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User guidelines and best practices for CASL VUQ analysis using Dakota

Adams, Brian M.; Hooper, Russell

Sandia's Dakota software (available at http://dakota.sandia.gov) supports science and engineering transformation through advanced exploration of simulations. Specifically it manages and analyzes ensembles of simulations to provide broader and deeper perspective for analysts and decision makers. This enables them to enhance understanding of risk, improve products, and assess simulation credibility. This manual offers Consortium for Advanced Simulation of Light Water Reactors (LWRs) (CASL) partners a guide to conducting Dakota-based VUQ studies for CASL problems. It motivates various classes of Dakota methods and includes examples of their use on representative application problems. On reading, a CASL analyst should understand why and how to apply Dakota to a simulation problem. This SAND report constitutes the product of CASL milestone L3:VUQ.V&V.P8.01 and is also being released as a CASL unlimited release report with number CASL-U-2014-0038-000.

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TYPE SAND Report YEAR 2014
DOIOSTI

An approach to determine a defensible spent fuel ratio

Durbin, S.; Lindgren, Eric

Sabotage of spent nuclear fuel casks remains a concern nearly forty years after attacks against shipment casks were first analyzed and has a renewed relevance in the post-9/11 environment. A limited number of full-scale tests and supporting efforts using surrogate materials, typically depleted uranium dioxide (DUO2), have been conducted in the interim to more definitively determine the source term from these postulated events. In all the previous studies, the postulated attack of greatest interest was by a conical shape charge (CSC) that focuses the explosive energy much more efficiently than bulk explosives. However, the validity of these large-scale results remain in question due to the lack of a defensible Spent Fuel Ratio (SFR), defined as the amount of respirable aerosol generated by an attack on a mass of spent fuel compared to that of an otherwise identical DUO2 surrogate. Previous attempts to define the SFR have resulted in estimates ranging from 0.42 to 12 and include suboptimal experimental techniques and data comparisons. Different researchers have suggested using SFR values of 3 to 5.6. Sound technical arguments exist that the SFR does not exceed a value of unity. A defensible determination of the SFR in this lower range would greatly reduce the calculated risk associated with the transport and dry storage of spent nuclear fuel. Currently, Oak Ridge National Laboratory (ORNL) is in possession of several samples of spent nuclear fuel (SNF) that were used in the original SFR studies in the 1980s and were intended for use in a modern effort at Sandia National Laboratories (SNL) in the 2000s. A portion of these samples are being used for a variety of research efforts. However, the entirety of SNF samples at ORNL is scheduled for disposition at the Waste Isolation Pilot Plant (WIPP) by approximately the end of 2015. If a defensible SFR is to be determined for use in storage and transportation security analyses, the need to begin this effort is urgent in order to secure the only known available SNF samples with a clearly defined path to disposal.

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TYPE SAND Report YEAR 2014
DOIOSTI

Experiments to populate and validate a processing model for polyurethane foam. BKC 44306 PMDI-10

Mondy, Lisa A.; Bauer, Stephen J.; Hileman, Michael B.; Thompson, Kyle; Smith, David; Rao, Rekha R.; Shelden, Bion; Soehnel, Melissa; O'Hern, Timothy J.; Grillet, Anne M.; Celina, Mathew C.; Wyatt, Nicholas B.; Russick, Edward M.

We are developing computational models to elucidate the expansion and dynamic filling process of a polyurethane foam, PMDI. The polyurethane of interest is chemically blown, where carbon dioxide is produced via the reaction of water, the blowing agent, and isocyanate. The isocyanate also reacts with polyol in a competing reaction, which produces the polymer. Here we detail the experiments needed to populate a processing model and provide parameters for the model based on these experiments. The model entails solving the conservation equations, including the equations of motion, an energy balance, and two rate equations for the polymerization and foaming reactions, following a simplified mathematical formalism that decouples these two reactions. Parameters for the polymerization kinetics model are reported based on infrared spectrophotometry. Parameters describing the gas generating reaction are reported based on measurements of volume, temperature and pressure evolution with time. A foam rheology model is proposed and parameters determined through steady-shear and oscillatory tests. Heat of reaction and heat capacity are determined through differential scanning calorimetry. Thermal conductivity of the foam as a function of density is measured using a transient method based on the theory of the transient plane source technique. Finally, density variations of the resulting solid foam in several simple geometries are directly measured by sectioning and sampling mass, as well as through x-ray computed tomography. These density measurements will be useful for model validation once the complete model is implemented in an engineering code.

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TYPE SAND Report YEAR 2014
DOIOSTI

Dynamical systems probabilistic risk assessment

Denman, Matthew R.; Ames, Arlo

Probabilistic Risk Assessment (PRA) is the primary tool used to risk-inform nuclear power regulatory and licensing activities. Risk-informed regulations are intended to reduce inherent conservatism in regulatory metrics (e.g., allowable operating conditions and technical specifications) which are built into the regulatory framework by quantifying both the total risk profile as well as the change in the risk profile caused by an event or action (e.g., in-service inspection procedures or power uprates). Dynamical Systems (DS) analysis has been used to understand unintended time-dependent feedbacks in both industrial and organizational settings. In dynamical systems analysis, feedback loops can be characterized and studied as a function of time to describe the changes to the reliability of plant Structures, Systems and Components (SSCs). While DS has been used in many subject areas, some even within the PRA community, it has not been applied toward creating long-time horizon, dynamic PRAs (with time scales ranging between days and decades depending upon the analysis). Understanding slowly developing dynamic effects, such as wear-out, on SSC reliabilities may be instrumental in ensuring a safely and reliably operating nuclear fleet. Improving the estimation of a plant's continuously changing risk profile will allow for more meaningful risk insights, greater stakeholder confidence in risk insights, and increased operational flexibility.

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TYPE SAND Report YEAR 2014
DOIOSTI

Definition of the National Rotor Testbed: An Aeroelastically relevant research-scale wind turbine rotor

32nd ASME Wind Energy Symposium

Resor, Brian R.; Maniaci, David C.

Sandia is designing a set of modern, research-quality blades for use on the V27 turbines at the DOE/SNL SWiFT site at Texas Tech University in Lubbock, Texas. The new blades will replace OEM blades and will be a publicly available resource for subscale rotor research. Features of the new blades do not represent the optimal design for a V27 rotor, but are determined by aeroelastic scaling of relevant parameters and design drivers from a representative megawatt-scale rotor. Scaling parameters and design drivers are chosen based two factors: 1) retrofit to the existing SWiFT turbines and 2) replicate rotor loads and wake formation of a utility scale turbine to support turbine -turbine interaction research at multiple scales. The blades are expected to provide a publicly available baseline blade design which will enable increased participation in future blade research as well as accelerated hardware manufacture and test for demonstration of innovation. This paper discusses aeroelastic scaling approaches, a rotor design process and a summary of design concepts.

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TYPE Conference YEAR 2014
OSTIScopus

Large-Scale Data Analytics and Its Relationship to Simulation

Leland, Robert W.

Large-Scale Data Analytics (LSDA) problems require finding meaningful patterns in data sets that are so large as to require leading-edge processing and storage capability. LSDA problems are increasingly important for government mission work, industrial application, and scientific discovery. Effective solution of some important LSDA problems requires a computational workload that is substantially different from that associated with traditional High Performance Computing (HPC) simulations intended to help understand physical phenomena or to conduct engineering. While traditional HPC application codes exploit structural regularity and data locality to improve performance, many analytics problems lead more naturally to very fine-grained communication between unpredictable sets of processors, resulting in less regular communication patterns that do not map efficiently on to typical HPC systems. In both simulation and analytics domains, however, data movement increasingly dominates the performance, energy usage, and price of computing systems. It is therefore plausible that we could find a more synergistic technology path forward. Even though future machines may continue to be configured differently for the two domains, a more common technological roadmap between them in the form of a degree of convergence in the underlying componentry and design principles to address these common technical challenges could have substantial technical and economic benefits.

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TYPE SAND Report YEAR 2014
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Homo- and heterometallic luminescent 2-D stilbene metal-organic frameworks

Dalton Transactions

Bauer, Christina A.; Jones, Simon C.; Kinnibrugh, Tiffany L.; Tongwa, Paul; Farrell, Richard A.; Vakil, Avinash; Timofeeva, Tatiana V.; Khrustalev, Victor N.; Allendorf, Mark D.

Metal-organic frameworks (MOFs) can provide a matrix for the assembly of organic chromophores into well-defined geometries, allowing for tuning of the material properties and study of structure-property relationships. Here, we report on the effect of the coordinated metal ion on the luminescence properties of eight isostructural MOFs having the formula M12M 2L3(DMF)2 (M1 = M2 = Zn (1), Cd (2), Mn (3), Co (4); M1 = Zn, M2 = Cd (5), Mn (6), Co (7); M1 = Co, M2 = Mn (8); L = trans-4,4′- stilbene dicarboxylate), synthesized by reaction of the appropriate metal nitrate or mixtures of metal nitrates with LH2 in DMF. The crystal structures of 2, 3 and 5-8 were determined by X-ray diffraction to be composed of trinuclear metal clusters linked by stilbene dicarboxylate linkers in a paddlewheel geometry, extending to form a 2-D layered structure. In the mixed-metal cases, the larger metal ion was found to occupy the octahedral site in the cluster while the smaller ion occupies the tetrahedral positions, suggesting a selective, ligand-directed assembly process for the mixed-metal species. Variable temperature magnetic measurements for paramagnetic MOFs 3 and 6-8 were consistent with the site occupancies determined crystallographically, and indicated weak intra-cluster antiferromagnetic coupling for 3 and 8. Comparison between the crystal structures of 2, 3 and 5-8 and those reported for 1 and 4 in the literature reveal close resemblances between linker environments, with important intermolecular stilbene-stilbene geometries that are comparable in all cases. Interestingly, pale-colored 1-3 and 5-7 display very similar emission profiles upon excitation at λex = 350 nm, whereas dark-colored 4 and 8 do not exhibit detectable emission spectra. The bright, well-resolved luminescence of 1, 2 and 5 is ascribed to rigidification of the linker upon coordination to the d10 metal ions, whereas the weaker emission observed for 3, 6 and 7 is presumably a result of quenching due to close proximity of the linker to one or more paramagnetic ions. Time-resolved measurements for 1, 2, 5 and 6 reveal biexponential emission decays, where the lifetime of the longer-lived state corresponds to observed variations in the nearest-neighbor cofacial stilbene-stilbene distances in their crystal structures. For 3, a monoexponential decay with shorter lifetime was determined, indicating significant paramagnetic quenching of its emissive state. © 2014 The Royal Society of Chemistry.

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TYPE Journal Article YEAR 2014
ScopusOSTI

S&S-PRG-036 – Security Connection

Terry, Stefanie F.

In order to provide Members of the Workforce with timely, accurate, and consistent responses to security-related questions and concerns, the Security and Emergency Management (S&EM) Center developed Security Connection, a customer-interfacing, single entry point resource center. Security Connection is manned by Security Connection Representatives (SCR) who process incoming questions via multiple sources, including phone and e-mail. In addition, SCRs also provide call volume relief to various Security programs and assume responsibility for answering program questions for line customers. In this manner, Security Connection adds value to both line customers and Security programs.

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TYPE SAND Report YEAR 2014
DOIOSTI

The effect of surface charge regulation on conductivity in fluidic nanochannels

Journal of Colloid and Interface Science

Fleharty, Mark E.; van Swol, Frank; Petsev, Dimiter N.

The precise electrostatic potential distribution is very important for the electrokinetic transport in fluidic channels. This is especially valid for small nanochannels where the electric double layers formed at the walls are comparable to the channel width. It can be expected that due to the large surface to volume ratio in such systems, they will exhibit properties that are not detectable in larger channels, capillaries and pores. We present a detailed numerical analysis of the current transport in fluidic nanochannels. It is based on solving the Poisson-Boltzmann equation with charge regulation boundary conditions that account for the surface-aqueous solution chemical equilibria. The focus is on studying the effect of the pH on the current transport. The pH is varied by adding either HCl or KOH. The analysis predicts non-monotonous and sometimes counterintuitive dependence of the conductivity on the pH. The channel conductivity exhibits practically no change over a range of pH values due to a buffering exerted by the chemical groups at the walls. An unexpected drop of the conductivity is observed around the wall isoelectric point and also in the vicinity of pH. = 7 even though the concentration of ions in the channel increases. These observations are explained in the framework of charge regulation theory. © 2013 Elsevier Inc.

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TYPE Journal Article YEAR 2014
ScopusOSTI

Effect of adverse pressure gradient on high speed boundary layer transition

Physics of Fluids

Franko, Kenneth J.; Lele, Sanjiva

The effect of adverse pressure gradients (APG) on boundary layer stability, breakdown, and heat-transfer overshoot is investigated. Flat plate isothermal boundary layers initially at Mach 6 with APG imposed through the freestream boundary condition are simulated using suction and blowing to produce boundary layer instabilities. The three different transition mechanisms compared are first mode oblique breakdown, second mode oblique breakdown, and second mode fundamental resonance. For all of the transition mechanisms, an adverse pressure gradient increases the linear growth rates and quickens the transition to turbulence. However, the nonlinear breakdown for all three transitionmechanisms is qualitatively the same as for a zero pressure gradient boundary layer. First mode oblique breakdown leads to the earliest transition location and an overshoot in heat transfer in the transitional region. Both types of Mack second mode forcing lead to a transitional boundary layer but even with the increased growth rates and N factors produced by the adverse pressure gradient, the breakdown process is still more gradual than first mode oblique breakdown because the primary Mack second mode instabilities saturate and produce streaks that breakdown further downstream. © 2014 AIP Publishing LLC.

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TYPE Journal Article YEAR 2014
ScopusOSTIDOI

Molecular simulation of carbon dioxide, brine, and clay mineral interactions and determination of contact angles

Environmental Science and Technology

Tenney, Craig M.; Cygan, Randall T.

Capture and subsequent geologic storage of CO2 in deep brine reservoirs plays a significant role in plans to reduce atmospheric carbon emission and resulting global climate change. The interaction of CO2 and brine species with mineral surfaces controls the ultimate fate of injected CO2 at the nanoscale via geochemistry, at the pore-scale via capillary trapping, and at the field-scale via relative permeability. We used large-scale molecular dynamics simulations to study the behavior of supercritical CO2 and aqueous fluids on both the hydrophilic and hydrophobic basal surfaces of kaolinite, a common clay mineral. In the presence of a bulk aqueous phase, supercritical CO2 forms a nonwetting droplet above the hydrophilic surface of kaolinite. This CO2 droplet is separated from the mineral surface by distinct layers of water, which prevent the CO2 droplet from interacting directly with the mineral surface. Conversely, both CO2 and H2O molecules interact directly with the hydrophobic surface of kaolinite. In the presence of bulk supercritical CO2, nonwetting aqueous droplets interact with the hydrophobic surface of kaolinite via a mixture of adsorbed CO2 and H2O molecules. Because nucleation and precipitation of minerals should depend strongly on the local distribution of CO2, H2O, and ion species, these nanoscale surface interactions are expected to influence long-term mineralization of injected carbon dioxide. © 2014 American Chemical Society.

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TYPE Journal Article YEAR 2014
ScopusOSTI

Nuclear Fuel Cycle System Simulation Tool Based on High-Fidelity Component Modeling

Ames, David E.

The DOE is currently directing extensive research into developing fuel cycle technologies that will enable the safe, secure, economic, and sustainable expansion of nuclear energy. The task is formidable considering the numerous fuel cycle options, the large dynamic systems that each represent, and the necessity to accurately predict their behavior. The path to successfully develop and implement an advanced fuel cycle is highly dependent on the modeling capabilities and simulation tools available for performing useful relevant analysis to assist stakeholders in decision making. Therefore a high-fidelity fuel cycle simulation tool that performs system analysis, including uncertainty quantification and optimization was developed. The resulting simulator also includes the capability to calculate environmental impact measures for individual components and the system. An integrated system method and analysis approach that provides consistent and comprehensive evaluations of advanced fuel cycles was developed. A general approach was utilized allowing for the system to be modified in order to provide analysis for other systems with similar attributes. By utilizing this approach, the framework for simulating many different fuel cycle options is provided. Two example fuel cycle configurations were developed to take advantage of used fuel recycling and transmutation capabilities in waste management scenarios leading to minimized waste inventories.

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TYPE SAND Report YEAR 2014
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The Energy Frontier Research Center for Solid-State Lighting Science: Exploring New Materials Architectures and Light Emission Phenomena

Journal of Physical Chemistry C

Coltrin, Michael E.; Subramania, Ganapathi S.; Tsao, Jeffrey Y.; Wang, George T.; Wierer, Jonathan J.; Wright, Jeremy B.; Armstrong, Andrew A.; Brener, Igal; Chow, Weng W.; Crawford, Mary H.; Fischer, Arthur J.; Koleske, Daniel; Martin, James E.; Rohwer, Lauren E.S.

Abstract not provided.

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TYPE Journal Article YEAR 2014
OSTIDOI
Results 54001–54100 of 99,299
Results 54001–54100 of 99,299