt gruss

    International Nuclear Information System (INIS)

    If wastes are disposed of in deep geological formations, e.g. in salt domes, radiolytically produced hydrogen may escape from the waste forms into the boreholes, forming an inflammable mixture with air. Complementary to part I (Report Juel-Spez--573), here the protection against flashback by salt gruss backfillings, the volume and form of the flammability range are examined. It was found out that salt gruss backfillings, under certain conditions, can prevent flashbacks in hydrogen-air mixtures, the most important condition being that the backfillings contain trickling material of the finest particle size of between 0 and 2 mm. Unfractional backfillings drilled in the domes of rock salt formations meet this requirement in their dry state. Their water content must not exceed 2 mass per cent. For flashback, the flammability point referred to as 'near' is more critical than the one referred to as 'far'. The length-diameter ratio of the hollow space where the mixture is ignited only has a secondary influence on the flashback. It hardly plays a role either whether the surfaces of the flammability ranges are rough or smooth. (orig./BBR)

  6. 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

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

    International Nuclear Information System (INIS)

    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

  8. Analysis of factors affecting the stability of backfill materials

    International Nuclear Information System (INIS)

    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 3000C, 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

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

    International Nuclear Information System (INIS)

    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

  10. A New Mode of Coal Mining Under Buildings with Paste-Like Backfill Technology

    Institute of Scientific and Technical Information of China (English)

    崔建强; 孙恒虎; 黄玉诚

    2002-01-01

    The formation of the paste-like backfill technology was introduced briefly in this paper. From the actual cases of coal mines, a new mode of coal mining un der buildings with the technology was proposed. And its specificity was analyzed , and a further introduction to the full-sand-soil solidifying material was given. The main parts of the backfill system, such as the backfill preparation system, the pipeline transportation system, the backfill systems in fully-mechanized mining faces and the backfill process, were presented emphatically.

  11. 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

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

    International Nuclear Information System (INIS)

    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 226Ra 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 222Rn emanation rate and 226Ra 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. - Highlights: • 222Rn emanation rate of the backfilled tailings varied from 0.12 to 7.03 Bq m−2 s−1. • Good correlation between 222Rn emanation rate and 226Ra activity concentration found. • Higher 222Rn emanation rate was obtained from moist backfilled tailings. • Radon emanation factor of the backfilled tailings varied in the range of 0.08–0.23. • Emanation factor of wet tailings was about 3 times higher than that of dry tailings

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

    International Nuclear Information System (INIS)

    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)

  14. Backfill as an engineered barrier for nuclear waste management

    International Nuclear Information System (INIS)

    The swelling, plastic flow, and relative impermeability of bentonite and hectorite were observed and measured after wetting with concentrated brines. Measurements of stable values of pH > 6.5 for the interstitial brines in wetted bentonite and hectorite confirmed conditions favorable for precipitation and sorption of transuranics. Values of K/sub d/ > 2000 ml/g were measured for Pu and Am. Calculated estimates of the effectiveness of a one-foot-thick backfill barrier are presented. They show that the breakthrough of Pu and other transuranics (K/sub d/ = 2000 ml/g) can be delayed for 104 to 105 years. The breakthrough of most fission products (K/sub d/ = 200 ml/g) can be delayed for 103 to 104 years, sufficient time for them to decay to very low concentrations. A backfill barrier can contribute significantly to a radioactive waste isolation system

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

    International Nuclear Information System (INIS)

    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)

  16. Reactive backfills in radioactive waste disposal selenium sorption on apatite

    International Nuclear Information System (INIS)

    Apatites are investigated as possible high performance material for reactive backfills in radioactive waste disposal. An experimental study showed an excellent selenite retaining rate and established the main characteristic of this element sorption on natural and synthetic apatites. Thermodynamical parameters have been calculated and integrated in a geochemical computer code in order to demonstrate the excellent potentialities of the apatite as a trap mineral for the selenium. (A.L.B.)

  17. Approach for Measuring Swelling Stress of Buffer Backfilling Material

    OpenAIRE

    Ming Zhang; Huyuan Zhang; Suli Cui; Lingyan Jia

    2012-01-01

    The characteristics of swelling stress of buffer backfilling material have been studied by forcebalance method and constant volume test method in this paper. The constant volume test apparatus was designed by the authors. Results show that swelling stress changing with time is a little different between the two methods. The value of swelling stress measured by constant volume test is more accurate; besides, uptaking water with time could also be monitored by constant volume test. The constant...

  18. Groundwater recovery problems associated with opencast mine backfills

    OpenAIRE

    Reed, S M

    1986-01-01

    The research outlined in this thesis is concerned with the environmental aspects of groundwater re-establishment as a consequence of surface mining. No principal effects which have been identified as being detrimental to the restored land area are as follows; i). The vertical and horizontal displacements of backfill materials following restoration, and ii). The pollution of groundwater from contact with weathered rockfill materials. The research into settlement has attempted to cl...

  19. Water quality and hydrologic impacts of disposal of uranium mill tailings by backfilling

    International Nuclear Information System (INIS)

    Backfilling of the sand portion of spent uranium mill tailings has been practised for years in the Grants Mineral Belt of New Mexico, USA. Until recently, it has been limited to abandoned stopes requiring roof support to enable continued ore production. Recent environmental regulations of surface disposal make backfilling an increasingly attractive alternative for disposal of a greater fraction of the tails. This paper discusses the impacts of the backfill process on groundwater resources. Immediate and long-term hydrologic effects are evaluated. Whereas backfilling does lead to some changes in minewater flows, these changes are localized, of slight magnitude, and of short duration. In the long term, backfilling will have inconsequential impact on regional hydrology. Short- and long-term water quality impacts are considered. In general, backfill decant is contaminated with the same constituents found in normal mine wastewater, but at elevated concentrations. During the backfill process, backfill decant is returned to the surface and treated along with dewatering discharge. In the longer term, there may exist some potential for contaminants mobilized from backfill media in a flooded mine to migrate into the surrounding aquifer. It is predicted that low groundwater velocities and geochemical interactions including precipitation will together prevent any backfill-caused deterioration of regional groundwater quality. (author)

  20. 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.

  1. Backfilling technology and strata behaviors in fully mechanized coal mining working face

    Institute of Scientific and Technical Information of China (English)

    Zhang Qiang; Zhang Jixiong; Huang Yanli; Ju Feng

    2012-01-01

    Based on the principle of fully mechanized backfilling and coal mining technology and combined with theXingtai Coal Mine conditions,we mainly optimized the coal mining equipment and adjusted the coal mining method in the Xingtai Coal Mine 7606 working face for implementation this technology,Firstly,we define the practical backfilling process as the "(from backfilling scraper conveyor's) head to tail backfilling,step by step swinging up of the tamping arm.gradual compacting,moving formed backfilling scraper conveyor when the second tamping arm cannot pass and connecting the immediate roof by back material push front material movement".Meanwhile,the stress changes of backfill body in coal mined out area was monitored by stress sensors,and the roof caving law was analyzed by monitoring the dynamic subsidence of -210 west roadway of this face.The site tests results show that using this new backfilling and coal mining integrated technology,the production capacity in the 7606 working face can reach to 283,000 ton a year,and 282,000 ton of solid materials (waste and fly ash) is backfilled,which meets the needs of high production and efficiency.The goaf was compactly backfilled with solid material and the strata behavior was quite desirable,with an actual maximum vertical stress of the backfill body of 5.5 MPa.Backfill body control the movement of overburden within a certain range,and there is no collapses of major areas in the overlying strata upon backfilled gob.The maximum subsidence and speed were 231 mm and 15.75 mm/d respectively,which proved the practical significance of this integrated technology.

  2. 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....

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

    International Nuclear Information System (INIS)

    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)

  4. Geotechnical charcterization of coal refuse for use as a backfill material

    OpenAIRE

    Bowman, Charles H

    1991-01-01

    Both active and residual mine subsidence resulting from underground coal mining have caused surface damage to land and structures. A method of subsidence mitigation successfully used abroad, and to a much lesser extent in U.S. coal mines, is backfilling. In addition to the possible benefits of subsidence mitigation, backfilling has the potential to increase coal recovery, enhance ventilation control, and to minimize mine fires. Backfilling can also be used as a means of mine refuse disposal, ...

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

    International Nuclear Information System (INIS)

    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

  6. 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

  7. Behavior of Radionuclides and RCRA Elements in Tank Backfill Grouts

    International Nuclear Information System (INIS)

    One approach to decommissioning emptied high-level waste tanks is to backfill them with grout. Because of the long lives and high toxicity of some of the contaminants, the chemical behavior of the contaminants in the grout need to be understood, especially as the grout ages and weathers over long times. In this paper, the sequestration of technetium and iodine in contact with two grout formulations, and their component materials, is discussed. Preliminary results are presented of experiments examining the solubility of actinides in contact with the grouts as pH is lowered and carbonate content increased, representing conditions of a weathered grout system. (authors)

  8. 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.

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

    International Nuclear Information System (INIS)

    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 (Kd) and the apparent diffusion coefficient (Da) 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

  10. Chemical behaviour of montmorillonite in a final repository backfill

    International Nuclear Information System (INIS)

    With a view to supplementing an earlier report (NTB 86-12, EIR 576), publications appearing in the interim period have been evaluated. Particular emphasis was placed on the thermodynamic status of the clay minerals, the long term stability of montmorillonite and interactions with other repository components. Smectites and illites are presumably thermodynamically unstable and even the formation of metastable solubility equilibria is questionable. Basic problems are thus encountered when formulating equilibrium models for the clay/water interaction. It can be concluded from investigations of argillaceous sediments that, given a repository temperature of 50 to 60 degrees C, a maximum of 50 % of the montmorillonite will alter to illite over a period of around 108 years. The formation of such illite/smectite interstratifications does not impair the function of the backfill material. Since the alteration of calcium montmorillonite is very restricted in comparison with that of the sodium variant, a calcium bentonite should be foreseen as the backfill material. Magnetite is probably unstable in the presence of montmorillonite. The thermodynamic data and experimental results necessary to allow a reliable assessment of potential interactions between the bentonite and the steel canister corrosions products are lacking. Given the current state of knowledge, the formation of iron-rich microcrystalline layer silicates is to be expected. Montmorillonite in contact with alkaline cement pore-waters reacts to form zeolites. This alteration is linked with a volume increase and a loss of plasticity. (author) 127 refs., 31 figs., 4 tabs

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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/sup 3/ ml/g for europium; (2 to 40) x 10/sup 3/ ml/g for plutonium(IV); and (4 to 16) x 10/sup 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/sub 4//sup -/) sorbed on activated charcoal with K/sub d/ values in the range of (0.2 to 0.4) x 10/sup 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/sub 4//sup -/ anions as well.

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

    International Nuclear Information System (INIS)

    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 103 ml/g for europium; (2 to 40) x 103 ml/g for plutonium(IV); and (4 to 16) x 103 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 (TcO4-) sorbed on activated charcoal with K/sub d/ values in the range of (0.2 to 0.4) x 103 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 TcO4- anions as well

  14. Design and application of solid, dense backfill advanced mining technology with two pre-driving entries

    Institute of Scientific and Technical Information of China (English)

    Zhang Qiang; Zhang Jixiong; Guo Shuai; Gao Rui; Li Weikang

    2015-01-01

    New solid backfill mining technology provides unique technical advantages for‘three-under’ coal min-ing which refers to coal resources trapped under buildings, railways, and water bodies. This technology has a much higher recovery rate and can effectively control the surface subsidence. However, successful application of this technology depends heavily on geological conditions. To avoid the disadvantages asso-ciated with downward mining and overhead backfilling with this new technology, a new advanced solid backfill mining design with two pre-driving entries is proposed here to ensure the backfill effect. Taking Huayuan coal mine as an example, this paper tests the double gob-side entries retaining with no pillar left scheme and optimizes an integrated technology setup for backfill mining and gob-side entry retain-ing. Field applications show that the recovery rate increased from 40%for strip mining to 85%for backfill mining. Moreover, the new backfill technology allowed for better control over the surrounding rock deformation caused by the gob-side entry retaining effect and better control of ground subsidence as compared to strip mining.

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

    International Nuclear Information System (INIS)

    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 m3 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

  16. Research on U-steel yieldable support with backfill technology in rock roadway

    Institute of Scientific and Technical Information of China (English)

    LUO Yong; CHANG Ju-cai

    2009-01-01

    The loading on U-steel yieldable support cannot be organically combined with the law of strata behaviors from the surrounding rocks of roadway. In order to effectively solve the problem, U-steel yieldable support with backfill material and the performance requirements of backfill material were analyzed on the basis of structural mechanics. The mechanical properties of backfill material selected were tested in the laboratory, and the test results show that the ratio of the backfill material complies with the requirements of backfill technology; it can effectively optimize the relationship between the support and the surrounding rock, and the filling layer can avoid the partial stress concentration and fully improve the support performance. Compared with U-steel yieldable support with gangue filling, the filed application shows that the supporting result of U-steel yieldable support with backfill technology is satisfactory, the stress on U-steel yieldable support with backfill technology decreases greatly and distributes uniformly, convergence of the surrounding rock of roadway is decreased by more than 50%, and the surrounding rocks of roadway are controlled effectively.

  17. Research on U-steel yieldable support with backfill technology in rock roadway

    Energy Technology Data Exchange (ETDEWEB)

    Yong Luo; Ju-cai Chang [Huainan Mining Group Co. Ltd., Huainan (China). Postdoctoral Scientific Research Station

    2009-12-15

    The loading on U-steel yieldable support cannot be organically combined with the law of strata behaviors from the surrounding rocks of roadway. In order to effectively solve the problem, U-steel yieldable support with backfill material and the performance requirements of backfill material were analyzed on the basis of structural mechanics. The mechanical properties of backfill material selected were tested in the laboratory, and the test results show that the ratio of the backfill material complies with the requirements of backfill technology; it can effectively optimize the relationship between the support and the surrounding rock, and the filling layer can avoid the partial stress concentration and fully improve the support performance. Compared with U-steel yieldable support with gangue filling, the filed application shows that the supporting result of U-steel yieldable support with backfill technology is satisfactory, the stress on U-steel yieldable support with backfill technology decreases greatly and distributes uniformly, convergence of the surrounding rock of roadway is decreased by more than 50%, and the surrounding rocks of roadway are controlled effectively.

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

    International Nuclear Information System (INIS)

    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/cm3, was determined to be 0.9 x 10-18 m2 in liquid water at 25 and 2000C, 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

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

    International Nuclear Information System (INIS)

    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

  20. Realizing of Optimization of Binder Backfill Material Under Certain Strength with Fuzzy Sets

    Institute of Scientific and Technical Information of China (English)

    崔明义; 胡华

    2001-01-01

    The main factors deciding the compressive strength of binder backfill body are tailing density and binder dosage in binder backfill materials. Based on the antecedent of certain pulp density, the method of increasing the tailing density and reducing the binder dosage, or the manner of cutting down the tailing density and gaining the binder dosage are taken to guarantee the strength of backfill body. The problem that should be solved is how to determine the tailing density and the binder dosage rationally. This paper tries to realize the correct selection of the tailing density and the binder dosage in computer with the method of fuzzy mathematics.

  1. Evaluation of using synthetic zeolite as a backfill material in radioactive waste disposal facility

    International Nuclear Information System (INIS)

    The fundamental safety concept for the disposal of radioactive wastes is to isolate the waste from the accessible environment for a period sufficiently long to allow substantial decay of the radionuclides and to limit release of residual radionuclides into the accessible environment. The underground disposal of radioactive waste is based upon a multi barrier concept. Backfill material is an important component of a multi-barrier disposal facility for low and intermediate level radioactive wastes. For long-term performance assessment of radioactive repositories, knowledge concerning the migration of radionuclides in the backfill material is required. Radionuclide migration through porous media (backfill materials) is governed by diffusion, advection, dispersion, retardation, and radionuclide decay. The work presented in this thesis is an examination of the feasibility of using synthetic zeolite NaA-X blend prepared from fly ash (FA) as backfill material in the proposed radioactive waste disposal facility in Egypt. The migration behavior of cesium and strontium ions, as two of the most important radionuclides commonly encountered in the Egyptian waste streams, through the proposed backfill material is studied using mathematical models. This approach considers the advective and dispersive transport of solutes dissolved in groundwater, which may undergo linear sorption (i.e retardation) and simple first order decay. To achieve these goals, the following investigations were carried out:1- Review of the materials most commonly used as engineered backfill to identify the important features to be considered in the examination of the proposed backfill material (zeolite Na A-X blend).2- Sorption experimental investigation aimed to study the sorption properties of the candidate backfill material towards the concerned radionuclides, cesium and strontium. Such studies are performed to establish clear understanding of the principle factors that control the sorption process, i

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

    International Nuclear Information System (INIS)

    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

  3. Use of cemented paste backfill in arsenic-rich tailings

    Science.gov (United States)

    Hamberg, Roger; Maurice, Christian; Alakangas, Lena

    2015-04-01

    Gold is extracted by cyanide leaching from inclusions in arsenopyrite from a mine in the north of Sweden. The major ore mineral assemblage consists of pyrrhotite and arsenopyrite-loellingite. Effluents from the gold extraction were treated with Fe2(SO4)3, with the aim to form stable As-bearing Fe-precipitates (FEP). The use of the method called cemented paste backfill (CPB) is sometimes suggested for the management of tailings. In CPB, tailings are commonly mixed with low proportions (3 - 7 %) of cement and backfilled into underground excavated area. To reduce costs, amendments such as granulated blast furnace slag (GBFS), biofuel fly ash (BFA) and cement kiln dust (CKD) are used for partial replacement of cement in CPB due to their pozzolanic and alkaline properties. The objective for this study was to evaluate the leaching behaviour of As in CPB-mixtures with low proportions (1 - 3 %) of BFA and ordinary cement and unmodified tailings. The selection of CPB-recipies was made based on technical and economical criterias to adress the demands deriving from the mining operations. Speciation of the As in ore and tailings samples revealed that mining processes have dissolved the majority of the arsenopyrite in the ore, causing secondary As phases to co-precipitate with newly formed FEP:s. Tank leaching tests (TLT) and weathering cells (WCT) were used to compare leaching behaviour in a monolithic mass contra a crushed material. Quantification of the presumed benefit of CPB was made by calculation of the cumulative leaching of As. Results from the leaching tests (TLT and WCT) showed that the inclusion of As-rich tailings into a cementitious matrix increased leaching of As. This behaviour could partially be explained by an increase of pH. The addition of alkaline binder materials to tailings increased As leaching due to the relocation of desorbed As from FEPs into less acid-tolerant species such as Ca-arsenates and cementitious As-phases. Unmodified tailings generated an

  4. Thermo-Hydraulic Modelling of Buffer and Backfill

    International Nuclear Information System (INIS)

    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. CODEBRIGHT 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

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

    International Nuclear Information System (INIS)

    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

  6. Method for the determination of the retention capacity of backfill materials and seals for gaseous radionuclides

    International Nuclear Information System (INIS)

    With the aid of radioindicator technology, the retention capacity of two backfill materials (iron ore and country rock) for the gases CH4, CO, CO2 (all 14C), HT, HTO, 131I2, CH3131I, 85Kr and 222Rn and was determined by performing fixed bed column experiments. In the experiments, iodine was converted to iodide and bound to the backfill materials obtained from the Konrad mine (R > 3x104). HTO and 14CO2 passed through the backfill material bed with a time delay. The other indicators showed no interaction with the backfill material. In addition to the retardation factors (R), the effective diffusion coefficients (D) were also determined. For all indicators, this value was in the range 0.16 cm2/s to 0.42 cm2/s. With 10 refs., 9 tabs., 4 figs

  7. 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

  8. REQUIREMENT OF FLUIDITY OF HIGH WATER CONTENT MATERIALS FORTHE GETWAY-SIDE BACKFILLING TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    QiTaiyue; MaNianjie

    1996-01-01

    Through analyzing the effects of water consumption, diameter of solid particle, and flow velocity on the fluidity of high water content material slurry, the relationship among the fluidity, the isotropy of the slurry, and the pumping facilities applied in getway-side backfilling has been found. And the requirment of fluidity of high water content material for the design of getway-side backfilling technique is put forward in the paper.

  9. Experimental and Numerical Modeling of Seismic Earth Pressures on Retaining Walls with Cohesive Backfills

    OpenAIRE

    CANDIA, GABRIEL ALFONSO

    2013-01-01

    Observations from recent earthquakes show that all types of retaining structures with non-liquefiable backfills perform very well and there is limited evidence of damage or failures related to seismic earth pressures. Even retaining structures designed only for static loading have performed well during strong ground motions suggesting that special seismic design provisions may not be required in some cases. The objective of this study was to characterize the seismic interaction of backfill-wa...

  10. Effects of bituminous layer as backfill material on mechanical behavior in tunnel model

    OpenAIRE

    Moriyoshi, Akihiro; Takano, Shin-ei; Urata, Hiroyuki; Suzuki, Tetsuya; Yoshida, Takaki

    2001-01-01

    This paper describes the effects of bituminous material as a backfill material on mechanical behavior in model tunnel in laboratory. It is known that load spreading and relaxation of bituminous material are good properties. Then if we use bituminous material as a backfill material of tunnel, the tunnel will have waterproof, good load spreading property. We used new bituminous material (Aquaphalt) which can solidify in water. We conducted relaxation test in tension for new bituminous mat...

  11. Rheological Properties of Cemented Tailing Backfill and the Construction of a Prediction Model

    OpenAIRE

    Liu Lang; KI-IL Song; Dezheng Lao; Tae-Hyuk Kwon

    2015-01-01

    Workability is a key performance criterion for mining cemented tailing backfill, which should be defined in terms of rheological parameters such as yield stress and plastic viscosity. Cemented tailing backfill is basically composed of mill tailings, Portland cement, or blended cement with supplementary cement material (fly ash and blast furnace slag) and water, among others, and it is important to characterize relationships between paste components and rheological properties to optimize the w...

  12. Dessicant materials screening for backfill in a salt repository

    International Nuclear Information System (INIS)

    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 CO2 in air to form CaCO3 and release the hydrated water. Thus the intimate mixture of CaO and MgO from calcined dolomite may serve as a desiccant and remove CO2 from the repository atmosphere

  13. 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.

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

    International Nuclear Information System (INIS)

    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

  15. 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

  16. 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)

    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

  17. 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

  18. 2D and 3D finite element analysis of buffer-backfill interaction

    International Nuclear Information System (INIS)

    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/m3. 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 3D

  19. 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

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

    International Nuclear Information System (INIS)

    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's ability to

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

    International Nuclear Information System (INIS)

    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.)

  2. Vertical transportation system of solid material for backfilling coal mining technology

    Institute of Scientific and Technical Information of China (English)

    Ju Feng; Zhang Jixiong; Zhang Qiang

    2012-01-01

    For transportation of solid backfill material such as waste and fly ash from the surface to the bottom of the shaft in a fully mechanized backfilling coal backfilling coal mining technology,we developed a new vertical transportation system to transport this type of solid backfill material.Given the demands imposed on safely in feeding this material,we also investigated the structure and basic parameter of this system.For a mine in the Xingtai mining area the results show that:(1) a vertical transportation system should include three main parts,i.e.,a feeding borehole,a maintenance chamber and a storage silo; (2) we determined that 486 mm is a suitable diameter for bore holes,the diameter of the storage silo is 6 m and its height 30 m in this vertical transportation system; (3) a conical buffer was developed to absorb the impact during the feeding process.To ensure normal implementation of fully mechanized backfilling coal mining technology and the safety of underground personnel,we propose a series of security technologies for anti-blockage,storage silo cleaning.high pressure air release and aspiration.This vertical transporting system has been applied in one this particular mine,which has fed about 4 million tons solid material with a feeding depth of 350 m and safely exploited 3 million tons of coal.

  3. Mechanical analyses of WIPP disposal rooms backfilled with either crushed salt or crushed salt-bentonite

    International Nuclear Information System (INIS)

    In this paper numerical calculations of disposal room configurations at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, NM are presented. Specifically, the behavior of either crushed salt or a crushed salt- bentonite mixture, when used as a backfill material in disposal rooms, is modeled in conjunction with the creep behavior of the surrounding intact salt. The backfill consolidation model developed at Sandia National Laboratories was implemented into the SPECTROM-32 finite element program. This model includes nonlinear elastic as well as deviatoric and volumetric creep components. Parameters for the models were determined from laboratory tests with deviatoric and hydrostatic loadings. The performance of the intact salt creep model previously implemented into SPECTROM-32 is well documented. Results from the SPECTROM-32 analyses were compared to a similar study conducted by Sandia National Laboratories using the SANCHO finite element program. The calculated deformations and stresses from the SPECTROM-32 and SANCHO analyses agree reasonably well despite differences in constitutive models and modeling methodology. These results provide estimates of the backfill consolidation through time. The trends in the backfill consolidation can then be used to estimate the permeability of the backfill and subsequent radionuclide transport

  4. 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

  5. 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)

    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

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

    International Nuclear Information System (INIS)

    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

  7. Testing of candidate waste-package backfill and canister materials for basalt

    International Nuclear Information System (INIS)

    The Basalt Waste Isolation Project (BWIP) is developing a multiple-barrier waste package to contain high-level nuclear waste as part of an overall system (e.g., waste package, repository sealing system, and host rock) designed to isolate the waste in a repository located in basalt beneath the Hanford Site, Richland, Washington. The three basic components of the waste package are the waste form, the canister, and the backfill. An extensive testing program is under way to determine the chemical, physical, and mechanical properties of potential canister and backfill materials. The data derived from this testing program will be used to recommend those materials that most adequately perform the functions assigned to the canister and backfill

  8. Identification and evaluation of appropriate backfills for the Waste Isolation Pilot Plant (WIPP)

    International Nuclear Information System (INIS)

    A backfill system has been designed for the Waste Isolation Pilot Plant (WIPP) which will control the chemical environment of the post-closure repository to a domain where the actinide solubility is within its lowest region. The actinide solubility is highly dependent on the chemical species which constitute the fluid, the resulting pH of the fluid, and the oxidation state of the actinide which is stable under the specific conditions. The use of magnesium oxide (MgO) has the backfill material not only controls the pH of the expected fluids, but also effectively removes carbonate from the system, which has a significant impact on actinide solubility. The backfill selection process, emplacement system design, and confirmatory experimental results are presented

  9. Research and development of buffer/backfilling material in deep geological disposal of high-level radioactive waste

    International Nuclear Information System (INIS)

    The author reviews the R and D of buffer/backfilling materials in deep geological disposal of high-level radioactive waste, and summarizes the research findings about buffer/backfilling material's properties including water permeability, heat property, swelling property. The direction for the future study of this field is pointed out

  10. Roadway backfill method to prevent geo-hazards induced by room and pillar mining: a case study in Changxing coal mine, China

    OpenAIRE

    Zhang, Jixiong; Li, Meng; Zhou, Nan; Gao, Rui

    2016-01-01

    Coal mines in the western areas of China experience low mining rates and induce many geo-hazards when using the room and pillar mining method. In this research, we proposed a roadway backfill method during longwall mining to target these problems. We tested the mechanical properties of the backfill materials to determine a reasonable ratio of backfill materials for the driving roadway during longwall mining. We also introduced the roadway layout and the backfill mining technique required for ...

  11. 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

  12. Fluid transport along gutta-percha backfills with and without sealer

    NARCIS (Netherlands)

    Wu, MK; van der Sluis, LWM; Wesselink, PR

    2004-01-01

    Objective. The use of heat may influence the sealing ability of sealer. The aim of this study was to compare the fluid transport along the gutta-percha backfill portion when different sealers were used or no sealer at all. Study design. Four groups consisting of the roots of maxillary and mandibular

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

  15. 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.

  16. Evaluation of the effect of sodium silicate addition to mine backfill, Gelfill L Part 1

    Institute of Scientific and Technical Information of China (English)

    M. Kermani; F.P. Hassani; E. Aflaki; M. Benzaazoua; M. Nokken

    2015-01-01

    In this paper, the mechanical properties of sodium silicate-fortified backfill, called Gelfill, were investi-gated 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 me-chanical 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.

  17. 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...

  18. 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 to a...

  19. Radiocolloid migration through backfill-surrounding porous media in semi-infinite cylindrical geometry

    International Nuclear Information System (INIS)

    Numerical simulation of radionuclide migration as a form of colloid in two dimentional cylindrical geometry were conducted. Due to the relatively strong filtration phenomena in backfill material of waste repository, colloid concentrations decay out very rapidly along the geosphere. Inside the backfill material, diffusional transport of radiocolloid is known to be relatively dominant than that of advection. The flow conditions of the waste repository groundwater can be represented with a dimensionless Peclet number. If the Peclet number is lower than 2, which means diffusion is dominant transport mechanism, general Finite Difference Method (FDM) cannot predict the migration behavior of the colloid exactly due to the numerical error. Instead, so called Central Difference Method (CDM) is applicable for the low Peclet number problems. outside the backfill media, where advection is the controlling transport process with Peclet number being greater than 2, the upwind numerical scheme would be a powerful tool. Most of the experiments simulating the radionuclide migration were conducted at high flow conditions, and the theoretical modelling about the experiments typically neglected the role of the diffusion in filtration mechanism. In this paper the two-dimensional CDM scheme and CDM-upwind scheme are developed to describe radio-colloid migration in two-dimensional porous media using potential flow theorem. Then the mass fluxes at a given position inside the backfill are predicted

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Gopala, Vinay Ramohalli, E-mail: gopala@nrg.eu [Nuclear Research and consultancy Group (NRG), P.O. Box 25, 1755 ZG Petten (Netherlands); Lycklama a Nijeholt, Jan-Aiso [Nuclear Research and consultancy Group (NRG), P.O. Box 25, 1755 ZG Petten (Netherlands); Bakker, Paul [Van Hattum en Blankevoort, Woerden (Netherlands); Haverkate, Benno [Nuclear Research and consultancy Group (NRG), P.O. Box 25, 1755 ZG Petten (Netherlands)

    2011-07-15

    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 dynamics

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

    International Nuclear Information System (INIS)

    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

  3. 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)

    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 (Krock = 10-13 m/s), while the influence is low if the rock is rather wet (Krock = 10-12 m/s). At Krock = 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 saturation in

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Rheological Properties of Cemented Tailing Backfill and the Construction of a Prediction Model

    Directory of Open Access Journals (Sweden)

    Liu Lang

    2015-04-01

    Full Text Available Workability is a key performance criterion for mining cemented tailing backfill, which should be defined in terms of rheological parameters such as yield stress and plastic viscosity. Cemented tailing backfill is basically composed of mill tailings, Portland cement, or blended cement with supplementary cement material (fly ash and blast furnace slag and water, among others, and it is important to characterize relationships between paste components and rheological properties to optimize the workability of cemented tailing backfill. This study proposes a combined model for predicting rheological parameters of cemented tailing backfill based on a principal component analysis (PCA and a back-propagation (BP neural network. By analyzing experimental data on mix proportions and rheological parameters of cemented tailing backfill to determine the nonlinear relationships between rheological parameters (i.e., yield stress and viscosity and mix proportions (i.e., solid concentrations, the tailing/cement ratio, the specific weight, and the slump, the study constructs a prediction model. The advantages of the combined model were as follows: First, through the PCA, original multiple variables were represented by two principal components (PCs, thereby leading to a 50% decrease in input parameters in the BP neural network model, which covered 98.634% of the original data. Second, in comparison to conventional BP neural network models, the proposed model featured a simpler network architecture, a faster training speed, and more satisfactory prediction performance. According to the test results, any error between estimated and expected output values from the combined prediction model based on the PCA and the BP neural network was within 5%, reflecting a remarkable improvement over results for BP neural network models with no PCA.

  8. Paste-like self-flowing transportation backfilling technology based on coal gangue

    Institute of Scientific and Technical Information of China (English)

    WANG Xin-min; ZHAO Bin; ZHANG Chuan-shu; ZHANG Qin-li

    2009-01-01

    A paste-like self-flowing pipeline transportation backfilling technology with coal gangue as aggregate is proposed to remove the potential damage caused by coal gangue piles. As well, the difficult problems of recovering high quality safety coal pillars and deep mining of the Suncun Coal Mine (SCM), Xinwen Coal Group, Shandong are resolved. The physical-chemical properties of coal gangue, optimized proportion of materials, backfilling system and craft in the SCM were studied in the laboratory and then an industrial test was carried out on high quality coal pillars under a town. The results show that finely crushed kaolinized and fresh gangue with granularity less than 5 mm can be used as aggregate with fly ash to replace part of the cement and a compos-ite water reducer as an additive, accounting for 1.0%-1.5% of the total amount of cement and fly ash. The recommended proportion is I(cement):4(fly ash): 15(coal gangue), with a mass fraction of 72%-75%, theological paste-like properties and a strength of more than 0.7 MPa at 7 d. The sequence of adding cement, fly ash, water reducer and then coal gangue ensures that the suspended state of the slurry, reducing the wear and jam of pipelines. The working face is advancing continuously by the alternating craft of building block walls with coal gangue and backfilling mined-out gobs with paste-like slurry. The recovery rate is as high as 90% with a backfilling cost of 36.9 Yuan/t, good utilization of coal gangue and no subsidence on the surface. This technology provides a good theoretical basis and application experience for coal mines, cement backfilling with paste-like slurry.

  9. Paste-like self-flowing transportation backfilling technology based on coal gangue

    Energy Technology Data Exchange (ETDEWEB)

    Xin-min Wang; Bin Zhao; Chuan-shu Zhang; Qin-li Zhang [Central South University, Changsha (China). School of Resources and Safety Engineering

    2009-03-15

    A paste-like self-flowing pipeline transportation backfilling technology with coal gangue as aggregate is proposed to remove the potential damage caused by coal gangue piles. As well, the difficult problems of recovering high quality safety coal pillars and deep mining of the Suncun Coal Mine (SCM), Xinwen Coal Group, Shandong are resolved. The physical-chemical properties of coal gangue, optimized proportion of materials, backfilling system and craft in the SCM were studied in the laboratory and then an industrial test was carried out on high quality coal pillars under a town. The results show that finely crushed kaolinized and fresh gangue with granularity less than 5 mm can be used as aggregate with fly ash to replace part of the cement and a composite water reducer as an additive, accounting for 1.0%-1.5% of the total amount of cement and fly ash. The recommended proportion is 1(cement):4(fly ash):15(coal gangue), with a mass fraction of 72%-75%, rheological paste-like properties and a strength of more than 0.7 MPa at 7 d. The sequence of adding cement, fly ash, water reducer and then coal gangue ensures that the suspended state of the slurry, reducing the wear and jam of pipelines. The working face is advancing continuously by the alternating craft of building block walls with coal gangue and backfilling mined-out gobs with paste-like slurry. The recovery rate is as high as 90% with a backfilling cost of 36.9 Yuan/t, good utilization of coal gangue and no subsidence on the surface. This technology provides a good theoretical basis and application experience for coal mines, cement backfilling with paste-like slurry. 17 refs., 6 figs., 3 tabs.

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

    International Nuclear Information System (INIS)

    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.

  11. 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.

  12. Determination of internal pressure and the backfill gas composition of nuclear fuel rods

    International Nuclear Information System (INIS)

    An important consideration in the nuclear fuel manufacturing is the measurement of the helium atmosphere pressure and its composition analysis inside the nuclear fuel rod. In this work it is presented a system used to measure the internal pressure and to determine the backfill gas composition of fuel rods. The system is composed of an expansion chamber provided of a seals system to assure that when rod is drilled, the gas stays contained inside the expansion chamber. The system is connected to a pressure measurement digital system: Baratron MKS 310-AHS-1000. Range 1000 mm Hg from which the pressure readings are taken when this is stabilized in all the system. After a gas sample is sent toward a Perkin Elmer gas chromatograph, model 8410 with thermal conductivity detector to get the corresponding chromatogram and doing the necessary calculations for obtaining the backfill gas composition of the rod in matter. (Author)

  13. Backfill as an engineered barrier for nuclear waste management. [Bentonite-hectorite

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, E.J.

    1979-01-01

    The swelling, plastic flow, and relative impermeability of bentonite and hectorite were observed and measured after wetting with concentrated brines. Measurements of stable values of pH > 6.5 for the interstitial brines in wetted bentonite and hectorite confirmed conditions favorable for precipitation and sorption of transuranics. Values of K/sub d/ > 2000 ml/g were measured for Pu and Am. Calculated estimates of the effectiveness of a one-foot-thick backfill barrier are presented. They show that the breakthrough of Pu and other transuranics (K/sub d/ = 2000 ml/g) can be delayed for 10/sup 4/ to 10/sup 5/ years. The breakthrough of most fission products (K/sub d/ = 200 ml/g) can be delayed for 10/sup 3/ to 10/sup 4/ years, sufficient time for them to decay to very low concentrations. A backfill barrier can contribute significantly to a radioactive waste isolation system.

  14. A mathematical model of the behaviour of concrete backfill in an underground waste repository

    International Nuclear Information System (INIS)

    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 sealing of underground repositories for radioactive waste. The present study 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 finite element material model developed accounts for the ageing of concrete, multi-axial creep and creep recovery, the effect of external environmental humidity and changing internal temperatures. The model compares favourably with available published experimental data for maturing concrete but requires considerable further validation against a wider range of experimental results. (author)

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

    International Nuclear Information System (INIS)

    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 of

  16. Implementation of chemical controls through a backfill system for the Waste Isolation Pilot Plant (WIPP)

    International Nuclear Information System (INIS)

    A backfill system has been designed for the WIPP which will control the chemical environment of the post-closure repository to a domain where the actinide solubility is within its lowest region. The actinide solubility is highly dependent on the chemical species which constitute the fluid, the resulting pH of the fluid, and oxidation state of the actinide which is stable under the specific conditions. The implementation of magnesium oxide (MgO) as the backfill material not only controls the pH of the expected fluids but also effectively removes the carbonate from the system, which has a significant impact for actinide solubility. The selection process, emplacement system, design, and confirmatory experimental results are presented

  17. Multiple determinations of isotope diffusion in cementitious backfills and Ordinary Portland Cement (OPC) monoliths

    International Nuclear Information System (INIS)

    The full text of publication follows: The UK concept for geological disposal of intermediate level (ILW) and low level waste (LLW) includes backfill materials based on admixtures of Ordinary Portland Cement (OPC). It is expected that the evolution of these backfill materials will generate high pH conditions and the corrosion of the metal canisters used for disposal will promote a low Eh environment. This combination of conditions within the near field of the Geological Disposal Facility (GDF) will reduce the solubility of many radionuclides and retard migration. In addition, sorption to some of the cementitious phases may contribute significantly to the retardation of many radionuclides. It is clearly important to understand how diffusion of radionuclides contributes to the overall migration from the repository. However, it remains practically difficult to isolate the effect of diffusion from other processes such as sorption and advection which may also occur in the near field and far fields of the GDF. This presentation describes a series of experiments undertaken to evaluate the diffusion of a selection of relevant radionuclides in saturated backfills (including the NIREX reference vault backfill, NRVB) and OPC matrices. The experiments build upon a significant number of related sorption studies previously undertaken by the radiochemistry group at Loughborough University and complement a series of small scale advection experiments also being undertaken. The experimental technique uses small pre-cast blocks (monoliths) of the matrix under investigation. An appropriate concentration of the isotope of interest is introduced in a cavity in the centre of the block, which is then sealed, and finally, placed in a solution previously equilibrated with the matrix. The increase in concentration of the isotope in the external solution is then determined at defined time intervals. The interpretation of the results is undertaken with methods conventionally used for geological

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

    OpenAIRE

    TERZİ, Niyazi Uğur; Sönmez YILDIRIM

    2009-01-01

    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 transdu...

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

    International Nuclear Information System (INIS)

    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

  20. Retardation of radionuclides in back-fill materials of TVO VLJ repository and in rocks

    International Nuclear Information System (INIS)

    Retardation and diffusion in rock and rock-bentonite back-fill of the following reactor waste elements are reviewed: carbon, cobalt, nickel, strontium, technetium, iodine, cesium, plutonium and americium. Such conservative values for distribution coefficients and diffusion coefficients are proposed for the use in safety assessment of the final disposal of the waste that they lead to overestimations in biosphere radiation doses. Also more realistic values are proposed

  1. Theoretical study of backfilling trenches bulldozer equipped with a screw intensifier

    OpenAIRE

    de Krol, R. van

    2015-01-01

    The advantages of a bulldozer with a screw intensifier when the backfilling of trenches, compared with the traditional method of filling. Shows cross-sectional shapes of the soil in the inter-track space screw intensifier and formulas for their determination. Given the method of determining the angular velocity of the screw in the intensifier nezabivanii dump coil and balancing the soil is above the auger intensifier.

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

    International Nuclear Information System (INIS)

    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

  3. Performance of concrete backfilling materials for shafts and tunnels in rock formations. Volume 2: mathematical modelling

    International Nuclear Information System (INIS)

    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 or Intermediate Level Wastes with long lived isotopes. The 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

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

    International Nuclear Information System (INIS)

    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

  5. Magnetic responses to traffic related contamination recorded by backfills: A case study from Tongling City, China

    Science.gov (United States)

    Ma, M. M.; Hu, S. Y.; Lin, H.; Cao, L. W.; Wang, L. S.

    2014-08-01

    With the development of urbanization and industrialization, traffic is creating a serious contamination problem. Conventional methods for contamination testing are generally expensive and time-consuming, while magnetic methods have been suggested to be an economic and non-destructive alternative. In this study, we measured magnetic properties and heavy metal contents in backfills along an urban road side in China, in situ on surface and on samples in vertical sections. Magnetic results and SEM images show the dominance of coarse magnetite, supposed to origin from human activities. Furthermore, there is an obvious decreasing trend of magnetic susceptibility (χ) and several heavy metals (Cu, Mn, Zn, Pb) with increasing distance from the road edge, symmetrically at both road sides, indicating that this is a typical traffic-related contamination signal. The detailed distribution patterns of χ and heavy metals exhibit slight variations in the surface data, probably due to the local topography and surface runoff due to rainfall. In vertical soil cores magnetic parameters show significant positive relationships (r = 0.88-0.99) with concentrations of heavy metals (Cu, Zn, Pb, Fe). Our results suggest that backfills unaffected by the traffic contamination signal and characterized by low χ value can be chosen for contamination monitoring. Despite the complex nature of backfills and the possibility of contamination prior to their transportation to the site, they are especially important for areas where undisturbed soil is not available.

  6. Development of a quantitative accelerated sulphate attack test for mine backfill

    Science.gov (United States)

    Shnorhokian, Shahe

    Mining operations produce large amounts of tailings that are either disposed of in surface impoundments or used in the production of backfill to be placed underground. Their mineralogy is determined by the local geology, and it is not uncommon to come across tailings with a relatively high sulphide mineral content, including pyrite and pyrrhotite. Sulphides oxidize in the presence of oxygen and water to produce sulphate and acidity. In the concrete industry, sulphate is known to produce detrimental effects by reacting with the cement paste to produce the minerals ettringite and gypsum. Because mine backfill uses tailings and binders---including cement---it is therefore prone to sulphate attack where the required conditions are met. Currently, laboratory tests on mine backfill mostly measure mechanical properties such as strength parameters, and the study of the chemical aspects is restricted to the impact of tailings on the environment. The potential of sulphate attack in mine backfill has not been studied at length, and no tests are conducted on binders used in backfill for their resistance to attack. Current ASTM guidelines for sulphate attack tests have been deemed inadequate by several authors due to their measurement of only expansion as an indicator of attack. Furthermore, the tests take too long to perform or are restricted to cement mortars only, and not to mixed binders that include pozzolans. Based on these, an accelerated test for sulphate attack was developed in this work through modifying and compiling procedures that had been suggested by different authors. Small cubes of two different binders were fully immersed in daily-monitored sodium sulphate and sulphuric acid solutions for a total of 28 days, after 7 days of accelerated curing at 50°C. In addition, four binders were partially immersed in the same solutions for 8 days for an accelerated attack process. The two procedures were conducted in tandem with leach tests using a mixed solution of

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

    International Nuclear Information System (INIS)

    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. Analysis on Backfill Mining of “Under Three” Coal in Zhouyuanshan Mine and Strata Movement Law

    Directory of Open Access Journals (Sweden)

    Weijian Yu

    2013-09-01

    Full Text Available In order to solve the problem of "under three" (under railways, buildings and water bodies coal pillar mining, analysis on backfill mining and strata movement law is carried on in 24 mining district of Zhouyuanshan coal mine. First of all, according to the engineering geology and strata occurrence condition in 24 mining district of Zhouyuanshan coal mine, FLAC2D software be used to establish a two-dimensional numerical model and to analyze and calculate the full caving method, strip method and backfill method and then gaining that backfill mining method is beneficial to improve the protection level of surface buildings and facilities. Then, using the theory of strata control and method of related mechanics to analyze the strata movement law and strata control principle of backfill mining, considering that supporting role of backfill body is mainly on lateral reinforcement of coal pillar and vertical supporting role of overlying strata, forming a cooperative control system of "bearing strata + coal pillar + backfill body" and deducing the equilibrium equations when it is in steady state. At last, using the numerical analysis method, respectively analyzing the surface subsidence of the corresponding important buildings of the three profiles of C-8 exploration line ,C-6 exploration line and A-A (cross section of the profile of C-8 exploration line after using backfill coal mining in 24 mining district. The results show that: the surface subsidence and horizontal deformation basically control within 30 mm and the surface deformation curvature of buildings generally in 0.1×10-3 /km in 24 mining district of Zhouyuanshan coal mine, which accord with the relevant standards and requirements.

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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/sup -11/ to 10/sup -5/ M and a Cs(I) concentration range of 10/sup -8/ to 10/sup -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. Transport of actinides and Tc through a bentonite backfill containing small quantities of iron or copper

    International Nuclear Information System (INIS)

    In the Swedish concept for final disposal of high-level radioactive waste, compacted bentonite has been proposed as a suitable backfill. The apparent diffusivity (Da) of the actinides U, Pu, Np and the fission product Tc in compacted bentonite mixed with 1% Fe(0), Fe(II), Cu(0) or Cu(II) has been measured in an inert nitrogen atmosphere. The results indicate, especially in the case of Fe(0) or Fe(II), reduction from the higher oxidation state Np(V), U(VI) and Tc(VII) probably to Np(IV), U(IV) and Tc(IV). (orig.)

  12. Chemistry and performance of blended cements and backfills for use in radioactive waste disposal

    International Nuclear Information System (INIS)

    The ability of NaCl and MgSO4 to impair the performance of Portland cement, blended cements containing slag and fly ash and of a permeable backfill have been measured. Performance is determined by decrease in pH, changes in mineralogy and loss of physical coherence. Experiments have been made at 25, 55 and 85 C and extensively backed up by chemical models of cement performance. NaCl, up to 1.5M, has a comparatively slight impact on performance but MgSO4 rapidly and almost quantitatively reacts, lowering system pH''s to 2 and magnesium silicates with gypsum

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

    International Nuclear Information System (INIS)

    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 an

  14. 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.

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

    International Nuclear Information System (INIS)

    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

  16. Backfill Mining Technology and Development Tendency in China Coal Mine%我国煤矿充填开采技术及其发展趋势

    Institute of Scientific and Technical Information of China (English)

    胡炳南

    2012-01-01

    Based on the requirements of the sustainable development and environment protection, the paper stated the necessity of the backfill mining in mine. With the collection and analysis on the application of 20 typical backfill mining faces in China, the paper systematically stated the technical features and suitable conditions of the mine roadway heading with the rejects backfill, conventional longwall mining with the rejects backfill, fully mechanized longwall coal mining with rejects backfill, high water material backfill and others. The solid rejects backfill of mine roadway heading is suitale for minor output and important protected buildings places. The longwall fully mech- anized mining with solid rejects and paste backfill is saitable for the meohanized coal mining and conventional mining under the protected buildings places. The high water backfill materia is suitable for the mine with shortage of backfill material and a single seam. The coal pro- duction, backfill value, coal recovery rate, cost per ton of coal, backfill rate, convergence value, subsidence value, subsidence reduction rate, deformation value and protected area were provide as the evaluation indexes of the backfill mining effect. Finally, a fruther study should be conducted on high efficient backfill mining, backfill space sealing and others.%基于煤矿可持续发展与环境保护的要求,阐述了煤矿充填开采的必要性,通过收集分析我国20个典型充填开采应用实例,系统论述了巷道掘进抛矸充填、长壁普采矸石充填、长壁综采矸石充填、膏体充填和高水充填等技术特点,得出了巷道掘进矸石充填适用于配采和重要保护场合,长壁综采矸石和膏体充填适用于主采和普通保护场合,高水充填适用于缺少充填材料和单一煤层场合;提出了采煤量、充填量、采出率、吨煤成本、充满率、移近量、下沉量、减沉率、变形量和保护面积可作为充填开采效果的评价指

  17. New approach for helium backfilling and leak testing seal-welded capsules in a hot cell

    International Nuclear Information System (INIS)

    Under the guidance of the US Department of Energy (DOE), Westinghouse Hanford Company (WHC) and Battelle's Pacific Northwest Laboratory (PNL) have undertaken a joint venture to manufacture sealed gamma sources using 137Cs in the form of 137CsCl. The gamma sources are used primarily by the medical industry for sterilization, blood and tissue irradiation, and various research applications. The energetic gamma (0.662 meV) and dispersion characteristics of the CsCl feed material pose stringent containment and shielding requirements. The PNL's shielded materials facility (SMF) located at Hanford was selected for this work because of its ability to meet those requirements. Production of the double-encapsulated 137Cs gamma sources includes preparing the feed material (sectioning, dissolution, and filtration), forming pellets, loading capsules, helium backfilling, welding, and helium leak testing. Development of the remotely operated equipment used in this process required innovative solutions to difficult problems by both WHC and PNL engineers. As a result, several new technologies were developed that have the potential for use in a variety of remote applications. Of particular interest is a new process for backfilling capsules with helium and subsequently welding and leak testing the capsules

  18. Assessment of arsenic immobilization in synthetically prepared cemented paste backfill specimens.

    Science.gov (United States)

    Coussy, Samuel; Benzaazoua, Mostafa; Blanc, Denise; Moszkowicz, Pierre; Bussière, Bruno

    2012-01-01

    Mine tailings coming from the exploitation of sulphide and/or gold deposits can contain significant amounts of arsenic (As), highly soluble in conditions of weathering. Open mine voids backfilling techniques are now widely practiced by modern mining companies to manage the tailings. The most common one is called cemented paste backfill (CPB), and consists of tailings mixed with low amounts of hydraulic binders (3-5%) and a high proportion of water (typically 25%). The CPB is transported through a pipe network, to be placed in the mine openings. CPB provides storage benefits and underground support during mining operations. Moreover, this technique could also enhance contaminant stabilization, by fixing the contaminants in the binder matrix. CPB composites artificially spiked with As were synthesized in laboratory, using two types of hydraulic binders: a Portland cement, and a mix of fly ash and Portland cement. After curing duration of 66 days, the CPB samples were subjected to several leaching tests in various experimental conditions in order to better understand and then predict the As geochemical behaviour within CPBs. The assessment of the As release indicates that this element is better stabilized in Portland cement-based matrices rather than fly ash-based matrices. The As mobility differs in these two matrices, mainly because of the different As-bearing minerals formed during hydration processes. However, the total As depletion does not exceed 5% at the end of the most aggressive leaching test, indicating that As is well immobilized in the two types of CPB. PMID:22054566

  19. Evaluation of Computational Method of High Reynolds Number Slurry Flow for Caverns Backfilling

    Energy Technology Data Exchange (ETDEWEB)

    Bettin, Giorgia [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-05-01

    The abandonment of salt caverns used for brining or product storage poses a significant environmental and economic risk. Risk mitigation can in part be address ed by the process of backfilling which can improve the cavern geomechanical stability and reduce the risk o f fluid loss to the environment. This study evaluate s a currently available computational tool , Barracuda, to simulate such process es as slurry flow at high Reynolds number with high particle loading . Using Barracuda software, a parametric sequence of simu lations evaluated slurry flow at Re ynolds number up to 15000 and loading up to 25%. Li mitations come into the long time required to run these simulation s due in particular to the mesh size requirement at the jet nozzle. This study has found that slurry - jet width and centerline velocities are functions of Re ynold s number and volume fractio n The solid phase was found to spread less than the water - phase with a spreading rate smaller than 1 , dependent on the volume fraction. Particle size distribution does seem to have a large influence on the jet flow development. This study constitutes a first step to understand the behavior of highly loaded slurries and their ultimate application to cavern backfilling.

  20. 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

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

  3. 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

  4. Coupled thermal-hydro analysis of unsaturated buffer and backfill in a high-level waste repository

    International Nuclear Information System (INIS)

    Highlights: • The sensitivity analysis was carried out for the thermal-hydro model parameters. • The temperature distribution was sensitive to a change in the degree of saturation. • The degree of saturation distribution was sensitive to a variation in temperature. • A coupled TH behavior in the buffer and backfill of KRS repository was analyzed. - Abstract: The buffer and backfill are the major components of an engineered barrier system (EBS) for a high level waste (HLW) repository. Reliable EBS performance assessment requires the delicate numerical modeling of the buffer and backfill. This study carried out the sensitivity analysis of thermal-hydro (TH) model parameters, and based on its results, the coupled TH analysis of an unsaturated buffer and backfill in an HLW repository. The temperature distribution was sensitive to a change in the degree of saturation and thus the thermal conductivity, and the degree of saturation distribution was sensitive to a variation in temperature and thus water viscosity. The decay heat of HLW from a canister dissipated out through the buffer and backfill into the surrounding rock. The temperature was higher closer to the canister and was lower farther from the canister. The temperature in the backfill was overall lower than that in the buffer, but both temperatures were approached slowly over a long time. The peak temperature was located at the center of the interface line between the canister and buffer, and was 107 °C at the elapsed time of 0.47 year. Re-saturation occurred in the order of the backfill and then a buffer as groundwater was intruded from the surrounding rock. The wetting of the backfill was initiated from the wall of the tunnel and the upper wall of deposition hole, and it then proceeded toward the inside. The buffer was wetted from the wall of the deposition toward the canister. The latest re-saturation location was a bit above from the center axis of the canister, at which the re-saturation period of

  5. Residual porosity and permeability of compacting salt grit backfill. REPOPERM - phase 1

    International Nuclear Information System (INIS)

    The direct disposal of spent nuclear fuel elements in BSK3 canisters in deep vertical boreholes is supposed to allow a safe long-term confinement in the host rock by backfilling of the holes using similar salt grit. The assessment of a long-term safe isolation of finally disposed radioactive wastes is usually performed using simulation models. Due to the lack of experimental data on the residual porosities of during the compacting process this issue is of increasing importance for the verification of a complete confinement within the safety concept of direct waste repositories. The Contribution covers the following topics: Determination of the state of knowledge on mechanical and hydraulic properties; development of a THMC model for a generic repository borehole; laboratory experiments with accompanying modeling calculations and planning of an in-situ experiment for complete confinement. The described investigations are the preliminary work for the subsequent project phase.

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

    International Nuclear Information System (INIS)

    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. 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

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

    International Nuclear Information System (INIS)

    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/m3. At densities less than approximately 0.9 Mg/m3 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/m3 is required to be present under fresh water or brackish porewater conditions. This density would need to be increased to approximately 0.9 Mg/m3 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.)

  9. 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.

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

    International Nuclear Information System (INIS)

    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. 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.)

  12. 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)

    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

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

    International Nuclear Information System (INIS)

    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/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

  14. Overview on backfill materials and permeable reactive barriers for nuclear waste disposal facilities.

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Robert Charles; Hasan, Ahmed Ali Mohamed; Holt, Kathleen Caroline; Hasan, Mahmoud A. (Egyptian Atomic Energy Authority, Cairo, Egypt)

    2003-10-01

    A great deal of money and effort has been spent on environmental restoration during the past several decades. Significant progress has been made on improving air quality, cleaning up and preventing leaching from dumps and landfills, and improving surface water quality. However, significant challenges still exist in all of these areas. Among the more difficult and expensive environmental problems, and often the primary factor limiting closure of contaminated sites following surface restoration, is contamination of ground water. The most common technology used for remediating ground water is surface treatment where the water is pumped to the surface, treated and pumped back into the ground or released at a nearby river or lake. Although still useful for certain remediation scenarios, the limitations of pump-and-treat technologies have recently been recognized, along with the need for innovative solutions to ground-water contamination. Even with the current challenges we face there is a strong need to create geological repository systems for dispose of radioactive wastes containing long-lived radionuclides. The potential contamination of groundwater is a major factor in selection of a radioactive waste disposal site, design of the facility, future scenarios such as human intrusion into the repository and possible need for retrieving the radioactive material, and the use of backfills designed to keep the radionuclides immobile. One of the most promising technologies for remediation of contaminated sites and design of radioactive waste repositories is the use of permeable reactive barriers (PRBs). PRBs are constructed of reactive material(s) to intercept and remove the radionuclides from the water and decontaminate the plumes in situ. The concept of PRBs is relatively simple. The reactive material(s) is placed in the subsurface between the waste or contaminated area and the groundwater. Reactive materials used thus far in practice and research include zero valent iron

  15. Overview on backfill materials and permeable reactive barriers for nuclear waste disposal facilities

    International Nuclear Information System (INIS)

    A great deal of money and effort has been spent on environmental restoration during the past several decades. Significant progress has been made on improving air quality, cleaning up and preventing leaching from dumps and landfills, and improving surface water quality. However, significant challenges still exist in all of these areas. Among the more difficult and expensive environmental problems, and often the primary factor limiting closure of contaminated sites following surface restoration, is contamination of ground water. The most common technology used for remediating ground water is surface treatment where the water is pumped to the surface, treated and pumped back into the ground or released at a nearby river or lake. Although still useful for certain remediation scenarios, the limitations of pump-and-treat technologies have recently been recognized, along with the need for innovative solutions to ground-water contamination. Even with the current challenges we face there is a strong need to create geological repository systems for dispose of radioactive wastes containing long-lived radionuclides. The potential contamination of groundwater is a major factor in selection of a radioactive waste disposal site, design of the facility, future scenarios such as human intrusion into the repository and possible need for retrieving the radioactive material, and the use of backfills designed to keep the radionuclides immobile. One of the most promising technologies for remediation of contaminated sites and design of radioactive waste repositories is the use of permeable reactive barriers (PRBs). PRBs are constructed of reactive material(s) to intercept and remove the radionuclides from the water and decontaminate the plumes in situ. The concept of PRBs is relatively simple. The reactive material(s) is placed in the subsurface between the waste or contaminated area and the groundwater. Reactive materials used thus far in practice and research include zero valent iron

  16. 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

  17. Role of a buffer component within an engineered barrier waste package and a preliminary evaluation of bentonite as a backfill material

    International Nuclear Information System (INIS)

    This paper deals with the functions, properties, and compositions of backfill components to be used in the geologic disposal of high-level nuclear waste in basalt. A conceptual design for a repository located in basalt is being developed by the Basalt Waste Isolation Project (BWIP) in which these backfill components are part of the waste package and the repository sealing system (rooms, tunnels, and shafts). The first part of the paper concerns the role of a buffer component which is located between the primary and secondary physical barriers of the waste package (the canister and overpack). The second part of the paper deals with the chemical and physical properties of bentonite, which is a primary candidate for a backfill material both in the outer backfill barrier of the waste package and in the rooms, tunnels, and shafts above the waste package

  18. 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

    OBJECTIVE: Fat metaplasia in bone marrow on T1-weighted magnetic resonance imaging (MRI) scans may develop after resolution of inflammation in patients with ankylosing spondylitis (AS) and may predict new bone formation in the spine. Similar tissue, termed backfill, may also fill areas of excavated...... bone in the sacroiliac (SI) joints and may reflect resolution of inflammation and tissue repair at sites of erosions. The purpose of this study was to test our hypothesis that SI joint ankylosis develops following repair of erosions and that tissue characterized by fat metaplasia is a key intermediary...... 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...

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

    International Nuclear Information System (INIS)

    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 experimental

  20. An experimental study on factors affecting the leachability of Cs-137 in cement matrix and leaching model with backfill

    International Nuclear Information System (INIS)

    Various factors affecting the leachability of Cs-137 in cement matrix have been investigated. Factors investigated include such as pressure curing, vibration curing, pressure leaching, the effect of the clay addition, ion-exchange resin(IRN-77) addition, and CO2 or air injection. Leaching experiments were conducted by the method recommended by IAEA. To analyze the experimental results, pore structure analysis of cement matrices was carried out by BET method. Cement matrices may not contact directly with underground water in real repository, since the surroundings of disposed drums are filled with backfill. Thus, the effect of backfill to the leachability has been investigated. The well-known diffusion theory was utilized to predict long term leach rate and cumulative fraction leached of Cs-137 or non-radioactive species. (Author)

  1. 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

  2. Analysis on Backfill Mining of “Under Three” Coal in Zhouyuanshan Mine and Strata Movement Law

    OpenAIRE

    Weijian Yu; Bo Xu; Tao Feng; Xinyuan Chen

    2013-01-01

    In order to solve the problem of "under three" (under railways, buildings and water bodies) coal pillar mining, analysis on backfill mining and strata movement law is carried on in 24 mining district of Zhouyuanshan coal mine. First of all, according to the engineering geology and strata occurrence condition in 24 mining district of Zhouyuanshan coal mine, FLAC2D software be used to establish a two-dimensional numerical model and to analyze and calculate the full caving method, strip method a...

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

    International Nuclear Information System (INIS)

    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)

  4. Deep repository - Engineered barrier system. Wetting and homogenization processes in backfill materials. Laboratory tests for evaluating modeling parameters

    International Nuclear Information System (INIS)

    SKB in Sweden and Posiva in Finland are developing and implementing similar disposal concepts for the final disposal of spent nuclear fuel. A 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 backfill materials investigated where: Asha 230B and Friedland for use as block materials and Cebogel QSE, MX-80, Minelco and Friedland for use as pellets material. The issues investigated were: 1. Homogenization processes of highly compacted backfill blocks and pellet filling during saturation. The influence of different materials and water salinity was studied. 2. Water uptake processes for different materials and different water types. Clay specimens were put in contact with water at one end and after a certain time the tests were terminated and the water content distribution determined. 3. The water retention curve was determined for the two block materials. The results of these investigations will be used for modeling purposes either directly (retention curve) or indirectly by modeling of the tests

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

    International Nuclear Information System (INIS)

    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

  6. Assessment of strength properties of cemented paste backfill by ultrasonic pulse velocity test.

    Science.gov (United States)

    Yılmaz, Tekin; Ercikdi, Bayram; Karaman, Kadir; Külekçi, Gökhan

    2014-07-01

    Ultrasonic pulse velocity (UPV) test is one of the most popular non-destructive techniques used in the assessment of the mechanical properties of concrete or rock materials. In this study, the effects of binder type/dosage, water to cement ratio (w/c) and fines content (ultrasonic pulse velocity (UPV) of cemented paste backfill (CPB) samples were investigated and correlated with the corresponding unconfined compressive strength (UCS) data. A total of 96 CPB samples prepared at different mixture properties were subjected to the UPV and UCS tests at 7, 14, 28 and 56-days of curing periods. UPV and UCS of CPB samples of ordinary Portland cement (CEM I 42.5 R) and sulphate resistant cement (SRC 32.5) initially increased rapidly, but, slowed down after 14 days. However, UPV and UCS of CPB samples of the blast furnace slag cement (CEM III/A 42.5 N) steadily increased between 7 and 56 days. Increasing binder dosage or reducing w/c ratio and fines content (<20 μm) increased the UCS and UPV of CPB samples. UPV was found to be particularly sensitive to fines content. UCS data were correlated with the corresponding UPV data. A linear relation appeared to exist between the UCS and UPV of CPB samples. These findings have demonstrated that the UPV test can be reliably used for the estimation of the strength of CPB samples. PMID:24602334

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

    International Nuclear Information System (INIS)

    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)

  8. Utilization of water-reducing admixtures in cemented paste backfill of sulphide-rich mill tailings.

    Science.gov (United States)

    Ercikdi, Bayram; Cihangir, Ferdi; Kesimal, Ayhan; Deveci, Haci; Alp, Ibrahim

    2010-07-15

    This study presents the effect of three different water-reducing admixtures (WRAs) on the rheological and mechanical properties of cemented paste backfill (CPB) samples. A 28-day strength of > or = 0.7 MPa and the maintenance of the stability (i.e. > or = 0.7 MPa) over 360 days of curing were desired as the design criteria. Ordinary Portland cement (OPC) and Portland composite cement (PCC) were used as binders at 5 wt.% dose. WRAs were initially tested to determine the dosage of a WRA for a required consistency of 7'' for CPB mixtures. A total of 192 CPB samples were then prepared using WRAs. The utilization of WRAs enhanced the flow characteristics of the CPB mixture and allowed to achieve the same consistency at a lower water-to-cement ratio. For OPC, the addition of WRAs appeared to improve the both short- and long-term performance of CPB samples. However, only polycarboxylate-based superplasticiser produced the desired 28-day strength of > or = 0.7 MPa when PCC was used as the binder. These findings suggest that WRAs can be suitably exploited for CPB of sulphide-rich tailings to improve the strength and stability in short and long terms allowing to reduce binder costs in a CPB plant. PMID:20382473

  9. Coupled effect of cement hydration and temperature on hydraulic behavior of cemented tailings backfill

    Institute of Scientific and Technical Information of China (English)

    WU Di; CAI Si-jing

    2015-01-01

    Cemented tailings backfill (CTB) is made by mixing cement, tailings and water together, thus cement hydration and water seepage flow are the two crucial factors affecting the quality of CTB. Cement hydration process can release significant amount of heat to raise the temperature of CTB and in turn increase the rate of cement hydration. Meanwhile, the progress of cement hydration consumes water and produces hydration products to change the pore structures within CTB, which further influences the hydraulic behavior of CTB. In order to understand the hydraulic behavior of CTB, a numerical model was developed by coupling the hydraulic, thermal and hydration equations. This model was then implemented into COMSOL Multiphysics to simulate the evolutions of temperature and water seepage flow within CTB versus curing time. The predicted outcomes were compared with correspondent experimental results, proving the validity and availability of this model. By taking advantage of the validated model, effects of various initial CTB and curing temperatures, cement content, and CTB's geometric shapes on the hydraulic behavior of CTB were demonstrated numerically. The presented conclusions can contribute to preparing more environmentally friendly CTB structures.

  10. A numerical study of macro-mesoscopic mechanical properties of gangue backfill under biaxial compression

    Institute of Scientific and Technical Information of China (English)

    Huang Zhimin; Ma Zhanguo; Zhang Lei; Gong Peng; Zhang Yankun; Liu Fei

    2016-01-01

    Based on the Particle Flow Code (PFC2D) program, we set up gangue backfill models with different gangue contents and bond strength, and studied the stress–strain behaviours, the pattern of shear band and force chains, motion and fragmentation of particles under biaxial compression. The results show that when the bond strength or contents of gangue are high, the peak strength is high and the phenomena of post-peak softening and fluctuation are obvious. When gangue contents are low, the shape of the shear band is sym-metrical and most strong force chains transfer in soil particles. With an increase in gangue content, the shape of the shear band becomes irregular and the majority of strong force chains turn to transfer in gangue particles gradually, most of which distribute along the axial direction. When the gangue content is higher than 50%, the interconnectivity of strong force chains decreases gradually;at the same time, the strong force chains become tilted and the stability of the system tends to decrease. With an increase in external loading, the coordination numbers of the system increase at first and then decrease and the main pattern of force chains changes into columnar from annular. However, after the forming of the advanta-geous shear band, the force chains external to the shear band maintain their columnar shape while the inner ones bend obviously. As a result, annular force chains form.

  11. Composite backfill materials for radioactive waste isolation by deep burial in salt

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, E.J.

    1980-01-01

    Bentonite and hectorite were found to sorb Pu(IV) and Am(III) from concentrated brines with distribution coefficients K/sub d/ > 3000 ml/g. The permeability of bentonite to brine was less than 1 microdarcy at a confining pressure of 18 MPa, the expected lithostatic pressure at the 800 m level in a salt repository. Getters for sorption of TcO/sub 4//sup -/ (K/sub d/ approx. 300 ml/g), I/sup -/ (K/sub d/ greater than or equal to 30 ml/g), Cs (K/sub d/ greater than or equal to 30 ml/g) and Sr (K/sub d/ greater than or equal to approx. 100 ml/g) from brines were identified. Their sorption properties are presented. Thermal conductivity results (>0.5 W/mK) and evidence for bentonite stability in brines at hydrothermal conditions are also given. It is shown by calculated estimates that a 3-ft-thick mixture of bentonite with other getter materials could retain Pu, Am, and TcO/sub 4//sup -/ for >10/sup 4/ years and I/sup -/ for > 10/sup 3/ years. Another tailored mixture could retain Cs for approx. 600 years, Sr for approx. 700 years, TcO/sub 4/ for approx. 4000 years and I/sup -/ for approx. 400 years. The backfill can offer a significant contribution to the isolation capability of a waste package system.

  12. The Bacchus backfill experiment at the Hades underground research facility at Mol, Belgium

    International Nuclear Information System (INIS)

    BACCHUS is the acronym for Backfilling Control experiment for High level wastes in Underground Storage. This large scale experiment is considering a compacted clay-based material around a heater implanted in the host clay in order to investigate the thermal behaviour of the Boom clay as well as the thermal and hydraulical transfers through a highly compacted material. It was developed jointly with CEA/DRDD in Fontenay. Beside the experiment itself and its original design, material characterization and instrumentation survey were important aspects in which considerable experience has been gained. In this respect, the development of specific sensors (thermal shock and Time Domain reflectometry probes) adapted to the particular experimental conditions is worth mentioning. In-situ investigations from the Hades facility have been running from November 1988 (implementation in clay) to August 1990 (end of the 5 months heating phase). Most of the data could be reproduced using the computer code available at CEN/SCK but some important limitations have to be overcome in the future, as for example the behavior of partially saturated materials. 11 refs., 29 figs., 7 tabs

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

    International Nuclear Information System (INIS)

    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

  14. 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

  15. 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.

  16. Mechanical performance and ultrasonic properties of cemented gangue backfill with admixture of fly ash.

    Science.gov (United States)

    Wu, Di; Zhang, Yongliang; Liu, Yucheng

    2016-01-01

    Cemented gangue backfill (CGB) is prepared by mixing cement, coal gangue and water. Fly ash from the combustion of coal is commonly utilized as admixture to improve the mechanical performance and fluidity of CGB, as well as to reduce cost of preparing CGB. Uniaxial compressive strength (UCS) is one of the most commonly used indicators for evaluating the mechanical performance of CGB. Ultrasonic testing, which is a non-destructive measurement, can also be applied to determine the mechanical properties of cementitious materials such as CGB. So this paper investigates the UCS and ultrasonic pulse velocity (UPV) of CGB prepared at different fly ash dosage (19, 20 and 21 wt.%) and solid content (76.5, 77.5 and 78.5 wt.%), versus curing periods of 3-28 days. The UCS and UPV values of CGB increase with increasing fly ash dosage and solid content. In order to find out the correlation between the UCS and UPV values of CGB, different types (linear, logarithmic, exponential and power) of curve fitting are conducted on the CGB samples made at different solid content. An exponential relationship with the correlation coefficient of 0.959 appears to exist between the UCS and UPV for CGB samples. This obtained exponential relationship is validated to be available by performing the t- and F- tests. The results acquired by this paper are capable of providing guidance for utilizing UPV test to estimate the strength of underground CGB structures. PMID:26320702

  17. 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}.

  18. 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.

  19. Composite backfill materials for radioactive waste isolation by deep burial in salt

    International Nuclear Information System (INIS)

    Bentonite and hectorite were found to sorb Pu(IV) and Am(III) from concentrated brines with distribution coefficients K/sub d/ > 3000 ml/g. The permeability of bentonite to brine was less than 1 microdarcy at a confining pressure of 18 MPa, the expected lithostatic pressure at the 800 m level in a salt repository. Getters for sorption of TcO4- (K/sub d/ approx. 300 ml/g), I- (K/sub d/ greater than or equal to 30 ml/g), Cs (K/sub d/ greater than or equal to 30 ml/g) and Sr (K/sub d/ greater than or equal to approx. 100 ml/g) from brines were identified. Their sorption properties are presented. Thermal conductivity results (>0.5 W/mK) and evidence for bentonite stability in brines at hydrothermal conditions are also given. It is shown by calculated estimates that a 3-ft-thick mixture of bentonite with other getter materials could retain Pu, Am, and TcO4- for >104 years and I- for > 103 years. Another tailored mixture could retain Cs for approx. 600 years, Sr for approx. 700 years, TcO4 for approx. 4000 years and I- for approx. 400 years. The backfill can offer a significant contribution to the isolation capability of a waste package system

  20. 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

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

    International Nuclear Information System (INIS)

    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/m3, with an average buffer dry density of 1600 kg/m3 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/m3, depending on material and placement method used. The lowest values were noted from

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

    International Nuclear Information System (INIS)

    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, CodeBright 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 CodeBright, 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

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

    International Nuclear Information System (INIS)

    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

  4. 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

  5. Swelling behavior of GMZ01 buffer/backfill material under flexible boundary condition

    International Nuclear Information System (INIS)

    In the high-level radioactive waste geological repository, the swelling properties of buffer/backfill material play an important role for insuring the long-term stability and safety of the repository. Traditionally, soil swelling behavior has been thoroughly examined under two extreme boundary conditions that included constant volume and constant stress. However, there exist infinite possible intermediate conditions that are neither constant volume nor constant stress and are termed flexible boundary conditions. In literature, the information on soil swelling behavior under flexible boundary condition is limited. In this investigation, a special flexible load ring-type device was developed to perform swelling tests on Gaomiaozi (GMZ01) bentonite under flexible boundary conditions, where the applied stress increases with increasing volume at a specified function. The initial dry density of the soil sample is 1.7 g/cm3, the applied initial axial stress is 0.2 MPa. The results indicate that the developed load ring-type device is effective to characterize the swelling behavior of soil sample under flexible boundary conditions; both the swelling strain and swelling pressure increase with increasing flooding time and then gradually reach stabilization, and the void ratio of the sample increases linearly with increasing swelling pressure; with increasing stiffness of the load ring, the finial swelling stain decreases while the final swelling pressure increases. For the tested soil sample, as the stiffness of the load ring increases from 278.5 N/mm to 2152 N/mm, the final equilibrium swelling strain decreases from 15.88% to 6.84%, while the final equilibrium swelling pressure increases from 0.59 MPa to 1.50 MPa. The experimental results highlights that choosing an appropriate swelling testing technique to simulate the field conditions is essential for design and evaluation of soil swelling potential. (authors)

  6. Couple mechanics hydraulics and sorption properties of mixtures to evaluate buffer/backfill materials

    International Nuclear Information System (INIS)

    The technique of multi-barrier disposal systems of radwaste has been studying among the world. The buffer materials that retard the migration of nuclides and make the canisters stable play a very important role. To couple engineering and sorption properties to evaluate the buffer/backfill materials, synthetic groundwater (GW) and seawater(SW) were used as the liquid phases to simulate possible conditions for a deep geological disposal in an island. The Rd value of Cs, I and Se (10-4 M ) with respect to various composite ratios of bentonite/ laterite/ quartz sand mixtures were measured using batch sorption tests in GW and SW. De-ionic water (DIW) was used as the liquid phase for Atterberg limit tests, triaxial shear test s and hydraulic conductivity tests to acquire the engineering properties of those mixtures mention above. The Atterberg limit tests results showed that 7 samples are concluded inorganic clays of high plasticity and one is inorganic clays of medium plasticity. The samples with 30% quartz sand content indicate the higher shear strength than those with 50% quartz sand content and very low hydraulic conductivity for all samples are in the same order about 1-10 m/s. The sorption of Cs on mixtures reveals that distribution coefficients (Rds) is higher in GW than those in SW. The Rd s of Cs are inverse proportion to plastic index (PI) in GW and SW as well as the Rds of Se. The sorption of Se on mixtures is affected significantly by composition of solid phase. However, the major affection for sorption of Se is solid phase and that of Cs is liquid phase. Very low sorption of I on all mixtures in GW and SW. Under these experimental conditions, these results reveal that more effective buffer material composition of 30% quartz sand content which PI are 40 to 60. Laterite is more effective sorbent for Cs and Se than Bentonite. (authors)

  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. 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)

    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

  9. Borehole Heat Exchanger Systems: Hydraulic Conductivity and Frost-Resistance of Backfill Materials

    Science.gov (United States)

    Anbergen, Hauke; Sass, Ingo

    2016-04-01

    Ground source heat pump (GSHP) systems are economic solutions for both, domestic heating energy supply, as well as underground thermal energy storage (UTES). Over the past decades the technology developed to complex, advanced and highly efficient systems. For an efficient operation of the most common type of UTES, borehole heat exchanger (BHE) systems, it is necessary to design the system for a wide range of carrier fluid temperatures. During heat extraction, a cooled carrier fluid is heated up by geothermal energy. This collected thermal energy is energetically used by the heat pump. Thereby the carrier fluid temperature must have a lower temperature than the surrounding underground in order to collect heat energy. The steeper the thermal gradient, the more energy is transferred to the carrier fluid. The heat injection case works vice versa. For fast and sufficient heat extraction, even over long periods of heating (winter), it might become necessary to run the BHE with fluid temperatures below 0°C. As the heat pump runs periodically, a cyclic freezing of the pore water and corresponding ice-lens growth in the nearfield of the BHE pipes becomes possible. These so called freeze-thaw-cycles (FTC) are a critical state for the backfill material, as the sealing effect eventually decreases. From a hydrogeological point of view the vertical sealing of the BHE needs to be secured at any time (e.g. VDI 4640-2, Draft 2015). The vertical hydraulic conductivity of the BHE is influenced not only by the permeability of the grouting material itself, but by the contact area between BHE pipes and grout. In order to assess the sealing capacity of grouting materials a laboratory testing procedure was developed that measures the vertical hydraulic conductivity of the system BHE pipe and grout. The key features of the procedure are: • assessment of the systeḿs hydraulic conductivity • assessment of the systeḿs hydraulic conductivity after simulation of freeze-thaw-cycle

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

    International Nuclear Information System (INIS)

    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

  11. Research and application of schemes for constructing concrete pillars in large section finishing cut in backfill coal mining

    Institute of Scientific and Technical Information of China (English)

    Sun Qiang; Zhang Jixiong; Ju Feng; Li Linyue; Zhao Xu

    2015-01-01

    Based on the technology of controlling surrounding rock deformation by constructing concrete pillars in large section finishing cut in backfill coal mining, the characteristics of vertical stress on concrete pillars and main factors influencing pillar stability are analyzed. By building a Winkler elastic foundation mechanical model for the support system constituted of coal pillar, backfill body and concrete pillars, mechanical calculation on stability of concrete pillar is carried out to evaluate the pillar stability and safety. Seven numeral models in three schemes with different pillar sizes, inter-row distances and com-pression ratios at the stopes were analyzed through numerical simulation according to width reduction principle. The practice of finishing cut at III644 workface at Yangzhuang coal mine shows that:when the actual compression ratio is 86.5%, construction size inside the finishing cut is 2000 mm ? 2000 mm and the interval between concrete pillars is 2000 mm ? 2000 mm, the pillars can be stable with the maxi-mum movement of two sides of each pillar being only 83 mm and 54 mm, which achieves the expected effect.

  12. Calculation procedure in GOLIA-FAME for pressure adjustment as a function of the compressibility of backfill

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, L.F.M.

    1991-08-01

    In a repository for radioactive waste in a salt formation there are openings (boreholes and galleries) that are excavated or drilled in order to store the waste into the salt formation. After storage of the waste the remaining openings are backfilled with a salt mixture. The behaviour of the salt mixture is laid down in a relation between the volumetric compression rate of the mix and the compressive working on it. In this report a set of subroutines for the FE-code GOLIA-FAME is described which can be used to model the interaction between the salt and the backfill. An example is described and some numerical tests are presented. The subroutines can easily be implemented in the computer code GOLIA-FAME and can easily be adapted for other specific purposes than described in this report in which the deformation of the structure is related to a pressure change. In the future it will be investigated how the pressure adjustment can be implemented in the Runge-Kutta solution steps of GOLIA-FAME to improve the efficiency of the program. (author). 2 refs.; 9 figs.; 5 tabs.

  13. 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.

  14. 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. PMID:27198634

  15. Hydraulic behaviour of bentonite based mixtures in engineered barriers: The Backfill and Plug Test at the Äspö HRL (Sweden)

    OpenAIRE

    Mata Mena, Clemente

    2003-01-01

    In 1996 the Backfill and Plug Test Project started at the Äspö Hard Rock Laboratory (Sweden) managed by SKB (the Swedish Radioactive Waste Agency). The Backfill and Plug Test Project makes up an important part of SKB's research in order to store nuclear waste in a deep geological repository in a safe manner. ENRESA (the Spanish Radioactive Waste Agency) collaborates in this project with the Swedish companies SKB and Clay Technology in characterising the hydro-mechanical behaviour of the backf...

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

    International Nuclear Information System (INIS)

    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% K2O) of the Na>Mg>>K. The 2O) 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

  17. 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. PMID:23220652

  18. 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

  19. 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)

    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)

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

    International Nuclear Information System (INIS)

    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

  1. 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)

    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)

  2. Backfilling-Free Strategy for Biopatterning on Intrinsically Dual-Functionalized Poly[2-Aminoethyl Methacrylate-co-Oligo(Ethylene Glycol) Methacrylate] Films.

    Science.gov (United States)

    Lee, Bong Soo; Lee, Juno; Han, Gyeongyeop; Ha, EunRae; Choi, Insung S; Lee, Jungkyu K

    2016-07-20

    We demonstrated protein and cellular patterning with a soft lithography technique using poly[2-aminoethyl methacrylate-co-oligo(ethylene glycol) methacrylate] films on gold surfaces without employing a backfilling process. The backfilling process plays an important role in successfully generating biopatterns; however, it has potential disadvantages in several interesting research and technical applications. To overcome the issue, a copolymer system having highly reactive functional groups and bioinert properties was introduced through a surface-initiated controlled radical polymerization with 2-aminoethyl methacrylate hydrochloride (AMA) and oligo(ethylene glycol) methacrylate (OEGMA). The prepared poly(AMA-co-OEGMA) film was fully characterized, and among the films having different thicknesses, the 35 nm-thick biotinylated, poly(AMA-co-OEGMA) film exhibited an optimum performance, such as the lowest nonspecific adsorption and the highest specific binding capability toward proteins. PMID:27252120

  3. 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)

    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, Kd, and surface distribution ratios, Ka; 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.)

  4. Simulations of the near-field transport of radionuclides by liquid diffusion at Yucca Mountain: Comparisons with and without emplacement backfill

    International Nuclear Information System (INIS)

    The possible set of hydrologic conditions at the Yucca Mountain repository site includes the case where groundwater recharge fluxes are sufficiently low relative to molecular diffusion in the rock so that, in the region around the waste package, the dominant mode of aqueous transport of radionuclides is by diffusion. Although the rock at the repository level is unsaturated, a sufficient amount of pore water could form a contiguous diffusion path from the waste form to the near-field rock if the waste is postulated to be in contact with the rock or emplacement backfill due to failure of the container. Future simulations will have to include conditions where the effects of convective transport in the rock are important in aqueous transport. We consider in this report simplified simulations of one-dimensional transport of radionuclides in the rock due to liquid molecular diffusion in order to determine the effects of an emplacement backfill. Comparison of estimated release rates with and without an emplacement backfill were given in an article by Chambre and Pigford [1984], and these values were referenced in our previous report. Here, we have extended their calculations to include estimates using the physical parameters expected at the Yucca Mountain repository site. Our model is a simple one-dimensional treatment of diffusion in a spherically symmetric geometry that takes into account the sorptive effects of the tuff and backfill through the use of K/sub d/ values. This geometry rather than a cylindrical one was chosen because it is conservative in predicting higher release rates. Radioactive decay is included, and only one species at a time is treated. The dissolution of the radionuclides is assumed to be solubility-limited. 12 refs., 13 figs., 1 tab

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

    International Nuclear Information System (INIS)

    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 m3/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/m3 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

  6. Experimental study of swell-shrink characteristics on compacted Gaomiaozi bentonite as the buffer/backfilling materials for HLW disposal

    International Nuclear Information System (INIS)

    In the deep geological disposal of high-level radioactive waste, buffer/backfill materials act as engineering barrier, hydraulic barrier, and chemical barrier, which can transmit and propagate the heat generated by radioactive waste in the deep geological repository. Gaomiaozi (GMZ) bentonite has been chosen as the first choice for using as buffer/back- fill materials in deep disposal of high-level radioactive waste in China. The swelling pressure, swelling and shrinking de formation property of compacted GMZ bentonite are studied in this paper. The results show that GMZ bentonite has high swelling property and low shrink characteristic. Swelling pressure changes with time nonlinearly. Moreover, there is a linear relationship with water content and an exponential relationship with dry density. The swelling property is influenced mainly by initial dry density, and the shrinking property is influenced mainly by initial water content. On the condition of the high water content and dry density, swelling pressure is about 0.85∼4.64 MPa, unloaded swelling ratio and shrinkage coefficient are around 24.4%∼40.8% and 0.19∼0.50 respectively. (authors)

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

    International Nuclear Information System (INIS)

    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

  8. The effect of pore fluid chemistry on strength and stress-strain behaviour of light and dense backfill materials

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Canada's Nuclear Waste Management Organization (NWMO) is investigating various concepts for isolation of Canada's used reactor fuel. These concepts include the In-floor Borehole (IFB), In-room and Horizontal Borehole geometries and geological environments being considered include crystalline bedrock of the Canadian Shield and low permeability sedimentary rocks such as limestone and shale. Regardless of geometry or geological environment, all options being considered will employ multiple clay-based barriers that include Highly Compacted Bentonite (HCB), Dense Backfill (DBF), Light Backfill (LBF), and Gap fill (GF). These materials will be initially placed in a repository in an unsaturated state, and will eventually become saturated with groundwater from the local geological environment. In both geological environments, the potential exists for the sealing materials to become saturated with high salinity groundwater. Quantitatively, the impact of high salinity on the strength and deformation performance of clay-based barriers is poorly understood although salinity is known to significantly affect the strength, compressibility, and hydraulic conductivity of clay-based barriers due to the suppression of the diffuse double layer. Understanding these potential changes in material properties is important in order to predict the overall performance of the clay barriers throughout the evolution of the system. This paper presents the results of a series of triaxial and one-dimensional oedometer tests conducted on LBF and DBF under various pore fluid conditions. Triaxial tests included isotropically consolidated drained (CID) and undrained (CIU-bar) tests. Testing was conducted collaboratively at the geotechnical laboratories of Atomic Energy of Canada Limited (AECL), the University of Manitoba (U of M) and the Royal Military College of Canada (RMC). The LBF and DBF materials used in this testing programme were

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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 60Co and 134Cs. The saturated permeabilities of the two ancient materials are in the order of 10-10 m/s and the distribution coefficients for the two radionuclides are all in the order of 101 m3/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)

  12. The potential use of swelling clays for backfilling and sealing of underground repositories: The case of the Boom clay

    International Nuclear Information System (INIS)

    In Belgium the SCK/CEN is studying the geological disposal of high level radioactive waste in the Boom clay formation. In such an argillaceous repository, the backfilling and sealing features will be multiple: boreholes, shafts, access drifts, disposal galleries or holes and dams. A preliminary selection study screening industrial materials has been performed based on the following criteria: at least as good thermal and hydraulic properties as the in situ Boom clay, sufficient volumetric swelling and swelling pressure, proven geochemical compatibility and stability. This study has shown that swelling clays are the most promising materials. Because of its evident geochemical compatibility and its easy availability, it is a logic choice to study the re-use of the excavated clay. The hydraulic, thermal and geochemical retention and swelling properties of the Boom clay were studied and the results are compared to those of bentonites. The main results of this study are: a hydraulic conductivity as low as 10-13 m/s can be reached which is one order of magnitude lower than that of the in situ Boom clay but is one order of magnitude higher than those of bentonite; the volumetric swelling of the Boom clay is rather limited but a swelling pressure of about 4 MPa can be obtained which is about a factor five lower than for bentonites but also corresponds to the in situ lithostatic pressure; the radionuclide retention properties of the in situ Boom clay are at least as good as those of dense bentonites and are for some nuclides even better; steam drastically reduces the volumetric swelling of bentonites which also leads to a higher hydraulic conductivity. The swelling properties of the Boom clay are also to be affected by steam, but the effect is less dramatic. In particular, its low hydraulic conductivity seems to be conserved. (author). 14 refs, 4 figs, 6 tabs

  13. Effect of water salinity on the hydro-mechanical behaviour of granular bentonite as light backfill material

    Energy Technology Data Exchange (ETDEWEB)

    Batenipour, H. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Civil Engineering; Kjartanson, B.H. [Lakehead Univ., Thunder Bay, ON (Canada). Dept. of Civil Engineering

    2008-07-01

    Crystalline rocks in the Canadian Shield and sedimentary rocks in Ontario are now being considered as deep geologic repositories (DGR) for spent nuclear fuels. Both areas contain relatively high salinity, calcium (Ca) rich groundwaters. Design plans have included a high compacted bentonite (HCB) layer adjacent to the container with an effective montmorillonite dry density (EMDD) of 1.5 Mg/m{sup 3}. This paper investigated the 1-D compression, swelling, and hydraulic behaviour and stiffness of granular bentonite light backfill (LBF) material in the presence of distilled water and 100 g/l calcium chloride (CaCI{sub 2}) and 250 g/l CaCI{sub 2} solutions were described and compared. The aim of the study was to examine the potential effects that the groundwaters may have on the long-term performance of the LBF. Tests were conducted to examine the dependence of the 1-D compression and swelling behaviour of LBF on the wetting and loading path. Results showed that the swelling, and self-sealing ability of the bentonite LBF was adversely affected by the presence of the 250 g/l CaCI{sub 2} solution. Samples of the 250 g/l solution achieved only 7 per cent to 10 per cent swelling strain under unloaded conditions. Stiffness increased exponentially with EMDD. It was concluded that the hydraulic conductivity values calculated from the loading increments of the tests increased with increasing CaCI{sub 2} concentrations and decreased with increasing EMDD. 11 refs., 2 tabs., 10 figs.

  14. Experimental research on the strength of cemented backfilling body of waste rocks%废石尾砂胶结充填体强度试验研究

    Institute of Scientific and Technical Information of China (English)

    罗根平; 乔登攀

    2015-01-01

    Experimental study is systematically conducted on cemented backfilling with waste rocks.The paper states the applicability and mechanism of waste rock cemented filling process and focuses on the influencing factors on the strength of cemented filling body of waste rocks,namely the water-cement ratio,cement-sand ratio,cement content, the grading and proportioning of the particle size of waste rocks.The research results show that the lager the water-ce-ment ratio and cement-sand ratio are,the less the strength of cemented backfilling body becomes,contrary to that rela-tion between cement content and the backfilling body's strength.With constant strength,cemented filling with waste rocks consumes less cement per unit volume and cost less than other filling methods.%对废石尾砂胶结充填进行了系统的试验研究。阐述了废石尾砂胶结充填工艺的工业性及原理,着重研究了废石尾砂胶结充填体强度的影响因素:水灰比、灰砂比、水泥含量、废石尾砂的粒径级配及配比。研究结果表明,废石尾砂胶结充填体强度随水灰比、灰砂比的减小而增大,随水泥含量的增加而增加。在强度一定的条件下,废石尾砂胶结充填比其他充填方式,单位体积内水泥耗量少,成本低。

  15. 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)

    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 m2/s, 1.44×10–14–9.41×10–14 m2/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

  16. Np sorption onto cement and Mg(OH)2-MgCl2-based backfill material in altered Q-brine

    International Nuclear Information System (INIS)

    Retention of actinides such as Np in the near field is critical for the long-term disposal and storage of radioactive waste in geological salt deposits. Portland cement and potential backfill material may have the capability to retard actinide migration through sorption processes. However, the effectiveness of the backfill material and cement (and their corrosion products, respectively) in concentrated MgCl2-NaCl solutions is not known. No models are available to evaluate sorption processes for such conditions based on thermodynamic data. In the present communication we report on results of site specific sorption experiments for the Asse mine. The Asse mine is situated in a diapir of Zechstein salt deposits. The salt mine operated for production of halite and potash. After termination of potash mining, low- and intermediate-level radioactive waste was emplaced in 13 of the excavated rooms in a depth of about 750, 725 and 511 m below surface ground. The salt mine was used thereafter as an underground research laboratory to develop technologies for disposal of high-level radioactive waste. Since termination of research in 1995, numerous excavated rooms, where no radioactive waste was emplaced, are being backfilled with crushed salt. Leaking of ca. 10 m3 d-1 NaCl- and CaSO4-rich brine into the mine is observed for several years now. The leaking is considered in the closure concept of the mine. In the present closure concept, systematic filling of the Asse mine with crushed rock salt and a MgCl2-rich solution, e.g. Q-brine, is planned. Recently, the use of a Mg(OH)2-MgCl2-based material, so called Mg-depot, was proposed for backfilling of the emplacement rooms of the Asse mine (Schuessler et al., 2001). As described in a forthcoming publication of the authors (Metz et al., 2004), the Mg-depot provides favorable chemical conditions with respect to actinide solubility. Currently there is a strong interest if the Mg-depot or brucite, one of its main constituent, provides

  17. Modeling coupled blast/structure interaction with Zapotec, benchmark calculations for the Conventional Weapon Effects Backfill (CONWEB) tests.

    Energy Technology Data Exchange (ETDEWEB)

    Bessette, Gregory Carl

    2004-09-01

    Modeling the response of buried reinforced concrete structures subjected to close-in detonations of conventional high explosives poses a challenge for a number of reasons. Foremost, there is the potential for coupled interaction between the blast and structure. Coupling enters the problem whenever the structure deformation affects the stress state in the neighboring soil, which in turn, affects the loading on the structure. Additional challenges for numerical modeling include handling disparate degrees of material deformation encountered in the structure and surrounding soil, modeling the structure details (e.g., modeling the concrete with embedded reinforcement, jointed connections, etc.), providing adequate mesh resolution, and characterizing the soil response under blast loading. There are numerous numerical approaches for modeling this class of problem (e.g., coupled finite element/smooth particle hydrodynamics, arbitrary Lagrange-Eulerian methods, etc.). The focus of this work will be the use of a coupled Euler-Lagrange (CEL) solution approach. In particular, the development and application of a CEL capability within the Zapotec code is described. Zapotec links two production codes, CTH and Pronto3D. CTH, an Eulerian shock physics code, performs the Eulerian portion of the calculation, while Pronto3D, an explicit finite element code, performs the Lagrangian portion. The two codes are run concurrently with the appropriate portions of a problem solved on their respective computational domains. Zapotec handles the coupling between the two domains. The application of the CEL methodology within Zapotec for modeling coupled blast/structure interaction will be investigated by a series of benchmark calculations. These benchmarks rely on data from the Conventional Weapons Effects Backfill (CONWEB) test series. In these tests, a 15.4-lb pipe-encased C-4 charge was detonated in soil at a 5-foot standoff from a buried test structure. The test structure was composed of a

  18. 矿山废石全尾砂充填研究现状与发展趋势%The directions of R&D on backfill with waste rock and total tailings in underground mine

    Institute of Scientific and Technical Information of China (English)

    王贤来; 姚维信; 王虎; 乔登攀; 程伟华; 张磊

    2011-01-01

    矿产资源开发过程中产生的废石、尾砂和冶炼渣,等占我国工业固体废料排放量的85%左右.大量矿山固体废料堆放地表,易造成严重污染,诱发泥石流、尾矿溃坝事故.固体废料充填工艺是解决矿山废尾排放的最有效途径.本文介绍了低浓度分级尾砂充填、全尾砂高浓度充填、膏体似膏体充填、块石胶结充填工艺的研究与应用现状,并分析了矿山废石全尾砂充填技术的研究与发展方向.%The waste rock, tailings and smelter slag in the process of the exploitation of mineral resources accounted the industrial solid wastes for about 85% in China based on traditional mining pattern. A large number of the solid waste pilled up on the ground in mine can cause serious pollutions, and may induce mudflows and tailings dam-break accidents. Undoubtedly, the solid waste backfill is the most effective way to solve the discharge of mine waste. In this paper, the present situation of research and application of several filling technology are described with regard to low-density classified tailings backfill, high-density total tailings backfill, paste and like paste backfill, as well as rock cemented backfill. Furthermore, the directions of R&D on backfill with waste rock and total tailings in underground mine were analyzed.

  19. Groundwater recovery experiment in Mizunami Underground Research Laboratory. Numerical simulation of H-M coupled behavior of rock and backfill materials to evaluate the influence on the surrounding rock

    International Nuclear Information System (INIS)

    In the Mizunami Underground Research Laboratory, groundwater recovery experiment is being conducted to develop the method to understand the transition of geological environment due to groundwater recovery at the -500 m access and research gallery-north. As a part of this experiment, backfill test is planned using drilling pits filled with artificial materials (clay and concrete) to evaluate the influence on the surrounding rock mass due to the interaction of rock and artificial materials. In this study, numerical simulation of the backfill test has been carried out to predict the qualitative hydro-mechanical behavior. (author)

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

    International Nuclear Information System (INIS)

    . 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

  1. 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

  2. Evaluation of the effect of sodium silicate addition to mine backfill, Gelfill e Part 2:Effects of mixing time and curing temperature

    Institute of Scientific and Technical Information of China (English)

    M. Kermani; F.P. Hassani; E. Aflaki; M. Benzaazoua; M. Nokken

    2015-01-01

    The effects of mixing time and curing temperature on the uniaxial compressive strength (UCS) and microstructure of cemented hydraulic fill (CHF) and sodium silicate-fortified backfill (Gelfill) were investigated in the laboratory. A series of CHF and Gelfill samples was mixed for time periods ranging from 5 min to 60 min and cured at temperatures ranging from 5 ?C to 50 ?C for 7 d, 14 d or 28 d. Increasing the mixing time negatively influenced the UCS of Gelfill samples, but did not have a detectable effect on CHF samples. The curing temperature had a strong positive impact on the UCSs of both Gelfill and CHF. An elevated temperature caused rapid UCS development over the first 14 d of curing. Mercury intrusion porosimetry (MIP) indicated that the pore size distribution and total porosity of Gelfill were altered by curing temperature.

  3. 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)

    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

  4. 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)

    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

  5. On grouting strengthening construction of gravel soil back-filled foundation%碎石土回填基础灌浆补强施工

    Institute of Scientific and Technical Information of China (English)

    陶旭东

    2012-01-01

    针对某取水泵站投入运行后场区碎石土回填基础出现沉降的原因进行了分析,通过研究比选采用灌浆加固方案,对灌浆施工关键点及特殊情况处理进行了阐述,以保证场区稳定、安全。%The paper analyzes the reasons for the settlement of the gravel soil back-filled foundation at the site after some pumping station was op erated, and illustrates the key points for the grouting construction and some treatment for some special circumstances by comparing and analyzing the grouting consolidation schemes, so as to ensure the site to be stable and safe.

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

    International Nuclear Information System (INIS)

    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

  7. Self-sealing experiments and gas injection tests in a backfilled micro-tunnel of the Mont Terri URL

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. The investigation of damage zones around excavations such as seal sections in tunnels or shafts and their impact on gas migration are key issues in the field of underground waste disposal. The experiment ('Gas path through host rock and along seal sections / HG-A') was designed as a long-term gas experiment in a backfilled micro-tunnel, to investigate both leak-off rates and gas release paths from a sealed tunnel section in an ultra-low permeability host rock (Opalinus Clay). The aims of the HG-A experiment are to: - Provide evidence for barrier function of the Opalinus Clay on the tunnel scale (scale effects in rock permeability); - Investigate self-sealing of the EDZ after tunnel closure (mechanical self-sealing in response to packer inflation and pore pressure changes); - Provide evidence for gas transport capacity of Opalinus Clay (intact host rock and EDZ). The HG-A experiment is located in the southern part of the Mont Terri Rock Laboratory off Gallery 04. A 13 m long, 1 m diameter micro-tunnel was excavated in February 2005. Hydraulic and mechanical response to excavation was monitored in an array of boreholes HG-A2 to HG-A7. This was subsequently extended with additional piezometers and remote sensing boreholes (HG-A8-14, HGA24, A25). In summer 2006 a Mega-packer was emplaced to create a tunnel seal isolating the test section (see Figure 1). The test and seal sections were instrumented with piezometers, strain gauges, total pressure cells and Time Domain Reflectometers (TDRs). The response to excavation of the micro-tunnel and the associated creation and development of the Excavation Damage Zone (EDZ) is discussed in Marschall et al. (2006, 2008). The test section saturation and hydraulic testing prior to gas injection is presented in Lanyon et al. (2009). This paper presents the results of gas leak-off testing, subsequent post-gas hydraulic testing together with an overview of the rock's response to

  8. 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

  9. 江西省某冶炼厂遗留尾砂场重金属污染特征%Evaluation on heavy metal pollution of backfilling fields of a melting factory in Jiangxi

    Institute of Scientific and Technical Information of China (English)

    丁凝; 刘建明; 孙峰

    2014-01-01

    By using single -factor pollution index method and Nemerow index method,the paper mainly investigates into the heavy metals( Pb,Cd,Cu,Zn,Cr,Ni,As)content and pollution on the backfilling fields in a melting factory of JiangXi. The backfilling fields were used to contain waste residue generated from the melting production. The result indicated that all the backfilling fields had a highly standard-exceeding content of Cu ,Zn,Ni,and As in soil. Except the deep soil of back-filling field No. 2,soils in other sampling spots contained heavy metals with their comprehensive pol-lution index higher than 1 ,implying soils in all backfilling fields were seriously contaminated by heavy meatless.%以江西省某冶炼厂生产过程中遗留在厂内各尾砂池中的废渣为研究对象,利用单因子污染指数法和内梅罗综合污染指数法相结合的方法对其重金属污染状况进行评价。结果表明:各尾砂池土壤中铜、锌、镍、砷超标倍数高,且除尾砂池2深层土壤外,其他样点重金属内梅罗综合污染指数均远大于1,显示各尾砂池土壤均为重污染土壤。

  10. 全尾砂新型充填胶凝材料开发及其水化机理探讨%Discussion on exploitation of new backfilling cementing materials with unclassified tailings and associated hydration mechanisms

    Institute of Scientific and Technical Information of China (English)

    李茂辉; 杨志强; 高谦; 王有团

    2015-01-01

    Based on the characteristics of unclassified tailings in the Sijiaying iron mine, experimental research on exploitation of new backfilling cementing materials that can replace the cement was carried out using lime, desulfurization gypsum, slag, and other solid wastes. Using scanning electron microscopy ( SEM) and X⁃ray diffraction ( XRD) analysis, the hydration mechanisms of the new backfilling cementing materials were analyzed, and the optimum ratio of activators was determined. The results show that the strength of the new backfilling cementing materials can meet the filling body strength requirements for safe mining in the Sijiaying iron mine when the mass fractions of slurry, lime, and desulfurization gypsum are 68%, 3. 5%, and 16. 0%, respectively, and the cement⁃sand ratio is 1∶8. The results also show that the new backfilling cementing materials have a more compact structure and coarser occurrence when compared with the cement. The hydration products of the new backfilling cementing materials are mainly AFt crystals and C⁃S⁃H gel, which greatly increases the age strength of the new backfilling cementing materials.%针对司家营铁矿全尾砂,利用石灰、脱硫石膏、矿渣等固体废弃物开展替代水泥的新型充填胶凝材料试验研究,并通过电镜扫描( SEM)和X射线衍射( XRD)分析,研究新型充填胶凝材料激发剂的水化机理,确定激发剂优化配比。研究表明,当料浆质量分数为68%、胶砂比为1∶8、石灰质量分数为3.5%、脱硫石膏质量分数为16.0%时能够满足司家营铁矿南区嗣后充填法采矿对充填体强度的要求。结果显示,新型充填胶凝材料胶砂体与水泥胶砂体相比,结构更致密、产状更粗大,水化产物主要为AFt晶体和无定型C⁃S⁃H凝胶,从而大幅度提高了新型充填胶凝材料胶砂体的龄期强度。

  11. Determination of internal pressure and the backfill gas composition of nuclear fuel rods; Determinacion de la presion interna y la composicion del gas de llenado de barras de combustible nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Garcia C, M.A.; Cota S, G.; Merlo S, L.; Fernandez T, F. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1997-07-01

    An important consideration in the nuclear fuel manufacturing is the measurement of the helium atmosphere pressure and its composition analysis inside the nuclear fuel rod. In this work it is presented a system used to measure the internal pressure and to determine the backfill gas composition of fuel rods. The system is composed of an expansion chamber provided of a seals system to assure that when rod is drilled, the gas stays contained inside the expansion chamber. The system is connected to a pressure measurement digital system: Baratron MKS 310-AHS-1000. Range 1000 mm Hg from which the pressure readings are taken when this is stabilized in all the system. After a gas sample is sent toward a Perkin Elmer gas chromatograph, model 8410 with thermal conductivity detector to get the corresponding chromatogram and doing the necessary calculations for obtaining the backfill gas composition of the rod in matter. (Author)

  12. 采空区回填体隧道冒顶塌方处理技术%Treatment Technology on Roof Fall and Landslide of Backfilled Tunnel in Goaf

    Institute of Scientific and Technical Information of China (English)

    谈东亚

    2014-01-01

    以铜陵市五松隧道在施工中遇到的采空区回填体塌方处理为例,针对采空区回填体导致冒顶塌方的特点,从安全顺利的角度,通过临时环向竖向钢支撑加固未塌方段、套管法超前管棚超前预支护、水泥水玻璃注浆加固、预留核心土法开挖支护、回填轻质混凝土、换拱等技术,安全顺利地处理完该塌方,为今后类似工程提供一定的参考。%Based on the example of treatment on backfilled landslide in goaf encountered in Wusong Tunnel construction in Tongling,according to the characteristics of goaf backfilling roof fall and landslide,from the safety angle,measures are used to deal with the landslide,like temporary reinforcement of the sound section with circumferential vertical steel support,ad-vanced support with cuff shed pipe,grouting reinforcement with cement water glass,reservation core soil excavation,backfill-ing of light weight concrete,arch replacement technology,so as to provide references for similar projects in the future.

  13. Analysis of Impacts on Earthquake Response of Intake Tower by Backfill Concrete on Tower Back%塔背回填混凝土对进水塔地震响应的影响分析

    Institute of Scientific and Technical Information of China (English)

    李锋

    2015-01-01

    塔背回填混凝土将岸塔式进水塔和山岩连成一体,提高了进水塔整体刚度,有效改善了塔体在地震情况下的拉应力幅值,对进水塔结构的抗震设计非常关键。以某水电站的岸塔式进水塔为例,针对不同高度塔背回填混凝土的塔体模型进行三维有限元静动力计算,以分析回填混凝土对进水塔地震响应的影响。%The backfill concrete on the tower back integrates the intake tower and the mountain rockmass, increasing the overall rigidity of the intake tower and effectively improving the tensile stress range value of the tower body in earthquake condition.This is very important for the aseismic design of the intake tower structure.With the case of the intake tower of one hydropower station, the static and dynamic calculations in 3D finite element method are performed to the tower models with the backfill concrete on the tower back at different heights so as to analyze the impacts on the earthquake response of the intake tower by the backfill concrete on the tower back.

  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)

    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. Size effect of compressive strength of cemented backfill%胶结充填体力学强度尺寸效应

    Institute of Scientific and Technical Information of China (English)

    彭志华

    2009-01-01

    本文通过尾砂胶结充填体配比试验,研究了尾砂胶结充填体强度与试样尺寸和几何形状之间的关系.试验研究结果表明:在相同条件下,胶结充填体强度在试验范围内,随试样尺寸的增加而减小,其呈非线性变化;不同尺寸与几何形状的胶结充填体试样强度之间的换算比例关系为:152mm充填体试样强度大致为72mm和85mm试样强度的3/4,为70.7mm立方体试样强度的3/5.%This paper researches relation of compressive strength of cemented tailings fill and size、geometries of cemented backfill. The test results show under same condition compressive strength of cemented tailings fill will minish with size increasing, it show itself non-linear variety. 150mm diameter cylinder specimen fill strength averaged approximately three-quarter of 72mm and 85mm diameter cylinders specimen, about three fifths of 70.7mm cubes specimen.

  17. Reduced clay bearing gray sandstone deposits of Meghalaya, NE India: a possible upper backfill material in geological repository for high level radioactive waste Disposal

    International Nuclear Information System (INIS)

    Geology and geochemical aspects of reduced clay rich gray sandstones of Cretaceous age hosting anomalous uranium occurrences in Meghalaya plateau have been evaluated to assess their suitability as lower backfills in far field region of the geological repository. These sandstones are chiefly made up of quartz (70-90%) and contain appreciable amount of clays and organic matters. Geochemical data on these sandstones indicates that actinides (U and Th), elements analogues to fission products (Rb, Sr, Zr, Mo, Nb, Cd, Ag, Cs, Ba and rare earth elements are adequately retained in clays and organic matters associated with these deposits. Albeit these clay rich (Illite-Smectite-Kaolinite) sandstones contain almost 30 % water-soluble uranium and lies in one of the highest rainfall area of the world, not much uranium and other trace elements have been reported to escape from the geological set up and hydrogeological system. Due to the presence of strong reducing environment prevailing in these rocks caused by the presence of pyrite and organic matter, most of the uranium being dissolved by circulatory oxygenated groundwater gets reduced and also is trapped in the organic matter as organo uranyl complexes. The organic matters in these sandstones have total adsorption capacity of 0,5% for actinides and at time contains as high as 40% uranium adsorbed form groundwater. Similarly it also contains as high as 193-ppm molybdenum, 458-ppm cadmium and 35-ppm silver. Data also reveals that most of the organic matter has been subjected to temperature more than 100 C in the geological past during its burial and diagenesis, hence possibility of carbon dioxide production consequent to waste emplacement also does not exists. The clays in these sandstones reveal good retention capacity for uranium, radium, rubidium, strontium, cesium and rare earth elements, whereas most of the barium appears to have been accommodated in secondary calcite frequently available in these sandstones

  18. Mechanical properties and consolidation of potential DHLW [Defense High-Level Wastes] backfill materials: Crushed salt and 70/30 bentonite/sand

    International Nuclear Information System (INIS)

    Thermomechanical properties of intact rock salt and the waste package materials have appeared in the literature. Only limited data is available, however, for the two backfill materials of interest in the analyses, crushed salt and 70/30 (by weight) bentonite/sand. A unique property of bentonite-based materials is the propensity for clay particles to swell as a result of water sorption. If volume expansion is prevented or partially restricted, pressures are built up within the bentonite materials. Therefore, the primary objective of this study is to supply appropriate data (not available in the literature) in support of the aforementioned detailed thermomechanical stress analyses. The study consists of laboratory tests performed on samples of crushed salt and 70/30 bentonite/sand. The remainder of this report is organized into five chapters and four appendixes. Chapter 2 describes the specimens tested in this study. Chapter 3 describes the testing machines and test procedures used. Chapter 4 gives the results of the tests on crushed salt and 70/30 bentonite/sand. Chapter 5 gives conclusions of the test program and is followed by a list of cited references. Four appendixes conclude the report. The first and second give stress-strain curves for the unconfined compression tests on crushed salt and 70/30 bentonite/sand, respectively; the third gives details of the algorithm used to compute volumetric strains during hydrostatic compression tests which accounts for vessel volume change; while the final appendix gives mean stress-volumetric strain curves for the hydrostatic compression tests. 16 refs., 18 figs., 10 tabs

  19. 堤坝下矸石不升井充填采煤技术实践%Application of solid backfill mining under dams avoiding raising waste rock

    Institute of Scientific and Technical Information of China (English)

    李剑; 王东升; 王志平; 康涛; 耿佃凯

    2013-01-01

      Aimed at exploiting coal resources under dams safely and efficiently and disposing of gangue excavated underground on a large scale of Jisan coal mine ,Yankuang Group ,this paper presented a solution of solid backfilling mining avoiding raising waste rock .According to mining geological conditions in pilot area of Jisan coal mine and structural characteristics of Nanyang Lake Dam ,proposed a method of gangue preprocessing and transport from advancing face to backfilling working face .Based on technical characteristics of backfilling mining ,developed four key equipments in backfilling working face :four‐link backfill supports with six props ,backfilling conveyor with a bunch of unloading holes at the bottom ,a full coal seam compactor and a self‐shift transshipping conveyor .According to the protection requirement of Nanyang Lake Dam ,determined the security technical measures of filling ratio .When mining was completed at 63下 04‐1 working face ,the maximum sinking value of the Nanyang Lake Dam was 32mm and the maximum horizontal deformation value was 0 .14mm/m ,which were both far lower than the predicted value and the dam's deformation extremum ,both Nanyang Lake Dam and the buildings around had not occurred crazing damage .%  为达到兖矿集团济三煤矿堤坝下压煤资源的安全高效开采及井下掘进矸石规模化处理的目的,提出采用矸石不升井充填采煤技术开采堤坝下压煤。根据济三煤矿试验区域采矿地质条件及南阳湖堤结构特点,设计了矸石由掘进工作面至充填采煤工作面的预处理和运输方案;基于充填采煤的工艺要求,研发了充填采煤工作面4种关键设备:正四连杆六柱式固体充填采煤液压支架、多孔底卸式输送机、全采高夯实机和自移式充填物料转载输送机;依照南阳湖堤保护要求,确定了充填采煤充实率保障技术措施。63下04‐1工作面按照设计方案开采完毕后,实测

  20. Research on Protecting the Safety of Buildings by Using Backfill Mining with Solid%利用固体充填开采方法保护建筑群安全的研究

    Institute of Scientific and Technical Information of China (English)

    徐惠

    2012-01-01

    我国煤矿建筑物下压煤量占总压煤量的69%,同时每年要向地面排放4.5亿t以上的固体废弃物,因此,研究利用固体废弃物充填开采方法,在保证地表建筑物安全性的基础上,高效开采出下压煤炭资源意义重大.文章应用数值模拟方法,对建筑物下压煤开采所引起的岩层移动过程进行模拟,系统分析了采场围岩塑性区分布及地表沉陷量变化规律,由计算结果分析得知,应用固体充填开采法与无充填直接开采相比,采场围岩破坏单元数较少,围岩稳定性受影响较小,减少地表沉陷量效果明显.以数值模拟结果作为参考,研制了长臂综采矸石充填开采工艺的配套设备,并在某矿建筑物下压煤炭开采的实际应用中取得良好效果,有效控制了地表变形,保证了建筑物的安全性和资源的高效开采.%The coal under buildings accounts for 69% of the total in China,while more than 4.5 billion tons of solid waste is discharged to the ground over years.This paper studied the backfill with solid mining method.It is meaningful for the efficient exploitation of coal mining under buildings as well as reducing environmental pollution around the mining area.In this paper,we analyzed the plastic zone distribution of the face surrounding rock and the variation of surface subsidence systematically.According to the simulation results,backfill mining with solid reduce the damage to the surrounding rock of the goaf and diminish the effect on the stability of surrounding rock.It also can reduce the surface subsidence obviously.Taking the above study results as one of the important references,we research and design the matching equipments with fully-mechanized filling mining.The filling equipments mainly are the self-tamping backfilling hydraulic support and backfilling conveyor.These have been applied to an actual exploitation of coal mining under buildings,and achieved good results.It can control the surface

  1. Fatigue Analysis on Pallet of Chain Type Feeder System for Backfill Mining%充填采煤链式投料系统托盘疲劳分析

    Institute of Scientific and Technical Information of China (English)

    张国伟; 马占国; 耿敏敏; 龚鹏

    2011-01-01

    According to the importance of the pallet in the chain type feeder system for the backfill mining,with the calculation formula of the impact load provided with the energy method,a finite element program was applied to study on the fatigue damage of the pallet after the impact of the backfill material under the different spaces and different dropping velocities and to predict the fatigue life of the pallet.Finally the dangerous part of the pallet was analyzed and the fatigue law of the pallet affected by the impact of the backfill material was obtained.The study results showed that with the space between the pallets increased,the fatigue damage of the pallet would be higher and when the space between pallets was 5 m,the fatigue life would meet the mining service life of the mine.The higher of the pallet dropping velocity,the fatigue damage of the pallets could be reduced.In consideration of the strength,stability and transportation efficiency of the pallet,the dropping velocity of 1.5~2.5 m/s would be suitable.%针对托盘在充填采煤链式投料系统中的重要性,通过能量法得出冲击载荷计算公式,利用有限元程序对托盘在不同间距、不同下降速度下,受充填材料冲击后的疲劳损伤进行研究,预测了托盘的疲劳寿命。最后分析了托盘的危险部位,得到托盘受充填材料冲击的疲劳规律。研究结果表明:随着托盘间距增大,托盘疲劳损伤越大,托盘间距取5 m时其疲劳寿命符合煤矿开采年限;托盘下降的速度越大,其受到的疲劳损伤减少,考虑到托盘的强度、稳定性、运输效率,选取其速度为1.5~2.5 m/s较合适。

  2. Experimental study on workability of soil-bentonite backfills for vertical slurry cutoff walls%土膨润土系竖向隔离墙材料施工和易性试验研究

    Institute of Scientific and Technical Information of China (English)

    梅丹兵; 杜延军; 刘松玉; 范日东; 杨玉玲

    2016-01-01

    为研究满足各类场地条件下土膨润土系竖向隔离墙材料施工和易性要求的主要施工参数,对钙基膨润土浆液和钠基膨润土浆液进行马氏漏斗黏度试验、API滤失试验和密度测定,并针对砂膨润土、黏性土膨润土、砂黏性土膨润土3类土膨润土系竖向隔离墙材料进行坍落度试验.试验结果表明,钙基膨润土浆液和钠基膨润土浆液的合理膨润土掺量分别为10%和3%.3类土膨润土系竖向隔离墙材料的坍落度与含水率均呈良好的线性正相关性.采用标准坍落筒和迷你锥坍落筒所测定的坍落度结果之间存在统一的经验关系.采用迷你锥坍落筒代替标准坍落筒进行土膨润土系竖向隔离墙材料施工和易性试验时,满足坍落度要求的含水率范围为其液限的1.0~1.6倍,所对应坍落度范围为22~48 mm.%In order to investigate the main construction parameters that meet the workability of soil-bentonite backfills for vertical slurry cutoff walls under various types of site conditions, the marsh fun-nel test, API(American Petroleum Institute) filtrate loss test and density measurement for sodium ben-tonite-water slurries and calcium bentonite-water slurries were carried out.The slump tests of three soil-bentonite backfills, including sandy soil-bentonite, clayey soil-bentonite sandy and soil-clayey soil-bentonite backfills, were measured.The experimental results show that the suitable contents of bentonite for calcium bentonite-water slurries and sodium bentonite-water slurries are 10% and 3%, respectively.The slumps of three soil-bentonite backfills and the water content exhibit a good linear positive correlation.And there exists a uniform correlation between the results based on the standard slump cone and those based on the miniature slump cones.When the standard slump cone is replaced by the miniature slump cone, the water content meeting the requirements of the slump is

  3. 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)

  4. The stabilization of the rock mass of the wieliczka salt mine through the backfilling of the witos chamber with the use of injection methods / Stabilizacji górotworu kopalni soli "wieliczka" poprzez likwidację komór "witos" z zastosowaniem metod iniekcji

    Science.gov (United States)

    D'Obyrn, Kajetan

    2012-10-01

    The Wieliczka Salt Mine is the most famous and the most visited mining industry monument in the world and it requires modern methods to ensure rock mass stability and tourists' security. Both for conservation and tourism organization reasons, the group of Warszawa-Wisla-Budryk-Lebzeltern-Upper Witos Chambers (Photo. 1, 2. 3) located the Kazanów mid-level at a depth of 117 m underground is extremely important. Discontinuous deformation occurring in this Chamber complex was eliminated by comprehensive securing work with anchor housing, but their final securing and stability is conditioned by further backfilling and sealing the Witos Chambers situated directly beneath. In the 1940s and 1950s, the Witos Chamber was backfilled with slag from the mine boilerhouse. However, slags with 80% compressibility are not backfilling material which would ensure the stability of the rock mass. The chambers were exploited in the early nineteenth century in the Spizit salts of the central part of the layered deposit. The condition of the Upper Witos, Wisla, Warszawa, Budryk, and Lebzeltern Chambers is generally good. The western part if the Lebzeltern Chamber (Fig. 1), which was threatened with collapse, was backfilled with sand. In all the chambers of the Witos complex, local deformation of ceiling rock of varying intensity is observed as well as significant destruction of the side walls of pillars between chambers. No hydrogeological phenomena are observed in the chambers. It has been attempted to solve the problem of stability of the rock mass in this region of the mine by extracting the slag and backfilling with sand, erecting concrete supporting pillars, backfilling the voids with sand, anchoring the ceiling and the side walls, the use of the pillar housing. The methods have either not been applied or have been proved insufficient to properly protect the excavation situated above. In order to select the optimal securing method, a geomechanical analysis was conducted in order to

  5. 用充填技术促进矿山资源开发与环境保护协调发展%Coordinated Development between Mineral Resource Exploitation and Environmental Protection with Backfill Technology

    Institute of Scientific and Technical Information of China (English)

    苏亮; 张小华

    2013-01-01

    阐述了资源开发与环境保护的矛盾,提出了矿山资源开发与环境保护协调发展的主要目标及途径.将充填技术应用于资源-经济-环境体系中,根据矿山固体废弃物料的特点,对不同的固体废弃物料采用废石充填、尾砂充填和矿碴灰充填等不同的充填工艺技术,不仅提高了矿产资源的利用率,而且降低了矿山废弃固体物料对环境的污染.%In view of the contradiction occurred between mineral resources exploitation and environmental protection,technology of backfilling with waste rocks,tailing sand and slags according to different types of solid mine wastes is proposed to be adopted for achieving coordinated development of mineral resources exploitation and environmental protection.Practice shows such technology can not only improve the utilization of mineral resources,but also reduce the adverse effect of mining waste on environment.

  6. 高放废物地质处置库中缓冲回填材料的收缩特征%Shrinkage characteristics of buffer-backfilling materials in high-level radioactive waste geological disposal

    Institute of Scientific and Technical Information of China (English)

    唐朝生; 施斌; 崔玉军

    2012-01-01

    The shrinkage characteristics of buffer-backfilling materials play an important role in the security and stability of the high-level radioactive waste geological disposal system. COx argillite is considered as a kind of potential buffer-backfilling materials in France. In this investigation, both the initially saturated compacted COx specimens and the paste-like COx specimens are prepared and subjected to different test methods to study their volumetric shrinkage behaviours. For the compacted specimens, it is found that the volumetric shrinkage deformation is significantly influenced by the initial dry density; the shrinkage limit, shrinkage efficiency and shrinkage strain decrease with the increasing dry density; in addition, it is observed that the shrinkage direction of specimens shows obvious anisotropism. For example, at low degree of compaction, the radial shrinkage strain is higher than axial shrinkage strain, and the shrinkage geometry factor is larger than 3; however, the contrary results are obtained at high degree of compaction. For the paste-like specimens, three shrinkage stages can be distinguished: normal shrinkage, residual shrinkage and zero shrinkage; most of the volume shrinkage deformation occurs before the air-entry point while the soil is still fully saturated. A group of four general shrinkage models are employed to fit the shrinkage curve of the paste-like specimens. The results show that the G & C model can get the highest performance for the present soil.%缓冲回填材料的收缩特征对高放废物处置库的安全性和稳定性有重要影响。以COx泥岩缓冲回填材料为研究对象,采用不同的试验方法分别研究了饱和的压实试样和糊状试样在干燥过程中的体积收缩变形特征。试验结果表明:压实试样的体积收缩变形特征受初始干密度的影响比较明显,缩限、收缩系数和收缩应变均随初始干密度的增加而减小;压实试样的体积收缩

  7. Research on Backfilling Friction Stir Spot Welding of LY12 Al Alloy%LY12铝合金回填式搅拌摩擦点焊工艺研究

    Institute of Scientific and Technical Information of China (English)

    王朗; 王敏; 郭立杰

    2013-01-01

    采用回填式搅拌摩擦点焊对1mm厚的LY12铝合金薄板进行焊接,研究单参数对接头拉剪力的影响.结果表明,在其他条件不变时,套下压时间影响接头U型区域的宽度,套下压时间为3.2s时,接头的拉剪力达到最大值;其他参数对U型区域深度产生影响;回填时间为0.4s、旋转速度为1500r/min、下压深度为1.1mm、焊接压力为23 MPa时接头的拉剪力均达到最大值.正交试验工艺优化结果表明,最佳的工艺参数组合为:套下压时间为3.6s、回填时间为0.9s、旋转速度为2400r/min、下压深度为1.1mm、压力为24 MPa.对最佳参数组合下的接头进行金相分析,发现接头区域分为三个部分:混合区、热影响区和母材.%The backfilling friction stir spot welding to weld 1 mm-thick LY12 aluminum alloy plate was adopted, and the single parameter on the effect of joint's shear load was investigated. The results show that when other conditions remain unchange, pressure time affect the width of the joint area. When pressure time is 3.2 s, joint's shear load reach maximum; other parameters affect the depth of the joint area; when refilling time is 0.4 s, rotating speed is 1500 r/min, depth is 1.1 mm, pressure is 23MPa, joint's shear load reaches maximum. After the optimization of process parameters, the orthogonal test results show that the best process parameter combination is pressure time 3.6s, refilling time 0.9s, rotating speed 2400 r/m, depth 1.1 mm, pressure 24 MPa. The metallographic analysis of the welded joint at the best parameters found that the joint area is divided into three parts: mixed zone, heat affected zone and mother material.

  8. Numerical calculation of backfilling of scour holes

    DEFF Research Database (Denmark)

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

    2014-01-01

    updating in time, both the hydrodynamic and morphologic solutions being advanced with the same time increment. In this way, the simulations illustrate the ability to simulate fully-coupled hydrodynamic and morphologic developments based on continuous feedback. The model has been implemented for two kinds...

  9. Multi-objective Modeling and Simulation of Mining Backfill Scene%多目标建模技术及煤矿充填开采场景仿真

    Institute of Scientific and Technical Information of China (English)

    张国英; 梁旭; 张智跃

    2015-01-01

    矿山信息化建设是煤矿企业实现现代化发展的必然趋势.煤矿充填开采是一个复杂的过程,为了解决实现采煤充填过程最优化的问题,对开采场景进行仿真是一个直观而有效的解决方法.煤矿充填开采场景仿真不仅让人们更加深刻地了解开采实际生产环境,而且方便指导现场生产以及矿工安全培训,实现煤矿信息化、数字化.由于煤矿充填系统场景复杂、设备繁多、数据量大,实时仿真的技术难度较大.设计了场景树组织模型,有效组织充填开采场景要素.提出了基于设备组件分析及分层的复杂设备建模方法,以液压支架为例阐述了设备建模过程.提出了基于场景树的场景装配方法,包括场景环境生成、设备资源组织,用相对坐标方法进行资源装配,实现了充填开采的场景仿真.%Mine informationization is an inevitable trend to realize the modernization of coal mine enterprises. Mine filling mining is a complex process,in order to solve the problem to realize the optimization of the filling process of coal mining,the mining scene simula-tion is an effective method. Simulation of mining backfill scene not only makes people more understanding the actual mining environment of exploiting,but also easily guides on-site production and miners training,to realize informationization and digitization of coal mine. Be-cause of complex scenes,large volumes of equipment and data in mine filling system,the work of scene simulation is heavy,especially for real-time simulation technology. Design scene tree of filling mining, effectively organizing scene elements of filling. Complex device modeling method was presented in this paper,which includes the equipment' s components analysis and layer,with hydraulic support as an example to discuss the equipment modeling processing. Scene' s assembly method was proposed based on scene tree,including scene' s environment generation and equipment resources

  10. Compression Characteristics of Solid Wastes as Backfill Materials

    Directory of Open Access Journals (Sweden)

    Meng Li

    2016-01-01

    Full Text Available 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 between stress and compression degree was approximately nonlinear, and the deformation of gangue was rather large during the initial portion of the test. Gangue sample mixed with Talbot Formula provides the best deformation resistance capacity, followed by fully graded and single-graded gangue samples. For applications, with adjustment of the gradation of filling materials and optimal design of compacting equipment, surface subsidence may be better controlled.

  11. Mass transfer of soluble species into backfill and rock

    International Nuclear Information System (INIS)

    This report describes a mathematical model that estimates the rate that cesium and iodine isotopes would migrate from spent fuel rods after emplacement in a geologic repository that is subsequently flooded with ground water. 4 refs., 2 figs

  12. 30 CFR 715.14 - Backfilling and grading.

    Science.gov (United States)

    2010-07-01

    ... the product of the overburden thickness times the bulking factor to be determined for each mine area.... All final grading, preparation of overburden before replacement of topsoil, and placement of topsoil... instability. If such grading, preparation or placement along the contour would be hazardous to...

  13. Results of backfilling and injection tests for the sealing of areas adjacent to storage chambers

    International Nuclear Information System (INIS)

    Cabin closings of cabins considered adequate for the storage of nuclear waste shall during all phases of operation conform with the requirements for radio-activity protection of the operating personnel and of the environment. Systematic injection of areas adjacent to cabin closings model 2 provide for the controlled adherence to specifications. Test injections within the ore deposit of the Konrad mine have been carried out to prove feasability. (orig.)

  14. Preliminary assessment of noble gas bundle tagging using a partial krypton backfill

    International Nuclear Information System (INIS)

    Current limitations of CANDU reactors to reliably locate defective fuel bundles have sparked interest into new identification techniques. Noble gas tagging, which would involve the addition of specific combinations of Kr and Xe isotopes to the fuel-to-sheath gap during manufacturing, has the potential to offer a means of locating failed-fuel bundles. The released tag with a given isotopic signature could be measured in the primary heat transport system by mass spectrometry. This technique would allow on-power failure location. Moreover, the technique could be of particular interest for demonstration irradiations with new fuel bundle designs. This report outlines preliminary considerations towards a suitable tag isotope choice and discusses the impact on the thermal performance of a fuel element. The detection limit of two mass spectrometer systems was determined through measurements of prepared krypton samples with aqueous concentrations in the range of 10-12 to 10-9 [molKr/molH2O]. (author)

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

    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)

  17. Cemented backfilling technology with unclassified tailings based on vertical sand silo

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new technology characterized by rapidly non-mechanical settlement of unclassified tailings was developed based on a large number of tests,and dynamic settlement and continual slurry preparation without hardening in vertical sand silo were eventually realized by the addition of an effective flocculating agent (NPA).The results show that the sedimentation velocity of interface between unclassified tailings and water after the addition of NPA increases by 10-20 times,the sedimentation mass fraction of unclassified tailings at the bottom of vertical sand silo is up to 64%,the solid particle content of waste water meets the national standard,and the side influences of NPA can be removed by the addition of fly ash.The industrial test result shows that the system,the addition manner and the equipments are rational,and the vertical sand silo is used efficiently.This developed system is simple with large throughput,and the processing cost is 2.2 yuan(RMB)/m3,only 10%-20% of that by mechanical settlement.

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

    International Nuclear Information System (INIS)

    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/m3. 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 m3 (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 m3 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)

  20. Benefits/impacts of utilizing depleted uranium silicate glass as backfill for spent fuel waste packages

    International Nuclear Information System (INIS)

    An assessment has been made of the benefits and impacts which can be derived by filling a spent nuclear fuel multi-purpose canister with depleted uranium silicate (DUS) glass at a reactor site. Although the primary purpose of the DUS glass fill would be to enhance repository performance assessment and control criticality of geologic times, a number of benefits to the waste management system can be derived from adding the DUS glass prior to shipment from the reactor site

  1. 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.

  2. Laboratory Study on the Use of Tire Shreds and Rubber-Sand in Backfilled and Reinforced Soil Applications

    OpenAIRE

    Bernal, Andres; Lovell, C. W.; Salgado, Rodrigo

    1996-01-01

    Millions of scrap tires are discarded annually in the United States, the bulk of which are currently landfilled or stockpiled. This consumes valuable landfill space, or, if improperly disposed, creates a fire hazard and provides a prolific breeding ground for rats and mosquitoes. The use of tire shreds as lightweight fill material can sharply reduce the tire disposal problem. The present study, based on laboratory testing and numerical modeling examines the feasibility of incorporating tire s...

  3. Application of a Backfilling Method in Coal Mining to Realise an Ecologically Sensitive “Black Gold” Industry

    OpenAIRE

    Xiaowei Feng; Nong Zhang; Lianyuan Gong; Fei Xue; Xigui Zheng

    2015-01-01

    China, as the largest coal-producing and -consuming country in the world, is highly dependent on its coal industry, or “Black Gold” industry, for the national energy and economy. The consequent environmental crises, however, have persisted for decades, and the most serious effect is surface subsidence induced by underground mining. Underground coal excavation in China has ignored this problem for thousands of years, even though it causes conspicuous damage to the surface ecosystem and constru...

  4. Chemical, physical and engineering characterization of candidate backfill clays and clay admixtures for a nuclear waste repository-Part I

    International Nuclear Information System (INIS)

    Fourteen Canadian clays and clay admixtures were subjected to simulated nuclear waste repository environments. The present work is concerned with the montmorillonite-dominant materials only. The montmorillonite-dominant samples showed significant leaching on interaction with deionized water. On heating the samples at 2000C for 500 hours, montmorillonites lost intermicellar water completely and acquired cusp-like to cylindrical morphologies. The loss of water and the morphological changes in montmorillonites significantly altered the engineering characteristics. Permeability, shrinkage limits, compactability and shear strength varied in response to the dominant exchange cation in the structure of montmorillonites and the presence of other mineral components in the materials. The synthetic granite water reacted with montmorillonites and led to changes in chemical and mineralogical compositions, crystalline state and engineering properties. 12 figures, 9 tables

  5. An experimental investigation of the temperature behavior of a CANDU 37-element spent fuel bundle with air backfill

    International Nuclear Information System (INIS)

    As part of the thermal analysis of a CANDU spent fuel dry storage system, a series of experiment has been conducted using a thermal mock-up of a simulated CANDU spent fuel bundle in a dry storage basket. The experimental system was designed to obtain the maximum fuel rod temperature along with the radial and axial temperature distributions within the fuel bundle. The main purpose of these experiments was to characterize the relevant heat transfer mechanisms in a dry, vertically oriented CANDU spent fuel bundle, and to verify the MAXROT code developed for the thermal analysis of a CANDU spent fuel bundle in a dry storage basket. A total of 48 runs were made with 8 different power inputs to the 37-element heater rod bundle ranging from 5 to 40 W, while using 6 different band heaters power inputs from 0 to 250 W to maintain the basket wall at a desired boundary condition temperature at the steady state. The temperature distribution in a heater rod bundle was measured and recorded at the saturated condition for each set of heater rod power and band heaters power. To characterize the heat transfer mechanism involved, the experimental data were corrected analytically for radiation heat transfer and presented as a Nusselt number correlation in terms of the Rayleigh number of the heater rod bundle. The results show that the Nusselt number remains nearly constant and all the experimental dada fall within a conduction regime. The experimental data were compared with the predictions of the MAXROT code to examine the code's accuracy and validity of assumptions used in the code. The MAXROT code explicitly models each representative fuel rod in a CANDU fuel bundle and couples the conductive and radiative heat transfer of the internal gas between rods. Comparisons between the measured and predicted maximum fuel rod temperatures of the simulated CANDU 37-element spent fuel bundle for all 48 tests show that the MAXROT code slightly over-predicts and the agreement is within 2.8 % with a mean deviation of 3.2/circ C. Based on the above results, it is concluded that the MAXROT code can be used in the second step of the two-step thermal analysis method, proposed to obtain the maximum fuel rod temperature of the CANDU 37-element spent fuel bundle within a fuel basket in a given spent fuel dry storage canister with an uncertainty of about 2.8 %

  6. 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)

    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)

  7. Numerical simulation of heat dissipation processes in underground power cable system situated in thermal backfill and buried in a multilayered soil

    International Nuclear Information System (INIS)

    Highlights: • A practical thermal analysis of underground power cable system. • The geological measurements were performed for cable line placement location. • Dry zone formation effect included in soil and FTB thermal conductivity formula. • A simplified FEM model of underground power cable system. • The computational numerical code validation with ANSYS. - Abstract: This paper presents the thermal analysis of the underground transmission line, planned to be installed in one of the Polish power plants. The computations are performed by using the Finite Element Method (FEM) code, developed by the authors. The paper considers a system of three power cables arranged in flat (in-line) formation. The cable line is buried in the multilayered soil. The soil layers characteristic and thermal properties are determined from geological measurements. Different conditions of cable bedding are analyzed including power cables placement in the FTB or direct burial in a mother ground. The cable line burial depth, measured from the ground level, varies from 1 m to 2.5 m. Additionally, to include the effect of dry zones formation on the temperature distribution in cable line and surroundings, soil and FTB thermal conductivities are considered as a temperature-dependent. The proposed approach for determining the temperature-dependent thermal conductivity of soil layers is discussed in detail. The FEM simulation results are also compared with the results of the simulation that consider soil layers as homogeneous materials. Therefore, thermal conductivity is assumed to be constant for each layer. The results obtained by using the FEM code, developed by the authors, are compared with the results of ANSYS simulations, and a good agreement was found

  8. Analysis of Factors Affecting the Compressive Strength of Cemented Backfill%胶结充填体抗压强度的影响因素分析

    Institute of Scientific and Technical Information of China (English)

    杨安国; 周宗红; 张秋华

    2014-01-01

    This paper introduces some factors influencing the compressive strength of cemented filling body, in order to demonstrate that the compressive strength of cemented filling body is affected by cementitious materials, inert material, slurry concentration, material ratio and curing conditions. In addition, this paper also points out some problems in mine cemented filling process and the improvement direction.%本文通过介绍影响胶结充填体抗压强度的若干因素,目的是为了说明胶结充填体抗压强度受到胶凝材料、惰性材料、料浆浓度以及物料配比和养护条件等因素的影响。此外,本文还指出了目前矿山胶结在充填过程中存在的一些问题以及改进的方向。

  9. Application of a Backfilling Method in Coal Mining to Realise an Ecologically Sensitive “Black Gold†Industry

    OpenAIRE

    Xiaowei Feng; Nong Zhang; Lianyuan Gong; Fei Xue; Xigui Zheng

    2015-01-01

    China, as the largest coal-producing and -consuming country in the world, is highly dependent on its coal industry, or “Black Gold†industry, for the national energy and economy. The consequent environmental crises, however, have persisted for decades, and the most serious effect is surface subsidence induced by underground mining. Underground coal excavation in China has ignored this problem for thousands of years, even though it causes conspicuous damage to the surface ecosystem and cons...

  10. Reliability Analysis of High Level Backfill Based on Chaotic Optimization%震后房屋评价模型的改进

    Institute of Scientific and Technical Information of China (English)

    王楠楠; 王存睿; 高云莉; 王庆春

    2011-01-01

    科学的评定震后的已损毁建筑对震后房屋处理,城市功能的及时恢复,社会生产稳定、生活秩序的恢复等,具有重要的现实意义.针对传统震后的损毁房屋评价模型的不足,提出了一种震后房屋危险性鉴定的评价模型,结合AHP方法,利用实际中各种因素影响的权重构建了相应的模糊隶属度函数,计算地震损毁房屋的等级.利用真实地震中的房屋数据对该方法进行了测试和分析,实验结果表明该方法是科学、有效的,可以一定程度提高震后房屋鉴定的准确性和合理性.%Scientific assessment of damaged buildings after earthquake is very important to the building processing, the timely restoration of urban functions, stability of social production and living order of restoration. In this paper, after analyzed the traditional evaluation model of the earthquake damaged housing, presents a risk assessment identification model for housing after eart hquake, combined with AHP method, using the actual impact of various factors in the weights of the corresponding construct fuzzy function, calculate the level of earthquake damage to building. In this paper, the real earthquake of building data test this method, experimental results indicate that this method is scientific and effectively, improve the identification accurate and rationality.

  11. Field surface backfill grouting and excavation and supporting technology of tunnel shallow unsymmetrial loading sector%隧道浅埋偏压段地表回填注浆及开挖支护施工技术

    Institute of Scientific and Technical Information of China (English)

    杨帆

    2007-01-01

    在六潜高速公路磨子潭1#隧道六安端进口浅埋段施工中,采用浅埋段施工挡土墙、水泥稳定碎石土分层回填及地表注浆加固、顶推套拱进洞、钢管注浆超前支护、预留核心土开挖、围岩量测、注浆加强初期支护、偏压加强衬砌等技术措施.施工证明上述施工技术能够保证偏压、浅埋及软弱围岩隧道施工时确保施工期间及后期安全,取得良好效果.

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

    International Nuclear Information System (INIS)

    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. Research and development of measures to be taken for long term stabilization and isolation of uranium mill tailings

    International Nuclear Information System (INIS)

    This paper contains results of research on the environmental impact of uranium mill tailings used for backfilling mined-out voids from uranium ore mining at Zhovty Vody. The general objective of the research was a comparison of qualitative and quantitative characteristics of the performance of using mill tailings as backfilling instead of the customary sand. Specifically the backfill massif strengths, the radiation impact on the mine staff, possible groundwater contamination with radionuclides from the backfill massif, and air and soil contamination with dust and gas emissions from the mine and the backfill mixing plant were investigated. It was concluded that the use of tailings as a backfill material would be feasible, both from a technical as well as an environmental impact point of view. (author)

  14. Studies on direct ultimate disposal of spent fuel elements. Pt. 1

    International Nuclear Information System (INIS)

    The activities reported encompass the demonstration and optimization of the backfilling technique applied for waste emplacement in drifts, the validation of thermal and thermomechanical models, and the simulation of the thermomechanical interactions between waste product dummies, backfilling material and surrounding rock. The current status of work and the results describing the thermal and thermomechanical reactions of backfill and rock are given, as well as the results of in situ density measurements in the backfill and of gas formation. The data have been recorded and processed for a central database. (DG)

  15. Sensitivity study of the coupled convergence/compaction model

    International Nuclear Information System (INIS)

    A sensitivity study on the coupled convergence/compaction behaviour of backfilled openings is performed. Hereto, a backfilled gallery, which is an example of a relevant situation in a mined repository was considered. The behaviour of a gallery with various types of backfill mixes, such as dry crushed course-grained salt, crushed salt with brine and brine-saturated salt, was investigated. The sensitivity to the variation of the relevant input parameters in a coupled convergence/compaction model developed at ECN was determined. Furthermore, the asymptotic behaviour from wet backfill to dry backfill was investigated. Generally, it can be concluded that the brine content, the initial porosity of the backfill mix as well as the grain size are the dominant parameters in the coupled convergence/compaction relationships. The evolution of the compaction rate in the case of a gallery with dry backfill can be reasonably well described with a general relationship for wet backfill and a proper set of values for the backfill mix parameters. (orig.)

  16. 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)

  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. 30 CFR 917.12 - State regulatory program and proposed program amendment provisions not approved.

    Science.gov (United States)

    2010-07-01

    ... completely incised or created by a depression left by backfilling and grading but not meeting MSHA requirements at 30 CFR 77.216 or not meeting the Class B and C classifications at section 1(10)(b) is not... depression left by backfilling and grading, that is not a sedimentation pond or coal mine waste...

  19. 77 FR 46107 - Notice of Intent To Prepare an Environmental Impact Statement for the Proposed Husky 1-North Dry...

    Science.gov (United States)

    2012-08-02

    ..., temporary and permanent overburden storage areas, storm water retention ponds and mine pit backfill areas... overburden backfill. Agrium has proposed management practices in its mine and reclamation plan to reduce... Mine Project include potential effects on groundwater and surface water quantity and quality; uptake...

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

    International Nuclear Information System (INIS)

    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

  1. 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)

    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.

  2. Bulkhead pressure measurements in model fill pours

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, R.J.; Roettger, J.J.

    1984-08-01

    The results of a series of model stope pours designed to investigate working pressures on bulkheads during hydraulic pouring of classified tailings backfill are reported. Total bulkhead pressures and fill water pressures were monitored under the condition of a fully saturated backfill. Similitude of the model testing is discussed and equations are developed to estimate bulkhead pressures under prototype conditions. The model results show that good base drainage, combined with a bulkhead setback, can reduce the expected bulkhead pressures to values such that timber or concrete block structures should be capable of supporting a saturated backfill.

  3. Migration and diffusion of radionuclides in engineered barrier system

    International Nuclear Information System (INIS)

    This paper describes the present status of the multibarrier system performance tests to provide a preliminary assessment of nuclide migration in the engineered barriers for shallow land burial of the low-level radioactive waste. Migration of radionuclides with seeped water through backfill and in subsequent diffusion in concrete pit are considered in this study. The results of laboratory investigations of unsaturated flow in backfill and radionuclides migration / diffusion in engineered barrier system are described and the calculated distribution of the radionuclides in backfill is presented

  4. Loviisa Power Station - final disposal of reactor waste

    International Nuclear Information System (INIS)

    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

  5. Ring exciting thin layer method applied to the forced vibration test of the Hualien large scale soil-structure interactions (SSI) model

    International Nuclear Information System (INIS)

    The blind prediction and post-test correlation analyses are conducted on the forced vibration tests of the 1/4 scale reinforced concrete cylindrical containment model both before and after backfill. In the present paper described for the case after backfill, the ring exciting thin layer technique was introduced to account realistically for the axisymmetrical irregularity of the soil condition due to the backfill. The computed results demonstrated that the proposed method has a great potential for simulating the dynamic responses of the soil-structure system to the forced vibration. (author). 5 refs., 8 figs

  6. Cumulative releases of radionuclides from uncontained waste packages

    International Nuclear Information System (INIS)

    This report describes mathematical predictions for the migration of radionuclides from an emplaced radioactive waste container. The model assumes a spherical-equivalent waste solid surrounded by backfill but neglects the effect of decay heat. 7 refs., 2 tabs

  7. 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...

  8. 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...

  9. Clay modified crushed salt for shaft sealing elements. Material optimization and evaluation in field tests

    International Nuclear Information System (INIS)

    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.

  10. 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.

  11. 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

  12. Evaluation of low-pH cement degradation in tunnel plugs and bottom plate systems in the frame of SR-Site

    International Nuclear Information System (INIS)

    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

  13. Study on forced vibration tests for large scale SSI model. Test results and their analysis

    International Nuclear Information System (INIS)

    A Large-Scale Seismic Test (LSST) Program has been conducted at Hualien, Taiwan, to obtain earthquake-induced soil-structure interaction (SSI) data in a stiff soil site environment. Forced vibration tests of the Hualien 1/4-scale containment SSI test model were conducted in October, 1992 before backfill (without embedment) and in February, 1993 after backfill (with embedment) for the purpose of defining basic dynamic characteristics of the soil-structure system. As results, peak frequencies were obtained as 4.1 and 4.3 Hz with twin peaks for both NS and EW horizontal excitation before backfill and as 6.1 and 6.3 Hz for NS and EW excitation respectively after backfill and orthogonal components were rather large. This results suggested existence of principal axes which were different from excitation directions. They were estimated 34 degree before backfill and 30 degree after backfill counterclockwise from NS direction, respectively. After transformed to the principal axes, each resonance curve had single peak and the orthogonal component became negligible. Based on this transformed results, the basic dynamic characteristics of the soil-structure system were obtained, namely, natural frequencies and damping factors. Soil impedances were also obtained by the method minimizing error function defined newly. (author)

  14. Behavior of crushed salt under heat source in boreholes in a salt mine (Amelie Mine, Alsace Potash Mines, France)

    International Nuclear Information System (INIS)

    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 1000C during the first field test and 1300C 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

  15. Tests for evaluation of pellets as foundation bed material KBP1003 - ASKAR

    International Nuclear Information System (INIS)

    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

  16. 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

  17. Drafting of the closure of the Asse salt mine. Final report

    International Nuclear Information System (INIS)

    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.)

  18. Movement and deformation laws of the overlying strata in paste filling stope

    Institute of Scientific and Technical Information of China (English)

    Xu Ying; Chang Qingliang; Zhou Huaqiang; Cao Zhong; Li Xiushan; ChenJianhang

    2011-01-01

    We combined the similar simulation with numerical simulation to analyze the movement and deformation features of overlying strata caused by paste backfill mining,study the movement and deformation laws of the overlying strata in paste backfill mining,structural movement of the stope strata as well as the stope stress distribution laws.Furthermore,authors also explored the key factors to the movement and deformation of the overlying strata in paste backfill mining.The results indicate that a caving zone existed in the bending zone only in the overlying strata of the paste backfill mining.Compared with the roof caving mining,the degree of stress concentration and area of influence in the paste filling stope were apparently smaller.And the degree of destruction and area of the overlying strata decreased prominently.Also,there was no apparent strata behavior in the working face.Lastly,the filling ratio was the key to control the movement and deformation of the overlying strata.Combined with a specific engineering example,the author proved the reliability of the simulation results and provided a theoretical basis for the further extension of the paste backfill mining.

  19. Thermo-mechanical analysis for determining the optimum design of a deposition hole using FLAC3D

    International Nuclear Information System (INIS)

    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

  20. Preliminary conceptual designs for advanced packages for the geologic disposal of spent fuel

    International Nuclear Information System (INIS)

    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

  1. Waste-filling in fully-mechanized coal mining and its application

    Energy Technology Data Exchange (ETDEWEB)

    Xie-xing Miao; Ji-xiong Zhang; Mei-mei Feng [China University of Mining and Technology, Xuzhou (China). State Key Laboratory for Geomechanics and Deep Underground Engineering

    2008-12-15

    A fully-mechanized coal mining (FMCM) technology capable of filling up the goaf with wastes (including solid wastes) is described. Industrial tests have proved that by using this technology not only can waste be re-used but also coal resources can be exploited with a higher recovery rate without removing buildings located over the working faces. Two special devices, a hydraulic support and a scraper conveyor, run side-by-side on the same working face to simultaneously realize mining and filling. These are described in detail. A case study of waste backfilling during FMCM was performed in the Shandong mining area in China. The process will increase costs by 20-30 RMB per ton of coal. However waste backfilling avoids costs of having to more building in the surface. The tests allow analysis of rock pressure and ground subsidence when backfilling techniques are employed. These values are compared to those from mining without using backfilling techniques, under the same geological conditions. The concept of equivalent mining height is proposed based on theoretical analysis of rock pressure and ground subsidence. The upper limits of the rock pressure and ground subsidence can be estimated in backfilling mining using this concept along with traditional engineering formulae. 6 refs., 6 figs., 1 tab.

  2. MCO gas composition for low reactive surface areas

    International Nuclear Information System (INIS)

    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)

  3. MCO gas composition for low reactive surface areas

    Energy Technology Data Exchange (ETDEWEB)

    Packer, M.J.

    1998-07-23

    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).

  4. Neon as a Buffer Gas for a Mercury-Ion Clock

    Science.gov (United States)

    Prestage, John; Chung, Sang

    2008-01-01

    A developmental miniature mercury-ion clock has stability comparable to that of a hydrogen-maser clock. The ion-handling components are housed in a sealed vacuum tube, wherein a getter pump is used to maintain the partial vacuum, and the evacuated tube is backfilled with mercury vapor in a buffer gas. Neon was determined to be the best choice for the buffer gas: The pressure-induced frequency pulling by neon was found to be only about two-fifths of that of helium. Furthermore, because neon diffuses through solids much more slowly than does helium, the operational lifetime of a tube backfilled with neon could be considerably longer than that of a tube backfilled with helium.

  5. The solubility limited source term for cement-conditioned wastes: A status report

    International Nuclear Information System (INIS)

    An important function of the cement backfill in a nuclear waste repository is to react with aqueous waste species and reduce their solubility. However, to quantify backfill performance it is first necessary to prove the existence and establish the nature of the chemical solubility controls. This can be done by characterizing the solubility-limiting phases, determining their solubility and thermodynamic functions, and assessing their stability and persistence and solubility during backfill degradation. Much of the necessary data must be acquired experimentally. The title paper describes briefly the progress of experimental work on selected species including nickel, chromium(III,VI), tin(IV), molybdenum(VI), uranium(VI), Ce(III,IV), thorium, actinide simulants (III,IV) and chloride. Data needs are assessed and although much experimental work remains to be done, methodologies have been developed which will expedite progress. The expectation of a more quantitative performance assessment of cement barriers is, therefore, attainable

  6. Studies for scenario modelling of conditions in the nearfield of a heat-affected repository compartment in salt rock

    International Nuclear Information System (INIS)

    It is supposed that in the nearfield of heat-generating wastes a number of thermally induced processes will occur that will have significant effects on the existing brine systems. Analyses considering ingress of brines into the nearfield of a heat-generating waste form cover inter alia such conditions as brine inflow into a not fully converged mine drift, brine penetrating the backfilling material, dissolution and re-dissolution processes in the system brine/backfilling material under the influence of the temperature field, and compacting of the backfilling material due to water evaporation from the brine and crystallisation of the salt content. The scenarios developed are taken as a basis for improving the precision of models describing the nearfield processes. (DG)

  7. Mass transfer and transport in a geologic environment

    International Nuclear Information System (INIS)

    This report is in a continuing series of reports that present analytic solutions for the dissolution and hydrogeologic transport of radionuclides from geologic repositories of nuclear waste. Previous reports have dealt mainly with radionuclide transport in the far-field, away from the effects of the repository. In the present report, the emphasis is on near-field processes, the transfer and transport of radionuclides in the vicinity of the waste packages. The primary tool used in these analyses is mass transfer theory from chemical engineering. The thrust of our work is to develop methods for predicting the performance of geologic repositories. The subjects treated in the present report are: radionuclide transport from a spherical-equivalent waste form through a backfill; analysis of radionuclide transport through a backfill using a non-linear sorption isotherm; radionuclide transport from a prolate spheroid-equivalent waste form with a backfill; radionuclide transport from a spherical-equivalent waste form through a backfill, where the solubility, diffusivity and retardation coefficients are temperature dependent; a coupled near-field, far-field analysis where dissolution and migration rates are temperature dependent; transport of radionuclides from a point source in a three-dimensional flow field; and a general solution for the transport of radioactive chains in geologic media. There are several important results from the numerical evaluations. First, radioactive decay, higher sorption in the rock and the backfill steepens the gradient for mass transfer, and lead to higher dissolution rates. This is contrary to what was expected by some other workers, but is shown clearly in the analytical solutions. Second, the backfill serves to provide sorption sites so that there is a delay in the arrival of radionuclides in the rock, although this effect is not so important for the steady-state transport of long-lived radionuclides

  8. The ESDRED project: Engineering studies and demonstration of repository designs

    International Nuclear Information System (INIS)

    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 m3 backfilled in 4 hours

  9. Laboratory corrosion tests on candidate high-level waste container materials: Results from the Belgian programme

    International Nuclear Information System (INIS)

    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 ENP and the protection potential EPP. 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)

  10. Feasibility and economic consequences of retrievable storage of radioactive waste in the deep underground

    International Nuclear Information System (INIS)

    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 cheapter than the first. This has been done for clary, granite and rocksalt as host formation, and both for vitrified waste and spent fuel. (orig.)

  11. Radionuclide source term and migration

    International Nuclear Information System (INIS)

    Progress in two types of experiment is reported. In the first the equilibrium and concentration of radionuclides in groundwater in contact with real radioactive wastes are measured. Container material, backfill material and rock are added to groundwater to investigate their effects. In the second experiment the retardation of radionuclides leached from wastes as groundwater flows over samples of container, backfill and geological material is measured. Outflow is analysed for radionuclides and experimental results for cesium 134, cesium 137 and cobalt 60 are presented. (U.K.)

  12. Spent nuclear fuel storage -- Performance tests and demonstrations

    International Nuclear Information System (INIS)

    This report summarizes the results of heat transfer and shielding performance tests and demonstrations conducted from 1983 through 1992 by or in cooperation with the US Department of Energy (DOE), Office of Commercial Radioactive Waste Management (OCRWM). The performance tests consisted of 6 to 14 runs involving one or two loadings, usually three backfill environments (helium, nitrogen, and vacuum backfills), and one or two storage system orientations. A description of the test plan, spent fuel load patterns, results from temperature and dose rate measurements, and fuel integrity evaluations are contained within the report

  13. Direct methods of soil-structure interaction analysis for earthquake loadings

    Energy Technology Data Exchange (ETDEWEB)

    Yun, J. B.; Kim, J. M.; Kim, Y. S. and others [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1993-07-15

    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.

  14. Surface-immobilized pyridine-functionalized gamma-cyclodextrin: alkanethiol co-adsorption-induced reorientation.

    Science.gov (United States)

    Mallon, Colm T; Forster, Robert J; McNally, Andrea; Campagnoli, Elena; Pikramenou, Zoe; Keyes, Tia E

    2007-06-19

    Monolayers of di-6A,6B-deoxy-6-(4-pyridylmethyl)amino-gamma-cyclodextrin (gamma-CD-(py)2) have been formed on polycrystalline platinum electrodes and investigated using electrochemical and surface-enhanced Raman spectroscopy (SERS). The behavior of self-assembled monolayers of (gamma-CD-(py)2) alone, (gamma-CD-(py)2) backfilled with 1-nonanethiol, and 1-nonanethiol are reported. The potential dependence of the capacitance indicates that the film capacitance is higher for the backfilled CD layers than for 1-nonanethiol layers, most likely due to ion flux through the CD cavity. SERS spectra of the backfilled layer exhibit features associated with both pyridine-functionalized CD and alkane moieties. Investigations using [Fe(CN)6]4- as a solution-phase probe indicate that the backfilled CD-alkane thiol layer exhibits enhanced blocking properties compared to gamma-CD-(py)2 films alone. Complete blocking was achieved by a combination of backfilling and insertion of a high-affinity guest 1-adamantylamine into the cavity. Significantly, an electroactive guest with high affinity for gamma-CD, [Co(biptpy)2]2+, does not exhibit a redox response at the gamma-CD-(py)2 layer but molecular recognition is turned on by backfilling the CD layer with 1-nonanethiol molecules. This switching on of the electrochemical activity suggests that the CD hosts are initially inaccessible but reorientate upon backfilling, exposing the CD opening to solution and permitting a supramolecular host-guest complex to form. The binding of [Co(biptpy)2]2+ to gamma-CD in the backfilled monolayer depends on the bulk concentration of guest and is modeled by the Langmuir isotherm, yielding an association constant for the Co2+ state of 1.45 +/- 0.46 x 105 M-1 and a limiting surface coverage 1.49 +/- 0.25 x 10-11 mol cm-2. The surface coverage of the divalent state is higher than the trivalent state, reflecting the dynamic nature of the inclusion. PMID:17521206

  15. Development of Multiple Cement Mixture and Its Applied Technology

    Science.gov (United States)

    Sun, Jie; Li, Qiaoling; Liu, Feng; Liu, Shipeng

    Currently, materials used to backfill grooves in municipal pipeline projects are pure soil and lime earth generally. Besides, punning or rolling compaction is used. Thus, it is difficult to compact or tamp haunches under pipes. Because of immersion of surface water and activities of underground water and as water inside pipes or underground structures leaks outward, fine-grained soil in backfill move with activities of underground water and collapse is caused for ground. This thesis mainly introduces multiple cement mixture and its performance.

  16. Selection of bentonite deposits

    International Nuclear Information System (INIS)

    The selection of bentonite deposits is to offer a supply base of backfill/buffer materials for high-level radioactive waste repository in China. In this paper the comprehensive evaluation criteria were discussed first, then a comprehensive comment on bentonite deposits in China was given. The properties of geographic distribution, origin, reserves and ore quality of bentonite deposits were also discussed. The comprehensive comparison studies on 12 large-sized bentonite deposits was presented. Based on the results obtained Gaomiaozi bentonite deposit, Inner Mongolia, was recommended as the first choice of backfill/buffer materials for repository in China. (author)

  17. 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.

  18. Rock segments for reducing the amount of cement used on high-level radioactive waste disposal

    International Nuclear Information System (INIS)

    Methods for constructing tunnels using the minimum quantities of cement-type support materials in high-level radioactive waste disposal facilities have been developed. Research and development concerning the technical aspects of the formation of rock segments using low alkali mortar have been conducted. This study examined the mechanical characteristics of rock segments and backfill materials and analyzed the stability of the drift that is supported by the rock segments and gravel backfill. The results confirmed the technical aspects of the formation of the rock segments and the effectiveness of the planned efforts to further reduce the amount of cement used. (author)

  19. Development of rock segment for reduction of amount of cement use

    International Nuclear Information System (INIS)

    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)

  20. Soil density and mass attenuation coefficients for use in shielding calculations at the Hanford Waste Vitrification Plant

    International Nuclear Information System (INIS)

    Compacted, backfilled soil excavated during construction may be used to provide shielding from gamma radiation at the Hanford Waste Vitrification Plant (HWVP). To provide a reasonable estimate of the shielding offered by this backfilled soil, the bulk density and the composition of the emplaced soil must be specified. This study provides an estimate of the bulk density and the mass attenuation coefficients of soil used for calculating gamma-ray shielding attenuation at the HWVP. These estimates are based on measurements taken from soil samples and underlying rock samples at the Hanford Site

  1. A disposal centre for irradiated nuclear fuel: conceptual design study

    International Nuclear Information System (INIS)

    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)

  2. Digital Format for Depositary Part of Scientific Publications' Collection

    Science.gov (United States)

    Zemskov, Andrei; Evstigneeva, Galina

    As a rule, any large library has so called depositary part of collection. Specific circulation of these publications is not high, but preservation, conservation and provision of access to given collection need permanent efforts. The paper presents evaluation of expenses and centralized systems efficiency. These systems (e.g. JSTOR, Backfiles for Future) are publicly accessible collections of full text versions of scientific periodicals.

  3. Slurry walls and slurry trenches - construction quality control

    International Nuclear Information System (INIS)

    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

  4. 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…

  5. 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.

  6. 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.

  7. Field Measurements and Pullout Tests of Reinforced Earth Retaining Wall

    Institute of Scientific and Technical Information of China (English)

    陈群; 何昌荣; 朱分清

    2004-01-01

    In this paper, field measurements and pullout tests of a new type of reinforced earth retaining wall, which is reinforced by trapezoid concrete blocks connected by steel bar, are described. Field measurements included settlements of the earth fill, tensile forces in the ties and earth pressures on the facing panels during the construction and at completion. Based on the measurements, the following statements can be made: ( 1 ) the tensile forces in the ties increased with the height of backfill above the tie and there is a tensile force crest in most ties; (2) at completion, the measured earth pressures along the wall face were between the values of the active earth pressures and the pressures at rest; (3) larger settlements occurred near the face of the wall where a zone of drainage sand and gravel was not compacted properly and smaller settlements occurred in the well-compacted backfill. The results of field pullout tests indicated that the magnitudes of pullout resistances as well as tensile forces induced in the ties were strongly influenced by the relative displacements between the ties and the backfill, and pullout resistances increased with the height of backfill above the ties and the length of ties.

  8. Importance of the source term for the release of radionuclides from a repository in a salt dome

    International Nuclear Information System (INIS)

    The release of radionuclides from a backfilled and brine saturated repository in a salt dome is analyzed as a function of canister lifetimes and solubility limits. The relationship between the waste package and the multi-barrier system of the repository is discussed

  9. 76 FR 72901 - Notice of Petitions by Firms for Determination of Eligibility To Apply for Trade Adjustment...

    Science.gov (United States)

    2011-11-28

    ... Missoula, MT 59808. attachments for excavators and backfill equipment and other attachments and parts for heavy equipment. Modular Sound System, Inc 22272 Pepper Road, 15-Nov-11 The firm manufactures Barrington... and surrounds, and also distributes, installs and resells kitchen and bathroom cabinets, sinks,...

  10. Evaluation of radionuclides migration in environment

    International Nuclear Information System (INIS)

    Radioactive waste management is one of the most pressing problems facing the world today because of its long half-life and the transport of radionuclides to the environment. The migration of radionuclides in environment is affected by its sorption in backfill materials, water pore velocity, water flowing direction, dispersion of radionuclides, components of backfill materials, species of radionuclides, microorganism effect and complexation ability of organic substances etc. In this study, the distribution coefficient of Eu(III) derived from batch experiments is used to evaluate the migration behavior of Eu(III) in compacted bentonite after long time. The effect of the dispersion coefficient and the pore water velocity on the migration of Eu(III)is also calculated. It is found that the variation of the distribution coefficient and water velocity has an obviously effect on the migration of Eu(III) in backfill materials and 30 m of the backfill materials is sufficient to prevent the migration of Eu(III) in environment. The dispersion coefficient has little effect on the migration of Eu(III). The evaluated results are applicable to estimate the escape of radionuclides from buried radioactive waste to the environment. (authors)

  11. Conference summaries

    International Nuclear Information System (INIS)

    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

  12. Efficient Subtorus Processor Allocation in a Multi-Dimensional Torus

    Energy Technology Data Exchange (ETDEWEB)

    Weizhen Mao; Jie Chen; William Watson

    2005-11-30

    Processor allocation in a mesh or torus connected multicomputer system with up to three dimensions is a hard problem that has received some research attention in the past decade. With the recent deployment of multicomputer systems with a torus topology of dimensions higher than three, which are used to solve complex problems arising in scientific computing, it becomes imminent to study the problem of allocating processors of the configuration of a torus in a multi-dimensional torus connected system. In this paper, we first define the concept of a semitorus. We present two partition schemes, the Equal Partition (EP) and the Non-Equal Partition (NEP), that partition a multi-dimensional semitorus into a set of sub-semitori. We then propose two processor allocation algorithms based on these partition schemes. We evaluate our algorithms by incorporating them in commonly used FCFS and backfilling scheduling policies and conducting simulation using workload traces from the Parallel Workloads Archive. Specifically, our simulation experiments compare four algorithm combinations, FCFS/EP, FCFS/NEP, backfilling/EP, and backfilling/NEP, for two existing multi-dimensional torus connected systems. The simulation results show that our algorithms (especially the backfilling/NEP combination) are capable of producing schedules with system utilization and mean job bounded slowdowns comparable to those in a fully connected multicomputer.

  13. Visualization of microscale phase displacement proceses in retention and outflow experiments: nonuniquensess of unsaturated flow properties

    DEFF Research Database (Denmark)

    Mortensen, Annette Pia; Glass, R.J.; Hollenbeck, K.J.;

    2001-01-01

    we observe the drainage process to be composed of a mixture of fast air fingering and slower air back-filling. The influence of each of these microscale processes is controlled by a combination of the size and the speed of the applied boundary step, the initial saturation and its structure, and small...

  14. 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 ...

  15. 76 FR 20940 - Troy Mine, Incorporated, Troy Mine Revised Reclamation Plan, Kootenai National Forest, Lincoln...

    Science.gov (United States)

    2011-04-14

    ... Reclamation Plan began with a press release that was published in area newspapers and announced on local TV...-hydraulic plugging (backfilling) of the adits and recontouring the slope of the South Portal patio; Limited... modifications to the Proposed Action: Hydraulic plugs would not be used at the Service and Conveyor...

  16. SES and Acoustics at GSFC

    Science.gov (United States)

    Hogue, Patrick

    2008-01-01

    This paper presents air and surface cleanliness characterization of the acoustics test facility and large (SES) thermal vacuum chamber at Goddard Space flight Center in Greenbelt, MD during the New Horizons Pluto probe program. It is shown that slow back-fill of the SES chamber is necessary to prevent excessive particle redistribution.

  17. Physical and numerical modelling of earth pressure on anchored sheet pile walls in sand

    DEFF Research Database (Denmark)

    Krogsbøll, Anette Susanne; Fuglsang, Leif D

    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 anch...

  18. Recycling of wastes from uranium mining and metallurgy and recovery of useful resources in China

    International Nuclear Information System (INIS)

    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)

  19. 76 FR 11259 - Notice of Intent To Prepare an Environmental Impact Statement for the Proposed Rasmussen Valley...

    Science.gov (United States)

    2011-03-01

    ... Blackfoot Wildlife Management Area, primarily for storm water retention ponds and the county road re...: Send written comments to: Rasmussen Valley Mine EIS, Bureau of Land Management, Pocatello Field Office... overburden storage areas, storm water retention ponds and mine pit backfill areas, a haul road, an...

  20. Environmental management and rehabilitation of the Nabarlek Uranium Mine

    International Nuclear Information System (INIS)

    Environmental protection was considered at Nabarlek since before mining commenced, continued during the mining life and culminated in its decommissioning and rehabilitation. Measures for the protection of the physical environment included: containment of all contaminated waters and treatment of tailing waters, return of the tailings direct to the open pit, backfilling of the open pit, landscaping and revegetation of disturbed area. ills

  1. Research project MAW and HTR fuel element test storage in boreholes (MHV project). Emplacement and borehole sealing techniques (EBT part-project). Final report on project phase October 1, 1989 - December 31, 1992

    International Nuclear Information System (INIS)

    The paper documents the working results of the third project phase from 1.10.89 to 31.12.92. At the beginning, the atmosphere in the repository borehole during the operational and post-operational phase is described. The borehole atmosphere is decisively influenced by gas and humidity releases from the waste forms and the solid rock salt, by the propagation of gases in the unfilled part of the borehole and in the part backfilled with salt grit, and by the permiabilities of the borehole lock and the solid bedrock. Hydrogen gas may be oxidized by an addition agent. The reference concept of borehole storage is the embedding of the waste forms in salt grit. The salt grit backfill required therefore is characterized, and pressure distribution in the backfill during storing of the forms in the borehole is modelled. Finally the flame extinguishing effect of salt grit is described. Safety considerations and a draft concept of a borehole backfill container complete the work of this project phase. (orig./HP)

  2. 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)

  3. Technetium diffusion in clay-based materials under oxic and anoxic conditions

    International Nuclear Information System (INIS)

    Diffusion coefficients were determined for Tc in compacted clay-based materials in both anoxic and oxic environments. The soils were saturated with a synthetic groundwater solution; the principle ions in solution were CA2+, Na+ and Cl-. Anoxic conditions were established by conducting the experiments in low-O2 glove box and by mixing 0.5 wt% powdered Fe with the soils. Under anoxic conditions, apparent diffusion coefficients, Da, were 2/s for Tc in compacted backfill material (a 1:3 mix by dry mass of Lake Agassiz clay and crushed granite aggregate). Distribution coefficients, Kd, for Tc on Lake Agassiz clay and backfill material in anoxic environments were back-calculated from Da values. Based on the Kd values, Tc strongly sorbs on Lake Agassiz clay and backfill under anoxic conditions. Effective diffusion coefficients De, for Tc of 10, 16 and 110 μm2/s were measured in oxic Avonlea bentonite, Lake Agassiz clay and illite-smectite, respectively, at a clay dry bulk density of ∼ 1.2 Mg/m3; the corresponding Da values were 55, 48 and 75 μm2/s. Since anoxic conditions are expected in a disposal vault excavated deep in granitic rock in the Canadian Shield, the results suggest the migration of Tc through the backfill will be relatively slow. (author) 23 refs., 9 tabs., 4 figs

  4. 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 st...

  5. 10 CFR 50.10 - License required; limited work authorization.

    Science.gov (United States)

    2010-01-01

    ... Commission requirements in 10 CFR Chapter I applicable to the design of those portions of the facility within... storage sheds, warehouse and shop facilities, utilities, concrete mixing plants, docking and unloading... construction are the driving of piles, subsurface preparation, placement of backfill, concrete, or...

  6. Dissertation Citations in Organismal Biology at Southern Illinois University at Carbondale: Implications for Collection Development

    Science.gov (United States)

    Nabe, Jonathan; Imre, Andrea

    2008-01-01

    We report on a citation analysis of Ph.D. dissertations in plant biology and zoology at Southern Illinois University Carbondale, undertaken to test the common assumption that scientists favor current research to such an extent that journal backfiles can be de-emphasized in academic library collections. Results demonstrate otherwise. The study is…

  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 anch...

  8. Modelling approach for geochemical changes in the Prototype repository engineered barrier system

    International Nuclear Information System (INIS)

    The study deals with a full-scale test of a repository concept for nuclear waste. The work is motivated and targeted to the safety assessment of a final repository for highly active nuclear waste. Successive rounds of predictive modelling are confidence building steps if modelling results can be successfully compared to gradually growing up measured test data. Calculations consider geochemical changes during the wetting of repository tunnel backfill and canister buffer, and the time-dependent changes at the boundaries of a repository engineered barrier system (EBS). The backfill and buffer volumes are divided to uniform subsequent reaction cells. The modelling assumes only schematic coupling between geochemical reactions and hydrologic transport. During a wetting front advance, instant water saturation occurs in subsequent, initially undersaturated, cell volumes. However, a water parcel introduced into a cell is expected to stay within that cell until dissolved components, and solid phases are fully equilibrated. The approach concentrates on the major element compositions of porewaters, and the changes in solid phases of the repository. The initial properties of canister buffer resemble the estimations for compacted Wyoming MX-80 sodium bentonite. The tunnel backfill is assumed to consist of sodium bentonite (30%), and crushed Aespoe diorite (70%) components. The backfill composition has been estimated in accordance with mineral quantities present in the components of the backfill mixture. The initial groundwater sucked into the EBS at the repository boundaries is Na-Ca-(HCO3)-SO4-Cl -water having a reference to brackish seawater origin. The reactions considered are cation exchange, surface complexation, and dissolution/precipitation of certain minerals. Calculations assume also diffuse water layers to occur upon the clay platelet surfaces. As an initial condition, the undersaturated pore volumes of backfill and buffer contain entrapped air (O2 content 20%). In the

  9. The demonstration experiment Thermal Simulation of Drift Emplacement

    International Nuclear Information System (INIS)

    An evaluation is being carried out for disposal of high level waste and spent nuclear fuel in a dual-purpose repository in a salt dome. Only a minor part of the spent fuel from nuclear power plants will be disposed of directly. The major part will be reprocessed. For the dual-purpose repository a reference concept for disposal of high level waste (HLW) and another one for spent fuel was developed. For direct disposal of spent LWR-fuel the reference concept consists of emplacement of self-shielded packages on the floor of emplacement drifts. For saving of space and cost, packages containing spent fuel possibly will be emplaced also in drifts above the filled and sealed HLW-boreholes. Immediately after emplacement of a package the drift will be backfilled with crushed salt. After backfilling the next disposal cask will be emplaced. Emplacement of these casks leads to effects which are rather different from the effects of HLW borehole emplacement. Because heat conductivity of the crushed salt backfill is lower than heat conductivity of compact rock salt, heating of the cask's vicinity will be faster than at borehole emplacement. This has been calculated, but validation of these calculations in experiments is necessary. Another new feature in this emplacement concept is backfilling of heat generating packages with crushed salt. Mathematical models exist for heat propagation, backfill compaction, and drift convergence, but they have to be validated by experiments. The purpose of the demonstration experiment Thermal Simulation of Drift Emplacement is to provide those data which are required for model validation and in a licensing procedure

  10. A study of the operational logistics in the disposal plant for spent nuclear fuel

    International Nuclear Information System (INIS)

    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

  11. 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

  12. 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

  13. Effect of the mineral precipitation-dissolution at tunnel walls during the operational and post-operational phases

    International Nuclear Information System (INIS)

    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 O2(g) and CO2(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(OH)3(am) during

  14. 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

  15. The potential for vault-induced seismicity in nuclear fuel waste disposal: experience from Canadian mines

    International Nuclear Information System (INIS)

    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)

  16. Investigation of sheet steel St 37.2 under mechanical impact

    International Nuclear Information System (INIS)

    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.)

  17. Waste package performance analysis

    International Nuclear Information System (INIS)

    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 107 yr for uranium, plutonium, and americium. 8 references, 6 figures, 9 tables

  18. Models for calculating radionuclide release from the near field

    International Nuclear Information System (INIS)

    Radionuclides released from a damaged canister for spent fuel will leak out through a damage in the canister wall and spread through the surrounding backfill. They will further migrate into water bearing fractures in the rock, up through the backfill into the damaged zone around the drift and into the drift itself. Some substances may also diffuse through the rock to adjacent fracture zones. Underway the nuclides will sorb on the materials along the transport paths. This paper reports that this complex and variable transport geometry has been modelled using a technique where we use the advantage of the Integrated Finite Difference method combined with analytical solution at location where the numerical technique would need a very detailed discretization. Also, another model which is limited for transport calculations at steady state has been developed using the advantages of a network of transport resistance, coupled together in the same way as an electrical circuit network

  19. Progress in the development of waste package performance requirements for a repository located in basalt

    International Nuclear Information System (INIS)

    The Basalt Waste Isolation Project waste package reference conceptual design consists of three components: the waste form, the canister, and the backfill. The waste package system is an engineered barrier in series with two barriers that are in parallel, i.e., the geologic site barrier and the repository seal system barrier (shaft seal, tunnel backfill, and borehole seals). Preliminary analyses of radionuclide transport and release through the waste package system and site geology are presented herein. The effect of a range of postulated groundwater travel times on radionuclide release to the accessible environment is shown. The required values for two waste package performance parameters are shown as a function of groundwater travel time and potential radionuclide release to the accessible environment. 3 references, 4 figures

  20. Behavior of a Nuclear Power Plant Ventilation Stack for Wind Loads

    Science.gov (United States)

    Venkatachalapathy, V.

    2012-05-01

    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.

  1. Effect of residual gaseous impurities on the dewetting of antimonide melts in fused silica crucibles in the case of bulk crystal growth

    Energy Technology Data Exchange (ETDEWEB)

    Sylla, L. [SIMAP-EPM, ENSEEG, BP 75, 38402 Saint Martin d' Heres (France)], E-mail: lamine.sylla@gmail.com; Paulin, J.P.; Vian, G.; Garnier, C.; Duffar, T. [SIMAP-EPM, ENSEEG, BP 75, 38402 Saint Martin d' Heres (France)

    2008-11-15

    A Bridgman set-up has been modified to perform the contactless growth ('dewetting') of gallium and indium antimonide compounds in fused silica crucibles. According to wetting parameters measured by the sessile drop method given in the literature, both molten InSb and GaSb compounds are considered as non-reactive with silica substrates. A detailed description of the experimental set-up is presented. Each polycrystalline sample is inserted in a sealed silica crucible that is backfilled with industrial argon containing a few ppm of oxygen. Under similar experimental conditions, the dewetted growth of GaSb is much easier to obtain than that for InSb. The presence of residual impurities such as oxygen in the backfilling gas appears to enhance the occurrence of the phenomenon for GaSb.

  2. Effect of residual gaseous impurities on the dewetting of antimonide melts in fused silica crucibles in the case of bulk crystal growth

    International Nuclear Information System (INIS)

    A Bridgman set-up has been modified to perform the contactless growth ('dewetting') of gallium and indium antimonide compounds in fused silica crucibles. According to wetting parameters measured by the sessile drop method given in the literature, both molten InSb and GaSb compounds are considered as non-reactive with silica substrates. A detailed description of the experimental set-up is presented. Each polycrystalline sample is inserted in a sealed silica crucible that is backfilled with industrial argon containing a few ppm of oxygen. Under similar experimental conditions, the dewetted growth of GaSb is much easier to obtain than that for InSb. The presence of residual impurities such as oxygen in the backfilling gas appears to enhance the occurrence of the phenomenon for GaSb

  3. The equilibrium leach testing of CAGR hulls

    International Nuclear Information System (INIS)

    Equilibrium leach tests were carried out on a laboratory scale in order to investigate the long-term performance of an intermediate level waste repository. The tests involved leaching fully active Commercial Advanced Gas-cooled Reactor (CAGR) hulls in the presence of crushed matrix and backfill materials. The matrix materials used were blast furnace slag (BFS)/ordinary Portland cement (OPC) and epoxide MS7531/MS7532, and the backfill materials were bentonite and pulverised fuel ash/ordinary Portland cement (PFA/OPC). Comparison of the long-lived radionuclide concentrations with the derived drinking water levels indicates that the performance of a repository under oxidising conditions would tend to be limited by the release of I-129 and Tc-99. (author)

  4. Dynamic stiffness of pile groups in a multilayered soil. Part 1

    International Nuclear Information System (INIS)

    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

  5. Exacting SNG-probe measurements

    International Nuclear Information System (INIS)

    For some years the Department of Electrophysics has measured Spectral Natural Gamma-ray logs (SNG-logs) in shallow boreholes (to 600 m below surface). For the interpretation - i.e. the ''transformation'' of count rates to concentrations of radioactive elements - there have been developed simple physical models and advanced computer models based on basic physical principles, and there have been performed a number of calibration measurements in order to check the computer models. For cased boreholes with thick layers of backfill it has been difficult (and expensive) to perform calibration measurements. In december 1991 the Department got an opportunity for performing special calibration measurements in a ''synthetic borehole'' - cased and supplied with a thick layer of backfill - that had been built for another purpose (than calibration of SNG-probes). The measurements and the results are described in this report, and the models mentioned above and some counting statistical problems, are briefly explained. (au)

  6. 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'.

  7. Soil Structure Interaction for Integral Abutment Bridge Using Spring Analogy Approach

    International Nuclear Information System (INIS)

    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.

  8. 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.

  9. Reference concept for a final storage of radioactive wastes in clay rocks - ERATO. Final report; Referenzkonzept fuer ein Endlager fuer radioaktive Abfaelle in Tongestein - ERATO. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Poehler, M.; Amelung, P.; Bollingerfehr, W.; Engelhardt, H.J.; Filbert, W.; Tholen, M.

    2010-06-15

    At the end of the 1990ies, the Federal Government decided to examine alternative host rocks for the final storage of radioactive wastes in clay formations. In the contribution under consideration further fundamentals for the dimensioning of final storages in clay rocks are developed. Additionally, a reference concept of final storage is compiled. After presentation of the geotechnical and geophysical procedures for the surface and underground investigation, variants of storage are examined and evaluated. The open mines for the final storage of high activity wastes, the storage technology, the backfilling technology as well as the operating procedures are described. The measures for the backfilling and closure of final storages as well as the safety precautions are presented. Additionally, the expenditure of time and the costs of the realization of the final storages of high activity wastes are evaluated.

  10. 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)

    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.)

  11. Equilibrium leach testing of Magnox swarf and sludge

    International Nuclear Information System (INIS)

    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, Np237, Am241, Cs137, Sr90, Tc99, I129 and C14. 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)

  12. Controlled low strength materials (CLSM), reported by ACI Committee 229

    International Nuclear Information System (INIS)

    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

  13. Numerical Simulation of Heat Transfer Characteristics of Horizontal Ground Heat Exchanger in Frozen Soil Layer

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A simplified numerical model of heat transfer characteristics of horizontal ground heat exchanger (GHE) in the frozen soil layer is presented and the steady-state distribution of temperature field is simulated. Numerical results show that the frozen depth mainly depends on the soil's moisture content and ambient temperature. The heat transfer loss of horizontal GHE tends to grow with the increase of the soil's moisture content and the decrease of ambient temperature. Backfilled materials with optimal thermal conductivity can reduce the thermal loss effectively in the frozen soil. The applicability of the Chinese national standard "Technical Code for Ground Source Heat Pump (GB 50366-2005)" is verified. For a ground source heat pump project, the feasible layout of horizontal GHE should be determined based on the integration of the soil's structure, backfilled materials,weather data, and economic analysis.

  14. 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)

    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

  15. Characteristics of the excavation response zone as applied to shaft sealing

    International Nuclear Information System (INIS)

    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

  16. Thermal simulation of drift emplacement (TSS): In-situ instrumentation and numerical modeling of stress measurement methods

    International Nuclear Information System (INIS)

    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

  17. Evaluation and analysis on mechanical stability and integrity of a radwaste repository in a deep salt rock formation

    International Nuclear Information System (INIS)

    Since a general guide line for the safety criteria to assess the geomechanical stability and integrity of a repository for radioactive waste in a deep salt rock formation is not yet available, few criteria commonly employed (dilatancy limit, zero tensional strength, failure strength and fluid pressure criterion) are summarized and assessed in this report. Within a scoping two dimensional analysis using the computer code ADINA, these criteria are applied to evaluate the stability and the integrity of a repository with a successive excavation of chambers on five different levels. The analyses indicate, that the instable regions with local failures and development or propagation of cracks in raise stope and in side wall areas are to be expected within the first 100 years after constructing the chambers, if the chambers are not backfilled. An early backfilling of the chambers can reduce the instable regions (dilatancy criterion) substantially but the possible leakage regions (fluid pressure criterion) to a lesser extent only. (orig.)

  18. Characteristics of thermally-enhanced bentonite grouts for geothermal heat exchanger in South Korea

    Institute of Scientific and Technical Information of China (English)

    Chulho; LEE; Kangja; LEE; Hangseok; CHOI; Hyo-Pum; CHOI

    2010-01-01

    The thermal conductivity and viscosity of bentonite grouts have been evaluated and compared each other to determine the suitability of these materials for backfilling vertical boreholes of ground heat exchangers.Seven bentonite grouts from different product sources were considered in this paper.Two additives,silica sand and graphite were added in bentonite grouts to enhance thermal performance.The bentonite grouts indicate that both the thermal conductivity and the viscosity increase with the content of silica sand and graphite.Therefore,it is recommended to select cautiously the amount of silica sand and graphite considering not only thermal conductivity but also viscosity for the optimum condition of backfilling.Finally,the effect of salinity in the pore water on the change of swelling potential of the bentonite-based grouts has been quantitatively evaluated to show the feasibility of bentonite grouts in the coastal area.

  19. 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 ...

  20. Forced vibration test of the Hualien large scale SSI model

    International Nuclear Information System (INIS)

    A Large-Scale Seismic Test (LSST) Program has been conducted at Hualien, Taiwan (Tang et al., 1991), to obtain earthquake-induced soil-structure interaction (SSI) data in a stiff soil site environment The Hualien program is a follow on of the Lotung program which is of soft soil site. Forced vibration tests of the Hualien 1/4-scale containment SSI test model were conducted in October, 1992 before backfill (without embedment) and in February, 1993 after backfill (with embedment) for the purpose of defining basic dynamic characteristics of the soil-structure system. Two horizontal directions excitation (NS, EW) are applied on the roof floor and on the basemat. Vertical excitation is applied on the basemat only. This paper describes the results of the forced vibration tests of the model without embedment. (author)

  1. PILOT-SCALE EVALUATION OF ENGINEERED BARRIER SYSTEMS FOR THE YUCCA MOUNTAIN PROJECT

    International Nuclear Information System (INIS)

    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

  2. Oil shale mining cost analysis. Volume I. Surface retorting process. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Resnick, B.S.; English, L.M.; Metz, R.D.; Lewis, A.G.

    1981-01-01

    An Oil Shale Mining Economic Model (OSMEM) was developed and executed for mining scenarios representative of commercially feasible mining operations. Mining systems were evaluated for candidate sites in the Piceance Creek Basin. Mining methods selected included: (1) room-and-pillar; (2) chamber-and-pillar, with spent shale backfilling; (3) sublevel stopping; and (4) sublevel stopping, with spent shale backfilling. Mines were designed to extract oil shale resources to support a 50,000 barrels-per-day surface processing facility. Costs developed for each mining scenario included all capital and operating expenses associated with the underground mining methods. Parametric and sensitivity analyses were performed to determine the sensitivity of mining cost to changes in capital cost, operating cost, return on investment, and cost escalation.

  3. Mobility and survival of sulphate-reducing bacteria in compacted and fully water saturated bentonite - microstructural aspects

    International Nuclear Information System (INIS)

    Sulphate-reducing bacteria will not be able to enter MX-80 buffer clay with the intended bulk density, i.e. 1900-2100 kg/m3. 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

  4. Soil-Structure Interaction for Non-Slender, Large-Diameter Offshore Monopiles

    DEFF Research Database (Denmark)

    Sørensen, Søren Peder Hyldal

    . 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...... University. 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....... been 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...

  5. Some considerations of the use of concrete for radioactive waste repositories

    International Nuclear Information System (INIS)

    This paper describes three particular investigations which have been undertaken in relation to the potential use of concrete as a backfill material for deep radioactive waste repositories. The first of these investigations considered some of the consequences of backfilling around heat generating wastes, with particular regard to identifying appropriate computer models and obtaining an indication of the temperature generated stresses in a hypothetical situation. The second study was concerned with the possibility of forming the concrete from grouted pre-packed aggregate which was thought to be less susceptible to creep and shrinkage than conventional concretes. No such benefits were identified. In the third study samples of concretes up to 2500 years old were obtained and subjected to chemical and physical examination to identify the characteristics which had contributed to the long life of these materials. An understanding of these mechanics may provide reassurance about the future reliability of equivalent current materials. (orig.)

  6. Shielding analysis of depleted uranium silicate filler concept for spent fuel canister designs

    International Nuclear Information System (INIS)

    A Depleted Uranium Silicate Container Backfill System (DUSCOBS) has been proposed at Oak Ridge National Laboratory. This concept suggests the use of small, depleted-uranium silicate glass beads as a backfill material inside storage, transportation, and repository waste packages containing spent nuclear fuel. Use of this backfdl material would substantially reduce external dose rates from a waste canister, allowing a reduction of the amount of external shielding required. This paper summarizes the results of scoping studies to estimate the dose reduction from the use of DUSCOBS in a conceptual canister design, and to determine what design modifications are required to offset the increased mass of the system, while simultaneously maintaining sufficient shielding to meet external dose rate limits

  7. THE EFFECT OF CORRUGATED ELEMENTS THICKNESS ON THE DEFLECTED MODE OF CORRUGATED METAL STRUCTURES

    Directory of Open Access Journals (Sweden)

    V. V. Kovalchuk

    2015-06-01

    Full Text Available Purpose. The work provides research the deflected mode and calculation the relative deformation of vertical and horizontal diameters of corrugated metal structures (CMS, horizontal ellipse type, and cross section in their interaction with soil backfill depending on the thickness of corrugated metal pipe. Such studies are required for optimal design of CMS, establishing the causes of defects timely, appropriate engineering solutions to improve the bearing capacity of the CMS and reasonable use of funds for their construction or rehabilitation of existing transportation facilities using corrugated metal pipes. Methodology. Stresses and stability calculations of CMS form are conducted using the developed mathematical algorithm in program environment Mathcad 14. In these studies different thickness of corrugated metal pipe were assigned, and further calculations were carried out at the design value of backfill soil compaction degree and magnitude of dynamic loading of railway transport. Findings. From the calculations is determined that the most influence the thickness of the corrugated metal pipe has on the strength in the calculation of the normal stresses and value of the vertical pipe strains. Therefore, the calculated parameters in the design of corrugated metal structures with small filling heights (from 1.2 m to 3 m above its peak is calculation of the strength by the normal stresses and determination of the vertical deformation of the pipe. Originality. For the first time, calculations of the deflected mode and relative deformations of vertical and horizontal cross-sectional diameters of CMS, horizontal ellipse type in the interaction with soil backfill. The factors complex was taken into account the backfill soil compaction degree, the value of dynamic loading of railway transport and different thickness of corrugated metal pipe. Practical value. The results of the deflected mode of corrugated metal structures such as horizontal ellipse of

  8. Stripa project, Quarterly report October through December 1981

    International Nuclear Information System (INIS)

    The methodology development for hydrogeological investigations in boreholes is continuing in combination with hydraulic, chemical and isotopic characterization of granites and groundwaters. The migration investigation is continued by drilling sampling holes and desigming the equipment. The first buffer mass tests have covered the measurement of temperature, swelling pressures and water migration in two deposition holes. The preparation of the bentonite/sand backfill has started. (G.B.)

  9. Treatment and final disposal of nuclear waste. Programme for encapsulation, deep geological disposal, and research, development and demonstration

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    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.

  10. Implementation of the Barcelona Basic Model into TOUGH-FLAC for simulations of the geomechanical behavior of unsaturated soils

    Energy Technology Data Exchange (ETDEWEB)

    Rutqvist, J.; Ijiri, Y.; Yamamoto, H.

    2010-06-01

    This paper presents the implementation of the Barcelona Basic Model (BBM) into the TOUGH-FLAC simulator analyzing the geomechanical behavior of unsaturated soils. We implemented the BBM into TOUGH-FLAC by (1) extending an existing FLAC{sup 3D} module for the Modified Cam-Clay (MCC) model in FLAC{sup 3D} and (2) adding computational routines for suction-dependent strain and net stress (i.e., total stress minus gas pressure) for unsaturated soils. We implemented a thermo-elasto-plastic version of the BBM, wherein the soil strength depends on both suction and temperature. The implementation of the BBM into TOUGH-FLAC was verified and tested against several published numerical model simulations and laboratory experiments involving the coupled thermal-hydrological-mechanical (THM) behavior of unsaturated soils. The simulation tests included modeling the mechanical behavior of bentonite-sand mixtures, which are being considered as back-fill and buffer materials for geological disposal of spent nuclear fuel. We also tested and demonstrated the use of the BBM and TOUGH-FLAC for a problem involving the coupled THM processes within a bentonite-backfilled nuclear waste emplacement tunnel. The simulation results indicated complex geomechanical behavior of the bentonite backfill, including a nonuniform distribution of buffer porosity and density that could not be captured in an alternative, simplified, linear-elastic swelling model. As a result of the work presented in this paper, TOUGH-FLAC with BBM is now fully operational and ready to be applied to problems associated with nuclear waste disposal in bentonite-backfilled tunnels, as well as other scientific and engineering problems related to the mechanical behavior of unsaturated soils.

  11. Bentonite in the repository - Manufacture of bentonite blocks. A literature study; Bentonit i slutfoervaret - Tillverkning av bentonitblock. En litteraturstudie

    Energy Technology Data Exchange (ETDEWEB)

    Hultgren, Aa. [NFC Konsult, Nykoeping (Sweden)

    1995-09-01

    Activities in nuclear power countries are reviewed, concerning developments in the use of bentonite for backfilling in nuclear waste repositories, in particular regarding manufacture of bentonite-blocks. Only one report was found which in detail describes the manufacture of highly compacted blocks of bentonite. Use of bentonite for sealing boreholes etc in the oil- and gas industry was also covered in the literature study. 19 refs, 3 tabs.

  12. Caractérisation géostatistique de pollutions industrielles de sols: cas des hydrocarbures aromatiques polycycliques sur d'anciens sites de cokeries

    OpenAIRE

    Jeannée, Nicolas

    2001-01-01

    Estimating polycyclic aromatic hydrocarbons concentrations in soil at former industrial sites poses several practical problems on account of the properties of the contaminants and the history of site : - collection and preparation of samples from highly heterogeneous material, - high short scale variability, particularly in presence of backfill, - highly contrasted grades making the variogram inference complicated. The sampling strategy generally adopted for contamined sites is based on the h...

  13. Tumor necrosis factor inhibitor therapy but not standard therapy is associated with resolution of erosion in the sacroiliac joints of patients with axial spondyloarthritis

    OpenAIRE

    Pedersen, Susanne J; Wichuk, Stephanie; Chiowchanwisawakit, Praveena; Lambert, Robert G; Maksymowych, Walter P

    2014-01-01

    Introduction Radiography is an unreliable and insensitive tool for the assessment of structural lesions in the sacroiliac joints (SIJ). Magnetic resonance imaging (MRI) detects a wider spectrum of structural lesions but has undergone minimal validation in prospective studies. The Spondyloarthritis Research Consortium of Canada (SPARCC) MRI Sacroiliac Joint (SIJ) Structural Score (SSS) assesses a spectrum of structural lesions (erosion, fat metaplasia, backfill, ankylosis) and its potential to...

  14. Simulation of the deformation of a stope support design / Abraham Johannes Laubscher

    OpenAIRE

    Laubscher, Abraham Johannes

    2014-01-01

    Supported stope mining is one of the most common types of mining in the modern day gold mining industry. The excavated regions, where ore is extracted, are supported with a combination of roof-bolting, timber packs, backfill, timber props and mechanical prop technologies. In order to install a support system that will be able to absorb the energy released by the elastic movement of the surrounding rock mass and support the unstable hanging wall, it is necessary for the rock eng...

  15. Synthesis and characterization of zeolite from waste coal flyash for tailored application in bio-refining and process water cleaning: An innovative approach towards a cleaner circular economy

    OpenAIRE

    Das, Gaurav

    2016-01-01

    The purpose of the investigation was to assess if Finnish coal flyash (CFA) waste could be used to synthesize zeolites. The world produces 750 million tonnes of CFA annually which is also the largest quantity waste produced. This figure will only increase as India, China, South America and Africa charges ahead with industrialization. The global recycle rate is 15% annually. Finland produces about 750,000 tonnes of CFA per year. It is also estimated that millions of tonnes of CFA is backfilled...

  16. PreBIND and Textomy – mining the biomedical literature for protein-protein interactions using a support vector machine

    OpenAIRE

    Baskin Berivan; Zhang Shudong; Tuekam Brigitte; Lay Vicki; Wolting Cheryl; de Bruijn Berry; Martin Joel; Donaldson Ian; Bader Gary D; Michalickova Katerina; Pawson Tony; Hogue Christopher WV

    2003-01-01

    Abstract Background The majority of experimentally verified molecular interaction and biological pathway data are present in the unstructured text of biomedical journal articles where they are inaccessible to computational methods. The Biomolecular interaction network database (BIND) seeks to capture these data in a machine-readable format. We hypothesized that the formidable task-size of backfilling the database could be reduced by using Support Vector Machine technology to first locate inte...

  17. Use of engineered soils and other site modifications for low-level radioactive waste disposal

    International Nuclear Information System (INIS)

    The U.S. Nuclear Regulatory Commission requires that low-level radioactive waste (LLW) disposal facilities be designed to minimize contact between waste and infiltrating water through the use of site design features. The purpose of this investigation is to identify engineered barriers and evaluate their ability to enhance the long-term performance of an LLW disposal facility. Previously used barriers such as concrete overpacks, vaults, backfill, and engineered soil covers, are evaluated as well as state-of-the-art barriers, including an engineered sorptive soil layer underlying a facility and an advanced design soil cover incorporating a double-capillary layer. The purpose of this investigation is also to provide information in incorporating or excluding specific engineered barriers as part of new disposal facility designs. Evaluations are performed using performance assessment modeling techniques. A generic reference disposal facility design is used as a baseline for comparing the improvements in long-term performance offered by designs incorporating engineered barriers in generic and humid environments. These evaluations simulate water infiltration through the facility, waste leaching, radionuclide transport through the facility, and decay and ingrowth. They also calculate a maximum (peak annual) dose for each disposal system design. A relative dose reduction factor is calculated for each design evaluated. The results of this investigation are presented for concrete overpacks, concrete vaults, sorptive backfill, sorptive engineered soil underlying the facility, and sloped engineered soil covers using a single-capillary barrier and a double-capillary barrier. Designs using combinations of barriers are also evaluated. These designs include a vault plus overpacks, sorptive backfill plus overpacks, and overpack with vault plus sorptive backfill, underlying sorptive soil, and engineered soil cover

  18. Screening evaluation of radionuclide groundwater concentrations for the end state basement fill model Zion Nuclear Power Station decommissioning project

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan T.

    2014-06-09

    ZionSolutions is in the process of decommissioning the Zion Nuclear Power Plant. The site contains two reactor Containment Buildings, a Fuel Building, an Auxiliary Building, and a Turbine Building that may be contaminated. The current decommissioning plan involves removing all above grade structures to a depth of 3 feet below grade. The remaining underground structures will be backfilled with clean material. The final selection of fill material has not been made.

  19. Performance of buffer material under radiation and thermal conditions

    International Nuclear Information System (INIS)

    Bentonite is generally selected as backfill and buffer material for repositories in the world. Radiation and heat release is the intrinsic properties of high level radioactive waste. This paper made a preliminary research on foreign literature about performance of the engineering barrier material under radiation and at higher temperatures (e. g. above 100℃). As our current research is just budding in this area, we need to draw lessons from foreign experience and methods. (authors)

  20. Radionuclide getters in the near-field chemistry of repositories

    International Nuclear Information System (INIS)

    The ultimate release of radionuclides from a radioactive waste repository will depend upon the natural and man-made barriers surrounding the site. An opportunity exists to enhance natural radionuclide retention through improved sorption, by the use of suitable additives applied to the repository backfill material. This programme of work was designed to identify problem isotopes, to search for suitable materials to enhance their retention and ultimately to provide, through experimental studies, an understanding of their effectiveness under repository conditions. (Author)

  1. 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)

  2. NTPC`s experiences in ash utilization

    Energy Technology Data Exchange (ETDEWEB)

    Trehan, A.; Krishnamurthy, R.; Kumar, A. [National Thermal Power Corporation Ltd., New Delhi (India)

    1997-12-31

    India is a major user of coal, and will remain so into the twenty first century. Ash disposal is a considerable problem, and NTPC has devised many methods of using ash, rather than dumping it. Such uses include the raising of ash dykes using coal ash rather than earth; structural fill; reclaiming low lying land; road construction; building materials; in the cement industry; in the asbestos industry; in agriculture; and backfilling in mines. Present and future use of ash is described. 1 tab.

  3. Weathering products of basic rocks as sorptive materials of natural radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Omelianenko, B.I.; Niconov, B.S.; Ryzhov, B.I.; Shikina, N.D. [AN SSSR, Moscow (Russian Federation). Inst. Geologii Rudnykh Mestorozhdenij, Petrografii, Mineralogii i Geokhimii

    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.

  4. Weathering products of basic rocks as sorptive materials of natural radionuclides

    International Nuclear Information System (INIS)

    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

  5. Equilibrium leach testing of low level waste. Pt. 1

    International Nuclear Information System (INIS)

    The equilibrium leach test was developed to simulate the chemical conditions in a repository after water has penetrated the near field barriers. The principal components of the repository (the waste, backfill and canister simulant) are equilibrated with water under static conditions to simulate the very low water flows likely to be encountered in the repository. The water is sampled at various times over a 1-2 year period and analysed for radionuclides. Equilibrium leach testing has now been extended to low level wastes and this report describes the effects of different backfill compositions. Later reports will deal with the effects of other variables. A series of experiments have been conducted using four different backfills with ferric floc sludge wastes in both oxidising and reducing environments. The water was sampled at 1, 3, 6 and 12 months and analysed for actinides, fission and activation products and inactive components. It was demonstrated that the activities released depended on the nature of the backfill but not very much on the redox potential of the system. Whereas fission and activation products generally reached steady state values by three months, this was not so for the actinides which had not reached a steady value even after twelve months. Initial experiments using membrane filters indicated this was partly due to the presence of colloidal material in the leachates. Similar tests for the inactive components of the leachates did not show any significant colloidal contribution from these elements except for iron and this only in a few cases. The role of these materials cannot be precluded however, since the amounts required to interact with actinides would be very small and might be difficult to detect. (author)

  6. Field Performance of Recycled Plastic Foundation for Pipeline

    OpenAIRE

    Seongkyum Kim; Kwanho Lee

    2015-01-01

    The incidence of failure of embedded pipelines has increased in Korea due to the increasing applied load and the improper compaction of bedding and backfill materials. To overcome these problems, a prefabricated lightweight plastic foundation using recycled plastic was developed for sewer pipelines. A small scale laboratory chamber test and two field tests were conducted to verify its construction workability and performance. From the small scale laboratory chamber test, the applied loads at ...

  7. Tabulated In-Drift Geometric and Thermal Properties Used In Drift-Scale Models for TSPA-SR

    International Nuclear Information System (INIS)

    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

  8. In Situ Remediation using Horizontal Wells

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Horizontal well technology has been widely used in petroleum and underground utility installation. Since late 1980's, the technology has been adapted for environmental remediation applications. Two general methods in drilling horizontal wells have been used in remediation, trenched and directionally-drilled. The first method involves the excavation of a relatively large diameter borehole, with simultaneous installation of well materials and backfill. The second method, directional drilling, p...

  9. Novel lattice models for porous media

    OpenAIRE

    Andrey P Jivkov, Joseph E Olele

    2011-01-01

    Several barriers in a nuclear waste repository, such as waste immobilisers, backfills and host rock are porous. Predicting the changes in their permeability over the repository lifetime is critical to the assessment of radionuclide transport. Pore network models used in petrology offer an advantageous way for such predictions, because they can be linked elegantly to physical mechanisms that could lead to pore structure changes, e.g. mechanical damage, gas generation, or irradiation. The ex...

  10. Third millennium BC ditched enclosures in central Iberia

    OpenAIRE

    Díaz del Río, Pedro

    2003-01-01

    This article examines contextual data from three Copper Age ditched enclosures excavated between 1997 and 2001 in the middle Tagus basin. Calibrated radiocarbon dates suggest that they were all constructed and backfilled during the first half of the third millennium BC. Key characteristics are their heterogeneous topographic position, variable visibility, small size and high density of features and domestic refuse. All evidence supports their interpretation as small occupation sites. Finally,...

  11. The influence of sintering time on the properties of PM duplex stainless steel

    OpenAIRE

    Z. Brytan; L.A. Dobrzański; M. Actis Grande; M. Rosso

    2009-01-01

    Purpose: The purpose of this paper is to analyse the effect of sintering time on the pore morphology, microstructural changes, tensile properties and corrosion resistance of vacuum sintered duplex stainless steel.Design/methodology/approach: In presented study PM duplex stainless steels were obtained through mixing base ferritic stainless steel powder with controlled addition of elemental alloying powders and then sintered in a vacuum furnace with argon backfilling at 1250°C for different tim...

  12. Plasticity in soil-structure interaction applied to cut-and-cover tunnels

    OpenAIRE

    Plumey, Sylvain; Muttoni, Aurelio; Vulliet, Laurent; Labiouse, Vincent

    2004-01-01

    Cut-and-cover tunnels behavior at ultimate limit state depends strongly on the interactions between the foundation soil, the backfill and the reinforced concrete structure. Characterization of the potential failure modes of these types of structure necessitates taking into account every major mechanical property of each components. The influence of the structure plastic behavior on the ultimate limit state of the soil-structure system is discussed through a basic case study of soil mechanics....

  13. Neuroanatomy of pars intercerebralis neurons with special reference to their connections with neurons immunoreactive for pigment-dispersing factor in the blow fly Protophormia terraenovae.

    Science.gov (United States)

    Yasuyama, Kouji; Hase, Hiroaki; Shiga, Sakiko

    2015-10-01

    Input regions of pars intercerebralis (PI) neurons are examined by confocal and electron microscopies with special reference to their connections with neurons immunoreactive for pigment-dispersing factor (PDF) in the blow fly, Protophormia terraenovae. PI neurons are a prerequisite for ovarian development under long-day conditions. Backfills from the cardiac recurrent nerve after severance of the posterior lateral tracts labeled thin fibers derived from the PI neurons in the superior medial protocerebrum. These PI fibers were mainly synapsin-negative and postsynaptic to unknown varicose profiles containing dense-core vesicles. Backfilled fibers in the periesophageal neuropils, derived from the PI neurons or neurons with somata in the subesophageal zone, were varicose and some were synapsin-positive. Electron microscopy revealed the presence of both presynaptic and postsynaptic sites in backfilled fibers in the periesophageal neuropils. Many PDF-immunoreactive varicosities were found in the superior medial and lateral protocerebrum and double-labeling showed that 60-88 % of PDF-immunoreactive varicosities were also synapsin-immunoreactive. Double-labeling with the backfills and PDF immunocytochemistry showed that the PI fibers and PDF-immunoreactive varicosities were located close to each other in the superior medial protocerebrum. Results of triple-labeling of PI neurons, PDF-immunoreactive neurons and synapsin-immunoreactive terminals demonstrated that the synapsin-positive PDF-immunoreactive varicosities contacted the PI fibers. These data suggest that PI neurons receive synaptic contacts from PDF-immunoreactive fibers, which are derived from circadian clock neurons, of small ventral lateral neurons (previously called OL2) or posterior dorsal (PD) neurons with somata in the pars lateralis. PMID:25971932

  14. Physical and numerical modelling of earth pressure on anchored sheet pile walls in sand

    DEFF Research Database (Denmark)

    Krogsbøll, Anette Susanne; Fuglsang, Leif D

    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......-model showed the right behaviour in pre-failure as well as failure for both flexible and stiff walls, whereas the MC-model showed some shortcomings when stiff walls were modelled....

  15. Three-dimensional porous stretchable and conductive polymer composites based on graphene networks grown by chemical vapour deposition and PEDOT:PSS coating.

    Science.gov (United States)

    Chen, Mengting; Duan, Shasha; Zhang, Ling; Wang, Zhihui; Li, Chunzhong

    2015-02-21

    We have manufactured a highly conductive and stretchable composite by backfilling the 3D graphene-PEDOT:PSS skeleton with poly(dimethylsiloxane) (PDMS). The electrical conductivity of our product can reach 24 S cm(-1) with only 1.5 wt% graphene and 1.5 wt% PEDOT:PSS loading, and its resistance increased only 35% when stretched to 80% strain. PMID:25605259

  16. Bentonite in the repository - Manufacture of bentonite blocks. A literature study

    International Nuclear Information System (INIS)

    Activities in nuclear power countries are reviewed, concerning developments in the use of bentonite for backfilling in nuclear waste repositories, in particular regarding manufacture of bentonite-blocks. Only one report was found which in detail describes the manufacture of highly compacted blocks of bentonite. Use of bentonite for sealing boreholes etc in the oil- and gas industry was also covered in the literature study. 19 refs, 3 tabs

  17. Proceedings of the Canadian Nuclear Society 2. international conference on radioactive waste management

    International Nuclear Information System (INIS)

    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

  18. Radionuclide Speciation During Mineral Reactions in the Chemically Disturbed Zone Around a Geological Disposal Facility

    OpenAIRE

    Marshall, Timothy

    2014-01-01

    Geological disposal of radioactive wastes currently stored at Earth's surface is now the favoured management pathway for these materials. Typically, intermediate level wastes (ILW) are grouted and emplaced in a geological disposal facility (GDF) which will be backfilled, possibly with cementitious materials. Post-closure leaching of the cementitious materials in a GDF is expected to create hyperalkaline conditions in and around the repository, resulting in mineral alteration and crystallisati...

  19. Long-term effect of water chemistry on the swelling pressure of a bentonite-based material

    OpenAIRE

    Wang, Qiong; Cui, Yu-Jun; Tang, Anh Minh; Delage, Pierre; Gatmiri, Behrouz; Ye, Wei-Min

    2014-01-01

    Compacted bentonite-based materials have been proposed as possible sealing and backfill materials in geological repositories for the high-level radioactive waste disposal in several countries. During the long time lifespan of a repository, as the chemical composition of pore water can change, the swelling and sealing capacity of the material may also change. From a point of view of storage safety assessment, it is important to evaluate this possible change of swelling capacity. In this study,...

  20. The influence of natural organic matter on radionuclide mobility under conditions relevant to cementitious disposal of radioactive wastes: a review of direct evidence

    OpenAIRE

    Stockdale, A.

    2013-01-01

    A concept for the disposal of intermediate level radioactive wastes involves emplacement within a geological disposal facility, followed by backfilling of the facility with cement. When the closed facility is re-saturated with groundwater, this will create a high pH environment due to dissolution of the cement minerals. Dissolved organic matter (DOM; defined here as naturally occurring organic acids and humin) will be present in the groundwater at a concentration that reflects the host rock e...

  1. Evaluation of rare earth on layered silicates under subcritical conditions: Effect of the framework and interlayer space composition

    OpenAIRE

    Chain, P.; Cota, Agustín; Pavón, Esperanza; Pazos, M. Carolina; Alba, María D.

    2013-01-01

    Clay-based minerals are considered to be an important component in backfill barriers due to both their ability to seal and adsorb radioactive waste and to interact chemically with it under subcritical conditions. Herein, we describe a systematic study of the properties of layered silicates that could affect their hydrothermal reactivity, namely type of layers, octahedral occupancy, origin and total amount of the layer charge, and nature of the interlayer cation. The silicates studied were sel...

  2. Engineered barrier development for a nuclear waste repository in basalt: an integration of current knowledge

    International Nuclear Information System (INIS)

    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

  3. Thermal cycling: impact on bentonite permeability

    OpenAIRE

    Zihms, S.G.; Harrington, J. F.

    2015-01-01

    Due to its favourable properties, in particular, low permeability and swelling capacity, bentonite has been favoured as an engineered-barrier and backfill material for the geological storage of radioactive waste. To ensure its safe long-term performance it is important to understand any changes in these properties when the material is subject to heat-emitting waste. As such, this study investigates the hydraulic response of bentonite under multi-step thermal loading subject to a constant-volu...

  4. THE IMPACT OF THE COMPOSITION OF THE WOOD GAS TO EMISSIONS AFTER COMBUSTION OF WOOD GAS

    OpenAIRE

    Kočanová, Slávka; Lukáč, Ladislav

    2014-01-01

    This paper presents the results of measurements which were carried out on Department of furnaces and thermal technology. Experiments were carried out on a countercurrent gasifier using different fuels, different flow gasification medium and different heights of backfill. In order to obtain values for emissions of the combustion process of producer gas are planned measurements for different composition of produced gas, depending on the type of gasifying medium. In our case, produced gas will b...

  5. Evaluation on Impact Interaction between Abutment and Steel Girder Subjected to Nonuniform Seismic Excitation

    OpenAIRE

    Yue Zheng; Xiang Xiao; Lunhai Zhi; Guobo Wang

    2015-01-01

    This paper aims to evaluate the impact interaction between the abutment and the girder subjected to nonuniform seismic excitation. An impact model based on tests is presented by taking material properties of the backfill of the abutment into consideration. The conditional simulation is performed to investigate the spatial variation of earthquake ground motions. A two-span continuous steel box girder bridge is taken as the example to analyze and assess the pounding interaction between the abut...

  6. 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)

  7. Closure concept for the Morsleben LLW repository for radioactive waste design of drift seals in a former salt mine

    International Nuclear Information System (INIS)

    In this paper the basis of drift seals conception is given including a comprehensive analysis of the site specific situation and an overview of the closure concept. The requirements on drift seals and backfill respectively sealing material rely on inputs from long-term safety analysis. These aspects altogether lead to a simple and robust design of drift seals associated with a plausible way of proving the drift seals' compliance with the requirements. (authors)

  8. Observation of an engineered barrier experiment in the Opalinus Clay of the Mont Terri Rock Laboratory (CH) with geophysical and hydraulic methods

    International Nuclear Information System (INIS)

    Within the framework of the European Commission project EB 'Engineered Barrier Experiment in Opalinus Clay, which aims at the demonstration of a new concept for the construction of HLW repositories in horizontal drifts, in competent clay formations, high frequency seismic, acoustic emission, geo-electric and hydraulic in-situ measurements were performed. Investigations were carried out at different stages after the excavation of the EB niche as well as after the placement of a dummy canister, the sealing with a concrete plug and hydration of the backfill. The initial geophysical characterisation shows a clearly identified EDZ in the roof up to a depth of about 70 cm. At the sidewalls the EDZ reaches a depth of about 10 cm. Highest hydraulic transmissivities were observed at a distance of about 50 cm from the wall. After sealing the EB niche, a change in geo-mechanical rock parameters with time was expected due to the swelling of the backfill and local stress redistributions. These developments were monitored with seismic transmission (diurnal) and acoustic emission (permanent) measurements over a time span of 19 months. Geo-electric measurements were repeated at two and hydraulic measurements at three different stages after the sealing. Results show a decrease in seismic amplitude damping and an increase in seismic velocities in parts of the EDZ and the backfill which can be interpreted as a compaction due to saturation. Acoustic emission events are very rare. During the first 13 months about 100 events could be detected. Resistivities derived from geo-electric measurements indicate a rather homogeneous distribution of the backfill material and are suitable to define boundaries between disturbed and intact rock zones. Hydraulic transmissivities decrease of 2 to 2.5 orders of magnitude within about 2 years. (authors)

  9. Characterisation of polymeric rod-connected diamond photonic crystal at near-infrared range

    OpenAIRE

    Chen, L; Taverne, M.P.C.; X. Zheng; Huang, C. C.; Garcia, Y.L.; Hewak, D.W.; Rarity, J.G.

    2015-01-01

    We present a low-index polymeric three-dimensional photonic crystal, rod-connected diamond structure, created via direct laser writing, showing a partial photonic band gap at near-infrared wavelengths in both P and S polarization, measured by angular resolved Fourier image spectroscopy. We show initial tests of backfilling with high refractive index material aimed at achieving a full photonic bandgap in the near-infrared.

  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. Experimental study on the hydro-mechanical coupling behaviour of highly compacted expansive clay

    OpenAIRE

    Tang, Anh-Minh; Cui, Yu-Jun

    2010-01-01

    Highly compacted expansive clays have been usually considered as a possible material for sealing and backfill in deep geological disposal of radioactive waste. In this condition, the material is simultaneously subjected to water infiltration from the geological barrier and stresses generated by the swelling of engineered barriers in confined conditions. Its behaviour under hydro-mechanical loading is essential to the safe design of the whole storage system. In the present work, MX80 bentonite...

  12. Computer simulation of an internally pressurized radioactive waste disposal room in a bedded salt formation

    International Nuclear Information System (INIS)

    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

  13. Soft Trencher

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Excavation near existing electrical lines, gas lines and other underground utilities can be dangerous and time consuming. A self propelled trencher called the Soft Trencher developed by Battelle Memorial Institute, Columbus, Ohio uses supersonic air to loosen dirt which is then vacuumed up into a truck or piled into a windrow for later removal of backfill. The supersonic air used to break up the soil is harmless to underground utilities and cables. Unlike traditional excavation methods there ...

  14. Modeling the Electro-Optical Performance of High Power Mid-Infrared Quantum Cascade Lasers

    OpenAIRE

    Hans Dieter Tholl; Quankui Yang; Joachim Wagner

    2016-01-01

    Performance modeling of the characteristics of mid-infrared quantum cascade lasers (MIR QCL) is an essential element in formulating consistent component requirements and specifications, in preparing guidelines for the design and manufacture of the QCL structures, and in assessing different modes of operation of the laser device. We use principles of system physics to analyze the electro-optical characteristics of high power MIR QCL, including thermal backfilling of the lower laser level, hot ...

  15. The sustainability of the Barcelona port enlargement works

    OpenAIRE

    Tarragó, D.; Gens Solé, Antonio; Alonso Pérez de Agreda, Eduardo; Romero Morales, Enrique Edgar; Griell, R.; Estrada, J.L.; Uzcanga, J.

    2011-01-01

    In the Barcelona Port enlargement, currently under construction, part of the new quays are being backfilled with re-used materials such as tunneling waste, rubble from demolitions and dredged soils with poor geotechnical properties. This has resulted in a cost-effective and sustainable construction process that is one of the main goals of the Barcelona Port Authority (APB). A series of control tests have been carried out on the mentioned materials. In addition, dredged soils have been impr...

  16. Expected environments in high-level nuclear waste and spent fuel repositories in salt

    International Nuclear Information System (INIS)

    The purpose of this report is to describe the expected environments associated with high-level waste (HLW) and spent fuel (SF) repositories in salt formations. These environments include the thermal, fluid, pressure, brine chemistry, and radiation fields predicted for the repository conceptual designs. In this study, it is assumed that the repository will be a room and pillar mine in a rock-salt formation, with the disposal horizon located approx. 2000 ft (610 m) below the surface of the earth. Canistered waste packages containing HLW in a solid matrix or SF elements are emplaced in vertical holes in the floor of the rooms. The emplacement holes are backfilled with crushed salt or other material and sealed at some later time. Sensitivity studies are presented to show the effect of changing the areal heat load, the canister heat load, the barrier material and thickness, ventilation of the storage room, and adding a second row to the emplacement configuration. The calculated thermal environment is used as input for brine migration calculations. The vapor and gas pressure will gradually attain the lithostatic pressure in a sealed repository. In the unlikely event that an emplacement hole will become sealed in relatively early years, the vapor space pressure was calculated for three scenarios (i.e., no hole closure - no backfill, no hole closure - backfill, and hole closure - no backfill). It was assumed that the gas in the system consisted of air and water vapor in equilibrium with brine. A computer code (REPRESS) was developed assuming that these changes occur slowly (equilibrium conditions). The brine chemical environment is outlined in terms of brine chemistry, corrosion, and compositions. The nuclear radiation environment emphasized in this report is the stored energy that can be released as a result of radiation damage or crystal dislocations within crystal lattices

  17. 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.

  18. 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

    International Nuclear Information System (INIS)

    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)

  19. Feasibility of an Integrated Thin Seam Coal Mining and Waste Disposal System

    OpenAIRE

    Basu, Kohinoor

    1997-01-01

    The depletion of more attractive thicker and easily accessible coal seams in the central Appalachia will direct attention towards the extraction of coal seams thinner than 28 in. This thesis investigates the feasibility of an integrated mining and backfilling system applicable to thin seams. Two conceptual mining systems, namely Auger mining and Self Advancing Miner, have been proposed for this purpose. Both these systems are designed to remotely mine coal from the seams. Several ...

  20. Research program to study the gamma radiation effects in Spanish bentonites

    International Nuclear Information System (INIS)

    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)

  1. The assessment of borehole cement sealing characteristics by acoustic waveform analysis

    International Nuclear Information System (INIS)

    Acoustic waveform analysis has been used to provide a quantitative analysis of the effectiveness of cement grouting for sealing three adjacent boreholes drilled at Harwell, Oxon, as part of a research programme into the disposal of radioactive wastes into argillaceous formations. Results indicate that bonding at cement/casing and cement/formation interfaces would be inadequate for sealing a radioactive waste repository and the use of a backfilling material such as bentonite is advocated. (U.K.)

  2. Effects of fuel burn-up and cooling periods on thermal responses in a repository for spent nuclear fuels

    International Nuclear Information System (INIS)

    Flexible methods and codes have been developed to calculate thermal responses in a spent nuclear fuel repository located in granitic bedrock. The thermal resistance of the backfill material makes an essential contribution to the temperature at the canister surface. The backfill is however so thin compared to the rock masses of the repository that a stationary solution for the temperature drop across the backfill can be used. Combining analytical solutions of thermal diffusion in the rock and the stationary temperature following the released heat power across the backfill gives a very good description of the thermal behaviour of a repository. Temperatures at different points in a repository were calculated for encapsuled spent fuel with different cooling times (10, 20, 30 and 40 years) and having different burn-up values (33, 35 and 45 MWd/kgU). The amount of spent fuel in each canister was supposed to originate from 1.4 tons of fresh Uranium in the calculated examples. A more crucial variable in a thermal analysis of a repository configuration is however the heat power of canisters as a function of time and not the content of canisters. The study shows that the largest temperature rise at the boundary of a centrally located canister and buffer mass will be at most 85 K with assumed thermal data, when the heat power of 900 canisters does not exceed 1200-1400 W each at the time of emplacement depending on burn-up and cooling time. Assuming a higher value for the heat conductivity of the buffer material corresponding to that of the water saturated bentonite gives 15% higher limits respectively. The canisters were supposed to be placed in 15 rows 25 m apart from each other and 60 canisters in each row. The distance between canisters was taken to be 6 m

  3. Approaches to inform redevelopment of brownfield sites: an example from the Leeds area of the West Yorkshire coalfield, UK

    OpenAIRE

    Burke, H; Hough, E.; Morgan, D J R; Hughes, L.; Lawrence, D.J.

    2015-01-01

    Government-led regeneration schemes and policies encouraging the use of brownfield land present a challenge, particularly in coalfield areas. Coalfields have typically experienced multiple phases of development and can be susceptible to a suite of problematic ground conditions that may be rooted in the near-surface geology or result from anthropogenic activity. Such problems, related to the nature of void backfill, undermined and unstable ground and the presence of contaminated land in the ne...

  4. Engineered barrier development for a nuclear waste repository in basalt: an integration of current knowledge

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Stiffness of Railway Soil-Steel Structures

    OpenAIRE

    Machelski Czesław

    2015-01-01

    The considerable influence of the soil backfill properties and that of the method of compacting it on the stiffness of soil-steel structures is characteristic of the latter. The above factors (exhibiting randomness) become apparent in shell deformation measurements conducted during construction and proof test loading. A definition of soil-shell structure stiffness, calculated on the basis of shell deflection under the service load, is proposed in the paper. It is demonstrated that the stiffne...

  6. Treatment and disposal of radioactive wastes from nuclear power plants. Program for encapsulation, deep geologic deposition and research, development and demonstration; Kaernkraftavfallets behandling och slutfoervaring. Program foer inkapsling, geologisk djupfoervaring samt forskning, utveckling och demonstration

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    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.

  7. 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)

    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

  8. Treatment and final disposal of nuclear waste. Programme for encapsulation, deep geological disposal, and research, development and demonstration

    International Nuclear Information System (INIS)

    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

  9. Retrievability of spent nuclear fuel canisters

    International Nuclear Information System (INIS)

    As a part of the designing process of the Finnish spent nuclear fuel repository, a preliminary study has been carried out to investigate how the canisters could technically be retrieved to the ground surface. Possibility of retrieving a canister has been investigated in different phases of the disposal project. Retrievability has not been a design goal for the spent fuel repository. However, design of the repository includes some features that may ease the retrieval of canisters in the future. Spent fuel elements are packaged in massive copper-iron canisters, which are mechanically strong and long-lived. The repository consists of excavated tunnels in hard rock which are supposed to be very long-lived making the removal of the tunnel backfilling technically possible also in the future. As long as the bentonite buffer has not been installed the canister can be returned to the ground surface using the same equipment as was used when the canister was brought down to the repository and lowered into the hole. In the encapsulation station the spent fuel elements can be packaged in the other canister or in the transport cask. After a deposition tunnel has been backfilled and closed, the retrieval consists of tearing down the concrete structure at the entry of the deposition tunnel, removal of the tunnel backfilling, removal of the bentonite from the disposal hole and lifting up of the canister. Various methods, e.g., flushing the bentonite with saline solutions, can be used to detach the canister from a hole with fully saturated bentonite. Recovery will be technically possible also after closing of the disposal facility. Backfilling of the shafts and tunnels will be removed and additional new structures and systems will have to be built in the repository. After that canisters can be transported to the ground surface as described above. In addition, handling of the canisters at the ground surface will require additional facilities. Canisters can be packaged in the

  10. Use of engineered soils and other site modifications for low-level radioactive waste disposal

    Energy Technology Data Exchange (ETDEWEB)

    1994-08-01

    The U.S. Nuclear Regulatory Commission requires that low-level radioactive waste (LLW) disposal facilities be designed to minimize contact between waste and infiltrating water through the use of site design features. The purpose of this investigation is to identify engineered barriers and evaluate their ability to enhance the long-term performance of an LLW disposal facility. Previously used barriers such as concrete overpacks, vaults, backfill, and engineered soil covers, are evaluated as well as state-of-the-art barriers, including an engineered sorptive soil layer underlying a facility and an advanced design soil cover incorporating a double-capillary layer. The purpose of this investigation is also to provide information in incorporating or excluding specific engineered barriers as part of new disposal facility designs. Evaluations are performed using performance assessment modeling techniques. A generic reference disposal facility design is used as a baseline for comparing the improvements in long-term performance offered by designs incorporating engineered barriers in generic and humid environments. These evaluations simulate water infiltration through the facility, waste leaching, radionuclide transport through the facility, and decay and ingrowth. They also calculate a maximum (peak annual) dose for each disposal system design. A relative dose reduction factor is calculated for each design evaluated. The results of this investigation are presented for concrete overpacks, concrete vaults, sorptive backfill, sorptive engineered soil underlying the facility, and sloped engineered soil covers using a single-capillary barrier and a double-capillary barrier. Designs using combinations of barriers are also evaluated. These designs include a vault plus overpacks, sorptive backfill plus overpacks, and overpack with vault plus sorptive backfill, underlying sorptive soil, and engineered soil cover.

  11. Expected environments in high-level nuclear waste and spent fuel repositories in salt

    Energy Technology Data Exchange (ETDEWEB)

    Claiborne, H.C.; Rickertsen, L.D., Graham, R.F.

    1980-08-01

    The purpose of this report is to describe the expected environments associated with high-level waste (HLW) and spent fuel (SF) repositories in salt formations. These environments include the thermal, fluid, pressure, brine chemistry, and radiation fields predicted for the repository conceptual designs. In this study, it is assumed that the repository will be a room and pillar mine in a rock-salt formation, with the disposal horizon located approx. 2000 ft (610 m) below the surface of the earth. Canistered waste packages containing HLW in a solid matrix or SF elements are emplaced in vertical holes in the floor of the rooms. The emplacement holes are backfilled with crushed salt or other material and sealed at some later time. Sensitivity studies are presented to show the effect of changing the areal heat load, the canister heat load, the barrier material and thickness, ventilation of the storage room, and adding a second row to the emplacement configuration. The calculated thermal environment is used as input for brine migration calculations. The vapor and gas pressure will gradually attain the lithostatic pressure in a sealed repository. In the unlikely event that an emplacement hole will become sealed in relatively early years, the vapor space pressure was calculated for three scenarios (i.e., no hole closure - no backfill, no hole closure - backfill, and hole closure - no backfill). It was assumed that the gas in the system consisted of air and water vapor in equilibrium with brine. A computer code (REPRESS) was developed assuming that these changes occur slowly (equilibrium conditions). The brine chemical environment is outlined in terms of brine chemistry, corrosion, and compositions. The nuclear radiation environment emphasized in this report is the stored energy that can be released as a result of radiation damage or crystal dislocations within crystal lattices.

  12. Clasificación morfológica de los rellenos en el trasdós de bóvedas de fábrica

    Directory of Open Access Journals (Sweden)

    Ramos, A.

    2013-12-01

    Full Text Available This paper proposes a classification of the different type of backfill (granular, stiff or masonry backup at the extrados of vaults of historical masonry buildings scattered throughout the Iberian Peninsula. This study, in the mainframe of a broader research program, highlights the structural significance, rather disregarded in literature, of the backfill regarding the structural stability of such constructions. Furthermore, the most common patterns of the arrangement of masonry backup and backfill, as well as some structural considerations, are depicted to illustrate how to evaluate their structural contribution.En este artículo se establece una clasificación de los diferentes tipos de rellenos (rígidos o cementados, granulares firmes o sueltos y aligerados situados en el trasdós de bóvedas y que han podido datarse en diferentes construcciones históricas en el ámbito geográfico de la Península Ibérica. Estos rellenos, tal y como pretende demostrar el estudio más amplio y del que se extrae el presente artículo, tienen una importancia vital para la estabilidad estructural de estas construcciones. Además de la clasificación, se establecen los patrones tipo con los que se encuentran estos rellenos y se introducen algunas de las consideraciones estructurales que deben tenerse en cuenta si se consideran estructuralmente.

  13. Mined salt storage feasibility: Engineering study report

    International Nuclear Information System (INIS)

    This study addresses a method of eliminating the surface storage of mined salt at the Deaf Smith repository site. It provides rough estimates of the logistics and costs of transporting 3.7 million tons of salt from the repository to the salt disposal site near Carlsbad, New Mexico and returning it to the repository for decommissioning backfill. The study assumes that a railcar/truck system will be installed and that the excavated salt will be transported from the repository to an existing potash mine located near Carlsbad, New Mexico approximately 300 miles from the repository. The 3.7 million tons of salt required for repository decommissioning backfill can be stored in the potash mines along with the excess salt, with no additional capital costs required for either a railcar or a truck transportation system. The capital cost for facilities to reclaim the 3.7 million tons of salt from the potash mine is estimated to be $4,400,000 with either a rail or truck transportation system. Segregating the 3.7 million tons of backfill salt in a surface storage area at the potash mine requires a capital cost of $13,900,000 with a rail system or $11,400,000 with a truck system. Transportation costs are estimated at $0.08/ton-mile for rail and $0.13/ton-mile for truck. 2 figs., 5 tabs

  14. Deformations during saturation of the crushed aggregate, Olkiluoto tonalite

    International Nuclear Information System (INIS)

    Crushed aggregate tonalite produced of crystalline tonalite or a correspondent rock with particle size up to 8 mm (or 16 mm) will be used as backfill material in the VLJ repository caverns at Olkiluoto (in Finland). The backfill material has to retard radionuclides, to restrict the groundwater perlocation and to support mechanically the concrete structure of the repository silos. Mechanical and hydraulic behaviour of crushed tonalite when effected by stresses applied during compaction of the backfill and due to groundwater perlocation was studied at three batches having different gradations. Information about the phenomenon of settlement due to saturation and as a function of the compaction methods was obtained from a literature survey. The maximum amount of possible deformation due to compaction was analyzed with a gyratory device, known to have a good repeatability. In a group of simulation tests using a large oedometer cell the amount of compression due to the saturation process was measured. Also studies on the suitability of different compaction methods could be done with these tests. (43 refs., 49 figs., 3 tabs.)

  15. Temperature history for Candu reprocessing waste and immobilized in an underground vault in plutonic rock

    International Nuclear Information System (INIS)

    Atomic Energy of Canada Limited (AECL) initiated a program in 1975 to assess the concept of disposal of high-level nuclear waste in deep geologic formations. Phase III of the studies involved a review of the basic design criteria and development of possible vault design concepts for both reprocessing waste (RW) and immobilized fuel (IF). The specifications used in Phase III included constraints on temperature of the backfill and container skin, as well as the long-term mechanical behavior of the rock mass. Results presented in this paper are for granite. In the thermal mechanical analyses, the vault was modeled in three geometric zones: container nearfield, room and pillar, and far-field. This paper is concerned with the thermal analyses of the IF and RW vaults in the three geometric zones. Particular attention is given to the characteristic transient thermal response of the RW and IF containers, emplaced backfill and the host rock mass. The influence of backfill and rock thermal conductivity, vault extraction ratio and container arrangement within a room is presented to define the combinations of these variables which satisfy particular maximum temperature constraints

  16. Recent Ground Hold and Rapid Depressurization Testing of Multilayer Systems

    Science.gov (United States)

    Johnson, Wesley L.

    2014-01-01

    In the development of flight insulation systems for large cryogenic orbital storage (spray on foam and multilayer insulation), testing need include all environments that are experienced during flight. While large efforts have been expended on studying, bounding, and modeling the orbital performance of the insulation systems, little effort has been expended on the ground hold and ascent phases of a mission. Historical cryogenic in-space systems that have flown have been able to ignore these phases of flight due to the insulation system being within a vacuum jacket. In the development phase of the Nuclear Mars Vehicle and the Shuttle Nuclear Vehicle, several insulation systems were evaluated for the full mission cycle. Since that time there had been minimal work on these phases of flight until the Constellation program began investigating cryogenic service modules and long duration upper stages. With the inception of the Cryogenic Propellant Storage and Transfer Technology Demonstration Mission, a specific need was seen for the data and as such, several tests were added to the Cryogenic Boil-off Reduction System liquid hydrogen test matrix to provide more data on a insulation system. Testing was attempted with both gaseous nitrogen (GN2) and gaseous helium (GHe) backfills. The initial tests with nitrogen backfill were not successfully completed due to nitrogen liquefaction and solidification preventing the rapid pumpdown of the vacuum chamber. Subsequent helium backfill tests were successful and showed minimal degradation. The results are compared to the historical data.

  17. Effects of water inflow into a deposition hole - Influence of pellets type and of buffer block manufacturing technique

    International Nuclear Information System (INIS)

    During the installation of buffer and canister in a deposition hole a number of different problems can arise. The problems are mainly connected to water flow from fractures in the rock into the deposition hole. According to the reference design for the KBS-3V concept, the buffer is protected with a special sheet made of rubber during the installation phase. This protection sheet will at some stage be removed and the outer gap between the buffer blocks and the rock surface will be filled with bentonite pellets. The interaction of buffer blocks and pellets have previously been investigated. The focuses of those studies were the following processes: 1. Erosion. Erosion of bentonite from the deposition hole up into the tunnel backfill material. This process will continue until a tunnel plug has been installed and the backfill is saturated. 2. Heave. Early wetting of the pellets filling may cause a heave of the buffer blocks into the backfill that will decrease the density of the buffer. The laboratory tests presented in this study are complementing previous investigations by focusing on how the choice of manufacturing process for the bentonite blocks (isostatic or uniaxial compaction) and pellets (roller compaction or extrusion) are affecting erosion and the heaving effect

  18. Nuclear waste package materials testing report: basaltic and tuffaceous environments

    International Nuclear Information System (INIS)

    The disposal of high-level nuclear wastes in underground repositories in the continental United States requires the development of a waste package that will contain radionuclides for a time period commensurate with performance criteria, which may be up to 1000 years. This report addresses materials testing in support of a waste package for a basalt (Hanford, Washington) or a tuff (Nevada Test Site) repository. The materials investigated in this testing effort were: sodium and calcium bentonites and mixtures with sand or basalt as a backfill; iron and titanium-based alloys as structural barriers; and borosilicate waste glass PNL 76-68 as a waste form. The testing also incorporated site-specific rock media and ground waters: Reference Umtanum Entablature-1 basalt and reference basalt ground water, Bullfrog tuff and NTS J-13 well water. The results of the testing are discussed in four major categories: Backfill Materials: emphasizing water migration, radionuclide migration, physical property and long-term stability studies. Structural Barriers: emphasizing uniform corrosion, irradiation-corrosion, and environmental-mechanical testing. Waste Form Release Characteristics: emphasizing ground water, sample surface area/solution volume ratio, and gamma radiolysis effects. Component Compatibility: emphasizing solution/rock, glass/rock, glass/structural barrier, and glass/backfill interaction tests. This area also includes sensitivity testing to determine primary parameters to be studied, and the results of systems tests where more than two waste package components were combined during a single test

  19. Modelling the short term, near field performance of an in-room emplacement configuration

    International Nuclear Information System (INIS)

    This paper presents a numerical investigation of the hydraulic performance of an in-room emplacement scenario. In this concept, two tubular shaped waste canisters are contained within a composite engineered shield of sand, sand/bentonite buffer, light backfill and dense backfill, all seated on a layer of high performance concrete. Because of anticipated excavation damage the elliptical shaped room has a 1.4m thick layer of fissured rock around its perimeter. A numerical study was employed to determine the extent of the granite 'near field' affected by the presence of the open excavation. A zone extending for 7m from the perimeter of the excavation was thus established. The time taken for the repository to fully saturate under isothermal conditions was initially predicted to be 12 years. Coupling the effects of temperature on to the flow of moisture increased the predicted time for saturation to 13 years. A sensitivity study showed that the time to achieve saturation is critically dependent on the assumed value for the coefficient of water storage capacity of the light backfill. Depending on the assumed magnitude of this parameter, it is shown that the repository may take over 250 years to attain a saturated condition. (author)

  20. Final repository for spent nuclear fuel in granite - the KBS-3V concept in Sweden and Finland

    International Nuclear Information System (INIS)

    surface. The operational area comprises a terminal building for receiving transport casks containing encapsulated fuel, a production building for preparation of buffer and backfill material, a supply building for electric power supply, buildings for offices and personnel and a restaurant building. When all canisters in one deposition drift have been emplaced the backfilling and final sealing of the drift can start. It has been discussed to carry out stepwise backfilling but the reference is that we do the backfilling in one step. The backfilling will be done with pre-compacted blocks of swelling clay and with some additional pellets for filling the void between the blocks and the rock wall and the roof of the drift. The principle for emplacement of the blocks is still not decided but different methods and equipment will be tested. The backfilling of the about 300 m long disposal drifts will be a challenge. The speed for backfilling must be high as we must avoid piping and problem with water. We plan to take down about 350 - 400 tons of backfilling material per 24 hours. The backfilling of one drift is estimated to take 10 - 12 full weeks working all days in the week and around the clock. The transport logistic for the backfill material from the production building in the operational area on ground down to the repository level and out into the drift and feeding to the emplacement equipment as well as filling the void between the blocks and the walls and the roof will not be an easy task. When the backfilling is completed it is time for construction of the sealing plug. SKB is investigating different designs of this plug. The plug will be a cast low-pH concrete plug but it is still open if it will be a short reinforced plug or a longer taped plug or if we need a bentonite plug between the backfill and the concrete construction. (author)

  1. Using TOUGH2 to model the coupled effects of gas generation, repository consolidation, and multiphase brine and gas flow at the Waste Isolation Pilot Plant

    International Nuclear Information System (INIS)

    The Waste Isolation Pilot Plant (WIPP) is a US Department of Energy facility designed to demonstrate the safe underground disposal of transuranic waste. Following waste emplacement, each room will be backfilled with crushed salt. Due to deviatoric stress introduced by excavation, the walls of the waste disposal rooms in the repository will deform over time, consolidating waste containers and salt backfill, thereby decreasing the void volume of the repository. Long-term repository assessment must consider the processes of gas generation, room closure and expansion due to salt creep, and multiphase (brine and gas) fluid flow, as well as the complex coupling between these three processes. Stone (1992) used the mechanical creep closure code SANCHO to simulate the closure of a single, perfectly sealed disposal room filled with waste and backfill. The results of the SANCHO f-series simulations provide a relationship between gas generation, room closure, and room pressure. Several methods for coupling this relationship with multiphase fluid flow into and out of a room were examined by Freeze et al. TOUGH2 was employed to couple the processes of gas generation, room closure/consolidation, and multiphase brine and gas flow. Two empirically-based methods for approximating salt creep and room consolidation were implemented in TOUGH2: the pressure-time-porosity line interpolation approach and the fluid-phase-salt approach. Both approaches utilized links to the SANCHO f-series simulation results to calculate room-void-volume changes with time during a simulation

  2. CORALUS phase II. Gas release and migration in the boom clay of mol within the project 'Corrosion of Active Glass in the Underground conditions'

    International Nuclear Information System (INIS)

    Within the scope of national and international radioactive waste disposal concepts, the intention is to isolate them in deep geological formations in order to avoid the release of radionuclides into the biosphere above an acceptable limit. Besides salt and granite, clay formations are investigated. For investigating the suitability of clay formations in terms of their physical and chemical behaviour, the Belgian research centre SCK-CEN is performing an in situ test called CORALUS (CORrosion of Active gLass in Underground Storage conditions) in the Boom clay of the Underground Research Facility HADES in Mol /VAL 97/. The overall objective of the CORALUS project is to study the performance of both active and inactive HLW glass specimens in direct contact with different types of backfill materials under conditions as representative as possible for those expected to prevail in a disposal site in the Boom clay formation (α- and γ-irradiation, temperature, pressure, backfill material, formation water,..). The experimental set-up represents a scenario in which the vitrified waste comes into direct contact with the interacting backfill material and/or the Boom clay. (orig.)

  3. Gas release and migration in the boom clay of mol within the project 'Corrosion of Active Glass in the Underground conditions' (CORALUS)

    International Nuclear Information System (INIS)

    Within the scope of national and international radioactive waste disposal concepts, the intention is to dispose of radioactive waste in deep geological formations, in order to isolate them from the biosphere and avoid the release of radionuclides above an acceptable limit. Besides salt and granite, clay formations are investigated. For investigating the suitability of clay formations in terms of their physical and chemical behaviour, the Belgian research centre SCK-CEN is performing an in situ test called CORALUS (CORrosion of Active gLass in Underground Storage conditions) in the Boom clay of the Underground Research Facility HADES in Mol/VAL 97/. The overall objective of the CORALUS project is to study the performance of both active and inactive HLW glass specimens in direct contact with different types of backfill materials under conditions as representative as possible for those expected to prevail in a disposal site in the Boom clay formation (α- and γ-irradiation, temperature, pressure, backfill material, formation water,..). The experimental set-up represents a scenario in which the vitrified waste comes into direct contact with the interacting backfill material and/or the Boom clay, because of the occurrence of fissures in the waste canisters and the metallic overpack. (orig.)

  4. Review of sorption and diffusion parameters for TVO-92

    International Nuclear Information System (INIS)

    Teollisuuden Voima Oy (TVO) is investigating the feasibility to dispose of spent nuclear fuel in a final repository constructed in a crystalline rock formation several hundred meters underground. This work is a part of the program of the updated preliminary safety assessment TVO-92. According to the plans the spent fuel, sealed in copper-iron canisters, is emplaced in drillholes below the tunnel floor and surrounded by bentonite clay buffer. The tunnels are backfilled with a mixture of quartz sand (90%) and bentonite (10%). Migration of solutes is retarded by sorption in the backfill and on fracture surfaces of the rocks and by diffusion into fissures and micropores of the rock. In migration calculations retardation due to sorption is derived from distribution ratios of solutes between water and solid. Migration by diffusion in rock is described by diffusion coefficients. Proposals are made for distribution ratios and diffusion coefficients in the backfill and in rocks for the radionuclides of spent significant with respect to safety of the final disposal. The proposals include realistic values besides the conservative values, leading with a high probability to overestimation of radiation doses in the biosphere. (orig.)

  5. R and D activities for ultimate disposal of HTR spent fuel elements

    International Nuclear Information System (INIS)

    For the direct ultimate disposal of HTR spent fuel, the LWR MAW storage method is examined, with a view to the following aspects: Activity released under rock pressure, and data of the design basis accidents: drop of waste package, underground fire, and inflow of lye in the post-operational phase of the repository. Strength tests with model packages containing HTR spent fuel in loose packing, or backfilled, have shown that backfilling with cement mortar or sand prevents damage to the spent fuel caused by rock pressure. Particle cracking in damaged, not backfilled fuel elements was at a maximum of 1 p.c. In leaching experiments with spent, complete fuel elements (900C - 2000C and 130/300 bar) only contaminations of the graphite matrix were released. Nuclide release after some 100 days of leaching time is determined by diffusion processes, but even after 1250 days of leaching, only trace amounts of Cs, Sr, Ce, Ba, Eu, Co, actinides or heavy metals could be found. High burn-up UO2 fuel kernels without coating and graphite matrix under the effects of leaching at 900C, 130 bar already after 60 days exhibited strong corrosion damage, and after about 100 days, cesium was released almost completely. (orig.)

  6. Prospects for coupled modelling

    Energy Technology Data Exchange (ETDEWEB)

    Savage, D.

    2012-07-01

    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. Significant changes can be expected to occur to the properties and behaviour of buffer and backfill, especially during re-saturation and through the thermal period. Reactions will occur in response to thermal and chemical gradients, induced by the thermal output of the spent fuel and at interfaces between different barrier materials, such as cement/clay, steel/clay etc. Processes of ion exchange, mineral dissolution and precipitation, and swelling can lead to significant re-distribution of mass and evolution of physical properties so that reliable predictive modelling of future behaviour and properties must be made. This report evaluates the current status of modelling of buffer and backfill evolution and tries to assess the potential future capabilities in the short- to medium-term (5-10 years) in a number of technical areas: (1) Non-isothermal (T-H-M-C-B) modelling and the potential for cementation, (2) The consistency of models, (3) Swelling pressure, (4) Cement-bentonite interactions, (5) Iron-bentonite interactions, (6) Mechanical (shear) behavior, and (7) Bentonite erosion.

  7. Waste-filling in fully-mechanized coal mining and its application

    Institute of Scientific and Technical Information of China (English)

    MIAO Xie-xing; ZHANG Ji-xiong; FENG Mei-mei

    2008-01-01

    A fully-mechanized coal mining (FMCM) technology capable of filling up the goaf with wastes (including solid wastes)is described. Industrial tests have proved that by using this technology not only can waste be re-used but also coal resources can be exploited with a higher recovery rate without removing buildings located over the working faces. Two special devices, a hydraulic support and a scraper conveyor, run side-by-side on the same working face to simultaneously realize mining and filling. These are described in detail. The tests allow analysis of rock pressure and ground subsidence when backfilling techniques are employed.These values are compared to those from mining without using backfilling techniques, under the same geological conditions. The concept of equivalent mining height is proposed based on theoretical analysis of rock pressure and ground subsidence. The upper limits of the rock pressure and ground subsidence can be estimated in backfilling mining using this concept along with traditional engineering formulae.

  8. Investigation of stress in a circular tunnel due to overburden and thermal loading of horizontally placed 21 PWR multi purpose canisters

    International Nuclear Information System (INIS)

    The drift of a High Level Nuclear Waste (HLNW) Repository were subjected to 2-D thermal loading resulting from the horizontal emplacement of 125 Ton Multi-Purpose Canisters (MPC). Ten 2-D temperature profiles, resulting from 57 Kw/acre and 114 Kw/acre thermal loading conditions, were used in a finite element analysis of the drift; in which a quadrant of the drift and surrounding rock ±100m above and below the drift were modeled. Our analysis shows that the 114 Kw/acre thermal loading results in compressive stresses around the drift, 60 years after emplacement, that exceed the unconfined compressive strength of the TSW tuff analyzed. Stresses resulting from a 57 Kw/acre thermal loading are within the acceptable limit in tunnel rock. A parametric analysis of the invert backfill material showed that Young's modulus for the invert backfill should closely match that of the surrounding unconfined rock in the tunnel in order to prevent an unacceptable stress rise in both rock and backfill

  9. Increasing the stability of DNA-functionalized gold nanoparticles using mercaptoalkanes

    Energy Technology Data Exchange (ETDEWEB)

    Stakenborg, T., E-mail: tim.stakenborg@imec.b [Veterinary Research Institute, Department of Bacteriology and Immunology (Belgium); Peeters, S.; Reekmans, G.; Laureyn, W.; Jans, H.; Borghs, G. [IMEC vzw, Nano Engineered Component Science (Belgium); Imberechts, H. [Veterinary Research Institute, Department of Bacteriology and Immunology (Belgium)

    2008-12-15

    In this work, the stability of DNA functionalized gold nanoparticles was examined in relation to their size, temperature, as well as the presence of mono- and bivalent ions. Furthermore, we report on the stabilizing effect of an additional post-functionalization with mercaptoalkanes, optionally bearing triethylene glycol (TEG) units. Although such so-called backfilling molecules are commonly used for planar gold surfaces, they have rarely been reported in combination with DNA-functionalized nanoparticles. Our results show that, conform the DLVO theory, smaller citrate-capped gold nanoparticles were more stable towards higher concentrations of salt. Citrate nanoparticles of 30 nm in size were only stable in sodium chloride concentrations up to {approx}0.05 M and up to 45 {sup o}C. The stability of these uncoated nanoparticles was even lower when bivalent salts were used (i.e. <2 x 10{sup -4} M). Immobilization of DNA on these nanoparticles, on the other hand, improved the stability in salt solutions with at least one order of magnitude. The additional use of backfilling molecules stabilized the gold nanoparticles even further, without negatively affecting the DNA hybridization efficiency. DNA functionalization also had a positive impact on the thermal stability of the nanoparticles. Unfortunately, this beneficial effect was not observed after a subsequent backfilling step.

  10. Increasing the stability of DNA-functionalized gold nanoparticles using mercaptoalkanes

    International Nuclear Information System (INIS)

    In this work, the stability of DNA functionalized gold nanoparticles was examined in relation to their size, temperature, as well as the presence of mono- and bivalent ions. Furthermore, we report on the stabilizing effect of an additional post-functionalization with mercaptoalkanes, optionally bearing triethylene glycol (TEG) units. Although such so-called backfilling molecules are commonly used for planar gold surfaces, they have rarely been reported in combination with DNA-functionalized nanoparticles. Our results show that, conform the DLVO theory, smaller citrate-capped gold nanoparticles were more stable towards higher concentrations of salt. Citrate nanoparticles of 30 nm in size were only stable in sodium chloride concentrations up to ∼0.05 M and up to 45 oC. The stability of these uncoated nanoparticles was even lower when bivalent salts were used (i.e. -4 M). Immobilization of DNA on these nanoparticles, on the other hand, improved the stability in salt solutions with at least one order of magnitude. The additional use of backfilling molecules stabilized the gold nanoparticles even further, without negatively affecting the DNA hybridization efficiency. DNA functionalization also had a positive impact on the thermal stability of the nanoparticles. Unfortunately, this beneficial effect was not observed after a subsequent backfilling step.

  11. Geoelectric monitoring of bentonite barrier resaturation in the Aespoeprototype repository. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Wieczorek, Klaus; Komischke, Michael; Miehe, Ruediger; Moog, Helge

    2014-10-15

    In 1994, SKB started constructing the ''Prototype Repository'', a full-scale replica of a part of a future KBS-3 repository in crystalline rock, at the AespoeHard Rock Laboratory. Six emplacement boreholes were planned and constructed in two tunnel sections until end of 1999. The international EC co-funded Prototype Repository project was started in 2000 (contract FIKW-CT-2000-00055). The project partners were SKB (Sweden), POSIVA (Finland), ENRESA (Spain), GRS (Germany), BGR (Germany), UWC (UK), and JNC (Japan). Between 2000 and 2003 the complete Prototype Repository was equipped and instrumented, and monitoring was started. In February 2004 the EC funding expired. The Prototype Repository project was continued with national funding of the project partners. In 2011, dismantling of Section II was started in a three-year project. Backfill, buffer and canisters as well as part of the instrumentation were retrieved, and numerous laboratory investigations on buffer and backfill samples were performed. GRS' part in the Prototype Repository was the monitoring of backfill and buffer resaturation using geoelectric tomography. The measurements were completed in 2013.

  12. The integrated interaction between high-level waste glass and the near field barriers

    International Nuclear Information System (INIS)

    The objective of this report is to assess the long-term stability of high-level waste glass in the geological disposal conditions of the Boom clay formation (Mol site, Belgium). In particular, research efforts were concentrated on the measurement of the dissolution rate of high-level waste glass in the presence of the host rock (Boom clay) and engineered barriers. The influence of three candidate backfill materials (bentonite, sand, and concrete) on the dissolution rate is assessed. The dissolution rate of high-level waste glass is measured by performing leaching experiments in the presence of claywater, Boom clay, and various canister, overpack, and backfill materials. These corrosion tests were carried out at 90 degrees Celsius and at different exposed surface area to volume ratios, namely 10 m-1, 100 m-1, and 1000 m-1. The duration of the tests varies from 30 to 90 days. From the experimental results is concluded that the dissolution of the Pamela/DWK SM513 glass is not affected by the presence of the three candidate backfill materials while in the presence of concrete, the dissolution of the glass is reduced in the short-term. (A.S.)

  13. Review of the sorption of actinides on natural minerals

    International Nuclear Information System (INIS)

    Over the past few years, a large body of data concerning sorption of actinides on geologic media has been built in connection with high-level-waste disposal. The primary aim of the work has been to allow predictions of the migration behavior of these radionuclides in the case of a breach of the repository that allowed groundwater flow through the repository. As a result of this work, some new backfill materials specifically tailored for the actinides have also been designed. Several major mechanisms of sorption that appear to dominate the sorption of actinides have emerged from these studies. These mechanisms can be divided into solution reactions dominated by hydrolysis, chemisorption reactions, and oxidation-reduction reactions. Each of these mechanisms will be discussed in detail, with experimental examples. Surprisingly, one mechanism, cation exchange, does not play an important role; why it fails to operate in any significant way in the environmental pH region will be discussed. The implications of the sorption mechanisms for waste forms and backfill materials will be discussed in detail. These discussions will center primarily around the valence state of the actinide in various waste forms and the effect of various anions on leachability from waste forms and backfill materials

  14. Geoelectric monitoring of bentonite barrier resaturation in the Aespoeprototype repository. Final report

    International Nuclear Information System (INIS)

    In 1994, SKB started constructing the ''Prototype Repository'', a full-scale replica of a part of a future KBS-3 repository in crystalline rock, at the AespoeHard Rock Laboratory. Six emplacement boreholes were planned and constructed in two tunnel sections until end of 1999. The international EC co-funded Prototype Repository project was started in 2000 (contract FIKW-CT-2000-00055). The project partners were SKB (Sweden), POSIVA (Finland), ENRESA (Spain), GRS (Germany), BGR (Germany), UWC (UK), and JNC (Japan). Between 2000 and 2003 the complete Prototype Repository was equipped and instrumented, and monitoring was started. In February 2004 the EC funding expired. The Prototype Repository project was continued with national funding of the project partners. In 2011, dismantling of Section II was started in a three-year project. Backfill, buffer and canisters as well as part of the instrumentation were retrieved, and numerous laboratory investigations on buffer and backfill samples were performed. GRS' part in the Prototype Repository was the monitoring of backfill and buffer resaturation using geoelectric tomography. The measurements were completed in 2013.

  15. Development of mechanical coupled analysis technique for the long term behavior of the near field (2)

    International Nuclear Information System (INIS)

    In evaluating the long term mechanical behavior of the near field containing Engineered Barrier System (EBS), it is essential to take into consideration the behaviors which affect the stress and deformation of the buffer material. The 3-D mechanical coupled analysis technique for the long term mechanical behavior of near field is developed. The object of analysis is extended to the disposal gallery and the near field rock, in addition to the buffer material and the overpack for previous one. The analysis model is developed with a degradation model of concrete support and modeling of the near field rock with the valuable- compliance-type constitutive equation. The remaining problems of current study are related to; 1) mechanical property and modeling of backfill material, 2) adopting a degradation model of concrete support in the prototype model, 3) examining the effect of analytical model mesh and time step for the 3-D mechanical coupled analysis. We conducted the one-dimensional consolidation test for the backfill material. The backfill material shows a similar behavior to that of buffer material. And the prototype model is developed adopting a degradation model for a concrete support and examining the effect of the model mesh and time step. The result shows that a degradation of concrete support affects the mechanical behavior of the near field. It is concluded this analysis technique is promising for evaluation of the long term mechanical behavior of the near field. (author)

  16. Thermo-hydro-mechanical modelling of buffer, synthesis report

    International Nuclear Information System (INIS)

    This study addresses analyses of coupled thermo-hydro-mechanical (THM) processes in a scheme considered for the spent nuclear fuel repository in Olkiluoto (Finland). The finite element code CODEBRIGHT is used to perform modelling calculations. The objective of the THM modelling was to study some fundamental design parameters. The time required to reach full saturation, the maximum temperature reached in the canister, the deformations in the buffer-backfill interface, the stress-deformation balance between the buffer and the backfill, the swelling pressure developed and the homogenization process development are critical variables. Because of the complexity of the THM processes developed, only a single deposition hole has been modelled with realistic boundary conditions which take into account the entire repository. A thermal calculation has been performed to adopt appropriate boundary conditions for a reduced domain. The modelling has been done under axisymmetric conditions. As a material model for the buffer bentonite and backfill soil, the Barcelona Basic Model (BBM) has been used. Simulation of laboratory tests conducted at B and Tech under supervision of Posiva has been carried out in order to determine the fundamental mechanical parameters for modelling the behaviour of MX-80 bentonite using the BBM model. The modelling process of the buffer-backfill interface is an essential part of tunnel backfill design. The calculations will aim to determine deformations in this intersection, the behaviour of which is important for the buffer swelling. The homogenization process is a key issue as well. Porosity evolution during the saturation process is evaluated in order to check if the final saturated density accomplishes the homogenization requirements. This report also describes the effect of the existence of an air-filled gap located between the canister and the bentonite block rings in thermo-hydro-mechanical behaviour of the future spent nuclear fuel repository in

  17. Earth dam plug for sealing of underground repositories

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. As a part of the stepwise more detailed design of the sealing and closure of the Swedish final repository for short lived radioactive waste, a concept for an 'earth dam plug' has been developed by SKB. The function of the plug is to decrease the ground water flow through the rock vaults and silo. The plug consists of the following principal parts: 1. Tunnel sections filled with bentonite which acts as a hydraulic seal 2. Tunnel sections filled with a mixture of 30% bentonite and 70% crushed rock that act as a transition material and transfers the load from the swelling bentonite to the adjacent backfill material and the rock. 3. Temporary concrete walls that are needed for the installation 4. Backfill material consisting of crushed rock that confines the transition material and transfers the load to the rock walls, roof and floor. The transition material is compacted in place in inclined layers, a method originally developed by SKB for backfilling of deposition tunnels in the KBS-3 repository. The tunnel contour is adjusted so that the transition material is confined by the crushed rock backfill. As the bentonite is saturated it will expand and build up a swelling pressure against the transition material. This will be compressed. The major part of the load will be transferred to the crushed rock as a smaller part of the load will be transferred to the rock contact. Analytic calculations show that for the geometry illustrated to the left in Figure 1 the combined compression of the transition material and the deformation of the crushed rock will result in a displacement of the transition material in-between 0,15 and 0,55 m for a swelling pressure of 2 Mpa. This is based on relatively conservative assumptions for the deformation properties of the crushed rock. If the displacement of the transition material leads to zones with higher hydraulic conductivity or other damages the bentonite is assumed to move into the zone

  18. Challenges in planning and performing the retrieval of the prototype repository at Aespoe HRL- Project management's reflections and practical experiences from field work

    International Nuclear Information System (INIS)

    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 overall objective of the trial 'Prototype Repository' is to test and demonstrate the integrated function of sub-components in a final repository under realistic full-scale conditions. Data from the experiment shall also be compared to results from modelling based on site conditions. Opening of the outer section for the Prototype Repository was recognized as substantial operation. No trial of this size has been made earlier with regard to removal of buffer and backfilling. Experience was available only from retrieval of the buffer in Canister Retrieval Test at Aespoe HRL where samples of the buffer were taken, down to the mid-height of the canister. It was expected that sampling of the buffer in the deposition holes of the Prototype Repository would be very difficult, especially deep down in the holes. No significant experience regarding the breaching of such a concrete plug or removing backfill was available. The lack of experience together with the size of the project made extensive planning essential before the opening and removal could begin. It was decided that SKB (Sweden) and Posiva Oy (Finland) should run the project in a co-operation, where SKB is responsible for managing the project. In addition, a wide international interest was observed and accordingly waste management organisations were invited by SKB and Posiva to be a party to the Retrieval of the Prototype Repository. Six individual project agreements were signed with Andra (France), NUMO (Japan), NDA (United Kingdom), NAGRA (Switzerland), BMWi (Germany) and NWMO (Canada). The planning of the Retrieval of the Prototype Repository (section II) started at the beginning of 2010. The planning phase was successful meaning that the breaching of

  19. Experimental programme to demonstrate the viability of the supercontainer concept for HLW

    International Nuclear Information System (INIS)

    The EIG EURIDICE (a joint venture between the Belgian Organisation for Radioactive Waste Management - ONDRAF/NIRAS - and the Belgian Nuclear Research Centre - SCKoCEN) is responsible for performing large-scale tests, technical demonstrations and experiments to assess the feasibility of a final disposal of vitrified radioactive waste in deep clay layers. This is part of the Belgian Research and Development programme managed by ONDRAF/NIRAS. The current Belgian reference design for vitrified HLW and spent fuel assemblies is the so-called Supercontainer design. The vitrified waste canisters or spent fuel assemblies are enclosed in a carbon steel overpack which has to prevent contact between water from the host formation and the waste during the thermal phase. In order to maintain favourable chemical conditions to avoid corrosion during this period (several hundred or even thousand of years), the overpack is surrounded by a high alkaline concrete buffer of about 70 cm thick. The buffer also provides permanent radiological shielding for the workers, simplifying handling and other operations. All the components of the Supercontainer are constructed in above ground installations, thus creating favourable QA/QC conditions. After the emplacement of the Supercontainers in the disposal galleries, the remaining space will be backfilled. Tests to demonstrate the viability and the construction feasibility of the supercontainer design have been initiated. The viability programme includes Tests to verify the feasibility to construct and emplace the components of the supercontainers, and tests to verify the feasibility to backfill the disposal galleries once the supercontainers are placed. Supercontainer construction: Tests in column to verify the construction feasibility (risk of cracking) of the buffer with two different types of concrete (a self-compacting concrete - SCC - and a rheoplastic concrete RPC) were performed in collaboration with the Belgian concrete factory Socea. A

  20. Field lysimeter studies for performance evaluation of grouted Hanford defense wastes

    Energy Technology Data Exchange (ETDEWEB)

    Last, G.V.; Serne, R.J.; LeGore, V.L.

    1995-02-01

    The Grout Waste Test Facility (GWTF) consisted of four large field lysimeters designed to test the leaching and migration rates of grout-solidified low-level radioactive wastes generated by Hanford Site operations. Each lysimeter was an 8-m-deep by 2-media closed-bottom caisson that was placed in the ground such that the uppermost rim remained just above grade. Two of these lysimeters were used; the other two remained empty. The two lysimeters that were used (A-1 and B-1) were backfilled with a two-layer soil profile representative of the proposed grout disposal site. The proposed grout disposal site (termed the Grout Treatment Facility Landfill) is located immediately east of the Hanford Site`s 200 East Area. This soil profile consisted of a coarse sand into which the grout waste forms were placed and covered by 4 m of a very fine sand. The A-1 lysimeter was backfilled in March 1985, with a grout-solidified phosphate/sulfate liquid waste from N Reactor decontamination and ion exchange resin regeneration. The B-1 lysimeter was backfilled in September 1985 and received a grout-solidified simulated cladding removal waste representative of waste generated from fuel reprocessing operations at the head end of the Plutonium Uranium Extraction (PUREX) plant. Routine monitoring and leachate collection activities were conducted for over three years, terminating in January 1989. Drainage was collected sporadically between January 1989 and December 1992. Decontamination and decommissioning of these lysimeters during the summer of 1994, confirmed the presence of a 15 to 20-cm-long hairline crack in one of the bottom plate welds. This report discusses the design and construction of the GWTF, presents the routine data collected from this facility through January 1989 and subsequent data collected sporadically between 1989 and 1993, and provides a brief discussion concerning preliminary interpretation of the results.