Development and Demonstration of Material Properties Database and Software for the Simulation of Flow Properties in Cementitious Materials

In-Tank Elutriation Test Report And Independent Assessment

The Salt Disposition Integration (SDI) portfolio of projects provides the infrastructure within existing Liquid Waste facilities to support the startup and long term operation of the Salt Waste Processing Facility (SWPF). Within SDI, the Blend and Feed Project will equip existing waste tanks in the Tank Farms to serve as Blend Tanks where 300,000-800,000 gallons of salt solution will be blended in 1.3 million gallon tanks and qualified for use as feedstock for SWPF. Blending requires the miscible salt solutions from potentially multiple source tanks per batch to be well mixed without disturbing settled sludge solids that may be present in a Blend Tank. Disturbing solids may be problematic both from a feed quality perspective as well as from a process safety perspective where hydrogen release from the sludge is a potential flammability concern. To develop the necessary technical basis for the design and operation of blending equipment, Savannah River National Laboratory (SRNL) completed scaled blending and transfer pump tests and computational fluid dynamics (CFD) modeling. A 94 inch diameter pilot-scale blending tank, including tank internals such as the blending pump, transfer pump, removable cooling coils, and center column, were used in this research. The test tank represents a 1/10.85 scaled version of an 85 foot diameter, Type IIIA, nuclear waste tank that may be typical of Blend Tanks used in SDI. Specifically, Tank 50 was selected as the tank to be modeled per the SRR, Project Engineering Manager. SRNL blending tests investigated various fixed position, non-rotating, dual nozzle pump designs, including a blending pump model provided by the blend pump vendor, Curtiss Wright (CW). Primary research goals were to assess blending times and to evaluate incipient sludge disturbance for waste tanks. Incipient sludge disturbance was defined by SRR and SRNL as minor blending of settled sludge from the tank bottom into suspension due to blending pump operation, where the sludge level was shown to remain constant. To experimentally model the sludge layer, a very thin, pourable, sludge simulant was conservatively used for all testing. To experimentally model the liquid, supernate layer above the sludge in waste tanks, two salt solution simulants were used, which provided a bounding range of supernate properties. One solution was water (H{sub 2}O + NaOH), and the other was an inhibited, more viscous salt solution. The research performed and data obtained significantly advances the understanding of fluid mechanics, mixing theory and CFD modeling for nuclear waste tanks by benchmarking CFD results to actual experimental data. This research significantly bridges the gap between previous CFD models and actual field experiences in real waste tanks. A finding of the 2009, DOE, Slurry Retrieval, Pipeline Transport and Plugging, and Mixing Workshop was that CFD models were inadequate to assess blending processes in nuclear waste tanks. One recommendation from that Workshop was that a validation, or bench marking program be performed for CFD modeling versus experiment. This research provided experimental data to validate and correct CFD models as they apply to mixing and blending in nuclear waste tanks. Extensive SDI research was a significant step toward bench marking and applying CFD modeling. This research showed that CFD models not only agreed with experiment, but demonstrated that the large variance in actual experimental data accounts for misunderstood discrepancies between CFD models and experiments. Having documented this finding, SRNL was able to provide correction factors to be used with CFD models to statistically bound full scale CFD results. Through the use of pilot scale tests performed for both types of pumps and available engineering literature, SRNL demonstrated how to effectively apply CFD results to salt batch mixing in full scale waste tanks. In other words, CFD models were in error prior to development of experimental correction factors determined during this research, which provided a technique to use CFD models for salt batch mixing and transfer pump operations. This major scientific advance in mixing technology resulted in multi-million dollar cost savings to SRR. New techniques were developed for both experiment and analysis to complete this research. Supporting this success, research findings are summarized in the Conclusions section of this report, and technical recommendations for design and operation are included in this section of the report.

Gelfill (GF) is made of tailings, water, binder and chemical additives (Fillset, sodium silicate gel). The components of GF are combined and mixed on the surface and transported (by gravity and/or pumping) to the underground mine workings, where the GF can be used for both underground mine support and tailings storage. Thermal (T), hydraulic (H), and mechanical (M) properties are important performance criteria of GF. The understanding of these engineering properties and their evolution with time are still limited due to the fact that GF is a new cemented backfill material. In this thesis, the evolution of the thermal, hydraulic, mechanical, and microstructural properties of small GF samples are determined. Various binder contents of Portland cement type I (PCI) are used. The GF is cured for 3, 7, 28, 90, and 120 days. It is found that the thermal, hydraulic and mechanical properties are time-dependent or affected by the degree of binder hydration index. Furthermore, a relationship is found between the compressive strength and the saturated hydraulic conductivity of the GF samples. The unsaturated hydraulic properties of GF samples have also been investigated. The outcomes show that unsaturated hydraulic conductivity is influenced by the degree of binder hydration index and binder content, especially at low suction ranges. Simple functions are proposed to predict the evolution of air-entry values (AEVs), residual water content, and fitting parameters from the van Genuchten model with the degree of hydration index (α). Furthermore, two columns are built to simulate the coupled thermo-hydro-mechanical (THM) behaviour of GF under drained and undrained conditions. The obtained results from the GF columns are compared with the small samples. It is observed that the mechanical properties, hydraulic properties (suction and water content), and temperature development are strongly coupled. The magnitude of these THM coupling factors is affected by the size of the GF. The findings also show that the mechanical, hydraulic and thermal properties of the GF columns are different from samples cured in plastic moulds.

Due to climate-induced variations, changes in the water content of the soil occur, and consequently its hydraulic and thermal properties change as well. Bedding materials for buried energy cables or geothermal installations are usually in capillary contact to the surrounding soil. Thus, they are subject to seasonal changes in the water content caused by natural climatic variations. For the design and construction of structures using thermal energy or dissipating waste heat in the shallow ground, it is important to be able to make reliable forecasts of the thermal and hydraulic properties of partially saturated bedding materials and soils. For this purpose, the climate-related changes of the thermal and hydraulic properties have to be investigated. In this technical note, an experimental setup is described, allowing for the simultaneous measurement of several hydraulic and thermal parameters during dewatering of a specimen. From the data, interrelations between thermal conductivity and water content, water retention characteristics and unsaturated hydraulic conductivity can be derived. This is why, a common evaporation test device was extended using a thermal needle probe. This setup enabled the examination of disturbed and undisturbed soils. A further method, which is also presented in this paper, provides the possibility of investigating cementitious bedding materials in this evaporation test for the first time. This experiment takes only a few days for cementitious bedding materials as well as for undisturbed soil samples. Thus, with only one single experiment, all the basic parameters required for unsaturated hydraulic modeling can be identified. Since thermal conductivity is measured along with the hydraulic parameters, it is possible to assign a value to the thermal conductivity for many hydraulic states of the soil or bedding material.

Cementitious materials can be considered as consisting of particulate elements on the levels of the microstructure and mesostructure. The mechanical properties of cementitious granular materials were studied by a numerical approach. First, an ellipsoid-based method was developed to generate single aggregate particles of arbitrary shape. The HADES toolbox was then used to form a material structure from aggregate (HADES is a concurrent, algorithm-based program that is designed to simulate the mixing or flow of granular material of arbi- trary shape). Afterwards, an interfacial transition zone (ITZ) between the aggregate particles and the cement paste was enriched and a special tool, Gmsh, was used for forming a mesh of aggregate, cement paste, and ITZ. Finally, the mesh data was transferred into the finite element code FEAP to predict the mechanical properties of the material. Based on these processes, a simulation of concrete was used as an example of a typical cementitious granular material. Additionally, a parameter study was conducted to highlight the influence of aggregate on the mechanical properties. The simulation shows that the method is feasible and effectively predicts the elastic modulus of three-phase cementitious granular materials (cement paste, ITZ and aggregate).

Savannah River National Laboratory (SRNL) has been providing radiological performance assessment analysis for Savannah River Site (SRS) solid waste disposal facilities (McDowell-Boyer 2000). The performance assessment considers numerous potential exposure pathways that could occur in the future. One set of exposure scenarios, known as inadvertent intruder analysis, considers the impact on hypothetical individuals who are assumed to inadvertently intrude onto the waste disposal site. An Automated Intruder Analysis application was developed by SRNL (Koffman 2004) that simplifies the inadvertent intruder analysis into a routine, automated calculation. Based on SRNL's experience, personnel from Planning Integration & Technology of Closure Business Unit asked SRNL to assist with inadvertent intruder calculations for F Tank Farm to support the development of the Tank Closure Waste Determination Document. Meetings were held to discuss the scenarios to be calculated and the assumptions to be used in the calculations. As a result of the meetings, SRNL was asked to perform four scenario calculations. Two of the scenarios are the same as those calculated by the Automated Intruder Analysis application and these can be calculated directly by providing appropriate inputs. The other two scenarios involve use of groundwater by the intruder and the Automated Intruder Analysis application was adapted to perform these calculations. The four calculations to be performed are: (1) A post-drilling scenario in which the drilling penetrates a transfer line. (2) A calculation of internal exposure due to drinking water from a well located near a waste tank. (3) A post-drilling calculation in which waste is introduced by irrigation of the garden with water from a well located near a waste tank. (4) A resident scenario where a house is built above transfer lines. Note that calculations 1 and 4 use sources from the waste inventory in the transfer line (given in Table 1) whereas calculations 2 and 3 use sources from groundwater beneath the waste tank (given in Appendix B). It is important to recognize that there are two different sources in the calculations. In these calculations, assumptions are made for parameter values. Three key parameters are the size of the garden, the amount of vegetables eaten, and the distance of the well from the waste tank. For these three parameters, different values are considered in the calculations to determine the impact of the change in these parameters. Another key parameter is the length of time of institutional control, which determines when an inadvertent intruder could first be exposed. The standard length of time for institutional control is 100 years from the time of closure. In this analysis, waste inventory values are used from year 2005 but tanks will not be closed until year 2020. Thus, the effective length of time of institutional control used in the calculations is 115 years from year 2005, which is taken to be time zero for radiological decay calculations. All calculations are carried out for a period of 10,000 years.

Forty three of the High Level Waste (HLW) tanks at the Savannah River Site (SRS) have internal structures that hinder removal of the last approximately five thousand gallons of waste sludge solely by mechanical means. Chemical cleaning can be utilized to dissolve the sludge heel with oxalic acid (OA) and pump the material to a separate waste tank in preparation for final disposition. This dissolved sludge material is pH adjusted downstream of the dissolution process, precipitating the sludge components along with sodium oxalate solids. The large quantities of sodium oxalate and other metal oxalates formed impact downstream processes by requiring additional washing during sludge batch preparation and increase the amount of material that must be processed in the tank farm evaporator systems and the Saltstone Processing Facility. Enhanced Chemical Cleaning (ECC) was identified as a potential method for greatly reducing the impact of oxalate additions to the SRS Tank Farms without adding additional components to the waste that would extend processing or increase waste form volumes. In support of Savannah River Site (SRS) tank closure efforts, the Savannah River National Laboratory (SRNL) conducted Real Waste Testing (RWT) to evaluate an alternative to the baseline 8 wt. % OA chemical cleaning technology for tank sludge heel removal. The baseline OA technology results in the addition of significant volumes of oxalate salts to the SRS tank farm and there is insufficient space to accommodate the neutralized streams resulting from the treatment of the multiple remaining waste tanks requiring closure. ECC is a promising alternative to bulk OA cleaning, which utilizes a more dilute OA (nominally 2 wt. % at a pH of around 2) and an oxalate destruction technology. The technology is being adapted by AREVA from their decontamination technology for Nuclear Power Plant secondary side scale removal. This report contains results from the SRNL small scale testing of the ECC process using SRS sludge tank sample material. A Task Technical and Quality Assurance Plan (TTQAP) details the experimental plan as outlined by the Technical Task Request (TTR). The TTR identifies that the data produced by this testing and results included in this report will support the technical baseline with portions having a safety class functional classification. The primary goals for SRNL RWT are as follows: (1) to confirm ECC performance with real tank sludge samples, (2) to determine the impact of ECC on fate of actinides and the other sludge metals, and (3) to determine changes, if any, in solids flow and settling behavior.

This is the second of two papers investigating the mechanical response of cemented granular materials by means of contact dynamics simulations. In this paper, a two-dimensional polydisperse sample with high void ratio is sheared in a load-controlled simple shear numerical device until the stress state of the sample reaches the yield stress. We first study the stress transmission properties of the granular material in terms of the fabric of different subsets of contacts characterized by the magnitude of their normal forces. This analysis highlights the existence of a peculiar force carrying structure in the cemented material, which is reminiscent of the bimodal stress transmission reported for cohesionless granular media. Then, the evolution of contact forces and torques is investigated trying to identify the micromechanical conditions that trigger macroscopic yielding. It is shown that global failure can be associated to the apparition of a group of particles whose contacts fulfill at least one of the local rupture conditions. In particular, these particles form a large region that percolates through the sample at the moment of failure, evidencing the relationship between macroscopic yielding and the emergence of large-scale correlations in the system.

The Hanford Tank Waste Treatment and Immobilization Plant (WTP) Project is currently transitioning its emphasis from an engineering design and construction phase toward facility completion, start-up and commissioning. With this transition, the WTP Project has initiated more detailed assessments of the requirements that must be met during the actual processing of the Hanford Site tank waste. One particular area of interest is the waste qualification program. In general, the waste qualification program involves testing and analysis to demonstrate compliance with waste acceptance criteria, determine waste processability, and demonstrate laboratory-scale unit operations to support WTP operations. The testing and analysis are driven by data quality objectives (DQO) requirements necessary for meeting waste acceptance criteria for transfer of high-level wastes from the tank farms to the WTP, and for ensuring waste processability including proper glass formulations during processing within the WTP complex. Given the successful implementation of similar waste qualification efforts at the Savannah River Site (SRS) which were based on critical technical support and guidance from the Savannah River National Laboratory (SRNL), WTP requested subject matter experts (SMEs) from SRNL to support a technology exchange with respect to waste qualification programs in which a critical review of the WTP program couldmore » be initiated and lessons learned could be shared. The technology exchange was held on July 18-20, 2011 in Richland, Washington, and was the initial step in a multi-phased approach to support development and implementation of a successful waste qualification program at the WTP. The 3-day workshop was hosted by WTP with representatives from the Tank Operations Contractor (TOC) and SRNL in attendance as well as representatives from the US DOE Office of River Protection (ORP) and the Defense Nuclear Facility Safety Board (DNFSB) Site Representative office. The purpose of the workshop was to share lessons learned and provide a technology exchange to support development of a technically defensible waste qualification program. The objective of this report is to provide a review, from SRNL's perspective, of the WTP waste qualification program as presented during the workshop. In addition to SRNL's perspective on the general approach to the waste qualification program, more detailed insight into the specific unit operations presented by WTP during the workshop is provided. This report also provides a general overview of the SRS qualification program which serves as a basis for a comparison between the two programs. Recommendations regarding specific steps are made based on the review and SRNL's lessons learned from qualification of SRS low-activity waste (LAW) and high-level waste (HLW) to support maturation of the waste qualification program leading to WTP implementation.« less

The Hanford Tank Waste Treatment and Immobilization Plant (WTP) is currently transitioning its emphasis from a design and construction phase toward start-up and commissioning. With this transition, the WTP Project has initiated more detailed assessments of the requirements related to actual processing of the Hanford Site tank waste. One particular area of interest is the waste qualification program to be implemented to support the WTP. Given the successful implementation of similar waste qualification efforts at the Savannah River Site (SRS), based on critical technical support and guidance from the Savannah River National Laboratory (SRNL), WTP requested the utilization of subject matter experts from SRNL to support a technology exchange to perform a review of the WTP waste qualification program, discuss the general qualification approach at SRS, and to identify critical lessons learned through the support of DWPF's sludge batch qualification efforts. As part of Phase 1, SRNL subject matter experts in critical technical and/or process areas reviewed specific WTP waste qualification information. The Phase 1 review was a collaborative, interactive, and iterative process between the two organizations. WTP provided specific analytical procedures, descriptions of equipment, and general documentation as baseline review material. SRNL subject matter experts reviewed the information and, as appropriate, requested follow-up information or clarification to specific areas of interest. This process resulted in multiple teleconferences with key technical contacts from both organizations resolving technical issues that lead to the results presented in this report. This report provides the results of SRNL's Phase 1 review of the WAC-DQO waste acceptance criteria and processability parameters, and the specific unit operations which are required to support WTP waste qualification efforts. The review resulted in SRNL providing concurrence, alternative methods, or gap identification for the proposed WTP analytical methods or approaches. For the unit operations, the SRNL subject matter experts reviewed WTP concepts compared to what is used at SRS and provided thoughts on the outlined tasks with respect to waste qualification. Also documented in this report are recommendations and an outline on what would be required for the next phase to further mature the WTP waste qualification program.

Image processing of the pozzolanic reactions in Roman mortars via X-Ray Map Analyser

The primary objective of the DOE-NE Nuclear Hydrogen Initiative (NHI) is to develop the nuclear hydrogen production technologies necessary to produce hydrogen at a cost competitive with other alternative transportation fuels. The focus of the NHI is on thermochemical cycles and high temperature electrolysis that can be powered by heat from high temperature gas reactors. The Savannah River National Laboratory (SRNL) has been tasked with the primary responsibility to perform research and development in order to characterize, evaluate and develop the Hybrid Sulfur (HyS) thermochemical process. This report documents work during the first quarter of Fiscal Year 2009, for the period between January 1, 2009 and March 31, 2009. The HyS Process is a two-step hybrid thermochemical cycle that is part of the 'Sulfur Family' of cycles. As a sulfur cycle, it uses high temperature thermal decomposition of sulfuric acid to produce oxygen and to regenerate the sulfur dioxide reactant. The second step of the process uses a sulfur dioxide depolarized electrolyzer (SDE) to split water and produce hydrogen by electrochemically reacting sulfur dioxide with H{sub 2}O. The SDE produces sulfuric acid, which is then sent to the acid decomposer to complete the cycle. The DOE NHI program is developing the acid decomposer at Sandia National Laboratory for application to both the HyS Process and the Sulfur Iodine Cycle. The SDE is being developed at SRNL. During FY05 and FY06, SRNL designed and conducted proof-of-concept testing for a SDE using a low temperature, PEM fuel cell-type design concept. The advantages of this design concept include high electrochemical efficiency, small footprint and potential for low capital cost, characteristics that are crucial for successful implementation on a commercial scale. During FY07, SRNL extended the range of testing of the SDE to higher temperature and pressure, conducted a 100-hour longevity test with a 60-cm{sup 2} single cell electrolyzer, and designed and built a larger, multi-cell stack electrolyzer. During FY08, SRNL continued SDE development, including development and successful testing of a three-cell electrolyzer stack with a rated capacity of 100 liters per hour. The HyS program for FY09 program will address improving SDE performance by focusing on preventing or minimizing sulfur deposition inside the cell caused by SO{sub 2} crossover, reduction of cell voltage for improved efficiency, an extension of cell operating lifetime. During FY09 a baseline technology development program is being conducted to address each of these issues. Button-cell (2-cm{sup 2}) and single cell (60-cm{sup 2}) SDEs will be fabricated and tested. A pressurized button-cell test facility will be designed and constructed to facilitate addition testing. The single cell test facility will be upgraded for unattended operation, and later for operation at higher temperature and pressure. Work will continue on development of the Gas Diffusion Electrode (GDE), or Gap Cell, as an alternative electrolyzer design approach that is being developed under subcontract with industry partner Giner Electrochemical Systems. If successful, it could provide an alternative means of preventing sulfur crossover through the proton exchange membrane, as well as the possibility for higher current density operation based on more rapid mass transfer in a gas-phase anode. Promising cell components will be assembled into membrane electrode assemblies (MEAs) and tested in the single cell test facility. Upon modification for unattended operation, test will be conducted for 200 hours or more. Both the button-cell and modified single cell facility will be utilized to demonstrate electrolyzer operation without sulfur build-up limitations, which is a Level 1 Milestone.

SRNL has performed an Extraction, Scrub, Strip (ESS) test using the next generation solvent and AP-101 Hanford Waste simulant. The results indicate that the next generation solvent (MG solvent) has adequate extraction behavior even in the face of a massive excess of potassium. The stripping results indicate poorer behavior, but this may be due to inadequate method detection limits. SRNL recommends further testing using hot tank waste or spiked simulant to provide for better detection limits. Furthermore, strong consideration should be given to performing an actual waste, or spiked waste demonstration using the 2cm contactor bank. The Savannah River Site currently utilizes a solvent extraction technology to selectively remove cesium from tank waste at the Multi-Component Solvent Extraction unit (MCU). This solvent consists of four components: the extractant - BoBCalixC6, a modifier - Cs-7B, a suppressor - trioctylamine, and a diluent, Isopar L{trademark}. This solvent has been used to successfully decontaminate over 2 million gallons of tank waste. However, recent work at Oak Ridge National Laboratory (ORNL), Argonne National Laboratory (ANL), and Savannah River National Laboratory (SRNL) has provided a basis to implement an improved solvent blend. This new solvent blend - referred to as Next Generation Solvent (NGS) - is similar to the current solvent, and also contains four components: the extractant - MAXCalix, a modifier - Cs-7B, a suppressor - LIX-79{trademark} guanidine, and a diluent, Isopar L{trademark}. Testing to date has shown that this 'Next Generation' solvent promises to provide far superior cesium removal efficiencies, and furthermore, is theorized to perform adequately even in waste with high potassium concentrations such that it could be used for processing Hanford wastes. SRNL has performed a cesium mass transfer test in to confirm this behavior, using a simulant designed to simulate Hanford AP-101 waste.

The elaboration of green building materials is nowadays a field of intensive researches aiming at reducing human activity impact on the environment. In particular the vegetal fibers are more and more considered to be an alternative renewable and natural raw material in building construction and thermal renovation. This work, carried out in the framework of research program PROMETHE, is devoted to the evaluation of thermo hydro mechanical properties of an insulated material elaborated using cereal straw and various natural mineral cements. In the objective to elaborate an optimal material in respect with its mechanic, hydraulic, thermal, economic and ecologic properties in short and long time, we performed in one hand a multiscale experimental characterization of constituents and in the other hand numerical upscaling simulations. In first glance the new elaborated material represents dense straw fibers plugged into a matrix of mineral cement. The mechanical properties (Young’s modulus and Poisson coefficient), thermal properties (thermal conductivity, linear thermal expansion coefficient and thermal capacity) and hydraulic properties are evaluated using a one step homogenization Mori-Tanaka scheme. While the insulating developed material must be an excellent thermal insulating it must match in the same time the standards in terms of mechanical and hydraulic ones. So it is necessary to search the best mixing volume fraction of mineral matrix and straw fibers in order to satisfy simultaneously thermal, mechanical and hydraulic standards for an insulating material. The numerical simulations and the first laboratory results show that it is possible to obtain such properties for various formulations of reinforced composite using either lime based mortar or plaster as mineral matrix and different volume fractions of straw fibers.

The multistep outflow method is routinely used to characterize the unsaturated hydraulic conductivity of soils. The technique involves placing a soil sample in a pressure plate apparatus, subjecting the sample to multiple gas pressures in discrete steps through time, and measuring the transient volume of pore fluid extracted. Unsaturated hydraulic property values are estimated through inverse modeling of the experimental conditions. In this study the multistep outflow concept was applied to micro-cracked cementitious materials to assess the efficacy of the technique for these materials. The cementitious materials tested were salt-waste simulant grout samples artificially damaged through oven-drying. Compared to typical soils, fractured media exhibit higher saturated conductivity and lower air-entry pressure, and the volume of fluid extractable from fractures is much lower than soil porosity. To accommodate these material differences the standard test apparatus was modified to incorporate a higher conductivity ceramic pressure plate, a high-precision digital balance for logging outflow mass, a low volume (diameter) effluent line, multiple inline high-precision gas regulators, and a high-precision low-range pressure gauge. Testing to date indicates that the modified apparatus can provide a viable means to measure the unsaturated hydraulic properties of micro-fractured cementitious materials. However the accuracy/uniqueness of inverse modeling is limited by the inherent characteristics of fractured media: high saturated conductivity, low air-entry pressure, and strong non-linearities. Hydraulic property results in the form of van Genuchten / Mualem curves are presented for three fractured grout specimens. DOE Performance Assessments often involve cementitious barriers and/or waste forms that are predicted or assumed to degrade over time due to various mechanisms such as carbonation-influenced reinforcing steel corrosion, external sulfate attack, differential settlement, and seismic activity. Physical degradation typically takes the form of small-scale cracking / fracturing, and the affected materials reside in unsaturated hydrogeologic zones. In these cases, unsaturated hydraulic properties are needed for fractured cementitious materials to simulate moisture movement and contaminant transport within and around the facility. The outflow extraction method, as implemented in the present study, provides a suitable method for estimating these material properties.